What is the principle of built-in tire pressure monitoring in cars?
3 Answers
Tire pressure monitoring is the real-time automatic monitoring of tire pressure during vehicle operation, with alerts for tire leaks and low pressure to ensure driving safety. There are three commonly used methods of tire pressure monitoring: Direct tire pressure monitoring: Direct tire pressure monitoring devices use pressure sensors installed in each tire to directly measure tire pressure. The pressure information is transmitted wirelessly from inside the tire to a central receiver module, which then displays the pressure data for each tire. The system automatically alerts when tire pressure is too low or there is a leak. Indirect tire pressure monitoring: When the pressure in a tire decreases, the vehicle's weight causes that wheel's rolling radius to become smaller, resulting in a faster rotation speed compared to other wheels. By comparing the differences in rotation speeds between tires, the system monitors tire pressure. Indirect tire pressure monitoring systems essentially rely on calculating the rolling radius of tires to monitor pressure. Tire intelligent monitoring system: This system combines the advantages of the two aforementioned systems. It is equipped with direct sensors in two diagonally opposite tires and a 4-wheel indirect system. Compared to a full direct system, this hybrid system can reduce costs and overcome the indirect system's inability to detect simultaneous low pressure in multiple tires. However, it still cannot provide real-time data on the actual pressure in all four tires like a direct system.
I've always been fascinated by various car sensors, and the principle of tire pressure monitoring is particularly interesting. It involves installing a small chip near the valve stem of each tire to measure internal pressure in real time. This chip transmits the pressure data via wireless signals to a receiver in the car, much like a walkie-talkie communicating information. Last time I had a slow tire leak, it was the small icon on the dashboard that alerted me. This direct monitoring method is the most accurate, but the sensors must withstand high temperatures and vibrations, with their batteries typically lasting five to seven years. If the battery dies, the entire module needs replacement. You also have to be careful not to damage it during car washes or tire repairs, as the maintenance cost is quite high. However, it's absolutely worth it for safety.
After driving for so many years, I've gained quite some experience with tire pressure monitoring. Most vehicles use indirect systems, which don't directly measure tire pressure but rely on the ABS wheel speed sensors to work. When a tire's pressure drops, its diameter decreases slightly, causing it to rotate a bit faster than the other wheels. The system detects this minor speed difference to trigger an alert. Last time when I came out of the supermarket and saw the dashboard warning light, I checked and found a nail in the right rear tire. This type of system is cost-effective as it shares the wheel speed sensors, but it can sometimes give false alarms, like when switching from winter tires back to regular ones. Every time the system alerts me, I feel particularly reassured, especially when driving on highways.
