A basic magnetic speed sensor, also known as a magnetic pickup or magnetic speed pickup, is a device used to measure the rotational speed of a target object with a magnetic component. It operates on the principle of electromagnetic induction and consists of a few key components:
Permanent Magnet: The sensor includes a small permanent magnet that creates a magnetic field around it.
Coil: A coil of wire is placed close to the magnetic field created by the permanent magnet. This coil can be wound around a core to enhance its sensitivity to changes in the magnetic field.
Target Object: The target object, which is usually a rotating shaft or gear, has a metal component attached to it, such as a ferrous tooth or gear tooth. This metal component acts as a trigger for the magnetic sensor.
Here's how the basic magnetic speed sensor operates:
Magnetic Field Interaction: As the target object rotates, the metal component on it passes near the magnetic sensor's permanent magnet. When the metal component comes close, it disrupts the magnetic field around the coil.
Electromagnetic Induction: The disruption of the magnetic field induces a voltage in the coil, generating a small electrical signal. The amplitude and frequency of this signal depend on the speed at which the target object is rotating.
Signal Output: The induced voltage in the coil is processed by external electronics connected to the sensor. These electronics may amplify and condition the signal to make it suitable for further processing.
Speed Measurement: By measuring the frequency of the electrical signal, the rotational speed of the target object can be determined. The frequency of the signal is directly proportional to the speed of the rotating object, allowing the sensor to accurately measure its rotational speed.
Applications:
Magnetic speed sensors are commonly used in various industries and applications, including:
Automotive: They are used in vehicles to measure the speed of the engine crankshaft or the vehicle's wheels, enabling functions like speedometers and traction control systems.
Industrial Machinery: Magnetic speed sensors are utilized in industrial equipment to monitor the rotational speed of rotating parts like motors, fans, and conveyor belts.
Aerospace: They find application in aircraft to measure the speed of aircraft engines and other rotating components.
Marine: Magnetic speed sensors can be used in marine applications to measure the speed of boat propellers or other rotating marine equipment.
Magnetic speed sensors are preferred for their simplicity, durability, and ability to operate in harsh environments where other sensing technologies may be less suitable.