In a modern, well-equipped (and often expensive) car, electronic systems like stability and traction control, along with anti-lock braking, will kick in to help the driver avoid an accident. Now a new tyre could detect when a car is about to skid and switch on safety systems in time to prevent it. It could also improve the fuel-efficiency of cars to which it is fitted.
Pirelli, an Italian tyremaker, has developed what it calls the Cyber Tyre. In it is embedded a small device containing miniature sensors that can measure the acceleration and deceleration along three axes at the point of contact with the road. A tiny transmitter in the device sends those readings to a unit that is linked to the braking and other control systems.
Developing the tyre has taken nine years so far. The main difficulty has been to make the sensor very small and light but capable of operating in harsh conditions. Accelerometers are already used in cars: for activating airbags, when they pick up the large decelerations that occur in crashes, for example, or for stability control, when they measure the acceleration during cornering and provide input to traction systems. These accelerometers are relatively large. In the Cyber Tyre they are just a few millimetres across.
The accelerometers in the Cyber Tyre have two tiny structures, the distance between which changes during acceleration and alters the electrical capacitance of the device, which is measured and converted into voltage. Powered by energy scavengers that exploit the vibration of the tyre, the device encapsulating the accelerometers and the transmitter is about 2.5 centimetres in diameter and about the thickness of a coin.
The device is embedded in the tyre within the natural and synthetic rubber, carbon black and silica that are a tyre’s main components. It must work in extreme conditions. Tyre temperatures can reach as high as 80°C and as low as -40°C; the acceleration forces can reach several thousand times gravity. The device must also last longer than the tyre itself.
Constantly monitoring the forces that tyres are subjected to as they grip the road could help reduce fuel consumption by optimising braking and suspension. Moreover, it could promote the greater use of tyres with a low rolling-resistance, which are often fitted to hybrid vehicles. These save fuel by reducing the resistance between the tyre and the road but, to do so, they have a reduced grip, especially in the wet. If fitted with sensors, such tyres could be more closely monitored and controlled in slippery conditions.
So far, the results are impressive. A prototype Cyber Tyre has been running on a test vehicle for the past nine months. Pirelli believes its new tyre could be fitted to cars in 2012 or 2013, but this will depend on when carmakers incorporate the necessary monitoring and control systems into their vehicles.
Earlier this year Brembo, a brake manufacturer, and Magneti Marelli, which makes electronics for cars, joined forces to help develop systems for the Cyber Tyre. As with most innovations, these are expected to be available first in upmarket models before filtering down to cheaper cars. But if the introduction in 1973 of Pirelli’s steel-belted Cinturato radial tyre is any guide, devices that make cars safer will be adopted rapidly. (Tire Review/Akron)
