Title: Rotary compressor
Abstract: A rotary compressor having a plurality of compression chambers and adapted to vary a compression capacity according to a direction of rotation of roller pistons within the compression chambers. A rotating shaft provided with a plurality of eccentric parts drives the roller pistons to compress refrigerant in the compression chambers by eccentric rotations of the eccentric parts. A reversible motor selectively rotates the rotating shaft in opposite directions, and a clutch engages the roller pistons such that the roller pistons perform a compressing action or an idle action according to a rotating direction of the rotating shaft, thus varying the compression capacity of the compressor according to a rotating direction of the rotating shaft. Thus, the compression capacity may be varied without using an inverter circuit.
Patent Number: 6,860,724 Issued on 03/01/2005 to Cho, et al.
| Inventors:
|
Cho; Sung-Hea (Suwon, KR);
Park; Sung-Yeon (Yongin, KR);
Jung; Chang-Ho (Suwon, KR);
Kim; Jong-Goo (Seoul, KR)
|
| Assignee:
|
Samsung Electronics Co., Ltd. (Suwon-si, KR)
|
| Appl. No.:
|
352000 |
| Filed:
|
January 28, 2003 |
Foreign Application Priority Data
| Oct 09, 2002[KR] | 2002-61462 |
| Current U.S. Class: |
417/218; 417/223; 417/326; 418/29 |
| Intern'l Class: |
F04B 049//00 |
| Field of Search: |
417/218,221,223,326
418/29
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Freay; Charles G.
Attorney, Agent or Firm: Staas & Halsey LLP
Claims
What is claimed is:
1. A rotary compressor, comprising:
a plurality of cylinders;
a rotating shaft provided with a plurality of eccentric parts which are
eccentrically rotated in compression chambers defined in the cylinders;
a plurality of roller pistons rotationally coupled with the eccentric parts
and which compress refrigerant in the compression chambers;
a reversible motor which rotates the shaft in selectively opposite
directions; and
a clutch which clutches the roller pistons such that the roller pistons
perform a compressing action or an idle action according to a rotating
direction of the rotating shaft, thus varying a compression capacity of
the compressor according to the rotating direction of the rotating shaft.
2. The rotary compressor as set forth in claim 1, wherein the cylinders
comprise first and second cylinders arranged at upper and lower positions,
respectively, and having different compression capacities, with first and
second eccentric parts provided in the first and second cylinders,
respectively, and first and second roller pistons provided in the first
and second cylinders, respectively.
3. The rotary compressor as set forth in claim 2, wherein the clutch
comprises:
first and second cam bushings having a cylindrical shape and provided
between the first eccentric part and the first roller piston and between
the second eccentric part and the second roller piston, respectively, and
being eccentric in a radial direction; and
an eccentricity control unit which controls the first and second cam
bushings such that eccentric directions of the first and second cam
bushings are equal to or opposite to eccentric directions of the first and
second eccentric parts when the rotating direction of the rotating shaft
is changed, thus controlling the first and second roller pistons to
selectively perform compressing actions thereof.
4. The rotary compressor as set forth in claim 3, wherein the eccentricity
control unit comprises:
first and second stop pins provided on the rotating shaft to be rotated
along with the rotating shaft; and
a stopper which limits a slidable rotating range of each of the first and
second stop pins with respect to an associated one of the first and second
cam bushings within a predetermined angular range when the rotating
direction of the rotating shaft is changed.
5. The rotary compressor as set forth in claim 4, wherein:
the stopper comprises arc-shaped first and second locking steps, the first
locking step being downwardly projected from a lower surface of the first
cam bushing and the second locking step being upwardly projected from an
upper surface of the second cam bushing; and
the first and second stop pins are provided on the rotating shaft in such a
way as to be perpendicular to the rotating shaft such that each of the
first and second stop pins is stopped at either end of an associated one
of the first and second locking steps according to a rotating direction of
the rotating shaft.
6. The rotary compressor as set forth in claim 3, wherein the first and
second cam bushings engage with each other by toothed parts provided on
the first and second cam bushings, such that the first and second cam
bushings are rotated together when the rotating shaft is rotated.
7. The rotary compressor as set forth in claim 6, wherein the toothed parts
comprise:
an arc-shaped downward toothed part provided on a lower surface of the
first cam bushing; and
an arc-shaped upward toothed part provided on an upper surface of the
second cam bushing, and engaging with the downward toothed part.
8. The rotary compressor as set forth in claim 7, wherein the eccentricity
control unit comprises a stop pin provided on the rotating shaft, the stop
pin perpendicularly engaged with the rotating shaft, rotating along with
the rotating shaft, and alternatively stopped at first and second ends of
the engaged toothed parts, to limit a slidable rotating range of the
rotating shaft with respect to the first and second cam bushings within a
predetermined angular range.
9. The rotary compressor as set forth in claim 3, wherein the first and
second cam bushings are connected to each other by a rod assembly
comprising at least one rod, such that the first and second cam bushings
are rotated together with the rotating shaft.
10. The rotary compressor as set forth in claim 9, wherein at least one rod
hole is formed on a lower surface of the first cam bushing and on an upper
surface of the second cam bushing at a position corresponding to the rod
hole formed on the first cam bushing, respectively, and both ends of the
rod are inserted into the rod holes formed on the first and second cam
bushings so as to connect the first and second cam bushings to each other.
11. The rotary compressor as set forth in claim 10, wherein the
eccentricity control unit comprises a stop pin provided on the rotating
shaft, the stop pin perpendicularly engaged with the rotating shaft,
rotating along with the rotating shaft, and alternatively stopped at first
and second sides of the rod assembly, to limit a slidable rotating range
of the rotating shaft with respect to the first and second cam bushings
within a predetermined angular range.
12. The rotary compressor as set forth in claim 3, wherein the first and
second cam bushings are connected to each other by a cylindrical
connecting part such that the first and second cam bushings are rotated
together when the rotating shaft is rotated.
13. The rotary compressor as set forth in claim 12, wherein the
eccentricity control unit comprises:
a stop channel circumferentially formed along a part of a sidewall of the
cylindrical connecting part; and
a stop pin provided on the rotating shaft the stop pin perpendicularly
engaged with the rotating shaft, rotating along with the rotating shaft,
and alternatively stopped at first and second ends of the stop channel, to
limit a slidable rotating range of the rotating shaft with respect to the
first and second cam bushings within a predetermined angular range.
14. The rotary compressor as set forth in claim 5, wherein the rotating
shaft is provided with a plurality of pin holes and each stop pin is
inserted into a respective one of the pin holes.
15. The rotary compressor as set forth in 8, wherein the rotating shaft is
provided with a pin hole and the stop pin is inserted into the pin hole.
16. The rotary compressor as set forth in 11, wherein the rotating shaft is
provided with a pin hole and the stop pin is inserted into the pin hole.
17. The rotary compressor as set forth in 13, wherein the rotating shaft is
provided with a pin hole and the stop pin is inserted into the pin hole.
18. The rotary compressor as set forth in claim 14, wherein an internal
threaded part is formed on an inner surface of each pin hole and an
external threaded part is formed on an outer surface of each stop pin,
thus allowing the stop pins to be screwed into the respective ones of the
pin holes.
19. The rotary compressor as set forth in claim 15, wherein an internal
threaded part is formed on an inner surface of the pin hole and an
external threaded part is formed on an outer surface of the stop pin, thus
allowing the stop pin to be screwed into the pin hole.
20. The rotary compressor as set forth in claim 16, wherein an internal
threaded part is formed on an inner surface of the pin hole and an
external threaded part is formed on an outer surface of the stop pin, thus
allowing the stop pin to be screwed into the pin hole.
21. The rotary compressor as set forth in claim 17, wherein an internal
threaded part is formed on an inner surface of the pin hole and an
external threaded part is formed on an outer surface of the stop pin, thus
allowing the stop pin to be screwed into the pin hole.
22. The rotary compressor as set forth in claim 3, wherein the eccentricity
of each of the first and second eccentric parts or each of the first and
second cam bushings is determined to allow an associated one of the first
and second roller pistons to be eccentrically rotated to a predetermined
extent during the idle action of the associated roller piston.
23. The rotary compressor as set forth in claim 3, wherein the eccentricity
control unit allows each of the first and second roller pistons to
eccentrically rotate to a predetermined extent during an idle action of
the first or second roller piston.
24. The rotary compressor as set forth in claim 16, wherein each of the
first and second roller pistons is provided with a relief along respective
upper and lower edges of an inner surface of each of the first and second
roller pistons.
25. The rotary compressor as set forth in claim 17, wherein each of the
first and second roller pistons is provided with a relief along respective
upper and lower edges of an inner surface of each of the first and second
roller pistons.
26. The rotary compressor as set forth in claim 24, wherein the reliefs
provided along the respective upper and lower edges of the inner surface
are symmetrically formed.
27. The rotary compressor as set forth in claim 25, wherein the reliefs
provided along the respective upper and lower edges of the inner surface
are symmetrically formed.
28. The rotary compressor as set forth in claim 24, further comprising:
a disc-shaped middle plate hermetically separating the first and second
cylinders from each other and having a central opening;
wherein each of the reliefs has one of a diagonal cross-section and a
rectangular multi-stepped cross-section, and each relief is formed so that
any point on a horizontal surface of the first or second roller piston,
which point is in contact with the disc-shaped middle plate, is not
exposed to the central opening of the middle plate when the first or
second roller piston is eccentrically rotated by a predetermined extent
during an idle action of the first or second roller piston.
29. The rotary compressor as set forth in claim 25, further comprising:
a disc-shaped middle plate hermetically separating the first and second
cylinders from each other and having a central opening,
wherein each of the reliefs has one of a diagonal cross-section and a
rectangular multi-stepped cross-section, and each relief is formed so that
any point on a horizontal surface of the first or second roller piston,
which point is in contact with the disc-shaped middle plate, is not
exposed to the central opening of the middle plate when the first or
second roller piston is eccentrically rotated by a predetermined extent
during an idle action of the first or second roller piston.
30. The rotary compressor as set forth in claim 24 wherein a depth of each
relief is determined according to a difference between a centrifugal force
and an inertia moment generated in an associated one of the first and
second cylinders.
31. The rotary compressor as set forth in claim 25, wherein a depth of each
relief is determined according to a difference between a centrifugal force
and an inertia moment generated in an associated one of the first and
second cylinders.
32. The rotary compressor as set forth in claim 6, wherein an eccentric
direction of the first cam bushing is opposite to an eccentric direction
of the second cam bushing within a predetermined angular range.
33. The rotary compressor as set forth in claim 9, wherein an eccentric
direction of the first cam bushing is opposite to an eccentric direction
of the second cam bushing within a predetermined angular range.
34. The rotary compressor as set forth in claim 12, wherein an eccentric
direction of the first cam bushing is opposite to an eccentric direction
of the second cam bushing within a predetermined angular range.
35. The rotary compressor as set forth in claim 32, wherein the
predetermined angular range is limited within .+-.30.degree..
36. The rotary compressor as set forth in claim 33, wherein the
predetermined angular range is limited within .+-.30.degree..
37. The rotary compressor as set forth in claim 34, wherein the
predetermined angular range is limited within .+-.30.degree..
38. The rotary compressor as set forth in claim 3, wherein the rotating
shaft is provided at a predetermined position under the second eccentric
part with a support step so as to upwardly support the second cam bushing
and downwardly support a lower flange supporting the rotating shaft.
39. The rotary compressor as set forth in claim 3, wherein an inner
diameter of each of the first and second cam bushings is equal to or
larger than an outer diameter of the rotating shaft, thus allowing the
first and second cam bushings to be axially fitted over the rotating shaft
connected to the reversible motor when assembling the compressor.
40. The rotary compressor as set forth in claim 1, wherein each of the
first and second roller pistons is provided with a relief along respective
upper and lower edges of an inner surface of each of the first and second
roller pistons.
41. The rotary compressor as set forth in claim 40, wherein the upper and
lower reliefs are symmetrically formed.
42. The rotary compressor as set forth in claim 26, wherein each of the
reliefs has one a diagonal cross-section and a rectangular multi-stepped
cross-section, and each relief is formed so that any point on a horizontal
surface of the first or second roller piston, which point is in contact
with a disc-shaped middle plate hermetically separating the first and
second cylinders from each other, is not exposed to a central opening of
the middle plate during an idle action of the first or second roller
piston.
43. The rotary compressor as set forth in claim 40, wherein a depth of each
relief is determined according to a centrifugal force and an inertia
moment generated in an associated one of the first and second cylinders.
44. The rotary compressor as set forth in claim 3, wherein an outer
diameter of the first eccentric part is smaller than or equal to an outer
diameter of the second eccentric part, and an inner diameter of the first
cam bushing is smaller than or equal to an inner diameter of the second
cam bushing.
45. The rotary compressor as set forth in claim 3, wherein each of the
first and second cam bushings is axially divided into pieces, thus
allowing the first and second cam bushings to be inserted and seated into
openings of the first and second roller pistons, respectively, when
assembling the compressor.
46. The rotary compressor as set forth in claim 1, wherein the eccentric
parts of the rotating shaft have the same eccentric direction.
47. The rotary compressor as set forth in claim 1, wherein respective outer
diameters of the eccentric parts are equal.
48. The rotary compressor as set forth in claim 2, wherein the first
cylinder has a larger compression capacity than a compression capacity of
the second cylinder.
49. The rotary compressor as set forth in claim 48, wherein a ratio of the
compression capacity of the first cylinder to the compression capacity of
the second cylinder is 10:4.
50. The rotary compressor as set forth in claim 2, wherein a compression
capacity of the first cylinder is not equal to a compression capacity of
the second cylinder.
51. A variable output compressor, comprising:
a plurality of compression chambers;
a plurality of roller pistons, each roller piston disposed in a respective
one of the plurality of compression chambers and adapted to be
eccentrically driven;
an eccentric drive system which:
drives at least one of the plurality of roller pistons to compress a gas at
a first compression ratio in one of the plurality of compression chambers,
where the at least one of the roller pistons is being driven in a first
angular direction; and
drives at least one other of the plurality of roller pistons to compress
the gas at a second compression ratio in another of the plurality of
compression chambers, where the at least one other of the roller pistons
is being driven in a second angular direction.
52. The rotary compressor as set forth in claim 51, wherein the eccentric
drive system:
drives the at least one of the plurality of roller pistons to compress the
gas at a third compression ratio in the one of the plurality of
compression chambers, where the at least one of the plurality of roller
pistons is being driven in the second angular direction; and
drives the at least one other of the plurality of roller pistons to
compress the gas at a fourth compression ratio in the another of the
plurality of compression chambers, where the at least one other of the
plurality of roller pistons is being driven in the first angular
direction.
53. The rotary compressor as set forth in claim 52, wherein one of the
first and third compression ratios is zero.
54. The rotary compressor as set forth in claim 52, wherein one of the
second and fourth compression ratios is zero.
55. The rotary compressor as set forth in claim 51, wherein a ratio of the
first compression ratio to the second compression ratio is about 10:4.
56. The rotary compressor as set forth in claim 51, wherein a ratio of the
first compression ratio to the second compression ratio is about 4:10.
57. The rotary compressor as set forth in claim 51, wherein the first and
second compression ratios are equal.
58. The rotary compressor as set forth in claim 52, wherein the third and
fourth compression ratios are equal.
59. The rotary compressor as set forth in claim 53, wherein the first and
second angular directions are determined by a reversible motor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Application No. 2002-61462,
filed Oct. 9, 2002, in the Korean Intellectual Property Office, the
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to a rotary compressor having a
plurality of cylinders and, more particularly, to a rotary compressor
which varies a compression capacity as desired, by selectively engaging
one or a plurality of roller pistons according to a direction of rotation
of a rotating shaft which drives the rotating pistons.
2. Description of the Related Art
As is well known to those skilled in the art, compressors are widely used
in a variety of refrigeration systems, such as refrigerators and air
conditioners. In such refrigeration systems, the compressor compresses
refrigerant to highly pressurize the refrigerant prior to discharging the
high-temperature and high-pressure refrigerant to a condenser. The
compressors are typically classified into linear compressors,
reciprocating compressors and rotary compressors. The present invention
relates to a rotary compressor compressing a refrigerant by a roller
piston which is arranged in a cylinder and is eccentrically rotated. More
particularly, the present invention relates to a rotary compressor which
is provided with a plurality of cylinders and which varies a capacity of
the rotary compressor.
A conventional rotary compressor of a double cylinder structure will be now
be described. Referring now to FIG. 1, a conventional rotary compressor
includes a hermetic casing 100, with a drive unit 10 and a compressing
unit 11 installed in the casing 100. A rotating shaft 101 is arranged at a
center of the drive unit 10, and is provided with first and second
eccentric parts 101a and 101b. A cylindrical rotor 102 surrounds the
rotating shaft 101 and is rotated by an electromagnetic force. A
cylindrical stator 103 surrounds the rotor 102 at a position which is
spaced apart from the rotor 102 by a predetermined interval, and is
fixedly mounted to the casing 100, with a coil wound around the stator
103. Further, a weight balancer 104 is provided at the bottom of the rotor
102 so as to reduce vibration and noise of the compressor due to an
imbalance of the center of the rotation of the eccentric parts 101a and
101b. The compressing unit 11 includes the first and second eccentric
parts 101a and 101b of the rotating shaft 101, and first and second
cylinders 106a and 106b in which first and second roller pistons 105a and
105b are arranged. The upper surface of the first cylinder 106a is
hermetically closed by an upper flange 107 which supports the rotating
shaft 101, while the lower surface of the first cylinder 106a is closed by
a middle plate 108. In this case, the middle plate 108 is positioned
between the first and second cylinders 106a and 106b to hermetically
separate a compression chamber 201a of the first cylinder 106a from a
compression chamber 201b of the second cylinder 106b. Similarly, the lower
surface of the second cylinder 106b is hermetically closed by a lower
flange 109 which supports the rotating shaft 101, while the upper surface
of the second cylinder 106b is closed by the middle plate 108. In such a
rotary compressor having a double cylinder structure, after a refrigerant
is compressed in the compressing unit 11 by a rotating force of the drive
unit 10, the compressed refrigerant is discharged to the outside of the
cylinder 106. Next, the refrigerant is discharged to the outside of the
compressor through a refrigerant outlet pipe 110, and then flows into a
condenser (not shown). In FIG. 1, the reference numeral 111 denotes an oil
container for containing oil therein. Several components of the compressor
are smoothly operated due to the lubricating effect of the oil.
The operation of the rotary compressor having a double cylinder structure
will be described with reference to FIG. 2, which is a sectional view of
one of the first and second cylinders 106a or 106b included in the
compressor.
When the rotating shaft 101 is rotated in a direction as shown by an arrow
in FIG. 2, the roller piston 105 is eccentrically rotated while being in
contact with an inner circumferential surface of the cylinder 106, by the
rotation of the eccentric part 101a or 101b, provided on the rotating
shaft 101. During the rotation, a space distribution within a compression
chamber 201, which comprises an intake part 21a and a discharge part 21b,
is varied. That is, the intake part 21a becomes large in volume while
becoming low in pressure, so refrigerant of an accumulator 112 is sucked
into the intake part 21a through an intake hole 202. As the volume of the
discharge part 21b becomes small due to the rotation of the roller piston
105, the refrigerant in the discharge part 21b is highly pressurized.
Thus, the highly pressurized refrigerant is discharged to the outside of
the cylinder 106 through an outlet hole 203. Thereafter, the refrigerant
is discharged to the outside of the compressor through the refrigerant
outlet pipe 110. The intake part 21a and the discharge part 21b are
hermetically separated from each other by a vane 204 which is biased by a
spring 204a, thus preventing the refrigerant from flowing between the
intake part 21a and the discharge part 21b.
However, the conventional rotary compressor having the double cylinder
structure has a problem that excessive vacuum may be generated in the
discharge part 21b of the cylinder 106 when the rotating shaft 101 is
rotated in a reverse direction, so the compressor may be broken. Thus, the
conventional rotary compressor uses a motor which rotates the rotating
shaft 101 in a single direction. Therefore, the first and second cylinders
106a and 106b and other associated components are constructed such that
the refrigerant is compressed during a single directional rotation of the
rotating shaft 101, so only a compressing action is ever performed in the
first and second cylinders 106a and 106b. Thus, an expensive inverter
circuit is required to vary a compression capacity of such a compressor.
Moreover, a control board is additionally required to control the inverter
circuit, thus undesirably increasing a production cost of the compressor
and increasing power consumption when the compressor is operated.
A reciprocating compressor having a construction for varying a compression
capacity is disclosed in U.S. Pat. No. 6,132,177. However, such a
construction is applied to only a reciprocating compressor. Substantially,
there has not been developed a rotary compressor having a construction for
varying a compression capacity as desired. In addition, the design of a
rotary compressor having a construction which varies a compression
capacity has been recognized as being very difficult.
SUMMARY OF THE INVENTION
Accordingly, it is an aspect of the present invention to provide a rotary
compressor with a plurality of cylinders, in which a compression capacity
is variable as desired without using an inverter circuit or a control
board for controlling the inverter circuit.
Additional aspects and advantages of the invention will be set forth in
part in the description which follows and, in part, will be obvious from
the description, or may be learned by practice of the invention.
The foregoing and/or other aspects of the present invention are achieved by
providing a rotary compressor, comprising a plurality of cylinders, a
rotating shaft provided with a plurality of eccentric parts which are
eccentrically rotated in compression chambers defined in the cylinders,
and a plurality of roller pistons which compress refrigerant in the
compression chambers by eccentric rotations of the eccentric parts, the
rotary compressor further comprising a reversible motor which rotates the
rotating shaft in selectively opposite directions, and a clutch which
engages the roller pistons such that the roller pistons perform a
compressing action or an idle action according to the rotating direction
of the rotating shaft, thus varying a compression capacity of the
compressor according to the rotating direction of the rotating shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and/or other aspects and advantages of the invention will become
apparent and more readily appreciated from the following description,
taken in conjunction with the accompanying drawings of which:
FIG. 1 is a side sectional view showing a conventional rotary compressor;
FIG. 2 is a sectional view showing a compressing unit of the conventional
rotary compressor shown in FIG. 1;
FIG. 3 is a side sectional view of a rotary compressor according to an
embodiment of the present invention;
FIG. 4 is a sectional view of a compressing unit included in the rotary
compressor shown in FIG. 3, showing a compression action in a first
chamber with rotation in a clockwise direction;
FIG. 5 is a sectional view of the compressing unit included in the rotary
compressor shown in FIG. 3, showing a transition between a compression
action and an idle action in the first chamber;
FIG. 6 is a sectional view of the compressing unit included in the rotary
compressor shown in FIG. 3, showing an idle action in the first chamber;
FIG. 7 is a sectional view of the compressing unit included in the rotary
compressor shown in FIG. 3, showing a compression action in a second
chamber;
FIG. 8 is a sectional view of the compressing unit included in the rotary
compressor shown in FIG. 3, showing an idle action in the second chamber;
FIG. 9 is a side view of a first configuration of a rotating shaft of the
rotary compressor according to the present invention;
FIG. 10 is a side view of a second configuration of a rotating shaft of the
rotary compressor according to the present invention;
FIG. 11 is a side view of a third configuration of a rotating shaft of the
rotary compressor according to the present invention;
FIG. 12 is a side view of a fourth configuration of a rotating shaft of the
rotary compressor according to the present invention;
FIG. 13A is a perspective view showing a first cam bushing according to an
embodiment of the present invention;
FIG. 13B is a perspective view showing a second cam bushing according to an
embodiment of the present invention;
FIG. 14 is a perspective view showing the first and second cam bushings of
FIGS. 13A and 13B assembled with a rotating shaft;
FIG. 15A is a perspective view showing a first cam bushing according to
another embodiment of the present invention;
FIG. 15B is a perspective view showing a second cam bushing according to
another embodiment of the present invention;
FIG. 16 is a perspective view showing the first and second cam bushings of
FIGS. 15A and 15B assembled with a rotating shaft;
FIG. 17 is an exploded perspective view showing first and second cam
bushings according to a further embodiment of the present invention;
FIG. 18 is a perspective view showing first and second cam bushings
according to still another embodiment of the present invention;
FIG. 19 is a perspective view showing the first and second cam bushings of
FIG. 18 assembled with a rotating shaft;
FIG. 20 is a perspective view showing one of first and second cam bushings
according to still another embodiment of the present invention;
FIG. 21 is a perspective view showing first and second cam bushings
according to still another embodiment of the present invention;
FIG. 22 is a sectional view showing one of the first and second cam
bushings of FIG. 20 or 21 set in an associated cylinder;
FIG. 23 is a perspective view showing a possible problem of the first and
second roller pistons;
FIG. 24 is a perspective view showing the first or second roller pistons
having a relief formed on an inner diameter thereof according to the
present invention;
FIG. 25 is a sectional view showing the first or second roller pistons
having a relief formed on an inner diameter thereof according to the
present invention; and
FIG. 26 is a view showing the operational effect of the first and second
roller pistons having the reliefs shown in FIGS. 24 and 25.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the embodiments of the present
invention, examples of which are illustrated in the accompanying drawings,
wherein like reference numerals refer to like elements throughout.
FIG. 3 is a side sectional view showing a rotary compressor according to an
embodiment of the present invention. As shown in FIG. 3, the rotary
compressor includes a hermetic casing 300 which defines an external
envelope and an appearance of the compressor. A drive unit 30 and a
compressing unit 31 are housed in the casing 300. A rotating shaft 301 is
set at a center of the drive unit 30, and is provided with first and
second eccentric parts 301a and 301b. A rotor 302 is mounted to the
rotating shaft 301, and is rotated by an electromagnetic force generated
by an interaction of a permanent magnet which is buried in or attached to
the rotor 302 and an electromagnet formed in a stator 303. The stator 303
surrounds the rotor 302 at a position which is spaced apart from the rotor
302 by a predetermined interval, and is fixedly mounted to the casing 300,
with a coil wound around the stator 303 for conducting an electrical
current to generate the stator electromagnet. In the rotary compressor
according to the present invention, a motor comprising the rotor 302 and
the stator 303 is constructed as a reversible motor which rotates the
rotating shaft 301 in selectively opposite directions. Further, a weight
balancer 304 is mounted to the bottom of the rotor 302 so as to reduce the
vibration and noise of the compressor due to an imbalance of the center of
the rotation of the eccentric parts 301a and 301b.
The compressing unit 31 comprises first and second cylinders 307a and 307b.
The first eccentric part 301a and a first roller piston 305a are provided
in the first cylinder 307a, and the second eccentric part 301b and a
second roller piston 305b are provided in the second cylinder 307b.
Further, a first cam bushing 306a is provided between the first eccentric
part 301a and the first roller piston 305a, and a second cam bushing 306b
is provided between the second eccentric part 301b and the second roller
piston 305b. The first cam bushing 306a makes the first roller piston 305a
eccentrically rotate when the rotating shaft 301 rotates clockwise, thus
performing a compressing action in the first cylinder 307a. When the
rotating shaft 301 rotates counterclockwise, the first cam bushing 306a
makes the first roller piston 305a idly rotate so that the compressing
action is not performed in the first cylinder 307a. The second cam bushing
306b makes the second roller piston 305b idly rotate when the rotating
shaft 301 rotates clockwise, so that the compressing action is not
performed in the second cylinder 307b during the clockwise rotation. When
the rotating shaft 301 rotates counterclockwise, the second cam bushing
306b makes the second roller piston 305b eccentrically rotate, thus
performing a desired compressing action in the second cylinder 307b. An
upper surface of the first cylinder 307a is hermetically closed by an
upper flange 310 which supports the rotating shaft 301, and a lower
surface of the first cylinder 307a is closed by a middle plate 309. The
middle plate 309 is positioned between the first and second cylinders 307a
and 307b to hermetically separate a compression chamber 308a of the first
cylinder 307a from a compression chamber 308b of the second cylinder 307b.
A lower surface of the second cylinder 307b is hermetically closed by a
lower flange 311 which supports the rotating shaft 301, while the upper
surface of the second cylinder 307b is closed by the middle plate 309.
In the rotary compressor shown in FIG. 4, a refrigerant is compressed in
the compressing unit 31 by a rotating force of the drive unit 30. After
compression, the compressed refrigerant is discharged to the outside of
the cylinders 307a and 307b. Next, the refrigerant is discharged to the
outside of the compressor through a refrigerant outlet pipe 312, and the
refrigerant then flows into a condenser (not shown). In FIG. 3, reference
numerals 502 and 702 denote first and second locking steps which will be
described in detail below. Reference numeral 313 denotes an oil container
for containing oil therein. Several components of the compressor are
smoothly operated due to the lubricating effect of the oil.
The operation of the rotary compressor constructed as shown in FIG. 3 will
be described in the following with reference to FIGS. 4 through 8.
FIG. 4 shows a compressing action performed in the first cylinder 307a.
When an eccentric direction of the first eccentric part 301a is equal to
an eccentric direction of the first cam bushing 306a during a clockwise
rotation of the rotating shaft 301, the first roller piston 305a performs
a compressing action in the first cylinder 307a. In order to make the
eccentric direction of the first eccentric part 501 coincide with the
eccentric direction of the first cam bushing 306a, a first stop pin 501
and a first locking step 502 are provided. The first stop pin 501 is
provided on the rotating shaft 301 at a position under the first eccentric
part 301a and perpendicular to the rotating shaft 301. The first locking
step 502 is arc-shaped and projects downwardly from the lower surface of
the first cam bushing 306a and stops the first stop pin 501. That is, when
the first stop pin 501 rotating along with the rotating shaft 301 is
rotated, the first locking step 502 stops the first stop pin 501 without
allowing the stop pin 501 to further slidably rotate with respect to the
first cam bushing 306a. According to the present invention, the first stop
pin 501 is stopped at a first end of the first locking step 502 such that
the first eccentric part 301a of the rotating shaft 301 and the first cam
bushing 306a are rotated clockwise together. When the eccentric direction
of the first eccentric part 301a is equal to the eccentric direction of
the first cam bushing 306a during a clockwise rotation of the rotating
shaft 301, a low-pressure refrigerant gas flows into an intake part 503a
of the compression chamber 308a through an intake hole 504 from an
accumulator 314. Meanwhile, in a discharging part 503b of the compression
chamber 308a, a highly-pressurized refrigerant gas is discharged to the
outside of the first cylinder 307a through an outlet hole 505.
An initial state of the first cylinder 307a when the rotating direction of
the first eccentric part 301a is changed is shown in FIG. 5. In this case,
the first eccentric part 301a is slidably rotated with respect to the
first cam bushing 306a while the first cam bushing 306a and the first
roller piston 305a are stopped. At this time, the first stop pin 501
rotates along with the rotating shaft 301 from the first end to the second
end of the first locking step 502, as shown in FIG. 5. When the first
eccentric part 301a is rotated counterclockwise by a predetermined angular
distance as shown in FIG. 6, the first stop pin 501 is stopped at the
second end of the locking step 502, so the eccentric direction of the
first eccentric part 301a is opposite to the eccentric direction of the
first cam bushing 306a. With the eccentric directions opposite, the center
of gravity of the first roller piston 305a coincides with the center of
rotation of the rotating shaft 301. Assuming that there is no frictional
force between an inner surface of the roller piston 305a and an outer
surface of the first cam bushing 306a, and the eccentricity of the first
eccentric part 301a is equal to the eccentricity of the first cam bushing
306a, and the eccentric direction of the first eccentric part 301a is
directly opposite to the eccentric direction of the first cam bushing
306a, the first roller piston 305a stops rotating in the first cylinder
307a. Of course, if such friction exists, the first roller piston 305a
will rotate in a counterclockwise direction. In either the case where the
first roller piston 305a is stopped or the case where the first roller
piston is rotated counterclockwise by friction created between the first
roller piston 305a and the first cam bushing 306a, the intake part 503a is
integrated with the discharging part 503b into a single part, so the first
roller piston 305a performs an idle action. Thus, the refrigerant is not
compressed in the first cylinder 307a.
Meanwhile, FIGS. 7 and 8 show a compressing action and an idle action
performed in the second cylinder 307b by the second roller piston 305b,
which is different from the compressing action and the idle action
performed in the first cylinder 307a by the roller piston 305a as the
rotating shaft 301 is rotated. That is, FIG. 7 shows a compressing action
performed in the second cylinder 307b when the rotating shaft 301 is
rotated counterclockwise, and FIG. 8 shows an idle action performed in the
second cylinder 307b when the rotating shaft 301 is rotated clockwise. As
shown in FIG. 7, an arc-shaped second locking step 702 is upwardly
projected from an upper surface of the second cam bushing 306b. A second
stop pin 701 is provided on the rotating shaft 301 at a position above the
second eccentric part 301b and perpendicular to the rotating shaft 301, so
the second stop pin 701 is slidably moved relative to the second cam
bushing 306b when the rotating direction of the rotating shaft 301 is
changed. The second stop pin 701 is stopped at a first or second end of
the second locking step 702. Thus, the second stop pin 701, in cooperation
with the second locking step 702, serves to control the eccentric
directions of the second eccentric part 301b and the second cam bushing
306b according to the direction of rotation of the rotating shaft 301.
As described above with reference to FIGS. 4 through 8, when the rotating
shaft 301 is rotated clockwise, a compressing action is performed in the
first cylinder 307a arranged at an upper position while an idle action is
performed in the second cylinder 307b arranged at a lower position. When
the rotating shaft 301 is rotated counterclockwise, an idle action is
performed in the first cylinder 307a while a compressing action is
performed in the second cylinder 307b. The first and second stop pins 501
and 701 and the first and second locking steps 502 and 702 serve as an
eccentric control unit which controls the eccentric directions of the
first and second eccentric parts 301a and 301b and the first and second
cam bushings 306a and 306b so that the first and second roller pistons
305a and 305b are eccentrically rotated or idly rotated according to a
rotation direction of the shaft 301. The eccentric control unit and the
first and second cam bushings 306a and 306b serve as a clutch which
engages the first and second roller pistons 305a and 305b such that the
pistons 305a and 305b perform a compressing action or an idle action.
Further, the rotary compressor according to the present invention may be
designed such that a ratio of a compression capacity obtained in the first
cylinder 307a when the rotating shaft 301 is rotated clockwise to a
compression capacity obtained in the second cylinder 307b when the
rotating shaft 301 is rotated counterclockwise becomes 10:4. As a result,
the compression capacity of the compressor is varied according to a
rotating direction of the rotating shaft 301 which may be rotated in
opposite directions by the reversible motor. Of course, according to the
present invention, the compression capacity ratio of the first cylinder
307a to the second cylinder 307b may be differently arranged and the
compression capacity is not limited to a ratio of 10:4. Furthermore, the
compressor of the present invention may be designed such that the
compression capacity of the first cylinder 307a is smaller than the
compression capacity of the second cylinder 307b.
FIGS. 9 through 12 show rotating shafts 301 according to different
embodiments of the present invention. Each of the rotating shafts 301 is
provided with the first and second eccentric parts 301a and 301b. When the
reversible motor is rotated, the rotating shaft 301 transmits a rotating
force of the motor to the first and second roller pistons 305a and 305b
which are provided in the first and second cylinders 307a and 307b,
respectively.
In the rotating shaft 301 of FIG. 9, the first eccentric part 301a to be
received in the first cylinder 307a is positioned above the second
eccentric part 301b to be received in the second cylinder 307b in such a
way that the eccentric direction of the first eccentric part 301a is
opposite to the eccentric direction of the second eccentric part 301b, in
the same manner as a rotating shaft used in a conventional rotary
compressor. Two internally-threaded pin holes 901 are formed at
predetermined positions between the first eccentric part 301a and the
second eccentric part 301b. The stop pins 501 and 701 are formed as
externally-threaded stop pins 501 and screwed into a respective one of the
two pin holes 901. Further, a support step 902 is provided on the rotating
shaft 301 at a predetermined position under the second eccentric part
301b, and supports the second cam bushing 306b. Such a support step 902
supports the second cam bushing 306b so as to prevent the second cam
bushing 306b from being downwardly removed from the rotating shaft 301,
and contacts the lower flange 311 which supports the rotating shaft 301
and hermetically covers the lower surface of the second cylinder 307b.
In a rotating shaft 301 shown in FIG. 10, the first and second eccentric
parts 301a and 301b are arranged with equal eccentric directions. The
arrangement of FIG. 10 allows the construction of a weight balancer to be
simple, like a weight balancer provided in a rotary compressor having a
single eccentric part and a single cylinder. As described above, the
weight balancer reduces the vibration and noise of the compressor caused
by the first and second eccentric parts 301a and 301b when the rotating
shaft 301 is rotated. Thus, in order to construct the weight balancer
simply, the eccentric direction of the first eccentric part 301a may be
equal to the eccentric direction of the second eccentric part 301b within
.+-.30.degree.. But, according to the present invention, the eccentric
direction of the first eccentric part 301a is not necessarily equal to the
eccentric direction of the second eccentric part 301b. Nor, is the
eccentric direction of the first eccentric part 301a necessarily opposite
to the eccentric direction of the second eccentric part 301b. That is,
when the rotary compressor of the present invention is provided with an
optimum weight balancer determined on the basis of an inertia moment and a
centrifugal force of the rotating shaft 301, the eccentric directions of
the first and second eccentric parts 301a and 301b are not important. As
such, although the eccentric directions of the first and second eccentric
parts 301a and 301b are not important, the eccentric control unit which
determines the eccentric directions of the first and second eccentric
parts 301a and 301b and the first and second cam bushings 306a and 306b
must be carefully designed.
FIGS. 11 and 12 show rotating shafts 301 each having a single pin hole 901
between the first and second eccentric parts 301a and 301b. The
construction and operation of the rotating shafts 301 of FIGS. 9 through
12 with the first and second cam bushings 306a and 306b will be further
described below.
FIGS. 13A and 13B show first and second cam bushings 306a and 306b
according to an embodiment of the present invention, with the first and
second cam bushings 306a and 306b clutching the roller pistons 305a and
305b such that the roller pistons 305a and 305b perform a compressing
action or an idle action according to a direction of rotation of the
roller pistons 305a and 305b.
FIG. 13A shows the first cam bushing 306a which is provided between the
first eccentric part 301a and the first roller piston 305a in the first
cylinder 307a. FIG. 13B shows the second cam bushing 306b which is
provided between the second eccentric part 301b and the second roller
piston 305b in the second cylinder 307b. In order to easily assemble the
compressor, the inner diameter of the first cam bushing 306a must be equal
to or larger than the outer diameter of the first eccentric part 301a of
the rotating shaft 301, while the inner diameter of the second cam bushing
306b must be equal to or larger than the outer diameter of the second
eccentric part 301b of the rotating shaft 301. The arc-shaped first
locking step 502 is provided on the lower surface of the first cam bushing
306a and the arc-shaped second locking step 702 is provided on the upper
surface of the second cam bushing 306b. The first and second cam bushings
306a and 306b of FIGS. 13A and 13B may be applied to the rotating shafts
301 shown in FIGS. 9 and 10.
FIG. 14 shows the first and second cam bushings 306a and 306b of FIGS. 13A
and 13B assembled with the rotating shaft 301 of FIG. 9. Of course, the
first and second cam bushings 306a and 306b of FIGS. 13A and 13B may be
applied to the rotating shaft 301 of FIG. 10 by changing the positions of
the pin holes 901 and the first and second locking steps 502 and 702.
FIGS. 15A and 15B show first and second cam bushings 306a and 306b
according to another embodiment of the present invention. In this case,
the first cam bushing 306a is provided on a lower surface with an
arc-shaped downward toothed part 150, and the second cam bushing 306b is
provided on its upper surface with an arc-shaped upward toothed part 151.
Such first and second cam bushings 306a and 306b may be applied to the
rotating shafts 301 shown in FIGS. 11 and 12.
FIG. 16 shows the first and second cam bushings 306a and 306b of FIGS. 15A
and 15B assembled with the rotating shaft 301 of FIG. 12. As shown in FIG.
16, when the first and second cam bushings 306a and 306b are assembled
with the rotating shaft 301, the downward toothed part 150 of the first
cam bushing 306a engages with the upward toothed part 151 of the second
cam bushing 306b. The first and second cam bushings 306a and 306b are
integrally rotated in opposite directions, through the engagement of the
downward toothed part 150 with the upward toothed part 151. In this case,
the stop pin 501 inserted into the pin hole 901 is stopped at either end
of the toothed parts 150 and 151 which engage with each other, thus
determining the eccentric directions of the first and second eccentric
parts 301a and 301b and the eccentric directions of the first and second
cam bushings 306a and 306b according to a rotating direction of the
rotating shaft 301. As described above, the first and second cam bushings
306a and 306b of FIGS. 15A and 15B may be applied to the rotating shaft
301 of FIG. 11 by changing the positions of the pin hole 901 and the
downward and upward toothed parts 150 and 151.
FIG. 17 shows first and second cam bushings 306a and 306b according to a
further embodiment of the present invention. In this case, the first and
second cam bushings 306a and 306b are connected to each other by three
rods 171 such that the first and second cam bushings 306a and 306b are
integrally rotated. In order to connect the first and second cam bushings
306a and 306b to each other using a rod assembly having the three rods
171, three rod holes 170 are formed on the lower surface of the first cam
bushing 306a, and three rod holes 170 are formed on the upper surface of
the second cam bushing 306b. The first and second cam bushings 306a and
306b of FIG. 17 may be applied to the rotating shafts 301 shown in FIGS.
11 and 12. Since the method of assembling the first and second cam
bushings 306a and 306b of FIG. 17 with the rotating shaft 301 is very
similar to that of assembling the first and second cam bushings 306a and
306b shown in FIGS. 15A ad 15B with the rotating shaft 301, the method of
assembling the first and second cam bushings 306a and 306b shown in FIG.
17 with the rotating shaft 301 will not be described in detail herein. In
this case, the stop pin 501 is stopped at either side rod 171.
FIG. 18 shows first and second cam bushings 306a and 306b according to
still another embodiment of the present invention. In this case, the first
and second cam bushings 306a and 306b are connected to each other by a
cylindrical connecting part 180. A stop channel 181 is circumferentially
formed along a part of the sidewall of the cylindrical connecting part
180. The first and second cam bushings 306a and 306b may be applied to the
rotating shaft 301 shown in FIG. 12. A stop pin 501 which is screwed into
the pin hole 901 of the rotating shaft 301 shown in FIG. 12 is stopped at
either end of the stop channel 181. FIG. 19 shows the first and second cam
bushings 306a and 306b of FIGS. 18 assembled with the rotating shaft 301
of FIG. 12. Since the eccentric directions of the first and second
eccentric parts 301a and 301b provided on the rotating shaft 301 shown in
FIG. 12 are equal to each other, the first and second cam bushings 306a
and 306b shown in FIG. 18 are arranged in such a way that their eccentric
directions are opposite to each other. In the case of the first and second
cam bushings 306a and 306b which engage with each other by the toothed
parts 150 and 151 of FIGS. 15A and 15B or are connected to each other by
the rods 171 of FIG. 17 so as to be integrally rotated, the first and
second cam bushings 306a and 306b are preferably arranged in such a way
that their eccentric directions are opposite to each other within
.+-.30.degree. when assembling the compressor, so as to reduce the number
of the weight balancers.
When assembling the first and second cam bushings 306a and 306b shown in
FIGS. 15A, 15B, 17, and 18 with the rotating shafts 301 shown in FIGS. 9
through 12, the first and second bushings 306a and 306b must be axially
fitted over each of the rotating shafts 301 in a direction from the top to
the bottom of the rotating shaft 301, because the support step 902 is
provided on the lower portion of the rotating shaft 301. In this case, the
inner diameters of the first and second cam bushings 306a and 306b shown
in FIGS. 15A, 15B, 17 and 18 must be equal to or larger than the outer
diameter of each of the rotating shafts 301 shown in FIGS. 9 through 12,
because the first and second eccentric parts 301a and 301b are inserted
into the openings of the first and second cam bushings 306a and 306b in
the first and second cylinders 307a and 307b, respectively. Of course,
when the outer diameter of the first or second eccentric parts 301a or
301b is larger the diameter of the rotating shaft 301, the inner diameter
of each of the first and second cam bushings 306a and 306b must be equal
to or larger than the outer diameter of an associated one of the first and
second eccentric parts 301a or 301b. In this case, the first cam bushing
306a is assembled with the rotating shaft 301 after assembling the second
cam bushing 306b with the rotating shaft 301. Thus, in order to allow the
first and second cam bushings 306a and 306b to be assembled with the
rotating shaft 301, the outer diameter of the first cam bushing 306a must
be smaller than or equal to the outer diameter of the second eccentric
part 301b and the inner diameter of the first cam bushing 306a must be
smaller than or equal to the inner diameter of the second cam bushing
306b. However, such an assembling method is problematic in that the first
and second cam bushings 306a and 306b must be axially fitted over the
rotating shaft 301. Thus, in order to allow the first and second cam
bushings 306a and 306b to be more easily fitted over the rotating shaft
301, the first and second cam bushings 306a and 306b each may be axially
divided into two pieces as shown in FIGS. 20 and 21.
FIG. 22 shows each of the first and second cam bushings 306a and 306b
seated in an associated one of the first and second cylinders 307a and
307b. As such, the first and second cam bushings 306a and 306b each are
axially divided into pieces, so the first and second cam bushings 306a and
306b do not need to be axially fitted over the rotating shaft 301.
Oil is supplied from the oil container 313, which is provided on the lower
portion of the compressor, to components between which friction is
created. Oil is smoothly supplied to the components as they are operated.
As described above with reference to FIG. 4, when the first or second
roller piston 305a or 305b performs an idle action, the first or second
roller piston 305a or 305b is only slightly rotated due to a frictional
force generated between each of the first and second roller pistons 305a
or 305b and the outer surface of an associated one of the first and second
cam bushings 306a or 306b. Due to a slight rotation of the roller piston
305a or 305b, oil may not be smoothly supplied between each of the first
and second eccentric parts 301a and 301b and an associated one of the
first and second cam bushings 306a and 306b, and between each of the first
and second cam bushings 306a and 306b and an associated one of the first
and second roller pistons 305a and 305b. Thus, in order to smoothly supply
oil to the components of the compressor even when performing an idle
action, the first and second roller pistons 305a and 305b must be slightly
and eccentrically rotated even when performing such an idle action. As
such, in order to allow the first and second roller pistons 305a and 305b
to be eccentrically rotated even when performing an idle action, the
positions of the first and second locking steps 502 and 702, the stop
channel 181, the toothed parts 150 and 151, the rod assembly and the stop
p
