Through shaft axial piston pump
c. Variable displacement pump with auxiliary pump figure B shows the structure of through shaft variable displacement axial piston pump with auxiliary pump. The back end cover of the main pump of the pump is equipped with an auxiliary pump 11, which is used to control the oil replenishment of the variable mechanism and system. The variable cylinder 12 is horizontally arranged perpendicular to the axis of the transmission shaft 1. The bracket type swash plate 3 supported on the semicircular cylindrical roller bearing 2 is adopted. The spherical valve plate is used to distribute the flow. The ball hinge return structure is used by the spring force of the disc spring 4. The axis of the piston cylinder hole is inclined to the center line of the pump transmission shaft. The advantage is that because of the centrifugal force, the plunger group has the component force extending outward from the cylinder bore, which makes it rely on the inclined plate, but it is inconvenient to process. The pump has compact structure and is used for hydraulic pump of closed system. A4V series through shaft pump is this kind of structure. It has many variable ways. The maximum pressure of main pump is 45MPa, and that of auxiliary pump is 4MPa. Its physical shape and hydraulic principle are shown in Figure C.
d. Figure D shows the structure of through shaft variable axial piston series double pump with make-up pump. The gear type oil replenishing pump 15 with spline shaft extension is inserted into the spline hole of the rear shaft and works with the main pump to replenish oil in the system. The two variable cylinders 8 and 11 are horizontally arranged parallel to the axis of the transmission shaft 1 and the rear shaft 14, and the swash plate 12 is controlled by the variable lever 7 to change its inclination angle to realize variable control; the spherical valve plate 21 is used to distribute the flow; the dispersed springs 19, 22 and the ball hinge 17 constitute the return mechanism. The pump has compact structure and high power density, which is used for hydraulic pump of excavator system. Figure e shows the hydraulic schematic diagram of the pump.