Method and apparatus for controlling creep torque in a hybrid powertrain system

Patent metadata

Field	Value
Publication number	US-9663108-B2
Application number	US-201414153254-A
Country	US
Kind code	B2
Filing date	Jan 13, 2014
Priority date	Jan 13, 2014
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

A method for operating a powertrain system of a vehicle includes determining an initial creep torque command in an operator-selected direction of travel, adjusting the initial creep torque command responsive to an operator braking request and responsive to a change in direction of vehicle speed relative to the operator-selected direction of travel, and operating the hybrid powertrain to generate axle torque in response to the adjusted creep torque command.

First claim

The invention claimed is:

1. A controller-implemented method for operating a powertrain system of a vehicle, comprising:
monitoring an initial creep torque command and an operator-selected direction of travel;
monitoring a magnitude and a direction of vehicle speed;
monitoring an operator braking request magnitude;
determining a braking-modified creep torque command by adjusting the initial creep torque command through multiplication by a first multiplier ranging between 0 and 1 in direct relation to the operator braking request magnitude;
providing a second multiplier inversely related to said first multiplier when the direction of vehicle speed is opposite the operator-selected direction of travel;
determining a second creep torque command by adjusting the braking-modified creep torque command through multiplication by said second multiplier;
selecting a second braking-modified creep torque command as one of the initial creep torque command and the second creep torque command based upon a comparison of the initial creep torque command with a torque threshold;
determining a preferred axle creep torque command as the lesser of the second braking-modified creep torque command and the initial creep torque command; and
operating the hybrid powertrain to generate axle torque that is responsive to the preferred axle creep torque command.

2. The method of claim 1 , wherein operating the hybrid powertrain to generate axle torque that is responsive to the preferred axle creep torque command comprises:
monitoring an operator acceleration request; and
operating the powertrain responsive to the initial creep torque command in the operator-selected direction of travel when the operator acceleration request is zero and the magnitude of vehicle speed is less than a speed threshold associated with creep operation.

3. A controller-implemented method for operating a hybrid powertrain system of a vehicle, comprising:
monitoring an initial creep torque command and an operator-selected direction of travel;
monitoring a magnitude and a direction of vehicle speed;
monitoring an operator braking request magnitude;
determining a braking-modified creep torque command by adjusting the initial creep torque command through multiplication by a first multiplier ranging between 0 and 1 in direct relation to the operator braking request magnitude;
providing a second multiplier inversely related to said first multiplier when the direction of vehicle speed is opposite the operator-selected direction of travel and otherwise equal to 1 when the direction of vehicle speed is the operator-selected direction of travel;
determining a second creep torque command by adjusting the braking-modified creep torque command through multiplication by said second multiplier;
selecting a second braking-modified creep torque command as one of the initial creep torque command and the second creep torque command based upon a comparison of the initial creep torque command with a torque threshold;
operating the hybrid powertrain to generate a magnitude of axle torque that is equivalent to the initial creep torque command in the operator-selected direction of travel when the initial creep torque command is less than said torque threshold; and
operating the hybrid powertrain to generate a magnitude of axle torque that is equivalent to the second braking-modified creep torque command in the operator-selected direction of travel when the initial creep torque command is greater than said torque threshold and greater than said second braking-modified creep torque command.

4. The method of claim 3 , wherein the speed threshold associated with vehicle creep operation comprises a speed threshold of 8 km/h.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Heisel Adam J

Classifications

• Y02T10/62

  Hybrid vehicles · CPC title

• B60W2520/06

  Direction of travel · CPC title

• B60W30/18063 Primary

  Creeping · CPC title

• B60W2540/10

  Accelerator pedal position · CPC title

• B60W30/18036

  Reversing · CPC title