Gear pump classification, characteristics and applications
1. Gear pump classification
Gear pump generally according to the configuration of the gear pair is divided into external mesh type (external gear pump) and internal mesh type (internal gear pump) two, the internal gear pump includes a cycloid gear pump specially marked tooth shape.
2. Characteristics of gear pump
The advantages of external gear pump are simple structure, light weight, small size, easy processing and manufacturing, low cost, reliable work, convenient maintenance, strong self-priming ability, not sensitive to oil pollution, can be widely used in pressure requirements are not high occasions, such as grinder, honing machine tool in the middle and low pressure. Its disadvantage is that the internal leakage is larger, the bearing under unbalanced force, serious wear and tear, and the flow pulsation and the larger the flow pulsation of the pump noise has a great influence on the normal use of the pump, it will cause the pressure pulsation of hydraulic system so that the pipe, valve and other components produce vibration and noise, at the same time, also affect the movement stability of working parts, especially for precision machine tool hydraulic system more Leon. Therefore, special attention should be paid when using it.
The advantages of internal gear pump are: compact structure, small size, light weight; Because the internal and external gear steering is the same, the relative slip speed is small, so the wear is small, the life is long, the flow pulsation and noise are much smaller than the external gear pump. The disadvantage of internal gear pump is that the tooth shape is complex, the processing is complex and the precision is high, so the manufacturing cost is high.
3. Application of gear pump
In all kinds of existing hydraulic pumps, gear pump working pressure is second only to the piston pump, together with their small size, low price, so it is widely used in mobile equipment and vehicles as hydraulic work system and steering system pressure oil source. On the other hand, due to the gear pump speed and displacement range are large, oil absorption capacity is strong, the cost is low, but also commonly used as a variety of hydraulic system auxiliary pump, for example, the closed loop rehydration pump, pilot control system in the low pressure control oil source. But in the field of fixed hydraulic equipment because of the external gear pump flow pulsation is large, high noise and limited life, as the main pump has become more and more unpopular, the use is limited to run under low pressure as an auxiliary pump and prepressure pump. On the contrary, the internal gear pump is the lowest noise, one of the best comprehensive performance of the hydraulic pump. In addition to the price is slightly higher this point, in other aspects are almost superior to the external gear pump. The development of modern manufacturing technology will greatly reduce the cost gap between internal and external gear pumps, and in the industrial field, the increasing popularity of speed regulating electric transmission technology, to a large extent, to make up for the shortcomings of the internal gear pump itself can not be variable. It can be expected that the future internal gear pump in fixed and mobile equipment applications will be rapidly expanded. In hydraulic engineering, cycloidal gear pump with small volume, low price and strong self-priming ability advantages, is widely integrated in the back cover of closed oil through shaft piston pump, as a low pressure rehydration pump (to provide control pressure) use, sometimes also used as the main pump of some machine tool hydraulic system. This kind of pump can realize one-way oil supply, and has nothing to do with the input steering, this performance for some vehicles or walking machinery needs to use wheel drive emergency steering, braking system has special significance. Cycloid gear pair with fixed pin gear ring (Olbit meshing pair) has a large unit volume displacement, but because of its low permitted speed, it is mostly used as a low speed hydraulic motor, only used as a metering pump in the hydraulic steering system for vehicles. When the power oil source in the system fails, the pump can be manually used as an emergency oil source.
