Created on:2021-05-22 10:27

Typical structure of axial distribution radial piston pump

Typical structure of axial distribution radial piston pump

① The point contact type radial piston pump is shown in Fig. l as a structure of axial flow distribution type radial piston pump. In addition to the main body, the pump also has many accessories, such as low-pressure oil filling gear pump, safety valve, variable mechanism, push cylinder, suction valve and so on. The internal pressure of pump body 1 is equipped with a port shaft 2, on which there are oil suction holes and oil pressure holes. The rotor 3 is supported on the port shaft 2 by two ball bearings. The plunger 4 can move back and forth in the plunger holes distributed radially on the rotor 3. When the rotor 3 is driven to rotate by the transmission shaft 9, the plunger extends outward and presses against the inner conical surface of the stator 5. The stator 5 is fixed on the drum 6, but the drum 6 is supported on the sliding seat 7 by two roller bearings, so the drum 6 can rotate freely on the sliding seat 7 with the stator 5. There are two parallel guide rails on the sliding seat 7, which are matched with the two parallel guide rails on the pump body 1, so that the sliding seat 7 can move left and right in the pump body 1. At the same time, it also drives the drum 6 and the stator 5 to move left and right, so that the eccentricity between the center of the stator 5 and the rotor 3 is generated. Therefore, when the rotor 3 is driven by the transmission shaft 9, the plunger 4 reciprocates in the plunger hole on the rotor 3 once every rotation, that is, oil suction and oil pressure. Therefore, this kind of radial piston pump is also called single acting piston pump.

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In this pump, the top of the plunger 4 is an approximate spherical surface, while the inner circular surface of the stator 5 is a conical surface, so the contact point between the top of the plunger 4 and the inner conical surface of the stator 5 does not pass through the rotation center of the plunger 4, so that the friction generated at the contact point between the plunger 4 and the stator 5 forms a torque on the rotation center of the plunger 4, forcing the plunger 4 to rotate around its own axis, so the plunger 4 is in the column When the plug hole moves back and forth, it also rotates to make the friction pair between the plunger and the plug hole have good lubrication and uniform wear. Because the above friction also acts on the stator 5, the stator 5 can also rotate on the sliding seat 7 together with the drum 6, thus greatly reducing the relative motion speed between the rotor 3 and the stator 5, reducing the mechanical wear, and prolonging the service life of the friction pair parts. The pump has three variable modes: manual variable, manual servo variable and electro-hydraulic proportional servo variable.

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② Figure m shows the structural principle of a surface contact variable displacement radial piston pump. The transmission shaft 1 drives the star rotor (cylinder block) 8 with balanced radial force to rotate through the cross coupling 4. The rotor is supported on port shaft 3. The plunger 9 installed in the rotor hole clings to the eccentric stator ring 5 through the statically balanced slipper 6. The plunger is connected with the sliding shoe by a ball hinge and is locked by a snap ring. The sliding shoes are constrained in the eccentric stator ring by two retaining rings 2. During operation, the sliding shoes are pressed to the eccentric stator ring by centrifugal force and hydraulic pressure. When the cylinder block rotates, due to the action of the eccentric stator ring, the plunger will form reciprocating motion, and its stroke is twice of the eccentric distance of the eccentric stator ring. The eccentric position of the stator ring can be adjusted by the variable of the radial relative position on the pump body to control the pistons 7 and 10. The suction and pressure oil pass through the flow passage on the pump body and the valve distribution shaft, and can be controlled by the oil inlet and outlet on the valve distribution shaft. Because the plunger and the inner surface of the stator ring in the pump are close to each other (surface contact) through the sliding shoes with arc surface at the upper end, and the hydraulic pressure acting on the inner surface is completely statically balanced, and the rolling bearing supporting the transmission shaft is only affected by external force, the service life of the pump is long. The RKP radial piston pump produced by Bosch Company in Germany is of this structure. Its maximum working pressure is 38.5mpa, flow range is 16-90ml / R, and maximum speed is 3500r / min.

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