What are the Structural Characteristics of Gear Pump?

Structural Characteristics

1. Simple structure and cheap price;
2. Low work requirements and wide application;
3. The end cover and the groove between the teeth of the gear constitute a lot of fixed sealing chamber, which can only be used as a quantitative pump.

Gear adopts the international advanced level of 90's new technology - double arc sine curve tooth arc. Compared with involute gear, the most prominent advantage is that the tooth profile surface of the gear meshing process has no relative sliding, so the tooth surface has no wear, running balance, no trapped liquid phenomenon, low noise, long life and high efficiency. The pump gets rid of the shackles of traditional design, which makes the gear pump enter a new field in design, production and use.

The pump is equipped with a differential pressure safety valve as overload protection, the total return pressure of the safety valve is 1.5 times the rated discharge pressure of the pump. It can also be adjusted in the allowable discharge pressure range according to actual needs. But this safety valve can not be used as a long-term reducing valve work, reducing valve can be installed when necessary.

The pump shaft end seal design is of two forms, one is mechanical seal, the other is packing seal, can be determined according to the specific use situation and user requirements.

Classification of Pumps

Gear pump belongs to hydraulic parts, as far as the core components of gear, mainly by the common normal line gear pump and arc gear pump. Common normal gear pump transmission containing impurities than the circular arc gear pump to durable, and circular arc gear pump special structure, transport clean media, low noise, long life, each has its own advantages.

Working Characteristics

Advantages: simple and compact structure, small volume, light weight, good technology, cheap price, strong self-suction, not sensitive to oil pollution, large speed range, impact load resistance, easy maintenance, reliable work.

Disadvantages: radial force imbalance, flow pulsation, noise, low efficiency, poor interchangeability of parts, wear is not easy to repair, can not be used for variable pump.

Oil trapping Phenomenon

Reason: hydraulic oil in the process of running involute gear pump, because the closed volume at the intersection of the gear changes with time, often a part of the hydraulic oil is sealed between the teeth, called trapped oil phenomenon, because the hydraulic oil is incompressible will make the external gear produce great vibration and noise, affecting the normal work of the system.

Measures: Open the unloading groove on the front and rear cover plates or floating shaft bushing, and the principle of opening the unloading groove: the spacing between the two grooves is the minimum closed volume, so that the closed volume is communicated with the pressure oil chamber from large to small, and the closed volume is communicated with the oil suction chamber from small to large.

Leakage Phenomenon

The leakage of gear pump is large. When the external meshing gear is running, the leakage path has the following three points: one is the gear top gap, the second is the measurement gap, and the third is the meshing gap.

The end-face clearance leakage is large, accounting for 80%-85% of the total leakage. When the pressure increases, the former will not change, but the deflection of the latter increases, which is the main reason for the leakage of external gear pump. The volume efficiency is low, so it is not suitable for high pressure pump.

Solution: End clearance compensation adopts static pressure balance measures, adding a compensation part between the gear and cover plate, such as floating sleeve and floating side plate.

Unbalanced Force Phenomenon

The right side is the oil pressure chamber, the left side is the oil suction chamber, the pressure of the two chambers is unbalanced; In addition, the pressure of the oil chamber decreases due to the leakage of the tooth top. Two unbalanced pressure acting on the gear and shaft radial unbalance pressure, the higher the oil pressure, the greater the force, accelerate bearing wear, reduce bearing life, make the shaft bending, increase the tooth top and shaft hole wear.

Prevention measures: use pressure balancing tank or reduce the pressure oil chamber.