KRACHT fuel separator supply pump KF6/500H1XBP0A7DP2

Oil entrapment phenomenon

To ensure smooth operation of the gear pump, the meshing overlap of the gears must be greater than 1. Therefore, there are always two pairs of gears meshing simultaneously, and a portion of the oil is trapped between the enclosed chambers formed by the two pairs of gear teeth. This closed chamber gradually decreases with the rotation of the gear, and then gradually increases again. The reduction in the volume of the enclosed chamber will cause the trapped oil to be compressed, resulting in high pressure and extrusion from the gaps, causing the oil to heat up and causing additional loads on the components; The increase in the volume of the enclosed chamber causes local vacuum, which separates the dissolved gases in the oil and produces cavitation. These will generate strong vibrations and noise, which is the phenomenon of trapped oil in gear pumps.

KRACHT fuel separator supply pump KF6/500H1XBP0A7DP2harm

When the radial unbalance force is large, it can cause the shaft to bend, the tooth tip to come into contact with the housing, and accelerate the wear of the bearing, reducing its lifespan.

KRACHT fuel separator supply pump KF6/500H1XBP0A7DP2Elimination methods

The method to eliminate trapped oil is usually to open unloading slots on both sides of the cover plate, so that when the volume of the closed chamber decreases, it is connected to the oil pressure chamber through the unloading slot on the left, and when the volume increases, it is connected to the oil suction chamber through the unloading slot on the right.

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Feasible circuit for improving the performance of gear oil pump

Due to the structural limitations of fixed displacement, gear pumps are generally considered to be only suitable for use as constant flow hydraulic sources.

Installing a control valve directly on the pump can eliminate the pipeline between the pump and the directional valve, thereby controlling costs. Fewer pipe fittings and connectors can reduce leakage and improve work reliability. Moreover, installing valves on the pump itself can reduce the circulating pressure of the circuit and improve its working performance. Here are some circuits that can improve the basic functions of gear pumps, some of which have been proven feasible in practice, while others are innovative research.

Unloading circuit

The unloading components will be combined with high flow pumps and low-power single pumps. Due to the structural limitations of fixed displacement, it is generally believed that gear pumps can only be used as constant flow hydraulic sources for liquid from two gear oil pumps Due to the structural limitations of fixed displacement, gear oil pumps are generally considered to be only suitable for use as constant flow hydraulic sources. However, the combination valve scheme of accessories and threaded connections is effective in improving its functionality, reducing system costs, and enhancing system reliability. Therefore, the performance of gear oil pumps can approach that of expensive and complex plunger pumps. At this point, the high flow pump circulates the flow from its outlet to its inlet, thereby reducing the pump's output flow to the system, that is, reducing the pump's power to slightly higher than the required value for high-pressure operation. The percentage of flow reduction depends on the ratio of unloaded displacement to total displacement at this time. The combination or threaded connection of unloading valves reduces or even eliminates possible leaks in pipelines, ducts, accessories, and other components.

Simple unloading of components is manually operated. The spring opens or closes the unloading valve, and when a control signal is given to the valve, the on/off state of the valve is easily switched. Leverage or other mechanical mechanisms are a simple way to operate this type of valve.