TOYOTA LATEST CVT TRANSMISSION TECHNOLOGY

TOYOTA CVT TRANSMISSION TECHNOLOGY

Figure 1. TOYOTA SUPER CVT-I

The current trend for Toyota transmission is CVT transmission.

The Super CVT-I 7 speed automatic transmission of the Corolla Altis 2011 varies in functionality from the conventional 4-speed torque converter based automatic transmission gearbox you find in the conventional corolla automatic.

The ideal CVT system works on infinite gear ratios which vary continuously over wide range and give a low loss transmission performance. The conventional automatic with fluid based torque converter transmission causes some losses, so its not very fuel efficient. However the CVT may also cause some practical problems and slip in due to the nature of the transmission mechanism. To overcome the disadvantages of these two system, Toyota has developed a 7-Speed CVT-I transmission which is not the ideal implementation of the CVT, but it makes use of 7 gears controlled on which the gear shift is intelligently controlled by a control system to keep the engine RPM of the car in the optimum range for superior fuel efficiency and power response of the car.

Figure 2 :The current Toyota Corolla or Toyota Altis in Malaysia is using Toyota Super CVT-i in all its variant.

Hybrid Transmission

A hybrid transmission that uses Toyota’s original power split device.

  

  The hybrid transmission consists of the power split device, the generator, the electric motor and the reduction gears, etc. The power from the engine is split into two by the power split device. One of the output shafts is connected to the motor and the wheels while the other is connected to the generator. In this way, the motive power from the engine is transmitted through two routes, i.e., a mechanical route and an electrical route.

  An electronically controlled continuously variable transmission is also provided, which can change speed while continuously varying the rpm of the engine and the rpm of the generator and the electric motor (in relation to vehicle speed).

  THS II also reduces friction loss by about 30% by using ball bearings in the transmission and low-friction.

 

 Power Split Device
   The power split device uses a planetary gear. The rotational shaft of the planetary carrier inside the gear mechanism is directly linked to the engine, and transmits the motive power to the outer ring gear and the inner sun gear via pinion gears. The rotational shaft of the ring gear is directly linked to the motor and transmits the drive force to the wheels, while the rotational shaft of the sun gear is directly linked to the generator.