Method of Engaging Transmission System of A Hybrid Vehicle

摘要

A traction motor of a hybrid electric vehicle drives a primary pump to provide pressurized hydraulic fluid to engage a power flow path of a multi-ratio transmission. To reduce fuel consumption, the motor is maintained at zero speed until a shift lever is moved into a drive position. After a power flow path is established, the motor speed is again reduced to zero until a driver demands torque by pressing an accelerator pedal. While the traction motor is stationary, an auxiliary pump maintains the fluid pressure to keep the transmission power flow path engaged.

主权项

1. A vehicle comprising:
a discrete ratio transmission having an input and an output; a primary pump drivably connected to the input and configured to supply a fluid at an elevated pressure to a line pressure circuit; a secondary pump configured to maintain the elevated pressure in the line pressure circuit; a valve body configured to route the fluid from the line pressure circuit to shift elements of the transmission; a traction motor drivably connected to the input; a drive mode selector; and a controller programmed to
in response to movement of the drive mode selector, increase a speed of the traction motor and control the valve body to direct the fluid to some of the shift elements to establish a power flow path from the input to the output, andafter establishing the power flow path, reduce the speed of the traction motor and maintain the transmission in the drive state using the secondary pump.