Created on：2021-06-02 10:23

# Working principle of vane pump

f. Wear of blade and stator inner surface and Countermeasures Due to the large gradient of vector diameter variation on the inner surface of the stator of double acting vane pump, the blade in the oil suction section is required to have greater radial acceleration to ensure that its outer end is not empty. However, due to the influence of motion friction, the centrifugal force of the blade itself is often unable to meet the requirements, so this kind of pump usually makes the bottom of the blade groove connect with the pump through the annular groove on the valve plate It is connected with the oil pressure chamber of the pump. As shown in Fig. 3-6, the annular groove a is connected with the oil pressure area through the groove (dotted line) on the back of the valve plate. The position of the annular groove corresponds to the bottom of the blade groove of the rotor, so as to introduce high-pressure oil into the bottom of all blade grooves. With the help of hydraulic pressure, the blades located in the oil suction area can quickly extend.

For the pump with higher working pressure, the hydraulic force at the top and bottom of the blade in the pressure area can be basically balanced. However, the hydraulic pressure at the bottom of the blade slot in the oil absorption section is significantly higher than the force required to extend the blade, resulting in the excessive contact stress between the blade and the inner surface of the stator in this section, which increases the friction resistance, decreases the mechanical efficiency, and intensifies the wear of the contact surface (especially near the end of the oil absorption section). In severe cases, the blade will be damaged due to too much tangential resistance at the end The extension of the disc was broken. Therefore, for high-pressure double acting vane pump, it is necessary to compensate the external thrust acting on the bottom of the vane (generally, it is not necessary for medium and low pressure pump).

When the blade is in the oil absorption area, the external thrust F of the pressure oil at the bottom of the blade is 0

F=pA (3-1)

Where P -- oil pressure at blade root;

A -- effective compression area of blade root.

There are two kinds of compensation principles for the external thrust acting on the bottom of the blade: one is to try to reduce the pressure P at the bottom of the blade groove in the oil absorption area to a reasonable value; the other is to use a special blade structure to reduce the effective pressure area a at the bottom of the blade. The internal spring force can also be used to replace the hydraulic pressure to extrapolate the blade. The specific measures are as follows.

i. Figure h shows a vane pump with a set value reducing valve and a floating port plate. The pressure reducing valve 6 attached to the pump reduces the pressure in the pressure chamber of the pump and then leads it to the bottom of the blade groove in the oil suction area, so as to reduce the force of the blade 2 on the stator 1. It is possible for this method to reach the optimal thrust value. But the pressure reducing valve is not only complex and expensive, but also consumes part of the output flow, resulting in the reduction of the volumetric efficiency of the pump; and the simple throttling groove is difficult to fully meet the requirements of pressure distribution, so it has been rarely used at present.