Air compressors for automobiles are also commonly known as air pumps or small engines. They are an assembly of more than 100 parts. Automotive air compressors are mainly used in commercial vehicles, construction machinery, agricultural machinery and other fields, and are important parts of diesel engines. The main function is to provide power and air source for these machines to achieve the functions of vehicle braking and opening and closing of doors and windows. Air compressors are divided into air-cooled and water-cooled according to the cooling method. The failure modes of air compressors mainly include oil leakage, no air pumping, and slow air pumping. Through statistical analysis of market failure modes, water-cooled air compressors have lower exhaust temperature and failure rates than air-cooled air compressors.

The cooling principle of an air compressor with water-cooled structure is that the upper water pump of the diesel engine runs, and the cooling water flows into the internal water channel through the water inlet of the air compressor, and then flows out from the water outlet. Relying on the circulating flow of cooling water to take away the heat generated when the air compressor is working, so as to reduce the temperature of the air compressor itself and the exhaust gas. At the same time, due to the decrease in exhaust temperature, it also protects the vehicle braking system.

Water-cooled air compressor for car are divided into three types according to the water cavity structure: the cylinder head is water-cooled with a water cavity structure. The cylinder head and valve plate are water-cooled with water cavity structure. The cylinder head, valve plate, and cylinder body are all water-cooled with water chambers. Among them, the cooling effect of the air compressor with a water-cooled structure is the best. At present, there are many types of all water-cooled air compressors on the market, partly due to the unreasonable design, the cooling effect is not obvious, and what is more, the cooling effect of water cooling is worse than that of air cooling. The following focuses on the full water-cooled air compressor with good cooling effect.

1. The cooling water flow of the air compressor depends on the displacement. The larger the displacement, the higher the temperature, and the greater the heat dissipation requirements. The minimum cross-sectional area of ​​the water passage and the larger water flow requirements during the design. The direction of water flow is preferably unidirectional flow circulation. The working flow direction of the cooling water is from bottom to top, and there should be no dead water area in the water cavity when the water is flowing. When the machine is stopped, the cooling water flows out naturally from top to bottom, and the natural flowing water brings out the impurities inside the air compressor.

2. Cooling cycle

The cooling water of the all-water-cooled air compressor enters from the water inlet of the cylinder body, and forms a surface surrounding the inner hole in the cylinder body to dissipate heat. The cooling water then flows into the valve plate, and the cooling water surface covering the cylinder bore is formed in the inner cavity of the valve plate to dissipate heat. The cooling water flows into the cylinder head and forms a cooling water surface covering the exhaust gas to dissipate heat in the inner cavity of the cylinder head. The cooling water finally flows out from the water outlet of the cylinder head. This cooling method is characterized by the formation of surface cooling at the heat generated by the friction between the piston and the cylinder bore, the formation of surface cooling inside the valve plate when the top of the piston is exhausted, and the formation of surface cooling in the exhaust cavity of the cylinder head. The heat generated when the piston assembly is pumped is taken away, the carbon deposits on the exhaust valve plate and the exhaust cavity due to high temperature are reduced, and the occurrence of failures such as slow pumping and carbon deposits of the air compressor is reduced. The temperature of the piston assembly, cylinder bore, etc. of the working parts of the air compressor is reduced, and other faults such as oil blow-by caused by thermal deformation of the cylinder bore are reduced, and the service life of the air compressor is improved.

3. Shutdown protection

The remaining cooling water in the cooling system water circuit flows in through the cylinder head water port of the air compressor during shutdown, and flows out through the cylinder head water cavity, the valve plate water cavity, the cylinder water cavity, and the cylinder water inlet. The remaining water in the air compressor cooling channel will form scale. Scale and impurities will cause blockage of the water outlet and water channel, block the water circulation, and reduce the cooling effect. Since the water flow of the all-water-cooled air compressor flows out naturally from top to bottom, it is easy to remove the remaining cooling water and impurities inside.