U.S. patent application number 09/841907 was filed with the patent office on 2002-01-10 for motor-driven compressor.
Invention is credited to Fujii, Toshiro, Nakane, Yoshiyuki, Tarao, Susumu, Yokomachi, Naoya.
Application Number | 20020002840 09/841907 |
Document ID | / |
Family ID | 18635767 |
Filed Date | 2002-01-10 |
United States Patent
Application |
20020002840 |
Kind Code |
A1 |
Nakane, Yoshiyuki ; et
al. |
January 10, 2002 |
Motor-driven compressor
Abstract
A compression mechanism is provided, in a casing, and
operatively coupled via a drive shaft 17 to an electric motor 21
accommodated in a motor chamber 15 within the casing, so that power
can be transmitted. An in-shaft bore 17A is formed in the drive
shaft and a first bifurcated hole 17B is formed for communicating
the in-shaft bore 17A to the motor chamber 15. The in-shaft bore
17A is communicated to the suction chamber 31 via a second
collecting hole 13F, the collecting chamber 13D and a suction
communication hole 13G formed in a cylinder block 13. Thereby, part
of the refrigerant sucked in the casing is introduced to the
compression mechanism through a gap between a stator 19 and a rotor
20, and the remainder of the refrigerant is introduced to the
compression mechanism without being used for cooling the electric
motor 21.
Inventors: |
Nakane, Yoshiyuki;
(Kariya-shi, JP) ; Tarao, Susumu; (Kariya-shi,
JP) ; Yokomachi, Naoya; (Kariya-shi, JP) ;
Fujii, Toshiro; (Kariya-shi, JP) |
Correspondence
Address: |
Woodcock Washburn Kurtz
Mackiewicz & Norris LLP
One Liberty Place - 46th Floor
Philadelphia
PA
19103
US
|
Family ID: |
18635767 |
Appl. No.: |
09/841907 |
Filed: |
April 25, 2001 |
Current U.S.
Class: |
62/505 ;
417/317 |
Current CPC
Class: |
F25B 31/008 20130101;
F04B 27/0895 20130101; F04B 27/109 20130101 |
Class at
Publication: |
62/505 ;
417/317 |
International
Class: |
F04B 009/00; F04B
017/00; F04B 035/00; F25B 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2000 |
JP |
2000-125897 |
Claims
1. A motor-driven compressor comprising, in a casing, a compression
mechanism for compressing refrigerant, an electric motor having a
stator and a rotor and disposed in a motor chamber in the casing,
and a drive shaft connected to the rotor and transmitting a drive
force of the electric motor to the compression mechanism, wherein
the motor chamber and an in-shaft refrigerant passage formed in the
drive shaft are provided in a suction passage for introducing the
refrigerant sucked into the casing to the compression mechanism,
and wherein part of the sucked refrigerant is introduced to the
compression mechanism while passing through a gap between the
stator and the rotor, and the other of the sucked refrigerant is
introduced to the compression mechanism without passing through the
gap between the stator and the rotor but while passing through the
in-shaft refrigerant passage.
2. A motor-driven compressor according to claim 1, wherein at least
one of a drive shaft bearing for rotationally supporting the drive
shaft in the casing and a bearing for supporting part or all of the
compression mechanism is disposed in the suction passage.
3. A motor-driven compressor according to claim 1, wherein a
suction opening for sucking the refrigerant into the casing is
provided in the motor chamber on the axis of the drive shaft.
4. A motor-driven compressor according to claim 1, wherein the
in-shaft refrigerant passage is formed through opposite ends of the
drive shaft.
5. A motor-driven compressor according to claim 1, wherein the
compression mechanism is of a scroll type in which a stationary
spiral wall formed in a stationary scroll provided on a side of the
casing is meshed with a movable spiral wall formed in a movable
scroll operatively coupled to the drive shaft so that the movable
scroll is subjected to an orbital motion as the drive shaft rotates
to compress the refrigerant, wherein an in-scroll refrigerant
passage is formed in the movable scroll so that at least part of
the refrigerant introduced into the in-shaft refrigerant passage is
introduced into a compression chamber defined between both the
spiral walls through the in-scroll refrigerant passage.
6. A motor-driven compressor according to claim 1, wherein the
compression mechanism is of a reciprocating piston type in which a
piston accommodated for reciprocation in a cylinder bore formed in
the casing is operatively coupled to the drive shaft to compress
the refrigerant by the reciprocation of the piston as the drive
shaft rotates.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a motor-driven compressor
and, more specifically, to a motor-driven compressor provided in a
casing with a compression mechanism for compressing a refrigerant
and an electric motor for driving the compression mechanism.
[0003] 2. Description of the Related Art
[0004] A motor-driven compressor has been known in the art as a
compressor to be incorporated in a refrigerant circulation circuit
of a heat exchanger for a car air-conditioner. Generally speaking,
the motor-driven compressor includes an electric motor and a
refrigerant compression mechanism in a casing constituting an outer
casing thereof. Since it is desirable that the motor has a rotating
power to provide a high rotating speed and a driving force over a
high torque loaded thereto, the compressor must have a high-output
motor. In a design wherein the high output motor is used for
overcoming a high rotating load, however, the motor generates a
large amount of heat to further accelerate the temperature rise in
the ambient atmosphere around the motor. Since such a temperature
rise of the ambient atmosphere naturally causes the temperature of
the motor itself to be higher, there is a risk in that the
rotational efficiency becomes lower due to the demagnetization of
the motor caused by the temperature rise. To solve such a problem,
an arrangement may be adopted, wherein refrigerant sucked into the
casing is introduced into a motor chamber for accommodating the
motor, and after the motor has been cooled with the refrigerant,
the refrigerant is introduced into the refrigerant compression
mechanism.
[0005] According to this arrangement, however, since the
refrigerant introduced into the motor chamber is heated by the
motor, the refrigerant is introduced into the refrigerant
compression mechanism while a specific volume thereof increases,
which decreases an amount of the refrigerant circulating the
refrigerant circulation circuit to result in a problem in that the
cooling capacity is lowered. Also, when the refrigerant cools the
motor, the refrigerant is often forced to pass through a small gap
between a stator and a rotor of the motor, during which a flow
resistance of the refrigerant, due to a viscosity of mist of
lubricant contained in the refrigerant, disturbs the smooth flow of
the refrigerant.
[0006] In Japanese Unexamined Patent Publication (Kokai) No.
9-236092, an arrangement is disclosed wherein two suction openings
are provided for taking refrigerant into the interior of the
compressor casing; one of which is provided in a wall portion of
the motor chamber (part of the casing) closer to the refrigerant
compression mechanism and the other is provided opposite to the
refrigerant compression mechanism while the motor is interposed.
According to this arrangement, part of the refrigerant taken into
the compressor casing is sucked through the former suction opening
and the remaining is sucked through the latter suction opening. The
refrigerant sucked through the former suction opening is introduced
into the refrigerant compression mechanism while hardly cooling the
motor. Also, the refrigerant sucked through the latter suction
opening is introduced into the refrigerant compression mechanism
after cooling the motor. Thereby, the above-mentioned two problems
can be solved because all of the refrigerant introduced into the
refrigerant compression mechanism does not pass by the motor.
[0007] According to this arrangement, however, it is necessary to
provide a plurality of seal members for isolating pressures in
correspondence to the plurality of suction openings in the
compressor casing, resulting in a problem in production cost or in
reliability.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide a
motor-driven compressor capable, in an inexpensive and reliable
manner, of cooling a motor, reducing the specific volume of
refrigerant and preventing the refrigerant suction efficiency of a
compressor mechanism from falling due to the flow resistance caused
by the viscosity of a lubricant oil.
[0009] To solve the above-mentioned problems, according to the
present invention, a motor-driven compressor is provided which
comprises, in a casing, a compression mechanism for compressing
refrigerant, an electric motor having a stator and a rotor and
disposed in a motor chamber in the casing, and a drive shaft
connected to the rotor and transmitting the torque of the electric
motor to the compression mechanism, wherein the motor chamber and
an in-shaft refrigerant passage formed in the drive shaft are
provided in a suction passage for introducing the refrigerant
sucked into the casing to the compression mechanism, wherein part
of the sucked refrigerant is introduced to the compression
mechanism while passing through a gap between the stator and the
rotor, and the rest of the sucked refrigerant is introduced to the
compression mechanism without passing through the gap between the
stator and the rotor but passes through the in-shaft refrigerant
passage.
[0010] According to the present invention, part of the refrigerant
sucked into the casing is introduced into the compression mechanism
through the gap between the stator and the rotor. That is to say,
not all the sucked refrigerant passes through the gap having a high
temperature. In other words, the refrigerant introduced to the
compression mechanism is not heated as a whole, whereby the
temperature rise of the refrigerant is restricted. Thus, the
increase in specific volume of the refrigerant introduced to the
compression mechanism is suppressed to prevent the compression
efficiency of the compression mechanism from falling. In addition,
if a mist of lubricant oil exists in the refrigerant for
lubricating the interior of the casing, the present invention
serves to reduce the flow resistance caused by the viscosity of the
lubricant oil when the refrigerant passes through the small gap
between the stator and the rotor. Also, since the flow rate of the
refrigerant passing through the gap between the stator and the
rotor is adjustable by providing the in-shaft refrigerant passage,
it is unnecessary to provide a plurality of suction inlets for
sucking the refrigerant into the casing to adjust the flow rate of
the refrigerant.
[0011] The present invention may be more fully understood from the
description of the preferred embodiments of the invention, as set
forth below, together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In the drawings:
[0013] FIG. 1 is a schematic side sectional view of a first
embodiment of a motor-driven compressor according to the present
invention;
[0014] FIG. 2 is a schematic side sectional view of a second
embodiment of a motor-driven compressor according to the present
invention; and
[0015] FIG. 3 is a rear side view of a movable scroll of the
motor-driven compressor shown in FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] (First Embodiment)
[0017] One aspect of the present invention, embodied as a swash
plate type motor-driven compressor, will be described below with
reference to FIG. 1, wherein it is assumed that the right of FIG. 1
is the front side of the compressor and the left thereof is the
rear side.
[0018] As shown in FIG. 1, the motor-driven swash plate type
compressor C1 includes a motor housing 11, a front housing 12, a
cylinder block 13 and a rear housing 14. These housings 11, 12, 14
and the cylinder block 13 are fixedly connected to each other by a
plurality of through-bolts not shown to define a generally
cylindrical casing of the compressor. A space encircled by the
motor housing 11 and the front housing 12 defines a motor chamber
15, and a space enclosed by the front housing 12 and the cylinder
block 13 defines a swash plate chamber 16.
[0019] A drive shaft 17 is rotatably supported by a pair of front
and rear radial bearings 18A, 18B between the motor housing 11 and
the cylinder block 13 while extending through the motor chamber 15
and the swash plate chamber 16. The drive shaft 17 is loosely
fitted in a central hole 12B bored through a wall portion 12A
formed in the front housing 12. In the wall portion 12A,
communication holes 12C are also formed for communicating the swash
plate chamber 16 with the motor chamber 15.
[0020] An electric motor 21, accommodated within the motor chamber
15, consists of a stator 19 and a rotor 20 fixedly secured to the
drive shaft 17 to be rotatable therewith. The stator 19 and the
rotor 20 are arranged so that a small gap exists between the inner
circumference of the stator 19 and the outer circumference of the
rotor 20.
[0021] A disk-shaped swash plate 22 is fixedly secured onto the
drive shaft 17 in the swash plate chamber 16 to be rotatable
therewith, and a thrust bearing 23 which is one of the bearings for
the drive shaft is disposed between the swash plate 22 and the wall
portion 12A. The drive shaft 17 and the swash plate 22 connected
integrally with each other are located at a position in the thrust
direction (the axial direction of the drive shaft) via a washer 25
biased forward by a spring 24 accommodated in an accommodation
recess 13A centrally formed in the cylinder block 13 and the thrust
bearing 23.
[0022] A plurality of cylinder bores 13B (only two are visible in
FIG. 1) are formed in the cylinder block 13. In the respective
cylinder bore, a single-head piston 26 is accommodated to be
slidable in reciprocated manner forward and backward, so that a
compression chamber 13C is defined in the respective bore 13B,
which is variable in volume in accordance with the reciprocation of
the piston 26. A pair of recesses 26A is provided in a front
portion of the respective piston 26, for accommodating a pair of
shoes 28 therein. The shoes 28 grippingly holds the periphery of
the swash plate 22 in a slidable manner to operatively couple the
piston 26 with the swash plate 22. Thus, when the drive shaft 17 is
made to rotate by the electric motor 21, the swash plate 22 also
rotates in synchronism with the drive shaft 17, whereby the
rotational motion of the swash plate 22 is converted to a linear
reciprocating motion of the piston 26 having a stroke corresponding
to the inclination angle thereof.
[0023] A valve-forming body 30 is provided between the cylinder
block 13 and the rear housing 14 while being sandwiched by the
both. Between the valve-forming body 30 and the rear housing 14, a
suction chamber 31 through which refrigerant introduced into the
respective cylinder bore 13B passes and a discharge chamber 33
through which refrigerant discharged from the respective cylinder
bore 13B passes are defined. In a rear side wall of the rear
housing 14, a discharge opening 33A, in communication with the
discharge chamber 33, is formed.
[0024] The valve-forming body 30 is formed of a suction
valve-forming plate, a port-forming plate, a discharge
valve-forming plate and a retainer-forming plate which are secured
together by a pin 34 in a superposed manner. In this valve-forming
body 30, a suction port 35 and a suction valve 36 for
opening/closing the port 35, and a discharge port 37 and a
discharge valve 38 for opening/closing the port 37 are formed
corresponding to the respective cylinder bore 13B. The suction
chamber 31 and the respective cylinder bore 13B are communicated
with each other via the suction port 35, and the respective
cylinder bore 13B and the discharge chamber 33 are communicated
with each other via the discharge port 37.
[0025] In this regard, a compression mechanism for compressing
refrigerant is constituted by the cylinder bore 13B, the swash
plate 22, the piston 26, the shoe 28 and the valve-forming body
30.
[0026] A collecting chamber 13D is defined in a central area of a
rear side of the cylinder block 13, and a plurality of collecting
holes 13E (only two are visible in FIG. 1) are formed between the
collecting chamber 13D and the swash plate chamber 16 for
communicating the chambers with each other. Further, a second
collecting hole 13F is formed between the collecting chamber 13D
and the accommodation recess 13A for communicating the chambers
with each other. A suction communication hole 13G is provided in
the cylinder block 13, for always communicating the collecting
chamber 13D with the suction chamber 31.
[0027] A bearing accommodating portion 11A is provided in the front
side wall of the motor housing 11, for accommodating the radial
bearing 18A therein. Also, in the front side wall, a suction
opening 11B is arranged on the axis of the drive shaft 17 for
communicating the bearing accommodating portion 11A with the
exterior of the motor chamber 15.
[0028] The drive shaft 17 is disposed so that a front end and a
rear end thereof are accommodated in the bearing accommodating
portion 11A and the accommodation recess 13A, respectively. The
drive shaft 17 is provided with an in-shaft bore 17A extending
between opposite ends of the drive shaft. That is, the bearing
accommodating portion 11A and the accommodation recess 13A are
communicated with each other via the in-shaft bore 17A. The drive
shaft 17 is also provided with a first bifurcated hole 17B for
communicating a front space of the motor chamber 15 forward of the
rotor 20 with the in-shaft bore 17 and a second bifurcated hole 17C
for communicating the interior of the thrust bearing 23 with the
in-shaft bore 17A. An in-shaft refrigerant passage is constituted
by the in-shaft bore 17A, the first bifurcated hole 17B and the
second bifurcated hole 17C.
[0029] A suction passage is constituted by the bearing
accommodating portion 11A, the in-shaft bore 17A, the accommodation
recess 13A, the second collecting hole 13F, the collecting chamber
13D, the suction communication hole 13G, the suction chamber 31,
the first bifurcated hole 17B, the motor chamber 15, the
communication hole 12C, the swash plate chamber 16, the first
collecting hole 13E, the second bifurcated hole 17C and the thrust
bearing 23, for introducing the refrigerant sucked into the casing
of the compressor Cl via the suction opening 11B.
[0030] The suction opening 11B and the discharge opening 33A are
connected with each other via an external refrigerant circuit not
shown. In the refrigerant which circulates in the compressor C1 and
the external refrigerant circuit, a mist of lubricant oil is mixed
for the purpose of lubricating the compressor C1 to allow smooth
operation of the latter.
[0031] Next, the operation of the compressor thus structured will
be described.
[0032] When the drive shaft 17 is driven to rotate by the electric
motor 21, the swash plate 22 is also made to rotate therewith. As
the swash plate 22 rotates, piston 26 reciprocates via the shoe 28.
By continuing such a motion, the refrigerant is repeatedly sucked
into the compression chamber 13C, compressed therein and discharged
therefrom.
[0033] The refrigerant sucked from the external refrigerant circuit
into the suction opening 11B is introduced into the in-shaft bore
17A via the bearing accommodating portion 11A. Part of the
refrigerant introduced into the in-shaft bore 17A is introduced to
the collection chamber 13D via the accommodation recess 13A and the
second collecting hole 13F.
[0034] After being introduced into a space of the motor chamber 15
forward of the rotor 20 via the first bifurcated hole 17B, part of
the remainder of the refrigerant is introduced into a space
rearward of the stator 19 and the rotor 20 through a gap between
the both, during which the electric motor is cooled because the
refrigerant removes heat from the electric motor 21. Thereafter,
the refrigerant introduced into the space rearward of the stator 19
and the rotor 20 is introduced into the swash plate chamber 16 via
the communication hole 12C and then introduced into the collecting
chamber 13D through the first collecting hole 13E.
[0035] The rest of the refrigerant introduced from the bearing
accommodating portion 11A to the in-shaft bore 17A described
hereinbefore is introduced into a gap in the thrust bearing 23 via
the second bifurcated hole 17C, and then into the collecting
chamber 13D via the swash plate chamber 16 and the first collecting
hole 13E. The thrust bearing 23 is cooled by the refrigerant
passing through the gap thereof and also lubricated with the mist
of lubricant oil contained in the refrigerant.
[0036] In this regard, part of the refrigerant introduced into the
swash plate chamber 16 is introduced into the collecting chamber
13D via the accommodation recess 13A and the second collecting hole
13F.
[0037] The refrigerant introduced into the collecting chamber 13D
is introduced into the suction chamber 31 via the suction
communication hole 13G, and then sucked into the compression
chamber 13C via the suction port 35, wherein the refrigerant is
subjected to the compressive operation of the piston 26 and
discharged to the discharge chamber 33 through the discharge port
37. The refrigerant thus discharged into the discharge chamber 33
is delivered to the external refrigerant circuit via the discharge
opening 33A.
[0038] The following effects are obtainable according to this
embodiment:
[0039] (1) Since part of the low temperature refrigerant sucked
from the suction opening 11B is introduced into the motor chamber
15, the cooling of the electric motor 21 is enhanced. Also, due to
lubricant oil contained in the refrigerant, the lubrication of the
radial bearing 18A is facilitated.
[0040] (2) Since the refrigerant introduced to the motor chamber 15
in the space forward of the rotor 20 via the first bifurcated hole
17B is transferred to the space rearward of the stator 19 and the
rotor 20 through the gap between the two, it is possible to cool a
wide area of the surface of the electric motor 21 whereby the
cooling of the electric motor 21 is facilitated.
[0041] (3) Since only part of the refrigerant introduced from the
suction opening 11B into the collecting chamber 13D is allowed to
be introduced into the motor chamber 15 while the rest is not
introduced into the motor chamber 15, it is possible to suppress
the temperature rise of the refrigerant introduced into the
collecting chamber 13D in comparison with a case wherein all the
refrigerant from the suction opening 11B is introduced into the
motor chamber 15. That is, it is possible to suppress the increase
in specific volume of the refrigerant sucked into the compression
chamber 13C caused by the temperature rise, and to prevent the
compression efficiency from lowering.
[0042] Also, since all the refrigerant sucked from the suction
opening 11B does not necessarily pass through the small gap between
the stator 19 and the rotor 20, it is possible to reduce the flow
resistance of the refrigerant generated by passing through the gap
due to the viscosity of a lubricant oil contained in the
refrigerant. Accordingly, the suction efficiency of the refrigerant
is improved throughout an overall area from the suction opening 11B
to the compression chamber 13C.
[0043] (4) The in-shaft bore 17A and the first bifurcated hole 17B
are provided in the drive shaft 17 so that the refrigerant sucked
from the suction opening 11B is divided into a part to be
introduced into the motor chamber 15 and the rest not introduced
thereto. Accordingly, it is possible to suck the refrigerant into
the casing of the compressor C1 via a single suction opening 11B
alone, without adopting, for example, an arrangement wherein inlets
for sucking the refrigerant from the exterior of the casing of the
compressor C1 are provided at two positions in the motor housing 11
forward and rearward of the electric motor 21 to prevent part of
the refrigerant from by passing the electric motor 21. That is to
say, since the number of joints between the compressor C1 and the
external refrigerant circuit can be reduced, the sealing process is
simplified to save the manufacturing cost and the reliability is
improved. Also, the production becomes easier in comparison with an
arrangement wherein a bypass is formed in the circumferential wall
of the motor housing 11 and the front housing 12 to introduce the
refrigerant sucked from the suction opening 11B into the swash
plate chamber 16 or the suction chamber 31 via the bypath, not via
the motor chamber 15.
[0044] (5) The second bifurcated hole 17C is provided for
introducing part of the refrigerant in the in-shaft bore 17A into
the swash plate chamber 16. Thus, lubrication of components in the
swash plate chamber 16 (for example, the radial bearing 18B, the
swash plate 22, the thrust bearing 23, recess 26A and the shoe 28)
is enhanced.
[0045] (6) Due to the second bifurcated hole 17C, the refrigerant
introduced from the in-shaft bore 17A to the swash plate chamber 16
passes through a gap in the thrust bearing 23. Thus, the
lubrication of the thrust bearing is enhanced.
[0046] (7) Since the suction opening 11B is provided in the motor
chamber 15 on the axis of the drive shaft 17, it is possible to
shorten a path between the suction opening 11B and the in-shaft
bore 17A and make the same linear. Accordingly, the flow
resistance, to the refrigerant, until it reaches the in-shaft bore
17A can be reduced in comparison with a case wherein the path is
longer and curved. Also, since the suction opening 11B can be
easily aligned with a center of the motor housing 11 and/or the
bearing accommodating portion 11A, the suction opening 11B is
easily machined.
[0047] (8) The in-shaft bore 17A is provided through the opposite
ends of the drive shaft 17 to introduce the refrigerant sucked from
the suction opening 11B into the collecting chamber 13D. Thereby,
it is possible to make a refrigerant passage from the suction
opening 11B to the collecting chamber 13D shorter and more linear,
resulting in a reduction of flow resistance to the refrigerant.
Further, since the refrigerant can be directly introduced from the
suction opening 11B to the collecting chamber 13D, it is possible
to suppress the temperature rise and therefore an increase in
specific volume of the refrigerant.
[0048] (Second Embodiment)
[0049] A second aspect of the present invention embodied to a
scroll type motor-driven compressor will be describe below with
reference to FIG. 2, wherein it is assumed that the right of FIG. 2
is the front side of the compressor and the left thereof is the
rear side.
[0050] As shown in FIG. 2, a center housing 52 is fixedly secured
to a stationary scroll 51, and a motor housing 53 is fixedly
secured to the center housing 52. A casing for a motor-driven
scroll type compressor C2 is constituted by the stationary scroll
51, the center housing 52 and the motor housing 53. A shaft 54 is
supported in a rotatable manner by the center housing 52 and the
motor housing 53 via radial bearings 55, 56 used as drive shaft
bearings, and has an eccentric shaft 57 integrally formed
therewith. A motor chamber 58 is defined by a space enclosed by the
inner circumference of the motor housing 53 and the center housing
52.
[0051] A bushing 60 is fitted over the eccentric shaft 57. Note
that the shaft 54, the eccentric shaft 57 and the bushing 60
constitute a drive shaft. A movable scroll 61 is supported by the
bushing 60 via a needle bearing 62 to be opposed to the stationary
scroll 51 and rotatable relative thereto. A movable spiral wall 64
is formed on a movable base plate 63 in the movable scroll 61,
while a stationary spiral wall 66 is formed on a stationary base
plate 65 in the stationary scroll 61 to be meshed with the movable
spiral wall 64. The needle bearing 62 is accommodated in an
accommodating portion formed in a boss 67 projected forward (right
in FIG. 1) from the movable base plate 63. A space enclosed by the
stationary base plate 65, the stationary spiral wall 66, the
movable base plate 63 and the movable spiral wall 64 defines closed
chambers 68, i.e., compression chambers which volume is variable as
the movable scroll 61 rotates. Generally at a center of the
stationary base plate 65, there is a discharge opening 69 for
communicating the exterior of the casing of the compressor C2 with
the closed chamber 68.
[0052] In a wall of the center housing 52 closer to the movable
scroll 61, a plurality of recesses 70 (only one is visible in FIG.
2) are formed along substantially the same circle. In the
respective recess 70 are accommodated a stationary pin 71 fixed to
the center housing 52 and a movable pin 72 fixed to the movable
scroll 61. The movable scroll 61 is subjected to an orbital motion
as the eccentric shaft 57 rotates, but is inhibited from rotating
about its own axis by means of the stationary pin 71, the movable
pin 72 and an annular ring 73.
[0053] Note a scroll type compression mechanism is constituted by
the movable scroll 61, the needle bearing 62, the stationary base
plate 65, the stationary spiral wall 66, the stationary pin 71, the
movable pin 72 and the annular ring 73.
[0054] A movable base plate chamber 52A is formed, rearward of the
center housing 52, for accommodating the movable base plate 63. An
intermediate chamber 52B is provided between the movable base plate
chamber 52A and the motor chamber 58, for communicating the
chambers with each other. As shown in FIGS. 2 and 3, a plurality of
base plate communication holes 63A (eight are shown in FIG. 3) of
an arcuate shape are provided in the vicinity of the outer
circumference of the movable base plate 63 while penetrating front
and rear surfaces of the latter. The outermost one of the plurality
of closed chambers 68 (hereinafter referred to a low pressure
closed chamber) and the intermediate chamber 52B are communicated
with each other through the base plate communication holes 63A.
[0055] Generally at a center of the center housing 52, a boss
chamber 52C is formed for accommodating the boss 67 therein. In a
region of the boss chamber 52C closer to the motor chamber 58, a
bearing chamber 52D for accommodating the radial bearing 55 is
formed and protrudes into the motor chamber 58. The boss chamber
52C is communicated with the bearing chamber 52D via a gap in the
radial bearing 55. Also the boss chamber 52C and the intermediate
chamber 52B communicate with each other through a communication
hole 52E provided between both the chambers.
[0056] A stator 80 is fixedly secured to the inner circumference of
the motor housing 53, and a rotor 81 is fixedly secured to the
outer circumference of the shaft 54 at a position opposite to the
stator 80. The stator 80 and the rotor 81 are disposed so that a
small gap exists between the inner circumference of the stator 80
and the outer circumference of the rotor 81. The stator 80 and the
rotor 81 constitutes an electric motor in that the rotor 81 and the
shaft 54 rotate together when the stator 80 is supplied with
electric current.
[0057] In the front side wall of the motor housing 53, a bearing
accommodating portion 53A is provided for accommodating the radial
bearing 56 and a front end of the shaft 54. Further, in this front
side wall, a suction opening 53B is provided on the axis of the
shaft 54, for communicating the bearing accommodating portion 53A
with the exterior of the motor chamber 58 and for sucking the
refrigerant into the casing of the compressor C2.
[0058] The shaft 54 has a shaft bore 54A penetrating the opposite
ends thereof. Also, the shaft 54 has a first bifurcated hole 54B
for communicating a space in the motor chamber 58 forward of the
rotor 81 with the shaft bore 54A and a second bifurcated hole 54C
for communicating a space in the bearing chamber 52D forward of the
radial bearing 55 with the shaft bore 54A. A shaft bore 57A is
provided in the eccentric shaft 57 while penetrating the opposite
ends thereof, and communicated with the shaft bore 54A. An internal
drive shaft refrigerant passage is constituted by the shaft bore
54A, the first bifurcated hole 54B, the second bifurcated hole 54C
and the shaft bore 57A.
[0059] As illustrated in FIGS. 2 and 3, a connecting chamber 63B is
formed at a center of a front side of the movable base plate 63. A
plurality of connecting passages 63C (four in this embodiment) are
formed in the interior of the movable base plate 63, for
communicating the connecting chamber 63B with the base plate
communication holes 63A. An internal scroll refrigerant passage is
constituted by the connecting chamber 63B, the connecting passages
63C and the base plate communication holes 63A, which in turn
communicates with the accommodating portion in the boss 67 and the
intermediate chamber 52B.
[0060] Note that a suction passage for introducing the refrigerant
sucked via the suction opening 53B into the casing of the
compressor C2 and further, to the scroll type compressor is
constituted by the bearing accommodating portion 53A, shaft bore
54A, shaft bore 57A, the first bifurcated hole 54B, the motor
chamber 58, the intermediate chamber 52B, the second bifurcated
hole 54C, the bearing chamber 52D, the radial bearing 55, the boss
chamber 52C, the communication hole 52E, the base plate
communication hole 63A, the connecting chamber 63B and the
connecting passages 63C.
[0061] The suction opening 53B is communicated with the discharge
opening 69 via an external refrigerant circuit not shown.
[0062] Next, the operation of the compressor of the above-mentioned
arrangement will be described.
[0063] When the shaft 54 is rotated by the electric motor, the
eccentric shaft 57 rotates together with the bushing 60. The
eccentric shaft 57 and the bushing 60 eccentrically rotate relative
to the rotational center of the shaft 54. Such rotation is
transmitted via the needle bearing 62 to the movable scroll 61
which then is subjected to an orbital motion. In accordance with
this orbital motion, the volume of the closed chamber 68 varies to
sequentially repeat the cycle of suction, compression and
discharge.
[0064] The refrigerant sucked into the suction opening 53B from the
external refrigerant circuit is introduced into the shaft bore 54A
via the bearing accommodating portion 53A. Part of the refrigerant
introduced into the shaft bore 54A is introduced into the base
plate communication holes 63A through the shaft bore 57A, the
accommodating portion in the boss 67, the connecting chamber 63B
and the connecting passage 63C, and sucked in the closed chamber 68
(the low pressure closed chamber).
[0065] Part of the remainder of the refrigerant is introduced into
a space in the motor chamber 58 forward of the rotor 81 through the
first bifurcated hole 54B, and then into a space rearward of the
stator 80 and the rotor 81 via a gap between the both, during which
the electric motor is cooled. Thereafter, the refrigerant
introduced into the space rearward of the stator 80 and the rotor
81 is introduced into the base plate communication holes 63A via
the intermediate chamber 52B.
[0066] Part of the refrigerant introduced to the shaft bore 54A
other than the above-mentioned part is introduced to the bearing
chamber 52D via the second bifurcated hole 54C and then to the boss
chamber 52C via the gap in the radial bearing 55. Thereby, the
radial bearing 55 is lubricated. Part of the refrigerant introduced
into the boss chamber 52C is introduced into the base plate
communication holes 63A via the communication hole 52E and the
intermediate chamber 52B, while the remainder of the refrigerant is
introduced into the connecting chamber 63B via the gap in the
needle bearing 62 accommodated in the boss 67. The needle bearing
62 is lubricated with the mist of lubricant oil contained in the
refrigerant passing through the gap in the needle bearing 62.
[0067] The refrigerant sucked in the closed chamber 68 (low
pressure chamber) is compressed due to the orbital motion of the
movable scroll 61 and delivered via the discharge opening 69 to the
external refrigerant circuit.
[0068] According to this embodiment, the following effects are
obtainable in addition to those similar to the items (1) to (4),
(7) and (8) described in relation to the preceding embodiment:
[0069] (9) The second bifurcated hole 54C is provided for
introducing part of the refrigerant in the shaft bore 54A to the
bearing chamber 52D and further to the boss chamber 52C via the
radial bearing 55. Thereby, it is possible to facilitate the
lubrication of the radial bearing 55 and the interior the boss
chamber 52C (such as the bushing 60 or the needle bearing 62).
[0070] (10) Part of the refrigerant introduced into the boss
chamber 52C is further introduced to the connecting chamber 63B
through the gap in the needle bearing 62. Thereby, lubrication of
the needle bearing 62 is facilitated.
[0071] (11) The refrigerant introduced into the connecting chamber
63B at a center of the movable base plate 63 from the shaft bore
57A is further guided to the base plate communication holes 63A
through the connecting passage 63C provided in the outer
circumference of the movable base plate 63. Thereby, it is possible
to shorten the refrigerant path from the shaft bore 57A to the
closed chamber 68 (low pressure closed chamber), whereby the flow
resistance to the refrigerant can be reduced until it reaches the
closed chamber 68 (low pressure chamber).
[0072] (12) By the provision of the connecting chamber 63B and the
connecting passages 63C, the movable scroll 61 can be lighter in
weight.
[0073] (13) All of the connecting passages 63C are not connected to
the eight base plate communication holes 63A but only to four of
them are. Thereby, it is possible to reduce the necessity of
providing the connecting passages 63C to prevent the production
cost from increasing.
[0074] The present invention should not be limited to the
above-mentioned embodiments but may include the following:
[0075] The second bifurcated hole 17C (corresponding to the second
bifurcated hole 54C in the second embodiment) may be eliminated.
That is, the refrigerant in the in-shaft bore 17A (shaft bore 54A)
need not be introduced into the thrust bearing 23 (radial bearing
55).
[0076] The suction opening 11B (suction opening 53B in the second
embodiment) may not be provided on the axis of the drive shaft 17
(shaft 54). For instance, the suction opening 11B (suction opening
53B) may be communicated with the motor chamber 15 (motor chamber
58) and not via the bearing accommodating portion 11A (bearing
accommodating portion 53A). In this case, part of the refrigerant
introduced from the suction opening 11B (suction opening 53B) into
the motor chamber 15 (motor chamber 58) is further introduced to
the compression chamber 13C (closed chamber 68) via a gap between
the stator 19 (stator 80) and the rotor 20 (rotor 81). Part of the
remainder of the refrigerant is introduced to the in-shaft bore 17A
(shaft bore 54A) via the first bifurcated hole 17B (first
bifurcated hole 54B), and then further to the compression chamber
13C (closed chamber 68).
[0077] The in-shaft bore 17A may be eliminated in a region rearward
of the second bifurcated hole 17C. In such a case, the refrigerant
in the in-shaft bore 17A is introduced to the collecting chamber
13D via the second bifurcated hole 17C, the swash plate chamber 16
and the first collecting hole 13E.
[0078] The in-shaft bore 17A (shaft bore 54A) may be eliminated in
a region forward of the first bifurcated hole 17B (first bifurcated
hole 54B), provided the suction opening 11B (suction opening 53B)
is communicated to the motor chamber 15 (motor chamber 58). In such
a case, part of the refrigerant in the motor chamber 15 (motor
chamber 58) is introduced to the in-shaft bore 17A (shaft bore 54A)
via the first bifurcated hole 17B (first bifurcated hole 54B).
[0079] The compression mechanism of the motor-driven swash plate
type compressor C1 (the motor-driven scroll type compressor C2 in
the second embodiment) may not be of a fixed volume type wherein a
discharged volume of the refrigerant per one rotation of the drive
shaft 17 is constant. For example, the compression mechanism of the
motor-driven swash plate type compressor C1 may be of a type
wherein a stroke of the piston 26 is variable. Also, the
compression mechanism of the motor-driven scroll type compressor C2
may be of a type wherein part of the refrigerant sucked in the
closed chamber 68 is discharged out of the closed chamber 68 while
reaching the discharge opening 69 so that the volume of the
refrigerant discharged through the discharge opening 69 is
variable.
[0080] Although the motor-driven swash plate type compressor C1 in
the above-mentioned embodiment is of a type wherein the swash plate
22 rotates integrally with the drive shaft 17, it may be of another
type wherein the swash plate for reciprocating the piston does not
rotate integrally with the drive shaft but is operatively connected
to a rotary plate rotatable together with the drive shaft to cause
the piston to reciprocate without the rotation of the swash plate.
The motor-driven swash plate type compressor C1 may be of a type
wherein the drive shaft is provided with a support surface
intersecting the axis of the drive shaft at an angle and a support
shaft formed vertically to the support surface, and wherein the
swash plate for reciprocating the piston is held via a thrust
bearing provided between the piston and the support surface to be
rotatable relative to the support shaft via a rolling bearing.
[0081] The motor-driven swash plate type compressor C1 may be of a
type as disclosed in Japanese Unexamined Patent Publication (Kokai)
No. 10-184539 wherein the refrigerant once discharged from a
compression chamber is further sucked into another compression
chamber and compressed again before being discharge.
[0082] The motor-driven swash plate type compressor C1 may have any
number of cylinders. For instance, the number of cylinders may be
two, three, four, five, six or seven.
[0083] The shaft bore 54A may be eliminated in a region rearward of
the second bifurcated hole 54C. In such a case, the refrigerant in
the shaft bore 54A is introduced to the base plate communication
holes 63A via the second bifurcated hole 54C, the bearing chamber
52D, the boss chamber 52C, the communication hole 52E and the
intermediate chamber 52B. According to this arrangement, the shaft
bore 57A becomes unnecessary.
[0084] In the motor driven scroll type compressor C2, a seal member
may be interposed between the bushing 60 and front side of the
movable base plate 63 to prevent the refrigerant from the shaft
bore 57A from being introduced into a space on the outer
circumference side of the bushing 60.
[0085] The connecting chamber 63B and the connecting passages 63C
may be eliminated.
[0086] The number of base plate communication holes 63A is not
limited to eight, but may be optional, provided no trouble occurs
in the introduction of the refrigerant into the closed chamber
68.
[0087] The connecting passages 63C may be communicated to all the
base plate communication holes 63A. Also, any number of the
connecting passages 63C may be communicated to one base plate
communication hole 63A. Similarly, any number of connecting
passages 63C may be provided.
[0088] As described in detail above, according to the present
invention, it is possible to achieve, in a motor-driven compressor,
in a reliable manner and at a lower cost, improved cooling of the
motor and a reduction in specific volume of the refrigerant and to
suppress a lowering of the refrigerant suction efficiency of the
compression mechanism due to an increase in flow resistance caused
by the viscosity of a lubricating oil.
* * * * *