Importance

Loading Importance Indicators...

Abstract

A positive displacement hydraulic pump/motor assembly (1) includes a rotary cylinder block (3) having a central axis (5) and a generally circular array of cylinders (6) disposed in parallel relationship around the axis. A corresponding plurality of axial pistons (10) is reciprocably disposed within the respective cylinders. A drive shaft (12) effects rotation of the cylinder block about the central axis and a drive plate (15) is disposed at one end of the cylinder block (3) to effect sequentially staggered reciprocation of the pistons (10) in response to rotation of the cylinder block. A stationary valve plate (20) is disposed at an opposite end of the cylinder block. The valve plate (20) includes a valve face (21) adapted for sliding rotational engagement with a complementary mating face (22) formed on the cylinder block. The valve plate further includes at least one inlet port (24) adapted for fluid communication with a source of hydraulic fluid and at least one outlet port (26) adapted for fluid communication with an hydraulic load. The ports (24, 26) are disposed such that in use, hydraulic fluid is progressively drawn into the cylinders in sequence as the respective pistons are displaced away from the valve plate and subsequently expelled from the cylinders as the pistons are progressively displaced toward the valve plate. The pump/motor assembly further includes lift-off means in the form of an hydraulic lift-off piston (40) and cylinder (41), selectively operable to displace the cylinder block marginally away from the valve plate, thereby to minimise rotational resistance between the respective mating valve faces (21, 22) under predetermined operational conditions. The pump/motor assembly is adapted for incorporation into an energy management system operable in a driving mode, a braking mode and a neutral motor to provide supplementary drive from regenerative braking in a vehicle.

Loading the Abstract Image...

First Claim