Patent ID: 7273355

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, said first and second cavity portions respectively having first and second cavity sidewalls extending substantially parallel to said central axis, a cross section of said first cavity portion oriented perpendicular to said central axis defining a first cross sectional configuration and area and a cross section of said second cavity portion oriented perpendicular to said central axis defining a second cross sectional configuration and area, said second cross sectional area being greater than said first cross sectional area, the entire first cross sectional area of said first cavity portion being contiguous with said second cavity portion, and wherein said 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 at least partially disposed in said cavity wherein said piston reciprocates along said central axis, said piston including a first piston portion and a second piston portion, said first piston portion having a cross sectional configuration and area substantially similar to said first cavity portion configuration and area, said second piston portion having a radially outer surface at least partially engageable with said second cavity sidewall, said second cavity portion being continuously vented during reciprocation of said piston, and wherein, during reciprocation of said piston within said cavity, said first piston portion compresses a fluid in said first cavity portion and forces transverse to said central axis are transferable between said radially outer surface of said second piston portion and said second cavity sidewall.