U.S. patent application number 11/525017 was filed with the patent office on 2007-03-29 for pressure control valve.
This patent application is currently assigned to Fujikoki Corporation. Invention is credited to Hisashi Asano, Sadatake Ise, Masaki Tomaru.
Application Number | 20070068194 11/525017 |
Document ID | / |
Family ID | 37517287 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070068194 |
Kind Code |
A1 |
Ise; Sadatake ; et
al. |
March 29, 2007 |
Pressure control valve
Abstract
A pressure control valve includes a valve main body (10A) having
a high-pressure refrigerant inlet port (11) and a low-pressure
refrigerant outlet port (12); a valve seat-attached valved
passageway (20) formed in the valve main body (10A) for
decompressing and guiding the refrigerant from the high-pressure
refrigerant inlet port (11) to the low-pressure refrigerant outlet
port (12) and configured to enable a differential pressure
regulating valve (15) to be fitted therein; and a throttling
passageway (30) provided with an orifice (32) having a
predetermined effective cross-sectional area for enabling the
high-pressure refrigerant inlet port (11) to communicate, through
short-cutting or detouring the valve seat (21), with a region of
the valved passageway which is located downstream side of the valve
seat (21), thereby enabling a magnitude of lift of the differential
pressure regulating valve (15) from the valve seat (21) to be
altered depending on a magnitude of difference in pressure between
a high-pressure side and a low-pressure side.
Inventors: |
Ise; Sadatake; (Tokyo,
JP) ; Tomaru; Masaki; (Tokyo, JP) ; Asano;
Hisashi; (Tokyo, JP) |
Correspondence
Address: |
BAKER & BOTTS L.L.P.
30 ROCKEFELLER PLAZA
44TH FLOOR
NEW YORK
NY
10112-4498
US
|
Assignee: |
Fujikoki Corporation
Tokyo
JP
|
Family ID: |
37517287 |
Appl. No.: |
11/525017 |
Filed: |
September 21, 2006 |
Current U.S.
Class: |
62/527 |
Current CPC
Class: |
F25B 2600/2505 20130101;
F25B 2500/01 20130101; G05D 16/103 20130101; F25B 2309/061
20130101; F25B 41/31 20210101 |
Class at
Publication: |
062/527 |
International
Class: |
F25B 41/06 20060101
F25B041/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2005 |
JP |
2005-276513 |
Claims
1. A pressure control valve comprising: a valve main body having a
high-pressure refrigerant inlet port and a low-pressure refrigerant
outlet port; a valve seat-attached valved passageway formed in the
valve main body for decompressing and guiding the refrigerant from
the high-pressure refrigerant inlet port to the low-pressure
refrigerant outlet port and configured to enable a differential
pressure regulating valve to be fitted therein; and a throttling
passageway provided with an orifice having a predetermined
effective cross-sectional area for enabling the high-pressure
refrigerant inlet port to communicate, through short-cutting or
detouring the valve seat, with a region of the valved passageway
which is located downstream side of the valve seat, to enable a
magnitude of lift of the differential pressure regulating valve
from the valve seat to be altered depending on a magnitude of
difference in pressure between a high-pressure side and a
low-pressure side.
2. The pressure control valve according to claim 1, wherein the
valve seat-attached valved passageway comprises: a cylinder portion
formed contiguous with the high-pressure refrigerant inlet port and
provided, at a downstream end portion thereof, with the valve seat,
an enlarged spring chamber formed contiguous with the downstream
side of the cylinder portion and having a larger diameter than a
diameter of the cylinder portion, a downstream passageway formed
contiguous with the low-pressure refrigerant outlet port, and a
communicating passageway for enabling the spring chamber to
communicate with the downstream passageway.
3. The pressure control valve according to claim 2, wherein the
differential pressure regulating valve comprises a valve portion
mounted retractively on the valve seat, a piston inserted slidably
in the cylinder portion and having a diametrally enlarged portion
on the distal end side thereof and a diametrally contracted portion
on the valve portion side, and a spring shoe for receiving a
valve-closing spring placed in the spring chamber, wherein the
piston includes a longitudinal hole therein and a lateral hole for
enabling a valve chamber formed between an inner circumferential
wall of the cylinder portion and an outer circumferential wall of
the diametrally contracted portion of the piston to be in
communication with the high-pressure refrigerant inlet port.
4. The pressure control valve according to claim 3, wherein a
vibration-proof O-ring is interposed between the diametrally
enlarged portion of the piston in the differential pressure
regulating valve and the cylinder portion.
5. The pressure control valve according to claim 3, wherein the
valve portion of the differential pressure regulating valve
includes a circular conical surface.
6. The pressure control valve according to claim 3, wherein an
adjusting screw is screw-engaged with the spring chamber so as to
make it possible to adjust the set-load of the valve-closing
valve.
7. The pressure control valve according to claim 3, wherein the
throttling passageway comprises a throttling hole-attached
passageway formed contiguous with the low-pressure refrigerant
outlet port, and a by-pass passageway formed so as to detour the
valve seat portion and to enable the high-pressure refrigerant
inlet port to be in communication with a region of the throttling
hole-attached passageway which is located upstream in relative with
the throttling hole.
8. The pressure control valve according to claim 1, the orifice of
the throttling passageway including a throttling hole having a
predetermined bore size, the pressure control valve further
comprising a needle valve which is designed to be inserted into the
throttling hole.
9. The pressure control valve according to claim 8, wherein the
position of the needle valve is displaceable relative to the
throttling hole as so to make it possible to adjust the effective
cross-sectional area of the passageway of the orifice.
10. The pressure control valve according to claim 1, wherein: the
valve seat-attached valved passageway comprises a cylinder portion
formed contiguous with the high-pressure refrigerant inlet port and
provided, at a downstream end portion thereof, with the valve seat;
and an enlarged spring chamber formed contiguous with the
downstream side of the cylinder portion and also with the
low-pressure refrigerant outlet port and having a larger diameter
than a diameter of the cylinder portion; and the differential
pressure regulating valve comprises a valve portion mounted
retractively on the valve seat, a piston inserted slidably in the
cylinder portion and having a diametrally enlarged portion on the
distal end side thereof and a diametrally contracted portion on the
valve portion side, and a spring shoe for receiving a valve-closing
spring placed in the spring chamber, wherein the piston includes
not only a longitudinal hole therein and a lateral hole to enable a
valve chamber formed between an inner circumferential wall of the
cylinder portion and an outer circumferential wall of the
diametrally contracted portion of the piston to be in communication
with the high-pressure refrigerant inlet port, but also with the
orifice which is formed so as to enable the longitudinal hole with
the spring chamber.
11. The pressure control valve according to claim 10, wherein an
adjusting screw is screw-engaged with the spring chamber so as to
make it possible to adjust the set-load of the valve-closing valve,
and the adjusting screw is provided with a longitudinal hole and a
lateral hole for enabling the spring chamber to be communicated
with the low-pressure refrigerant outlet port.
12. A pressure control valve comprising: a valve main body having a
high-pressure refrigerant inlet port and a low-pressure refrigerant
outlet port; a valve seat-attached valved passageway formed in the
valve main body for decompressing and guiding the refrigerant from
the high-pressure refrigerant inlet port to the low-pressure
refrigerant outlet port and configured to enable a constant
pressure regulating valve to be fitted therein; and a throttling
passageway provided with an orifice having a predetermined
effective cross-sectional area for enabling the high-pressure
refrigerant inlet port to communicate, through short-cutting or
detouring the valve seat, with a region of the valved passageway
which is located downstream side of the valve seat, to enable a
magnitude of lift of the constant pressure regulating valve from
the valve seat to be altered depending on a magnitude of pressure
on the high-pressure side.
13. The pressure control valve according to claim 12, wherein the
valve seat-attached valved passageway comprises a cylinder portion
formed contiguous with the high-pressure refrigerant inlet port and
provided, at a downstream end portion thereof, with the valve seat,
and an enlarged spring chamber formed contiguous with the
downstream side of the cylinder portion and communicating with the
low-pressure refrigerant outlet port, the spring chamber having a
larger diameter than that of the cylinder portion.
14. The pressure control valve according to claim 13, wherein the
constant pressure regulating valve comprises: a valve portion
mounted retractively on the valve seat; a piston inserted slidably
in the cylinder portion and having a diametrally enlarged portion
on the distal end side thereof and a diametrally contracted portion
on the valve portion side; a spring shoe for receiving a
valve-closing spring placed in the spring chamber; and a stem
portion formed contiguous with the valve portion; wherein the
piston includes a longitudinal hole therein and a lateral hole to
enable a valve chamber formed between an inner circumferential wall
of the cylinder portion and an outer circumferential wall of the
diametrally contracted portion of the piston to be in communication
with the high-pressure refrigerant inlet port; the constant
pressure regulating valve being also featured in that atmospheric
pressure is to be received by an end face of the stem portion which
faces opposite to the piston.
15. The pressure control valve according to claim 14, wherein the
valve portion of the constant pressure regulating valve includes a
circular conical surface.
16. The pressure control valve according to claim 14, wherein an
adjusting screw is screw-engaged with the spring chamber so as to
make it possible to adjust the set-load of the valve-closing valve
and includes a through-hole into which the stem portion is slidably
inserted.
17. The pressure control valve according to claim 14, wherein the
throttling passageway includes a throttling hole-attached
passageway formed contiguous with the low-pressure refrigerant
outlet port, and a by-pass passageway formed in a manner to detour
the valve seat portion and to enable the throttling hole-attached
passageway to be in communication with the spring chamber.
18. The pressure control valve according to claim 12, the orifice
of the throttling passageway including a throttling hole having a
predetermined bore size, the pressure valve further comprising a
needle valve which is designed to be inserted into the throttling
hole.
19. The pressure control valve according to claim 18, wherein the
position of the needle valve is displaceable relative to the
throttling hole as so to make it possible to adjust the effective
cross-sectional area of the passageway of the orifice.
20. The pressure control valve according to claim 12, wherein: the
valve seat-attached valved passageway comprises a cylinder portion
formed contiguous with the high-pressure refrigerant inlet port and
provided, at a downstream end portion thereof, with the valve seat;
and an enlarged spring chamber formed contiguous with the
downstream side of the cylinder portion and also with the
low-pressure refrigerant outlet port and having a larger diameter
than a diameter of the cylinder portion; and the constant pressure
regulating valve comprises a valve portion mounted retractively on
the valve seat, a piston inserted slidably in the cylinder portion
and having a diametrally enlarged portion on the distal end side
thereof and a diametrally contracted portion on the valve portion
side, a spring shoe for receiving a valve-closing spring placed in
the spring chamber, and a stem portion formed contiguous with the
valve portion, wherein the piston includes not only a longitudinal
hole therein and a lateral hole to enable a valve chamber formed
between an inner circumferential wall of the cylinder portion and
an outer circumferential wall of the diametrally contracted portion
of the piston to be in communication with the high-pressure
refrigerant inlet port, but also the orifice which is formed so as
to enable the longitudinal hole with the spring chamber.
21. The pressure control valve according to claim 1, wherein the
valve seat is provided with a V-shaped trench functioning as the
orifice.
22. The pressure control valve according to claim 12, wherein the
valve seat is provided with a V-shaped trench functioning as the
orifice.
Description
FIELD
[0001] The present invention relates to a pressure control valve
which is adapted to be integrated into a steam-compression type
refrigerating cycle where CO.sub.2 is employed as a refrigerant
(CO.sub.2 cycle) for adjusting the pressure of refrigerant on the
outlet side of gas cooler (condenser). In particular, the present
invention relates to a pressure control valve which is suitable for
use in a steam-compression type refrigerating cycle to be employed
in a car air conditioner provided with an internal heat exchanger
for performing heat exchange between the refrigerant on the outlet
side of an evaporator and the refrigerant on the outlet side of the
gas cooler.
BACKGROUND INFORMATION
[0002] FIG. 7 shows one example of the steam-compression type
refrigerating cycle into which a pressure control valve of this
kind can be integrated. The refrigerating cycle 100 shown herein is
constituted by: a compressor 101 for circulating CO.sub.2 employed
as a refrigerant; a gas cooler (condenser) 102 for cooling the
refrigerant that has been compressed by the compressor 101; an
evaporator 104 into which the refrigerant is designed to be
introduced from the gas cooler 102; an internal heat exchanger 103
for performing heat exchange between the refrigerant on the outlet
side of the evaporator 104 and the refrigerant on the outlet side
of the gas cooler 102; an accumulator (gas-liquid separator) 105
for dividing the refrigerant from the evaporator 104 into a gas
phase refrigerant and a liquid phase refrigerant and for
introducing the gas phase refrigerant into the intake side of the
compressor 101 through the heat exchanger 103 while accumulating
surplus refrigerant; and a pressure control valve (expansion valve)
110 for passing the refrigerant to the evaporator 104 after
adjusting the pressure of the refrigerant that has been introduced
via the internal heat exchanger 103 into the pressure control valve
110 from the gas cooler 102.
[0003] The pressure control valve 110 is provided for effectively
operating the refrigerating cycle 100. In other words, the pressure
control valve 110 is provided for adjusting the pressure (adiabatic
expansion) of the refrigerant on the outlet side of the gas cooler
102 so as to secure a maximum coefficient of performance in the
refrigerating cycle 100. As for the method of adjusting the
pressure of the refrigerant, there has been mainly employed a
temperature-depending system wherein the pressure of refrigerant is
adjusted depending on the temperature of refrigerant existing on
the outlet side of the gas cooler 102. See for example JP Patent
Laid-open Publication (Kokai) No. 2001-81157 (2001).
[0004] In the case of this pressure control valve of temperature
depending system however, when the temperature of outer atmosphere
is high, the pressure control valve may be overheated by the solar
radiation or by the heat from engine as the motor car is left
outdoors. When the pressure control valve is overheated, the
pressure of refrigerant is increased, imposing an excessive stress
on the pressure control valve in such a way to close the valve. As
a result, malfunctions such as failure to open the valve on the
occasion of operating the compressor (especially on the occasion of
starting the compressor) are caused to occur. As a result, the
discharge pressure may be abnormally increased, giving rise to
breakdown or destruction of high-pressure side apparatuses such as
an internal heat exchanger, a gas cooler, or a compressor.
[0005] Further, with respect to the construction thereof, there are
problems that temperature sensing means or a relief valve for
avoiding troubles at high temperatures is required to be installed,
thus complicating the structure of control valve or increasing the
manufacturing cost.
[0006] On the other hand, as seen from JP Patent Laid-open
Publication (Kokai) No. 2004-142701 (2004), there is known, as a
pressure control valve which does not depend on the temperature of
refrigerant, a structure where the magnitude of opening of valve is
to be adjusted depending only on the fluctuation of pressure of
refrigerant which can be detected by a pressure sensitive element.
Furthermore, as seen from JP Patent Laid-open Publication (Kokai)
No. 2002-520572 (2002) and JP Patent Laid-open Publication (Kokai)
No. 2000-146365 (2000), there is also known, as a pressure control
valve which does not depend on the temperature of refrigerant, a
structure which is provided with a stationary orifice and relief
valve. The stationary orifice of this structure is employed to
restrict the flow rate of refrigerant to a constant level, and when
the pressure of refrigerant on the high pressure side is increased
over a certain level, the relief valve is forced to open by a
difference of pressure between the refrigerant of high pressure
side and the refrigerant of low pressure side, thereby making it
possible to decrease the pressure of high pressure side, and when
the pressure of refrigerant on the high pressure side is decreased
down to a certain level, the relief valve is forced to close.
[0007] However, even in the case of the aforementioned
pressure-depending type pressure control valve, there is increasing
demands to further reduce the manufacturing cost in recent years.
Therefore, it is now strongly demanded to develop a pressure
control valve, which is simple in structure, low in manufacturing
cost and enhanced in operation efficiency.
SUMMARY OF THE INVENTION
[0008] The present invention has been made in response to the
problems and demands mentioned above and, therefore, an object of
the present invention to provide a pressure control valve which is
capable of appropriately adjusting the pressure of the refrigerant
on the outlet side of the gas cooler, capable of reliably
preventing the malfunctions of valve such as failure to open the
valve due to an increase in pressure of refrigerant at high
temperatures, and capable of achieving the simplification of
structure, the reduction of manufacturing cost and the enhancement
of operation efficiency.
[0009] With a view to achieve the aforementioned object, there is
provided, according to one aspect of the present invention, a
pressure control valve which is adapted to be integrated into a
steam-compression type refrigerating cycle which is constituted by:
a compressor for circulating CO.sub.2 employed as a refrigerant, a
gas cooler for cooling the refrigerant of high pressure that has
been compressed by the compressor, an evaporator into which the
refrigerant is introduced from the gas cooler after being adjusted
of its pressure, and an internal heat exchanger for performing heat
exchange between the refrigerant of low pressure on the outlet side
of the evaporator and the refrigerant of high pressure on the
outlet side of the gas cooler; the pressure control valve being
constructed to pass the refrigerant to the evaporator after
adjusting the pressure of the refrigerant that has been introduced
therein via the internal heat exchanger from the gas cooler. This
pressure control valve is fundamentally constructed to include a
valve main body having a high-pressure refrigerant inlet port and a
low-pressure refrigerant outlet port, a valve seat-attached valved
passageway formed in the valve main body for decompressing and
guiding the refrigerant from the high-pressure refrigerant inlet
port to the low-pressure refrigerant outlet port and configured to
enable a differential pressure regulating valve to be fitted
therein, and a throttling passageway provided with an orifice
having a predetermined effective cross-sectional area for enabling
the high-pressure refrigerant inlet port to communicate, through
short-cutting or detouring the valve seat, with a region of the
valved passageway which is located downstream side of the valve
seat, thereby enabling a magnitude of lift of the differential
pressure regulating valve from the valve seat to be altered
depending on a magnitude of difference in pressure between a
high-pressure side and a low-pressure side.
[0010] Preferably, the valve seat-attached valved passageway is
constituted by a cylinder portion formed contiguous with the
high-pressure refrigerant inlet port and provided, at a downstream
end portion thereof, with the valve seat, an enlarged spring
chamber formed contiguous with the downstream side of the cylinder
portion and having a larger diameter than a diameter of the
cylinder portion, a downstream passageway formed contiguous with
the low-pressure refrigerant outlet port, and a communicating
passageway for enabling the spring chamber to communicate with the
downstream passageway.
[0011] In a preferable embodiment, the differential pressure
regulating valve is constructed to include a valve portion mounted
retractively on the valve seat, a piston inserted slidably in the
cylinder portion and having a diametrally enlarged portion on the
distal end side thereof and a diametrally contracted portion on the
valve portion side, and a spring shoe for receiving a valve-closing
spring placed in the spring chamber, wherein the piston is provided
therein with a longitudinal hole and a lateral hole for enabling a
valve chamber formed between an inner circumferential wall of the
cylinder portion and an outer circumferential wall of the
diametrally contracted portion of the piston to be in communication
with the high-pressure refrigerant inlet port.
[0012] In another preferable embodiment, a vibration-proof O-ring
is interposed between a distal end portion of the diametrally
enlarged portion of the piston of the differential pressure
regulating valve and the cylinder portion.
[0013] Preferably, the valve portion of the differential pressure
regulating valve is configured to have a circular conical
surface.
[0014] In a further preferable embodiment, an adjusting screw is
screw-engaged with the spring chamber so as to make it possible to
adjust the set-load of the valve-closing valve.
[0015] Preferably, the throttling passageway is constituted by a
throttling hole-attached passageway formed contiguous with the
low-pressure refrigerant outlet port, and a by-pass passageway
formed so as to detour the valve seat portion and enabling the
high-pressure refrigerant inlet port to be in communication with a
region of the throttling hole-attached passageway which is located
upstream in relative with the throttling hole.
[0016] Preferably, the orifice of the throttling passageway is
constituted by a throttling hole having a predetermined bore size;
and a needle valve is designed to be inserted into the throttling
hole.
[0017] In a further preferable embodiment, the position of the
needle valve is made displaceable relative to the throttling hole
as so to make it possible to adjust the effective cross-sectional
area of the passageway of the orifice.
[0018] In a further preferable embodiment, the valve seat-attached
valved passageway is constituted by a cylinder portion formed
contiguous with the high-pressure refrigerant inlet port and
provided, at a downstream end portion thereof, with the valve seat;
and an enlarged spring chamber formed contiguous with the
downstream side of the cylinder portion and also with the
low-pressure refrigerant outlet port and having a larger diameter
than a diameter of the cylinder portion. On the other hand, the
differential pressure regulating valve is constructed to include a
valve portion mounted retractively on the valve seat, a piston
inserted slidably in the cylinder portion and having a diametrally
enlarged portion on the distal end side thereof and a diametrally
contracted portion on the valve portion side, and a spring shoe for
receiving a valve-closing spring placed in the spring chamber,
wherein the piston is provided therein not only with a longitudinal
hole and a lateral hole for enabling a valve chamber formed between
an inner circumferential wall of the cylinder portion and an outer
circumferential wall of the diametrally contracted portion of the
piston to be in communication with the high-pressure refrigerant
inlet port, but also with the orifice which is formed so as to
enable the longitudinal hole with the spring chamber.
[0019] In this case, preferably, an adjusting screw is
screw-engaged with the spring chamber so as to make it possible to
adjust the set-load of the valve-closing valve, and the adjusting
screw is provided with a longitudinal hole and a lateral hole for
enabling the spring chamber to be communicated with the
low-pressure refrigerant outlet port.
[0020] On the other hand, as a further embodiment, the pressure
control valve is constructed to include a valve main body having a
high-pressure refrigerant inlet port and a low-pressure refrigerant
outlet port, a valve seat-attached valved passageway formed in the
valve main body for decompressing and guiding the refrigerant from
the high-pressure refrigerant inlet port to the low-pressure
refrigerant outlet port and configured to enable a constant
pressure regulating valve to be fitted therein, and a throttling
passageway provided with an orifice having a predetermined
effective cross-sectional area for enabling the high-pressure
refrigerant inlet port to communicate, through short-cutting or
detouring the valve seat, with a region of the valved passageway
which is located downstream side of the valve seat, thereby
enabling a magnitude of lift of the constant pressure regulating
valve from the valve seat to be altered depending on a magnitude of
pressure on the high-pressure side.
[0021] Preferably, the valve seat-attached valved passageway is
constituted by a cylinder portion formed contiguous with the
high-pressure refrigerant inlet port and provided, at a downstream
end portion thereof, with the valve seat, and an enlarged spring
chamber formed contiguous with the downstream side of the cylinder
portion and communicating with the low-pressure refrigerant outlet
port, the spring chamber having a larger diameter than that of the
cylinder portion.
[0022] In a preferable embodiment, the constant pressure regulating
valve is constructed to include a valve portion mounted
retractively on the valve seat, a piston inserted slidably in the
cylinder portion and having a diametrally enlarged portion on the
distal end side thereof and a diametrally contracted portion on the
valve portion side, a spring shoe for receiving a valve-closing
spring placed in the spring chamber, and a stem portion formed
contiguous with the valve portion, wherein the piston is provided
therein with a longitudinal hole and a lateral hole for enabling a
valve chamber formed between an inner circumferential wall of the
cylinder portion and an outer circumferential wall of the
diametrally contracted portion of the piston to be in communication
with the high-pressure refrigerant inlet port. The constant
pressure regulating valve is also constructed such that atmospheric
pressure is to be received by an end face of the stem portion which
faces opposite to the piston.
[0023] Preferably, the valve portion of the constant pressure
regulating valve is configured to have a circular conical
surface.
[0024] In a further preferable embodiment, an adjusting screw is
screw-engaged with the spring chamber so as to make it possible to
adjust the set-load of the valve-closing valve and is provided with
a through-hole into which the stem portion is slidably
inserted.
[0025] Preferably, the throttling passageway is constituted by a
throttling hole-attached passageway formed contiguous with the
low-pressure refrigerant outlet port, and a by-pass passageway
formed in a manner to detour the valve seat portion and to enable
the throttling hole-attached passageway to be in communication with
the spring chamber.
[0026] Preferably, the orifice of the throttling passageway is
constituted by a throttling hole having a predetermined pore size,
and a needle valve which is designed to be inserted into the
throttling hole.
[0027] Preferably, in this case, the position of the needle valve
is made displaceable relative to the throttling hole as so to make
it possible to adjust the effective cross-sectional area of the
passageway of the orifice.
[0028] In a further preferable embodiment, the valve seat-attached
valved passageway is constituted by a cylinder portion formed
contiguous with the high-pressure refrigerant inlet port and
provided, at a downstream end portion thereof, with the valve seat;
and an enlarged spring chamber formed contiguous with the
downstream side of the cylinder portion and also with the
low-pressure refrigerant outlet port and having a larger diameter
than a diameter of the cylinder portion. On the other hand, the
constant pressure regulating valve is constructed to include a
valve portion mounted retractively on the valve seat, a piston
inserted slidably in the cylinder portion and having a diametrally
enlarged portion on the distal end side thereof and a diametrally
contracted portion on the valve portion side, a spring shoe for
receiving a valve-closing spring placed in the spring chamber, and
a stem portion formed contiguous with the valve portion, wherein
the piston is provided therein not only with a longitudinal hole
and a lateral hole for enabling a valve chamber formed between an
inner circumferential wall of the cylinder portion and an outer
circumferential wall of the diametrally contracted portion of the
piston to be in communication with the high-pressure refrigerant
inlet port, but also with the orifice which is formed so as to
enable the longitudinal hole with the spring chamber.
[0029] In a further preferable embodiment, the valve seat is
provided with a V-shaped trench functioning as the orifice.
[0030] The pressure control valve according to the present
invention is featured in that in a situation where a cycling
quantity of the refrigerant is small in a refrigerating cycle,
high-pressure refrigerant is decompressed down, by making use of
the orifice mounted in the throttling passageway, to a pressure (by
adiabatic expansion) which is advantageous in obtaining excellent
operation efficiency. In a situation where a cycling quantity of
the refrigerant is large in a refrigerating cycle, the differential
pressure regulating valve (or constant pressure regulating valve)
is lifted (to change the opening degree of valve) by taking
advantage of a difference in pressure between the high pressure
side and the low pressure side (or taking advantage of the pressure
of the high-pressure side), since it is impossible, with the
employment of only the orifice, to decompress the high-pressure
refrigerant to such an extent that is advantageous in obtaining
excellent operation efficiency, thereby making it possible to
decompress the high-pressure refrigerant down to a pressure (by
adiabatic expansion) which is advantageous in obtaining excellent
operation efficiency.
[0031] Since the pressure control valve of the present invention is
constructed as described above, it is possible to appropriately
adjust the pressure of refrigerant on the outlet side of gas cooler
and at the same time, it is possible to more simplify the structure
of the valve, to further reduce the manufacturing cost thereof, and
to further enhance the operation efficiency as compared with the
conventional pressure control valve of temperature-depending type
which requires a temperature-sensing element, etc. Additionally, it
is now possible to prevent the generation of malfunctions such as
failures to open the valve that may be caused due to an increase in
pressure of the refrigerant under high temperatures.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0032] FIG. 1 is a longitudinal sectional view illustrating a first
embodiment of the pressure control valve according to the present
invention;
[0033] FIG. 2 is an enlarged cross-sectional view of the
differential pressure regulating valve shown in FIG. 1;
[0034] FIG. 3 is an enlarged plan view of the needle valve shown in
FIG. 1;
[0035] FIG. 4 is a longitudinal sectional view illustrating a
second embodiment of the pressure control valve according to the
present invention;
[0036] FIG. 5 is a longitudinal sectional view illustrating a third
embodiment of the pressure control valve according to the present
invention;
[0037] FIG. 6 is a longitudinal sectional view illustrating a
fourth embodiment of the pressure control valve according to the
present invention; and
[0038] FIG. 7 is a flow chart illustrating one example of a
steam-compression type refrigerating cycle where the pressure
control valve of the prior art is incorporated.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0039] Next, various embodiments of the pressure control valve
according to the present invention will be explained in detail with
reference to the drawings.
[0040] FIG. 1 shows a longitudinal sectional view illustrating a
first embodiment of the pressure control valve according to the
present invention. The pressure control valve 1A according to the
first embodiment shown herein is adapted to be integrated into a
steam-compression type refrigerating cycle (CO.sub.2 cycle) 100
which is constructed fundamentally in the same manner as shown FIG.
7 mentioned above, wherein a high-pressure refrigerant that has
been introduced into the pressure control valve 1A from a gas
cooler 102 through an internal heat exchanger 103 is decompressed
down to a pressure (by adiabatic expansion) which is advantageous
in obtaining excellent operation efficiency before it is introduced
into an evaporator 104.
[0041] The pressure control valve 1A includes a valve main body 10A
having a high-pressure refrigerant inlet port 11 and a low-pressure
refrigerant outlet port 12; a valve seat (valve port) 21-attached
valved passageway 20 formed in the valve main body 10A for
decompressing and guiding the refrigerant from the high-pressure
refrigerant inlet port 11 to the low-pressure refrigerant outlet
port 12 and configured to enable a differential pressure regulating
valve 15 to be fitted therein; and a throttling passageway 30
provided with an orifice 32 having a predetermined effective
cross-sectional area for enabling the high-pressure refrigerant
inlet port 11 to communicate, through short-cutting or detouring
the valve seat 21, with a region of the valved passageway 20 which
is located downstream side of the valve seat 21. As a result, a
magnitude of lift of the differential pressure regulating valve 15
from the valve seat 21 is enabled to be altered depending on a
magnitude of difference in pressure between a high-pressure side
(the high-pressure refrigerant inlet port 11 side) and a
low-pressure side (the low-pressure refrigerant outlet port 12
side).
[0042] More specifically, the valve seat-attached valved passageway
20 is constituted by a cylinder portion 22 formed contiguous with
the high-pressure refrigerant inlet port 11 and provided, at a
downstream end portion thereof, with the valve seat (valve port)
21, an enlarged spring chamber 23 formed contiguous with the
downstream side of the cylinder portion 22 and having a larger
diameter than a diameter of the cylinder portion 22, a downstream
passageway 25 formed contiguous with the low-pressure refrigerant
outlet port 12, and a communicating passageway 24 for enabling the
spring chamber 23 to communicate with the downstream passageway
25.
[0043] The high-pressure refrigerant inlet port 11, the cylinder
portion 22 and the spring chamber 23 are all formed coaxially on a
common axial line O.sub.a, while the low-pressure refrigerant
outlet port 12 and the downstream passageway 25 are all formed
coaxially on a common axial line O.sub.b. The communicating
passageway 24 is constituted by a lateral hole extending
horizontally from one side portion of the valve main body 10A, thus
orthogonally intersecting the axial lines O.sub.a and O.sub.b. The
outer end portion of this lateral hole is screw-engaged with a
sealing plug 46.
[0044] As clearly seen from FIG. 2 (enlarged view) in addition with
FIG. 1, the differential pressure regulating valve 15 is
constructed to include a valve portion 16 mounted retractively on
the valve seat 21, a piston 17 inserted slidably in the cylinder
portion 22 and having a diametrally enlarged portion 17a on the
distal end side thereof and a diametrally contracted portion 17b on
the valve portion side, and a spring shoe 18 having a collar-like
configuration for receiving a valve-closing spring 40 made of a
compression coil spring and placed in the spring chamber 23. The
piston 17 is provided therein with a longitudinal hole 19a and a
plurality of lateral holes 19b for enabling a valve chamber 13
formed between an inner circumferential wall of the cylinder
portion 22 and an outer circumferential wall of the diametrally
contracted portion 17b of the piston 17 to be communicated with the
high-pressure refrigerant inlet port 11.
[0045] Between a distal end portion of the diametrally enlarged
portion of the piston 17 in the differential pressure regulating
valve 15 and the cylinder portion 22, there is interposed a
vibration-proof O-ring 26. Due the provision of this O-ring 26, it
is possible to suppress the generation of abnormal noise that may
be caused to happen due to the vibration of the differential
pressure regulating valve 15 on the occasion when the refrigerant
passes through the differential pressure regulating valve 15.
[0046] Further, since the differential pressure regulating valve 15
is provided therein with the longitudinal hole 19a and a plurality
of lateral holes 19b and these holes are enabled to be utilized as
part of the valved passageway 20, it is now possible to secure a
sufficient cross-sectional flowing area (effective cross-sectional
flowing area), irrespective of the existence or absence of the
O-ring 26.
[0047] Further, the valve portion 16 of the differential pressure
regulating valve 15 is configured to have a circular conical
surface having a conic angle .theta..sub.a (for example,
35-90.degree.). As described above, since the valve portion 16 is
configured to have a conical surface having a conic angle
.theta..sub.a, and also a region of the valve 15 which is located
between the valve portion 16 and the diametrally contracted portion
17b is configured into a moderately inclined surface (conical
surface, etc.) without forming any stepped portion, it is possible
to moderately vary, in conformity with changes of opening degree
(magnitude of lift) of the valve that may be caused due to the
fluctuation of pressure of high-pressure refrigerant, the flowing
area (effective cross-sectional flowing area) of the valve port
(valve seat) 21 where a refrigerant is enabled to pass through. As
a result, it is now possible to more delicately control the valve
in response to the fluctuations of the high-pressure refrigerant
and at the same time, it is possible to smooth the passing of
refrigerant.
[0048] An adjusting screw 42 is screw-engaged with a lower portion
of the spring chamber 23 so as to make it possible to adjust the
set-load of the valve-closing spring 40. By making use of this
adjusting screw 42, a lower end of the valve-closing spring 40 is
sustained through a spring shoe 43. A sealing plug 44 is screwed
into a lower end portion of the spring chamber 23.
[0049] The throttling passageway 30 provided with the orifice 32 is
constituted by a throttling hole (34)-attached passageway 33 having
a predetermined bore size and formed contiguous with the
low-pressure refrigerant outlet port 12 via a downstream passageway
25 of the valved passageway 20, and a by-pass passageway 35 formed
so as to detour the cylinder portion 22 and enabling the
high-pressure refrigerant inlet port 11 to be communicated with a
region of the throttling hole (34)-attached passageway 33 which is
located upstream relative to the throttling hole 34.
[0050] The orifice 32 of the throttling passageway 30 is
constituted by a throttling hole 34, and a needle valve 36 which is
designed to be inserted into the throttling hole 34. In this
embodiment, the position of the needle valve 36 is made
displaceable in relative to the throttling hole 34 as so to make it
possible to adjust the effective cross-sectional area of the
passageway of the orifice 32. More specifically, the needle valve
36 is provided, at one end thereof, with a threaded portion 36a
which is adapted to be screw-engaged with one end portion of the
throttling hole (34)-attached passageway 33. By the adjustment of
the magnitude of engagement of this threaded portion 36a with the
throttling hole (34)-attached passageway 33, it is made possible to
adjust the effective cross-sectional area of the passageway of the
orifice 32. A locknut 37 is mounted, through screw-engagement, on
one end of the threaded portion 36a, and a sealing plug 49 is
attached, through screw-engagement, to one end of the passageway
33. Further, as shown in FIG. 3, if a V-shaped groove 36b is
engraved beforehand, as a scale, on the top surface of the needle
valve 36 at intervals of 90.degree. for example, or if a punch hole
36c is engraved beforehand at a reference point, the aforementioned
adjustment of the magnitude of engagement (the adjustment of the
effective cross-sectional area of the passageway of the orifice 32)
can be easily performed.
[0051] According to the pressure control valve 1A of this
embodiment constructed as described above, when a cycling quantity
of the refrigerant is small in the CO.sub.2 cycle, the differential
pressure regulating valve 15 takes a completely closed state
(magnitude of lift is zero) as the valve portion 16 is contacted
with the valve seat 21 due to the urging force by the valve-closing
spring 40, since the difference in pressure between the
high-pressure side (the high-pressure refrigerant inlet port 11
side) and the low pressure side (the low-pressure refrigerant
outlet port 12 side) is small. In this case, the high-pressure
refrigerant is introduced from the high-pressure refrigerant inlet
port 11 side into the throttling hole (34)-attached passageway 33
through the by-pass passageway 35. Then, due to the effect of the
orifice 32 provided at this passageway 33, the high-pressure
refrigerant is decompressed (by adiabatic expansion) to a pressure
which is advantageous in obtaining excellent operation efficiency,
after which the refrigerant is introduced into the evaporator via
the downstream passageway 25 and the low-pressure refrigerant
outlet port 12.
[0052] Whereas, when a cycling quantity of the refrigerant is large
(i.e. when it is impossible, with the employment of only the
orifice, to decompress the high-pressure refrigerant to such an
extent that is advantageous in obtaining excellent operation
efficiency), the difference in pressure between the high-pressure
side (the high-pressure refrigerant inlet port 11 side) and the low
pressure side (the low-pressure refrigerant outlet port 12 side)
becomes large, the differential pressure regulating valve 15 is
forced to lift resisting against the urging force of the
valve-closing spring 40, thereby moving the valve portion 16 away
from the valve seat 21, thus opening the valve. In the case, the
magnitude of lift (opening degree of valve) of the differential
pressure regulating valve 15 from the valve seat 21 varies
depending on the difference in pressure between the high-pressure
side (the high-pressure refrigerant inlet port 11 side) and the low
pressure side (the low-pressure refrigerant outlet port 12 side),
so that the high-pressure refrigerant is decompressed (by adiabatic
expansion) down to such an extent that is advantageous in obtaining
excellent operation efficiency. The refrigerant thus decompressed
is permitted to move from the low-pressure refrigerant outlet port
12 into the evaporator 104 after passing through the spring chamber
23, the communicating passageway 24 and the downstream passageway
25.
[0053] As described above, according to the pressure control valve
1A of this embodiment, when a cycling quantity of the refrigerant
is small, the high-pressure refrigerant is decompressed down, by
making use of the orifice mounted in the throttling passageway, to
a pressure (by adiabatic expansion) which is advantageous in
obtaining excellent operation efficiency. When a cycling quantity
of the refrigerant is large, since it is not feasible, with the
employment of only the orifice, to decompress the high-pressure
refrigerant to such an extent that is advantageous in obtaining
excellent operation efficiency, the differential pressure
regulating valve 15 is lifted (to change the opening degree of
valve) by taking advantage of a difference in pressure between the
high pressure side and the low pressure side, thereby making it
possible to decompress the high-pressure refrigerant down to a
pressure (adiabatic expansion) which is advantageous in obtaining
excellent operation efficiency.
[0054] As a result, it is now possible to appropriately adjust the
pressure of refrigerant on the outlet side of gas cooler 102 and at
the same time, it is possible to more simplify the structure of the
valve, to further reduce the manufacturing cost thereof, and to
further enhance the operation efficiency as compared with the
conventional pressure control valve of temperature-depending type
which necessitates a temperature-sensing element and other
components. Additionally, it is now possible to prevent the
generation of malfunctions such as failures to open the valve that
may be caused due to an increase in pressure of the refrigerant
under high temperatures.
[0055] FIG. 4 is a longitudinal sectional view illustrating a
second embodiment of the pressure control valve according to the
present invention. The pressure control valve 1B is constructed in
almost the same manner as that of the first embodiment. This
pressure control valve 1B is however aimed at improvements with
regard to the simplification of structure, compactness and the
reduction in number of components as compared with the pressure
control valve of the aforementioned first embodiment. In the
following description, the same functions and components as those
of the aforementioned first embodiment will be identified by same
numbers or symbols, thereby omitting the duplicated explanation
thereof and only the features which differ from the aforementioned
first embodiment will be mainly explained.
[0056] The valve main body 10B shown herein includes a valve main
body 10B which is slimmer in configuration than that of the first
embodiment and provided, at upper and lower end portions thereof,
with a high-pressure refrigerant inlet port 11 and a low-pressure
refrigerant outlet port 12, respectively. Further, the valve main
body 10B is provided with a valve seat (21)-attached valved
passageway 20'.
[0057] This valve seat (21)-attached valved passageway 20' is
constituted by a cylinder portion 22 formed contiguous with the
high-pressure refrigerant inlet port 11 and provided, at a
downstream end portion thereof, with the valve seat 21, and an
enlarged spring chamber 23 formed contiguous with the downstream
side of the cylinder portion 22, communicating with the
low-pressure refrigerant outlet port 12 and having a larger
diameter than a diameter of the cylinder portion 22. Further, the
differential pressure regulating valve 15' is constructed to
include a valve portion 16 mounted retractively on the valve seat
21, a piston 17 inserted slidably in the cylinder portion 22 and
having a diametrally enlarged portion 17a on the distal end side
thereof and a diametrally contracted portion 17b on the valve
portion side, and a spring shoe 18 for receiving a valve-closing
spring 40 placed in the spring chamber 23, wherein the piston 17 is
provided therein with a longitudinal hole 19a' and a plurality of
lateral holes 19b for enabling a valve chamber 13 formed between an
inner circumferential wall of the cylinder portion 22 and an outer
circumferential wall of the diametrally contracted portion 17b of
the piston 17 to be communicated with the high-pressure refrigerant
inlet port 11. The longitudinal hole 19a' is extended more deeply
downward (down to the vicinity of the lower end of differential
pressure regulating valve 15') than that (19a) of the first
embodiment, and an orifice 32' is formed at a lower end portion of
the differential pressure regulating valve 15', thereby enabling
the longitudinal hole 19a' to communicate with the spring chamber
23.
[0058] In contrast to the orifice 32 of the first embodiment, the
orifice 32' in this embodiment is incapable of changing the
effective cross-sectional area of the valve, thereby providing a
stationary orifice having a predetermined bore size.
[0059] An adjusting screw 42 is screw-engaged with a lower portion
of the spring chamber 23 so as to make it possible to adjust the
set-load of the valve-closing spring 40. By making use of this
adjusting screw 42, a lower end of the valve-closing spring 40 is
sustained through a spring shoe 43. Furthermore, the adjusting
screw 42 is provided therein with a longitudinal hole 42a and a
plurality of lateral holes 42b for enabling the spring chamber 23
to be communicated with the low-pressure refrigerant outlet port
12.
[0060] In this embodiment, the high-pressure refrigerant inlet port
11, the cylinder portion 22, the spring chamber 23 and the
low-pressure refrigerant outlet port 12 are all formed coaxially on
a common axial line O.sub.a. The communicating passageway 24, the
downstream passageway 25 and the by-pass passageway 35, all
necessitated in the pressure control valve of the first embodiment,
are no longer employed in this embodiment. The function of the
throttling passageway 30 (the throttling hole (34)-attached
passageway 33) of the first embodiment is taken up by an orifice
(32')-attached longitudinal hole 19a' which is formed inside the
differential pressure regulating valve 15'.
[0061] According to the pressure control valve of this second
embodiment which is constructed as explained above, it is possible
to achieve not only almost the same effects as those of the first
embodiment, but also further simplification in structure of the
valve, further enhanced compactness and further reduction in number
of components as compared with the pressure control valve of the
first embodiment.
[0062] FIG. 5 shows a longitudinal sectional view illustrating a
third embodiment of the pressure control valve according to the
present invention. In the same manner as described in the
aforementioned first and second embodiments, the pressure control
valve 1C according to the third embodiment is adapted to be
integrated into a steam-compression type refrigerating cycle
(CO.sub.2 cycle) 100 which is constructed fundamentally in the same
manner as shown FIG. 7 mentioned above, wherein a high-pressure
refrigerant that has been introduced into the pressure control
valve 1C from a gas cooler 102 through an internal heat exchanger
103 is decompressed down to a pressure (by adiabatic expansion)
which is advantageous in obtaining excellent operation efficiency
before it is introduced into an evaporator 104.
[0063] The pressure control valve 1C includes a valve main body 10C
provided, at a lower portion and one side thereof, with a
high-pressure refrigerant inlet port 11 and a low-pressure
refrigerant outlet port 12, respectively; a valve seat (valve port)
61-attached valved passageway 60 formed in the valve main body 10C
for decompressing and guiding the refrigerant from the
high-pressure refrigerant inlet port 11 to the low-pressure
refrigerant outlet port 12 and configured to enable a constant
pressure regulating valve 55 to be fitted therein; and a throttling
passageway 70 provided with an orifice 72 having a predetermined
effective cross-sectional area for enabling the high-pressure
refrigerant inlet port 11 to communicate, through short-cutting or
detouring the valve seat 61, with a region of the valved passageway
60 which is located downstream side of the valve seat 61. As a
result, a magnitude of lift of the constant pressure regulating
valve 55 from the valve seat 61 is enabled to be altered depending
on a magnitude of pressure of the high-pressure side (the
high-pressure refrigerant inlet port 11 side).
[0064] More specifically, the valve seat-attached valved passageway
60 is constituted by a cylinder portion 62 formed contiguous with
the high-pressure refrigerant inlet port 11 and provided, at a
downstream end portion thereof, with the valve seat (valve port)
61, and an enlarged spring chamber 63 formed contiguous with the
downstream side of the cylinder portion 62 and having a larger
diameter than a diameter of the cylinder portion 62. The
high-pressure refrigerant inlet port 11, the cylinder portion 62
and the spring chamber 63 are all formed coaxially on a common
axial line O.sub.a, while the low-pressure refrigerant outlet port
12 is formed orthogonal to the line O.sub.a.
[0065] The constant pressure regulating valve 55 is constructed to
include a valve portion 56 mounted retractively on the valve seat
61, a piston 57 inserted slidably in the cylinder portion 62 and
having a diametrally enlarged portion 57a on the distal end side
thereof and a diametrally contracted portion 57b on the valve
portion side, a conical receiving seat 58 which is adapted to be
engaged with a collar-like spring shoe 83 for receiving a lower end
portion of the valve-closing spring 80 made of a compression coil
spring and placed in the spring chamber 63, and a stem portion 54
formed contiguous with the valve portion 56. The piston 57 is
provided therein with a longitudinal hole 59a and a plurality of
lateral holes 59b for enabling a valve chamber 53 (which is formed
between an inner circumferential wall of the cylinder portion 62
and an outer circumferential wall of the diametrally contracted
portion 57b of the valve) to be communicated with the high-pressure
refrigerant inlet port 11.
[0066] As described above, since the constant pressure regulating
valve 55 is provided therein with the longitudinal hole 59a and a
plurality of lateral holes 59b and these holes are enabled to be
utilized as part of the valved passageway 60, it is now possible to
secure a sufficient cross-sectional flowing area (effective
cross-sectional flowing area).
[0067] Further, the valve portion 56 of the constant pressure
regulating valve 55 is configured to have a circular conical
surface having a conic angle .theta..sub.a (for example,
35-90.degree.) as in the cases of the above-mentioned first and
second embodiments. As described above, since the valve portion 56
is configured to have a conical surface having a conic angle
.theta..sub.a, and also a region of the valve 55 which is located
between the valve portion 56 and the diametrally contracted portion
57b is configured into a moderately inclined surface (conical
surface, etc.) without forming any stepped portion, it is possible
to moderately vary, in conformity with changes of opening degree
(magnitude of lift) of the valve that may be caused due to the
fluctuation of pressure of high-pressure refrigerant, the flowing
area (effective cross-sectional flowing area) of the valve port
(valve seat) 61 where a refrigerant is enabled to pass through. As
a result, it is now possible to more delicately control the valve
in response to the fluctuations of the high-pressure refrigerant
and at the same time, it is possible to smooth the passing of
refrigerant.
[0068] An adjusting screw 82 is screw-engaged with an upper portion
of the spring chamber 63 so as to make it possible to adjust the
set-load of the valve-closing spring 80. By making use of this
adjusting screw 82, an upper end of the valve-closing spring 80 is
sustained through a spring shoe 83. This adjusting screw 82 is
provided with a through-hole 92, in which an upper portion of the
stem portion 54 is slidably inserted, thereby enabling the
atmospheric pressure to be received by the top face (top surface
which faces opposite to the piston) of the stem portion 54. More
specifically, an annular stopper plate 94 for preventing the
disengagement of adjusting screw 82 is secured, at three points
thereof, to the top surface of the valve main body 10C by making
use of screw 95. A cap 90 is screw-engaged with an upper outer
circumferential portion of the valve main body 10C so as to enclose
the stopper plate 94. This stopper plate 94 provided, on its top
surface, with a plurality of grooves 96 extending radially. A
cavity portion 97 formed over the end face 54a of the stem portion
54 in the through-hole 92 is communicated, via the screw-engaged
portion (thread portion) 98 between an upper outer circumferential
portion of valve main body 10C and the cap 90 and via the grooves
96, with air atmosphere. Therefore, the atmospheric pressure is
enabled to act on this upper end face 54a of the stem portion
54.
[0069] A couple of O-rings 87 (two-stage) are interposed between
the outer circumferential surface of the stem portion 54 and the
through-hole 92, and one O-ring 89 is interposed between a lower
portion of the adjusting screw 82 and the inner circumferential
surface of the valve chamber 63.
[0070] On the other hand, the throttling passageway 70 having the
orifice 72 therein is constituted by a throttling hole
(74)-attached passageway 73 having a predetermined bore size and
communicated, via the cylinder portion 62 of the valved passageway
60, with the high-pressure refrigerant inlet port 11; and by a
by-pass passageway 75 for enabling, while detouring the valve seat
61, the throttling hole (74)-attached passageway 73 to be
communicated with the spring chamber 63.
[0071] The orifice 72 of the throttling passageway 70 is
constituted by a throttling hole 74, and a needle valve 76 which is
designed to be inserted into the throttling hole 74. In this
embodiment, the position of the needle valve 76 is made
displaceable in relative to the throttling hole 74 as so to make it
possible to adjust the effective cross-sectional area of the
passageway of the orifice 72. More specifically, the needle valve
76 is provided, at one end thereof, with a threaded portion 76a
which is adapted to be screw-engaged with one end portion of the
throttling hole (74)-attached passageway 73. By the adjustment of
the magnitude of engagement of this threaded portion 76a with the
throttling hole (74)-attached passageway 73, it is possible to
adjust the effective cross-sectional area of the passageway of the
orifice 72. A locknut 77 is mounted, through screw-engagement, on
one end of the threaded portion 76a, and a cap 79 is attached,
through screw-engagement, to one end of the passageway 73.
[0072] According to the pressure control valve 1C of this
embodiment constructed as described above, in a situation where a
cycling quantity of the refrigerant is small in the CO.sub.2 cycle,
since the pressure of the high-pressure side (high-pressure
refrigerant inlet port 11) is small, the constant pressure
regulating valve 55 is enabled to take a completely closed state
(magnitude of lift is zero) as the valve portion 56 contacts the
valve seat 61 due to the urging force by the valve-closing spring
80. On this occasion, the high-pressure refrigerant from the
high-pressure refrigerant inlet port 11 is decompressed (by
adiabatic expansion) to a pressure which is advantageous in
obtaining excellent operation efficiency due to the effect of the
orifice 72 provided in the throttling hole (74)-attached passageway
73 before the refrigerant is delivered from the low-pressure
refrigerant outlet port 12 to the evaporator.
[0073] When a cycling quantity of the refrigerant is large (i.e.
when it is impossible, with the employment of only the orifice 72,
to decompress the high-pressure refrigerant to such an extent that
is advantageous in obtaining excellent operation efficiency), the
pressure of the high-pressure side (the high-pressure refrigerant
inlet port 11 side) becomes high, so that the constant pressure
regulating valve 55 is forced to lift resisting against the urging
force of the valve-closing spring 80, thereby moving the valve
portion 56 thereof away from the valve seat 61, thus opening the
valve. In the case, since the magnitude of lift (opening degree of
valve) of the constant pressure regulating valve 55 from the valve
seat 61 varies proportionally depending on the pressure of the
high-pressure side (the high-pressure refrigerant inlet port 11
side), the high-pressure refrigerant is decompressed (by adiabatic
expansion)) down to such an extent that is advantageous in
obtaining excellent operation efficiency. The refrigerant thus
decompressed is then permitted to be delivered from the
low-pressure refrigerant outlet port 12, via the spring chamber 63,
to the evaporator 104.
[0074] As described above, according to the pressure control valve
1C of this embodiment, when a cycling quantity of the refrigerant
is small, the high-pressure refrigerant is decompressed down, by
making use of the orifice 72 mounted in the throttling passageway
70, to a pressure (by adiabatic expansion) which is advantageous in
obtaining excellent operation efficiency. On the other hand, when a
cycling quantity of the refrigerant is large, since it is
impossible, with the employment of only the orifice 72, to
decompress the high-pressure refrigerant to such an extent that is
advantageous in obtaining excellent operation efficiency, the
constant pressure regulating valve 55 is lifted (to change the
opening degree of valve) by taking advantage of the pressure of the
high-pressure side, thereby making it possible to decompress the
high-pressure refrigerant down to a pressure (by adiabatic
expansion) which is advantageous in obtaining excellent operation
efficiency. As a result, it is now possible to appropriately adjust
the pressure of refrigerant on the outlet side of gas cooler 102
and at the same time, it is possible to more simplify the structure
of the valve, to further reduce the manufacturing cost thereof, and
to further enhance the operation efficiency as compared with the
conventional pressure control valve of temperature-depending type
which necessitates a temperature-sensing element, and other
components. Additionally, it is now possible to prevent the
generation of malfunctions such as failures to open the valve that
may be caused due to an increase in pressure of the refrigerant
under high temperatures.
[0075] FIG. 6 is a longitudinal sectional view illustrating a
fourth embodiment of the pressure control valve according to the
present invention. The pressure control valve 1D of this fourth
embodiment is constructed to have almost the same function as that
of the third embodiment. This pressure control valve 1D is however
aimed at improvements with regard to the simplification of
structure, compactness and the reduction in number of components as
compared with the pressure control valve 1A of the aforementioned
first embodiment. In the following description, the same functions
and components as those of the aforementioned first embodiment will
be identified by same numbers or symbols, thereby omitting the
duplicated explanation thereof and only the features which differ
from the aforementioned first embodiment will be mainly
explained.
[0076] The pressure control valve ID shown herein includes a valve
main body 10D is more slim than that of the first embodiment and
provided with a high-pressure refrigerant inlet port 11 and a
low-pressure refrigerant outlet port 12; and a constant pressure
regulating valve 55 including a piston portion 57. The piston
portion 57 is provided therein with a longitudinal hole 59a' and a
plurality of lateral holes 59b for enabling a valve chamber 53
(which is formed between an inner circumferential wall of the
cylinder portion 62 and an outer circumferential wall of the
diametrally contracted portion 57b of the valve) to be communicated
with the high-pressure refrigerant inlet port 11. This longitudinal
hole 59a' is extended upward more than that (59a) of the third
embodiment (i.e. extended passing through the valve portion 56 and
the receiving seat 58 and penetrating into the stem portion 54).
The longitudinal hole 59a' is provided, in a sidewall portion
thereof located in the vicinity of the bottom thereof, with an
orifice 72', thereby enabling this longitudinal hole 59a' to be
communicated with the spring chamber 63.
[0077] In contrast to the orifice 72 of the third embodiment, the
orifice 72' of this embodiment is incapable of changing its
effective cross-sectional area of passageway. Namely, this orifice
72' is a stationary orifice having a predetermined bore size.
[0078] In this embodiment, the function of the throttling
passageway 70 (the throttling hole (74)-attached passageway 73) of
the third embodiment is taken up by an orifice (72')-attached
longitudinal hole 59a' which is formed inside the constant pressure
regulating valve 55.
[0079] According to the pressure control valve 4B of the fourth
embodiment which is constructed as described above, it is possible
to achieve not only almost the same effects as those of the third
embodiment, but also further simplification in structure of the
valve, further enhanced compactness and further reduction in number
of components as compared with the pressure control valve of the
third embodiment.
[0080] While there have been described the exemplary embodiments of
the present invention, those skilled in the art will recognize that
other and further changes and modifications may be made thereto
without department from the spirit of the invention, and it is
intended to claim all such changes and modifications that fall
within the true scope of the invention. For example, instead of
employing the aforementioned orifices 32, 32', 72 and 72', a
V-shaped groove may be formed on the valve seat for instance,
thereby enabling the V-shaped groove to function as an orifice on
the occasion of completely closing the differential pressure
regulating valve or the constant pressure regulating valve.
* * * * *