Taking the single-screw air compressor as an example to illustrate the working principle of air compressors, the working process of a screw air compressor is divided into four stages: suction, sealing and delivery, compression, and exhaust. When the screw rotates inside the housing, the teeth of the screw mesh with the tooth grooves of the housing. Air is drawn in through the inlet, along with oil. Due to the rotation of the meshing surfaces, the ingested air and oil are sealed and delivered towards the exhaust port. During the delivery process, the meshing gap between the teeth gradually narrows, and the air and oil are compressed. When the meshing surfaces rotate to the exhaust port of the housing, the higher-pressure mixture of air and oil is discharged from the machine. By using a frequency converter, the exhaust volume can be changed by adjusting the speed of the screw rotor. When the air consumption changes, the frequency converter adjusts the speed to regulate the exhaust volume of the air compressor, achieving a constant exhaust pressure and saving energy.
In the air compressor control system, a pressure sensor installed on the outlet pipe at the rear end of the air compressor is used to control the pressure of the air compressor. When the air compressor starts, the loading solenoid valve is closed, the loading cylinder does not operate, and the frequency converter drives the motor to run without load. After a period of time (which can be set arbitrarily by the controller, set to 10S here), the loading solenoid valve opens, and the air compressor runs with load. After the air compressor starts running, if the air consumption of the rear-end equipment is large and the pressure of the compressed air in the gas storage tank and the rear-end pipeline does not reach the upper pressure limit, the controller will actuate the loading valve, open the air inlet, and the motor runs with load, continuously generating compressed air to the rear-end pipeline. If the rear-end air-consuming equipment stops using air, the pressure of the compressed air in the rear-end pipeline and gas storage tank gradually increases. When it reaches the set upper pressure limit, the pressure sensor sends an unloading signal, the loading solenoid valve stops working, the air inlet filter closes, and the motor runs without load.
When the air compressor operates continuously, the temperature of the compressor body will rise.
When the temperature reaches a certain level, which is set to 80℃ in this system (the controllerc can be set according to the application environment), the fan starts to operate to reduce the working temperature of the main unit. After the fan operates for a period of time, the temperature of the main unit decreases, and when it falls below 75℃, the fan stops.
Currently, the pressure sensors commonly used in air compressors on the market include pressure transmitters made from SSI chips from SMI in the United States and MLH016BSB01B pressure sensors from Honeywell in the United States! These products are mainly used in air compressors, water treatment equipment, industrial equipment, buildings, HVAC, petroleum, automotive, and other OEM factories.
