Control valve for variable capacity compressors

Details Control valve for variable capacity compressors Control valve for variable capacity compressors

2000-09-27

2002-11-26

Freay, Charles G. (Department: 3746)

Pumps

Condition responsive control of drive transmission or pump...

Adjustable cam or linkage

Reexamination Certificate

active

06485267

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a control valve for a variable capacity compressor to be employed in air conditioners for vehicles, etc., and in particular to a control valve for a variable capacity compressor, which is designed to supply, upon requirements, a coolant gas from a discharge pressure region to an intermediate pressure region.
A variable capacity compressor is generally provided with a cylinder, a piston, a wobble plate, etc., and is employed for compressing and discharging a coolant gas in an air conditioner of vehicles. There is known a variable capacity compressor comprising a coolant gas passage for communicating a discharge pressure region with a crankcase, and designed such that the quantity of coolant gas to be discharged can be changed in conformity with changes in inclination angle of the wobble plate which can be effected through an adjustment of the pressure inside the crankcase. The adjustment of pressure inside the crankcase is performed by feeding a high pressure compressed coolant gas from the discharge pressure region to the crankcase while adjusting the opening degree of a control valve disposed at an intermediate portion of the coolant gas passage.
As one example of the aforementioned control valve, a control valve
100
′ for a variable capacity compressor (hereinafter referred to simply as a control valve) as shown in
FIG. 8
is known (see Japanese Patent Unexamined Publication (Kokai) H11-218078). This control valve
100
′ is disposed neighboring on the rear housing
3
of the variable capacity compressor
1
and is airtightly placed inside space
84
of the rear housing
3
, the airtightness thereof being effected by means of O-rings
121
a
′,
121
b
′ and
131
b′.
As shown in
FIG. 8
, this control valve
100
′ is constituted by a main body
120
′, solenoid magnetization portion
130
′ and pressure sensitive portion
145
′, wherein the solenoid magnetization portion
130
′ is disposed at the center, and the main body
120
′ and pressure sensitive portion
145
′ are respectively disposed on both sides of the solenoid magnetization portion
130
′.
The solenoid magnetization portion
130
′ is provided on the outer circumference thereof with a solenoid housing
131
′, in which a solenoid
131
A′, a plunger
133
′ to be moved up and down by the magnetization of solenoid
131
A′, and a suction member
141
′ are housed. A plunger chamber
130
a
′ housing the plunger
133
′ is communicated with suction coolant port
129
′ attached to the main body
120
′.
The pressure sensitive portion
145
′ is disposed below the solenoid housing
131
′ and is provided therein with pressure sensitive chamber
145
a
′, in which a bellows
146
′ and a spring
159
′ which are designed to actuate plunger
133
′ via a stem
138
′ are positioned.
The main body
120
′ is provided with valve chamber
123
′, and a ball valve
132
′ to be actuated by the plunger
133
′ through a push rod
135
′ is disposed inside the valve chamber
123
′, to which a coolant gas of high discharge pressure Pd is designed to be introduced. The valve chamber
123
′ is provided at the bottom surface thereof with a valve bore
125
′ communicating with a crankcase coolant port
128
′, and the upper space of the valve chamber
123
′ is closed by means of a stopper
124
′. This stopper
124
′ is provided at the central portion thereof with a discharging coolant-introducing port
126
a
′ and also provided at the bottom portion thereof with valve-closing spring
127
′ for urging the valve
132
′ to move toward the bottom side of the valve chamber
123
′.
The main body
120
′ is further provided with a port
114
′ which is communicated via a passageway
57
with a crankcase constituting an intermediate pressure region of the compressor
1
and also with a chamber pressure Pc of the crankcase. Therefore, when the valve bore
125
′ is opened by means of the valve
132
′, a high-pressure coolant gas that has been introduced into the valve chamber
123
′ is allowed to be introduced via the port
114
′ and the passageway
57
into crankcase. The suction coolant port
129
′ which is communicated via a passageway
80
with a suction pressure region of the compressor
1
and is designed to receive a suction pressure Ps of the suction pressure region is not only communicated with the pressure sensitive chamber
145
a
′, but also communicated with a suction pressure-introducing space
85
formed between the rear housing
3
and the solenoid housing
131
′.
The plunger
133
′ disposed inside the solenoid housing
131
′ is slidably sustained by a pipe
136
′, which is air-tightly contacted via a couple of O-rings
134
a
′ and
134
b
′ with one end of the main body
120
′. Further, a valve-opening spring
144
′ for urging the plunger
133
′ to move away from the suction member
141
′ is interposed between the plunger
133
′ and the suction member
141
′. Out of a pair of stoppers
147
′ and
148
′ disposed inside the bellows
146
′ arranged inside pressure sensitive chamber
145
a
′, only the stopper
147
′ is attached to the lower end
138
b
′ of the stem
138
′, thereby enabling the stopper
147
′ to move close to or away from the stopper
148
′. Additionally, a spring
150
′ for urging the stopper
147
′ to move away from the suction member
141
′ is interposed between the stopper
147
′ and the suction member
141
′.
The pipe
154
′ functions to form the pressure sensitive chamber
145
a
′ and is air-tightly secured via an
0
-ring
156
′ to the solenoid housing
131
′, and an adjusting screw holder
152
′ is fixedly fitted in this pipe
154
′. This adjusting screw holder
152
′ is provided therein an adjusting screw
156
′ for adjusting the strength of the bellows
146
′. The adjusting screw
156
′ is air-tightly contacted via an
0
-ring
157
′ with the adjusting screw holder
152
′ and the distal end thereof is contacted with the stopper
148
′ of the bellows
146
′.
By the way, a cord
158
′ for supplying a predetermined magnetization current that will be controlled by a controlling computer (not shown) is connected with the solenoid
131
A′.
When solenoid
131
A′ of control valve
100
′ is magnetized, the plunger
133
′ is pulled toward the suction member
141
′ against the urging force of the valve-opening spring
144
′, thereby causing the push rod
135
′ connected with the plunger
133
′ to move. As a result, the valve
132
′ is moved in the direction to close the valve bore
125
′ of the main body
120
′. When the suction pressure Ps inside the pressure sensitive chamber
145
a
′ becomes higher, bellows
146
′ is forced to contract in conformity with the suction pressure Ps, so that the direction of this shrinkage becomes identical with the sucking direction of the plunger
133
′ to be effected by the solenoid
131
A′. This displacement of bellows
146
′ is followed by the valve
132
′, thereby reducing the opening degree of the valve bore
125
′. As a result, the quantity of high-pressure coolant gas to be introduced into the crankcase through the port
114
′ and passageway
57
after being introduced into the interior of the valve chamber
123
′ via the discharging coolant-introducing port
126
a
′ from the discharge pressure region is caused to decrease (crankcase pressure Pc is lowered), thereby increasing the angle of inclination of the wobble plate of the compressor
1
. Whereas, whe

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