Patent ID: 8734127
Filing Date: 2014-05-27
Classification: F04B

Abstract:
1. An axial hydraulic pump-motor in which a cylinder block having a plurality of cylinder bores formed about a rotational axis slides relative to a valve plate having a high-pressure side port and a low-pressure side port to control an amount of reciprocation of a piston in each cylinder bore by tilt of a swash plate, comprising: an oil passage for allowing the high-pressure side port and each cylinder bore to temporarily communicate for a first time of bottom dead center non communication after each cylinder bore is freed from communication with the low pressure side port until before each cylinder bore communicates with the high-pressure side port, wherein the oil passage has a length capable of transmitting high pressure in the oil passage to the cylinder bore at the time of communication, and of restoring pressure in the oil passage to a pressure of the high-pressure side port before communication with a next cylinder bore during the first time of bottom dead center non-communication; and a residual pressure loss regeneration circuit extending between a residual pressure loss recovery port and a residual pressure loss regeneration port to transmit pressure from one of the cylinder bore for a second time of top dead center non-communication, wherein when the residual pressure loss recovery port aligns with a residual pressure loss port of such cylinder bore so that the cylinder bore is freed from communication with the high-pressure and low-pressure side ports, the residual pressure loss regeneration circuit receives pressure from such cylinder bore, and the residual pressure loss regeneration circuit passes pressure to another cylinder bore in the first time, when the residual pressure loss regeneration port aligns with the residual pressure loss port of said another cylinder bore when the another cylinder bore is freed from communication with the high-pressure and low-pressure side ports in the first time of the bottom dead center non-communication until the oil passage communicates.