U.S. patent application number 11/798532 was filed with the patent office on 2007-11-22 for mounting structure of expansion valve.
This patent application is currently assigned to TGK CO., LTD.. Invention is credited to Hisatoshi Hirota.
Application Number | 20070266731 11/798532 |
Document ID | / |
Family ID | 38321713 |
Filed Date | 2007-11-22 |
United States Patent
Application |
20070266731 |
Kind Code |
A1 |
Hirota; Hisatoshi |
November 22, 2007 |
Mounting structure of expansion valve
Abstract
To reduce the number of refrigerant external leak-prone spots,
in a portion where an expansion valve is mounted. A casing is
joined to a refrigerant outlet of an evaporator, and a low-pressure
pipe extending to a compressor is connected to the casing by a pipe
clamp. An expansion valve is disposed within the casing. Within the
casing, an inlet port of the expansion valve and a high-pressure
pipe are connected to each other, and an outlet port of the
expansion valve and an inlet pipe of an evaporator are connected to
each other. This limits the portions of the expansion valve which
can cause refrigerant external leakage to portions connected by the
pipe clamp.
Inventors: |
Hirota; Hisatoshi; (Tokyo,
JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
TGK CO., LTD.
Tokyo
JP
|
Family ID: |
38321713 |
Appl. No.: |
11/798532 |
Filed: |
May 15, 2007 |
Current U.S.
Class: |
62/527 ;
62/513 |
Current CPC
Class: |
F25B 41/31 20210101;
F25B 2341/0683 20130101 |
Class at
Publication: |
62/527 ;
62/513 |
International
Class: |
F25B 41/00 20060101
F25B041/00; F25B 41/06 20060101 F25B041/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2006 |
JP |
2006-139007 |
Aug 3, 2006 |
JP |
2006-212449 |
Oct 11, 2006 |
JP |
2006-277265 |
Claims
1. A mounting structure of an expansion valve in a refrigeration
cycle, wherein the expansion valve is accommodated in a
low-pressure return pipe extending between an outlet of an
evaporator and an inlet of a compressor, and connection between an
inlet port of the expansion valve and a high-pressure pipe, and
connection between an outlet port of the expansion valve and a
low-pressure pipe to an inlet of the evaporator are made within the
low-pressure return pipe.
2. The mounting structure of an expansion valve according to claim
1, wherein the evaporator is formed, by joining, integrally with a
casing extending from the outlet of the evaporator and
accommodating the expansion valve, and an inlet pipe disposed at
the inlet of the evaporator and having a portion for connection
with the outlet port of the expansion valve, the portion being open
into the casing, and the low-pressure return pipe is connected to
an open end of the casing.
3. The mounting structure of an expansion valve according to claim
2, wherein the casing is joined to the evaporator in a manner
enclosing the inlet and the outlet of the evaporator.
4. The mounting structure of an expansion valve according to claim
2, wherein the casing is joined to the evaporator in a manner
enclosing the outlet of the evaporator, and the inlet pipe having
one end thereof joined to the inlet of the evaporator, and another
end thereof positioned within the casing in a manner extending
through the casing, and the inlet pipe and the casing are
hermetically joined to each other.
5. The mounting structure of an expansion valve according to claim
2, wherein the low-pressure return pipe is connected to the open
end of the casing via a joint part joined to a foremost end of the
low-pressure return pipe, and the high-pressure pipe extends
through the joint part, the high-pressure pipe and the joint part
being hermetically joined to each other.
6. The mounting structure of an expansion valve according to claim
2, wherein the low-pressure return pipe and the high-pressure pipe
are formed as a double pipe in which the high-pressure pipe is
concentrically disposed within the low-pressure return pipe.
7. The mounting structure of an expansion valve according to claim
1, wherein a connecting part is connected to the evaporator in a
manner enclosing the inlet and the outlet of the evaporator, and an
inlet pipe is connected to the inlet of the evaporator, wherein a
casing to which a joint part is joined in a manner extending in a
direction orthogonal to the inlet pipe is connected to the
connecting part, the low-pressure return pipe being connected to
the joint part, and wherein the expansion valve having the inlet
port and the outlet port thereof disposed in respective directions
orthogonal to each other is disposed within the casing.
8. The mounting structure of an expansion valve according to claim
1, wherein a casing accommodating the expansion valve is disposed
in an intermediate portion of the low-pressure return pipe, and the
high-pressure pipe concentrically disposed in the low-pressure
return pipe at a location closer to the compressor than to the
casing is connected to the inlet port of the expansion valve.
9. The mounting structure of an expansion valve according to claim
1, wherein a casing accommodating the expansion valve is disposed
in an intermediate portion of the low-pressure return pipe, and an
evaporator inlet pipe concentrically disposed within the
low-pressure return pipe at a location closer to the evaporator
than to the casing is connected to the outlet port of the expansion
valve.
10. The mounting structure of an expansion valve according to claim
9, wherein the portion of the low-pressure return pipe closer to
the evaporator and the casing are joined to each other.
11. The mounting structure of an expansion valve according to claim
1, wherein a casing accommodating the expansion valve is disposed
in an intermediate portion of the low-pressure return pipe, and the
high-pressure pipe is connected to the inlet port of the expansion
valve in a manner extending through the casing.
12. The mounting structure of an expansion valve according to claim
1, wherein a casing accommodating the expansion valve is disposed
in an intermediate portion of the low-pressure return pipe, and an
evaporator inlet pipe is connected to the outlet port of the
expansion valve in a manner extending through the casing.
13. The mounting structure of an expansion valve according to claim
2, wherein the casing is formed such that a shape of the casing at
a location where the expansion valve is mounted is adapted to an
outer shape of the expansion valve.
14. The mounting structure of an expansion valve according to claim
1, wherein the evaporator is formed, by joining, integrally with a
hollow cylindrical connecting part extending from the evaporator in
a manner enclosing the inlet and the outlet of the evaporator and
an evaporator inlet pipe, and a hollow cylindrical casing
accommodating the expansion valve and having a peripheral surface
thereof connected with the low-pressure return pipe and one end
thereof closed is connected to the connecting part.
15. The mounting structure of an expansion valve according to claim
14, wherein the casing and the low-pressure return pipe are
connected to each other by welding.
16. The mounting structure of an expansion valve according to claim
14, wherein the connection between the casing and the low-pressure
return pipe is a connection effected by sealing using an O ring and
swaging.
17. The mounting structure of an expansion valve according to claim
14, wherein the high-pressure pipe is concentrically disposed
within the low-pressure return pipe, or is connected to the casing
in a direction orthogonal to the low-pressure return pipe.
18. The mounting structure of an expansion valve according to claim
17, wherein a portion of the casing on a side opposite from a side
where the high-pressure pipe is disposed is deformed inward to
thereby press the expansion valve connected to the high-pressure
pipe via a sealing portion, toward the high-pressure pipe.
19. The mounting structure of an expansion valve according to claim
17, wherein the connection between the high-pressure pipe and the
casing in the direction orthogonal to the low-pressure return pipe
is a connection effected by welding.
20. The mounting structure of an expansion valve according to claim
17, wherein the connection between the high-pressure pipe and the
casing in the direction orthogonal to the low-pressure return pipe
is a connection effected by sealing using an O ring and
swaging.
21. The mounting structure of an expansion valve according to claim
18, wherein a portion of the casing where the high-pressure pipe is
welded and its vicinity are formed to have a flat surface so as to
make flat the sealing portion of an inner surface of the casing and
the expansion valve.
22. The mounting structure of an expansion valve according to claim
14, wherein the evaporator has the inlet and the outlet thereof
arranged in parallel, and the outlet port of the expansion valve is
formed in a manner eccentric toward the inlet of the evaporator
with respect to a center of the expansion valve.
23. The mounting structure of an expansion valve according to claim
14, wherein the evaporator has the inlet and the outlet thereof
concentrically disposed, and the expansion valve is disposed in the
casing such that the outlet port of the expansion valve and the
inlet of the evaporator are on an identical axis.
24. The mounting structure of an expansion valve according to claim
14, wherein a soundproofing member is disposed on at least one of
an inner inside and an outer outside of the casing, for insulating
noise generated by the expansion valve.
25. The mounting structure of an expansion valve according to claim
24, wherein the soundproofing member is disposed on the inner side
of the casing in a manner covering the expansion valve.
26. The mounting structure of an expansion valve according to claim
1, wherein the expansion valve is a thermostatic expansion valve.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS, IF ANY
[0001] This application claims priorities of Japanese Application
No. 2006-139007 filed on May 18, 2006, No. 2006-212449 filed on
Aug. 3, 2006, and No. 2006-277265 filed on Oct. 11, 2006, all
entitled "Mounting Structure of Expansion Valve".
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] The present invention relates to a mounting structure of an
expansion valve, and more particularly to a mounting structure of
an expansion valve configured to expand high-temperature,
high-pressure refrigerant supplied from a condenser and deliver
low-temperature, low-pressure refrigerant to an evaporator, in a
refrigeration cycle of an automotive air conditioner.
[0004] (2) Description of the Related Art
[0005] In general, a refrigeration cycle of an automotive air
conditioner comprises a compressor that compresses refrigerant
circulating through the refrigeration cycle, a condenser that
condenses the compressed refrigerant, a receiver that temporarily
stores the refrigerant circulating through the refrigeration cycle
and separates the condensed refrigerant into gas and liquid, an
expansion valve that throttles and expands the liquid refrigerant
obtained by gas/liquid separation, and an evaporator that
evaporates the refrigerant expanded by the expansion valve. The
expansion valve is implemented e.g. by a thermostatic expansion
valve configured to sense the temperature and pressure of
refrigerant at the outlet of the evaporator and control the flow
rate of refrigerant delivered to the evaporator (see e.g. Japanese
Unexamined Patent Publication No. 2002-115938).
[0006] This thermostatic expansion valve comprises a block
including a valve section, and a power element that senses the
temperature and pressure of refrigerant returned from the
evaporator and controls the valve section. The block has a side
thereof formed with a connection hole for connection to a
high-pressure pipe through which high-temperature, high-pressure
refrigerant is supplied from the receiver, a connection hole for
connection to a low-pressure pipe through which low-temperature,
low-pressure refrigerant having been expanded in the expansion
valve is delivered to the evaporator, a connection hole for
connection to a return pipe extending from an evaporator outlet,
and a connection hole for connection to a pipe through which
refrigerant having passed through the expansion valve is returned
to the compressor. The block serves as a joint of the pipes.
Further, the block has one longitudinal end face thereof formed
with a screw hole for connecting the power element to the block,
and the other longitudinal end face formed with a screw hole in
which is screwed an adjustment screw for adjusting a set value of
the valve section from outside. Each of these holes is provided
with a sealing member for holding the block hermetic in a state
where the pipes are inserted and the power element and the
adjustment screw are screwed therein.
[0007] By the way, currently, automotive air conditioners generally
use chlorofluorocarbon (HFC-134a) as refrigerant. However,
chlorofluorocarbon has a high global warming potential, and hence
it is said that when chlorofluorocarbon leaks out into the
atmosphere, it has a serious effect on global warming. As a
countermeasure against the global warming, there have been proposed
a method of replacing chlorofluorocarbon by a refrigerant having a
low global warming potential, and a method of ensuring prevention
of leakage of chlorofluorocarbon and collecting the same when the
use thereof is no longer required.
[0008] Portions in the refrigeration cycle, from which
chlorofluorocarbon is prone to leak out, are e.g. connecting
portions of pipes, and sealing members disposed at the portions are
responsible for the leakage. In particular, joints of the
high-pressure pipe extending from a compressor outlet to an
expansion valve inlet are more prone to cause refrigerant external
leakage than joints of the low-pressure pipe.
[0009] However, in the expansion valve, such as the conventional
thermostatic expansion valve, which includes the block containing
the valve section, and the power element connected to the block,
the body also serves as joints, and hence even when limited to pipe
connections alone, the block as many as four connections which
require provision of sealing members. In addition, there are a
portion where the power element is connected and a portion where
the adjustment screw is provided, and hence the expansion valve has
six connections, in total, which can cause refrigerant external
leakage. Six is a large number for this problem.
SUMMARY OF THE INVENTION
[0010] The present invention has been made in view of these points,
and an object thereof is to provide a mounting structure of an
expansion valve having a reduced number of refrigerant external
leak-prone spots.
[0011] To solve the above problem, the present invention provides a
mounting structure of an expansion valve in a refrigeration cycle,
wherein the expansion valve is accommodated in a low-pressure
return pipe extending between an outlet of an evaporator and an
inlet of a compressor, and connection between an inlet port of the
expansion valve and a high-pressure pipe, and connection between an
outlet port of the expansion valve and a low-pressure pipe to an
inlet of the evaporator are made within the low-pressure return
pipe.
[0012] The above and other objects, features and advantages of the
present invention will become apparent from the following
description when taken in conjunction with the accompanying
drawings which illustrate preferred embodiments of the present
invention by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a cross-sectional view showing a mounting
structure of an expansion valve according to a first
embodiment.
[0014] FIG. 2 is a cross-sectional view taken on line A-A of FIG.
1.
[0015] FIG. 3 is a cross-sectional view useful in explaining the
operation of the expansion valve according to the first
embodiment.
[0016] FIG. 4 is a cross-sectional view showing a mounting
structure of an expansion valve according to a second
embodiment.
[0017] FIG. 5 is a cross-sectional view taken on line B-B of FIG.
4.
[0018] FIG. 6 is a cross-sectional view showing a mounting
structure of an expansion valve according to a third
embodiment.
[0019] FIG. 7 is a cross-sectional view showing a mounting
structure of an expansion valve according to a fourth
embodiment.
[0020] FIG. 8 is a cross-sectional view taken on line C-C of FIG.
7.
[0021] FIG. 9 is a cross-sectional view showing a mounting
structure of an expansion valve according to a fifth
embodiment.
[0022] FIG. 10 is a cross-sectional view taken on line D-D of FIG.
9.
[0023] FIG. 11 is a cross-sectional view showing a mounting
structure of an expansion valve according to a sixth
embodiment.
[0024] FIG. 12 is a cross-sectional view taken on line E-E of FIG.
11.
[0025] FIG. 13 is a cross-sectional view showing a mounting
structure of an expansion valve according to a seventh
embodiment.
[0026] FIG. 14 is a cross-sectional view showing a mounting
structure of an expansion valve according to a eighth
embodiment.
[0027] FIG. 15A is a cross-sectional view showing a mounting
structure of an expansion valve according to a ninth
embodiment.
[0028] FIG. 15B is a cross-sectional view taken on line F-F of FIG.
15A.
[0029] FIG. 16A is a cross-sectional view taken in a plane
containing the center line of the high-pressure pipe and that of
the low-pressure pipe, regarding a mounting structure of an
expansion valve according to a tenth embodiment.
[0030] FIG. 16B is a cross-sectional view taken on line G-G of FIG.
16A.
[0031] FIG. 17A is a cross-sectional view showing a mounting
structure of an expansion valve according to an eleventh
embodiment.
[0032] FIG. 17B is a cross-sectional view taken on line H-H of FIG.
17A.
[0033] FIG. 18 is a cross-sectional view showing a mounting
structure of an expansion valve according to a twelfth
embodiment.
[0034] FIG. 19 is a cross-sectional view showing a mounting
structure of an expansion valve according to a thirteenth
embodiment.
[0035] FIG. 20 is an exploded perspective view showing a mounting
structure of an expansion valve according to a fourteenth
embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings.
[0037] FIG. 1 is a cross-sectional view showing a mounting
structure of an expansion valve according to a first embodiment of
the present invention. FIG. 2 is a cross-sectional view taken on
line A-A of FIG. 1. FIG. 3 is a cross-sectional view useful in
explaining the operation of the expansion valve according to the
first embodiment.
[0038] The evaporator 1 is formed by laminating a plurality of
aluminum plates, and has a header portion thereof formed with a
refrigerant inlet 2 for introducing refrigerant and a refrigerant
outlet 3 for delivering refrigerant. An inlet pipe 5 is integrally
formed with the refrigerant inlet 2 by pressing an end plate 4 as a
component of the evaporator 1. A hollow cylindrical casing 6
forming a low-pressure return pipe extending from the evaporator 1
is joined to the end plate 4 in a manner enclosing the opening of
the inlet pipe 5 and that of the refrigerant outlet 3. The
evaporator 1 is formed by simultaneously welding the laminated
plates and the end plate 4 by an NB (Noncorrosive Flux Brazing)
method in which brazing is performed using fluoride-based flux
within a nitrogen atmosphere in a furnace, and at this time the
casing 6 is also welded together, whereby the evaporator 1 and the
casing 6 are formed integral with each other.
[0039] The casing 6 has an expansion valve 7 mounted therein. The
expansion valve 7 has a body 10 integrally formed with an inlet
port 8 for introducing high-pressure refrigerant and an outlet port
9 for delivering low-pressure refrigerant. The body 10 has a valve
hole formed therethrough for communication between the inlet port 8
and the outlet port 9, and a valve element 11 is disposed in the
body 10 for opening and closing the valve hole, in a state urged in
the valve-closing direction by a spring 12 from a low pressure
side. The spring 12 is received in an adjustment member 13
press-fitted into a lower end opening, as viewed in FIG. 1, of the
body 10. The load of the spring 12 is adjusted by the press-fitted
amount of the adjustment member 13 press-fitted into the body 10,
whereby the set value of the expansion valve 7 is adjusted. The
valve element 11 is integrally formed with a shaft 14 supported by
the body 10 in a manner movable in the valve opening/closing
direction, and a V ring 15 is fitted on the shaft 14 so as to
prevent the high-pressure refrigerant introduced into the inlet
port 8 from leaking into the casing 6 through a clearance between
the body 10 and the shaft 14.
[0040] The body 10 has a power element 16 screwed into an upper end
thereof, as viewed in FIG. 1. The power element 16 comprises an
upper housing 17 and a lower housing 18, each made of thick metal,
a diaphragm 19 made of a flexible thin metal plate and disposed in
a manner partitioning a space enclosed by the upper and lower
housings 17 and 18, and a center disk 20. The space enclosed by the
upper housing 17 and the diaphragm 19 forms a temperature-sensing
chamber, which is filled with refrigerant gas. The center disk 20
has an upper surface thereof held in contact with the lower surface
of the diaphragm 19, and a lower surface thereof held in contact
with an end surface of the shaft 14 protruding from the body 10, so
as to transmit the displacement of the diaphragm 19 to the valve
element 11. The lower housing 18 has a gas-passing hole 21 formed
so as to introduce refrigerant passing through the casing 6 into
space below the diaphragm 19. The amount of refrigerant to be
introduced is adjusted by changing the size or number of the
gas-passing hole 21. Further, a heat-insulating cover 22 made of
resin or rubber is attached to the power element 16 in a manner
covering the same.
[0041] The outlet port 9 of the expansion valve 7 is fitted on the
inlet pipe 5 of the evaporator 1 and is sealed by an O ring 23. The
inlet port 8 of the expansion valve 7 is fitted in a high-pressure
pipe 24 extending from a receiver, and is sealed by an O ring 25.
The casing 6 is connected to a low-pressure pipe 26 extending to a
compressor. In the illustrated example 1, the low-pressure pipe 26
has a joint part 27 welded to an end portion thereof (as indicated
by black triangles), and the joint part 27 is connected to the
casing 6 by a pipe clamp 28 and is sealed by two O rings 29 so as
to minimize refrigerant external leakage. The low-pressure pipe 26
and the high-pressure pipe 24 are formed by a concentric double
pipe such that the high-pressure pipe 24 is disposed within the
low-pressure pipe 26.
[0042] The expansion valve 7 housed in the casing 6 is positioned
in the center of the casing 6, and therefore, as shown in FIG. 2,
the body 10 and the heat-insulating cover 22 have respective outer
contours formed along the inner shape of the casing 6.
[0043] Now, the expansion valve 7 is mounted in the casing 6
functioning as a low-pressure return pipe from the evaporator 1, as
follows: Since the evaporator 1 and the casing 6 are integrally
welded such that the inlet pipe 5 of the evaporator 1 protrudes
into the casing 6, first, the O ring 23 is fitted on the inlet pipe
5, and then the expansion valve 7 is pushed into the casing 6 until
the outlet port 9 is fitted on the inlet pipe 5. The O ring 25 is
fitted on the inlet port 8 of the expansion valve 7 in advance, or
at this time. Next, the inlet port 8 is positioned such that it can
be fitted in the high-pressure pipe 24, and the joint part 27
having the O rings 29 fitted beforehand in respective grooves
formed by bending the end portion of the joint part 27 is pushed
into the casing 6. Finally, a connecting portion of the casing 6
and that of the joint part 27 are connected by the pipe clamp
28.
[0044] Thus, the expansion valve 7 is mounted in the casing 6, with
the inlet port 8 connected to the high-pressure pipe 24, and the
outlet port 9 connected to the inlet pipe 5 of the evaporator 1.
More specifically, the expansion valve 7 is accommodated in the
low-pressure return pipe from the evaporator 1, together with the
high-pressure pipe 24 and the connecting portion thereof, and hence
connecting portions from which refrigerant can leak out are limited
to only the connecting portions connected by the pipe clamp 28.
Since the high-pressure pipe 24 and the connecting portion thereof
are accommodated in the casing 6, even if a minute amount of
high-pressure refrigerant leaks via the O ring 25, the refrigerant
remains in the low-pressure return pipe without leaking out into
the atmosphere.
[0045] Next, a description will be given of the operation of the
expansion valve 7. When an automotive air conditioner is in
stoppage, gas filling the temperature-sensing chamber of the power
element 16 is condensed, so that the pressure of the gas is low.
Therefore, as shown in FIG. 1, the diaphragm 19 is displaced inward
(upward, as viewed in FIG. 1), and the displacement is transmitted
to the valve element 11 via the shaft 14, whereby the expansion
valve 7 is placed in the fully closed state.
[0046] When the automotive air conditioner is started in this
state, refrigerant is drawn by the compressor, and hence pressure
within the low-pressure return pipe drops. The power element 16
senses this, so that the diaphragm 19 is displaced outward to lift
the valve element 11. On the other hand, refrigerant compressed by
the compressor is condensed by a condenser, and liquid refrigerant
obtained by gas/liquid separation in the receiver is supplied to
the inlet port 8 of the expansion valve 7 through the high-pressure
pipe 24. It should be noted that arrows appearing in the figures
indicate respective directions of refrigerant flow. The
high-temperature, high-pressure liquid refrigerant is expanded
while passing through the expansion valve 7 and flows out as
low-temperature, low-pressure gas-liquid mixture refrigerant from
the outlet port 9. The refrigerant is supplied to the evaporator 1
through the inlet pipe 5 and the refrigerant inlet 2, and is
evaporated in the evaporator 1 to flow out from the refrigerant
outlet 3. The refrigerant having returned from the evaporator 1
returns to the compressor via the casing 6 and the low-pressure
pipe 26.
[0047] The space enclosed by the diaphragm 19 of the power element
16 and the lower housing 18 of the same communicates with the
inside of the casing 6 via the gas-passing hole 21, so that while
refrigerant having returned from the evaporator 1 is passing
through the casing 6, some of the refrigerant is introduced into
the space within the power element 16, and the temperature of the
introduced refrigerant is detected by the power element 16. In the
early stage of the start of the automotive air conditioner, the
temperature of the refrigerant returning from the evaporator 1 is
high due to heat exchange with high-temperature air in the
compartment, and the power element 16 senses the temperature of the
refrigerant, so that the pressure within the temperature-sensing
chamber becomes high. This causes, as shown in FIG. 3, the
diaphragm 19 to be displaced in the valve-opening direction until
the center disk 20 in contact therewith is brought into abutment
with a shoulder of the lower housing 18, and this displacement is
transmitted to the valve element 11 via the shaft 11, whereby the
expansion valve 7 is fully opened.
[0048] As the temperature of refrigerant from the evaporator 1
becomes lower, the pressure within the temperature-sensing chamber
also becomes lower. Accordingly, the diaphragm 19 is displaced
upward, as viewed in FIG. 3, whereby the expansion valve 7 moves in
the valve-closing direction to control the flow rate of refrigerant
passing therethrough. At this time, the expansion valve 7 operates
to detect the temperature of refrigerant at the outlet of the
evaporator 1, and controls the flow rate of refrigerant supplied to
the evaporator 1 such that the refrigerant maintains a
predetermined degree of superheat. As a consequence, refrigerant in
a superheated state is always returned to the compressor, which
enables the compressor to perform an efficient operation.
[0049] It should be noted that since the power element 16 is
disposed in the low-pressure return pipe from the evaporator 1 such
that the temperature of refrigerant can be detected by the entire
power element 16, the power element 16 would have a very short
temperature-sensing time constant due to its structure. If the
temperature-sensing time constant is short, the response to a
change in the temperature of refrigerant becomes so sensitive as to
perform an excessive feedback correction on the operation of the
valve section, which can result in a periodic pressure variation
(hunting). To eliminate this inconvenience, the heat-insulating
cover 22 is provided to block the transfer of heat to the upper
housing 17 to thereby increase the temperature-sensing time
constant.
[0050] FIG. 4 is a cross-sectional view showing a mounting
structure of an expansion valve according to a second embodiment of
the present invention, and FIG. 5 is a cross-sectional view taken
on line B-B of FIG. 5. Component elements appearing in FIGS. 4 and
5, which have functions identical to or equivalent to those of the
component elements appearing in FIG. 1, are designated by identical
reference numerals, and detailed description thereof is
omitted.
[0051] The mounting structure of the expansion valve according to
the second embodiment is distinguished from the mounting structure
of the expansion valve according to the first embodiment, in that
the double pipe extends in a direction substantially orthogonal to
a direction in which the refrigerant inlet 2 and the refrigerant
outlet 3 of the evaporator 1 extend.
[0052] In many cases, the evaporator 1 is installed in a vehicle
compartment such that a header portion having the refrigerant inlet
2 and the refrigerant outlet 3 is directed transversely to the
vehicle. For this reason, the high-pressure pipe 24 and the
low-pressure pipe 26 extending from an engine room into the
compartment are required to be bent at right angles at the
expansion valve 7 and the refrigerant outlet 3. To bend pipes at
right angles necessitates space therefor, and hence, in the present
embodiment, the direction of inflow of refrigerant and that of
outflow of the same are made at right angles at a location where
the expansion valve 7 is mounted.
[0053] The evaporator 1 is integrally formed with the inlet pipe 5
and a connecting part 6a by furnace brazing. The casing 6 is
connected to the connecting part 6a by the pipe clamp 28, and the
joint part 27 is welded to an upper portion, as viewed in FIG. 4,
of the pipe clamp 28. The joint part 27 is connected to the
low-pressure pipe 26 by the pipe clamp 28. In the present
embodiment, connecting portions of the joint part 27 and the
low-pressure pipe 26 connected by the pipe clamp 28 are sealed by
an O ring 29 and a backup ring 29a.
[0054] The expansion valve 7 is mounted in the casing 6 and the
joint part 27 having the openings facing in the respective
directions orthogonal to each other, as described above. The body
10 of the expansion valve 7 has the inlet port 8 and the outlet
port 9 formed in a manner facing in the respective directions
orthogonal to each other. The body 10 has an outer shape extended
in respective three directions up to the vicinity of the inner
surface of the casing 6, as shown in FIG. 5, which makes it easy to
position the expansion valve 7, when inserting the same into the
casing 6 and connecting the outlet port 9 to the inlet pipe 5.
[0055] In the present embodiment, the low-pressure return pipe from
the evaporator is required to be formed into an L shape, and hence
junctures which can be responsible for external leakage of
refrigerant are two connections, i.e. a juncture between the
connecting part 6a and a juncture between the joint part 27 and the
low-pressure pipe 26.
[0056] FIG. 6 is a cross-sectional view showing a mounting
structure of an expansion valve according to a third embodiment of
the present invention. Component elements appearing in FIG. 6,
which have functions identical to or equivalent to those of the
component elements appearing in FIG. 1, are designated by identical
reference numerals, and detailed description thereof is
omitted.
[0057] Similarly to the mounting structure of the expansion valve
according to the second embodiment, the mounting structure of the
expansion valve according to the third embodiment has an L-shaped
structure in which the double pipe extends orthogonally to the
direction in which the refrigerant inlet 2 and the refrigerant
outlet 3 of the evaporator 1 extend. However, the mounting
structure of the expansion valve according to the third embodiment
is distinguished from the mounting structure of the expansion valve
according to the second embodiment in that it has only one
connection from which refrigerant can leak out.
[0058] More specifically, in the present embodiment, the evaporator
1, the inlet pipe 5, and the casing 6 are integrally formed by
furnace brazing. At this time, the casing 6 and the inlet pipe 5 as
well has through parts thereof hermetically joined. Further, the
inlet pipe 5 and the casing 6 are independently joined to the
refrigerant inlet 2 and the refrigerant outlet 3, respectively,
such that the free end of the inlet pipe 5 bent at right angles
extends into the casing 6. The casing 6 is connected to the
low-pressure pipe 26 by fixing a backup ring 29b to an end face of
the casing 6 by the pipe clamp 28 with the low-pressure pipe 26
inserted into the casing 6, and the O ring 29 prevents refrigerant
from leaking out from the low-pressure return pipe. This reduces
the number of junctures of the low-pressure return pipe from the
evaporator 1 to one.
[0059] It should be noted that the expansion valve 7 employed in
the present embodiment is different in the structure of the power
element 16 from the expansion valve 7 described by way of example
in the first and second embodiments. More specifically, the power
element 16 comprises a temperature-sensing chamber formed by
sandwiching the outer peripheral edge of the diaphragm 19 between
the upper housing 17 and the lower housing 18 and welding them, and
a belleville spring 30 provided within the temperature-sensing
chamber. The belleville spring 30 is configured to assist the force
of gas filled in the temperature-sensing chamber, for pushing the
diaphragm 19 outward according to a sensed temperature. The
belleville spring 30 acts to cause a pseudo-increase in the
pressure of the gas. In the valve section, a ball-shaped valve
element 11 is used, and the valve element 11 is joined to one end
of the shaft 14 by spot welding. The shaft 14 has a pipe 31 fitted
on the other end thereof, which is supported by the body 10 in a
manner slidable along the axis of the shaft 14. The shaft 14 and
the pipe 31 have respective end faces thereof held in contact with
the diaphragm 19 of the power element 16. The V ring 15 is fitted
on a reduced-diameter portion formed by fitting the pipe 31 on the
shaft 14, for preventing high-pressure refrigerant from leaking
into the low-pressure return pipe.
[0060] FIG. 7 is a cross-sectional view showing a mounting
structure of an expansion valve according to a fourth embodiment of
the present invention, and FIG. 8 is a cross-sectional view taken
on line C-C of FIG. 7. Component elements appearing in FIGS. 7 and
8, which have functions identical to or equivalent to those of the
component elements appearing in FIG. 1, are designated by identical
reference numerals, and detailed description thereof is
omitted.
[0061] The mounting structure of the expansion valve according to
the fourth embodiment is distinguished from the mounting structure
of the expansion valve according to the first embodiment, in that
the high-pressure pipe 24 and the low-pressure pipe 26 extending
toward a compressor from the expansion valve 7 are not formed by a
double pipe.
[0062] More specifically, in this mounting structure, the
high-pressure pipe 24 and the low-pressure pipe 26 have respective
end portions thereof connected to the joint part 27 through an end
treatment by welding. The joint part 27 has two hollow cylindrical
parts 27a and 27b integrally formed by pressing. The end face of
the hollow cylindrical part 27a and a peripheral surface of the
high-pressure pipe 24 are welded in a state where the high-pressure
pipe 24 is inserted through the hollow cylindrical part 27a, and
the end face of the hollow cylindrical part 27b and that of the
low-pressure pipe 26 are welded in a state where the low-pressure
pipe 26 is inserted into the hollow cylindrical part 27b, whereby
joining portions of the joint part 27 to the high-pressure pipe 24
and the low-pressure pipe 26 are sealed. Further, the joint part 27
is connected to the casing 6 by the pipe clamp 28, and a juncture
therebetween is sealed by the O ring 29. As shown in FIG. 8, the
casing 6 is formed to have an oval cross section so as to
facilitate guiding insertion of the expansion valve 7 and
positioning performed for connection between the outlet port 9 of
the expansion valve 7 and the inlet pipe 5 of the evaporator 5. In
the structure described above, the number of junctures of the
low-pressure return pipe extending from the evaporator 1 is reduced
to one.
[0063] It should be noted that the expansion valve 7 employed in
the present embodiment is of a different type from the expansion
valve 7 described by way of example in the first and second
embodiments. More specifically, the expansion valve 7 employed in
the present embodiment has a retainer 32 disposed in the
temperature-sensing chamber formed by the upper housing 17 and the
diaphragm 19 of the power element 16, and an activated carbon 33 is
filled in a space between the retainer 32 and the upper housing 17.
The activated carbon 33 is provided to convert temperature into
pressure utilizing its adsorption characteristic. The activated
carbon 33 determines pressure within the temperature-sensing
chamber in accordance with a change in the detected temperature.
Further, the activated carbon 33 has a characteristic that due to
its low thermal conductivity, it takes much time before the
pressure changes in response to a change in temperature. This makes
it possible to dispense with the heat-insulating cover 22 for
blocking the transfer of heat to the upper housing 17 of the power
element 16.
[0064] FIG. 9 is a cross-sectional view showing a mounting
structure of an expansion valve according to a fifth embodiment of
the present invention, and FIG. 10 is a cross-sectional view taken
on line D-D of FIG. 9. Component elements appearing in FIGS. 9 and
10, which have functions identical to or equivalent to those of the
component elements appearing in FIGS. 1 and 6, are designated by
identical reference numerals, and detailed description thereof is
omitted.
[0065] The mounting structure of the expansion valve according to
the fifth embodiment is distinguished from the mounting structure
of the expansion valve according to each of the first to fourth
embodiments, in which the expansion valve 7 is mounted in the
casing 6 connected, as the low-pressure return pipe, to the
evaporator 1, in that the expansion valve 7 is mounted in a
low-pressure pipe extending between the vehicle compartment in
which the evaporator 1 is installed and the engine room in which
the compressor and the receiver are installed. In particular, in
the present embodiment, the expansion valve 7 is mounted in the
low-pressure pipe of the structure in which not only the
high-pressure pipe 24 and the low-pressure pipe 26 but also the
inlet pipe 5 and the low-pressure pipe 26 are formed by a double
pipe.
[0066] More specifically, in the present mounting structure, the
casing 6 is connected between an evaporator-side low-pressure pipe
26a and a compressor-side low-pressure pipe 26b, and the expansion
valve 7 is disposed in the casing 6. Further, the high-pressure
pipe 24 is connected to the inlet port 8 of the expansion valve 7,
and the inlet pipe 5 of the evaporator is connected to the outlet
port 9 of the expansion valve 7. For this reason, each of the
low-pressure pipes 26a and 26b has an end thereof to which the
joint part 27 is welded in advance so that the low-pressure pipes
26a and 26b can be easily connected to the casing 6. As a
consequence, the number of junctures of the low-pressure return
pipe extending from the evaporator 1 and having the expansion valve
7 mounted therein is reduced to two.
[0067] Further, as shown in FIG. 10, the casing 6 is partially
deformed such that insertion of the expansion valve 7 can be
guided, and such that the expansion valve 7 disposed in the casing
6 can maintain a predetermined position. In the illustrated
example, an upper central portion, as viewed in the figure, of the
casing 6 is formed into a recessed shape in a manner adapted to the
shape of the top of the power element 16, and a portion of the
casing 6 corresponding to the legs of the body 10 are curved along
the outer shape of the leg of the body 10 so that the motion of the
leg can be restricted.
[0068] It should be noted that the expansion valve 7 employed in
the present embodiment is similar to the type employed in the third
embodiment (FIG. 6) in that the belleville spring 30 is provided in
the temperature-sensing chamber of the power element 16. Further,
the upper housing 17 of the power element 16 is formed with a hole
for introducing gas into the temperature-sensing chamber. After the
temperature-sensing chamber is filled with gas, the hole is sealed
by resistance welding of a metal ball, and in the present expansion
valve 7, a portion surrounding the hole is recessed to prevent the
metal ball from protruding from the top surface of the upper
housing 17.
[0069] FIG. 11 is a cross-sectional view showing a mounting
structure of an expansion valve according to a sixth embodiment of
the present invention, and FIG. 12 is a cross-sectional view taken
on line E-E of FIG. 11. Component elements appearing in FIGS. 11
and 12, which have functions identical to or equivalent to those of
the component elements appearing in FIGS. 9 and 10, are designated
by identical reference numerals, and detailed description thereof
is omitted.
[0070] The mounting structure of the expansion valve according to
the sixth embodiment is distinguished from the mounting structure
of the expansion valve according to the fifth embodiment, in which
the number of junctures of the low-pressure return pipe extending
from the evaporator 1 at a location where the expansion valve 7 is
mounted is two, in that the number of junctures of the same is
reduced to one.
[0071] More specifically, in the present mounting structure, the
evaporator-side low-pressure pipe 26a and the casing 6 are welded
in advance, whereby the number of junctures of the low-pressure
return pipe extending from the evaporator 1 is reduced to one.
[0072] It should be noted that in the expansion valve 7 employed in
the present embodiment, the power element 16 is fixed to the body
10 by swaging. Further, this expansion valve 7 has a structure in
which the valve element 11 formed by pressing is joined to an end
face of the shaft 14 by spot welding. Further, the adjustment
member 13 is provided with a differential pressure control valve 34
operated by a differential pressure between inlet t pressure and
outlet pressure of the evaporator 1. The differential pressure
control valve 34 comprises a valve element 35 disposed on the
low-pressure return pipe side of a valve hole formed through the
adjustment member 13, and a spring 36 urging the valve element 35
in the valve closing direction. The differential pressure control
valve 34 is configured to open when refrigeration load is so high
as to make the differential pressure across the evaporator 1 higher
than a predetermined value, to supply a refrigerant having high
moisture into the low-pressure return pipe, thereby lowering the
temperature of refrigerant returned to the compressor. This
operation of the differential pressure control valve 34 is
necessitated for the following reason: The expansion valve 7
controls the flow rate of refrigerant supplied to the evaporator 1,
such that refrigerant at the outlet of the evaporator 1 maintains a
predetermined degree of superheat, to thereby cause refrigerant
having a predetermine degree of superheat to be returned to the
compressor, but since the high-pressure pipe 24 and the
low-pressure pipe 26b form a double-pipe structure, the refrigerant
having the predetermined degree of superheat is further heated,
while flowing through the low-pressure pipe 26b, by refrigerant
flowing through the high-pressure pipe 24. The differential
pressure control valve 34 is provided to prevent the temperature of
refrigerant compressed by the compressor from becoming excessively
high due to the double-pipe structure.
[0073] FIG. 13 is a cross-sectional view showing a mounting
structure of an expansion valve according to a seventh embodiment
of the present invention. Component elements appearing in FIG. 13,
which have functions identical to or equivalent to those of the
component elements appearing in FIGS. 1 and 9, are designated by
identical reference numerals, and detailed description thereof is
omitted.
[0074] The mounting structure of the expansion valve according to
the seventh embodiment is distinguished from the mounting structure
of the expansion valve according to each of the fifth and sixth
embodiments, in which not only the high-pressure pipe 24 and the
low-pressure pipe 26b but also the inlet pipe 5 and the
low-pressure pipe 26a are formed by a double pipe, and the
expansion valve 7 is mounted in an intermediate portion of the
double pipe, in that the high-pressure pipe 24 and the inlet pipe 5
of the evaporator 1 are formed separately from the respective
low-pressure pipes 26a and 26b.
[0075] In the present embodiment, the inlet pipe 5 of the
evaporator 1 and the low-pressure pipe 26a have respective ends
thereof integrally joined to the casing 6 e.g. by welding, and the
end of the high-pressure pipe 24 opposed to that of the inlet pipe
5 and the end of the low-pressure pipe 26b opposed to that of the
low-pressure pipe 26a are rigidly joined to a disk-shaped joint
part 27 by welding. The casing 6 and the joint part 27 are
connected by the pipe clamp 28. As a consequence, the number of
junctures of the low-pressure return pipe extending from the
evaporator 1 is reduced to one.
[0076] It should be noted that the expansion valve 7 described by
way of example in each of the first to six embodiments acts in the
valve opening direction when it receives high-pressure refrigerant,
whereas the expansion valve 7 employed in the present embodiment is
configured to act in the valve closing direction when it receives
high-pressure refrigerant. Further, the heat-insulating cover 22
covering the power element 16 is integrally formed with fixing legs
22a by resin-molding. Although not shown, each fixing leg 22a has a
hook formed at an end thereof, and the hook is engaged with a
stepped portion formed in the body 10, whereby the heat-insulating
cover 22 is fixed.
[0077] FIG. 14 is a cross-sectional view showing a mounting
structure of an expansion valve according to a eighth embodiment of
the present invention. Component elements appearing in FIG. 14,
which have functions identical to or equivalent to those of the
component elements appearing in FIGS. 1 and 9, are designated by
identical reference numerals, and detailed description thereof is
omitted.
[0078] The mounting structure of the expansion valve according to
the eighth embodiment is distinguished from the mounting structure
of the expansion valve according to each of the second and third
embodiments, in which the high-pressure pipe 24 and the
low-pressure pipe 26 are formed by a double pipe, and are connected
to the inlet port 8 of the expansion valve 7 and the casing 6,
respectively, in that the high-pressure pipe 24 and the
low-pressure pipe 26 formed as separate members are used, and
respective ends thereof are welded to a hollow cylindrical casing 6
having one end thereof closed. It should be noted that although not
shown, the low-pressure pipe 26 is welded to the casing 6 at a
surface of the casing 6 facing in a direction at right angles to
the sheet of FIG. 14.
[0079] Further, the present embodiment is distinguished from the
above-described embodiments in connection between the inlet port 8
of the expansion valve 7 and the high-pressure pipe 24 and
connection between the outlet port 9 of the expansion valve 7 and
the inlet pipe 5 of the evaporator 1, within the casing 6. This
concerns the structure of the expansion valve 7, and hence, first,
a description will be given of the expansion valve 7 employed in
the present embodiment.
[0080] In the present expansion valve 7, a hollow cylindrical valve
body 37 axially movably holding the shaft 14 integrally formed with
the valve element 11 is integrally formed with the lower housing 18
of the power element 16, and the end face of the valve body 37 is
utilized as a valve seat. Further, the hollow cylindrical
adjustment member 13 is press-fitted on the valve body 37. The
adjustment member 13 has an end bent into a groove in which the O
ring 23 is disposed, and a stepped portion formed by the bending in
a manner protruding inward plays the role of a receiver for the
spring 12 for adjusting the set value of the expansion valve 7.
[0081] The valve body 37 is held by a resin body 38. The resin body
38 houses a collar 39 and the O ring 25 and an O ring 25a at
respective locations on a refrigerant inlet side thereof. The
collar 39 connects between the inlet port 8 formed on the curved
surface of the expansion valve 7 and an opening formed in the
curved casing 6 and connected with the high-pressure pipe 24, with
the connecting portions sealed by the respective O rings 25 and
25a. Further, the resin body 38 has a recessed part 40 formed in
the outer peripheral surface on a diametrically opposite side from
the side where the collar 39 is housed. After the expansion valve 7
is inserted into the casing 6, the casing 6 is deformed inwardly by
swaging toward the recessed part 40 of the resin body 38 on the
diametrically opposite side of the casing 6 from the opening
connected with the high-pressure pipe 24 to thereby press the resin
body 38 toward the opening connected with the high-pressure pipe
24. This not only facilitates insertion of the expansion valve 7
with the O ring 25a mounted thereon into the casing 6, before the
swaging, but also makes it possible to further ensure sealing of
the connection between the inlet port 8 of the expansion valve 7
and the high-pressure pipe 24 by the O ring 25a, after the
swaging.
[0082] Further, the inlet pipe 5 of the evaporator 1 is integrally
formed with the connecting part 6a and joined to the evaporator 1,
and connection between the inlet pipe 5 and the outlet port 9 of
the expansion valve 7 is made by inserting the adjustment member 13
forming the outlet port 9 into the inlet pipe 5 and provides
sealing by the O ring 23.
[0083] In the present embodiment, since the high-pressure pipe 24
and the low-pressure pipe 26 are welded to the casing 6, and the
casing 6 is connected by the pipe clamp 28 to the connecting part
6a integrally formed with the evaporator 1, the number of junctures
of the low-pressure return pipe extending from the evaporator 1 is
reduced to one.
[0084] FIG. 15A is a cross-sectional view showing a mounting
structure of an expansion valve according to a ninth embodiment of
the present invention. FIG. 15B is a cross-sectional view taken on
line F-F of FIG. 15A. Component elements appearing in FIGS. 15A and
15B, which have functions identical to or equivalent to those of
the component elements appearing in FIG. 14, are designated by
identical reference numerals, and detailed description thereof is
omitted.
[0085] The mounting structure of the expansion valve according to
the ninth embodiment is similar to the second and third embodiments
in that the high-pressure pipe 24 and the low-pressure pipe 26 are
formed by a double pipe, and the low-pressure pipe 26 and the
casing 6 are joined to each other by the O ring 29 and by swaging.
More specifically, the casing 6 is formed by pressing integrally
with a hollow cylindrical joint part 27 extending outward from the
peripheral surface of the hollow cylindrical portion thereof. The
resin body 38 housing the expansion valve 7 is integrally formed
with an inlet hollow cylindrical part 41 located at the inlet port
8 of the expansion valve 7 and connected to the high-pressure pipe
24, and an outlet hollow cylindrical part 42 connected to the inlet
pipe 5 of the evaporator 1. An O ring restriction member 43 is
fitted in the outlet hollow cylindrical part 42.
[0086] The resin body 38 is formed into a hollow cylindrical outer
shape so as to be inserted into the hollow cylindrical casing 6
from the open end thereof, while the foremost end of the
low-pressure pipe 26 has a flat end face. A washer 44 having a
non-uniform circumferential thickness is interposed between the
resin body 38 and the low-pressure pipe 26 so as to accommodate the
difference in shape between the connecting portions of the two.
[0087] In the process of inserting the expansion valve 7 into the
casing 6, first, the resin body 38 having the expansion valve 7
mounted therein is inserted from the open end of the casing 6 on
the side for connection to the connecting part 6a joined to the
evaporator 1, and then the double pipe of the high-pressure pipe 24
and the low-pressure pipe 26 is inserted into the joint part 27 of
the casing 6. At this time, the high-pressure pipe 24 is fitted on
the inlet hollow cylindrical part 41 of the resin body 38, and
sealed by the O ring 25. Next, the open end of the joint part 27 is
swaged, and the surface of the casing 6 on the opposite side from
the joint part 27 is swaged toward the joint part 27. Thereafter,
the casing 6 having the expansion valve 7 inserted therein is
fitted on the connecting part 6a of the evaporator 6. At this time,
the outlet hollow cylindrical part 42 of the resin body 38 is
connected to the inlet pipe 5 of the evaporator 1 in a state sealed
by the O ring 23. Then, the open end portion of the casing 6 and
the connecting part 6a of the evaporator 1 are connected by the
pipe clamp 28. As a consequence, the number of junctures, from
which refrigerant can leak out, of the low-pressure return pipe
extending from the evaporator 1 at a location where the expansion
valve 7 is mounted is reduced to two.
[0088] FIG. 16A is a cross-sectional view taken in a plane
containing the center line of the high-pressure pipe and that of
the low-pressure pipe, in a mounting structure of an expansion
valve according to a tenth embodiment of the present invention.
FIG. 16B is a cross-sectional view taken on line G-G of FIG. 16A.
Component elements appearing in FIGS. 16A and 16B, which have
functions identical to or equivalent to those of the component
elements appearing in FIGS. 15A and 15B, are designated by
identical reference numerals, and detailed description thereof is
omitted.
[0089] The mounting structure of the expansion valve according to
the tenth embodiment is distinguished from the ninth embodiment in
which the double pipe is used, in that the high-pressure pipe 24
and the low-pressure pipe 26 are joined to the casing 6 by the
respective O rings 25 and 29 and swaging. More specifically, the
casing 6 has a hollow cylindrical portion having sides thereof
integrally formed with the joint part 27 and a joint part 45 both
extending outward in respective directions orthogonal to each
other. The high-pressure pipe 24 has a foremost end provided with
the two O rings 25 and 25a for sealing between the inlet hollow
cylindrical part 41 of the resin body 38 and the casing 6, and is
joined to the casing 6 by the O ring 25a and by swaging of the
joint part 45. On the other hand, the low-pressure pipe 26 is
joined to the casing 6 by the O ring 29 and by swaging of the joint
part 27. Therefore, the number of junctures, from which refrigerant
can leak out, of the low-pressure return pipe at a location where
the expansion valve 7 is mounted is reduced to two.
[0090] It should be noted that the expansion valve 7 employed in
the present embodiment has the resin body 38 having a valve seat
formed by insert, and the resin body 38 holds the shaft 14
integrally formed with the valve element 11, such that the shaft 14
is movable in the valve opening or closing direction, with the
adjustment member 13 screwed into the resin body 38, for adjusting
the set value, and the power element 16 rigidly secured to the
resin body 38 by engagement of the heat-insulating cover 22
therewith.
[0091] FIG. 17A is a cross-sectional view showing a mounting
structure of an expansion valve according to an eleventh embodiment
of the present invention. FIG. 17B is a cross-sectional view taken
on line H-H of FIG. 17A. Component elements appearing in FIGS. 17A
and 17B, which have functions identical to or equivalent to those
of the component elements appearing in FIG. 14, are designated by
identical reference numerals, and detailed description thereof is
omitted.
[0092] The mounting structure of the expansion valve according to
the eleventh embodiment is different from the eighth embodiment in
which the high-pressure pipe 24 and the low-pressure pipe 26 are
welded to the casing 6, in that the method of sealing between the
inlet port 8 of the expansion valve 7 and the outlet port 9 of the
same is changed. More specifically, the expansion valve 7 according
to the present embodiment is connected to the high-pressure pipe 24
and the inlet pipe 5 of the evaporator 1 via the resin body 38, but
sealing between the inlet port 8 and the outlet port 9 after
mounting of the expansion valve 7 in the resin body 38 is made by a
lip 46. The lip 46 is integrally formed with the resin body 38 as a
thin hollow cylindrical portion at the peripheral edge of an
opening between the inlet port 8 and the outlet port 9 of the
expansion valve 7 in which the valve section is press-fitted. This
makes it possible to dispense with one of the O rings required in
mounting the expansion valve 7 in the resin body 38.
[0093] It should be noted that the expansion valve 7 employed in
the present embodiment is configured such that the hollow
cylindrical valve body 37 which axially movably holds the shaft 14
integrally formed with the valve element 11, and has a stepped
portion formed in the central portion thereof as a valve seat is
press-fitted in the lower housing 18 of the power element 16, and
further the adjustment member 13 is press-fitted in the valve body
37, for adjusting the set value. A portion of the valve body 37
sealed by the lip 46 is tapered to form a wedge in the
press-fitting direction.
[0094] In the mounting structure of the expansion valve according
to the eleventh embodiment, the pipe clamp 28 connecting between
the connecting part 6a welded to the evaporator 1 and the casing 6
is formed by two engaging plates engaging in the opening edge of
the connecting part 6a and the opening edge of the casing 6,
respectively, and a bolt, as shown in FIG. 17 by way of
example.
[0095] Further, in the mounting structure of the expansion valve
according to the eleventh embodiment, as shown in FIG. 17B, in a
juncture between the high-pressure pipe 24 and the inlet hollow
cylindrical part 41 of the resin body 38 for introducing
high-pressure refrigerant into the expansion valve 7, a portion of
the casing 6 where the high-pressure pipe 24 is welded and its
vicinity are formed to have a flat surface. This prevents the shape
of the O ring 25 for sealing between the inner surface of the
casing 6 and the inlet hollow cylindrical part 41 from being
changed between when the expansion valve 7 is inserted into the
casing 6 and when sealing is effected by deforming the casing 6
from a side diametrically opposite to a side where the
high-pressure pipe 24 is welded, so as to press the inlet hollow
cylindrical part 41 of the resin body 38 toward the high-pressure
pipe 24. This makes it possible to improve assemblability.
[0096] Furthermore, in the mounting structure of the expansion
valve according to the eleventh embodiment, the refrigerant inlet 2
and the refrigerant outlet 3 of the evaporator 1 are arranged in
parallel, and the expansion valve 7 mounted in the resin body 38 is
connected to the refrigerant inlet 2 and the refrigerant outlet 3
arranged in parallel, by way of example, as shown in FIG. 17. When
the refrigerant inlet 2 and the refrigerant outlet 3 of the
evaporator 1 are thus arranged in parallel, the outlet hollow
cylindrical part 42 of the resin body 38 for connecting the outlet
port 9 of the expansion valve 7 to the inlet pipe 5 of the
evaporator 1 is formed in a manner eccentric toward the inlet pipe
5 with respect to the center of the expansion valve 7.
[0097] According to the above-described mounting structure, at a
location where the expansion valve 7 is mounted, the low-pressure
return pipe has only one juncture from which refrigerant can leak
out at a location where the connecting part 6a and the casing 6 are
connected by the pipe clamp 28.
[0098] FIG. 18 is a cross-sectional view showing a mounting
structure of an expansion valve according to a twelfth embodiment
of the present invention. Component elements appearing in FIG. 18,
which have functions identical to or equivalent to those of the
component elements appearing in FIG. 17, are designated by
identical reference numerals, and detailed description thereof is
omitted.
[0099] The mounting structure of the expansion valve according to
the twelfth embodiment is distinguished from the eleventh
embodiment in which the invention is applied to the evaporator 1
having the refrigerant inlet 2 and the refrigerant outlet 3 formed
in parallel in a plurality of plates and end plates laminated one
upon another, in that the invention is applied to an evaporator 1a
having the refrigerant inlet 2 and the refrigerant outlet 3
concentrically arranged. The expansion valve 7 is disposed within
the casing 6 such that the outlet port 9 is coaxial with the inlet
pipe 5 of the evaporator 1a.
[0100] The evaporator 1a comprises two header portions and a core
portion connecting between the header portions by a plurality of
pipes. The juncture of one of the header portions with the casing 6
and the expansion valve 7 has a double-pipe structure. The inlet
pipe 5 disposed as the inner one of the double pipe extends into
the header portion up to an intermediate portion thereof and the
foremost end portion of the inlet pipe 5 partitions the header
portion in a manner dividing the same into two in the longitudinal
direction. With this construction, one half of the header portion
on the connection side forms a return collective space, and the
other half forms a forward collective space.
[0101] It should be noted that although the expansion valve 7
employed in the present embodiment is similar in construction to
the expansion valve 7 described by way of example in the eleventh
embodiment illustrated in FIG. 17, the present expansion valve 7 is
configured such that the valve body 37 is press-fitted into the
resin body 38 instead of providing the lip 46 to thereby dispense
with an O ring, and the valve body 37 is connected to the inlet
pipe 5 of the evaporator 1a. Further, although not shown, the
low-pressure pipe 26 is welded to the casing 6 in a direction at
right angles to the sheet of FIG. 18.
[0102] According to this mounting structure as well, at a location
where the expansion valve 7 is mounted, the low-pressure return
pipe has only one juncture from which refrigerant can leak out at a
location where the connecting part 6a and the casing 6 are
connected by the pipe clamp 28.
[0103] FIG. 19 is a cross-sectional view showing a mounting
structure of an expansion valve according to a thirteenth
embodiment of the present invention. Component elements appearing
in FIG. 19, which have functions identical to or equivalent to
those of the component elements appearing in FIG. 18, are
designated by identical reference numerals, and detailed
description thereof is omitted.
[0104] The mounting structure of the expansion valve according to
the thirteenth embodiment is distinguished from the mounting
structure of the expansion valve according to the twelfth
embodiment in that the expansion valve 7 and the casing 6 are
configured to be sound-insulating and that the connecting part 6a
and the casing 6 are connected to each other by swaging.
[0105] More specifically, in the present mounting structure, the
expansion valve 7 disposed within the casing 6 is covered by a
soundproofing member 47, and the casing 6 is covered by a
soundproofing member 48. These soundproofing members 47 and 48 are
made of a material which has large mass and a main content of
rubber. The soundproofing member 47 also functions as a
heat-insulating cover for adjusting the temperature-sensing time
constant of the power element 16 of the expansion valve 7. The
expansion valve 7 generates flow noise when throttling and
expanding refrigerant, which makes a noise source. Since the
expansion valve 7 is disposed in the vehicle compartment together
with the evaporator 1a, noise is directly emitted into the vehicle
compartment, which becomes a factor that largely impairs the
quietness of the vehicle compartment. By covering the expansion
valve 7 with the soundproofing member 47, flow noise emitted from
the expansion valve 7 is absorbed and attenuated by the
soundproofing member 47, so that the sound pressure of the noise
source can be reduced. Moreover, since the casing 6 housing the
expansion valve 7 provided with the soundproofing measure is
covered by the soundproofing member 48, it is possible to further
reduce noise.
[0106] Further, in this mounting structure, the casing 6 is not
removably connected to the connecting part 6a of the evaporator 1a
by the pipe clamp, but is connected to the evaporator 1a by
swaging.
[0107] It should be noted that in the expansion valve 7 employed in
the present embodiment, the valve body 37 is integrally formed with
the lower housing 18 of the power element 16, with the end face of
the valve body 37 being utilized as a valve seat, and a hollow
cylindrical guide 49 axially movably holding the shaft 14
integrally formed with the valve element 11 is press-fitted into
the valve body 37. The guide 49 axially movably holds a hollow
cylindrical member 50 in which the shaft 14 is press-fitted. The
hollow cylindrical member 50 has one end integrally formed with a
flange portion, and the flange portion functions as a center disk
for receiving the diaphragm 19 of the power element 16 and a spring
receiver for the spring 12 urging the valve element 11 in the valve
closing direction.
[0108] Although in the present embodiment, the soundproofing member
47 insulates noise from the expansion valve 7 by covering the
expansion valve 7, the casing 6 may be lined with the soundproofing
member 47 except for portions in contact with the resin body
38.
[0109] In the present embodiment, since the high-pressure pipe 24
and the low-pressure pipe 26 are welded to the casing 6, and the
casing 6 is connected to the connecting part 6a integrally formed
with the evaporator 1 by swaging, the low-pressure return pipe from
the evaporator 1 has only one juncture.
[0110] FIG. 20 is an exploded perspective view showing a mounting
structure of an expansion valve according to a fourteenth
embodiment of the present invention. Component elements appearing
in FIG. 20, which have functions identical to or equivalent to
those of the component elements appearing in FIG. 17, are
designated by identical reference numerals, and detailed
description thereof is omitted.
[0111] The mounting structure of the expansion valve according to
the fourteenth embodiment is distinguished from the mounting
structure of the expansion valve according to the eleventh
embodiment in that between the evaporator 1 having the refrigerant
inlet 2 and the refrigerant outlet 3 formed in parallel and the
connecting part 6a to which is connected the casing 6 housing the
expansion valve 7, there is interposed a member for forming a flow
passage through which refrigerant from the expansion valve 7 is
guided to the refrigerant inlet 2. More specifically, between the
evaporator 1 and the connecting part 6a, there is disposed a base
plate 51. The base plate 51 has an elliptical cup-shaped member 52
which extends thereon from an approximately central portion thereof
to a corner thereof associated with the refrigerant inlet 2 of the
evaporator 1, and is open toward the evaporator 1, and the
cup-shaped member 52 has an opening formed at a location
corresponding to the approximately central portion of the base
plate 51 and the inlet pipe 5 is formed in an manner surrounding
the opening. Further, the base plate 51 has a hole 53 formed at a
location corresponding to the refrigerant outlet 3 of the
evaporator 1.
[0112] The connecting part 6a is shaped such that when overlaid on
the base plate 51, the connecting part 6a covers the cup-shaped
member 52, the inlet pipe 5, and the hole 53, and has a connecting
end 54 formed in a central portion thereof for connection with the
casing 6 in a manner concentric with the inlet pipe 5. The
high-pressure pipe 24 and the low-pressure pipe 26 are welded to
the peripheral surface of the casing 6.
[0113] The base plate 51 and the connecting part 6a are integrally
formed with the evaporator 1 by furnace brazing. The expansion
valve 7 is inserted in the casing 6, in advance, and the casing 6
is deformed inward from a diametrically opposite side of the casing
6 from a portion of the same to which is welded the high-pressure
pipe 24, to thereby connect the inlet port to the high-pressure
pipe 24. In assembling, the expansion valve 7 received within the
casing 6 is inserted from the connecting end 54 of the connecting
part 6a, whereby the portion of the expansion valve 7 formed with
the outlet port is pushed into the inlet pipe 5. Thereafter, the
connecting end 54 and the casing 6 are connected by a pipe clamp or
by swaging the open end of the casing 6. As a consequence,
high-pressure liquid refrigerant introduced from the high-pressure
pipe 24 is throttled and expanded by the expansion valve 7 into
atomized low-pressure refrigerant, and the atomized low-pressure
refrigerant is introduced to the refrigerant inlet 2 of the
evaporator 1 via the inlet pipe 5 and the cup-shaped member 52.
Refrigerant evaporated by the evaporator 1 is introduced into a
space within the connecting part 6a and a space within the casing 6
via the refrigerant outlet 3 and the hole 53 of the base plate 51,
and then flows to the low-pressure pipe 26. At this time, the
expansion valve 7 senses the temperature and pressure of the
refrigerant flowing to the low-pressure pipe 26 and controls the
flow rate of refrigerant delivered to the evaporator 1.
[0114] In the present embodiment as well, since the high-pressure
pipe 24 and the low-pressure pipe 26 are welded to the casing 6,
and the casing 6 is connected to the connecting part 6a integrally
formed with the evaporator 1 by the pipe clamp or by swaging, the
low-pressure return pipe from the evaporator 1 has only one
juncture.
[0115] It should be noted that although in the first to thirteenth
embodiments, the expansion valves 7 different in construction are
employed, respectively, the expansion valves 7 are employed only by
way of example, but they are not limitatively employed for the
respective mounting structures.
[0116] The mounting structure of the expansion valve according to
the present invention is constructed such that the low-pressure
return pipe extending from the evaporator to the compressor
accommodates the expansion valve, and the expansion valve is
connected to the high-pressure pipe and the evaporator inlet pipe,
within the low-pressure return pipe. This makes it is possible to
largely reduce the number of refrigerant external leak-prone spots
in the mounting portions of the expansion valve.
[0117] By forming the casing for housing the expansion valve
integrally with the evaporator, it is possible to further reduce
the number of refrigerant external leak-prone spots at a juncture
between the evaporator and the low-pressure return pipe.
[0118] The foregoing is considered as illustrative only of the
principles of the present invention. Further, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and applications shown and described, and accordingly,
all suitable modifications and equivalents may be regarded as
falling within the scope of the invention in the appended claims
and their equivalents.
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