Speed sensor is a kind of can feel the speed of the object to be tested and can be converted into can take advantage of the output signal of the sensor. Speed is refers to the movement of the object displacement variation in unit time. And including angular velocity and linear velocity, so it is with their corresponding angular velocity sensor and speed sensor, collectively known as speed sensor.

To introduce the following rotary speed sensor, according to the installation of the it forms can be divided into two types: contact and non-contact.

Contact speed sensor

It is a direct contact and moving object, when the rotating speed sensor in contact with the movement of objects, the friction roller turn will drive the sensor. Turn the pulse sensor is installed on the roller, it will send out a series of pulse, and each pulse is on behalf of the value of a certain distance. So when using sensors, must on the surface of the roller with some friction coefficient larger materials or are applying pressure, so that we can well reduce the slip.

The sensor structure is very simple, and use is very convenient. But there is a problem, that is, when the movement of objects and the diameter of the contact roller is always contact with, and this will lead to the periphery of the roller under wear, so the wheel circumference of a certain impact. But the number of pulses for each sensor is fixed, therefore have a certain influence on the accuracy of measurement of sensor. If you want to improving the measuring accuracy of the sensor, it is necessary to adding some compensation circuit in secondary instrument; In addition, contact sensor will inevitably produce the slip, and the existence of the slip and will have a certain influence on the correctness of the measurement. So, in the use of sensors, it must be on the surface of the roller with some of the friction coefficient is larger material or some other positive pressure, such doing can effectively reduce the slip.

Non-contact sensors

As the name suggests, it is and the motion of an object, there is no direct contact, and non-contact measurement principle is very much, the following is a brief introduction of two, as a reference.

1, photoelectric speed sensor

Its action principle is: there is wind, will drive the rotation of the anemometer, and then after gear transmission driven CAM, in direct proportion relationship between spin. At that time, optical fiber can be ACTS wheels take turns to interrupt, then can form a series of light pulses, it passes through cell can be converted into electrical signals, after calculation, can detect the wind speed.

2, photoelectric velocity sensor

The edge of the impeller blades of this kind of sensor location on the reflective film, when the circulation flow can drive the impeller rotating together, every turn a circle, the impeller of reflective optical fiber can transmit a, then generates an electrical signal. So the number of pulses can be obtained by testing, effectively calculate the velocity of flow.