U.S. patent application number 10/686481 was filed with the patent office on 2004-05-06 for control valve for variable displacement compressor.
This patent application is currently assigned to TGK CO., LTD.. Invention is credited to Hirota, Hisatoshi, Kajiwara, Morimitsu.
Application Number | 20040086391 10/686481 |
Document ID | / |
Family ID | 32074160 |
Filed Date | 2004-05-06 |
United States Patent
Application |
20040086391 |
Kind Code |
A1 |
Hirota, Hisatoshi ; et
al. |
May 6, 2004 |
Control valve for variable displacement compressor
Abstract
The object of the present invention is to provide a control
valve for a variable displacement compressor, which is capable of
controlling the variable displacement compressor to the minimum
capacity without using an electromagnetic clutch, and can be
constructed without accommodating a solenoid in a pressure chamber.
A plunger of a solenoid is formed by a first plunger and a second
plunger, and a diaphragm is disposed between them, for sensing
suction pressure Ps, such that the first plunger controls a valve
element via a shaft, with component elements of the solenoid except
for the first plunger being disposed on a side of the diaphragm
where the atmospheric pressure is received. Further, when the
solenoid is not energized, the high suction pressure Ps urges the
second plunger toward the core via the diaphragm, and a spring
causes the first plunger to urge the valve element to the fully
open position, which enables the variable displacement compressor
to be controlled to the minimum capacity.
Inventors: |
Hirota, Hisatoshi; (Tokyo,
JP) ; Kajiwara, Morimitsu; (Tokyo, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
TGK CO., LTD.
Tokyo
JP
|
Family ID: |
32074160 |
Appl. No.: |
10/686481 |
Filed: |
October 16, 2003 |
Current U.S.
Class: |
417/222.2 ;
251/129.18 |
Current CPC
Class: |
F04B 27/1804 20130101;
F04B 2027/1827 20130101; F04B 2027/1854 20130101; F04B 2027/1859
20130101 |
Class at
Publication: |
417/222.2 ;
251/129.18 |
International
Class: |
F04B 001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2002 |
JP |
2002-308576 |
Feb 26, 2003 |
JP |
2003-048392 |
Aug 8, 2003 |
JP |
2003-289581 |
Claims
What is claimed is:
1. A control valve for a variable displacement compressor for
controlling pressure in a crank chamber formed gastight to thereby
change a refrigerant discharge capacity, characterized in that a
plunger of a solenoid is divided into a first plunger and a second
plunger, and a pressure-sensing member is disposed between the
first plunger and the second plunger, for sensing suction pressure
in a suction chamber.
2. The control valve for a variable displacement compressor
according to claim 1, wherein the first plunger is disposed between
a valve section for controlling pressure within the crank chamber
and the pressure-sensing member in a state urged for opening the
valve section, and the second plunger is attracted to the first
plunger via the pressure-sensing member to form an integral member
when the solenoid is energized, and is urged by the suction
pressure received by the pressure-receiving member in a direction
away from the first plunger when the solenoid is deenergized.
3. The control valve for a variable displacement compressor
according to claim 2, wherein the pressure-sensing member is a
diaphragm.
4. The control valve for a variable displacement compressor
according to claim 3, wherein the diaphragm is formed of polyimide
film.
5. The control valve for a variable displacement compressor
according to claim 4, wherein the polyimide film is formed by
laminating a plurality of pieces of polyimide film.
6. The control valve for a variable displacement compressor
according to claim 2, wherein the pressure-sensing member is a
bellows.
7. The control valve for a variable displacement compressor
according to claim 2, wherein the valve section is disposed between
first and second ports communicating respectively with a discharge
chamber of the variable displacement compressor and the crank
chamber.
8. The control valve for a variable displacement compressor
according to claim 7, wherein the valve section includes a valve
element disposed such that the valve element can be moved, from a
side of the first port, to and away from a valve seat formed in a
passage between the first port communicating with the discharge
chamber of the variable displacement compressor and the second port
communicating with the crank chamber, and a shaft disposed between
the valve element and the first plunger, for transmitting motion of
the first plunger to the valve element.
9. The control valve for a variable displacement compressor
according to claim 7, wherein the valve section includes a valve
element disposed such that the valve element can be moved, from a
side of the second port, to and away from a valve seat formed in a
passage between the first port communicating with the discharge
chamber of the variable displacement compressor and the second port
communicating with the crank chamber, and a pressure-sensing piston
integrally formed with the valve element such that the
pressure-sensing piston has an outer diameter substantially equal
to an inner diameter of a valve hole forming the valve seat, and
that the pressure-sensing piston receives discharge pressure from
the discharge chamber, at a pressure-receiving area equal to a
pressure-receiving area of the valve element, from a direction
opposite to a direction from which the valve element receives the
discharge pressure, and receives the suction pressure at an end
face thereof toward the solenoid, for transmitting motion of the
first plunger to the valve element.
10. The control valve for a variable displacement compressor
according to claim 1, wherein shock-absorbing means is disposed
between the pressure-sensing member and the first plunger.
11. The control valve for a variable displacement compressor
according to claim. 10, wherein the shock-absorbing means includes
a disk disposed between the pressure-sensing member and the first
plunger, and a spring constantly urging the disk such that the disk
is brought into abutment with the pressure sensing member.
12. The control valve for a variable displacement compressor
according to claim 11, wherein the first plunger and the disk are
centered by a sleeve.
13. The control valve for a variable displacement compressor
according to claim 11, wherein the first plunger is centered by
being fixed to a pressure-sensing piston that is integrally formed
with a valve element of a valve section that controls pressure in
the crank chamber, and held in an axially movably manner, and the
disk is centered through fitting of a convex or concave portion
formed in a center of the end face thereof opposed to the
pressure-sensing member and a concave or convex portion formed in a
center of the pressure-sensing member and the second plunger.
14. The control valve for a variable displacement compressor
according to claim 1, wherein the first plunger has a side thereof
toward a valve section that controls pressure in the crank chamber,
fixed to a pressure-sensing piston which is integrally formed with
a valve element of the valve section, and axially movably held, and
a side thereof toward the pressure-sensing member, held by a
C-shaped guide provided therearound.
15. The control valve for a variable displacement compressor
according to claim 1, wherein the first plunger is axially movably
held by two C-shaped guides provided therearound in a manner
axially spaced from each other.
16. The control valve for a variable displacement compressor
according to claim 15, wherein the first plunger has a surface
thereof for contact with the pressure-sensing member, formed into a
tapered shape, to thereby have a reduced flat area opposed to the
pressure-sensing member.
17. The control valve for a variable displacement compressor
according to claim 7, wherein the valve section includes a valve
element disposed such that the valve element can be moved, from a
side of the second port, to and away from a valve seat formed in a
passage between the first port communicating with the discharge
chamber of the variable displacement compressor and the second port
communicating with the crank chamber, and a pressure-sensing piston
integrally formed, with the valve element such that the
pressure-sensing piston has an outer diameter smaller than an inner
diameter of a valve hole forming the valve seat, and that the
pressure-sensing piston receives discharge pressure from the
discharge chamber, at a pressure-receiving area smaller than a
pressure-receiving area of the valve element, from a direction
opposite to a direction from which the valve element receives the
discharge pressure, and receives the suction pressure at an end
face thereof toward the solenoid, for transmitting motion of the
first plunger to the valve element.
18. The control valve for a variable displacement compressor
according to claim 2, wherein the valve section includes a valve
element disposed between a first port and a second port
communicating respectively with a discharge chamber of the variable
displacement compressor and the crank chamber and between a third
port and a fourth port respectively communicating with the crank
chamber and the suction chamber such that the valve element can be
moved, from a side of the first port, to and away from a valve seat
formed in a first passage between the first port and the second
port, and a shaft disposed between the valve element and the first
plunger for transmitting motion of the first plunger to the valve
element, the first plunger opening and closing the second passage
between the third port and the fourth port.
19. The control valve for a variable displacement compressor
according to claim 2, wherein the valve section includes a first
valve element disposed between a first port and a second port
communicating respectively with a discharge chamber of the variable
displacement compressor and the crank chamber and between a third
port and a fourth port respectively communicating with the crank
chamber and the suction chamber such that the first valve element
can be moved, from a side of the second port, to and away from a
valve seat formed in a first passage between the first port and the
second port, a pressure-sensing, piston integrally formed with the
first valve element such that the pressure-sensing piston has an
outer diameter substantially equal to an inner diameter of a valve
hole forming the valve seat, and receives discharge pressure from
the discharge chamber, at a pressure-receiving area equal to a
pressure-receiving area of the valve element from a direction
opposite to a direction from which the valve element receives the
discharge pressure, and a second valve element integrally formed
with the pressure-sensing piston such that the second valve element
opens and closes a second passage between the third port and the
fourth port and receives the suction pressure at an end face
thereof toward the solenoid, for transmitting motion of the first
plunger to the valve element.
20. The control valve for a variable displacement compressor
according to claim 1, wherein the solenoid includes a spring for
urging the second plunger toward the first plunger against the
suction pressure received by the pressure-sensing member, and an
adjustment screw for adjusting load of the spring.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS, IF ANY
[0001] This application claims priority of Japanese Applications
No.2002-308576 filed on Oct. 23, 2002, entitled "Control Valve for
Variable Displacement Compressor", No.2003-048392 filed on Feb. 26,
2003, entitled "Control Valve for Variable Displacement Compressor"
and No.2003-289581 filed on Aug. 8, 2003, entitled "Control Valve
for Variable Displacement Compressor".
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] The present invention relates to a control valve for a
variable displacement compressor, and more particularly to a
control valve employed in a variable displacement compressor of an
automotive air conditioner, for controlling the refrigerant
discharge capacity.
[0004] (2) Description of the Related Art
[0005] A compressor used in a refrigeration cycle of an automotive
air conditioner is driven by an engine whose rotational speed is
varied depending on a traveling condition of the vehicle, and hence
is incapable of performing rotational speed control. For this
reason, in general, a variable displacement compressor capable of
changing the refrigerant discharge capacity is employed so as to
obtain an adequate refrigerating capacity without being constrained
by the rotational speed of the engine.
[0006] In the variable displacement compressor, in general, a
wobble plate disposed within a crank chamber formed gastight, such
that the inclination angle thereof can be changed, is driven by the
rotational motion of a rotational shaft, for performing wobbling
motion, and pistons caused to perform reciprocating motion in a
direction parallel to the rotational shaft by the wobbling motion
of the wobble plate draw refrigerant from a suction chamber into
associated cylinders, compress the refrigerant, and then discharge
the same into a discharge chamber. In doing this, the inclination
angle of the wobble plate is varied by changing the pressure in the
crank chamber, whereby the refrigerant discharge capacity is
varied. The control valve for a variable displacement compressor
provides control to change the pressure in the crank chamber.
[0007] In general, such a control valve for a variable displacement
compressor, which variably controls the discharge capacity of the
compressor, operates to introduce part of refrigerant discharged
from the discharge chamber and having discharge pressure Pd into
the crank chamber formed gastight, such that pressure Pc in the
crank chamber is controlled through control of the amount of
refrigerant thus introduced, which control is carried out according
to suction pressure Ps in the suction chamber. That is, the control
valve for a variable displacement compressor senses the suction
pressure Ps, and controls the flow rate of refrigerant introduced
from the discharge chamber into the crank chamber at the discharge
pressure Pd, so as to hold the suction pressure Ps at a constant
level.
[0008] To this end, the control valve for a variable displacement
compressor is equipped with a pressure-sensing section for sensing
the suction pressure Ps, and a valve section for causing a passage
leading from the suction chamber to the crank chamber to open and
close according to the suction pressure Ps sensed by the
pressure-sensing section. Further, a type of the control valve for
a variable displacement compressor which is capable of freely
externally setting a value of suction pressure Ps to be assumed, at
the start of the variable placement operation, is equipped with a
solenoid that enables configuration of settings of the
pressure-sensing section by external electric current.
[0009] By the way, conventional control valves for a variable
displacement compressor which can be externally controlled include
a type for control of a variable displacement compressor configured
such that an engine is directly connected to a rotational shaft of
the compressor without providing an electromagnetic clutch between
the engine and the rotational shaft on which a wobble plate is
fitted, for execution and inhibition of transmission of a driving
force of the engine (see e.g. Japanese Unexamined Patent
Publication No. 2000-110731 (Paragraph Nos. [0010] and [0044], and
FIG. 1)).
[0010] This control valve comprises a valve section causing a
passage communicating between a discharge chamber and a crank
chamber to be opened and closed, a solenoid for generating an
electromagnetic force causing the valve section to operate in the
closing direction, and a pressure-sensing section for causing the
valve section to operate in the opening direction as suction
pressure Ps becomes lower compared with the atmospheric pressure,
which are arranged in this order. Therefore, when the solenoid is
not energized, the valve section is in a fully open state, whereby
pressure Pc in a crank chamber can be held at a pressure close to
discharge pressure Pd. This causes the wobble plate to become
substantially at right angles to the rotational shaft, enabling the
variable displacement compressor to operate with minimum capacity.
Thus, the refrigerant discharge capacity can be substantially
reduced to approximately zero even when the engine is directly
connected to the rotational shaft, which makes it possible to
eliminate the electromagnetic clutch.
[0011] However, the conventional control valve for controlling a
variable displacement compressor dispensed with the electromagnetic
clutch is configured such that the pressure-sensing section and the
valve section are arranged with the solenoid interposed
therebetween, and the suction pressure Ps is introduced to the
pressure-sensing section which compares the suction pressure Ps and
the atmospheric pressure, via the solenoid. This necessitates the
solenoid in its entirety to be accommodated within a pressure
chamber, and hence components of the solenoid need to be designed
with considerations given to resistance to pressure.
SUMMARY OF THE INVENTION
[0012] The present invention has been made in view of these points,
and an object thereof is to provide a control valve for a variable
displacement compressor, which is capable of controlling the
variable displacement compressor to the minimum capacity without
using an electromagnetic clutch, and can be constructed without
accommodating a solenoid in a pressure chamber.
[0013] To solve the above problem, the present invention provides a
control valve for a variable displacement compressor for
controlling pressure in a crank chamber formed gastight to thereby
change a refrigerant discharge capacity, characterized in that a
plunger of a solenoid is divided into a first plunger and a second
plunger, and a pressure-sensing member is disposed between the
first plunger and the second plunger, for sensing suction pressure
in a suction chamber.
[0014] The above and other objects, features and advantages of the
present invention will become apparent from the following
description when taken in conjunction with the accompanying
drawings which illustrate preferred embodiments of the present
invention by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a first embodiment.
[0016] FIG. 2 is a central longitudinal cross-sectional view
showing the control valve for a variable displacement compressor in
a state where the variable displacement compressor is started.
[0017] FIG. 3 is a central longitudinal cross-sectional view
showing the control valve for a variable displacement compressor in
a state where the variable displacement compressor is in steady
operation.
[0018] FIG. 4 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a second embodiment.
[0019] FIG. 5 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a third embodiment.
[0020] FIG. 6 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a fourth embodiment.
[0021] FIG. 7 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a fifth embodiment.
[0022] FIG. 8 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a sixth embodiment.
[0023] FIG. 9 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a seventh embodiment.
[0024] FIG. 10 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to an eighth embodiment.
[0025] FIG. 11 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a ninth embodiment.
[0026] FIG. 12 is a partial enlarged central longitudinal
cross-sectional view for explaining a valve section of a control
valve for a variable displacement compressor, according to a tenth
embodiment.
[0027] FIG. 13 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to an eleventh embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings.
[0029] FIG. 1 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a first embodiment of the
invention.
[0030] The control valve for the variable displacement compressor
includes a valve section in an upper location as viewed in the
figure. In the valve section, an opening in the top of a body 11
forms a port 12 which communicates with a discharge chamber of the
variable displacement compressor and receives discharge pressure
Pd, and a strainer 13 is provided on the port 12. The port 12
receiving the discharge pressure Pd internally communicates with a
port 14 communicating with a crank chamber of the variable
displacement compressor and formed in the body 11 so as to guide
controlled pressure Pc out into the crank chamber, and a valve seat
15 is formed in a refrigerant passage communicating between the
port 12 and the port 14, as an integral part of the body 11. In
opposed relation to a side of the valve seat where the discharge
pressure Pd is received, a valve element 16 is disposed in an
axially movable manner. The valve element 16 is urged in the
valve-closing direction by a spring 17 which has its load adjusted
by an adjustment screw 18 screwed into the port 12. Below the body
11, as viewed in the figure, there is formed a port 19
communicating with a suction chamber of the variable displacement
compressor and receiving suction pressure Ps.
[0031] A hollow cylindrical member 20 is disposed at a lower end of
the body 11, and a first plunger 21 is axially movably disposed
within the hollow cylindrical member 20. The first plunger 21 has a
guide 22, which is made e.g. of polytetrafluoroethylene and has a
low sliding resistance, fitted along the periphery thereof at a
lower part location as viewed in the figure. The outer peripheral
surface of the guide 22 is in sliding contact with the inner wall
of the hollow cylindrical member 20, whereby when the first plunger
21 axially moves, the guide 22 serves to guide the first plunger
21, while maintaining the same at a predetermined distance from the
inner wall of the hollow cylindrical member 20. It should be noted
that the guide 22 is not provided along the entire circumference of
the first plunger 21, but has one portion thereof cut open, thereby
allowing the suction pressure Ps to be introduced into a space
formed on a lower end side of the first plunger 21.
[0032] The first plunger 21 has a flange 23 fixed to an upper end
location thereof by press-fitting, with a spring 24 interposed
between the flange 23 and an upper end face of the hollow
cylindrical member 20. A shaft 25, which is axially movably
disposed within the body 11 with almost no clearance between the
same and the body 11, has a lower end thereof fixed to the first
plunger 21, by press-fitting, at an upper axial location of the
first plunger 21. Thus, the shaft 25 and the guide 22 position the
first plunger 21 on the axis of the body 11. The upper end of the
shaft 25 extends through a valve hole and is in contact with the
valve element 16.
[0033] The spring 24 urging the first plunger 21 upward as viewed
in the figure is configured to have a larger spring force than that
of the spring 17 urging the valve element 16 in the valve-closing
direction. Therefore, when the solenoid is not energized, the first
plunger 21 is in abutment with the ceiling of a chamber
communicating with the port 19, and the valve element 16 with which
the shaft 25 is in contact is in its fully open position.
[0034] Below the first plunger 21, a diaphragm 26 constituting a
pressure-sensing section is disposed. The diaphragm 26 has its
outer peripheral edge sandwiched by the hollow cylindrical member
20 and a casing 27 of the solenoid, and sealed by a gasket 28. The
sandwiching of the diaphragm 26 by the hollow cylindrical member 20
and the casing 27 of the solenoid is realized by swaging an upper
end edge of the casing 27 as viewed in the figure onto the lower
end of the body 11 as viewed in the figure, with the hollow
cylindrical member 20 held therebetween. Thus, part forming a
pressure chamber of the control valve for the variable displacement
compressor extends up to a portion partitioned by the diaphragm 26,
and part lower than this portion receives the atmospheric pressure.
It should be noted that the diaphragm 26 is formed e.g. of one
piece of polyimide film. However, by using a plurality of pieces
thereof overlaid one upon other as required, it is possible to
increase resistance to breakage which might be caused by repeated
collision of the first plunger 21.
[0035] Within the casing 27, a magnet coil 29 is disposed, and
inside the magnet coil 29 is disposed a sleeve 30. The sleeve 30
has a core 31 inserted into a lower portion thereof and fixed
thereto. Between the core 31 and the diaphragm 26 is disposed a
second plunger 32 such that the second plunger 32 is axially
movable within the sleeve 30. The second plunger 32 has the upper
end of a shaft 33 disposed along the axis thereof, as viewed in the
figure, fixed thereto by press-fitting, with the lower end of the
shaft 33 being supported by a bearing 35 disposed within a knob 34
which closes the open end of the casing 27. Disposed between the
second plunger 32 and the core 31 is a spring 36 which urges the
second plunger 32 toward the diaphragm 26.
[0036] The body 11 has an O ring 37 fitted on a periphery thereof
at a location between the port 12 via which the discharge pressure
Pd is introduced and the port 14 via which the pressure Pc is
guided out into the crank chamber, and has an O ring 38 fitted on a
periphery thereof at a location between the port 14 via which the
pressure Pc is guided out and the port 19 via which the suction
pressure Ps is introduced. The lower end of the casing 27 as viewed
in the figure has an O ring 39 fitted on a periphery thereof for
cutting off the suction pressure Ps from the atmospheric pressure.
Further, the magnet coil 29 is supplied with control current via a
harness 40.
[0037] In the above construction described above, the hollow
cylindrical member 20, the casing 27, and the knob 34 are made of
magnetic materials, thereby serving as a yoke of a magnetic circuit
of the solenoid, with the lines of magnetic force generated by the
magnet coil 29 extending through the magnetic circuit formed by the
casing 27, the hollow cylindrical member 20, the first plunger 21,
the second plunger 32, the core 31, and the knob 34.
[0038] The control valve for a variable displacement compressor as
shown in the figure is in a state wherein the solenoid is not
energized, and the suction pressure Ps is high, that is, when the
air conditioner is not in operation. Since the suction pressure Ps
is high, the diaphragm 26 is displaced downward, as viewed in the
figure, against the load of the spring 36 to thereby bring the
second plunger 32 into abutment with the core 31. On the other
hand, the first plunger 21 is urged upward as viewed in the figure
by the spring 24, so that it is moved away from the diaphragm 26,
and hence in a state free from influence of the diaphragm 26 which
is displaced by changes in the suction pressure Ps. Further, the
first plunger 21 urges the valve element 16 toward the fully open
position thereof via the shaft 25. Therefore, in this state, even
when the rotational shaft of the variable displacement compressor
is driven for rotation by the engine, the variable displacement
compressor is operated with the minimum discharge capacity.
[0039] FIG. 2 is a central longitudinal cross-sectional view
showing the control valve for a variable displacement compressor in
a state where the variable displacement compressor is started, and
FIG. 3 is a central longitudinal cross-sectional view showing the
control valve for a variable displacement compressor in a state
where the variable displacement compressor is in steady
operation.
[0040] When the maximum control current is supplied to the magnet
coil 29 of the solenoid, as in the case of the variable
displacement compressor having been started, as shown in FIG. 2,
the second plunger 32 is pressed downward as viewed in the figure
by the high suction pressure Ps to be brought into abutment with
the core 31, so that even if the second plunger 32 is attracted by
the core 31, it remains in the same position. Therefore, in this
case, the second plunger 32 and the core 31 behaves as if they were
a fixed core, so that the second plunger 32 attracts the first
plunger 21, causing the first plunger 21 to be attached to the
second plunger 32 via the diaphragm 26, whereby the shaft 25 is
pulled downward. As a result, the spring 17 causes the valve
element 16 to be seated on the valve seat 15, to fully close the
valve section. This blocks off the passage extending from the
discharge chamber to the crank chamber, so that the variable
displacement compressor is promptly shifted into the operation with
the maximum capacity.
[0041] When the variable displacement compressor continues to
operate with the maximum capacity to make the suction pressure Ps
low enough, the diaphragm 26 senses the suction pressure Ps to
attempt to move upward as viewed in the figure. At this time, if
the control current supplied to the magnet coil 29 is decreased
according to the set temperature of the air conditioner, as shown
in FIG. 3, the first plunger 21, the diaphragm 26, and the second
plunger 32 in attracted state move in unison upward as viewed in
the figure to a position where the suction pressure Ps, the loads
of the springs 17, 24, and 36, and the attractive force of the
solenoid are balanced. This causes the valve element 16 to be
pushed upward as viewed in the figure by the shaft 25 to move away
the valve seat 15, to be set to a predetermined valve lift.
Therefore, refrigerant having discharge pressure Pd is introduced
into the crank chamber at a flow rate controlled to a value
dependent on the valve lift, whereby the variable displacement
compressor is shifted to operation with the capacity corresponding
to the control current.
[0042] When the control current supplied to the magnet coil 29 of
the solenoid is constant, the diaphragm 26 senses the suction
pressure Ps to thereby control the valve lift of the valve section.
For example, when the refrigerating load is increased to make the
suction pressure Ps high, the diaphragm 26 is displaced downward as
viewed in the figure, so that the valve element 16 is also moved
downward to decrease the valve lift of the valve section, causing
the variable displacement compressor to operate in a direction of
increasing the discharge capacity. On the other hand, when the
refrigerating load is decreased to make the suction pressure Ps
low, the diaphragm 26 is displaced upward as viewed in the figure
to increase the valve lift of the valve section, causing the
variable displacement compressor to operate in a direction of
decreasing the discharge capacity. Thus, the variable displacement
compressor operates to make the suction pressure Ps constant.
[0043] FIG. 4 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a second embodiment of the
present invention, and component elements identical or equivalent
to those shown in FIG. 1 are designated by the same reference
numerals, and detailed description thereof is omitted.
[0044] The control valve for a variable displacement compressor,
according to the second embodiment is distinguished from the
control valve according to the first embodiment in that the
locations of the port 12 receiving discharge pressure Pd from the
discharge chamber and the port 14 from which the controlled
pressure Pc is guided out into the crank chamber are inverted.
[0045] In the control valve for a variable displacement compressor,
the valve element 16 is integrally formed with a pressure-sensing
piston 41, and the discharge pressure Pd is introduced into a
reduced-diameter portion connecting the valve element 16 and the
pressure-sensing piston 41. The pressure-sensing piston 41 has an
outer diameter equal to an inner diameter of a valve hole forming
the valve seat 15, whereby the pressure-receiving area of the valve
element 16 and the pressure-receiving area of the pressure-sensing
piston 41 are made equal to each other. This causes the force of
the discharge pressure Pd acting to move the valve element 16
upward as viewed in the figure to be cancelled out by the force of
the same acting to move the pressure-sensing piston 41 downward as
viewed in the figure, thereby enabling the solenoid and the
diaphragm 26 to control the valve element 16 without being
influenced by the discharge pressure Pd which is high.
[0046] The pressure-sensing piston 41 has a function of canceling
out influence of the discharge pressure Pd and a function of a
shaft for transmitting the motions of the solenoid and the
diaphragm 26 to the valve element 16, as in the case of the control
valve for a variable displacement compressor, according to the
first embodiment.
[0047] The other features of the construction in which the plunger
is divided into two with the diaphragm 26 disposed therebetween and
the construction of the solenoid are the same as those of the
control valve for a variable displacement compressor, according to
the first embodiment, and hence description of the operation
thereof is omitted.
[0048] FIG. 5 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a third embodiment of the
present invention, and component elements identical or equivalent
to those shown in FIG. 1 are designated by the same reference
numerals, and detailed description thereof is omitted.
[0049] The control valve for a variable displacement compressor,
according to the third embodiment is distinguished from the control
valves according to the first embodiment and the second embodiment
in that the control valve performs the control of the flow rate of
refrigerant having pressure Pc allowed to escape from the crank
chamber to the suction chamber in addition to the control of the
flow rate of refrigerant having discharge pressure Pd introduced
into the crank chamber, which is carried out by the control valves
according to the first and second embodiments.
[0050] In this control valve for a variable displacement
compressor, the passage communicating with the crank chamber is
divided in two. That is, the body 11 has a port 14a via which
controlled pressure Pc1 is guided out into the crank chamber and a
port 14b via which pressure Pc2 is introduced from the crank
chamber. This is for forming a passage allowing refrigerant
introduced from the discharge chamber and controlled by the valve
section to once enter the crank chamber and then flow from the
crank chamber into the suction chamber, so as to cause lubricating
oil mixed in the refrigerant for lubrication of the compressor, to
be positively flow by way of the crank chamber.
[0051] The port 14b via which the refrigerant returns from the
crank chamber opens, via a communication passage 42, into space
communicating with the port 19 leading to the suction chamber. The
opening which opens into the space is configured to be opened and
closed by the first plunger 21. Therefore, when the valve section
is fully closed, a passage between the crank chamber and the
suction chamber is opened, to maximize the flow rate of refrigerant
allowed to flow from the crank chamber to the suction chamber,
thereby enabling the compressor to perform prompt transition to the
maximum capacity operation, while the valve section is fully open,
the passage between the crank chamber and the suction chamber is
closed, to maximize the flow rate of refrigerant introduced from
the discharge chamber into the crank chamber, thereby enabling the
compressor to perform prompt transition to the minimum capacity
operation.
[0052] The other features of the construction in which the plunger
is divided into the first plunger 21 and the second plunger 32 with
the diaphragm 26 disposed therebetween, and the construction of the
solenoid are the same as those of the control valve for a variable
displacement compressor, according to the first embodiment.
Therefore, the operation of this control valve for a variable
displacement compressor is the same as that of the control valve
for a variable displacement compressor, according to the first
embodiment, and hence description thereof is omitted.
[0053] FIG. 6 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a fourth embodiment of the
present invention. In FIG. 6, component elements identical or
equivalent to those shown in FIG. 1 are designated by the same
reference numerals, and detailed description thereof is
omitted.
[0054] The control valve for a variable displacement compressor,
according to the fourth embodiment includes cushioning means for
softening impact of collision of the first plunger 21 with the
diaphragm 26 occurring when the first plunger 21 is attracted to
the second plunger 32 upon energization of the solenoid. More
specifically, a disk 43 is interposed between the first plunger 21
and the diaphragm 26, and a spring 44 is interposed between the
first plunger 21 and the disk 43. This arrangement has not only the
function of constantly bringing the disk 43 into contact with the
diaphragm 26, but also the same function as the function of the
spring 24 urging the first plunger 21 toward the valve section as
in the case of the control valves for a variable displacement
compressor, according to the first to third embodiments. The disk
43 is held by a guide 22 formed on the outer periphery of the first
plunger 21 and extending further downward with respect to a lower
end of the first plunger 21.
[0055] With the above arrangement, the disk 43 is urged by the
spring 44, so that the second plunger 32, the diaphragm 26, and the
disk 43 are always in contact with each other, and move in unison.
When the solenoid is not energized, as shown in the figure, the
first plunger 21 and the disk 43 are made separate from each other
by the spring 44. When the solenoid is energized, the first plunger
21 is attracted by the disk 43 integrated therewith and attached to
the disk 43 by collision. The force of impact of the collision is
transmitted to the diaphragm 26 after being absorbed for cushioning
by the disk 43, so that the impact on the diaphragm 26 is
reduced.
[0056] The other features of the construction in which the plunger
is divided into the first plunger 21 and the second plunger 32 with
the diaphragm 26 disposed therebetween, and the construction of the
solenoid are also the same as those of the control valve for a
variable displacement compressor, according to the first
embodiment. Therefore, the operation of this control valve for a
variable displacement compressor is the same as that of the control
valve for a variable displacement compressor, according to the
first embodiment, and therefore description thereof is omitted.
[0057] FIG. 7 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a fifth embodiment of the
present invention. In FIG. 7, component elements identical or
equivalent to those shown in FIG. 4 are designated by the same
reference numerals, and detailed description thereof is
omitted.
[0058] The control valve for a variable displacement compressor,
according to the fifth embodiment includes a mechanism for
adjusting the load of the spring 36, in addition to the
construction of the control valve for a variable displacement
compressor, according to the second embodiment. More specifically,
an adjustment screw 45 is screwed into the knob 34 at the lower end
of the valve as viewed in the figure, and the adjustment screw 45
is formed to have such a shape that it supports the lower end of
the shaft 33 in an axially movable manner. A retaining ring 46 is
fitted on an intermediate portion of the shaft 33, and a spring
retainer 47 is provided such that the upward motion, as viewed in
the figure, of the spring retainer 47 is limited by the retaining
ring 46. A spring 36 is interposed between the spring retainer 47
and the adjustment screw 45. With this arrangement, the amount of
screw-in of the adjustment screw 45 into the knob 34 can be
adjusted to adjust the load of the spring 36, thereby adjusting the
set value for the control valve for a variable displacement
compressor.
[0059] FIG. 8 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a sixth embodiment of the
present invention. In FIG. 8, component elements identical or
equivalent to those shown in FIGS. 6 and 7 are designated by the
same reference numerals, and detailed description thereof is
omitted.
[0060] The control valve for a variable displacement compressor,
according to a sixth embodiment of the present invention is
configured such that the first plunger 21 and the disk 43 are
axially movably guided by a sleeve 48 fixed to the hollow
cylindrical member 20 by press-fitting, and the first plunger 21 is
in contact with the pressure-sensing piston 41 which is integrally
formed with the valve element 16. The hollow cylindrical member 20
has a lower part thereof, as viewed in the figure, expanded such
that annular space is defined between the same and the sleeve 48,
with a communication hole 49 being formed through a stepped portion
thereof, for communication between the port 19 via which the
suction pressure Ps is introduced and a space above the upper
surface of the diaphragm 26. Further, the lower end of the
solenoid, as viewed in the figure, is provided with a connector 50
to which is connected the connector of the harness. The connector
50 has the adjustment screw 45 screwed therein for adjustment of
load of the spring 36, and is formed with a communication hole 51
for communicating the inside of the solenoid with the atmosphere.
The other features of this control valve are identical to those of
the control valve for a variable displacement compressor, according
to the fourth embodiment, except that the valve element 16 has a
tapered shape, and hence description of the operation thereof is
omitted.
[0061] FIG. 9 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a seventh embodiment of the
present invention. In FIG. 9, component elements identical or
equivalent to those shown in FIG. 8 are designated by the same
reference numerals, and detailed description thereof is
omitted.
[0062] The control valve for a variable displacement compressor,
according to the seventh embodiment is distinguished from the
control valve for a variable displacement compressor according to
the sixth embodiment in which the centering of the first plunger 21
and the disk 43 is performed by the sleeve 48 fixed to the hollow
cylindrical member 20, in that the centering is performed by
another method. That is, the first plunger 21 is centered by being
fitted on the pressure-sensing piston 41 integrally formed with the
valve element 16, and the disk 43 is centered by having a convex
portion formed on an end face thereof toward the diaphragm 26
fitted in a concave portion formed in the center of the diaphragm
26 and the second plunger 32. It should be noted that the same
effects can be obtained by providing a concave portion in the disk
43 and providing a convex portion on the diaphragm 26 and the
second plunger 32. The other features of the construction of this
control valve are the same as those of the control valve for a
variable displacement compressor, according to the sixth embodiment
shown in FIG. 8, and therefore, description of the operation
thereof is omitted.
[0063] FIG. 10 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to an eighth embodiment of the
present invention. In FIG. 10, component elements identical or
equivalent to those shown in FIGS. 7 and 8 are designated by the
same reference numerals, and detailed description thereof is
omitted.
[0064] The control valve for a variable displacement compressor,
according to the eighth embodiment is distinguished from the
control valve for a variable displacement compressor, according to
the fifth embodiment shown in FIG. 7 in that the shape of the first
plunger 21 is changed such that it is promptly brought into contact
with the diaphragm 26.
[0065] That is, the first plunger 21 is axially movably held by two
C-shaped guides 22 provided therearound in sliding contact with the
inner wall of the hollow cylindrical member 20 with a predetermined
distance maintained from the surface of the inner wall. Therefore,
the first plunger 21 is held by the hollow cylindrical member 20
with a relatively large clearance provided between the first
plunger 21 and the hollow cylindrical member 20. An end face of the
first plunger 21 opposed to the diaphragm 26 is not flat but
configured such that a center and its neighborhood thereof is
formed as a flat surface and a surrounding portion is gently
tapered, or such that the cross-section of the end face has a shape
of an arc having a large radius.
[0066] If the guide 22 is made of a material, e.g.
polytetrafluoroethylene- , having a characteristic of expanding and
contracting depending on temperature or the type of refrigerant,
when the solenoid is energized to cause the first plunger 21 and
the second plunger 32 to attract each other, the guide 22 sometimes
causes the first plunger 21 to be inclined and then bring the same
into contact with the diaphragm 26. In this case, the end face of
the first plunger 21 opposed to the diaphragm 26 is brought into
abutment the diaphragm via its tapered portion, and therefore it is
possible to cause the valve element 16 to promptly close the valve
section. This prevents occurrence of a two-step operation occurring
in the case of the end face of the first plunger 21 opposed to the
diaphragm being flat, i.e. a two-step operation in which a
peripheral portion of the flat end face of the first plunger 21 is
brought into contact with the diaphragm 26 by the attractive force,
and then the flat end face of the first plunger 21 is brought into
contact with the diaphragm 26. This makes it possible to promptly
close the valve element 16, and close the valve element 16 with
accuracy since the phenomenon of the first plunger 21 being stopped
at a first step of the two-step operation does not occur.
[0067] It should be noted that this control valve for a variable
displacement compressor has the same construction as that of the
control valve for a variable displacement compressor, according to
the fifth embodiment shown in FIG. 7, except that the end face of
the first plunger 21 opposed to the diaphragm 26 has a tapered
shape, and the first plunger 21 is supported by the two guides 22,
and therefore, description of the operation thereof is omitted.
[0068] FIG. 11 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to a ninth embodiment of the
present invention. In FIG. 11, component elements identical or
equivalent to those shown in FIG. 10 are designated by the same
reference numerals, and detailed description thereof is
omitted.
[0069] The control valve for a variable displacement compressor,
according to the ninth embodiment is distinguished from the control
valve for a variable displacement compressor, according to the
eighth embodiment shown in FIG. 10 in that a bellows is used for
the pressure-sensing member for sensing the suction pressure
Ps.
[0070] That is, the bellows 52 is disposed between the first
plunger 21 and the second plunger 32. The bellows 52 has its flange
portion radially extending from an upper end face thereof as viewed
in the figure, sandwiched between the hollow cylindrical member 20
and the casing 27 of the solenoid, and sealed by the gasket 28. The
lower end face of the bellows 52 as viewed in the figure is closed,
and in contact with the second plunger 32. The first plunger 21 has
a columnar member 53 formed integrally therewith at a lower portion
thereof as viewed in the figure, and the columnar member 53 is
positioned in a hollow space of the bellows 52. When the solenoid
is not energized, and the first plunger 21 is urged by the spring
24 in the upward direction as viewed in the figure, the columnar
member 53 of the first plunger 21 is spaced from the bellows
52.
[0071] It should be noted that this control valve for a variable
displacement compressor has the same construction as that of the
control valve for a variable displacement compressor, according to
the eighth embodiment shown in FIG. 10, except that the bellows 52
is used for the pressure-sensing member. Therefore, the operation
of the control valve according to the present embodiment is the
same as that of the control valve according to the eight
embodiment, and hence description of the operation thereof is
omitted.
[0072] FIG. 12 is a partial enlarged central longitudinal
cross-sectional view for explaining the construction of a valve
section of a control valve for a variable displacement compressor,
according to a tenth embodiment of the present invention. In FIG.
12, component elements identical or equivalent to those shown in
FIG. 11 are designated by the same reference numerals, and detailed
description thereof is omitted.
[0073] The control valve for a variable displacement compressor,
according to the tenth embodiment is configured such that even when
the suction pressure Ps is in any condition, making the receiving
pressure unbalanced with the discharge pressure Pd received at the
valve section, it is possible to promptly fully open the valve.
[0074] That is, in the control valves for a variable displacement
compressor shown in FIGS. 4, 7 to 11, the ports of the valve
section are arranged from the solenoid side in the order of the
respective ones for the suction pressure Ps, the discharge pressure
Pd, and the pressure Pc for the crank chamber, so as to prevent the
discharge pressure Pd, which is highest in pressure, from affecting
the control of valve element 16. This is achieved by making the
inner diameter A of the valve hole equal to the outer diameter B of
the pressure-sensing piston 41, which causes the force of the
discharge pressure Pd acting on the valve element 16 in the upward
direction as viewed in the figure to be cancelled out by the force
of the same acting on the pressure-sensing piston 41 in the
downward direction as viewed in the figure. In the construction of
canceling out the discharge pressure Pd, the valve element 16
controls the valve section by the differential pressure (Pc-Ps)
between the pressure Pc for the crank chamber and the suction
pressure Ps.
[0075] However, the differential pressure (Pc-Ps) between the
pressure Pc acting on the valve element 16 and the suction pressure
Ps acting on the pressure-sensing piston 41 imposes load on the
valve element 16 and the pressure-sensing piston 41 in the
self-closing direction since the pressure Pc is higher than the
suction pressure Ps. Therefore, when the feed of current to the
solenoid is stopped to fully open the valve section, the spring 24
urging the first plunger 21 in the valve-opening direction presses
the pressure-sensing piston 41 to cause the valve element 16 to be
made separate from the valve seat 15. However, as the differential
pressure (Pc-Ps) increases, the load in the self-closing direction
also increases, which makes the valve section difficult to open,
and in some cases, the phenomenon of incapable of opening the valve
section occurs. Particularly, in the case of variable displacement
compressors that dispense with an electromagnetic clutch, no matter
the suction pressure Ps may be in what pressure condition, when the
power supply to the solenoid is stopped, it is necessary to
forcibly fully open the control valve to minimize the discharge
capacity of the compressor.
[0076] To this end, in this control valve for a variable
displacement compressor, the inner diameter A of the valve hole is
made e.g. approximately 3% larger than the outer diameter B of the
pressure-sensing piston 41, to make the pressure-receiving area of
the valve element 16 larger than the pressure-sensing area of the
pressure-sensing piston 41, whereby the pressure-receiving balance
related to the discharge pressure Pd is thrown off in the
valve-opening direction. This makes the load in the self-closing
direction smaller even when the differential pressure (Pc-Ps)
increases, so that it is possible to positively fully open the
valve section by the urging force of the spring 24 when the power
supply to the solenoid is turned off.
[0077] FIG. 13 is a central longitudinal cross-sectional view
showing the construction of a control valve for a variable
displacement compressor, according to an eleventh embodiment of the
present invention. In FIG. 13, component elements identical or
equivalent to those shown in FIGS. 5 and 10 are designated by the
same reference numerals, and detailed description thereof is
omitted.
[0078] The control valve for a variable displacement compressor,
according to the eleventh embodiment, is configured such that in
addition to control provided by the control valve for a variable
displacement compressor, according to the eighth embodiment shown
in FIG. 10, on the flow rate of refrigerant introduced into the
crank chamber while canceling out the discharge pressure Pd of
refrigerant introduced into the crank chamber, this control valve
provides control also on the flow rate of refrigerant having
pressure Pc allowed to escape from the crank chamber into the
suction chamber.
[0079] That is, the body 11 is provided with a port 14a for guiding
refrigerant out into the crank chamber and a port 14b for
introducing refrigerant from the crank chamber, and this port 14b
communicates with a space accommodating the first plunger 21 via a
refrigerant passage 54 coaxial with the pressure-sensing piston 41.
The solenoid side end of the pressure-sensing piston 41 has a valve
element 55 integrally formed therewith, and the valve element 55
has an end face thereof in contact with the first plunger 21. The
valve element 55 has a valve element structure of a spool valve.
When the valve element 16 is lifted off the valve seat 15, the
valve element 55 closes the refrigerant passage 54 to block off the
flow of refrigerant from the crank chamber to the suction chamber,
whereas when the valve element 16 is seated on the valve seat 15,
the valve element 55 opens the refrigerant passage 54 to allow
refrigerant in the crank chamber to escape into the suction chamber
via the port 19. This makes it possible to promptly increase or
decrease the pressure Pc in the crank chamber, whereby the variable
displacement compressor can be promptly shifted to the minimum
capacity operation or the maximum capacity operation.
[0080] As describe above, according to the present invention, the
plunger of the solenoid is divided in two, with the
pressure-sensing member being disposed between them, for sensing
suction pressure, and one of the divisional plungers performs valve
opening control of the valve section for controlling the pressure
in the crank chamber. This makes it possible to construct
components ranging from the valve section to a portion where the
pressure-sensing member is disposed, including one of the plungers
which controls the valve lift of the valve section, as components
to which pressure is applied, and part of the solenoid exclusive of
one the plungers which controls the valve lift of the valve section
can be constructed as part open to the atmospheric pressure without
being accommodated in the pressure chamber.
[0081] Further, when the solenoid is not energized, the
pressure-sensing member is moved away from one of the plungers
which controls the valve lift of the valve section, so that the
displacement of the pressure-sensing member is not transmitted to
the valve section, and at the same time, the valve section is held
in a fully open state. This makes it possible to control the
variable displacement compressor to the minimum capacity without
using an electromagnetic clutch.
[0082] The foregoing is considered as illustrative only of the
principles of the present invention. Further, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and applications shown and described, and accordingly,
all suitable modifications and equivalents may be regarded as
falling within the scope of the invention in the appended claims
and their equivalents.
* * * * *