U.S. patent application number 10/804171 was filed with the patent office on 2004-12-02 for variable capacity rotary compressor.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Cho, Sung Hea, Lee, Seung-Kap.
Application Number | 20040241010 10/804171 |
Document ID | / |
Family ID | 33422274 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040241010 |
Kind Code |
A1 |
Cho, Sung Hea ; et
al. |
December 2, 2004 |
Variable capacity rotary compressor
Abstract
A variable capacity rotary compressor capable of varying a
compression capacity thereof. The variable capacity rotary
compressor includes a housing defined therein with first and second
compressing chambers having different volumes, a rotating shaft
adapted to rotate in the first and second compressing chambers, a
compressing unit arranged in the first and second compressing
chambers, and adapted to perform a compression operation in a
selected one of the first and second compressing chambers in
accordance with a change of a rotating direction of the rotating
shaft, and a drive motor adapted to rotate the rotating shaft in a
first direction or in a second direction, the drive motor being
variable in rotating speed in accordance with an electrical control
operation. The variable capacity rotary compressor can achieve a
multi-stage variation in capacity thereof within a wide range while
reducing a variation range of rotating speed, as compared to
conventional cases, because it is possible not only to mechanically
vary the capacity of the compressing device in accordance with a
change of the rotating direction of the drive motor, but also to
control the rotating speed of the drive motor in accordance with an
electrical control method.
Inventors: |
Cho, Sung Hea; (Suwon-si,
KR) ; Lee, Seung-Kap; (Suwon-si, KR) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700
1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
Suwon-si
KR
|
Family ID: |
33422274 |
Appl. No.: |
10/804171 |
Filed: |
March 19, 2004 |
Current U.S.
Class: |
417/274 ;
417/410.3 |
Current CPC
Class: |
F04C 23/008 20130101;
F01C 21/0845 20130101; F04C 18/3564 20130101; F04C 28/04 20130101;
F04C 23/001 20130101; F04C 11/001 20130101 |
Class at
Publication: |
417/274 ;
417/410.3 |
International
Class: |
F04B 049/00; F04B
035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2003 |
KR |
2003-19060 |
Mar 8, 2004 |
KR |
2004-15385 |
Claims
1. A variable capacity rotary compressor comprising: a housing
defined therein with first and second compressing chambers having
different volumes; a rotating shaft adapted to rotate in the first
and second compressing chambers; a compressing unit arranged in the
first and second compressing chambers, and adapted to perform a
compression operation in a selected one of the first and second
compressing chambers in accordance with a change of a rotating
direction of the rotating shaft; and a drive motor adapted to
rotate the rotating shaft in a first direction or in a second
direction, the drive motor being variable in rotating speed in
accordance with an electrical control operation.
2. The variable capacity rotary compressor according to claim 1,
wherein the compressing unit comprises: first and second sleeves
respectively arranged in the first and second compressing chambers;
first and second eccentric units mounted on the rotating shaft, and
adapted to operate in opposite manners such that one of the first
and second eccentric units selectively rotates an associated one of
the first and second sleeves in an eccentric state in accordance
with the rotating direction change of the rotating shaft, thereby
causing the associated sleeve to perform a compression operation in
an associated one of the first and second compressing chambers,
while the other eccentric unit idly rotates the other sleeve
associated therewith in the other compressing chamber associated
therewith during the compression operation caused by the one
eccentric unit; and first and second vanes respectively arranged in
the first and second compressing chambers to be radially movable
between extended positions thereof and retracted positions
thereof.
3. The variable capacity rotary compressor according to claim 1,
wherein the drive motor is a brushless DC motor.
4. The variable capacity rotary compressor according to claim 1,
wherein the drive motor is an inverter motor.
5. The variable capacity rotary compressor according to claim 2,
wherein: the first eccentric unit comprises a first eccentric cam
fixedly fitted around an outer surface of the rotating shaft in the
first compressing chamber, and a first eccentric bush rotatably
fitted around an outer surface of the first eccentric cam; the
second eccentric unit comprises a second eccentric cam fixedly
fitted around the outer surface of the rotating shaft in the second
compressing chamber, and a second eccentric bush rotatably fitted
around an outer surface of the second eccentric cam; and the
compressing unit further comprises a locking unit adapted to lock
the first and second eccentric bushes in opposite states in
accordance with the rotating direction change of the rotating shaft
such that one of the first and second eccentric bushes is locked in
an eccentric state, while the other eccentric bush is locked in an
eccentricity-released state.
6. The variable capacity rotary compressor according to claim 5,
wherein: the compressing unit further comprises a cylindrical
connecting member adapted to connect the first and second eccentric
bushes such that the first and second eccentric bushes have
opposite eccentric directions; and the locking unit comprises a
locking slot provided at the connecting member to extend
circumferentially, and a locking pin extending radially through the
locking slot to be coupled to the rotating shaft such that the
locking pin is engagable with the locking slot.
7. The variable capacity rotary compressor according to claim 5,
wherein: the first vane is arranged between suction and discharge
ports of the first compressing chamber to be radially movable
between an extended position thereof and a retracted position
thereof while being in contact with an outer surface of the first
sleeve; and the second vane is arranged between suction and
discharge ports of the second compressing chamber to be radially
movable between an extended position thereof and a retracted
position thereof while being in contact with an outer surface of
the second sleeve.
8. A variable capacity rotary compressor comprising: a housing
defined therein with first and second compressing chambers having
different volumes; a rotating shaft adapted to rotate in the first
and second compressing chambers; first and second sleeves
respectively arranged in the first and second compressing chambers;
an eccentric unit mounted on the rotating shaft, and adapted to
operate the first and second sleeves such that one of the first and
second sleeves rotates in an eccentric state when the rotating
shaft rotates in a first direction, thereby performing a
compression operation, while the other sleeve idly rotates during
the compression operation, whereas, when the rotating shaft rotates
in a second direction, the first and second sleeves perform
operations opposite to the operations carried out when the rotating
shaft rotates in the first direction, respectively; and a drive
motor adapted to rotate the rotating shaft in a first direction or
in a second direction, the drive motor being variable in rotating
speed in accordance with an electrical control operation.
9. The variable capacity rotary compressor according to claim 8,
wherein the eccentric unit comprises: first and second eccentric
cams fixedly fitted around an outer surface of the rotating shaft
in the first and second compressing chambers, respectively; first
and second eccentric bushes rotatably fitted around respective
outer surfaces of the first and second eccentric cams; and a
locking unit adapted to lock the first and second eccentric bushes
in opposite states in accordance with a change of a rotating
direction of the rotating shaft such that one of the first and
second eccentric bushes is locked in an eccentric state, while the
other eccentric bush is locked in an eccentricity-released
state.
10. The variable capacity rotary compressor according to claim 8,
wherein the eccentric unit further comprises: a first vane arranged
between suction and discharge ports of the first compressing
chamber to be radially movable between an extended position thereof
and a retracted position thereof while being in contact with an
outer surface of the first sleeve; and a second vane arranged
between suction and discharge ports of the second compressing
chamber to be radially movable between an extended position thereof
and a retracted position thereof while being in contact with an
outer surface of the second sleeve.
11. The variable capacity rotary compressor according to claim 8,
wherein the drive motor is a brushless DC motor.
12. The variable capacity rotary compressor according to claim 8,
wherein the drive motor is an inverter motor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Application
No. 2003-19060, filed Mar. 27, 2003 and Korean Application No.
2004-15385, filed Mar. 8, 2004 in the Korean Intellectual Property
Office, the disclosures of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a variable capacity rotary
compressor, and more particularly to a variable capacity rotary
compressor capable of varying a refrigerant compression ability
thereof in a multi-stage fashion within a wide range.
[0004] 2. Description of the Related Art
[0005] Recently developed air conditioners and coolers of
refrigerators have a function capable of varying a cooling capacity
in accordance with a variation in cooling conditions (for example,
the temperature of a confined space to be cooled, etc.) in order to
achieve an optimal cooling operation while reducing energy
consumption. For this function, such devices typically use a
variable capacity rotary compressor configured to vary a
refrigerant compression ability thereof.
[0006] Known variable capacity rotary compressors generally include
a compressing device adapted to compress a refrigerant, and then to
discharge the compressed refrigerant, and a drive motor adapted to
drive the compressing device. For the drive motor of such a
compressor, a general inverter motor or brushless DC (BLDC) motor
may be used which can vary a rotating speed thereof, depending on a
variation in input electric power. That is, such a compressor can
vary a refrigerant compression ability thereof, that is, a
refrigerant compression capacity thereof, by varying the rotating
speed of the drive motor in accordance with an operation for
controlling input electric power to be applied to the drive
motor.
[0007] However, such a variable capacity rotary compressor has a
problem in that it is difficult to control the refrigerant
compression capacity in a multi-stage fashion within a wide range
because the control to vary the refrigerant compression capacity is
carried out, using a method of operating the compressing device at
a speed controlled by control of the rotating speed of the drive
motor.
[0008] Since, when it is required to increase the compression
capacity of the rotary compressor, the drive motor must rotate at
high speed to operate the compressing device at high speed,
rotational elements of the rotary compressor may be correspondingly
rapidly worn. As a result, the lifespan of the drive motor and
compressing device may be shortened. Also, where the rotating speed
of the drive motor varies abruptly, the entire system of the rotary
compressor may abnormally operate because the operating condition
of the compressing device must vary abruptly. For example, supply
of oil to the compressing device may be ineffectively achieved
because the oil supply conditions in high-speed and low-speed
operations are different from each other.
SUMMARY OF THE INVENTION
[0009] Therefore, it is an aspect of the invention to provide a
variable capacity rotary compressor which is configured to achieve
a variation in the capacity thereof by electrically controlling a
drive motor thereof while using a particular mechanical structure
of a compressing device thereof, thereby being capable of achieving
the capacity variation in a multi-stage fashion within a wide range
while reducing a variation in the rotating speed of a drive motor
thereof.
[0010] Another aspect of the invention is to provide a variable
capacity rotary compressor capable of achieving a variation in
capacity in a multi-stage fashion within a wide range without any
overload to a drive motor thereof and a compressing device
thereof.
[0011] In accordance with one aspect, the present invention
provides a variable capacity rotary compressor comprising: a
housing defined therein with first and second compressing chambers
having different volumes; a rotating shaft adapted to rotate in the
first and second compressing chambers; a compressing unit arranged
in the first and second compressing chambers, and adapted to
perform a compression operation in a selected one of the first and
second compressing chambers in accordance with a change of a
rotating direction of the rotating shaft; and a drive motor adapted
to rotate the rotating shaft in a first direction or in a second
direction, the drive motor being variable in rotating speed in
accordance with an electrical control operation.
[0012] The compressing unit may comprise first and second sleeves
respectively arranged in the first and second compressing chambers,
first and second eccentric units mounted on the rotating shaft, and
adapted to operate in opposite manners such that one of the first
and second eccentric units selectively rotates an associated one of
the first and second sleeves in an eccentric state in accordance
with the rotating direction change of the rotating shaft, thereby
causing the associated sleeve to perform a compression operation in
an associated one of the first and second compressing chambers,
while the other eccentric unit idly rotates the other sleeve
associated therewith in the other compressing chamber associated
therewith during the compression operation caused by the one
eccentric unit, and first and second vanes respectively arranged in
the first and second compressing chambers to be radially movable
between extended positions thereof and retracted positions
thereof.
[0013] The drive motor may be a brushless DC motor.
[0014] The drive motor may be an inverter motor.
[0015] The first eccentric unit may comprise a first eccentric cam
fixedly fitted around an outer surface of the rotating shaft in the
first compressing chamber, and a first eccentric bush rotatably
fitted around an outer surface of the first eccentric cam. The
second eccentric unit may comprise a second eccentric cam fixedly
fitted around the outer surface of the rotating shaft in the second
compressing chamber, and a second eccentric bush rotatably fitted
around an outer surface of the second eccentric cam. The
compressing unit may further comprise a locking unit adapted to
lock the first and second eccentric bushes in opposite states in
accordance with the rotating direction change of the rotating shaft
such that one of the first and second eccentric bushes is locked in
an eccentric state, while the other eccentric bush is locked in an
eccentricity-released state.
[0016] The compressing unit may further comprise a cylindrical
connecting member adapted to connect the first and second eccentric
bushes such that the first and second eccentric bushes have
opposite eccentric directions. The locking unit may comprise a
locking slot provided at the connecting member to extend
circumferentially, and a locking pin extending radially through the
locking slot to be coupled to the rotating shaft such that the
locking pin is engagable with the locking slot.
[0017] The first vane may be arranged between suction and discharge
ports of the first compressing chamber to be radially movable
between an extended position thereof and a retracted position
thereof while being in contact with an outer surface of the first
sleeve. The second vane may be arranged between suction and
discharge ports of the second compressing chamber to be radially
movable between an extended position thereof and a retracted
position thereof while being in contact with an outer surface of
the second sleeve.
[0018] In accordance with another aspect, the present invention
provides a variable capacity rotary compressor comprising: a
housing defined therein with first and second compressing chambers
having different volumes; a rotating shaft adapted to rotate in the
first and second compressing chambers; first and second sleeves
respectively arranged in the first and second compressing chambers;
an eccentric unit mounted on the rotating shaft, and adapted to
operate the first and second sleeves such that one of the first and
second sleeves rotates in an eccentric state when the rotating
shaft rotates in a first direction, thereby performing a
compression operation, while the other sleeve idly rotates during
the compression operation, whereas, when the rotating shaft rotates
in a second direction, the first and second sleeves perform
operations opposite to the operations carried out when the rotating
shaft rotates in the first direction, respectively; and a drive
motor adapted to rotate the rotating shaft in a first direction or
in a second direction, the drive motor being variable in rotating
speed in accordance with an electrical control operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The above aspects, and other features and advantages of the
present invention will become more apparent after reading the
following detailed description when taken in conjunction with the
drawings, in which:
[0020] FIG. 1 is a sectional view illustrating a configuration of a
variable capacity rotary compressor according to the present
invention;
[0021] FIG. 2 is a perspective view illustrating a configuration of
an eccentric unit included in the variable capacity rotary
compressor according to the present invention;
[0022] FIG. 3 is a cross-sectional view illustrating a compression
operation in a first compressing chamber when a rotating shaft of
the variable capacity rotary compressor according to the present
invention rotates in a first direction;
[0023] FIG. 4 is a cross-sectional view illustrating an idle
rotation in a second compressing chamber when the rotating shaft of
the variable capacity rotary compressor according to the present
invention rotates in the first direction;
[0024] FIG. 5 is a cross-sectional view illustrating an idle
rotation in the first compressing chamber when the rotating shaft
of the variable capacity rotary compressor according to the present
invention rotates in a second direction;
[0025] FIG. 6 is a cross-sectional view illustrating a compression
operation in the second compressing chamber when the rotating shaft
of the variable capacity rotary compressor according to the present
invention rotates in the second direction; and
[0026] FIG. 7 is a table showing a variation in compression
capacity depending on a variation in the operation condition of the
variable capacity rotary compressor according to the present
invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE, NON-LIMITING EMBODIMENTS OF
THE INVENTION
[0027] An illustrative, non-limiting embodiment of the present
invention will now be described in detail with reference to the
annexed drawings.
[0028] Referring to FIG. 1, a variable capacity rotary compressor
according to an exemplary embodiment of the present invention is
illustrated. The variable capacity rotary compressor includes a
hermetic casing 10, a drive motor 20 installed in the casing 10 at
an upper portion of the casing 10, and adapted to generate a
rotating force, and a compressing device 30 installed in the casing
10 at a lower portion of the casing 10, and connected to the drive
motor 20 via a rotating shaft 21.
[0029] The drive motor 20 includes a cylindrical stator 22 fixedly
mounted to an inner surface of the casing 10, and a rotor 23
rotatably mounted in the stator 22, and coupled, at a central
portion thereof, to the rotating shaft 21. The drive motor 20 may
comprise a variable speed motor configured to be rotatable in
forward and reverse directions while being capable of controlling a
rotating speed thereof. For such a variable speed motor, an
inverter motor or BLDC motor may be used which can vary a rotating
speed thereof in accordance with an electrical control operation.
As the rotating speed of the drive motor 20 increases or decreases
in accordance with the electrical control operation, the operating
speed of the compressing device 30 is controlled to vary the
compression capacity of the rotary compressor.
[0030] The compressing device 30 includes upper and lower housings
31 and 32 vertically arranged while defining therein first and
second cylindrical compressing chambers 31 and 32 having different
volumes, an intermediate plate 34 arranged between the upper and
lower housings 33a and 33b to partition the first and second
compressing chambers 31 and 32. The compressing device 30 also
includes upper and lower flanges 35 and 36 adapted to close the top
of the first compressing chamber 31 and the bottom of the second
compressing chamber 32, respectively, while rotatably supporting
the rotating shaft 21. The upper and lower flanges 35 and 36 are
mounted to an upper end of the upper housing 33a and a lower end of
the lower housing 33b, respectively.
[0031] The compressing device 30 further includes a compressing
unit arranged in the first and second compressing chambers 31 and
32, and adapted to perform a compression operation in the first or
second compressing chambers 31 and 32 in accordance with rotation
of the rotating shaft 21 in such a manner that the compression
operation is carried out in only a selected one of the first and
second compressing chambers 31 and 32, depending on the rotating
direction of the rotating shaft 21. As shown in FIGS. 2 to 4, the
compressing unit includes first and second eccentric units 40 and
50 vertically arranged to be disposed in the first and second
compressing chambers 31 and 32, respectively, while being mounted
on the rotating shaft 21, and first and second sleeves 37 and 38
rotatably arranged around the eccentric units 40 and 50. The
compressing unit also includes a first vane 61 arranged between
suction and discharge ports 63 and 65 of the first compressing
chamber 31 such that it moves radially to extend into or retract
from the first compressing chamber 31 in a state of being in
contact with an outer surface of the sleeve 37 during a compression
operation carried out in the first compressing chamber 31. The
compressing unit further includes a second vane 62 arranged between
suction and discharge ports 64 and 66 of the second compressing
chamber 32 such that it moves radially to extend into or retract
from the second compressing chamber 32 in a state of being in
contact with an outer surface of the sleeve 38 during a compression
operation carried out in the second compressing chamber 32. The
vanes 61 and 62 are elastically supported by first and second vane
springs 61a and 62a. The suction and discharge ports 63 and 65 of
the first compressing chamber 31 are arranged at opposite sides of
the vane 61, respectively, whereas the suction and discharge ports
64 and 66 of the second compressing chamber 32 are arranged at
opposite sides of the vane 62, respectively.
[0032] The first eccentric unit 40 includes a first eccentric cam
41 fixedly fitted, in an eccentric state, around a portion of the
rotating shaft 21 arranged in the first compressing chamber 31, and
an upper or first eccentric bush 42 rotatably fitted around the
eccentric cam 41. Similarly, the second eccentric unit 50 includes
a second eccentric cam 51 fixedly fitted, in an eccentric state,
around a portion of the rotating shaft 21 arranged in the second
compressing chamber 32 while having the same eccentric direction as
the first eccentric cam 41, and a lower or second eccentric bush 52
rotatably fitted around the eccentric cam 51. As shown in FIG. 2,
the first and second eccentric bushes 42 and 52 are connected by a
cylindrical connecting member 43 such that they are integral while
having opposite eccentric directions, respectively. The first and
second sleeves 37 and 38 are rotatably fitted around the first and
second eccentric bushes 42 and 52, respectively.
[0033] As shown in FIG. 2, an eccentric member 44 is also fixedly
fitted, in an eccentric state, around the rotating shaft 21 between
the first and second eccentric cams 41 and 51 while having the same
eccentric direction as that of the eccentric cams 41 and 51. The
connecting member 43 is rotatably fitted around the eccentric
member 44. A locking unit 80 is arranged between the connecting
member 43 and the eccentric member 44 to cause one of the eccentric
bushes 42 and 52 to be rotated along with the rotating shaft 21 in
an eccentric state while causing the other eccentric bush to be
rotated along with the rotating shaft 21 in an
eccentricity-released state, in accordance with the rotation
direction of the rotating shaft 21. The locking unit 80 includes a
locking pin 81, and a locking slot 82. The locking slot 82 is
formed at the connecting member 43 such that it extends
circumferentially by a desired length. The locking pin 81 extends
radially through the locking slot 82, and is threadedly coupled
with a threaded hole formed at a flat portion of the outer surface
of the eccentric member 44 at one side of the eccentric member 44.
In accordance with rotation of the rotating shaft 21, the locking
pin 81 is engaged with the locking slot 82 at a position where the
first eccentric bush 42 is locked in an eccentric state, and the
second eccentric bush 52 is locked in an eccentricity-released
state, or at another position where the first eccentric bush 42 is
locked in an eccentricity-released state, and the second eccentric
bush 52 is locked in an eccentric state. That is, when the rotating
shaft 21 rotates by a certain angle under the condition in which
the locking pin 81 is coupled to the eccentric member 44, and thus,
the rotating shaft 21, through the locking slot 82, the locking pin
81 is engaged with one of opposite ends 82a and 82b of the locking
slot 82, so that both the eccentric bushes 42 and 52 are rotated,
along with the rotating shaft 21. In accordance with such an
engagement of the locking pin 81 with the locking slot 82, one of
the eccentric bushes 42 and 52 is locked in an eccentric state
thereof, whereas the other eccentric bush is locked in an
eccentricity-released state thereof. As a result, a compression
operation is carried out in one compressing chamber 31 or 32
associated with the eccentric bush 42 or 52 locked in an eccentric
state thereof, whereas an idle rotation is carried out in the other
compressing chamber 32 or 31 associated with the eccentric bush 52
or 42 locked in an eccentricity-released state thereof. When the
rotating direction of the rotating shaft 21 is changed, respective
locked states of the eccentric bushes 42 and 52 are reversed.
[0034] As shown in FIG. 1, the variable capacity rotary compressor
according to the illustrated embodiment of the present invention
also includes a flow path change device 70 adapted to change a
suction flow path so that a refrigerant from a suction conduit 69
can be sucked into the suction port of the compressing chamber
where a compression operation is carried out, that is, the suction
port 63 of the first compressing chamber 31 or the suction port 64
of the second compressing chamber 32.
[0035] The flow path change device 70 includes a cylindrical body
71, and a valve unit arranged in the cylindrical body 71. The
cylindrical body 71 is provided, at a central portion thereof, with
an inlet 72, to which the suction conduit 69 is connected. The
cylindrical body 71 is also provided, at opposite sides thereof,
with first and second outlets 73 and 74, to which conduits 67 and
68 connected to respective suction ports 63 and 64 of the first and
second compressing chambers 31 and 32 are connected, respectively.
The valve unit arranged in the cylindrical body 71 includes a
cylindrical valve seat 75 arranged at the central portion of the
cylindrical body 71, first and second valve members 76 and 77
respectively arranged at opposite lateral portions of the
cylindrical body 71 such that they are movable toward or away from
opposite ends of the valve sheet 75 to close or open the opposite
ends of the valve sheet 75, and a connecting member 78 adapted to
connect the first and second valve members 76 and 77 such that the
first and second valve members 76 and 77 are movable together. When
a compression operation is carried out in the first or second
compressing chamber 31 or 32, a pressure difference is generated
between the outlets 73 and 74, thereby causing the first and second
valve members 76 and 77 to move toward a lower pressure side in the
cylindrical body 71. Thus, the flow path change device 70
automatically changes the suction flow path.
[0036] Now, the mechanical capacity varying operation of the
compressing device carried out depending on a change in the
rotating direction of the rotating shaft in the above described
variable capacity rotary compressor will be described.
[0037] When the rotating shaft 21 rotates in a first direction
(counterclockwise direction), as shown in FIG. 3, the locking pin
81 is engaged with the end 82b of the locking slot 82 in a state in
which the outer surface of the first eccentric bush 42 in the first
compressing chamber 31 is eccentric to the rotating shaft 21.
Accordingly, the first sleeve 37 rotates while coming into contact
with the inner surface of the first compressing chamber 31. Thus, a
compression operation is carried out in the first compressing
chamber 31. In this case, the outer surface of the second eccentric
bush 52 in the second compressing chamber 32 is concentric to the
rotating shaft 21, so that the second sleeve 38 is maintained in a
state of being spaced apart from the inner surface of the second
compressing chamber 32. Thus, an idle rotation is carried out in
the second compressing chamber 32. During the compression operation
in the first compressing chamber 31, a refrigerant is sucked only
into the first compressing chamber 31 through the suction port 63
in accordance with the operation of the flow path change device
70.
[0038] These operations are enabled because the first and second
eccentric cams 41 and 51 have the same eccentric direction, whereas
the first and second eccentric bushes 42 and 52 have opposite
eccentric directions, respectively, that is, because when the
maximum eccentric portions of the first eccentric cam 41 and first
eccentric bush 42 have the same direction, the maximum eccentric
portions of the second eccentric cam 51 and second eccentric bush
52 have opposite directions, respectively.
[0039] On the other hand, when the rotating shaft 21 rotates at the
same speed as that of the above case in a second direction
(clockwise direction) reverse to that of the above case to perform
a compression operation, as shown in FIG. 5, the locking pin 81 is
engaged with the end 82a of the locking slot 82 in a state in which
the outer surface of the first eccentric bush 42 in the first
compressing chamber 31 is released from the eccentric state thereof
to the rotating shaft 21. Accordingly, the first sleeve 37 is
maintained in a state of being spaced apart from the inner surface
of the first compressing chamber 31, so that an idle rotation is
carried out in the first compressing chamber 31. In this case, the
outer surface of the second eccentric bush 52 in the second
compressing chamber 32 is eccentric to the rotating shaft 21, as
shown in FIG. 6. Accordingly, the second sleeve 38 rotates while
coming into contact with the inner surface of the second
compressing chamber 32. Thus, a compression operation is carried
out in the second compressing chamber 32. During the compression
operation in the second compressing chamber 32, a refrigerant is
sucked only into the second compressing chamber 32 in accordance
with the operation of the flow path change device 70.
[0040] Thus, it is possible to achieve a variation in capacity in
accordance with the mechanical operation of the compressing device
30 caused by simply changing the rotating direction of the rotating
shaft 21 in accordance with the present invention. That is, where a
compression operation is carried out in the second compressing
chamber 32 as the rotating shaft 21 rotates in the second
direction, a reduction in compression capacity is achieved even
under the condition in which the drive motor 20 rotates at the same
speed as that in the compression operation in the first compressing
chamber 31. This is because the second compressing chamber 32 has a
volume smaller than that of the first compressing chamber 31. For
example, where the second compressing chamber 32 has a volume
corresponding to 50% of the volume of the first compressing chamber
31, it has a compression capacity corresponding to 50% of the
compression capacity of the first compressing chamber 31 under the
condition in which the rotating speed of the drive motor 20 is
constant.
[0041] In accordance with the present invention, it is also
possible to control the variation in the compression capacity of
the rotary compressor in a multi-stage fashion within a wide range
by not only implementing the above described mechanical capacity
variation of the compressing device 30, but also implementing a
variation in capacity through control of the rotating speed of the
drive motor 20. That is, the compression capacity of the rotary
compressor can be controlled in a multi-stage fashion with a wide
range by varying the frequency of input electric power, to be
applied to the drive motor 20, within a range of 20 to 120 Hz to
control the rotating speed of the drive motor 20, while changing
the rotating direction of the drive motor 20.
[0042] For example, where the volume of the second compressing
chamber 32 corresponds to 50% of the volume of the first
compressing chamber 31, the frequency of input electric power to be
applied to the drive motor 20 is controlled to be 20 Hz, 60 Hz, and
120 Hz, in order to control the rotating speed of the drive motor
20 to be a low speed, a medium speed, and a high speed,
respectively, and the rotating direction of the drive motor 20 is
controlled to be a first or second direction, a multi-stage
capacity variation within a wide range may be achieved, as
described in a table of FIG. 7. The results of FIG. 7 represent
relative compression capacity variations under various operation
conditions achieved when a compression operation is carried out in
the first compressing chamber 31 as the drive motor 20 rotates in
the first direction, and it is assumed that the compression
capacity obtained at the medium rotating speed (60 Hz) corresponds
to 100%.
[0043] The first example in FIG. 7 corresponds to the case in which
a compression operation is carried out in the first compressing
chamber 31 as the drive motor 20 rotates in the first direction
(counterclockwise direction in FIG. 3), and the rotating speed of
the drive motor 20 is controlled to be the low speed (20 Hz). In
this case, a compression capacity corresponding to 33% of the
second example in FIG. 7 is obtained.
[0044] The second example corresponds to the case in which a
compression operation is carried out in the first compressing
chamber 31 as the drive motor 20 rotates in the first direction,
and the rotating speed of the drive motor 20 is controlled to be
the medium speed (60 Hz). In this case, a compression capacity of
100% is obtained.
[0045] The third example corresponds to the case in which a
compression operation is carried out in the first compressing
chamber 31 as the drive motor 20 rotates in the first direction,
and the rotating speed of the drive motor 20 is controlled to be
the high speed (120 Hz). In this case, a compression capacity
corresponding to 200% of the second example is obtained.
[0046] The fourth example corresponds to the case in which a
compression operation is carried out in the second compressing
chamber 32 as the drive motor 20 rotates in the second direction
(clockwise direction in FIG. 6), and the rotating speed of the
drive motor 20 is controlled to be the low speed (20 Hz). In this
case, a compression capacity corresponding to 16.6% of the second
example is obtained.
[0047] The fifth example corresponds to the case in which a
compression operation is carried out in the second compressing
chamber 32 as the drive motor 20 rotates in the second direction,
and the rotating speed of the drive motor 20 is controlled to be
the medium speed (60 Hz). In this case, a compression capacity
corresponding to 50% of the second example is obtained.
[0048] The sixth example corresponds to the case in which a
compression operation is carried out in the second compressing
chamber 32 as the drive motor 20 rotates in the second direction,
and the rotating speed of the drive motor 20 is controlled to be
the high speed (120 Hz). In this case, a compression capacity
corresponding to 100% of the second example is obtained.
[0049] Thus, in accordance with the present invention, it is
possible to achieve a multi-stage capacity variation within a wide
range, as compared to conventional cases, by not only implementing
a mechanical capacity variation of the compressing device 30
through a change of the rotating direction of the drive motor 20,
but also implementing a variation in capacity through control of
the rotating speed of the drive motor 20.
[0050] In particular, as shown in FIG. 7, the compression capacity
obtained under the operation condition of the second example is
equal to the compression capacity obtained under the operation
condition of the sixth example. In either case, accordingly, the
same result is obtained. However, it is preferred that the
operation condition of the second example be selected in that it is
possible, in this case, to prevent the elements of the compressor
from being overloaded by virtue of a lower rotating speed of the
drive motor 20, thereby extending the lifespan of those elements,
while obtaining the same compression capacity. Thus, in accordance
with the present invention, it is possible to select, from a
plurality of operation conditions providing the same compression
capacity, an operation condition capable of minimizing an overload
applied to the drive motor 20 and compressing device 30.
[0051] Although not illustrated in FIG. 7, the rotating speed of
the drive motor 20 may be controlled in a more diversified fashion,
using various frequencies of input electric power, to be applied to
the drive motor 20, other than 20 Hz, 60 Hz, and 120 Hz. In this
case, it is also possible to prevent the drive motor 20 and
compressing unit 30 from being overloaded by setting an appropriate
operation condition such that the same compression capacity is
obtained without an excessively high or low-speed rotation of the
drive motor 20.
[0052] As apparent from the above description, the variable
capacity rotary compressor according to the present invention can
achieve a multi-stage variation in capacity thereof within a wide
range while reducing a variation range of rotating speed, as
compared to conventional cases, because it is possible not only to
mechanically vary the capacity of the compressing device in
accordance with a change of the rotating direction of the drive
motor, but also to control the rotating speed of the drive motor in
accordance with an electrical control method.
[0053] Since a multi-stage capacity variation within a wide range
can be achieved without an excessively high or low-speed rotation
of the drive motor, it is also possible to prevent the elements of
the compressor from being overloaded, thereby achieving an
extension of the lifespan of those elements and an improvement in
the reliability of the compressor.
[0054] Although the preferred embodiments of the invention have
been disclosed for illustrative purposes, those skilled in the art
will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
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