U.S. patent application number 11/293019 was filed with the patent office on 2006-07-27 for displacement control valve for variable displacement compressor.
Invention is credited to Yuji Hashimoto, Tatsuya Hirose, Kazutaka Oda, Masataka Taniue, Satoshi Umemura.
Application Number | 20060165534 11/293019 |
Document ID | / |
Family ID | 36580368 |
Filed Date | 2006-07-27 |
United States Patent
Application |
20060165534 |
Kind Code |
A1 |
Umemura; Satoshi ; et
al. |
July 27, 2006 |
Displacement control valve for variable displacement compressor
Abstract
A displacement control valve for a variable displacement
compressor includes a valve hole partially forming a supply passage
or a bleed passage of the compressor and a valve body having a
cross-sectional area changed portion that is movable into and out
of the valve hole. The cross-sectional area changed portion has a
minimum cross-sectional area portion and a maximum cross-sectional
area portion. The cross-sectional area changed portion is shaped so
that the cross-sectional area of the cross-sectional area changed
portion increases from the minimum cross-sectional area portion to
the maximum cross-sectional area portion. The minimum
cross-sectional area portion initially enters into the valve hole
when the cross-sectional area changed portion is moved into the
valve hole. The maximum cross-sectional area portion is movable
into the valve hole. The valve hole is closed when the maximum
cross-sectional area portion is positioned in the valve hole.
Inventors: |
Umemura; Satoshi;
(Kariya-shi, JP) ; Hirose; Tatsuya; (Kariya-shi,
JP) ; Hashimoto; Yuji; (Kariya-shi, JP) ; Oda;
Kazutaka; (Kariya-shi, JP) ; Taniue; Masataka;
(Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
36580368 |
Appl. No.: |
11/293019 |
Filed: |
December 2, 2005 |
Current U.S.
Class: |
417/222.2 ;
62/228.3 |
Current CPC
Class: |
F04B 2027/1854 20130101;
F04B 2205/05 20130101; F04B 2027/185 20130101; F04B 27/1804
20130101; F04B 2205/08 20130101; F04B 2027/1827 20130101 |
Class at
Publication: |
417/222.2 ;
062/228.3 |
International
Class: |
F04B 1/26 20060101
F04B001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2004 |
JP |
2004-366558 |
Claims
1. A displacement control valve used for a variable displacement
compressor that adjusts a pressure in a pressure control chamber by
introducing a refrigerant in a discharge pressure region into the
pressure control chamber through a supply passage and releasing the
refrigerant in the pressure control chamber to a suction pressure
region through a bleed passage, thereby controlling displacement of
the compressor, the displacement control valve comprising: a valve
hole partially forming the supply passage or the bleed passage; and
a valve body having a cross-sectional area changed portion that is
movable into and out of the valve hole, wherein the cross-sectional
area changed portion has a minimum cross-sectional area portion and
a maximum cross-sectional area portion, wherein the cross-sectional
area changed portion is shaped so that a cross-sectional area of
the cross-sectional area changed portion increases from the minimum
cross-sectional area portion to the maximum cross-sectional area
portion, wherein the minimum cross-sectional area portion initially
enters into the valve hole when the cross-sectional area changed
portion is moved into the valve hole, wherein the maximum
cross-sectional area portion is movable into the valve hole, and
wherein the valve hole is closed when the maximum cross-sectional
area portion is positioned in the valve hole.
2. The displacement control valve according to claim 1, wherein the
cross-sectional area changed portion has a conical peripheral
surface.
3. The displacement control valve according to claim 1, wherein a
minute clearance is formed between the maximum cross-sectional area
portion and a circumferential wall surface of the valve hole when
the maximum cross-sectional area portion is positioned in the valve
hole for allowing the refrigerant to flow therethrough
slightly.
4. The displacement control valve according to claim 1, wherein the
valve hole is a part of the supply passage, and wherein the
displacement control valve is adapted to open the valve hole when
the compressor is at its minimum displacement.
5. The displacement control valve according to claim 1, wherein the
valve hole is a part of the bleed passage, and wherein the
displacement control valve is adapted to close the valve hole when
the compressor is at its minimum displacement.
6. The displacement control valve according to claim 1, wherein the
cross-sectional area changed portion is tapered toward the valve
hole.
7. The displacement control valve according to claim 1, further
comprising a pressure sensing means operable to sense a pressure of
a first point in the discharge pressure region and a pressure of a
second point in the discharge pressure region and to regulate a
position of the valve body based on pressure difference between the
first and second points.
8. The displacement control valve according to claim 7, wherein the
pressure sensing means includes a first pressure sensing chamber, a
second pressure sensing chamber and a displacement body that
divides the first and second pressure sensing chambers, wherein the
valve body is connected to the displacement body, wherein the
pressure of the first point is introduced into the first pressure
sensing chamber, and wherein the pressure of the second point is
introduced into the second pressure sensing chamber.
9. The displacement control valve according to claim 8, wherein the
displacement body is a bellows.
10. The displacement control valve according to claim 1, further
comprising a rod connected to the valve body, wherein the
displacement control valve is formed so that the rod receives the
pressure in the discharge pressure region and the pressure in the
pressure control chamber, and wherein a load resulting from the
pressure in the discharge pressure region and a load resulting from
the pressure in the pressure control chamber act against each other
through the rod.
11. The displacement control valve according to claim 1, further
comprising a rod connected to the valve body, wherein the
displacement control valve is formed so that the rod receives the
pressure in the discharge pressure region and the pressure in the
suction pressure region, and wherein a load resulting from the
pressure in the discharge pressure region and a load resulting from
the pressure in the suction pressure region act against each other
through the rod.
12. The displacement control valve according to claim 1, further
comprising a solenoid for generating an electromagnetic force
acting on the valve body.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a displacement control
valve used for a variable displacement compressor that adjusts the
pressure in a pressure control chamber by introducing refrigerant
in the discharge pressure region of the compressor into the
pressure control chamber through a supply passage and releasing the
refrigerant in the pressure control chamber to the suction pressure
region of the compressor through a bleed passage, thereby to
control displacement of the compressor.
[0002] In a variable displacement compressor having a pressure
control chamber that accommodates therein a swash plate whose
inclination angle is variable, the inclination angle of the swash
plate decreases as the pressure in the pressure control chamber
rises. This decrease of the inclination angle increases the stroke
of a piston thereby to increase the displacement of the compressor.
On the other hand, the inclination angle of the swash plate
increases as the pressure in the pressure control chamber falls.
This increase of the inclination angle decreases the stroke of the
piston thereby to decrease the displacement of the compressor.
[0003] Unexamined Japanese Patent Publication No. 2001-349278
discloses a displacement control valve having a valve body which is
operable to open and close a supply passage through which a
refrigerant gas in the discharge pressure region of the compressor
is introduced into a crank chamber (or pressure control chamber).
The valve body has a tapered portion which is movable to be brought
into contact with a valve seat thereby to close a valve hole. When
the valve body is moved or shifted in the direction that opens the
valve hole, the amount of the refrigerant flowing from the
discharge pressure chamber to the crank chamber increases. Thus,
the pressure in the crank chamber rises, thereby decreasing the
displacement of the compressor. On the other hand, when the valve
body is shifted in the direction that closes the valve hole, the
amount of the refrigerant flowing from the discharge pressure
chamber to the crank chamber decreases. Thus, the pressure in the
crank chamber falls, thereby increasing the displacement of the
compressor.
[0004] When the valve body of the above displacement control valve
is shifted in the direction for closing the valve hole, the tapered
portion of the valve body is moved with the minimum-diameter
portion thereof entering into the valve hole, until the tapered
portion of the valve body is brought into contact at any
intermediate-diameter portion thereof with the valve seat or the
edge of opening of the valve hole. Since the maximum-diameter
portion of the tapered portion of the valve body is larger than the
inner diameter of the valve hole, the movement of the valve body is
stopped before the maximum-diameter portion of the tapered portion
reaches the valve seat. When the valve hole is opened, the
refrigerant gas in the discharge pressure region flows past the
tapered portion of the valve body in the direction from the minimum
diameter portion to the maximum diameter portion. Thus, the tapered
portion of the valve body is subjected to a pressure which is
substantially the same as the discharge pressure of the compressor
and acts on the valve body in the direction which causes an
increase of the opening of the valve hole. On the other hand, the
pressure in the crank chamber (or control pressure) acts on the
valve body in the direction opposite to the above pressure.
[0005] The pressure of refrigerant gas present adjacent to the part
of the valve body which protrudes radially outward beyond the inner
peripheral surface of the valve hole as seen in the moving
direction (or the axial direction) of the valve body, or whose
diameter is greater than the inner diameter of the valve hole, is
varied depending on the opening degree of the valve hole when the
valve hole is opened. Namely, the pressure acting on the above
protruding part of the tapered portion is varied according to the
opening degree of the valve hole. Such pressure varying with the
valve opening will affect the difference of pressures acting on the
valve body in opposing directions and hence the accuracy of
displacement controlling of the compressor.
[0006] The present invention is directed to a displacement control
valve that contributes to improvement in controllability of the
displacement of a variable displacement compressor.
SUMMARY OF THE INVENTION
[0007] According to the present invention, a displacement control
valve is used for a variable displacement compressor that adjusts a
pressure in a pressure control chamber by introducing a refrigerant
in a discharge pressure region into the pressure control chamber
through a supply passage and releasing the refrigerant in the
pressure control chamber to a suction pressure region through a
bleed passage, thereby controlling displacement of the compressor.
The displacement control valve includes a valve hole and a valve
body. The valve hole partially forms the supply passage or the
bleed passage. The valve body has a cross-sectional area changed
portion that is movable into and out of the valve hole. The
cross-sectional area changed portion has a minimum cross-sectional
area portion and a maximum cross-sectional area portion. The
cross-sectional area changed portion is shaped so that a
cross-sectional area of the cross-sectional area changed portion
increases from the minimum cross-sectional area portion to the
maximum cross-sectional area portion. The minimum cross-sectional
area portion initially enters into the valve hole when the
cross-sectional area changed portion is moved into the valve hole.
The maximum cross-sectional area portion is movable into the valve
hole. The valve hole is closed when the maximum cross-sectional
area portion is positioned in the valve hole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] 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:
[0009] FIG. 1A is a longitudinal cross-sectional view of a
compressor of a first preferred embodiment according to the present
invention;
[0010] FIG. 1B is a cross-sectional view of a hinge mechanism of
the compressor of the first preferred embodiment;
[0011] FIG. 2A is a cross-sectional view of a displacement control
valve of the first preferred embodiment;
[0012] FIG. 2B is a partially enlarged cross-sectional view of the
displacement control valve of the first preferred embodiment when a
valve hole is blocked;
[0013] FIG. 3 is a partially enlarged cross-sectional view of the
displacement control valve of the first preferred embodiment when
the valve hole is opened;
[0014] FIG. 4 is a partially enlarged cross-sectional view of the
displacement control valve of the first preferred embodiment when
the valve hole is fully opened;
[0015] FIG. 5 is a cross-sectional view of a displacement control
valve of a second preferred embodiment according to the present
invention;
[0016] FIG. 6 is a cross-sectional view of a displacement control
valve of a third preferred embodiment according to the present
invention; and
[0017] FIG. 7 is a cross-sectional view of a displacement control
valve of a fourth preferred embodiment according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The following will describe a first preferred embodiment
according to the present invention with reference to FIGS. 1A
through 4. Referring to FIG. 1A, a variable displacement compressor
10 has a housing assembly which includes a cylinder block 11, a
front housing 12 and a rear housing 13. The front housing 12 is
connected to the front end (the left end as seen in FIG. 1) of the
cylinder block 11. The rear housing 13 is connected to the rear end
(the right end as seen in FIG. 1) of the cylinder block 11 through
a valve plate 14, valve plate forming plates 15 and 16 and a
retainer forming plate 17.
[0019] The front housing 12 and the cylinder block 11 cooperate to
define therein a pressure control chamber 121 through which a
rotary shaft 18 extends. The rotary shaft 18 is supported by the
front housing 12 and the cylinder block 11 via radial bearings 19
and 20. The rotary shaft 18 extends out of the front housing 12 and
is driven to rotate by a vehicle engine E as an external drive
source via an electromagnetic clutch (not shown).
[0020] A lug plate 21 is secured to the rotary shaft 18. A swash
plate 22 is supported by the rotary shaft 18 in such a way that it
is slidable in the axial direction of the rotary shaft 18 and
inclinable relative to the axis of the rotary shaft 18. A hinge
mechanism 23 is provided between the swash plate 22 and the lug
plate 21 for allowing the swash plate 22 to incline relative to the
lug plate 21 and transmitting the rotation of the rotary shaft 18
to the swash plate 22. As shown in FIG. 1B, the hinge mechanism 23
includes a pair of arms 212 and 213 extending from the lug plate 21
toward the swash plate 22 and a pair of projections 221 and 222
extending from the swash plate 22 toward the lug plate 21. The
projections 221 and 222 are inserted in a recess 214 formed between
the paired arms 212 and 213 and movable in the recess 214. The
bottom of the recess 214 provides a cam surface 211 on which the
ends of the projections 221 and 222 are slidable. The
above-described arrangement of the paired arms 212 and 213, the
paired projections 221 and 222 and the cam surface 211 permits the
swash plate 22 to incline relative to the axis of the rotary shaft
18 and also to rotate with the rotary shaft 18. The inclination of
the swash plate 22 is guided with the projections 221 and 222
sliding on the cam surface 211 and the swash plate 22 sliding on
the rotary shaft 18.
[0021] As the center portion of the swash plate 22 moves toward the
lug plate 21, the inclination angle of the swash plate 22
increases. The maximum inclination of the swash plate 22, which is
shown by solid line in FIG. 1A, is restricted by contact of the
swash plate 22 with the lug plate 21. The minimum inclination of
the swash plate is shown by chain double-dashed line in FIG.
1A.
[0022] The cylinder block 11 has formed therethrough a plurality of
cylinder bores 111 in which pistons 24 are received. The rotation
of the swash plate 22 is converted into the reciprocating movement
of the piston 24 via a pair of shoes 25.
[0023] The rear housing 13 has formed therein a suction chamber 131
as a suction pressure region and a discharge chamber 132 as a
discharge pressure region. A suction port 141 is formed in the
valve plate 14, the valve plate forming plate 16 and the retainer
forming plate 17, respectively. A discharge port 142 is formed in
the valve plate 14 and the valve forming palate 15, respectively.
The valve forming plate 15 has formed therein a suction valve 151,
and the valve forming plate 16 has formed therein a discharge valve
161. As the piston 24 moves leftward in its corresponding cylinder
bore 111 as seen in FIG. 1A, a refrigerant gas is drawn from the
suction chamber 131 into the cylinder bore 111 through the suction
port 141 while pushing open the suction valve 151. As the piston 24
moves rightward in the cylinder bore as seen in FIG. 1A, on the
other hand, the refrigerant gas is compressed and discharged out of
the cylinder bore 111 into the discharge chamber 132 through the
discharge port 142 pushing open the discharge valve 161. The
discharge valve 161 then comes into contact with a retainer 171
formed in the retainer forming plate 17 thereby to restrict the
opening degree of the discharge valve 161.
[0024] The rear housing 13 has formed therein a suction passage 26
through which the refrigerant gas before compression is introduced
into the suction chamber 131. The rear housing 13 has also formed
therein a discharge passage 27 through which the compressed
refrigerant gas is delivered out of the discharge chamber 132. The
suction passage 26 and the discharge passage 27 are connected by an
external refrigerant circuit 28 in which a condenser 29 for
removing heat from the refrigerant gas, an expansion valve 30 and
an evaporator 31 for allowing the refrigerant to absorb the ambient
heat are disposed. The expansion valve 30 is operable to regulate
the flow rate of the refrigerant according to variation in the
temperature of the refrigerant gas at the outlet of the evaporator
31. A throttle 281 is disposed in the external refrigerant circuit
28 between the discharge passage 27 and the condenser 29. The part
of the external refrigerant circuit 28 between the discharge
passage 27 and the throttle 281 is referred to as an external
refrigerant circuit 28A, and the part of the external refrigerant
circuit 28 between the throttle 281 and the condenser 29 is
referred to as an external refrigerant circuit 28B.
[0025] An electromagnetic displacement control valve 32 is
installed in the rear housing 13. As shown in FIG. 2A, the
displacement control valve 32 has a solenoid 34 including a fixed
core 35, a coil 36 and a movable core 37. Supplying an electric
current to the coil 34, the fixed core 35 is magnetized to attract
the movable core 37 thereto. Operation of the solenoid 34 is
controlled by a controller C (shown in FIG. 1A) with electric
current. In this preferred embodiment, the solenoid 34 is
controlled by the controller C with duty ratio. A transmitting rod
38 is secured to the movable core 37.
[0026] The displacement control valve 32 includes a valve housing
39 which has a valve hole forming wall 40. The valve hole forming
wall 40 has formed therein a valve hole 41 having a circumferential
wall surface 411 and a uniform diameter. A chamber 42 is formed
between the valve hole forming wall 40 and the movable core 37 in
the valve housing 39. The valve hole 41 communicates with the
chamber 42 which in turn communicates with the pressure control
camber 121 through a passage 43 formed in the rear housing 13 and
the cylinder bore 11. Furthermore, the chamber 42 communicates with
a clearance 59 formed between the movable core 37 and the fixed
core 35 through a passage 351. The chamber 42 also communicates
with a back pressure space 60 formed behind the movable core 37
through the passage 351 and a passage 371. Namely, the pressure in
the pressure control chamber 121 prevails in the back pressure
space 60 through the passage 43, the chamber 42, and the passages
351 and 371.
[0027] Referring to FIG. 2B, the transmitting rod 38 has a valve
body 44 formed integrally therewith. The valve body 44 includes a
cylindrical portion 441 and a tapered portion 442. The tapered
portion 442 is shaped so that its diameter decreases from the
chamber 42 toward the valve hole 441, or is tapered toward the
valve hole 441. The tapered portion 442 has its maximum-diameter
portion 443 at the boundary between the cylindrical portion 441 and
the tapered portion 442 and its minimum-diameter portion 444 at the
boundary between the tapered portion 442 and the cylindrical
reduced diameter portion 381 of the transmitting rod 38. Namely,
the tapered portion 442 is shaped so that its cross sectional area
increases from the minimum-diameter portion 444 as a minimum
cross-sectional area portion toward the maximum-diameter portion
443 as a maximum cross-sectional area portion.
[0028] The cylindrical portion 441 of the valve body 44 is slidable
in the valve hole 41. With part of the cylindrical portion 441 (or
the maximum-diameter portion 443) positioned in the valve hole 41
as shown in FIG. 2A, a minute clearance is formed between the inner
circumferential wall surface 411 of the valve hole 41 and the
cylindrical portion 441 of the valve body 44. Due to the presence
of this minute clearance, the cylindrical portion 441 is slidable
in the valve hole 41. This minute clearance also allows the
refrigerant gas in the valve hole 41 to flow slightly therethrough.
To be more specific, with part of the cylindrical portion 441 (or
the maximum-diameter portion 443) positioned in the valve hole 41,
the valve hole 41 is not closed completely, but loosely so as to
allow a slight flow of the refrigerant gas therethrough.
[0029] As shown in FIG. 2A, the transmitting rod 38 in the chamber
42 is provided with a spring seat 52 and a spring 53 is installed
on the valve body 44 between the spring seat 52 and the valve hole
forming wall 40. The transmitting rod 38 is urged by the spring
force of the spring 53 in the direction which causes the movable
core 37 to move away from the fixed core 35.
[0030] A first pressure sensing chamber 45 and a second pressure
sensing chamber 46 are defined in the valve housing 39 and divided
by a bellows 47 as a displacement body. The bellows 47 has its
fixed end connected to an end wall 48 of the valve housing 39 and
the opposite movable end connected to the reduced diameter portion
381 of the transmitting rod 38. The transmitting rod 38 is movable
in conjunction with the bellows 47.
[0031] The first pressure sensing chamber 45 communicates with the
external refrigerant circuit 28A upstream of the throttle 281
through a pressure introducing passage 49, and the second pressure
sensing chamber 46 communicates with the external refrigerant
circuit 28B downstream of the throttle 281 through a pressure
introducing passage 50. The pressure in the external refrigerant
circuit 28A upstream of the throttle 281 is introduced into the
first pressure sensing chamber 45, and the pressure in the external
refrigerant circuit 28B downstream of the throttle 281 and upstream
of the condenser 29 is introduced into the second pressure sensing
chamber 46. The pressure in the first pressure sensing chamber 45
and the pressure in the second pressure sensing chamber 46 act
against each other through the bellows 47.
[0032] When there is a flow of the refrigerant gas in the external
refrigerant circuits 28A and 28B, the pressure of refrigerant gas
in the external refrigerant circuit 28A upstream of the throttle
281 is larger than that in the external refrigerant circuit 28B
downstream of the throttle 281 and upstream of the condenser 29. As
the flow rate of the refrigerant gas in the external refrigerant
circuits 28A and 28B (or in the discharge pressure region)
increases, the difference of pressures between the upstream and
downstream of the throttle 281 increases, so that the pressure
difference between the first and second pressure sensing chambers
45 and 46 increases. On the other hand, as the flow rate of the
refrigerant gas in the external refrigerant circuits 28A and 28B
(or in discharge pressure region) decreases, the pressure
difference between the upstream and downstream of the throttle 281
decreases, so that the pressure difference between the first and
second pressure sensing chambers 45 and 46 decreases. The pressure
difference between the first and second pressure sensing chambers
45 and 46 produces a force urging the transmitting rod 38 in the
direction from the valve hole 41 toward the chamber 42, or downward
as seen in FIG. 2A.
[0033] The first and second pressure sensing chambers 45 and 46 and
the bellows 47 constitute a pressure sensing means 51 of the
present invention for sensing the pressure difference between the
external refrigerant circuit 28A upstream of the throttle 281 and
the external refrigerant circuit 28B downstream of the throttle 281
and upstream of the condenser 29. The opening and closing operation
of the valve hole 41 depends on the balance among various forces
such as the electromagnetic force generated by the solenoid 34, the
urging force resulting from the pressure in the back pressure space
60 (or control pressure) and acting on the transmitting rod 38 in
the direction that closes the valve hole 41, the spring force of
the spring 53 and the urging force of the pressure sensing means
51.
[0034] The pressure sensing means 51 is operable to sense the
pressure at a first point (or the external refrigerant circuit 28A)
in the discharge pressure region (or the external refrigerant
circuits 28A and 28B) and the pressure at a second point (or the
external refrigerant circuit 28B) in the discharge pressure region
and to adjust the position of the transmitting rod 38 or the valve
body 44 based on the difference of pressures between the first and
second points.
[0035] As shown in FIG. 1A, the controller C, which controls the
solenoid 34 of the displacement control valve 32 with electric
current (duty ratio), supplies electric current to the solenoid 34
while the air conditioner switch 54 is turned on. With the air
conditioner switch 54 turned off, the controller C stops supplying
the electric current to the solenoid 34. A room temperature setting
device 55 and a room temperature detector 56 are electrically
connected to the controller C. With the air conditioner switch
turned on, the controller C controls the electric current supplied
to the solenoid 34 based on the difference between a target
temperature set by the room temperature setting device 55 and a
temperature then detected by the room temperature detector 56. As
the duty ratio is increased, the transmitting rod 38 (the valve
body 44) moves in the direction from the chamber 42 toward the
valve hole 41, or upward as seen in FIG. 2A.
[0036] When the maximum-diameter portion 443 of the valve body 44
is moved out of the valve hole 41 to open the valve hole 41 as
shown in FIGS. 3 and 4, part of the refrigerant gas in the external
refrigerant circuit 28B flows into the pressure control chamber 121
through a supply passage 57 which includes the pressure introducing
passage 50, the second pressure sensing chamber 46, the valve hole
41, the chamber 42 and the passage 43. When the maximum-diameter
portion 443 of the valve body 44 is moved into the valve hole 41
thereby to close the valve hole 41 as shown in FIG. 2B, the
refrigerant flow from the external refrigerant circuit 28B through
the supply passage 57 to the pressure control chamber 121 is
blocked.
[0037] As shown in FIG. 1A, the pressure control chamber 121
communicates with the suction chamber 131 through a bleed passage
58 that is formed in the cylinder block 11, the valve forming plate
15, the valve plate 14, the valve forming plate 16 and the retainer
forming plate 17. Thus, the refrigerant gas in the pressure control
chamber 121 can flow out thereof into the suction chamber 131
through the bleed passage 58. The pressure in the pressure control
chamber 121 is varied or adjusted by controlling the flow of
refrigerant gas flowing from the external refrigerant circuit 28B
into the pressure control chamber 121 through the supply passage 57
and the flow of refrigerant gas flowing from the pressure control
chamber 121 into the suction chamber 131 through the bleed passage
58.
[0038] In FIG. 2A, the maximum amount of the electric current is
supplied to the solenoid 34 and the valve hole 41 is closed,
accordingly. In this state, the amount of the refrigerant gas
flowing from the external refrigerant circuit 28B through the
supply passage 57 into the pressure control chamber 121 is
substantially zero. The refrigerant gas in the pressure control
chamber 121 then flows out into the suction chamber 131 through the
bleed passage 58. Thus, the pressure in the pressure control
chamber 121 falls, so that the swash plate 22 is tilted to its
maximum angle position and the piston 14 is moved for its maximum
length of stroke, accordingly, with the result that the
displacement of the compressor 10 becomes the maximum.
[0039] In FIG. 3, the amount of electric current supplied to the
solenoid 34 is less than the maximum and the valve hole 41 is
opened. In this state, the refrigerant gas in the external
refrigerant circuit 28B flows into the pressure control chamber 121
through the supply passage 57, thereby increasing the pressure in
the pressure control chamber 121. Thus, the inclination angle of
the swash plate 22 decreases from the maximum angle.
[0040] In FIG. 4, the electric current supply to the solenoid 34 is
stopped and, therefore, the valve hole 41 is fully opened. In this
state, the amount of the refrigerant gas flowing from the external
refrigerant circuit 28B through the supply passage 57 into the
pressure control chamber 121 is increased thereby to further
increase the pressure in the pressure control chamber 121. Thus,
the inclination angle of the swash plate 22 becomes the minimum. As
apparent from the foregoing description, the displacement control
valve 32 is of a normally-opened type according to which the valve
hole 41 is opened when no electric current is supplied to the
solenoid 34.
[0041] The following advantageous effects are obtained according to
the first preferred embodiment.
[0042] (1-1) With the maximum-diameter portion 443 of the tapered
portion 442 positioned out of the valve hole 41, the valve hole 41
is opened. Unlike the displacement control valve of the
aforementioned prior art, no part of the tapered portion 442 of the
valve body 44 protrude radially outward beyond the inner peripheral
surface of the valve hole 41 as seen in the moving direction (or
the axial direction) of the valve body 44.
[0043] Let us assume that part of the tapered portion 442 of the
valve body 44 protrudes radially outward beyond the inner
peripheral surface of the valve hole 41 as seen in the moving
direction of the valve body 44 or that the diameter of the
maximum-diameter portion 443 is greater than the inner diameter of
the valve hole 41. The pressure of refrigerant gas present adjacent
to such imaginary protruding part of the tapered portion 442 (or
the part whose outer diameter is larger than the inner diameter of
the valve hole 41) is varied depending on the opening degree of the
valve hole 41 when the valve hole 41 is opened. Namely, the
pressure acting on the protruding part of the tapered portion 442
is varied according to the opening degree of the valve hole 41.
Such pressure varying with the valve opening will affect the
difference between the pressure acting on the tapered portion 442
(or the pressure that is substantially the same as the discharge
pressure) and the pressure in the back pressure space 60 acting on
the valve body 44 through the transmitting rod 38 (or the control
pressure), with the result that the movement of the valve body 44
(or the transmitting rod 38) becomes unstable, thereby
deteriorating the controllability of the displacement of the
compressor 10. When the valve hole 41 is changed from the closed
state to the opened state, the pressure of the refrigerant gas then
flowing from the valve hole 41 to the chamber 42 suddenly acts on
the protruding part of the tapered portion 442, which may cause
excessive movement of the valve body 44. Namely, since the area of
the tapered portion 442 which receives the pressure of the
refrigerant gas flowing from the valve hole 41 to the chamber 42
rapidly increases, the valve body 44 may move excessively. This
deteriorates the controllability of the displacement of the
compressor 10.
[0044] In the displacement control valve of the above-described
embodiment according to the present invention, no part of the
tapered portion 442 protrudes radially outward beyond the inner
peripheral surface of the valve hole 41 as seen in the moving
direction of the valve body 44. This structure prevents the
difference between the pressure acting on the tapered portion 442
(or the pressure corresponding to the discharge pressure) and the
pressure acting on the valve body 44 from the opposite direction
(or the control pressure) from being changed significantly by
variation in the opening degree of the valve hole 41. As a result,
the controllability of the displacement of the compressor 10 is
improved.
[0045] (1-2) If the cross-sectional area of the valve hole 41 that
forms a part of the supply passage 57 could be changed as desired,
the displacement of the compressor 10 could be controlled
elaborately. The tapered portion 442 having the conical peripheral
surface is advantageous for changing the cross-sectional area of
the valve hole 41 in accordance with the position of the valve body
44 in the valve hole 41.
[0046] (1-3) With the cylindrical portion 441 (the maximum-diameter
portion 443) positioned in the valve hole 41, a minute clearance is
formed between the circumferential wall surface 411 of the valve
hole 41 and the cylindrical portion 441 of the valve body 44. A
small amount of refrigerant gas flows from the second pressure
sensing chamber 46 into the chamber 42 through this minute
clearance. Thus, the pressure in the chamber 42 adjacent to the
valve hole 41 is larger than that in the state where the valve hole
is completely closed by the valve body as in the case of the
Unexamined Japanese Patent Publication No. 2001-349278 where the
refrigerant gas is completely prevented from flowing from the valve
hole to the chamber. Namely, the provision of the minute clearance
between the circumferential wall surface 411 of the valve hole 41
and the cylindrical portion 441 reduces the change of the pressure
difference (or the difference between the pressures acting on the
tapered portion 442 and on the valve body 44 in opposing
directions), which occurs when the maximum-diameter portion 443 is
moved out of the valve hole 41.
[0047] The following will describe a second preferred embodiment of
the present invention with reference to FIG. 5. Like or same parts
or elements are referred to by the same reference numerals as those
which have been used in the first preferred embodiment.
[0048] Referring to FIG. 5, the displacement control valve 32A has
a valve housing 39 that defines therein a discharge pressure
introducing chamber 61. The discharge pressure introducing chamber
61 communicates through a passage 62 with the external refrigerant
circuit 28C that connects the discharge chamber 132 and the
condenser 29. A spring seat 63 and a spring 64 are disposed in the
discharge pressure introducing chamber 61. The spring 64 is
interposed between the spring seat 63 and the end wall 48 of the
valve housing 39, and the reduced diameter portion 381 of the
transmitting rod 38 is connected to the spring seat 63. The spring
64 urges the transmitting rod 38 in the direction from the valve
hole 41 toward the chamber 42, or downward as seen in FIG. 5. The
transmitting rod 38 is also urged by the spring 53 in the same
direction.
[0049] The pressure in the discharge pressure introducing chamber
61 is substantially the same as that in the external refrigerant
circuit 28C as a discharge pressure region (or the discharge
pressure). The pressure in the chamber 42 and the back pressure
space 60 is substantially the same as that in the pressure control
chamber 121 (or the control pressure). The transmitting rod 38
receives the pressure in the discharge pressure introducing chamber
61 at one end thereof on the side of the reduced diameter 381 and
the pressure in the back pressure space 60 (or the control
pressure) at the other end thereof. More specifically, the
transmitting rod 38 receives a load F1 resulting from the pressure
in the back pressure space 60 and determined by multiplying the
cross sectional area of the cylindrical portion 441 of the valve
body 44 by the control pressure. The load F1 acts on the
transmitting rod 38 in the direction from the chamber 42 toward the
valve hole 41, or upward as seen in FIG. 5. The transmitting rod 38
also receives a load F2 resulting from the discharge pressure in
the discharge pressure introducing chamber 61 and determined by
multiplying the cross sectional area of the cylindrical portion 441
by the discharge pressure. The load F2 acts on the transmitting rod
38 in the direction opposite to the load F1. Namely, the load F1
and the load F2 act against each other through the transmitting rod
38. Therefore, the transmitting rod 38 is urged by the load
difference (or F2-F1) in the direction from the valve hole 41
toward the chamber 42, or downward as seen in FIG. 5. The load
difference (F2-F1) acts against the electromagnetic force of the
solenoid 34.
[0050] The opening and closing operation of the valve hole 41
depends on the balance among various forces such as the
electromagnetic force generated by the solenoid 34, the spring
forces of the springs 53 and 64 and the urging force resulting from
the load difference (F2-F1). As the pressure difference between the
discharge pressure and the control pressure increases, the load
difference (F2-F1) becomes large and the transmitting rod 38 moves
downward as seen in FIG. 5, accordingly. On the other hand, as the
pressure difference between the discharge pressure and the control
pressure decreases, the load difference (F2-F1) becomes small, so
that the transmitting rod 38 moves upward as seen in FIG. 5.
[0051] According to the second preferred embodiment, the same
advantageous effects as those in the first preferred embodiment are
obtained and the following additional effect is also obtained.
[0052] (2-1) In the displacement control valve 32A which is formed
so that the pressure in the discharge pressure introducing chamber
61 acts against the pressure in the back pressure space 60 (or the
control pressure) through the transmitting rod 38, the pressure
difference between the discharge pressure and the control pressure
is the object to be controlled. The displacement control valve 32A
is controlled in such a manner that the pressure difference between
the discharge pressure and the control pressure balances with the
electromagnetic force at the solenoid 34. Since the displacement
control valve 32A of FIG. 5 dispenses with the pressure sensing
means 51 using the bellows 47 as in the first preferred embodiment,
the displacement control valve 32A of the second preferred
embodiment is simpler in structure than the displacement control
valve 32 including the pressure sensing means 51.
[0053] The following will describe a third preferred embodiment of
the present invention with reference to FIG. 6. Like or same parts
or elements are referred to by the same reference numerals as those
which have been used in the first preferred embodiment.
[0054] Referring to FIG. 6, the displacement control valve 32B has
a chamber forming housing 65 that has formed therein a suction
pressure introducing chamber 651. The spring 53 is disposed in the
suction pressure introducing chamber 651 and urges the transmitting
rod 38 in the direction from the valve hole 41 toward the chamber
42. The suction pressure introducing chamber 651 communicates with
the suction chamber 131 through a passage 66. The suction pressure
introducing chamber 651 also communicates with the back pressure
space 60 through the passages 351 and 371. The pressure in the
suction chamber 131 (or suction pressure) is introduced into the
back pressure space 60 through the passage 66, the suction pressure
introducing chamber 651 and the passages 351 and 371. Thus, the
back pressure space 60 is a part of the suction pressure
region.
[0055] The transmitting rod 38 receives a load F3 resulting from
the suction pressure in the back pressure space 60 and determined
by multiplying the cross sectional area of the cylindrical portion
441 of the valve body 44 by the suction pressure. The load F3 acts
on the transmitting rod 38 in the direction from the chamber 42
toward the valve hole 41, or upward as seen in FIG. 6. The
transmitting rod 38 also receives the load F2 resulting from the
discharge pressure in the discharge pressure introducing chamber 61
and determined by multiplying the cross sectional area of the
cylindrical portion 441 by the discharge pressure. The load F2 acts
on the transmitting rod 38 in the direction from the valve hole 41
toward the chamber 42, or downward as seen in FIG. 6. Namely, the
load F3 and the load F2 act against each other through the
transmitting rod 38. Therefore, the transmitting rod 38 is urged by
the load difference (or F2-F3) downward as seen in FIG. 6. The load
difference (F2-F3) acts against the electromagnetic force of the
solenoid 34.
[0056] The opening and closing operation of the valve hole 41
depends on the balance among various forces such as the
electromagnetic force generated at the solenoid 34, the spring
forces of the springs 53 and 64 and the urging force resulting from
the load difference (F2-F3). As the pressure difference between the
discharge pressure and the control pressure increases, the load
difference (F2-F3) becomes large and the transmitting rod 38 moves
downward as seen in FIG. 6, accordingly. On the other hand, as the
pressure difference between the discharge pressure and the control
pressure decreases, the load difference (F2-F3) becomes small, so
that the transmitting rod 38 moves upward as seen in FIG. 6.
[0057] According to the third preferred embodiment, the same
advantageous effects as those in the first preferred embodiment are
obtained and the following additional effect is also obtained.
[0058] (3-1) In the displacement control valve 32B which is formed
so that the pressure in the discharge pressure introducing chamber
61 acts against the pressure in the back pressure space 60 (or
suction pressure) through the transmitting rod 38, the pressure
difference between the discharge pressure and the suction pressure
is the object to be controlled. The displacement control valve 32B
is controlled in such a manner that the pressure difference between
the discharge pressure and the suction pressure balances with the
electromagnetic force at the solenoid 34. Since the displacement
control valve 32B of FIG. 6 dispenses with the pressure sensing
means 51 using the bellows 47 as in the first preferred embodiment,
the displacement control valve 32B of the third preferred
embodiment is simpler in structure than the displacement control
valve 32 including the pressure sensing means 51.
[0059] The following will describe a fourth preferred embodiment of
the present invention with reference to FIG. 7. Like or same parts
of elements are referred to by the same reference numerals as those
which have been used in the first preferred embodiment.
[0060] Referring to FIG. 7, the displacement control valve 32C has
a chamber forming housing 67 and a housing 69. The chamber forming
housing 67 has formed therein a control pressure introducing
chamber 671 and a valve hole 673. The chamber forming housing 67
and the housing 69 cooperate to define a suction pressure
introducing chamber 672. The control pressure introducing chamber
671 communicates with the suction pressure introducing chamber 672
through the valve hole 673.
[0061] The housing 69 accommodates therein a bellows 47 as a
displacement body to which an auxiliary rod 68 is connected. The
auxiliary rod 68 extends through a partition wall 691 of the
housing 69 and further into the suction pressure introducing
chamber 672. The auxiliary rod 68 has a reduced diameter portion
681 that extends through the valve hole 673 and further into the
control pressure introducing chamber 671. The reduced diameter
portion 681 is connected to the transmitting rod 38, and the
auxiliary rod 68 is movable in conjunction with the transmitting
rod 38.
[0062] The auxiliary rod 68 is formed integrally with a valve body
70 which includes a cylindrical portion 701 and a tapered portion
702. The tapered portion 702 is shaped so that its diameter
decreases from the suction pressure introducing chamber 672 toward
the valve hole 673, or is tapered toward the valve hole 673. The
tapered portion 702 has its maximum-diameter portion 703 at the
boundary between the tapered portion 702 and the cylindrical
portion 701 and its minimum-diameter portion 704 at the boundary
between the tapered portion 702 and the reduced diameter portion
681 of the auxiliary rod 68. Namely, the tapered portion 702 is
shaped so that its cross-sectional area increases from the
minimum-diameter portion 704 as a minimum cross-sectional area
portion toward the maximum-diameter portion 703 as a maximum
cross-sectional area portion.
[0063] The cylindrical portion 701 of the valve body 70 is slidable
in the valve hole 673. With the cylindrical portion 701 (or the
maximum-diameter portion 703) positioned in the valve hole 673, the
valve hole 673 is closed, but a minute clearance is formed between
the circumferential wall surface of the valve hole 673 and the
cylindrical portion 701. This minute clearance permits the
cylindrical portion 701 to slide in the valve hole 673. The minute
clearance also allows the refrigerant gas in the valve hole 673 to
flow therethrough slightly with the cylindrical portion 701 (or the
maximum-diameter portion 703) positioned in the valve hole 673.
Namely, with the cylindrical portion 701 (the maximum-diameter
portion 703) positioned in the valve hole 673, the valve hole 673
is not completely but loosely closed, thereby allowing a slight
flow of the refrigerant gas therethrough.
[0064] The control pressure introducing chamber 671 communicates
with the pressure control chamber 121 through a passage 71, and the
suction pressure introducing chamber 672 communicates with the
suction chamber 131 through a passage 72. The passage 71, the
control pressure introducing chamber 671, the valve hole 673, the
suction pressure introducing chamber 672 and the passage 72
constitute a bleed passage 73 through which the refrigerant gas
flows from the pressure control chamber 121 into the suction
chamber 131. The discharge chamber 132 communicate with the
pressure control chamber 121 through a supply passage 74.
[0065] The control pressure introducing chamber 671 communicates
with the back pressure space 60 through the passages 351 and 371
and, therefore, the back pressure space 60 is a part of control
pressure region. The opening and closing operation of the valve
hole 673 depends on the balance among various forces such as the
electromagnetic force generated by the solenoid 34, the urging
force resulting from the pressure in the back pressure space 60 (or
control pressure) which urges the transmitting rod 38 the direction
that closes the valve hole 673, the spring force of the spring 53
in the control pressure introducing chamber 671 and the urging
force of the pressure sensing means 51.
[0066] The controller C regulates the electric current supplied to
the solenoid 34 (duty ratio) based on the temperature difference
between a target temperature set by the room temperature setting
device 55 and a room temperature then detected by the room
temperature detector 56. As the duty ratio is increased, the
transmitting rod 38 and the auxiliary rod 68 (the valve body 70)
are moved in the direction from the control pressure introducing
chamber 671 toward the valve hole 673.
[0067] In FIG. 7, the valve hole 673 of the displacement control
valve 32C is fully opened (the minimum-diameter portion 704 is
moved out of the valve hole 673) and the refrigerant gas in the
pressure control chamber 121 flows out into the suction chamber 131
through the bleed passage 73. The refrigerant gas in the discharge
chamber 132 flows into the pressure control chamber 121 through the
supply passage 74. In the state where the valve hole 673 is fully
opened, the pressure in the pressure control chamber 121 is low, so
that the inclination angle of the swash plate 22 (cf. FIG. 1A)
becomes the maximum. Accordingly, the piston 24 is reciprocated for
the maximum length of stoke (cf. FIG. 1A), with the result that
that the displacement of the compressor becomes the maximum.
[0068] With the electric current supply to the solenoid 34 stopped,
the maximum-diameter portion 703 is moved into the valve hole 673
thereby to close the valve hole 673. In this state, no refrigerant
gas flows from the pressure control chamber 121 into the suction
chamber 131 through the bleed passage 73. Since the refrigerant gas
in the discharge chamber 132 flows into the pressure control
chamber 121 through the supply passage 74, the pressure in the
pressure control chamber 121 is high in the state where the valve
hole 673 is closed, so that the inclination angle of the swash
plate 22 (cf. FIG. 1A) then becomes the minimum. Accordingly, the
stroke of the piston 24 (cf. FIG. 1A) becomes the minimum, so that
the displacement of the compressor becomes the minimum. The
displacement control valve 32C is of a normally-closed type
according to which the valve hole 673 is closed when no electric
current is supplied to the solenoid 34.
[0069] According to the fourth preferred embodiment, the same
advantageous effects as the paragraphs (1-2) and (1-3) in the first
preferred embodiment are obtained. The following additional effect
is also obtained.
[0070] (4-1) In the displacement control valve 32C of the fourth
preferred embodiment, no part of the tapered portion 702 protrudes
radially outward beyond the inner peripheral surface of the valve
hole 673 as seen in the moving direction (or the axial direction)
of the valve body 70. This structure prevents the difference
between the pressure acting on the tapered portion 702 (or the
pressure corresponding to the control pressure) and the pressure
acting on the valve body 70 from the opposite direction (or the
urging force from the pressure sensing means 51) from being changed
significantly by variation in the opening degree of the valve hole
673. As a result, the controllability of the displacement of the
compressor 10 (cf. FIG. 1A) is improved.
[0071] According to the present invention, the following
alternative embodiments may be practiced.
[0072] (1) In the foregoing embodiments, the intermediate portion
between the maximum-diameter and minimum-diameter portions of the
valve body is formed with a taper so that the diameter of the
intermediate portion of the valve body is changed linearly.
However, this intermediate portion of the valve body may be formed
such that the diameter thereof is changed in a non-linear
manner.
[0073] (2) The circumferential wall surface of the valve hole may
be formed with a taper. In this case, the minimum diameter portion
initially enters into the tapered valve hole when the valve body
having the cross-sectional area changed portion is moved into the
tapered valve hole.
(3) The bellows used as a part of the pressure sensing means in the
first and fourth embodiments may be substituted by a diaphragm or a
piston.
[0074] 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.
* * * * *