Hybrid electric vehicle auxiliary oil pump
AssigneeFord Motor Company
InventorsAndrew John Silveri, Marvin Paul Kraska, Walter Joseph Ortmann
Life of this patent
Estimating the term…
Abstract
An automatic transmission for a hybrid electric vehicle where an engine is shut down during vehicle stops to improve fuel economy. The automatic transmission includes a main pump that is driven off of a transmission input shaft, and an electronically driven auxiliary pump. A shut down shuttle valve switches a hydraulic circuit connection from the main pump to the auxiliary pump for a low-reverse clutch and a forward clutch when the vehicle stops in drive or low gear. A pressure transducer, controller and steady state relay allow for closed loop feedback to control the auxiliary pump in order to assure sufficient hydraulic pressure while minimizing power consumption.
Claims20
A transmission for a hybrid electric vehicle comprising:
- an input shaft with a main transmission fluid pump drivingly connected thereto;
- an electronically controlled hydraulic shift system;
- a low-reverse clutch and a forward clutch connected to the hydraulic shift system;
- an electronically driven fluid pump;
- and
- a shut down shuttle valve operatively engaging the electrically driven fluid pump, the low/reverse clutch and the forward clutch and switchable to selectively engage and disengage the electronically driven pump from the hydraulic shift system.
A hybrid powertrain for a vehicle comprising:
- an internal combustion engine;
- a traction motor drivingly connected to the engine;
- and
- a transmission having an input shaft, with a main transmission fluid pump drivingly connected thereto, and an electronically controlled hydraulic shift system, and including a low-reverse clutch and a forward clutch connected to the hydraulic shift system, and with an electronically driven fluid pump, and with a shut down shuttle valve operatively engaging the electrically driven fluid pump, the low/reverse clutch and the forward clutch and switchable to selectively engage and disengage the electronically driven pump from the hydraulic shift system.
A method of operating a hydraulic system in an automatic transmission of a hybrid electric vehicle, with the transmission including an input shaft and a main pump for generating pressure in a hydraulic fluid when the input shaft is rotating, the method comprising the steps of:
- detecting that a rotational velocity of the transmission input shaft is below a predetermined threshold, and that a gear shift is in one of a drive and a low position;
- actuating an auxiliary pump to boost a pressure of the hydraulic fluid;
- operating the auxiliary pump to increase the hydraulic fluid pressure to a desired line pressure;
- hydraulically connecting the auxiliary pump to a low-reverse clutch and a forward clutch;
- and
- hydraulically disconnecting the main pump from the low-reverse clutch and the forward clutch.
Dependencies are inferred from the claim text.