Traction control system
Traction control system has the following trade names depending on the manufacturer: ASR (Automatic Slip Regulation, Acceleration Slip Regulation) on Mercedes, Volkswagen, Audi and other vehicles. ASC (Anti-Slip Control) for BMW vehicles; A-TRAC (Active Traction Control) for Toyota vehicles; DSA (Dynamic Safety) for Opel vehicles; DTC (Dynamic Traction Control) for BMW vehicles; ETC (Electronic Traction Control) for Range Rover vehicles; ETS (Electronic Traction System) for Mercedes vehicles; STC (System Traction Control) for Volvo vehicles; TCS (Traction Control System) for Honda vehicles; TRC (Traking Control) for Toyota vehicles. Despite the diversity of names, the design and principle of operation of these traction control systems are similar in many ways, so let’s take the example of one of the most common systems – ASR. The traction control system is based on the structural basis of the anti-lock braking system. The ASR system has two functions: electronic differential lock and engine torque control. The system uses a return pump and additional solenoid valves (switch and high-pressure valve) for each of the driving wheels in the ABS hydraulic unit to implement the anti-locking functions. The ASR system is controlled by the corresponding software included in the ABS control unit. The ABS/ASR control unit communicates with the engine management system control unit in its operation. Operating principle of the traction control system: The ASR system prevents wheels from spinning across the entire range of vehicle speeds: 1) at low speeds (from 0 to 80 km/h) the system provides transmission of torque by braking the drive wheels; 2) at speeds above 80 km/h efforts are regulated by reducing the torque delivered by the engine. Based on wheel speed sensor signals, the ABS/ASR control unit determines the following features: -corner acceleration of driving wheels; -speed of the car (on the basis of non-driven wheel angular speed); -the nature of the car – straight-line or curved-line (on the basis of non-driven wheel angular speed comparison); -how much driving wheel slippage (on the basis of the difference between driving wheel angular speed and non-driven wheel angular speed). Depending on the current performance value, the brake pressure or motor torque is controlled.
Brake pressure control is cyclic. The duty cycle has three phases – pressure increase, pressure hold and pressure release. The increase in pressure of the brake fluid in the circuit ensures braking of the drive wheel. This is achieved by switching on the return pump, closing the switching valve and opening the high pressure valve. Pressure retention is achieved by switching off the return pump. Pressure release is accomplished at the end of slippage with the inlet and switching valves open. If necessary, the cycle is repeated.
Engine torque control is performed in conjunction with the engine management system. The traction control unit calculates the amount of torque required based on the information on drive wheel slip from the wheel speed sensors and the actual amount of torque received from the engine control unit. This information is transmitted to the engine control unit and is accomplished by various actions: -changing the throttle position; -skipping fuel injections in the injection system; -skipping ignition pulses or changing the ignition advance angle in the ignition system; -shifting gears in vehicles with automatic transmissions. When the traction control system is activated, the control lamp on the instrument panel illuminates. The system can be deactivated.
Diagram of the ASR traction control system (Fig. below) 1 compensation tank 2vacuum booster 3 brake pedal position sensor 4 brake system pressure sensor 5 control unit 6 return flow pump 7 pressure accumulator 8damping chamber 9inlet valve of front left brake mechanism 10outlet valve 10 Front left brake inlet valve 11 Rear right brake inlet valve 12 Rear right brake outlet valve 13 Front right brake inlet valve 14 Front right brake outlet valve 13 Front right brake inlet valve 15 Rear left brake inlet valve 16 Rear left brake outlet valve 17 Front left brake cylinder 18 Front left brake light 19 Front right brake cylinder 20 Front right brake light 21 Rear left brake cylinder 22 Rear left brake light 23 Rear right brake cylinder 24 Rear right brake light 25 Switching valve 26 High pressure valve 27 Data bus
The anti-skid system in the car: what is it, system disadvantages, disable with your own hands
The anti-skid system ensures driving safety on a bad road, prevents the car from getting stuck on a slippery or loose surface (in snow or soft ground).
Drivers are familiar with a difficult road situation, when due to poor grip the car loses control over driving. To increase driving safety, it is necessary to equip cars with electronics to get out of skids and stabilize the position. On poor Russian roads, which are often found outside of cities and highways, the anti-skid system in the car is indispensable.
Anti-skid system: what is it
Anti-boosting is a system to prevent slipping of driving wheels. Drivers are familiar with the situation when the engine roars, the wheels spin, but the car stands still, because it hit a slippery surface, and the tire tread cannot catch it to push off. This problem can be solved with the help of electronics. It will prevent the wheel from spinning in vain, brakes it and redirects the torque to the wheels that hold the road.
Schematic illustration of a traction control system
The anti-skid system is installed on all modern vehicles and provides safe driving on all roads and at all times of the year. It prevents accidents on wet and slippery asphalt, ice, loose soil or sand and snow. If necessary, the anti-boosting system can be easily deactivated.
How it works
The main function of the anti-bukes is to stop the wheel from spinning freely. To understand how the antibux system works in the car, it is necessary to know what it consists of. It is a control unit and sensors that determine:
- angular acceleration of the driving wheels;
- speed of the vehicle (calculated by the angular velocity of the non-driven wheels);
- features of the trajectory (curvilinear or rectilinear);
- value of slippage (electronics independently calculates difference between angular speed of driving wheels and non-driven wheels).
How the anti-boost works
Based on the data received, the anti-lock control unit located in the car corrects the braking force on the wheel and the torque transmitted from the engine. As a result, the car quickly stabilizes and starts to drive smoothly and smoothly.
Antibrake and brake pressure
The brake system has three cycles in total:
- increasing brake fluid pressure;
- holding pressure;
During the first phase, the brake pads are pressed against the disc of the active wheel and the brakes are applied. Pressure is pressurized into the hydraulic system by means of a special fast-acting return pump. The switching valve closes and the inlet valve opens. The pressure is held when this device is switched off. Resetting is accomplished by opening the discharge and switching valve. This occurs only after the slip has stopped. The cycle can be repeated an unlimited number of times if necessary.
Anti-boost and torque
The anti-boost control controls the torque when interacting with the engine. Information about the nature of the movement is transmitted to the control unit and the electronics determine the amount of torque. This requires knowledge of the slip of the drive wheels, their rotation speed and the speed of the vehicle. The necessary torque can be obtained by:
- throttle movements;
- adjusting the fuel injection volume or skipping injections;
- adjusting the advance angle in the ignition system;
- ignition pulse skipping;
- shift change cancellation – in cars with automatic transmission.
Traction control system icon on the dashboard
Immediately after activation of the traction control system, the corresponding light on the dashboard will illuminate. The driver will receive a signal that at the moment the car is in a difficult situation and the electronic system tries to stabilize its position and avoid a dangerous situation.
What type of traction control systems are there
Antiwheelspinch systems are installed on almost all modern cars. Their exact trade name depends on the manufacturer:
- ASR on Volkswagen Group vehicles;
- TCS on Honda vehicles;
- TRC on Toyota.
Various systems with the same principle of operation are now used. They all consist of controllers and solenoid valves (switching and high pressure) installed in the ABS hydrogroup.
The system is controlled by special software installed in the control unit of this system. It also interacts with the devices controlling the engine operation.
Traction control system button
Many drivers, often going on the road on a bad road, seek to create an anti-skid system with their own hands. It will be very difficult to install all the necessary control and monitoring units, adjust them and ensure the normal operation of electronics, so to prevent slipping, you can use mechanical ways to improve traction. But they only partially replace the anti-brake. It can be special pads or chains, improving the traction of the wheel with slippery roads, loose snow and the ground. Wheels with spikes will be enough for driving on icy city streets, but more effective anti-skidding methods will be needed for driving outside of paved roads. Anti-skidding mechanisms are sold in kits, easily installed on the wheels if necessary, and quickly removed when leaving on a good cleared road.
Why do you need a traction control system?
The anti-skid system provides driving safety on bad roads, prevents the car from getting stuck on slippery or loose surfaces (in snow or soft ground). The Electronic Stability Program (ESP) is very popular now. Antiwheelspin gear is only a part of them. But such modern equipment is expensive, so many drivers can not afford a car equipped with it.
The Antiwheelbuckle not only ensures the safety of driving on roads, but also prolongs the life of the automatic transmission. Prolonged towing can put it out of order.
Disadvantages of the antiwheelspin system
The traction control system has many advantages, but it also has disadvantages. The main one is the deterioration of the dynamics. When the driver will try to start on a snowy road, the wheels will be braked, depriving the car of dynamics. Inadequate operation of the system is also possible. Sometimes overcoming even small obstacles may cause difficulties.
How to disable the anti-skid system
If necessary, the system can be easily disabled. This may be required in case of its breakdown or when the driver wants to feel the drive. The corresponding button is located on the dashboard or next to the gearshift. When disabled, a light on the dashboard lights up, signaling the danger of skidding.