The vacuum pressure switch achieves equipment automation control and safety protection by precisely sensing pressure changes in the vacuum environment. Its working principle can be divided into three core links: sensing element deformation, contact action triggering, and control function implementation.
The deformation of sensing elements is the basis for vacuum pressure switches to sense pressure. When the pressure inside the vacuum system changes, elastic components such as diaphragms, bellows, or pistons will deform. For example, in vacuum packaging equipment, as the air inside the packaging chamber is drawn out and the pressure decreases, the diaphragm will sink towards the vacuum side due to the pressure difference between the inside and outside, and its deformation is linearly related to the pressure value. This mechanical deformation is the physical basis for subsequent signal conversion.
The contact action triggers the conversion of mechanical deformation into electrical signals. When the pressure reaches the preset threshold, the deformation sensing element pushes the micro switch to move through mechanical structures such as lever springs. For example, the ZSE series vacuum pressure switch from SMC Corporation in Japan adopts a continuous displacement setting method. When the diaphragm deformation reduces the contact spacing to a critical value, the electrical contacts close and output a switch signal. Some models also have hysteresis function, which avoids misoperation caused by pressure pulsation by setting the on/off pressure difference.
The control function implementation process controls the equipment status through electrical signals. When the vacuum pressure is lower than the set value, the contact can be closed to start the vacuum pump; After the pressure returns to a safe range, the contact opens to stop the equipment. In the airtightness testing system, if a leak is detected causing the pressure to rise above the threshold, the switch will trigger an alarm device. In addition, the vacuum pressure switch also supports multi set point control, such as setting three thresholds for start, stop, and alarm simultaneously, to meet the requirements of complex working conditions.