摘要 |
A hybrid drive system for use in a drive train assembly of a vehicle includes a control apparatus that operates the hybrid drive system in either a normal energy recovery mode in response to a braking request or an extended braking mode in response to an extended braking request. In the normal energy recovery mode, fluid is pumped to an accumulator, which consumes kinetic energy of the vehicle and causes deceleration of the vehicle. In the extended braking mode, fluid is pumped through a pressure relief valve containing a restriction, which consumes the kinetic energy of the vehicle and causes deceleration of the vehicle. If the temperature of the fluid being pumped through the pressure relief valve exceeds a predetermined value, fluid is alternatively pumped through a pump/motor operating in a motoring mode, which consumes the kinetic energy of the vehicle and causes deceleration the vehicle. |