U.S. patent application number 12/192524 was filed with the patent office on 2008-12-18 for control valve for compressor.
This patent application is currently assigned to TGK Co., Ltd.. Invention is credited to Hisatoshi HIROTA.
Application Number | 20080307812 12/192524 |
Document ID | / |
Family ID | 38458867 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080307812 |
Kind Code |
A1 |
HIROTA; Hisatoshi |
December 18, 2008 |
CONTROL VALVE FOR COMPRESSOR
Abstract
To improve the pressure resistance strength of a
pressure-sensing section of a control valve for a internal variable
control compressor. In the control valve, a stack of snap-acting
discs is disposed on a side of a diaphragm forming the
pressure-sensing section opposite from a transmitting member. With
this arrangement, even if the diaphragm receives large suction
pressure Ps, since the snap-acting disc receives suction pressure
Ps from the opposite side, the diaphragm is prevented from being
broken or deformed. This makes it possible to improve the pressure
resistance strength of the pressure-sensing section. As a result,
even if the control valve is applied to a refrigeration cycle in
which suction pressure Ps becomes high, such as one using carbon
dioxide as refrigerant, it is possible to secure sufficient
pressure resistance strength.
Inventors: |
HIROTA; Hisatoshi; (Tokyo,
JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
TGK Co., Ltd.
Tokyo
JP
|
Family ID: |
38458867 |
Appl. No.: |
12/192524 |
Filed: |
August 15, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2007/052194 |
Feb 8, 2007 |
|
|
|
12192524 |
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Current U.S.
Class: |
62/228.3 |
Current CPC
Class: |
F04B 2027/1859 20130101;
F04B 27/1804 20130101; F04B 2027/1827 20130101 |
Class at
Publication: |
62/228.3 |
International
Class: |
F25B 1/00 20060101
F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2006 |
JP |
2006-054329 |
Claims
1. A control valve for a compressor that varies displacement of the
compressor, comprising: a body that has a refrigerant passage
formed therein; a valve element that moves to and away from a valve
seat formed in said body in order to adjust a flow rate of
refrigerant when causing part of discharge refrigerant of said
compressor to flow into a control chamber; and a power element that
transmits a driving force which varies according to suction
pressure of refrigerant sucked into a suction chamber of said
compressor to said valve element via a transmitting member, wherein
said power element comprises a diaphragm that senses said suction
pressure to be displaced in an axial direction, and at least one
snap-acting disc disposed to support said diaphragm while being in
contact with said diaphragm from a side of said diaphragm opposite
from a side where said valve element is disposed.
2. The control valve according to claim 1, wherein said
transmitting member is slidably inserted into a guide hole formed
in said body to be axially supported therein, and at the same time
has one end thereof supporting said valve element, and the other
end thereof directly or indirectly connected to said diaphragm.
3. The control valve according to claim 1, wherein said snap-acting
disc has a central part having a shape convex toward said valve
element, and is deformable by having a direction in which said
central part is convex inverted using a periphery of said
snap-acting disc as a support.
4. The control valve according to claim 3, wherein said power
element is formed such that said thin-film diaphragm is sandwiched
between an upper housing and a lower housing, and wherein said
snap-acting disc is disposed in a region surrounded by said upper
housing and said diaphragm, and is brought into contact with a side
wall of said upper housing such that an edge of a periphery of said
snap-acting disc forms the support, thereby being supported
thereon.
5. The control valve according to claim 4, wherein a contact
surface of said upper housing in contact with said edge of said
snap-acting disc is formed to have a tapered shape, and said
support is hardly changed in position by an axial displacement of
said snap-acting disc.
6. The control valve according to claim 5, wherein said upper
housing has an inner wall formed such that said inner wall has a
shape substantially matching a shape of said snap-acting disc when
said snap-acting disc is deformed by inversion.
7. The control valve according to claim 4, wherein an auxiliary
spring is disposed within said upper housing, for urging said
snap-acting disc in a valve-opening direction from a side opposite
from said diaphragm.
8. The control valve according to claim 7, including a load
adjusting structure for adjusting load of said auxiliary
spring.
9. The control valve according to claim 1, wherein said power
element comprises a plurality of said snap-acting discs, and
wherein said snap-acting discs are stacked one upon another by a
predetermined number according to a magnitude of suction pressure
to be received by said diaphragm.
10. The control valve according to claim 9, wherein a thin film is
disposed between said diaphragm and said snap-acting disc, or
between said snap-acting discs stacked one upon another by said
predetermined number.
11. The control valve according to claim 1, further comprising an
another spring that urges said valve element in a valve-closing
direction from a side opposite from a side where said power element
is disposed, a spring-receiving member for supporting said another
spring from the side opposite from the side where said valve
element is disposed and for adjusting the load of said another
spring by being fixed after having being adjusted in position.
12. A control valve for a compressor that varies displacement of
the compressor, comprising: a body that has a refrigerant passage
formed therein; a valve element that moves to and away from a valve
seat formed in said body in order to adjust a flow rate of
refrigerant when causing part of discharge refrigerant of said
compressor to flow into a control chamber; and a power element that
transmits a driving force which varies according to suction
pressure of refrigerant sucked into a suction chamber of said
compressor to said valve element via a transmitting member, wherein
said power element is formed by disposing at least one thin-film
snap-acting disc between an upper housing and a lower housing such
that said thin-film snap-acting disc is sandwiched between said
upper housing and said lower housing, and performing
circumferential welding of peripheries thereof, and is configured
such that an axial displacement of said snap-acting disc caused by
sensing the suction pressure at a central part thereof gives a
driving force transmitted to said valve element via said
transmitting member.
13. The control valve according to claim 12, wherein said
transmitting member is slidably inserted into a guide hole formed
in said body to be axially supported therein, and at the same time
has one end thereof supporting said valve element, and the other
end thereof directly or indirectly connected to said snap-acting
disc.
14. The control valve according to claim 12, wherein said
snap-acting disc has a central part having a shape convex toward
said valve element, and wherein said upper housing has an inner
wall having a shape substantially matching a shape of said
snap-acting disc when said snap-acting disc is deformed in a
direction opposite from a direction in which the central part of
said snap-acting disc is convex, using the vicinity of a periphery
of said snap-acting disc as a support.
Description
[0001] This application is a continuing application, filed under 35
U.S.C. .sctn.111(a), of International Application
PCT/JP2007/052194, filed Feb. 8, 2007.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a control valve for a
compressor, and more particularly to a control valve for an
internal variable control compressor, which is disposed in such an
internal variable control compressor as a component of a
refrigeration cycle of an automotive air conditioner, and is
suitable for controlling the displacement or the refrigerant
discharge capacity of the compressor.
[0004] 2. Description of the Related Art
[0005] In a refrigeration cycle for an automotive air-conditioner,
in general, a variable displacement compressor is used to control
refrigeration capacity thereof according to a load thereon. To vary
the displacement of the compressor, there are known an internal
variable control method in which the control is performed only by
making use of an internal mechanical construction of the variable
displacement compressor, and an external variable control method in
which the control is electrically performed using a magnet coil or
the like, based on results of calculation of various sensor
outputs. Here, a description will be given of a control valve for
an internal variable control compressor which is controlled by the
internal variable control method.
[0006] The control valve for the internal variable control
compressor includes a power element having a pressure-sensing
member that senses suction pressure of the compressor, and a valve
section that generates crankcase pressure in a crankcase into which
discharge pressure of the compressor is delivered via the valve
section, according to the pressure sensed by the pressure-sensing
member. A bellows or a diaphragm is used as the pressure-sensing
member. However, to make the control valve for the compressor
compact in construction as a whole, a diaphragm made of e.g. sheet
metal is used (see e.g. Japanese Unexamined Patent Publication No.
2004-218443 (FIG. 2)).
[0007] FIG. 15 is a cross-sectional view of an example of the
arrangement of a conventional control valve for an internal
variable control compressor.
[0008] The control valve for a compressor includes a valve main
unit 101 and a power element 102 which drivingly controls the valve
main unit 101.
[0009] In a body 103 of the valve main unit 101, there are formed a
port 104 communicating with a discharge chamber of the compressor,
for introducing discharge pressure Pd, a port 105 communicating
with a crankcase of the compressor, for outputting controlled
pressure, i.e. crankcase pressure PC, and a port 106 communicating
with a suction chamber of the compressor, for receiving suction
pressure Ps. In a refrigerant passage which communicates between
the port 104 and the port 105, a ball valve element 107 is disposed
such that it seats on a valve seat integrally formed with the body
103 from the port 104 side. The ball valve element 107 is urged in
the valve-closing direction by a spring 108. Further, a
transmitting member 109 is held on the axis of the body 103 in a
manner axially movable back and forth, for being brought into
contact with the ball valve element 107 to be drivingly controlled
thereby.
[0010] The power element 102 is configured such that a thin-film
diaphragm 113 is held between an upper housing 111 and a lower
housing 112 in a manner dividing between the upper housing 111 and
the lower housing 112. More specifically, the upper housing 111 and
the lower housing 112 are rigidly joined by swaging in a state
sandwiching an outer periphery of the diaphragm 113 therebetween,
such that a vacuum chamber is formed on the upper housing 111 side.
In the vacuum chamber on the upper housing 111 side, there are
arranged a disc 114 disposed in contact with the diaphragm 113 for
spring-receiving use, and a spring 115 urging the disc 114 toward
the diaphragm 113 (i.e., in the valve-opening direction). On the
other hand, the lower housing 112 is engaged with the end of the
body 103 in a state having the upper housing 111 joined thereto.
Within the lower housing 112, the end of the transmitting member
109 extending from the body 103 is connected to the diaphragm 113
via a disc 116.
[0011] Further, the control valve is displaced upward/downward as
viewed in FIG. 15 in response to suction pressure Ps received by
the diaphragm 113, the amount of lift of the ball valve element 107
is determined by the amount of the displacement, whereby the flow
rate of refrigerant supplied from the discharge chamber into the
crankcase is controlled. By this operation, the control valve
varies the amount of refrigerant discharged from the variable
displacement compressor while controlling the pressure Pc in the
crankcase such that suction pressure Ps is maintained constant.
[0012] Such a control valve for an internal variable control
compressor is used for a refrigeration cycle using
chlorofluorocarbon (e.g. HFC-134a) as refrigerant at present, since
it is limited in pressure resistance due to the use of the
thin-film diaphragm as the pressure-sensing member.
[0013] More specifically, when chlorofluorocarbon is used as
refrigerant, if the temperature of the refrigerant changes within a
range of 0 to 15 degrees Celsius or so, discharge pressure Pd
varies within a range of about 0.5 to 3 Mpa, and suction pressure
Ps varies in a range of about 0.3 to 0.45 Mpa.
[0014] By the way, due to the global warming issue, it is proposed
that carbon dioxide is used as refrigerant in the refrigeration
cycle of an automotive air conditioner instead of
chlorofluorocarbon. The basic operation of the refrigeration cycle
using carbon dioxide as refrigerant is also the same in principle
as that of a refrigeration cycle using chlorofluorocarbon. That is,
such a refrigeration cycle is constructed by piping designed such
that refrigerant flows from the compressor, through a gas cooler,
an expansion valve, an evaporator, and an accumulator, and returns
to the compressor. The carbon dioxide refrigerant in gas phase is
compressed by the compressor, and the compressed high-temperature,
high-pressure refrigerant in gas phase is cooled by the gas cooler.
Next, after being decompressed by the expansion valve, the
refrigerant in gas-liquid two-phase is evaporated in the
evaporator, where air in the vehicle compartment is deprived of
latent heat of vaporization to be cooled, and the refrigerant is
separated into gas and liquid phases in the accumulator. The
separated carbon dioxide in gas phase is returned to the
compressor.
[0015] However, in the refrigeration cycle using carbon dioxide as
the refrigerant, suction pressure Ps of the compressor becomes
approximately equal to 3.5 to 6.5 MPa, which is larger than the
refrigeration cycle using chlorofluorocarbon by an order of
magnitude. This makes it impossible for the thin-film diaphragm to
withstand suction pressure Ps, and hence depending on the case,
there is a possibility that the diaphragm is broken or deformed to
have its original characteristics lost. Further, in order to cause
such a pressure-sensing member to effectively operate, it is
necessary to use a spring fairly large in size with a load of
approximately 35 kg/cm.sup.2, for supporting the diaphragm.
Therefore, this makes it difficult to design a control valve if the
control valve is to have the current size of the conventional
control valve for the compressor.
SUMMARY OF THE INVENTION
[0016] The present invention has been made in view of the above
points, and an object thereof is to provide a control valve for an
internal variable control compressor which is improved in pressure
resistance strength of a pressure-sensing member.
[0017] To solve the above problem, the present invention provides a
control valve for a compressor that varies displacement of the
compressor, comprising a body that has a refrigerant passage formed
therein, a valve element that moves to and away from a valve seat
formed in the body in order to adjust a flow rate of refrigerant
when causing part of discharge refrigerant of the compressor to
flow into a control chamber, and a power element that transmits a
driving force which varies according to suction pressure of
refrigerant sucked into a suction chamber of the compressor to the
valve element via a transmitting member, wherein the power element
comprises a diaphragm that senses the suction pressure to be
displaced in an axial direction, and at least one snap-acting disc
disposed to support the diaphragm while being in contact with the
diaphragm from a side of the diaphragm opposite from a side where
the valve element is disposed.
[0018] Further, the present invention provides a control valve for
a compressor that varies displacement of the compressor, comprising
a body that has a refrigerant passage formed therein, a valve
element that moves to and away from a valve seat formed in the body
in order to adjust a flow rate of refrigerant when causing part of
discharge refrigerant of the compressor to flow into a control
chamber, and a power element that transmits a driving force which
varies according to suction pressure of refrigerant sucked into a
suction chamber of the compressor to the valve element via a
transmitting member, wherein the power element is formed by
disposing at least one thin-film snap-acting disc between an upper
housing and a lower housing such that the thin-film snap-acting
disc is sandwiched between the upper housing and the lower housing,
and performing circumferential welding of peripheries thereof, and
is configured such that an axial displacement of the snap-acting
disc caused by sensing the suction pressure at a central part
thereof gives a driving force transmitted to the valve element via
the transmitting member.
[0019] 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
[0020] FIG. 1 is a cross-sectional view of a control valve for a
compressor, according to a first embodiment of the present
invention, in a state accommodated in a housing of a variable
displacement compressor.
[0021] FIG. 2 is a cross-sectional view of the arrangement of the
control valve.
[0022] FIG. 3 is an enlarged view of an area A in FIG. 2.
[0023] FIG. 4 is a explanatory view illustrating spring
characteristics of a snap-acting disc.
[0024] FIG. 5 is a cross-sectional view showing the control valve
at the moment at which the valve is fully closed.
[0025] FIG. 6 is a cross-sectional view showing the snap-acting
discs in a state completely inverted.
[0026] FIG. 7 is a partial cross-sectional view showing the
arrangement of essential parts of a variation of the control
valve.
[0027] FIG. 8 is a cross-sectional view of the arrangement of a
control valve for a compressor according to a second embodiment of
the present invention.
[0028] FIG. 9 is a cross-sectional view of a first variation of the
control valve.
[0029] FIG. 10 is a cross-sectional view of a second variation of
the control valve.
[0030] FIG. 11 is a cross-sectional view of the arrangement of a
control valve for a compressor according to a third embodiment of
the present invention.
[0031] FIG. 12 is a cross-sectional view of the arrangement of a
control valve for a compressor according to a fourth embodiment of
the present invention.
[0032] FIG. 13 is a cross-sectional view of the control valve
according to the first embodiment in a state accommodated in the
housing of the compressor.
[0033] FIG. 14 is a partial cross-sectional view of the compressor
in an operating state during control operation.
[0034] FIG. 15 is a cross-sectional view of an example of the
arrangement of a conventional control valve for a internal variable
control compressor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] Hereafter, embodiments of the present invention will be
described in detail with reference to the drawings. It should be
noted that the positional relationship between components is
sometimes expressed as "upper" or "lower" with reference to the
states shown in the drawings, for convenience sake.
First Embodiment
[0036] FIG. 1 is a cross-sectional view of a control valve for a
compressor, according to a first embodiment of the present
invention, in a state accommodated in a housing of a variable
displacement compressor. FIG. 2 is a cross-sectional view of the
arrangement of the control valve.
[0037] As shown in FIG. 1, the control valve 1 is inserted and
disposed in a refrigerant passage in the form of a stepped hole
formed in a housing 2 of the variable displacement compressor, and
is fixed in the housing 2 by bolts 4 via a plate-shaped cover 3.
The control valve 1 includes a body 5 through which refrigerant
passages are formed. The body 5 is formed with a port 6
communicating with a discharge chamber of the variable displacement
compressor, a port 7 communicating with a crankcase as a control
chamber of the compressor, and a port 8 communicating with a
suction chamber.
[0038] As shown in FIG. 2, the control valve 1 includes a valve
main unit 11 containing a valve section, and a power element 12
which controls the valve section such that the valve section opens
and closes.
[0039] The body 5 of the valve main unit 11 is made of brass, and
is formed as mentioned above with the port 6 communicating with the
discharge chamber to introduce discharge pressure Pd, the port 7
communicating with the crankcase to output controlled pressure,
that is, crankcase pressure PC, and the port 8 communicating with
the suction chamber to receive suction pressure Ps. A ball valve
element 14 is disposed in a refrigerant passage communicating
between the port 6 and the port 7, such that the ball valve element
14 moves to and away from a valve seat 13 integrally formed with
the body 5 on the port 6 side. The ball valve element 14 is urged
in the valve-closing direction by a conical spring 15. An opening
in a bottom end of the body 5 where the port 6 is disposed is
swaged inward to form a spring-receiving portion 16. One end of the
conical spring 15 supports the ball valve element 14, and the other
end of the same is supported by the spring-receiving portion 16.
Further, the opening in the bottom end of the body 5 is capped by a
strainer 17 to prevent foreign matter from entering.
[0040] A stainless-steel transmitting member 19 having one end
brought into contact with the ball valve element 14 for being
drivingly controlled thereby is slidably inserted into a guide hole
18 formed along the axis of the body 5, and is held in a manner
movable back and forth in the axial direction.
[0041] On the other hand, the power element 12 is formed by
assembling a lid-like upper housing 21 having a shallow spring
accommodating portion 20, and a hollow cylindrical lower housing 22
having a flange at an opening in one end thereof, such that a
thin-film metal diaphragm 23 is sandwiched between the upper
housing 21 and the lower housing 22. Four snap-acting discs 24
having the same shape are disposed in layers in the spring
accommodating portion 20 of the upper housing 21. The upper housing
21, the lower housing 22, the diaphragm 23, and the snap-acting
discs 24 are all made of stainless-steel.
[0042] More specifically, the power element 12 is made by placing
the snap-acting discs 24 in the spring accommodating portion 20 of
the upper housing 21, placing the diaphragm 23 such that the
periphery of the diaphragm 23 is held between the bottom face of
the peripheral end of the upper housing 21 and the flange of the
lower housing 22 and performing circumferential welding W along a
boundary of these layered parts. The welding is performed by laser
welding under vacuum atmosphere, so that a space surrounded by the
upper housing 21 and the diaphragm 23 is placed under vacuum.
[0043] Then, the power element 12 is assembled to the valve main
unit 11 by press-fitting the lower housing 22 on the top end of the
body 5. In the central part of the top end of the body 5, a
refrigerant passage 25 communicating between the port 8 and the
inside of the lower housing 22 is formed such that suction pressure
Ps can be introduced to the underside of the diaphragm 23. Further,
the transmitting member 19 has the top end thereof inserted in the
refrigerant passage 25 and is connected to the underside of the
diaphragm 23 via a disc 26 having a bottomed hollow cylindrical
shape. Therefore, displacement of the diaphragm 23 is transmitted
to the ball valve element 14 via the disc 26 and the transmitting
member 19 to cause the valve section to open and close.
[0044] FIG. 3 is an enlarged view of an area A in FIG. 2. FIG. 4 is
an explanatory view illustrating spring characteristics of a
snap-acting disc. A horizontal axis in FIG. 4 represents suction
pressure Ps, and a vertical axis represents displacement of the
snap-acting disc (to be more precise, a position of the central
part with respect to the periphery of the snap-acting disc).
[0045] As shown in FIG. 3, each snap-acting disc 24 is formed by
stamping out stainless plate into a circular shape, and then
pressing the circular stainless plate into a shape trapezoidal in
cross-section. For example, the snap-acting disc 24 is formed such
that it has a thickness of 0.25 mm, an outer diameter of 16 mm, and
a diameter of a central flat part of 10 mm, and the periphery
thereof is tapered. In illustrated example, four of the snap-acting
discs 24 are stacked in the direction of thickness, and the bottom
snap-acting disc 24 is brought into contact with the diaphragm 23
to urge the diaphragm 23 downward (in the valve-opening direction).
An edge 28 of the periphery of the top snap-acting disc 24 is
stopped by a sidewall of the upper housing 21, and the stack of the
snap-acting discs 24 is held in a state sandwiched between the
diaphragm 23 and the upper housing 21. A contact surface 29 of the
upper housing 21 for being brought into contact with the edge 28 is
tapered at an inclination angle of e.g. 15 degrees, such that a
support for supporting the snap-acting discs 24 (a contact point or
a contact line between the edge 28 and the contact surface 29 forms
the support in the present embodiment) performing an inverting
operation (operation in which a direction in which a central part
of each snap-acting disc 24 is convex is inverted) is hardly
changes before or after the inverting operation of the snap-acting
discs 24. Moreover, a shape of the inner wall of the upper housing
21 is formed such that it substantially matches the inverted shape
of the snap-acting discs 24, and the spring accommodating portion
20 is formed to be small in size. For this reason, the upper
housing 21 is configured to be small, and hence it greatly
contributes to downsizing of the control valve 1.
[0046] As shown in FIG. 4, the stack of the four snap-acting discs
24 has characteristics that it is displaced in the valve-opening
direction or the valve-closing direction depending on the suction
pressure Ps. That is, each snap-acting disc 24 has a shape that the
central part thereof is convex toward the transmitting member 19,
and hence the amount of displacement (particularly, a position of
the central part of the snap-acting disc 24 with respect to the
support at the periphery of the same) is set to be approximately
0.3 mm when the suction pressure Ps received by the diaphragm 23 is
in a low range. Then, when suction pressure Ps becomes higher, the
stack of the snap-acting discs 24 is displaced in the valve-closing
direction little by little, and when suction pressure Ps becomes
equal to a predetermined value (approximately 3.7 MPa in the
present embodiment), the stack becomes flat. At this time, the ball
valve element 14 is seated on the valve seat 13 to close the valve.
As suction pressure Ps becomes higher than the predetermined value,
the stack is inverted in shape, and the amount of displacement
changes up to approximately -0.3 mm. At this time, the control
valve 1 maintains the fully closed state. If suction pressure Ps
inversely becomes lower from this state, the snap-acting discs 24
are displaced in the valve-opening direction little by little, and
when suction pressure Ps becomes equal to the predetermined value
(approximately 3.5 MPa in the present embodiment), the stack
returns to the flat shape. As suction pressure Ps becomes lower
than the predetermined value, the amount of displacement changes up
to approximately 0.3 mm. At this time, the ball valve element 14 is
lifted from the valve seat 13 to open the valve. It should be noted
that the snap-acting discs 24 have so-called hysteresis
characteristics that displacement changes in different ways between
when suction pressure Ps increases and when suction pressure Ps
decreases, and therefore, the stack of the snap-acting discs 24 is
used such that insofar as the control valve 1 is open to perform a
control operation, the stack of the snap-acting discs 24 is not
inverted.
[0047] Next, a description will be given of the operation of the
control valve. FIG. 5 is a cross-sectional view showing the control
valve at the moment at which the valve is fully closed. FIG. 6 is a
cross-sectional view showing the snap-acting discs in a state
completely inverted. It should be noted that FIG. 1, with reference
to which the above description has been given, shows an open state
of the valve.
[0048] In the control valve 1, the diaphragm 23 receives the
suction pressure Ps to be displaced upward or downward as viewed in
the figures. The amount of the displacement determines the amount
of lift of the ball valve element 14, which in turn controls the
flow rate of refrigerant supplied from the discharge chamber into
the crankcase. By this operation, the control valve 1 controls
crankcase pressure PC such that suction pressure Ps becomes
constant to vary the discharge amount of refrigerant discharged
from the variable displacement compressor.
[0049] More specifically, when suction pressure Ps is low (lower
than approximately 3.7 MPa), as shown in FIG. 1, a spring load by
the stack of the snap-acting discs 24 is transmitted to the ball
valve element 14 via the diaphragm 23, the disc 26, and the
transmitting member 19, whereby the valve section is made open. At
this time, discharge pressure Pd introduced via the port 6 turns
into crankcase pressure PC controlled via the valve section to be
introduced to the crankcase. This controls the displacement of the
variable displacement compressor.
[0050] Then, when suction pressure Ps increases to become equal to
the predetermined pressure (approximately 3.7 MPa in the illustrate
example), as shown in FIG. 5, the stack of the snap-acting discs 24
starts to be inverted in shape. The illustrated example is
configured such that when the diaphragm 23 and the snap-acting
discs 24 become flat or horizontal, the ball valve element 14 is
seated on the valve seat 13 to realize the valve-closed state.
[0051] Then, when suction pressure Ps becomes higher than the
predetermined pressure, as shown in FIG. 6, the stack of the
snap-acting discs 24 completes inversion and is supported by the
inner wall of the upper housing 21 in a manner brought into
substantially close contact therewith. At this time, the
transmitting member 19 may move away from the ball valve element 14
seated on the valve seat 13, as shown in FIG. 6, depending on the
magnitude of crankcase pressure PC.
[0052] On the other hand, when suction pressure Ps decreases from
the state shown in FIG. 6 to become lower than the predetermined
pressure (approximately 3.5 MPa in the illustrated example), the
control valve 1 operates in an opposite way from the
above-described operation to shift to the open state, and this
makes it possible to perform the minimum displacement operation.
When the control valve 1 opens in this way, suction pressure Ps
becomes higher, and when suction pressure Ps reaches the
predetermined pressure, the stack of the snap-acting discs 24 is
inverted in shape again. According to such an operation of the
snap-acting discs 24, suction pressure Ps is controlled such that
it is fixed at the predetermined pressure.
[0053] As described above, in the control valve 1 according to the
present embodiment, the stack of the snap-acting discs 24 is
disposed on an opposite side of the diaphragm 23 forming the
pressure-sensing section, from the transmitting member 19.
Therefore, even if the diaphragm 23 receives high suction pressure
Ps when the control valve 1 is open, since the snap-acting discs 24
receive suction pressure Ps from the opposite side, the diaphragm
23 is prevented from being broken or deformed. Therefore, this
makes it possible to improve pressure resistance strength of the
pressure-sensing section. As a result, even if the control valve 1
is applied to a refrigeration cycle where suction pressure Ps
becomes high, including one using carbon dioxide as refrigerant, it
is possible to secure a sufficient pressure resistance
strength.
[0054] On the other hand, the stack of the snap-acting discs 24
operates to be inverted in shape when the load in the valve-closing
direction received from the diaphragm 23 becomes larger than the
predetermined value, so that the valve-closing operation of the
ball valve element 14 is not impaired. Further, since the
snap-acting discs 24 return to the original shapes when the load in
the valve-closing direction received from the diaphragm 23 becomes
less than the predetermined value, the snap-acting discs 24 can
continue to support the diaphragm 23.
[0055] Although no related description is given in the present
embodiment, in order to prevent the deformation of the stack of the
snap-acting discs 24 and that of the diaphragm 23 from being
impaired by friction between the stacked snap-acting discs 24, or
friction between the snap-acting discs 24 and the diaphragm 23, a
friction-reducing structure may be provided between the snap-acting
discs 24, or between the snap-acting discs 24 and the diaphragm 23.
FIG. 7 is a partial cross-sectional view of the arrangement of
essential parts of a variation of the control valve.
[0056] More specifically, an interference prevention film 31 may be
interposed between each adjacent pair of the snap-acting discs 24.
Further, an interference prevention film 32 may be interposed
between the stack of the snap-acting discs 24 and the diaphragm 23.
Thin films of polyimide or thin films of Teflon (registered
trademark) may be used as these films. Alternatively, instead of
such a film, grease may be applied between the snap-acting discs
24, or between the stack of the snap-acting discs 24 and the
diaphragm 23.
[0057] Although in the present embodiment, the diaphragm 23 and the
transmitting member 19 are indirectly connected to each other via
the disc 26, by way of example, the disc 26 may be omitted to bring
the diaphragm 23 and the transmitting member 19 into direct contact
with each other.
[0058] Further, although in the present embodiment, a stack is
formed by stacking four snap-acting discs 24, by way of example,
the number of the snap-acting discs 24 forming the stack is not
limited to four, but it is possible to select the number
appropriately depending on the spring load to be obtained.
[0059] Moreover, although in the present embodiment, a vacuum
chamber is formed by the upper housing 21 and the diaphragm 23, by
way of example, since the upper housing 21 and the lower housing 22
are joined by laser welding, a space surrounded by the upper
housing 21 and the diaphragm 23 need not be under vacuum, but the
space may be under atmospheric pressure or the like. For example,
welding may be performed under atmospheric pressure, or there a
hole may be formed through the upper housing 21, for communication
between the inside and the outside thereof.
Second Embodiment
[0060] Next, a description will be given of a second embodiment of
the present invention. A control valve for a compressor according
to the present embodiment is configured similarly to the control
valve according to the first embodiment, except that only one
snap-acting disc is disposed. Therefore, description of component
parts configured substantially similarly to those of the component
parts of the first embodiment is omitted as deemed appropriate
while denoting the component parts by identical reference numerals.
FIG. 8 is a cross-sectional view of the arrangement of the control
valve according to the second embodiment of the present
invention.
[0061] In the control valve 201, only one snap-acting disc 24 is
disposed in an upper housing 203 of a power element 202.
Accordingly, a spring accommodating portion 204 of the upper
housing 203 is also configured to be small. However, the control
valve 201 is designed such that a desired spring load can be
obtained by the one snap-acting discs 24.
[0062] Also in the control valve 201 according to the present
embodiment, since the snap-acting disc 24 is disposed on an
opposite side of the diaphragm 23 from the transmitting member 19,
even if the diaphragm 23 receives relatively high suction pressure
Ps, the snap-acting disc 24 receives the suction pressure Ps, from
the opposite side. As a result, the diaphragm 23 is prevented from
being broken or deformed, which makes it possible to improve
pressure resistance strength of the pressure-sensing section.
Therefore, if the spring load which one snap-acting disc 24 has is
large, the control valve 201 can be applied to a refrigeration
cycle where suction pressure Ps is high, such as one using carbon
dioxide or the like. Moreover, even if the spring load which one
snap-acting disc 24 has cannot withstand the refrigeration cycle
using carbon dioxide or the like, it is possible to apply the same
to the refrigeration cycle using chlorofluorocarbon (i.e. HFC-134a)
or refrigerant which is used under higher pressure than
chlorofluorocarbon.
[0063] It should be noted that various variations of the control
valve having one snap-acting disc 24 disposed therein as described
above can be envisaged.
[0064] FIG. 9 is a cross-sectional view of a first variation of the
control valve.
[0065] As shown in FIG. 9, an interference prevention film 225 may
be interposed between the snap-acting disc 24 of a power element
222 and the diaphragm 23. A thin film of polyimide or a thin film
of Teflon (registered trademark) may employed as this film.
Alternatively, grease may be applied between the snap-acting disc
24 and the diaphragm 23. The film 225 is fixed such that the
periphery of the film 225 is held between an upper housing 223 and
the lower housing 22 together with the diaphragm 23.
[0066] FIG. 10 is a cross-sectional view of a second variation of
the control valve.
[0067] As shown in FIG. 10, the bottom opening of a body 205 of a
valve main unit 211 is not swaged, but a ring-shaped
spring-receiving member 216 may be press-fitted into the bottom
opening to support the conical spring 15 urging the ball valve
element 14 in the valve-closing direction. In this way, the load of
the conical spring 15 can be adjusted by the amount of
press-fitting of the spring-receiving member 216.
[0068] It should be noted that the structure of the
spring-receiving member is not limited to that shown in the
drawing, various shapes can be applied. Further, a screw portion
may be formed in the bottom opening of the body 205 and on the
another spring receiving member, and the load of the conical spring
15 may be adjusted by the screwing amount of the spring receiving
member into the body 205.
Third Embodiment
[0069] Next, a description will be given of a third embodiment of
the present invention. A control valve for a compressor according
to the present embodiment is configured similarly to the control
valve according to the second embodiment, except that the power
element is configured differently. Therefore, description of
component parts configured substantially similarly to those of the
component parts of the second embodiment is omitted as deemed
appropriate while denoting the component parts by identical
reference numerals. FIG. 11 is a cross-sectional view of the
arrangement of the control valve according to the third
embodiment.
[0070] In the control valve 301, a spring accommodating portion 304
of an upper housing 303 of a power element 302 is formed to be
large in size, and a auxiliary spring 305 in a coil form is
disposed for providing an urging force in a valve-opening direction
for assisting the spring force of the snap-acting discs 24. A
disc-shaped spring receiver 306 is interposed between the
snap-acting disc 24 and the auxiliary spring 305, and a disc-shaped
spring receiver 307 is interposed between an upper wall surface of
the upper housing 303 and the snap-acting disc 24. Therefore, the
spring load of the auxiliary spring 305 is transmitted to the
snap-acting disc 24 via the spring receiver 306, and the spring
receiver 306 supports the snap-acting disc 24 from a side thereof
opposite from the diaphragm 23. The spring load of the auxiliary
spring 305 can be adjusted by deforming a central part of the upper
wall surface of the upper housing 303 by pressing the same, as
illustrated in FIG. 11 (corresponds to "a load-adjusting
structure").
[0071] In the control valve 301 according to the present embodiment
as well, the snap-acting disc 24 is disposed on the side of the
diaphragm 23 opposite from the transmitting member 19, and
therefore, even if the diaphragm 23 receives high suction pressure
Ps, the snap-acting disc 24 receives the suction pressure Ps, from
the opposite side. Further, the auxiliary spring 305 is provided on
the opposite side of the snap-acting disc 24 from the diaphragm 23
whereby a lack of sprig load by the snap-acting discs 24 is
compensated for. As a result, it is possible to improve pressure
resistance strength of the pressure-sensing section more than the
second embodiment, whereby the diaphragm 23 is prevented from being
broken or deformed. Therefore, the control valve can be applied to
the refrigeration cycle where suction pressure Ps becomes high,
such as one using carbon dioxide or the like.
[0072] Further, since the auxiliary spring 305 is a spring that
compensates for a lack of spring load of the snap-acting discs 24,
a very large spring load is not required. Therefore, the auxiliary
spring 305 rarely makes it difficult to design the control valve
301.
[0073] Although the present embodiment shows the configuration in
which one snap-acting disc 24 is disposed, a stack of snap-acting
discs 24 may be disposed, as in the case of the first embodiment,
whereby a spring having a small spring load may be used as the
auxiliary spring.
[0074] Further, the load-adjusting structure is not limited to the
one described above, but there may be used a structure in which the
position of a spring receiving member corresponding to the spring
receiver 307 can be adjusted by press-fitting or screwing the
spring receiving member into the upper housing to thereby adjust
the spring load.
Fourth Embodiment
[0075] Next, a description will be given of a fourth embodiment of
the present invention. A control valve for a compressor according
to the present embodiment is configured similarly to that according
to the first embodiment, except that a snap-acting disc is used in
place of the diaphragm. Therefore, description of component parts
configured substantially similarly to those of the component parts
of the first embodiment is omitted as deemed appropriate while
denoting the component parts by identical reference numerals. FIG.
12 is a cross-sectional view of the arrangement of the control
valve according to the fourth embodiment.
[0076] A diaphragm is not disposed in a power element 402 of the
control valve 401. A stack of four snap-acting discs 424 is fixed
in a manner sandwiched between an upper housing 421 and the lower
housing 22.
[0077] More specifically, the snap-acting discs 424 are configured
to be larger in size than the snap-acting discs 24 according to the
first embodiment in the radial direction, and has the approximately
same outer diameter as the upper housing 421. The power element 402
is formed by arranging the stack of the snap-acting discs 424
between the upper housing 421 and the lower housing 22 in a manner
sandwiched therebetween, and performing circumferential welding W2
on peripheries of these layered parts by laser welding. The bottom
snap-acting disc 424 has its central part connected to the
transmitting member 19 via the disc 26. The stack of the
snap-acting discs 424 is capable of performing inverting operation
using the vicinity of the periphery thereof as a support, and
operates in response to suction pressure Ps of the variable
displacement compressor to transmit driving force in the axial
direction to the transmitting member 19.
[0078] As described hereinabove, in the control valve 401 according
to the present embodiment, not the diaphragm but the snap-acting
disc 424 forms the pressure-sensing section. When the upper housing
421 and the lower housing 22 are assembled, the stack of the
snap-acting discs 424 has its periphery fixed by welding at the
same time, which makes the working much simplified. Further, the
stack of the snap-acting discs 424 is inverted using the vicinity
of its periphery as the support. Since the stack of the snap-acting
discs 424 is used in place of the diaphragm, it is possible to
maintain the strength of the pressure-sensing section higher than
when the diaphragm is used. Therefore, the control valve can be
applied to a refrigeration cycle where suction pressure Ps is high,
such as one using carbon dioxide as refrigerant.
[0079] Although the present embodiment shows the configuration in
which the stack of the snap-acting discs 424 and the transmitting
member 19 are indirectly connected to each other via the disc 26,
by way of example, the disc 26 may be omitted to bring the stack of
snap-acting discs 424 and the transmitting member 19 into direct
contact with each other.
[0080] Although in the present embodiment, the upper housing 421,
the stack of the snap-acting discs 424, and the lower housing 22
are joined by laser welding, so that a vacuum chamber is formed by
the upper housing 421 and the snap-acting disc 424, a space
surrounded by the upper housing 421 and the snap-acting disc 424
need not be under vacuum, but the space may be under atmospheric
pressure or the like. For example, welding may be performed under
atmospheric pressure, or a hole may be formed through the upper
housing 421, for communication between the inside and the outside
thereof.
[0081] Although in the present embodiment, the description is given
of the case where the control valve according to the present
invention is applied to the variable displacement compressor to
control the pressure in the crankcase as a control chamber of the
compressor, it is possible to apply the control valve to a
compressor which does not have a variable displacement mechanism. A
description will be given of a specific example of the application,
hereinafter.
[0082] FIG. 13 is a cross-sectional view of the control valve
according to the first embodiment in a state accommodated in a
housing of a compressor. FIG. 14 is a partial cross-sectional view
of the compressor in an operating state during control
operation.
[0083] The compressor 41 is a type the displacement of which is not
varied when it is driven by an engine at a fixed rotational speed,
and may be a rotary-type or reciprocating type compressor, such as
a rotary compressor or a scroll compressor. Such a compressor 41
can vary the refrigerant discharge capacity by controlling the flow
rate of refrigerant sucked into the suction chamber. For this
reason, the compressor 41 includes a throttle control valve 42 in a
passage on the suction side, and the control valve 1 according to
the first embodiment is used for controlling the throttle control
valve 42.
[0084] The throttle control valve 42 has a valve seat 43 disposed
in the passage on the suction side, and a hollow cylindrical valve
element 44 is disposed in a manner movable to and away from the
valve seat 43. The valve element 44 is integrally formed with a
piston 46 disposed in a piston chamber 45 in a manner movable back
and forth in the valve-opening/closing direction of the throttle
control valve 42, and is urged in the valve-opening direction by a
spring 47. It should be noted that the piston chamber 45 forms a
control chamber of the throttle control valve 42. Further, an
orifice 48 communicating between the passage of the suction side
and the piston chamber 45 is formed through the valve element
44.
[0085] Here, the control valve 1 is disposed in the compressor 41
such that the port 6 where suction pressure Ps is introduced
communicates with the discharge chamber, the port 7 through which
the controlled pressure Pp is delivered communicates with the
piston chamber 45 of the throttle control valve 42, and the port 8
which receives suction pressure Ps communicates with the passage on
the suction side.
[0086] In the compressor 41 constructed as described above, when
suction pressure Ps is sufficiently lower than a predetermined
pressure (e.g. 3.6 MPa), as shown in FIG. 13, the pressure-sensing
section is displaced toward the ball valve element 14 in response
to low suction pressure Ps, and the displacement causes the control
valve 1 to be opened. At this time, discharge pressure Pd is
introduced into the piston chamber 45 as the control chamber of the
throttle control valve 42 via the opened control valve 1, so that
pressure Pp in the piston chamber 45 is high. For this reason,
since the piston 46 is pressed in the valve-closing direction, the
hollow cylindrical valve element 44 is seated on the valve seat 43,
and the throttle control valve 42 is in a fully closed state. Since
the control valve 1 is in a state incapable of drawing refrigerant,
the compressor 41 is in a state where the refrigerant discharge
capacity is small.
[0087] On the other hand, when suction pressure Ps increases up to
the predetermined pressure (e.g. 3.6 MPa), the pressure-sensing
section is displaced, as shown in FIG. 14, to a side opposite from
the ball valve element 14 due to high suction pressure Ps, and the
displacement causes the control valve 1 to be closed. At this time,
since discharge pressure Pd is not introduced into the piston
chamber 45, pressure Pp in the piston chamber 45 is made
substantially equal to suction pressure Ps via the orifice 48. For
this reason, since the piston 46 is pressed in the valve-opening
direction by the spring 47, the hollow cylindrical valve element 44
is moved away from the valve seat 43, and the throttle control
valve 42 is fully open. Since the throttle control valve 42 is in a
state capable of sucking the refrigerant at maximum, the compressor
41 is in a state where the refrigerant discharge capacity is
large.
[0088] Further, as suction pressure Ps becomes lower from the
predetermined pressure to cause the throttle control valve 42 to
move from the fully open state shown in FIG. 14 to the fully closed
state shown in FIG. 13, the pressure Pp of the piston chamber 45
progressively becomes lower, and the throttle control valve 42
throttles the passage of the suction side in response thereto, and
hence the displacement of the compressor 41 can be continuously
varied in a decreasing direction.
[0089] In this way, in the compressor 41 without the variable
displacement mechanism, it is possible to make variable the
refrigerant discharge capacity by controlling the pressure Pp in
the piston chamber 45 as the control chamber of the throttle
control valve 42 using the control valve 1.
[0090] In the control valve for a compressor according to the
present invention, a snap-acting disc is disposed in a
pressure-sensing section to receive suction pressure. This makes it
possible to improve pressure resistance strength of the
pressure-sensing section.
[0091] 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.
* * * * *