Electronic Shift Lever Sensor Magnet [Material Function Principle]

Electronic Shift Sensor Magnet [Material Function Principle]

Electronic shift sensors are commonly used in electric vehicles and certain intelligent transmission systems. Their internal shift detection mechanisms typically employ permanent magnets in conjunction with Hall sensors to achieve gear recognition, transmission control, and position detection. This article focuses on the sensor magnets used in such systems, covering their operating principles, materials, and functions.

The operating principle of induction magnets for electronic shifters is based on physical phenomena such as electromagnetic induction and the Hall effect. At its core lies a multipole magnet (primarily annular). Taking a common 8-pole magnetic ring as an example, eight magnetic poles are evenly distributed around the circumference in an alternating N-S-N-S pattern, with each pole corresponding to a 45-degree angle. The magnetic ring is fixed to the knob base and rotates synchronously with driver operation. Multiple Hall sensors or magnetic encoder chips are installed at fixed positions beneath the magnetic ring. Typically, at least two sensors with a 90-degree phase difference are required to form an orthogonal configuration. As the knob rotates, the sensors sequentially pass through different magnetic poles, outputting periodically varying sine and cosine signals. By detecting signal amplitude, phase, and zero-crossing points, the control unit precisely calculates the knob's absolute angular position. Each gear position (P, R, N, D, S, etc.) corresponds to a preset angular range. When the knob rotates into and remains within a specific range, the system identifies that gear position as selected.

Regarding materials, sintered ferrite and injection-molded ferrite are primarily used, with some applications employing injection-molded neodymium iron boron. All these materials require molds. Injection-molded magnets can be formed via injection molding, offering excellent impact resistance. Magnetization is achieved through multipolar magnetization.

Regarding function, the primary role of magnets is to generate a magnetic field. Here, the sensing magnet serves the same purpose—providing detectable magnetic field changes that enable the Hall sensor to detect gear shifts.

The above covers the relevant details about sensing magnets in electronic shifters.