Hybrid vehicle front end accessory drive control system and method

Abstract

A method of operating an accessory drive system for a motor vehicle, wherein the accessory drive system includes one or more accessory components, a motor generator of the motor vehicle, and a flexible drive element configured to transmit a torque load between the one or more accessory components and the motor generator, includes determining a maximum permissible flexible drive element torque threshold, detecting an increase in torque demand on the flexible drive element, determining when the torque demand on the flexible drive element will exceed the flexible drive element torque threshold, and reducing the torque demand of one or more of the accessory components so that the flexible drive element torque threshold is not exceeded.

What is claimed is: 
     
         1 . A method of operating an accessory drive system for a hybrid vehicle having pulleys associated with an engine, a motor/generator, and an air conditioning compressor driven by a belt, comprising, by a vehicle controller:
 measuring a belt parameter;   adjusting a belt torque threshold based on the belt parameter; and   controlling torque of the motor/generator and/or the air conditioning compressor responsive to a regenerative braking event to maintain the belt torque below the belt torque threshold.   
     
     
         2 . The method of  claim 1  wherein adjusting the belt torque threshold comprises accessing a lookup table based on the belt parameter. 
     
     
         3 . The method of  claim 1  wherein the belt parameter is an age of the belt. 
     
     
         4 . The method of  claim 1  wherein the vehicle controller is configured to control torque by disengaging a clutch associated with the air conditioning compressor. 
     
     
         5 . A vehicle comprising:
 an engine having a drive pulley;   a belt-driven integrated starter generator (ISG) having an ISG pulley;   an accessory having an accessory pulley, wherein a belt coupled to the drive pulley drives the accessory pulley and the ISG pulley; and   a controller configured to reduce torque demand of the accessory responsive to a regenerative braking event so that torque applied to the belt is less than a torque limit adjusted by the controller.   
     
     
         6 . The vehicle of  claim 5  wherein the controller reduces the torque demand of the accessory for a predetermined time period. 
     
     
         7 . The vehicle of  claim 5  wherein the controller reduces the torque demand of the accessory for a duration of the regenerative braking event. 
     
     
         8 . The vehicle of  claim 5  wherein the accessory comprises an air conditioning compressor.