Patent ID: 7175400

Claim:
A compressor assembly comprising: a cylinder block, said cylinder block defining a cavity having a first cavity portion and a second cavity portion, said cavity defining a central axis extending through each of said first and second cavity portions and wherein said compressor assembly defines an inlet in communication with said first cavity portion and an outlet in communication with said first cavity portion whereby a compressible fluid enters said first cavity portion through said inlet at a suction pressure and is discharged through said outlet at a discharge pressure; and a piston reciprocatingly disposed along said central axis, said piston including a first piston portion and a second piston portion, said first piston portion at least partially disposed within said first cavity portion, said first piston portion defining a compression chamber within said first cavity portion wherein reciprocation of said piston relative to said cavity compresses the compressible fluid within said compression chamber, said second piston portion at least partially disposed within said second cavity portion and reciprocable therein, said second piston portion having a radially outer surface at least partially engageable with a sidewall of said second cavity portion wherein forces transverse to said central axis are transferable between said radially outer surface and said sidewall and wherein said compressor assembly defines a vent passage in communication with a variable volume space defined by said second piston portion and said second cavity portion and disposed axially adjacent said first cavity portion.