Relative motion relation in the external return spherical bearing pair of a balanced double-row axial piston pump

Abstract

Based on the external compaction return mechanism of a balanced double-row axial piston pump and the vector coordinate transformation principle, a mathematical model of the relative motion relation within the external return spherical bearing pair was built. The influence of slant inclination of the external swash plate and of pump shaft rotating speed and eccentricity on the relative motion trail, movement speed and acceleration was analysed. The relative motion velocity and acceleration between external retainer plate and external spherical hinge, at top and bottom dead centres, were discussed. By increasing the slant inclination of the external swash plate, the relative motion trail increased correspondingly, leading to a larger size of the pump integral structure. The relative speed and acceleration increased with the pump shaft speed and the slant inclination of the external swash plate, leading to a larger fluctuation of the slipper pair oil film. The increase of eccentricity slightly influenced the relative velocity and acceleration along the x-axis, without significantly increasing the fluctuation of the slipper pair oil film. Increasing the pump shaft speed, the external swash plate slant inclination and the eccentricity all caused fluctuations in the relative velocity and acceleration along the y- and z-axes, deepening the grinding crack on the compaction surface of the external retainer plate. In case of eccentricity and a 0° rotation angle of the principal axis, the related acceleration of the radial friction surface of the retainer plate showed the largest fluctuation amplitude, and a scratch could easily occur.

Lubrication characteristics of external return spherical hinge pair of axial piston pump or motor under combined action of inclination and offset distance

“…To analyze the kinematic characteristics of the external return mechanism, principal and subordinate coordinates similar to Ref. [27] were established. As shown in Figure 2, the principal coordinate system O-xyz is consolidated on the external spherical hinge; the origin is coincident with the inner contour of this hinge and the O-x axis is taken as the axial direction of the pump shaft and is used to describe the hinge's rotation.…”

“…Because the relative motion of the external return mechanism significantly influences the lubrication characteristics, the lubrication problem is studied according to the vector equation of the relative speed of the external return spherical hinge pair in Ref. [27].…”

Friction and wear analysis of the external return spherical bearing pair of axial piston pump/motor

“…Since the unit vector n t has the same direction as the radius vector r 5t of the contact point m t , and the unit vector u t has a direction opposite to the relative motion velocity DV t of the contact point m t [23], the unit vector n t and u t can be expressed as…”

“…Its kinematic and frictionlubricating characteristics have a great influence on the working performance of the slipper pair, plunger pair and port pair of the pump/motor-and they are also a key factor affecting technical indicators such as service life, working performance and vibration noise of the pump/ motor component. Deng et al carried out a deep analysis of the kinetic characteristics of the external return mechanism [23]. This paper will further analyse the force laws and wear characteristics of the external return mechanism and provide a basis for a dynamic-pressure lubrication-characteristics analysis.…”

Analysis of the Hydrodynamic Lubrication Characteristics of the External Return Spherical Bearing Pair of an Axial Piston Pump/Motor

“…Liu et al [9] established a mathematical model of the dynamic rules of a lubricating oil film for the slipper pair and investigated the influence of different return mechanisms on the oil film characteristic of the slipper. Deng et al [10] analysed the relative motion characteristics between the external spherical hinge and the external retainer plate and investigated the influence of the external swash plate inclination and pump shaft rotating speed on the relative motion scratches of them.…”