A connecting rod for an air compressor includes a rod member, a wrist pin receiving end connected to a first end of the rod member, and a crank pin receiving end connected to a second opposing end of the rod member. A separation line for the connecting rod is provided above the crank pin receiving end. The separation line may be provided between the crank pin receiving end and the rod member. The connecting rod may include a first portion including the rod member and the wrist pin receiving end, and a separate second portion including the crank pin receiving end. The separation line may be provided between the first portion and the second portion.

A piston drive device includes: a crankcase; first and second compression cylinders fixed to the crankcase; first and second vacuum cylinders fixed to the crankcase; a rotational shaft rotatably supported within the crankcase; first and second compression pistons connected to the rotational shaft and reciprocating respectively within the first and second compression cylinders; and first and second vacuum pistons connected to the rotational shaft and reciprocating respectively within the first and second vacuum cylinders; wherein each diameter of piston heads of the first and second compression pistons is smaller than each diameter of piston heads of the first and second vacuum pistons, and the first and second compression pistons are connected to the rotational shaft so as to sandwich the first and second vacuum pistons in an axial direction of the rotational shaft.

A cam driven compressor includes a cam coupled to a plurality of cylinder and piston assemblies. Each cylinder and piston assembly comprises a piston located and movable within a respective cylinder. Each cylinder has a cylinder head. The compressor comprises a housing defining a cavity configured to receive a portion of a source gas from one or more of the cylinders in order to maintain a positive gas pressure within the cavity.

A compressor includes a housing, a first compression mechanism and a second compression mechanism disposed in the housing, and a housing cover fixed to the housing. Both the first compression mechanism and the second compression mechanism are configured to compress a working fluid from a suction pressure to a discharge pressure. The first compression mechanism includes a first cylinder housing having a first fluid storage plenum. The second compression mechanism includes a second cylinder housing having a second fluid storage plenum. The housing cover defines an intermediate-fluid port in fluid communication with the first fluid storage plenum via a first intermediate-fluid passage and the second fluid storage plenum via a second intermediate-fluid passage. Working fluid at an intermediate pressure enters the intermediate-fluid port. The intermediate pressure is greater than the suction pressure and less than the discharge pressure.

A compressor includes a housing, a first compression mechanism and a second compression mechanism disposed in the housing, and a valve. Both the first compression mechanism and the second compression mechanism are configured to compress a working fluid from a suction pressure to a discharge pressure. The first compression mechanism includes a first cylinder housing having a first fluid storage plenum. The second compression mechanism includes a second cylinder housing having a second fluid storage plenum. An intermediate-fluid port is in selective fluid communication with the valve. The intermediate-fluid port is in fluid communication with the first fluid storage plenum via a first intermediate-fluid passage and the second fluid storage plenum via a second intermediate-fluid passage. Working fluid at an intermediate pressure enters the intermediate-fluid port through the valve. The intermediate pressure is greater than the suction pressure and less than the discharge pressure.

A compressor includes a cylinder, a sleeve assembly disposed in the cylinder, and a piston disposed within the sleeve assembly. The sleeve assembly includes a sleeve and a collar. The sleeve and the collar cooperate to define a plurality of ports. The piston is movable between a first position and a second position and is configured to compress a working fluid from a suction pressure at the first position to a discharge pressure at the second position. The piston and the sleeve assembly cooperate to selectively permit working fluid at an intermediate pressure to enter the cylinder. The intermediate pressure is greater than the suction pressure and less than the discharge pressure.

A reciprocating piston air compressor has a first cylinder assembly, a second cylinder assembly, and a plurality intake valves and exhaust valves associated with each of the cylinder assemblies. Each cylinder assembly has a cylinder bore and a piston disposed in the cylinder bore. Each cylinder bore has a first end having a circumference defining an area. Each piston has a first end having a circumference defining an area. The valves associated with the first cylinder assembly are disposed within the circumference of the bore and/or the piston. The valves associated with the second cylinder assembly are disposed partially within and partially outside of the circumference of the bore and/or the piston.