Pick up speed magnetic sensor

Types of Pick-Up Speed Magnetic Sensors

A magnetic pickup sensor is used for a variety of purposes, including measuring the speed of a rotating object, detecting the presence of metallic objects, and more. There are various types of pick-up speed magnetic sensors, each designed for specific applications. Some common types of pick-up speed magnetic sensors include:

• Hall Effect Pick-Up Speed Sensors

In vehicles, a Hall effect pickup senses the magnetic field of a window ring. The Hall effect sensor is a non-contact device that converts the presence of a magnetic field into a voltage signal. It consists of three main components: a voltage source, a Hall element, and a load resistor. When the rotating part is in front of the sensor, the magnetic field is detected by the Hall effect element, which then produces a voltage signal proportional to the strength of the magnetic field.

• Magnetoresistive (MR) Speed Sensors

Magnetoresistive speed sensors are two-terminal devices that change their resistance when a magnetic field is detected by a rotating component. The resistance of the sensor depends on the relative position of the magnetic field and the current flow direction through the sensor. When the magnetic field changes with rotation, resistance also changes. Magnetoresistive sensors are not as common as Hall effect sensors, but they can provide higher resolution and accuracy to specific applications.

• Variable Reluctance (VR) Speed Sensors

Variable reluctance speed sensors work on the principle of variations in the reluctance of the magnetic field between a rotating component's teeth and a stationary coil. When the rotating part passes in front of the sensor, the reluctance changes. This change in reluctance causes a variation in the magnetic field and the induction of an electric current in the coil. The frequency of the current pulse is directly proportional to the speed of the rotating part.

• Reed Switch Speed Sensors

Reed switch speed sensors are simple and low-cost devices that contain two flexible metal reeds in a glass tube. One reed acts as a contact and the other as a switch. The presence of a magnetic field (such as that from a rotating gear with teeth) causes the reeds to come into contact. When the reeds come into contact, the electrical circuit is closed, and when the magnetic field changes, the circuit opens. Reed switch sensors provide a switching function rather than analog information.

• Inductive Pick-Up Speed Sensors

Inductive pick-up sensors generate an AC voltage when a metal gear or a gear with teeth passes in front of a coil. The voltage generated has an amplitude, frequency, and waveform that changes with the speed of the rotating gear. Inductive pick-up sensors are simple, robust, and affordable, but they are not as accurate as other types of sensors. They are suitable for applications where high precision is not required.

Specifications and Maintenance of Pick-up Speed Magnetic Sensor

The following are the specifications of magnetic pickup speed sensors:

• Signal output: The signal output is the type of information that the magnetic sensor sends. It is usually a voltage signal. This signal tells the speed the vehicle is moving at. This enables the control system to make the necessary adjustments.
• Response time: The response time refers to how quickly the sensor reacts to changes in the magnetic field. A faster response time provides better accuracy in measuring speed variations.
• Operating temperature: The operating temperature is the range of temperatures where the sensor can work effectively. The pick-up sensor will still give accurate readings within this temperature range. The operator should not install the sensor close to the exhaust system or in other places where it might get overheated.
• Accuracy: Accuracy refers to how closely the sensor's measured speed matches the actual speed of the rotating shaft. A more accurate sensor provides better performance.
• Installation type: The installation type of the magnetic pickup unit refers to how it is mounted to the vehicle. There are several options for installing sensor housings in various places on the vehicle chassis. This is how the sensor is attached to the vehicle so that it can accurately measure its speed.
• Supply voltage: The supply voltage of the magnetic sensor is the voltage required to power the sensor. The electrical system of the vehicle must be compatible with this voltage. Otherwise, the sensor will not work.

It’s important to maintain magnetic pickup speed sensor and wheel speed sensors regularly to ensure they provide accurate information to the vehicle's control system. Users can follow the steps below to maintain the sensors:

• 1. Always check the sensors' electrical connections to ensure they are clean, tight, and free from corrosion. Loose connections can cause the sensor to lose power or malfunction.
• 2. Inspect the sensor and its wires for damage, such as cuts, cracks, or exposed wires. If there is damage, replace the sensor or wire harness as required.
• 3. Ensure the air gap between the sensor and the rotating part (like the ring gear) is correct. The manufacturer usually specifies the correct air gap. Adjust if necessary to maximize signal strength.
• 4. Protect the sensors from moisture and dirt by ensuring they are properly sealed and installed in a clean, dry location.
• 5. Periodically test the sensors using diagnostic tools to confirm they are working correctly. Follow the manufacturer's instructions for diagnosing sensor problems.

How to choose pick up speed magnetic sensors

Choosing the right mag pickup speed sensor requires critical consideration of various factors as follows:

• Consider the application:

This is the first thing to consider when selecting a speed sensor. One should understand the motor's application and its requirements. Some of the questions to consider are: What is the target operating speed and temperature? Is high accuracy speed detection required or high resolution? What is the motor's environment like? For example, is it a hazardous environment that requires explosion-proof sensors? Answering such questions will help select a pickup sensor that will work effectively in a given application.

• Speed and resolution:

This involves selecting a sensor that matches the motor speed and resolution. One should choose a sensor with a maximum frequency greater than the maximum speed of the motor. The sensor's resolution should also be considered. A high-resolution sensor will be required for applications where speed accuracy is crucial.

• Installation:

When selecting a sensor, one should take into account how it will be installed. The sensor should be compatible with the available mounting space. This is because some sensors have specific requirements for the target gear or the air gap between the sensor and the target gear.

• Environmental conditions:

This involves considering the environmental conditions in which the sensor will operate. Some sensors are designed to work in extreme conditions like high temperatures or wet environments. If the environment is hazardous, then an explosion-proof sensor will be required.

• Electrical compatibility:

This involves selecting a sensor that is electrically compatible with the control system. The sensor's output signal and voltage level should match the input requirements of the control system to be used.

• Reliability and durability:

These are important factors to consider when choosing a sensor. One should select a sensor from a reputable manufacturer. This is because well-known manufacturers produce sensors of high quality and consistent performance. The sensor should also be designed to withstand harsh conditions and have a long lifespan.

How to DIY and Replace Pick Up Speed Magnetic Sensor

Here are the easy steps to replace a magnetic pick up sensor:

• Prepare for the replacement by getting the right sensor specifications and any other tools needed for the job.
• Locate the sensor on the vehicle. Typically, it is close to the transmission system, a place that the sensor can access the rotating part.
• Unplug the sensor from the wiring by disconnecting the electrical connector to the sensor. Clean the area around the sensor before removing it to prevent dirt from getting into the transmission system.
Read the installation manual that comes with the new sensor to make sure it is compatible with the vehicle.
• Remove the old sensor using the appropriate wrench or socket. Be careful not to damage the mounting surface when removing it.
• Install the new sensor by screwing it into the mounting surface. Make sure the sensor is aligned correctly and securely attached.
• Once it is installed properly, plug in the electrical connector to the sensor.
Test the function of the sensor by starting the engine and checking for any warning lights on the dashboard. If everything is okay, the process is complete.

Q and A

Q1: What is the importance of a pickup speed magnetic sensor?

A1: A pickup speed magnetic sensor is essential for detecting the rotation of gears and shafts in various applications. It provides data on rotational speed, which is crucial for maintaining accuracy and safety in systems like vehicles and industrial machinery.

Q2: How to test a pickup speed sensor?

A2: To test a pickup speed sensor, a digital multimeter can be used to measure its output voltage while rotating the connected gear or shaft by hand. The voltage should increase smoothly with speed. Visual inspection for any physical damage or contamination should also be done.

Q3: What are the signs of a bad speed sensor?

A3: Signs of a bad speed sensor may include erratic speedometer readings, ABS or traction control warning lights, transmission shifting issues, and engine performance problems. These indicate potential issues with detecting vehicle speed or wheel rotation.

Q4: How often should a speed sensor be replaced?

A4: Speed sensors usually have a long lifespan and don't require regular replacement. However, they should be replaced when they fail or show symptoms of malfunction. Routine maintenance and inspections are important to detect any issues early and prevent further damage.

Q5: Can speed sensor problems be fixed?

A5: Yes, speed sensor problems can be fixed by cleaning or replacing the sensor if faulty. Repairs may also involve fixing damaged wiring or connectors. Proper calibration and testing after repair are important to ensure accurate speed detection.