U.S. patent application number 11/090213 was filed with the patent office on 2005-10-06 for control valve for variable displacement compressor.
This patent application is currently assigned to TGK CO., LTD.. Invention is credited to Hirota, Hisatoshi.
Application Number | 20050220631 11/090213 |
Document ID | / |
Family ID | 34879943 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050220631 |
Kind Code |
A1 |
Hirota, Hisatoshi |
October 6, 2005 |
Control valve for variable displacement compressor
Abstract
To prevent the movable parts of a solenoid of a control valve
for a variable displacement compressor, in which a diaphragm is
used as a pressure-sensing section, from being affected by metal
dust contained in refrigerant. A core, a plunger, and a spring of a
solenoid are accommodated in a bottomed sleeve. A diaphragm is
welded to an open end of the bottomed sleeve under a vacuum
ambience, whereby an assembly that makes the inside a vacuum is
formed. As a result, suction pressure Ps can be sensed as an
absolute pressure with reference to a vacuum. The movable parts of
the solenoid are housed in the vacuum container, so that they are
free from the influence of metal dust contained in refrigerant
circulating through a refrigeration cycle.
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: |
34879943 |
Appl. No.: |
11/090213 |
Filed: |
March 28, 2005 |
Current U.S.
Class: |
417/222.2 ;
417/222.1; 417/440 |
Current CPC
Class: |
F04B 2027/1859 20130101;
F04B 2027/1854 20130101; F04B 27/1804 20130101 |
Class at
Publication: |
417/222.2 ;
417/440; 417/222.1 |
International
Class: |
F04B 001/26; F04B
023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2004 |
JP |
2004-097964 |
Claims
What is claimed is:
1. A control valve for a variable displacement compressor, which is
mounted on the variable displacement compressor for control of
pressure in a gastightly-formed crankcase by sensing suction
pressure by a diaphragm, wherein a core of a solenoid and a plunger
urged in a direction away from the core are accommodated in a
bottomed sleeve, and an open end of the bottomed sleeve is sealed
by the diaphragm such that an inside of the bottomed sleeve is kept
gastight.
2. The control valve according to claim 1, wherein the core is
press-fitted in the bottomed sleeve, and a magnetic gap between the
core and the plunger is adjusted by an amount of press-fitting of
the core into the bottomed sleeve.
3. The control valve according to claim 2, wherein the bottomed
sleeve has a bottom-side portion thereof formed as a part for
press-fitting of the core by reducing a diameter of the bottom-side
portion.
4. The control valve according to claim 1, comprising a shaft
axially extending through the core and having one end thereof fixed
to the plunger, a bearing disposed in contact with a bottom of the
bottomed sleeve and supporting the other end of the shaft, and a
spring having one end thereof engaged with the shaft and the other
end thereof held in abutment with the bearing and urging the
plunger in the direction away from the core, and wherein a position
of the bearing receiving the spring is changed by deforming the
bottom of the bottomed sleeve from outside such that the bottom is
dented, to thereby adjust load of the spring.
5. The control valve according to claim 1, wherein the bottomed
sleeve has a flange portion formed on an open end thereof, the
diaphragm being circumferentially welded to the flange portion
along an entire perimeter thereof to seal the bottomed sleeve, and
a sealing member for sealing between a space from which the
diaphragm receives the suction pressure and the atmosphere is
disposed radially inward of a position where the diaphragm is
welded.
6. The control valve according to claim 1, wherein the diaphragm
comprises a base part formed with a hole in a central portion
thereof and welded to a flange portion formed on the open end of
the bottomed sleeve, a funnel-shaped intermediate connecting part
having an inner periphery welded to an inner periphery of the base
part, and a disk having an outer periphery welded to an outer
periphery of the intermediate connecting part.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS, IF ANY
[0001] This application claims priority of Japanese Application No.
2004-097964 filed on Mar. 30, 2004 and entitled "CONTROL VALVE FOR
VARIABLE DISPLACEMENT COMPRESSOR".
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] The present invention relates to a control valve for a
variable displacement compressor, and more particularly to a
control valve for a variable displacement compressor which is
suitable for controlling refrigerant displacement of a variable
displacement compressor for an automotive air conditioner.
[0004] (2) Description of the Related Art
[0005] A compressor used in a refrigeration cycle of an automotive
air conditioner is driven by an engine whose rotational speed
varies depending on a traveling condition of the vehicle, and hence
incapable of performing rotational speed control. To eliminate the
inconvenience, a variable displacement compressor capable of
changing the discharge amount of refrigerant is generally employed
so as to obtain an adequate refrigerating capacity without being
constrained by the rotational speed of the engine.
[0006] In a typical variable displacement compressor, a wobble
plate is disposed within a gastightly-formed crankcase such that
the inclination angle thereof can be changed, and driven by the
rotational motion of a rotational shaft, for performing wobbling
motion, and pistons caused to perform reciprocating motion in a
direction parallel to the rotational shaft by the wobbling motion
of the wobble plate draw refrigerant from a suction chamber into
associated cylinders, compress the refrigerant, and then discharge
the same into a discharge chamber. In doing this, the inclination
angle of the wobble plate can be varied by changing the pressure in
the crankcase, whereby the stroke of the pistons is changed for
changing the discharge amount of the refrigerant. The control valve
for a variable displacement compressor provides control to change
the pressure in the crankcase.
[0007] In general, the control valve for variably controlling the
displacement of the compressor introduces part of refrigerant
discharged at discharge pressure Pd from the discharge chamber into
the gastightly-formed crankcase, and controls pressure Pc in the
crankcase through control of the amount of refrigerant thus
introduced. The amount of introduced refrigerant is controlled
according to suction pressure Ps in the suction chamber. That is,
the control valve senses the suction pressure Ps, and controls the
flow rate of refrigerant introduced at the discharge pressure Pd
from the discharge chamber into the crankcase, so as to maintain
the suction pressure Ps at a constant level.
[0008] To this end, the control valve is equipped with a
pressure-sensing section for sensing the suction pressure Ps, and a
valve section for causing a passage leading from the discharge
chamber to the crankcase to open and close according to the suction
pressure Ps sensed by the pressure-sensing section. Further, a type
of control valve for a variable displacement compressor, which is
capable of freely externally setting a value of suction pressure Ps
to be assumed at the start of the variable displacement operation,
is equipped with a solenoid that enables the set point of the
pressure-sensing section to be varied by external electric current.
The pressure-sensing section is generally implemented by a bellows,
but there has also been proposed a control valve using a
diaphragm.
[0009] In the control valve having a pressure-sensing section
implemented by a diaphragm, the relative pressure between the
suction pressure Ps and atmospheric pressure is sensed, and hence
due to a change in atmospheric pressure between when the vehicle is
running on a road at a high altitude and when the vehicle is
running on a road at a low altitude, there occurs a control error.
To solve this problem, a control valve has been proposed in which
suction pressure is sensed as an absolute pressure and the control
error due to the difference in altitude is thereby eliminated (see
Japanese Unexamined Patent Publication (Kokai) No. 2004-36596).
[0010] This control valve is formed by arranging a vacuum chamber
sealed by a diaphragm, a valve section for controlling the flow
rate of refrigerant introduced from a discharge chamber into a
crankcase, and a solenoid for setting a value of suction pressure
Ps to be received by the diaphragm, in the mentioned order.
[0011] However, the conventional control valve is configured such
that refrigerant flows through the valve section and the solenoid,
and hence metal dust contained in the refrigerant circulating
through a refrigeration cycle tends to affect the solenoid,
particularly movable parts thereof.
SUMMARY OF THE INVENTION
[0012] The present invention has been made in view of this point,
and an object thereof is to prevent the movable parts of a solenoid
of a control valve for a variable displacement compressor, in which
a diaphragm is used as a pressure-sensing section, from being
adversely affected by metal dust contained in refrigerant.
[0013] To solve the above problem, the present invention provides a
control valve for a variable displacement compressor, which is
mounted on the variable displacement compressor for control of
pressure in a gastightly-formed crankcase by sensing suction
pressure by a diaphragm, wherein a core of a solenoid and a plunger
urged in a direction away from the core are accommodated in a
bottomed sleeve, and an open end of the bottomed sleeve is sealed
by the diaphragm such that an inside of the bottomed sleeve is kept
gastight.
[0014] 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
[0015] FIG. 1 is a central longitudinal cross-sectional view of the
arrangement of a control valve for a variable displacement
compressor, according to a first embodiment of the present
invention.
[0016] FIG. 2 is an enlarged fragmentary cross-sectional view
showing a welded portion of a diaphragm.
[0017] FIG. 3 is an enlarged fragmentary cross-sectional view
showing a press-fitting portion of a bottomed sleeve.
[0018] FIG. 4 is a central longitudinal cross-sectional view of the
arrangement of a control valve for a variable displacement
compressor, according to a second embodiment of the present
invention.
[0019] FIG. 5 is an enlarged exploded cross-sectional view showing
a diaphragm and a bottomed sleeve.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] FIG. 1 is a central longitudinal cross-sectional view of the
arrangement of a control valve for a variable displacement
compressor, according to a first embodiment of the present
invention. FIG. 2 is an enlarged fragmentary cross-sectional view
showing a welded portion of a diaphragm. FIG. 3 is an enlarged
fragmentary cross-sectional view showing a press-fitting portion of
a bottomed sleeve.
[0021] This control valve for a variable displacement compressor
has a valve section provided at an upper location, as viewed in
FIG. 1. The valve section has a body 11, and the body 11 has a side
portion thereof formed with a port 12 for communicating with a
discharge chamber of the variable displacement compressor when the
control valve is mounted in the compressor, to receive discharge
pressure Pd from the discharge chamber. The port 12 has a strainer
13 fixed to the periphery thereof. The port 12 for receiving the
discharge pressure Pd communicates with a port 14 opening in the
center of the top of the body 11, via a refrigerant passage through
the inside of the body 11. The port 14 communicates with a
crankcase of the variable displacement compressor to introduce
controlled pressure Pc into the crankcase.
[0022] In the refrigerant passage via which the port 12 and the
port 14 are communicated through the body 11, a valve seat 15 is
formed integrally with the body 11. In opposed relation to a side
of the valve seat 15, from which the pressure Pc is introduced, a
valve element 16 is axially disposed in a manner movable to and
away from the valve seat 15. The valve element 16 is integrally
formed with a shaft 17 which extends downward as viewed in the
figure, through a valve hole such that it is axially movably held
by the body 11. The discharge pressure Pd from the discharge
chamber is introduced into a small-diameter portion which connects
between the valve element 16 and the shaft 17. The outer diameter
of the shaft 17 is set to be equal to the inner diameter of the
valve hole forming the valve seat 15 such that the
pressure-receiving area of the valve element 16 is equal to that of
the shaft 17. This causes a force of the discharge pressure Pd
which acts on the valve element 16 in the upward direction as
viewed in the figure to be cancelled out by a force acting on the
shaft 17 in the downward direction as viewed in the figure, so as
to prevent the control of the valve section from being adversely
affected by the discharge pressure Pd which is high in pressure
level.
[0023] The valve element 16 is urged by a spring 18 in the
valve-closing direction, and load of the spring 18 is adjusted by
an adjustment screw 19 screwed into the port 14.
[0024] Further, a port 20 communicating with a suction chamber of
the variable displacement compressor to receive suction pressure Ps
is formed in a lower portion of the body 11 as viewed in the
figure.
[0025] A pressure-sensing section and a solenoid are arranged below
the body 11, as viewed in the figure. More specifically, on the
lower end of the body 11, there is disposed an assembly that is
formed by accommodating a plunger 22, a core 23, and a spring 24,
as component elements of the solenoid, in a bottomed sleeve 21
which forms a vacuum container, and sealing the opening of the
bottomed sleeve 21 with a metal diaphragm 25, and outside the
bottomed sleeve 21, there are arranged a coil 26, a ring 27, a case
28, and a handle 29, which are made of magnetic substances and
constitute a yoke for establishing a magnetic circuit.
[0026] In the bottomed sleeve 21, the core 23 is rigidly
press-fitted and the plunger 22 is axially movably disposed on a
side of the core 23 toward the valve section. The plunger 22 is
rigidly press-fitted on one end of a shaft 30 axially extending in
the center of the core 23, and the other end of the shaft 30 is
supported by a bearing 31 slidably disposed in the core 23. A stop
ring 32 is fitted on an intermediate portion of the shaft 30, and a
spring-receiving member 33 is formed such that the upward movement
thereof as viewed in the figure is restricted by the stop ring 32.
The spring 24 is interposed between the spring-receiving member 33
and the bearing 31. The plunger 22 is urged by the spring 24 via
the shaft 30 in a direction away from the core 23. It should be
noted that load of the spring 24 can be changed by externally
adjusting the axial position of the bearing 31. More specifically,
in final adjustment after assembly of the control valve for a
variable displacement compressor, the bottom of the bottomed sleeve
21 is pushed to be deformed inward, whereby the axial position of
the bearing 31 in abutment with the bottom is changed to adjust the
load of the spring 24. Thus, the set point of the control valve is
adjusted.
[0027] The bottomed sleeve 21 accommodating the plunger 22 and the
core 23 as described above is sealed by welding the diaphragm 25 to
a flange portion formed on the open end of the bottomed sleeve 21.
For example, as shown in detail in FIG. 2, the diaphragm 25 is
placed on the flange portion of the bottomed sleeve 21 and
circumferentially welded to the flange portion along the entire
perimeter thereof via an annular patch 34 by laser welding,
resistance welding, or the like, under vacuum atmosphere, whereby
the gastight assembly is formed such that the inside thereof
maintained under vacuum.
[0028] This assembly is fixed to the body 11 via a reinforcing ring
35 by positioning the flange portion of the bottomed sleeve 21 in a
recess formed in the lower end of the body 11 and caulking the
peripheral wall of the recess. Then, the case 28 accommodating the
coil 26 is fixed to the body 11 by caulking an upper end 36 of the
case 28.
[0029] Further, in mounting the assembly to the body 11, an O ring
37 is interposed between the patch 34 and the body 11 so as to seal
between a chamber receiving the suction pressure Ps and the
atmosphere, such that the center of the solid part of the O ring 37
is positioned at a location radially inward of a weld line 38.
Thus, stress generated by the displacement of the diaphragm is
prevented from reaching the weld line 38 which has become fragile
due to a change in material caused by the welding.
[0030] The bottomed sleeve 21 is formed by deep-drawing of a
stainless steel material, such as SUS304. The bottomed sleeve 21 is
required to be formed of a non-magnetic material so as to prevent
the bottomed sleeve 21 from attracting the plunger 22 during
energization of the solenoid and thereby increasing sliding
resistance. However, SUS304 is known to have a property that when
subjected to strong cold working, it acquires magnetism due to a
partial change in its metallic crystal structure. In such a case,
the bottomed sleeve 21 is made non-magnetic again by subjecting the
same to annealing.
[0031] On the other hand, the bottomed sleeve 21 also includes a
portion which is desirably magnetic in view of the magnetic
circuit. The portion is in an area in which is located the handle
29 magnetically connecting between the core 23 and the case 28. For
this reason, a part of the bottom-side portion of the bottomed
sleeve 21 which is formed by deep drawing to extend straight, is
further drawn as shown in detail in FIG. 3. More specifically, the
part of the bottom-side portion of the bottomed sleeve 21 is
subjected to strong cold working such that its diameter is reduced,
whereby the part of the bottom-side portion can be made magnetic to
increase magnetic permeability. The drawn part of the bottom-side
portion of the bottomed sleeve 21 has its diameter reduced to form
a press-fitting portion 39 used for rigidly press-fitting the core
23 in the bottomed sleeve 21. In this press-fitting portion 39, the
amount of press-fitting of the core 23 is adjusted to adjust the
magnitude of the magnetic gap between the core 23 and the plunger
22.
[0032] It should be noted that when the bottomed sleeve 21 is made
of a stainless steel, the diaphragm 25 is also made of a stainless
steel material for springs, called SUS304CSP, in view of welding.
Of course, the materials of the bottomed sleeve 21 and the
diaphragm 25 are not limited to the stainless steel materials, but
it is also possible to use copper for the bottomed sleeve 21, and
beryllium copper for the diaphragm 25.
[0033] In the arrangement described above, the ring 27, the case
28, and the handle 29 are formed of magnetic materials to serve as
the yoke of the magnetic circuit of the solenoid. Magnetic lines of
force generated by the coil 26 pass through the magnetic circuit
formed by the case 28, the ring 27, the plunger 22, the core 23,
and the handle 29.
[0034] FIG. 1 shows a state of the control valve for a variable
displacement compressor, in which the solenoid is not energized and
the suction pressure Ps is high, i.e. a state in which an air
conditioner is not operating. Since the suction pressure Ps is
high, the diaphragm 25 is displaced downward, as viewed in the
figure, against the load of the spring 24 to bring the plunger 22
into contact with the core 23. As a result, the valve element 16
held in contact with the diaphragm 25 via the shaft 17 is seated on
the valve seat 15 by being urged in the valve-closing direction by
the spring 18, and hence the valve section is in its fully-closed
state.
[0035] Now, assuming that the automotive air conditioner is started
and the variable displacement compressor is driven for rotation by
an engine, the variable displacement compressor whose control valve
is in its fully-closed state is operated with the maximum
displacement.
[0036] When the variable displacement compressor continues to
operate with the maximum displacement to make the suction pressure
Ps from the suction chamber sufficiently low, the diaphragm 25,
sensing the suction pressure Ps, moves upward as viewed in the
figure. With this upward motion of the diaphragm 25, the plunger 22
moves away from the core 23 in a state abutted to the diaphragm 25.
At this time, if control current supplied to the solenoid coil 26
is set to a value of cooling capacity corresponding to a
temperature set for air conditioning, the plunger 22 stops in a
position where the suction pressure Ps, the loads of the springs 18
and 24, and the attractive force of the solenoid are balanced. This
causes the valve element 16 held in contact with the diaphragm 25
via the shaft 17 to be pushed upward by the diaphragm 25 to move
away from the valve seat 15 so as to be set to a predetermined
valve lift. Therefore, refrigerant at the discharge pressure Pd is
introduced into the crankcase at a flow rate controlled to a value
dependent on the valve lift, whereby the variable displacement
compressor is controlled to perform operation with the displacement
corresponding to the control current.
[0037] When the control current supplied to the coil 26 of the
solenoid is constant, the diaphragm 25 senses the suction pressure
Ps as an absolute pressure to thereby control the valve lift of the
valve section. For example, when the refrigeration load increases
to make the suction pressure Ps high, the diaphragm 25 is displaced
downward as viewed in the figure, so that the valve element 16 is
also moved downward to decrease the valve lift of the valve
section, causing the variable displacement compressor to operate in
a direction of increasing the displacement. On the other hand, when
the refrigeration load decreases to make the suction pressure Ps
low, the diaphragm 25 is displaced upward as viewed in the figure
to increase the valve lift of the valve section, causing the
variable displacement compressor to operate in a direction of
decreasing the displacement. Thus, the control valve controls the
displacement of the variable displacement compressor such that the
suction pressure Ps becomes equal to a value set by the
solenoid.
[0038] FIG. 4 is a central longitudinal cross-sectional view of the
arrangement of a control valve for a variable displacement
compressor, according to a second embodiment of the present
invention. FIG. 5 is an enlarged exploded cross-sectional view
showing a diaphragm and a bottomed sleeve. It should be noted that
component elements in FIG. 4 identical or similar in function to
those in FIG. 1 are designated by identical reference numerals, and
detailed description thereof is omitted.
[0039] The control valve for a variable displacement compressor of
the second embodiment is distinguished from the control valve for a
variable displacement compressor of the first embodiment in that
the shape of the diaphragm 25 is modified. As shown in detail in
FIG. 5, the present diaphragm 25 comprises three component parts.
First, a base part 40 having a largest diameter has a central
portion thereof formed with a hole, and is welded to the flange
portion of the bottomed sleeve 21. An intermediate connecting part
41 in the form of a funnel is disposed on the base part 40, and a
disk 42 is disposed on the intermediate connecting part 41 in a
manner covering the upper opening of the same. The base part 40,
the intermediate connecting part 41, and the disk 42 are formed
e.g. of beryllium copper. The base part 40 and the intermediate
connecting part 41 have inner peripheral portions thereof welded to
each other along the entire perimeters thereof e.g. by forming a
protuberance along the inner peripheral edge of the base part 40
and projection-welding the inner peripheral portions of the two,
and the intermediate connecting part 41 and the disk 42 have outer
peripheral portions thereof welded to each other along the entire
perimeters thereof e.g. by laser-welding. The diaphragm 25 is thus
formed. In this case, the bottomed sleeve 21 is formed of the same
copper material as the diaphragm 25, and the base part 40 of the
diaphragm 25 is welded to the flange portion of the bottomed sleeve
21 along the entire perimeter thereof under vacuum atmosphere e.g.
by laser-welding.
[0040] This diaphragm 25 can have a larger stroke in the direction
of displacement than that of the control valve of the first
embodiment in which the pressure-sensing section is formed by a
single thin metal plate, and hence the control range of the valve
section can be expanded.
[0041] The control valve for a variable displacement compressor,
according to the present invention, is configured such that an
assembly is separately formed by sealing the bottomed sleeve
containing the movable parts of the solenoid with the diaphragm
such that the assembly has a vacuum inside, and the assembly is
fixed to the body of the valve section. Further, the assembly is
fixed to the body of the valve section with the solenoid coil
arranged therearound. Therefore, the control valve is advantageous
in its ease of construction.
[0042] 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.
* * * * *