What is the function of automotive environmental sensors
Automotive sensors are input devices of the vehicle's computer system. They convert various working condition information during vehicle operation, such as vehicle speed, temperatures of various media, and engine operating conditions, into electrical signals and send them to the computer, so that the engine can be in the best working condition. There are many sensors used in vehicles. When diagnosing a fault in a sensor, one should not only consider the sensor itself but also the entire circuit where the fault occurred. Therefore, when locating faults, in addition to checking the sensors, it is also necessary to inspect the wiring harnesses, connectors, and the relevant circuits between the sensors and the electronic control unit.
The damage of the automotive ambient temperature sensor can lead to the following effects:
Abnormality of the air conditioning system
A damaged environmental temperature sensor will prevent the air conditioning system from accurately obtaining external temperature information. Insufficient cooling in hot weather and poor heating effect in cold weather will affect driving comfort.
Instrument display error
Sensor failure may cause incorrect readings of the external temperature displayed on the dashboard, affecting the driver's judgment of the environment.
Engine performance issues
Incorrect information can cause deviations in the fuel injection volume controlled by the engine ECU, resulting in problems such as difficult starting, unstable idle speed, and increased fuel consumption. Long-term use may damage the internal components of the engine.
Automatic function failure
The seat heating/ventilation and automatic wipers of some vehicles may not work properly due to the lack of accurate temperature signals.
Automotive environmental sensors mainly detect environmental parameters such as temperature and pressure through different principles. The following are the main types and working principles:
Thermistor type
By taking advantage of the characteristic that the resistance value of a thermistor varies with temperature, temperature is converted into an electrical signal. When the temperature rises, the resistance value decreases. When the temperature drops, the resistance value increases. After processing by the ECU, it controls the air conditioning, heating system, etc.
Metal expansion type
The measurement is achieved through the differences in the expansion coefficients of metallic materials at different temperatures. For instance, a bimetallic strip sensor is composed of two metal strips with different coefficients of expansion. When temperature changes cause them to bend and deform, they then output signals.
Liquid/gas deformation monitoring
The volume change of a liquid or gas when the temperature changes is utilized, and the linear expansion or positional change through structural transformation (such as metal tubes or liquid containers) is converted into an electrical signal.
Capacitive
Perceiving physical quantities through changes in capacitance values (such as proximity detection) is often used in scenarios like keyless entry systems. For instance, the AS8580 sensor features a sensitivity of 1.9fF/LSB, enabling precise detection of touch or proximity actions.
After these sensors convert environmental parameters into electrical signals, the ECU processes the data to achieve functions such as air conditioning adjustment and engine control.
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