There are many types of sensors used in automobiles. When diagnosing a sensor malfunction, one should not only consider the sensor itself, but also the entire circuit that is malfunctioning. Therefore, in troubleshooting, in addition to checking the sensor, one should also check the wiring harness, connectors, and the related circuits between the sensor and the electronic control unit.
Automotive sensors are input devices for automotive computer systems. They convert various operating conditions of the vehicle, such as vehicle speed, temperature of various media, and engine operating conditions, into electrical signals and transmit them to the computer so that the engine can be in the best working condition.
There are many types of sensors used in automobiles. When diagnosing a sensor malfunction, one should not only consider the sensor itself, but also the entire circuit that is malfunctioning. Therefore, in troubleshooting, in addition to checking the sensor, one should also check the wiring harness, connectors, and the related circuits between the sensor and the electronic control unit.
One of the defining characteristics of automotive technology development is the increasing adoption of electronic control in various components. Based on their function, sensors can be categorized into those that measure temperature, pressure, flow rate, position, gas concentration, speed, light intensity, humidity, distance, and so on. Each sensor has its specific function, and if one fails, the corresponding device will malfunction or even stop working altogether. Therefore, sensors play a crucial role in automobiles.
Automotive sensors, once used solely in engines, have expanded to include the chassis, body, and lighting and electrical systems. These systems utilize over 100 different types of sensors. Among these diverse sensors, common ones include:
Intake pressure sensor: It reflects the change in absolute pressure in the intake manifold and provides a reference signal to the ECU (Engine Control Unit) for calculating the duration of fuel injection.
Air flow meter: measures the amount of air drawn into the engine and provides it to the ECU as a reference signal for fuel injection timing;
Throttle position sensor: measures the angle of throttle opening and provides the ECU with a reference signal for fuel cut-off, fuel/air ratio control, and ignition timing correction;
Crankshaft position sensor: detects crankshaft and engine speeds and provides them to the ECU as a reference signal for determining ignition timing and firing order;
Oxygen sensor: detects the oxygen concentration in the exhaust and provides it to the ECU as a reference signal to control the fuel/air ratio near the optimal (theoretical) value;
Intake air temperature sensor: detects intake air temperature and provides it to the ECU as a basis for calculating air density;
Coolant temperature sensor: detects the temperature of the coolant and provides engine temperature information to the ECU;
Knock sensor: Installed on the cylinder block to detect engine knocking and provide signals to the ECU to adjust the ignition timing.
These sensors are mainly used in transmissions, steering systems, suspensions, and ABS.
Transmission: Includes vehicle speed sensor, temperature sensor, shaft speed sensor, pressure sensor, etc. Steering gear includes angle sensor, torque sensor, hydraulic sensor;
Suspension: Includes vehicle speed sensor, acceleration sensor, vehicle height sensor, roll angle sensor, and steering angle sensor;
Test characteristics
The diversity and rapid changes of the tested objects
Commonly used automotive sensors include wheel speed sensors, crankshaft/camshaft position sensors, temperature sensors, pressure sensors, and knock sensors. With the ever-increasing number of car models, sensors with the same function can vary greatly in appearance. Furthermore, increasingly stringent requirements for measurement specifications and production environments make traditional, single-function testing benches unable to handle the production of such a diverse range of sensors.
Test Approximation
In actual production, the testing requirements for different sensors have certain similarities. This is because, in terms of testing principles, automotive sensors are mainly divided into active/passive types, temperature sensors, pressure sensors, etc. In other words, for different sensors, as long as the testing principle is the same, it means that their testing instruments and equipment are also the same.
Test equipment
Automotive sensor production lines require economical, efficient, automated, and flexible testing equipment, characterized by high automation, high efficiency, high capacity, and high reliability. Sensor manufacturers hope that after an initial investment, the testing equipment itself can be continuously expanded to effectively support the latest products and higher performance requirements, thereby ensuring the effectiveness of the capital investment.
Other requirements
To ensure production quality, equipment needs to possess certain production process statistics capabilities, which helps reduce quality degradation caused by human factors. Integration and intelligence are the development trends of automotive sensors. If only final inspection is performed, problems may be discovered too late, so testing is often conducted interactively with the production process. This requires, on the one hand, that the testing equipment can be well integrated with other equipment on the production line, and on the other hand, that information and data sharing between equipment can be achieved.
