At present, there are several lubrication methods for three gear oil pumps: using high-pressure oil leakage for lubrication; High pressure lubrication with continuous or pulsed oil supply to bearings; High pressure lubrication using the reduction of trapped oil volume to pulse supply oil to bearings

 

In general, the correct selection of bearing lubrication method determines the conditions and service life of the bearings in the triple gear oil pump, so it is also a very important part of gear pump design. At present, there are several lubrication methods for three gear oil pumps: using high-pressure oil leakage for lubrication; High pressure lubrication with continuous or pulsed oil supply to bearings; Using the reduction of trapped oil volume to provide high-pressure lubrication to the bearings through pulse oil supply; Directly introducing high-pressure oil into the bearing hole to achieve high-pressure lubrication at the load-bearing point; Utilize the vacuum suction and low-pressure self-priming lubrication formed when the trapped oil volume expands; Spiral oil discharge or oil suction low-pressure lubrication and low-pressure lubrication using auxiliary pump oil supply.

The first lubrication method is generally applied to lubrication methods such as rolling bearings that require low oil cleanliness and insensitive working oil temperature. The second to fourth lubrication methods use high-pressure oil for lubrication, which loses some high-pressure oil and reduces the volumetric efficiency of the gear oil pump. The last two lubrication methods, one of which reduces the bearing capacity of the bearing bearing surface, and the other is not adopted due to its complex structure and high cost. The vacuum suction low-pressure self-priming lubrication formed by expanding the trapped oil volume is widely used for lubrication of rolling and sliding bearings in triple gear oil pumps due to its simple structure, low manufacturing cost, and high comprehensive performance.

 

By utilizing the vacuum suction and low-pressure self-priming lubrication formed when the trapped oil volume expands, there is a large oil passage connected to the low-pressure area outside the bearing, which can make the pressure outside the bearing the same as that in the low-pressure area. Due to the use of DU bearings, a lubricating oil groove needs to be designed axially on the non load bearing surface of the bearing inner hole, and a lubricating oil groove needs to be formed by chamfering the inner hole of the side plate to ensure smooth passage of lubricating oil and stable oil storage.

 

The low-pressure area on the inner side of the side plate is designed with a rectangular elongated groove, which is connected to the lubricating oil grooves of the two bearing holes. When the gear rotates, due to the expansion of the trapped oil volume, a vacuum is first formed at the rectangular groove, which creates an instantaneous pressure difference at both ends of the bearing. As a result, a small part of the oil in the low-pressure area enters the axial oil groove of the bearing hole along the designed oil path. At this time, the oil can lubricate and cool the bearing well. Then, the oil passes through the oil collection groove and the rectangular long groove in sequence, and finally fills the expanded inter tooth volume, thus forming a complete lubrication system.

 

The lubrication method used in the triple gear oil pump has many advantages: because the oil temperature in the low-pressure area is relatively low, it is more conducive to the formation of a pressure bearing oil film in the sliding bearing, and the low-temperature oil can take away most of the bearing heat, playing an excellent role in bearing lubrication and cooling. From this, it can be seen that compared with other lubrication methods, this lubrication method not only has a simple structure and low losses, but also increases the volumetric efficiency of the three gear oil pump.

 

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