What is an automotive crankshaft sensor
The crankshaft position sensor is a core sensor in automotive engines used to detect the position, speed of the crankshaft and the top dead center signal of the piston. Its signal directly controls the ignition timing and fuel injection timing, ensuring the efficient and stable operation of the engine.
Core function
Detection of crankshaft position: By the relative movement of the signal disk teeth and the magnetic head, a pulse signal is generated to determine the piston position (70° before the top dead center).
Monitor engine speed: Calculate the circulating fuel supply volume and assist the ECU in adjusting the fuel injection volume and ignition advance Angle.
Cylinder sequence identification and misfire monitoring: Cylinder sequence identification is achieved through the phase difference of pulse signals (such as 90°), and misfire phenomena are detected.
Common types
Youdaoplaceholder0 magnetic pulse type : It generates an alternating electromotive force by changing the magnetic field, such as the systems of Nissan and Toyota.
Youdaoplaceholder0 Hall effect formula : By detecting magnetic field changes through hall elements, a digital signal is output.
Youdaoplaceholder0 photoelectric type : It generates signals by relying on the occlusion of the optical path and is less applied.
Installation location
Diesel engine: It is mostly installed on the flywheel housing or supply pump.
Gasoline engine: Commonly found inside the distributor (such as in Toyota's TCCS system) or near the flywheel.
Fault manifestation
The engine is difficult to start, shaking or stalling.
Fuel economy has declined and emissions have exceeded standards.
The core function of the automotive crankshaft sensor (also known as the crankshaft position sensor or engine speed sensor) is to detect the crankshaft position, engine speed and piston top dead center signals, and transmit these data to the engine control unit (ECU) to precisely control the ignition timing, fuel injection timing and fuel injection sequence, ensuring the efficient and stable operation of the engine.
Core function
The crankshaft sensor is a core component of the engine's electronic control system. Its main functions include:
Youdaoplaceholder0 Detect crankshaft position and rotation Angle : Monitor the crankshaft rotation Angle in real time, determine the specific position of the piston in the cylinder, and provide reference signals for ignition and fuel injection timing to the ECU.
Youdaoplaceholder0 measures engine speed : As a speed sensor, it inputs the speed signal into the ECU to dynamically adjust the fuel injection volume and ignition advance Angle, avoiding insufficient fuel injection or ignition delay.
Youdaoplaceholder0 Identify the position of the piston top dead center : Locate the moment when the piston reaches the top dead center (especially the top dead center of the first cylinder), assist the ECU in achieving sequential fuel injection and cylinder sequence discrimination, and ensure the correct working sequence of each cylinder.
Youdaoplaceholder0 supports auxiliary control : participates in subsystems such as idle speed control and fuel evaporation control, and determines engine misfire by monitoring the fluctuation of crankshaft Angle, optimizing combustion efficiency and reducing emissions.
Working principle and types
Crankshaft sensors achieve their functions through physical signal conversion. Common types include:
Youdaoplaceholder0 magnetic pulse type : It generates a sinusoidal wave signal by triggering a magnetic field change through a signal disk. It has a low cost but is vulnerable to interference.
Youdaoplaceholder0 hall type : It outputs square wave signals by means of the trigger blade, requires an external power supply, and the output signal is stable and not affected by the rotational speed.
Youdaoplaceholder0 photoelectric type : Pulse voltage is generated by transmitting through the light hole, with high precision but easily affected by oil stains.
All types need to work in conjunction with the camshaft position sensor to ensure complementary signals.
Fault impact
Sensor abnormalities can lead to:
When the engine fault light comes on, it indicates difficulty in starting, insufficient power or inability to start.
Incorrect ignition and fuel injection timing reduce fuel economy and increase emissions.
Common causes of faults include aging of the circuit, dirty sensors or improper installation clearance (the standard clearance is 0.2-0.4mm).
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