Slant plate type compressor with variable capacity control mechanism

Abstract

A variable capacity type slant plate type compressor including a crank chamber, a suction chamber and a discharge chamber is disclosed. The crank chamber is linked by a first communication path to the suction chamber, and is linked by a second communication path to the discharge chamber. A first valve control mechanism is disposed within the first communication path and second valve control mechanism is disposed within the second communication path. Fluid communication between the crank and suction chambers is controlled by the first valve control mechanism so that the suction chamber pressure is maintained at one predetermined constant value while fluid communication between the crank and discharge chambers is continuously closed. Fluid communication between the crank and discharge chambers is opened by the second valve control mechanism when the predetermined constant value of the suction chamber pressure must be increased. However, in the latter condition, fluid communication between the crank and suction chambers is continuously closed as long as the crank chamber pressure is not abnormally increased.

I claim: 
     
       1. A slant plate type refrigerant compressor comprising: a compressor housing enclosing a crank chamber, a suction chamber and a discharge chamber therein, said compressor housing comprising a cylinder block having a plurality of cylinders formed therethrough;   a piston slidably fitted within each of said cylinders;   drive means coupled to said pistons for reciprocating said pistons within said cylinders, said drive means including a drive shaft rotatably supported in said housing and coupling means for drivingly coupling aid drive shaft to said pistons such that rotary motion of said drive shaft is converted into reciprocating motion of said pistons, said coupling means including a slant plate having a surface disposed at an adjustable inclined angle relative to a plane perpendicular to said drive shaft, the slant angle changing in response to a change in pressure in said crank chamber relative to pressure in said suction chamber to thereby change the capacity of said compressor;   a first communication path linking said crank chamber with said suction chamber;   a first valve control mechanism disposed within said first communication path, said first valve control mechanism controlling fluid communication through said first communication path in response to changes in pressure in said suction chamber;   a second communication path linking said crank chamber with said discharge chamber, said first and second communication paths sharing a common portion linked to said crank chamber; and   a second valve control mechanism disposed within said second communication path, said second valve control mechanism responding to an external signal to open said second communication path to increase the pressure in said crank chamber to thereby reduce the capacity of the compressor, fluid communication through said first communication path being continuously controlled by said first valve control mechanism to maintain pressure in said suction chamber at a predetermined constant value as long as said second communication path is closed, hid second communication path being continuously opened as long as said first communication path is closed and said common portion being selectively coupled to the open one of said first or second communication paths.   
     
     
       2. The slant plate type refrigerant compressor of claim 1, said first valve control mechanism including a first valve member, said first communication path including a first valve seat formed at one portion thereof, said second valve control mechanism including a second valve member, said second communication path including a second valve seat formed at one portion thereof, fluid communication through said first communication path being continuously controlled by said first valve control mechanism so as to maintain pressure in said suction chamber at a predetermined constant value as long as said second valve member is received on said second valve seat, said second valve member moving away from said second valve seat as long as said first valve member is received on said first valve seat. 
     
     
       3. The slant plate type refrigerant compressor of claim 2 wherein said first valve member is forcibly moved away from said first valve seat to open said first communication path when the pressure difference between the crank chamber and the suction chamber exceeds a predetermined value. 
     
     
       4. The slant plate type refrigerant compressor of claim 1 wherein said first communication path is forcibly opened when the pressure difference between the crank chamber and the suction chamber exceeds a predetermined value. 
     
     
       5. A slant plate type refrigerant compressor comprising: a compressor housing enclosing a crank chamber, a suction chamber and a discharge chamber therein, said compressor housing comprising a cylinder block having a plurality of cylinders formed therethrough;   a piston slidably fitted within each of said cylinders;   drive means coupled to said pistons for reciprocating said pistons within said cylinders, said drive means including a drive shaft rotatably supported in said housing and coupling means for drivingly coupling said drive shaft to said pistons such that rotary motion of said drive shaft is converted into reciprocating motion of said pistons, said coupling means including a slant plate having a surface disposed at an adjustable inclined angle relative to a plane perpendicular to said drive shaft, the slant angle changing in response to a change in pressure in said crank chamber relative to pressure in said suction chamber to change the capacity of said compressor;   a first communication path linking said crank chamber with said suction chamber;   a first valve control mechanism disposed within said first communication path, said first valve control mechanism controlling fluid communication through said first communication path in response to change in pressure in said suction chamber;   a second communication path linking said crank chamber with said discharge chamber, said first and second communication paths sharing a common portion linked to said crank chamber; and   a second valve control mechanism disposed within said second communication path, said second valve control mechanism responding to an external signal to open said second communication path to increase the pressure in said crank chamber to thereby reduce the capacity of the compressor, said first and second valve control mechanisms functioning to prevent said first and second communication paths from opening simultaneously and to selectively couple said common portion to one of said first or second communication paths.