| 摘要 |
<p>A hydraulic pump-motor has a pressure regulating restriction (52) for allowing, immediately before a cylinder bore (25f) is communicated with a valve plate discharge port, communication between the cylinder bore (25f) and the valve plate discharge port. The hydraulic pump-motor also has an oil path (40) for temporarily allowing communication between the valve plate discharge port and the inside of the cylinder bore (25f) in a period after the cylinder bore (25f) is freed from its communication with a valve plate suction port until the cylinder bore (25f) is communicated with the pressure regulating restriction (52). The oil path (40) has a length that transmits, when the communication is established, high pressure in that part of the oil path which is on the cylinder bore (25f) side into the cylinder bore (25f) and that can, when the communication is not established, restore the pressure in that part of the oil path which is on the cylinder bore (25f) side to pressure on the valve plate discharge port side before communication with the next cylinder bore is established. Thus, such a simple structure as described above can suppress pulsation in a relatively large rotation speed region.</p> |
