ABS sensor, anti-lock brake system.
Main species
1, linear wheel speed sensor
Linear wheel speed sensor is mainly composed of permanent magnet, pole axis, induction coil and tooth ring. When the gear ring rotates, the tip of the gear and the backlash alternate opposite polar axis. During the rotation of the gear ring, the magnetic flux inside the induction coil changes alternately to generate the induction electromotive force, and this signal is input to the electronic control unit of ABS through the cable at the end of the induction coil. When the speed of the gear ring changes, the frequency of the induced electromotive force also changes.
2, ring wheel speed sensor
Annular wheel speed sensor is mainly composed of permanent magnet, induction coil and tooth ring. The permanent magnet is composed of several pairs of magnetic poles. During the rotation of the gear ring, the magnetic flux inside the induction coil changes alternately to generate the induction electromotive force. This signal is input to the electronic control unit of ABS through the cable at the end of the induction coil. When the speed of the gear ring changes, the frequency of the induced electromotive force also changes.
3, Hall type wheel speed sensor
When the gear is located in the position shown in (a), the magnetic field lines passing through the Hall element are dispersed and the magnetic field is relatively weak; When the gear is located in the position shown in (b), the magnetic field lines passing through the Hall element are concentrated and the magnetic field is relatively strong. When the gear rotates, the density of the magnetic line of force passing through the Hall element changes, which causes the Hall voltage to change, and the Hall element will output a millivolt (mV) level of quasi-sine wave voltage. This signal also needs to be converted by the electronic circuit into a standard pulse voltage.
Install
(1) Stamping gear ring
The tooth ring and the inner ring or mandrel of the hub unit adopt interference fit. In the assembling process of the hub unit, the tooth ring and the inner ring or mandrel are combined together by an oil press.
(2) Install the sensor
The fit between the sensor and the outer ring of the hub unit is interference fit and nut lock. The linear wheel speed sensor is mainly nut lock form, and the ring wheel speed sensor adopts interference fit.
The distance between the inner surface of the permanent magnet and the tooth surface of the ring: 0.5 ± 0.15 mm (mainly through the control of the outer diameter of the ring, the inner diameter of the sensor and the concentricity)
(3) The test voltage uses the self-made professional output voltage and waveform at a certain speed, and the linear sensor should also test whether the short circuit;
Speed: 900rpm
Voltage requirement: 5.3 ~ 7.9 V
Waveform requirements: stable sine wave
Voltage detection
Output voltage detection
Inspection items:
1, output voltage: 650 ~ 850mv(1 20rpm)
2, output waveform: stable sine wave
Second, abs sensor low temperature durability test
Keep the sensor at 40 ° C for 24 hours to test whether the abs sensor can still meet the electrical and sealing performance requirements of normal use
Is the abs sensor front and back
The ABS sensor is left and right. ABS sensor is an important part of automobile anti-lock braking system, which is used to detect wheel speed and send it to ABS control unit. In this way, the control unit can adjust the size of the braking force according to the speed and the speed of the wheel to prevent the wheel from being locked. ABS sensors are typically installed in locations near the wheels, which can vary by model and brand. For models such as the Volkswagen Lavida, the ABS sensor is installed separately according to each wheel, a total of four front and rear left and right. This means that the ABS sensor has left and right points on the front wheel of the vehicle, so it is necessary to distinguish between left and right. For example, if the left rear wheel sensor is damaged when you replace the ABS sensor, you need to replace it accordingly.
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