Service brake control system for optimized regenerative braking of medium or heavy trucks

Abstract

Braking control for a hybrid vehicle provides both service and regenerative mode braking for the driven wheels. A hybrid drive system is coupled to the driven wheels to provide traction power and which is capable of operating in a regenerative braking mode. The service brakes are provided by pneumatically actuated service brakes coupled to the driven wheels. Braking is initiated conventionally using an operator controlled brake actuator. A pressure regulator is placed in a pneumatic brake actuation line coupled from the operator controlled brake actuator to the pneumatically actuated service brakes for the driven wheels. The pressure regulator initially closes during braking, preventing operation of the service brakes up to the limit of the ability of the hybrid drive system to absorb torque for regenerative braking. When the torque limit for the hybrid drive system is reached, the regulator opens the actuation line progressively allowing the service brakes to supplement the hybrid drive system. During loss of traction events regenerative braking is discontinued to avoid interference with operation of anti-lock braking of the vehicle's service brakes.