U.S. patent number RE34,148 [Application Number 07/522,058] was granted by the patent office on 1992-12-22 for scroll type compressor with variable displacement mechanism.
This patent grant is currently assigned to Sanden Corporation. Invention is credited to Atsushi Mabe, Kiyoshi Terauchi.
United States Patent |
RE34,148 |
Terauchi , et al. |
December 22, 1992 |
Scroll type compressor with variable displacement mechanism
Abstract
A variable displacement type compressor is disclosed. The
compressor includes a housing having fluid inlet and fluid outlet
ports. A fixed scroll is fixed within the housing and has a
circular end plate from which a first spiral element extends. The
end plate of the fixed scroll partitions the inner chamber of the
compressor housing into a front chamber connected to the fluid
inlet port and a rear chamber. The rear chamber is divided into a
discharge chamber connected to the fluid outlet port and an
intermediate pressure chamber. The end plate of the fixed scroll
has at least two holes which connect the fluid pockets to the
intermediate pressure chamber. The end plate also has a
communicating channel which connects the front chamber to the
intermediate chamber. A control device controls the communication
between the front chamber and intermediate pressure chamber. The
control device is disposed on the intermediate pressure chamber,
and a valve element of the control means is operated by pressure
from the discharge chamber.
Inventors: |
Terauchi; Kiyoshi (Gunma,
JP), Mabe; Atsushi (Gunma, JP) |
Assignee: |
Sanden Corporation (Gunma,
JP)
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Family
ID: |
15082520 |
Appl.
No.: |
07/522,058 |
Filed: |
May 10, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
875561 |
Jun 18, 1986 |
04744733 |
May 17, 1988 |
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Foreign Application Priority Data
|
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Jun 18, 1985 [JP] |
|
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60-132487 |
|
Current U.S.
Class: |
417/310; 417/440;
418/55.1 |
Current CPC
Class: |
F04C
28/16 (20130101) |
Current International
Class: |
B60H
3/00 (20060101); F04C 18/02 (20060101); F04C
18/06 (20060101); F04C 18/04 (20060101); F04B
49/02 (20060101); F04B 49/08 (20060101); F04D
1/00 (20060101); F04B 049/02 (); F04B 049/08 () |
Field of
Search: |
;418/55.1
;417/295,310,440 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Smith; Leonard E.
Attorney, Agent or Firm: Banner, Birch McKie &
Beckett
Claims
We claim:
1. In a scroll type compressor including a housing having an inlet
port and an outlet port, a fixed scroll fixedly disposed within
said housing and having a circular end plate from which a first
spiral element extends into the interior of said housing, an
orbiting scroll having a circular end plate from which a second
spiral element extends, said first and second spiral elements
interfitting at an angular and radial offset to make a plurality of
line contacts and define at least one pair of fluid pockets within
the interior of said housing, a driving mechanism operatively
connected to said orbiting scroll to effect the orbital motion of
said orbiting scroll, a rotation preventing mechanism for
preventing the rotation of said orbiting scroll during the orbital
motion, said circular end plate of said fixed scroll dividing the
interior of said housing into a front chamber and a rear chamber,
said front chamber communicating with said inlet port, and said
rear chamber being divided into a discharge chamber which
communicates between said outlet port and a central fluid pocket
formed by both said scrolls and an intermediate pressure chamber,
the improvement comprising:
at least one pair of holes formed through said circular end plate
of said fixed scroll forming a fluid channel between the fluid
pockets and said intermediate pressure chamber, a communication
channel formed through said circular end plate of said fixed scroll
to form a fluid channel between said intermediate pressure chamber
and said front chamber, control means disposed on a portion of said
intermediate pressure chamber for controlling fluid communication
between said intermediate pressure chamber and said front chamber,
said control means comprising a .[.valve element operated by the
compressed fluid in said discharge chamber, and a.]. cylinder
.Iadd.connected with said intermediate pressure chamber, said front
chamber and said discharge chamber.Iaddend., a piston slidably
disposed within said cylinder .Iadd.and operated by the compressed
fluid from said discharge chamber.Iaddend., and a control valve
element.[., a top portion of said cylinder being connected to said
discharge chamber, said control valve element.]. controlling the
communication between said discharge chamber and said front
chamber.
2. A scroll type compressor according to claim 1 wherein said
.Iadd.control .Iaddend.valve element is disposed in said piston.
.Iadd.3. A scroll type compressor according to claim 1 wherein said
control valve element comprises a bellows and a valve operated by
said bellows, said piston including a first opening facing a
portion of said cylinder in communication with said discharge
chamber and a second opening facing a portion of said cylinder in
communication with said front chamber, said bellows being located
within said piston and being responsive to the pressure in said
front chamber to operate said valve to open and close said first
opening to thereby control communication between said discharge
chamber and said front chamber. .Iaddend. .Iadd.4. A scroll type
compressor according to claim 3 wherein a lower portion of said
cylinder communicates with said intermediate pressure chamber and
said front chamber, communication between said intermediate
pressure chamber and said front chamber being controlled by the
sliding operation of said piston, a top portion of said cylinder
being connected with said discharge chamber.
.Iaddend. .Iadd.5. A scroll type compressor according to claim 4
wherein the top portion of said cylinder and said discharge chamber
are connected through a fluid channel including a constricted
conduit disposed in a
portion thereof. .Iaddend. .Iadd.6. A scroll type compressor
according to claim 1 wherein a lower portion of said cylinder
communicates with said intermediate pressure chamber and said front
chamber, communication between said intermediate pressure chamber
and said front chamber being controlled by the sliding operation of
said piston, a top portion of said cylinder being connected with
said discharge chamber. .Iaddend. .Iadd.7. A scroll type compressor
according to claim 6 wherein said control valve element controls
the sliding operation of said piston in response to the pressure in
said front chamber to thereby control communication between said
intermediate pressure chamber and said front chamber to vary
the
compression ratio of said compressor. .Iaddend. .Iadd.8. A scroll
type compressor according to claim 7 wherein, in the event the
pressure in said front chamber is less than a predetermined
pressure, said control valve element opens communication between
said discharge chamber and said front chamber and said piston
slides upward in said cylinder to open communication between said
intermediate pressure chamber and said front chamber to thereby
decrease the compression ratio. .Iaddend. .Iadd.9. A scroll type
compressor according to claim 8 wherein, in the event the pressure
in said front chamber is greater than the predetermined pressure,
said control valve element closes off communication between said
discharge chamber and said front chamber and said piston slides
downward in response to the pressure from said discharge chamber to
close off communication between said intermediate pressure chamber
and said front chamber to
thereby increase the compression ratio. .Iaddend. .Iadd.10. In a
scroll type compressor including a housing having an inlet port and
an outlet port, a fixed scroll fixedly disposed within said housing
and having a circular end plate from which a first spiral element
extends into the interior of said housing, an orbiting scroll
having a circular end plate from which a second spiral element
extends, said first and second spiral elements interfitting at an
angular and radial offset to make a plurality of line contacts and
define at least one pair of fluid pockets within the interior of
said housing, a driving mechanism operatively connected to said
orbiting scroll to effect the orbital motion of said orbiting
scroll, a rotation preventing mechanism for preventing the rotation
of said orbiting scroll during the orbital motion, said circular
end plate of said fixed scroll dividing the interior of said
housing into a front chamber and a rear chamber, said front chamber
communicating with said inlet port, and said rear chamber being
divided into a discharge chamber which communicates between said
outlet port and a central fluid pocket formed by both said scrolls
and an intermediate pressure chamber, the improvement
comprising:
at least one pair of holes formed through said circular end plate
of said fixed scroll forming a fluid channel between the fluid
pockets and said intermediate pressure chamber, a communication
chamber formed by a further division of said rear chamber, a
communicating channel formed through said circular end plate of
said fixed scroll forming a fluid channel between said front
chamber and said communication chamber, a first opening formed
through a wall of said communication chamber forming a fluid
channel between said communication chamber and said intermediate
pressure chamber and thereby forming a continuous fluid channel
between said front chamber and said intermediate pressure chamber,
control means disposed on a portion of said intermediate pressure
chamber for controlling fluid communication between said
intermediate pressure chamber and said front chamber, said control
means comprising a cylinder including a top portion connected to
said discharge chamber by a conduit for communicating fluid
therebetween, a side portion connected to said wall of said
communication chamber with said first opening formed therethrough
for communicating fluid therebetween, and a bottom portion
connected with said intermediate pressure chamber, a piston
slidably disposed within said cylinder and operated by the
compressed fluid from said discharge chamber, and a control valve
element controlling the communication between said discharge
chamber and said front chamber and operated by the compressed fluid
from said communication chamber. .Iaddend. .Iadd.11. A scroll type
compressor according to claim 10 wherein said control valve element
is disposed in
said piston. .Iaddend. .Iadd.12. In a scroll type compressor
including a housing having an inlet port and an outlet port, a
fixed scroll fixedly disposed within said housing and having a
circular end plate from which a first spiral element extends into
the interior of said housing, an orbiting scroll having a circular
end plate from which a second spiral element extends, said first
and second spiral elements interfitting at an angular and radial
offset to make a plurality of line contacts and define at least one
pair of fluid pockets within the interior of said housing, a
driving mechanism operatively connected to said orbiting scroll to
effect the orbital motion of said orbiting scroll, a rotation
preventing mechanism for preventing the rotation of said orbiting
scroll during the orbital motion, said circular end plate of said
fixed scroll dividing the interior of said housing into a front
chamber and a rear chamber, said front chamber communicating with
said inlet port, and said rear chamber being divided into a
discharge chamber which communicates between said outlet port and a
central fluid pocket formed by both said scrolls and an
intermediate pressure chamber, the improvement comprising:
at least one pair of holes formed through said circular end plate
of said fixed scroll forming a fluid channel between the fluid
pockets and said intermediate pressure chamber, a communication
chamber formed by a further division of said rear chamber, a
communicating channel formed through said circular end plate of
said fixed scroll forming a fluid channel between said front
chamber and said communication chamber, first control means
disposed on a portion of said intermediate pressure chamber for
controlling fluid communication between said communication chamber
and said intermediate pressure chamber, conduit means connected
between said first control means and said discharge chamber for
communicating fluid therebetween, said first control means operated
by the compressed fluid from said discharge chamber, second control
means associated with said first control means for controlling
fluid communication between said discharge chamber and said
communication chamber, said second control means operated by
changes of the fluid pressure in said communication chamber.
.Iaddend. .Iadd.13. A scroll type compressor according to claim 12
wherein said first control means comprises a cylinder connected
with said intermediate pressure chamber, said communication chamber
and said conduit means, and a piston slidably disposed within said
cylinder.
.Iaddend. .Iadd.14. A scroll type compressor according to claim 12
wherein said conduit means comprises a fluid channel including
a
constricted conduit disposed in a portion thereof. .Iaddend.
.Iadd.15. A scroll type compressor according to claim 13 wherein
said second control means comprises a control valve element
disposed in said piston. .Iaddend. .Iadd.16. A scroll type
compressor according to claim 15 wherein said control valve element
comprises a bellows and a valve operated by said bellows, said
piston including a first opening facing a portion of said cylinder
in communication with said conduit means and a second opening
facing a portion of said cylinder in communication with said
communication chamber, said bellows being responsive to the
pressure in said communication chamber to operate said valve to
open and close said first opening and thereby control communication
between said discharge chamber and said front chamber. .Iaddend.
.Iadd.17. A scroll type compressor according to claim 16 wherein a
lower portion of said cylinder communicates with said intermediate
pressure chamber and said communication chamber, communication
between said intermediate pressure chamber and said communication
chamber being controlled by the sliding operation of said piston, a
top portion of said cylinder being connected with said conduit
means. .Iaddend. .Iadd.18. A scroll type compressor according to
claim 17 wherein said control valve element controls the sliding
operation of said piston in response to the pressure in said
communication chamber to thereby control communication between said
intermediate pressure chamber and said communication chamber to
vary the compression ratio of said compressor. .Iaddend. .Iadd.19.
A scroll type compressor according to claim 18 wherein, in the
event the pressure in said communication chamber is less than a
predetermined pressure, said control valve element opens
communication between said communication chamber and said discharge
chamber through said conduit means and said piston slides upward in
said cylinder to open communication between said intermediate
pressure chamber and said communication chamber to thereby decrease
the compression ratio. .Iaddend. .Iadd.20. A scroll type compressor
according to claim 19 wherein, in the event the pressure in said
communication chamber is greater than the predetermined pressure,
said control valve element closes off communication between said
conduit means and said communication chamber and said piston slides
downward in response to the pressure from said conduit means to
close off communication between said intermediate pressure chamber
and said communication chamber to thereby increase the compression
ratio. .Iaddend.
Description
TECHNICAL FIELD
The present invention relates to a scroll type compressor. More
particularly, the present invention relates to a scroll type
compressor with a variable displacement mechanism.
BACKGROUND OF THE INVENTION
When the air conditioning load in the compartment of a car is
decreased by an air conditioning system, or the temperature in the
compartment of the car is below the predetermined temperature, the
displacement of the compressor, and therefore the compression ratio
of the compressor, can be decreased.
A scroll type compressor which can vary the compression ratio is
well known in the art. For example, U.S. Pat. No. 4,505,651 and
U.S. Pat. No. 4,642,034 show such compressors.
However, in U.S. Pat. No. 4,505,651, the compression ratio change
is not sufficient. Also, in the mechanism shown in U.S. Pat. No.
4,642,034, the temperature of the discharge fluid increases
abnormally when the compressor operates at high speeds.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a scroll
type compressor with a variable displacement mechanism which can
continuously vary compressor displacement as the load changes or as
the rotational speed of the compressor varies.
It is another object of the present invention to provide a scroll
type compressor with a variable displacement mechanism which can
vary the compression volume over a large range.
It is still another object of the present invention to provide a
scroll type compressor with a variable displacement mechanism which
eliminates suction pressure loss and which does not increase the
temperature of the discharged fluid.
A scroll type compressor according to the present invention
includes a housing having a inlet port and an outlet port. A fixed
scroll is fixedly disposed with the housing and has a circular end
plate from which a first spiral element extends. An orbiting scroll
having a circular end plate from which a second spiral element
extends is placed on a drive shaft. The two spiral elements
interfit at an angular and radial offset to form a plurality of
line contacts and to define at least one pair of fluid pockets
within the interior of the housing. A driving mechanism is
operatively connected to the orbiting scroll to effect orbital
motion of the orbiting scroll and to change the volume of the fluid
pockets during orbital motion. A rotation preventing mechanism
prevents rotation of the orbiting scroll. The circular end plate of
the fixed scroll divides the interior of the housing into a front
chamber and a rear chamber. The front chamber communicates with a
fluid inlet port. The rear chamber is divided into a discharge
chamber which communicates with a fluid outlet port and a central
fluid pocket formed by both scrolls, and an intermediate pressure
chamber. At least one pair of holes is formed through the circular
end plate of the fixed scroll to form a fluid channel between the
fluid pockets and the intermediate pressure chamber. A
communicating channel formed through the circular end plate of the
fixed scroll provides a fluid channel between the intermediate
pressure chamber and the front chamber. Control means disposed on a
portion of the intermediate pressure chamber controls opening and
closing of the communicating channel. A valve element of the
control device is controlled by the compressed fluid in the
discharge chamber.
Various additional advantages and features of novelty which
characterize the invention are further pointed out in the claims
that follow. However, for a better understanding of the invention
and its advantages, reference should be made to the accompanying
drawings and descriptive matter which illustrate and describe
preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical cross-sectional view of a scroll type
compressor according to one embodiment of this invention.
FIG. 2 is a sectional view of the compressor of FIG. 1 illustrating
the position of the holes in the end plate.
FIG. 3 is a cross-sectional view of an alternate embodiment of the
variable displacement mechanism used in the scroll type compressor
of FIG. 1.
FIG. 4 is a cross-sectional view of another alternate embodiment of
the variable displacement mechanism used in the scroll type
compressor of FIG. 1.
FIG. 5 is a cross-sectional view of another alternate embodiment of
the variable displacement mechanism used in the scroll type
compressor of FIG. 1.
FIG. 6 is a cross-sectional view of another alternate embodiment of
the variable displacement mechanism used in the scroll type
compressor of FIG. 1.
FIG. 7 is a cross-sectional view of another alternate embodiment of
the variable displacement mechanism used in the scroll type
compressor of FIG. 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIG. 1, a scroll type compressor according to one
embodiment of this invention is shown. The scroll type compressor
includes a compressor housing 10 having front end plate 11 and
cup-shaped casing 12 which is attached to an end surface of end
plate 11. Opening 111 is formed in the center of front end plate 11
and drive shaft 13 is disposed in opening 111. Annular projection
112 is formed in a rear surface of front end plate 11. Annular
projection 112 faces cup-shaped casing 12 and is concentric with
opening 111. An outer peripheral surface of projection 112 extends
into an inner wall of the opening of cup-shaped shaped casing 12.
Opening 121 of cup-shaped casing 12 is covered by front end plate
11. O-ring 14 is placed between the outer peripheral surface of
annular projection 112 and the inner wall of the opening of cup
shaped casing 12 to seal the mating surfaces of front end plate 11
and cup-shaped casing 12.
Annular sleeve 16 projects from the front end surface of front end
plate 11, surrounds drive shaft 13, and defines a shaft seal
cavity. In the embodiment shown in FIG. 1, sleeve 16 is formed
separately from front end plate 11. Sleeve 16 is fixed to the front
end surface of front end plate 11 by screws (not shown).
Alternatively, sleeve 16 may be formed integrally with front end
plate 11.
Drive shaft 13 is rotatably supported by sleeve 16 through bearing
17 located within the front end of sleeve 16. Drive shaft 13 has
disk-shaped rotor 131 at its inner end which is rotatably supported
by front end plate 11 through bearing 15 located within opening 111
of front end plate 11. Shaft seal assembly 18 is coupled to drive
shaft 13 within the shaft seal cavity of sleeve 16.
Pulley 201 is rotatably supported by ball bearing 19 which is
carried on the outer surface of sleeve 16. Electromagnetic coil 202
is fixed about the outer surface of sleeve 16 by a support plate.
Armature plate 203 is elastically supported on the outer end of
drive shaft 13. Pulley 201, magnetic coil 202, and armature plate
203 form magnetic clutch 20. In operation, drive shaft 13 is driven
by an external power source, for example, the engine of an
automobile, through a rotation transmitting device such as magnetic
clutch 20.
Fixed scroll 21, orbiting scroll 22, a driving mechanism for
orbiting scroll 22, and rotation preventing/thrust bearing
mechanism 24 for orbiting scroll 22 are disposed in the interior of
housing 10.
Fixed scroll 21 includes circular end plate 211 and spiral element
212 affixed to or extending from one end surface of circular end
plate 211. Fixed scroll 21 is fixed within the inner chamber of
cup-shaped casing 12 by screws 25 screwed into end plate 211 from
the outside of cup-shaped casing 12. Circular end plate 211 of
fixed scroll 21 partitions the inner chamber of cup-shaped casing
12 into two chambers, front chamber 27 and rear chamber 28. Spiral
element 212 is located within front chamber 27.
Partition wall 122 axially projects from the inner end surface of
cup-shaped casing 12. The end surface of partition wall 122
contacts the end surface of circular end plate 211. Thus, partition
wall 122 divides rear chamber 28 into discharge chamber 281 formed
at the center portion of rear chamber 21 and intermediate chamber
282. Gasket 26 may be disposed between the end surface of partition
wall 122 and end plate 211 to secure the sealing.
Orbiting scroll 2, which is located in front chamber 27, includes
circular end plate 221 and spiral element 222 extending from one
end surface of circular end plate 221. Spiral element 222 of
orbiting scroll 22 and spiral element 212 of fixed scroll 21
interfitting at an angular offset of 180.degree. and a
predetermined radial offset, form sealed spaces between spiral
elements 212 and 222. Orbiting scroll 22 is rotatably supported by
bushing 23, which is eccentrically connected to the inner end of
disc-shaped portion 131 through radial needle bearing 20.
While orbiting scroll 22 orbits, rotation is prevented by rotation
preventing/thrust bearing mechanism 24 which is placed between the
inner end surface of front end plate 11 and circular end plate 221
of orbiting scroll 22. Rotation preventing/thrust bearing mechanism
24 includes fixed ring 241, fixed race 242, orbiting ring 243,
orbiting race 244, and balls 245. Fixed ring 241 is attached to the
inner end surface of front end plate 11 through fixed race 242 and
has a plurality of circulate holes 241a. Orbiting ring 243 is
attached to the rear end of orbiting scroll 22 through orbiting
race 244 and has a plurality of circular holes 243a. Each ball 245
is placed between hole 241a of fixed ring 241 and circular hole
243a of orbiting ring 243, and moves along the edges of both
circular holes 241a and 243a. Also, the axial thrust load from
orbiting scroll 22 is supported on front end plate 11 through balls
245.
Compressor housing 10 is provided with inlet port 31 and outlet
port 32 for connecting the compressor to an external refrigeration
circuit. Refrigeration fluid from the external circuit is
introduced into suction chamber 271 through inlet portion 31 and
flows into sealed spaces formed between spiral elements 212 and 222
through open spaces between the spiral elements. The spaces between
the spiral elements sequentially open and close during the orbital
motion of orbiting scroll 22. When the spaces are open, fluid to be
compressed flows into these spaces but no compression occurs. When
the spaces are closed, no additional fluid flows into the spaces
and compression begins. Since the location of the outer terminal
ends of spiral elements 212 and 222 is at a final involute angle,
location of the spaces is directly related to the final involute
angle. Furthermore, refrigeration fluid in the sealed space is
moved radially inwardly and is compressed by the orbital motion of
orbiting scroll 22. Compressed refrigeration fluid at the center
sealed space is discharged to discharge chamber 281 through
discharge port 213, which is formed at the center of circular end
plate 211.
Referring to FIGS. 1 and 2, a pair of holes 214, 215 are formed in
end plate 211 of fixed scroll 21 and are symetrically placed so
that an axial end surface of spiral element 222 of orbiting scroll
22 simultaneously crosses over both holes 214, 215. Holes 214 and
215 communicate between the sealed space and intermediate pressure
chamber 282. Hole 214 is placed at a position defined by involute
angle .phi..sub.1 (not shown) and opens along the inner side wall
of spiral element 212. The other hole 215 is placed at a position
defined by involute angle (.phi..sub.1 -.pi.) (not shown) and opens
along the outer side wall of spiral element 212. A control device,
such as valve member having valve plates 341, 342 is attached by
fasteners 351, 352 to the end surface of end plate 211 opposite
holes 214, 215, respectively. Each valve plate 341, 342 is made of
a spring type material so that the bias of each valve plate 341,
342 pushes it against the opening of holes 214, 215 to close each
hole.
End plate 211 of fixed scroll 21 also has communicating channel 29
at an outer side portion of the terminal end of spiral element 212.
Communicating channel 29 connects section chamber 271 of front
chamber 27 and intermediate pressure chamber 282 through
communication chamber 283. Control mechanism 36 controls fluid
communication between communication chamber 283 and intermediate
pressure chamber 282. Control mechanism 36 includes cylinder 361,
I-shaped piston 362 slidably disposed within cylinder 361, and coil
spring 363 disposed between the lower end portion of piston 362 and
the bottom portion of cylinder 361 to support piston 362. First
opening 361a is formed on a side surface of cylinder 362 and
creates a fluid path between cylinder 361 and communication chamber
283. Second opening 361b is formed on the bottom portion of
cylinder 361 and creates a fluid path between cylinder 361 and
intermediate pressure chamber 282. The upper portion of cylinder
361 is covered by plate 365 which is provided with aperture 366 at
its center portion and is connected with discharge chamber 281
through capillary tube 368. Fluid communication between cylinder
361 and discharge chamber 281 is controlled by magnetic valve 364
disposed on housing 10. Piston ring 362c is placed on the upper
portion of piston 362 to prevent the leakage of high pressure fluid
between cylinder 361 and piston 362.
The operation of control mechanism 36 is as follows. When orbiting
scroll 22 is operated by the rotation of drive shaft 13,
refrigeration fluid flows into suction chamber 271 through inlet
port 31 and then flows into sealed spaces (fluid pockets) defined
between spiral elements 212 and 222. As the refrigeration fluid in
the sealed spaces moves towards the center of spiral elements 212
and 222 its volume is reduced and it is compressed. The fluid is
then discharged through discharge port 213 to discharge chamber
281.
When electromagnetic valve 364 is de-energized, there is no
communication between discharge chamber 281 and cylinder 361.
Piston 362 is urged upwardly by the recoil strength of spring 363,
and the bottom portion 362b of piston 362 moves upwardly past first
opening 361a. This connects intermediate pressure chamber 282 to
communication chamber 283 through cylinder 361 and opening 361a.
Therefore, intermediate pressure chamber 282 maintains the suction
pressure level, and some refrigeration fluid in the fluid pockets
flows into intermediate pressure chamber 282 through holes 214 and
215 and back into front chamber 27. Therefore, the compression
phase of the compressor starts after the spiral element passes over
holes 214 and 215. This greatly reduces the compression ratio of
the compressor.
On the other hand, when electromagnetic valve 364 is energized,
compressed fluid in discharge chamber 281 flows into cylinder 361
through capillary tube 368. As the recoil strength of spring 363 is
selected to be less than the force of the compressed fluid, piston
362 is pushed downwardly by the compressed fluid. Second hole 361d
which connects cylinder 361 with intermediate pressure chamber 282
is covered by piston 362 and this prevents communication between
communication chamber 283 and intermediate pressure chamber 282.
Therefore, the pressure in intermediate pressure chamber 282
gradually increases due to fluid passage from the fluid pockets
through holes 214 and 215. This passage of compressed fluid
continues until the pressure in intermediate pressure chamber 282
is equal to the pressure in the fluid pockets. When pressure
equalization occurs, holes 214 and 215 are closed by the spring
tension of valve plates 341 and 342. Compression then operates
normally and the displacement volume of the sealed fluid pockets is
the same as the displacement volume when the terminal end of each
spiral element 212, 222 first contacts outer spirals 211, 221.
Referring to FIG. 3, the second embodiment of a control mechanism
is shown. The control mechanism includes cylinder 361, I-shaped
piston 362 slidably disposed within cylinder 361, spring 363
disposed between the lower end surface of piston 362 and the bottom
portion of cylinder 361, and control element 37. Intermediate
pressure chamber 282, cylinder 361, and communicating chamber 283
are connected to one another through first and second openings 361a
and 361b. The upper opening cylinder 361 is covered by the upper
portion of control element 37 which is provided with operating
chamber 371. The interior of operating chamber 371 is connected
with cylinder 361 through first conduit 372 and is also connected
with communicating chamber 283 through second conduit 373. The
mid-portion of conduit 372 is connected to discharge chamber 281
through capillary tube 368 and connecting conduit 374. Bellows 375
is disposed in operating chamber 371 and comprises bellows portion
375a and valve portion 375b attached to the lower end of bellows
portion 375a. Valve portion 375b is slidably disposed in aperture
372 and controls fluid communication between cylinder 361 and
discharge chamber 281. During operation of the compressor, if the
pressure in connecting chamber 283 decreases, the pressure in
operating chamber 371 also decreases. When this occurs, if the
pressure in bellows portion 375a is larger than the pressure in
operating chamber 371, the fluid in bellows portion 375a expands
and forces valve portion 375b downwardly to close the opening of
conduit 372. This prevents communication between discharge chamber
281 and cylinder 361. Piston 362 is pushed upwardly by the bias of
spring 363 and intermediate pressure chamber 282 communicates with
cylinder 361. This reduces the compression ratio of the compressor
in the manner described with respect to the compressor of FIG.
1.
On the other hand, if the pressure in operating chamber 371
increases and the pressure in bellows portion 375a is less than the
pressure in operating chamber 371, the volume of the fluid in
bellows portion 375a decreases. Thus, bellows portion 375a shrinks
and valve portion 375b moves upwardly and opens conduit 372.
Cylinder 361 is connected with discharge chamber 281 through
conduit 372, connecting conduit 374, and capillary tube 368.
Compressed fluid flows form discharge chamber 281 into cylinder 361
through capillarly tube 368. Because the pressure of the compressed
fluid in discharge chamber 281 is selected to be stronger than the
recoil strength of spring 363, piston 362 is pushed downwardly by
the compressed fluid. Accordingly, intermediate pressure chamber
282 is disconnected from communicating chamber 283 and the
compression ratio of the compressor increases. The moving distance
of bellows portion 375a is determined by the fluid pressure in
operating chamber 371. Accordingly, the operating valve portion
375b is set to the pressure in operating chamber 371.
When the air conditioning load is small, or the pressure in
operating chamber 371 is less than the predetermined value as
caused by an increased rotational speed of the compressor, bellows
portion 375a moves downwardly, the moving distance of valve portion
375b is smaller, and the refrigeration fluid volume supplied to
cylinder 361 decreases. Piston 362 is pushed upwardly by the bias
of spring 363 and the area of opening 361a increases. This
decreases pressure loss from the compressed fluid at opening 361a
because the open area 361a of cylinder 361 is increased. Therefore,
the compression ratio decreases, and the pressure in connecting
chamber 283 is gradually increased.
When the fluid pressure in connecting chamber 283 is larger than
the predetermined value, bellows portion 375a of bellows 375
shrinks, and the moving distance of valve portion 375b gradually
increases. The volume of the compressed fluid supplied to cylinder
361 increases. Therefore, piston 362 is pushed downwardly by the
fluid against the bias of spring 363. The open area of opening 361a
of cylinder 361 gradually decreases, and the pressure in connecting
chamber 382 also gradually decreases.
Referring to FIG. 4, a third embodiment of the control mechanism is
shown. Electromagnetic valve 38, which functions as the control
mechanism, is disposed on the upper opening of cylinder 361 and
comprises coil 38a, armature 38b, and spring 38c. Armature 38b is
slidably fitted within the inner surface of coil 38a and pushes
downwardly to close aperture 366. Aperture 366 is connected to
discharge chamber 281 through connecting conduit 374, orifice 381,
and capillary tube 368.
During operation of the compressor, a small amount of compressed
fluid which is discharged from discharge chamber 281 is always
supplied to the upper space of cylinder 361 through aperture 366.
When coil 38a is not energized, the upper end of aperture 366 is
closed by armature 38b. The pressure of the compressed fluid in
cylinder 361 is larger than the recoil strength of spring 363,
therefore, piston 362 moves downwardly to close openings 361a and
361b. Communication between intermediate chamber 282 and connecting
chamber 283 is prevented, and the compression ratio of the
compressor is normal.
When coil 38a is energized, a magnetic flux is produced around coil
38a and armature 38b is pulled up. Compressed fluid flows into
operating chamber 382 through aperture 366. Piston 362 is pushed
upwardly by the recoil strength of spring 363. Accordingly,
communicating chamber 283 is connected with intermediate pressure
chamber 282 through cylinder 361 and the compression volume
decreases.
Referring to FIG. 5, a fourth embodiment of the control mechanism
is shown, Magnetic valve 38 of FIG. 4 is replaced by bellows valve
element 39. Bellows valve element 39 includes bellows portions 391
disposed in first operating chamber 393 and needle portion 392
attached on the bottom surface of bellows portion 391. First
operating chamber 393 is connected to connecting chamber 283
through conduit 397. Needle portion 392 slidably penetrates
aperture 396 and extends into second operating chamber 394.
Aperture 396 connects first and second operating chambers 393 and
394. Second operating chamber 394 is connected to cylinder 361 and
discharge chamber 281 through capillary tube 368. Ball 395 is
disposed on the top of spring 399 which is disposed in second
operating chamber 394 and contacts the end of needle portion 392.
Thus, ball 395 controls the opening and closing of aperture 396 by
the recoil strength of spring 399 and the operation of bellows
portion 391.
During operation of the compressor, a small amount of compressed
fluid which is discharged from discharge chamber 281 is always
supplied to second operating chamber 394 through orifice 381 and
capillary tube 368. When the pressure in first operating chamber
393 is larger than that in bellows portion 391, bellows portion 391
shrinks. Ball 395, moved upwardly by the recoil strength of spring
399, pushes needle portion 392 upwardly and closes the opening of
aperture 398. Piston 362 is pushed downwardly against spring 363 by
the compressed fluid and closes 361b. Connecting chamber 283 is
disconnected from intermediate pressure chamber 282, and the
compression volume is increased. When the pressure in first
operating chamber 393 is decreased and the pressure in bellows
portions 391 is larger than the pressure in first operating chamber
393, bellows portion 391 expands. Needle portion 392 moves
downwardly and pushes ball 395 against spring 399. Compressed fluid
in second operating chamber 394 flows to first operating chamber
393 through aperture 396. Since the pressure in second operating
chamber 394 is decreased, piston 362 moves upwardly by the force of
spring 363. Accordingly, connecting chamber 283 is connected with
intermediate pressure chamber 282 through cylinder 361 and openings
361a and 361b. Therefore, the compression volume is decreased.
Referring to FIG. 6, a fifth embodiment of the control mechanism is
shown. Control mechanism 40 includes cylinder 401, piston valve
402, bellows 403, and spring 404. Piston valve 402 is slidably
disposed within cylinder 401 and has openings 402a and 402b. Piston
402 is pushed upwardly by spring 404 disposed between the bottom
portion of cylinder 401 and the lower end surface of piston 402.
Bellows 403 is disposed in the interior of piston valve 402, and
includes valve portion 403a and bellows portion 403b. Valve portion
403a extends to the outside of piston valve 402 through opening
402a which is formed on the upper portion of piston valve 402.
Cylinder 401 is connected to discharge chamber 281 through conduits
405, 406, and capillary tube 368.
Since the interior of piston valve 402 is connected to connecting
chamber 283 through opening 402b, cylinder 401, and opening 361a,
if the pressure in connecting chamber 283 is less than the pressure
of the fluid enclosed in bellows portion 403b, bellow portions 403b
expands. Valve portion 403a opens opening 402a of piston valve 402,
and a small amount of compressed fluid which is supplied to the top
space of cylinder 401 from conduit 406 flows into communicating
chamber 283 through piston valve 402 and cylinder 401. At this
time, piston 407 which closes opening 361b, is pushed upwardly by
the recoil strength of spring 404, and established communication
between communicating chamber 263 and intermediate pressure chamber
282. Therefore, the compression ratio is decreased.
On the other hand, if the pressure of fluid in communicating
chamber 283 is larger than the pressure of the fluid in bellows
portion 403b, bellows portion 403b contracts and opening 402a is
closed by valve portion 403a. In this situation, a small amount of
compressed fluid flows from discharge chamber 281 into the top
space of cylinder 401, and piston valve 402 is pushed downwardly
against the recoil strength of spring 404. Opening 361a and 361b
are therefore closed by piston valve 402, and the compression ratio
is increased. In this embodiment, the construction of valve portion
403a is a simple structure. However, a needle-ball type valve
mechanism 41 may be used, as shown in FIG. 7. Also, the force
caused by bellows portion 403b is controlled by the position of
bellows 403, which, in turn, is determined by screw 42 screwed on
the bottom portion of piston valve 402, as shown in FIG. 7.
Needle-ball type valve mechanism 41, as shown in FIG. 7, uses
elements similar to those of valve mechanism 40 of FIG. 6.
Needle-ball type valve mechanism 41 is connected to discharge
chamber 281 through conduit 406 and capillary tube 368. When the
pressure in cylinder 401 is less than the pressure within bellows
portion 403b, bellows portion 403b expands, needle-ball type valve
mechanism 41 is pushed upwardly, and opening 402a of piston valve
402 is opened. Therefore, discharge chamber 281 is placed in fluid
communication with the interior of piston valve 402 through conduit
406 and capillary tube 368.
When the pressure in cylinder 401 is greater than the pressure
within bellows portion 403b, bellows portion 403b contracts and
needle-ball type valve mechanism 41 is pushed downwardly and
obstructs opening 402a of piston valve 402. Thus, discharge chamber
281 is not in fluid communication with the interior of piston valve
402, and the compressed fluid from the discharge chamber 281 acts
on the upper end surface of piston valve 402 to push downwardly
piston valve 402 against the recoil strength of spring 404. This
obstructs communication between communicating chamber 283 and
intermediate pressure chamber 282 and increases the compression
ratio.
Numerous characteristics, advantages, and embodiments of the
invention have been described in detail in the foregoing
description with reference to the accompanying drawings. However,
the disclosure is illustrative only and it is to be understood that
the invention is not limited to the precise illustrated
embodiments. Various changes and modifications may be effected
therein by one skilled in the art without departing from the scope
of spirit of the invention.
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