A spiral gear pump

At present, the product application of gear pump has been very wide.The structure of gear pump generally includes two spur involute gears, pump body and front and rear covers, which can form a closed space.When a pair of gears engage and rotate with each other, the space volume on the disengaging side of the gear will gradually increase, creating a vacuum environment, and the space volume on the engaging side of the gear will gradually decrease, resulting in liquid squeezing into the pipeline until it reaches the actuating mechanism [1-2].But when a pair of spur involute gears engage, the engagement track is a short, discontinuous line.As a result, the gear drive will be uneven and the pumped hydraulic fluid will pulsate.In order to guarantee the smoothness of gear drive, it is urgent to solve the problems of gear drive and oil trap of gear pump.

The figure shows the structure of a conventional gear pump.The parameters of the two meshing gears are identical.Once the gear pump is designed, the center distance between the two gears is fixed.In the direction shown in Figure 1, the track of the gear engagement point during the rotation of the active gear is a straight line between K’-K.Therefore, the intermittent, recurring motion of the meshing points between K’-K (as shown in Fig. 2) will cause unevenness in the gear drive and pulsation in the hydraulic fluid pressed out [3].During the meshing process, the two sides of the teeth, the top of the teeth and the root of the teeth will form a closed small area, resulting in oil trapping.Causes uneven pressure and noise.If the top, side and root of the gear are designed as conjugate curves, they are always in meshing state and there is no backlash on the side of the gear, so there will be no oil trapping and transmission roughness.

Through the design and Research on the curve of a helical gear pump, the design method of the gear of the gear pump is given, and a set of conjugate curves with full engagement are obtained. After the curve modification and optimization, a gear pump gear can be obtained by increasing the helical angle with the curve. After assembly and test, this gear pump can effectively solve the oil trap problem of the gear pump.It can greatly reduce the pulsation of gear pump and reduce the noise of gear pump. It is of great significance to the design and research of current hydraulic system to reduce noise.