U.S. patent application number 12/218730 was filed with the patent office on 2009-01-22 for suction structure in piston type compressor.
Invention is credited to Nobuaki Hoshino, Masaki Ota.
Application Number | 20090022604 12/218730 |
Document ID | / |
Family ID | 40264979 |
Filed Date | 2009-01-22 |
United States Patent
Application |
20090022604 |
Kind Code |
A1 |
Hoshino; Nobuaki ; et
al. |
January 22, 2009 |
Suction structure in piston type compressor
Abstract
A suction structure is provided for allowing refrigerant from a
suction pressure region in a piston type compressor. The compressor
includes a rotary valve. The suction structure includes a shifting
device which shifts between a connecting state and a disconnecting
state. In the connecting state an outlet of a supply passage of the
rotary valve is connected to a suction pressure region and in the
disconnecting state the outlet of the supply passage is
disconnected from the suction pressure region. The shifting device
includes a valve body, a return spring, and a permanent magnet. The
valve body is movable between a connecting position and a
disconnecting position. The return spring urges the valve body from
the connecting position toward the disconnecting position. The
permanent magnet attracts the valve body by magnetic force from the
connecting position toward the disconnecting position.
Inventors: |
Hoshino; Nobuaki;
(Kariya-shi, JP) ; Ota; Masaki; (Kariya-shi,
JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 WORLD FINANCIAL CENTER
NEW YORK
NY
10281-2101
US
|
Family ID: |
40264979 |
Appl. No.: |
12/218730 |
Filed: |
July 17, 2008 |
Current U.S.
Class: |
417/269 ;
417/559 |
Current CPC
Class: |
F04B 27/1009 20130101;
F04B 27/1018 20130101; F05C 2251/12 20130101 |
Class at
Publication: |
417/269 ;
417/559 |
International
Class: |
F04B 27/08 20060101
F04B027/08; F04B 39/10 20060101 F04B039/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2007 |
JP |
2007-187207 |
Claims
1. A suction structure for allowing refrigerant from a suction
pressure region in a piston type compressor, wherein cylinder bores
for accommodating a respective piston are arranged around a rotary
shaft, wherein a cam body is formed with the rotary shaft, wherein
the piston is engaged with the cam body so that rotation of the
rotary shaft is transmitted to the piston, wherein a compression
chamber is defined by the piston in the respective cylinder bore,
wherein a rotary valve is rotated integrally with the rotary shaft,
wherein the rotary valve has a supply passage for introducing the
refrigerant from the suction pressure region to the compression
chamber, the suction structure comprising: a shifting device for
shifting between a connecting state and a disconnecting state,
wherein in the connecting state an outlet of the supply passage is
connected to the suction pressure region and in the disconnecting
state the outlet of the supply passage is disconnected from the
suction pressure region, the shifting device including; a valve
body movable between a connecting position and a disconnecting
position, wherein the connecting position corresponds to the
connecting state and the disconnecting position corresponds to the
disconnecting state; a return spring urging the valve body from the
connecting position toward the disconnecting position; and a
permanent magnet for attracting the valve body by magnetic force
from the connecting position toward the disconnecting position.
2. The suction structure according to claim 1, wherein the
compressor has a housing and the permanent magnet is fixed to the
housing.
3. The suction structure according to claim 2, wherein the valve
body is in contact with the permanent magnet when the valve body is
in the disconnecting position.
4. The suction structure according to claim 3, wherein the valve
body is in surface contact with the permanent magnet.
5. The suction structure according to claim 1, wherein the valve
body disconnects an inlet of the supply passage from the suction
pressure region when the shifting device is in the disconnecting
state.
6. The suction structure according to claim 1, wherein the
compressor includes a cylinder block in which the cylinder bores
are formed, wherein a rear housing is connected to the cylinder
block, wherein a suction chamber as the suction pressure region is
formed in the rear housing, wherein the valve body is provided in
the rear housing.
7. The suction structure according to claim 6, the valve body is
moved between the connecting position and the disconnecting
position in the direction of a rotary axis of the rotary shaft, and
wherein the permanent magnet is fixed to an inner wall surface of
the rear housing which extends so as to intersect with the movement
direction of the valve body.
8. The suction structure according to claim 1, wherein the
compressor has a housing, and the housing includes a communication
chamber and a suction chamber, wherein a partition wall separates
the communication chamber from the suction chamber, and wherein the
permanent magnet is formed with the partition wall.
9. The suction structure according to claim 1, wherein the valve
body includes a piston, a rod, a disk and a cylindrical body,
wherein the piston is attracted by the permanent magnet, wherein
the rod is connected to the piston, the disk and the cylindrical
body, wherein the disk and the cylindrical body disconnect the
outlet of the supply passage from the suction pressure region when
the shifting device is in the disconnecting state.
10. The suction structure according to claim 1, wherein the
compressor has a housing, and wherein a plate formed of magnetic
material is fixed to the housing and the permanent magnet is formed
with the valve body so as to be moved to and apart from the
plate.
11. The suction structure according to claim 1, wherein the rotary
shaft is connected to an external drive source through a
clutch.
12. A suction structure for allowing refrigerant to flow from a
suction pressure region in a piston type compressor, wherein
cylinder bores for accommodating a respective piston are arranged
around a rotary shaft, wherein a cam body is formed with the rotary
shaft, wherein the piston is engaged with the cam body so that
rotation of the rotary shaft is transmitted to the piston, wherein
a compression chamber is defined by the piston in the respective
cylinder bore, wherein a valve mechanism is disposed adjacent to
the compression chamber, the suction structure comprising: a
shifting device for shifting between a connecting state and a
disconnecting state, wherein in the connecting state the
compression chamber is connected to the suction pressure region
upstream the shifting device through the valve mechanism and in the
disconnecting state the compression chamber is disconnected from
the suction pressure region upstream the shifting device through
the valve mechanism, the shifting device including; a valve body
movable between a connecting position and a disconnecting position,
wherein the connecting position corresponds to the connecting state
and the disconnecting position corresponds to the disconnecting
state; a return spring urging the valve body from the connecting
position toward the disconnecting position; and a permanent magnet
for attracting the valve body by magnetic force from the connecting
position toward the disconnecting position.
13. A piston type compressor comprising: a housing; cylinder bores
formed in the housing, wherein the cylinder bores are arranged
around a rotary shaft; pistons accommodated in the respective
cylinder bore; a cam body formed with the rotary shaft, wherein the
piston is engaged with the cam body so that rotation of the rotary
shaft is transmitted to the piston; a compression chamber defined
by the piston in the respective cylinder bore; a rotary valve
rotated integrally with the rotary shaft, wherein the rotary valve
includes a supply passage for introducing refrigerant from a
suction pressure region in the compressor to the compression
chamber; and a shifting device for shifting between a connecting
state and a disconnecting state, wherein in the connecting state an
outlet of the supply passage is connected to the suction pressure
region and in the disconnecting state the outlet of the supply
passage is disconnected from the suction pressure region, the
shifting device including; a valve body movable between a
connecting position and a disconnecting position, wherein the
connecting position corresponds to the connecting state and the
disconnecting position corresponds to the disconnecting state; a
return spring urging the valve body from the connecting position
toward the disconnecting position; and a permanent magnet for
attracting the valve body by magnetic force from the connecting
position toward the disconnecting position.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a suction structure for
allowing refrigerant from a suction pressure region in a piston
type compressor. More specifically, the compressor has a rotary
valve that is integrally rotated with a rotary shaft and that has a
supply passage for introducing refrigerant from the suction
pressure region into a compression chamber defined in a cylinder
bore by a piston.
[0002] In piston type compressors, there are two types of suction
valves. One is a rotary valve as disclosed in Unexamined Japanese
Patent Publications No. 7-119631 and No. 2006-083835. The other is
a reed type suction valve as disclosed in Unexamined Japanese
Patent Publications No. 64-088064 and No. 2000-145629. The piston
type compressors including the rotary valves has lower suction
resistance in introducing refrigerant into cylinder bores, and has
superior energy efficiency, compared to the piston type compressors
including the reed type suction valves.
[0003] At the start of a conventional compressor disclosed in the
above reference No. 7-119631, torque is rapidly increased in
accordance with the compression of refrigerant gas, and is applied
as a load to a vehicle engine (internal combustion). Thereby the
vehicle speed is temporarily decreased at the start of the
compressor, and the passengers of the vehicle feel start-up
shock.
[0004] In the piston type compressor disclosed in the above
reference No. 7-119631, the rotary valve is provided so as to be
axially movable in the direction of the axis of the rotary shaft.
The position of the rotary valve is displaced in accordance with
the pressure supplied to a control pressure chamber. A bypass
groove is formed in the rotary valve so as to communicate almost
all the cylinder bores to a suction port formed at the center of a
cylinder block. The rotary valve is located at a position in the
axial direction of the rotary shaft in such a manner that almost
all the cylinder bores are communicable with the suction port
through the bypass groove at the stop and at the start of the
compressor. Therefore, even when the piston performs compression of
the refrigerant gas in the cylinder bore at the start of the
compressor, the refrigerant gas in the cylinder bore is returned to
the suction port through the bypass groove. The shock at the start
of the compressor does not occur, accordingly.
[0005] In order to prevent leakage of the refrigerant gas along the
periphery of the rotary valve, and also to allow the rotary valve
to rotate, it is required that clearance around the periphery of
the rotary valve is set as small as possible. However, with the
structure in which the rotary valve is movable in the axial
direction of the rotary shaft, the rotary valve needs clearance to
allow the rotary valve to be movable in the axial direction of the
rotary shaft. It is hard to set such clearance appropriately.
[0006] A compressor disclosed in Unexamined Japanese Patent
Publication No. 2000-145629 includes a pressure differential
detecting valve which is opened and closed in accordance with the
pressure differential between discharge pressure and suction
pressure. The pressure differential detecting valve is located
between a low-pressure refrigerant passage for introducing
refrigerant from the outside of the compressor and a suction
chamber in the compressor. When the compressor is started in a
state where the pressure in the compressor is balanced, the
pressure differential detecting valve is closed, and the flow of
the refrigerant from the outside of the compressor into the suction
chamber is stopped. Thereby the shock at the start of the
compressor is suppressed.
[0007] However, in the compressor disclosed in the reference No.
2000-145629, the refrigerant is remained in the suction chamber
even when the pressure differential detecting valve is closed. The
residual refrigerant is introduced into the cylinder bore and
compressed therein. The volume of the suction chamber is set large
so as to suppress the suction pulsation. Thereby large amount of
refrigerant is introduced into the cylinder bore in a state where
the pressure differential detecting valve is closed, and the effect
in suppressing the shock at the start of the compressor is not
sufficiently obtained.
[0008] The present invention is directed to increase the effect in
suppressing the shock at the start of the compressor.
SUMMARY OF THE INVENTION
[0009] In accordance with the present invention, a suction
structure is provided for allowing refrigerant from a suction
pressure region in a piston type compressor. The compressor has
cylinder bores arranged around a rotary shaft for accommodating a
respective piston. A cam body is formed with the rotary shaft. The
piston is engaged with the cam body so that rotation of the rotary
shaft is transmitted to the piston. A compression chamber is
defined by the piston in the respective cylinder bore. A rotary
valve has a supply passage for introducing the refrigerant from the
suction pressure region to the compression chamber. The rotary
valve is rotated integrally with the rotary shaft. The suction
structure includes a shifting device. The shifting device shifts
between a connecting state and a disconnecting state. In the
connecting state the outlet of the supply passage is connected to
the suction pressure region and in the disconnecting state the
outlet of the supply passage is disconnected from the suction
pressure region. The shifting device includes a valve body, a
return spring, and a permanent magnet. The valve body is movable
between a connecting position and a disconnecting position. The
connecting position corresponds to the connecting state and the
disconnecting position corresponds to the disconnecting state. The
return spring urges the valve body from the connecting position
toward the disconnecting position. The permanent magnet attracts
the valve body by magnetic force from the connecting position
toward the disconnecting position.
[0010] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The features of the present invention that are believed to
be novel are set forth with particularity in the appended claims.
The invention together with objects and advantages thereof, may
best be understood by reference to the following description of the
presently preferred embodiments together with the accompanying
drawings in which:
[0012] FIG. 1 is a longitudinal cross-sectional view of a
compressor according to a first preferred embodiment of the present
invention;
[0013] FIG. 2A is a cross-sectional view which is taken along the
line I-I in FIG. 1;
[0014] FIG. 2B is a cross-sectional view which is taken along the
line II-II in FIG. 1;
[0015] FIG. 3 is a partially enlarged cross-sectional view
illustrating the suction structure of the compressor in a
disconnecting state according to the first preferred embodiment of
the present invention;
[0016] FIG. 4 is a partially enlarged cross-sectional view
illustrating the suction structure of the compressor in a
connecting state according to the first preferred embodiment of the
present invention;
[0017] FIG. 5A is a graph showing torque fluctuation of the
compressor having a permanent magnet according to the first
preferred embodiment of the present invention;
[0018] FIG. 5B is a graph showing positional change of a valve body
in the compressor having the permanent magnet according to the
first preferred embodiment of the present invention;
[0019] FIG. 5C is a graph showing torque fluctuation of a piston
type compressor without the permanent magnet;
[0020] FIG. 5D is a graph showing positional change of a valve body
in the piston type compressor without the permanent magnet;
[0021] FIG. 6A is a partially enlarged cross-sectional view of a
compressor illustrating a suction structure in a disconnecting
state according to a second preferred embodiment of the present
invention;
[0022] FIG. 6B is a partially enlarged cross-sectional view of the
compressor illustrating the suction structure in a connecting state
according to the second preferred embodiment of the present
invention;
[0023] FIG. 7A is a partially enlarged cross-sectional view of a
compressor illustrating a suction structure in a connecting state
according to a third preferred embodiment of the present
invention;
[0024] FIG. 7B is a partially enlarged cross-sectional view of the
compressor illustrating the suction structure in a disconnecting
state according to the third preferred embodiment of the present
invention;
[0025] FIG. 8A is a partially enlarged cross-sectional view of a
compressor illustrating a suction structure in a disconnecting
state according to a fourth preferred embodiment of the present
invention;
[0026] FIG. 8B is a partially enlarged cross-sectional view of the
compressor illustrating the suction structure in a connecting state
according to the fourth preferred embodiment of the present
invention; and
[0027] FIG. 9 is a longitudinal cross-sectional view of a
compressor according to a fifth preferred embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] A first preferred embodiment of a piston type compressor 10
according to the present invention will now be described with
reference to FIGS. 1 through 5. The compressor 10 is a fixed
displacement type. It is noted that the front side and the rear
side of the compressor 10 respectively correspond to the left side
and the right side in the drawings. Referring to FIG. 1, a front
cylinder block 11 is connected to a rear cylinder block 12. A front
housing 13 is connected to the front cylinder block 11. A rear
housing 14 is connected to the rear cylinder block 12. The front
and rear cylinder blocks 11, 12 and the front and rear housings 13,
14 constitute a whole compressor housing assembly of the piston
type compressor 10. A discharge chamber 131 as a discharge pressure
region in the compressor 10 is defined in the front housing 13. A
discharge chamber 141 as a discharge pressure region in the
compressor 10 is defined in the rear housing 14. A suction chamber
142 as a suction pressure region is defined in the rear housing 14.
It is noted that "in the compressor" corresponds to the inside of
the whole compressor housing assembly, and that "out of the
compressor" corresponds to the outside of the whole compressor
housing assembly.
[0029] A valve port plate 15, a valve plate 16 and a retainer plate
17 are interposed between the front cylinder block 11 and the front
housing 13. A valve port plate 18, a valve plate 19 and a retainer
plate 20 are interposed between the rear cylinder block 12 and the
rear housing 14. Discharge ports 151, 181 are respectively formed
in the valve port plates 15, 18. Discharge valves 161, 191 are
respectively formed in the valve plates 16, 19 to open and close
the respective discharge ports 151, 181. Retainers 171, 201 are
respectively formed in the retainer plates 17, 20 to regulate the
respective opening degrees of the discharge valves 161, 191.
[0030] A rotary shaft 21 is rotatably supported by the front and
rear cylinder blocks 11, 12 and is inserted into shaft holes 111,
121 which extend through the front and rear cylinder blocks 11, 12.
The outer periphery of the rotary shaft 21 is in contact with the
inner periphery of the shaft holes 111, 121. The rotary shaft 21 is
directly supported by the front and rear cylinder blocks 11, 12
through the inner periphery of the respective shaft holes 111 and
121. A contacting portion of the outer periphery of the rotary
shaft 21 with the shaft hole 111 forms a sealing circumferential
surface 211. A contacting portion of the outer periphery of the
rotary shaft 21 with the shaft hole 121 forms a sealing
circumferential surface 212.
[0031] A swash plate 23 as a cam body is secured to the rotary
shaft 21. The swash plate 23 is accommodated in a crank chamber 24
which is defined between the front and rear cylinder blocks 11, 12.
A lip-seal type shaft seal member 22 is interposed between the
front housing 13 and the rotary shaft 21. The shaft seal member 22
prevents leakage of the refrigerant gas through the clearance
between the front housing 13 and rotary shaft 21. The front end of
the rotary shaft 21 protruding externally from the front housing 13
is connected to a vehicle engine 26 as an external drive source
through an electromagnetic clutch 25. The rotary shaft 21 receives
driving force for rotation from the vehicle engine 26 through the
electromagnetic clutch 25.
[0032] As shown in FIG. 2A, a plurality of front cylinder bores 27
is formed in the front cylinder block 11 and is arranged around the
rotary shaft 21. As shown in FIG. 2B, a plurality of rear cylinder
bores 28 is formed in the rear cylinder block 12 and is arranged
around the rotary shaft 21. Front and rear heads of a double-headed
piston 29 are respectively accommodated in the pair of the cylinder
bores 27, 28.
[0033] As shown in FIG. 1, the double-headed piston 29 is engaged
with the swash plate 23 through a pair of shoes 30. The swash plate
23 integrally rotates with the rotary shaft 21. The rotary motion
of the swash plate 23 is transmitted to the double-headed piston 29
through the shoes 30 so that the double-headed piston 29
reciprocates in the pair of the cylinder bores 27, 28. Compression
chambers 271, 281 are defined in the respective cylinder bores 27,
28.
[0034] An in-shaft passage 31 is formed in the rotary shaft 21. The
in-shaft passage 31 extends along the rotary axis 210 of the rotary
shaft 21. An inlet 311 of the in-shaft passage 31 is formed at an
end surface 213 of the rotary shaft 21 in the cylinder block 12.
The inlet 311 is open to the suction chamber 142 in the rear
housing 14. A front outlet 312 of the in-shaft passage 31 is open
at the front sealing circumferential surface 211 of the rotary
shaft 21 in the shaft hole 111. A rear outlet 313 of the in-shaft
passage 31 is open at the rear sealing circumferential surface 212
of the rotary shaft 21 in the shaft hole 121.
[0035] As shown in FIG. 2A, a front communication passage 32 is
formed in the front cylinder block 11 so as to communicate with the
cylinder bore 27 and the shaft hole 111. As shown in FIG. 2B, a
rear communication passage 33 is formed in the rear cylinder block
12 so as to communicate with the cylinder bore 28 and the shaft
hole 121. As the rotary shaft 21 rotates, the outlets 312, 313 of
the in-shaft passage 31 intermittently communicate with the
communication passages 32, 33.
[0036] When the front cylinder bore 27 is in a suction process,
that is, when the double-headed piston 29 moves from the left side
to the right side in FIG. 1, the outlet 312 communicates with the
communication passage 32. As a result, refrigerant in the in-shaft
passage 31 is introduced into the compression chamber 271 in the
cylinder bore 27 through the outlet 312 and the communication
passage 32.
[0037] When the front cylinder bore 27 is in a discharge process,
that is, when the double-headed piston 29 moves from the right side
to the left side in FIG. 1, the outlet 312 is disconnected from the
communication passage 32. As a result, refrigerant in the
compression chamber 271 is discharged to the discharge chamber 131
through the discharge port 151 by pushing the discharge valve 161
away. The refrigerant discharged to the discharge chamber 131 flows
out to an external refrigerant circuit 34 through a passage
341.
[0038] When the rear cylinder bore 28 is in a suction process, that
is, in a process of the double-headed piston 29 moving from the
right side to the left side in FIG. 1, the outlet 313 communicates
with the communication passage 33. As a result, refrigerant in the
in-shaft passage 31 of the rotary shaft 21 is introduced into the
compression chamber 281 of the cylinder bore 28 through the outlet
313 and the communication passage 33.
[0039] When the rear cylinder bore 28 is in a discharge process,
that is, in a process of the double-headed piston 29 moving from
the left side to the right side in FIG. 1, the outlet 313 is
disconnected from the communication passage 33. As a result,
refrigerant in the compression chamber 281 is discharged to the
discharge chamber 141 through the discharge port 181 by pushing the
discharge valve 191 away. The refrigerant discharged to the
discharge chamber 141 flows out to the external refrigerant circuit
34 through a passage 342.
[0040] The external refrigerant circuit 34 is provided with a heat
exchanger 37 for removing heat from refrigerant, an expansion valve
38, and a heat exchanger 39 for evaporating the refrigerant with
heat. The expansion valve 38 controls the flow rate of the
refrigerant in accordance with the fluctuation in temperature of
the gaseous refrigerant at the outlet of the heat exchanger 39. The
refrigerant flowing out to the external refrigerant circuit 34
returns to the suction chamber 142.
[0041] The part of the rotary shaft 21 corresponding to the sealing
circumferential surface 211 forms a first rotary valve 35. The part
of the rotary shaft 21 corresponding to the sealing circumferential
surface 212 forms a second rotary valve 36. The rotary valves 35,
36 serve as a valve mechanism which is disposed adjacent to the
compression chambers 271, 281 in this embodiment. The rotary valves
35, 36 are formed integrally with the rotary shaft 21. That is, the
rotary shaft 21 serves as rotary valves. The rotary axis 210 serves
as the rotary axis of the rotary valves. The end surface 213 of the
rotary shaft 21 (the end surface of the rotary valve) intersects
with the rotary axis 210 of the rotary valves. The in-shaft passage
31 and outlets 312, 313 form the supply passage of the rotary
valves 35, 36. The shaft hole 111 serves as a valve accommodation
chamber for accommodating the first rotary valve 35, and the shaft
hole 121 serves as a valve accommodation chamber for accommodating
the second rotary valve 36.
[0042] As shown in FIGS. 3 and 4, a base portion 40 is formed
integrally with the end wall of the rear housing 14. An inner wall
of the rear housing 14 defines the suction chamber 142. A
cylindrical portion 41 is formed integrally with the inner wall
surface 401 of the base portion 40. The rotary axis 210 of the
rotary shaft 21 intersects with the inner wall surface 401
perpendicularly.
[0043] A valve body 42 in the form of a spool is slidably inserted
in the inner space 411 inside of the cylindrical portion 41. The
valve body 42 is formed of magnetic material. The valve body 42
includes a disk-like piston member 43 and a cylindrical member 44.
An introduction port 441 is open at the outer peripheral surface of
the cylindrical member 44. The introduction port 441 communicates
with the inner space 442 inside of the cylindrical member 44. The
inner space 442 serves as an inner passage of the valve body 42.
The piston member 43 defines a pressure chamber 412 in the inner
space 411 inside of the cylindrical portion 41. The pressure
chamber 412 communicates with the suction chamber 142 through a
hole 413.
[0044] A guide cylinder 45 is formed integrally with the end
surface of the rear cylinder block 12 adjacent to the rear housing
14 so as to face to the cylindrical portion 41. The inner space 451
of the guide cylinder 45 communicates with the inlet 311 of the
in-shaft passage 31 of the rotary shaft 21. The rear end of the
guide cylinder 45 and the front end of the cylindrical portion 41
are spaced apart from each other, and the cylindrical member 44 of
the valve body 42 is slidably fitted together by insertion with the
guide cylinder 45. A circular clip 46 is attached to the inner
circumferential surface of the guide cylinder 45. A return spring
47 is interposed between the circular clip 46 and the piston member
43. The return spring 47 urges the valve body 42 so that the valve
body 42 approaches the base portion 40. When the valve body 42
approaches the base portion 40, the volume of the pressure chamber
412 decreases.
[0045] In the inner space 411 of the cylindrical portion 41, a
permanent magnet 48 is fixed to the inner wall surface 401 of the
base portion 40. The permanent magnet 48 protrudes from the inner
wall surface 401 in the inner space 411 so that the piston member
43 is capable of coming into surface contact with the permanent
magnet 48.
[0046] In the state shown in FIG. 4, the introduction port 441 is
in a position where the entire introduction port 441 is exposed to
the suction chamber 142. The in-shaft passage 31 communicates with
the suction chamber 142 through the inner space 451 of the guide
cylinder 45, the inner space 442 of the cylindrical portion 44 and
the introduction port 441. In this state, the valve body 42 is
spaced apart from the permanent magnet 48, and FIG. 4 shows a state
where the valve body 42 is in a position to connect the in-shaft
passage 31 to the suction chamber 142. In a state shown in FIG. 3,
the introduction port 441 is in a position where the entire
introduction port 441 is fitted in the inner space 411, and the
in-shaft passage 31 is disconnected from the suction chamber 142.
In this state, the valve body 42 is in surface contact with the
permanent magnet 48, and FIG. 3 shows a state where the valve body
42 is in a position to disconnect the in-shaft passage 31 from the
suction chamber 142.
[0047] As shown in FIG. 1, the activation of the electromagnetic
clutch 25 is controlled by a computer C. The computer C is
connected by way of signals to an operating switch 49 for an air
conditioner, a room temperature setting device 50 for setting a
target room temperature, and a room temperature detecting device 51
for detecting a room temperature. When the operating switch 49 is
turned on, the computer C controls the electric supply (activation
and deactivation) to the electromagnetic clutch 25 in accordance
with the temperature difference between the target room temperature
and the detected room temperature.
[0048] The computer C shuts off the electric supply to the
electromagnetic clutch 25, when the detected temperature is lower
than the target temperature, or, when the detected temperature is
higher than the target temperature and the temperature difference
is within an allowable range. In this case, the electromagnetic
clutch 25 is in a disconnected state, and the driving force of the
vehicle engine 26 is not transmitted to the rotary shaft 21. The
computer C supplies electric current to the electromagnetic clutch
25, when the detected temperature is higher than the target
temperature and the temperature difference between the detected
temperature and the target temperature is beyond the allowable
level. In this case, the electromagnetic clutch 25 is in a
connected state, and the driving force of the vehicle engine 26 is
transmitted to the rotary shaft 21.
[0049] When the operation of the compressor 10 is shut down (the
electromagnetic clutch 25 is in a disconnected state), the pressure
in the compressor 10 is balanced. In this state, the valve body 42
is in the disconnecting position by the spring force of the return
spring 47, as shown in FIG. 3. When the compressor 10 is started,
the refrigerant in the in-shaft passage 31 and the inner spaces
451, 442 is introduced into the compression chambers 271 (as shown
in FIG. 1) and 281. Due to the suction motion, the pressures in the
in-shaft passage 31 and the inner spaces 451, 442 are decreased.
That is, the pressures in the in-shaft passage 31 and the inner
spaces 451, 442 become lower than the pressure in the suction
chamber 142. The pressure in the suction chamber 142 is applied to
the pressure chamber 412, and the pressure in the pressure chambers
412 corresponds to the pressure in the suction chamber 142. The
pressure in the pressure chamber 412 opposes to the pressure in the
inner spaces 451, 442 and the spring force of the return spring 47
through the valve body 42.
[0050] The sum of the spring force of the return spring 47 and the
magnetic force of the permanent magnet 48 is set to be overcome by
the pressure difference between the pressure chamber 412 and the
inner spaces 451, 442 when the compressor 10 is operated. When the
compressor 10 is started in a state where the valve body 42 is in
contact with the permanent magnet 48, the pressure difference
between the pressure chamber 412 and the inner spaces 451, 442
overcomes the sum of the spring force of the return spring 47 and
the magnetic force of the permanent magnet 48. Thereby the valve
body 42 is moved from the disconnecting position as shown in FIG. 3
to the connecting position as shown in FIG. 4. When the valve body
42 is in the connecting position, the refrigerant in the suction
chamber 142 flows into the compression chambers 271, 281 through
the introduction port 441, inner spaces 442, 451, in-shaft passage
31 and the communication passages 32, 33.
[0051] When the operation of the compressor 10 is stopped, the
refrigerant in the in-shaft passage 31 and the inner spaces 451,
442 is not introduced into the compression chambers 271 (as shown
in FIG. 1) and 281. Thereby the pressures in the in-shaft passage
31 and the inner spaces 451, 442 are increased. Therefore, the
pressures in the in-shaft passage 31 and the inner spaces 451, 442
are balanced with the pressure in the pressure chamber 412.
Accordingly the valve body 42 is moved from the connecting position
as shown in FIG. 4 to the disconnecting position as shown in FIG. 3
due to the spring force of the return spring 47.
[0052] The valve body 42 is moved between the connecting position
and the disconnecting position in accordance with the pressure in
the supply passage (the in-shaft passage 31) which corresponds to
the operated state and the stopped state of the compressor 10. When
the valve body 42 is located in the connecting position, the
outlets 312, 313 of the supply passage are connected to the suction
chamber 142 (suction pressure region) in the compressor 10. When
the valve body 42 is located in the disconnecting position, the
outlets 312, 313 of the supply passage are disconnected from the
suction chamber 142. The valve body 42, the return spring 47, the
permanent magnet 48 constitute a shifting device 52. The shifting
device 52 shifts between the connecting state and the disconnecting
state.
[0053] In the state shown in FIG. 3, the shifting device 52 is in
the disconnecting state where the outlets 312 (as shown in FIG. 1)
and 313 of the supply passage are disconnected from the suction
chamber 142. In other words, the compression chambers 271, 281 are
disconnected from the suction chamber 142 upstream the shifting
device 52 through the valve mechanism (the rotary valves 35, 36).
In the state shown in FIG. 4, the shifting device 52 is in the
connecting state where the outlets 312 (as shown in FIG. 1) and 313
of the supply passage are connected to the suction chamber 142. In
other words, the compression chambers 271, 281 are connected to the
suction chamber 142 upstream the shifting device 52 through the
rotary valves 35, 36.
[0054] FIG. 5A shows a graph of torque fluctuation of the
compressor 10 with the permanent magnet 48, and a waveform E1 in
FIG. 5A indicates the torque fluctuation in the compressor 10 when
the compressor 10 is started. FIG. 5B shows a graph of positional
change of the valve body 42 in the compressor 10 having the
permanent magnet 48, and a line D1 indicates the positional change
of the valve body 42. In the graph of FIG. 5A, the horizontal axis
represents time, and the vertical axis represents torque. Time T0
represents the time when the electromagnetic clutch 25 is changed
from a deactivated state into an activated state. Time T1
represents starting time when the introduction port 441 is exposed
to the suction chamber 142, that is, the starting time of
communication between the suction chamber 142 and the inner space
442. In the graph of FIG. 5B, the horizontal axis represents time,
and the vertical axis represents the position of the valve body 42.
Position L1 represents the disconnecting position (the position of
the valve body 42 shown in FIG. 3) and position L2 represents the
connecting position (the position of the valve body 42 shown in
FIG. 4). The difference (T1-T0) represents the elapsed time from
the time T0 when the electromagnetic clutch 25 is changed into the
activated state, to the time T1 when the communication between the
introduction port 441 and the suction chamber 142 is started.
[0055] FIG. 5C shows a graph of torque fluctuation of a fixed
displacement piston type compressor without the permanent magnet
48, and a waveform E2 in FIG. 5C indicates the torque fluctuation
in the compressor when the compressor is started. FIG. 5D shows a
graph of positional change of a valve body in the compressor
without the permanent magnet 48, and a line D2 indicates the
positional change of the valve body. In the graph of FIG. 5C, the
horizontal axis represents time, and the vertical axis represents
torque. Time T0 represents the time when the electromagnetic clutch
25 is changed from a deactivated state into the activated state.
Time T2 represents starting time when the introduction port 441 is
exposed to the suction chamber 142, that is, the starting time of
communication between the suction chamber 142 and the inner space
442. In the graph of FIG. 5D, the horizontal axis represents time,
and the vertical axis represents the position of the valve body.
The difference (T2-T0) represents the elapsed time from the time T0
when the electromagnetic clutch 25 is changed into the activated
state, to the time T2 when the communication between the
introduction port 441 and the suction chamber 142 is started.
[0056] According to the first preferred embodiment, the following
advantageous effects are obtained.
(1) As shown in the graphs of FIGS. 5A, 5C, the elapsed time
(T1-T0) is greater than the elapsed time (T2-T0). When the elapsed
time (T1-T0) is greater, sudden torque fluctuation in a short time
is effectively reduced in the compressor 10.
[0057] The difference between the elapsed time (T1-T0) and the
elapsed time (T2-T0) is resulted from whether the compressor 10 has
the permanent magnet 48 or not. The magnetic force of the permanent
magnet 48 delays the start of the movement of the valve body 42,
which is in the disconnecting position at the start of the
compressor 10, moving from the disconnecting position to the
connecting position. Thereby the elapsed time (T1-T0) is greater
than the elapsed time (T2-T0), and as a result, the shock at the
start of the compressor 10 is reduced.
[0058] Further, the compressed amount of the refrigerant is small
during the time when the communication between the suction chamber
142 in the compressor 10 and the introduction port 441 is shut off
(that is, the valve body 42 is in the disconnecting position).
Thereby the effect reducing the torque fluctuation, or, the shock
absorbing effect at the start of the compressor 10 is high.
(2) The valve body 42 is urged by the permanent magnet 48 in
addition to the return spring 47 in the direction from the
connecting position to the disconnect position. The magnetic force
of the permanent magnet 48 which is applied to the valve body 42 is
maximum when the valve body 42 is in the disconnecting position.
Thereby, the spring force of the return spring 47 for positioning
the valve body 42 in the disconnecting position can be reduced,
compared to the case where the permanent magnet 48 is not
provided.
[0059] When the communication between the suction chamber 142 and
the introduction port 441 is started, the pressure fluctuation in
the supply passage is large, and hunting of the valve body 42 may
be easily occurred. Once the valve body 42 is moved apart from the
disconnecting position (the position where the valve body 42 is
stuck to the permanent magnet 48), the magnetic force of the
permanent magnet 48 attracting the valve body 42 toward the
disconnecting position is getting to be rapidly reduced. Thereby
the movement speed of the valve body 42 is increased after the
valve body 42 is moved apart from the permanent magnet 48, compared
to the case without the permanent magnet 48. Therefore, even when
the fluctuation in the pressure condition in the supply passage is
large, the hunting of the valve body 42 is suppressed.
(3) When the compressor 10 is stopped, the valve body 42 is
returned to the disconnecting position by the spring force of the
return spring 47. Utilizing the return spring 47 results in a
simple construction in returning the valve body 42 to the
disconnecting position. (4) The valve body 42 is moved in the
direction of the rotary axis 210 of the rotary shaft 21. The inner
wall surface 401 of the rear housing 14 extends so as to intersect
with the movement direction of the valve body 42 (the direction of
the rotary axis 210). The inner wall surface 401 of the rear
housing 14 is an appropriate position for providing the permanent
magnet 48. (5) When the valve body 42 is in the disconnecting
position, the valve body 42 is in contact with the permanent magnet
48. The construction where the valve body 42 comes into contact
with the permanent magnet 48 is appropriate for increasing the
performing force of the permanent magnet 48 which maintains the
valve body 42 in the disconnecting position. (6) The valve body 42
in the disconnecting position is maintained at the disconnecting
position in the surface contacting state with the permanent magnet
48. The structure where the valve body 42 comes into surface
contact with the permanent magnet 48 is appropriate for increasing
the performing force of the permanent magnet 48 which maintains the
valve body 42 in the disconnecting position. (7) The introduction
port 441 as the inlet of the inner space 442 of the valve body 42
is closed in such a manner that the introduction port 441 is
located in the inner space 442 when the valve body 42 is in the
disconnecting position. The introduction port 441 is exposed to the
suction chamber 142 at the outside the inner space 411 when the
valve body 42 is at the connecting position. The construction in
which the introduction port 441 moves into and away from the inner
space 411 is appropriate for ensuring a sufficient cross-sectional
area of the supply passage by enlarging the introduction port
441.
[0060] A second preferred embodiment of the present invention will
now be described with reference to FIGS. 6A, 6B. The same reference
numerals denote the identical components to those in the first
preferred embodiment.
[0061] The rear housing 14 includes a communication chamber 53 and
a valve hole 541 formed therein. A plate 55 for opening and closing
the valve hole 541 is accommodated in the communication chamber 53.
The plate 55 is made of magnetic material. The valve hole 541 is
formed through a partition wall 54 which separates the
communication chamber 53 from the suction chamber 142. The inlet
311 of the in-shaft passage 31 is formed at the rear end surface
213 of the rotary shaft 21 in the rear cylinder block 12 and is
open to the communication chamber 53 in the rear housing 14.
[0062] A piston 56 is inserted in the inner space 411. A rod 57 is
formed integrally with the piston 56. The plate 55 is fixed to the
end of the rod 57. A ring-shaped permanent magnet 58 is fittedly
inserted in the partition wall 54 so as to surround the valve hole
541. The permanent magnet 58 has the front and rear surfaces, and a
planar valve seat 581 is formed in the front surface of the
permanent magnet 58 adjacent to the communication chamber 53. The
plate 55 comes into contact with the valve seat 581 for closing the
valve hole 541, and moved apart from the valve seat 581 for opening
the valve hole 541. A sealing surface 551 of the plate 55 facing
the valve seat 581 is formed of a planar shape. In other words,
when the valve hole 541 is closed by the plate 55, the sealing
surface 551 of the plate 55 is in surface contact with the valve
seat 581. The piston 56, the rod 57 and the plate 55 constitute a
valve body 59 for opening and closing the valve hole 541. The valve
body 59 defines a pressure chamber 412 in the inner space 411.
[0063] A return spring 60 is interposed between the piston 56 and
the partition wall 54. The return spring 60 urges the piston 56 in
the direction to push the piston 56 into the inner space 411. In
FIG. 6B, the valve body 59 is in a connecting position connecting
the communication chamber 53 to the suction chamber 142 by opening
the valve hole 541. In FIG. 6A, the valve body 59 is in a
disconnecting position disconnecting the communication chamber 53
from the suction chamber 142 by closing the valve hole 541. The
return spring 60 urges the valve body 59 in the direction from the
connecting position toward the disconnecting position.
[0064] Plural restricting members 552 protrude from the front
surface of the plate 55 facing the end surface 213 of the rotary
shaft 21. The restricting members 552 come into contact with the
rear end of a cylindrical portion 123 protruding from an end
surface 122 of the rear cylinder block 12, and are moved away from
the rear end of the cylindrical portion 123. In a state where the
valve body 59 is in the connecting position as shown in FIG. 6B,
the restricting members 552 are in contact with the rear end of the
cylindrical portion 123. In a state where the valve body 59 is in
the disconnecting position as shown in FIG. 6A, the restricting
members 552 are spaced apart from the rear end of the cylindrical
portion 123.
[0065] When the operation of the compressor 10 is stopped, the
valve body 59 is located in the disconnecting position as shown in
FIG. 6A due to the spring force of the return spring 60. In this
state, the refrigerant in the suction chamber 142 does not flow
into the communication chamber 53. When the compressor 10 is
started, the refrigerant in the in-shaft passage 31 and the
communication chamber 53 is introduced into the compression
chambers 271 (shown in FIG. 1) and 281. Due to the suction motion,
the pressures in the in-shaft passage 31 and the communication
chamber 53 decrease. That is, the pressures in the in-shaft passage
31 and the communication chamber 53 become lower than the pressure
in the suction chamber 142. Thereby the valve body 59 is in the
connecting position as shown in FIG. 6B, and the refrigerant in the
suction chamber 142 flows into the compression chambers 271 (as
shown in FIG. 1) and 281 through the valve hole 541, the
communication chamber 53 and the in-shaft passage 31.
[0066] The valve body 59, the return spring 60, and the permanent
magnet 58 constitute a shifting device 52A. The shifting device 52A
shifts between a connecting state and a disconnecting state. In the
connecting state, the outlets 312, 313 of the supply passage are
connected to the suction chamber 142 (the suction pressure region)
in the compressor 10. In the disconnecting state, the outlets 312,
313 of the supply passage are disconnected from the suction chamber
142.
[0067] When the valve body 59 is in the disconnecting position, the
plate 55 formed of magnetic material is stuck to the permanent
magnet 58. Thereby the shock absorbing effect at the start of the
compressor 10 is highly obtained in the second preferred
embodiment. Further, since the volume of the communication chamber
53 which accommodates the plate 55 is reduced, similar to the first
embodiment, the shock absorbing effect is high.
[0068] The following will describe a third embodiment of the
present invention with reference to FIGS. 7A and 7B. The same
reference numerals denote the identical components to those in the
first preferred embodiment.
[0069] A piston 61 is slidably fitted in the cylindrical portion
41. The piston 61 defines the pressure chamber 412 in the inner
space 411. The piston 61 is attracted by the permanent magnet 48
fixed on the inner wall surface 401 of the base portion 40,
however, the piston 61 is formed not so as to be in contact with
the permanent magnet 48.
[0070] A rod 62 is connected to the piston 61. The rod 62 is
inserted in an in-shaft passage 31A. The in-shaft passage 31A
includes a small-diameter passage 314 and a large-diameter passage
315. A disk 63 is fixed to the front end of the rod 62 in the
small-diameter passage 314. A cylindrical body 64 with a circular
cross-section is fixed to the rod 62 in the large-diameter passage
315.
[0071] The disk 63 is fitted in the small-diameter passage 314 in
such a manner that the disk 63 is slidable in the direction of the
rotary axis 210 of the rotary shaft 21. The cylindrical body 64 is
fitted in the large-diameter passage 315 in such a manner that the
cylindrical body 64 is slidable in the direction of the rotary axis
210 of the rotary shaft 21, and that the outlet 313 is to be opened
and closed. Part of the in-shaft passage 31A between the disk 63
and the cylindrical body 64 communicates with part of the in-shaft
passage 31A between the inlet 311 and the cylindrical body 64
through inner space of the cylindrical body 64.
[0072] As shown in FIG. 7B, when the cylindrical body 64 is in a
position to close the outlet 313, the disk 63 is located rearward
of the outlet 312 in the in-shaft passage 31A. In this state, the
refrigerant in the in-shaft passage 31A does not flow into the
compression chamber 271 through the outlet 312. As shown in FIG.
7A, when the cylindrical body 64 is in a position to open the
outlet 313, the disk 63 is located frontward of the outlet 312 in
the in-shaft passage 31A. In this state, the refrigerant in the
in-shaft passage 31A flows into the compression chamber 271 through
the outlet 312.
[0073] A step 316 is formed between the small-diameter passage 314
and the large-diameter passage 315. A return spring 65 is
interposed between the step 316 and the cylindrical body 64. The
return spring 65 urges the disk 63, the cylindrical body 64, the
rod 62 and the piston 61 altogether in the direction toward the
pressure chamber 412 so as to push the piston 61 into the inner
space 411.
[0074] When the compressor 10 is stopped, the disk 63 and the
cylindrical body 64 are maintained at the disconnecting position as
shown in FIG. 7B by the spring force of the return spring 65. In
this state, the piston 61 is slightly apart from the permanent
magnet 48.
[0075] When the compressor 10 is started, the refrigerant in a
space 317 (a part of the in-shaft passage 31A) defined by the disk
63 and the front end of the in-shaft passage 31A is introduced into
the compression chamber 271, and the pressure in the space 317
decreases. Thereby the disk 63 and the cylindrical body 64 are
moved from the disconnecting position as shown in FIG. 7B toward
the connecting position as shown in FIG. 7A to overcome the spring
force of the spring 65. When the compressor 10 is stopped, the disk
63 and the cylindrical body 64 are returned to the disconnecting
position as shown in FIG. 7B by the spring force of the return
spring 65. Thus, the disk 63 and the cylindrical body 64 serve to
disconnect the outlets 312, 313 of the supply passage from the
suction chamber 142. The disk 63, the cylindrical body 64, the rod
62, and the piston 61 constitute a valve body which defines the
pressure chamber 412 in the inner space 411.
[0076] The valve body is moved between the connecting position and
the disconnecting position in accordance with the pressure in the
space 317 (a part of the in-shaft passage 31A, or the supply
passage) which corresponds to the operated state and stopped state
of the compressor 10. In the connecting position, the outlets 312,
313 of the supply passage are connected to the suction chamber 142
(the suction pressure region) in the compressor 10. In the
disconnecting position, the outlets 312, 313 of the supply passage
are disconnected from the suction chamber 142. The valve body, the
return spring 65, and the permanent magnet 48 constitute a shifting
device 52B. The shifting device 52B shifts between a connecting
state and a disconnecting state. In the connecting state, the
outlets 312, 313 of the supply passage are connected to the suction
chamber 142 (suction pressure region) in the compressor 10. In the
disconnecting state, the outlets 312, 313 of the supply passage are
disconnected from the suction chamber 142.
[0077] According to the third preferred embodiment, the similar
effects as the first preferred embodiment are obtained.
Specifically, the third embodiment is more effective than the first
and the second embodiments in absorbing the shock at the start of
the compressor 10. That is because the refrigerant which is to be
introduced into the compression chambers 271, 281 is only in the
space 317, outlets 312, 313, and communication passages 32, 33,
when the disk 63 and the cylindrical body 64 are in the
disconnecting position.
[0078] The following will describe a fourth preferred embodiment of
the present invention with reference to FIGS. 8A, 8B. The same
reference numerals denote the identical components to those in the
first preferred embodiment. A permanent magnet 66 is fixed to the
piston member 43 of the valve body 42, and a joint plate 67 formed
of magnetic material is fixed to the base portion 40.
[0079] When the compressor 10 is stopped, the valve body 42 is
maintained in the disconnecting position by the spring force of the
return spring 47 as shown in FIG. 8A. In this state, the permanent
magnet 66 is stuck to the joint plate 67 by the magnetic force.
[0080] When the compressor 10 is started, the valve body 42 is
moved from the disconnecting position as shown in FIG. 8A to the
connecting position as shown in FIG. 8B by overcoming the spring
force of the return spring 47 and the attracting force due to the
magnetic force of the permanent magnet 66. The valve body 42, the
return spring 47, the permanent magnet 66, and the joint plate 67
constitute a shifting device 52C which shifts between a connecting
state and a disconnecting state. In the connecting state, the
outlets 312, 313 of the supply passage are connected to the suction
chamber 142 (the suction pressure region) in the compressor 10. In
the disconnecting state, the outlets 312, 313 of the supply passage
are disconnected from the suction chamber 142.
[0081] According to the fourth preferred embodiment, the similar
effects are obtained as the first preferred embodiment.
[0082] The following will describe a fifth preferred embodiment of
the present invention with reference to FIG. 9. The same reference
numerals denote the identical components to those in the first
preferred embodiment.
[0083] A piston type compressor 10A is a fixed displacement type
and includes a cylinder block 12, a front housing 13, and a rear
housing 14 so as to form a compressor housing assembly. A crank
chamber 24 is defined in the cylinder block 12 and the front
housing 13 so as to accommodate a swash plate 23. Single-headed
pistons 68 are engaged with the swash plate 23. The single-headed
pistons 68 are reciprocated in cylinder bores 28 in accordance with
the rotation of the swash plate 23. A rotary valve 36 is formed in
a rotary shaft 21 at a position corresponding to the cylinder block
12. A valve body 42 and a permanent magnet 48 are provided in the
rear housing 14.
[0084] According to the fifth preferred embodiment, the similar
effects are obtained as the first preferred embodiment.
[0085] The present invention is not limited to the above-described
embodiments, but may be modified into the following alternative
embodiments.
[0086] The first rotary valve 35 and the second rotary valve 36 may
be formed independently from the rotary shaft 21.
[0087] In the first embodiment, a ring-shaped permanent magnet may
be fitted to the inner circumferential surface of the cylindrical
portion 41.
[0088] In the first embodiment, only the piston member 43 of the
valve body 42 may be formed of magnetic material.
[0089] Therefore, the present examples and embodiments are to be
considered as illustrative and not restrictive, and the invention
is not to be limited to the details given herein but may be
modified within the scope of the appended claims.
* * * * *