Drain valve
AssigneePunch Powertrain N.V.
InventorsPeter Mark Smid, Stefan Hubertus Godelieve Van Raemdonck
Life of this patent
Estimating the term…
Abstract
A hydraulic system for a multiple friction transmission, comprising: a first pressure relief valve 5 regulable by means of a first pilot pressure; a normally-open drain valve 8, which is a directional valve switchable between an open state and a closed state by means of a second pilot pressure; at least one first pressure regulator 11 for operating the drain valve by means of a first pilot pressure and a second pilot pressure, respectively; wherein in the event of detrimental hydraulic pressure build up, the second pilot pressure is dropped to open the drain valve, so as to relieve pressure through the drain line.
Claims15
A hydraulic system for a vehicle transmission with multiple friction elements for coupling and transmitting engine power to wheels of a vehicle by actuation of the friction elements via said hydraulic system, said hydraulic system comprising:
- at least one pressure pump supplying pressurized fluid to a pressure circuit via a first pressure pump outlet line, the pressure circuit in fluid connection with a friction element actuation line actuating a friction element;
- at least one first pressure regulator for operating a first pressure relief valve by means of a first pilot pressure through a first pilot pressure line;
- said first pressure relief valve arranged in a pressure controlled hydraulic line branched off at the first pressure pump outlet line, wherein the first pressure relief valve is controlled by means of the first pilot pressure to control the pressure in the pressure circuit;
- wherein a drain valve is arranged in a pressure drain line branched off at the first pressure pump outlet line, different from the pressure controlled hydraulic line, said drain valve being a directional valve switchable between an open state and a closed state by means of a second pilot pressure through a second pilot pressure line, said second pilot pressure in fluid communication with the first pilot pressure.
A method for controlling pressure in a hydraulic system for a vehicle transmission with multiple friction elements for coupling and transmitting engine power to wheels of a vehicle by actuation of the friction elements via said hydraulic system, the method comprising:
- supplying pressurized fluid to a pressure circuit in fluid connection with a friction element of the transmission;
- operating a first pressure relief valve by means of a first pilot pressure through a first pilot pressure line;
- said first pressure relief valve arranged in a pressure controlled hydraulic line branched off at a first pressure pump outlet line to control the pressure in the pressure circuit;
- switching a drain valve in a pressure drain line branched off at the first pressure pump outlet line, different from the pressure controlled hydraulic line, said drain valve being a directional valve, switchable between an open state and a closed state by means of a second pilot pressure through a second pilot pressure line, said second pilot pressure in fluid communication with the first pilot pressure.
Dependencies are inferred from the claim text.