Variable displacement wobble plate type compressor with improved crankcase pressure control system

A variable displacement wobble plate type compressor comprising:

• a housing element having therein a suction chamber for a refrigerant before compression and a discharge chamber for a refrigerant after compression;
• a cylinder block defining therein a plurality of cylinder bores arranged so as to surround an axial drive shaft and having therein associated reciprocatory pistons disposed so as to draw the refrigerant from said suction chamber and to then discharge the compressed refrigerant into said discharge chamber;
• a crankcase having defined therein a chamber communicating with said cylinder bores and containing therein a drive plate mounted in such a manner that it is capable of rotating with said drive shaft as well as changing an inclination thereof with respect to said drive shaft and a non-rotating wobble plate held by said drive plate;
• a plurality of connecting rods connecting between said wobble plate and said pistons;
• a first passageway means for fluidly communicating said chamber of said crankcase with said discharge chamber of said housing element;
• a first valve means arranged in said first passageway means, for opening and closing said first passageway means;
• a second passageway means for providing a fluid communication between said chamber of said crankcase and said suction chamber of said housing element;
• a second valve means arranged in said second passageway means, for varying an extent of opening of a part of said second passageway means;
• a first valve control means for controlling an operation of said first valve means in response to a change in fluid pressure in said suction chamber with respect to a first predetermined pressure level, said first valve control means moving said first valve means to a first position opening said first passageway means when pressure in said suction chamber is less than said first predetermined pressure level, and to a second position closing said first passageway means when pressure in said suction chamber is larger than said first predetermined pressure level;
• and
• a second valve control means for controlling an operation of said second valve means in response to a change in fluid pressure in said discharge chamber with respect to a second predetermined pressure level, said second valve control moving said second valve means to a first position increasing the extent of opening of said part of said second passageway means when pressure in said discharge chamber is larger than said second predetermined pressure level, and to a second position decreasing the extent of opening of said part of said second passageway means when pressure in said discharge chamber is not larger than said second predetermined pressure level, said second valve control means including fluid passageway means for providing fluid communication between said discharge chamber and said second valve control means to sense a change in a discharge pressure in the discharge chamber.