Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2002-04-01
2003-09-30
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C251S129020, C251S129150
Reexamination Certificate
active
06626645
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control valve for variable capacity compressors used in air conditioners of vehicles and the like and, more particularly, to a control valve for variable capacity compressors that controls the supply of a coolant gas in the interior of a crankcase from a discharge-pressure region as required.
2. Description of the Prior Art
Conventionally, variable capacity compressors provided with a cylinder, a piston, a wobble plate, etc. have been used, for example, in compressing and delivering a coolant gas of an air conditioner for automobiles. A known variable capacity compressor of this type is provided with a coolant-gas passage that communicates with a discharge-pressure region and a crankcase, and changes the inclination angle of the wobble plate by adjusting the pressure in the interior of the crankcase thereby to change discharge capacity. The pressure adjustment in the interior of the crankshaft is performed by supplying a high-pressure compressed coolant gas from the discharge-pressure region to the crankcase by the opening adjustment of a control valve provided within the coolant-gas passage.
For example, a control valve
100
′ as shown in
FIGS. 10 and 11
is known (Japanese Patent Application Laid-Open Nos. 9-268973 and 9-268974) as a control valve for such a variable capacity compressor as described above. This control valve
100
′ is provided on the side of the rear housing
210
of a variable capacity compressor
200
, and performs the pressure adjustment of a crankcase
231
within a front housing
230
, which is installed in connection with a cylinder block
220
of the variable capacity compressor
200
.
In the interior of the crankcase
231
, a wobble plate
240
is supported by a driving shaft
250
in a manner such that the wobble plate
240
can slide in the axial direction of the driving shaft
250
and tilt. A guide pin
241
of this wobble plate
240
is slidably supported by a support arm
252
of a rotary support
251
. Also, the wobble plate
240
is connected, via a pair of shoes
242
, to a piston
260
, which is slidably disposed within a cylinder bore
221
.
The wobble plate
240
rotates in the directions indicated by an arrow shown in
FIG. 10
according to a difference between the suction pressure Ps in the cylinder bore
221
and the crankcase pressure Pc in the crankcase
231
, and changes the inclination angle of the wobble plate
240
itself. On the basis of the inclination angle of the wobble plate
240
, the stroke width of forward and backward movements of the piston
260
in the cylinder bore
221
is determined. And a blocking element
270
that abuts against the middle portion of the wobble plate
240
moves forward and backward in a housing hole
222
as the wobble plate
240
rotates in the directions indicated by the arrow.
In the interior of the rear housing
210
, suction chambers
211
a
,
211
b
, which constitute a suction-pressure region, and discharge chambers
212
a
,
212
b
, which constitute a discharge-pressure region, are defined and formed. When the piston
260
moves forward and backward on the basis of the rotation of the wobble plate
240
, a coolant gas in the suction chamber
211
a
is sucked into the interior of the cylinder bore
221
from a suction port
213
, is compressed to a prescribed pressure and is then delivered from a discharge port into the discharge chamber
212
a.
Furthermore, a suction passage
215
formed in the center portion of the rear housing
210
communicates with the housing hole
222
and, at the same time, the suction passage
215
communicates also with the suction chamber
211
b
via a through hole
216
. When the wobble plate
240
moves to the side of the blocking element
270
, the blocking element
270
moves to the side of the suction passage
215
and blocks the through hole
216
.
The upper side of the control valve
100
′ communicates with the suction passage
215
via a pressure-detection passage
217
that introduces the suction pressure Ps into the interior of the control valve
100
′. Furthermore, the discharge chamber
212
b
and the crankcase
231
communicate with each other via air supply passages
218
,
219
of the control valve
100
′. The air supply passages
218
,
219
are opened and closed by a valve element
106
′ of the control valve
100
′.
The discharge pressure Pd of the discharge chamber
212
b
is introduced into a valve chamber port
113
′ via the air supply passage
218
. The pressure Pc within the crankcase is introduced into the air supply passage
219
via a valve hole port
114
′. The suction pressure Ps is introduced into a suction pressure introduction port
115
′ via the pressure-detection passage
217
.
When an operation switch
280
of an air conditioner is on, for example, when a temperature detected by a room sensor
281
is not less than a temperature set by a room temperature setting device
282
, a control computer
283
gives instructions to a solenoid
101
′ of the control valve
100
′ and causes the solenoid
101
′ to supply a prescribed current to a driving circuit
284
. And a moving core
102
′ is attracted toward the fixed core
104
′ by the attraction of the solenoid
101
′ and the urging force of a spring
103
′.
With the movement of the moving core
102
′ the valve element
106
′ attached to a solenoid rod
105
′ moves, while resisting the urging force of a forced relief spring
107
′, in a direction in which the opening of a valve hole
108
′ is reduced. With the movement of this valve element
106
′ a pressure-sensitive rod
109
′, which is integral with the valve element
106
′, also rises. As a result of this, a bellows
111
′ is pressed, which is connected to the valve element
106
′ via a pressure-sensitive rod receiving part
110
′ in such a manner that the bellows
111
′ can come close to and away from the valve element
106
′.
The bellows
111
′ is displaced according to variations in the suction pressure Ps introduced into the interior of a pressure-sensitive part
112
′ via the pressure-detection passage
217
, and gives loads to the pressure-sensitive rod
109
′. Accordingly, the opening of the valve hole
108
′ of control valve
100
′ by the valve element
106
′ is determined by a combination of the attraction by the solenoid
101
′, the urging force of the bellows
111
′ and the urging force of the forced relief spring
107
′.
When a difference between a temperature detected by the room sensor
281
and a temperature set by the room temperature setting device is great (when the cooling load is large), an increase in supply current causes the fixed core
104
′ to attract the moving core
102
′, and the opening of the valve hole
108
′ by the valve element
106
′ decreases. As a result, the control valve
100
′ operates in such a manner that the control valve
100
′ holds a lower suction pressure Ps, and under this suction pressure Ps the opening and closing of the valve element
106
′ is performed.
When the valve opening decreases, the volume of the coolant gas that flows from the discharge chamber
212
b
via the air supply passages
218
,
219
into the crankcase
231
decreases and, at the same time, the gas in the crankcase
231
flows out and enters the suction chambers
211
b
,
211
a
, with the result that the pressure Pc in the crankcase drops. And when the cooling load is large, the suction pressure Ps in the cylinder bore
221
increases and a difference is made between the suction pressure Ps and the pressure Pc in the crankcase, resulting in an increased inclination angle of the wobble plate
240
. As a result, the blocking element
270
leaves the side of the suction passage
215
and opens the through hole
216
.
Incidentally, as shown in
FIGS. 10 and 1
Imai Masayuki
Kume Yoshiyuki
Okii Toshiki
Freay Charles G.
Fujikoki Corporation
Gray Michael K.
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