Tachometer is one of the necessary instruments in machinery industry, which is used to measure the speed, linear speed or frequency of motor. Commonly used in motor, fan, paper, plastic, chemical fiber, washing machine, automobile, aircraft, ship and other manufacturing industries. Most commonly used are hand-held centrifugal tachometers. Tachometer measurement is essential in all fields of national economy.
Rotational speed is the physical quantity of the ratio of the number of revolutions of a rotating body to time. In engineering, it is usually expressed as rotational speed = number of revolutions / time. It is an important parameter to describe the rotational motion of an object. Electricians often need to measure the speed of the motor and its driving equipment, using a portable tachometer. Tachometer is an instrument used to measure motor speed and linear speed. There are many kinds of tachometers. Generally, there are mechanical centrifugal tachometers and digital electronic tachometers.
The tachometer reads the received digital pulse signal (sent by the sensor) directly into the counting port of the CPU after processing, calculates the speed and the corresponding position of the pointer through the software, and then amplifies it through the control port of the CPU to drive the stepper motor to rotate in the positive and negative directions and indicate the corresponding speed value (the pointer is directly installed on the rotating shaft of the stepper motor). The step of the stepper motor is only 1 / 3 degree.
1. The large static moment pointer is not easy to shake and has strong anti vibration performance.
2. It adopts single-chip microprocessor through software design, so it has high precision and strong anti-interference.
3. The hour meter adopts liquid crystal display and has no mechanical part, so it is more reliable and has a sense of the times.
Because the pointer indication conforms to the traditional visual recognition habit and is convenient for computer remote processing and networking requirements, the digital stepping motor instrument is the development trend of modern automobile instrument and motorcycle instrument. The stepping motor of switec company has been widely used in various automobile, motorcycle and engineering machinery instruments at home and abroad. Micro stepping motor for vehicle is a special new type of automobile instrument accessories. The instrument designed by it can not only meet the traditional visual recognition habits, but also meet the requirements of digital processing. It is an ideal accessory for modern instruments.
Centrifugal tachometer is composed of transmission part, receiver and indicator. It is one of the most traditional speed measurement tools. Its main advantages are simple structure, convenient use and low accuracy. Its working principle is a tachometer formed by using the principle of centrifugal force of rotating mass and rotation angle or proportion. When the shaft of the tachometer rotates, the weight on the centrifuge leaves the shaft center under the action of inertial centrifugal force, and drives the needle to rotate through the transmission device. The rotational speed of the shaft is determined according to the position of the pointer where the inertial centrifugal force and the spring force are balanced.
The magnetic tachometer uses the rotating magnetic field to generate the rotating force on the metal cap, and uses the balance between the rotating force and the hairspring force to indicate the rotating speed. Magnetic tachometer is a model of successful use of magnetic force and a mechanical tachometer based on the principle of magnetic force; It is generally installed locally, and it can be installed in a short distance with a flexible shaft. Magnetic tachometer, because of its simple structure. The flexible shaft is easy to be damaged during remote installation.
Purpose of tachometer
The tachometer is generally set in the instrument panel and placed symmetrically with the speedometer. The tachometer works according to the magnetic principle. It receives the pulse signal generated when the primary current in the ignition coil is interrupted and converts this signal into a displayed speed value. The faster the engine speed, the more pulses generated by the ignition coil, and the greater the speed value displayed on the table.
Cars are generally electronic tachometers, including pointer type and liquid crystal digital display type. There is a digital integrated circuit in the meter. It drives the pointer to move or digital display after calculating the voltage pulse transmitted from the ignition coil. In addition, there is another kind of tachometer, which takes out the pulse signal from the generator and sends it to the tachometer circuit to explain the speed value. However, due to the influence of factors such as generator belt slip, the value is not very accurate.
The above is the basic introduction to the tachometer. If you want to know more, please pay attention to us. See you next time.