Through shaft axial piston pump
Through shaft axial piston pump 1
① Through shaft axial piston pump
a. The structure of a through shaft quantitative axial piston pump is shown in Figure W. The transmission shaft 1 passes through the swash plate 2 and the return plate 3, and is supported by the ball bearing 11 and the roller bearing 9. The left end is equipped with the skeleton oil seal 12. The ball head of the plunger 5 is installed in the ball socket of the slipper 4, and the return mechanism composed of the center spring 10 and the return plate 3 makes the slipper limit close to the inclined plane of the swash plate 2. The distribution mode of the pump is plane distribution.
When the prime mover drives the cylinder block to rotate in the direction shown in Fig. w through the transmission shaft 1, the plunger assembly reciprocates relative to the cylinder block due to the inclined plane of the swash plate. In the process of the sliding shoe sliding from the top point of the inclined plane of the swash plate to the bottom point, the plunger group extends out of the cylinder block hole. At this time, the sealing cavity formed by the plunger and the cylinder block hole gradually increases, and the oil is sucked through the channel a of the pump cover 8 and the window of the valve plate 7 The sealing chamber is enlarged. In the process of sliding shoe sliding from the lowest point to the highest point, the plunger group moves to the cylinder bore, so the sealing chamber is gradually reduced, and the oil is pressed out through the window on the other side of the port plate and the flow channel B of the pump cover. The oil chamber C at the contact point between the slipper and the swash plate is connected with the working chamber in the cylinder block through the small hole D in the middle of the plunger. After the pressure oil enters the oil chamber, a layer of oil film with the function of hydrostatic support is formed between the contact surface of the slipper and the swash plate, which greatly reduces the force of the slipper on the swash plate, so the wear is also reduced. Because the inclination angle of the swash plate is not changed, the pump is a constant displacement pump.
b. Variable displacement pump figure x shows a through axis variable displacement axial piston pump structure. The pump adopts trunnion swash plate 6; the plunger 3 returns by the center spring 10, return plate 5 and ball hinge 9; the plane flow distribution surface is on the end face of the back cover 1, so the valve plate parts are omitted. The longitudinal centralized variable mechanism 8 is directly controlled by the outlet oil pressure of the pump.
This kind of pump has the advantages of low pressure, simple structure, light weight and low cost. Its efficiency is about 5% higher than that of vane pump. Its service life is longer than that of vane pump, and its noise is close to that of vane pump. It is suitable for hydraulic source of open system. In addition to the direct control variable of oil pressure, PVB series through shaft pumps have a variety of variable modes, such as pressure compensation, maximum displacement adjustable pressure compensation, medium pressure compensation, maximum displacement adjustable medium pressure compensation, remote control pressure compensation, maximum displacement adjustable remote control pressure compensation, load sensing and pressure limiting load sensing.
Figure y shows another through shaft variable displacement axial piston pump [Parker PV series]. The pump is a through shaft transmission structure. It has nine plungers 5. The inclination angle of swash plate 3 is controlled and adjusted by a variable mechanism (compensator) composed of variable control cylinder (piston) 6, control valve 7 and return spring 8. The compensator has four forms: standard pressure compensation, constant power compensation, load sensing and electro-hydraulic displacement control (Fig. z). The nominal pressure of the pump is 35MPa, the displacement range is 16 ~ 270ml / R, and the rotation speed is 1800 ~ 3000r / min. The pump is characterized by fast variable response (the response time from zero to maximum stroke is less than 70ms, and the response time from maximum stroke to zero stroke is less than 40ms); the compensator has the function of active pressure relief, which reduces the pressure peak value when the flow variable is toward zero; it still has the function of stable compensation and regulation under low pressure, with low noise. The 9-plunger is designed and the new technology of compression volume is adopted to reduce the flow pulsation to a minimum The lowest level ever; single pump and multiple pumps can be connected in series, and pumps with the same specification, type and almost the same mounting flange can be installed in combination (Fig. a). The pump is suitable for open hydraulic system.