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Reasons for ABS solenoid valve noise
When a solenoid valve makes a noise, most people think it's a problem with the ECU, but after replacing the ECU, the problem still exists. They also think it's a problem with the solenoid valve, but after replacing the solenoid valve, it still makes a noise. Actually, it's not a problem with the ECU and solenoid valve, but a problem with the sensor signal. The installation of the sensor and gear ring directly affects the output signal of the sensor. The installation of the gear ring must ensure that its rotating surface is perpendicular to the rotating shaft (alignment). Otherwise, if the gear ring rotates once, the gap D between the gear ring and the sensor will periodically change from large to small, and the output signal of the sensor will also periodically change from large to small. The typical sensor output waveform is shown in the following figure:
Due to the variation of gap D, the maximum Vmax is output at the minimum gap (Dmin) and the minimum Vmin is output at the maximum gap (Dmax). The greater the deviation between the rotation surface of the gear ring and the rotation axis, the greater the end jump (Dmax Dmin) of the gear ring, and the greater the difference between Vmax and Vmin. Installation requires an end jump of<0.2mm, with Vmax/Vmin<2. In addition, the ECU's requirement for the wheel speed signal output from the sensor is Vmin>0.2V.
If the installed gear ring is not aligned, coupled with the influence of wheel bearing clearance, the end skip is large, which will cause Vmin to be less than 0.2V. At this time, the ECU cannot recognize the wheel speed signal output by the sensor, and it will consider the wheel to be locked, thus driving the solenoid valve to relieve pressure, and we will hear the solenoid valve sound.
If there is a solenoid valve noise in a new offline vehicle, it is usually due to incorrect installation of the gear ring, and the end jump should be checked for excessive size.
If the electromagnetic valve sounds while using the vehicle, it is usually due to excessive sensor clearance. Push the sensor inward. If necessary, replace the clamping sleeve and increase the clamping force to prevent it from exiting due to vibration.
In addition, if the electromagnetic valve sounds on bumpy roads, in addition to considering the sensor clearance, it is also necessary to consider whether the wheel bearing clearance is too large. （2020.07.13）
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