ELECTRONIC TRACTION CONTROL.

Presentation by Dun Wataka. What to expect in this presentation..

➢Introduction. ➢History. ➢Components of traction control. ➢Operation of Electronic Control. ➢ When is Traction control useful. And lastly, The Limitations of Traction Control. Introduction: The basic idea behind the need for a is the loss of grip that compromises steering control and stability of vehicles because of the difference in traction of the drive wheels. This mostly causes slippage. Traction control helps limit tire slip in acceleration on slippery surfaces. What may cause slippage?... Difference in slip may occur due to...

• Turning of a vehicle . When a car turns, its outer and inner wheels rotate at different speeds; this is conventionally controlled by using a differential.

• Varying road conditions for different wheels. Wet and loose gravel on roads or pavements lowers tire traction. This are the common abbreviations of Electronic Traction Control which you may come across: ASR is solely in Mercedes, Audi and Volkswagen. ASC can only be seen in a BMW. DSA is used in Opel cars. TRC was developed specifically for Toyota. TCS is unique to Honda.

HISTORY: It all started from a purely mechanical system that transfer a relatively small amount of power to the non-slipping wheel, while still allowing some wheel spin to occur. It was found in high Torque,high power rear-wheel drive vehicles as a LIMITED SLIP DIFFERENTIAL. Sometimes referred to as Positraction, a limited-slip rear axle will mechanically transfer power to the rear wheel with the most traction, helping to reduce, but not eliminate wheel spin. ❑ limited-slip differential prevents excessive power from being allocated to one wheel, and so keeps both wheels in powered rotation, ensuring that the traction will not be limited to the wheel which can handle the minimum amount of power. Back in 1971, introduced Maxtrac which used an early computer system to detect rear wheel spin and modulate engine power to the wheels to provide the most traction.

First gen of Buick MaxTrac 1979 Cadillac introduced the traction monitoring system on the Redesigned Eldorado.

Later,more manufactures adapted traction control into their products. 1971 1975 Buick LeSabre

1973 225 Buick Centurion Components of Traction Control: Basic system components include.. ✓ Engine control unit, ✓ Transmission speed sensor, ✓ Wheel speed sensors, ✓ Traction electronic control unit, ✓ On and Off switch, ✓ Electrical harness.

Over the past years there is no significant change in the components in traction control system. ENGINE CONTROL UNIT Traction control systems have different ways of reducing the rotational speed of individual wheels. Some “pump” the brake to the problem wheel, while other systems combine wheel braking with reduced engine power. In a vehicle that uses reduced engine power to control the rotation of slipping wheels, the driver may experience a pulsation of the gas pedal when traction control is active. This sensation is similar to the experience of having the brake pedal pulsate when ABS is active.This is by the help of Engine control unit in: Electronically limiting throttle application , Electronically limiting fuel delivery, Retarding Ignition spark or Completely shutting down Engine cylinders. Transmission speed sensor This sensor is a mechanically driven electromagnetically device which produces an AC voltage with frequency proportional to the input shaft speed. In comparison to typical speed sensors that use a magnet to generate a reference voltage; the Hall-Effect sensor employs its own reference voltage signal. The sensor is mounted in the transmission output shaft. Its function is to convert the rear wheel speed into an electrical signal at a frequency of 25Hz/mph. This rear wheel speed signal is transmitted via the electrical harness to the electronic controller.

WHEEL SPEED SENSORS Even some vehicles without anti-lock brake systems (ABS) will use wheel speed sensors as the vehicle speed input for the engine control module and transmission control module. This is a an electromagnetic device which in conjunction with the rotating speed disc, produces an AC voltage with frequency proportional to the speed of the disc.The speed disc is mounted on the hub of the wheels.The sensor is mounted ata predetermined distance from the disc and the gap is adjusted at the sensor mounting. The function is to convert the wheel speed into an electrical signal at a frequency of 6.25Hz/mph. Wheel speed signals are sent via electrical harness to the electronic controller.

TRACTION CONTROL UNIT

The controller is a solid state electronic computer.it receives the speed signals from the different sensors, processes the information and initiates braking to the affected wheels via a cable connected to an automatic traction control (ATC) valve or ABS control module.The Traction Control module is mostly incorporated with the ESP control unit. Automatic Traction Control valve(ATC) Location of traction control module. "ON-OFF" SWITCHES The ON-OFF switch is mostly located on the instrument panel or on the centre console. It allows the driver to access and activate or deactivate the system easily. It is recommended that the switch normally be in the "ON" position. However its desirable to have the system inoperative under certain driving conditions. I.E Rocking the car in snow.Also,should a malfunction in the system occur, the vehicle may be driven with the switch "OFF" until the repairs are made. ELECTRICAL HARNESS The harness provide electrical connection between the sensors and different components involved in Traction control such as ▪ Traction controller, ▪ Speed sensors, ▪ power source, ▪ ignition switch, ▪ brake switch, ▪ engine module, ▪ transmission module and ▪ traction switches, ▪OPERATION OF ELECTRONIC TRACTION CONTROL Mostly Traction control unit is incorporated into another control unit such as ESP module. Traction control works similar to ABS and is often considered as a supplement to existing ABS setups. Both systems work to solve opposite problems associated with wheel slippage or wheel lockage. In fact, in most modern vehicles the traction control feature uses the same components as ABS, including wheel-speed sensors, hydraulic modulator, and ECU. Traction Control as an additional feature to ABS it has an additional valve to the ABS system. This is the Automatic Traction Control Valve. When the ECU senses that one wheel is spinning faster than the others (an indicator that the wheel is losing traction), it sends a message to the hydraulic brake-modulator (attached to the ECU) and automatically reduces the speed of that wheel which lessens the slip by applying brake friction to the wheels with the lessened traction. This often occurs in conjunction with powertrain controller reducing available Engine torque. Also in Turbo-charged vehicles,a boost control solenoid is actuated to reduce boost and therefore engine power.

In Summary. Electronic Traction control system operation works hand in and with the safety systems so as to work efficiently uses a combination of signals so as to work efficiently and work accordingly. The following is diagrammatic overview of inputs and actuators which makes up the Traction control System.

When would traction control be useful? Traction control is useful whenever you are trying to accelerate in low-friction conditions. These conditions include when roads are wet, snowy, icy, uneven, or poorly maintained. Some concrete examples of when traction control would be useful include the following: • You are attempting to accelerate up a hill where the surface is loose and gravelly. Without traction control, your wheels spin and you begin to slide backwards. • You hit a patch of slushy road that causes your wheels to lose traction. As a result, your vehicle slows down and begins to fishtail. •Two of your wheels cross an icy section of road, causing them to spin and lose traction. As a result, your car turns sharply out of your control • You lose traction driving through a puddle. As a result, your vehicle cannot maintain its speed, leaving you in danger of being hit by other vehicles. • You are trying to accelerate at a green light on a slick road with traffic approaching you from behind. Does traction control have any limitations?

Yes. Traction control works by preventing your tires from slipping, thereby allowing your wheels to take full advantage of the traction that is available on the road. Traction control cannot increase the total amount of traction available. I.E If there is no traction on the road because the road is iced-over completely, then no one has traction. Traction control cannot create traction where it does not exist. Drivers who choose to drive in slippery conditions face the challenge of reduced traction equally, whether or not they have traction control on their vehicle. The difference is that drivers with traction control are more likely to successfully accelerate in low-traction conditions since traction control prevents their wheels from spinning. In addition, since the vehicle’s wheels are not spinning, drivers are able to maintain steering control. However, it cannot be overstated that drivers with traction control do not experience more traction; just better handling on whatever little traction is available. Therefore, drivers are encouraged to limit or avoid driving in slippery, low-friction conditions, whether or not they have traction control. On a related note, while vehicles without traction control might experience a reduction in speed on slippery roads, the same speed reduction may not be observed in vehicles with traction control. As such, the traction control system may allow vehicles to reach a higher speed than is desirable for roadway conditions. You should always take care to monitor your speed and to ensure that it does not exceed what is safe for current conditions. Lastly, have this picture in mind to remind you the major importance of Traction control.

THE END OF TRACTION CONTROL.