摘要 |
A compressor (20) comprises: a case (22); and at least one piston (40) mounted for reciprocating movement, each in a respective cylinder (42) of the case. The at least one piston having a peripheral surface (50) and an upper surface (52), the upper surface having an outer portion (54) and a projection (80) extending from the upper surface. The at least one piston has a channel (220) positioned to pass flow from an area above the outer portion. |