Patent ID: 6508735
Filing Date: 2003-01-21
Classification: B60L,F16H,Y10T

Abstract:
A hydraulic control system for a transmission which has: a first transmission mechanism for transmitting a torque between rotary members and a transmission member by clamping the transmission member between the rotary members with a clamping pressure based on an oil pressure, and a second transmission mechanism for changing transmission states of the torque by applying/releasing frictional engagement elements with an oil pressure, comprising:an oil pressure source; a first pressure regulator mechanism for regulating an oil pressure outputted from the oil pressure source, to a first oil pressure for establishing the clamping pressure for said transmission member by said rotary members, wherein the first pressure regulator mechanism includes a first pressure regulator value having a first input port communicating with said oil pressure source for establishing said first oil pressure and a first drain port communicating selectively with said first input port for discharging an oil pressure; a second pressure regulator mechanism for regulating the first oil pressure, as regulated and outputted by said first pressure regulator mechanism, to a second oil pressure for applying said frictional engagement elements, wherein the second pressure regulator mechanism includes a second pressure regulator value having a second input port communicating with said first input port, an output port communicating selectively with said second input port for establishing said second oil pressure, and a second drain port communicating with said output port, when said second input port is disconnected from said output port, and connected with said first drain port; and an oil passage connected with said first drain port and said second drain port for feeding an oil pressure, as outputted from said first drain port and said second drain port, to a lubrication system.