U.S. patent application number 11/330941 was filed with the patent office on 2006-07-13 for expansion valve for refrigerating cycle.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Nobuharu Kakehashi, Yoshinori Murase, Hiromi Ohta, Yoshitaka Tomatsu.
Application Number | 20060150650 11/330941 |
Document ID | / |
Family ID | 36275098 |
Filed Date | 2006-07-13 |
United States Patent
Application |
20060150650 |
Kind Code |
A1 |
Murase; Yoshinori ; et
al. |
July 13, 2006 |
Expansion valve for refrigerating cycle
Abstract
An expansion valve for a refrigerating cycle, in which the body
dimensions and the weight of the whole valve can be reduced and a
reduction in cost can be achieved. An expansion valve of the
invention comprising a temperature-sensing portion arranged in a
refrigerant passage leading to an evaporator from a gas cooler or
an internal heat exchanger in a vapor compression type
refrigerating cycle and varied in internal pressure according to a
refrigerant temperature at an outlet side of the gas cooler or on
an outlet side of the internal heat exchanger, a valve member that
mechanically interlocks with a change in internal pressure of the
temperature-sensing portion to adjust an opening degree of a valve
port, and a body that accommodates therein the valve member, and
wherein the body is provided with a flow passage, through which a
refrigerant reduced in pressure by the valve member is led to the
evaporator while a refrigerant temperature at the outlet side of
the gas cooler or on the outlet side of the internal heat exchanger
is transmitted to the temperature-sensing portion. Also, that
density, at which a refrigerant is charged in a temperature-sensing
body, is set in the range of about 200 kg/m.sup.3 to about 600
kg/m.sup.3. Further, a ratio of a temperature-sensing cylinder
corresponding portion to the temperature-sensing body is made at
least 60%.
Inventors: |
Murase; Yoshinori;
(Nagoya-city, JP) ; Tomatsu; Yoshitaka;
(Chiryu-city, JP) ; Kakehashi; Nobuharu;
(Toyoake-city, JP) ; Ohta; Hiromi; (Okazaki-city,
JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO Corporation
Kariya-city
JP
|
Family ID: |
36275098 |
Appl. No.: |
11/330941 |
Filed: |
January 12, 2006 |
Current U.S.
Class: |
62/222 ; 62/513;
62/527 |
Current CPC
Class: |
F25B 2341/0683 20130101;
F25B 2341/063 20130101; F25B 41/31 20210101; F25B 2309/061
20130101 |
Class at
Publication: |
062/222 ;
062/527; 062/513 |
International
Class: |
F25B 41/04 20060101
F25B041/04; F25B 41/00 20060101 F25B041/00; F25B 41/06 20060101
F25B041/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 2005 |
JP |
2005-006344 |
Nov 14, 2005 |
JP |
2005-329466 |
Claims
1. An expansion valve for a refrigerating cycle, arranged in a
refrigerant passage leading from a gas cooler to an evaporator in a
vapor compression type refrigerating cycle to adjust an opening
degree of a valve port on the basis of a refrigerant temperature at
an outlet side of the gas cooler to thereby control a refrigerant
pressure at the outlet side of the gas cooler, the expansion valve
comprising a temperature-sensing portion, the inner pressure of
which is varied according to the refrigerant temperature at the
outlet side of the gas cooler, a valve member that mechanically
interlocks with a chance in internal pressure of the
temperature-sensing portion to adjust an opening degree of the
valve port, and a body that accommodates therein the valve member,
and wherein the body is provided with a flow passage, through which
a refrigerant reduced in pressure by the valve member is led to the
evaporator while the refrigerant temperature at the outlet side of
the gas cooler is transmitted to the temperature-sensing
portion.
2. The expansion valve for a refrigerating cycle according to claim
1, wherein the temperature-sensing portion comprises a diaphragm,
and a lid and a lower support member, which interpose therebetween
a peripheral edge of the diaphragm from upper and lower directions
to define an enclosed space above the diaphragm, and transmission
or a refrigerant temperature to the temperature-sensing portion is
performed by a clearance, which is formed by the valve member and
the lower support member to be communicated to the refrigerant
passage.
3. The expansion valve for a refrigerating cycle according to any
one of claim 1, wherein the enclose, space of the
temperature-sensing portion is charged with a refrigerant and
provided with an adjustment spring, which biases the valve member
in a valve closing direction.
4. The expansion valve for a refrigerating cycle according to any
one of claim 1, wherein the enclosed space of the
temperature-sensing portion is charged with a mixed gas of a
refrigerant and gases, which are lower in coefficient of thermal
expansion than the refrigerant, and an adjustment spring, which
biases the valve member in a valve closing direction, is
omitted.
5. The expansion valve for a refrigerating cycle according to any
one of claim 1, further comprising a lid that covers a wall surface
of the first enclosed space in contact with an outside air to
provide an air layer between the wall surface and the outside
air.
6. The expansion valve for a refrigerating cycle according to any
one of claim 1, wherein at least a part of the wall surface of the
first enclosed space in contact with an outside air is covered by a
thermal insulating material.
7. An expansion valve for a refrigerating cycle arranged in a
refrigerant passage leading from an internal heat exchanger to an
evaporator in a vapor compression type refrigerating cycle to
adjust an opening degree of a valve port on the basis of a
refrigerant temperature at an outlet side of the gas cooler to
thereby control a refrigerant pressure at the outlet side of the
gas cooler, the expansion valve comprising a temperature-sensing
portion, the inner pressure of which is varied according to the
refrigerant temperature at the outlet side of the gas cooler, a
valve member that mechanically interlocks with a change in internal
pressure of the temperature-sensing portion to adjust an opening
degree of the valve port, and a body that accommodates therein the
valve member, and wherein the body is provided with a first flow
passage, through which a refrigerant flows to the internal heat
exchanger, and a second flow passage, through which a refrigerant
reduced in pressure by the valve member is led to the evaporator
from the internal heat exchanger, while the refrigerant temperature
at the outlet side of the gas cooler is transmitted to the
temperature-sensing portion.
8. The expansion valve for a refrigerating cycle according to claim
7, wherein the temperature-sensing portion comprises a diaphragm,
and a lid and a lower support member, which interpose therebetween
a peripheral edge of the diaphragm from upper and lower directions
to define an enclosed space above the diaphragm, and transmission
of a refrigerant temperature to the temperature-sensing portion is
performed by a clearance, which is formed by the valve member and
the lower support member to be communicated to the refrigerant
passage.
9. The expansion valve for a refrigerating cycle according to any
one of claim 7, wherein the enclosed space of the
temperature-sensing portion is charged with a refrigerant and
provided with an adjustment spring, which biases the valve member
in a valve closing direction.
10. The expansion valve for a refrigerating cycle according to any
one of claim 7, wherein the enclosed space of the
temperature-sensing portion is charged with a mixed gas of a
refrigerant and gases, which are lower in coefficient of thermal
expansion than the refrigerant, and an adjustment spring, which
biases the valve member in a valve closing direction, is
omitted.
11. The expansion valve for a refrigerating cycle according to any
one of claim 7, further comprising a lid that covers a wall surface
of the first enclosed space in contact with an outside air to
provide an air layer between the wall surface and the outside
air.
12. The expansion valve for a refrigerating cycle according to any
one of claim 7, wherein at least a part of the wall surface of the
first enclosed space in contact with an outside air is covered by a
thermal insulating material.
13. An expansion valve for a refrigerating cycle arranged in a
refrigerant passage leading from an internal heat exchanger to an
evaporator in a vapor compression type refrigerating cycle to
adjust an opening degree of a valve port on the basis of a
refrigerant temperature at an outlet side of the internal heat
exchanger to thereby control a refrigerant pressure at the outlet
side of the internal heat exchanger, the expansion valve comprising
a temperature-sensing portion, inner pressure of which is varied
according to the refrigerant temperature at the outlet side of the
internal heat exchanger, a valve member that mechanically
interlocks with a change in internal pressure of the
temperature-sensing portion to adjust an opening degree of the
valve port, and a body that accommodates therein the valve member,
and wherein the body is provided with a flow passage, through which
a refrigerant reduced in pressure by the valve member flows to the
evaporator while the refrigerant temperature at the outlet side of
the internal heat exchanger is transmitted to the
temperature-sensing portion.
14. The expansion valve for a refrigerating cycle according to
claim 13, wherein the temperature-sensing portion comprises a
diaphragm, and a lid and a lower support member, which interpose
therebetween a peripheral edge of the diaphragm from upper and
lower directions to define an enclosed space above the diaphragm,
and transmission of a refrigerant temperature to the
temperature-sensing portion is performed by a clearance, which is
formed by the valve member and the lower support member to be
communicated to the refrigerant passage.
15. The expansion valve for a refrigerating cycle according to any
one of claim 13, wherein the enclosed space of the
temperature-sensing portion is charged with a refrigerant and
provided with an adjustment spring, which biases the valve member
in a valve closing direction.
16. The expansion valve for a refrigerating cycle according to any
one of claim 13, wherein the enclosed space of the
temperature-sensing portion is charged with a mixed gas of a
refrigerant and gases, which are lower in coefficient of thermal
expansion than the refrigerant, and an adjustment spring, which
biases the valve member in a valve closing direction, is
omitted.
17. Am expansion valve for a refrigerating cycle arranged in a
refrigerant passage leading to an evaporator from a gas cooler
through an internal heat exchanger in a vapor compression type
refrigerating cycle to adjust an opening degree of a valve port on
the basis of a refrigerant temperature at an outlet side of the gas
cooler or a refrigerant temperature at an outlet side of the
internal heat exchanger to thereby control a refrigerant pressure
at the outlet side of the internal heat exchanger, the expansion
valve comprising a temperature-sensing portion charged with a
refrigerant and varied in inner pressure according to the
refrigerant temperature at the outlet side of the gas cooler or the
refrigerant temperature at the outlet side of the internal heat
exchanger, and a valve member that mechanically interlocks with a
change in internal pressure of the temperature-sensing portion to
adjust an opening degree of the valve port, and wherein the
density, at which a refrigerant is charged in the
temperature-sensing portion, is 200 to 600 kg/m.sup.3 in a valve
closed state.
18. The expansion valve for a refrigerating cycle according to
claim 17, wherein the density, at which a refrigerant is charged in
the temperature-sensing portion, is 200 to 450 kg/m.sup.3 in a
valve closed state.
19. The expansion valve for a refrigerating cycle according to
claim 17, wherein the valve member is opened when high pressure at
the outlet side of the gas cooler or at the outlet side of the
internal heat exchanger becomes higher, by a predetermined
magnitude, than inner pressure in the temperature-sensing
portion.
20. The expansion valve for a refrigerating cycle according to
claim 19, wherein a load corresponding to the predetermined
magnitude is given by an elastic member, or a non-condensed gas
charged in the temperature-sensing portion together with a
refrigerant, or the elastic member and the non-condensed gas.
21. The expansion valve for a refrigerating cycle according to
claim 20, wherein the elastic member comprises any one of a coil
spring, a diaphragm, and a bellows, or an optional combination
thereof.
22. The expansion valve for a refrigerating cycle according to
claim 17, wherein when a refrigerant temperature at the outlet side
of the gas cooler is 50.degree. C. or higher, the internal heat
exchanger heats a refrigerant sucked into a compressor so that
superheat becomes 10.degree. C. or higher.
23. An expansion valve for a refrigerating cycle that uses a
refrigerant in a supercritical state, the expansion valve
comprising a temperature-sensing portion having a first enclosed
space provided above a diaphragm and charged with a refrigerant,
and a second enclosed space provided to be communicated to the
first enclosed space, and wherein a refrigerant on an outlet side
of a gas cooler, or a refrigerant on an outlet side of an internal
heat exchanger is introduced below the diaphragm to apply high
pressure below the diaphragm, a refrigerant temperature at the
outlet side of the gas cooler, or a refrigerant temperature at the
outlet side of the internal heat exchanger is transmitted to a
refrigerant charged in the temperature-sensing portion, and the
valve is opened and closed by that displacement of the diaphragm,
which is caused by a pressure difference between above and below
the diaphragm.
24. The expansion valve for a refrigerating cycle according to
claim 23, wherein the second enclosed space is provided inside a
valve member fixed to the diaphragm.
25. The expansion valve for a refrigerating cycle according to
claim 23, wherein the sum of a half of a volume of the first
enclosed space and a volume of the second enclosed space amounts to
60% or more of the sum of a volume of the first enclosed space and
the second enclosed space.
26. The expansion valve for a refrigerating cycle according to any
one of claim 23, further comprising a lid that covers a wall
surface of the first enclosed space in contact with an outside air
to provide an air layer between the wall surface and the outside
air.
27. The expansion valve for a refrigerating cycle according to any
one of claim 23, wherein at least a part of the wall surface of the
first enclosed space in contact with an outside air is covered by a
thermal insulating material.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an expansion valve for a
refrigerating cycle that controls a refrigerant on a radiator
outlet side on the basis of a refrigerant temperature at the
radiator (gas cooler) outlet side of a vapor-compression-type
refrigerating cycle, and is especially suited to a supercritical
refrigerating cycle that uses a refrigerant, such as carbon dioxide
(CO.sub.2) or the like, in a supercritical range.
[0003] 2. Description of Related Art
[0004] Generally, it is known to use, as a vehicular air
conditioning apparatus, a vapor-compression-type refrigerating
cycle that circulates CO.sub.2 as a refrigerant in a closed circuit
comprising a compressor 1, a gas cooler (radiator) 2, an expansion
valve 3, an evaporator 4, an accumulator 5, etc. Conventionally, a
pressure control valve as disclosed in JP-A-2000-193347 and
JP-A-2003-254460 is known as a mechanical type expansion valve used
in such a vapor compression type refrigerating cycle.
[0005] As shown in FIG. 12, the pressure control valves disclosed
in JP-A-2000-193347 and JP-A-2003-254460 control a refrigerant
pressure at an outlet side of a radiator 2 by passing a refrigerant
at an outlet of a radiator 2 in a casing 30, which covers a valve
member part, in which gases such as refrigerant or the like are
charged in an enclosed space A formed on one side of a diaphragm 32
with the diaphragm therebetween, and a pressure of high pressure
refrigerant before pressure reduction acts on the other side to
displace the diaphragm 32 to make a valve member 31 move, and
detecting a refrigerant in the enclosed space (temperature-sensing
portion) A.
[0006] However, the pressure control valve of the conventional type
involves a problem that the weight is increased to lead to an
increase in cost as there is a need for the casing 33 that covers
the enclosed space (temperature-sensing portion).
[0007] Also, there is also known a pressure control valve
(expansion valve) of a type in which the casing 30 is eliminated to
achieve reduction in cost, an enclosed space is connected to a
temperature-sensing cylinder 7 through a capillary tube 6, the
temperature-sensing cylinder 7 is provided in contact with a pipe
at an outlet of a radiator 2, and the temperature-sensing cylinder
7 detects a refrigerant temperature at the outlet of the radiator
2, but this type of expansion valve involves a problem of an
increase in cost as there is a need of a process of assembling the
temperature-sensing cylinder 7.
[0008] Also, the case where CO.sub.2 is used as a refrigerant
involves a problem that the theoretical cycle efficiency is low as
compared to HFC134a as conventionally used. Therefore, there is a
need of enhancing an efficiency COP of a refrigerating cycle
through heat exchange between a gas cooler outlet refrigerant and a
refrigerant sucked by a compressor with the use of an internal heat
exchanger shown in FIG. 3. When the internal heat exchanger is
used, a sucked refrigerant of the compressor is heated and enthalpy
is increased to bring about a superheat state. In order to
efficiently operate a refrigerating cycle in which a refrigerant,
such as CO.sub.2, with high pressure becomes supercritical, there
is proposed a construction in which density in an enclosed space is
prescribed but this takes no account of a refrigerating cycle using
an internal heat exchanger (see JP-A-9-264622).
[0009] Further, as a gas cooler outlet refrigerant temperature or
an internal heat exchanger outlet refrigerant temperature is
detected in a CO.sub.2 cycle, a high pressure control valve is
arranged in an engine room in the case where the cycle is applied
to a vehicular air conditioning apparatus. As the temperature in
the engine room is higher than that of an outside air and a
refrigerant cooled by a gas cooler does not flow to the control
valve when the cycle is stopped, the control valve is heated to the
ambient temperature in the engine room, which is higher than that
of an outside air, and sometimes reaches 100.degree. C. to
120.degree. C.
[0010] As a refrigerant is charged in a temperature-sensing portion
in the control valve, the pressure in the temperature-sensing
portion rapidly rises when an ambient temperature rises and the
charged refrigerant is heated. As a refrigerant temperature at a
gas cooler outlet is cooled close to the ambient temperature, a
maximum temperature in the engine room reaches 30 to 60.degree. C.
above a maximum temperature of the refrigerant at the gas cooler
outlet. Therefore, the pressure in the temperature-sensing portion
at the time of stoppage becomes higher than a maximum pressure of
the CO.sub.2 cycle, so that a very high pressure-resistance, above
that for other high pressure parts, is demanded of the
temperature-sensing portion.
[0011] In this manner, when the control valve is heated to an
ambient temperature in the engine room, the pressure in the
temperature-sensing portion becomes higher than a normal
high-pressure control pressure to bring about a valve-closed state
at the startup of the CO.sub.2 cycle. Therefore, cooling of the
temperature-sensing portion is conventionally performed by
circulating a small quantity of refrigerant through a bleed hole
provided near the valve part and causing the refrigerant cooled by
a gas cooler to flow to the control valve. Thereafter, the control
valve is opened until temperature of the temperature-sensing
portion is decreased and internal pressure of the
temperature-sensing portion is decreased to a range of
high-pressure control pressure, so that the refrigerant is
increased in flow rate and a maximum cooling capacity is obtained.
Accordingly, in order to reduce the time elapsed until the maximum
cooling capacity is attained, that is, cool-down, it becomes
important to quickly lower the internal pressure of the
temperature-sensing portion to a normal control pressure.
[0012] Besides, in a supercritical cycle using CO.sub.2, a
refrigerant in a temperature-sensing portion is put in a
supercritical state as the temperature of a refrigerant at a gas
cooler outlet, in which high pressure is attained, or an internal
heat exchanger outlet is detected. With a conventional HFC134a, a
refrigerant in a temperature-sensing portion is used in a
gas-liquid two-phase and a refrigerant pressure is determined at a
saturation temperature, that is, a liquid refrigerant temperature,
so that pressure in the temperature-sensing portion is not affected
by temperatures in other regions. However, a refrigerant put in a
supercritical state is affected by temperatures of those regions,
which are communicated to and other than the temperature-sensing
portion, to cause a problem that the internal pressure of the
temperature-sensing portion is not determined and control pressure
is varied.
SUMMARY OF THE INVENTION
[0013] The invention has been made in view of the above problems
and has as its object to provide an expansion valve for a
refrigerating cycle that does not need any casing and any
temperature-sensing cylinder, can reduce the body dimensions and
the weight of the whole valve and enables a reduction in cost. A
further object is to provide an expansion valve for a refrigerating
cycle that can decrease the pressure-resistance of a
temperature-sensing portion by optimizing control characteristics
in the case where an internal heat exchanger is used in
combination. A still further object is to provide an expansion
valve or a refrigerating cycle comprising an expansion valve which,
when used in a supercritical cycle, decreases variation in control
pressure and enables miniaturization of an expansion valve
member.
[0014] The invention provides, as means for solving the problem, an
expansion valve for a refrigerating cycle according to the
respective claims.
[0015] An expansion valve for a refrigerating cycle according to
the first aspect of the present invention is arranged in a
refrigerant passage leading from a gas cooler to an evaporator in a
vapor compression type refrigerating cycle, and comprises a
temperature-sensing portion, inner pressure of which is varied
according to the refrigerant temperature at the outlet side of the
gas cooler, a valve member that mechanically interlocks with a
change in internal pressure of the temperature-sensing portion to
adjust an opening degree of the valve port, and a body that
accommodates therein the valve member, and the body is provided
with a flow passage, through which a refrigerant reduced in
pressure by the valve member is led to the evaporator while the
refrigerant temperature at the outlet side of the gas cooler is
transmitted to the temperature-sensing portion, whereby it is
possible to omit a casing that covers the temperature-sensing
portion, or a capillary tube and a temperature-sensing cylinder,
into which a refrigerant is introduced, and to achieve
miniaturization of the expansion valve and reduction in cost.
[0016] An expansion valve for a refrigerating cycle according to
the second aspect of the present invention is applied to a vapor
compression type refrigerating cycle provided with an internal heat
exchanger, and arranged in a refrigerant passage leading from an
internal heat exchanger to an evaporator, the expansion valve
comprising a temperature-sensing portion, inner pressure of which
is varied according to the refrigerant temperature at the outlet
side of the gas cooler, a valve member that mechanically interlocks
with a change in internal pressure of the temperature-sensing
portion to adjust an opening degree of the valve port, and a body
that accommodates therein the valve member, and wherein the body is
provided with a first flow passage, through which a refrigerant
flows to the internal heat exchanger, and a second flow passage,
through which a refrigerant reduced in pressure by the valve member
is led to the evaporator from the internal heat exchanger, while
the refrigerant temperature at the outlet side of the gas cooler is
transmitted to the temperature-sensing portion, whereby it is
possible in the same manner as the first aspect to achieve
miniaturization of the expansion valve and a reduction in cost.
[0017] An expansion valve for a refrigerating cycle according to
the third aspect of the present invention is applied to a vapor
compression type refrigerating cycle provided with an internal heat
exchanger, and is arranged in a refrigerant passage leading from an
internal heat exchanger to an evaporator, the expansion valve
comprising a temperature-sensing portion, inner pressure of which
is varied according to the refrigerant temperature at the outlet
side of the internal heat exchanger, a valve member that
mechanically interlocks with a change in internal pressure of the
temperature-sensing portion to adjust an opening degree of the
valve port, and a body that accommodates therein the valve member,
and wherein the body is provided with a flow passage, through which
a refrigerant reduced in pressure by the valve member flows to the
evaporator while the refrigerant temperature at the outlet side of
the internal heat exchanger is transmitted to the
temperature-sensing portion.
[0018] With the expansion valve, the temperature-sensing portion
can comprise a diaphragm, and a lid and a lower support member,
which interpose therebetween a peripheral edge of the diaphragm
from upper and lower directions to define an enclosed space above
the diaphragm, and transmission of a refrigerant temperature to the
temperature-sensing portion is performed by a clearance, which is
formed by the valve member and the lower support member to be
communicated to the refrigerant passage, whereby it is possible to
transmit a refrigerant temperature to the temperature-sensing
portion through the clearance and to omit a casing, or a capillary
tube and a temperature-sensing cylinder.
[0019] With the expansion valve, the enclosed space of the
temperature-sensing portion can be charged with a refrigerant and
provided with an adjustment spring, which biases the valve member
in a Salve closing direction, and a valve closing force provided by
internal pressure in the temperature-sensing portion and the
adjustment spring and a valve opening force provided by a
refrigerant pressure balance to operate the valve member.
[0020] With the expansion valve, the enclosed space of the
temperature-sensing portion can be charged with a mixed gas of a
refrigerant and gases, which are lower in coefficient of thermal
expansion than the refrigerant, and an adjustment spring, which
biases the valve member in a valve closing direction, is omitted,
whereby it is possible to simplify the construction and reduced the
number of parts.
[0021] An expansion valve for a refrigerating cycle according to
the fourth aspect of the present invention is one provided with an
internal heat exchanger, and has a feature in that a density, at
which a refrigerant is charged in the temperature-sensing portion,
is 200 to 600 kg/m.sup.3 in a valve closed state. Thereby, it is
possible to optimize control characteristics when an internal heat
exchanger is used, and to decrease pressure-resistance of the
temperature-sensing body.
[0022] With the expansion valve, the density, at which a
refrigerant is charged in the temperature-sensing portion, can be
200 to 450 kg/m.sup.3 in a valve closed state, whereby it is
possible to further optimize control characteristics and to
decrease pressure-resistance of the temperature-sensing body.
[0023] With the expansion valve, the valve member can be opened
when high pressure at the outlet side of the gas cooler or at the
outlet side of the internal heat exchanger becomes higher by a
predetermined magnitude than inner pressure in the
temperature-sensing portion.
[0024] With the expansion valve, a load corresponding to the
predetermined magnitude can be given by an elastic member, or a
non-condensed gas charged in the temperature-sensing portion
together with a refrigerant, or the elastic member and the
non-condensed gas.
[0025] With the expansion valve, the elastic member can be any one
of a coil spring, a diaphragm, and a bellows, or an optional
combination thereof.
[0026] With the expansion valve, when a refrigerant temperature at
the outlet side of the gas cooler is 50.degree. C. or higher, the
internal heat exchanger can heat a refrigerant sucked into a
compressor so that superheat becomes 10.degree. C. or higher.
[0027] An expansion valve for a refrigerating cycle according to
the fifth aspect of the present invention is one that uses a
refrigerant in a supercritical state, and comprises a
temperature-sensing portion having a first enclosed space provided
above a diaphragm and charged with a refrigerant, and a second
enclosed space provided below the diaphragm to be communicated to
the first enclosed space. Thereby, it is possible to enlarge a
volume of the temperature-sensing body and to improve the
temperature-sensing body in accuracy.
[0028] With the expansion valve, the second enclosed space can be
provided inside a valve member fixed to the diaphragm.
[0029] With the expansion valve, the sum of a half of a volume of
the first enclosed space and a volume of the second enclosed space
can amount to 60% or more of the sum of a volume of the first
enclosed space and the second enclosed space. Thereby, it is
possible to lessen influences of temperature at a portion of the
temperature-sensing portion except the temperature-sensing cylinder
corresponding portion.
[0030] The expansion valve can further comprise a lid that covers a
wall surface of the first enclosed space in contact with an outside
air to provide an air layer between the wall surface and the
outside air, and can lessen the influence of the temperature of the
outside air.
[0031] With the expansion valve, at least a part of the wall
surface of the first enclosed space in contact with an outside air
can be covered by a thermal insulating material, and it is possible
to further lessen the influence of temperature of the outside
air.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a view illustrating a vapor compression type
refrigerating cycle, in which CO.sub.2 is circulated as a
refrigerant;
[0033] FIG. 2 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a first embodiment of the
invention, used in the refrigerating cycle illustrated in FIG.
1;
[0034] FIG. 3 is a view illustrating a vapor compression type
refrigerating cycle including an internal heat exchanger;
[0035] FIG. 4 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a second embodiment of the
invention, applied to the refrigerating cycle illustrated in FIG.
3;
[0036] FIG. 5 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a third embodiment of the
invention, applied to the refrigerating cycle illustrated in FIG.
3;
[0037] FIG. 6 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a fourth embodiment of the
invention, applied to the refrigerating cycle illustrated in FIG. 1
or 3;
[0038] FIG. 7 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a fifth embodiment of the
invention, applied to the refrigerating cycle illustrated in FIG.
3;
[0039] FIG. 8 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a sixth embodiment of the
invention, applied to the refrigerating cycle illustrated in FIG. 1
or 3;
[0040] FIG. 9 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a seventh embodiment of the
invention, applied to the refrigerating cycle illustrated in FIG. 1
or 3;
[0041] FIG. 10 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to an eighth embodiment of the
invention, applied to the refrigerating cycle illustrated In FIG.
3;
[0042] FIG. 11 is a cross sectional view showing an expansion valve
for a refrigerating cycle, according to a ninth embodiment of the
invention, applied to the refrigerating cycle illustrated in FIG.
3;
[0043] FIG. 12 is a cross sectional view showing a conventional
expansion valve for a refrigerating cycle (pressure control
valve);
[0044] FIG. 13 is a view showing an improvement in COP in the case
where an internal heat exchanger is used;
[0045] FIG. 14 is a view showing control pressure, at which COP
becomes maximum, versus a gas cooler outlet temperature when a
refrigerant in an evaporator is 0.degree. C.;
[0046] FIG. 15 is a view showing control pressure, at which COP
becomes maximum, versus a gas cooler outlet temperature when a
refrigerant in an evaporator is 20.degree. C.;
[0047] FIG. 16 is a view showing a collier chart representative of
physical properties Of CO.sub.2 refrigerant;
[0048] FIG. 17 is a view schematically showing effects at the time
of cool-down;
[0049] FIG. 18 is a view schematically showing a
temperature-sensing cylinder corresponding portion of a
temperature-sensing body and a portion except the portion;
[0050] FIG. 19 is a view (first) showing a change in control
pressure versus a ratio of a temperature-sensing cylinder
corresponding portion;
[0051] FIG. 20 is a view (second) showing a change in control
pressure versus a ratio of a temperature-sensing cylinder
corresponding portion; and
[0052] FIG. 21 is a view showing an embodiment obtained by
providing a lid on a temperature-sensing portion of the ninth
embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0053] An expansion valve for a refrigerating cycle according to an
embodiment of the invention will be described below with reference
to the drawings. FIG. 1 is a view illustrating a vapor compression
type refrigerating cycle (supercritical refrigerating cycle), in
which CO.sub.2 is circulated as a refrigerant, and FIG. 2 is a
cross sectional view showing an expansion valve for a refrigerating
cycle, according to a first embodiment of the invention, applied to
the vapor compression type refrigerating cycle illustrated in FIG.
1. In FIG. 1, the reference numeral 1 denotes a compressor that
sucks and compresses a refrigerant (CO.sub.2), and 2 a gas cooler
(radiator) that cools the refrigerant compressed by the compressor
1. An expansion valve 3 is arranged on an outlet side of the gas
cooler 2 to control a refrigerant pressure at the outlet side of
the gas cooler 2 on the basis of a refrigerant temperature at the
outlet side of the gas cooler 2, the expansion valve also
functioning as a decompressor that decompresses a refrigerant at
high pressure. In FIG. 1, a temperature-sensing cylinder 7 is
mounted on an outlet-side pipe of the gas cooler 2 and connected to
the expansion valve 3 through a capillary tube 6. Accordingly, a
valve opening degree of the expansion valve 3 is controlled
according to the change in internal pressure, which is based on a
refrigerant temperature of gases charged in the temperature-sensing
cylinder 7.
[0054] The reference numeral 4 denotes an evaporator that
evaporates a gas-liquid two-phase refrigerant decreased in pressure
by the expansion valve 3, and 5 an accumulator that separates a
gaseous phase refrigerant and a liquid phase refrigerant from each
other and temporarily accumulates a surplus refrigerant in the
refrigerating cycle. The compressor 1, the gas cooler 2, the
expansion valve 3, the evaporator 4, and the accumulator 5 are
connected together by means of piping to form a closed circuit.
[0055] Subsequently, an expansion valve for a refrigerating cycle
3A according to the first embodiment will be described with
reference to FIG. 2. Formed in a body 33 of the expansion valve 3A
is a part of a refrigerant low passage leading from the gas cooler
2 to the evaporator 4 via a valve port 33a. Formed in the body 33
are an inflow port 33b connected to a side of the gas cooler 2, an
outflow port 33c connected to a side of the evaporator 4, a first
opening 33d, to which a temperature-sensing portion described later
is mounted, and a second opening 33e, in which an adjustment spring
36 is set. A valve member 31 is received in the body 33 to open and
close the valve port 33a whereby an upstream space C.sub.1
connected to an outlet side of the gas cooler 2 and a downstream
space C.sub.2 connected to an inlet side of the evaporator 4, which
spaces are disposed in the body 33, are put into communication and
non-communication to each other.
[0056] The temperature-sensing portion is mounted to the first
opening 33d of the body 33. The temperature-sensing portion mainly
comprises the diaphragm 32, a lid 35, and a lower support member
34, and is formed therein with an enclosed space A. That is, a
concave portion 35a is formed centrally of the lid 35 to define the
enclosed space A, and the lid 35 and the lower support member 34
interpose and secure a peripheral edge of the diaphragm 32
therebetween to form the temperature-sensing portion. The diaphragm
32 is in the form of a thin film made of a stainless steel material
to be deformed and displaced according to a pressure difference
inside and outside the enclosed space A. The lower support member
34 comprises a cylindrical portion 34a and a flange portion 34b,
and a threaded portion formed on an outer periphery of the
cylindrical portion 34a is threaded into the first opening 33d of
the body 33 to mount the temperature-sensing portion to the body
33. Also, a charge pipe 35b is mounted to the lid 35 and a
refrigerant is charged into the enclosed space A through the charge
pipe 35b. After the refrigerant is charged, the charge pipe 35b is
sealed.
[0057] One end 31b of the valve member 31, extending upwardly, of a
valve portion 31a through the cylindrical portion 34a of the lower
support member 34 is fixed to the diaphragm 32, and a clearance B
having an annular-shaped cross section is formed between an inner
surface of the cylindrical portion 34a and an outer peripheral
surface of the valve member 31. The clearance B is communicated to
an upstream space C.sub.1 connected to the outlet side of the gas
cooler 2. Accordingly, a refrigerant on the outlet side of the gas
cooler 2 flows into the clearance B, so that a refrigerant
temperature is transmitted to a refrigerant in the enclosed space A
and at the same time pressure of the refrigerant on the outlet side
of the gas cooler 2 acts on the diaphragm 32.
[0058] Further, an adjustment nut 37 is threaded onto the other end
31c of the valve member 31 extending downwardly of the valve
portion 31a through the valve port 33a. The adjustment spring 36
that biases the valve member 31 in a valve closing direction is
interposed between a neighborhood of an underside of the valve port
33a and the adjustment nut 37, and an initial set load (an elastic
force in a state, in which the valve port 33a is closed) of the
adjustment spring 36 can be optionally adjusted by rotating the
adjustment nut 37. The adjustment spring 36, the adjustment nut 37,
etc. are provided in the downstream space C.sub.2 connected to the
inlet side of the evaporator 4. Also, a cap 38 is fitted into the
second opening 33e of the body 33 whereby a lower part of the
downstream space C.sub.2 is closed.
[0059] With the expansion valve for a refrigerating cycle 3A,
according to the first embodiment, constructed in the above manner,
a valve closing force of the valve member 31 is provided by inner
pressure in the enclosed space A and the adjustment spring 36, a
valve opening force of the valve member 31 is provided by a
refrigerant pressure at the outlet side of the gas cooler 2, and
balance of the both forces affords opening and closing the
expansion valve 3A. Also, the inner pressure in the enclosed space
A is varied depending upon temperature of that refrigerant on the
outlet side of the gas cooler 2, which flows into the clearance B,
whereby the valve port 33a is varied in opening degree to control
the refrigerant pressure at the outlet side of the gas cooler
2.
[0060] FIG. 3 is a view illustrating a vapor compression type
refrigerating cycle, in which an internal heat exchanger is
incorporated. In this manner, the vapor compression type
refrigerating cycle including an internal heat exchanger is a
conventionally known refrigerating cycle to improve a cooling
capacity. In this case, an internal heat exchanger 8 is arranged in
the cycle as shown in FIG. 3 so as to make heat exchange between a
refrigerant going to the expansion valve 3 from the gas cooler 2
and a refrigerant returning to the compressor 1 from the
accumulator 5. Accordingly, the evaporator valve 3 is arranged in a
refrigerant passage leading from the internal heat exchanger 8 to
the evaporator 4. The remaining construction is the same as the
vapor compression type refrigerating cycle illustrated in FIG. 1
and so an explanation therefor is omitted. The refrigerating cycle
according to the invention is also applicable to a vapor
compression type refrigerating cycle including such an internal
heat exchanger.
[0061] FIG. 4 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3B, according to a second embodiment,
applied to a vapor compression type refrigerating cycle including
an internal heat exchanger. A first flow passage D making a part of
a refrigerant flow passage leading from a gas cooler 2 to an
internal heat exchanger 8 and a second flow passage E making a part
of a refrigerant flow passage leading from the internal heat
exchanger 8 to an evaporator 4 via a valve port 33a, respectively,
are formed independently in a body 33 of the expansion valve 3B
according to the second embodiment. According to the second
embodiment, a clearance B, through which a refrigerant temperature
at an outlet side of the gas cooler 2 is transmitted to a
refrigerant in an enclosed space A of a temperature-sensing
portion, is provided on a side of the first flow passage D, and a
valve portion 31a of a valve member 31, which opens and closes the
valve port 33a, is provided on a side of the second flow passage
E.
[0062] That is, one end 31b of the valve member 31 extending
upwardly of a valve portion 31a across the first flow passage D and
through a cylindrical portion 34a of a lower support member 34 is
fixed to a diaphragm 32, and a clearance B having an annular-shaped
cross section is provided between an inner surface of the
cylindrical portion 34a and an outer peripheral surface of the
valve member 31. The clearance E is communicated to the first flow
passage D connected to the outlet side of the gas cooler 2.
Accordingly, a refrigerant on the outlet side of the gas cooler 2
flows into the clearance B, so that the refrigerant temperature is
transmitted to a refrigerant in the enclosed space A and at the
same time pressure of the refrigerant on the outlet side of the gas
cooler 2 acts on the diaphragm 32.
[0063] A valve port 33a providing for communication between the
internal heat exchanger 8 and the evaporator 4 is provided in the
second flow passage E. Accordingly, the valve portion 31a of the
valve member 31, which opens and closes the valve port 33a, an
adjustment spring 36 provided on the other end 31c of the valve
member 31 extending downward through the valve port 33a, an
adjustment nut 37, etc. are provided in the second flow passage E.
The remaining detailed construction is the same as that of the
first embodiment and so an explanation therefor is omitted.
[0064] FIG. 5 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3C, according to a third embodiment,
applied to a vapor compression type refrigerating cycle including
an internal heat exchanger. According to the third embodiment, a
part of a refrigerant flow passage leading from an internal heat
exchanger 8 to an evaporator 4 via a valve port 33a is formed in a
body 33 of the expansion valve 3C. That is, the remaining
construction is the same as that of the expansion valve 3A of the
first embodiment except that an inflow port 33b of the body 33 is
connected to the internal heat exchanger 8 in place of a gas cooler
2.
[0065] Accordingly, according to the third embodiment, a
refrigerant on an outlet side of the internal heat exchanger 8
flows into a clearance B, so that a refrigerant temperature at the
outlet side of the internal heat exchanger 8 is transmitted to a
refrigerant charged in an enclosed space A of a temperature-sensing
portion. Likewise, a refrigerant pressure at the outlet side of the
internal heat exchanger 8 acts on a diaphragm 32. The same function
and effect as those in the first embodiment are produced also in
the third embodiment.
[0066] FIG. 6 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3D, according to a fourth embodiment,
applied to the vapor compression type refrigerating cycle
illustrated in FIG. 1 or FIG. 3. According to the fourth
embodiment, in place of the adjustment spring 36, for example,
nitrogen gases (N.sub.2), helium gases (He), etc., which are lower
in the coefficient of thermal expansion than a refrigerant,
together with the refrigerant are charged in an enclosed space A in
the expansion valve according to the first embodiment in FIG. 2 or
in the expansion valve according to the third embodiment in FIG. 5.
That is, according to the fourth embodiment, a refrigerant and
gases, which are lower in coefficient of thermal expansion than the
refrigerant, are charged in the enclosed space A of the
temperature-sensing portion, a second opening 33e of a body 33 is
closed, and a portion extending downwardly of a valve portion 31a
of a valve member 31, an adjustment spring 36, an adjustment nut
37, etc. are removed. The remaining construction is the same as
that of the first embodiment or the third embodiment and so an
explanation therefor is omitted.
[0067] Accordingly, according to the fourth embodiment, only inner
pressure of those mixed gases charged in the enclosed space A, to
which temperature of a refrigerant on the outlet side of the gas
cooler 2 flowing into a clearance B is transmitted, acts as a valve
closing force of the valve member 31, and a refrigerant pressure at
the outlet side of the gas cooler 2 acts as a valve opening force.
In this manner, according to the fourth embodiment, gases, which
are lower in the coefficient of thermal expansion than the
refrigerant, function as an adjustment spring 36. Also, in the case
where a refrigerant is carbon dioxide (CO.sub.2) and the gas being
mixed are nitrogen gas (N.sub.2), it is preferred that carbon
dioxide (CO.sub.2) be charged at a density in the order of 500 to
700 kg/m.sup.3 and nitrogen gas (N.sub.2) be charged at a density
in the order of 10 to 40 kg/m.sup.3.
[0068] FIG. 7 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3E, according to a fifth embodiment,
applied to a vapor compression type refrigerating cycle including
the internal heat exchanger shown in FIG. 3. According to the fifth
embodiment, as in the fourth embodiment, in place of the adjustment
spring 36, for example, nitrogen gas (N.sub.2) helium gas (He),
etc., which are lower in the coefficient of thermal expansion than
a refrigerant, together with the refrigerant are charged in an
enclosed space A in the expansion valve 3B according to the second
embodiment. That is, according to the fifth embodiment, a mixed gas
of a refrigerant and gases, which are lower in coefficient of
thermal expansion than the refrigerant, are charged in an enclosed
space A of a temperature-sensing portion, a second opening 33e of a
body 33 is closed, and a portion extending downwardly of a valve
portion 31a of a valve member 31, an adjustment spring 36, an
adjustment nut 37, etc. are removed from a second flow passage E.
The remaining construction is the same as that of the second
embodiment and so an explanation therefor is omitted.
[0069] Accordingly, according to the fifth embodiment, only inner
pressure of those mixed gases charged in the enclosed space A, to
which temperature of a refrigerant on an outlet side of a gas
cooler 2 flowing into a clearance B is transmitted, acts as a valve
closing force of the valve member 31, and a refrigerant pressure at
the outlet side of the gas cooler 2 acts as a valve opening force.
In this manner, according to the fifth embodiment, gases, which are
lower in the coefficient of thermal expansion than the refrigerant,
functions as an adjustment spring 36. Also, in the case where a
refrigerant is carbon dioxide (CO.sub.2) and the gases being mixed
are nitrogen gas (N.sub.2), it is preferred that carbon dioxide
(CO.sub.2) be charged at a density in the order of 400 to 550
kg/m.sup.3 and nitrogen gases (N.sub.2) be charged at a density in
the order of 10 to 40 kg/m.sup.3.
[0070] FIG. 8 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3F, according to a sixth embodiment of
the invention, applied to the refrigerating cycle shown in FIG. 1
or FIG. 3. According to the sixth embodiment, a cavity 31d
communicated to an enclosed space A of a temperature-sensing
portion is formed in the valve member 31 of the expansion valve 3
according to the first embodiment in FIG. 2 or according to the
third embodiment in FIG. 5. Accordingly, the enclosed space of the
temperature-sensing portion can comprise the sum of (the enclosed
space A+the cavity 31d+the charge pipe 35b), and the enclosed space
charged with a refrigerant can be enlarged, so that it is possible
to improve the temperature-sensing portion in accuracy. The
remaining construction is the same as that of the first embodiment
or the third embodiment and so an explanation therefor is
omitted.
[0071] FIG. 9 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3G, according to a seventh embodiment of
the invention, applied to the refrigerating cycle shown in FIG. 1
or FIG. 3. According to the seventh embodiment, like the sixth
embodiment, a cavity 31d communicated to an enclosed space A of a
temperature-sensing portion is formed in the valve member 31 of the
expansion valve 3 according to the fourth embodiment in FIG. 6.
Also, according to the seventh embodiment, the enclosed space of
the temperature-sensing portion can be further increased by a
volume of the cavity 31d, so that it is possible to improve the
temperature-sensing portion in accuracy. The remaining construction
is the same as that of the fourth embodiment and so an explanation
therefor is omitted.
[0072] FIG. 10 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3H, according to an eighth embodiment of
the invention, applied to the refrigerating cycle shown in FIG. 3.
According to the eighth embodiment, like the sixth and seventh
embodiments, a cavity 31d communicated to an enclosed space A of a
temperature-sensing portion is formed in the valve member 31 of the
expansion valve 3 according to the fifth embodiment in FIG. 7.
Also, according to the eighth embodiment, the enclosed space of the
temperature-sensing portion can be further increased by a volume of
the cavity 31d, so that it is possible to improve the
temperature-sensing portion, in accuracy. The remaining
construction is the same as that of the fifth embodiment and so an
explanation therefor is omitted.
[0073] FIG. 11 is a cross sectional view showing an expansion valve
for a refrigerating cycle 3I, according to a ninth embodiment of
the invention, applied to the refrigerating cycle shown an FIG. 3.
According to the ninth embodiment, like the sixth, seventh, and
eighth embodiments, a cavity 31d communicated to an enclosed space
A of a temperature-sensing portion is formed in the valve member 31
of the expansion valve 3 according to the second embodiment in FIG.
4. Also, according to the ninth embodiment, the enclosed space of
the temperature-sensing portion can be further increased by a
volume of the cavity 31d, so that it is possible to improve the
temperature-sensing portion, in accuracy. The remaining
construction is the same as that of the second embodiment and so an
explanation therefor is omitted.
[0074] In addition, while the embodiments have described an
expansion valve used for a vapor compression type refrigerating
cycle, in which carbon dioxide (CO.sub.2) is used as a refrigerant,
the expansion valve for a refrigerating cycle according to the
invention is not limited thereto but is also applicable to a vapor
compression type refrigerating cycle, in which the refrigerant is
fluorocarbon or the like, not to mention a vapor compression type
refrigerating cycle, in which a refrigerant, such as ethylene,
ethane, nitrogen oxide, etc., used in a supercritical zone, is
used.
[0075] Subsequently, an explanation is given to an embodiment of an
expansion valve suited to a supercritical refrigerating cycle, in
which the internal heat exchanger 8 shown in FIG. 3 is
incorporated. The expansion valve according to the embodiment is
intended for firstly, improving COP of a refrigerating cycle
including an internal heat exchanger, secondly, enabling decreasing
the pressure-resistance of a temperature-sensing portion to achieve
reduction in cost, and thirdly, accelerating the cool-down.
Therefore, the embodiment prescribes the density at which a
refrigerant is charged in a temperature-sensing portion. An
explanation is given below.
[0076] FIG. 13 shows effects of an improvement in COP in the case
where an internal heat exchanger is used to provide for superheat
in a sucked refrigerant. TS in the figure indicates a refrigerant
evaporating temperature in an evaporator. Accordingly, the higher a
refrigerant temperature in an evaporator, the higher an improvement
in COP. In a vehicular air conditioner, a compressor is decreased
in rotating speed at the time of idling and a cooling capacity
becomes minimum. However, as a refrigerant evaporating temperature
in an evaporator rises, COP of a vehicular air conditioner is
enhanced when an internal heat exchanger is used. In this manner,
the use of an internal heat exchanger in a vehicular air
conditioner produces a great advantage.
[0077] FIGS. 14 and 15 show high pressure control pressures, at
which COP becomes a maximum, relative to a gas cooler outlet
refrigerant temperature in the case where a refrigerant temperature
in an evaporator is 0.degree. C. and in the case where a
refrigerant temperature in an evaporator is 20.degree. C., and show
characteristics that in the case where an internal heat exchanger
is used to heat a compressor sucked refrigerant, the lower control
pressure in case of possessing superheat, the higher a refrigerant
evaporating temperature in an evaporator and the higher a gas
cooler outlet refrigerant temperature.
[0078] This is apparent in the Mollier chart shown in FIG. 16 and
representative of physical properties of CO.sub.2 refrigerant. That
is, a refrigerant sucked by a compressor ideally follows along an
isoentropic line to be compressed to a high temperature high
pressure refrigerant. An isoentropic line for the physical
properties of CO.sub.2 refrigerant is less inclined as it goes to
the right side in the Mollier chart where enthalpy is increased.
This is because, when a comparison is made at the same pressure, an
increase in enthalpy (=compressor power) in case of compression to
the same pressure becomes large in the case where a refrigerant
with superheat is heated, as compared with the case where a
saturated gas refrigerant is sucked and compressed.
[0079] For a cycle with the use of CO.sub.2 refrigerant, there is
known a method of exercising control to high pressure, at which COP
becomes maximum, relative to a gas cooler outlet refrigerant
temperature. In case of the provision of an internal heat
exchanger, there is produced an advantage that a high pressure, at
which COP becomes maximum, is decreased since a compressor power is
increased. Also, the ability of making a control pressure low
produces an advantage in improving other high-pressure parts such
as a compressor, a gas cooler, etc. in durability.
[0080] For example, with vehicles, since a traveling wind is not
generated at the time of idling, a gas cooler is decreased in wind
velocity, and additionally a sucked air temperature rises and a gas
cooler outlet refrigerant temperature rises due to blowing-in of a
hot wind from an engine room. Accordingly, control pressure becomes
low in the case where an internal heat exchanger is used.
[0081] Accordingly, in order to make effective use of a
refrigerating cycle, in which an internal heat exchanger is used,
there is a need for a high-pressure control valve having control
characteristics that control pressure is further decreased for the
same gas cooler outlet refrigerant temperature. Also, it is
necessary to charge a refrigerant into a control valve having such
characteristics at a lower density than that at which a refrigerant
is charged into a conventional temperature-sensing portion (see
JP-A-9-264622).
[0082] As seen from FIG. 15, assuming that a refrigerant
temperature in an evaporator is 20.degree. C. and superheat of a
sucked refrigerant is 10.degree. C. in a refrigerating cycle, in
which an internal heat exchanger having a small heat exchanging
capacity is used, COP assumes a maximum value when a refrigerant
temperature at a gas cooler outlet is 60.degree. C. and control
pressure is 15 MPa. In order to make a control pressure attain 15
MPa, it is necessary to adopt a charged refrigerant density
(hereinafter called a charging density) in the order of about 600
kg/m.sup.3.
[0083] Since COP is improved when an internal heat exchanger having
a large heat exchanging capacity is used, it is conceivable to
increase a quantity of superheat further. As a discharge
temperature also rises when a sucked refrigerant temperature of a
compressor becomes high, however, a quantity of superheat is
preferred to be in the range of 15 to 25.degree. C. In case of
adopting a quantity of superheat in the range of 15 to 25.degree.
C., COP becomes maximum in the case where control pressure is made
14.2 MPa, for example, when a gas cooler outlet refrigerant
temperature is 60.degree. C. In order to make a control pressure
attain 14.2 MPa, it is necessary to adopt a charging density in the
order of about 570 kg/m.sup.3.
[0084] Also, as that density, at which a refrigerant is charged in
a temperature-sensing portion of an expansion valve, is desirably
low in terms of pressure-resistance of the expansion valve
described later, inner pressure in the temperature-sensing portion
is set low by about 2 MPa by further using in combination a spring
for biasing the valve in a valve closing direction whereby control
pressure, at which COP becomes maximum, can be ensured even in a
charging density in the order of about 450 kg/m.sup.3 when a gas
cooler outlet refrigerant temperature is 60.degree. C.
Subsequently, an explanation is given to pressure-resistance of a
temperature-sensing portion. As pressure in the temperature-sensing
portion at the time of stoppage of a vehicle becomes very high, a
large pressure-resistance is required. As is apparent from the
Mollier chart of CO.sub.2 refrigerant shown in FIG. 16, the higher
a density, the more rapid pressure rises relative to temperature,
so that in order to decrease an increase in internal pressure of a
temperature-sensing portion, it is necessary to lower a charging
density. In particular, there is caused a problem that since an
inclination of an isothermal line intersecting an equidensity line
becomes is large when the charging density exceeds 600 kg/m.sup.3,
an increase in internal pressure relative to temperature rise
becomes also large.
[0085] Also, since a maximum allowable pressure of high-pressure
parts is set to about 18 MPa, an upper limit of pressure in a
temperature-sensing portion is made in the same order as the
pressure to eliminate the need of excessively heightening only the
temperature-sensing portion in strength to enable making the same
equal to other high-pressure parts in strength, thus enabling
providing a control valise at low cost.
[0086] Therefore, while it is required that a temperature-sensing
portion charging density be set to at most about 550 kg/m.sup.3
when a maximum ambient temperature is 80.degree. C., at most about
450 kg/m.sup.3 when a maximum ambient temperature is 100.degree.
C., and at most about 360 kg/m.sup.3 when a maximum ambient
temperature is 120.degree. C., it is desired that the charging
density be set to at most 450 kg/m.sup.3 since 100.degree. C. at
the highest must be taken account of even when a position of low
temperature is selected as a mount position in an engine room.
[0087] Further, since a charging density for an intended control
pressure can be reduced by a quantity corresponding to a spring
load by giving a load in a direction of closure with the use of a
spring or the line, it is effective to use the spring or the like
in combination.
[0088] When a temperature-sensing portion charging density is made
small, control pressure for a gas cooler outlet refrigerant
temperature is decreased but the control pressure, at which COP
becomes maximum, is also decreased in case of using an internal
heat exchanger, so that the use of the internal heat exchanger
makes it possible to decrease that density, at which a refrigerant
is charged in a temperature-sensing portion of an expansion valve,
without decreasing COP.
[0089] In addition, as shown in the Mollier chart in FIG. 16, a
tendency is demonstrated, in which an inclination of the isothermal
line becomes rapidly small and a change in enthalpy become large
relative to pressure change when temperature and pressure of a
refrigerant come near to a critical point. Since a quantity of
discharged heat is decreased and a cooling capacity is decreased
when enthalpy at a gas cooler outlet increases, it is desired that,
for example, high pressure at 40.degree. C. of refrigerant
temperature be equal to or higher than 9 MPa (T point in FIG.
16).
[0090] Even when a method of giving an initial load by means of a
spring or the like is used in combination, a decrease in cooling
capacity becomes conspicuous unless inner pressure in a
temperature-sensing portion when at 40.degree. C. is set to be 7
MPa or higher (at 2 MPa corresponding to a spring load).
Accordingly, the temperature-sensing portion charging density is
desirably 200 kg/m.sup.3 or higher.
[0091] Finally, an explanation is given to an acceleration of
cool-down. As described above, at the start of CO.sub.2 cycle,
cooling of a temperature-sensing portion is performed by
circulating a small quantity of refrigerant through a bleed hole
provided near a valve part and causing the refrigerant cooled by a
gas cooler to flow to a control valve, and the control valve is
opened when the temperature-sensing portion is decreased in
temperature and internal pressure of the temperature-sensing
portion is decreased to a range of high-pressure control pressure.
Accordingly, in order to accelerate cool-down, it becomes important
to quickly lower the internal pressure of the temperature-sensing
portion to a normal range of control pressure. In order to quickly
lower the internal pressure of the temperature-sensing portion to a
normal range of control pressure, it is effective to use an
internal heat exchanger to set a control pressure to a little low
and to decrease that density, at which a refrigerant is charged in
a temperature-sensing portion of a mechanical type control
valve.
[0092] FIG. 17 schematically shows effects at the time of
cool-down. When a refrigerating cycle is stopped, an expansion
valve in an engine room is heated to high temperature, for example,
about 80.degree. C. When the refrigerating cycle is started in this
state, the valve is closed because the internal pressure of a
temperature-sensing portion exceeds an upper limit pressure (in
this case, 13 MPa) in operation of the cycle. Therefore, a small
quantity of refrigerant cooled by a gas cooler flows through a
bleed hole provided near a valve part to cool the
temperature-sensing portion. At this time, a compressor is varied
in capacity so as not to exceed the upper limit pressure in
operation, thus controlling high pressure.
[0093] When the temperature-sensing portion is decreased in
temperature and the internal pressure thereof becomes equal to or
lower than the upper limit pressure in operation, the valve is
opened and the compressor becomes maximum in capacity, so that the
refrigerant is increased in flow rate and a maximum cooling
capacity is demonstrated.
[0094] When that density, at which the refrigerant is charged in
the temperature-sensing portion, is high, there is a need for
cooling to a further low temperature as compared with the case
where the charging density is low, in order that the internal
pressure of the temperature-sensing portion become equal to or
lower than the upper limit pressure in operation. Thus time (=time,
during which the refrigerant is small in flow rate), during which
the temperature-sensing portion is cooled at the start, is
prolonged and a decrease in blow-off temperature is delayed.
[0095] According to the embodiment, the above is taken into
consideration and an optimum value of a temperature-sensing portion
charging density in a refrigerating cycle, in which an internal
heat exchanger is used, is prescribed in the following manner.
[0096] Typically, in the expansion valve 3I used in a refrigerating
cycle provided with the internal heat exchanger according to the
ninth embodiment illustrated with reference to FIG. 11, that
density, at which a refrigerant is charged into the enclosed space
A of the temperature-sensing portion of the expansion valve 3I, is
set in the range of about 200 kg/m.sup.3 to about 600 kg/m.sup.3.
In the case where a quantity of superheat is to be increased, an
upper limit value of the range of charging density may be made in
the order of about 570 kg/m.sup.3, and in the case where an elastic
member for biasing in a valve closing direction is used in
combination, the charging density can be made in the order of about
450 kg/m.sup.3. More desirably, that density, at which a
refrigerant is charged into the temperature-sensing portion of the
expansion valve, is set in the range of about 200 kg/m.sup.3 to
about 450 kg/m.sup.3.
[0097] Further, for the expansion valve 3H used in a refrigerating
cycle, in which the internal heat exchanger according to the
seventh embodiment and illustrated with reference to FIG. 10 is
used, the expansion valve being provided with no adjustment spring,
it is preferable to adopt a charged refrigerant density being the
same as that described above. That is, that density, at which a
refrigerant is charged into the enclosed space A of the
temperature-sensing portion of the expansion valve 3H and the
cavity 31d, is set in the range of about 200 kg/m.sup.3 to about
600 kg/m.sup.3. In the case where a quantity of superheat is to be
increased, an upper limit value in the range of charging density
may be made in the order of about 570 kg/m.sup.3 and, further, in
the case where an elastic member for biasing in a valve closing
direction is used in combination, the charging density can be in
the order of about 450 kg/m.sup.3. More desirably, that density, at
which a refrigerant is charged into the temperature-sensing portion
of the expansion valve, is set in the range of about 200 kg/m.sup.3
to about 450 kg/m.sup.3.
[0098] Also, in a refrigerating cycle, in which the internal heat
exchanger according to the second, third, and fifth embodiments
(FIGS. 4, 5, and 7) is provided, and a refrigerating cycle, in
which the internal heat exchanger according to the fourth, sixth,
and seventh embodiments (FIGS. 6, 8, 9) is provided, that density,
at which a refrigerant is charged into the temperature-sensing
portion of the expansion valve, is set in the range of about 200
kg/m.sup.3 to about 600 kg/m.sup.3. In the case where a quantity of
superheat is to be increased, an upper limit value in the range of
charging density may be in the order of about 570 kg/m.sup.3 and,
further, in the case where an elastic member for biasing in a valve
closing direction is used in combination, the charging density can
be made in the order of about 450 kg/m.sup.3. More desirably, that
density, at which a refrigerant is charged into the
temperature-sensing portion of the expansion valve, is set in the
range of about 200 kg/m.sup.3 to about 450 kg/m.sup.3.
[0099] Subsequently, an explanation is given to those embodiments,
which solve a problem that control pressure is varied in a
temperature-sensing portion, in which a refrigerant in a
supercritical state is used.
[0100] As shown in FIGS. 8 to 11, according to the sixth to ninth
embodiments, the cavity 31a being an enclosed space is formed below
the diaphragm so as to be communicated to the enclosed space A of
the temperature-sensing portion formed above the diaphragm 32.
Consequently, the enclosed space of the temperature-sensing portion
is enlarged to the enclosed space A+the cavity 31d from a
conventional enclosed space A. In addition, while the charge pipe
35b is separated from the enclosed space in the foregoing
explanation, it is included in the enclosed space A in this case.
Accordingly, it can be said that the temperature-sensing portion
according to the sixth to ninth embodiments comprises the enclosed
space A and the cavity 31d. As described above, the cavity 31d
increases a volume of the enclosed space, in which a refrigerant is
charged, and improves the temperature-sensing portion in
accuracy.
[0101] The enclosed space A is a flat space formed above the
diaphragm, temperature of a refrigerant is transmitted to the
enclosed space through the diaphragm, and an outer wall of the
enclosed space A contacts with an outside air to be susceptible to
influences of an outside air temperature. Accordingly, it can be
said in the construction of the temperature-sensing portion that,
the portion to which temperature of a refrigerant is transmitted
and which is heated, that is, the cavity 31d below the diaphragm
and a lower half of the enclosed space A in contact with the
diaphragm correspond to a temperature-sensing cylinder, and an
upper half of the enclosed space A susceptible to influences of an
outside air temperature, corresponds to another portion different
from the temperature-sensing cylinder. Accordingly, by attaching an
insulating material to the outer wall portion, temperature
variation of the upper half of the enclosed space A is lessened to
enable ensuring a minimum temperature-sensing volume.
[0102] According to the embodiment, a ratio of the portion (here,
the lower half of the enclosed space A and the cavity 31d)
corresponding to the temperature-sensing cylinder to the whole
temperature-sensing portion is prescribed to lessen variation in
control pressure.
[0103] FIG. 18 schematically shows a temperature-sensing cylinder
corresponding portion P and another portion Q. FIG. 19 shows
temperature effects of the portion Q versus a ratio of the portion
P to a whole volume, that is, a volume ratio of a direct
temperature-sensing portion P/(P+Q) for the temperature-sensing
cylinder corresponding portion P and another portion Q in the case
where the charged refrigerant density assumes a standard value of
450 kg/m.sup.3 and temperature of the portion P is 60.degree. C.
Temperature of the portion Q is 65.degree. C., 70.degree. C., and
80.degree. C. A target control pressure is one in the case where
temperature of the portion Q is 60.degree. C. to be the same as
that of the portion P.
[0104] For example, at a point S in FIG. 19 the portion P is at
60.degree. C., the portion Q is at 60.degree. C., a volumetric
ratio of the portion P is 50% (the ratio of 0.5), the refrigerant
density at the portion P is 538 kg/m.sup.3, the refrigerant density
at the portion Q is 362 kg/m.sup.3, internal pressures of the both
balance at 13.51 MPa, and an average density is 450 kg/m.sup.3. A
point S indicates pressures balance at the respective temperatures
and the volumetric ratio.
[0105] In this manner, in the case where a refrigerant is in a
supercritical state, control pressure for the expansion valve is
varied by an ambient temperature in the engine room being affected
by temperature of other portions than the temperature-sensing
cylinder corresponding portion. Accordingly, it is necessary to
lessen influences of temperature of other portions than the
temperature-sensing cylinder corresponding portion.
[0106] Therefore, according to the embodiment, the volumetric ratio
of the temperature-sensing cylinder corresponding portion is
ensured, which amounts to a predetermined magnitude or more.
Further, an insulating material may be attached to the other
portion than the temperature-sensing cylinder corresponding portion
to prevent heating due to an ambient temperature.
[0107] While the larger a difference between a refrigerant
temperature and an ambient temperature, the more conspicuous
influences of the volumetric ratio, it is necessary to decrease a
change in control pressure in order to avoid an abnormally high
pressure because control pressure becomes also high and a margin
for an upper limit pressure of the cycle is small In the case where
a gas cooler outlet temperature is high.
[0108] While it is desired that the variation in pressure be small,
it is necessary to make the variation equal to or less than about
0.5 MPa in order to make the same in the order of dispersion in a
pressure sensor or the like, and assuming that a maximum
temperature of a gas cooler outlet refrigerant is 60.degree. C. and
temperature in the engine room is 80 to 100.degree. C., the outer
wall portion above the diaphragm rises 5 to 6.degree. C. in
temperature even in the case where an insulating material is
attached thereto. Accordingly, in order to rake the variation equal
to or less than about 0.5 MPa, it suffices to ensure a volume of at
least 50% at the minimum for the volumetric ratio of the
temperature-sensing cylinder corresponding portion as seen from
FIG. 19.
[0109] In the case where a gas cooler outlet refrigerant
temperature is low, the control pressure is low so that there is a
margin for an upper limit pressure in the cycle. Since a
temperature difference between the refrigerant temperature and an
ambient temperature becomes large, the influence of the ambient
temperature becomes large.
[0110] FIG. 20 shows effects of temperature of the portion Q (other
than the temperature-sensing cylinder corresponding portion) due to
an ambient temperature in the case where a refrigerant temperature
is 40.degree. C. 50.degree. C., 60.degree. C., 80.degree. C., and
100.degree. C. are shown for temperature of the portion Q. A target
control pressure is attained when temperature of the portion except
the temperature-sensing portion is 40.degree. C. While for example,
when a refrigerant temperature is 40.degree. C., temperature of the
outer wall rises about 10.degree. C. to attain 50.degree. C. in the
case where a temperature difference between the refrigerant
temperature and an ambient temperature is increased to 60.degree.
C., it is found desirable to make the volumetric ratio of the
temperature-sensing cylinder equal to or more than 60% in order to
make variation in high pressure equal to 0.5 MPa.
[0111] Also, it can be seen from FIG. 20 that when the volumetric
ratio is made equal to or more than 70%, variation in control
pressure can be made equal to about 0.5 MPa even when an insulating
material is omitted for the portion except the temperature-sensing
cylinder corresponding portion.
[0112] Accordingly, the larger the ratio to the whole
temperature-sensing portion is made by increasing a volume (the
lower half of the enclosed space above the diaphragm and the
enclosed space below the diaphragm) of the temperature-sensing
cylinder corresponding portion, the smaller the variation in
operating value, due to an ambient temperature, can be made.
According to the embodiment, the volumetric ratio of the
temperature-sensing cylinder corresponding portion to the enclosed
space is made equal to or more than 60%. In addition, the
volumetric ratio in the embodiment is represented by the following
formula (Vu.times.0.5+Vb)/(Vu-Vb)>0.6 where Vu indicates a
volume of the enclosed space above the diaphragm and Vb indicates a
volume of the enclosed space below the diaphragm.
[0113] Typically, the expansion valve 3G, according to the seventh
embodiment, used in a refrigerating cycle with no internal heat
exchanger, illustrated with reference to FIG. 9 is formed such that
the volumetric sum of 1/2 of the enclosed space A (including the
charge pipe 35b) and the cavity 31d amounts to at least 60% of the
volumetric sum of the enclosed space A (including the charge pipe
35b) and the cavity 31. In addition, while the embodiment is
directed to an expansion valve used in a refrigerating cycle with
no internal heat exchanger, it may be applied to a refrigerating
cycle with an internal heat exchanger.
[0114] Further, the expansion valve, according to the sixth,
eighth, and ninth embodiments illustrated with reference to FIGS.
8, 10, 11 can also be formed such that the volumetric sum of 1/2 of
the enclosed space A (including the charge pipe 35b) and the cavity
31 amounts to at least 60% of the volumetric sum of the enclosed
space A (including the charge pipe 35b) and the cavity 31d.
[0115] Further, as shown in FIG. 21, variation in control pressure
can be suppressed in the expansion valve 31, according to the ninth
embodiment, shown in FIG. 11 by providing a lid 39, which covers
the cuter wall of the temperature-sensing portion and the charge
pipe 35b, and forming an air layer between the outer wall of the
temperature-sensing portion and an outside air to thermally
insulate a portion except the temperature-sensing cylinder
corresponding portion of the temperature-sensing portion.
[0116] As described above, according to the invention, as a
refrigerant temperature is transmitted to an interior of the
enclosed space A through the clearance B, it is possible to omit a
casing or a capillary tube and a temperature-sensing cylinder,
which are used in the related art, and to achieve miniaturization
and lightening of an expansion valve and reduction in cost. By
composing gases, which are charged in an enclosed space, of mixed
gas of a refrigerant and gases which are lower in the coefficient
of thermal expansion than the refrigerant, it is possible to omit
an adjustment spring or the like and to further simplify an
expansion valve. Also, by prescribing that the density, at which a
refrigerant is charged into a temperature-sensing body, it is
possible to optimize control characteristics when an internal heat
exchanger is used, and to decrease pressure-resistance of the
temperature-sensing body. Further, as a ratio of a
temperature-sensing body to a whole temperature-sensing cylinder
corresponding portion is prescribed, it is possible to lessen the
partial influences of temperature of the temperature-sensing
body.
* * * * *