Briefly describe the main difference between the double-acting vane pump and the vane motor

The vane pump is also a positive displacement pump. It uses the rotation of the rotor and the expansion and contraction of the blades in the rotor chute to complete its closed volume change. Figure 3-6 shows the working principle of a single-acting vane pump. It is mainly composed of parts such as drive shaft, rotor, blade, stator, oil distribution plate and pump body. The rotor has a uniformly distributed slot in the radial direction, and the slot is provided with slidable blades, and the rotor and the stator are separated by an eccentricity e. The top end of each blade abuts against the inner surface of the stator such that a closed cavity is formed between the two blades. This closed cavity changes as the rotor rotates counterclockwise as the drive shaft drives. When turning to the situation shown in Figure 3-5, the volume between adjacent blades on the right side gradually increases to form a vacuum, and the oil is sucked from the fuel tank through the suction pipe and the lower oil window (suction window) of the oil distribution plate. . In the left half, two phases. Figure 3-5 Working principle of the vane pump The closed cavity between the adjacent vanes is gradually reduced, and the oil is pressed to obtain the pressure energy. The oil pressure pipe flows to the working oil passage through the oil pressure window of the oil distribution plate.

 

Changing the eccentricity e can change the oil delivery of the oil pump. The left half of the oil pump (pressure zone) is the high pressure zone and the right half (oil suction zone) is the low pressure zone, so the rotor is subjected to a radial imbalance. Therefore, the working pressure of this oil pump should not be too high. In order to improve the stress and increase the pressure, a double-acting vane pump can be used.

The inner surface of the stator is waist-shaped, and the stator and the rotor are concentric. An oil distribution plate is also installed at the two ends of the stator. What is not relevant to the single-acting type is that there are four oil distribution windows symmetrically on each of the distribution trays, that is, two oil suction windows and two pressure oil windows. When the rotor rotates, the volume between adjacent two blades continuously changes periodically as the shape of the stator changes. In this way, each time one revolution, the secondary oil absorption and oil pressure process is completed. The double-acting vane pump has a higher output pressure than the single-acting vane pump because the rotor is balanced. At present, it is generally possible to hit 0-105 kg / cm.

Since the closed cavity of the vane pump is composed of two parts, such as two blades, a stator, a rotor and two oil distribution plates, the leakage is more, and the working pressure is not as high as the plunger pump. Moreover, due to the increase in the number of relatively sliding parts, there is a certain requirement for the degree of cleanliness of the oil. Otherwise, it is easy to produce a "bite" phenomenon.

But the vane pump also has an advantage that cannot be ignored: smooth operation. From the point of view of the theory, the amount of oil pressed by each closed cavity in the vane pump at each moment of rotation is substantially the same. Therefore, the output flow and pressure are relatively uniform. While the plunger pump is rotating, the movement of the plunger is not uniform, but it is fast and slow, so the amount of oil that is pressed out at each moment is also different, so that the total output flow and pressure of the pump are also changing. . This creates a pulsation of flow and pressure. The oil in the working line is not evenly stabilized. This is where the plunger pump is not as good as the vane pump.

The vane pump has a smooth running flow, uniform flow rate, and can easily obtain a working pressure of 25 to 70 kg and is cheaper than a plunger pump. Therefore, it is currently widely used in medium and low pressure hydraulic systems, such as combination machine tools, grinding machines, hydraulic lathes, hydraulic planers, injection molding machines, robots, and the like.