U.S. patent application number 10/108047 was filed with the patent office on 2002-10-03 for synchronous induction motor and manufacturing method and drive unit for the same, and hermetic electric compressor.
This patent application is currently assigned to SANYO ELECTRIC CO., LTD.. Invention is credited to Arai, Kazuhiko, Enomoto, Kazuhiro, Igarashi, Keijiro, Koiso, Shigemi, Murata, Eiichi, Nakayama, Yoshitomo, Onodera, Noboru, Takezawa, Masaaki, Yanashima, Toshihito.
Application Number | 20020140309 10/108047 |
Document ID | / |
Family ID | 27567031 |
Filed Date | 2002-10-03 |
United States Patent
Application |
20020140309 |
Kind Code |
A1 |
Yanashima, Toshihito ; et
al. |
October 3, 2002 |
Synchronous induction motor and manufacturing method and drive unit
for the same, and hermetic electric compressor
Abstract
A synchronous induction motor features improved assemblability
of a rotor, significantly reduced production cost, and improved
operation performance of the motor. A plurality of die-cast
secondary conductors is provided around a rotor yoke constituting
the rotor of the synchronous induction motor. End rings are
die-cast integrally with the secondary conductors on the peripheral
portions of both end surfaces of the rotor yoke. Permanent magnets
are inserted into slots formed such that they penetrate the rotor
yoke. The openings of both ends of the slots are closed by a pair
of end surface members formed of a non-magnetic constituent. One of
the end surface members is secured to the rotor yoke by one of the
end rings when the secondary conductors and the end rings are
formed. The other end surface member is secured to the rotor yoke
by a fixture.
Inventors: |
Yanashima, Toshihito;
(Ota-shi, JP) ; Igarashi, Keijiro; (Ota-shi,
JP) ; Takezawa, Masaaki; (Nitta-gun, JP) ;
Arai, Kazuhiko; (Nitta-gun, JP) ; Murata, Eiichi;
(Isesaki-shi, JP) ; Onodera, Noboru; (Ora-gun,
JP) ; Koiso, Shigemi; (Ota-shi, JP) ; Enomoto,
Kazuhiro; (Osato-gun, JP) ; Nakayama, Yoshitomo;
(Ota-shi, JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN & HATTORI, LLP
1725 K STREET, NW.
SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
SANYO ELECTRIC CO., LTD.
Moriguchi-shi
JP
|
Family ID: |
27567031 |
Appl. No.: |
10/108047 |
Filed: |
March 28, 2002 |
Current U.S.
Class: |
310/162 |
Current CPC
Class: |
F04B 2203/0205 20130101;
H02K 21/46 20130101; H02K 1/2766 20130101; F04B 35/04 20130101;
F04B 49/10 20130101; F04C 2270/07 20130101; H02K 1/276 20130101;
F04C 2270/19 20130101; F04C 28/28 20130101; H02K 7/04 20130101;
H02P 1/445 20130101; F04C 23/008 20130101 |
Class at
Publication: |
310/162 |
International
Class: |
H02K 019/00; H02K
021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2001 |
JP |
2001-99883 |
Mar 30, 2001 |
JP |
2001-99938 |
Mar 30, 2001 |
JP |
2001-100033 |
Mar 30, 2001 |
JP |
2001-100129 |
Mar 30, 2001 |
JP |
2001-100198 |
Mar 30, 2001 |
JP |
2001-100263 |
May 30, 2001 |
JP |
2001-161521 |
Claims
What is claimed is:
1. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor rotating in the stator; a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting; end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting; a permanent magnet inserted in
a slot formed such that it penetrates the rotor yoke; and a pair of
end surface members which is formed of a non-magnetic material and
which closes the openings of both ends of the slot, wherein one of
the end surface members is secured to the rotor yoke by one of the
end rings when the secondary conductors and end rings are formed,
and the other end surface member is secured to the rotor yoke by a
fixture.
2. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor rotating in the stator; a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting; end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting; a permanent magnet inserted in
a slot formed such that it penetrates the rotor yoke; and a pair of
end surface members which formed of a non-magnetic material and
which closes the openings of both ends of the slot, wherein
non-magnetic members are disposed in contact with the inner sides
of the two end rings to secure the two end surface members by
pressing them against the rotor yoke by the non-magnetic
members.
3. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor rotating in the stator; a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting; end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting; a permanent magnet inserted in
a slot formed such that it penetrates the rotor yoke; and a pair of
end surface members which is formed of a non-magnetic material and
which closes the openings of both ends of the slot, wherein a
balancer formed into a predetermined shape beforehand is secured by
a fixture to the rotor yoke together with the end surface
member.
4. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor rotating in the stator; a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting; end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting; a permanent magnet inserted in
a slot formed such that it penetrates the rotor yoke; and a pair of
end surface members which is formed of a non-magnetic material and
which closes the openings of both ends of the slot, wherein a
plurality of laminated sheet balancers is secured by a fixture to
the rotor yoke together with the end surface member.
5. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor rotating in the stator; a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting; end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting; a permanent magnet inserted in
a slot formed such that it penetrates the rotor yoke; and a pair of
end surface members which is formed of a non-magnetic material and
which closes the openings of both ends of the slot, wherein at
least one of the end surface members and a balancer are formed into
one piece.
6. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor rotating in the stator; a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting; end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting; a permanent magnet inserted in
a slot formed such that it penetrates the rotor yoke; a pair of end
surface members which is formed of a non-magnetic material and
which closes the openings of both ends of the slots; and a balancer
secured by being press-fitted to the inner side of at least one of
the end rings.
7. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor rotating in the stator; a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting; end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting; a permanent magnet inserted in
a slot formed such that it penetrates the rotor yoke; and a pair of
end surface members which is formed of a non-magnetic material and
which closes the openings of both ends of the slot in which the
permanent magnet has been inserted, wherein the two end surface
members are secured to the rotor yoke by the two end rings when the
secondary conductors and the end rings are formed.
8. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor which is secured to a rotating shaft and
which rotates in the stator; a secondary conductor provided around
the rotor yoke constituting the rotor; and a permanent magnet
embedded in the rotor yoke, wherein a magnetic field produced by
the permanent magnet does not pass through the rotating shaft.
9. A synchronous induction motor comprising: a stator equipped with
a stator winding; a rotor which is secured to a rotating shaft and
which rotates in the stator; a secondary conductor provided around
the rotor yoke constituting the rotor; and a permanent magnet
embedded in the rotor yoke, wherein a magnetic field produced by
the permanent magnet bypasses the rotating shaft.
10. A synchronous induction motor comprising: a stator equipped
with a stator winding; a rotor which is secured to a rotating shaft
and which rotates in the stator; a secondary conductor provided
around the rotor yoke constituting the rotor; and a permanent
magnet embedded in the rotor yoke, wherein a magnetic field
produced by the permanent magnet passes through only the rotor
yoke, excluding the rotating shaft.
11. The synchronous induction motor according to claim 8, claim 9,
or claim 10, wherein a void is formed in the rotor yoke between the
permanent magnet and the rotating shaft.
12. The synchronous induction motor according to claim 8, claim 9,
claim 10, or claim 11, wherein a pair of the permanent magnets is
disposed, sandwiching the rotating shaft therebetween, and
permanent magnets for attracting the magnetic field produced by the
paired permanent magnets are further disposed at both ends of a
line that passes the paired permanent magnets and the rotating
shaft.
13. The synchronous induction motor according to claim 8, claim 9,
claim 10, or claim 11, wherein the permanent magnets are provided
at both ends of a line that connects two magnetic poles, and the
permanent magnets are radially disposed substantially about the
rotating shaft.
14. A synchronous induction motor comprising: a stator equipped
with a stator winding; a rotor rotating in the stator; a secondary
conductor provided around the rotor yoke constituting the rotor;
and a permanent magnet embedded in the rotor yoke, wherein the
permanent magnet is magnetized by current passed through the stator
winding.
15. The synchronous induction motor according to claim 14, wherein
the permanent magnet is made of a rare earth type magnet or a
ferrite magnet.
16. The synchronous induction motor according to claim 14 or claim
15, wherein the stator winding is of a single-phase configuration
and has a primary winding and an auxiliary winding, and the
permanent magnet is magnetized by the current passed through either
the primary winding or the auxiliary winding.
17. The synchronous induction motor according to claim 14 or claim
15, wherein the stator winding is of a three-phase configuration
that includes a three-phase winding, and the permanent magnet is
magnetized by current passed through a single phase, two phases, or
three phases of the stator windings.
18. The synchronous induction motor according to claim 14, claim
15, claim 16, or claim 17, wherein the stator winding is coated
with varnish or a sticking agent that is heated to fuse the
winding.
19. The synchronous induction motor according to claim 1, claim 2,
claim 3, claim 4, claim 5, claim 6, claim 7, claim 8, claim 9,
claim 10, claim 11, claim 12, claim 13, claim 14, claim 15, claim
16, claim 17, or claim 18, which is installed in a compressor.
20. The synchronous induction motor according to claim 19, wherein
the compressor is used with an air conditioner or an electric
refrigerator or the like.
21. A manufacturing method for a synchronous induction motor that
has a stator equipped with a stator winding, a rotor rotating in
the stator, a secondary conductor provided around a rotor yoke
constituting the rotor, and a permanent magnet embedded in the
rotor yoke, the manufacturing method comprising: a step for
embedding a magnet constituent for the permanent magnet in the
rotor yoke; and a step for passing current through the stator
winding to magnetize the magnet constituent.
22. The manufacturing method for the synchronous induction motor
according to claim 21, wherein a rare earth type or ferrite
material is used for the magnet constituent.
23. The manufacturing method for the synchronous induction motor
according to claim 21 or claim 22, wherein the stator winding is of
a single-phase configuration and has a primary winding an auxiliary
winding, and the permanent magnet is magnetized by the current
passed through either the primary winding or the auxiliary
winding.
24. The manufacturing method for the synchronous induction motor
according to claim 21 or claim 22, wherein the stator winding is of
a three-phase configuration that includes a three-phase winding,
and the permanent magnet is magnetized by current passed through a
single phase, two phases, or three phases of the stator
windings.
25. The manufacturing method for the synchronous induction motor
according to claim 21, claim 22, claim 23, or claim 24, wherein the
stator winding is coated with varnish or a sticking agent that is
heated to fuse the windings.
26. In a synchronous induction motor comprising: a stator equipped
with a stator winding constructed of a primary winding and an
auxiliary winding; a rotor rotating in the stator; a secondary
conductor provided around a rotor yoke constituting the rotor; and
a permanent magnet embedded in the rotor yoke, a drive unit for the
synchronous induction motor, comprising: an operating capacitor
connected to the auxiliary winding; and a series circuit of a
start-up capacitor and a PTC, which is connected in parallel to the
operating capacitor.
27. In a synchronous induction motor comprising: a stator equipped
with a stator winding formed of a primary winding and an auxiliary
winding; a rotor rotating in the stator; a secondary conductor
provided around a rotor yoke constituting the rotor; and a
permanent magnet embedded in the rotor yoke, a drive unit for the
synchronous induction motor, comprising: an operating capacitor
connected to the auxiliary winding; and a PTC connected in parallel
to the operating capacitor.
28. In a synchronous induction motor comprising: a stator equipped
with a stator winding formed of a primary winding and an auxiliary
winding; a rotor rotating in the stator; a secondary conductor
provided around a rotor yoke constituting the rotor; and a
permanent magnet embedded in the rotor yoke, a drive unit for the
synchronous induction motor, comprising: an operating capacitor
connected to the auxiliary winding; and a series circuit of a
start-up capacitor and a start-up relay contact, which is connected
in parallel to the operating capacitor.
29. In a synchronous induction motor comprising: a stator equipped
with a stator winding formed of a primary winding and an auxiliary
winding; a rotor rotating in the stator; a secondary conductor
provided around a rotor yoke constituting the rotor; and a
permanent magnet embedded in the rotor yoke, a drive unit for the
synchronous induction motor, comprising: an operating capacitor
connected to the auxiliary winding.
30. A hermetic electric compressor comprising a compression unit
and an electric unit for driving the compression unit in a hermetic
vessel, wherein the electric unit is secured to the hermetic vessel
and constituted by a stator equipped with a stator winding and a
rotor rotating in the stator, the rotor comprises a secondary
conductor provided around a rotor yoke and a permanent magnet
embedded in the rotor yoke, and a thermal protecting means for
cutting off the supply of current to the electric unit in response
to a predetermined temperature rise is provided in the hermetic
vessel.
31. The hermetic electric compressor according to claim 30, wherein
the thermal protecting means is installed on the stator
winding.
32. A hermetic electric compressor comprising a compression unit
and an electric unit for driving the compression unit in a hermetic
vessel, wherein the electric unit is secured to the hermetic vessel
and constituted by a stator equipped with a stator winding and a
rotor rotating in the stator, the rotor comprises a secondary
conductor provided around a rotor yoke and a permanent magnet
embedded in the rotor yoke, and a thermal protecting means for
cutting off the supply of current to the electric unit in response
to a predetermined temperature rise is provided on the outer
surface of the hermetic vessel.
33. The hermetic electric compressor according to claim 30, claim
31, or claim 32, wherein the thermal protecting means is
constructed of a thermistor whose resistance value varies with
temperature and a controller that controls the supply of current to
the electric unit according to a change in the resistance value of
the thermistor.
34. The hermetic electric compressor according to claim 30, claim
31, or claim 32, wherein the thermal protecting means is
constructed of a bimetal switch.
35. The hermetic electric compressor according to claim 30, claim
31, or claim 32, wherein the thermal protecting means is
constructed of a thermostat that opens/closes a contact according
to temperature.
36. A hermetic electric compressor comprising a compression unit
and an electric unit for driving the compression unit in a hermetic
vessel, wherein the electric unit is secured to the hermetic vessel
and constituted by a stator equipped with a stator winding and a
rotor rotating in the stator, the rotor comprises a secondary
conductor provided around a rotor yoke and a permanent magnet
embedded in the rotor yoke, and a thermal protecting means for
cutting off the supply of current to the electric unit at a
predetermined overload current is provided.
37. The hermetic electric compressor according to claim 36, wherein
the overload protecting means is constituted by an overload
switch.
38. The hermetic electric compressor according to claim 36, wherein
the overload protecting means is constituted by a current
transformer for detecting the current supplied to the electric unit
and a controller for controlling the supply of current to the
electric unit on the basis of an output of the current
transformer.
39. The hermetic electric compressor according to claim 33 or claim
38, wherein the controller cuts off the supply of current to the
electric unit after a predetermined time elapses since a
temperature or current exceeded a predetermined value.
40. The hermetic electric compressor according to claim 39, wherein
the controller restarts the supply of current to the electric unit
after waiting for the elapse of a predetermined delay time since
the supply of current to the electric unit was cut off.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a synchronous induction
motor constituted by a plurality of secondary conductors provided
on the peripheral portion of a rotor yoke, an end ring which is
positioned on the peripheral portions of both end surfaces of the
rotor yoke and which is integrally formed with the secondary
conductors by die casting, and a permanent magnet embedded in the
rotor yoke.
[0003] 2. Description of the Related Art
[0004] Conventionally, an air conditioner or a refrigerator, for
example, incorporates a hermetic electric compressor for the
refrigerating cycle of a cooling unit of the air conditioner or the
refrigerator. As an electric constituent for driving the
compressor, an induction motor, a DC brushless motor, or a
synchronous induction motor driven by a single-phase or three-phase
commercial power supply has been used.
[0005] The rotor of the synchronous induction motor is constituted
by a stator having stator windings and a rotor rotating in the
stator. A plurality of secondary conductors positioned around a
rotor yoke that makes up the rotor are die-cast. Furthermore, end
rings are integrally formed with the secondary conductors by
die-casting onto the peripheral portions of both end surfaces of
the rotor yoke. Slots are formed through the rotor yoke, permanent
magnets are inserted in the slots, and the openings at both ends of
the slots are respectively secured by end surface members.
[0006] The permanent magnets to be provided in the rotor are
inserted in the slots formed in the rotor yoke, then secured by
fixing members. Furthermore, in order to ensure good rotational
balance of the rotor, balancers are installed in the vicinity of
the end rings positioned on the peripheral portions of the end
surfaces of the rotor yoke. In this case, after forming the end
rings by die casting, the end surface members for fixing the
permanent magnets in the slots and the balancers are separately
installed. This has been posing a problem in that the assembling
efficiency of the synchronous induction motor is considerably
deteriorated.
[0007] Furthermore, in order to secure the space for the slots for
fixing the permanent magnets in the rotor, the end rings have to be
made small. This inevitably leads to small sectional areas of the
end rings. As a result, the heat generated by the rotor during
operation increases, leading to a problem in that running
performance is degraded due to degraded magnetic forces of the
magnets, and, if rare earth type magnets are used for the permanent
magnets, then significant demagnetization occurs.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention has been made with a view
toward solving the problems with the prior art described above, and
it is an object of the present invention to provide a synchronous
induction motor that features improved assemblability of a rotor of
a synchronous induction motor and improved running performance.
[0009] According to one aspect of the present invention, there is
provided a synchronous induction motor having a stator equipped
with a stator winding, a rotor rotating in the stator, a plurality
of secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting, end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting, permanent magnets inserted in
slots formed such that they penetrate the rotor yoke, and a pair of
end surface members formed of a non-magnetic material that closes
the openings of both ends of the slots, wherein one of the end
surface members is secured to the rotor yoke by one of the end
rings when the secondary conductors and end rings are formed, and
the other end surface member is secured to the rotor yoke by a
fixture. Therefore, one of the end surface members can be secured
to the rotor yoke at the same time when the secondary conductors
and the end rings are die-cast.
[0010] With this arrangement, after the permanent magnets are
inserted into the slots, the permanent magnets can be secured to
the rotor merely by securing the other end surface member to the
rotor yoke by a fixture. It is therefore possible to reduce the
number of steps for installing the permanent magnets with resultant
improved assemblability, permitting the overall productivity of
synchronous induction motors to be dramatically improved.
[0011] According to another aspect of the present invention, there
is provided a synchronous induction motor having a stator equipped
with a stator winding, a rotor rotating in the stator, a plurality
of secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting, end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting, permanent magnets inserted in
slots formed such that they penetrate the rotor yoke, and a pair of
end surface members formed of a non-magnetic material that closes
the openings of both ends of the slots, wherein a non-magnetic
member is disposed in contact with the inner sides of the two end
rings to secure the two end surface members by pressing them
against the rotor yoke by the non-magnetic member. It is therefore
possible to increase the sectional areas of the end rings by the
amount provided by pressing the end surface members against the
non-magnetic member.
[0012] With this arrangement, the loss of the rotor can be
decreased by the amount equivalent to the increased portion of the
sectional areas of the end rings. This allows the amount of
generated heat of the rotor to be reduced, making it possible to
significantly improve the running performance of the synchronous
induction motor.
[0013] According to yet another aspect of the present invention,
there is provided a synchronous induction motor having a stator
equipped with a stator winding, a rotor rotating in the stator, a
plurality of secondary conductors which is positioned around a
rotor yoke constituting the rotor and which is formed by die
casting, end rings which are positioned on the peripheral portions
of both end surfaces of the rotor yoke and which are integrally
formed with the secondary conductors by die casting, permanent
magnets inserted in slots formed such that they penetrate the rotor
yoke, and a pair of end surface members formed of a non-magnetic
material that closes the openings of both ends of the slots,
wherein a balancer formed into a predetermined shape beforehand is
secured by a fixture to the rotor yoke together with the end
surface member. Therefore, the ease of installation of the balancer
can be considerably improved.
[0014] With this arrangement, it is no longer necessary to secure
the permanent magnets and the balancer separately, with consequent
greater ease of installation. This permits dramatically improved
productivity of the synchronous induction motor.
[0015] According to still another aspect of the present invention,
there is provided a synchronous induction motor having a stator
equipped with a stator winding, a rotor rotating in the stator, a
plurality of secondary conductors which is positioned around a
rotor yoke constituting the rotor and which is formed by die
casting, end rings which are positioned on the peripheral portions
of both end surfaces of the rotor yoke and which are integrally
formed with the secondary conductors by die casting, permanent
magnets inserted in slots formed such that they penetrate the rotor
yoke, and a pair of end surface members formed of a non-magnetic
material that closes the openings of both ends of the slots,
wherein a plurality of laminated sheet balancers is secured by a
fixture to the rotor yoke together with the end surface member.
Therefore, the ease of installation of the balancer is improved,
permitting dramatically improved productivity to be achieved.
[0016] Furthermore, since a plurality of sheet balancers is
laminated, using inexpensive metal sheets for the balancer allows a
considerable reduction in the cost of the balancer. This leads to a
dramatically reduced production cost of the synchronous induction
motor.
[0017] According to a further aspect of the present invention,
there is provided a synchronous induction motor having a stator
equipped with a stator winding, a rotor rotating in the stator, a
plurality of secondary conductors which is positioned around a
rotor yoke constituting the rotor and which is formed by die
casting, end rings which are positioned on the peripheral portions
of both end surfaces of the rotor yoke and which are integrally
formed with the secondary conductors by die casting, permanent
magnets inserted in slots formed such that they penetrate the rotor
yoke, and a pair of end surface members formed of a non-magnetic
material that closes the openings of both ends of the slots,
wherein at least one of the end surface members and a balancer are
formed into one piece. Hence, the number of components can be
reduced. This permits simpler installation of the end surface
members, resulting in dramatically improved productivity.
[0018] According to another aspect of the present invention, there
is provided a synchronous induction motor having a stator equipped
with a stator winding, a rotor rotating in the stator, a plurality
of secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting, end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting, permanent magnets inserted in
slots formed such that they penetrate the rotor yoke, a pair of end
surface members formed of a non-magnetic material that closes the
openings of both ends of the slots, and a balancer secured by being
press-fitted to the inner side of at least one of the end rings.
Hence, the installation of the balancer can be simplified. This
arrangement makes it possible to significantly improve the
productivity of the synchronous induction motor.
[0019] According to another aspect of the present invention, there
is provided a synchronous induction motor having a stator equipped
with a stator winding, a rotor rotating in the stator, a plurality
of secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting, end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting, permanent magnets inserted in
slots formed such that they penetrate the rotor yoke, and a pair of
end surface members formed of a non-magnetic material that closes
the openings of both ends of the slots in which the permanent
magnets have been inserted, wherein the two end surface members are
secured to the rotor yoke by the two end rings when the secondary
conductors and the end rings are formed. This arrangement makes it
possible to obviate the need of, for example, the cumbersome step
for inserting the permanent magnets into the slots, then attaching
the end surface members to both ends of the rotor yoke after
die-casting the end rings, as in the case of a prior art. Thus, the
productivity of the rotor can be dramatically improved.
[0020] According to a further aspect of the present invention,
there is provided a synchronous induction motor having a stator
equipped with a stator winding, a rotor which is secured to a
rotating shaft and which rotates in the stator, a secondary
conductor provided around the rotor yoke constituting the rotor,
and a permanent magnet embedded in the rotor yoke, wherein a
magnetic field produced by the permanent magnet does not pass
through the rotating shaft. Thus, it is possible to prevent the
rotating shaft from being magnetized. This arrangement makes it
possible to prevent iron powder or the like from adhering to the
rotating shaft and to protect the rotating shaft and a bearing from
being worn due to the friction attributable to the magnetic force
of the permanent magnet. This permits secure prevention of damage
to the motor caused by the friction.
[0021] According to a further aspect of the present invention,
there is provided a synchronous induction motor having a stator
equipped with a stator winding, a rotor which is secured to a
rotating shaft and which rotates in the stator, a secondary
conductor provided around the rotor yoke constituting the rotor,
and a permanent magnet embedded in the rotor yoke, wherein a
magnetic field produced by the permanent magnet bypasses the
rotating shaft. Thus, it is possible to prevent the rotating shaft
from being magnetized. This arrangement makes it possible to
prevent iron powder or the like from adhering to the rotating shaft
and to protect the rotating shaft and a bearing from being worn due
to the friction attributable to the magnetic force of the permanent
magnet. This permits secure prevention of damage to the motor
caused by the friction.
[0022] According to another aspect of the present invention, there
is provided a synchronous induction motor having a stator equipped
with a stator winding, a rotor which is secured to a rotating shaft
and which rotates in the stator, a secondary conductor provided
around the rotor yoke constituting the rotor, and a permanent
magnet embedded in the rotor yoke, wherein a magnetic field
produced by the permanent magnet passes through only the rotor
yoke, excluding the rotating shaft. Thus, it is possible to prevent
the rotating shaft from being magnetized. This arrangement makes it
possible to prevent iron powder or the like from adhering to the
rotating shaft and to protect the rotating shaft and a bearing from
being worn due to the friction attributable to the magnetic force
of the permanent magnet. This permits secure prevention of damage
to the motor caused by the friction.
[0023] In a preferred form of the synchronous induction motor in
accordance with the present invention, a void is formed in the
rotor yoke between the permanent magnet and the rotating shaft, so
that the passage of the magnetic field produced by the permanent
magnet can be reduced. Thus, it is possible to prevent the rotating
shaft from being magnetized. This arrangement makes it possible to
prevent iron powder or the like from adhering to the rotating shaft
and to protect the rotating shaft and a bearing from being worn due
to the friction attributable to the magnetic force of the permanent
magnet. This permits secure prevention of damage to the motor
caused by the friction.
[0024] In another preferred form of the synchronous induction motor
in accordance with the present invention, a pair of the permanent
magnets is disposed with the rotating shaft therebetween, and
permanent magnets for attracting the magnetic field produced by the
paired permanent magnets are disposed at both ends of a line that
passes the paired permanent magnets and the rotating shaft. It is
therefore possible to prevent the magnetic field produced by the
paired permanent magnets from passing through the rotating shaft.
Thus, it is possible to prevent the rotating shaft from being
magnetized. This arrangement makes it possible to prevent iron
powder or the like from adhering to the rotating shaft and to
protect the rotating shaft and a bearing from being worn due to the
friction attributable to the magnetic force of the permanent
magnet. This permits secure prevention of damage to the motor
caused by the friction.
[0025] In yet another preferred form of the synchronous induction
motor in accordance with the present invention, the permanent
magnets are provided at both ends of a line that connects two
magnetic poles, and the permanent magnets are radially disposed
substantially about the rotating shaft. Hence, the magnetic field
produced by the permanent magnets can be spaced away from the
rotating shaft. Thus, it is possible to prevent the rotating shaft
from being magnetized. This arrangement makes it possible to
prevent iron powder or the like from adhering to the rotating shaft
and to protect the rotating shaft and a bearing from being worn due
to the friction attributable to the magnetic force of the permanent
magnet. This permits secure prevention of wear on the rotor caused
by the friction.
[0026] According to another aspect of the present invention, there
is provided a synchronous induction motor having a stator equipped
with a stator winding, a rotor rotating in the stator, a secondary
conductor provided around the rotor yoke constituting the rotor,
and a permanent magnet embedded in the rotor yoke, wherein the
permanent magnet is magnetized by current passed through the stator
winding. Hence, for example, a rotor in which a magnetic material
for the permanent magnet that has not yet been magnetized has been
inserted is installed in the stator, so that the rotor can be
inserted into the stator without being magnetically attracted to
its surrounding. This arrangement makes it possible to prevent
inconvenience of lower productivity of the synchronous induction
motor, thus permitting improved assemblability of the synchronous
induction motor. This allows a synchronous induction motor with
high reliability to be provided.
[0027] In a preferred form of the synchronous induction motor in
accordance with the present invention, the permanent magnet is made
of a rare earth type magnet or a ferrite magnet, so that high
magnet characteristic can be achieved. With this arrangement, the
magnitude of the current passed through the stator winding can be
reduced so as to control the temperature at the time of
magnetization to a minimum. Hence, the deformation of the rotor or
the stator or the like that would be caused by high temperature can
be minimized, making it possible to provide a synchronous induction
motor with secured high quality.
[0028] Especially in the case of a synchronous induction motor,
current passes through the secondary conductor even during normal
synchronous operation, causing the temperature of the entire rotor
to rise. Therefore, the demagnetization at high temperature can be
restrained by using, for example, a ferrite magnet or a rare earth
type magnet (the coercive force at normal temperature being 1350 to
2150 kA/m and the coercive force temperature coefficient being
-0.7%/.degree. C. or less).
[0029] In a preferred form of the synchronous induction motor in
accordance with the present invention, the stator winding is of a
single-phase configuration and has a primary winding and an
auxiliary winding, and the permanent magnet is magnetized by the
current passed through either the primary winding or the auxiliary
winding. Hence, it is possible to achieve better magnetizing
performance than, for example, in the case where current is passed
through both the primary winding and the auxiliary winding at the
same time. This allows an unmagnetized magnet material to be
intensely magnetized.
[0030] In a preferred form of the synchronous induction motor in
accordance with the present invention, the stator winding is of a
three-phase configuration that includes a three-phase winding. The
permanent magnet is magnetized by current passed through a single
phase, two phases, or three phases of the stator windings.
Therefore, it is possible to select the phase or phases through
which current is to be passed according to the disposition of the
magnet or the permissible current (against deformation or the like)
of the windings.
[0031] In yet another preferred form of the synchronous induction
motor in accordance with the present invention, the stator windings
are coated with varnish or a sticking agent that is heated to fuse
the windings. Hence, for example, even if the stator windings
generate heat and become hot when an unmagnetized magnet material
inserted into the rotor is magnetized by passing current through
the stator windings, it is possible to restrain the deformation of
winding ends of the stator windings and the deterioration of
winding films caused by the heat. Thus, since the winding ends of
the stator windings do not deform even if an unmagnetized magnet
material inserted into the rotor is magnetized, a highly reliable
synchronous induction motor can be provided.
[0032] Furthermore, the synchronous induction motor in accordance
with the present invention is installed in a compressor, allowing
the production cost of the compressor to be considerably
reduced.
[0033] Moreover, the compressor incorporating the synchronous
induction motor in accordance with the present invention is used
with an air conditioner or an electric refrigerator or the like.
Hence, the production cost of the air conditioner or the electric
refrigerator can be significantly decreased.
[0034] According to another aspect of the present invention, there
is provided a manufacturing method for a synchronous induction
motor having a stator equipped with a stator winding, a rotor
rotating in the stator, a secondary conductor provided around a
rotor yoke constituting the rotor, and a permanent magnet embedded
in the rotor yoke, wherein a magnet constituent for the permanent
magnet is embedded in the rotor yoke and current is passed through
the stator winding to magnetize the magnet constituent. Hence, the
rotor can be inserted into the stator without being magnetically
attracted to its surrounding, permitting dramatically improved
assemblability of the synchronous induction motor. This makes it
possible to prevent an inconvenience of reduced productivity of the
synchronous induction motor, which permits improved assemblability
of the synchronous induction motor. As a result, a highly reliable
synchronous induction motor can be provided.
[0035] In a preferred form of the manufacturing method for the
synchronous induction motor in accordance with the present
invention, a rare earth type or ferrite material is used for the
magnet constituent. Therefore, a high magnet characteristic can be
achieved even if, for example, a magnetizing magnetic field is
weak. This makes it possible to reduce the current passing through
the stator winding so as to minimize a temperature rise that occurs
at the time of magnetization. Thus, the deformation of the rotor or
the stator or the like caused by high temperature can be minimized,
ensuring high quality of the synchronous induction motor.
[0036] In a preferred form of the manufacturing method for the
synchronous induction motor in accordance with the present
invention, the stator winding is of a single-phase configuration
and has a primary winding and an auxiliary winding, and the magnet
constituent is magnetized by the current passed through either the
primary winding or the auxiliary winding. Hence, it is possible to
achieve better magnetizing performance than, for example, in the
case where current is passed through both the primary winding and
the auxiliary winding at the same time. This allows an unmagnetized
magnet material to be intensely magnetized.
[0037] In a preferred form of the manufacturing method for the
synchronous induction motor in accordance with the present
invention, the stator winding is of a three-phase configuration
that includes a three-phase winding. The magnet constituent is
magnetized by current passed through a single phase, two phases, or
three phases of the stator windings. Therefore, it is possible to
select the phase or phases through which current is to be passed
according to the disposition of the magnet or the permissible
current (against deformation or the like) of the windings.
[0038] In yet another preferred form of the manufacturing method
for the synchronous induction motor in accordance with the present
invention, the stator windings are coated with varnish or a
sticking agent that is heated to fuse the windings. Hence, for
example, even if the stator windings are subjected to
electromagnetic forces when an unmagnetized magnet constituent
inserted into the rotor is magnetized by passing current through
the stator windings, it is possible to restrain the deformation of
windings and the deterioration of the films of the windings. Thus,
since the winding ends of the stator windings do not deform even if
an unmagnetized magnet material inserted into the rotor is
magnetized, a highly reliable synchronous induction motor can be
provided.
[0039] According to yet another aspect of the present invention,
there is provided a drive unit for a synchronous induction motor
that includes a stator equipped with a stator winding formed of a
primary winding and an auxiliary winding, a rotor rotating in the
stator, a secondary conductor provided around a rotor yoke
constituting the rotor, a permanent magnet embedded in the rotor
yoke, an operating capacitor connected to the auxiliary winding,
and a series circuit of a start-up capacitor and a PTC, which is
connected in parallel to the operating capacitor. This arrangement
permits larger running torque to be provided at starting up the
synchronous induction motor equipped with the operating capacitor
connected to the auxiliary winding, and the series circuit of the
start-up capacitor and the PTC, which is connected in parallel to
the operating capacitor. This enables the power consumed during
normal operation to be reduced, making it possible to provide a
drive unit capable of running the synchronous induction motor with
extremely high efficiency. Hence, considerably higher efficiency
can be achieved during the operation of the synchronous induction
motor.
[0040] According to still another aspect of the present invention,
there is provided a drive unit for a synchronous induction motor
that includes a stator equipped with a stator winding formed of a
primary winding and an auxiliary winding, a rotor rotating in the
stator, a secondary conductor provided around a rotor yoke
constituting the rotor, a permanent magnet embedded in the rotor
yoke, an operating capacitor connected to the auxiliary winding,
and a PTC connected in parallel to the operating capacitor. This
arrangement permits larger running torque to be provided at
starting up the synchronous induction motor equipped with the
operating capacitor connected to the auxiliary winding and the PTC
connected in parallel to the operating capacitor. This enables the
power consumed during normal operation to be reduced, making it
possible to provide a drive unit capable of running the synchronous
induction motor with extremely high efficiency. Hence, considerably
higher efficiency can be achieved during the operation of the
synchronous induction motor.
[0041] According to yet another aspect of the present invention,
there is provided a drive unit for a synchronous induction motor
that includes a stator equipped with a stator winding formed of a
primary winding and an auxiliary winding, a rotor rotating in the
stator, a secondary conductor provided around a rotor yoke
constituting the rotor, a permanent magnet embedded in the rotor
yoke, an operating capacitor connected to the auxiliary winding,
and a series circuit of a start-up capacitor and a start-up relay
contact connected in parallel to the operating capacitor. This
arrangement permits larger running torque to be provided at
starting up the synchronous induction motor equipped with the
operating capacitor connected to the auxiliary winding, and the
series circuit of the start-up capacitor and the start-up relay
contact connected in parallel to the operating capacitor. This
enables the power consumed during normal operation to be reduced,
making it possible to provide a drive unit capable of running the
synchronous induction motor with extremely high efficiency. Hence,
considerably higher efficiency can be achieved during the operation
of the synchronous induction motor.
[0042] According to a further aspect of the present invention,
there is provided a drive unit for a synchronous induction motor
that includes a stator equipped with a stator winding formed of a
primary winding and an auxiliary winding, a rotor rotating in the
stator, a secondary conductor provided around a rotor yoke
constituting the rotor, a permanent magnet embedded in the rotor
yoke, and an operating capacitor connected to the auxiliary
winding. This arrangement permits larger running torque to be
provided at starting up the synchronous induction motor equipped
with the operating capacitor connected to the auxiliary winding.
This enables the power consumed during normal operation to be
reduced, making it possible to provide a drive unit capable of
running the synchronous induction motor with extremely high
efficiency. Hence, considerably higher efficiency can be achieved
during the operation of the synchronous induction motor.
[0043] According to a further aspect of the present invention,
there is provided a hermetic electric compressor having a
compression unit and an electric unit for driving the compression
unit in a hermetic vessel, wherein the electric unit is secured to
the hermetic vessel and constituted by a stator equipped with a
stator winding and a rotor rotating in the stator, the rotor has a
secondary conductor provided around a rotor yoke and a permanent
magnet embedded in the rotor yoke, and a thermal protector for
cutting off the supply of current to the electric unit in response
to a predetermined temperature rise is provided in the hermetic
vessel. Therefore, installing the thermal protector onto the stator
winding, for example, makes it possible to cut off the supply of
current to the electric unit if the temperature of the stator
winding rises. This arrangement makes it possible to prevent the
permanent magnet embedded in the rotor yoke from being thermally
demagnetized by a rise in temperature of the electric unit. Hence,
the supply of current to the stator winding can be cut off before
the stator winding generates abnormal heat while the hermetic
electric compressor is in operation. This makes it possible to
securely prevent damage to the stator winding and thermal
demagnetization of the permanent magnet so as to ideally maintain
the driving force of a synchronous induction motor, permitting
significantly improved reliability of the electric unit.
[0044] According to a further aspect of the present invention,
there is provided a hermetic electric compressor having a
compression unit and an electric unit for driving the compression
unit in a hermetic vessel, wherein the electric unit is secured to
the hermetic vessel and constituted by a stator equipped with a
stator winding and a rotor rotating in the stator, the rotor has a
secondary conductor provided around a rotor yoke and a permanent
magnet embedded in the rotor yoke, and a thermal protector for
cutting off the supply of current to the electric unit at a
predetermined temperature rise is provided on the outer surface of
the hermetic vessel. Therefore, it is possible to cut off the
supply of current to the electric unit if the temperature of the
outer surface of the hermetic vessel rises due to the heat
generated by the electric unit. Thus, a temperature rise in the
hermetic vessel can be restrained, so that an accident, such as a
fire, caused by a temperature rise in the hermetic vessel can be
prevented.
[0045] In a preferred form of the hermetic electric compressor in
accordance with the present invention, the thermal protector is
constructed of a thermistor whose resistance value varies with
temperature and a controller that controls the supply of current to
the electric unit according to a change in the resistance value of
the thermistor. Thus, if, for example, the temperature of the
hermetic electric compressor rises and exceeds a preset level, the
controller controls the supply of current to the electric unit and
cuts off the supply of current to the electric unit. With this
arrangement, it is possible to control the current supplied to the
stator winding before the hermetic electric compressor is run under
overload and damaged. This means that a temperature rise in the
electric unit can be securely controlled by controlling the
revolution of the electric unit, enabling the service life of the
electric unit to be prolonged, with resultant dramatically improved
reliability of the hermetic electric compressor.
[0046] In a preferred form of the hermetic electric compressor in
accordance with the present invention, the thermal protector is
constituted by a bimetal switch, so that the current supplied to
the electric unit can be cut off also if the temperature of the
hermetic electric compressor rises. This obviates the need for
controllably adjust the electric unit by using an expensive circuit
device, making it possible to effect inexpensive and secure
protection of the hermetic electric compressor from damage caused
by a temperature rise.
[0047] In a preferred form of the hermetic electric compressor in
accordance with the present invention, the thermal protector is
constituted by a thermostat that opens/closes a contact according
to temperature, so that the current supplied to the electric unit
can be cut off also if the temperature of the hermetic electric
compressor rises. This obviates the need for controllably adjusting
the electric unit by using an expensive circuit device, making it
possible to effect inexpensive and secure protection of the
hermetic electric compressor from damage caused by a temperature
rise.
[0048] According to a further aspect of the present invention,
there is provided a hermetic electric compressor having a
compression unit and an electric unit for driving the compression
unit in a hermetic vessel, wherein the electric unit is secured to
the hermetic vessel and constituted by a stator equipped with a
stator winding and a rotor rotating in the stator, the rotor has a
secondary conductor provided around a rotor yoke and a permanent
magnet embedded in the rotor yoke, and an overload protector for
cutting off the supply of current to the electric unit in response
to a predetermined overload current is provided. Therefore, it is
possible to cut off the supply of current to the electric unit if
the hermetic electric compressor is overloaded during operation,
thereby allowing the electric unit to be protected from a
temperature rise. Thus, damage to the electric unit can be
prevented, enabling the service life of the electric unit to be
considerably prolonged, with resultant dramatically improved
reliability of the hermetic electric compressor.
[0049] In a preferred form of the hermetic electric compressor in
accordance with the present invention, the overload protector is
constituted by an overload switch, so that the current supplied to
the electric unit can be cut off to prevent a temperature rise in
the electric unit thereby to protect it if the hermetic electric
compressor is overloaded during operation. Thus, damage to the
electric unit can be prevented, enabling the service life of the
electric unit to be considerably prolonged, with resultant
dramatically improved reliability of the hermetic electric
compressor.
[0050] In another preferred form of the hermetic electric
compressor in accordance with the present invention, the overload
protector is constituted by a current transformer for detecting the
current supplied to the electric unit and a controller for
controlling the supply of current to the electric unit on the basis
of an output of the current transformer, so that the current
supplied to the electric unit can be cut off by the controller if
the hermetic electric compressor is overloaded during operation.
This arrangement makes it possible to prevent a temperature rise in
the electric unit so as to protect the electric unit. Hence, damage
to the electric unit attributable to an overload current can be
securely prevented.
[0051] In another preferred form of the hermetic electric
compressor in accordance with the present invention, the controller
cuts off the supply of current to the electric unit after a
predetermined time elapses since a temperature or current exceeded
a predetermined value. It is therefore possible to protect, by the
controller, the electric unit which would be damaged if
continuously subjected to an excessive temperature rise or
overcurrent caused by an overloaded operation or the like of the
hermetic electric compressor. Thus, damage to the electric unit can
be prevented, enabling the service life of the electric unit to be
considerably prolonged, with resultant dramatically improved
reliability of the hermetic electric compressor.
[0052] In a further preferred form of the hermetic electric
compressor in accordance with the present invention, the controller
restarts the supply of current to the electric unit after waiting
for the elapse of a predetermined delay time since the supply of
current to the electric unit was cut off. This means that the delay
time is always allowed before the supply of current to the electric
unit is restarted after the supply of current to the electric unit
was cut off. It is therefore possible to prevent the rotor from
becoming hot due to, for example, frequent repetition of energizing
and de-energizing of the electric unit. Hence, demagnetization of
the permanent magnet embedded in the rotor due to heat can be
prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a longitudinal sectional side view of a hermetic
electric compressor to which a synchronous induction motor in
accordance with the present invention has been applied;
[0054] FIG. 2 is a plan view of the hermetic electric compressor
with its hermetic vessel split into two;
[0055] FIG. 3 is a cross sectional top view of the motor;
[0056] FIG. 4 is a partially cutaway cross sectional top view of a
rotor;
[0057] FIG. 5 is a side view of the rotor;
[0058] FIG. 6 is a top view of the rotor;
[0059] FIG. 7 is a longitudinal side view of the rotor shown in
FIG. 6;
[0060] FIG. 8 is a refrigerant circuit diagram of an air
conditioner or an electric refrigerator or the like that uses the
hermetic electric compressor provided with the synchronous
induction motor in accordance with the present invention;
[0061] FIG. 9 is an electric circuit diagram of the synchronous
induction motor;
[0062] FIG. 10 is a top view of another rotor;
[0063] FIG. 11 is a partially longitudinal sectional side view of
the rotor shown in FIG. 10;
[0064] FIG. 12 is a top view of another rotor;
[0065] FIG. 13 is a longitudinal sectional side view of the rotor
shown in FIG. 12;
[0066] FIG. 14 is a top view of a rotor illustrating an end surface
member that is provided inside an end ring and fixed by a
balancer;
[0067] FIG. 15 is a diagram showing a part of the longitudinal
sectional side view of the rotor shown in FIG. 12;
[0068] FIG. 16 is a diagram showing a part of the longitudinal
sectional side view of a rotor incorporating a balancer formed of a
plurality of laminated sheet balancers;
[0069] FIG. 17 is a top view of a rotor in which an end surface
member and a balancer have been integrally formed and
installed;
[0070] FIG. 18 is a diagram showing a part of the longitudinal
sectional side view of the rotor shown in FIG. 17;
[0071] FIG. 19 is a top view of another rotor;
[0072] FIG. 20 is a partial longitudinal sectional side view of the
rotor shown in FIG. 19;
[0073] FIG. 21 is a top view of a rotor in which an end surface
member is integrally formed with a balancer and fixed to a rotor
yoke;
[0074] FIG. 22 is a partial longitudinal sectional side view of the
rotor shown in FIG. 21;
[0075] FIG. 23 is a cross sectional top view of another rotor;
[0076] FIG. 24 is an analytical diagram of a magnetic field of a
rotor in the layout of the permanent magnet shown in FIG. 4;
[0077] FIG. 25 illustrates a magnetic flux density in a rotating
shaft of the rotor shown in FIG. 24;
[0078] FIG. 26 is an analytical diagram of a magnetic field of a
rotor observed when a void is formed in the rotor yoke in the
layout of the permanent magnet shown in FIG. 4;
[0079] FIG. 27 is a diagram illustrating a magnetic flux density in
the rotating shaft of the rotor shown in FIG. 26;
[0080] FIG. 28 is an analytical diagram of the magnetic field of
the rotor observed when a plurality of voids is formed in the rotor
yoke in the layout of the permanent magnet shown in FIG. 4;
[0081] FIG. 29 is a diagram illustrating a magnetic flux density in
the rotating shaft of the rotor shown in FIG. 28;
[0082] FIG. 30 is an analytical diagram of the magnetic field of a
rotor configured such that a magnetic field produced by a permanent
magnet bypasses a rotating shaft;
[0083] FIG. 31 is a diagram illustrating a magnetic flux density in
the rotating shaft of the rotor shown in FIG. 28;
[0084] FIG. 32 is a cross sectional top view of a rotor
illustrating another layout example of a permanent magnet;
[0085] FIG. 33 is a cross sectional top view of a rotor
illustrating yet another layout example of a permanent magnet;
[0086] FIG. 34 is a cross sectional top view of a rotor
illustrating still another layout example of a permanent
magnet;
[0087] FIG. 35 is a cross sectional top view of a rotor
illustrating a further layout example of a permanent magnet;
[0088] FIG. 36 is a cross sectional top view of a rotor
illustrating another layout example of a permanent magnet;
[0089] FIG. 37 is a cross sectional top view of a rotor
illustrating another layout example of a permanent magnet;
[0090] FIG. 38 is a partially cutaway cross sectional top view of
another rotor;
[0091] FIG. 39 is a partial longitudinal sectional side view of the
rotor shown in FIG. 38;
[0092] FIG. 40 is a cross sectional top view of the rotor shown in
FIG. 38;
[0093] FIG. 41 is a cross sectional top view of another rotor;
[0094] FIG. 42 is a cross sectional top view of yet another
rotor;
[0095] FIG. 43 is a cross sectional top view of still another
rotor;
[0096] FIG. 44 is a cross sectional top view of a further
rotor;
[0097] FIG. 45 is a cross sectional top view of another rotor;
[0098] FIG. 46 is an electrical circuit diagram of a three-phase,
two-pole synchronous induction motor;
[0099] FIG. 47 is an electrical circuit diagram of a drive unit of
the synchronous induction motor in accordance with the present
invention;
[0100] FIG. 48 is an electrical circuit diagram of a drive unit of
another synchronous induction motor;
[0101] FIG. 49 is an electrical circuit diagram of a drive unit of
still another synchronous induction motor;
[0102] FIG. 50 is an electrical circuit diagram of a drive unit of
yet another synchronous induction motor;
[0103] FIG. 51 is a diagram illustrating a relationship between a
rotational torque and a number of revolutions provided by each
electric circuit of each drive unit;
[0104] FIG. 52 is another refrigerant circuit diagram of an air
conditioner or an electric refrigerator or the like that uses the
hermetic electric compressor incorporating a synchronous induction
motor;
[0105] FIG. 53 is a longitudinal sectional side view of a part (in
the vicinity of an end cap) of the hermetic electric compressor in
accordance with the present invention;
[0106] FIG. 54 is an electrical circuit diagram of a synchronous
induction motor;
[0107] FIG. 55 is a longitudinal sectional side view of a part (in
the vicinity of an end cap) of another hermetic electric
compressor;
[0108] FIG. 56 is an electrical circuit diagram of a synchronous
induction motor of the hermetic electric compressor shown in FIG.
55;
[0109] FIG. 57 is a longitudinal sectional side view of a part (in
the vicinity of an end cap) of another hermetic electric
compressor;
[0110] FIG. 58 is a longitudinal sectional side view of a part (in
the vicinity of an end cap) of still another hermetic electric
compressor;
[0111] FIG. 59 is an electrical circuit diagram of a synchronous
induction motor of the hermetic electric compressor shown in FIG.
58;
[0112] FIG. 60 is a longitudinal sectional side view of a part (in
the vicinity of an end cap) of yet another hermetic electric
compressor;
[0113] FIG. 61 is an electrical circuit diagram of a synchronous
induction motor of the hermetic electric compressor shown in FIG.
60;
[0114] FIG. 62 is a longitudinal sectional side view of a part (in
the vicinity of an end cap) of a further hermetic electric
compressor;
[0115] FIG. 63 is an electrical circuit diagram of a synchronous
induction motor of the hermetic electric compressor shown in FIG.
62;
[0116] FIG. 64 is a longitudinal sectional side view of a part (in
the vicinity of an end cap) of another hermetic electric
compressor;
[0117] FIG. 65 is an electrical circuit diagram of a synchronous
induction motor of the hermetic electric compressor shown in FIG.
64; and
[0118] FIG. 66 is an electrical circuit diagram of a synchronous
induction motor of another hermetic electric compressor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0119] Embodiments of the present invention will be described in
detail with reference to the accompanying drawings. FIG. 1 is a
longitudinal sectional side diagram of a hermetic electric
compressor C, an embodiment to which the present invention is
applied. A hermetic vessel 1 in FIG. 1 includes a synchronous
induction motor 2 in accordance with the present invention in an
upper compartment and a compressor 3 in a lower compartment in the
hermetic vessel 1, the compressor 3 being rotatively driven by the
synchronous induction motor 2. The hermetic vessel 1 is split into
two parts in advance to house the synchronous induction motor 2 and
the compressor 3, then hermetically sealed by high-frequency
welding or the like. The hermetic electric compressor C may be a
rotary, reciprocal, scroll compressor, or the like.
[0120] The synchronous induction motor 2 is constructed of a
single-phase, two-pole stator 4 secured to the inner wall of the
hermetic vessel 1 and a rotor 5 which is located on the inner side
of the stator 4 and rotatively supported around a rotating shaft 6.
The stator 4 is provided with a stator winding 7 for applying a
rotational magnetic field to the rotor 5.
[0121] The compressor 3 has a first rotary cylinder 9 and a second
rotary cylinder 10 separated by a partitioner 8. The cylinders 9
and 10 have eccentric members 11 and 12 rotatively driven by the
rotating shaft 6. The eccentric positions of the eccentric members
11 and 12 are phase-shifted from each other 180 degrees.
[0122] A first roller 13 located in the cylinder 9 and a second
roller 14 located in the cylinder 10 rotate in the cylinders as the
eccentric members 11 and 12 rotate. Reference numerals 15 and 16
denote a first frame member and a second frame member,
respectively. The first frame member 15 forms a closed compression
space of the cylinder 9 between itself and the partitioner 8.
Similarly, the second frame member 16 forms a closed compression
space of the cylinder 10 between itself and the partitioner 8. The
first frame member 15 and the second frame member 16 are equipped
with bearings 17 and 18, respectively, that rotatively support the
bottom of the rotating shaft 6.
[0123] Discharge mufflers 19 and 20 are installed so as to cover
the first frame member 15 and the second frame member 16. The
cylinder 9 and the discharge muffler 19 are in communication
through a discharge aperture (not shown) provided in the first
frame member 15. Similarly, the cylinder 10 and the discharge
muffler 20 are also in communication through a discharge aperture
(not shown) provided in the second frame member 16. A bypass pipe
21 provided outside the hermetic vessel 1, and is in communication
with the interior of the discharge muffler 20.
[0124] A discharge pipe 22 is provided at the top of the hermetic
vessel 1. Suction pipes 23 and 24 are connected to the cylinders 9
and 10, respectively. A hermetic terminal 25 supplies electric
power to the stator winding 7 of the stator 4 from outside the
hermetic vessel 1 (the lead wire connecting the hermetic terminal
25 and the stator winding 7 being not shown).
[0125] A rotor iron core 26 is formed of a plurality of laminated
rotator iron plates, each of which is made by punching an
electromagnetic steel plate having a thickness of 0.3 mm to 0.7 mm
(not shown) into a predetermined shape. The laminated rotator iron
plates are crimped into one piece, or may be welded into one piece.
End surface members 66 and 67 are attached to the top and bottom
ends of the rotor iron core 26. The end surface members 66 and 67
are formed of planes made of a non-magnetic material, such as
stainless steel, aluminum, copper, or brass. If the end surface
members 66 and 67 should use a magnetic material, then the end
surface members 66 and 67 would provide a magnetic path, and the
magnet of the rotor 5 would develop a magnetic short circuit,
leading to degraded running performance of the synchronous
induction motor 2. For this reason, a non-magnetic material is used
for the members 66 and 67.
[0126] FIG. 2 is a plan view of the hermetic electric compressor C
having the hermetic vessel 1 split into two parts. FIG. 3 is a
cross sectional top view of the hermetic electric compressor C,
FIG. 4 is a cross sectional top view of the rotor 5, and FIG. 5 is
a side view of the rotor 5. The stator 4 has the stator winding 7
wound around the stator 4. A leader line 50 connected to the stator
winding 7 and a coil end of the stator winding 7 are joined
together with a polyester thread 70, and the leader line 50 is
connected to the hermetic terminal 25.
[0127] The rotor 5 is constructed of a rotor yoke 5A, die-cast
squirrel-cage secondary conductors 5B positioned around the rotor
yoke 5A, a die-cast end ring 69 which is positioned on the
peripheral portion of an end surface of the rotor yoke 5A, which
annularly protrudes by a predetermined dimension, and which is
integrally die-cast with the squirrel-cage secondary conductors 5B,
and permanent magnets 31 embedded in the rotor yoke 5A. The
permanent magnets 31 are magnetized after permanent magnet
materials are inserted in slots 44, which will be discussed
hereinafter. The permanent magnets 31 (31SA and 31SB) embedded in
one side (e.g., the right side in the drawing) from the rotating
shaft 6 are polarized with the same south pole, while the permanent
magnets 31 (31NA and 31NB) embedded in the other side (e.g., the
left side in the drawing) are polarized with the same north
pole.
[0128] The plurality of squirrel-cage secondary conductors 5B are
provided on the peripheral portion of the rotor yoke 5A and have
aluminum diecast members injection-molded in cylindrical holes (not
shown) formed in the cage in the direction in which the rotating
shaft 6 extends. The squirrel-cage secondary conductors 5B are
formed in a so-called skew pattern in which they are spirally
inclined at a predetermined angle in the circumferential direction
of the rotating shaft 6 from one end toward the other end, as shown
in FIG. 5.
[0129] The rotor yoke 5A has a plurality of slots 44 (four in this
embodiment) vertically formed with both ends open. The openings at
both ends of the slots 44 are closed by a pair of the end surface
members 66 and 67, respectively, as shown in FIGS. 6 and 7. When
the squirrel-cage secondary conductors 5B and the end rings 68 and
69 are die-cast, the end surface member 67 is fixed to the rotor
yoke 5A by the end ring 69. The end surface member 66 is secured to
the rotor yoke 5A by a plurality of rivets 66A functioning as
fixtures.
[0130] In this case, after the permanent magnets 31 are inserted
through the openings of the slots 44, the openings are closed by
the end surface member 66, and the end surface member 66 is fixed
by riveting into engaging holes 5C provided in the rotor yoke 5A.
This secures the permanent magnets 31 into the slots 44. The
permanent magnets 31 are made of a rare earth type permanent magnet
material of, for example, a praseodymium type permanent magnet or a
neodymium type permanent magnet with nickel plating or the like
provided on the surface thereof so as to produce high magnetic
forces. The permanent magnets 31 and 31 are provided such that they
oppose the rotating shaft 6, and the opposing permanent magnets 31
and 31 are embedded and magnetized to have opposite poles.
[0131] The permanent magnets 31SA and 31SB embedded in one side
(e.g., the right side and the upper side in the drawing) from the
rotating shaft 6 are polarized with the same south pole, while the
permanent magnets 31NA and 31NB embedded in the other side (e.g.,
the left side and the lower side in the drawing) are polarized with
the same north pole. More specifically, the permanent magnets 31SA,
31SB and the permanent magnets 31NA, 31NB are disposed to
substantially form a rectangular shape around the rotating shaft 6,
and are embedded such that they carry two poles, namely, the south
pole and the north pole, outward in the circumferential direction
of the rotating shaft 6. This enables torque to be applied to the
rotor 5 by the magnetic forces of a primary winding 7A and an
auxiliary winding 7B, which will be discussed hereinafter. The
layout of the permanent magnets 31 shown in FIGS. 6 and 7 is
different from the layout of the permanent magnets 31 shown in
FIGS. 2, 3, and 4. The layout of the permanent magnets 31 shown in
FIGS. 6 and 7 may be replaced by the layout shown in FIGS. 2, 3,
and 4. In this case, however, the riveting positions of the rivets
66A have to be changed. Further alternatively, the permanent
magnets 31 shown in FIGS. 2, 3, and 4 may be arranged as shown in
FIG. 6 or 7.
[0132] The hermetic electric compressor C provided with the
synchronous induction motor 2 set forth above is used in a
refrigerant circuit (FIG. 8) of an air conditioner or an electric
refrigerator or the like to cool the interior of a room or a
refrigerator. More specifically, when the compressor 3 of the
hermetic electric compressor C is driven, a refrigerant sealed in
the refrigerant circuit is drawn in through a suction pipe 23,
compressed by the first rotary cylinder 9 and the second rotary
cylinder 10, and discharged into a pipe 27 from a discharge pipe
22. The compressed gas refrigerant discharged into the pipe 27
flows into a condenser 28 where it radiates heat and is condensed
into a liquid refrigerant, then flows into a receiver tank 29.
[0133] The liquid refrigerant that flows into and temporarily stays
in the receiver tank 29 passes from a pipe 29A at the outlet side
of the receiver tank 29 to a dryer 30, a moisture indicator 35, a
solenoid valve 36, and a thermostatic expansion valve 37 wherein it
is throttled. Then, the liquid refrigerant flows into an evaporator
38 where it evaporates. At this time, the refrigerant absorbs heat
around it to effect its cooling action. When the refrigerant almost
liquefies, the refrigerant runs from a pipe 38A at the outlet side
of the evaporator 38 into an accumulator 39 where it undergoes
vapor-liquid separation, then it is drawn back into the compressor
3 again through a check valve 40. This refrigerating cycle is
repeated.
[0134] The liquid refrigerant that has left the receiver tank 29 is
branched off from the pipe 29A into a pipe 38A between the
evaporator 38 and the accumulator 39 via a capillary tube 41, a
high/low pressure switch 42, and a capillary tube 43. The high/low
pressure switch 42 detects the pressures of the pipe 29A and the
pipe 38A through the capillary tubes 41 and 43. If the pressures of
the two pipes 29A and 38A exceeds a predetermined pressure
difference or more, resulting in an insufficient amount of the
refrigerant drawn into the hermetic electric compressor C, then the
liquid refrigerant from the receiver tank 29 is allowed to flow
into the compressor 3 for protection. The thermostatic expansion
valve 37 automatically adjusts its opening degree on the basis of
the temperature detected by a thermosensitive cylinder 34 provided
at the outlet end of the evaporator 38.
[0135] FIG. 9 shows an electrical circuit diagram of the
synchronous induction motor 2. The synchronous induction motor 2
shown in FIG. 9 that receives power from a single-phase alternating
current commercial power source AC is equipped with a primary
winding 7A and an auxiliary winding 7B. One end of the primary
winding 7A is connected to one end of the single-phase alternating
current commercial power source AC, and the other end thereof is
connected to the other end of the power source AC. The auxiliary
winding 7B connected to one end of the single-phase alternating
current commercial power source AC is connected in series to the
other end of the power source AC through the intermediary of a PTC
46 and a start-up capacitor 48 and also connected to an operating
capacitor 47 in parallel to the PTC 46 and the start-up capacitor
48.
[0136] The PTC 46 is formed of a semiconductor device whose
resistance value increases in proportion to temperature. The
resistance value is low when the synchronous induction motor 2 is
started, and increases as current passes therethrough, generating
heat. A power switch 49 is constituted by a current-sensitive type
line current sensor for detecting line current and an overload
relay that serves also as a protective switch used to supply power
from the single-phase alternating current commercial power source
AC to the stator winding 7 and to cut off the supply of power to
the stator winding 7. The operating capacitor 47 is set to have a
capacitance suited for steady operation, and the operating
capacitor 47 and the start-up capacitor 48 are set to provide
capacitances suited for start-up in the state wherein the
capacitors 47 and 48 are connected in parallel.
[0137] The operation of the synchronous induction motor 2 will now
be described. When the power switch 49 is closed, current flows
from the single-phase alternating current commercial power source
AC to the primary winding 7A and the auxiliary winding 7B. When the
synchronous induction motor 2 is started up, the temperature of the
PTC 46 is low and the resistance value thereof is also low, so that
large current passes through the PTC 46 and large current
accordingly passes through the auxiliary winding 7B. The auxiliary
winding 7B obtains start-up torque from the current phase
difference between itself and the primary winding 7A produced by
the operating capacitor 47 and the start-up capacitor 48 connected
in parallel, thus causing the synchronous induction motor 2 to
start running. This energization causes the PTC 46 to start
self-heating, and the resistance value of the PTC 46 increases
accordingly until very little current passes through the PTC 46
itself. Thus, the start-up capacitor 48 is isolated, and the
synchronous induction motor 2 continues steady operation from the
current phase difference between the primary winding 7A and the
auxiliary winding 7B by the operating capacitor 47. As the hermetic
electric compressor C operates, air conditioning is effected in a
room or the interior of a refrigerator is cooled.
[0138] As described above, one of the end surface members 67 is
secured to the rotor yoke 5A by one of the end rings 69 when the
secondary conductors 5B and the two end rings 68 and 69 are formed.
The other end surface member 66 is secured to the rotor yoke 5A by
the rivets 66A. Hence, it is possible to secure the end surface
member 67 to the rotor yoke 5A at the same time when the secondary
conductors 5B and the end rings 68 and 69 are die-cast. Thus, after
the permanent magnets 31 are inserted into the slots 44, the
permanent magnets 31 can be secured to the rotor 5 merely by
securing the other end surface member 66 to the rotor yoke 5A by
the rivets 66A.
[0139] Another rotor 5 is shown in FIG. 10 and FIG. 11. In this
case, non-magnetic constituents 55 and 56 are disposed in contact
with the inner sides of the two end rings 68 and 69, which are
integrally die-cast with the squirrel-cage type secondary
conductors 5B making up the rotor 5. The non-magnetic constituents
55 and 56 are made of copper, brass, or the like that allows easy
passage of current. The thickness of the non-magnetic constituents
55 and 56 is set such that, when they are closely attached onto the
plate-like end surface members 66 and 67 that close both ends of
the permanent magnets 31 embedded in the rotor yoke 5A, they do not
jut out beyond the end rings 68 and 69 that are integrally
die-cast, protruding from both end surfaces of the rotor yoke
5A.
[0140] The non-magnetic constituents 55 and 56 are riveted at both
ends thereof by the rivets 66B in the engaging through holes 5C
provided in the rotor yoke 5A. The rivets 66B are fixed at four
positions in the inner side of the corners where both ends of the
individual permanent magnets 31SA, 31SB and the permanent magnets
31NA, 31NB are in contact, the permanent magnets being disposed
substantially into a rectangular shape around the rotating shaft 6.
Thus, the non-magnetic constituents 55 and 56 fix the two end
surface members 66 and 67 by pressing them against the rotor yoke
5A.
[0141] FIG. 12 and FIG. 13 show another rotor 5. As in the case of
the rotor shown in FIG. 10 and FIG. 11, the non-magnetic
constituents 55 and 56 are disposed in contact with the inner sides
of the two end rings 68 and 69, which are integrally die-cast with
the squirrel-cage type secondary conductors 5B making up the rotor
5. The non-magnetic constituents 55 and 56 are made of copper,
brass, or the like that allows easy passage of current. The
thickness of the non-magnetic constituents 55 and 56 is set such
that, when they are closely attached onto the plate-like end
surface members 66 and 67 that close both ends of the permanent
magnets 31 embedded in the rotor yoke 5A, they do not jut out
beyond the end rings 68 and 69 that are integrally die-cast,
protruding from both end surfaces of the rotor yoke 5A.
[0142] Engaging pins 55A, 55A having a predetermined diameter and a
predetermined length are protuberantly formed on one surface of the
non-magnetic constituent 55. Similarly, engaging pins 56A, 56A
having a predetermined diameter and a predetermined length are
protuberantly formed on one surface of the non-magnetic constituent
56. The non-magnetic constituents 55 and 56 are formed using a
cast, and the engaging pins 55A, 55A, 56A, and 56A are integrally
formed with the non-magnetic constituents 55 and 56. The
non-magnetic constituents 55 and 56 are fixed by being press-fitted
into the engaging holes 5C provided in the rotor yoke 5A. Thus, the
non-magnetic constituents 55 and 56 secure the two end surface
members 66 and 67 by pressing them against the rotor yoke 5A.
[0143] As set forth above, the non-magnetic constituents 55 and 56
are disposed in contact with the inner sides of the two end rings
68 and 69, and the two end surface members 66 and 67 are secured by
being pressed against the rotor yoke 5A by the non-magnetic
constituents 55 and 56. Therefore, the sectional areas of the end
rings 68 and 69 can be increased by the amount provided by the
non-magnetic constituents 55 and 56 securing the members 66 and 67
by pressing. With this arrangement, the secondary resistance is
decreased by the amount equivalent to the increase in the sectional
areas of the end rings 68 and 69. Hence, a rise in temperature of
the end rings 69 and 69 can be restrained, and the magnetic forces
of the magnets can be effectively used, making it possible to
significantly improve the running performance of the synchronous
induction motor 2.
[0144] The rotor yoke 5A is provided with a balancer 60 for
ensuring good rotational balance of the rotor 5 (see FIG. 14 and
FIG. 15). The balancer 60 die-cast into a predetermined shape in
advance has an end surface fixing portion 60A for fixing the end
surface member 66 and a rested portion 60B placed on the end ring
68, the end surface fixing portion 60A and the rested portion 60B
forming a step. The balancer 60 is shaped substantially like a
semicircle of the rotor yoke 5A. Rivets 66C are located
substantially equidistantly from the center of the semicircular
balancer 60, and the balancer 60 is secured to the rotor yoke 5A
together with the end surface members 66 by the rivets 66C.
[0145] Thus, since the balancer 60 is secured to the rotor yoke 5A
together with the end surface member 66 by the rivets 66C, the ease
of installing the balancer 60 can be dramatically improved. This
obviates the need for separately fixing the permanent magnets 31
and the balancer 60, permitting dramatically improved productivity
of the synchronous induction motor 2.
[0146] A balancer assembly 61 is shown in FIG. 16. The balancer 61
is constructed of a predetermined number of plate-like balancers
61A and plate-like balancers 61B having substantially the same
outer configuration as that of the rested portion 60B. The
plate-like balancers 61A are made of metal plates, each plate being
made of stainless steel, copper, brass, or the like and having a
predetermined thickness and having substantially the same outer
configuration as that of the end surface fixing portion 60A of the
balancer 60 shown in FIG. 14. A predetermined number of the
plate-like balancers 61A and a predetermined number of the
plate-like balancers 61B are laminated, and secured to the rotor
yoke 5A together with the end surface member 66 by the rivets 66C,
thereby making up the balancer assembly 61.
[0147] Thus, since the balancer assembly 60 is fixed to the rotor
yoke 5A together with the end surface member 66 by the rivets 66A,
greater ease of installation of the balancer 60 can be achieved,
allowing considerably higher productivity to be achieved. Moreover,
since a plurality of the plate-like balancers 61A and 61B are
laminated, the weight of the balancer assembly 61 can be easily
adjusted. In addition, the cost of the balancer assembly 61 can be
significantly reduced by using, for example, inexpensive metal
plates for the balancer assembly 61.
[0148] FIG. 17 and FIG. 18 show another balancer assembly 62. The
balancer assembly 62 is formed of the end surface member 67 and the
balancer 60 shown in FIG. 14 combined into one piece. A weight
portion 62A corresponding to the balancer 60 and an end surface
portion 62B which is formed continuously from the weight 62A and
which corresponds to the end surface member 67 are combined into
one piece. The balancer assembly 62 is die-cast, or formed by
pouring molten copper, brass, or the like into a mold. The end
surface portion 62B and the weight portion 62A are secured to the
rotor yoke 5A together with the other end surface member 67 by a
rivet 66B and a rivet 66C, respectively.
[0149] As described above, since the balancer 62 is formed of the
end surface member 67 and the balancer 60 combined into one piece,
the number of components can be reduced. This allows the
installation of the end surface member 67 to be simplified, thus
permitting dramatically improved productivity to be achieved.
[0150] FIG. 19 and FIG. 20 show another rotor 5. In this case, the
rotor yoke 5A constituting the rotor 5 has a plurality of slots 44
(four in this embodiment) that are formed to vertically penetrate
the rotor yoke 5A and have their both ends open. The openings of
both ends of the slots 44 are closed by a pair of end surface
members 66 and 67, as shown in FIG. 19 and FIG. 20. When the
squirrel-cage secondary conductors 5B and end rings 68 and 69 are
die-cast, the end surface member 67 is integrally secured to the
rotor yoke 5A by the end ring 69, and the end surface member 66 is
integrally secured to the rotor yoke 5A by the end ring 68.
[0151] In this case, with the peripheral portions of the end
surface members 66 and 67 slightly extended into the end rings 68
and 69, respectively, the rotor yoke 5A, the end rings 68 and 69,
and the end surface members 66 and 67 are die-cast into one piece.
This secures the two end surface members 66 and 67 to both ends of
the rotor yoke 5A, and also fixes the permanent magnets 31 in the
slots 44. The permanent magnets 31 are made of a rare earth type
permanent magnet material of, for example, a praseodymium type
permanent magnet or a neodymium type permanent magnet with nickel
plating or the like provided on the surface thereof so as to
produce high magnetic forces. The permanent magnets 31 and 31 are
provided such that they oppose the rotating shaft 6, and the
opposing permanent magnets 31 and 31 are embedded and magnetized to
have opposite poles.
[0152] The permanent magnets 31SA and 31SB embedded in one side
(e.g., the right side and the upper side in the drawing) from the
rotating shaft 6 are polarized with the same south-seeking poles,
while the permanent magnets 31NA and 31NB embedded in the other
side (e.g., the left side and the lower side in the drawing) are
polarized with the same north-seeking poles. More specifically, the
permanent magnets 31SA, 31SB and the permanent magnets 31NA, 31NB
are disposed to substantially form a rectangular shape around the
rotating shaft 6, and are embedded such that they carry two poles,
namely, the south pole and the north pole, outward in the
circumferential direction of the rotating shaft 6. This enables
torque to be applied to the rotor 5 by the magnetic forces of a
primary winding 7A and an auxiliary winding 7B, which will be
discussed hereinafter. The layout of the permanent magnets 31 shown
in FIGS. 19 and 20 is different from the layout of the permanent
magnets 31 shown in FIGS. 2, 3, and 4. The layout of the permanent
magnets 31 shown in FIGS. 19 and 20 may be replaced by the layout
shown in FIGS. 2, 3, and 4. Further alternatively, the permanent
magnets 31 shown in FIGS. 2, 3, and 4 may be arranged as shown in
FIG. 19 or 20.
[0153] Thus, since the two end surface members 66 and 67 are
secured to the rotor yoke 5A by the two end rings 68 and 69 when
the secondary conductors 5B and the end rings 68 and 69 are formed
by die casting, the two end surface members 66 and 67 can be easily
secured to the rotor yoke 5A when the secondary conductors 5B and
the end rings 68 and 69 are formed by die casting. This arrangement
makes it possible to obviate the need of, for example, the
cumbersome step for inserting the permanent magnets 31 into the
slots 44, then attaching the end surface members 66 and 67 to both
ends of the rotor yoke 5A after die-casting the end rings 68 and
69, as in the case of a prior art.
[0154] Another rotor is shown in FIGS. 21 and 22. In this case, a
rotor yoke 5A is provided with a balancer 60 for ensuring good
rotational balance of the rotor 5. The balancer 60 is integrally
formed with an end surface member 66, and is constituted by an end
surface plate portion 60A, a weight portion 60C, and a connecting
portion 60B that connects the weight portion 60C and the end
surface plate portion 60A. The weight portion 60C is formed to have
a sufficient size to be rested on an end ring 68, and has a
substantially semicircular shape.
[0155] The end surface plate portion 60A has substantially the same
shape as the end surface member 66. The end surface plate portion
60A and the weight portion 60C are connected by the connecting
portion 60B. The end surface plate portion 60A, the weight portion
60C, and the connecting portion 60B are formed into one piece. The
balancer 60 is cast by pouring molten copper, brass, or the like
into a mold. The connecting portion 60B is positioned on the inner
side of the end ring 68, with the periphery of the end surface
plate portion 60A slightly extending into the end ring 68. The
weight portion 60C is formed on the end ring 68.
[0156] The balancer 60 formed as set forth above is secured to the
rotor yoke 5A by the end ring 68 when both end surface members 66
and 67, secondary conductors 5B, and the end rings 68 and 69 are
die-cast. The end surface member 67 is secured to the rotor yoke 5A
by the end ring 69, as previously mentioned. This fixes the
permanent magnets 31 in slots 44 of the rotor yoke 5A.
[0157] Thus, the balancer 60 and the end surface member 67 are
secured to the rotor yoke 5A when the secondary conductors 5B and
the two end rings 68 and 69 are die-cast. This makes it possible to
obviate the need for a cumbersome step for inserting a plurality of
the permanent magnets 31 into the slots 44 after die-casting the
secondary conductor 5B and the two end rings 68 and 69, then
installing the end surface members 66 and 67 to both ends of the
rotor yoke 5A, as in the prior art.
[0158] When the permanent magnets are installed in the rotor of a
synchronous induction motor, a magnetic field of the permanent
magnets inevitably passes through a rotating shaft. Hence, the
rotating shaft is magnetized, and there has been a problem in that
iron powder or the like adheres to the magnetized rotating shaft,
causing the rotating shaft to wear.
[0159] In addition, installing the permanent magnets in the rotor
causes the rotting shaft and a bearing to be attracted to each
other due to the magnetic forces of the permanent magnets,
resulting in high friction between the rotating shaft and the
bearing. This has also been presenting a problem of wear on the
rotating shaft.
[0160] Referring now to FIG. 23 through FIG. 37, the descriptions
will be given of the configuration that significantly restrains the
magnetization of a rotating shaft to which a rotor of a two-pole
synchronous induction motor has been attached.
[0161] In this case, unmagnetized magnet constituents of permanent
magnets 31 are inserted in the openings of slots 44, the openings
are then closed by an end surface member 66, and the end surface
member 66 is riveted to engaging holes 5C provided in the rotor
yoke 5A by rivets 66A so as to fix the magnet constituents in the
slots 44. Thus, the end surface members 66 and 67 are secured to
both ends of the rotor yoke 5A, and the permanent magnets 31 are
fixed in the slots 44. The permanent magnets 31 are made of a rare
earth type permanent magnet material of, for example, a
praseodymium type permanent magnet or a neodymium type permanent
magnet with nickel plating or the like provided on the surface
thereof so as to produce high magnetic forces. The permanent
magnets 31 and 31 are provided such that they oppose the rotating
shaft 6, and the opposing permanent magnets 31 and 31 are embedded
and magnetized to have opposite poles, as shown in FIG. 23.
[0162] The permanent magnets 31SA and 31SB embedded in one side
(e.g., the right side and the upper side in the drawing) from the
rotating shaft 6 are polarized with the same south-seeking poles,
while the permanent magnets 31NA and 31NB embedded in the other
side (e.g., the left side and the lower side in the drawing) are
polarized with the same north-seeking poles. More specifically, the
permanent magnets 31SA, 31SB and the permanent magnets 31NA, 31NB
are disposed to substantially form a rectangular shape around the
rotating shaft 6, and are embedded such that they carry two poles,
namely, the south pole and the north pole, outward in the
circumferential direction of the rotating shaft 6. This enables
torque to be applied to the rotor 5 by the lines of magnetic force
of a primary winding 7A and an auxiliary winding 7B, which will be
discussed hereinafter. The layout of the permanent magnets 31 shown
in FIG. 23 is different from the layout of the permanent magnets 31
shown in FIGS. 2, 3, and 4. The layout of the permanent magnets 31
shown in FIG. 23 may be replaced by the layout shown in FIGS. 2, 3,
and 4. Further alternatively, the permanent magnets 31 shown in
FIGS. 2, 3, and 4 may be arranged as shown in FIG. 23.
[0163] FIG. 24 is an analytical diagram of the magnetic field of
the rotor 5 shown in FIG. 4. In the rotor 5, a magnetic field in
which both permanent magnets 31 and 31 attract each other is
formed; however, only the south-pole side of the magnetic field is
shown in FIG. 24. As may be seen from FIG. 24 and FIG. 4, The
permanent magnets 31 and 31 mounted on the rotor 5 and opposing the
rotating shaft 6 are arranged to have opposite magnetic poles from
each other against the rotating shaft 6. The magnetic flux of the
rotor 5 with this arrangement is 0.294.times.10.sup.-2[Wb],
although it depends on the magnetic force of the permanent magnets
31 and other conditions.
[0164] A lubricant runs between the rotor 5 and the rotating shaft
6, and the rotor yoke 5A in which the permanent magnets 31 have
been inserted is formed of a ferromagnetic member. Therefore, most
lines of magnetic force (hereinafter referred to as the "magnetic
field") of both permanent magnets 31 and 31 pass through the rotor
yoke 5A and attract each other. A part of the magnetic field
bypasses the rotor yoke 5A and passes through the rotating shaft 6
via a void (including a lubricant). It is already well known that a
magnetic member easily passes a magnetic field, while the void,
which is not a magnetic member, restrains the passage of the
magnetic field; therefore, no further explanation will be
given.
[0165] Measurement results have shown that the magnetic flux
density of the rotating shaft 6 ranges from about 0.3 teslas up to
about 0.42 teslas, as shown in FIG. 25, although it depends on the
magnetic forces of the permanent magnets 31 and other conditions.
More specifically, the magnetic field of the permanent magnets 31
that passes through the rotating shaft 6 magnetizes the rotating
shaft 6. The different permanent magnets 31 and 31 are laterally
disposed in FIG. 4, and the different permanent magnets 31 and 31
are vertically disposed in FIG. 24; however, both are the same
permanent magnets. In the drawings, the south magnetic pole of the
permanent magnets 31 is shown, and the north magnetic pole has been
omitted, because a magnetic field symmetrical to that of the south
magnetic pole is produced on the north magnetic pole side.
[0166] FIG. 26 is an analytical diagram of a magnetic field
produced when the rotor 5 of FIG. 24 is provided with voids 5D. The
voids 5D are arcuately formed in the rotor yoke 5A around the
rotating shaft 6 and formed such that they are spaced away from the
rotating shaft 6 by a predetermined distance and they penetrate in
the direction in which the rotating shaft 6 extends. The voids 5D
are laterally spaced away from each other by a predetermined
dimension from a point where the permanent magnet 31 is closest to
the rotating shaft 6, and the voids 5D are extended therefrom for a
predetermined length and arcuately formed around the rotating shaft
6. More specifically, since a magnetic field is hardly formed in
the voids 5D, so that the rotor 5 is provided with the voids 5D to
restrain the passage of a magnetic field so as to alter the
direction of the magnetic field in the rotor 5. The magnetic flux
force of the rotor 5 in this case is 0.294.times.10.sup.-2
[Wb].
[0167] In this case, the voids 5D provided in the rotor yoke 5A are
formed around the rotating shaft 6, and the magnetic field is
accordingly formed around the rotating shaft 6. However, a part of
the magnetic field of the two permanent magnets 31 and 31 passes
between the two voids 5D and enter the rotating shaft 6. The
magnetic flux density of the rotating shaft 6 ranges from about
0.25 teslas up to about 0.49 teslas, as shown in FIG. 27. In other
words, since the magnetic field of the permanent magnets 31
undesirably passes between the void 5D and the void 5D spaced away
from each other by the predetermined dimension, the rotating shaft
6 located therebetween is magnetized.
[0168] FIG. 28 is an analytical diagram of a magnetic field
produced when the rotor 5 is provided with a plurality of voids 5D
at positions different from those of the voids 5D shown in FIG. 26.
A void 5D is arcuately formed in the rotor yoke 5A around the
rotating shaft 6 and formed such that they are spaced away from the
rotating shaft 6 by a predetermined distance and it penetrates in
the direction in which the rotating shaft 6 extends, as mentioned
above. The void 5D is laterally and arcuately formed for a
predetermined dimension from a point where the permanent magnet 31
is closest to the rotating shaft 6. In addition, arcuate voids 5D
are further formed around the rotating shaft 6, with predetermined
dimensions allowed from both ends of the void 5D. In other words,
the void 5D having a predetermined width is provided at the central
portion where the permanent magnets 31 and 31 provided in the rotor
5 attract each other so as to reduce the magnetic field passing
through the rotor 5, thereby altering the direction of the magnetic
field in the rotor 5. The magnetic flux of the rotor 5 in this case
is 0.288.times.10.sup.-2 [Wb].
[0169] In this case also, the voids 5D provided in the rotor yoke
5A are formed around the rotating shaft 6; however, the one of the
voids 5D laterally extends by a predetermined dimension from the
point where the permanent magnet 31 is closest to the rotating
shaft 6, and the magnetic field reduces when it passes through the
void 5D. Actually, however, the magnetic field bypasses the voids
5D, as illustrated. In this case, the magnetic field formed by the
permanent magnets 31 and 31 bypasses the rotating shaft 6 because
of the voids 5D. The magnetic flux density of the rotating shaft 6
ranges from about 0.23 teslas up to about 0.32 teslas, as shown in
FIG. 29. In other words, since the magnetic field of the permanent
magnets 31 avoids passing through the voids 5D, the rotating shaft
6 is hardly magnetized.
[0170] FIG. 30 is an analytical diagram showing a magnetic field of
the rotor 5 when the permanent magnets 31 are disposed at different
positions. In this case, permanent magnets 31SB are provided
between two permanent magnets 31SA (one of the permanent magnets
31SA is not shown) that oppose the rotating shaft 6 . The permanent
magnets 31SB and 31SB are disposed such that they are inclined with
respect to the center of the permanent magnet 31SA provided on the
outer side of the rotor 5. In other words, the permanent magnets
31SB are inclined in the direction such that the flow of the
magnetic field of the permanent magnet 31SA moves away from the
rotating shaft 6. This means that the permanent magnets 31SB and
31SB for drawing in the magnetic field produced by the permanent
magnet 31SA are disposed on both sides of the line that passes the
permanent magnets 31SA and the rotating shaft 6.
[0171] Thus, the flow of the magnetic field of the permanent
magnets 31SA is directed toward the permanent magnets 31SB. In
other words, the permanent magnets 31SA and the permanent magnets
31SB are disposed to attract each other thereby to change the
direction of the magnetic field in the rotor 5 so as to cause the
magnetic field to pass through the rotor yoke 5A excluding the
rotating shaft 6. The magnetic flux of the rotor 5 in this case is
0.264.times.10.sup.-2 [Wb]. In this case, the magnetic field
produced by the two permanent magnets 31SA is formed such that it
bypasses the rotating shaft 6 due to the presence of the permanent
magnets 31SB. The magnetic flux density of the rotating shaft 6
ranges from about 0.03 teslas up to about 0.18 teslas, as shown in
FIG. 31. In other words, the magnetic field of the permanent
magnets 31 avoids passing through the rotating shaft 6, so that the
rotating shaft 6 is hardly magnetized.
[0172] Based on the analytical results of the magnetic field of the
rotor 5, the one shown in FIG. 30 wherein the permanent magnets
31SB are differently disposed with respect to the permanent magnet
31SA is most effective for restraining the magnetization of the
rotating shaft 6. This layout of the permanent magnets, however, is
not necessarily fully satisfactory. In comparison, it has been
proven that the rotor 5 shown in FIG. 28 in which the voids 5D are
provided such that they block the magnetic field between the two
permanent magnets 31 and 31, facing against the rotating shaft 6,
provides the greatest magnetic force without causing the rotating
shaft 6 to be magnetized. This means that the experiment results
have shown that providing the rotor yoke 5A with the voids 5D shown
in FIG. 28 makes it possible to prevent iron powder from adhering
to the rotating shaft 6 and restrain the degradation in the
performance of the synchronous induction motor 2. Regarding the
voids 5D, only the void 5D provided at the center between the two
permanent magnets 31 and 31 may be provided.
[0173] Examples of the layout of the two-pole permanent magnets 31
are given by the rotors 5 shown in FIG. 32 through FIG. 37.
Referring to FIG. 32, permanent magnets 31SB, 31SB and permanent
magnets 31NB, 31NB are disposed on the right and left sides of the
rotating shaft 6 of the rotor yoke 5A such that they oppose each
other. These permanent magnets 31SB, 31SB and the permanent magnets
31NB, 31NB are laid out in "V" shapes such that they face toward
the center of the rotating shaft 6. On the outer sides of these
permanent magnets 31 (on the sides away from the rotating shaft 6),
a pair of permanent magnets 31 are disposed, opposing each other,
to have two poles, the one on the right side of the rotating shaft
6 carrying the south pole and the one on the left side thereof
carrying the north pole. Referring to FIG. 33, permanent magnets
31SB, 31SB and permanent magnets 31NB, 31NB are further disposed in
the rotor 5 of FIG. 32 such that they are inclined toward the
rotating shaft 6. The permanent magnets provide two poles, the ones
on the right side of the rotating shaft 6 carrying the south pole,
while the ones on the left side thereof carrying the north
pole.
[0174] Referring now to FIG. 34, two permanent magnets 31 are
disposed in the rotor yoke 5A substantially in "V" shapes such that
they substantially form a diamond shape, laterally opposing each
other, sandwiching the rotating shaft 6. The permanent magnet on
the right side of the rotating shaft 6 carries the south pole,
while the permanent magnet on the left side thereof carries the
north pole. In other words, in the rotors 5 having the permanent
magnets 31 laid out as shown in FIG. 32 through FIG. 34, the
magnetization of the rotating shaft 6 caused by the magnetic forces
of the permanent magnets 31 can be restrained by forming the voids
5D, which is shown in FIG. 28, in the rotor yoke 5A as described
above, the voids being located at the central portion where the
opposing permanent magnets 31 and 31 attract each other.
[0175] Referring to FIG. 35, the rotor yoke 5A is provided with
eight permanent magnets 31. The permanent magnets 31 are disposed
roughly radially, as observed from the rotating shaft 6. More
specifically, the permanent magnets 31 are arranged in an
approximate radial pattern in two rows on each side with
predetermined intervals provided among the permanent magnets and
with a predetermined space laterally provided between the rows on
the right side and the left side such that they oppose each other,
sandwiching the rotating shaft 6. The permanent magnets carry two
poles, the ones on the right side of the rotating shaft 6 carrying
the south pole, while the ones on the left side thereof carrying
the north pole. In FIG. 36, the permanent magnets 31 are arranged
in an approximate radial pattern in three rows on each side with a
predetermined interval laterally provided between the rows. The
permanent magnets carry two poles, the ones on the right side of
the rotating shaft 6 carrying the south pole, while the ones on the
left side thereof carrying the north pole. In other words, in the
rotors 5 shown in FIG. 35 and FIG. 36, the permanent magnets 31 are
radially arranged substantially around the rotating shaft 6, so
that the magnetic field is directed away from the rotating shaft 6,
as illustrated in FIG. 30. Thus, the magnetic field of the two
permanent magnets 31 and 31 disposed to oppose the rotating shaft 6
bypasses the rotating shaft 6; therefore, the rotating shaft 6 will
not be magnetized.
[0176] Referring to FIG. 37, the rotor yoke 5A is provided with six
permanent magnets 31. These permanent magnets 31 are laid out in a
substantially hexagonal shape around the rotating shaft 6. The
permanent magnets 31 have two poles, the ones on the right side of
the rotating shaft 6 carrying the south pole, while the ones on the
left side carrying the north pole. By forming the void 5D shown in
FIG. 28 in the rotor yoke 5A mentioned above at the central portion
where the opposing permanent magnets 31 attract each other, it is
possible to further restrain the rotating shaft 6 from being
magnetized by the magnetic forces of the permanent magnets 31. More
specifically, in the rotor 5 provided with the permanent magnets 31
disposed as shown in FIG. 37, the voids 5D provided in the rotor 5
shown in FIG. 26 cause the magnetic fields of the two opposing
permanent magnets 31 to pass the rotor yoke 5A, bypassing the voids
5D. As a result, the magnetic fields do not pass the rotating shaft
6, so that the rotating shaft 6 is hardly magnetized. Voids 32
shown in FIGS. 33, 34, and 37 intercept the magnetic field formed
between the permanent magnets 31 on the south pole side and the
permanent magnets 31 on the north pole side. The voids 32, however,
are dispensable.
[0177] As described above, the voids 5D are formed at the central
portion of the rotor yoke 5A where the permanent magnets 31 and 31,
which oppose each other with the rotating shaft 6 sandwiched
therebetween and attract each other, and the permanent magnets 31
are arranged such that the magnetic field does not pass through the
rotating shaft 6 or the magnetic field bypasses the rotating shaft
6. With this arrangement, it is possible to restrain the rotating
shaft 6 from being magnetized. This makes it possible to prevent
inconveniences in which iron powder or the like adheres to the
rotating shaft 6 or the rotating shaft 6 and the bearings 17 and 18
wear out due to friction caused by the magnetic forces of the
permanent magnets 31.
[0178] In general, the permanent magnets used with synchronous
induction motors are magnetized in advance at a different place,
then installed in rotors. For this reason, when inserting the
magnetized permanent magnets in rotors, the permanent magnets
attract each other, leading to poor workability. Furthermore, when
inserting a rotor in a stator, the rotor is attracted to a
surrounding surface, posing the problem of degraded assemblability
of a synchronous induction motor.
[0179] In addition, since the permanent magnets are incorporated in
a rotor, the workability in installing the rotor in a stator is
degraded, resulting in assembly failure.
[0180] Referring now to FIG. 38 through FIG. 46, the descriptions
will be given to the structure of a synchronous induction motor
that allows permanent magnets to be inserted in a rotor without the
magnetic attraction problem of the permanent magnets, and that also
features dramatically improved workability of installation. The
descriptions will also be given of a manufacturing method for the
synchronous induction motor.
[0181] The rotor 5 in this case is constructed of a rotor yoke 5A,
die-cast squirrel-cage secondary conductors 5B positioned around
the rotor yoke 5A, a die-cast end ring 69 which is positioned on
the peripheral portion of an end surface of the rotor yoke 5A,
annularly protrudes by a predetermined dimension, and integrally
die-cast with the squirrel-cage secondary conductors 5B, and
permanent magnets 31 embedded in the rotor yoke 5A. The permanent
magnets 31 are magnetized after permanent magnet materials are
inserted in slots 44, which will be discussed hereinafter. The
permanent magnets 31 (31SA and 31SB) embedded in one side (e.g.,
the right side in the drawing) from the rotating shaft 6 are
polarized with the same south pole, while the permanent magnets 31
(31NA and 31NB) embedded in the other side (e.g., the left side in
the drawing) are polarized with the same north pole, as shown in
FIG. 38 and FIG. 39.
[0182] The plurality of squirrel-cage secondary conductors 5B are
provided on the peripheral portion of the rotor yoke 5A and have
aluminum diecast members injection-molded in cylindrical holes (not
shown) formed in the cage in the direction in which the rotating
shaft 6 extends, as described previously. The squirrel-cage
secondary conductors 5B are formed in a so-called skew pattern in
which they are spirally inclined at a predetermined angle in the
circumferential direction of the rotating shaft 6 from one end
toward the other end, as illustrated in FIG. 5.
[0183] The rotor yoke 5A has a plurality of slots 44 (four in this
embodiment) vertically formed with both ends open. The openings at
both ends of the slots 44 are closed by a pair of the end surface
members 66 and 67, respectively, as shown in FIG. 7. When the
squirrel-cage secondary conductors 5B and the end rings 68 and 69
are die-cast, the end surface member 67 is fixed to the rotor yoke
5A by the end ring 69. The end surface member 66 is secured to the
rotor yoke 5A by a plurality of rivets 66A functioning as
fixtures.
[0184] In this case, after the unmagnetized magnet constituents of
the permanent magnets 31 are inserted through the openings of the
slots 44, the openings are closed by the end surface member 66, and
the end surface member 66 is fixed by riveting into engaging holes
5C provided in the rotor yoke 5A by using the rivets 66A. This
secures the magnet constituents in the slots 44. The magnet
constituents are formed of a rare earth type permanent magnet
material of, for example, a praseodymium type permanent magnet or a
neodymium type permanent magnet with nickel plating or the like
provided on the surface thereof, or a ferrite material, that is
capable of exhibiting high magnet characteristics even in a low
magnetizing magnetic field. In this case, the demagnetization
during operation can be restrained by using, for example, a ferrite
magnet or a rare earth type magnet (the coercive force at normal
temperature being 1350 to 2150 kA/m and the coercive force
temperature coefficient being 0.7%/.degree. C. or less).
[0185] If an unmagnetized magnet constituent is inserted in a
rotor, and a stator winding is energized to magnetize the magnet
constituent, the stator winding may be deformed by the
electromagnetic force produced at the magnetization. For this
reason, the stator winding 7 is coated with varnish or a sticking
agent that fuses when heated. The varnish or the sticking agent
that fuses when heated securely prevents the deformation of a
winding end of the stator winding 7 and the degradation of the
coating of the winding caused by heat if the stator winding 7
becomes hot from the heat generated by itself when the magnet
constituent is magnetized.
[0186] There is another problem in that the quality of a
synchronous induction motor is deteriorated. To solve the problem,
a predetermined voltage and a predetermined current are supplied to
one phase or two phases of the stator winding so as to magnetize
the unmagnetized magnet constituents fixed in the slots 44 provided
in the rotor yoke 5A. This permits better magnetizing performance
than that obtained by energizing the primary winding 7A and the
auxiliary winding 7B at the same time. Hence, the unmagnetized
magnet constituents can be intensely magnetized.
[0187] The rotor 5 is provided with four permanent magnets 31 and
31 formed of the magnetized magnet constituents that oppose the
rotating shaft 6. The opposing permanent magnets 31 and 31 are
disposed with opposite magnetic poles, as shown in FIG. 40.
Permanent magnets 31SA and 31SB embedded in one side of the
rotating shaft 6 (e.g., upper and lower on the right side in the
drawing) from the rotating shaft 6 are polarized with the same
south pole, while the permanent magnets 31NA and 31NB embedded in
the other side (e.g., upper and lower on the left side in the
drawing) are polarized with the same north pole.
[0188] More specifically, the permanent magnets 31SA, 31SB and the
permanent magnets 31NA, 31NB are disposed to substantially form a
rectangular shape around the rotating shaft 6, and are embedded
such that they carry two poles, namely, the south pole and the
north pole, outward in the circumferential direction of the
rotating shaft 6. This enables torque to be applied to the rotor 5
by the magnetic forces of a primary winding 7A and an auxiliary
winding 7B, which will be discussed hereinafter. The layout of the
permanent magnets 31 shown in FIG. 40 is different from the layout
of the permanent magnets 31 shown in FIG. 38; however, the layout
of the permanent magnets 31 shown in FIG. 40 may be replaced by the
layout shown in FIG. 38. In this case, however, the riveting
positions of the rivets 66A have to be changed. Further
alternatively, the permanent magnets 31 shown in FIG. 38 may be
arranged as shown in FIG. 40.
[0189] Thus, after the magnet constituents of the permanent magnets
31 are embedded in the rotor yoke 5A, the magnet constituents are
magnetized by current passed through the stator winding 7. Hence,
when the rotor 5 is inserted in the stator 4, a problem can be
solved in which the permanent magnets 31 inserted in the stator 4
cause magnetic attraction to the surrounding. This arrangement
makes it possible to prevent inconvenience of lower productivity of
the synchronous induction motor 2, thus permitting improved
assemblability of the synchronous induction motor 2.
[0190] Another rotor 5 is shown in FIG. 41. In this case, the rotor
yoke 5A has two magnet constituents embedded therein. The two
plate-like magnet constituents are arranged in parallel to each
other, sandwiching the rotating shaft 6 and embedded in slots 44
vertically formed in the rotor yoke 5A so that they penetrate the
rotor yoke 5A. The magnet constituents are formed of a rare earth
type or ferrite material, as mentioned above.
[0191] Referring now to FIG. 46, a three-phase, two-pole
synchronous induction motor 2A will be described. The synchronous
induction motor 2A is installed in the hermetic electric compressor
C, as in the case of the synchronous induction motor 2 described
above. FIG. 46 is an electrical circuit diagram of the three-phase,
two-pole synchronous induction motor 2A. In the drawing, the
synchronous induction motor 2A is equipped with a three-phase
stator winding 75 constructed of a winding 75A, a winding 75B, and
a winding 75C. The winding 75A, the winding 75B, and the winding
75C of the stator winding 75 are connected to a three-phase
alternating current commercial power source AC3 through the
intermediary of a power switch 77. Current-sensitive line current
detectors 76 for detecting line current are provided on the lines
connected to the winding 75A, the winding 75B, and the winding 75C.
The power switch 77 functions also as a protective switch that cuts
off the supply of power to the stator winding 7 if any of the line
current detectors 76 senses a predetermined current. The rest of
the configuration is as described above.
[0192] The two unmagnetized magnet constituents fixed in the slots
44 provided in the rotor yoke 5A are magnetized by a predetermined
voltage and a predetermined current supplied to one phase, two
phases, or three phases of the stator winding. Thus, the two
opposing magnet constituents are magnetized into the permanent
magnets 31 having opposite magnetic polarities. To be more
specific, the rotor 5 includes opposing permanent magnets 31
magnetized to have opposite magnetic polarities, namely, permanent
magnets 31SA on the right side and permanent magnets 31NA on the
left side.
[0193] Another example of the rotor 5 is shown in FIG. 42. In this
case also, the rotor yoke 5A is provided with two magnet
constituents. The two magnet constituents are embedded in slots 44
vertically formed in the rotor yoke 5A so that they penetrate the
rotor yoke 5A. The magnet constituents are disposed in arcuate
shapes inside the squirrel-cage secondary conductor 5B with a
predetermined interval allowed therebetween, and are embedded such
that both ends of the two arcuate magnet constituents are close to
each other. The magnet constituents is formed of a rare earth type
or ferrite material, as mentioned above.
[0194] The two unmagnetized magnet constituents fixed in the slots
44 provided in the rotor yoke 5A are magnetized by a predetermined
voltage and a predetermined current supplied to one phase, two
phases, or three phases of the stator winding. Thus, the two
opposing magnet constituents are magnetized into the permanent
magnets 31 having opposite magnetic polarities to constitute the
rotor 5. To be more specific, the rotor 5 includes opposing
permanent magnets 31 magnetized to have opposite magnetic
polarities, namely, a permanent magnet 31SA on the right side and a
permanent magnet 31NA on the left side.
[0195] Another example of the rotor 5 is shown in FIG. 43. In this
case, the rotor yoke 5A is provided with four magnet constituents.
The four magnet constituents are individually embedded in slots 44
vertically formed in the rotor yoke 5A such that they penetrate the
rotor yoke 5A. The magnet constituents are embedded inside the
squirrel-cage secondary conductor 5B such that two sets of
permanent magnets 31, each set consisting of two magnet
constituents and shaping substantially like "V", oppose each other,
sandwiching the rotating shaft 6. The magnet constituents are
arranged such that they form substantially a diamond shape, as
observed from above. The magnet constituents are formed of a rare
earth type or ferrite material, as previously mentioned. Voids 32
function to intercept the magnetic field formed between the south
pole (permanent magnets 31SA, 31SB) and the north pole (permanent
magnets 31NA, 31NB). The voids 32, however, are dispensable.
[0196] The unmagnetized magnet constituents fixed in the slots 44
provided in the rotor yoke 5A are magnetized by a predetermined
voltage and a predetermined current supplied to one phase, two
phases, or three phases of the stator winding. Thus, the opposing
sets of magnet constituents are magnetized into the sets of
permanent magnets 31 carrying opposite magnetic polarities. To be
more specific, the rotor 5 includes opposing sets of permanent
magnets 31 magnetized to have opposite magnetic polarities, namely,
two upper and lower permanent magnet 31SA and 31SB on the right
side and two upper and lower permanent magnet 31NA and 31NB on the
left side.
[0197] Another example of the rotor 5 is shown in FIG. 44. In this
case, the rotor yoke 5A is provided with six magnet constituents.
The six magnet constituents are individually embedded in slots 44
vertically formed in the rotor yoke 5A such that they penetrate the
rotor yoke 5A. The magnet constituents are arranged inside the
squirrel-cage secondary conductor 5B such that two sets, each set
consisting of three magnet constituents, oppose each other,
sandwiching the rotating shaft 6 therebetween, and are shaped like
a hexagon. The magnet constituents are formed of a rare earth type
or ferrite material, as previously mentioned.
[0198] The unmagnetized magnet constituents fixed in the slots 44
provided in the rotor yoke 5A are magnetized by a predetermined
voltage and a predetermined current supplied to one phase, two
phases, or three phases of the stator winding. Thus, the opposing
sets of magnet constituents are magnetized into the sets of
permanent magnets 31 carrying opposite magnetic polarities. To be
more specific, the rotor 5 includes opposing sets of permanent
magnets 31 magnetized to have opposite magnetic polarities, namely,
three permanent magnets 31SA, 31SB, and 31SC on the right side and
three permanent magnets 31NA, 31NB, and 31NC on the left side.
[0199] Another example of the rotor 5 is shown in FIG. 45. In this
case, the rotor yoke 5A is provided with eight magnet constituents.
The eight magnet constituents are individually embedded in slots 44
vertically formed in the rotor yoke 5A such that they penetrate the
rotor yoke 5A. The magnet constituents are arranged inside the
squirrel-cage secondary conductor 5B such that two sets, each set
consisting of four magnet constituents, oppose each other,
sandwiching the rotating shaft 6 therebetween, and are shaped like
an octagon. The magnet constituents are formed of a rare earth type
or ferrite material, as previously mentioned.
[0200] The unmagnetized magnet constituents fixed in the slots 44
provided in the rotor yoke 5A are magnetized by a predetermined
voltage and a predetermined current supplied to one phase, two
phases, or three phases of the stator winding. Thus, the opposing
sets of magnet constituents are magnetized into the sets of
permanent magnets 31 carrying opposite magnetic polarities. To be
more specific, the rotor 5 includes opposing sets of permanent
magnets 31 magnetized to have opposite magnetic polarities, namely,
four permanent magnets 31SA, 31SB, 31SC, and 31SD on the right side
and four permanent magnets 31NA, 31NB, 31NC, and 31ND on the left
side.
[0201] Thus, it is possible to magnetize a plurality of
unmagnetized magnet constituents inserted in the rotor 5 either at
once or in a plurality of number of times. This arrangement makes
it possible to energize either one phase or two phases of windings
to effect the magnetization if a winding or the like deforms due to
heat generated during magnetization. Even if windings are not
deformed by heat generated during magnetization, either one phase
or two phases of windings may be selected and energized to
magnetize at once. This makes it possible to efficiently magnetize
a plurality of unmagnetized magnet constituents inserted in the
rotor 5, leading to dramatically improved productivity of the
synchronous induction motor 2.
[0202] An air conditioner or an electric refrigerator or the like
requires large motion torque at the time of start-up, so that it
incorporates a motor that provides larger motion torque than steady
motion torque required for normal operation. Increasing the motion
torque for starting a synchronous induction motor inevitably
increases power consumed during normal operation. Therefore, the
motion torque for starting the motor used in a hermetic electric
compressor constituting a refrigerating cycle of a refrigerator or
an air conditioner has not been entirely adequate in achieving
higher efficiency to meet recent energy regulations. For this
reason, there has been demand for developing a drive unit for a
synchronous induction motor that consumes less power during normal
operation and secures sufficient motion torque at a start-up at the
same time.
[0203] Referring to FIG. 47 through FIG. 52, the descriptions will
now be given of a drive unit for a synchronous induction motor that
consumes less power during normal operation and provides high
motion torque at a start-up.
[0204] FIG. 47 is an electrical circuit diagram of a drive unit T1
of a synchronous induction motor 2 that exhibits the aforesaid
features. Referring to FIG. 47, the synchronous induction motor 2
that receives power from a single-phase alternating current
commercial power source AC is equipped with a stator winding 7
constructed of a primary winding 7A and an auxiliary winding 7B.
One end of the primary winding 7A is connected to one end of the
single-phase alternating current commercial power source AC, and
the other end thereof is connected to the other end of the
single-phase alternating current commercial power source AC through
the intermediary of a socket terminal 51. One end of the auxiliary
winding 7B is connected to one end of the single-phase alternating
current commercial power source AC, and the other end thereof is
connected to the other end of the single-phase alternating current
commercial power source AC through the intermediary of a socket
terminal 51 and an operating capacitor 47. A power switch 49 is
constituted by a current-sensitive type line current sensor for
detecting line current and an overload relay that serves also as a
protective switch used to supply power from the single-phase
alternating current commercial power source AC to the stator
winding 7 and to cut off the supply of power to the stator winding
7. The operating capacitor 47 is set to have a capacitance suited
for start-up and steady operation of the synchronous induction
motor 2.
[0205] When the power switch 49 is turned ON to supply power from
the single-phase alternating current commercial power source AC,
the parallel circuit of the operating capacitor 47 and the primary
winding 7A is connected to the auxiliary winding 7B. By the current
phase difference between the primary winding 7A and the auxiliary
winding 7B, the synchronous induction motor 2 obtains a start-up
motion torque to start running. The synchronous induction motor 2
continues its steady operation from the current phase difference
between the primary winding 7A and the auxiliary winding 7B
produced by the operating capacitor 47. In this case, the operating
capacitor 47 serves also as a start-up capacitor.
[0206] FIG. 48 is an electrical circuit diagram of another drive
unit T2 for a synchronous induction motor 2. Referring to FIG. 48,
the synchronous induction motor 2 receiving power from a
single-phase alternating current commercial power source AC is also
equipped with a stator winding 7 constructed of a primary winding
7A and an auxiliary winding 7B. The stator winding 7 is connected
to the single-phase alternating current commercial power source AC
through the intermediary of a power switch 49. The primary winding
7A connected to one end of the single-phase alternating current
commercial power source AC is connected to the other end of the
single-phase alternating current commercial power source AC through
the intermediary of a socket terminal 51. The auxiliary winding 7B
connected to one end of the single-phase alternating current
commercial power source AC is connected to the power switch 49
through the intermediary of the socket terminal 51 and a relay coil
45A of a start-up relay 45.
[0207] The auxiliary winding 7B is connected in series to the other
end of the single-phase alternating current commercial power source
AC through the intermediary of a socket terminal 51, a start-up
relay contact 45B of the start-up relay 45, and a start-up
capacitor 48. The operating capacitor 47 is connected in parallel
to the start-up relay contact 45B and the start-up capacitor 48.
The operating capacitor 47 is set to provide a capacitance suited
for steady operation. In a state wherein the operating capacitor 47
and the start-up capacitor 48 are connected in parallel, the
capacitors 47 and 48 are set to capacitances suited for a start-up.
Very little current passes the relay coil 45A at an operation start
when large current passes through the synchronous induction motor
2. When the synchronous induction motor 2 moves to its steady
operation with the start-up relay contact 45B closed, current
passes through the relay coil 45A, and the start-up relay contact
45B is opened, isolating the start-up capacitor 48.
[0208] The moment the power switch 49 is turned ON, current flows
from the single-phase alternating current commercial power source
AC to the primary winding 7A and the auxiliary winding 7B. When
large current passes through the auxiliary winding 7B at the
start-up of the synchronous induction motor 2, very little current
passes through the relay coil 45A; therefore, the start-up relay
contact 45B of the start-up relay 45 remains closed, and the
auxiliary winding 7B provides start-up motion torque from the
current phase difference from the primary winding 7A provided by
the operating capacitor 47 and the start-up capacitor 48 connected
in parallel thereto, thus causing the synchronous induction motor 2
to start running. As the synchronous induction motor 2 shifts to
its steady operation, the current passing through the auxiliary
winding 7B decreases, causing current to pass through the relay
coil 45A. The magnetomotive force of the relay coil 45A turns the
power switch 49 OFF to isolate the start-up capacitor 48. The
synchronous induction motor 2 continues its steady operation by the
current phase difference between the primary winding 7A and the
auxiliary winding 7B produced by the operating capacitor 47.
Alternatively, the use of the start-up relay 45 may be replaced by
current control based on a thyristor.
[0209] FIG. 49 is an electrical circuit diagram of another drive
unit T3 for the synchronous induction motor 2. Referring to FIG.
49, the synchronous induction motor 2 receiving power from a
single-phase alternating current commercial power source AC is also
equipped with a stator winding 7 constructed of a primary winding
7A and an auxiliary winding 7B. The stator winding 7 is connected
to the single-phase alternating current commercial power source AC
through the intermediary of a power switch 49. One end of the
primary winding 7A is connected to one end of the single-phase
alternating current commercial power source AC, and the other end
thereof is connected to the other end of the single-phase
alternating current commercial power source AC. One end of the
auxiliary winding 7B is connected to one end of the single-phase
alternating current commercial power source AC, and the other end
thereof is connected to the other end of the single-phase
alternating current commercial power source AC through the
intermediary of a positive thermistor 46 (hereinafter referred to
as "PTC). An operating capacitor 47 is connected in parallel to the
PTC 46. The PTC 46 is a semiconductor device whose resistance value
increases with increasing temperature. The resistance value of the
PTC 46 is low when the synchronous induction motor 2 is started,
but it increases as the PTC 46 generates heat due to the passage of
current.
[0210] The moment the power switch 49 is turned ON, current flows
from the single-phase alternating current commercial power source
AC to the primary winding 7A and the auxiliary winding 7B, causing
the synchronous induction motor 2 to start up. When the synchronous
induction motor 2 is started up, the temperature of the PTC 46 is
low and its resistance value is low; therefore, large current
passes through the PTC 46, and large current accordingly passes
through the auxiliary winding 7B (the current passing through the
operating capacitor 47 being small). This energization causes the
PTC 46 to start self-heating, and the resistance value of the PTC
46 increases accordingly until very little current passes through
the PTC 46 itself. Thus, the synchronous induction motor 2
continues steady operation from the current phase difference
between the primary winding 7A and the auxiliary winding 7B by the
operating capacitor 47.
[0211] FIG. 50 is an electrical circuit diagram of another drive
unit T4 for the synchronous induction motor 2. The construction of
the drive unit T4 is the same as that shown in FIG. 9. The
construction will be explained again in detail. The synchronous
induction motor 2 receiving power from a single-phase alternating
current commercial power source AC is also equipped with a stator
winding 7 constructed of a primary winding 7A and an auxiliary
winding 7B. The stator winding 7 is connected to the single-phase
alternating current commercial power source AC through the
intermediary of a power switch 49. One end of the primary winding
7A is connected to one end of the single-phase alternating current
commercial power source AC, and the other end thereof is connected
to the other end of the single-phase alternating current commercial
power source AC. One end of the auxiliary winding 7B is connected
to one end of the single-phase alternating current commercial power
source AC, and the other end thereof is connected in series to the
other end of the single-phase alternating current commercial power
source AC through the intermediary of a PTC 46 and a start-up
capacitor 48. An operating capacitor 47 is connected in parallel to
the PTC 46 and the start-up capacitor 48.
[0212] When the power switch 49 is closed, current flows from the
single-phase alternating current commercial power source AC to the
primary winding 7A and the auxiliary winding 7B. When the
synchronous induction motor 2 is started up, the temperature of the
PTC 46 is low and the resistance value thereof is also low, so that
large current passes through the PTC 46 and large current
accordingly passes through the auxiliary winding 7B. The auxiliary
winding 7B obtains start-up torque from the current phase
difference between itself and the primary winding 7A produced by
the operating capacitor 47 and the start-up capacitor 48 connected
in parallel, thus causing the synchronous induction motor 2 to
start running. This energization causes the PTC 46 to start
self-heating, and the resistance value of the PTC 46 increases
accordingly until very little current passes through the PTC 46
itself. Thus, the start-up capacitor 48 is isolated, and the
synchronous induction motor 2 continues steady operation from the
current phase difference between the primary winding 7A and the
auxiliary winding 7B by the operating capacitor 47.
[0213] FIG. 51 shows the relationship between rotating torque T
provided by the electric circuit of each of the drive units T1, T2,
T3, and T4 set forth above, and a number of revolutions n. In the
chart, the axis of ordinates indicates a rotating torque T, the
rotating torque T is the smallest at the bottom, and is higher at a
higher level. The axis of abscissa indicates the number of
revolutions n, the left end thereof being the smallest number of
revolutions n, while the right end being the largest number of
revolutions n. The two-dot chain curve denotes the rotating torque
T in relation to the number of revolutions n of the drive unit T1,
and the solid-line curve denotes the rotating torque T in relation
to the number of revolutions n of the drive unit T3. The dashed
line curve denotes the rotating torque T in relation to the number
of revolutions n of the drive unit T4, and the one-dot chain curve
denotes the rotating torque T in relation to the number of
revolutions n of the drive unit T2.
[0214] As can be seen from the chart, the drive unit T1 having a
single capacitor that serves as the starting capacitor 48 and the
operating capacitor 47 exhibits low start-up operating torque and
low steady operating torque. The drive unit T1, however, obviates
the need for the start-up relay 45 and other elements, so that it
is used with an air conditioner or other equipment, such as an
electric refrigerator, that has relatively low start-up operating
torque and steady operating torque.
[0215] The drive unit T2 that switches between the start-up
capacitor 48 and the operating capacitor 47 by the start-up relay
45 provides higher start-up operating torque. As the number of
revolutions n of the synchronous induction motor 2 increases,
leading to the shift to the steady operation mode, current passes
through the relay coil 45A, causing the start-up relay contact 45B
to open thereby to isolate the start-up capacitor 48. Thereafter,
the drive unit T2 performs the same operation as that of the drive
unit T3 at the rotating torque T in relation to the number of
revolutions n. Thus, the operating torque for starting up the
synchronous induction motor 2 can be increased, while the power
consumed during the steady operation can be reduced, permitting the
synchronous induction motor 2 to be operated at extremely high
efficiency. The drive unit T2 provides higher operating torque for
start-up and higher operating torque for steady operation, so it is
used with an air conditioner or other equipment, such as an
electric refrigerator, that has relatively high start-up operating
torque and steady operating torque.
[0216] The drive unit T3 that uses the PTC 46, which is a
semiconductor device whose resistance value increases with
increasing temperature, and the operating capacitor 47 provides a
higher start-up rotating torque than the drive unit T1. The drive
unit T3 obviates the need for the start-up relay 45 and other
devices, and secures higher reliability. This makes it possible to
allow a higher operating torque to be obtained at the start-up of
the synchronous induction motor 2, and to reduce the power consumed
during normal operation, thus enabling the synchronous induction
motor 2 to be operated with extremely high efficiency. The drive
unit T3, therefore, is used with an air conditioner or other
equipment, such as an electric refrigerator, that has relatively
low start-up operating torque and steady operating torque and is
required to exhibit high reliability.
[0217] The drive unit T4 that uses the PTC 46, which is a
semiconductor device whose resistance value increases with
increasing temperature, the start-up capacitor 48, and the
operating capacitor 47 provides a still higher start-up rotating
torque T than the drive unit T3, permitting even higher reliability
to be achieved. This makes it possible to allow a higher operating
torque to be obtained at the start-up of the synchronous induction
motor 2, and to reduce the power consumed during normal operation,
thus enabling the synchronous induction motor 2 to be operated with
extremely high efficiency. The drive unit T4, therefore, is used
with an air conditioner or other equipment, such as an electric
refrigerator, that has relatively high start-up operating torque
and steady operating torque and is required to exhibit high
reliability.
[0218] FIG. 52 is a refrigerant circuit of an air conditioner or
other equipment, such as an electric refrigerator, that uses a
hermetic electric compressor C incorporating a synchronous
induction motor 2. The refrigerant circuit has added a liquid
injection circuit 58 to the refrigerant circuit shown in FIG. 8. A
receiver tank 29 provided in the refrigerant circuit is connected
to a compressor 3 of the hermetic electric compressor C through the
intermediary of a strainer 52, a solenoid valve 53, and a capillary
tube 54.
[0219] The solenoid valve 53 is connected to a thermosensor 57
connected to a pipe 27 located at the discharge end of the
compressor 3, and the opening degree thereof is automatically
adjusted according to the temperature detected by the thermosensor
57. When the compressor 3 of the hermetic electric compressor C is
driven, the refrigerant sealed in the refrigerant circuit is drawn
in through a suction pipe 23 and compressed in steps by a first
rotary cylinder 9 and a second rotary cylinder 10, then discharged
into the pipe 27 through a discharge pipe 22. The compressed gas
refrigerant discharged into the pipe 27 flows into a condenser 28
wherein it radiates heat and condenses into a liquid refrigerant
which flows into the receiver tank 29. A part of the liquid
refrigerant leaving the receiver tank 29 flows also into the liquid
injection circuit 58 and further passes through the strainer 52 and
the solenoid valve 53 to reach the capillary tube 54 wherein it is
throttled before being discharged into a compressor 3. The liquid
refrigerant discharged into the compressor 3 evaporates therein
when it absorbs heat so as to cool the compressor 3. This restrains
a temperature rise in the compressor 3 in a cooling operation mode
thereby to protect the compressor 3. The rest of the operation is
the same as previously described.
[0220] Hitherto, the stator winding constituting the synchronous
induction motor of this type of hermetic electric compressor is
thermally protected primarily by actuating a thermostat wrapped
around the stator winding to cut off the supply of power to the
synchronous induction motor. Alternatively, a temperature sensor is
attached to the discharge pipe or the suction pipe of the hermetic
electric compressor or to the outer surface of the hermetic vessel,
and if the temperature of the hermetic electric compressor reaches
a preset value or more, a protective switch is actuated by the
temperature sensor to cut off the supply of power to the
synchronous induction motor so as to protect the hermetic electric
compressor.
[0221] In a conventional hermetic electric compressor, if the
temperature of the stator winding rises due to an overloaded
operation, in order to protect the stator winding of the
synchronous induction motor from being burnt, the thermostat
wrapped around the stator winding is actuated to cut off the supply
of power to the synchronous induction motor. Alternatively, an
expensive circuit device using a thermistor or the like is
installed on the discharge pipe, and if a discharge temperature
reaches a reference level or more, then the supply of power to the
synchronous induction motor is cut off thereby to protect the
synchronous induction motor from abnormal temperatures. In this
case, the difference between the actual temperature of the stator
winding and the discharge temperature greatly varies according to
load conditions, etc. Hence, there has been a problem in that the
operation of the synchronous induction motor is actually continued
while the temperature of the stator winding is higher than the
reference level, leading to a markedly shortened service life of
the synchronous induction motor. There has been another problem in
that the stator winding is burnt.
[0222] There has been still another problem in that a rise in the
temperature of the synchronous induction motor causes the permanent
magnets embedded in the rotor yoke to be thermally demagnetized,
resulting in reduced driving power of the synchronous induction
motor.
[0223] Referring now to FIG. 53 through FIG. 66, a hermetic
electric compressor capable of restraining a rise in temperature of
the stator winding and of securely preventing permanent magnets
from being thermally demagnetized will be described.
[0224] In this case, a hermetic vessel 1 of a hermetic electric
compressor C is divided into two parts, namely, a cylindrical shell
1A having an open upper end and an end cap 1B that closes the open
upper end. An electric unit and a compression unit (hereinafter
referred to as "the synchronous induction motor 2" and "the
compressor 3") are housed in the shell 1A, the end cap 1B is
attached to the shell 1A so as to cover the shell 1A, then they are
sealed by high-frequency welding or the like.
[0225] The hermetic electric compressor C is provided with a
thermistor 46 serving as a thermal protective device whose
resistance value changes with temperature. The thermistor 46 is
attached to a stator winding 7 provided in the hermetic vessel 1 of
the hermetic electric compressor C. The thermistor 46 is secured to
the stator winding 7 by a polyester yarn 70 binding the coil end of
the stator winding 7. Furthermore, the thermistor 46 is connected
to a connection terminal 71 provided on the end cap 1B of the
hermetic vessel 1 by a lead wire 72, as shown in FIG. 53.
[0226] FIG. 54 is an electrical circuit diagram of the synchronous
induction motor 2 in this embodiment. Referring to FIG. 54, the
synchronous induction motor 2, which receives power from a
single-phase alternating current commercial power source AC, is
equipped with a stator winding 7 formed of a primary winding 7A and
an auxiliary winding 7B. One end of the primary winding 7A is
connected to one end of the single-phase alternating current
commercial power source AC, and the other end thereof is connected
to the other end of the power source AC. One end of the auxiliary
winding 7B is connected to one end of the single-phase alternating
current commercial power source AC, and the other end thereof is
connected to the other end of the power source AC through the
intermediary of an operating capacitor 47.
[0227] One end of the auxiliary winding 7B is connected to the
other end of the single-phase alternating current commercial power
source AC through the intermediary of a contact 61B of a start-up
relay 61 and start-up capacitors 48 and 48. These contact 61B and
the start-up capacitors 48 and 48 are connected in series, and the
operating capacitor 47 is connected in parallel to the contact 61B
and the start-up capacitors 48 and 48. The operating capacitor 47
is set to a capacitance suited for steady operation. In the state
wherein the operating capacitor 47 and the start-up capacitors 48
and 48 are connected in parallel, the capacitors 47, 48, and 48 are
set to capacitances suited for start-up. Reference numerals 48A and
48A denote discharge resistors for discharging currents charged in
the start-up capacitors 48 and 48, reference numeral 61A denotes a
start-up relay coil, and reference character PSW denotes a power
switch.
[0228] A control relay 49 is provided that is connected between the
power switch PSW and the stator winding 7 and provided with a
control relay contact 49B to supply power from the single-phase
alternating current commercial power source AC to the stator
winding 7 and to cut off the supply of power to the stator winding
7. A controller 62 controls the supply of power to the synchronous
induction motor 2 according to a change in the resistance value of
the thermistor 46. The controller 62 is connected to the thermistor
46 secured to the stator winding 7 and also connected to a control
relay coil 49A of the control relay 49. Connected to the controller
62 is a current-sensitive line current detector 63 that is
connected to one end of the single-phase alternating current
commercial power source AC and that functions as an overload
protective device for detecting line current.
[0229] When the power switch PSW is turned ON with the control
relay contact 49B closed, current is supplied from the single-phase
alternating current commercial power source AC to the primary
winding 7A and the auxiliary winding 7B. At the start-up of the
synchronous induction motor 2, current passes through a start relay
coil 61A, causing the contact 61B to close. The auxiliary winding
7B obtains start-up torque from the current phase difference
between itself and the primary winding 7A produced by the operating
capacitor 47 and the start-up capacitors 48 and 48 connected in
parallel, thus causing the synchronous induction motor 2 to start
running. After the synchronous induction motor 2 is energized and
starts running, the contact 61B opens after a while to isolate the
start-up capacitors 48 and 48, and the synchronous induction motor
2 continues steady operation from the current phase difference
between the primary winding 7A and the auxiliary winding 7B
produced by the operating capacitor 47. The running synchronous
induction motor 2 operates the hermetic electric compressor C, thus
enabling an air conditioner to effect air conditioning in the room
wherein the air conditioner is installed, or enabling the
refrigerator to effect cooling therein.
[0230] As the hermetic electric compressor C is operated, the
temperature of the compressor 3 rises and the compressor 3 becomes
hot. As the compressor 3 becomes hot, the temperature of the stator
winding 7 rises accordingly. This causes the resistance value of
the thermistor 46 to change, and the temperature rise in the stator
winding 7 is detected. If the detected temperature is higher than a
preset temperature level, then the controller 62 detects that the
temperature of the stator winding 7 is higher than the preset
level, and passes current through the control relay coil 49A to
open the control relay contact 49B thereby to cut off the supply of
power to the stator winding 7. With this arrangement, the supply of
power to the stator winding 7 can be interrupted before the stator
winding 7 generates abnormal heat while the hermetic electric
compressor C is in operation, thus making it possible to securely
restrain damage to the stator winding 7 and the thermal
demagnetization of the permanent magnets 31. The controller 62
causes current to the control relay coil 49A to open the control
relay contact 49B so as to interrupt the supply of power to the
stator winding 7 if it detects that the temperature of the stator
winding 7 is higher than a preset temperature. Alternatively,
however, the controller 62 may control the supply of power to the
synchronous induction motor 2 to reduce the number of revolutions
thereof or to shut off the supply of power to the synchronous
induction motor 2 if the temperature of the hermetic electric
compressor C rises and exceeds a preset temperature level.
[0231] Furthermore, if large current flows into the stator winding
7 due to overloaded operation of the hermetic electric compressor
C, the line current detector 63 detects the large current flow. If
the detected current is larger than a preset current level, then
the controller 62 detects the large current flow into the stator
winding 7, and passes current through the control relay coil 49A to
open the control relay contact 49B so as to cut off the supply of
power to the stator winding 7. With this arrangement, the supply of
power to the stator winding 7 can be interrupted so as to protect
the synchronous induction motor 2 before an overloaded operation of
the hermetic electric compressor C is continued, which would lead
to damage to the hermetic electric compressor C. The controller 62
shuts off the supply of power to the stator winding 7 to protect
the synchronous induction motor 2 in response to a signal issued by
the thermistor 46 or the line current detector 63, whichever issued
the detection signal first.
[0232] FIG. 55 is a longitudinal sectional side view of a part of
another hermetic electric compressor C (the part being in the
vicinity of an end cap 1B). The hermetic electric compressor C
shown in FIG. 55 is equipped with a bimetal switch 64 as a thermal
protector that opens and closes a contact at a predetermined
temperature. The bimetal switch 64 is secured to the stator winding
7 by a polyester yarn 70 for binding a coil end of the stator
winding 7. The bimetal switch 64 is connected between a hermetic
terminal 25 provided on the end cap 1B of the hermetic vessel 1 and
the stator winding 7, and it cuts off the supply of power from the
single-phase alternating current commercial power source AC to the
stator winding 7 by opening the contact 61B if the temperature of
the stator winding 7 exceeds a predetermined temperature level.
[0233] FIG. 56 is an electrical circuit diagram of the synchronous
induction motor 2 of the hermetic electric compressor C shown in
FIG. 55. Referring to FIG. 56, the synchronous induction motor 2,
which receives power from a single-phase alternating current
commercial power source AC through the intermediary of the bimetal
switch 64, is equipped with a stator winding 7 formed of a primary
winding 7A and an auxiliary winding 7B. One end of the primary
winding 7A is connected to one end of the single-phase alternating
current commercial power source AC, and the other end thereof is
connected to the other end of the power source AC. One end of the
auxiliary winding 7B is connected to one end of the single-phase
alternating current commercial power source AC, and the other end
thereof is connected to the other end of the power source AC
through the intermediary of an operating capacitor 47.
[0234] One end of the auxiliary winding 7B is also connected to the
other end of the single-phase alternating current commercial power
source AC through the intermediary of a contact 61B of a start-up
relay 61 and start-up capacitors 48 and 48. These contact 61B and
the start-up capacitors 48 and 48 are connected in series, and the
operating capacitor 47 is connected in parallel to the contact 61B
and the start-up capacitors 48 and 48. The operating capacitor 47
is set to a capacitance suited for steady operation. In the state
wherein the operating capacitor 47 and the start-up capacitors 48
and 48 are connected in parallel, the capacitors 47, 48, and 48 are
set to capacitances suited for start-up. Reference numerals 48A and
48A denote discharge resistors for discharging currents charged in
the start-up capacitors 48 and 48, and reference numeral 61A
denotes a start-up relay coil.
[0235] When the power switch PSW is turned ON, current is supplied
from the single-phase alternating current commercial power source
AC to the primary winding 7A and the auxiliary winding 7B. At the
start-up of the synchronous induction motor 2, current passes
through the start relay coil 61A, causing the contact 61B to close.
The auxiliary winding 7B obtains start-up torque from the current
phase difference between itself and the primary winding 7A produced
by the operating capacitor 47 and the start-up capacitors 48 and 48
connected in parallel, thus causing the synchronous induction motor
2 to start running. After the synchronous induction motor 2 is
energized and starts running, the contact 61B opens after a while
to isolate the start-up capacitors 48 and 48, and the synchronous
induction motor 2 continues steady operation from the current phase
difference between the primary winding 7A and the auxiliary winding
7B produced by the operating capacitor 47. The running synchronous
induction motor 2 operates the hermetic electric compressor C, thus
enabling an air conditioner to effect air conditioning in the room
wherein the air conditioner is installed, or the refrigerator to
effect cooling therein.
[0236] As the hermetic electric compressor C is operated, the
temperature of the compressor 3 rises and the compressor 3 becomes
hot. As the compressor 3 becomes hot, the temperature of the stator
winding 7 rises accordingly. The bimetal switch 64 detects the
temperature of the stator winding 7. If the detected temperature is
higher than a preset temperature level, then the bimetal switch 64
opens the contact to interrupt the supply of power to the stator
winding 7. With this arrangement, the supply of power to the stator
winding 7 can be interrupted before the stator winding 7 generates
abnormal heat while the hermetic electric compressor C is in
operation, thus making it possible to securely restrain damage to
the stator winding 7 and the thermal demagnetization of the
permanent magnets 31 and to protect the hermetic electric
compressor C from damage due to abnormal heat generation.
[0237] FIG. 57 is a longitudinal sectional side view of a part of
another hermetic electric compressor C (the part being in the
vicinity of an end cap 1B). The hermetic electric compressor C
shown in FIG. 57 is equipped with a bimetal switch 64 as a thermal
protector that opens and closes a contact at a predetermined
temperature, as mentioned above. The bimetal switch 64 is directly
connected to a hermetic terminal 25 that extends into a hermetic
vessel 1. The bimetal switch 64 is connected between the hermetic
terminal 25 provided on the end cap 1B of the hermetic vessel 1 and
the stator winding 7, and it cuts off the supply of power from the
single-phase alternating current commercial power source AC to the
stator winding 7 by opening the contact if the temperature in the
hermetic vessel 1 exceeds a predetermined temperature level. The
electrical circuit diagram of the hermetic electric compressor C is
the same as that shown in FIG. 56.
[0238] When the power switch PSW is turned ON, current is supplied
from the single-phase alternating current commercial power source
AC to the primary winding 7A and the auxiliary winding 7B. At the
start-up of the synchronous induction motor 2, current passes
through the start relay coil 61A, causing the contact 61B to close.
The auxiliary winding 7B obtains start-up torque from the current
phase difference between itself and the primary winding 7A produced
by the operating capacitor 47 and the start-up capacitors 48 and 48
connected in parallel, thus causing the synchronous induction motor
2 to start running. After the synchronous induction motor 2 is
energized and starts running, the contact 61B opens after a while
to isolate the start-up capacitors 48 and 48, and the synchronous
induction motor 2 continues steady operation from the current phase
difference between the primary winding 7A and the auxiliary winding
7B produced by the operating capacitor 47. The running synchronous
induction motor 2 operates the hermetic electric compressor C, thus
enabling an air conditioner to effect air conditioning in the room
wherein the air conditioner is installed, or the refrigerator to
effect cooling therein.
[0239] As the hermetic electric compressor C is operated, the
temperature of the compressor 3 rises and becomes hot. As the
compressor 3 becomes hot, the temperature of the stator winding 7
rises, and the temperature inside the end cap 1B also rises
accordingly. As the temperature inside the end cap 1B rises, the
bimetal switch 64 detects the temperature. If the detected
temperature inside the end cap 1B is higher than a preset
temperature level, then the contact is opened to interrupt the
supply of power to the stator winding 7. With this arrangement, the
supply of power to the stator winding 7 can be interrupted before
the stator 4 or the stator winding 7 generates abnormal heat while
the hermetic electric compressor C is in operation, thus making it
possible to securely restrain damage to the stator winding 7 and
the thermal demagnetization of the permanent magnets 31 and to
protect the hermetic electric compressor C from damage due to
abnormal heat generation.
[0240] FIG. 58 is a longitudinal sectional side view of a part of
yet another hermetic electric compressor C (the part being in the
vicinity of an end cap 1B). The hermetic electric compressor C
shown in FIG. 58 is equipped with a thermostat 65 as a thermal
protector that opens and closes a contact at a predetermined
temperature. The thermostat 65 is connected to a connecting
terminal 71 provided on the end cap 1B of a hermetic vessel 1 by a
lead wire 72, and it cuts off the supply of power from the
single-phase alternating current commercial power source AC to the
stator winding 7 by opening the contact if the temperature in the
hermetic vessel 1 exceeds a predetermined temperature level.
[0241] FIG. 59 shows an electrical circuit diagram of the
synchronous induction motor 2 of the hermetic electric compressor C
shown in FIG. 58. Referring to FIG. 59, reference numeral 65
denotes the thermostat. The rest of FIG. 59 is the same as FIG. 54.
When a power switch PSW is turned ON with a control relay contact
49B closed, current is supplied from the single-phase alternating
current commercial power source AC to the primary winding 7A and
the auxiliary winding 7B. At the start-up of the synchronous
induction motor 2, current passes through a start relay coil 61A,
causing the contact 61B to close. The auxiliary winding 7B obtains
start-up torque from the current phase difference between itself
and the primary winding 7A produced by the operating capacitor 47
and the start-up capacitors 48 and 48 connected in parallel
thereto, thus causing the synchronous induction motor 2 to start
running. After the synchronous induction motor 2 is energized and
starts running, the contact 61B opens after a while to isolate the
start-up capacitors 48 and 48, and the synchronous induction motor
2 continues steady operation from the current phase difference
between the primary winding 7A and the auxiliary winding 7B
produced by the operating capacitor 47. The running synchronous
induction motor 2 operates the hermetic electric compressor C, thus
enabling an air conditioner to effect air conditioning in the room
wherein the air conditioner is installed, or enabling the
refrigerator to effect cooling therein.
[0242] As the hermetic electric compressor C is operated, the
temperature of the compressor 3 rises and the compressor 3 becomes
hot. As the compressor 3 becomes hot, the temperature inside the
end cap 1B also rises. This causes the thermostat 65 to detect the
temperature inside the end cap 1B, and if the detected temperature
is higher than a preset temperature level, the contact thereof is
closed. The moment the contact of the thermostat 65 is closed, the
controller 62 causes current to pass through the control relay coil
49A to open the control relay contact 49B thereby to cut off the
supply of power to the stator winding 7. With this arrangement, the
supply of power to the stator winding 7 can be interrupted before
abnormal heat is generated inside the end cap 1B while the hermetic
electric compressor C is in operation, thus making it possible to
securely restrain damage to the stator winding 7 and the thermal
demagnetization of the permanent magnets 31.
[0243] Furthermore, if large current flows into the stator winding
7 due to overloaded operation of the hermetic electric compressor
C, the line current detector 63 detects the large current flow. If
the detected current is larger than a preset current level, then
the controller 62 detects the large current flow into the stator
winding 7, and passes current through the control relay-coil 49A to
open the control relay contact 49B to cut off the supply of power
to the stator winding 7. With this arrangement, the supply of power
to the stator winding 7 can be interrupted so as to protect the
synchronous induction motor 2 before an overloaded operation of the
hermetic electric compressor C is continued, which would lead to
damage to the hermetic electric compressor C. The controller 62
shuts off the supply of power to the stator winding 7 to protect
the synchronous induction motor 2 in response to a signal issued by
the thermostat 65 or the line current detector 63, whichever issued
the detection signal first.
[0244] FIG. 60 is a longitudinal sectional side view of a part of a
further hermetic electric compressor C (the part being in the
vicinity of an end cap 1B). The hermetic electric compressor C
shown in FIG. 60 is provided with a thermostat 65 whose resistance
value changes with temperature. The thermostat 65 is secured to the
stator winding 7 by a polyester yarn 70 for binding a coil end of
the stator winding 7. The thermostat 65 is connected, by a lead
wire 72, also to a connecting terminal 71 provided on the end cap
1B of the hermetic vessel 1.
[0245] FIG. 61 is an electrical circuit diagram of the synchronous
induction motor 2 of the hermetic electric compressor C shown in
FIG. 60. Referring to FIG. 61, the synchronous induction motor 2,
which receives power from a single-phase alternating current
commercial power source AC is equipped with a stator winding 7
formed of a primary winding 7A and an auxiliary winding 7B. One end
of the primary winding 7A is connected to one end of the
single-phase alternating current commercial power source AC, and
the other end thereof is connected to the other end of the power
source AC. One end of the auxiliary winding 7B is connected to one
end of the single-phase alternating current commercial power source
AC, and the other end thereof is connected to the other end of the
power source AC through the intermediary of an operating capacitor
47.
[0246] One end of the auxiliary winding 7B is also connected to the
other end of the single-phase alternating current commercial power
source AC through the intermediary of a contact 61B of a start-up
relay 61 and start-up capacitors 48 and 48. These contact 61B and
the start-up capacitors 48 and 48 are connected in series, and the
operating capacitor 47 is connected in parallel to the contact 61B
and the start-up capacitors 48 and 48. The operating capacitor 47
is set to a capacitance suited for steady operation. In the state
wherein the operating capacitor 47 and the start-up capacitors 48
and 48 are connected in parallel, the capacitors 47, 48, and 48 are
set to capacitances suited for start-up. Reference numerals 48A and
48A denote discharge resistors for discharging currents charged in
the start-up capacitors 48 and 48, reference numeral 61A denotes a
start-up relay coil, and PSW denotes a power switch.
[0247] A control relay 49 is provided that is connected between the
power switch PSW and the stator winding 7 and that serves also as a
protective switch for supplying power from the single-phase
alternating current commercial power source AC to the stator
winding 7 and to cut off the supply of power to the stator winding
7. One end of the thermostat 65 secured to the stator winding 7 is
connected to one end of the single-phase alternating current
commercial power source AC through the intermediary of a relay coil
49A of the control relay 49 and an overload switch 73 functioning
as an overload protector. The other end of the thermostat 65 is
connected to the other end of the single-phase alternating current
commercial power source AC. Reference numeral 49B denotes switch
contacts that cause current to pass through a control relay coil
49A so as to open the control relay 49 if a predetermined overload
current flows into the overload switch 73.
[0248] When the power switch PSW is turned ON with the control
relay contact 49B closed, current is supplied from the single-phase
alternating current commercial power source AC to the primary
winding 7A and the auxiliary winding 7B through the intermediary of
an overload switch 73 and the control relay contact 49B. At the
start-up of the synchronous induction motor 2, current passes
through a start relay coil 61A, causing the contact 61B to close.
The auxiliary winding 7B obtains start-up torque from the current
phase difference between itself and the primary winding 7A produced
by the operating capacitor 47 and the start-up capacitors 48 and 48
connected in parallel, thus causing the synchronous induction motor
2 to start running. After the synchronous induction motor 2 is
energized and starts running, the contact 61B opens after a while
to isolate the start-up capacitors 48 and 48, and the synchronous
induction motor 2 continues steady operation from the current phase
difference between the primary winding 7A and the auxiliary winding
7B produced by the operating capacitor 47. The running synchronous
induction motor 2 operates the hermetic electric compressor C, thus
enabling an air conditioner to effect air conditioning in the room
wherein the air conditioner is installed, or enabling the
refrigerator to effect cooling therein.
[0249] As the hermetic electric compressor C is operated, the
temperature of the compressor 3 rises and the compressor 3 becomes
hot. As the compressor 3 becomes hot, the temperature of the stator
winding 7 rises accordingly. The thermostat 65 detects the
temperature, and if the detected temperature is higher than a
preset temperature level, then the contact is closed. This causes
current to pass through the control relay coil 49A to open the
control relay contacts 49B thereby to cut off the supply of power
to the stator winding 7. With this arrangement, the supply of power
to the stator winding 7 can be interrupted before abnormal heat is
generated inside the end cap 1B while the hermetic electric
compressor C is in operation, thus making it possible to securely
restrain damage to the stator winding 7 and the thermal
demagnetization of the permanent magnets 31.
[0250] If overload current flows into the stator winding 7 due to
overloaded operation of the hermetic electric compressor C, the
overload switch 73 detects the overload current. If the detected
current exceeds a preset current value, then the overload switch 73
passes current through the control relay coil 49A to open the
control relay contacts 49B so as to cut off the supply of power to
the stator winding 7. This makes it possible to cut off the supply
of power to the stator winding 7 to protect the synchronous
induction motor 2 before the hermetic electric compressor C is
damaged due to an overloaded operation of the hermetic electric
compressor C. The supply of power to the stator winding 7 is
interrupted in order to protect the synchronous induction motor 2
in response to a signal issued by the thermostat 65 or the overload
switch 73, whichever issued the detection signal first.
[0251] FIG. 62 is a longitudinal sectional side view of a part of
still another hermetic electric compressor C (the part being in the
vicinity of an end cap 1B). The hermetic electric compressor C
shown in FIG. 62 is equipped with an overload switch 73 as an
overload protector. The overload switch 73 is secured to the end
cap 1B of a hermetic vessel 1. More specifically, the overload
switch 73 is secured to a hermetic terminal 25 on the end surface
of the hermetic vessel 1, and opens a contact (not shown) to cut
off the supply of power to the stator winding 7 if a predetermined
overload current passes. Reference numeral 74 denotes a cover for
protecting the hermetic terminal 25 and the overload switch 73, and
reference numeral 75 denotes a nut for securing the cover 74.
[0252] FIG. 63 is an electrical circuit diagram of the synchronous
induction motor 2 of the hermetic electric compressor C shown in
FIG. 62. Referring to FIG. 63, the synchronous induction motor 2,
which receives power from a single-phase alternating current
commercial power source AC through the intermediary of the overload
switch 73 is equipped with a stator winding 7 formed of a primary
winding 7A and an auxiliary winding 7B. One end of the primary
winding 7A is connected to one end of the single-phase alternating
current commercial power source AC, and the other end thereof is
connected to the other end of the power source AC. One end of the
auxiliary winding 7B is connected to one end of the single-phase
alternating current commercial power source AC, and the other end
thereof is connected to the other end of the power source AC
through the intermediary of an operating capacitor 47.
[0253] One end of the auxiliary winding 7B is also connected to the
other end of the single-phase alternating current commercial power
source AC through the intermediary of a contact 61B of a start-up
relay 61 and a start-up capacitor 48. These contact 61B and the
start-up capacitor 48 are connected in series, and the operating
capacitor 47 is connected in parallel to the contact 61B and the
start-up capacitor 48. The operating capacitor 47 is set to a
capacitance suited for steady operation. In the state wherein the
operating capacitor 47 and the start-up capacitor 48 are connected
in parallel, the capacitors 47 and 48 are set to capacitances
suited for start-up. Reference numeral 48A denotes a discharge
resistor for discharging current charged in the start-up capacitor
48, reference numeral 61A denotes a start-up relay coil, and PSW
denotes a power switch.
[0254] When the power switch PSW is turned ON, current is supplied
from the single-phase alternating current commercial power source
AC to the primary winding 7A and the auxiliary winding 7B through
the intermediary of the overload switch 73. At the start-up of the
synchronous induction motor 2, current passes through a start relay
coil 61A, causing the contact 61B to close. The auxiliary winding
7B obtains start-up torque from the current phase difference from
the primary winding 7A produced by the operating capacitor 47 and
the start-up capacitor 48 connected in parallel thereto, thus
causing the synchronous induction motor 2 to start running. After
the synchronous induction motor 2 is energized and starts running,
the contact 61B opens after a while to isolate the start-up
capacitor 48, and the synchronous induction motor 2 continues
steady operation from the current phase difference between the
primary winding 7A and the auxiliary winding 7B produced by the
operating capacitor 47. The running synchronous induction motor 2
operates the hermetic electric compressor C, thus enabling an air
conditioner to effect air conditioning in the room wherein the air
conditioner is installed, or enabling the refrigerator to effect
cooling therein.
[0255] If overload current flows into the stator winding 7 due to
overloaded operation of the hermetic electric compressor C, the
overload switch 73 detects the overload current. If the detected
current exceeds a preset current value, then the overload switch 73
causes the contact to open so as to cut off the supply of power to
the stator winding 7. More specifically, if overload current flows
into the stator winding 7, then the overload switch 73 opens the
contact thereby to interrupt the supply of power from the
single-phase alternating current commercial power source AC to the
stator winding 7. This makes it possible to cut off the supply of
power to the stator winding 7 to protect the synchronous induction
motor 2 before the hermetic electric compressor C is damaged due to
an overloaded operation of the hermetic electric compressor C.
[0256] FIG. 64 is a longitudinal sectional side view of a part of
still another hermetic electric compressor C (the part being in the
vicinity of an end cap 1B). The hermetic electric compressor C
shown in FIG. 64 is equipped with a thermostat 65 functioning as an
overload protector that opens/closes a contact at a predetermined
temperature. The thermostat 65 is secured to the end cap 1B, which
is an outer surface of a hermetic vessel 1. More specifically, the
thermostat 65 is secured to the a hermetic terminal 25 on the end
surface of the hermetic vessel 1, and opens/closes a contact
according to the temperature of the end cap 1B. Reference numeral
74 denotes a cover for protecting the hermetic terminal 25 and the
thermostat 65, and reference numeral 75 denotes a nut for securing
the cover 74.
[0257] FIG. 65 is an electrical circuit diagram of the synchronous
induction motor 2 of the hermetic electric compressor C shown in
FIG. 64. Referring to FIG. 65, the synchronous induction motor 2,
which receives power from a single-phase alternating current
commercial power source AC through the intermediary of the overload
switch 73 and the thermostat 65 is equipped with a stator winding 7
formed of a primary winding 7A and an auxiliary winding 7B. One end
of the primary winding 7A is connected to one end of the
single-phase alternating current commercial power source AC, and
the other end thereof is connected to the other end of the power
source AC. One end of the auxiliary winding 7B is connected to one
end of the single-phase alternating current commercial power source
AC, and the other end thereof is connected to the other end of the
power source AC through the intermediary of an operating capacitor
47.
[0258] One end of the auxiliary winding 7B is also connected to the
other end of the single-phase alternating current commercial power
source AC through the intermediary of a contact 61B of a start-up
relay 61 and a start-up capacitor 48. These contact 61B and the
start-up capacitor 48 are connected in series, and the operating
capacitor 47 is connected in parallel to the contact 61B and the
start-up capacitor 48. The operating capacitor 47 is set to a
capacitance suited for steady operation. In the state wherein the
operating capacitor 47 and the start-up capacitor 48 are connected
in parallel, the capacitors 47 and 48 are set to capacitances
suited for start-up. Reference numeral 48A denotes a discharge
resistor for discharging current charged in the start-up capacitor
48, reference numeral 61A denotes a start-up relay coil, and PSW
denotes a power switch.
[0259] When the power switch PSW is turned ON, current is supplied
from the single-phase alternating current commercial power source
AC to the primary winding 7A and the auxiliary winding 7B. At the
start-up of the synchronous induction motor 2, current passes
through the start relay coil 61A, causing the contact 61B to close.
The auxiliary winding 7B obtains start-up torque from the current
phase difference between itself and the primary winding 7A produced
by the operating capacitor 47 and the start-up capacitor 48
connected in parallel thereto, thus causing the synchronous
induction motor 2 to start running. After the synchronous induction
motor 2 is energized and starts running, the contact 61B opens
after a while to isolate the start-up capacitor 48, and the
synchronous induction motor 2 continues steady operation from the
current phase difference between the primary winding 7A and the
auxiliary winding 7B produced by the operating capacitor 47. The
running synchronous induction motor 2 operates the hermetic
electric compressor C, thus enabling an air conditioner to effect
air conditioning in the room wherein the air conditioner is
installed, or enabling the refrigerator to effect cooling
therein.
[0260] As the hermetic electric compressor C is operated, the
temperature of the compressor 3 rises and the compressor 3 becomes
hot. As the compressor 3 becomes hot, the temperature of the end
cap 1B rises accordingly. The thermostat 65 detects the temperature
of the end cap 1B, and if the temperature of the end cap 1B is
higher than a preset temperature level, then the contact is opened.
This interrupts the supply of power to the stator winding 7. With
this arrangement, the supply of power to the stator winding 7 can
be shut off before abnormal heat is generated inside the end cap 1B
while the hermetic electric compressor C is in operation, thus
making it possible to securely restrain damage to the stator
winding 7 and the thermal demagnetization of the permanent magnets
31.
[0261] If overload current flows into the stator winding 7 due to
overloaded operation of the hermetic electric compressor C, the
overload switch 73 detects the overload current. If the detected
current exceeds a preset current value, then the overload switch 73
opens the contact so as to cut off the supply of power to the
stator winding 7. This makes it possible to cut off the supply of
power to the stator winding 7 to protect the synchronous induction
motor 2 before the hermetic electric compressor C is damaged due to
an overloaded operation of the hermetic electric compressor C. The
supply of power to the stator winding 7 is interrupted in order to
protect the synchronous induction motor 2 in response to a signal
issued by the thermostat 65 or the overload switch 73, whichever
issued the detection signal first.
[0262] FIG. 66 is an electrical circuit diagram of another
synchronous induction motor 2 of the hermetic electric compressor
C. A thermostat 65 is secured to the outer surface of the hermetic
vessel 1, as in the case of the compressor shown in FIG. 64.
Referring to FIG. 66, the synchronous induction motor 2, which
receives power from a single-phase alternating current commercial
power source AC is equipped with a stator winding 7 formed of a
primary winding 7A and an auxiliary winding 7B. One end of the
primary winding 7A is connected to one end of the single-phase
alternating current commercial power source AC, and the other end
thereof is connected to the other end of the power source AC. One
end of the auxiliary winding 7B is connected to one end of the
single-phase alternating current commercial power source AC, and
the other end thereof is connected to the other end of the power
source AC through the intermediary of an operating capacitor 47.
The operating capacitor 47 is set to a capacitance suited for
start-up and steady operation of the synchronous induction motor
2.
[0263] A control relay 49 is provided which is connected between
the power switch PSW and the stator winding 7 and which acts also
as a protective switch for supplying power from the single-phase
alternating current commercial power source AC to the stator
winding 7 and for cutting off the supply of power to the stator
winding 7. A controller 62 is connected to the thermostat 65
secured to the end cap 1B and also connected to a control relay
coil 49A of the control relay 49. Connected to the controller 62 is
a current-sensitive line current detector 63 that is connected to
one end of the single-phase alternating current commercial power
source AC and that functions as an overload protector for detecting
line current. Reference numeral 49B denotes a control relay
contact.
[0264] When the power switch PSW is turned ON to supply power from
the single-phase alternating current commercial power source AC to
the stator winding 7, a parallel circuit of the operating capacitor
47 and the primary winding 7A is connected to the auxiliary winding
7B. The auxiliary winding 7B obtains start-up operating torque
produced by the current phase difference between the primary
winding 7A and the auxiliary winding 7B, thus causing the
synchronous induction motor 2 to start running. The synchronous
induction motor 2 then shifts to the steady operation from the
current phase difference between the primary winding 7A and the
auxiliary winding 7B produced by the operating capacitor 47. In
this case, the operating capacitor 47 serves also as a start-up
capacitor.
[0265] As the hermetic electric compressor C is operated, the
temperature of the compressor 3 rises and the compressor 3 becomes
hot. As the compressor 3 becomes hot, the temperature of the end
cap 1B (the outer surface of the hermetic vessel 1) rises
accordingly. The thermostat 65 detects the temperature of the outer
surface of the hermetic vessel 1, and if the detected temperature
is higher than a preset temperature level, then the contact is
closed. This causes the controller 62 to detect that the
temperature of the outer surface of the hermetic vessel 1 is higher
than the preset temperature and to pass current through the control
relay coil 49A to open the control relay contact 49B thereby to cut
off the supply of power to the stator winding 7. With this
arrangement, the supply of power to the stator winding 7 can be
interrupted before the hermetic vessel 1 develops abnormal heat
while the hermetic electric compressor C is in operation, thus
making it possible to securely restrain damage to the stator
winding 7 and the thermal demagnetization of the permanent magnets
31.
[0266] Furthermore, if large current flows into the stator winding
7 due to an overloaded operation of the hermetic electric
compressor C, the line current detector 63 detects the large
current flow. If the detected current is larger than a preset
current level, then the controller 62 passes current through the
control relay coil 49A to open the control relay contact 49B so as
to cut off the supply of power to the stator winding 7. With this
arrangement, the supply of power to the stator winding 7 can be
interrupted so as to protect the synchronous induction motor 2
before an overloaded operation of the hermetic electric compressor
C is continued, which would lead to damage to the stator winding 7.
The controller 62 shuts off the supply of power to the stator
winding 7 to protect the synchronous induction motor 2 in response
to a signal issued by the thermostat 65 or the line current
detector 63, whichever issued the detection signal first.
[0267] The controller 62 incorporates a timer. The controller 62 is
adapted to restart the supply of current to the synchronous
induction motor 2 after waiting for the elapse of a predetermined
delay time since the supply of current to the synchronous induction
motor 2 was cut off. This means that the controller 62 waits for
the predetermined time counted by the timer before it restarts the
supply of current to the synchronous induction motor 2 after the
supply of current to the synchronous induction motor 2 was cut off.
Thus, since the predetermined delay time is allowed before the
supply of power to the synchronous induction motor 2 is restarted
after the power to the synchronous induction motor was cut off, it
is possible to restrain the rotor 5 from becoming hot due to, for
example, frequent repetition of energizing and de-energizing of the
synchronous induction motor 2 because of a starting failure of the
synchronous induction motor 2. This arrangement make it also
possible to restrain the demagnetization of the permanent magnets
31 embedded in the rotor 5 caused by the heat generated in the
rotor 5.
[0268] As described above, the hermetic electric compressor C is
provided with the thermal protector (the thermistor 46, the bimetal
switch 64, or the thermostat 65) to cut off the supply of power to
the synchronous induction motor 2 in response to a predetermined
temperature rise. Hence, the supply of power to the stator winding
7 can be interrupted before the stator winding 7 generates abnormal
heat while the hermetic electric compressor C is running. This
arrangement makes it possible to restrain the demagnetization of
the permanent magnets 31 embedded in the rotor yoke 5A caused by a
temperature rise, permitting dramatically improved reliability of
the hermetic electric compressor C.
[0269] Moreover, the hermetic electric compressor C is provided
with the overload protector (the line current detector 63 or the
overload switch 73) to cut off the supply of power to the
synchronous induction motor 2 in response to a predetermined
overload current. Hence, the supply of power to the synchronous
induction motor 2 to restrain a temperature rise in the synchronous
induction motor 2 thereby to protect it if the hermetic electric
compressor C is operated under an overload. This makes it possible
to prevent damage to the synchronous induction motor 2, permitting
a markedly prolonged service life of the synchronous induction
motor 2 with resultant markedly improved reliability of the
hermetic electric compressor C.
[0270] In the embodiments, the stainless steel plates have been
used for the end surface members 66 and 67 holding the permanent
magnets 31. Alternatively, however, using aluminum plates that
allow further easier passage of current for the end surface members
66 and 67 will permit a reduction in the secondary resistance,
leading to significantly higher operational performance.
[0271] In the embodiments, the rotary compressor has been used as
an example of the hermetic electric compressor C; however, the
present invention is not limited thereto. The present invention may
be also effectively applied to a hermetic scroll compressor
constituted by a pair of meshed scrolls.
[0272] As described above in detail, according to the present
invention, the synchronous induction motor includes a stator
equipped with a stator winding, a rotor rotating in the stator, a
plurality of secondary conductors which is positioned around a
rotor yoke constituting the rotor and which is formed by die
casting, end rings which are positioned on the peripheral portions
of both end surfaces of the rotor yoke and which are integrally
formed with the secondary conductors by die casting, permanent
magnets inserted in slots formed such that they penetrate the rotor
yoke, and a pair of end surface members formed of a non-magnetic
material that closes the openings of both ends of the slots,
wherein one of the end surface members is secured to the rotor yoke
by one of the end rings when the secondary conductors and end rings
are formed, and the other end surface member is secured to the
rotor yoke by a fixture. Therefore, one of the end surface members
can be secured to the rotor yoke at the same time when the
secondary conductors and the end rings are die-cast.
[0273] With this arrangement, after the permanent magnets are
inserted into the slots, the permanent magnets can be secured to
the rotor merely by securing the other end surface member to the
rotor yoke by a fixture. It is therefore possible to reduce the
number of steps for installing the permanent magnets and to improve
the assemblability, permitting the overall productivity of
synchronous induction motors to be dramatically improved.
[0274] Furthermore, according to the present invention, the
synchronous induction motor includes a stator equipped with a
stator winding, a rotor rotating in the stator, a plurality of
secondary conductors which is positioned around a rotor yoke
constituting the rotor and which is formed by die casting, end
rings which are positioned on the peripheral portions of both end
surfaces of the rotor yoke and which are integrally formed with the
secondary conductors by die casting, permanent magnets inserted in
slots formed such that they penetrate the rotor yoke, and a pair of
end surface members formed of a non-magnetic material that closes
the openings of both ends of the slots, wherein a non-magnetic
member is disposed in contact with the inner sides of the two end
rings to secure the two end surface members by pressing them
against the rotor yoke by the non-magnetic member. It is therefore
possible to increase the sectional areas of the end rings by the
amount provided by pressing the end surface members against rotor
yoke by the non-magnetic member. With this arrangement, the
secondary resistance is decreased by the amount equivalent to the
increase in the sectional areas of the end rings. Hence, the loss
of the rotor can be decreased and the heat generation can be
restrained, and the magnetic forces of the magnets can be
effectively used, making it possible to significantly improve the
running performance of the synchronous induction motor.
[0275] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor rotating in the stator, a plurality of secondary conductors
which is positioned around a rotor yoke constituting the rotor and
which is formed by die casting, end rings which are positioned on
the peripheral portions of both end surfaces of the rotor yoke and
which are integrally formed with the secondary conductors by die
casting, permanent magnets inserted in slots formed such that they
penetrate the rotor yoke, and a pair of end surface members formed
of a non-magnetic material that closes the openings of both ends of
the slots, wherein a balancer formed into a predetermined shape
beforehand is secured by a fixture to the rotor yoke together with
the end surface member. Therefore, the ease of installation of the
balancer can be considerably improved. With this arrangement, it is
no longer necessary to secure the permanent magnets and the
balancer separately, with consequent greater ease of installation.
This permits dramatically improved productivity of the synchronous
induction motor.
[0276] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor rotating in the stator, a plurality of secondary conductors
which is positioned around a rotor yoke constituting the rotor and
which is formed by die casting, end rings which are positioned on
the peripheral portions of both end surfaces of the rotor yoke and
which are integrally formed with the secondary conductors by die
casting, permanent magnets inserted in slots formed such that they
penetrate the rotor yoke, and a pair of end surface members which
is formed of a non-magnetic material and which closes the openings
of both ends of the slots, wherein a plurality of laminated sheet
balancers is secured by a fixture to the rotor yoke together with
the end surface member. Therefore, the ease of installation of the
balancer is improved, permitting dramatically improved productivity
to be achieved. Furthermore, since a plurality of sheet balancers
is laminated, using inexpensive metal sheets for the balancer
allows a considerable reduction in the cost of the balancer. This
leads to a dramatically reduced production cost of the synchronous
induction motor.
[0277] According to the present invention, the synchronous
induction motor is provided with a stator equipped with a stator
winding, a rotor rotating in the stator, a plurality of secondary
conductors which is positioned around a rotor yoke constituting the
rotor and which is formed by die casting, end rings which are
positioned on the peripheral portions of both end surfaces of the
rotor yoke and which are integrally formed with the secondary
conductors by die casting, permanent magnets inserted in slots
formed such that they penetrate the rotor yoke, and a pair of end
surface members formed of a non-magnetic material that closes the
openings of both ends of the slots, wherein at least one of the end
surface members and a balancer are formed into one piece. Hence,
the number of components can be reduced. This permits simpler
installation of the end surface members, resulting in dramatically
improved productivity.
[0278] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor rotating in the stator, a plurality of secondary conductors
which is positioned around a rotor yoke constituting the rotor and
which is formed by die casting, end rings which are positioned on
the peripheral portions of both end surfaces of the rotor yoke and
which are integrally formed with the secondary conductors by die
casting, permanent magnets inserted in slots formed such that they
penetrate the rotor yoke, a pair of end surface members formed of a
non-magnetic material that closes the openings of both ends of the
slots, and a balancer secured by being press-fitted to the inner
side of at least one of the end rings. Hence, the installation of
the balancer can be simplified. This arrangement makes it possible
to significantly improve the productivity of the synchronous
induction motor.
[0279] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor rotating in the stator, a plurality of secondary conductors
which is positioned around a rotor yoke constituting the rotor and
which is formed by die casting, end rings which are positioned on
the peripheral portions of both end surfaces of the rotor yoke and
which are integrally formed with the secondary conductors by die
casting, permanent magnets inserted in slots formed such that they
penetrate the rotor yoke, and a pair of end surface members formed
of a non-magnetic material that closes the openings of both ends of
the slots in which the permanent magnets have been inserted,
wherein the two end surface members are secured to the rotor yoke
by the two end rings when the secondary conductors and the end
rings are formed. This arrangement makes it possible to obviate the
need of, for example, the cumbersome step for inserting the
permanent magnets into the slots, then attaching the end surface
members to both ends of the rotor yoke after die-casting the end
rings, as in the case of a prior art. Thus, the productivity of the
rotor can be dramatically improved.
[0280] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor which is secured to a rotating shaft and which rotates in the
stator, a secondary conductor provided around the rotor yoke
constituting the rotor, and a permanent magnet embedded in the
rotor yoke, wherein a magnetic field produced by the permanent
magnet does not pass through the rotating shaft. Thus, it is
possible to prevent the rotating shaft from being magnetized. This
arrangement makes it possible to prevent iron powder or the like
from adhering to the rotating shaft and to protect the rotating
shaft and a bearing from being worn due to the friction
attributable to the magnetic force of the permanent magnet. This
permits secure prevention of damage to the motor caused by the
friction.
[0281] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor which is secured to a rotating shaft and which rotates in the
stator, a secondary conductor provided around the rotor yoke
constituting the rotor, and a permanent magnet embedded in the
rotor yoke, wherein a magnetic field produced by the permanent
magnet bypasses the rotating shaft. Thus, it is possible to prevent
the rotating shaft from being magnetized. This arrangement makes it
possible to prevent iron powder or the like from adhering to the
rotating shaft and to protect the rotating shaft and a bearing from
being worn due to the friction attributable to the magnetic force
of the permanent magnet. This permits secure prevention of damage
to the motor caused by the friction.
[0282] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor which is secured to a rotating shaft and which rotates in the
stator, a secondary conductor provided around the rotor yoke
constituting the rotor, and a permanent magnet embedded in the
rotor yoke, wherein a magnetic field produced by the permanent
magnet passes through only the rotor yoke, excluding the rotating
shaft. Thus, it is possible to prevent the rotating shaft from
being magnetized. This arrangement makes it possible to prevent
iron powder or the like from adhering to the rotating shaft and to
protect the rotating shaft and a bearing from being worn due to the
friction attributable to the magnetic force of the permanent
magnet. This permits secure prevention of damage to the motor
caused by the friction.
[0283] In the synchronous induction motor in accordance with the
present invention, a void is formed in the rotor yoke between the
permanent magnet and the rotating shaft, so that the passage of the
magnetic field produced by the permanent magnet can be reduced.
Thus, it is possible to prevent the rotating shaft from being
magnetized. This arrangement makes it possible to prevent iron
powder or the like from adhering to the rotating shaft and to
protect the rotating shaft and a bearing from being worn due to the
friction attributable to the magnetic force of the permanent
magnet. This permits secure prevention of damage to the motor
caused by the friction.
[0284] In the synchronous induction motor in accordance with the
present invention, a pair of the permanent magnets is disposed,
sandwiching the rotating shaft therebetween, and permanent magnets
for attracting the magnetic field produced by the paired permanent
magnets are disposed at both ends of a line that passes the paired
permanent magnets and the rotating shaft. It is therefore possible
to prevent the magnetic field produced by the paired permanent
magnets from passing through the rotating shaft. Thus, it is
possible to prevent the rotating shaft from being magnetized. This
arrangement makes it possible to prevent iron powder or the like
from adhering to the rotating shaft and to protect the rotating
shaft and a bearing from being worn due to the friction
attributable to the magnetic force of the permanent magnet. This
permits secure prevention of damage to the motor caused by the
friction.
[0285] In the synchronous induction motor in accordance with the
present invention, the permanent magnets are provided at both ends
of a line that connects two magnetic poles, and the permanent
magnets are radially disposed substantially about the rotating
shaft. Hence, the magnetic field produced by the permanent magnets
can be spaced away from the rotating shaft. Thus, it is possible to
prevent the rotating shaft from being magnetized. This arrangement
makes it possible to prevent iron powder or the like from adhering
to the rotating shaft and to protect the rotating shaft and a
bearing from being worn due to the friction attributable to the
magnetic force of the permanent magnet. This permits secure
prevention of damage to the motor due to the friction.
[0286] According to the present invention, the synchronous
induction motor includes a stator equipped with a stator winding, a
rotor rotating in the stator, a secondary conductor provided around
the rotor yoke constituting the rotor, and a permanent magnet
embedded in the rotor yoke, wherein the permanent magnet is
magnetized by current passed through the stator winding. Hence, for
example, a rotor in which a magnetic material for the permanent
magnet that has not yet been magnetized has been inserted is
installed in the stator, so that the rotor can be inserted into the
stator without being magnetically attracted to its surrounding.
This arrangement makes it possible to prevent inconvenience of
lower productivity of the synchronous induction motor, thus
permitting improved assemblability of the synchronous induction
motor. This allows a synchronous induction motor with high
reliability to be provided.
[0287] In the synchronous induction motor in accordance with the
present invention, the permanent magnet is made of a rare earth
type magnet or a ferrite magnet, so that high magnet characteristic
can be achieved. With this arrangement, the magnitude of the
current passed through the stator winding can be reduced so as to
control the temperature at the time of magnetization to a minimum.
Hence, the deformation of the rotor or the stator or the like that
would be caused by high temperature can be minimized, making it
possible to provide a synchronous induction motor with secured high
quality.
[0288] Especially in the case of a synchronous induction motor,
current passes through the secondary conductor even during normal
synchronous operation, causing the temperature of the entire rotor
to rise. Therefore, a reduction in demagnetization at high
temperature can be restrained by using, for example, a ferrite
magnet or a rare earth type magnet (the coercive force at normal
temperature being 1350 to 2150 kA/m and the coercive force
temperature coefficient being -0.7%/.degree. C. or less).
[0289] In the synchronous induction motor in accordance with the
present invention, the stator winding is of a single-phase
configuration and has a primary winding and an auxiliary winding,
and the permanent magnet is magnetized by the current passed
through either the primary winding or the auxiliary winding. Hence,
it is possible to achieve better magnetizing performance than, for
example, in the case where current is passed through both the
primary winding and the auxiliary winding at the same time. This
allows an unmagnetized magnet material to be intensely
magnetized.
[0290] In the synchronous induction motor in accordance with the
present invention, the stator winding is of a three-phase
configuration that includes a three-phase winding. The permanent
magnet is magnetized by current passed through a single phase, two
phases, or three phases of the stator windings. Therefore, it is
possible to select the phase or phases through which current is to
be passed according to the disposition of the magnet or the
permissible current (against deformation or the like) of the
windings.
[0291] In the synchronous induction motor in accordance with the
present invention, the stator windings are coated with varnish or a
sticking agent that is heated to fuse the windings. Hence, for
example, even if the stator windings generate heat and become hot
when an unmagnetized magnet material inserted into the rotor is
magnetized by passing current through the stator windings, it is
possible to restrain the deformation of winding ends of the stator
windings and the deterioration of winding films caused by the heat.
Thus, since the winding ends of the stator windings do not deform
even if an unmagnetized magnet material inserted into the rotor is
magnetized, a highly reliable synchronous induction motor can be
provided.
[0292] Furthermore, according to the present invention, the
synchronous induction motor in accordance with the present
invention is installed in a compressor, allowing the production
cost of the compressor to be considerably reduced.
[0293] In addition, it is possible to prevent inconveniences in
that iron powder adhere to the rotating shaft of the synchronous
induction motor of the compressor or the rotating shaft is
magnetically attracted to the bearing and wears itself. This makes
it possible to prevent the operation performance of the compressor
from degrading.
[0294] Moreover, according to the present invention, the compressor
is used with an air conditioner or an electric refrigerator or the
like. Hence, the production cost of the air conditioner or the
electric refrigerator can be decreased.
[0295] It is also possible to restrain the degradation of the
operation performance of the air condition or the electric
refrigerator or the like.
[0296] According to the present invention, the manufacturing method
for a synchronous induction motor having a stator equipped with a
stator winding, a rotor rotating in the stator, a secondary
conductor provided around a rotor yoke constituting the rotor, and
a permanent magnet embedded in the rotor yoke, includes a step for
embedding a magnet constituent for the permanent magnet in the
rotor yoke and a step for passing current through the stator
winding to magnetize the magnet constituent. Hence, the rotor can
be inserted into the stator without being magnetically attracted to
its surrounding, permitting dramatically improved assemblability of
the synchronous induction motor. This makes it possible to prevent
an inconvenience of reduced productivity of the synchronous
induction motor, which permits improved assemblability of the
synchronous induction motor. As a result, a highly reliable
synchronous induction motor can be provided.
[0297] In the manufacturing method for the synchronous induction
motor in accordance with the present invention, a rare earth type
or ferrite material is used for the magnet constituent. Therefore,
a high magnet characteristic can be achieved even if, for example,
a magnetizing magnetic field is weak. This makes it possible to
reduce the current passing through the stator winding so as to
minimize a temperature rise that occurs at the time of
magnetization. Thus, the deformation of the rotor or the stator or
the like caused by high temperature can be minimized, ensuring high
quality of the synchronous induction motor.
[0298] In the manufacturing method for the synchronous induction
motor in accordance with the present invention, the stator winding
is of a single-phase configuration and has a primary winding and an
auxiliary winding, and the magnet constituent is magnetized by the
current passed through either the primary winding or the auxiliary
winding. Hence, it is possible to achieve better magnetizing
performance than, for example, in the case where current is passed
through both the primary winding and the auxiliary winding at the
same time. This allows an unmagnetized magnet material to be
intensely magnetized.
[0299] In the manufacturing method for the synchronous induction
motor in accordance with the present invention, the stator winding
is of a three-phase configuration that includes a three-phase
winding. The magnet constituent is magnetized by current passed
through a single phase, two phases, or three phases of the stator
windings. Therefore, it is possible to select the phase or phases
through which current is to be passed according to the disposition
of the magnet or the permissible current (against deformation or
the like) of the windings.
[0300] In the manufacturing method for the synchronous induction
motor in accordance with the present invention, the stator windings
are coated with varnish or a sticking agent that is heated to fuse
the windings. Hence, for example, even if the stator windings are
subjected to electromagnetic forces when an unmagnetized magnet
material inserted into the rotor is magnetized by passing current
through the stator windings, it is possible to restrain the
deformation of the windings and the deterioration of the films of
the windings. Thus, since the winding ends of the stator windings
do not deform even if an unmagnetized magnet material inserted into
the rotor is magnetized, a highly reliable synchronous induction
motor can be provided.
[0301] According to the present invention, the drive unit for a
synchronous induction motor includes a stator equipped with a
stator winding formed of a primary winding and an auxiliary
winding, a rotor rotating in the stator, a secondary conductor
provided around a rotor yoke constituting the rotor, a permanent
magnet embedded in the rotor yoke, an operating capacitor connected
to the auxiliary winding, and a series circuit of a start-up
capacitor and a PTC, which is connected in parallel to the
operating capacitor. This arrangement permits larger running torque
to be provided at starting up the synchronous induction motor
equipped with the operating capacitor connected to the auxiliary
winding and the series circuit of the start-up capacitor and the
PTC, which is connected in parallel to the operating capacitor.
This enables the power consumed during normal operation to be
reduced, making it possible to provide a drive unit capable of
running the synchronous induction motor with extremely high
efficiency. Hence, considerably higher efficiency can be achieved
during the operation of the synchronous induction motor.
[0302] According to the present invention, the drive unit for a
synchronous induction motor that includes a stator equipped with a
stator winding formed of a primary winding and an auxiliary
winding, a rotor rotating in the stator, a secondary conductor
provided around a rotor yoke constituting the rotor, a permanent
magnet embedded in the rotor yoke, an operating capacitor connected
to the auxiliary winding, and a PTC connected in parallel to the
operating capacitor. This arrangement permits larger running torque
to be provided at starting up the synchronous induction motor
equipped with the operating capacitor connected to the auxiliary
winding and the PTC connected in parallel to the operating
capacitor. This enables the power consumed during normal operation
to be reduced, making it possible to provide a drive unit capable
of running the synchronous induction motor with extremely high
efficiency. Hence, considerably higher efficiency can be achieved
during the operation of the synchronous induction motor.
[0303] According to the present invention, the drive unit for a
synchronous induction motor includes a stator equipped with a
stator winding formed of a primary winding and an auxiliary
winding, a rotor rotating in the stator, a secondary conductor
provided around a rotor yoke constituting the rotor, a permanent
magnet embedded in the rotor yoke, an operating capacitor connected
to the auxiliary winding, and a series circuit of a start-up
capacitor and a start-up relay contact, which is connected in
parallel to the operating capacitor. This arrangement permits
larger running torque to be provided at starting up the synchronous
induction motor equipped with the operating capacitor connected to
the auxiliary winding and the series circuit of the start-up
capacitor and the start-up relay contact, which is connected in
parallel to the operating capacitor. This enables the power
consumed during normal operation to be reduced, making it possible
to provide a drive unit capable of running the synchronous
induction motor with extremely high efficiency. Hence, considerably
higher efficiency can be achieved during the operation of the
synchronous induction motor.
[0304] According to the present invention, the drive unit for a
synchronous induction motor includes a stator equipped with a
stator winding formed of a primary winding and an auxiliary
winding, a rotor rotating in the stator, a secondary conductor
provided around a rotor yoke constituting the rotor, a permanent
magnet embedded in the rotor yoke, and an operating capacitor
connected to the auxiliary winding. This arrangement permits larger
running torque to be provided at starting up the synchronous
induction motor equipped with the operating capacitor connected to
the auxiliary winding. This enables the power consumed during
normal operation to be reduced, making it possible to provide a
drive unit capable of running the synchronous induction motor with
extremely high efficiency. Hence, considerably higher efficiency
can be achieved during the operation of the synchronous induction
motor.
[0305] According to the present invention, the hermetic electric
compressor includes a compression unit and an electric unit for
driving the compression unit in a hermetic vessel, wherein the
electric unit is secured to the hermetic vessel and constituted by
a stator equipped with a stator winding and a rotor rotating in the
stator, the rotor has a secondary conductor provided around a rotor
yoke and a permanent magnet embedded in the rotor yoke, and a
thermal protector for cutting off the supply of current to the
electric unit in response to a predetermined temperature rise is
provided in the hermetic vessel. Therefore, installing the thermal
protector onto the stator winding, for example, makes it possible
to cut off the supply of current to the electric unit if the
temperature of the stator winding rises. This arrangement makes it
possible to prevent the permanent magnet embedded in the rotor yoke
from being thermally demagnetized by a rise in temperature of the
electric unit. Hence, the supply of current to the stator winding
can be cut off before the stator winding generates abnormal heat
while the hermetic electric compressor is in operation. This makes
it possible to securely prevent damage to the stator winding and
thermal demagnetization of the permanent magnet so as to ideally
maintain the driving force of a synchronous induction motor,
permitting significantly improved reliability of the electric
unit.
[0306] According to the present invention, the hermetic electric
compressor has a compression unit and an electric unit for driving
the compression unit in a hermetic vessel, wherein the electric
unit is secured to the hermetic vessel and constituted by a stator
equipped with a stator winding and a rotor rotating in the stator,
the rotor has a secondary conductor provided around a rotor yoke
and a permanent magnet embedded in the rotor yoke, and a thermal
protector for cutting off the supply of current to the electric
unit in response to a predetermined temperature rise is provided on
the outer surface of the hermetic vessel. Therefore, it is possible
to cut off the supply of current to the electric unit if the
temperature of the outer surface of the hermetic vessel rises due
to the heat generated by the electric unit. Thus, a temperature
rise in the hermetic vessel can be restrained, so that an accident,
such as a fire, caused by a temperature rise in the hermetic vessel
can be prevented.
[0307] In the hermetic electric compressor in accordance with the
present invention, the thermal protector is constructed of a
thermistor whose resistance value varies with temperature and a
controller that controls the supply of current to the electric unit
according to a change in the resistance value of the thermistor.
Thus, if, for example, the temperature of the hermetic electric
compressor rises and exceeds a preset level, the controller
controls the supply of current to the electric unit to reduce the
number of revolutions of the electric unit or cut off the supply of
current to the electric unit. With this arrangement, it is possible
to control the current supplied to the stator winding before the
hermetic electric compressor is run under an overload condition and
damaged. Thus, since the temperature of the electric unit can be
controlled without the need for interrupting the operation of the
hermetic electric compressor, an inconvenience, such as inadequate
cooling, attributable to an interrupted operation of the hermetic
electric compressor can be securely avoided. Moreover, a
temperature rise in the electric unit can be securely controlled by
controlling the revolution of the electric unit, enabling the
service life of the electric unit to be prolonged, with resultant
dramatically improved reliability of the hermetic electric
compressor.
[0308] In the hermetic electric compressor in accordance with the
present invention, the thermal protector is constituted by a
bimetal switch, so that the current supplied to the electric unit
can be cut off also if the temperature of the hermetic electric
compressor rises. This obviates the need for controllably adjusting
the electric unit by using an expensive circuit device, making it
possible to effect inexpensive and secure protection of the
hermetic electric compressor from damage caused by a temperature
rise.
[0309] In the hermetic electric compressor in accordance with the
present invention, the thermal protector is constituted by a
thermostat that opens/closes a contact according to temperature, so
that the current supplied to the electric unit can be cut off also
if the temperature of the hermetic electric compressor rises. This
obviates the need for controllably adjusting the electric unit by
using an expensive circuit device, making it possible to effect
inexpensive and secure protection of the hermetic electric
compressor from damage caused by a temperature rise.
[0310] According to a further aspect of the present invention, the
hermetic electric compressor includes a compression unit and an
electric unit for driving the compression unit in a hermetic
vessel, wherein the electric unit is secured to the hermetic vessel
and constituted by a stator equipped with a stator winding and a
rotor rotating in the stator, the rotor has a secondary conductor
provided around a rotor yoke and a permanent magnet embedded in the
rotor yoke, and an overload protector for cutting off the supply of
current to the electric unit at a predetermined overload current is
provided. Therefore, it is possible to cut off the supply of
current to the electric unit if the hermetic electric compressor is
overloaded during operation, thereby allowing the electric unit to
be protected from a temperature rise. Thus, damage to the electric
unit can be prevented, enabling the service life of the electric
unit to be considerably prolonged, with resultant dramatically
improved reliability of the hermetic electric compressor.
[0311] In the hermetic electric compressor in accordance with the
present invention, the overload protector is constituted by an
overload switch, so that the current supplied to the electric unit
can be cut off to prevent a temperature rise in the electric unit
thereby to protect it if the hermetic electric compressor is
overloaded during operation. Thus, damage to the electric unit can
be prevented, enabling the service life of the electric unit to be
considerably prolonged, with resultant dramatically improved
reliability of the hermetic electric compressor.
[0312] In the hermetic electric compressor in accordance with the
present invention, the overload protector is constituted by a
current transformer for detecting the current supplied to the
electric unit and a controller for controlling the supply of
current to the electric unit on the basis of an output of the
current transformer, so that the current supplied to the electric
unit can be cut off by the controller if the hermetic electric
compressor is overloaded during operation. This arrangement makes
it possible to prevent a temperature rise in the electric unit so
as to protect the electric unit. Hence, damage to the electric unit
attributable to an overload current can be securely prevented.
[0313] In the hermetic electric compressor in accordance with the
present invention, the controller cuts off the supply of current to
the electric unit after a predetermined time elapses since a
temperature or current exceeded a predetermined value. It is
therefore possible to protect, by the controller, the electric unit
which would be damaged if continuously subjected to an excessive
temperature rise or overcurrent caused by an overload operation or
the like of the hermetic electric compressor. Thus, damage to the
electric unit can be prevented, enabling the service life of the
electric unit to be considerably prolonged, with resultant
dramatically improved reliability of the hermetic electric
compressor.
[0314] In the hermetic electric compressor in accordance with the
present invention, the controller restarts the supply of current to
the electric unit after waiting for the elapse of a predetermined
delay time since the supply of current to the electric unit was cut
off. This means that the delay time is always allowed before the
supply of current to the electric unit is resumed after the supply
of current to the electric unit was cut off. It is therefore
possible to prevent the rotor from becoming hot due to, for
example, frequent repetition of energizing and de-energizing of the
electric unit. Hence, demagnetization of the permanent magnet
embedded in the rotor due to heat can be prevented.
* * * * *