Torque distribution
Under torque distribution (engl. Active Yaw . Resp Torque Vectoring ) is the active influence of the yaw angle of motor vehicles (English "Yaw Angle".) And the yaw rate (yaw rate, closely "Yaw rate".) - or simply put: With torque distribution Systems, a motor vehicle can also be steered using the wheels by specifically distributing the drive torques left and right differently. The system is not to be confused with steering, active steering, all-wheel steering or active rear axle kinematics (e.g. rear-wheel steering in the BMW 850). The effect is based on a controlled redistribution of the drive torque, not on changing the wheel position.
Mode of action
The classic, open differential gear always distributes drive torque equally; the left and right wheels always transmit the same forces, which means that the transmission is free of yaw moments.
In the case of a limited slip differential , on the other hand, torque can be shifted from the faster turning to the slower turning wheel. Steering effects occur when cornering. Since the slower wheel receives more drive torque during normal cornering, this means that a vehicle with a limited-slip differential resists steering movements and tends to understeer, or to put it positively: it has better straight-line stability. The behavior changes under high lateral accelerations. The wheel on the inside of the bend is relieved and tends to spin. The limited slip differential directs most of the torque to the wheel on the outside of the bend, which results in a turning (oversteering) yaw moment when accelerating and a turning out yaw moment (understeering) when overrun.
Torque distribution systems are electronically controlled and can supply both the faster and the slower wheel with higher torque, so that cornering is specifically supported or suppressed. A torque distribution system thus also includes the function of an electronically controlled locking differential. For the purpose of redistribution, part of the drive torque is directed from the differential carrier to the desired wheel. In principle, this is the reverse of ESP , in which the yaw moment is influenced by braking intervention (instead of drive torque). The interaction of yaw control and ESP is that the yaw control improves the stability of the vehicle during dynamic driving and thus an intervention of the ESP is delayed. However, as soon as the ESP detects a critical driving condition, it takes over control and deactivates (as of 2008) the yaw control. Future developments will possibly also use a yaw control.
The electronic control allows typical characteristics of the brand, e.g. B. specifically support the driving behavior of a rear-wheel drive in fast corners and at the same time limit the risks (loss of control). In this way, the driver receives the driving behavior he expects without risking side effects or impairing everyday practicality.
history
Automotive sector
Technically, this concept was z. B. in the Mitsubishi Lancer Evolution IV (called Active-Yaw-Control , AYC for short, since 1996 with development contribution from GKN Driveline ) brought into series production for the first time. In the same year such a system was optionally available for the 5th generation of the Honda Prelude under the name ATTS . The technical structures are still the basis of the current and expected systems today. In the Honda / Acura Legend (Super Handling All Wheel Drive System, or SH-AWD), this system was implemented since of 2004. The BMW X6 also has a torque vectoring rear axle drive from ZF Friedrichshafen and GKN Driveline . Audi followed suit in 2008 with a system from Magna Steyr in the Audi S4 . Nissan uses the system in the all-wheel drive version of the Juke model, which has been available since 2010 . Torque Vectoring Control has been part of the basic equipment in the new Ford Focus since model year 2012 . The MUTE electric mobility project of the Technical University of Munich also relies on torque vectoring. The functionality of the control including pre-control is described in the work "Method for creating and safeguarding a model-based target specification for vehicle dynamics control systems" by Michael Graf. Vehicles with a purely electric drive result in expanded options and potential for torque vectoring.
formula 1
In Formula 1, a very similar system called the Front-Torque Transfer System was used with the Benetton B199 . The BAR team perfected this system over the years, but the FIA banned the system from the 2004 Formula 1 World Championship .
Web links
Active Yaw details and patents . Retrieved March 21, 2011.
Individual evidence
- ↑ dict.cc torque vectoring
- ↑ Automotive-Technology.de: "The new Audi RS6 Avant in the driving report"
- ↑ MUTE - TUM ELECTRIC MOBILITY: chassis . Technical University of Munich. 2011. Retrieved March 21, 2011.
- ↑ Method for creating and safeguarding a model-based target specification for vehicle dynamics control systems . Technical University of Munich. 2014. Accessed March 21, 2015.