U.S. patent application number 11/826250 was filed with the patent office on 2007-11-15 for control valve for variable displacement compressor.
This patent application is currently assigned to TGK CO., LTD.. Invention is credited to Hisatoshi Hirota.
Application Number | 20070264134 11/826250 |
Document ID | / |
Family ID | 36677503 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070264134 |
Kind Code |
A1 |
Hirota; Hisatoshi |
November 15, 2007 |
Control valve for variable displacement compressor
Abstract
To provide a control valve for variable displacement compressor
employing ON/OFF control, which is capable of taking measures for
occurrence of an abnormally high pressure. When a solenoid is OFF,
a spring causes a movable core to move a stopper in a direction
away from a stationary core and to thereby separate a shaft fixed
to the stopper from a valve seat, resulting in opening the control
valve. When the solenoid is ON, the movable core is attracted by
the stationary core by a stroke longer than that of the shaft, and
a spring causes the shaft to seat on the valve seat, resulting in
closing the control valve. If a discharge pressure Pd increases to
an abnormally high pressure, a differential pressure between the
discharge pressure Pd and a pressure Pc in a crankcase pushes the
shaft while compressing the spring, so that the discharge pressure
Pd flows out to the crankcase. Therefore, the pressure Pc in the
crankcase increases and the variable displacement compressor shifts
to operate at a minimum discharge capacity, resulting in decreasing
the abnormally high pressure.
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: |
36677503 |
Appl. No.: |
11/826250 |
Filed: |
July 13, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP05/22845 |
Dec 13, 2005 |
|
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11826250 |
Jul 13, 2007 |
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Current U.S.
Class: |
417/222.2 |
Current CPC
Class: |
F04B 2027/1854 20130101;
F04B 2027/1827 20130101; F04B 27/1804 20130101 |
Class at
Publication: |
417/222.2 |
International
Class: |
F04B 1/26 20060101
F04B001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2005 |
JP |
2005-007701 |
Claims
1. A control valve for variable displacement compressor for
changing a discharge capacity by controlling a flow rate of
refrigerant to be introduced from a discharge chamber to a
crankcase of the variable displacement compressor with ON/OFF
control, the control valve comprising: a valve section where a
valve element is arranged on a downstream side of a valve hole for
opening and closing the valve hole into which the refrigerant that
is discharged from the discharge chamber is introduced; and a
solenoid for opening the valve section in a deenergized state and
for closing the valve section in an energized state, wherein, in
the solenoid, the valve element is held at a valve-opening position
by a first spring imposing an urging force in a valve-opening
direction in the deenergized state and a second spring imposing an
urging force in a valve-closing direction, and is held at a
valve-closing position by the second spring in the energized state,
the valve element receiving a discharge pressure of the refrigerant
introduced from the discharge chamber in the valve-opening
direction.
2. The control valve for variable displacement compressor according
to claim 1, wherein, in the solenoid, a stroke of a movable core
moving to be attracted by a stationary core in the energized state
from a position where the valve element is positioned at the
valve-opening position is set longer than a stroke of the valve
element moving to the valve-closing position from the valve-opening
position in the energized state.
3. The control valve for variable displacement compressor according
to claim 2, wherein, in the solenoid, the stationary core, the
first spring, the movable core, a stopper, and the second spring
are arranged from a side of the valve section in this order on a
same axis as the valve hole, and a shaft that is loosely fitted in
the stationary core and the movable core in a manner axially
extending therethrough has one end serving as the valve element for
opening and closing the valve hole and another end fixed to the
stopper.
Description
[0001] This application is a continuing application, filed under 35
U.S.C. .sctn.111(a), of International Application
PCT/JP2005/022845, filed Dec. 13, 2005, it being further noted that
priority is based upon Japanese Patent Application No. 2005-007701,
filed Jan. 14, 2005.
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] This invention relates to a control valve for variable
displacement compressor, and more particularly to a control valve
for variable displacement compressor, which controls a discharge
capacity of a variable displacement compressor of an automotive air
conditioning system with ON/OFF control.
[0004] (2) Description of the Related Art
[0005] A compressor that is used in a refrigeration cycle of an
automotive air conditioning system is incapable of controlling the
rotational speed because the compressor uses as a driving source an
engine that varies its rotational speed according to a running
condition. Therefore, in general, a variable displacement
compressor is employed which is designed to be capable of changing
a discharge capacity of refrigerant in order to secure an adequate
cooling capacity, irrespective of the rotational speed of the
engine.
[0006] In general, in a variable displacement compressor, a
wobbling plate, which is provided at a variable inclination angle
in an airtight crankcase, is driven and wobbles by rotations of a
rotating shaft, this wobbling plate wobbling makes a piston move
back and forth in parallel to the rotating shaft, and this moving
piston introduces refrigerant of a suction chamber into a cylinder
where the refrigerant is compressed and is discharged to a
discharge chamber. In this operation, by controlling the pressure
in the crankcase, the inclination angle of the wobbling plate can
be changed by a pressure difference received on the both ends of
the piston. This angle change causes the stroke of the piston to
vary, thereby changing the discharge capacity of the refrigerant. A
control valve for variable displacement compressor has a function
of changing the pressure in the crankcase.
[0007] In general, such a control valve for controlling a discharge
capacity of a variable displacement compressor partly introduces
refrigerant of a discharge pressure Pd discharged from a discharge
chamber, into an airtight crankcase. By controlling the introducing
rate of the refrigerant, a pressure Pc in the crankcase is
controlled. For example, a known control valve for variable
displacement compressor controls a flow rate of refrigerant to be
introduced into a crankcase according to a differential pressure
between a discharge pressure Pd in a discharge chamber and a
suction pressure Ps in a suction chamber (For example, refer to
Japanese Unexamined Patent Publication No. 2001-132650 (paragraphs
[0043] to [0045], FIG. 4)).
[0008] This control valve for variable displacement compressor
senses a differential pressure between the discharge pressure Pd in
the discharge chamber and the suction pressure Ps in the suction
chamber, and controls a flow rate of refrigerant of the discharge
pressure Pd to be introduced from the discharge chamber to the
crankcase such that the differential pressure becomes equal to a
differential pressure which is set by a solenoid, resulting in
maintaining a fixed discharge capacity of refrigerant discharged
from the variable displacement compressor.
[0009] However, there arises a problem that such a control valve
for variable displacement compressor has a complex structure and is
therefore expensive. Another problem is that, in the refrigeration
cycle which uses carbon dioxide whose working pressure is very high
as a refrigerant, the variable displacement compressor may be
broken when the high pressure section in the refrigeration cycle
has become an abnormal high pressure, in the case where a failure
in a control circuit for controlling the control valve for variable
displacement compressor or a pressure sensor for sensing a
refrigerant pressure, for example, ahs caused a malfunction of the
control valve for variable displacement compressor.
SUMMARY OF THE INVENTION
[0010] This invention has been made in view of the foregoing and
intends to provide a control valve for variable displacement
compressor, which has a simple structure and is capable of
preventing the variable displacement compressor from being broken
due to an abnormally high pressure.
[0011] To solve the above problems, there has been provided a
control valve for variable displacement compressor that controls a
flow rate of refrigerant to be introduced from a discharge chamber
to a crankcase of the variable displacement compressor with ON/OFF
control in order to thereby change a discharge capacity. This
control valve comprises: a valve section where a valve element is
arranged on a downstream side of a valve hole for opening and
closing the valve hole, into which the refrigerant that is
discharged from the discharge chamber is introduced; and a solenoid
for opening the valve section in a deenergized state and for
closing the valve section in an energized state. In the solenoid,
the valve element that receives a discharge pressure of the
refrigerant introduced from the discharge chamber in a
valve-opening direction is held at a valve-opening position by a
first spring imposing an urging force in the valve-opening
direction in the deenergized state and a second spring imposing an
urging force in a valve-closing diction, and the valve element is
held at a valve-closing position by the second spring in the
energized state.
[0012] The above and other objects, features and advantages of the
present invention will becomes 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 central longitudinal cross-sectional view
showing a construction of a control valve for variable displacement
compressor.
[0014] FIG. 2 is a central longitudinal cross-sectional view
showing an operating state of the control valve for variable
displacement compressor when a solenoid is energized.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Hereinafter, a preferred embodiment of the present invention
will be described with reference to accompanying drawings in
detail.
[0016] FIG. 1 is a central longitudinal cross-sectional view
showing a construction of a control valve for variable displacement
compressor. FIG. 2 is a central longitudinal cross-sectional view
showing an operating state of the control valve for variable
displacement compressor when a solenoid is energized.
[0017] This control valve for variable displacement compressor has
a body 10 of a valve section, as illustrated on the upper side of
the figure. This body 10 has a port 11 for receiving a discharge
pressure Pd at the upper central part of the body 10, and a port 12
through which a controlled pressure Pc is delivered to a crankcase.
The port 11 and the port 12 communicate with each other inside the
body 10. An extending portion from the port 11 forms a valve hole,
and a portion that is open in an internal space where the valve
hole communicates with the port 12 serves as a valve seat 13.
[0018] Under the body 10, a solenoid is disposed. This solenoid has
a stationary core 14 which is press-fitted to the body 10 from the
bottom side of the figure. The lower part of this stationary core
14 is engaged with a bottomed sleeve 15. The bottomed sleeve 15 is
welded to the stationary core 14 and the inside of the bottomed
sleeve 15 is held at the airtight condition. Inside the bottomed
sleeve 15, a movable core 16 is disposed in an axially movable
manner and is urged by a spring 17 in a direction away from the
stationary core 14.
[0019] In addition, in this solenoid, a shaft 18 is loosely fitted
in the stationary core 14 and the movable core 16 in a manner
axially extending therethrough. The top end of the shaft 18, as
viewed in the figure, forms a valve element of the valve section
that can be moved to and away from the valve seat 13 of the valve
section. To the bottom end of the shaft 18, as viewed in the
figure, a stopper 19 is fixed. Between the stopper 19 and the
bottom of the bottomed sleeve 15, a spring 20 is disposed to urge
the shaft 18 in a direction toward the valve seat 13. The stopper
19 has an outer diameter larger than the inner diameter of the
central opening of the movable core 16 where the shaft 18 is
loosely fitted. Therefore, while the movable core 16 is separated
from the stationary core 14 by the urging force of the spring 17,
the stopper 19 is brought into contact with the movable core 16 by
the urging force of the spring 20. While the movable core 16 is
attracted by the stationary core 14, the top end of the shaft 18
(valve element) is seated on the valve seat 13 by the urging force
of the spring 20, so that the stopper 19 is separated from the
movable core 16.
[0020] Then, a coil 21 is disposed around the outer circumference
of the bottomed sleeve 15, a yoke 22 and a plate 23, both made of
magnetic material, are disposed so as to cover the coil 21, and a
harness is drawn to outside through the plate 23 for power supply
to the coil 21. When this control valve for variable displacement
compressor is mounted in the variable displacement compressor, an
O-ring 25 disposed around the body 10 at an upper position than the
port 12 prevents a high discharge pressure Pd from leaking to the
medium pressure port 12, and an O-ring 26 disposed around the
stationary core 14 seals between the medium pressure port 12 and
atmosphere.
[0021] The control valve for variable displacement compressor as
constructed above operates as an ON/OFF valve where the valve
section is opened and closed according to the supply of pulse
current to the solenoid. That is, when the solenoid is deenergized
where no current is present in the coil 21, the movable core 16 is
separated from the stationary core 14 by the spring 17 having a
stronger spring force than the spring 20, as shown in FIG. 1. At
this time, the movable core 16 pushes the stopper 19 downward, as
viewed in the figure, against the urging force of the spring 20,
and the top end of the shaft 18 (valve element) is separated from
the valve seat 13, so that the control valve for variable
displacement compressor is in open state.
[0022] When the solenoid is energized where the coil 21 carries
current, the movable core 16 is attracted by the stationary core 14
against the urging force of the spring 17, as shown in FIG. 2.
Thereby, the shaft 18 is pushed upward by the spring 20, as viewed
in the figure, and the valve element of its top end is seated on
the valve seat 13, so that the control valve for variable
displacement compressor is in closed state. At this time, a stroke
of the movable core 16 moving to be attracted by the stationary
core 14 is set longer than a stroke of the top end of the shaft 18
moving to be seated on the valve seat 13. Therefore, while the
control valve for variable displacement compressor is in closed
state, the stopper 19 fixed to the shaft 18 is separated from the
movable core 16.
[0023] As described above, this control valve for variable
displacement compressor operates by ON/OFF pulse current supplied
to the coil 21. When the solenoid is deenergized, the shaft 18
moves to a position where the spring 17 is balanced with the spring
20, so that the control valve is in open state. When the solenoid
is energized, the control valve is in closed state by the urging
force of the spring 20. A flow rate of refrigerant to be supplied
to the crankcase is controlled by changing a duty cycle of pulse
current.
[0024] Next explanation is about how the control valve for variable
displacement compressor operates under the abnormal condition due
to some trouble in a control device controlling the control valve
for variable displacement compressor or a sensor connected to the
control device.
[0025] If the trouble causes the solenoid to keep the OFF state,
the control valve for variable displacement compressor is held in
the open state. In this case, the variable displacement compressor
operates at a minimum discharge capacity, and therefore the
pressure of the refrigeration cycle does not abnormally
increase.
[0026] If the trouble causes the solenoid to keep the ON state, on
the contrary, the control valve for variable displacement
compressor is held in the closed state. Therefore, the continuous
operation of the variable displacement compressor at a maximum
discharge capacity makes pressure high abnormally at a high
pressure section in the refrigeration cycle. At this time, in the
control valve for variable displacement compressor, the port 11
receives a high discharge pressure Pd while the port 12 has a
medium pressure Pc. Since the port 12 communicates with the inside
of the bottomed sleeve 15 with the movable core 16 contained
therein, through a clearance between the stationary core 14 and the
shaft 18, the pressure in the bottomed sleeve 15 is equal to the
pressure Pc. That is, the shaft 18 receives the discharge pressure
Pd in the valve-opening direction at its top end serving as the
valve element, and also receives the load of the spring 20 and the
pressure Pc in the valve-closing direction.
[0027] As a result of the variable displacement compressor
operating at the maximum discharge capacity in this condition, the
discharge pressure Pd increases to an abnormally high pressure such
that a differential pressure between the discharge pressure Pd and
the pressure Pc in the crankcase exceeds a predetermined pressure
(for example, 10 MPa), and a force pushing the shaft 18 in the
valve-opening direction becomes larger. Thereby the shaft 18 moves
in the valve-opening direction while compressing the spring 20,
with the result that the control valve for variable displacement
compressor is in open state.
[0028] In short, in the control valve for variable displacement
compressor, when the discharge pressure Pd in the variable
displacement compressor abnormally increases, the shaft 18 senses
it and moves in the valve-opening direction, so that the high
pressure flows out to the crankcase. Thereby, the variable
displacement compressor shifts to operate at the minimum discharge
capacity, which decreases the discharge pressure Pd, thus making it
possible to prevent breakdown caused by the abnormally high
pressure.
[0029] The above embodiment shows an example where the shaft 18 is
loosely fitted in the stationary core 14 and the movable core 16 in
a manner axially extending therethrough. It is preferable that
bearings are disposed in the vicinity of both ends of the shaft 18
for positioning the shaft 18 on the same axis as the port 11 and
the stationary core 14.
[0030] A control valve for variable displacement compressor of the
present invention opens a valve section by a differential pressure
between a discharge pressure and a pressure to be introduced into a
crankcase when the discharge pressure increases to an abnormally
high pressure. Therefore, the high pressure flows out to the
crankcase, which shifts the variable displacement compressor to
operate at a minimum discharge capacity and decreases the
abnormally high pressure. As a result, at least the variable
displacement compressor can be prevented from being broken due to
the abnormally high pressure, which is an advantage.
[0031] 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.
* * * * *