A、 Structural basis for sealing volume of hydraulic vane pump

The formation of the sealing volume of a vane pump depends on three core components:

1. Inner curve of stator: The inner surface of the stator is a transition curve (such as an equal acceleration curve), and the difference between the long radius R and the short radius r determines the eccentricity e (e=R-r). A sample from a certain manufacturer shows that the single rotation displacement can reach 25mL/rev when e=3mm.

2. Rotor and blades: The rotor has radial grooves, and the blades slide along the grooves under the action of centrifugal force and hydraulic pressure. Taking a certain model of double acting vane pump as an example, the blade thickness is usually 2-3mm, and the quantity is 8-12 pieces (according to the Hydraulic Component Design Manual), ensuring that independent chambers are formed between adjacent blades.

3. Distribution plate: The angle of the oil suction and discharge windows on both sides of the distribution plate should strictly match the phase change of the sealing chamber, and the window angle error should be controlled within ± 0.5 ° to avoid pressure shock.

B、 The formation process of dynamic sealing volume of hydraulic vane pump

The periodic variation of sealing volume can be divided into four stages (taking a single acting pump as an example):

1. Volume expansion period: When the blade transitions from a short radius to a long radius, the volume of the cavity increases, forming a vacuum oil absorption. A certain experimental data shows that when the speed is 1500rpm, the pressure in the oil suction chamber can be reduced to below 0.03MPa.

2. Transition closure period: The blade passes through the vertex of the stator curve, and the cavity is isolated from the suction and discharge ports. At this time, the sealing performance depends on the gap between the blade tip and the stator (ideal value is 0.01-0.02mm).

3. Volume compression period: The blades move towards a shorter radius, and the chamber squeezes the oil to the discharge port. If the blade rake angle is designed to be 13 °, it can reduce the risk of blade jamming (refer to ISO 4401 standard).

4. Pressure release period: High pressure oil is discharged through the port plate window, and at the same time, a new set of blades begins the next cycle.

C、 Key parameters affecting sealing performance

According to the SAE J745 test standard, the following parameters need to be controlled with emphasis:

-Working pressure: When the pressure increases from 10MPa to 21MPa, the volumetric efficiency of a regular vane pump will decrease from 95% to 88%

-Blade tip clearance: When it exceeds 0.03mm, the volumetric efficiency decreases by more than 5%

-Oil viscosity: It is recommended to use ISO VG32-46 hydraulic oil. When the viscosity is below 10cSt, internal leakage increases significantly

D、 Engineering optimization direction

1. Structural improvement: The design of the mother and child blades ensures that the high-pressure zone blades are tightly attached to the stator, suitable for working conditions with a pressure of ≥ 25MPa.

2. Material selection: Using tungsten carbide coated blades can reduce wear rate by 60% (data source: Tribology International journal).

3. Thermal compensation design: Adding temperature compensation slots to the distribution plate can offset gap deformation at high temperatures.

The above: Introduction to Hydraulic Ball Valve