The pressure balance structure principle of vacuum pressure switches

The pressure balance structure principle of vacuum pressure switches mainly involves the deformation of elastic elements, pressure sensing and signal conversion, as well as the regulation of pressure balance. The following is a specific analysis:

Deformation of elastic elements and pressure sensing

The elastic elements of vacuum pressure switches, such as diaphragms and bellows, will deform when the pressure in the vacuum system changes. For example, the diaphragm will bulge or dent to one side under pressure, and this deformation is the basis of pressure perception. The deformation of the elastic element will be captured by the sensor and converted into an electrical signal, which is a key step in achieving pressure-electrical signal conversion. Sensors may adopt silicon diffusion type semiconductor pressure sensors, etc. The resistance value of the internal bridge circuit will change with the deformation of the elastic element, thereby disrupting the bridge balance and generating a current corresponding to the pressure.

Pressure balance adjustment

Take the small-orifice suction confirmation type vacuum pressure switch as an example. Its pressure balance structure involves components such as the suction orifice, adjustable needle valve and the internal hole diameter of the switch. In the figure, S4 represents the effective cross-sectional area of the suction orifice, S2 is the effective cross-sectional area of the adjustable needle valve, S1 and S3 are the internal apertures of the suction confirmation type switch, and S1 = S3. When the workpiece is not adhered, the S4 value is relatively large. At this time, by adjusting the needle valve to change the size of the S2 value, the pressure at both ends of the pressure sensor can be balanced, that is, p1 = p2. When the workpiece is attracted, S4 = 0, and a pressure difference p1 - p2 occurs. This pressure difference will be detected by the pressure sensor, thereby triggering the switch to act.

Signal output and control

The pressure change signal detected by the pressure sensor, after processing, will be compared with the preset pressure threshold. When the pressure reaches or exceeds the set value, the switch will send out an electrical signal to direct the related equipment to act, such as starting or stopping the vacuum pump, opening or closing the vacuum valve, triggering the alarm or safety device, etc. This signal output and control function ensures the stable operation of the vacuum system within the set pressure range.