Pneumatic butterfly valve
Inflatable pneumatic butterfly valve. Inflatable pneumatic butterfly valve is a new type of pneumatic butterfly valve developed since the 1960s. Its structural feature is that a floating piston is installed at the lower part of the cylinder barrel, and a sealed gas chamber composed of the floating piston and one end of the cylinder barrel is filled with high-pressure nitrogen. The floating piston is equipped with a large section O-ring, which completely separates oil and gas. The working piston is equipped with a contraction valve and an extension valve that can change the cross-sectional area of the channel according to its movement speed.
When the wheels are bouncing up and down, the working piston of the pneumatic butterfly valve reciprocates in the oil, causing the oil pressure difference between the upper chamber and the lower chamber of the working piston, and the pressure oil pushes open the compression valve and the extension valve to move back and forth. Because the valve has a large damping force on the pressure oil, the vibration is attenuated.
Pneumatic butterfly valve with adjustable resistance. The suspension of a vehicle equipped with an adjustable resistance pneumatic butterfly valve usually uses an air spring with variable stiffness as an elastic element. The principle is that if the air pressure of the air spring rises, the pressure in the air chamber of the pneumatic butterfly valve will also rise, and the throttle aperture of the oil will change due to the change of the pressure, so as to achieve the purpose of changing the damping stiffness.
The shock absorber is a vulnerable part in the process of vehicle operation. The working quality of the shock absorber will directly affect the stability of the vehicle and the life of other parts. Therefore, we should keep the shock absorber in good working condition. The following methods can be used to check whether the shock absorber works well.
1. Stop the car after driving 10km on the road with poor road conditions, touch the shock absorber shell with your hand. If it is not hot enough, explain that there is no resistance inside the shock absorber, and the shock absorber does not work. At this time, take part in the appropriate lubricating oil, and then stop the test. If the shell is hot, it means that the shock absorber is short of oil, and it should be filled with enough oil; Otherwise, it indicates that the shock absorber is invalid.
2. Press the bumper firmly, and then release it. If the car jumps 2-3 times, it indicates that the shock absorber works well.
3. If the vehicle vibrates violently in case of slow driving and emergency braking, it indicates that there is a problem with the shock absorber.
4. Dismantle the shock absorber and erect it, clamp the lower connecting ring on the bench clamp, and pull and press the shock absorber rod several times with force. At this time, there should be stable resistance. The resistance to pull up (recover) should be greater than the resistance to press down. If the resistance is unstable or no resistance, it may be due to lack of oil in the shock absorber or damage of valve parts, and repair or replacement of parts should be stopped.
From the above, we can know that when the car is driving more than ten kilometers on an uneven road, it is necessary to check whether the pneumatic butterfly valve is still working. If not, the main parts may have been damaged or take an appropriate smooth oil test. Abnormal chatter occurs during driving, which indicates that there is a problem with the pneumatic butterfly valve. Check the working condition of the pneumatic butterfly valve when the car is stopped for secondary maintenance. The inspection method is: fix the lower end of the pneumatic butterfly valve on the bench clamp, stretch and tighten it several times by hand, the normal pneumatic butterfly valve should have a certain damping force, and the resistance to stretching should be greater than the resistance to tightening. If it is unstable or has no resistance, it may be that the pneumatic butterfly valve is short of oil or the parts are damaged. It should be repaired or replaced with new parts.

Electromagnetic flowmeter has been widely used in industry, medicine and other industries due to its convenient installation and use, simple structure and operation, high measurement accuracy, measurement results not affected by external physical parameters, alarm function and fault self diagnosis. Electromagnetic flowmeter is an instrument for measuring the volume flow of conductive liquid, which is made by Faraday's law of electromagnetic induction. Since the early 1950s, China has realized the industrial application of electromagnetic flowmeter. In recent years, the output of electromagnetic flowmeter in the world has been in an important position in the output of industrial flow meters. Generally speaking, electromagnetic flowmeter is composed of flow sensor transmitter. The flow sensor converts the volume flow of conductive liquid flowing through the pipe into a linear electrical signal. The transmitter is composed of excitation circuit, signal filtering and amplification circuit, A/D sampling circuit, microprocessor circuit, D/A circuit, transmission circuit, etc. The conversion principle is Faraday's law of electromagnetic induction, that is, the conductor cuts the electromagnetic line through the magnetic field to generate aerodynamic force. The magnetic field of the flow sensor is realized by excitation, and now most flow sensors use low-frequency square wave excitation. In the electromagnetic flowmeter, the conductive medium in the measuring tube is equivalent to the conductive metal rod in the Faraday test, and the two electromagnetic coils at the upper and lower ends generate a constant magnetic field. When a conductive medium flows through, an induced voltage will be generated. Two electrodes inside the pipe measure the induced voltage generated. The measuring pipe is electromagnetically isolated from the fluid and the measuring electrode through non-conductive linings such as rubber and Teflon.