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Leakage, oil trapping and radial hydraulic pressure imbalance of external gear pumps are the three major problems that affect the performance and life of gear pumps. The structural characteristics of various gear pumps are different because of the adoption of different structural measures to solve these three problems.
leakage. There are three possible leaks in external gear pumps: between the gear end face and the end cover; between the gear tooth top and the inner hole of the gear, and the tooth surface meshing of the two gears.
Among them, the greatest impact on leakage is the axial gap between the gear end face and the end cover. The leakage through the axial gap can account for 75%-80% of the total leakage because the leakage path is short and the leakage area is large. If the axial clearance is too large and the leakage is large, the volumetric efficiency will be reduced; but if the clearance is too small, the mechanical friction loss between the gear end face and the end cover will increase, which will reduce the mechanical efficiency of the pump. Therefore, the axial clearance of the pump must be strictly controlled when designing and manufacturing.
Gear pumps are generally used for construction machinery with unclean working environment and general machine tools with low precision, as well as hydraulic systems with low pressure and large flow.
Advantages of gear pumps:
1) The structure is simple, the manufacturability is better, and the cost is lower.
2) Compared with other types of pumps with the same flow rate, it has a compact structure and a small volume.
3) Good self-priming performance. It can reliably achieve self-priming regardless of high or low speed or even in manual conditions.
4) Large speed range. Because the transmission part and gears of the pump are basically balanced, no large inertial force will be generated at high speeds.
5) The dirt in the oil does not have a serious impact on its work, and it is not easy to be bitten.
1) The structure is simple, the manufacturability is better, and the cost is lower.
2) Compared with other types of pumps with the same flow rate, it has a compact structure and a small volume.
3) Good self-priming performance. It can reliably achieve self-priming regardless of high or low speed or even in manual conditions.
4) Large speed range. Because the transmission part and gears of the pump are basically balanced, no large inertial force will be generated at high speeds.
5) The dirt in the oil does not have a serious impact on its work, and it is not easy to be bitten.
