The Technology Review reports that Toyota may have the lead in hybrid vehicles but General Motors, DaimlerChrysler, and BMW have joined forces to develop transmission technology that could beat Toyota's system by applying mechanical engineering to catch up.
Toyota's transmission enables hybrids to start in all-electric mode, leaving the engine off during the low-speed, high-torque regime where mechanical power from the engine is least efficient. The engine comes on only when the driver requests more power than the electric motors can provide or to recharge the vehicle's battery.
Engineers at GM, DaimlerChrysler, and BMW are developing a new transmission system that delivers EV-mode operation just like Toyota. The transmission adds one more feature: the system can also take the electric side of the drivetrain out of the loop and run in engine-only mode. Their two-mode hybrid transmission, patented in 1999 by GM and currently used in its hybrid buses, swaps out the motors with a set of fixed gears, locking the engine to the driveshaft