DYNAMIC OF AN AXIAL PISTON PUMP WITH FLOATING PISTONS

A new structure of the axial piston pump was proposed to address the limitation of its application under low viscosity medium conditions due to the insufficient oil film bearing capacity. The piston of this structure is in a floating state in the axial direction, and both ends of the piston are supported by a discrete cylinder in the shape of a spherical joint. Because of the adaptive ability of the spherical joint in the orientation, the lateral force borne by the piston during operation has been decreased. And through a pair of bevel gears, the relative distance between the spherical joints at both ends of the piston varies with the rotation of the shaft, thereby enabling the pump to achieve a change in the cylinder volume. To demonstrate the superiority of the structure, firstly a mathematical model for dynamic analysis was constructed based on its working principle. Then, a kinematic analysis was conducted on a developed product, and co-simulated with AMESim to obtain the output flow pulsation. Subsequently, the dynamic characteristics of the piston were calculated. Finally, the simulation data was compared with that of a traditional swash plate axial piston pump of the same specifications. The results showed that the flow quality of AFPP will not be lower than that of the traditional pump with same displacement. And the piston lateral force can be changed from pressure dependent force to pressure independent force, so the piston lateral force of AFPP is smaller than that of traditional piston pumps at high-pressure condition, so the friction force and the wear between the cylinder and the piston can be significantly reduced. Therefore, this this type of structure can reduce the demand for oil film bearing capacity and have the ability to adapt to low viscosity media and low-speed working conditions.