Variable speed accessory drive system

Abstract

The present invention provides an accessory drive system for a vehicle. The accessory drive system includes a planetary gear set having a first, second, and third planetary member. A torque transfer device operatively connects an engine with the first planetary member. A motor/generator is operatively connected to the second planetary member, and a plurality of accessories are operatively connected to the third planetary member. Engine output is transferable through the planetary gear set to drive the accessories, and the speed at which the accessories are driven is selectable by controlling the speed of the motor/generator.

1 . An accessory drive system for a vehicle comprising:
 an engine;   an accessory operatively connected to the engine;   a planetary gear set disposed between the engine and the accessory;   a motor/generator operatively connected to the planetary gear set;   wherein output from said engine is transferable through the planetary gear set to drive the accessories, and the speed at which the accessories are driven is selectable by controlling the speed of the motor/generator.   
     
     
         2 . The accessory drive system of  claim 1 , further comprising a plurality of pulleys configured to transfer output from the engine to the accessories. 
     
     
         3 . The accessory drive system of  claim 1 , further comprising at least one belt operatively connecting said plurality of pulleys. 
     
     
         4 . The accessory drive system of  claim 1 , further comprising a gear assembly operatively connecting the motor/generator to the planetary gear set. 
     
     
         5 . The accessory drive system of  claim 1 , further comprising a second planetary gear set operatively connected between the engine and the accessory. 
     
     
         6 . An accessory drive system for a vehicle comprising:
 a planetary gear set having a first, second, and third planetary member;   an engine operatively connected to the first planetary member;   a motor/generator operatively connected to the second planetary member; and   a plurality of accessories operatively connected to the third planetary member;   wherein engine output is transferable through the planetary gear set to drive the plurality of accessories, and the speed at which the plurality of accessories are driven is selectable by controlling the torque transfer from the motor/generator to the second planetary member.   
     
     
         7 . The accessory drive system of  claim 6 , wherein the first planetary member is a ring gear member, the second planetary member is a sun gear member, and the third planetary member is a planet carrier member. 
     
     
         8 . The accessory drive system of  claim 6 , wherein the first planetary member is a sun gear member, the second planetary member is a planet carrier member, and the third planetary member is a ring gear member. 
     
     
         9 . The accessory drive system of  claim 6 , wherein the first planetary member is a ring gear member, the second planetary member is a planet carrier member, and the third planetary member is a sun gear member. 
     
     
         10 . The accessory drive system of  claim 6 , wherein the first planetary member is a planet carrier member, the second planetary member is a ring gear member, and the third planetary member is a sun gear member. 
     
     
         11 . The accessory drive system of  claim 6 , wherein the first planetary member is a planet carrier member, the second planetary member is a sun gear member, and the third planetary member is a ring gear member. 
     
     
         12 . The accessory drive system of  claim 6 , wherein the first planetary member is a sun gear member, the second planetary member is a ring gear member, and the third planetary member is a planet carrier member. 
     
     
         13 . The accessory drive system of  claim 6 , further comprising a gear assembly operatively connecting the motor/generator to the second planetary member. 
     
     
         14 . The accessory drive system of  claim 6 , further comprising a belt operatively connecting the motor/generator to the second planetary member. 
     
     
         15 . The accessory drive system of  claim 6 , further comprising a chain operatively connecting the motor/generator to the second planetary member. 
     
     
         16 . The accessory drive system of  claim 6 , wherein one of the first, second, and third planetary members is a double-pinion carrier. 
     
     
         17 . The accessory drive system of  claim 6 , wherein one of the first, second, and third planetary members is a single-pinion carrier. 
     
     
         18 . An accessory drive system comprising:
 a planetary gear set having a first, second, and third planetary member;   a first torque transfer apparatus operatively connecting an engine to the first planetary member;   a second torque transfer apparatus operatively connecting a motor/generator to the second planetary member; and   an accessory operatively connected to the third planetary member;   wherein the engine provides sufficient rotational resistance while off to restrain the first planetary member from rotating and thereby allow the motor/generator to drive the accessory without also driving the engine.   
     
     
         19 . The accessory drive system of  claim 18 , wherein the first and second torque transfer apparatus includes a gear assembly. 
     
     
         20 . The accessory drive system of  claim 18 , further comprising a chain operatively connecting the motor/generator to the second planetary member.