Patent ID: 8176838
Filing Date: 2012-05-15
Classification: F03C,F04B

Abstract:
1. A hydraulic machine arrangement including a hydraulic machine operable in at least one of two modes, a first mode being a pump mode, wherein the hydraulic machine can be driven by mechanical energy to increase the pressure of fluid flowing through the hydraulic machine, and a second mode being a motor mode, wherein the hydraulic machine can be driven by pressurized fluid to provide output torque, the hydraulic machine arrangement comprising: a port housing including a high pressure fluid port, a low pressure fluid port, and an exhaust port; a cylinder block in fluid communication with the port housing and including a plurality of cylinders therein; a plurality of radial pistons, each of the pistons being configured to reciprocate within a corresponding cylinder in the cylinder block, the pistons pumping fluid when the hydraulic machine is operating in the pump mode, and providing torque when the hydraulic machine is operating in the motor mode, each of the pistons including a corresponding cam follower; a cam disposed inboard of the pistons, and having a plurality of lobes configured to cooperate with the cam followers such that effecting a relative rotational motion between the cam and the cylinder block effects linear motion of the pistons when the hydraulic machine is operating in the pump mode, and effecting linear motion of the pistons effects a relative rotational motion between the cam and the cylinder block when the hydraulic machine is operating in the motor mode, at least one of the lobes having a first profile to effect a full stroke movement of a corresponding piston, and at least one other of the lobes having a second profile shallower than the first profile to effect a partial stroke movement of a corresponding piston; a first control valve associated with the high pressure fluid port and the exhaust port, the first control valve being movable between first and second positions, the first position of the first control valve facilitating fluid flow between the high pressure port and at least one cylinder, the second position of the first control valve facilitating fluid flow between the exhaust port and the at least one cylinder, thereby disengaging a respective piston in the at least one cylinder from the cam; a second control valve associated with the low pressure fluid port and the exhaust port, the second control valve being movable between first and second positions, the first position of the second control valve facilitating fluid flow between the low pressure port and at least one other cylinder, the second position of the second control valve facilitating fluid flow between the exhaust port and the at least one other cylinder, thereby disengaging a respective piston in the at least one other cylinder from the cam, movement of at least one of the first or second control valves between its respective first and second positions effecting discrete variation in the displacement of the hydraulic machine; and a valve plate including a plurality of apertures therethrough, at least one of the apertures communicating with the first control valve and at least one other of the apertures communicating with the second control valve, the valve plate being configured to connect the at least one cylinder with the first control valve and the at least one other cylinder with the second control valve, the valve plate and the port housing being movable relative to each other to effect a first transition to disconnect the at least one cylinder from the first control valve and connect it with the second control valve, and to effect a second transition to disconnect the at least one other cylinder from the second control valve and connect it with the first control valve.