Traction control system

The traction control system (TCS ), also called Traction control, ensures that the wheels do not spin when accelerating. The traction control is to prevent starting up with a lot of gas ( " racing start " ) or in bad surfaces such as ice, snow, gravel, wet cobblestone (low friction ) that one or by rotating a plurality of wheels and the vehicle breaks the side. Counterpart is the engine drag torque control (MSR ), which should lessen a vehicle instability during abrupt gas removal.

The system has many manufacturers have different names:

• Audi: ( ASR)
• BMW: Automatic Stability Control (ASC )
• Fiat: ( ASR)
• Hyundai: (TSC )
• Mazda: Traction Control System (TCS )
• Mercedes: ( ASR)
• Nissan: Traction Control System (TCS )
• Opel / GM: Traction Control Support System ( TCSS )
• Peugeot: ( ASR)
• Porsche: ASR as part of the Porsche Stability Management ( PSM)
• Saab: Traction Control System (TCS )
• Renault: ( ASR)
• Suzuki: ( ASR)
• Toyota: Traction Control (TRC )
• Volkswagen: ( ASR)
• Volvo: Traction Control System ( TRACS )

• 3.1 launch cars
• 3.2 launch motorcycle

Basics

ASR occurs when the wheels start to spin when starting a vehicle, meaning they have no or very little grip on the street. Is there a risk of excessive slippage of the drive wheels, the drive torque is regulated by selective braking or / and engine management intervention. The control system, which, inter alia, receives its information about the anti -lock brake system wheel speed sensors, thus ensuring traction and stability during the acceleration phase, both on straight track and in curves. Fully trained ASR systems come in their traditional operating areas very close to the electronic stability program approach, but not replace it. Intervention in the brake will take place at lower speeds to optimize traction. The engine intervention generally brings the driving stability over the entire speed range. Because some manufacturers of control intervention usually somewhat coarsely done and also pollutes the brake, such systems are switched off at higher speeds usually. In narrow limits (Start) ASR can take over the function of a locking differential.

It was the first driver assistance system that independently of the driver built up brake pressure. This provided a reasonable driving stability in critical driving situations.

Function

While driving the speed sensors monitor together with the control unit the slip behavior of the drive wheels (whether front, rear or all-wheel drive ). When the driver is more gas to the torque and hence the drive torque increases at the wheels, the wheel slip increases. With a wheel slip of about 10 to 20% of the adhesion reached a maximum on dry pavement, the transferable by the tire circumferential forces reach their maximum.

The drive torque is increased further, the adhesion decreases, the transmittable torque is reduced and at least a wheel is tending to spin. Depending on road surface and slip rate, both wheels can be affected. Due to the associated with excessive scope slippage loss of cornering potential drivability can also be unstable. Now ASR is active and controls the drive torque to the wheels with several measures.

Some ASR systems take into account the steering angle.

Traction control by brake

Simple ASR systems usually only have access to the brake. As the mechanical components are already present by the anti- lock brake system ( ABS), the ASR is a hardware and software of the ABS and extension may each drive wheel brake separately. Such a procedure is required only for the wheels of which are driven. The wheel is braked too fast here and the other wheel will get more of the drive torque. The braking action is done without the driver's involvement. The ABS will be changed for an additional switching valve and a suction valve from the normal brake operating on ASR operation. The return pump of the ABS sucked from the master cylinder via the brake fluid inlet valve and produces the ASR system pressure.

Disadvantage is an active traction control on longer trips affects especially the offroad area: the brake discs or drums can be very hot, without you yourself ever braked.

Traction control via intervention in the engine control

Here a procedure is performed in the engine management. By reduction of the engine torque to a driven wheel or by rotating the entire drive shaft is counteracted. This is possible when the engine is either no mechanical link between the accelerator pedal to the throttle valve (petrol engine ) or fuel injection pump (diesel engine) or that it has installed a second throttle valve for the ASR in the Otto engine.

In the first case, the object of the power reduction takes an electronic accelerator. This e- gas function handles the ASR commands take precedence over the driver's request. Join ASR to great traction, the engine control unit adjusts the gasoline engine, the throttle valve and the ignition angle and hidden single injection and ignition signals from the injection system. In diesel engines, either the shift lever of the injection pump and in engines with common rail is reduced by means of a torque interface via the CAN data bus by the engine control unit, the amount of fuel at the request of ASR. In both cases, this reduces the excess motor and drive torque.

Combined control

Here both interventions take place over the braking system as well as via the engine management.

History

Even the built in 1939 under the leadership of Ferdinand Porsche, Mercedes- Benz T 80 was fitted with a device to prevent wheel slip. As a mass product was after the introduction of ABS, this system developed for ASR.

With the advent of ESP ASR has become an integral component in the vehicle control. ASR is the basis for the following ESP systems which contribute additionally has a sensor and a braking operation to the non- driven wheels, the vehicle stabilization. With the increasing complexity of such electronic systems is to be expected that maintenance and upkeep of statutory duty are, as in airplanes has long been the case.

The terms of the ASR vary depending on the manufacturer, additional distinction is often made between individual ASR systems, eg

• BMW: sole Automatic Stability Control (ASC ) = intervention in the engine management; ASC T = combined control
• Mercedes: Electronic Traction System (ETS ) = sole intervention of the braking system; ASR = combined control

Launch car

In 1971, the Buick division of General Motors Group, a traction control system called ' maxtrac ' a. It was equipped with appropriate sensors and a computer system to recognize the wheel spin and was able to distribute accordingly the force on the rear axle. ' Maxtrac ' was available as an accessory for all full-size models of Buick (Riviera, Estate Wagon, Electra 225, Centurion and LeSabre ). Less successful was the ' Traction Monitoring System ' (TMS ) of Cadillac, which was offered for the 1979 Eldorado. Criticism aroused a long reaction time and high error rates. In the above systems, however, is not a traction control system, from today's perspective, but merely an electronically controlled limited slip differential.

In 1987, the first Mercedes traction control system, according to current view in models of the W 126 series with a V8 engine ( S-Class ) to market; 1979 introduced the electronically controlled ABS in the previous model W 116.

Launch motorcycle

In 1992, Honda introduced the first time in his model the traction control a Pan European. Currently (November 2010), BMW R 1200 GS, BMW S 1000 RR, Ducati 1198 S, Kawasaki 1400 GTR, MV Agusta Brutale 1090 Yamaha XT 1200 Z Super Ténéré and Aprilia RSV4 Factory APRC equipped with it. The systems are based on different principles. Either by measuring the rear wheel speed increase ( MV Agusta ), Raddrehzahlabgleich of front and rear (BMW, Ducati, Kawasaki, Yamaha) or Raddrehzahlabgleich and skew sensor (BMW S 1000 RR), the electronics responds with an engagement on throttle and engine management. The reaction times of the system are 0.05 to 0.16 seconds, respectively, half a wheel rotation.