The internal control variable vane pump is a form of va […]
The internal control variable vane pump is a form of variable vane pump whose variable operating force comes from its own discharge pressure. So what is the working principle of it? The following is an introduction to the working principle of the internal control variable vane pump.
The stator ring is movable in a horizontal direction under the support of its top rolling bearing. The arrangement of the suction and discharge windows of the pump distribution plate and the direction of movement of the stator have an off-angle of 0. The force of the discharge pressure on the stator ring can be decomposed into a component F1 in the vertical direction and a horizontal component F2 in the same direction as the direction of movement of the stator. F2 overcomes the compression force of the adjusting spring, forms an adjusting force, and pushes the stator ring to move. When the adjustment force R formed by the working pressure of the pump is less than the spring preload, the eccentricity e of the stator to the rotor is limited by the maximum flow adjustment screw and is maintained at the maximum value. Therefore, the flow rate of the pump is basically the same, only because the leakage is slightly reduced, as shown by AB in Figure 7-2. When the working pressure of the pump exceeds P. After the value, the adjustment force F2 is greater than the spring preload. As the working pressure increases, the adjustment force F increases, and the spring force is moved to decrease the direction of the eccentricity of the stator ring, and the displacement of the pump begins to decrease. When the working pressure reaches P, the theoretical flow of the pump corresponding to the eccentricity of the stator ring is equal to its leakage, and the actual output flow of the pump is zero. At this point the pump's output pressure is at its maximum.
Increasing the preload of the adjustment spring can cause the curved segment of Figure 7-2 to move parallel to the right. Reducing the spring rate changes the slope of the BC section to make it steeper. Adjust the maximum flow adjustment screw to adjust the position of the curve point A (ie the maximum flow rate). This variable pump is called a pressure limiting (also known as pressure feedback or pressure compensated) pump.
The internal control variable vane pump has a simple structure and is easy to adjust. However, due to the deflection of the distribution plate, the effective displacement of the pump is reduced and the flow pulsation is increased. Its dynamic adjustment characteristics are also relatively poor, so it is generally only used on economical small-size pumps. For large and medium-sized variable vane pumps with high performance requirements, the characteristic section of the pressure-limiting variable vane pump adopts an external control type.