Abstract
Abstract. To study the flow characteristics of a new swashplate rotary valve distribution double-row axial piston pump, an instantaneous flow model was developed for the pump, the influences of structural parameters on the flow pulsation and uneven coefficient of flow were determined, and the ideal plunger distribution parameters were derived. On this basis, a valve distribution model was developed for the pump, the flow superposition process in the plunger cavity was analyzed, and the high-speed switching valve's control strategy was optimized. Additionally, the effects of parameters such as the plunger motion frequency, the plunger cavity's dead zone volume, the spool valve's preloading force, and the spool's equivalent mass on the flow characteristics were studied. The results show that the new pump had a small flow pulsation when there were five plungers in both the inner and outer rows and the dislocation angle was 18∘. The plunger's reverse-suction effect at the moment when the discharge valve opened and the suction valve closed and the plunger cavity's dead zone volume size were the primary factors affecting the size of the pump's flow spike. The discharge valve's opening was delayed by 3 ms to be consistent with the suction valve's closing time; for this case, the flow peak was small and the volumetric efficiency was the highest. The discharge valve began to close 2 ms early and closed completely at the critical point when the plunger transferred from the discharge stroke to the suction stroke, which helped the suction valve to open on time and improved the pump's oil absorption capacity. The active opening and closing control of the discharge valve improved the coordination of the flow distribution to a large extent, reduced the hysteresis of the suction valve, and ultimately improved the pump's volumetric efficiency and flow stability. The results of this study can provide theoretical guidance for the flow control of balanced double-row axial piston pumps with valve distribution.
Highlights
Axial piston pumps with high pressures, high flow rates, and compact structures are core power elements in many fields, such as aerospace, metallurgy, ships, and engineering machinery (Casoli et al, 2019; Manco et al, 2002)
A reasonable design dislocation angle, θ, caused the flow curves for the inner and outer rows of plungers to be staggered half a cycle, causing the minimum value of the inner flow to always correspond to the maximum value of the outer flow and the maximum value of the inner flow to always correspond to the minimum value of the outer flow
Opening and closing of the discharge valve require a certain amount of time, and delayed closing would affect the opening of the suction valve, which would result in insufficient oil absorption and would affect the volumetric efficiency
Summary
Axial piston pumps with high pressures, high flow rates, and compact structures are core power elements in many fields, such as aerospace, metallurgy, ships, and engineering machinery (Casoli et al, 2019; Manco et al, 2002). Li et al (2013) studied the flow characteristics of a high-frequency reciprocating pump with a check valve distribution and analyzed the reasons why the output flow of the pump was still bottlenecked despite the fact that the frequency response of the check valve met the system requirements They concluded that there was a large disparity between the volumetric efficiencies for the passive and active flow distributions. A new balanced valve distribution double-row axial piston pump is proposed in this paper to achieve semi-active flow distribution with high-speed on– off valve technology. The new pump’s structure and working principle were determined, the influences of the plunger distribution and the numbers of inner and outer row plungers on the pump’s flow characteristics were analyzed, and better plunger distribution parameters were derived On this basis, an AMESim flow distribution model for the whole pump was developed, and the discharge valve’s opening and closing strategy was optimized. Variable function was achieved by replacing the two-position two-way highspeed switching valve with a two-position three-way switching valve
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