How are Hall Effect Switches Used to Measure Car Speed?

唯小样

How are Hall Effect Switches Used to Measure Car Speed? [Copy link]

　　Hall-effect vehicle speed sensor: Hall effect sensors (switches) are very special in automotive applications, mainly due to spatial conflicts around the transmission. Hall effect sensors are solid sensors. They are mainly used for crankshaft angle and camshaft position, used to switch ignition and fuel injection circuit triggering, and are also used in other computer circuits that need to control the position and speed of rotating parts.

　　The Hall effect sensor or switch consists of an almost completely closed magnetic circuit containing a permanent magnet and a magnetic pole portion. A soft magnet vane rotor passes through the air gap between the magnet and the magnetic pole. The window on the vane rotor allows the magnetic field to pass through and reach the Hall effect sensor unaffected, while the part without the window interrupts the magnetic field. Therefore, the role of the vane rotor window is to switch the magnetic field, so that the Hall effect is turned on or off like a switch. This is why some automobile manufacturers call Hall effect sensors and other similar electronic devices Hall switches. The component is actually a switching device, and its key functional component is the Hall effect sensor.

　　The Hall-type speed sensor on the car has a signal disk embedded in the wheel bearing on the vehicle side, which rotates with the wheel. The Hall-type speed sensor is installed on the signal disk on the outside of the bearing. The vehicle speed is calculated by the braking system control unit based on the speed of the four wheels. Some tire pressure monitoring is obtained by detecting changes in wheel speed while driving.

　　Some Hall wheel speed sensors have multiple Hall elements integrated inside, which are more sensitive and can monitor the speed and direction of rotation at the same time. The crankshaft position sensor also uses this method to detect the crankshaft position so that the reversal of the crankshaft when the engine is turned off can be monitored, and the restart time is faster (mostly during start-stop). In the early days, including now, the window glass lifting uses Hall sensors to detect the number of motor rotations and current to identify the position of the glass window and prevent pinching. Now, due to the progress of the control module, it can detect the position and prevent pinching by only monitoring the current.

　　The electronic parking brake motor also has a Hall-type speed sensor integrated inside it, and there is also one inside the gearbox. Due to the advantages of the Hall-type, the electromagnetic type is becoming less and less used.

toothache

Hall sensors are really useful. Contactless, convenient and accurate