Active Torque Transfer System (ATTS)

DESCRIPTION
The active torque transfer system (ATTS) detects the engine torque, transmission gear position, acceleration and cornering condition of the vehicle. This is done by means of the engine speed, manifold absolute pressure (MAP) sensor, backup light switch, front and rear wheel sensors, steering angle sensor, lateral G sensor and the yaw rate sensor. As these data are put in the ATTS control unit, it determines the driving force of the right and left wheels. The then system controls the right and left clutch pressure according to the determined driving force by transmitting the signal to the ATTS unit and thereby distributes the driving force to the right and left wheels.

OPERATION
Acceleration Rate And Distribution Ratio
The driving force distribution rate is set as 8:2 between the outer wheels and inner wheels. The vehicle is equipped with an acceleration mechanism to distribute the driving force with wet clutches (torque is transmitted from the high speed side to the low speed side), where the acceleration ratio is set at 15%.

When Driving Straight Forward (ATTS Not Activated):
- Right and left clutches are OFF.
- The planetary pinion gears, center central gear, right central gear, and left central gear engage each other and rotate as an assembly. Therefore, there is no difference in acceleration between the right and left wheels.








When Turning To The Right (ATTS Activated):
- The right clutch is ON.
- Because the center central gear and right central gear are turning, the rotation speed from the right central gear to the planetary pinion gear increases at a ratio of 30/16, while the speed from the planetary pinion gear to the center central gear decrease at a ratio of 16/26. See the following formula that shows the rotation speed of the center central gear increases at a ratio of approximately 1.15.








When Turning To The Left (ATTS Activated):
- The left clutch is ON.
- The left central gear is fixed.
- Because the planetary pinion gear is engaged with the led central gear, it rotates around the central gears while rotating on its axis.
- When the planetary pinion shaft makes one full turn, the planetary pinion gear turns around the led central gear at a ratio of 32/28. It also turns around the center central gear at a ratio of 16/30. Therefore, the following formula shows that the rotation speed of the right central gear increases at a ratio of approximately 1.15.