The vehicle water temperature sensor is usually installed on the water jacket of the engine block or cylinder head and directly contacts the cooling water to measure the temperature of the engine cooling water. It has an internal semiconductor thermistor, which is characterized by the lower the temperature, the higher the resistance. We can know the current running state of the car through the temperature of the engine water temperature, and the electronic control unit measures the temperature of the engine cooling water according to this change, as the correction number of the fuel injection and ignition timing.
The principle of the vehicle water temperature sensor is to transmit the sensed water level signal to the controller by the water level sensor in the container. The computer in the controller compares the measured water level signal with the set signal to obtain the deviation, and then according to the nature of deviation, the “on” and “off” command is issued to the feed water electric valve to ensure the container reaches the set water level. After the water inflow procedure is completed, the temperature-controlled portion of the computer issues an “on” command to the electric valve that supplies the heat medium, so the system begins to heat the water in the container. When the temperature is set, the controller issues the command to close the valve, cut off the heat source, and the system enters the thermal insulation state. During the programming process, ensure that the system does not open the electric control valve that controls the heat source without reaching a safe water level, so as to avoid heat loss and accident.
Automotive water temperature sensors are usually divided into two types.
The first type of water temperature sensor has a simple function. The internal resistance of the sensor is changed to drive the change of water temperature meter by changing the resistance of the sensor, and the working temperature of the engine is told indirectly.
The second type of water temperature sensor has no structural change. The main difference is that the second type of function is to provide an analog signal of temperature change to the engine control unit. Its supply voltage is the 5V power supply provided by the control unit, and the return control unit’s signal is a linear change signal of 1.3V-3.8V. The main function is to tell the engine control unit what the temperature is now. Conversely, its signal is extremely important for the control unit because the engine has different working methods at different operating temperatures.
However, these two types water temperature sensors operate in different voltage conditions. The sensor for the water supply thermometer is 12V, and the engine control unit is 5V, so they are not interchangeable. In addition, their plugs have different shapes, the difference being that there is only one wire in the plug of the former, and the latter has two wires in the plug for the engine control unit.
NTC thermistor chip used as temperature measurement in previous automotive water temperature sensors generally use a wafer-shaped NTC thermistor chip. They are all calculated by diameter. Exsense Electronics Technology Co., Ltd. has independently developed a square-shaped NTC thermistor chip suitable for automotive water temperature sensors. The shape of the chip is square, which is more convenient to solder than the wafer.