What is the Principle of Passive Tire Pressure Monitoring?
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Passive tire pressure monitoring is an indirect tire pressure monitoring system. Its working principle is that when the air pressure of a tire decreases, the weight of the vehicle will cause the rolling radius of that wheel to become smaller, resulting in its rotation speed being faster than other wheels. By comparing the differences in rotation speed between tires, the purpose of monitoring tire pressure is achieved. There are three commonly used tire pressure monitoring methods: Direct tire pressure monitoring: Direct tire pressure monitoring devices use pressure sensors installed in each tire to directly measure the tire pressure. The pressure information is transmitted wirelessly from inside the tire to a central receiver module, which then displays the tire pressure data for each tire. The system automatically alerts when the tire pressure is too low or there is a leak. Indirect tire pressure monitoring: When the air pressure of a tire decreases, the weight of the vehicle will cause the rolling radius of that wheel to become smaller, resulting in its rotation speed being faster than other wheels. By comparing the differences in rotation speed between tires, the purpose of monitoring tire pressure is achieved. Indirect tire pressure warning systems actually rely on calculating the rolling radius of the tires to monitor air pressure. Introduction to Tire Pressure Monitoring System (TPMS): It combines the advantages of the two systems mentioned above. Direct sensors are installed in two diagonally opposite tires, and a four-wheel indirect system is also equipped. Compared to using only a direct system, this hybrid system can reduce costs and overcome the defect of indirect systems being unable to detect when multiple tires simultaneously have low pressure. However, it still cannot provide real-time data of the actual pressure in all four tires like a direct system.
