How good are pressure sensors?
These systems warn the driver when they detect a drop in tyre pressure. They may soon be mandatory on new vehicles sold in Europe.
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Driving with correctly inflated tyres is a basic rule, both of safety (stability, road holding, braking distances) and economy and environment (fuel consumption, tyre life). However, too few drivers bother to check their tyre pressure every month, as recommended.
For this reason, equipment suppliers developed pressure sensors (also known as TPMS: Tyre Pressure Monitoring System), that warn the driver in the event of a loss of pressure.
There are two categories of product on the market:
- Indirect systems (or passive systems). They use data collected by the ABS sensors to detect an unusually high rotation speed (an underinflated tyre is small in diameter and thus rotates more quickly). Economical but not very accurate.
- Direct systems (or active systems). They use sensors fitted to the valves or to the wheels. These sensors measure the pressure of each tyre and transmit the data by radio waves to a receiver.
How does it work?
The air pressure acts on a piezo-crystal membrane through a small hole. The pressure difference is then converted into a voltage difference. This measurement is sent to the car by a radio signal radio at a frequency of 433 Mhz (in Europe). The sensor operates with a small battery.
When you change a tyre, remember to tell your specialist about the presence of the sensors. It will prevent them being damaged or lost!