Patent ID: 7249810
Filing Date: 2007-07-31
Classification: B60T

Abstract:
1. A method for providing a desired braking torque in a vehicle, the method comprising the step of: determining a desired braking torque for the vehicle; activating a stepped retarder braking system during braking of the vehicle wherein the stepped retarder braking system has a capability of providing a plurality of steps of braking torque and a stepped braking torque provided by the stepped retarder braking system is a function of one of engine speed and transmission speed, by activating an infinitely-variable retarder braking system in cooperation with the stepped retarder braking system to provide a combined braking torque representing a difference between the step of braking torque provided by the stepped braking system and the desired braking torque, an infinitely variable braking torque provided by the infinitely variable retarder braking system is a function of one of engine speed and transmission speed and so that a sum of a braking torque of the stepped retarder braking system is continuously combined with the braking torque provided by the infinitely-variable retarder braking system to provide the desired braking torque.