How does the pressure switch of Automobile Air Conditioner Work
How does the pressure switch of Automobile Air Conditioner Work
The pressure switch is ubiquitous in the automatic control. It could be installed in the refrigerant circulation pipeline of automobile air conditioning to detect the pressure of the refrigeration circulation system, and starts the corresponding protection circuit when the pressure is abnormal, to prevent the damage of the system. The common pressure switch mainly include the high voltage switch, the low voltage switch, the double pressure switch and the triple pressure switch and so on. The following is the principle of work of these automotive air-conditioning pressure switch .
1:Working principle of high pressure switch
When the automobile air conditioner is working , If the Heat Sink Block, cooling fan does not work or excessive refrigerant and other abnormal conditions appear, the system pressure will be too high and damage the system components if not controlled.
The high pressure switch is installed in the high pressure pipeline, generally installed on the Drying bottle, and connected in the compressor electromagnetic clutch circuit or condenser fan circuit. When the system pressure is too high, high pressure switch will act to cut off the Clutch Circuit or cut in the cooling Fan high-speed circuit, to prevent the pressure continues to rise, to avoid damage to the system.
When the refrigerant of the refrigeration system is insufficient or leaks, the frozen lubricating oil may also leak, resulting in poor lubrication of the air conditioning system. If the compressor runs out of oil, it will cause serious damage.
Low pressure switches are usually installed directly in high pressure pipelines with thread connections and are connected in the electromagnetic clutch circuit. The structure is similar to the normally open type high pressure switch, When the refrigerant pressure is normal, the moving contact turn on the compressor electromagnetic Clutch Circuit; On the contrary,The low pressure switch will turn off Electromagnetic Clutch Circuit to stop the compressor when it’s exhaust refrigerant pressure is too low.
In addition, when the ambient temperature is too low, the temperature and pressure of the refrigerant is also reduced. For example, when the ambient temperature is below 10 °c, the refrigerant pressure is 0.423 MPA, the low-pressure switch is cutting off and the compressor stops running, thus reducing power consumption and saving energy.
3:Working principle of double pressure switch
The new type of air conditioning refrigeration system is a combination of high and low pressure switches into a dual pressure switch, which is installed on the drying bottle, thus reducing the number of pressure switches and interfaces, and reducing the possibility of refrigerant leakage.
When the pressure of refrigerant is normal, the pressure is kept between 0.423 ~ 2.75 MPA, the metal membrane is in the equilibrium position, the high-pressure contacts 14,15 and the low-pressure contacts 1,2,6,7 are closed, current comes out from 6,7 contacts to high pressure contacts 14,15 and then to 1,2 contacts ;When the refrigeration pressure drops to 0.423 MPA, the spring pressure will be greater than the refrigerant pressure, the low-pressure contacts 1,2 and 6,7 disengage, the current is interrupted immediately, the compressor stops running;When the pressure is higher than 2.75 MPA, the refrigerant pressure continues to press the metal diaphragm upward, pushing the whole device up to the top dead center, pushing the top pin 12 to separate the high-pressure moving contact 14 from the high-pressure static contact 15, and disconnecting the clutch circuit, the compressor stops running;When the high pressure side is less than 2.17 MPA, the metal diaphragm will return to its normal position and the compressor will start running again.
4:Working principle of triple pressure switch
The triple pressure switch consists of a double pressure switch (high pressure switch, low pressure switch) and a medium pressure switch, which is more compact. The triple pressure switch is installed in the high-pressure pipeline. When the pressure is too high or too low, the double pressure switch controls the compressor to stop and running. When the refrigerant pressure reaches a certain intermediate value, the medium pressure switch will control the condenser fan circuit.
