Patent ID: 7740556
Filing Date: 2010-06-22
Classification: F15B,F16H

Abstract:
1. A hydraulic control apparatus of a hydraulic servo unit that selectively changes an operation direction between a first direction when an oil is supplied from a first port and discharged from a second port and a second direction opposite to the first direction when the oil is supplied from the second port and discharged from the first port, the hydraulic control apparatus comprising: a first oil flow control valve and a second oil flow control valve each including an oil supply control portion that controls an oil supply from a pressurized oil source, and an oil discharge control portion that controls a connection with an oil discharge passage; a control valve operation controller that controls each operation of the first and the second oil flow control valves; and a depressurize oil supply unit that supplies a pressurized oil from the pressurized oil source, which has been depressurized to at least one of the first and the second ports by bypassing the first and the second oil flow control valves, wherein the first port receives an oil supply from the oil supply control portion of the first oil flow control valve, and discharges the oil through the oil discharge control portion of the second oil flow control valve, wherein the second port receives the oil supply from the oil supply control portion of the second oil flow control valve, and discharges the oil through the oil discharge control portion of the first oil flow control valve, wherein an operation state of the hydraulic servo unit is controlled by the control valve operation controller that controls each operation of the first and the second oil flow control valves, and wherein the hydraulic servo unit includes a toroidal type continuously variable transmission.