Crankshaft Position Sensor: Vital Component for Ignition in Cylinder

1. Magnetoelectric Crankshaft Position Sensor

1.1 Structure & Working Principle

Magnetoelectric sensors usually have three output lines: the signal output line, the lap line and the shield line. When the number of sensor turns is determined, the frequency and amplitude of the induced voltage are proportional to the target wheel speed.

There is no flux change in the middle of the tip or notch, and the output voltage is 0. The ECU's zero signal conversion domain value usually contains a specific over-zero hysteresis value to prevent misconversion caused by over-width of the tip or notch, vibration or vehicle noise.

1.2 Pros & Cons

There are some advantages. It has a simple, durable structure, high-temperature resistance, low assembly requirements, and a rotation-insensitive installation. However, there are some disadvantages. The signal is susceptible to interference, the electronic control unit needs to equip with the relevant signal processing circuit, the accuracy is low, and it does not apply to the engine with VVT.

2. Hall Crankshaft Position Sensor

2.1 Structure & Working Principle

The Hall sensor usually has three output lines: the power line, the signal output line and the override line. When the sensor design is completed, the magnitude of the Hall voltage depends on the magnitude of the magnetic field strength, and only the frequency is proportional to the target wheel speed.

The crankshaft position sensor is usually a dual Hall sensor, which integrates two Hall chips. The signal teeth need a front and a back through the double Hall chip. The two Hall signals get differential operation, and then the domain value conversion. Then, the output square wave signal is sent to the ECU. As a result, the dual Hall sensor has no zero-speed function. That is, to generate the signal, the signal wheel must have a certain speed.

2.2 Pros & Cons

There are some advantages. The output is a digital signal with high accuracy. There are some disadvantages: high assembly requirements, rotation-sensitive mounting and integration with electrical components.

3. Magnetoresistive Crankshaft Position Sensor

The advantages are larger mounting clearance allowed, better temperature stability, and highest accuracy. The disadvantages are higher assembly requirements, rotation-sensitive mounting, prone to saturation, high power consumption, and higher cost.

4. Symptoms & Analysis

A vehicle has been running for 16,000 km. It intermittently has a starting problem, or it accelerates weakly after starting. The problem is worse when the car is warmed up. The fault light comes on, and the crankshaft position sensor has no signal. The corresponding trouble code can be read out.

Check if the sensor works normally. The faulty parts are functionally tested according to the return part analysis process. The basic parameters such as high and low voltage, phase accuracy, rising and falling edge delay of the sensor output meet the technical requirements and can pass several necessary sensor tests.

The assembly dimensions of the sensors are normal, and the sensor height and center distance can meet the design requirements. The basic parameters such as the outer diameter of the signal wheel, the length of the cam tooth, the height of the cam tooth, the length of the tooth groove and the thickness of the signal wheel are measured. They all meet the design requirements.

We simulate the actual working condition. The vehicle is started continuously. The crankshaft position sensor has 780 ms signal loss at the starting moment. During signal loss, the vehicle cannot be started normally. It reports no sensor signal issues.

Now it can be determined that the sensor is more prone to failure under high temperature and vibration. To identify the root cause of the part failure better, all tests in the test chamber were conducted with high temperature and vibration as the basic conditions. After the actual vibration caused by the hammer striking at a high temperature, the sensor failure was captured to reappear.

The internal magnet of the sensor is not fixed, and the thermal expansion coefficient of each part is not consistent at high temperature, which causes the magnet to move slightly. The sensor detects an abnormal high frequency signal, and this signal makes the sensor enter the 780 ms self-resetting state. The sensor in the self-resetting state can not output a signal within the system synchronization time. It causes the ECU to report an error. You will have to get a strange automotive idling. 

5. Reasons for Choosing Delcoribo Crankshaft Position Sensors

The crankshaft position sensor sends crucial information to the ECU, which helps to improve engine operation. This is a heavy duty, and it’s terrible to have too many issues. Delcoribo is committed to top-quality crankshaft position sensors. Our products gain good reputation of compact design. Small components can be competent in vital tasks.

We know the importance that sensors keep high accuracy. Valves and pistons change positions all the time. The ECU requires precise data to control fuel injection and ignition timing. Delcoribo sensors ensure excellent performance and low noises. Exceptional durability leads to long service life.

The crankshaft position sensor is the core component for emissions reduction. People want powerful parts to improve fuel economy and driving experience. We produce trustworthy sensors for customers worldwide.