1) Structural understanding and the role of each component
2) Working principle of swash plate axial piston pump
The cylinder block is connected with the spline on the main shaft, so as to rotate with the main shaft. The plunger assembly is installed inside the cylinder that moves with the swash plate, and the plunger moves from the bottom dead center to the top dead center and moves in the direction of increasing outlet flow. After the hydraulic oil passes through the oil suction port, it flows to the cylinder through the valve plate (oil suction process). During the stroke from the top dead center to the bottom dead center, the plunger always moves in the direction of the reduced oil discharge, so the hydraulic oil is discharged through the oil discharge port (Draining process). The oil displacement changes with the change of the inclination of the swash plate. The hydraulic oil sucked through the cylinder suction port is discharged through the oil discharge port of the distribution plate, and the hydraulic oil sucked through the oil suction port of the outer (inner) ring of the cylinder is discharged through the oil discharge port of the outer (inner) ring of the distribution plate.
3) Distributor
Function: separate the oil suction area (low pressure area) and the oil discharge area (high pressure area), and form a sealed volume with the cylinder block and plunger.
As shown in the figure: the small groove in the red circle is at the starting point of the valve plate, the purpose is to reduce trapped oil.
4) Pump control function
Pump is a variable displacement plunger pump that discharges two kinds of the same flow rate from a cylinder. Although it has a double pump structure, the 3 pump and the pilot pump are connected on the same axis through a coupling sleeve, but the structure is very compact. Because the pump has only one swash plate, the tilt angle is the same. The inclination angle of the pump can change the total flow Q1+Q2. The output power is a constant value, so the product of the outlet pressure and the flow rate is constant, that is (Q1+Q2)X p=P (constant).
Control function of pump
The angle of the swash plate is determined by the discharge pressure of the PI pump and P2 pump, and the force of the power spring is opposite to the direction of the discharge pressure. When the pressure is less than the set load of the power bullet grate A, the swash plate is at the maximum tilt angle position. When the pressure exceeds the set load of the power spring A, the inclination of the swash plate will change to a small angle, and.
It is fixed at a position in equilibrium under the hydraulic oil pressure and the force of the power spring A. When the inclination angle of the swash plate continues to decrease due to the increase in the pressure of the hydraulic oil, the spring B, which has not functioned, begins to function. To overcome the elastic force of the two spring forces, the maximum bottom dead center of the oil pressure must be reached . When the p3 hydraulic oil pushing the servo piston flows in, the control displacement curve will be changed.
5) Pump port description
