Pressure Switch For Refrigeration System
The pressure switch is mainly used in the refrigeration system, in the pipeline circulation system of high pressure and low pressure, to protect the abnormal high pressure of the system to prevent damage to the compressor.
After being filled, the refrigerant flows into the aluminum shell (that is, inside the switch) through the small hole under the aluminum shell. The inner cavity uses a rectangular ring and a diaphragm to separate the refrigerant from the electrical part and seal it at the same time.
When the pressure reaches the low-pressure switch-on value 0.225+0.025-0.03MPa, the low-pressure diaphragm (1 piece) is turned over, the diaphragm seat moves upward, and the diaphragm seat pushes the upper reed to move upward, and the contacts on the upper reed are on the bottom yellow plate. The contact of the compressor is contacted, that is, the low pressure is connected, and the compressor starts to run.
The pressure continues to rise. When it reaches the high-pressure disconnect value of 3.14±0.2 MPa, the high-pressure diaphragm (3 pieces) flips, pushing the ejector rod upwards, and the ejector rod rests on the lower reed, so that the lower reed moves upward, and the contact on the lower yellow plate The point is separated from the contact on the upper reed, that is, the high pressure is disconnected, and the compressor stops working.
The pressure gradually balances (ie decreases). When the pressure drops to the high-pressure switch-on value minus 0.6±0.2 MPa, the high-pressure diaphragm recovers, the ejector rod moves down, and the lower reed recovers. The contacts on the lower yellow plate and the contacts on the upper reed are restored. Point contact, that is, high pressure is connected, the compressor works.
When the pressure drops to the low-pressure cut-off value of 0.196±0.02 MPa, the low-pressure diaphragm recovers, the diaphragm seat moves down, the upper reed resets down, and the contact on the upper yellow leaf separates from the contact on the lower reed, that is, low-pressure disconnect , The compressor stops working.
In actual use, the switch is disconnected when there is no pressure. It is installed in the car air conditioner system. After the refrigerant is filled (usually 0.6-0.8MPa), the pressure switch is in the on state. If the refrigerant does not leak, The system works normally (1.2-1.8 MPa);The switch is always on.
when the temperature is above seven or eight degrees, When the system does not work normally, such as poor heat dissipation of the condenser or dirty/ice blockage of the system, and the system pressure exceeds 3.14±0.2 MPa, the switch will be turned off;If the refrigerant leaks or the temperature is below seven or eight degrees, and the system pressure is lower than 0.196±0.02 MPa, the switch will be turned off. In short, the switch protects the compressor.
