new positive and negative pressure switch

Mechanical pressure switches cause micro switch action through pure mechanical deformation. Like the widely used pressure switches, reliable springs and precision micro switches are used as key components.When the pressure increases, the different sensing pressure components (diaphragm, bellows, piston) will be deformed and will move upward through the railing spring and other mechanical structures, and finally activate the uppermost micro switch to output electrical signals.Mechanical pressure switches are widely used in automation systems for measuring gas and liquid pressures in chemical, machinery, hydrology, electric power, environmental protection, etc.It is especially used to detect the fluid pressure of commercial water dispensers and coffee machines; detect the water pressure of water heaters or household gas stoves; detect the blockage of household or industrial air pumps; pressure sensing and control of steam cleaners; detect the operation of vacuum pumps.Because the adjustment is convenient and flexible, and the installation is simple, it can replace most occasions where liquid level switches are used.

However, in the current pressure switch application market, in addition to the demand of positive pressure, there is also the demand of negative pressure;However, there are few pressure switches with negative pressure induction at present, and even if they have, they are complicated in structure, the product quality is unreliable or the application pressure range is very low.The traditional pressure switch includes a shell, a micro switch set on the top of the shell, an adjusting screw threaded on the shell, a diaphragm set in the inner cavity of the shell, Piston plate and spring under the adjusting screw, and the bottom of the piston is pressed against the diaphragm, the spring is arranged between the adjusting screw and the piston piece, the bottom of the micro switch is provided with a switch button, and the top of the piston piece is connected with the switch button.However, this type of pressure switch has two sealed cavities, a positive pressure sealed cavity and a negative pressure sealed cavity. In order to achieve negative pressure sealing, the negative pressure cavity requires a set of diaphragms or compression devices, which makes the product structure complex。In addition, it is difficult to achieve reliable sealing of the negative pressure sealing cavity with existing structures, and leakage or low pressure resistance often occurs.

The new type of pressure switch can be used in both positive and negative pressure occasions, simplifying the product structure and improving product reliability.It includes a shell, a micro switch set on the top of the shell, an adjusting screw threaded on the shell, a diaphragm set in the inner cavity of the shell, Piston plate and main spring located under the adjusting screw，The bottom of the piston is pressed against the diaphragm, and the main spring is set between the adjusting screw and the piston.The space between the diaphragm and the bottom of the inner cavity of the housing forms a closed positive/negative pressure cavity，A negative pressure spring is arranged between the diaphragm and the bottom of the inner cavity of the casing.There is a supporting piece between the negative pressure spring and the diaphragm，The middle of the diaphragm is recessed downward. The shell includes a rubber shell and a rubber cover, and the rubber cover is connected to the bottom of the rubber shell.The main spring is arranged between the adjusting screw and the piston plate, and the space between the diaphragm and the bottom of the inner cavity of the housing forms a closed positive/negative pressure cavity,There is a negative pressure spring between the diaphragm and the bottom of the inner cavity of the shell. When the negative pressure spring is not installed in the positive/negative pressure cavity, the pressure switch senses positive pressure;When a negative pressure spring is installed in the positive/negative pressure cavity, since the elastic force of the negative pressure spring is greater than that of the main spring, in the initial state, the diaphragm is in the up position. When the negative pressure reaches a certain value, the diaphragm and the piston are affected. The pressure drives down and compresses the negative pressure spring to realize the conversion of the micro switch。

In summary, the new pressure switch has only one sealed cavity, relatively simple structure and reliable sealing. It can be applied to both positive pressure and negative pressure applications, so that the product can simplify the product structure while ensuring negative pressure applications. Improve product reliability, can achieve greater negative pressure setting and greater pressure resistance.