Internal gear pump
(2) Internal gear pump
Figure Q shows the structure of high pressure internal gear pump with floating side plate to realize automatic axial clearance compensation. The outer gear 6 of the pump is integrated with the transmission shaft. The axial clearance is automatically compensated by the forward movement of floating side plates 4 and 7 with back pressure (pressure oil chamber). The radial fit clearance between the inner ring 5 and the inner surface of the semicircle support block 14 is driven by the back pressure (from the oil pressure chamber) under the support block. The support block pushes the inner ring, and the inner ring pushes the filler 12 to contact with the tooth top of the outer gear 6, forming a radial seal in the high pressure area, realizing the automatic compensation of the radial clearance. The flexible bearing supports 2 and 8 (the connection with the shell is less than 180 degrees) can also produce corresponding deformation when the pump shaft is stressed and deformed, which reduces the load capacity decline and local wear problems caused by the shaft tilting in the bearing. Sliding bearings 3 and 9 (the outer end is communicated with the oil inlet of the pump) are lubricated and cooled by oil suction type low pressure through the spiral oil groove (the spiral direction is the same as the shaft diameter direction) opened on the inner wall. This kind of pump has high volumetric efficiency and total efficiency, which is suitable for high pressure gear pump (the rated pressure can reach 40MPa at present).
(3) Cycloidal gear pump (rotor pump)
The pump adopts a three piece structure of pump cover, shell and pump cover (Fig. s). The inner rotor 6 is connected with the pump shaft 13 by the flat key 7, and the matching section of the shaft hole is short, so that the inner rotor has a certain self positioning ability. The outer rotor 5 is mounted directly in the housing 2. The eccentricity between the housing and the front and rear end covers and bearing holes of the pump (that is, the eccentricity between the inner and outer rotors) is ensured by the positioning of two cylindrical pins 3. A leakage hole is opened on the rotor shaft and the pump back cover to directly lead out the leakage oil. The pump adopts clearance sealing structure, which is suitable for low pressure gear pump. BB-B cycloidal gear pump belongs to this kind of pump (its maximum working pressure is 2.5MPa, displacement is 4 ~ 125ml / min).
If the cycloidal gear pump wants to be high pressure, it needs to use the end clearance compensation structure, and its working pressure can reach 16MPa.