Type and working principle of piston pump?

Plunger hydraulic pump is a positive displacement hydraulic pump, through the repeated movement of the plunger in the cylinder hole, change the capacity of the plunger cylinder, the low pressure oil into the tank, pressure into the system high pressure oil. The plunger pump is widely used in the hydraulic system of construction machinery because of its advantages of high output pressure, high efficiency, large power, convenient variable and strong and durable.

According to the different arrangement of the plunger in the cylinder hole, the plunger pump can be divided into radial plunger pump and axial plunger pump. The radial piston pump is mainly composed of a plunger, a rotor, a bushing and a distribution shaft. The plunger is closely matched with the rotor hole, rotating with the rotor, and the distribution shaft is fixed. When the rotor rotates, the plunger is stuck on the inner wall of the stator under the action of centrifugal force. The plunger is uniformly arranged in the rotor, and there is eccentricity between the rotor and the stator. When the rotor rotates, the plunger in the oil absorbing area extends out under the action of centrifugal force, and the capacity of the sealing studio in the radial hole gradually increases, and the oil is absorbed through the oil absorbing chamber of the distribution shaft. Due to the compression of the inner surface of the stator, the plunger in the oil pressing area shrinks, the capacity of the sealing studio is gradually reduced, and the oil chamber is pressed through the distribution shaft. Moving the stator to change the eccentricity can change the stroke of the plunger and then change the displacement. Due to the complex structure of the radial piston pump, large radial size, poor self-priming capacity, the distribution shaft is affected by the hydraulic imbalance force, easy to damage, limiting the increase of speed and working pressure, and gradually replaced by the axial piston pump in many places. But the radial plunger is mainly used for low speed and large rotation hydraulic motor. Axial piston pumps are widely used in systems where high pressure, high flow and flow regulation are required.

Axial piston pump plunger parallel to the rotor cylinder, the plunger axial arrangement. Axial piston pump according to its distribution mode can be divided into plate distribution and valve distribution. Axial piston pumps with valve placement rely on rotation of the rotor to force the plunger to repeatedly move axially. When the plunger changes the direction of movement at the end of the stroke, the two check valves automatically open and close with the reduction of pressure in the pump chamber during the suction process and the increase of pressure in the pump chamber during the discharge process to achieve flow distribution. In practice, the valve distribution axial piston pump loses its reversibility due to its complex structure. This kind of pump can not be used as a hydraulic motor, when the pump rotates at high speed, the gate valve opening and closing process is prone to collision and action lag, so the valve distribution axial piston pump is not commonly used in the hydraulic control system.

Axial piston pump with flow plate and flow channel can be divided into swashplate axial piston pump and swashplate axial piston pump according to its structural characteristics. Swash plate type axial piston pump is widely used in construction machinery. The axial piston pump consists of a drive shaft, a key, a cylinder block, a plunger, a slipper shoe, a rotary plate, a swash plate, etc. The large bearing branches are inherited on the pump body, and the plungers are installed in the plunger holes evenly distributed in the cylinder block. In order to avoid direct wear of the plunger head and the inclined plate, it is worn. When riveted, neither the plunger nor the slipper shoe falls off, nor does there be relative movement between the spheres. Under the action of the center spring and the return drive, the slipper always moves close to the surface of the diagonal disc. The drive shaft drives the cylinder to rotate through the spline, the cylinder rotation drives the plunger to rotate, and the plunger moves in a straight line in the plunger hole. In order to precisely coordinate the movement of the plunger and the suction channel and the switching of the pressure channel, a fixed prior art distribution component is placed on the surface of the tank end of the pump and between the suction channel and the pressure channel. There are two curved channels and waist-shaped flow Windows on the board. The front end of the flow tray is closely fitted with the end face of the cylinder and slides relative to it. On the back of the flow plate, two waist-shaped flow Windows are connected to the oil suction circuit and the oil circuit of the pump. When the cylinder block is rotated from the bottom position with the plunger, the sealing volume of the plunger hole increases when the plunger wants to extend out of the return mechanism, forming a local vacuum. Next, the oil suction window of the oil tray is sucked into the plunger hole, which is the oil suction process; When the cylinder is rotated with the plunger from the bottom position to the top position, the plunger is pressed into the tilting tray and is pressed into the tipping in the tilting tray. In the plunger hole, the sealing volume of the plunger hole is reduced, and the oil in the hole is squeezed. The oil window is pressed into the system through the oil window of the flow tray. This is the oil discharge process.