How does a Rexroth vane pump work?

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Previously, Autosys Hydraulics explained to you the working principle of Rexroth piston pumps. Here, Autos continues to explain to you another type of structure from the Rexroth brand: the working principle of Rexroth vane pumps. 　　As the rotor of the Rexroth vane pump rotates, the vanes, under the influence of centrifugal force and pressure oil, press their tips tightly against the inner surface of the stator. In this way, the working volume formed by the two blades together with the inner surfaces of the rotor and stator draws in oil from a small volume to a larger one, and then discharges the oil from a large volume back to a smaller one; one complete rotation of the blades results in one cycle of oil intake and discharge. 　　I. Working principle of the single-acting Rexroth vane pump A Rexroth pump is composed of components such as the rotor 1, stator 2, vanes 3, oil distribution plate, and end caps. The inner surface of the stator is a cylindrical hole. There is eccentricity between the rotor and the stator. The blades can slide freely within the grooves of the rotor. Under the effect of the centrifugal force generated by the rotation of the rotor and the pressure oil supplied to the base of the blades, the top portions of these blades press against the inner surface of the stator. As a result, sealed working chambers are formed between adjacent blades, as well as between the oil distribution plate, the stator, and the rotor. When the rotor rotates counterclockwise, the blades on the right side of the diagram extend outward, causing the volume of the sealed working chamber to increase gradually and a vacuum to be created; as a result, oil is drawn in through the oil suction port 6 and the openings on the oil distribution plate 5. And on the left side of the graph. The Rexroth vane retracts inward, causing the volume of the sealing chamber to decrease gradually. The oil in the sealing chamber is forced out through another window in the oil distribution plate and port 1, and then sent to the system. In this type of pump, the rotor rotates once, drawing in oil and discharging it once each, which is why it is called a single-acting pump. The rotor is subjected to radial hydraulic unbalanced forces, which is why it is also known as an unbalanced pump; its bearing loads are high. By changing the eccentricity between the stator and the rotor, the displacement of the pump can be altered; therefore, such pumps are all variable-displacement pumps. 　　II. Working principle of the double-acting Rexroth vane pump Its working principle is similar to that of a single-acting vane pump; the difference lies in the fact that the stator surface consists of eight sections: two long-radius arcs, two short-radius arcs, and four transition curves. Moreover, the stator and the rotor are concentric. With the rotor rotating in a clockwise direction as shown, the volume of the sealed working chamber increases gradually at the top left and bottom right corners, which are the oil suction areas, while it decreases gradually at the bottom left and top right corners, which are the oil compression areas ； There is an oil-sealing area between the oil suction area and the oil compression area, separating them. With each rotation of the rotor in this type of pump, each sealing chamber performs suction and compression actions twice, which is why it is called a double-acting vane pump. The two suction areas and the two discharge areas of the pump are radially symmetric, and the hydraulic pressures acting on the rotor are radially balanced; hence it is also known as a balanced vane pump. 　　The instantaneous flow rate of a double-acting Rexroth vane pump is pulsating, and the pulsation rate is low when the number of vanes is a multiple of 4. For this reason, the number of vanes in double-acting vane pumps is usually 12 or 16. 　　In fact, it’s not only the working principle of Rexroth vane pumps that is like this; the working principles of vane pumps from other brands are also largely similar to those of Rexroth vane pumps. If there is a chance in the future, I will explain to you the principles of other types of vane pumps as well. You can also visit Aotuoshi’s official website for more detailed information: http://www.aotuoshi.com/