Views: 92 Author: Site Editor Publish Time: 2020-02-25 Origin: Site
TPMS is the abbreviation of ‘tire pressure monitoring system’, which is mainly used to automatically monitor tire pressure during driving to ensure driving safety.
According to the statistics of relevant data, when the tire pressure reaches a reasonable value, it can not only improve the driving safety, but also save fuel consumption. There are two kinds of tire pressure monitoring system, direct system and indirect system. The direct tire pressure monitoring system can be divided into two types, active and passive.
Tire pressure sensor consists of four parts, pressure / temperature sensor, measurement and control electronic device, lithium-ion battery and transmitting antenna. Among them, the pressure / temperature sensor has the functions of pressure, temperature, acceleration, voltage detection and post signal processing. The measurement and control electronic device includes 4-8-bit MCU, RF transmitter chip.
When the tire pressure sensor works, it will send information to LIN bus, including tire pressure, tire temperature, special identification number, integrated battery status and the status, synchronization and control information needed to ensure data transmission.
The working principle of strain sensor is mainly based on the resistance strain effect. That is, when the conductor is mechanically deformed under the external action, its resistance value changes accordingly. The strain is calculated by the relationship between the change of resistance value and output electric signal. Then the pressure is calculated.
There are two key technologies of tire pressure sensor
In order to ensure that a lithium battery can make TPMS transmitter work for 3-5 years, or even longer, the power saving of the system is particularly important. A good way is to make the system sleep most of the time, so as to save power and extend battery life. However, this makes a problem particularly important. How to wake up TPMS system quickly? In general, when the car is activated and driving at high speed, the TPMS system is awakened by software setting timing detection and adding inertial sensor in the sensor module. The former is to install a wake-up chip on the transmitter module and send a wake-up signal through the receiver. The latter is to automatically enter the system self-test and automatically adjust the detection cycle according to the sensitivity of moving objects.
TPMS involves wireless transmission and reception of signals. The reliability of system signals, especially the stability of high-speed driving signal transmission, should not be ignored in the design. Due to the poor working condition of the car at high speed and the large number of electronic products in the car, the signal may drift or off and on. In addition, when using electronic products such as mobile phones, the signals will interfere with each other, which will affect the signal stability. Therefore, how to do a good job of system shielding and anti-interference is particularly important. The key to solve these problems lies in the chip selection of RF transmitter and RF receiver.
In recent years, automotive sensors are the fastest growing and most used sensor categories. The development of domestic automobile industry stimulates the development of automobile pressure sensor. Advanced manufacturing technology and process technology make the performance of sensor more and more high. Thus tire pressure monitoring system becomes more and more accurate.
