Variable displacement compressor
View Patent ↗A variable displacement compressor comprising a first control means for detecting the suction pressure of fluid or the crank chamber pressure and controlling the suction pressure to a target control value, and a second control means including means for detecting high-pressure side pressure to control the displacement of the compressor so as to relax an increase in the high-pressure side pressure when it is equal to or higher than a predetermined threshold and increasing the control value of the suction pressure depending on the increase in the high-pressure side pressure in a region exceeding the threshold. The control system is simple, the control valve is inexpensive and simple and capable of stabilized operation, and the variable displacement compressor has the internal control means suitable for refrigeration cycle operating in a supercritical region.
1. A variable displacement compressor comprising:
a first control means for detecting a suction pressure of fluid or a crank chamber pressure and controlling said suction pressure to a target control value;
a second control means for detecting a high-pressure side pressure and for controlling a displacement of the compressor, wherein said high-pressure side pressure is reduced when the high-pressure side pressure is equal to or higher than a predetermined threshold and said target control value of said suction pressure is increased when said high-pressure side pressure-exceeds said threshold,
wherein said target control value is held constant or is decreased relative to an increase of the high-pressure side pressure, when the high-pressure side pressure is less than said threshold, and
wherein the predetermined threshold is constant.
2. The variable displacement compressor according to claim 1 , wherein said fluid is a fluid capable of operating in a supercritical region.
3. The variable displacement compressor according to claim 2 , wherein said fluid capable of operating in a supercritical region is carbon dioxide.
4. The variable displacement compressor according to claim 1 , wherein said first control means or/and said second control means has a valve portion, and the opening/closing operation of said valve portion is controlled by said suction pressure or/and said high-pressure side pressure.
5. The variable displacement compressor according to claim 1 , wherein each of said first control means and said second control means is formed as a single control valve capable of being incorporated into the compressor.
6. A variable displacement compressor comprising:
a first pressure sensitive member configured to adjust an amount of a fluid discharged into a crank chamber, such that a suction pressure approaches a target value;
a second pressure sensitive member configured to adjust the amount of fluid discharged into the crank chamber, such that the target value increases when a discharge pressure exceeds a threshold value,
wherein the target value is held constant or is decreased relative to an increase of the discharge pressure, when the discharge pressure is less than the threshold value, and
wherein the threshold value is constant.
7. The variable displacement compressor of claim 6 , further comprising:
a valve configured to communicate said fluid between a discharge chamber and the crank chamber.
8. The variable displacement compressor of claim 7 , wherein the first pressure sensitive member adjusts the amount of fluid discharged into the crank chamber by controlling the valve.
9. The variable displacement compressor of claim 8 , wherein the second pressure sensitive member adjusts the amount of fluid discharged into the crank chamber by controlling the valve.
10. The variable displacement compressor of claim 6 , wherein the first pressure sensitive member comprises a bellows or a diaphragm.
11. The variable displacement compressor of claim 6 , wherein the second pressure sensitive member comprises a piston and a spring.
12. The variable displacement compressor of claim 6 , wherein the fluid passes through a supercritical region during operation of the compressor.
13. The variable displacement compressor of claim 6 , wherein the fluid is carbon dioxide.
14. An internal control valve for controlling a pressure difference in a variable displacement compressor, comprising:
a valve portion configured to adjust an opening between a discharge pressure side of the internal control valve and a suction pressure side of the internal control valve;
a first pressure sensitive member configured to open the valve portion when a suction pressure of the suction pressure side is below a target value and to close the valve portion when the suction pressure is above the target value;
a second pressure sensitive member configured to further open the valve portion when a discharge pressure of the discharge side exceeds a threshold value,
wherein the target value is held constant or is decreased relative to an increase of the discharge pressure, when the discharge pressure is less than the threshold value, and
wherein the threshold value is constant.
15. The internal control valve of claim 14 , wherein the first pressure sensitive member comprises a bellows or a diaphragm.
16. The internal control valve of claim 14 , wherein the second pressure sensitive member comprises a piston and a spring.
17. The internal control valve of claim 16 , wherein the threshold value is determined by a spring factor of the spring.
18. The variable displacement compressor according to claim 1 , wherein the target control value is decreased relative to an increase of the high-pressure side pressure, when the high-pressure side pressure is less than said threshold.
19. The variable displacement compressor of claim 6 , wherein the target value is decreased relative to an increase of the discharge pressure, when the discharge pressure is less than the threshold value.
20. The internal control valve of claim 14 , wherein the target value is decreased relative to an increase of the discharge pressure, when the discharge pressure is less than the threshold value.