Structure of water pump

[Charlie Duan]

Structure of water pump
 
The water pump used in automobile engine is centrifugal water pump, which consists of shell, impeller, bearing, pump shaft, water seal and transmission belt wheel.
 
(1) water pump housing is made of cast iron or cast aluminum.
The wall of cast iron case is thick and its quality is large. With the improvement of the requirement of engine lightweight, only some large engines of commercial cars are still using the pump of cast iron case.
Many cast iron cases also have some water channels and thermostat installation rooms, which further increase the weight of the case.
Most water pumps in cars use cast aluminum shells, and the size of the shells is getting smaller, many of the shells no longer have the function of water channels.
(2) the impeller of the impeller pump is made of metal or engineering plastics, such as cast iron. The impeller is made of semi-circular arc, double circular arc or multi-circular arc blades that bend backwards.
Pump impeller made of cast iron is of high quality, but its mechanical strength is high.
The plastic impeller is easy to realize miniaturization and lightweight, and has good corrosion resistance and easy shape processing. Therefore, more and more car engine pumps use plastic impeller.
                 
 
(3) bearing water pump bearing is an important part of water pump, and the failure of a considerable part of water pump is caused by the damage of water pump bearing.
As the engine gradually develops towards high power, the pump bearing needs to have higher thermal stability, greater bearing capacity and better sealing, so some automobile pumps use axial bearing.
Shaft bearing is actually a kind of double supported bearing with simplified structure. Two supporting bearings have no inner ring. The raceway of the rolling body is directly processed on the pump shaft.
Under the same bearing capacity, the size of shaft bearing is smaller than that of general type bearing.
Under the condition of the same size, the bearing capacity of shaft bearing is greater than that of general type bearing.
 
(4) pump shaft pump shaft is generally made of forged steel.
The pump impeller is installed on one end of the pump shaft, which is supported on the pump housing by bearing.
The other end of the pump shaft is equipped with a transmission belt wheel, which is driven by the engine crankshaft through toothed tape or v-shaped tape.
 
(5) water seal is used to seal the cooling fluid so as to avoid leakage. Meanwhile, the cooling fluid is separated from the pump bearing to protect the bearing.
At present, two-layer ceramic water seal has been widely used in water pumps. Two ceramic water seals installed on the same axis are pressed together by a spiral spring.
Compared with rubber water seal, ceramic water seal is more wear-resistant and has a longer service life, but it is also prone to abrasion by hard particles in the cooling fluid.
Although the processing of water seal has been improved continuously, water seal damage caused water pump leakage is still the main reason for water pump damage.
 
(6) according to the tooth shape of the belt, the belt wheel can be divided into toothed belt wheel and v-shaped belt wheel.
With less and less transmission tape on the engine, more and more pumps share one toothed belt drive with generators, air conditioning compressors, steering pumps, etc. Therefore, more and more toothed transmission belt wheels are added.