Torque Sensor Knowledge Sharing

In life, I think everyone has encountered such problems. Torque sensor failure. Once the torque sensor fails, it will cause a lot of trouble. If it is serious, a traffic accident may occur! So everyone should be careful. It is found that the torque sensor is broken and needs to be repaired in time.

Torque sensors are typically used to measure the magnitude and direction of the driver's torque on the steering wheel and convert it into an electrical signal. The power is converted to the ECU, which receives this signal and the vehicle speed signal, and determines the direction and magnitude of the auxiliary power. Therefore, the rotational torque is controlled to be smaller when driving at low speed, and to be moderately larger when driving at high speed. This is one of the important components of the electronically controlled power rotation system.

Torque sensors can currently be divided into two types: contact type and non-contact type. Non-contact torque sensors are also called sliding variable electromagnetic torque sensors. The contact torque sensor installs a torsion bar between the steering shaft and the steering pinion. When the steering system is working, it uses a slip ring and a potentiometer to measure the deformation of the torsion bar and convert it into a voltage signal. Non-contact torque sensors have two pairs of pole rings. If relative rotation occurs between the input shaft and the output shaft, the air spacing between the polar rings will change, the electromagnetic induction coefficient will change, and the wire will generate an induced voltage. Convert voltage signal to torque signal. The advantages of non-contact torque sensors are small size and high accuracy.

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 models integrate the steering motor, torque sensor and steering wheel to form a steering column assembly, which makes the steering control more reliable.

Generally speaking, when the torque sensor is damaged or performs poorly, the following types of failures may occur in the steering system:

1. Difficulty in steering; left and right rotational torques are different or uneven.

2. When driving, the turning torque does not change with the vehicle speed, or the steering wheel cannot rotate normally.

3. The P/S warning light on the instrument turns on.

There are many reasons why the process signal of the torque sensor is unstable. Generally speaking, there are three aspects:

First of all, the torque sensor is not installed properly and the axes are not parallel, which will cause the signal output to be unstable. The sensor is easily damaged when it is in this state for a long time.

Secondly, the electrical voltage is unstable. Torque sensors are generally powered by a dual-voltage power supply of plus and minus 15V, which is also powered by 24V or other voltages. Unstable power supply voltage will lead to unstable output signals.

The third reason is also easy to ignore. This is interference from other machines next to the torque sensor. For example, if there is a frequency converter next to the torque sensor, the output signal may become unstable. The solution is to add a 1:1 isolation switch before the sensor's power supply.