Active Torque Transfer System
The Active Torque Transfer System (ATTS) developed by Honda is an electronic and mechanical auxiliary system that improves the driving characteristics of front-wheel drive vehicles by reducing oversteer and understeer .
Basic principle
If a curve is to be negotiated, the wheels on the outside of the curve must be driven more powerfully than the wheels on the inside of the curve. The radius of the curve becomes tighter, the greater the difference in the forces on the outer and inner wheels. An example can be given of a rower in a rowing boat who rowed more vigorously with the oar on the outside of the curve than on the inside.
Mode of action
If a front-wheel drive vehicle drives through a curve at high speed , the vehicle tends to understeer . This means that the vehicle travels a wider arc than desired. ATTS intervenes preventively by distributing the drive force variably to the driven wheels and driving the heavily loaded wheel on the outside of the curve more strongly than the wheel on the inside of the curve. The wheel on the outside of the curve actively supports cornering and also pulls the car.
Other positive effects are the increase in traction and greater effectiveness . The system works in reverse when decelerating in a curve and thereby minimizes oversteering . Since oversteering or readjusting when the accelerator is released in a bend may well be desirable during sporty driving, this effect is often perceived as annoying.
Dynamic force distribution
In contrast to a conventional differential gear , with ATTS it is possible to apply different torques to the drive wheels. The dynamic force distribution depends on the curve radius, the gear shift position, the lateral acceleration and the load condition of the vehicle and is achieved by two multi-plate clutches and two electronically controlled planetary gear sets. If the electronic ATTS torque control device detects a tendency to understeer, the drive force is distributed to the wheel on the outside of the curve in such a way that there is a speed difference of up to 15% compared to the wheel on the inside of the curve. This task is taken over by the mechanical torque control unit (MCU torque control unit), which is attached directly to the differential gear. The system can deliver up to 80% of the total torque to a wheel.
history
ATTS was first offered as an option in 1997 in the Honda Prelude V sports coupé , but was only installed in a few vehicles due to the surcharge. ATTS was not used in other vehicles. Thanks to the ATTS system, the Honda Prelude was voted “best-handling car under $ 30,000” in the American Car and Driver Magazine 1997. The models with ATTS had the additional designation SH ("Super-Handling"). Today, however, the very innovative approach of ATTS is considered obsolete because a similar effect can be achieved with electronic, so-called intelligent differential locks. A further development of the ATTS is the all-wheel drive SH-AWD ( Super Handling All Wheel Drive ) of the Honda Legend .
literature
- Mike Ancas: Honda & Acura performance handbook. MotorBooks / MBI Publishing Company, 1999, ISBN 978-0-7603-0669-7 , p. 125 ( Google Book ).
Web links
- ATTS = Active Torque Transfer System. Retrieved December 28, 2009 .
- Direct yaw moment control by Active Torque Transfer System (ATTS). (PDF) In: Development of SH-AWD, Vehicle Dynamics EXPO 2005. p. 4 , archived from the original on March 25, 2006 ; accessed on January 2, 2014 .
- Douglas Kott: Prelude Type SH. (PDF; 2.7 MB) In: Road & Track magazine. November 1996, p. 92 , accessed December 30, 2009 .
Individual evidence
- ↑ 1997-2001 Honda Prelude: Full Review, Vehicle Highlights. (No longer available online.) Archived from the original on January 13, 2010 ; accessed on December 31, 2009 .
- ↑ Honda Prelude, Fifth_Generation. Retrieved December 31, 2009 .
- ↑ SH-AWD = Super Handling All-Wheel Drive. Retrieved December 31, 2009 .