Valves and valve actuation – Electrically actuated valve – With nonelectrical actuator
Reexamination Certificate
2003-01-31
2004-08-10
Tanner, Harry B. (Department: 3744)
Valves and valve actuation
Electrically actuated valve
With nonelectrical actuator
C062S228300, C417S222200, C137S625170
Reexamination Certificate
active
06772990
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a capacity control valve for variably modulating the capacity or pressure of a process fluid. More particularly, the invention relates to a capacity control valve which modulates the capacity or pressure in a control chamber of an air-conditioning system in a quick manner.
2. Description of the Related Art
There have been known as a relative art of the present invention capacity control valves for a variable displacement type swash plate compressor in an air-conditioning system. The relative art of the capacity control valve is illustrated in FIG.
15
.
In
FIG. 15
, a pressure sensing element
210
is disposed in a suction chamber
206
which is located at the lower end of a capacity control valve
200
. The pressure sensing element
210
is formed by a resilient bellows with a biasing spring which is disposed inside the bellows and the element is constructed in such a way that the upper end of the element moves by a contraction due to a suction pressure Ps supplied from an external. At the upper end of the pressure sensing element
210
, an intermediate rod
207
is disposed in a guide passage of a housing
220
in an axially movable manner. Furthermore, a valve body
201
connected to the intermediate rod
207
is disposed in a valve hole
208
, as shown in
FIG. 15
, at the upper portion of the housing
220
. Opening or closing motion of the valve body
201
corresponds to a separation or contact, respectively, of the valve body with the valve seat of the valve hole
208
, and hence an opening or closing of the valve hole
208
, respectively.
The housing
220
constitutes Ps supply port, Pd discharge port, and Pc crank chamber supply port wherein the Pd discharge port is connected to the valve hole
208
by means of a through communication passage
209
. When the valve hole
208
opens, the valve hole
208
is directly connected to the Pc crank chamber supply port and a process fluid is allowed to a crank chamber which is not shown in FIG.
15
.
Opening or closing of the valve body
201
is modulated by changing the set supply pressure (Ps set value) of the pressure sensing element
210
in accordance with the generated force of an electromagnetic solenoid coil device
202
which is disposed in the upper end portion of the capacity control valve
200
, and a capacity control of the variable displacement compressor is achieved by modulating the crank pressure Pc of the crank chamber while controlling the flow under the discharge pressure Pd guided to the crank chamber of the variable displacement compressor in accordance with an opening degree of the valve body
201
.
The pressure sensing element
210
disposed in the suction chamber
206
has a load characteristic such that the element expands or contracts in accordance with the suction pressure Ps within the normal use range of the suction pressure Ps.
When no electric current is supplied to the electromagnetic solenoid coil device
202
, the valve body
201
is maintained at a fully open position by the urging spring force of a return spring
203
. This fully opened position corresponds to a fully unloaded state. When the current is supplied to the solenoid coil device
202
, an electromagnetic attractive force is generated between a plunger
40
and a fixed iron core
205
. The valve body
201
maintains its fully opened position, namely an insensitive zone, until the electromagnetic force becomes larger than the opposing urging force of the return spring
203
.
However, when the electromagnetic force becomes larger than the urging force of the return spring
203
, the valve body
2011
moves in a direction closing the valve, entering Ps control range in which the more the coil current supply, the larger the valve closing force, and the lower the Ps set value.
In this type of capacity control valve
200
, it is difficult to reduce a cooling load because, in case of a great cooling load, the valve quickly closes due to the suction pressure Ps. Consequently, the compressor has to be stopped by means of clutch and the air-conditioning system needs to be turned off.
Diameter of the connected rod varies in place, and when the pressure areas of the rod are subjected to the suction pressure Ps, discharge pressure Pd, or crank chamber supply pressure Pc, the balance of the forces acting on the operation mechanism of the rods including the valve body (according to the ratio of the pressure receiving area of the respective rod diameters) causes substantially a bad influence on the valve opening degree of the valve body
201
.
Furthermore, a variation in the crank pressure Pc due to the different operation modes of a compressor may cause uncontrollable disturbances to the suction pressure Pc. Therefore, an accurate current control to the electromagnetic solenoid coil does not help improve the capacity control precision of the valve according to a preset suction pressure Ps.
A connection rod between the pressure sensing element
210
and the fixed iron core
205
comprises an intermediate rod
207
, a valve body rod
201
A, and a plunger rod
204
A. In the connection rod, a wear of the joint portion of each rod causes a serious problem of the valve opening degree of the valve body
202
.
Performance of the connection rod between the pressure sensing element
210
and the valve body
201
is worsened with respect to the opening degree of the valve body
201
because a wear of the contact surface causes the total length of the connection rod to be shortened since each joint is formed by a simple contact of the two adjacent rods.
This type of capacity control valve for variable displacement compressors suffers from the following problems due to the above mentioned arrangements. Primarily, the capacity control valve does not allow a quick change in the pressure of the control chamber. Therefore, such a variable displacement compressor, for instance, will require a clutch, which may result in a cost increase due to the more complicated structure of the variable displacement compressor.
Since no consideration is given in terms of the force balance which is affected by the pressure areas of the valve body, valve body rod, intermediate rod, and so on, to each of which the process fluid exerts a corresponding pressure, it is hard to maintain the control accuracy of the capacity or pressure of the process fluid under the control pressure.
Furthermore, the valve operation in which the valve body, valve body rod, intermediate rod and so on, are individually connected may cause a decrease in accuracy of the valve opening or closing action due to wears of the joint portions.
The present invention is introduced to resolve the above mentioned problems. A primary technical goal which this invention tries to achieve is to realize an accurate control of the pressure or the capacity of the capacity control valve without being affected by other pressures, and to be able to modify the pressure or the capacity of the capacity control valve as soon as an operation load exceeds a predetermined value. For example, when a clutch is needed for a variable displacement compressor, this invention eliminates such a clutch from the compressor and reduces the extra cost to install a clutch in the variable displacement compressor.
Another goal is to obtain a capacity control valve wherein the force balance acting on the operation mechanism of the connection rod including the valve body is arbitrarily chosen and the capacity or the pressure in the control chamber is accurately controlled based on a predetermined suction pressure (Pset) without being affected by other pressures.
For example, when the capacity control valve is used in a variable displacement compressor which is controlled by the suction pressure Ps, this invention enables the compressor to implement an accurate control with the predetermined suction pressure (Ps) without being affected by the crank chamber pressure (Pc) or the discharge pressure (Pd).
A further goal is to increase a manufacturing precision
Cho Ryousuke
Iwa Toshiaki
Maeda Takahiro
Ogawa Yoshihiro
Sasaki Sinji
Arent & Fox PLLC
Eagle Industry Co. Ltd.
Tanner Harry B.
LandOfFree
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