Rotary speed sensors are divided into two types: contact type and non-contact type according to the installation form.
Contact
The contact type rotary speed sensor is in direct contact with the moving object. When the moving object comes into contact with the rotary speed sensor, the friction force drives the roller of the sensor to rotate. The rotating pulse sensor mounted on the roller sends out a series of pulses. Each pulse represents a certain distance value, so that the linear velocity can be measured.
The contact type rotation speed sensor has a simple structure and is convenient to use. However, the diameter of the contact roller is always in contact with the moving object, and the outer circumference of the roller will wear out, thereby affecting the circumference of the roller. The number of pulses is fixed for each sensor. Affect the measurement accuracy of the sensor. To improve the measurement accuracy, a compensation circuit must be added to the secondary instrument. In addition, the contact type will inevitably produce slip, and the existence of slip will also affect the accuracy of the measurement.
Contactless
The non-contact rotary speed sensor has no direct contact with the moving object. There are many non-contact measurement principles. Only two points are introduced below for reference.
Photoelectric flow sensor
The edge of the blade of the impeller is attached with a reflective film, which drives the impeller to rotate when the fluid flows. The optical fiber transmits the reflection light every time the impeller rotates and generates an electric pulse signal. The flow rate can be calculated from the number of pulses detected.
Photoelectric wind speed sensor
The wind drives the anemometer to rotate, and drives the cam to rotate proportionally after being driven by a gear. The optical fiber is interrupted by the cam wheel to form a series of light pulses, which are converted into a fixed signal by the photoelectric tube, and the wind speed can be detected by calculation.
The non-contact rotation speed sensor has a long life and does not need to add a compensation circuit. But the pulse equivalent is not an integer multiple of the distance, so the speed calculation is relatively complicated.
The performance of the rotary speed sensor can be summarized as follows:
(1). The output signal of the sensor is a pulse signal, and its stability is relatively good, it is not easy to be interfered by external noise, and there is no special requirement for the measurement circuit.
(2). The structure is relatively simple, the cost is low, and the performance is stable and reliable. The full-featured microcomputer chip makes the calculation conversion coefficient easy to obtain, so the speed sensor application is extremely common.
speed odometer sensor
Contact
The contact type rotary speed sensor is in direct contact with the moving object. When the moving object comes into contact with the rotary speed sensor, the friction force drives the roller of the sensor to rotate. The rotating pulse sensor mounted on the roller sends out a series of pulses. Each pulse represents a certain distance value, so that the linear velocity can be measured.
The contact type rotation speed sensor has a simple structure and is convenient to use. However, the diameter of the contact roller is always in contact with the moving object, and the outer circumference of the roller will wear out, thereby affecting the circumference of the roller. The number of pulses is fixed for each sensor. Affect the measurement accuracy of the sensor. To improve the measurement accuracy, a compensation circuit must be added to the secondary instrument. In addition, the contact type will inevitably produce slip, and the existence of slip will also affect the accuracy of the measurement.
Contactless
The non-contact rotary speed sensor has no direct contact with the moving object. There are many non-contact measurement principles. Only two points are introduced below for reference.
Photoelectric flow sensor
The edge of the blade of the impeller is attached with a reflective film, which drives the impeller to rotate when the fluid flows. The optical fiber transmits the reflection light every time the impeller rotates and generates an electric pulse signal. The flow rate can be calculated from the number of pulses detected.
Photoelectric wind speed sensor
The wind drives the anemometer to rotate, and drives the cam to rotate proportionally after being driven by a gear. The optical fiber is interrupted by the cam wheel to form a series of light pulses, which are converted into a fixed signal by the photoelectric tube, and the wind speed can be detected by calculation.
The non-contact rotation speed sensor has a long life and does not need to add a compensation circuit. But the pulse equivalent is not an integer multiple of the distance, so the speed calculation is relatively complicated.
The performance of the rotary speed sensor can be summarized as follows:
(1). The output signal of the sensor is a pulse signal, and its stability is relatively good, it is not easy to be interfered by external noise, and there is no special requirement for the measurement circuit.
(2). The structure is relatively simple, the cost is low, and the performance is stable and reliable. The full-featured microcomputer chip makes the calculation conversion coefficient easy to obtain, so the speed sensor application is extremely common.
speed odometer sensor
