Electromechanical variable transmission

Abstract

A drive train includes a first gear set including a sun gear, a ring gear and planetary gears coupling the sun gear to the ring gear, a second gear set including a sun gear, a ring gear and planetary gears coupling the sun gear to the ring gear, a first motor/generator coupled to the first gear set, a second motor/generator coupled to the second gear set, and at least one of (a) a first clutch that selectively engages the second motor/generator with the first gear set and (b) a second clutch that selectively engages the ring gear of the second gear set with the planetary gear carrier of at least one of the first gear set and the second gear set. The planetary gears of both sets are rotatably supported by respective planetary gear carriers.

1 . A drive train for a vehicle, comprising:
 a first gear set comprising a sun gear, a ring gear and planetary gears coupling the sun gear to the ring gear;   a second gear set comprising a sun gear, a ring gear and planetary gears coupling the sun gear to the ring gear, wherein the planetary gears of both sets are rotatably supported by respective planetary gear carriers;   a first motor/generator coupled to the first gear set;   a second motor/generator coupled to the second gear set; and   at least one of:
 a first clutch that selectively engages the second motor/generator with the first gear set; and 
 a second clutch that selectively engages the ring gear of the second gear set with the planetary gear carrier of at least one of the first gear set and the second gear set. 
   
     
     
         2 . The drive train of  claim 1 , wherein at least one of the first gear set and the second gear set are at least selectively engaged with an output shaft of an engine. 
     
     
         3 . The drive train of  claim 1 , further comprising a third gear set including at least two gears that couple the first clutch to the second motor/generator. 
     
     
         4 . The drive train of  claim 1 , further comprising a brake mechanism configured to selectively prevent rotation of the first motor/generator. 
     
     
         5 . The drive train of  claim 4 , further comprising a third clutch selectively coupling the brake mechanism to the first motor/generator. 
     
     
         6 . The drive train of  claim 1 , wherein the drive train comprises the first clutch that selectively engages the second motor/generator with the first gear set. 
     
     
         7 . The drive train of  claim 6 , wherein the first clutch selectively engages the second motor/generator with the ring gear of the first gear set. 
     
     
         8 . The drive train of  claim 1 , wherein the drive train comprises the second clutch that selectively engages the ring gear of the second gear set with the planetary gear carrier of the at least one of the first gear set and the second gear set. 
     
     
         9 . The drive train of  claim 8 , wherein the second clutch selectively engages the ring gear of the second gear set with the planetary gear carrier of the first gear set and the planetary gear carrier of the second gear set. 
     
     
         10 . A drive train for a vehicle, comprising:
 a first planetary gear set;   a second planetary gear set directly attached to the first planetary gear set;   an output shaft coupled to at least one of the first and the second planetary gear sets and radially offset from the first and second planetary gear sets;   a first electromagnetic device directly coupled to the first planetary gear set; and   a second electromagnetic device coupled to the second planetary gear set and selectively rotationally engaged with the first planetary gear set.   
     
     
         11 . The drive train of  claim 10 , wherein the first and second electromagnetic devices are aligned. 
     
     
         12 . The drive train of  claim 10 , wherein at least one of the first electromagnetic device and the second electromagnetic device comprises a motor/generator. 
     
     
         13 . The drive train of  claim 10 , wherein the first and second planetary gear sets are aligned. 
     
     
         14 . The drive train of  claim 10 , wherein the first planetary gear set includes a first planetary gear carrier, and wherein the second planetary gear set includes a second planetary gear carrier that is fixed to the first planetary gear carrier. 
     
     
         15 . A vehicle, comprising:
 a transmission comprising a first gear set having a first planetary gear carrier and a second gear set having a second planetary gear carrier;   a first motor/generator coupled to the first gear set; and   a second motor/generator coupled to the second gear set;   wherein during a first mode of operation of the vehicle the second motor/generator is disengaged from the first gear set, and   wherein during a second mode of operation of the vehicle the second motor/generator is coupled to the first gear set.   
     
     
         16 . The vehicle of  claim 15 , wherein during the second mode of operation, the second motor/generator is coupled to an output shaft of an engine. 
     
     
         17 . The vehicle of  claim 15 , wherein the first planetary gear carrier is coupled to the second planetary gear carrier. 
     
     
         18 . The vehicle of  claim 15 , wherein the transmission further comprises a third gear set that is coupled to a drive axle of the vehicle. 
     
     
         19 . The vehicle of  claim 15 , wherein the first motor/generator and the second motor/generator are aligned. 
     
     
         20 . The vehicle of  claim 15 , wherein the first planetary gear carrier and the second planetary gear carrier are aligned.