Working characteristics of micro small flow pump.

Advantages of micro small flow pump: simple and compact structure, small size, light weight, good workmanship, cheap, strong self-priming force, insensitive to oil pollution, large speed range, able to resist impact loads, easy maintenance, reliable work.

Disadvantages of micro small flow pump: unbalanced radial force, large flow pulsation, high noise, low efficiency, poor interchangeability of parts, not easy to repair after wear, cannot be used as variable pump.

Oil trapping phenomenon.

Cause: hydraulic oil in the involute gear pump operation process, because the gear intersection of the closed volume changes over time, there is often a part of the hydraulic oil is sealed between the teeth, as shown in the figure, known as the trapped oil phenomenon, because the hydraulic oil is not compressible will make the external gears produce great vibration and noise, affecting the normal operation of the system.

Measures: in the front and rear cover or floating sleeve to open the unloading groove, open the principle of unloading groove: two groove spacing for the minimum closed volume, and make the closed volume from large to small with the pressure oil cavity, closed volume from small to large with the suction cavity.

Leakage phenomenon.

micro small flow pump leakage is larger, external gear operation leakage path has the following three points: one for the gear top gap, followed by the measurement gap, the third for the meshing gap.

The end side gap leakage is larger, accounting for 80%-85% of the total leakage, when the pressure increases, the former will not change, but the latter deflection increased greatly, this is the main reason for the leakage of external gear pump, the volume efficiency is low, so it is not suitable for use as a high-pressure pump.

Solution: end face clearance compensation using static pressure balance measures, adding a compensation parts between the gear and cover, such as floating sleeve, floating side plate.

Unbalanced force phenomenon.

The right side is the pressure oil cavity, the left side is the suction oil cavity, the pressure of the two cavities is unbalanced; in addition, the pressure oil cavity is decreasing due to the leakage of the tooth top. The higher the oil pressure, the greater the force, accelerating bearing wear, reducing bearing life, bending the shaft, and increasing the wear of the top of the tooth and the shaft hole.

Preventive measures: the use of pressure balance groove or reduce the pressure oil chamber.

The seal form of micro small flow pump.

1. Mechanical seal

2.Three layers with oil chamber seal

3. Single-layer seal

4. Magnetic seal Each type of seal depends on different inlet pressure and sealing performance