U.S. patent application number 09/788993 was filed with the patent office on 2001-10-11 for expansion valve.
This patent application is currently assigned to TGK Co., Ltd.. Invention is credited to Hirota, Hisatoshi, Kobayashi, Takashi, Saeki, Shinji.
Application Number | 20010027656 09/788993 |
Document ID | / |
Family ID | 18566669 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010027656 |
Kind Code |
A1 |
Hirota, Hisatoshi ; et
al. |
October 11, 2001 |
Expansion valve
Abstract
In an expansion valve the pressure vessel of which is
constituted by a reduced number of parts and which does not require
seal members a valve unit is surrounded by first and second half
shells which in turn are surrounded by a pressure vessel formed as
a one-piece body by molding resin by an insert molding process.
Since the resin constituting the resin molded one-piece pressure
vessel simultaneously form internal sealing member structures no
additional seal members are required to be positioned and mounted.
The first and second half shells are shaped such that the necessary
refrigerant passages for the valve unit are defined in
communication with connection holes of the pressure vessel.
Inventors: |
Hirota, Hisatoshi; (Tokyo,
JP) ; Saeki, Shinji; (Tokyo, JP) ; Kobayashi,
Takashi; (Tokyo, JP) |
Correspondence
Address: |
James E. Nilles
NILLES & NILLES, S.C.
Firstar Center, Suite 2000
777 East Wisconsin Avenue
Milwaukee
WI
53202
US
|
Assignee: |
TGK Co., Ltd.
|
Family ID: |
18566669 |
Appl. No.: |
09/788993 |
Filed: |
February 19, 2001 |
Current U.S.
Class: |
62/210 ;
62/222 |
Current CPC
Class: |
B29L 2031/7506 20130101;
B29C 45/14467 20130101; F25B 2500/21 20130101; F25B 2341/0683
20130101; Y10T 137/7036 20150401; F25B 41/335 20210101 |
Class at
Publication: |
62/210 ;
62/222 |
International
Class: |
F25B 041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2000 |
JP |
2000-043812 |
Claims
1. An expansion valve including an in-built valve unit, said valve
unit having the function of a temperature sensing section detecting
a degree of refrigerant overheat at an outlet of an evaporator and
the function of a valve element controlling a passing amount of
high-pressure refrigerant to be adiabatically expanded in
accordance with changes of the degree of refrigerant overheat as
detected by said temperature sensing section, wherein said valve
unit completely is received in an outer pressure vessel formed by
moulding resin into a one-piece body by an insert moulding
process.
2. The expansion valve as in claim 1, wherein two half shells are
interposed between said valve unit and said resin-moulded pressure
vessel as a pre-assembled sub-unit containing said valve unit, each
of said half shells having a shape forming refrigerant passages
communicating with refrigerant passage ports formed by said
resin-moulded pressure vessel.
3. The expansion valve as in claim 2, wherein each of said half
shells has at least one resin injection port and a groove
communicating with said resin injection port and extending along a
boundary between an inlet section for introducing the high-pressure
refrigerant and an outlet section for letting out adiabatically
expanded low-pressure refrigerant, and extending along a boundary
at which a refrigerant passage for passing the refrigerant from the
outlet of the evaporator is bounded by the high-pressure
refrigerant inlet section and by the low-pressure refrigerant
outlet section, the resin forming said pressure vessel being
injected into said grooves during the insert moulding process to
form an integrated seal member structure of said expansion
valve.
4. The expansion valve as in claim 1, wherein said resin-moulded
pressure vessel has an elliptic outer form in view onto a pipe
mounting surface thereof.
5. The expansion valve as in claim 1, wherein said pressure vessel
has an integrated circumferential flange protruding at a location
close to one pipe mounting surface thereof, said flange forming
part of a sealing structure for a mounting section.
6. The expansion valve as in claim 1, wherein said pressure vessel
has at least one through hole extending through said pressure
vessel from one pipe mounting surface to another pipe mounting
surface to permit a mounting bolt to be inserted therethrough, and
a metal collar inserted into said through hole and having a length
greater than that of said through hole.
7. The expansion valve as in claim 6, wherein a metal plate as a
component separate from said pressure vessel is arranged close to
one pipe mounting surface in abutment against an end face of said
metal collar for bearing stress induced by tightening the mounting
bolt inserted through said metal collar arranged in said through
hole.
8. The expansion valve as in claim 7, wherein said metal plate has
a mounting bolt either securely fixed on said metal plate or formed
integrally therewith, said mounting bolt permitting a pipe to be
mounted to said one pipe mounting surface.
9. The expansion valve as in claim 2, wherein both of said half
shells of said sub-unit are positively interconnected in
predetermined mutually related positions along common peripheral
continuous edge regions comprising a positively engaging groove and
rib structure and by positively inter-engaging hook and counter
hook structures provided outside of said edge regions.
10. A method for manufacturing an expansion valve for a
refrigeration cycle, according to which method a valve unit
including a temperature sensing section and valve element is
completely inserted into a pressure vessel having a cavity for said
valve unit and high-pressure and low-pressure refrigerant passages,
wherein said pressure vessel is formed in one piece around said
valve unit from a resin and by an insert moulding process.
11. Method as in claim 10, wherein said insert moulding process
simultaneously and in situ forms from said resin defining said
pressure vessel a sealing structure for and between the respective
refrigerant passages.
12. Method as in claim 10 or 11, wherein two half shells are
prefabricated and are interconnected around said valve unit into a
sub-unit of said expansion valve, each of said half shells being
prefabricated with integrated cavities for said sealing structure
and with refrigerant passage parts, forming a sub-form cavity from
said sub-form cavity depressions by interconnecting said half
shells, positioning of said sub-unit in a form cavity corresponding
to the shape and dimension of said pressure vessel, filling said
form cavity and simultaneously said sub-form cavity within said
sub-unit and integrating said sub-unit into said pressure vessel by
injecting resin in an insert moulding process into said form
cavity.
Description
DESCRIPTION
[0001] The present invention relates to an expansion valve and to a
method for manufacturing the expansion valve conventionally used in
a refrigerating cycle of an automobile air-conditioner or the like
for adiabatically expanding a high temperature, high-pressure
liquid refrigerant to turn the refrigerant into a low temperature
low-pressure gas liquid mixture of refrigerant and also for
controlling the flow rate of the refrigerant such that the
refrigerant has a predetermined degree of overheat at the outlet of
an evaporator. The expansion valve according to the invention
includes a in-built valve unit, said valve unit having the function
of a temperature sensing section detecting the degree of
refrigerant overheat at an outlet of an evaporator and the function
of a valve element controlling a passing amount of high-pressure
refrigerant to be adiabatically expanded in accordance with changes
of the degree of refrigerant overheat as detected by said
temperature sensing section.
[0002] In known refrigerant cycles of car air-conditioners the
expansion valve arranged in an evaporator casing is connected to
refrigerant inlet and outlet pipes of the evaporator which is
arranged in the vehicle compartment. Said expansion valve is also
connected to pipes leading to a compressor and a condenser,
respectively, both of which are arranged in the engine
compartment.
[0003] The mounting of a conventional expansion valve is
illustrated in FIG. 19. The expansion valve 111 is fixed to a
partition wall 112 separating the vehicle compartment from the
engine compartment. Due to the irregular external shape of
expansion valve 111 a connector 113 is needed as an adapter
matching to the external shape of the expansion valve. Connector
113 is joined to that side of the expansion valve to which the
pipes are connected leading to the compressor and the condenser.
Around connector 113 an insulator 114 is provided sealing the gap
between the connector 113 and the partition wall 112 and between
the connector 113 and an evaporator casing 115. Pipes 116 and 117
to compressor and the condenser are connected to connector 113 and
fixed thereto by a mounting bolt 119 with a plate 118 interposed
therebetween. Pipes 120 and 121 leading to an evaporator are fixed
to an evaporator side of the expansion valve 111 by a mounting bolt
123 with a blade plate 122 interposed therebetween. Expansion valve
111 includes a valve unit 124 comprising a temperature sensing
section measuring the refrigerant temperature at the outlet of the
evaporator and a valve element the degree of opening of which is
determined by the refrigerant temperature at the outlet of the
evaporator. In FIG. 19 valve 124 has its temperature sensing
section arranged outside of the refrigerant pipe. There are other
types of expansion valve units where the temperature sensing
section is arranged inside the refrigerant pipe. In either type,
the expansion valve unit used has a low-pressure passage for the
refrigerant exiting the evaporator and a high-pressure passage with
the valve element inserted therein for restricting the flow of
liquid refrigerant and expanding the refrigerant prior to the
refrigerant reaching the evaporator. The temperature sensing
section is arranged in the low-pressure passage. The valve element
is actuated in accordance with the measured temperature.
[0004] Among expansion valves having the temperature sensing
section received inside its casing, there is a type known in which
the valve unit (temperature sensing section and valve element
integrally combined) is completely received in a pressure vessel.
The pressure vessel used is formed from extruded aluminium
material. A chamber or cavity is cut out for receiving the valve
unit. Also the high-pressure and low-pressure passages are formed
into said pressure vessel. However, seal members are needed in said
pressure vessel, and a lid closing the pressure vessel after the
valve unit is inserted, such that any gaps between the valve unit
and the refrigerant passages and the surrounding are sealed in
order to completely seal the pressure vessel. The plurality of
seals needs corresponding manufacturing machining or preparation.
Due to the complexity of the seals and their number the likelihood
of refrigerant leaking to the outside is high.
[0005] It is an object of the present invention to create an
expansion valve included into a pressure vessel which expansion
valve is constituted by a reduced number of parts and does not
require seal members to be inserted or manufacturing preparation
for the insertion of seal members.
[0006] Said task is achieved by the feature combination of claim 1
and the feature combination of method claim 10.
[0007] In the expansion valve according to the invention, the
pressure vessel completely enclosing the valve unit is formed
solely by resin moulding. By said moulding process it is
unnecessary to use seal members such as O-rings, which normally
constitute a primary cause of refrigerant leakages to the outside.
Forming the pressure vessel solely by resin moulding also allows to
reduce the number of parts necessary to constitute the expansion
valve, because the pressure vessel is constituted by a single
resin-moulded article. The expansion valve is completed for
operation as soon as the pressure vessel is formed with the valve
unit contained therein. Any further assembling steps can be
avoided.
[0008] Expedient embodiments of the invention are contained in the
depending claims.
[0009] The valve unit is surrounded by two half shells which in
turn are surrounded by a body block formed by insert moulding and
defining said pressure vessel. Since the pressure vessel is formed
solely by resin moulding, any further step of assembling the
expansion valve can be omitted. Since neither a lid nor any O-rings
are required for sealing purposes, the number of parts of the
expansion valve can be reduced, thus reducing the manufacturing and
assembling costs. Furthermore, no O-rings are used for sealing
purposes, so that the refrigerant is prevented from leaking to the
outside.
[0010] Both half shells are shaped to define therein a gap at a
boundary between the high-pressure region and the low-pressure
region. By injecting resin into the gap when the body block or
pressure vessel is formed by insert moulding a wall sealing
structure is formed by injected resin. It is, therefore,
unnecessary to provide any separate seal member at the boundary
between the high and low pressure regions.
[0011] The expansion valve defines by its pressure vessel an
elliptic outer form and as such can serve as a connector so that no
separate connector is needed when mounting the expansion valve. A
flange is formed on the expansion valve adjacent to its surface to
which pipes leading to the evaporator are to be mounted. Thus,
satisfactory sealing performance can be ensured with ease by simply
interposing an insulator between said flange and the partition
separating the vehicle compartment from the engine compartment.
[0012] Metal collars are fitted in the respective holes through
which the mounting bolts are inserted. In this case any stress
induced by tightening the mounting bolts is taken up by the metal
collars so that the pressure vessel or body block of the expansion
valve made of resin is prevented from being fractured by
excessively large stress applied thereto.
[0013] Particularly serial production of a large number of
identical expansion valves of this type can be carried out with
reduced costs. The half shells and the valve units are
prefabricated components. The half shells do not need precise
machining for positioning sealing members. Sub-units thus can be
prefabricated by solely inserting the valve between the
interconnected half shells. The sub-units can be comfortably stored
and transported to the injection or insertion moulding site and can
be placed one by one or in series in the respective mould cavities.
By injecting the resin the pressure vessel surrounding each
sub-unit and simultaneously the internal sealing member structures
necessary between the regions of the expansion valve having
different pressures are formed. With the termination of the
insertion mould process the expansion valves are readily assembled
for use. The degree of freedom to design the outer contour of the
pressure vessel in view to easy and comfortable mounting of the
expansion valve in an evaporator casing and at the separation wall
between the engine compartment and the vehicle compartment and
finally the mounting of the expansion are simplified to a
considerable extent.
[0014] Embodiments of the invention as well as a prior art
expansion valve will be hereinafter described with reference to the
drawings. In the drawings is:
[0015] FIGS. 1A, 1B and 1C a front view, a side view and a rear of
a first embodiment of an expansion valve,
[0016] FIG. 2 a vertical sectional view of the expansion valve,
[0017] FIG. 3 a further detailed longitudinal sectional view of the
expansion valve,
[0018] FIGS. 4A, 4B, 4C, 4D a first half shell of the expansion
valve in a rear view, a side view, a front view and a sectional
view,
[0019] FIGS. 5A, 5B, 5C 5D a second half shell of the expansion
valve in a front view, a side view, a rear view and a sectional
view,
[0020] FIG. 6 a front view of a sub-unit constituted by first and
second half shells confining a valve unit,
[0021] FIG. 7 a longitudinal sectional view of the sub-unit of FIG.
6, in detail,
[0022] FIG. 8 another longitudinal sectional view of the first
embodiment of the expansion valve illustrating an integrated seal
member structure,
[0023] FIGS. 9 and 10 horizontal sectional views in sectional plane
a-a and b-b in FIG. 8,
[0024] FIG. 11 a vertical sectional view illustrating the first
embodiment of the expansion valve in mounted condition,
[0025] FIG. 12 a vertical sectional view of a second embodiment of
the expansion valve,
[0026] FIGS. 13A, 13B, and 13C a third embodiment of the expansion
valve in a front view, a side view and a rear view,
[0027] FIGS. 14A, 14B, 14C and 14D a example of a mounting bolt for
the expansion valve, in a front view, a side View, a rear view and
a sectional view (sectional plane a-a in FIG. 14A),
[0028] FIGS. 15A, 15B, 15C and 15D another example of a mounting
bolt for the expansion valve, in a front view, a side view, a rear
view and a view in viewing direction b-b of FIG. 15A,
[0029] FIG. 16 a horizontal sectional view of a modified expansion
valve containing method collars,
[0030] FIG. 17 a vertical sectional view of an expansion valve in
mounted condition,
[0031] FIG. 18 a vertical sectional view of another mounting
structure of a flanged expansion valve, and
[0032] FIG. 19 a vertical sectional view of a mounted conventional
expansion valve according to prior art.
[0033] In FIGS. 1A to 1C a first embodiment of an expansion 1, as
an example for an expansion valve useful for a refrigerating cycle
of a car air-conditioner, has the shape of a elliptic cylinder with
front and rear pipe mounting surfaces and refrigerant pipe
connection holes 2, 3, 4 and 5. Hole 2 is an opening to which a
refrigerant pipe extending from the outlet of a not shown
evaporator is connected. To hole 3 a refrigerant pipe extending to
the inlet of said evaporator is to be connected. To hole 4 a
refrigerant pipe extending to a not shown compressor is to be
connected. To hole 5 a refrigerant pipe extending from a not shown
condenser is to be connected.
[0034] Refrigerant pipes connected to holes 4 and 5 can be fixed by
means of an embedded bolt 6. Holes 7 and 8 permit to insert bolts,
not shown, provided on the evaporator side, to secure the expansion
valve 1 in position. The compressor and the condenser of the
refrigerating cycle are arranged in the engine compartment, while
the evaporator is arranged in the vehicle compartment. Expansion
valve 1 is intended to be arranged at a partition wall separating
the engine compartment from the vehicle compartment. In FIG. 2 a
valve unit 10 is arranged in a central portion of the expansion
valve 1. Valve unit 10 is surrounded by first and second half
shells 11, 12 which, in turn, are surrounded by a body block or
pressure vessel 13.
[0035] Valve unit 10 has a temperature sensing section and a valve
member integrally combined with each other. The first and second
half shells 11, 12 have the function to define refrigerant passages
between the valve unit 10 and the pressure vessel 13 in
communication with refrigerant pipe connection holes 2, 3, 4 and 5
provided in said pressure vessel. Said pressure vessel or body
block 13 forming the outermost part of said expansion valve 1 is
formed by moulding a resin into a one-piece body by insert
moulding.
[0036] In FIG. 3 a diaphragm 23 is arranged in valve unit 10 a
space surrounded by upper and lower housing parts 21, 22. A
retainer 25 is provided above diaphragm 23 for retaining activated
charcoal 24 adjusting the response speed of the temperature sensing
section. A capillary tube 26 protrudes from the upper housing 21
used to fill gas into upper housing part 21. After filling the gas
tube 26 is crushed flat and is cut and it brazed using a brazing
filler metal 27 to prevent leakage of the gas. In lower housing
part 22 a pressure equalising hole 28 is cut leaving space beneath
diaphragm 23 open.
[0037] Below diaphragm 23 a disk 29 and below disk 29 a stopper 31
are provided. Stopper 31 is slidably received in a cylinder chamber
formed in an upper portion of valve body 30 for controlling and
regulating the stroke of the diaphragm 23. A shaft 32 transmits
displacement of the diaphragm 23 to a valve ball 33. O-ring 34
prevents high-pressure refrigerant acting upon valve ball 33 from
leaking to the low-pressure, equalised pressure region.
[0038] Shaft 32 and valve ball 33 are welded together. Valve ball
33 is urged in closing direction towards a valve seat by a spring
36 and via a valve holder 35. Spring 36 is seated against an
adjusting screw 37 allowing to adjust the force of spring 36. By
spring 36 a set value for the static overheat degree of the
expansion valve can be adjusted.
[0039] Valve body 30 has a high-pressure refrigerant inlet port 38
at an upstream side of valve ball 33, and a low-pressure
refrigerant outlet port 39 downstream of valve ball 33.
[0040] When upper housing part 21 is exposed to the refrigerant at
the outlet of the evaporator, the refrigerant temperature is
converted into a pressure depending on the adsorptivity of
activated charcoal provided. As said pressure changes valve body 33
is displaced by the diaphragm 23, disk 29 and shaft 32. In this way
the opening degree of said valve ball in relation to its associated
valve seat is controlled.
[0041] The valve unit 10 surrounded by said first and second half
shells 11 and 12 (FIGS. 4 and 5) forms a sub-unit as shown in FIG.
6. A body 41 of the first half shell 11 in FIGS. 4A to 4D has a
hole 42 defining an opening for communication with refrigerant pipe
connection hole 4 of pressure vessel 13, and a hole 43 defining an
opening for communication with refrigerant pipe connection hole 5.
In an end face of body 41 along the outer circumference or
continuous edge region an engaging groove 44 is cut fitting to an
engaging rib 54 of the other second half shell of FIG. 5A to FIG.
5D. This is the edge region in which the first half shell 11 is to
be joined to the second half shell 12. At the periphery of body 41
hooks 45 are formed serving to securely join the second half shell
12 to the first half shell 11.
[0042] Inside body 41 a refrigerant passage 46 is formed for
guiding refrigerant from hole 43 to high-pressure refrigerant inlet
port 38 of valve unit 10. Into body 41 resin injection holes 47 are
cut so as to open from the outside into a seal-forming groove 48
formed inside body 41. Resin injection holes 47 and seal-forming
groove 48 are used to form a seal member structure integrally with
pressure vessel or body block 13 when said pressure vessel 13 is
formed from resin by an insert moulding process. During said
process resin is injected through said resin injection holes 47
into the space defined between the seal-forming groove 48 and valve
unit 10 resulting in the integral seal member structure.
[0043] A body 51 of the second half shell 12 in FIGS. 5A to 5D has
holes 52, 53 defining openings for communication with refrigerant
pipe connection holes 2 and 3. On an end face of body 51 along the
outer circumference or edge region an engaging ridge 45 is formed
fitting into groove 44 of first half shell 11. Said engaging ridge
54 extends along the edge region of said second half shell 12 along
which both half shells 11, 12 are to be joined to each other. At
the outer periphery of body 51 engaging portions 55 are formed in
alignment with hooks 45 of the first half shell 11. When joining
both half shells 11, 12 engaging portions 55 are brought into
engagement with hooks 45 for a positive joint of both half
shells.
[0044] Inside body 51 of second half shell 12 a refrigerant passage
56 is formed for guiding refrigerant from low-pressure refrigerant
pressure outlet port 39 of valve unit 10 to hole 53. Resin
injection holes 53 are cut into body 51 so as to open from outside
into a seal forming groove 58 formed inside body 51. Also through
resin injection holes 57 resin is to be injected into the space
defined between the seal forming groove 58 and the valve unit 10 to
form a seal member structure integrally with pressure vessel or
body block 13 at the same time when pressure vessel 13 is formed
from resin by insert moulding.
[0045] FIG. 6 illustrates the sub-unit in which valve unit 10 is
surrounded by the interconnected first and second half shells prior
to moulding the pressure vessel. Portion 55 are engaging with hooks
45. In the sectional view of FIG. 7 the engaging ridge 54 of the
second half shell 12 is fitted into engaging groove 44 of the first
half shell 11 to assemble the valve unit 10 and both shells 11, 12
in said sub-unit. In said sub-unit port 38 of valve unit 10 is
aligned with refrigerant passage 46 of first half shell 11 and also
with outlet port 39 of valve unit 10 aligned with refrigerant
passage 56 of the second half shell 12. The assembling of said
sub-unit is completed as soon as engaging portions 55 of the second
half shell are brought into engagement with hooks 45 of first half
shell 11.
[0046] At this stage of the manufacturing of the expansion valve,
in FIG. 7, seal-forming passages 61 are defined by portions of the
surface of valve unit 10 near inlet port 38 and outlet port 39 and
by said seal-forming grooves 48 an 58 inside first and second half
shells 11, 12. Said seal-forming passages 61 communicate with each
other inside the half shells and open to the outside through said
resin injection holes 47, 57 of both half shells 11, 12.
[0047] The assembled sub-unit thus obtained is positioned in a form
cavity in an injection moulding machine. Then said body block or
pressure vessel 13 is formed by insert moulding from resin. During
insert moulding said pressure vessel 13 is formed from resin around
the first and second half shells 11, 12. At the same time the
seal-forming passages 61 are filled with resin injected through
resin injection holes 47, 57, so that a seal member structure and
the body block or pressure vessel 13 are formed as a one-piece
body.
[0048] In FIGS. 8, 9 and 10 resin injected through resin injection
holes 47, 57 of both shells 11, 12 flows along the outer surface of
valve body 30 and surrounds the outer peripheral surface of same,
except inlet port 38 and outlet port 39 of valve unit. Seal forming
passages 61 then are consequently filled by the injected resin thus
forming a seal member structure 62. Said seal member structure 62
serves to seal in a boundary between a high-pressure region close
to connection hole 5 and low-pressure region close to connection
hole 3. Seal member structure 62 further seals at a boundary at
which the refrigerant passage connecting connection holes 2, 4 is
bounded by the high-pressure region close to connection hole 5 and
the low-pressure region close to connection hole 3. As seal member
structure 62 and body block or pressure vessel 13 are formed as a
one-piece body, no seal members such as O-rings are needed as in
conventional arrangements.
[0049] In FIG. 11 expansion valve 1 is fitted through an elliptic
hole cut in a partition wall 71 separating the vehicle compartment
from the engine compartment in a car. An insulator 73 winds around
expansion valve 1 to seal a gap between the outer contour of
expansion valve 1 and the hole in partition wall 71 as well between
partition walls 71, an evaporator casing 72 and said expansion
valve 1. Said insulator 73 interrupts communication between the
vehicle compartment and the engine compartment. Furthermore, the
portion of the expansion valve 1 at which the valve is mounted to
the evaporator casing 72 is sealed. Due to the elliptic outer form
of expansion valve 1 it is unnecessary to use a connector as
necessary for conventional expansion valves.
[0050] Pipes 74, 75 leading to the evaporator are connected to
connection holes 2, 3, respectively, and fixed to the expansion
valve 1 by mounting bolts 76 inserted from the engine compartment
side through holes 7, 8 additionally, a plate 77 is used for the
fixation. Pipes 78, 79 leading to the compressor and the condenser,
respectively, are connected to connection holes 4, 5 and are fixed
to the expansion valve 1 by embedded bolt 6 and a plate 80.
[0051] For the second embodiment of the expansion valve according
to the present invention in FIG. 12 identical reference numerals
are used to denote elements identical to those of the expansion
valve of the first embodiment. Different from the first embodiment
the valve unit 10a in FIG. 12 includes a valve poppet 83 instead of
a valve ball. Valve unit 10a includes a piston 81 movably received
in the cylinder of valve body 30 for reciprocating motion, a shaft
82, valve poppet body 83 and a spring seat 84 unified in a
one-piece body. The upper end of piston 81 is fixed to disk 29.
Spring seat 84 bears the load of spring 36. Disk 29 also functions
as a stopper and regulates the stroke of diaphragm 23.
[0052] FIGS. 13A to 13C illustrate the external appearance of a
third embodiment of an expansion valve 1 according to the
invention. Identical reference numerals are used to denote elements
identical with those of the first embodiment of FIG. 1. Flush with
the end face in which connection holes 2, 3 are formed a flanged 91
is formed on the expansion valve 1. The flange 91 is formed
integrally with the body block or pressure vessel when the body
block is formed using resin and by an insert moulding process. In
the other end face of expansion valve 1 where pipe connection holes
4, 5 are formed a recess 92 for receiving a separate mounting bolt
93 or 98 is formed.
[0053] FIGS. 14A to 14D illustrate said mounting bolt 93 comprising
a bolt 94 and a plate 95 joined together by welding. Plate 95 has
holes 96, 97 at locations corresponding to holes 7, 8,
respectively, of the expansion valve 1. Mounting bolt 93 is
attached to recess 92 when the pipes are to be connected to the
expansion valve 1.
[0054] FIGS. 15A to 15D illustrate said other mounting bolt 98
comprising a plate 100 and a bolt 99 formed as a one-piece body.
Plate 100 has holes 101, 102 at locations corresponding to the
respective holes 7, 8 in the expansion valve 1. Mounting bolt 98 is
attached in recess 92 and is used when the pipes are to be
connected to the expansion valve 1.
[0055] Holes 7, 8 of expansion valve 1 are fitted with pipe
mounting bolts. Those mounting bolts, when inserted, are tightened
to securely fix the pipes. As soon as said mounting bolts are
tightened there tightening forces are applied directly to pressure
vessel 13. Since pressure vessel 13 is made of resin there is a
possibility that the pressure vessel will fracture when applied
with excessively large stress. According to FIG. 16 a structure is
employed for preventing such fracture.
[0056] In FIG. 16 the expansion valve 1 is shown in a section along
a plane passing through holes 7, 8. In holes 7, 8 metal collars
103, 104 are fitted. Collars 103, 104 are of a length slightly
greater than the length of holes 7, 8. As soon as the pipes are
mounted at the evaporator side with the mounting bolts inserted
into holes 7, 8, the pipe fixing plate abuts against the evaporator
side end faces of metal collars 103, 104, while plate 95 of
mounting bolt 93 abuts against the opposite end faces of said
collars, so that the plates attached to the opposite end faces of
the expansion valve 1 do not directly contact portions of the resin
body block or pressure vessel 13 where mounting bolts are
tightened. Any stress induced by the tightening of said mounting
bolts is borne by the metal collars 103, 104 to prevent the
application of excessive stress to the pressure vessel 13 made of
resin eliminating the danger of fractures of expansion valve 1 at
the time of mounting the pipes.
[0057] In FIG. 17 identical reference numerals are used to denote
identical elements as appearing in FIG. 11. An insulator 73a having
an L-shaped cross-section is fitted around expansion valve 1 and is
interposed between the elliptic opening of the partition wall 71
and the outer peripheral surface of expansion valve 1 and in close
contact with flange 91 and evaporator casing 72. Consequently, the
gap between partition wall 72 and expansion valve 1 is sealed,
blocking air communication between the vehicle compartment and the
engine compartment. Simultaneously the gap between partition wall
71 and evaporator casing 72 is sealed. By thus forming the flange
91 with the shown configuration and its shown location on the
expansion valve 1 it is possible to provide with ease a sealing
structure for the partition wall 71 separating the vehicle
compartment from the engine compartment.
[0058] In FIG. 18 identical reference numerals are used to denote
elements identical with those appearing in FIG. 11. In FIG. 18
those end faces of flange 91 and evaporator casing 72 facing
partition wall 71 are positioned flush with each other. Between
said end faces and partition 71 a ring-shaped insulator 73b is
simply interposed to provide the necessary sealing. The insulator
73b as used is simple in shape. Also the sealing structure for the
partition wall 71 separating the vehicle compartment from the
engine compartment can be simplified.
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