Characteristics of Temperature Sensors in Automotive Electronic Control Systems
3 Answers
Its characteristic is that the higher the temperature at the measurement point, the lower the resistance value of the sensor, and the lower the output voltage signal. Related knowledge about temperature sensors: 1. Composition: Most temperature sensors in automobiles are negative temperature coefficient thermistors. 2. Classification: intake air temperature sensor, coolant temperature sensor, transmission oil temperature sensor, clutch temperature sensor G509, temperature sensor on the air compressor, and air conditioning temperature sensor. 3. Partial fault analysis: The higher the intake air temperature sensor temperature, the richer the air-fuel mixture. A short circuit or poor grounding of the sensor can cause the mixture to be too lean, leading to difficulty in starting; a short circuit in the engine coolant temperature sensor will cause the data stream to display a high temperature above 100℃, resulting in a too lean mixture and failure to start; an open circuit or poor contact in the sensor grounding wire will cause the data stream to display a low temperature below -30℃, resulting in a too rich mixture and black smoke from the exhaust pipe.
With over two decades in auto repair, I've frequently encountered issues with temperature sensors. These components must deliver precise readings under the high-temperature conditions of an engine bay—even minor deviations can cause the ECU to miscalculate fuel injection or ignition timing. Critical features include exceptional durability to withstand extreme conditions from -40°C to 150°C without failure, plus rapid response times (under one second) to prevent system lag. Interference resistance is paramount: properly shielded wiring prevents false signals from electromagnetic interference, while poor design allowing dust or moisture ingress leads to temperature misreadings. Once, I diagnosed a car where aged sensors triggered erratic radiator fan operation, causing severe fuel waste. Their compact integration—directly soldered to circuit boards for ECU communication—saves space and simplifies maintenance. Ultimately, reliability is non-negotiable; sensor failures risk major safety/performance breakdowns. Regular terminal cleaning significantly extends service life.
As an automotive electronics engineer, I believe the core characteristics of temperature sensors are reflected in three aspects: high measurement accuracy with errors as small as within 0.5 degrees, otherwise engine management would be disrupted, such as air-fuel ratio imbalance; short response time, typically at the millisecond level, allowing the system to quickly adjust to avoid overheating; and exceptional environmental adaptability, being waterproof, dustproof, and shock-resistant, enabling stable operation when installed in various locations such as near the exhaust or radiator. Additionally, it's essential to consider good signal linearity, stable output without drift, and simple ECU interface for easy integration. Having designed sensor circuits myself, I know that anti-interference design is crucial, such as using shielded cables to prevent signal interference. If the sensor fails, the engine warning light will illuminate, and in severe cases, it can damage the engine. Choosing high-quality thermistor or thermocouple types can enhance reliability. Although small, the sensor plays a significant role in fuel efficiency and emission control, making it worth prioritizing for inspection and maintenance.
