The core components of axial piston pump include cylinder, oil distribution plate, plunger and swash plate. There are many plungers arranged in the cylinder, and the axis of these plungers is parallel to the axis of the drive shaft, hence the name axial piston pump. Unlike traditional reciprocating piston pumps, the plunger of axial piston pump not only reciprocates in the pump cylinder, but also produces relative rotational motion with the swash plate. The spherical end of the plunger is in close contact with the swash plate. The oil distribution plate is provided with high and low pressure moon-shaped grooves, which are separated by partitions to ensure good sealing and are connected to the oil inlet and outlet of the pump. A specific inclination angle is maintained between the axis of the swash plate and the axis of the cylinder.
The working principle of the axial piston pump is as follows: when the motor drives the drive shaft to start rotating, the pump cylinder and the plunger will rotate synchronously. Because there is a certain inclination angle between the swash plate and the cylinder, the plunger head always keeps in contact with the swash plate when it reciprocates in the pump cylinder. Take a single plunger as an example. When it rotates from 0° to 180°, that is, when it reaches the position of the plunger above the swash plate, as the volume of the plunger cylinder gradually increases, the liquid is sucked into the oil cylinder through the oil suction port a of the oil distribution plate.
Changing the angle of the tilting element can adjust the stroke of the plunger in the pump cylinder, thereby controlling the flow of the pump.
When the tilt angle is fixed, the pump is a fixed displacement pump; when the tilt angle is variable, it is called a variable displacement pump.
Axial piston pumps are mainly divided into two types: swash plate type and swash shaft type. In the swash plate pump, there is an inclination angle between the swash plate and the rotating cylinder body. This design allows the plunger to reciprocate in the pump cylinder. The axis of its drive shaft coincides with the axis of the cylinder body, the structure is relatively simple, and the speed is high. However, it should be noted that this structure has strict requirements on working conditions, and the contact part between the end of the plunger and the swash plate often becomes a weak link.
The design of the swash shaft pump is different. The axis of its swash plate is consistent with the axis of the drive shaft. Here, the plunger cylinder body is tilted at an angle relative to the drive shaft, thereby driving the plunger to reciprocate. Flow regulation is achieved by swinging the angle of the piston cylinder, so it is sometimes called the swing cylinder type. Compared with the inclined plate type, this structure works more reliably and has a larger flow rate, but the structure is also more complicated.
Axial piston pumps are widely used in hydraulic transmission systems of machine tools, metallurgy, forging, mining and lifting machinery, especially in high-power hydraulic transmission systems. In order to improve efficiency, these systems are usually equipped with gear pumps or vane pumps as auxiliary oil pumps to supplement leakage and maintain pressure in the oil circuit.
