What are the characteristics of the speed sensor?

There are 2 types of speed sensors: contact and non-contact

Contact

The contact speed sensor is in direct contact with the moving object. When the moving object touches the speed sensor, the friction drives the roller of the sensor to rotate. The rotating pulse sensor installed on the roller sends a series of pulses. Each pulse represents a specific distance value, so Line speed can be measured.

speed sensor

speed sensor

The utility model is simple in structure and easy to use. However, the diameter of the contact roller is always in contact with the moving object, and the outer circumference of the contact roller will be worn, thereby affecting the circumference of the contact roller. The number of pulses of each sensor is fixed. The impact sensor The measurement accuracy. In order to improve the measurement accuracy, a compensation circuit must be added to the secondary meter. In addition, the contact type will inevitably produce slip, and the existence of slip will also affect the measurement accuracy.

Contactless

The non-contact speed sensor has no direct contact with the moving object, and there are many non-contact measurement principles. The following are only 2 points for reference.

1. Photoelectric flow sensor

There is a reflective film on the blade edge of the impeller. When the fluid flows, the reflective film drives the impeller to rotate. The optical fiber reflects once every time the impeller rotates to generate an electrical pulse signal. The flow rate can be calculated according to the number of detected pulses.

2. Photoelectric wind speed sensor

The wind drives the anemometer to rotate, and the cam is driven by the gear to rotate proportionally. The optical fiber is interrupted by the cam disc to form a series of light pulses, and the photocell converts the light pulses into a constant signal, and the wind speed can be detected by calculation.

speed sensor

speed sensor

The non-contact speed sensor has a long service life and does not need to increase the compensation circuit. However, the pulse equivalent is not an integer multiple of the distance, so the speed operation is relatively complicated.

The performance of the speed sensor is summarized as follows:

(1) The output signal of the sensor is a pulse signal, which has good stability, is not easily disturbed by external noise, and has no special requirements for the measurement circuit.

(2) The utility model has the advantages of simple structure, low cost and stable and reliable performance. The fully functional microcomputer chip makes it easy to obtain the calculation conversion coefficient, so the application of speed sensors is very common.