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 directional control valve (DCV) fluidly coupled to the second chamber and the fourth chamber, a first relief valve fluidly coupled to the DCV via a first control line and the second chamber via a first sensing line, a first orifice positioned along the first sensing line, a second relief valve fluidly coupled to the DCV via a second control line and the fourth chamber via a second sensing line, and a second orifice positioned along the second sensing line.

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.

A pump system includes a pump assembly and a pump controller. The pump assembly includes a housing defining a first volume and a second volume separated by a divider, a first piston dividing the first volume into a first chamber and a second chamber, a second piston dividing the second volume into a third chamber and a fourth chamber, and a piston rod coupling the first piston and the second piston such that a movement of the first piston causes an equal movement of the second piston. The pump controller is configured to alternately supply a first fluid to the second chamber and the fourth chamber to cause the first piston and the second piston to reciprocate within the housing.

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 directional control valve (DCV) fluidly coupled to the second chamber and the fourth chamber, a first relief valve fluidly coupled to the DCV via a first control line and the second chamber via a first sensing line, a first orifice positioned along the first sensing line, a second relief valve fluidly coupled to the DCV via a second control line and the fourth chamber via a second sensing line, and a second orifice positioned along the second sensing line.

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 submersible pump assembly for transference of a fluid medium with low viscosity is disclosed. In one embodiment, the submersible pump assembly includes a cylinder block having cylinders and pistons. A drive shaft is rotatably supported in the cylinder block and coupled to a drive unit. An inclined leading plate is coupled to the pistons and the drive shaft such that the pistons are configured to be axially driven in a reciprocating motion within the cylinders upon rotation of the inclined leading plate. A suction chamber and a pressure chamber are each located in fluid communication with the cylinders. In one operational mode, the fluid medium is transferred from the suction chamber to the pressure chamber during the reciprocating motion of the pistons, when the pistons are active. In another operational mode, the fluid medium is circulated through the suction chamber.

A pump system includes a pump assembly and a pump controller. The pump assembly includes a housing defining a first volume and a second volume separated by a divider, a first piston dividing the first volume into a first chamber and a second chamber, a second piston dividing the second volume into a third chamber and a fourth chamber, and a piston rod coupling the first piston and the second piston such that a movement of the first piston causes an equal movement of the second piston. The pump controller is configured to alternately supply a first fluid to the second chamber and the fourth chamber to cause the first piston and the second piston to reciprocate within the 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.