Direct-type of TPMS system installation has two divided types;
one type is connect the sensor and valve, this is the mainstream method. As shown in figure1:
Advantages: compact design, high integration, high monitoring precision, high Adopting rate, and perfect after-sales service and replacement parts.
The other one method is fix the sensor on the wheel hub, and this method is rarely used. As shown in figure2:
Disadvantages: large size, hard to install, easy to loose, affect the dynamic balance of the tire, the adoption rate is low, and the after-sales service can't be guaranteed
Indirect systems employ wheel speed sensors on a vehicle's anti-lock brake (ABS) system to track each tire's rotation. The premise is that under-inflated tires have a smaller radius, resulting in a higher rotational speed compared with a fully inflated tire. The sensor is supposed to detect the faster rotation, and the system alerts the driver. In practice, this change in radius is small, making indirect measurement less reliable than direct pressure measurement. Belong to the passive alarm.
Disadvantages
1,It’s unable to display the tire pressure number and can’t make sure the fault tire.
2,the System calibration is complex
3,when the speed is above 100km/h,the monitoring will be failured.
4,If two wheels on the same axle are losing pressure at the same time, the divice can't to send out the alarm message.
5,When the vehicles is stop driving，the device can't monitor tire pressure.
6,the react period is too long, and the deivice can’t alarm in time.
The importance of TPMS
First, we have to know the dangers of abnormal tire pressure：.
1，Low tire pressure
1）Increase the tire rolling resistance, increase vehicle fuel consumption and pollutant emission
2）Reduce the vehicle's handling ability
3）In a high speed, tire may prone to high temperature, so it’s easy to cause tire blowout
2，High tire pressure
1）Reduce the friction of the tire， weaken the brake performance
2）Increase the abnormal wear of the suspension system
3）Reduce the comfortable of the vehicle
The benefits of the TPMS：
1,Safety
1)predict gas leak, prevent tire blowout.
2)keep the 4 wheel at standard values of tire pressure, keep the driving and brake stability.
Comfort:
1)optimizing handing of vehicle.
2)optimizing brake performance of vehicle.
3)stable tire pressure makes the chassis and suspension in the best state.
3, economical efficiency
1)reduce fuel consumption, lower transport costs, and reduce pollutant emission.
2)avoid abnormal tire wearing and extending working life of tires.
3)avoid chassis and suspension of vehicle abnormal wearing, and extending working life of vehicle.