U.S. patent application number 10/664961 was filed with the patent office on 2004-03-25 for capacity control valve for variable displacement compressor.
This patent application is currently assigned to TGK CO., LTD.. Invention is credited to Hirota, Hisatoshi.
Application Number | 20040057840 10/664961 |
Document ID | / |
Family ID | 31973268 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040057840 |
Kind Code |
A1 |
Hirota, Hisatoshi |
March 25, 2004 |
Capacity control valve for variable displacement compressor
Abstract
The object of the present invention is to provide a capacity
control valve for a variable displacement compressor that controls
flow rate without the need for increased solenoid power. A compact,
low-cost capacity control valve is provided as an integrated
structure of a first control valve and a second control valve. The
first control valve, placed on a passageway of refrigerant
discharged from a variable displacement compressor, functions as a
variable orifice whose cross-sectional area can be set as desired
by varying the power of a solenoid unit. Part of the refrigerant
discharged at pressure PdH is supplied to the crank chamber, in
which the pressure is Pc. The second control valve controls this
refrigerant flow to the crank chamber in such a way that the
differential pressure between upstream pressure PdH and downstream
pressure PdL of the discharged refrigerant will be regulated at a
specified level. This arrangement makes it possible to reduce the
size of the solenoid unit because the first control valve does not
need a large force to yield a small differential pressure that is
required for operation.
Inventors: |
Hirota, Hisatoshi; (Tokyo,
JP) |
Correspondence
Address: |
ARMSTRONG, KRATZ, QUINTOS, HANSON & BROOKS, LLP
1725 K STREET, NW
SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
TGK CO., LTD.
Tokyo
JP
|
Family ID: |
31973268 |
Appl. No.: |
10/664961 |
Filed: |
September 22, 2003 |
Current U.S.
Class: |
417/222.2 |
Current CPC
Class: |
F04B 2027/185 20130101;
F04B 2027/1854 20130101; F04B 27/1804 20130101; F04B 49/225
20130101; F04B 2027/1813 20130101; F04B 2027/1827 20130101; F04B
2027/1872 20130101 |
Class at
Publication: |
417/222.2 |
International
Class: |
F04B 001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 25, 2002 |
JP |
2002-278764 |
Claims
What is claimed is:
1. A capacity control valve for a variable displacement compressor
that regulates a flow rate of refrigerant discharged by the
variable displacement compressor, comprising: a first control valve
that sets a specific cross-sectional area of a refrigerant
passageway that leads to a suction chamber or a discharge chamber
of the variable displacement compressor; a second control valve
that senses differential pressure developed across the first
control valve and controls a flow rate of refrigerant supplied to
or coming out of a crank chamber of the variable displacement
compressor in such a way that the differential pressure will be
maintained at a specified level; and a solenoid unit that actuates
the first control valve to set the cross-sectional area of the
refrigerant passageway according to variations in a given external
condition, wherein the first control valve, second control valve,
and solenoid unit are integrally formed.
2. A capacity control valve for a variable displacement compressor
that regulates a flow rate of refrigerant discharged by the
variable displacement compressor, comprising: a first control valve
that sets a specific cross-sectional area of a refrigerant
passageway that leads to a suction chamber or a discharge chamber
of the variable displacement compressor; a second control valve and
a third control valve that sense differential pressure developed
across the first control valve and respectively control flow rates
of refrigerant supplied to and coming out of a crank chamber of the
variable displacement compressor in such a way that the
differential pressure will be maintained at a specified level; and
a solenoid unit that actuates the first control valve to set the
cross-sectional area of the refrigerant passageway according to
variations in a given external condition, wherein the first,
second, and third control valves and solenoid unit are integrally
formed.
3. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway leading from the discharge chamber, and
a first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, actuated by
an upstream force that is produced and controlled by the solenoid
unit while being urged by a downstream force in a valve-closing
direction; and the second control valve comprises: a second valve
seat formed as part of a passageway that leads from the upstream
end of the first control valve to the crank chamber, a second valve
element located opposite the second valve seat, allowed to move
upstream toward and downstream away from the second valve seat
while being urged by upstream-end pressure of the first control
valve, and a piston receiving downstream-end pressure of the first
control valve and impelling the second valve element in a
valve-closing direction with the received downstream-end
pressure.
4. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway leading from the discharge chamber, and
a first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, actuated by
a downstream force that is produced and controlled by the solenoid
unit while being urged in a valve-closing direction when the
solenoid unit is de-energized; and the second control valve
comprises: a second valve seat formed as part of a passageway that
leads from the upstream end of the first control valve to the crank
chamber, a second valve element located opposite the second valve
seat, allowed to move upstream toward and downstream away from the
second valve seat while being urged by upstream-end pressure of the
first control valve, and a piston receiving downstream-end pressure
of the first control valve and impelling the second valve element
in a valve-closing direction with the received downstream-end
pressure.
5. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway leading from the discharge chamber, and
a first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move downstream toward and upstream away from the first valve seat
while being forced in a valve-opening direction, actuated by a
force that is produced and controlled by the solenoid unit; the
second control valve comprises: a second valve seat formed as part
of a passageway that leads from the downstream end of the first
control valve to the crank chamber, a second valve element located
opposite the second valve seat, allowed to move upstream toward and
downstream away from the second valve seat while receiving
downstream-end pressure of the first control valve, and a piston
receiving, on one endface thereof, upstream-end pressure of the
first control valve and thereby impelling the second valve element
in a value-closing direction; and the capacity control valve
further comprises a communication hole between the first and second
control valves to connect a space adjacent to the pressure
receiving endface of the piston with an upstream-end space of the
first control valve.
6. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a spool valve disposed in the
refrigerant passageway coming from the discharge chamber,
comprising a spool-shaped first valve element, and a pressure
responsive piston that is integrally formed with, and has the same
diameter as, the first valve element of the spool valve, having a
pressure balancing hole therethrough to cause an endface thereof
remote from the first valve element to receive valve hole pressure
of the spool valve; and the second control valve comprises: a
second valve seat formed as part of a passageway that leads from
the upstream end of the first control valve to the crank chamber, a
second valve element located opposite the second valve seat,
allowed to move downstream toward and upstream away from the second
valve seat, and a pressure responsive member integrally formed with
the second valve element, one end thereof serving as a first valve
seat receiving the first valve element of the spool valve,
impelling the second valve element in response to differential
pressure developed across the spool valve.
7. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a spool valve disposed in the
refrigerant passageway coming from the discharge chamber,
comprising a spool-shaped first valve element, and a pressure
responsive piston that is integrally formed with, and has the same
diameter as, the first valve element of the spool valve, having a
pressure balancing hole therethrough to cause valve hole pressure
of the spool valve to act on an endface of the pressure responsive
piston remote from the first valve element; and the second control
valve comprises: a second valve seat formed as part of a passageway
that leads from the downstream end of the first control valve to
the crank chamber, a second valve element located opposite the
second valve seat, allowed to move upstream toward and downstream
away from the second valve seat while being forced in a
valve-closing direction, and a pressure responsive member impelling
the second valve element through a valve hole thereof in response
to differential pressure developed across the spool valve, one end
of the pressure responsive member serving as a first valve seat
receiving the first valve element of the spool valve.
8. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve element with a
taper-shaped end, disposed in the refrigerant passageway coming
from the discharge chamber, being urged by a downstream force in a
valve-closing direction that is produced by the solenoid unit in
de-energized state; and the second control valve comprises: a
second valve seat formed as part of a passageway that leads from
the downstream end of the first control valve to the crank chamber,
a second valve element located opposite the second valve seat,
allowed to move upstream toward and downstream away from the second
valve seat while being forced in a valve-closing direction, and a
pressure responsive member impelling the second valve element
through a valve hole thereof in response to differential pressure
developed across the first control valve, one end of the pressure
responsive member serving as a first valve seat receiving the first
valve element of the first control valve.
9. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a taper valve with a first valve
element disposed in the refrigerant passageway coming from the
discharge chamber, being urged by a downstream force that is
produced by the solenoid unit in de-energized state and acts on the
first valve element in a valve-closing direction, a pressure
responsive piston integrally formed with the first valve element of
the taper valve, with the same diameter as a valve hole of the
taper valve, having a pressure balancing hole therethrough to cause
valve hole pressure of the taper valve to act on an endface of the
pressure responsive piston remote from the first valve element; and
the second control valve comprises: a second valve seat formed as
part of a passageway that leads from the downstream end of the
first control valve to the crank chamber, a second valve element
located opposite the second valve seat, allowed to move upstream
toward and downstream away from the second valve seat while being
forced in a valve-closing direction, and a pressure responsive
member impelling the second valve element through a valve hole
thereof in response to differential pressure developed across the
taper valve, one end of the pressure responsive member serving as a
first valve seat receiving the first valve element of the taper
valve.
10. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a plurality of first valve seats
formed as downstream-side edges of a plurality of valve holes, the
valve holes being arranged along a circle so as to constitute a
part of the refrigerant passageway coming from the discharge
chamber, and a plurality of ball-shaped first valve elements
disposed in a downstream-side space adjacent to the respective
first valve seats, being urged by an upstream force in a
valve-closing direction that is produced by the solenoid unit in
de-energized state; and the second control valve comprises: a
second valve seat formed as part of a passageway that leads from
the upstream end of the first control valve to the crank chamber, a
second valve element located opposite the second valve seat,
allowed to move downstream toward and upstream away from the second
valve seat, and a pressure responsive member integrally formed with
the second valve element, impelling the second valve element in
response to differential pressure developed across the first
control valve.
11. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as a
downstream-side edge of a doughnut-shaped valve hole, the valve
hole being hollowed so as to constitute a part of the refrigerant
passageway coming from the discharge chamber, a first valve element
located opposite the first valve seat, being urged by an upstream
force in a value-closing direction that is produced by the solenoid
unit in de-energized state; and the second control valve comprises:
a second valve seat formed as part of a passageway that leads from
the upstream end of the first control valve to the crank chamber, a
second valve element located opposite the second valve seat,
allowed to move downstream toward and upstream away from the second
valve seat, and a pressure responsive member integrally formed with
the second valve element, impelling the second valve element in
response to differential pressure developed across the first
control valve.
12. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a cylinder constituting a part of
the refrigerant passageway coming from the discharge chamber, the
downstream end thereof serving as a first valve seat, and a first
valve element located opposite the first valve seat, integrally
formed with a plunger of the solenoid unit, being urged by a force
in a valve-closing direction that is produced by the solenoid unit
in de-energized state; and the second control valve comprises: a
second valve seat formed as part of a passageway that leads from
the upstream end of the first control valve to the crank chamber, a
second valve element located opposite the second valve seat,
allowed to move downstream toward and upstream away from the second
valve seat, a pressure responsive piston integrally formed with the
second valve element, with the same diameter as a valve hole of the
second valve seat, a communication hole that propagates
upstream-end pressure of the first control valve to an endface of
the pressure responsive piston remote from the second valve
element, a sliding member slidably fitted on an outer surface of
the cylinder, and a diaphragm disposed between the sliding member
and a body, impelling the second valve element in response to
differential pressure developed across the first control valve.
13. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a cylinder constituting a part of
the refrigerant passageway coming from the discharge chamber, the
upstream end thereof serving as a first valve seat, and a first
valve element located opposite the first valve seat, being urged by
a force in a valve-closing direction that is produced by the
solenoid unit in de-energized state; and the second control valve
comprises: a second valve seat formed as part of a passageway that
leads from the upstream end of the first control valve to the crank
chamber, a second valve element located opposite the second valve
seat, allowed to move downstream toward and upstream away from the
second valve seat, and a sliding member slidably fitted on an outer
surface of the cylinder, and a diaphragm disposed between the
sliding member and a body, impelling the second valve element in
response to differential pressure developed across the first
control valve.
14. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway leading from the discharge chamber, and
a first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
and the second control valve comprises: a second valve seat formed
as part of a passageway that leads from the crank chamber to the
suction chamber, a second valve element located opposite the second
valve seat, allowed to move downstream toward and upstream away
from the second valve seat, a first piston integrally formed with
the second valve element, receiving upstream-end pressure of the
first control valve and impelling the second valve element in a
valve-closing direction with the received upstream-end pressure,
and a second piston integrally formed with the second valve
element, receiving downstream-end pressure of the first control
valve and impelling the second valve element in a valve-opening
direction with the received downstream-end pressure.
15. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway coming from the discharge chamber, and a
first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
and the second control valve comprises: a second valve seat formed
as part of a passageway that leads from the downstream end of the
first control valve to the crank chamber, a second valve element
located opposite the second valve seat, allowed to move upstream
toward and downstream away from the second valve seat, a piston
integrally formed with the second valve element, having
substantially the same diameter as a valve hole of the second valve
seat, receiving downstream-end pressure of the first control valve,
and a pressure responsive piston installed coaxially with the
second valve element, causing the second valve element to move in a
valve-opening direction in response to upstream-end pressure of the
first control valve, also causing the second valve element to move
in a valve-closing direction in response to the downstream-end
pressure of the first control valve.
16. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway coming from the discharge chamber, and a
first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
and the second control valve comprises: a second valve seat formed
as part of a passageway that leads from the crank chamber to the
suction chamber, a second valve element located opposite the second
valve seat, allowed to move downstream toward and upstream away
from the second valve seat, and first and second pistons formed
integrally and coaxially with the second valve element at both ends
thereof, the distal endfaces of the first and second pistons having
substantially equal areas to receive downstream-end pressure of the
first control valve, and a pressure responsive piston installed
coaxially with the second valve element, causing the second valve
element to move in a valve-closing direction in response to
upstream-end pressure of the first control valve, also causing the
second valve element to move in a valve-opening direction in
response to downstream-end pressure of the first control valve.
17. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway coming from the discharge chamber, and a
first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
and the second control valve comprises: a second valve seat formed
as part of a passageway that leads from the downstream end of the
first control valve to the crank chamber, a second valve element
located opposite the second valve seat, allowed to move upstream
toward and downstream away from the second valve seat, and a
pressure responsive piston installed coaxially with the second
valve element, causing the second valve element to move in a
valve-opening direction in response to upstream-end pressure of the
first control valve, also causing the second valve element to move
in a valve-closing direction in response to downstream-end pressure
of the first control valve.
18. The capacity control valve according to claim 1, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway coming from the discharge chamber, and a
first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
and the second control valve comprises: a second valve seat formed
as part of a passageway that leads from the crank chamber to the
suction chamber, a second valve element located opposite the second
valve seat, allowed to move downstream toward and upstream away
from the second valve seat, and a pressure responsive piston
installed coaxially with the second valve element, causing the
second valve element to move in a valve-closing direction in
response to upstream-end pressure of the first control valve, also
causing the second valve element to move in a valve-opening
direction in response to downstream-end pressure of the first
control valve.
19. The capacity control valve according to claim 2, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway coming from the discharge chamber, and a
first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
the second control valve comprises: a second valve seat formed as
part of a passageway that leads from the upstream end of the first
control valve to the crank chamber, and a second valve element
located opposite the second valve seat, allowed to move upstream
toward and downstream away from the second valve seat; and the
third control valve comprises: a third valve seat formed as part of
a passageway that leads from the crank chamber to the suction
chamber, a third valve element integrally formed with the second
valve element, located opposite the third valve seat, allowed to
move downstream toward and upstream away from the third valve seat,
and a piston integrally formed with the third valve element,
receiving downstream-end pressure of the first control valve and
impelling the second valve element in a valve-closing direction and
the third valve element in a valve-opening direction with the
received downstream-end pressure.
20. The capacity control valve according to claim 2, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway coming from the discharge chamber, and a
first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
the second control valve comprises: a second valve seat formed as
part of a passageway that leads from the downstream end of the
first control valve to the crank chamber, and a second valve
element located opposite the second valve seat, allowed to move
upstream toward and downstream away from the second valve seat; and
the third control valve comprises: a third valve seat formed as
part of a passageway that leads from the crank chamber to the
suction chamber, a third valve element integrally formed with the
second valve element, located opposite the third valve seat,
allowed to move downstream toward and upstream away from the third
valve seat, a piston integrally formed with the third valve
element, receiving downstream-end pressure of the first control
valve and impelling the second valve element in a valve-closing
direction and the third valve element in a valve-opening direction
with the received downstream-end pressure, and a pressure
responsive piston installed coaxially with the second and third
valve elements, actuating the second valve element in a
valve-opening direction and the third valve element in a
valve-closing direction in response to upstream-end pressure of the
first control valve, also actuating the second valve element in the
valve-closing direction and the third valve element in the
valve-opening direction in response to downstream-end pressure of
the first control valve.
21. The capacity control valve according to claim 2, wherein: the
first control valve comprises: a first valve seat formed as part of
the refrigerant passageway coming from the discharge chamber, a
first valve element located opposite the first valve seat to set
the cross-sectional area of the refrigerant passageway, allowed to
move upstream toward and downstream away from the first valve seat,
actuated by a downstream force that is produced and controlled by
the solenoid unit while being forced in a valve-closing direction;
the second control valve comprises: a second valve seat formed as
part of a passageway that leads from the downstream end of the
first control valve to the crank chamber, and a second valve
element located opposite the second valve seat, allowed to move
upstream toward and downstream away from the second valve seat; and
the third control valve comprises: a third valve seat formed as
part of a passageway that leads from the crank chamber to the
suction chamber, a third valve element integrally formed with the
second valve element, located opposite the third valve seat,
allowed to move downstream toward and upstream away from the third
valve seat, and a pressure responsive piston installed coaxially
with the second and third valve elements, causing the second valve
element move in a valve-opening direction and the third valve
element in a valve-closing direction in response to upstream-end
pressure of the first control valve, also causing the second valve
element to move in the valve-closing direction and the third valve
element in the valve-opening direction in response to
downstream-end pressure of the first control valve.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS, IF ANY:
[0001] This application claims priority of Japanese Application No.
2002-278764 filed on Sep. 25, 2002 and entitled "Capacity Control
Valve for Variable Displacement Compressor".
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] The present invention relates to a capacity control valve
for a variable displacement compressor, and more particularly to a
capacity control valve that regulates a flow of refrigerant
discharged by a variable displacement compressor.
[0004] (2) Description of the Related Art
[0005] Automotive air conditioning systems employ a compressor to
compress refrigerant gases in their refrigeration cycle. Since the
compressor is driven by the automobile engine, the air conditioning
system is unable to vary compressor rotation speed to control its
output. To obtain a required cooling capacity without being
restricted by the engine speed, the system uses a variable
displacement compressor designed to be able to change the capacity
(i.e., the amount of refrigerant that it can discharge) on its
own.
[0006] In a variable displacement compressor, a wobble plate (swash
plate) is fitted obliquely on the compressor's drive shaft, which
is rotated by the engine. Rotation of this inclined wobble plate
produces displacement of pistons that are linked to that plate,
where the resulting piston strokes depends on the inclination angle
of the wobble plate. This means that the compressor capacity (i.e.,
the amount of refrigerant being discharged from the compressor) can
be varied by changing the wobble plate angle.
[0007] To control the wobble plate angle; part of the pressurized
refrigerant is introduced into the gastight crank chamber of the
compressor. Changing the crank chamber pressure creates a new state
of balance between opposing pressures exerted on the both ends of
each piston linked to the wobble plate, making it possible to vary
the wobble plate angle steplessly.
[0008] To change the crank chamber pressure, a capacity control
valve is installed either between the refrigerant outlet and the
crank chamber or between the refrigerant inlet and the crank
chamber. Capacity control valves are designed to open or close
themselves in such a way that a certain level of differential
pressure between their inlet and outlet will be maintained. More
specifically, one can set a desired differential pressure by
supplying a capacity control valve with an appropriate control
current from an external power source. When the engine speed rises,
the capacity control valve raises the pressure of refrigerant
supplied to the crank chamber so as to reduce the compressor
capacity. When in turn the engine slows down, the capacity control
valve decreases the crank chamber pressure so as to increase the
compressor capacity. In this way, the amount of refrigerant
discharged from the variable displacement compressor is
regulated.
[0009] One method to control capacity of the above variable
displacement compressors is disclosed in Unexamined Japanese Patent
Application Publication No. 2001-107854 (Paragraphs (0035) to
(0036), FIG. 3) This literature describes a capacity control valve
that regulates the flow of refrigerant being discharged from a
variable displacement compressor.
[0010] According to Unexamined Japanese Patent Application
Publication No. 2001-107854, the flow of refrigerant that is taken
into the suction chamber is determined indirectly by detecting
differential pressure between two pressure monitoring points with
sensors. The capacity control valve controls the flow of
refrigerant supplied from the discharge chamber to the crank
chamber such that the intake flow rate will be maintained at a
constant level, thereby regulating the flow of refrigerant
discharged from the compressor.
[0011] The capacity control valve that controls a flow in the way
described in Unexamined Japanese Patent Application Publication No.
2001-107854 needs sensors to detect differential pressure, as well
as a controller to control the capacity control valve accordingly.
Those extra components push up the cost of variable displacement
compressor.
[0012] Another noteworthy aspect of automobile air conditioning
systems is what kind of refrigerant to choose for their
refrigeration cycles. While HFC-134a, a chlorofluorocarbon
alternative, is widely used for that purpose as of this point in
time, the recent development of supercritical refrigeration cycles
using, for example, carbon dioxide poses another challenge to the
compressor design. The new refrigeration cycle requires refrigerant
to function in a region that exceeds its critical temperature,
hence the supercritical refrigeration. Let us think of a
refrigeration cycle using carbon dioxide as refrigerant in which a
capacity control valve is employed to control crank chamber
pressure according to the compressor's discharge pressure. In this
case, the differential pressure between the refrigerant outlet and
crank chamber could become extremely high because the refrigerant
has to be pressurized up to its supercritical region. This means
that a high-power solenoid actuator will be needed to produce a
sufficiently large force to deal with the high differential
pressure, which leads to increased size and cost of the capacity
control valve.
SUMMARY OF THE INVENTION
[0013] In view of the foregoing, it is an object of the present
invention to provide a compact capacity control valve for use with
a flow-controlled variable displacement compressor, which can be
applied not only to ordinary refrigeration cycles using HFC-134a,
but also to those using supercritical high-pressure refrigerant,
without the needs for high-power solenoids or extra pressure
sensors.
[0014] To solve the above-described problems, the present invention
provides a capacity control valve that regulates a flow of
refrigerant discharged from a variable displacement compressor.
This capacity control valve comprises the following components
formed in an integrated way: a first control valve that sets a
specific cross-sectional area of a refrigerant passageway that
leads to a suction chamber or a discharge chamber of the variable
displacement compressor; a second control valve that senses
differential pressure developed across the first control valve and
controls a flow of refrigerant supplied to or coming out of the
crank chamber of the variable displacement compressor in such a way
that the differential pressure will be maintained at a specified
level; and a solenoid unit that actuates the first control valve to
set the cross-sectional area of the refrigerant passageway
according to variations in a given external condition.
[0015] 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
[0016] FIG. 1 is a sectional view of a variable displacement
compressor.
[0017] FIG. 2 is a detailed sectional view of a capacity control
valve for a variable displacement compressor according to the first
embodiment
[0018] FIG. 3 is a sectional view of a capacity control valve for a
variable displacement compressor according to the second
embodiment.
[0019] FIG. 4 is a sectional view of a capacity control valve for a
variable displacement compressor according to the third
embodiment.
[0020] FIG. 5 is a sectional view of a capacity control valve for a
variable displacement compressor according to the fourth
embodiment.
[0021] FIG. 6 is a sectional view of a capacity control valve for a
variable displacement compressor according to the fifth
embodiment.
[0022] FIG. 7 is a sectional view of a capacity control valve for a
variable displacement compressor according to the sixth
embodiment.
[0023] FIG. 8 is a sectional view of a capacity control valve for a
variable displacement compressor according to the seventh
embodiment.
[0024] FIG. 9 is a sectional view of a capacity control valve for a
variable displacement compressor according to the eighth
embodiment.
[0025] FIG. 10 is a sectional view of a capacity control valve for
a variable displacement compressor according to the ninth
embodiment.
[0026] FIG. 11 is a sectional view of a capacity control valve for
a variable displacement compressor according to the tenth
embodiment.
[0027] FIG. 12 is a sectional view of a capacity control valve for
a variable displacement compressor according to the eleventh
embodiment.
[0028] FIG. 13 is a sectional view of a capacity control valve for
a variable displacement compressor according to the twelfth
embodiment.
[0029] FIG. 14 is a sectional view of a capacity control valve for
a variable displacement compressor according to the thirteenth
embodiment.
[0030] FIG. 15 is a sectional view of a capacity control valve for
a variable displacement compressor according to the fourteenth
embodiment.
[0031] FIG. 16 is a sectional view of a capacity control valve for
a variable displacement compressor according to the fifteenth
embodiment.
[0032] FIG. 17 is a sectional view of a capacity control valve for
a variable displacement compressor according to the sixteenth
embodiment.
[0033] FIG. 18 is a sectional view of a capacity control valve for
a variable displacement compressor according to the seventeenth
embodiment.
[0034] FIG. 19 is a sectional view of a capacity control valve for
a variable displacement compressor according to the eighteenth
embodiment.
[0035] FIG. 20 is a sectional view of a capacity control valve for
a variable displacement compressor according to the nineteenth
embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Embodiments of the present invention will now be described
below with reference to the accompanying drawings. The description
will illustrate capacity control valves for use with a
flow-controlled variable displacement compressor that is supposed
to discharge refrigerant at a regulated flow rate.
[0037] FIG. 1 is a sectional view of a variable displacement
compressor.
[0038] The explanation will begin with the overall structure of the
variable displacement compressor 1 of FIG. 1.
[0039] The illustrated variable displacement compressor 1 is
composed of the following three sections: a driving section 100
that receives drive power from a vehicle engine (not shown); a
refrigerant compressing section 200 including a gastight crank
chamber; and a capacity controlling section 300 that controls
discharge capacity. The variable displacement compressor 1 has an
outlet port 1a, which is connected to a condenser (or gas cooler) 3
through a high-pressure refrigerant line 2. The refrigerant is then
routed from the condenser 3 to an expansion valve 4, an evaporator
5, and a low-pressure refrigerant line 6 in that order, and finally
returns to the inlet port 1b of the variable displacement
compressor 1, thus forming a closed circuit for refrigeration
cycle.
[0040] The driving section 100 is constructed such that the
rotational power of the engine can be transmitted from a drive
pulley 13 to a bracket 14, and then to a rotating shaft 12 that
protrudes out of a front housing 11. In the refrigerant compressing
section 200, the crank chamber 15 is formed as a closed space
surrounded by a front housing 11 and a cylinder block 16. The
rotating shaft 12 is rotatably installed in the crank chamber 15,
across the length of the front housing 11 and cylinder block
16.
[0041] The drive pulley 13 is rotatably supported by an angular
bearing 17 at the front housing 11. A drive belt (not shown) is
installed around the circumference of the drive pulley 13. The
bracket 14, which rotates together with the drive pulley 13, is
coupled to one end of the rotating shaft 12 that protrudes from the
front housing 11. As can be seen, the rotation of the vehicle
engine is directly transmitted to the variable displacement
compressor 1, with no intervening clutch mechanisms (e.g.,
electromagnetic clutch) between them.
[0042] To seal off the crank chamber 15 from the exterior space of
the refrigerant compressing section 200, a lip seal 18 is placed
between the front housing 11 and the front portion of the rotating
shaft 12. The rotational support member 19 is fixed to the rotating
shaft 12 in the crank chamber 15. A swash plate 20 is supported in
such a way that it can be inclined at an oblique angle to the axis
of the rotating shaft 12. The swash plate 20 has a guide pin 22,
whose spherical top portion is engaged with a support arm 21 that
is mounted on the rotational support member 19 in a protruding
manner. This linkage between the support arm 21 and guide pin 22
enables the swash plate 20 to rotate together with the rotating
shaft 12.
[0043] Interposed between the rotational support member 19 and
swash plate 20 is an inclination-reducing spring 23, which urges
the swash plate 20 in the direction that its inclination angle is
reduced. The maximum swash plate angle is restricted by an
inclination-limiting protrusion 20a of the swash plate 20 itself,
which juts out toward the rotational support member 19.
[0044] The rotating shaft 12 is rotatably supported at its rear end
by a radial bearing 24 that is mounted at a central axis position
of the cylinder block 16.
[0045] The cylinder block 16 has a plurality of cylinder bores 16a
formed in a manner that they pass through the cylinder block 16.
Those cylinder bores 16a house a plurality of single-headed pistons
25 (hereafter, "pistons"), one for each. The swash plate 20 engages
with the head of each piston 25 via shoes 26, which permits
rotational motion of the swash plate 20 to be converted into
reciprocating motion of the pistons 25. Placed between the
rotational support member 19 and front housing 11 is a thrust
bearing 28, which receives reaction forces that are caused by the
compression of refrigerant and act on the rotational support member
19 via the pistons 25 and swash plate 20.
[0046] The capacity controlling section 300 is attached to the
refrigerant compressing section 200, with a valve plate 27
separating them. The capacity controlling section 300 is made up of
a rear housing 31 located next the valve plate 27 and a capacity
control valve 30 (described later) installed and secured in a
predetermined position in the rear housing 31. The rear housing 31
provides the following separate cavities formed immediately beside
the valve plate 27: suction chambers 32, discharge chambers 33, and
a communication passage 34. The suction chambers 32 are cavities at
suction pressure Ps. The discharge chambers 33 at discharge
pressure PdH receive the refrigerant compressed by the refrigerant
compressing section 200. The communication passage 34 communicates
with the crank chamber, and hence is at crank chamber pressure Pc.
In addition, the rear housing 31 provides an outlet port 1a and an
inlet port 1b of the variable displacement compressor 1, as well as
a housing cavity 35 for accommodating the capacity control valve
30. Further, the rear housing 31 has several communication holes 36
to 39 formed in its body. The first communication hole 36 connects
the inlet port 1b with the suction chambers 32. The second
communication hole 37 connects the housing cavity 35 with the
communication passage 34, which further leads to the crank chamber
15. The housing cavity 35 can also communicate with the discharge
chamber 33 through the third communication hole 38. The fourth
communication hole 39 permits the housing cavity 35 to communicate
with the outlet port 1a of the variable displacement compressor
1.
[0047] A suction relief valve 32v is placed at each cylinder port
connecting to the suction chamber 32, on the side of the valve
plate 27 adjacent to the cylinder bores 16a. A discharge relief
valve 33v is placed similarly at each cylinder port connecting to
its corresponding discharge chambers 33, but on the opposite side
of the valve plate 27, remote from the cylinder bores 16a. The
suction chambers 32, one for each cylinder bore 16a, communicate
with each other in the rear housing 31, as well as with the first
communication hole 36. Likewise, the discharge chambers 33
communicate with each other in the rear housing 31, as well as with
the third communication hole 38. As the pistons 25 reciprocate, the
refrigerant gas in the suction chamber 32 is sucked into each
cylinder bore 16a through its corresponding suction relief valve
32v and then discharged from those cylinder bores 16a to their
corresponding discharge chambers 33 through respective discharge
relief valves 33v.
[0048] While not shown in FIG. 1, there is a fixed orifice between
the crank chamber 15 and suction chambers 32 to release the
refrigerant from the crank chamber 15 to the suction chambers
32.
[0049] The following will now describe several specific examples of
the proposed capacity control valve for a variable displacement
compressor.
[0050] First Embodiment
[0051] FIG. 2 is a detailed sectional view of a capacity control
valve for a variable displacement compressor according to the first
embodiment.
[0052] This capacity control valve 30 is made up of a first control
valve 30A, a second control valve 30B, and a solenoid unit 30C.
[0053] The first control valve 30A has two ports 41 and 42 formed
on its body 40. One port 41 receives a discharge pressure PdH from
the discharge chambers 33 through the third communication hole 38
of the rear housing 31 shown in FIG. 1. The other port 42 outputs
refrigerant at discharge pressure PdL that has been reduced at the
first control valve 30A, for delivery through the fourth
communication hole 39 and then the high-pressure refrigerant line
2. Bored between those two ports 41 and 42 is a valve hole 45 for
communication of refrigerant, the upstream edge of which is
intended to function as a first valve seat 45a. In an upstream
space adjacent to the first valve seat 45a, a ball-shaped valve
element (ball valve element) 46 is placed opposite to the first
valve seat 45a. This ball valve element 46 is referred to herein as
the first valve element. The valve hole space communicating with
the port 41 accommodates a coil spring 48 that urges the ball valve
element 46 in the direction that it closes the passage, and the
amount of that spring load can be adjusted by turning an adjustment
screw 47, which is screwed into the body 40.
[0054] The downstream side of the ball valve element 46 is in
contact with one end of a shaft 49 that extends in the axial
direction of the solenoid unit 30C through the valve hole of the
first valve seat 45a. This shaft 49 is supported by a bearing 50a
formed in the body 40, and the bearing 50a has a communication hole
50b to equalize the inside pressure of the solenoid unit 30C with
the discharge pressure PdL.
[0055] The solenoid unit 30C contains a solenoid coil 51 that has a
cylindrical cavity, in which a sleeve 52 is fitted. As the fixed
core of the solenoid actuator, a core 53 is pressed into the sleeve
52 through its opening end adjacent to the first control valve 30A.
The sleeve 52 also contains a plunger 54 that can slide in its
axial direction while being urged by a coil spring 55 in the
downward direction as viewed in FIG. 2. The plunger 54 is fixed to
the lower end (as viewed in FIG. 2) of the shaft 49 running
coaxially through the core 53. This arrangement permits the
capacity control valve 30 to operate as follows. When the solenoid
coil 51 is in de-energized state, the plunger 54 is set away from
the core 53 due to the force of the coil spring 55, causing the
shaft 49 extending from the plunger 54 to lose contact with the
ball valve element 46. As a result, the first control valve 30A
becomes fully closed because the freed ball valve element 46 is
seated on the first valve seat 45a, being urged by another coil
spring 48. When, on the other hand, the solenoid coil 51 is
energized, the plunger 54 attracted by the magnetized core 53 will
pushes the ball valve element 46 via the shaft 49 in the
valve-opening direction (i.e., in the direction that the valve
element will leave its corresponding valve seat). The ball valve
element 46 thus moves, and the amount of this movement, or the
valve lift (or openness), is proportional to the electrical current
being supplied to the solenoid coil 51. This means that the control
current given to the solenoid coil 51 determines the
cross-sectional area of the refrigerant passageway that the first
control valve 30A provides. In other words, the first control valve
30A functions as a variable orifice, which changes its
cross-sectional size as specified by the control current to allow
the discharged refrigerant to pass through it.
[0056] The solenoid unit 30C described above is intended, not for
directly controlling high-pressure refrigerant flow, but for
controlling the first control valve 30A so that a small
differential pressure will be produced depending on the discharge
flow rate Qd of the refrigerant passing therethrough. Since only a
small power is needed to achieve the purpose, it is possible to
reduce the size of the solenoid unit 30C.
[0057] The second control valve 30B has a body 40a, which is
screwed to the body 40 of the first control valve 30A so that the
two valves 30A and 30B are stacked in series. The body 40a has two
ports 43 and 44. One port 43 is used to apply controlled pressure
Pc to the crank chamber, and the other port 44 is used to introduce
discharge pressure PdL that has been reduced at the first control
valve 30A. The body 40a also has an opening at its bottom end,
which communicates with the port 41 to receive discharge pressure
PdH of the discharge chambers 33 through a communication hole 47a
formed on an adjustment screw 47. Between this opening and the port
43, a second valve seat 56 is formed as an integral part of the
body 40a. Placed opposite to this second valve seat 56 in the port
43 is a second valve element 57. The second valve element 57 is a
taper-shaped member that is integrally formed with a cylindrical
piston 58, where the piston 58 can move in its axial direction
within a cylinder that is bored on the axis of the body 40a. A coil
spring 60 is installed at the upper end portion of the piston 58 as
viewed in FIG. 2, which urges the second valve element 57 in the
valve-closing direction. This spring load depends on how much an
adjustment screw 59 is screwed into the body 40a. The adjustment
screw 59 has a through hole 59a at its central position, and this
through hole 59a serves as a passage for introducing the reduced
discharge pressure PdL from the port 44 to the space above the
piston 58. The second valve element 57 and piston 58 thus receive
different pressures at their both endfaces apart in the direction
of their axis. That is, the second valve element 57 receives
discharge pressure PdH from its nearest port 41, while the piston
58 receives discharge pressure PdL from its nearest port 44. Their
differential pressure .DELTA.P determines the lift of the second
valve element 57. More specifically, differential pressure .DELTA.P
is produced when refrigerant flows through a passage with a certain
cross-sectional area that is determined by the first control valve
30A. Then the second control valve 30B functions as a constant
differential pressure valve that controls the amount of refrigerant
flowing into the crank chamber 15 in such a way that the above
differential pressure .DELTA.P will be maintained at a constant
level.
[0058] Several O-rings are provided around the periphery of the
capacity control valve 30. They include: an O-ring 29a to seal up
the gap between the ports 44 and 43, another O-ring 29b between the
ports 43 and 41, yet another O-ring 29c between the ports 41 and
42, still another O-ring 29d between the port 42 and solenoid unit
30C, and yet another O-ring 29e to seal the solenoid unit 30C off
from the surrounding atmosphere.
[0059] The variable displacement compressor 1 described above
operates as follows. When the rotating shaft 12 is driven by the
engine power, the swash plate 20 begins to wobble while turning
around that rotating shaft 12. This wobbling produces reciprocating
motion of the pistons 25 that are linked to the outer regions of
the swash plate 20, which causes refrigerant to be sucked from the
suction chambers 32 into the cylinder block 16. The refrigerant is
thus compressed and discharged toward the discharge chambers
33.
[0060] Suppose here that the solenoid unit 30C is in de-energized
state. Since the first control valve 30A is fully closed in this
state, the refrigerant discharged to the discharge chambers 33 is
entered to the crank chamber 15 in its entirety via the second
control valve 30B. This causes the variable displacement compressor
1 to run in the minimum capacity mode.
[0061] When a predetermined amount of control current is supplied
to the solenoid unit 30C, the first control valve 30A gives a
predetermined openness (valve lift) associated with that control
current. The first control valve 30A now acts as an orifice with a
certain cross-sectional size, allowing a flow of refrigerant
through the high-pressure refrigerant line 2 leading to the
condenser 3. This develops a certain amount of differential
pressure .DELTA.P (=PdH-PdL) across the orifice, depending on the
actual discharge flow rate Qd of the refrigerant passing through
it.
[0062] In the second control valve 30B, its second valve element 57
and piston 58 are responsive to the differential pressure .DELTA.P
across the first control valve 30A, which is functioning here as an
orifice. The second control valve 30B controls the flow of
refrigerant from the discharge chambers 33 to the crank chamber 15
in such a way that the differential pressure .DELTA.P will be
maintained at a constant level. This control action may vary the
capacity of the variable displacement compressor 1 as needed, so as
to regulate the flow of refrigerant being discharged therefrom.
[0063] The flow rate of refrigerant discharged from the variable
displacement compressor 1 is determined depending on how much
refrigeration capacity is required in the present refrigeration
cycle. Actually, the refrigeration capacity is calculated from
various parameters, which include: engine rotation speed, vehicle
speed, accelerator pedal position, indoor and outdoor temperatures,
set temperatures, and monitoring signals supplied from various
temperature and pressure sensors. The amount of the electrical
current that energizes the solenoid coil 51 is determined on the
basis of this calculation result.
[0064] Suppose here that the engine rotation rises and the
discharge flow rate of refrigerant is increased accordingly. This
develops an increased differential pressure .DELTA.P across the
first control valve 30A. In response to .DELTA.P, the second
control valve 30B lifts its valve element, so that more refrigerant
will be supplied from the discharge chambers 33 to the crank
chamber 15. As a result, pressure Pc in the crank chamber 15 rises,
and the variable displacement compressor 1 is thus controlled in an
output-reducing condition. The variable displacement compressor 1
now operates with a smaller discharge capacity, suppressing the
discharge flow rate of refrigerant, and thus reducing the
differential pressure .DELTA.P. In this way, the discharge flow
rate Qd of refrigerant is regulated by controlling the second
control valve 30B so that the differential pressure across the
orifice (i.e., the first control valve 30A being configured as a
proportional solenoid valve) will be maintained at a constant
level.
[0065] The engine rotation may in turn drops. This decreases the
flow rate of discharged refrigerant and reduces the differential
pressure across the first control valve 30A accordingly. The
refrigerant discharge pressure PdH falls, and thus the second
control valve 30B operates in such a way as to reduce the
refrigerant flow from the discharge chambers 33 to the crank
chamber 15. Pressure Pc in the crank chamber 15 falls accordingly,
which causes the variable displacement compressor 1 to operate in a
capacity-increasing condition, thus recovering the discharge. In
this way, the discharge flow rate Qd of refrigerant is maintained
at the constant level.
[0066] As can be seen from the above description, the present
invention provides a capacity control valve 30 for use with a
variable displacement compressor. This capacity control valve 30 is
composed of a first control valve 30A that functions as a variable
orifice controlled by a solenoid unit 30C and a second control
valve 30B that controls the pressure in the crank chamber 15 so as
to maintain a constant differential pressure across the variable
orifice. The present invention combines those components in an
integrated way, thus providing a compact, space-saving design for
the capacity control functions (i.e., regulating the flow rate Qd
of refrigerant discharged from the variable displacement compressor
1).
[0067] Second Embodiment
[0068] FIG. 3 is a sectional view of a capacity control valve for a
variable displacement compressor according to the second embodiment
of the invention. Since many of the valve components shown in FIG.
3 are identical or similar to those discussed in FIG. 2, the same
reference numerals are used in FIG. 3 to designate such components,
and the following section will not provide details about them.
[0069] The illustrated capacity control valve 30 of the second
embodiment resembles that of the first embodiment (FIG. 2) in that
they share the same basic structure of their first control valve
30A and second control valve 30B, as well as in that the two valves
30A and 30B are stacked in series. The second embodiment is,
however, different from the first embodiment in that the ball valve
element 46 of its first control valve 30A is arranged in such a way
that it will allow more refrigerant to pass through when it is
displaced following the stream of refrigerant. In other words, the
ball valve element 46, or the first valve element, is placed on the
downstream side with respect to the first valve seat 45a. To make
this arrangement possible, the plunger 54 and core 53 have to swap
their positions in the solenoid unit 30C.
[0070] The first control valve 30A stays in a fully closed position
when the solenoid unit 30C is not energized, because the ball valve
element 46 is seated on the first valve seat 45a due to the force
of a coil spring 55 installed between the plunger 54 and core 53.
Accordingly, the refrigerant coming into the port 41 at discharge
pressure PdH is led to the crank chamber 15 in its entirety through
the second control valve 30B, meaning that the variable
displacement compressor 1 now operates in the minimum capacity
condition.
[0071] When a predetermined amount of control current is supplied
to a solenoid coil 51 of the solenoid unit 30C, the plunger 54 is
attracted by the core 53 and stops at the point where the
attraction force associated with that control current comes into
balance with the urging force of the coil spring 55. In this state,
the ball valve element 46 is lifted, keeping in contact with the
shaft 49 due to the force of the coil spring 48, and the consequent
gap serves as an orifice with a designated size.
[0072] Variations in the engine speed affect the discharge flow
from the variable displacement compressor. In this situation, the
capacity control valve 30 of the second embodiment operates in the
same way as in the first embodiment described earlier in FIG.
2.
[0073] Third Embodiment
[0074] FIG. 4 is a sectional view of a capacity control valve for a
variable displacement compressor according to a third embodiment of
the invention. Since many of the valve components shown in FIG. 4
are identical or similar to those discussed in FIGS. 2 and 3, the
same reference numerals are used in FIG. 4 to designate such
components, and the following section will not provide details
about them.
[0075] Recall that a ball valve element 46 is used as the first
valve element in the first and second embodiments (FIGS. 2 and 3).
However, the illustrated capacity control valve 30 of the third
embodiment is different in that a taper-shaped valve element 61 is
placed on the upstream side with respect to the first valve seat
45a while receiving a force in the valve-opening direction. Another
difference is that it eliminates the port 44, which is employed in
the first and second embodiments to introduce discharge pressure
PdL into the second control valve 30B. Instead, the illustrated
capacity control valve 30 has a communication hole 62 formed in the
body 40 to serve the purpose. To make this arrangement possible,
the port 41 for discharge pressure PdH and port 42 for discharge
pressure PdL have swapped their positions in the third embodiment.
Yet another difference is that the crank chamber 15 receives
discharge pressure PdL after orifice.
[0076] More specifically, the first control valve 30A has a port 41
formed in its body 40 to receive discharge pressure PdH from the
discharge chambers 33. It has another port 42 formed in the same
body 40 to supply the high-pressure refrigerant line 2 with
discharge pressure PdL that is reduced by the first control valve
30A. A valve hole 45 is bored for communication between those two
ports 41 and 42, and its upstream-side edge is intended to function
as a first valve seat 45a. A taper-shaped valve element 61 is
placed in an upstream-side space, opposite to the first valve seat
45a. This valve element 61 is referred to herein as a first valve
element. A flange 61a is formed as an integral part of the first
valve element 61, on its circumference remote from the first valve
seat 45a.
[0077] The flange 61a retains one end of a coil spring 48 that is
placed around the first valve element 61 against the first valve
seat 45a. This coil spring 48 urges the first valve element 61 in
the direction that the valve will open. The valve element 61 is
also coupled to an end of a shaft 49 that extends from the solenoid
unit 30C in its axial direction. When the solenoid unit 30C is in
de-energized state, the coil spring 55 makes the first valve
element 61 sit on the first valve seat 45a. The shaft 49 is
supported by a bearing 50a at its middle portion adjacent to the
first control valve 30A, as well as by another bearing 50c at its
bottom end. The bottom-end bearing 50c has been pressed into the
central bore of the core 53.
[0078] The second control valve 30B is coupled in series with the
first control valve 30A, the space above the piston 58 being closed
by a lid 59b. Its body 40 has a communication hole 62 to
communicate that space with the port 41, through which discharge
pressure PdH acts on the back face of the piston 58. This
arrangement of the third embodiment reduces the number of ports
that should be created on the body 40, thus making it easier to
manufacture the capacity controlling section 300 of a variable
displacement compressor 1. It also eliminates some O-rings that are
required when fitting the capacity control valve 30 into the
housing cavity 35 of the variable displacement compressor 1.
[0079] As can be seen from the above description, the illustrated
capacity control valve 30 contains a first control valve 30A
composed of a first valve element 61 and first valve seat 45a, the
first valve element 61 being a taper-shaped valve element located
in an upstream-side space adjacent to the first valve seat 45a.
Here, the first control valve 30A sets a certain cross-section area
for the refrigerant passageway in accordance with how much the
solenoid unit 30C is energized. The second control valve 30B is
responsive to differential pressure developed across the first
control valve 30A to control the flow rate of refrigerant supplied
from the discharge chambers 33 to the crank chamber 15. In the way
described above, the capacity control valve 30 regulates the flow
rate Qd of refrigerant that the variable displacement compressor 1
discharges.
[0080] Fourth Embodiment
[0081] FIG. 5 is a sectional view of a capacity control valve for a
variable displacement compressor according to a fourth embodiment
of the invention. Since many of the valve components shown in FIG.
5 are identical or similar to those discussed in FIG. 2, the same
reference numerals are used in FIG. 5 to designate such components,
and the following section will not provide details about them.
[0082] Compared with the first embodiment discussed earlier in FIG.
2, the capacity control valve 30 of the fourth embodiment is
distinct in the following points. First, its first control valve
30A employs a spool-shaped valve element 63 as a first valve
element. Second, its second control valve 30B uses a taper-shaped
valve element 64 as a second valve element. Third, as the
counterpart of the spool-shaped valve element 63 (or first valve
element), a first valve seat 63a is provided as an integral part of
the second valve element in the second control valve 30B. This
first valve seat 63a is designed to set a required cross-section
area for refrigerant passage while moving together with the second
valve element.
[0083] More specifically, the second control valve 30B has a second
valve seat 56 and its corresponding second valve element 64 with a
tapered shape. The second valve seat 56 is formed as an integral
part of the body 40, in the middle of a refrigerant passageway
between two ports 41 and 43, the former receiving refrigerant from
the discharge chambers 33 and the latter delivering refrigerant to
the crank chamber 15. Opposite the second valve seat 56, the second
valve element 64 is located in an upstream-side space, where
discharge pressure PdH is available. The second valve element 64 is
urged by a coil spring 66 in the valve-opening direction.
Integrally formed with this second valve element 64 is a pressure
responsive member 64a, whose base portion detects differential
pressure between two different discharge pressures PdH and PdL. The
pressure responsive member 64a is installed inside the body 40 in a
manner that it can come in contact with or move away from the
second valve seat 56 according to the differential pressure acting
thereon. The pressure responsive member 64a has a central cavity
around its axis, the bottom end of which is open. The pressure
responsive member 64a has also a hole 64b in its upper portion,
which allows the discharge pressure PdH in the port 41 to reach the
central cavity.
[0084] The first control valve 30A, on the other hand, has a first
valve seat 63a formed around the rim of the bottom opening of the
pressure responsive member 64a, which operates together with a
spool-shaped valve element (or a first valve element) 63 located
below the bottom opening. The first valve seat 63a and first valve
element 63 set an appropriate cross-sectional area for a passageway
that delivers refrigerant from one port 41 to another port 42 via
the hole 64b of the pressure responsive member 64a.
[0085] The spool-shaped valve element 63, or the first valve
element, is integrally formed with a pressure responsive piston 63p
having the same cross-sectional area as the valve hole of the first
valve seat 63a. A flange 63b is formed around this valve element
63, on a downstream-side portion remote from the first valve seat
63a. This flange 63b is used to receive a force of a coil spring
48, which urges the valve element 63 in the value-opening
direction. Another coil spring 60 is disposed between the pressure
responsive piston 63p and the pressure responsive member 64a of the
second valve element 64. The pressure responsive piston 63p is
slidably supported by a plug 40b, which seals the bottom of the
body 40. The pressure responsive piston 63p may also be pressed
upward by a shaft 49. This shaft 49 extends from the solenoid unit
30C in its axial direction and reaches the bottom endface of the
pressure responsive piston 63p. A pressure balancing hole 65 is
bored through the pressure responsive piston 63p to introduce a
back pressure from the upstream-side cavity adjacent to the first
valve seat 63a. This structure permits the discharge pressure PdH
from the port 41 to act equally on both the bottom end of the
pressure responsive piston 63p and the top end of the spool-shaped
valve element 63. Since those two opposing forces cancel each other
out, the discharge pressure PdH never disturbs the solenoid unit
30C when it controls the position of the valve element 63.
[0086] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54 and shaft 49 upward
as viewed in FIG. 5, making the spool-shaped valve element 63 fit
into the central opening of the pressure responsive member 64a. The
first control valve 30A is fully closed in this state, while the
second control valve 30B fully opens itself in attempt to obtain a
predetermined differential pressure between discharge pressures PdH
and PdL acting on the pressure responsive member 64a.
[0087] When the solenoid unit 30C is energized, the shaft 49 moves
downward as viewed in FIG. 5. This movement of the shaft 49 allows
the spool-shaped valve element 63 to come out of the first valve
seat 63a and maintain a certain amount of gap between itself and
the first valve seat 63a. As a result, the refrigerant coming into
the port 41 at discharge pressure PdH begins flowing out of the
port 42 through the first control valve 30A. Then, in the second
control valve 30B, the pressure responsive member 64a of the second
valve element 64 receives differential pressure between discharge
pressures PdH and PdL, which moves the second valve element 64 so
that the differential pressure will become a predetermined level.
With this movement of the second valve element 64, the second
control valve 30B controls the refrigerant being delivered from its
port 43 to the crank chamber 15.
[0088] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. The increased differential pressure causes
the second valve element 64 to move in the valve-opening direction,
so that the second control valve 30B supplies more refrigerant into
the crank chamber 15. As a result of this control action, the
variable displacement compressor 1 operates with a smaller
displacement so as to recover its original discharge flow rate. If,
in turn, the refrigerant flowing through the first control valve
30A decreases, the second control valve 30B is actuated in a
valve-closing direction, thus reducing the refrigerant flowing into
the crank chamber 15. As a result of this control action, the
variable displacement compressor 1 operates with a larger
displacement so as to regulate the flow rate Qd of refrigerant that
it discharges.
[0089] Fifth Embodiment
[0090] FIG. 6 is a sectional view of a capacity control valve for a
variable displacement compressor according to a fifth embodiment of
the invention. Since many of the valve components shown in FIG. 6
are identical or similar to those discussed in FIG. 5, the same
reference numerals are used in FIG. 6 to designate such components,
and the following section will not provide details about them.
[0091] The capacity control valve 30 of the fifth embodiment is
similar to that of the fourth embodiment (FIG. 5) in that their
first control valve 30A employs a spool-shaped valve element 63 as
a first valve element. The fifth embodiment, however, is different
from the fourth embodiment in that the port 41 for discharge
pressure PdH and port 42 for discharge pressure PdL have swapped
their positions. While the second control valve 30B of the fourth
embodiment has a taper-shaped valve element 64 as a second valve
element, the fifth embodiment employs a ball valve element 67 for
that purpose. This ball valve element (or the second valve element)
67 is located downstream with respect to the second valve seat 56,
while being urged in the valve-opening direction by a stem that
extends through the valve hole and the first control valve 30A.
[0092] More specifically, the second control valve 30B has a second
valve seat 56 formed as an integral part of its body 40, and a ball
valve element 67 is located in a downstream-side space adjacent to
the second valve seat 56. The ball valve element 67 is urged by a
coil spring 60 in the valve-closing direction, the spring load of
which can be adjusted by turning an adjustment screw 59. The
adjustment screw 59 has a through hole 59a in its central portion,
and this through hole 59a serves as a port 43 for delivery of
refrigerant to the crank chamber 15.
[0093] The first control valve 30A has a first valve seat 63a at
the bottom end of a pressure responsive member 64a. The pressure
responsive member 64a is integrally formed with a shaft 68 that
extends in the axial direction of the second control valve 30B,
passing through the valve hole of same. The upper end of this shaft
68 is in contact with the ball valve element 67 of the second
control valve 30B.
[0094] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54 and shaft 49 in the
upward direction as viewed in FIG. 6, making the spool-shaped valve
element 63 fit into the central opening of the pressure responsive
member 64a. The first control valve 30A is fully closed in this
state, while the second control valve 30B is fully opened because
of the differential pressure that acts on the pressure responsive
member 64a.
[0095] When the solenoid unit 30C is energized, the shaft 49 moves
downward as viewed in FIG. 6. This movement of the shaft 49 allows
the spool-shaped valve element 63 to come out of the first valve
seat 63a and maintain a certain amount of gap between itself and
the first valve seat 63a. As a result, the refrigerant coming into
the port 41 at discharge pressure PdH begins flowing out of the
port 42 through the first control valve 30A. Then, in the second
control valve 30B, the pressure responsive member 64a receives
differential pressure between discharge pressures PdH and PdL,
which moves the ball valve element 67 so that the differential
pressure will become a predetermined level. With this movement of
the ball valve element 67, the second control valve 30B controls
the flow rate of the refrigerant being delivered from its port 43
to the crank chamber 15.
[0096] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. With the increased differential pressure,
the ball valve element 67 gives a greater openness, so that the
second control valve 30B supplies more refrigerant into the crank
chamber 15. As a result of this control action, the variable
displacement compressor 1 operates with a smaller displacement so
as to recover its original discharge flow rate. If, in turn, the
refrigerant flowing through the first control valve 30A decreases,
the second control valve 30B is actuated in a valve-closing
direction, thus reducing the refrigerant flowing into the crank
chamber 15. As a result of this control action, the variable
displacement compressor 1 operates with a larger displacement so as
to regulate the flow rate Qd of refrigerant that it discharges.
[0097] Sixth Embodiment
[0098] FIG. 7 is a sectional view of a capacity control valve for a
variable displacement compressor according to a sixth embodiment of
the invention. Since many of the valve components shown in FIG. 7
are identical or similar to those discussed in FIG. 2, 4, or 6, the
same reference numerals are used in FIG. 7 to designate such
components, and the following section will not provide details
about them.
[0099] As in the third embodiment (FIG. 4), the capacity control
valve 30 of the sixth embodiment is different from that of the
fifth embodiment (FIG. 6) in that its first control valve 30A
employs a taper-shaped valve element 61 as a first valve element,
and in that the valve element 61 is located in an upstream-side
space adjacent to the first valve seat 63a, being urged in the
valve-opening direction.
[0100] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54 and shaft 49 upward
as viewed in FIG. 7, making the taper-shaped valve element 61 sit
on the first valve seat 63a. The first control valve 30A is fully
closed in this state, while the second control valve 30B is fully
opened because of the differential pressure that acts on the
pressure responsive member 64a.
[0101] When the solenoid unit 30C is energized, the shaft 49 moves
downward as viewed in FIG. 7. This movement of the shaft 49 allows
the taper-shaped valve element 61 to leave the first valve seat 63a
and maintain a certain amount of gap between itself and the first
valve seat 63a. As a result, the refrigerant coming into the port
41 at discharge pressure PdH begins flowing out of the port 42
through the first control valve 30A. Then, in the second control
valve 30B, the pressure responsive member 64a receives differential
pressure between discharge pressures PdH and PdL, which moves the
ball valve element 67 so that the differential pressure will become
a predetermined level. With this movement of the ball valve element
67, the second control valve 30B controls the flow rate of the
refrigerant being delivered from its port 43 to the crank chamber
15.
[0102] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. With the increased differential pressure,
the ball valve element 67 gives a greater openness, allowing the
second control valve 30B to supply more refrigerant into the crank
chamber 15. As a result of this control action, the variable
displacement compressor 1 operates with a smaller displacement so
as to recover its original discharge flow rate. If, in turn, the
refrigerant flowing through the first control valve 30A decreases,
the second control valve 30B is actuated in a valve-closing
direction, thus reducing the refrigerant flowing into the crank
chamber 15. As a result of this control action, the variable
displacement compressor 1 operates with a larger displacement so as
to regulate the flow rate Qd of refrigerant that it discharges.
[0103] Seventh Embodiment
[0104] FIG. 8 is a sectional view of a capacity control valve for a
variable displacement compressor according to a seventh embodiment
of the invention. Since many of the valve components shown in FIG.
8 are identical or similar to those discussed in FIG. 6 or 7, the
same reference numerals are used in FIG. 8 to designate such
components, and the following section will not provide details
about them.
[0105] The illustrated capacity control valve 30 of the seventh
embodiment is different from that of the sixth embodiment (FIG. 7)
only in that its first valve element 61 is designed to cancel the
back pressure in order to prevent the discharge pressure PdH from
affecting operation of the first control valve 30A. This concept is
what has been described in the fifth embodiment (FIG. 6). The
capacity control valve 30 of the seventh embodiment operates
basically in the same as that of the sixth embodiment.
[0106] More specifically, when the solenoid unit 30C is in
de-energized state, the coil spring 55 urges the plunger 54 and
shaft 49 in the upward direction as viewed in FIG. 8. This makes
the taper-shaped valve element 61 sit on the first valve seat 63a.
Accordingly, the first control valve 30A is fully closed, while the
second control valve 30B is fully opened.
[0107] When the solenoid unit 30C is energized, the shaft 49 moves
downward as viewed in FIG. 8. This movement of the shaft 49 allows
the taper-shaped valve element 61 to leave the first valve seat 63a
and maintain a certain amount of gap between itself and the first
valve seat 63a. As a result, the refrigerant coming into the port
41 at discharge pressure PdH begins flowing out of the port 42
through the first control valve 30A. Then, in the second control
valve 30B, the pressure responsive member 64a receives differential
pressure between discharge pressures PdH and PdL, which moves the
ball valve element 67 so that the differential pressure will become
a predetermined level. With this movement of the ball valve element
67, the second control valve 30B controls the flow rate of the
refrigerant being delivered from its port 43 to the crank chamber
15.
[0108] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. With the increased differential pressure,
the ball valve element 67 gives a greater openness, allowing the
second control valve 30B to supply more refrigerant into the crank
chamber 15. As a result of this control action, the variable
displacement compressor 1 operates with a smaller displacement so
as to recover its original discharge flow rate. If, in turn, the
refrigerant flowing through the first control valve 30A decreases,
the second control valve 30B is actuated in a valve-closing
direction, thus reducing the refrigerant flowing into the crank
chamber 15. As a result of this control action, the variable
displacement compressor 1 operates with a larger displacement so as
to regulate the flow rate Qd of refrigerant that it discharges.
[0109] Eighth Embodiment
[0110] FIG. 9 is a sectional view of a capacity control valve for a
variable displacement compressor according to an eighth embodiment
of the invention. Since many of the valve components shown in FIG.
9 are identical or similar to those discussed in FIG. 2 or 5, the
same reference numerals are used in FIG. 9 to designate such
components, and the following section will not provide details
about them.
[0111] The illustrated capacity control valve 30 of the eighth
embodiment resembles that of the fourth embodiment (FIG. 5) in that
both of them use a taper-shaped valve element 64 as their second
valve element. The eighth embodiment is, however, different from
the fourth embodiment in that its first valve seat 45a is not
designed to move, but is constructed as an integral part of the
body 40 of the first control valve 30A. Another difference is that
a plurality of ball valve elements 46 are employed to serve the
function of the first valve element.
[0112] More specifically, the first control valve 30A is
constructed as follows. The body 40 has a plurality of valve holes
45 bored along a circle that is concentric with a cross section of
the body 40 itself, the bottom-end edge of each hole serving as a
first valve seat 45a. A ball valve element 46 is placed at a
downstream-side space adjacent to each first valve seat 45a. Those
ball valve elements 46 sit on the downstream-side surface of a
support member 70, which is urged by a coil spring 60 in the
downward direction as viewed in FIG. 9. The support member 70 also
receives a force of a coil spring 55 in the solenoid unit 30C, via
a plunger 54 and shaft 49, which acts in the upward direction as
viewed in FIG. 9.
[0113] The second control valve 30B, on the other hand, has a
pressure responsive member 64a, which is urged by a coil spring 66
upward as viewed in FIG. 9. Since this pressure responsive member
64a is integrally formed with a second valve element 64, the urging
force of the coil spring 66 also acts on the second valve element
64 in the valve-closing direction. The pressure responsive member
64a, in combination with the second valve element 64, is supposed
to be responsive to differential pressure .DELTA.P between two
different discharge pressures PdH and PdL, which are observed on
the upstream end and downstream end of the first control valve 30A,
respectively.
[0114] When the solenoid unit 30C is in de-energized state, the
coil spring 55 urges the plunger 54 and shaft 49 in the upward
direction as viewed in FIG. 9. This makes the ball valve elements
46 fit with corresponding first valve seats 45a, and thus the first
control valve 30A is fully closed. With the refrigerant at
discharge pressure PdH present in the port 41, the maximum
differential pressure acts on the pressure responsive member 64a,
making the second control valve 30B fully open. The variable
displacement compressor 1 thus operates in the minimum capacity
condition.
[0115] When the solenoid unit 30C is energized, the shaft 49 moves
downward as viewed in FIG. 9. This movement of the shaft 49, in
conjunction with the force of the coil spring 60, allows the
support member 70 to follow in the same direction while keeping in
contact with the shaft 49. Each ball valve element 46 thus leaves
the corresponding first valve seat 45a and maintains a certain
amount of gap between itself and that valve seat 45a. As a result,
the refrigerant coming into the port 41 at discharge pressure PdH
begins flowing out of the port 42 through the first control valve
30A. Then, in the second control valve 30B, the pressure responsive
member 64a adjacent to the second valve element 64 receives
differential pressure between discharge pressures PdH and PdL,
which moves the second valve element 64 so that the differential
pressure will become a predetermined level. This movement of the
second valve element 64 controls the flow rate of the refrigerant
at discharge pressure PdH that flows through the second control
valve 30B, from one port 41 to another port 43.
[0116] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. With the increased differential pressure
acting on the pressure responsive member 64a, the second valve
element 64 in the second control valve 30B is moved in the
direction that it gives a greater openness, allowing the second
control valve 30B to supply more refrigerant into the crank chamber
15. As a result of this control action, the variable displacement
compressor 1 operates with a smaller displacement so as to recover
its original discharge flow rate. If, in turn, the refrigerant
flowing through the first control valve 30A decreases, the second
control valve 30B reduces the refrigerant into the crank chamber 15
because the pressure responsive member 64a impels the second valve
element 64 in the valve-closing direction. As a result of this
control action, the variable displacement compressor 1 operates
with a larger displacement so as to regulate the flow rate Qd of
refrigerant that it discharges.
[0117] Ninth Embodiment
[0118] FIG. 10 is a sectional view of a capacity control valve for
a variable displacement compressor according to a ninth embodiment
of the invention. Since many of the valve components shown in FIG.
10 are identical or similar to those discussed in FIG. 9, the same
reference numerals are used in FIG. 10 to designate such
components, and the following section will not provide details
about them.
[0119] The capacity control valve 30 of this embodiment differs
from that of the eighth embodiment (FIG. 9) in its first control
valve 30A, particularly in the structure of its first valve element
and first valve seat.
[0120] More specifically, the first control valve 30A is
constructed as follows. The body 40 has a doughnut-shaped valve
hole 45 hollowed along a circle that is concentric with a cross
section of the body 40 itself, and the bottom-end edge of that hole
is supposed to serve as a first valve seat 45a. It should be noted
that the doughnut-shaped valve hole 45 does not go through the
floor of the body 40 in its entire circumference, but some middle
part of the floor is left unhallowed at a few places on its
circumference. This is necessary because the central portion of the
floor should still be connected to 64a in that portion. As the
counterpart of the first valve seat 45a, a flat valve element 71 is
disposed on the downstream side, together with a plug 40b that
supports the flat valve element 71 in a way that it can slide in
the axial direction.
[0121] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54 and shaft 49 in the
upward direction as viewed in FIG. 10, making the flat valve
element 71 abut on the first valve seat 45a. The first control
valve 30A is fully closed in this state. With the refrigerant at
discharge pressure PdH present in the port 41, the maximum
differential pressure acts on the pressure responsive member 64a,
making the second control valve 30B fully open. The variable
displacement compressor 1 thus operates in the minimum capacity
condition.
[0122] When the solenoid unit 30C is energized, the shaft 49 moves
downward as viewed in FIG. 10. This movement of the shaft 49, in
conjunction with the force of a coil spring 60, allows the flat
valve element 71 to follow in the same direction while keeping in
contact with the shaft 49. The flat valve element 71 thus leaves
the first valve seat 45a and maintains a certain amount of gap
between itself and that valve seat 45a. As a result, the
refrigerant coming into the port 41 at discharge pressure pdH
begins flowing out of the port 42 through the first control valve
30A. Then, in the second control valve 30B, the pressure responsive
member 64a adjacent to the second valve element 64 receives
differential pressure between discharge pressures PdH and PdL,
which moves the second valve element 64 so that the differential
pressure will become a predetermined level. This movement of the
second valve element 64 controls the flow rate of the refrigerant
at discharge pressure PdH that flows through the second control
valve 30B, from one port 41 to another port 43.
[0123] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. With the increased differential pressure
acting on the pressure responsive member 64a, the second valve
element 64 in the second control valve 30B is moved in the
direction that it gives a greater openness, allowing the second
control valve 30B to supply more refrigerant into the crank chamber
15. As a result of this control action, the variable displacement
compressor 1 operates with a smaller displacement so as to recover
its original discharge flow rate. If, in turn, the refrigerant
flowing through the first control valve 30A decreases, the second
control valve 30B reduces the refrigerant into the crank chamber 15
because its pressure responsive member 64a impels the second valve
element 64 in the valve-closing direction. As a result of this
control action, the variable displacement regulate the flow rate Qd
of refrigerant that it discharges.
[0124] Tenth Embodiment
[0125] FIG. 11 is a sectional view of a capacity control valve for
a variable displacement compressor according to a tenth embodiment
of the invention. Since many of the valve components shown in FIG.
11 are identical or similar to those discussed in FIG. 2 or 4, the
same reference numerals are used in FIG. 11 to designate such
components, and the following section will not provide details
about them.
[0126] The capacity control valve 30 of this embodiment differs
from that of the first embodiment (FIG. 2) in several points. The
most prominent difference is that the tenth embodiment uses, in its
first control valve 30A, a diaphragm 72 to detect differential
pressure between upstream and downstream.
[0127] More specifically, in a central region of the body 40, a
cylinder 40c is formed as an integral part of the body 40, and the
inner cavity of that cylinder 40c serves as a valve hole 45 to
interconnect two ports 41 and 42. The bottom end of the cylinder
40c functions as a first valve seat 45a for the first control valve
30A. In the downstream-side space communicating with the port 42, a
taper-shaped valve element 61 is placed opposite the first valve
seat 45a. This taper-shaped valve element 61, integrally formed
with the plunger 54 of the solenoid unit 30C, has a circumferential
groove 61b around its round side surface at the boundary portion
where the plunger 54 is joined. The groove 61b receives a piston
ring 74, which permits the plunger 54 to be slidably supported on
the inner wall of the sleeve 52, as well as centering the
taper-shaped valve element 61 on the axis of the sleeve 52.
[0128] In the second control valve 30B, on the other hand, a valve
hole is bored to allow a port 41 to communicate with another port
43, the bottom end of which is supposed to function as a second
valve seat 56. In the upstream-side space adjacent to the second
valve seat 56, a taper-shaped second valve element 64 is placed.
Integrally formed on top of this second valve element 64 are a
shaft 64c and a piston 64d. This piston 64d has the same outer
diameter as the valve hole of the second valve seat 56. The endface
of the piston 64d remote from the second valve element 64 receives,
through a communication hole 62, discharge pressure PdH in the port
41, so that the second valve element 64 can be driven with nothing
but differential pressure between discharge pressures PdH and PdL,
without being affected by the absolute value of discharge pressure
PdH. The second valve element 64 is integrally formed also with a
base member 64e, which is larger in diameter than the second valve
element 64 and has a hole 64b to introduce discharge pressure PdH
from the port 41 to the inner cavity of the cylinder 40c.
[0129] A sliding member 73 is provided around the outer surface of
the cylinder 40c in the body 40 in a way that it can move in the
vertical direction as viewed in FIG. 11. This sliding member 73 is
connected with the inner surface of the bodies 40 and 40a via a
diaphragm 72, which is a doughnut-shaped sheet with a center hole.
The outer circumference of the diaphragm 72 is clamped between two
bodies 40 and 40a, the latter 40a being pressed into the former 40.
The inner circumference of the diaphragm 72, on the other hand, is
clamped between the sliding member 73 and a ring 73a being fitted
thereto. The base member 64e of the second valve element 64 is
placed on the sliding member 73, and two coil springs 60 and 66
urge those two members 64e and 73 such that they will keep in
contact with each other. With the above arrangement, the diaphragm
72 receives differential pressure between discharge pressure PdH
available at one port 41 and discharge pressure PdL at another port
42. This differential pressure displaces the sliding member 73 in
its axial direction, causing the second valve element 64 to move
toward or away from its corresponding second valve seat 56.
[0130] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54 and taper-shaped
valve element 61 upward as viewed in FIG. 11, making the
taper-shaped valve element 61 sit on the first valve seat 45a. The
first control valve 30A is fully closed in this state. With the
refrigerant at discharge pressure PdH present in the port 41, the
maximum differential pressure acts on the diaphragm 72, making the
second control valve 30B fully open. The variable displacement
compressor 1 thus operates in the minimum capacity condition.
[0131] When the solenoid unit 30C is energized, the plunger 54
moves downward as viewed in FIG. 11. This movement of the plunger
54 allows the taper-shaped valve element 61 to leave the first
valve seat 45a and maintain a certain amount of gap between itself
and the first valve seat 45a. As a result, the refrigerant coming
into the port 41 at discharge pressure PdH begins flowing out of
the port 42 through the hole 64b of the second valve element 64,
the central cavity of the cylinder 40c, and the first control valve
30A. Then, in the second control valve 30B, the diaphragm 72
receives differential pressure between two different discharge
pressures PdH and PdL, which moves the sliding member 73 upward as
viewed in FIG. 11 so that the differential pressure will become a
predetermined level. The second valve element 64 follows this
movement of the sliding member 73, thus controlling the refrigerant
at discharge pressure PdH that flows through the second control
valve 30B, from one port 41 to another port 43.
[0132] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. With the increased differential pressure
acting on the diaphragm 72, the second valve element 64 in the
second control valve 30B is impelled in the direction that it gives
a greater openness, allowing the second control valve 30B to supply
more refrigerant into the crank chamber 15. As a result of this
control action, the variable displacement compressor 1 operates
with a smaller displacement so as to recover its original discharge
flow rate. If, in turn, the refrigerant flowing through the first
control valve 30A decreases, the diaphragm 72 of the second control
valve 30B receives a reduced differential pressure and reduces the
refrigerant flowing into the crank chamber 15 because its sliding
member 73 impels the second valve element 64 in the valve-closing
direction. As a result of this control action, the variable
displacement compressor 1 operates with a larger displacement so as
to regulate the flow rate Qd of refrigerant that it discharges.
Note here that the second control valve 30B is controlled to be
responsive only to differential pressure between two different
discharge pressures PdH and PdL, because since its second valve
element 64 is decoupled from variations of discharge pressure
PdH.
[0133] Eleventh Embodiment
[0134] FIG. 12 is a sectional view of a capacity control valve for
a variable displacement compressor according to an eleventh
embodiment of the invention. Since many of the valve components
shown in FIG. 12 are identical or similar to those discussed in
FIGS. 2, 5, or 11, the same reference numerals are used in FIG. 12
to designate such components, and the following section will not
provide details about them.
[0135] The illustrated capacity control valve 30 of the eleventh
embodiment resembles that of the tenth embodiment (FIG. 11) in that
both of them use a diaphragm 72 as their pressure sensing element.
The eleventh embodiment is, however, different from the tenth
embodiment in that the taper-shaped valve element (first valve
element) 61 in its first control valve 30A is disposed in an
upstream-side space adjacent to a first valve seat 45b formed at
the top end of the cylinder 40c. For this reason, in the solenoid
unit 30C of the eleventh embodiment, the plunger 54 and core 53
have swapped their positions on the axis. Also, a shaft 49 is
employed to connect the first valve element 61 with the plunger 54
in the solenoid unit 30C. The first valve element 61 is urged by a
coil spring 55 in the valve-closing direction.
[0136] The eleventh embodiment operates basically in the same way
as the tenth embodiment because of its similarity in structure;
that is, it uses a diaphragm 72 to detect differential pressure
.DELTA.P between the upstream and downstream ends of the first
control valve 30A, so as to control the refrigerant flow in the
second control valve 30B according to that differential pressure
.DELTA.P. In this structure, the widened base member 64e of the
second valve element 64 has a round hole 64f in addition to the
hole 64b in order to deliver the discharge pressure PdH from the
port 41 toward the upstream side of the first valve element 61.
[0137] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54, shaft 49, and first
valve element 61 downward as viewed in FIG. 12, making the first
valve element 61 sit on the first valve seat 45b. The first control
valve 30A is fully closed in this state. With the refrigerant at
discharge pressure PdH present in the port 41, the maximum
differential pressure acts on the diaphragm 72, making the second
control valve 30B fully open. The variable displacement compressor
1 thus operates in the minimum capacity condition.
[0138] When the solenoid unit 30C is energized, the plunger 54
moves upward as viewed in FIG. 12. This movement of the plunger 54
allows the taper-shaped valve element 61 to leave the first valve
seat 45b and maintain a certain amount of gap between itself and
the first valve seat 45b. As a result, the refrigerant coming into
the port 41 at discharge pressure PdH begins flowing out of the
port 42 through round hole 64f and the hole 64b of the second valve
element 64, the first control valve 30A, and the central cavity of
the cylinder 40c. Then, in the second control valve 30B, the
diaphragm 72 receives differential pressure between two different
discharge pressures PdH and PdL, which moves the sliding member 73
upward as viewed in FIG. 12 so that the differential pressure will
become a predetermined level. The second valve element 64 follows
this upward movement of the sliding member 73, thus controlling the
flow rate of the refrigerant at discharge pressure PdH that flows
through the second control valve 30B, from one port 41 to another
port 43.
[0139] If the refrigerant flowing through the first control valve
30A increases, a larger differential pressure will be produced
across that valve 30A. With the increased differential pressure
acting on the diaphragm 72, the second valve element 64 in the
second control valve 30B is moved in the direction that it gives a
greater openness, allowing the second control valve 30B to supply
more refrigerant into the crank chamber 15. As a result of this
control action, the variable displacement compressor 1 operates
with a smaller displacement so as to recover its original discharge
flow rate. If, in turn, the refrigerant flowing through the first
control valve 30A decreases, the diaphragm 72 of the second control
valve 30B detects a reduced differential pressure acting thereon,
and thus the sliding member 73 impels the second valve element 64
in the valve-closing direction. As a result, the second control
valve 30B reduces the refrigerant supplied to the crank chamber 15,
and the variable displacement compressor 1 operates with a larger
displacement so as to regulate the flow rate Qd of refrigerant that
it discharges.
[0140] Twelfth Embodiment
[0141] FIG. 13 is a sectional view of a capacity control valve for
a variable displacement compressor according to a twelfth
embodiment of the invention. Since many of the valve components
shown in FIG. 13 are identical or similar to those discussed in
FIG. 4, the same reference numerals are used in FIG. 13 to
designate such components, and the following section will not
provide details about them.
[0142] Recall the capacity control valve 30 of the third embodiment
shown in FIG. 4. In that embodiment, the first control valve 30A is
located between the discharge chambers 33 and crank chamber 15, and
the pressure in the crank chamber 15 is controlled by varying the
flow rate of refrigerant at discharge pressure PdL that is supplied
from the discharge chambers 33 into the crank chamber 15. Unlike
the third embodiment, the twelfth embodiment controls the flow rate
of the refrigerant returning from the crank chamber 15 back into
the suction chambers 32. In this alternative arrangement, the
variable displacement compressor 1 has a fixed orifice in the
middle of a passageway that delivers refrigerant from the discharge
chambers 33 to the crank chamber 15.
[0143] The first control valve 30A and solenoid unit 30C of this
capacity control valve 30 have almost the same structure as those
in the third embodiment. The exception is that the first control
valve 30A is designed to route the discharged refrigerant in the
direction that the stream pushes the taper-shaped valve element 61
away from the first valve seat 45a, or in short, in the
valve-opening direction.
[0144] In the second control valve 30B, there are two pistons 58
and 58a integrally formed with a second valve element 57. The
pistons 58 and 58a have the same outer diameter as the valve hole
of the second valve seat 56. Discharge pressure PdH acts on the
piston 58a and discharge pressure PdL propagates through a
communication hole 62 and acts on one endface of the piston 58.
Pressure Pc of the crank chamber 15 is led from the port 43 to an
upstream-side cavity adjacent to the second valve element 57. The
downstream-side room, on the other hand, communicates with the
suction chambers 32 at suction pressure Ps via the port 75. With
such an arrangement of the second control valve 30B, the second
valve element 57 and piston 58 are responsive to the differential
pressure .DELTA.P developed across the first control valve 30A,
which is functioning here as an orifice. The second control valve
30B thus controls the flow rate of the refrigerant flowing from the
crank chamber 15 to the suction chambers 32 in such a way that the
differential pressure .DELTA.P will be maintained at a constant
level. This control action varies the capacity of the variable
displacement compressor 1 so as to regulate the flow rate of
refrigerant being discharged therefrom.
[0145] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54, shaft 49, and first
valve element 61 upward as viewed in FIG. 13, making the first
valve element 61 sit on the first valve seat 45a. The first control
valve 30A is fully closed in this state.
[0146] When the solenoid unit 30C is energized, the plunger 54
moves downward as viewed in FIG. 13. This movement of the plunger
54 allows the first valve element 61 to leave the first valve seat
45a and maintain a certain amount of gap between itself and the
first valve seat 45a. As a result, the refrigerant coming into the
port 41 at discharge pressure PdH begins flowing out of the port 42
through the first control valve 30A. Then, in the second control
valve 30B, the second valve element 57 and piston 58, as a single
integrated member, receive differential pressure between two
different discharge pressures PdH and PdL, in addition to the force
of the coil spring 60. The second valve element 57 thus moves to a
point at which all those forces and pressures come into balance,
which allows the refrigerant in the crank chamber 15 at pressure Pc
to flow back to the suction chambers 32. The second control valve
30B can now control the discharge capacity of the variable
displacement compressor 1 by varying crank chamber pressure Pc.
[0147] The amount of refrigerant flowing through the first control
valve 30A may rise due to, for example, sudden acceleration of the
engine. If this happens, a larger differential pressure will be
produced across that valve 30A. The increased differential pressure
actuates the second control valve 30B in the direction that it
gives a smaller openness, thus reducing the flow rate of
refrigerant coming out of the crank chamber 15. As a result of this
control action, the variable displacement compressor 1 operates
with a smaller displacement so as to recover its original discharge
flow rate. If, in turn, the refrigerant flowing through the first
control valve 30A decreases, the second control valve 30B is
actuated in the valve-opening direction, thus increasing the flow
rate of refrigerant coming out of the crank chamber 15. As a result
of this control action, the variable displacement compressor 1
operates with a larger displacement, thus regulating the flow rate
Qd of refrigerant that it discharges.
[0148] Thirteenth Embodiment
[0149] FIG. 14 is a sectional view of a capacity control valve for
a variable displacement compressor according to a thirteenth
embodiment of the invention. Since many of the valve components
shown in FIG. 14 are identical or similar to those discussed in
FIG. 13, the same reference numerals are used in FIG. 14 to
designate such components, and the following section will not
provide details about them.
[0150] The third embodiment (FIG. 4) has presented a capacity
control valve 30 that is designed to control the flow rate of
refrigerant entering the crank chamber 15, which is referred to as
the inflow control. In contrast to this, the twelfth embodiment
(FIG. 13) manipulates the flow rate of refrigerant coming out of
the crank chamber 15, which is referred to as the outflow control.
The thirteenth embodiment now offers a capacity control valve 30
that employs both in-flow and out-flow control mechanisms. More
specifically, the capacity control valve 30 of the thirteenth
embodiment has a first control valve 30A that is placed on a
passageway leading from the discharge chambers 33 and a solenoid
unit 30C that governs the cross-sectional area of that passageway.
In addition to those components, the capacity control valve 30 has
second and third control valves 30B and 30D that detect
differential pressure developed across the first control valve 30A
and control the pressure in the crank chamber 15 such that the
differential pressure will become a specified level.
[0151] The second and third control valves 30B and 30D accommodate
the following components in their common valve hole: a piston 58, a
second valve element 57, and a third valve element 76. Those
components are integrally formed as a single member. One edge
formed in the valve hole serves as a third valve seat 77, and the
piston 58 has the same outer diameter as that valve seat 77. The
second valve element 57 receives discharge pressure PdH on its
bottom endface, while the piston 58 receives discharge pressure PdL
through a communication hole 62. The upstream-side room adjacent to
the second valve element 57 is at discharge pressure PdH introduced
from a port 41. The downstream side, on the other hand,
communicates with the crank chamber 15 through another port 43a,
the pressure at which is Pc1. The upstream-side space adjacent to
the third valve element 76 receives pressure Pc2 from the crank
chamber 15 via yet another port 43b. The downstream-side space
adjacent to the third valve element 76, on the other hand,
communicates with the suction chambers 32 at suction pressure Ps
via still another port 75.
[0152] With the arrangement described above, the piston 58 and
second valve element 57 move together in response to differential
pressure .DELTA.P across the first control valve 30A, which is
functioning here as an orifice. The second and third control valves
30B and 30D now act as a three-way valve that controls the inflow
of refrigerant from the discharge chambers 33 into the crank
chamber 15, simultaneously with the outflow from the crank chamber
15 to the suction chambers 32, so that the differential pressure
.DELTA.P will be maintained at a constant level.
[0153] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54, shaft 49, and first
valve element 61 upward as viewed in FIG. 14, making the first
valve element 61 sit on the first valve seat 45a. The first control
valve 30A is fully closed in this state.
[0154] When the solenoid unit 30C is energized, the plunger 54
moves downward as viewed in FIG. 14. This movement of the plunger
54 causes the first valve element 61 to leave the first valve seat
45a and maintain a certain amount of gap. As a result, the
refrigerant coming into the port 41 at discharge pressure PdH
begins flowing out of the port 42 through the first control valve
30A. Then in the second control valve 30B, the unified valve member
(i.e., second valve element 57, third valve element 76, and piston
58) receives differential pressure between two different discharge
pressures PdH and PdL while being pushed by the coil spring 60, and
thus moves to a point at which all those forces and pressures come
into balance. The second control valve 30B now supplies the crank
chamber 15 with refrigerant at discharge pressure PdH, and the
third control valve 30D allows the refrigerant at pressure Pc to
flow back into the suction chambers 32. The capacity control valve
30 varies the crank chamber pressure Pc in this way, thus being
able to control the discharge capacity of the variable displacement
compressor 1.
[0155] The amount of refrigerant flowing through the first control
valve 30A may rise due to, for example, sudden acceleration of the
engine. If this happens, a larger differential pressure will be
produced across that valve 30A. The increased differential pressure
makes the second control valve 30B open wider, while actuating the
third control valve 30D in the valve-closing direction. This
control action brings about an increased inflow of refrigerant to
the crank chamber 15, along with a decreased outflow from the crank
chamber 15. As a result, the variable displacement compressor 1
operates with a smaller displacement so as to recover its original
discharge flow rate. If, in turn, the refrigerant flowing through
the first control valve 30A decreases, the second control valve 30B
is actuated in the valve-closing direction, thus producing a
decreased inflow of refrigerant to the crank chamber 15. At the
same time, the third control valve 30D is impelled in the
valve-opening direction, resulting in an increased outflow from the
crank chamber 15. The variable displacement compressor 1 now
operates with a larger displacement, resulting in a regulated flow
rate Qd of refrigerant that it discharges.
[0156] Fourteenth Embodiment
[0157] FIG. 15 is a sectional view of a capacity control valve for
a variable displacement compressor according to a fourteenth
embodiment of the invention. Since many of the valve components
shown in FIG. 15 are identical or similar to those discussed in
FIG. 13, the same reference numerals are used in FIG. 15 to
designate such components, and the following section will not
provide details about them.
[0158] As opposed to the twelfth embodiment (FIG. 13), the capacity
control valve 30 of the fourteenth embodiment is designed to
control how much of the discharged refrigerant to supply to the
crank chamber 15. Another difference is that the second valve
element 57 of the second control valve 30B is provided as a
discrete component, not integrated with a pressure sensing member
that responds to differential pressure across the first control
valve 30A.
[0159] More specifically, the second control valve 30B is
constructed as follows. A piston 58 is located inside the body 40,
and a communication hole 62 is bored through the body 40 to apply
discharge pressure PdL to the piston 58. A refrigerant passageway
branches from the communication hole 62, leading to a port 43 for
the crank chamber 15. In the middle of this passageway, a second
valve seat 56 is formed as an integral part of the body 40. Located
downstream with respect to the second valve seat 56 is a second
valve element 57. This second valve element 57, integrally formed
with the piston 58, can move toward and away from the second valve
seat 56 in the downstream-side space. The piston 58 receives
discharge pressure PdL on its distal end. In addition, a piston 78,
coil spring 79, and spring seat 80 are installed coaxially with the
second valve element 57 and piston 58 in a space formed between the
port 41 and communication hole 62. Discharge pressure PdH is
available in this space. A shaft is integrally formed with the
second valve element 57, extending therefrom toward the piston 78
in a space that communicates with the communication hole 62. The
piston 78 is forced against the shaft by the coil spring 79.
Discharge pressure PdL does not affect the movement of the second
valve element 57 and piston 58 because their pressure-receiving
areas are substantially equal. In the second control valve 30B, its
piston 78 is responsive to differential pressure .DELTA.P developed
across the first control valve 30A, which is functioning here as an
orifice. The second control valve 30B thus controls the flow rate
of refrigerant from the discharge chambers 33 to the crank chamber
15 such that the differential pressure .DELTA.P will be maintained
at a constant level. This mechanism varies the capacity of the
variable displacement compressor 1 so as to regulate the flow rate
of refrigerant that it discharges.
[0160] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54, shaft 49, and first
valve element 61 in the upward direction as viewed in FIG. 15,
making the first valve element 61 sit on the first valve seat 45a.
The first control valve 30A is fully closed in this state.
[0161] When the solenoid unit 30C is energized, the plunger 54
moves downward as viewed in FIG. 15. This movement of the plunger
54 allows the first valve element 61 to leave the first valve seat
45a and maintain a certain amount of gap between itself and the
first valve seat 45a. As a result, the refrigerant coming into the
port 41 at discharge pressure PdH begins flowing out of the port 42
through the first control valve 30A. Then in the second control
valve 30B, the piston 78 receives differential pressure between two
different discharge pressures PdH and PdL while being pushed by two
coil springs 60 and 79, and thus moves to a point at which all
those forces and pressures come into balance. This allows the
refrigerant at discharge pressure PdH to flow into the crank
chamber 15, and the second control valve 30B can now control the
discharge capacity of the variable displacement compressor 1 by
varying crank chamber pressure Pc.
[0162] The amount of refrigerant flowing through the first control
valve 30A may rise due to, for example, sudden acceleration of the
engine. If this happens, a larger differential pressure will be
produced across that valve 30A, which makes the second control
valve 30B open wider. This control action produces an increased
inflow of refrigerant to the crank chamber 15, and as a result, the
variable displacement compressor 1 operates with a smaller
displacement, thus recovering its original discharge flow rate. If,
in turn, the refrigerant flowing through the first control valve
30A decreases, the second control valve 30B is actuated in the
valve-closing direction, thus producing a decreased inflow of
refrigerant to the crank chamber 15. The variable displacement
compressor 1 now operates with a larger displacement, resulting in
a regulated flow rate Qd of refrigerant that it discharges.
[0163] Fifteenth Embodiment
[0164] FIG. 16 is a sectional view of a capacity control valve for
a variable displacement compressor according to a fifteenth
embodiment of the invention. Since many of the valve components
shown in FIG. 16 are identical or similar to those discussed in
FIG. 13, the same reference numerals are used in FIG. 16 to
designate such components, and the following section will not
provide details about them.
[0165] The capacity control valve 30 of the fifteenth embodiment is
similar to that of the twelfth embodiment (FIG. 13) in that it
controls the outflow of refrigerant from the crank chamber 15 to
the suction chambers 32. The fifteenth embodiment, however, differs
in that the second valve element 57 in its second control valve 30B
is provided as a discrete component, not integrated with a pressure
sensing member that responds to differential pressure across the
first control valve 30A.
[0166] More specifically, to detect differential pressure across
the first control valve 30A, the second control valve 30B employs a
piston 78, a coil spring 79, and a spring seat 80. Ports 43 and 75
are disposed to communicate with the crank chamber 15 and suction
chambers 32, respectively, and between these two ports, a second
valve seat 56 is formed as an integral part of the body 40. A
second valve element 57 is installed in an upstream-side space near
the port 43 such that it can move toward and away from the second
valve seat 56. Integrally formed with this second valve element 57
is a piston 58 with the same diameter as the valve hole of the
second valve seat 56. Discharge pressure PdL propagates through a
communication hole 62 and acts on one endface of the piston 58. The
second valve element 57 is integrally formed also with another
piston 58a having nearly the same diameter as the valve hole of the
second valve seat 56. This piston 58a is held in the body 40 in an
airtight manner, movably in its axial direction, receiving
discharge pressure PdL. The lower end of the piston 58a as viewed
in FIG. 16 abuts on yet another piston 78. Discharge pressure PdL
does not affect movement of the pistons 58a and 58 because their
diameters are substantially the same. With the above arrangement of
the second control valve 30B, the piston 78 is responsive to
differential pressure .DELTA.P across the first control valve 30A,
which is functioning here as an orifice. The second control valve
30B thus controls the outflow of refrigerant from the crank chamber
15 to the suction chambers 32 in such a way that the differential
pressure .DELTA.P will be maintained at a constant level. This
control action varies the capacity of the variable displacement
compressor 1 so as to regulate the flow rate of refrigerant being
discharged therefrom.
[0167] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54, shaft 49, and first
valve element 61 upward as viewed in FIG. 16, making the first
valve element 61 sit on the first valve seat 45a. The first control
valve 30A is fully closed in this state.
[0168] When the solenoid unit 30C is energized, the plunger 54
moves downward as viewed in FIG. 16. This movement of the plunger
54 allows the first valve element 61 to leave the first valve seat
45a and maintain a certain amount of gap between itself and the
first valve seat 45a. As a result, the refrigerant coming into the
port 41 at discharge pressure PdH begins flowing out of the port 42
through the first control valve 30A. Then, in the second control
valve 30B, the piston 78 receives differential pressure between
discharge pressures PdH and PdL, while being pushed by two coil
springs 60 and 79, and thus moves to a point at which all those
forces and pressures come into balance. With this movement of the
piston 78, the refrigerant in the crank chamber 15 at pressure Pc
is allowed to flow back into the suction chambers 32. The second
control valve 30B can now control the discharge capacity of the
variable displacement compressor 1 by varying crank chamber
pressure Pc.
[0169] The amount of refrigerant flowing through the first control
valve 30A may rise due to, for example, sudden acceleration of the
engine. If this happens, a larger differential pressure will be
produced across that valve 30A. The increased differential pressure
actuates the second control valve 30B in the direction that it
gives a smaller openness, thus reducing the flow rate of
refrigerant coming out of the crank chamber 15 and raising the
crank chamber pressure Pc. As a result of this action, the variable
displacement compressor 1 operates with a smaller displacement so
as to recover its original discharge flow rate. If, in turn, the
refrigerant flowing through the first control valve 30A decreases,
the second control valve 30B is actuated in the valve-opening
direction, thus permitting an increased outflow from the crank
chamber 15. Since the crank chamber pressure Pc goes down, the
variable displacement compressor 1 now operates with a larger
displacement, resulting in a regulated flow rate Qd of refrigerant
that it discharges.
[0170] Sixteenth Embodiment
[0171] FIG. 17 is a sectional view of a capacity control valve for
a variable displacement compressor according to a sixteenth
embodiment of the invention. Since many of the valve components
shown in FIG. 17 are identical or similar to those discussed in
FIGS. 14 and 16, the same reference numerals are used in FIG. 17 to
designate such components, and the following section will not
provide details about them.
[0172] The capacity control valve 30 of this sixteenth embodiment
is similar to that of the thirteenth embodiment (FIG. 14) in that
it controls both inflow and outflow of refrigerant to/from the
crank chamber 15. The sixteenth embodiment, however, differs in
that the second valve element 57 in its second control valve 30B is
provided as a discrete component, not integrated with a member that
senses differential pressure across the first control valve 30A.
Regarding the pressure responsive member, the sixteenth embodiment
uses a similar structure to that in the fifteenth embodiment (FIG.
16).
[0173] More specifically, inside the second and third control
valves 30B and 30D, a piston 58, a second valve element 57, and a
third valve element 76 are disposed in an integrated manner. The
piston 58 has the same outer diameter as the valve holes of second
and third valve seats 56 and 77 so as to avoid the effect of
discharge pressure PdL acting thereon. With this arrangement, the
piston 58 and second valve element 57 move together in response to
differential pressure .DELTA.P across the first control valve 30A,
which is functioning here as an orifice. The second and third
control valves 30B and 30D now serve as a three-way valve that
controls the inflow of refrigerant from the discharge chambers 33
into the crank chamber 15, simultaneously with the outflow from the
crank chamber 15 to the suction chambers 32, in such a way that the
differential pressure .DELTA.P will be maintained at a constant
level.
[0174] The capacity control valve 30 with the above construction
operates as follows. When the solenoid unit 30C is in de-energized
state, the coil spring 55 urges the plunger 54, shaft 49, and first
valve element 61 upward as viewed in FIG. 17, making the first
valve element 61 sit on the first valve seat 45a. The first control
valve 30A is fully closed in this state.
[0175] When the solenoid unit 30C is energized, the plunger 54
moves downward as viewed in FIG. 17. This movement of the plunger
54 allows the first valve element 61 to leave the first valve seat
45a and maintain a certain amount of gap. As a result, the
refrigerant coming into the port 41 at discharge pressure PdH
begins flowing out of the port 42 through the first control valve
30A. Then in the second control valve 30B, the unified valve member
(i.e. second valve element 57, third valve element 76, and piston
58) receives differential pressure between discharge pressures PdH
and PdL while being pushed by the coil springs 60 and 79, and thus
moves to a point at which all those forces and pressures come into
balance. The second control valve 30B now supplies refrigerant at
pressure Pc1 to the crank chamber 15 by controlling refrigerant at
discharge pressure PdL, and at the same time, the third control
valve 30D allows the refrigerant at pressure Pc2 in the crank
chamber 15 to flow back into the suction chambers 32. The capacity
control valve 30 varies the crank chamber pressure Pc in this way,
thus being able to control the discharge capacity of the variable
displacement compressor 1.
[0176] The amount of refrigerant flowing through the first control
valve 30A may rise due to, for example, sudden acceleration of the
engine. If this happens, a larger differential pressure will be
produced across that valve 30A. The increased differential pressure
makes the second control valve 30B open wider, while actuating the
third control valve 30D in the valve-closing direction. This
control action produces an increased inflow of refrigerant to the
crank chamber 15, together with a decreased outflow from the crank
chamber 15. As a result, the variable displacement compressor 1
operates with a smaller displacement so as to recover its original
discharge flow rate. If, in turn, the refrigerant flowing through
the first control valve 30A decreases, the second control valve 30B
is actuated in the valve-closing direction, and the third control
valve 30D in the value-opening direction, thus producing a
decreased inflow of refrigerant to the crank chamber 15 and an
increased outflow from the crank chamber 15. The variable
displacement compressor 1 now operates with a larger displacement,
resulting in a regulated flow rate Qd of refrigerant that it
discharges.
[0177] Seventeenth Embodiment
[0178] FIG. 18 is a sectional view of a capacity control valve for
a variable displacement compressor according to a seventeenth
embodiment of the invention. Since many of the valve components
shown in FIG. 18 are identical or similar to those discussed in
FIG. 15, the same reference numerals are used in FIG. 18 to
designate such components, and the following section will not
provide details about them.
[0179] As in the fourteenth embodiment (FIG. 15), the capacity
control valve 30 of this seventeenth embodiment is designed to
control how much of the discharged refrigerant to supply to the
crank chamber 15. Another similarity is that the second valve
element 57 of the second control valve 30B is provided as a
discrete component, not integrated with a member that responds to
differential pressure across the first control valve 30A. The
seventeenth embodiments is, however, different in that it has no
back-pressure cancellation mechanism for the second valve element
57.
[0180] More specifically, the second control valve 30B is
constructed as follows. A second valve element 57 is urged by a
coil spring 60 in the valve-closing direction, where discharge
pressure PdL is routed through a communication hole 62 and acts
only on the piston 78 and second valve element 57. The upper end of
the coil spring 60, as viewed in FIG. 18, is supported by a lid 59c
having a vent. An O-ring 29b is used for sealing of the capacity
control valve 30 when it is installed in a variable displacement
compressor 1. The upper space above the level of this O-ring 29b,
as viewed in FIG. 18, will be at pressure Pc, i.e., the pressure in
the port 43, meaning that the same pressure Pc will be available in
the cavity where the coil spring 60 resides.
[0181] The above-described capacity control valve 30 bears close
resemblance to the fourteenth embodiment (FIG. 15) in terms of the
structure, except for the fact that the second valve element 57 is
not free from back pressures. When its solenoid unit 30C is in
de-energized state, the capacity control valve 30 operates in the
same way as described in the fourteenth embodiment. This similarity
in its control operations also applies when the solenoid unit 30C
is energized, as well as when the engine rotation varies.
[0182] Eighteenth Embodiment
[0183] FIG. 19 is a sectional view of a capacity control valve for
a variable displacement compressor according to an eighteenth
embodiment of the invention. Since many of the valve components
shown in FIG. 19 are identical or similar to those discussed in
FIG. 16, the same reference numerals are used in FIG. 19 to
designate such components, and the following section will not
provide details about them.
[0184] As in the fifteenth embodiment (FIG. 16), the capacity
control valve 30 of this eighteenth embodiment is designed to
control the outflow of refrigerant coming out of the crank chamber
15 to the suction chambers 32. Another likeness is that the second
valve element 57 of the second control valve 30B is provided as a
discrete component, not integrated with a member that senses
differential pressure across the first control valve 30A. The
eighteenth embodiments is, however, different in that it has no
back-pressure cancellation mechanism for the second valve element
57.
[0185] More specifically, the second control valve 30B is
constructed as follows. A second valve element 57 is urged against
a piston 78 by a coil spring 60 in the valve-opening direction,
where discharge pressure PdL is routed through a communication hole
62 in such a way that it acts only on the piston 78 and another
piston that extends from the second valve element 57. Yet another
piston 58 is integrally formed with the second valve element 57,
and the coil spring 60 is accommodated in a space between this
piston 58 and a lid 59c having a vent. The coil spring space is
pressurized at Ps through the vent in the lid 59c.
[0186] The above-described capacity control valve 30 bears close
resemblance to the fifteenth embodiment (FIG. 16) in terms of the
structure, except for the fact that the second valve element 57 is
not free from back pressures. When its solenoid unit 30C is in
de-energized state, the capacity control valve 30 operates in the
same way as described in the fifteenth embodiment. This similarity
in its control operations also applies when the solenoid unit 30C
is energized, as well as when the engine rotation varies.
[0187] Nineteenth Embodiment
[0188] FIG. 20 is a sectional view of a capacity control valve for
a variable displacement compressor according to a nineteenth
embodiment of the invention. Since many of the valve components
shown in FIG. 20 are identical or similar to those discussed in
FIG. 17, the same reference numerals are used in FIG. 20 to
designate such components, and the following section will not
provide details about them.
[0189] The capacity control valve 30 of this nineteenth embodiment
controls both inflow and outflow of refrigerant to/from the crank
chamber 15, as in the seventeenth embodiment (FIG. 18). The
nineteenth embodiment is also similar to the seventeenth embodiment
in that the second valve element 57 in its second control valve 30B
is provided as a discrete component, not integrated with a member
that senses differential pressure across the first control valve
30A.
[0190] More specifically, the second and third control valves 30B
and 30D are constructed as follows. A second valve element 57 and a
third valve element 76, which constitute a three-way valve, are
urged by a coil spring 60 in the valve-closing direction and in the
valve-opening direction, respectively, where discharge pressure PdL
is routed through a communication hole 62 in such a way that it
acts only on the second valve element 57 and piston 78. A piston 58
is integrally formed with the second and third valve elements 57
and 76, and the coil spring 60 is accommodated in a space between
this piston 58 and a lid 59c having a vent. The coil spring space
is pressurized at Ps through the vent in the lid 59c.
[0191] The above-described capacity control valve 30 bears close
resemblance to the sixteenth embodiment (FIG. 17) in terms of the
structure, except for the fact that the second valve element 57 and
third valve element 76 are not free from back pressures. When its
solenoid unit 30C is in de-energized state, the capacity control
valve 30 operates in the same way as described in the sixteenth
embodiment. This similarity in its control operations also applies
when the solenoid unit 30C is energized, as well as when the engine
rotation varies.
[0192] Various types of capacity control valves 30 have been
presented as preferred embodiments of the present invention. All
those embodiments share a common concept that the first control
valve 30A controls the cross-section area of a passageway of
discharged refrigerant, and the second control valve 30B (and third
control valve 30D in several cases) controls pressure Pc in the
crank chamber 15 in such a way that the differential pressure
across the controlled passageway will be maintained at a specified
level. The capacity control valves of the present invention should
not be limited to the structure that uses differential pressure on
the discharge side of the valves. Rather, it has to be appreciated
that the invention covers the structure using differential pressure
on the suction side. That is, the first control valve 30A may
control the cross-section area of a passageway of refrigerant
coming into the compressor, and the second control valve 30B (and
third control valve 30D) controls pressure Pc in the crank chamber
15 in such a way that the differential pressure across the
controlled passageway will be maintained at a specified level.
[0193] As can be seen from the above explanation, the present
invention proposes a structure that employs first and second
control valves formed in an integrated way. Here, the first control
valve controls the cross-section area at a midway point between
low-pressure refrigerant passage and suction chamber, or between
discharge chamber and high-pressure refrigerant passage, according
to a given external condition. The second control valve, on the
other hand, detects differential pressure between upstream end and
downstream end of the first control valve and controls the crank
chamber pressure in such a way that the differential pressure will
be maintained at a specified level. This feature of the present
invention enables us to construct a smaller variable displacement
compressor at lower cost.
[0194] Because the first control valve has only to produce a small
amount of differential pressure, the solenoid unit can drive the
valve with a small power, and thus it is not necessary to increase
its size to achieve the purpose. The present invention can easily
be applied to refrigeration cycles using HFC-134a in a system that
should operate with small differential pressure between discharge
chamber and crank chamber, or crank chamber and suction chamber. In
addition, the present invention can also be applied to those using
high-pressure refrigerant in its supercritical region.
[0195] 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.
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