Sharing of knowledge about torque sensors

2025-03-01

In life, I think everyone has encountered such a problem, torque sensor failure. Once the torque sensor fails, it will bring great trouble, and in serious cases, a traffic accident will occur! So everyone should be careful. If you find that this torque sensor is broken, you should repair it in time. Torque sensors are usually used to measure the size and direction of the torque applied by the driver on the steering wheel and convert it into an electrical signal. The power is converted to the ECU, which receives the signal and the vehicle speed signal and determines the direction and size of the auxiliary power, so that the torque is small when driving at low speed and the torque is moderately increased when driving at high speed. This is one of the important components of the electronically controlled power transmission system.

The torque sensor can currently be divided into two types: contact and non-contact. The non-contact torque sensor is also called a sliding variable torque sensor. The contact torque sensor installs a lever between the steering pinion and the steering pinion, and uses a slip ring and a potentiometer when the steering system is working. The non-contact torque sensor measures the deformation of the torsion bar and converts it into a voltage signal. The non-contact torque sensor has two pairs of pole rings. If the input shaft and the output shaft rotate relative to each other, the air gap between the pole rings will change, the electromagnetic induction coefficient will change, and the coil will generate an induced voltage. Convert the voltage into a torque signal. The advantages of non-contact torque sensors are small size and high precision.

In addition, some sensors can also measure the size and direction of the steering wheel angle. The torque measurement system is complex and costly. For example, Toyota integrates the steering motor, torque sensor and steering column assembly together to make the steering control more reliable.

Generally speaking, when the torque sensor is damaged or has poor performance, the steering system may have the following types of faults:

1. Difficult steering; different left and right rotation torques or uneven rotation torques.

2. When driving, the rotation force does not change with the speed of the vehicle, and the steering wheel cannot rotate normally.

3. The P/S warning light on the instrument is turned on.

There are many reasons for the unstable signal during the use of the torque sensor. Generally speaking, there are three aspects:

First, the torque sensor is not installed properly, and the shaft is not parallel, which will lead to unstable signal output. The sensor is easily damaged if it works in this state for a long time

Second, the power voltage is unstable. The torque sensor is generally powered by a dual voltage power supply of positive and negative 15V, and is also powered by 24V or other voltages. Unstable power supply voltage will lead to unstable output signal

The third reason is also easy to ignore. This is the interference of other machines next to the torque sensor. For example, if there is a frequency converter next to the torque sensor, the output signal is prone to instability. The solution is to add a 1:1 isolation switch in front of the power supply of the sensor.

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