An electro hydrostatic actuator comprising a hydraulic pump driven by an electric motor to supply hydraulic fluid to a hydraulic actuator, the pump comprising an inlet and an outlet for the hydraulic fluid and an active flow path configured therebetween such that, in an active mode of operation when the pump is driven by the electric motor, hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The pump further comprises a bypass flow path configured to open between the inlet and outlet such that, in a damping mode of operation when the pump is not driven by the electric motor, hydraulic fluid is able to pass through the pump along the bypass flow path between the inlet and outlet. The hydraulic pump is a rotary piston pump comprising a pump barrel driven to rotate by a motor shaft.

An axial piston motor having a cylinder housing, in which a plurality of cylinders are formed, and having pistons which are movably guided in the cylinders, wherein the pistons are attached to a swash plate and wherein a flow of a fluid that has entered via an inlet into the axial piston motor is controlled into and out of the cylinders by means of inlet and outlet valves, wherein the inlet and/or outlet valves comprise fluid change openings which are formed in a cylinder head plate and which can be temporarily released and covered by means of a rotary slide, for which purpose the rotary slide forms at least one passage opening.

The present invention relates to an axial piston pump (1) of the rotating inclined plate type for pumping a liquid comprising: a head (25), a plurality of cylinders (30) made in the head (25) in a number greater than two, having axes (C) parallel to each other and the cylinders being arranged radially around a common axis (A) parallel to the axes of the cylinders, a plurality of pistons (75), each slidingly inserted within a respective cyl-inder (30) of the plurality of cylinders (30) for the pumping of the liquid, and a plurality of delivery ducts (145) made in the head (25), each of which runs directly from a re-spective cylinder (30) to a respective delivery valve (120) and is arranged transversely to the axis (C) of the respective cylinder. Where the head (25) has a first side (61) and a second side (62), the second side (62) being opposite to the first side (61) in relation to an imaginary secant plane (S) which contains the common axis (A) and which is paral-lel to the axes (C) of the cylinders (30), where the plurality of cylinders (30) comprises a first arrangement of cylinders, which has its own axis (C) between the first side (61) and the imaginary secant plane (S), and a second arrangement of cylinders, which has its own axis (C) between the second side (62) and the imaginary secant plane (S). Said delivery ducts (145) running from the cylinders (30) of the first arrangement of cylin-ders, run from the respective cylinder (30) towards the first side (61), and the delivery ducts running from the cylinders of the second arrangement of cylinders, run from the respective cylinder (30) towards the second side (62).

The present invention relates to an axial piston pump (1) of the rotating inclined plate type for pumping a liquid comprising: a head (25), a plurality of cylinders (30) made in the head (25) in a number greater than two, having axes (C) parallel to each other and the cylinders being arranged radially around a common axis (A) parallel to the axes of the cylinders, a plurality of pistons (75), each slidingly inserted within a respective cyl-inder (30) of the plurality of cylinders (30) for the pumping of the liquid, and a plurality of delivery ducts (145) made in the head (25), each of which runs directly from a re-spective cylinder (30) to a respective delivery valve (120) and is arranged transversely to the axis (C) of the respective cylinder. Where the head (25) has a first side (61) and a second side (62), the second side (62) being opposite to the first side (61) in relation to an imaginary secant plane (S) which contains the common axis (A) and which is paral-lel to the axes (C) of the cylinders (30), where the plurality of cylinders (30) comprises a first arrangement of cylinders, which has its own axis (C) between the first side (61) and the imaginary secant plane (S), and a second arrangement of cylinders, which has its own axis (C) between the second side (62) and the imaginary secant plane (S). Said delivery ducts (145) running from the cylinders (30) of the first arrangement of cylin-ders, run from the respective cylinder (30) towards the first side (61), and the delivery ducts running from the cylinders of the second arrangement of cylinders, run from the respective cylinder (30) towards the second side (62).

A hydraulic machine includes a first member (1) having a first structure (2) for a hydraulic medium opening in a first interface surface (3) and a second member having a second structure for the hydraulic medium opening in a second interface surface is described, the first interface surface (3) being in contact with the second interface surface, wherein at least one of the members (1) is provided with a support element (6) surrounding the member (1). Such a machine should have a good efficiency. To this end the support element (6) has a strength varying in circumferential direction around the member (1) and/or in thickness direction in a middle region of the member (1).

A piston pump (1) is described for pumping a liquid comprising: a head (10) wherein at least a cylinder (15) is obtained, a piston (45) slidably inserted in the cylinder, a first sealing annular gasket (60) which circumferentially sealingly contacts the piston (45), a second sealing annular gasket (80) which circumferentially sealingly contacts the piston, and an annular body (100) which circumferentially encloses the piston (45) and is at least partially accommodated in a housing seat (110) obtained in the head (10) in a portion of the cylinder (15). Said annular body (100) comprises: a first housing seat (150) wherein the first sealing annular gasket (60) is housed, a second housing seat (155) wherein the second sealing annular gasket (80) is housed, and a third housing seat (185) wherein a third sealing annular gasket (190) is housed, which is placed between the annular body (100) and the housing seat (110) of the annular body.

A piston pump (1) is described for pumping a liquid comprising: a head (10) wherein at least a cylinder (15) is obtained, a piston (45) slidably inserted in the cylinder, a first sealing annular gasket (60) which circumferentially sealingly contacts the piston (45), a second sealing annular gasket (80) which circumferentially sealingly contacts the piston, and an annular body (100) which circumferentially encloses the piston (45) and is at least partially accommodated in a housing seat (110) obtained in the head (10) in a portion of the cylinder (15). Said annular body (100) comprises: a first housing seat (150) wherein the first sealing annular gasket (60) is housed, a second housing seat (155) wherein the second sealing annular gasket (80) is housed, and a third housing seat (185) wherein a third sealing annular gasket (190) is housed, which is placed between the annular body (100) and the housing seat (110) of the annular body.

An electric motor driven pump assembly configuration that includes an electric motor, a hydraulic pump driven by the electric motor is provided. The hydraulic pump is driven by the electric motor to convert electrical power into hydraulic power. A multi-inlet hydraulic pump enhances cooling flow through a pump case of the assembly and also enhances cooling flow for cooling the electric motor and corresponding drive/control components.

A hydroelectric power system and pump suitable for the system are disclosed which can make efficient use of the energy available in water flows with considerably variable flow rates. A simple, compact variable displacement axial piston pump can be operated so as to provide an essentially constant output pumping pressure and variable output volume that varies efficiently in accordance with water flow rate. The system is particularly suitable for shoreline tidal power generation and provides firm power output throughout the tidal slacks occurring during the tidal reversals.

A pump plunger is disclosed. The plunger may include a proximal end and a distal end opposite the proximal end. The plunger may also include a body portion extending between the proximal end and a second transition datum, and additionally include a transition section extending between a first transition datum and the second transition datum. The transition section may have a non-linear geometric profile. A first shoulder portion may be positioned adjacent to the transition section that may extend between the second transition datum and a third datum. The third datum may be positioned radially inward of the second transition datum. The plunger may also include a tip portion positioned adjacent to the first shoulder portion that may extend between the third datum and a fourth datum positioned at the distal end. The fourth datum may be positioned radially inward of the third datum.