Abstract:This article presents a novel methodology to design swash plate type axial piston machines based on computationally based approach. The methodology focuses on the design of the main lubricating interfaces present in a swash plate type unit: the cylinder block/valve plate, the piston/cylinder, and the slipper/swash plate interface. These interfaces determine the behavior of the machine in term of energy efficiency and durability. The proposed method couples for the first time the numerical models developed at t… Show more
“…A type of non-linear groove opening profile was adopted within the virtual prototyping optimization procedure and plausible results on maximizing volumetric efficiency and reducing flow ripples were received. 14 After decades of development, the relief groove has now become a default design for the valve plates in axial piston pumps.…”
This paper presents a study of flow ripple reduction method of a spool valves distribution radial piston pump (SVDRPP). Relief chamfers are adopted to prolong and moderate the opening processes of the delivery spool valves, thus to relieve the pressure surges as well as the consequent flow ripples, vibrations and noises. The mathematical model of this method is established and multiple numerical simulations are conducted to analyze the mechanism as well as the effectiveness of this method. According to the simulation results, different relief chamfer angles have varying influences on flow ripple reduction. Remarkable reduction of flow fluctuation from 43.4% to 36% could be achieved, when the relief chamfer angle is set around 30°. Comparisons between the relief chamfer method and the time delay method indicate that the former has better compatibility to the load pressure lower than the rated value; while the latter has better compatibility to the higher load pressure.
“…A type of non-linear groove opening profile was adopted within the virtual prototyping optimization procedure and plausible results on maximizing volumetric efficiency and reducing flow ripples were received. 14 After decades of development, the relief groove has now become a default design for the valve plates in axial piston pumps.…”
This paper presents a study of flow ripple reduction method of a spool valves distribution radial piston pump (SVDRPP). Relief chamfers are adopted to prolong and moderate the opening processes of the delivery spool valves, thus to relieve the pressure surges as well as the consequent flow ripples, vibrations and noises. The mathematical model of this method is established and multiple numerical simulations are conducted to analyze the mechanism as well as the effectiveness of this method. According to the simulation results, different relief chamfer angles have varying influences on flow ripple reduction. Remarkable reduction of flow fluctuation from 43.4% to 36% could be achieved, when the relief chamfer angle is set around 30°. Comparisons between the relief chamfer method and the time delay method indicate that the former has better compatibility to the load pressure lower than the rated value; while the latter has better compatibility to the higher load pressure.
“…Assessing the performance of surface shaping via physical testing is prohibitive for cost and time requirement reasons; the present work therefore prototypes virtually, simulating the behavior of the piston–cylinder lubricating interface using the multi-physics model developed at the Maha Fluid Power Research Center by Pelosi, 20 Mizell, 21 and Shang. 22 More information on this model and its validation is available in, 23,24,14,25,5,26 and an example of the design of water-lubricated piston–cylinder interfaces in a commercial APMSPD using the model, with physical testing, can be found in. 27 Since its outputs serve as performance markers in the design studies to follow, a brief overview of the model will be provided here, guided by Figure 5.Figure 5.Multi-physics lubricating interface model (image based on Ref.…”
Water’s low viscosity renders it a poor lubricant, but its green footprint, non-toxicity, inflammability, and low cost make it a desirable hydraulic fluid. Axial piston machines running on water are commercially available, but, especially the larger units, do not operate in the high-pressure regime ( ≥300 bar). The present work investigates micro surface shaping as a design solution for the critical piston–cylinder interfaces of these units, which are particularly hard-struck by the low viscosity of water in that the pistons are subject to a heavy side load, and these interfaces cannot be hydrostatically balanced. Through virtual prototyping, the effect of two surface shapes at a high-pressure operating condition is studied for the case of a 75 cc commercial unit: first, the concave bore profile, which gives the bore surfaces through which the pistons travel the lengthwise cross-section of a circular arc, and second, the barrel piston profile, which bestows this cross-section on the piston running surface instead. The design studies conducted show that, on account of the manner in which the pistons of these machines deform over the high-pressure stroke, the concave bore profile is most able to improve overall load support when its apex is in the middle of the guide length, or shifted toward the displacement chamber. Furthermore, the concave bore profile outperforms the barrel piston profile, largely because when the piston’s axial movement takes its apex into the displacement chamber, this surface shape is no longer able to enhance the piston-bore surface conformity at the end of the interface bordering the displacement chamber that is conducive to hydrodynamic pressure buildup in that region.
“…The TPGA utilizes the Maha Fluid Power Research Center state-of-the-art multi-physics model, which simulates the behavior of the three most important APMSPD lubricating interfaces: the piston-cylinder interface, the slipper-swash plate interface, and the cylinder block-valve plate interface. The value of this model is demonstrated by Chacon and Ivantysynova [25], who utilize it as part of an APMSPD virtual prototyping algorithm, ultimately designing and testing an entire 24 cc unit. In avoiding the repeated physical prototyping and measuring associated with the traditional trial-and-error approach to design, the TPGA, using this interface model, is able to drastically cut down on what would otherwise be extremely high, if not prohibitive, development costs.…”
A novel virtual prototyping algorithm has been developed to design one of the most critical lubricating interfaces in axial piston machines of the swash plate type—the piston–cylinder interface—for operation with water as the working fluid. Due to its low viscosity, the use of water as a lubricant can cause solid friction and wear in these machines at challenging operating conditions. The prototyping algorithm compensates for this by tailoring the shape of the bore surface that guides the motion of each piston in this type of positive displacement machine to conform with the piston surface, taking into account both the piston’s tilt and its deformation. Shaping these surfaces in this manner can render the interface more conducive to generating hydrodynamic pressure buildup that raises its load-carrying capacity. The present work first outlines the structure of the proposed algorithm, then presents a case study in which it is employed to design a bore surface shape for use with two prototypes, one virtual and one physical—both modified versions of a 444 cc commercial axial piston pump. Experimental testing of the physical prototype shows it to achieve a significantly higher maximum total efficiency than the stock unit.
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