How Reverse Detection Rotation Speed Sensors Work Using the Hall Effect Principle

The reverse detection rotation speed sensor developed by Shenzhen Soway Technology Development Co., Ltd. is a precision device designed to measure both the rotational speed and the direction of a rotating shaft or wheel. Its operation is fundamentally based on the Hall effect principle, which enables accurate detection through non-contact magnetic sensing.

Working Principle

At the heart of the sensor’s operation are two magnets mounted on the rotating shaft or wheel. These magnets are installed in a specific arrangement such that one magnet’s north (N) pole faces the Hall effect sensor while the other magnet’s south (S) pole faces it. This arrangement is critical for the sensor to distinguish the direction of rotation.

As the shaft or wheel turns, the magnets sequentially pass by the sensor head. When a magnet approaches the sensor, the magnetic field around the sensor changes accordingly. The Hall element inside the sensor detects this change in the magnetic field and converts it into an electrical signal. The presence of two magnets with opposite poles causes the sensor to generate two distinct signals per rotation, corresponding to the alternating magnetic polarity.

Direction Detection

What enables reverse detection capability is the sequence in which the N and S poles pass the sensor. By analyzing the order and timing of the signals generated by the Hall element, the sensor’s electronic circuitry can identify whether the shaft is rotating forward or backward.

For example, if the N pole passes first followed by the S pole, the sensor registers a forward rotation. Conversely, if the S pole passes first followed by the N pole, the sensor recognizes reverse rotation. This directional determination is essential in applications where the motor or shaft must be monitored for correct rotational direction to avoid damage or errors.

Speed Measurement

Along with direction detection, the sensor also calculates the rotational speed. This is done by measuring the frequency of the electrical pulses generated as the magnets pass the sensor. The faster the shaft rotates, the higher the pulse frequency. The sensor can thus provide real-time speed data with high precision.

Advantages of Using Hall Effect-Based Reverse Detection Rotation Speed Sensors

Non-contact Measurement: The sensor does not require physical contact with the rotating part, which eliminates mechanical wear and increases reliability.

Robustness: Hall effect sensors operate well under harsh industrial environments including dust, dirt, and moisture.

Accurate Direction Recognition: The use of two magnets with opposite poles allows clear identification of rotational direction without ambiguity.

Compact and Easy Installation: The sensor and magnet setup is simple to mount on existing shafts or wheels without complex mechanical adjustments.