Patent ID: 7766139

Claim:
A method of operating a DCT hydraulic power control system having a pump, a high pressure section for providing oil to actuators of the DCT, a low pressure section for providing oil to a lubrication and cooling system of the DCT, and a regulator for directing excess oil from the high pressure section to the lubrication and cooling section and for keeping pressure in the high pressure section constant, the method comprising: closing, in a low speed mode, a directional valve disposed in a main line of the low pressure section for leading oil to the lubrication and cooling section of clutches of the DCT; operating two pump outlets of the pump in parallel, thereby forcing oil to flow through a check valve disposed in a first branch line of the low pressure section leading to the high pressure section; opening, in a medium speed mode, the directional valve in the main line of the low pressure section by activating an ON/OFF valve to create an ON/OFF pilot pressure for the directional valve in a connecting line branching off the first branch line; and maintaining, in a high speed mode, a first pressure outlet of the pump at a high pressure level and keeping a second pressure outlet of the pump continuously at a low pressure level by activating the ON/OFF valve of the directional valve.