The oil trapped phenomenon of the gear oil pump refers to the phenomenon that during its working process, due to the meshing and rotation of the gears, part of the oil is trapped between the closed chambers surrounded by two pairs of gear teeth, and the volume decreases and increases as the gears rotate, resulting in a series of adverse consequences.

Specific manifestations of the oil trapped phenomenon

The volume of the closed chamber decreases: When the volume of the closed chamber decreases, the trapped oil is squeezed and high pressure is generated, which may cause the oil to be squeezed out of the gap, increase the oil temperature, and increase the additional load on the machine parts.

The volume of the closed chamber increases: When the volume of the closed chamber increases, a local vacuum will be formed, causing the gas dissolved in the oil to separate, resulting in cavitation, which in turn causes strong vibration and noise.

Solutions to oil trapping

The following solutions can be adopted for the oil trapping of gear oil pumps:

Pressure relief groove method:

Two relief grooves are milled on the end covers on both sides of the gear pump, so that when the volume of the trapped oil area decreases, it is connected to the oil pressure chamber, which is convenient for timely oil extrusion and prevents pressure increase; when the volume of the trapped oil area increases, it is connected to the oil suction chamber, which is convenient for timely oil replenishment and prevents vacuum gasification. This method is a commonly used pressure relief method.

Pressure relief hole method:

A relief hole is opened on the floating side plate to alleviate the oil trapping phenomenon. However, it should be noted that the position and size of the relief hole need to be precisely designed to ensure that it can effectively relieve pressure without affecting the normal operation of the pump.

Modified tooth shape method:

Reduce the occurrence of oil trapping by changing the tooth shape of the gear. For example, use a short tooth shape or add some transition tooth shapes in the non-meshing area.

Use helical gears or herringbone gears:

The meshing process of helical gears or herringbone gears is relatively smooth, which can significantly reduce the occurrence of oil trapping. The tooth design of these gears makes the oil flow more smoothly in the closed cavity, reducing the generation of pressure and vacuum.

Choose the right lubricant:

Avoid using oil that is too viscous to reduce the flow resistance of the oil in the closed cavity and reduce the occurrence of oil entrapment.

Check the installation and pipeline of the pump:

Make sure the suction port of the pump is installed correctly to avoid sucking in air or bubbles. At the same time, check whether the inlet pipeline of the pump is blocked or whether the inlet valve of the pump is open to ensure that the oil can enter the pump cavity smoothly.

Adjust the speed and pressure of the pump:

In some cases, increasing the speed of the gear pump or increasing the outlet pressure of the pump can improve the oil entrapment phenomenon. However, it should be noted that this method may be limited by the design and working conditions of the pump.

There are many ways to solve the oil entrapment phenomenon of gear oil pumps, and it is necessary to choose the appropriate solution according to the specific situation. In practical applications, it is also necessary to pay attention to regular inspection and maintenance of the performance and status of the pump to ensure its long-term stable operation.