Variable displacement hydraulic pump control
AssigneeFord Global Technologies, LLC
InventorsDerek Kinch, Mark R. Dobson, Lev Pekarsky, Hrudaya Mahapatro
Life of this patent
Estimating the term…
Abstract
A system controlling pressure in a transmission including a variable displacement pump, a circuit carrying fluid from the pump to the transmission, a valve using fluid in said circuit to regulate pressure that controls displacement of the pump, a source of control pressure including an accumulator, a first spring acting with said source causing the valve to change the regulated pressure, and a second spring acting with feedback pressure from said circuit to oppose said change.
Claims20
A system controlling pressure in a transmission, comprising:
- a variable displacement pump;
- a spool valve hydraulically engaging the pump with regulated pressure directed from the spool valve to the pump that controls displacement of the pump;
- a circuit providing pressurized fluid from the pump to the transmission and to bias the spool valve in a first direction;
- an electronically controlled valve selectively providing hydraulic control pressure to the spool valve, biasing the spool valve in an opposed second direction;
- a first spring biasing the spool valve in the first direction;
- and
- a second spring biasing the spool valve in the second direction.
A system controlling pressure in a transmission, comprising:
- a variable displacement pump;
- a spool valve hydraulically engaging the pump with regulated pressure directed from the spool valve to the pump that controls displacement of the pump;
- a circuit providing pressurized fluid from the pump to the transmission and to bias the spool valve in a first direction;
- an electronically controlled valve selectively providing hydraulic control pressure to the spool valve, biasing the spool valve in an opposed second direction;
- a hydraulic line extending from the electronically controlled valve to the spool valve, an accumulator hydraulically connected only to the hydraulic line between the electronically controlled valve and the spool valve, with hydraulic fluid flowing between the electronically controlled valve and the spool valve actuating the accumulator;
- and
- a first spring biasing the spool valve in the first direction.
A method for controlling pressure in a transmission, comprising:
- activating a variable displacement pump;
- using a spool valve to regulate pressure in a hydraulic line extending from the spool valve to the pump to control displacement of the pump whose output is connected to the transmission and the spool valve to bias the spool valve in a first direction;
- selectively actuating an electronically controlled valve to provide a source of control pressure;
- using a first spring and the source of control pressure to cause the spool valve to move in the second direction, effecting a change in the pump displacement;
- and
- a second spring engaging the spool valve to bias the spool valve toward the first direction, with the second spring and pressure at the outlet of the pump opposing movement in the second direction.
Dependencies are inferred from the claim text.