A pump system includes a housing defining a first internal volume and a second internal volume, a first piston positioned to separate the first internal volume into a first chamber and a second chamber, a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber, a first inlet check valve configured to permit fluid flow into the first chamber, a second inlet check valve configured to permit fluid flow into the third chamber, a directional control valve (DCV) repositionable between (a) a first position where the DCV is configured to fluidly couple the second chamber to a high pressure fluid source and (b) a second position where the DCV is configured to fluidly couple the fourth chamber to the high pressure fluid source, and a relief valve configured to supply a fluid to the DCV through an orifice to move the DCV.

A compressor may include a crankcase, a crankshaft, a piston, a discharge valve and a suction plenum. The crankcase defines a discharge plenum receiving working fluid at a first pressure. The crankshaft is disposed within the discharge plenum. The piston is drivingly connected to the crankshaft and reciprocatingly received in a cylinder. The piston and cylinder cooperate to define a compression chamber therebetween. The discharge valve may control fluid flow through a discharge passage between the compression chamber and the discharge plenum. The suction plenum may receive working fluid at a second pressure that is less than the first pressure. The suction plenum may provide working fluid at the second pressure to the compression chamber.

A compressor may include a crankcase, a crankshaft, a piston, a discharge valve and a suction plenum. The crankcase defines a discharge plenum receiving working fluid at a first pressure. The crankshaft is disposed within the discharge plenum. The piston is drivingly connected to the crankshaft and reciprocatingly received in a cylinder. The piston and cylinder cooperate to define a compression chamber therebetween. The discharge valve may control fluid flow through a discharge passage between the compression chamber and the discharge plenum. The suction plenum may receive working fluid at a second pressure that is less than the first pressure. The suction plenum may provide working fluid at the second pressure to the compression chamber.

A vehicle air-conditioner compressor may include a housing having a front housing section and a rear housing section; a shaft rotatably installed in the housing; a lug fixed at a preset position on the shaft; a swash plate coupled with the lug at one side thereof and rotating together with the lug, a piston connected to the swash plate by a shoe and moved reciprocatingly by the swash plate; a cylinder that accommodates the piston therein, and a pressure-sensing chamber coupled with a rod at the other side of the swash plate, that operates the rod using a pressure provided from a high-pressure chamber of the rear housing.

A vehicle air-conditioner compressor may include a housing having a front housing section and a rear housing section; a shaft rotatably installed in the housing; a lug fixed at a preset position on the shaft; a swash plate coupled with the lug at one side thereof and rotating together with the lug, a piston connected to the swash plate by a shoe and moved reciprocatingly by the swash plate; a cylinder that accommodates the piston therein, and a pressure-sensing chamber coupled with a rod at the other side of the swash plate, that operates the rod using a pressure provided from a high-pressure chamber of the rear housing.

A compressor may include a crankcase, a crankshaft, a piston, a discharge valve and a suction plenum. The crankcase defines a discharge plenum receiving working fluid at a first pressure. The crankshaft is disposed within the discharge plenum. The piston is drivingly connected to the crankshaft and reciprocatingly received in a cylinder. The piston and cylinder cooperate to define a compression chamber therebetween. The discharge valve may control fluid flow through a discharge passage between the compression chamber and the discharge plenum. The suction plenum may receive working fluid at a second pressure that is less than the first pressure. The suction plenum may provide working fluid at the second pressure to the compression chamber.

A compressor may include a crankcase, a crankshaft, a piston, a discharge valve and a suction plenum. The crankcase defines a discharge plenum receiving working fluid at a first pressure. The crankshaft is disposed within the discharge plenum. The piston is drivingly connected to the crankshaft and reciprocatingly received in a cylinder. The piston and cylinder cooperate to define a compression chamber therebetween. The discharge valve may control fluid flow through a discharge passage between the compression chamber and the discharge plenum. The suction plenum may receive working fluid at a second pressure that is less than the first pressure. The suction plenum may provide working fluid at the second pressure to the compression chamber.

An apparatus for delivery of fluids to a patient includes an inlet tube and an outlet tube connected to each other at an angular joint. A rotary valve and a piston are fitted to the angular joint forming a chamber. The rotary valve is provided with a priming channel notch and a pumping notch. For priming operation with the fluid delivery apparatus, a user sets the rotary valve to a priming position. During pumping operation, the rotary valve rotates in coordination with the piston to transfer a quantum of fluid from the inlet tube to the outlet tube via the chamber. A second piston is optionally provided on the outlet tube for smoothing out flow rate pulsations.

A pump system includes a housing defining a first internal volume and a second internal volume, a first piston positioned to separate the first internal volume into a first chamber and a second chamber, a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber, a first inlet check valve configured to permit fluid flow into the first chamber, a second inlet check valve configured to permit fluid flow into the third chamber, a directional control valve (DCV) repositionable between (a) a first position where the DCV is configured to fluidly couple the second chamber to a high pressure fluid source and (b) a second position where the DCV is configured to fluidly couple the fourth chamber to the high pressure fluid source, and a relief valve configured to supply a fluid to the DCV through an orifice to move the DCV.

Refrigerant compressor for refrigeration systems, comprising an electric motor, at least two cylinder banks and a mechanical performance control unit for activating and deactivating at least one of the cylinder banks in order to activate or deactivate its refrigerant output, wherein, for the purpose of operation in partial performance conditions, the refrigerant compressor is operable in at least two different operating modes, of which each provides an activation or deactivation of the cylinder banks that is different from the other operating modes, wherein associated with the refrigerant compressor is a frequency converter for controlling the speed of the electric motor, wherein associated with the refrigerant compressor is an operating condition controller that, in accordance with a performance request signal supplied to it for operation of the refrigerant compressor in the partial performance condition corresponding to this performance request signal, operates the refrigerant compressor in an operating mode that is selected from at least two different operating modes and at a speed adapted to the selected operating mode, for the purpose of achieving this partial performance condition.