First, the basic principle of hydraulic pressure measurement
Hydraulic pressure refers to the internal force generated when a liquid is acted by an external force in a closed system, which is usually expressed by the force per unit area. The international unit is Pascal (Pa), and megapascals (MPa) or bars are commonly used in engineering. The generation of hydraulic pressure comes from the push of the pump, which transfers energy to the actuator (such as hydraulic cylinder or hydraulic motor) through the incompressibility of liquid.
The basic principle of measuring hydraulic pressure is to convert liquid pressure into readable value by using pressure sensor or pressure gauge. Common measurement methods include mechanical measurement and electronic measurement.
Second, the commonly used hydraulic pressure measuring tools
1. Spring tube
pressure gauge
This is a traditional mechanical pressure measuring instrument, and its core component is a bent spring tube. When liquid pressure acts on the inside of the spring tube, the spring tube will be elastically deformed, and the pointer will be driven to rotate through the mechanical transmission mechanism, thus indicating the pressure value. This kind of pressure gauge has simple structure and high reliability, and is widely used in industrial field.
2. Diaphragm manometer
Diaphragm manometer uses metal diaphragm as sensing element. When the pressure changes, the diaphragm is deformed, and the deformation is transformed into pointer displacement through mechanical structure. This kind of instrument is suitable for low voltage measurement and has good sensitivity.
3. Electronic pressure sensor
Electronic pressure sensors use piezoresistive, capacitive or piezoelectric elements to detect pressure changes and convert pressure signals into electrical signals for output. By connecting display instrument or PLC system, remote transmission and automatic monitoring can be realized. Electronic sensors have the advantages of high precision, fast response and easy integration, and are widely used in modern hydraulic systems.
Three, the matters needing attention
of hydraulic pressure measurement
1. Select an appropriate measuring range: the measuring range of the measuring instrument should be slightly higher than the maximum working pressure of the system, so as to avoid instrument damage caused by over-measuring range.
2. Reasonable installation position: The pressure measuring point should be selected in a place where the fluid is stable, free from eddy current and pulsation, and avoid being installed near the pump outlet or valve, so as not to affect the measurement accuracy.
3. Regular calibration and maintenance: Pressure gauges or sensors may drift or have errors after being used for a period of time, so they need to be calibrated and maintained regularly to ensure the reliability of data.
Fourth, the application of hydraulic pressure measurement
Hydraulic pressure measurement is widely used in construction machinery, aerospace, automobile manufacturing, ship power and other fields. For example, in an excavator, the working state of the hydraulic pump can be judged by measuring the pressure of the hydraulic oil; In the aircraft landing gear control system, accurate pressure measurement is helpful to ensure safe landing.
tag
The measurement of hydraulic pressure is an important means of operation monitoring and fault diagnosis of hydraulic system. With the development of sensing technology and automatic control, modern hydraulic pressure measurement is developing in the direction of digitalization and intelligence. Knowing and mastering the correct measurement method can not only improve the operation efficiency of the equipment, but also provide a strong guarantee for the safety and stability of the system.