An improved air compressor is provided. The air compressor includes a cylinder block having a head deck that defines a piston bore for reciprocal movement of a piston therein. The head deck further includes first and second ramped surfaces that slope downward toward the peripheral edge of the piston bore. A valve plate is in direct contact with the upper surface of the head deck, the valve plate having a leaf valve. During an intake stroke of the piston, the leaf valve deflects downward into direct engagement with the first and second ramped surfaces. Because the air compressor lacks a lower gasket between the valve plate and the head deck, the cost and assembly time associated with the lower gasket are eliminated.

An air compressor pump is provided, including a crankcase with an opening and a crankshaft extending out of the opening; a cover disposed over the opening in the crankcase; and a condensing chamber formed between the crankcase and the cover.

Lubricating oil has a kinematic viscosity in a range of 1 mm.sup.2/S to 7 mm.sup.2/S at 40° C., has a mass average molecular weight in a range of 150 to 400, and contains 0.5% by mass or more of a high molecular weight component. The high molecular weight component has a mass molecular weight of greater than or equal to 500. A crankshaft serving as a shaft part of a compression element includes a main shaft that includes a sliding surface. In a case where the sliding surface is a single sliding surface, a length of the single sliding surface in an axial direction is a single sliding length L, whereas in a case where the sliding surface is divided into a plurality of sliding surfaces, a length of one of the sliding surfaces in the axial direction, the one sliding surface having a least length in the axial direction among the plurality of sliding surfaces, is the single sliding length L, and a ratio L/D of the single sliding length L to an external diameter D of the main shaft is less than or equal to 2.0.

In a hermetic refrigerant compressor, a thrust bearing (e.g., thrust ball bearing (210)) is provided on a thrust surface (136) of a main bearing (134). One end of a sliding surface of the main bearing (134), the one end being closer to a compression chamber (133) than an opposite end of the sliding surface, is a first end, and the opposite end of the sliding surface is a second end. A distance between a center axis of the compression chamber (133) and the second end of the sliding surface (sliding surface lower end (139)) of the main bearing (134) is a distance L, and a distance between the center axis of the compression chamber (133) and the first end of the sliding surface (sliding surface upper end (138)) of the main bearing (134) is a distance La. When the distance L is in a range of 38 mm to 51 mm, the distance La is less than or equal to 16 mm.

A pump assembly includes a housing with an air inlet and an air outlet, a motor supported by the housing, the motor including a drive shaft rotatable about a drive shaft axis, a first plurality of diaphragms supported by the housing, the first plurality of diaphragms positioned along a first plane, and a second plurality of diaphragms supported by the housing, the second plurality diaphragms positioned along a second plane, the second plane spaced apart from the first plane. Rotation of the drive shaft is operable to move each diaphragm of the first plurality of diaphragms and each diaphragm of the second plurality of diaphragms from an intake position to a compression position to pump a fluid from the air inlet through the air outlet.

A power end assembly includes a crankshaft section, a crosshead section, and a connector section coupled together by one, two, or more sets of stay rods. The power end may include one or more support plates that are coupled to the crankshaft section and/or crosshead section. The crosshead section includes a plurality of individual crosshead frames. The connector section may include a plurality of individual connector plates or may be a unitary connector plate. The power end is configured to be coupled to a fluid end assembly by coupling the fluid end assembly to the connector plates.

A crankshaft assembly, a compressor and a refrigeration device are provided. The crankshaft assembly has an eccentric shaft component, a spindle component and a main screw oil pump. The eccentric shaft component has an eccentric cavity, and the spindle component has a first cavity communicated with the eccentric cavity. A first through-hole and a second through-hole in a first spindle are each communicated with the first cavity. An outer surface of the first spindle is provided with a first spiral oil groove connecting the first through-hole and the second through-hole. An outer surface of the main screw oil pump is provided with a second spiral oil groove along its length direction, and a spiral direction of the second spiral oil groove is opposite that of the first spiral oil groove.

A fluid pump for pumping a fluid. One or more piston-cylinder arrangements each include a respective cylinder portion, a respective head portion and a respective piston portion together defining a respective pumping chamber. One or more connecting arrangements connect a crank member to the one or more piston-cylinder arrangements to drive the respective piston portion of each of the one or more piston-cylinder arrangements. A housing and the respective piston portion of each of the one or more piston-cylinder arrangements together house the crank member in an interior. The interior is sealed to capture blow-by. A transmission is arranged to transmit power, for rotating the crank member, into the housing magnetically, electrically or both.

A sealed refrigerant compressor (10A) accommodates an electric component (20A) and a compression component (30) in a sealed container (11). A crankshaft (40) included in the compression component (30) includes a main shaft part (41) and an eccentric shaft part (42). A main shaft part (41) is secured to a rotor (22A) of the electric component (20A). The rotor (22A) is provided with a balance adjustment means such as a balance hole (27), which adjusts an unbalanced load caused by the structure of the main shaft part (41).

An internal combustion engine system includes a reciprocating compressor for pressurizing a fluid medium and having a compressor cylinder for accommodating a compressor piston. The compressor cylinder has a main cylinder volume and a secondary adjustable volume in fluid communication with the main cylinder volume so as to provide a variable geometrical compression ratio.