• 한국생산제조학회지
• /
• 제8권2호
• /
• pp.35-43
• /
• 1999

The paper describes an approach for measuring delivery flow ripple generated by oil hydraulic axial piston pumps. In order to reduce pressure ripple which cause to undesirable noise. vibration and fatigue in hydraulic systems it is indispensible measure a delivery flow ripple from pumps. Since the flow ripple measurement of flow pumps is independent of the dynamic characteristics of the connected hydraulic circuit the measurement of flow ripple is most suitable for pump fluid-borne noise rating. The measurement of flow ripple with high frequencies from axial piston pumps is made by applying the remote instantaneous flow rate measurement method which is based on the dynamic characteristics between pressure and flow rate in hydraulic pipeline. The measured flow ripple waveforms are influenced by the configuration of V-shaped triangular relief groove in the valve plate. It can be seen that the appropriate relief groove in valve plate reduces the pressure and flow ripple amplitude and frequency spectrum for high harmonics.

• Tribology and Lubricants
• /
• 제14권4호
• /
• pp.51-57
• /
• 1998

Recently, bent-axis-type axial piston pumps driven by rods being in extensively used in the world, because of simple design, lightweight, effective cost. So, to guarantee the quality of bent-axis-type axial piston pumps driven by rods, it is necessary to know characteristics of the driving mechanism of rods. But, as they perform both reciprocating and spinning motions, it is difficult to understand driving mechanism. In this paper, I studied the theoretical driving mechanisms of cylinder block driven by rods through geometric method. I found that the cylinder block was driven by one rod in limited area and the driving area was changed by rod's tilting angle and cylinder block's swivel angle.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.156-158
• /
• 2008

Along the various gap distance between shoe and swash plate and pocket diameter, lifting force of piston shoe during the compressing stage was calculated. The flow in piston, orifice, shoe, and back space was considered to be 2-dimension axisymmetric and analysed by Fluent, a commercial CFD Software. The wall boundary condition was given as nonslip and adiabatic, while the change in fluid viscosity was considered as linear along temperature. Calculated lifting force and oil leakage of shoe was used in the design of a pump to confirm the shape of the shoe.

• Tribology and Lubricants
• /
• 제30권2호
• /
• pp.116-123
• /
• 2014

The objective of this study is to model and simulate the nonlinear lubrication performance of the sliding part between the piston and cylinder wall in a hydrostatic swash-plate-type axial piston pump. A numerical algorithm is developed that facilitates simultaneous calculation of the rotating body motion and fluid film pressure to observe the fluid film geometry and power loss. It is assumed that solid asperity contact, so-called mixed lubrication in this study, invariably occurs in the swash-plate-type axial piston pump, which produces a higher lateral moment on the pistons than other types of hydrostatic machines. Two comparative mixed lubrication models, rigid and elastic, are used to determine the reaction force and sliding friction. The rigid model does not allow any elastic deformation in the partial lubrication area. The patch shapes, reactive forces, and virtual local elastic deformation in the partial lubrication area are obtained in the elastic contact model using a simple Hertz contact theory. The calculation results show that a higher reaction force and friction loss are obtained in the rigid model, indicating that solid deformation is a significant factor on the lubrication characteristics of the reciprocating piston part.

• Tribology and Lubricants
• /
• 제24권6호
• /
• pp.343-348
• /
• 2008

In this paper, a CFD (Computational fluid dynamics) code, FLUENT is adopted to investigate accurate flow characteristics for a slipper bearing which is used swash plate type hydraulic axial piston pump. Static pressure and velocity distributions, and velocity vectors are plotted for different film thickness and slipper rotational velocity. In recess region, there exists a doughnut shaped vortex ring. The static pressure distributions are non-uniform and the flow fields are highly asymmetrical under bearing rotation. Therefore the numerical method adopted in this paper can be use in design of hydrostatic components and further studies are required.

• 한국공작기계학회논문집
• /
• 제16권6호
• /
• pp.117-124
• /
• 2007

The pressure ripple in most hydraulic systems is the root cause of their noise and vibration. This paper reduced the pressure ripple using side branch hose for an axial piston pump applied to small excavator. First, in calculating open area, a new method using groove area of valve plate is proposed. Simulation model in AMESim environment is developed to verify proposed method, find effective length and diameter of branch hose. Finally, the comparisons with experiment results show that the proposed method is more effective than previous method in reducing the pressure ripple.

• Journal of Advanced Marine Engineering and Technology
• /
• 제37권8호
• /
• pp.893-904
• /
• 2013

NSGA-II와 함께 크리깅 메타모델기반 다목적최적설계 전략을 3차원 CFD 시뮬레이션을 통해 액셜 피스톤 펌프의 밸브 플레이트 형상을 최적화하는데 적용하였다. 펌프의 압력 변동을 저감하고 수력 효율을 최대화하기 위한 최적설계 과정은 두 단계, 즉 (1) 밸브 플레이트 상의 6개 형상 설계 변수를 선정하고 각 설계변수의 변화에 따른 CFD 해석을 수행하며, (2) CFD 데이터를 이용한 NSGA-II에 기반한 다목적최적설계 접근방식으로 최소 맥동 압력과 펌프 효율 설계에 대해 파레토 프론트를 평가하는 것으로 구성된다. 이들 결과로부터 최소 맥동 압력을 가지며 액셜 피스톤 펌프의 목표 효율에 도달하는 최적 절충해를 선택할 수 있었다.

• 드라이브 ㆍ 컨트롤
• /
• 제17권1호
• /
• pp.51-60
• /
• 2020

This study addresses the modeling of a bi-directional outlet variable swash plate type axial piston pump with two EPPR valves and an analysis of the response characteristics to the angle control of that pump. In this paper, the combination of the EPPR valve and double rod type piston is referred to as the EPPR regulator. The EPPR regulator is compact and inexpensive, and has good responsiveness. Under actual pump operating conditions, because of the various external conditions of the pump, inertia is applied to the swash plate, generating the tilting torque. Also, the tilting torque can delay or shorten the response characteristics of the regulator. So we validated them through the analysis using SimulationX and these results allow users to freely integrate the EPPR regulator into the desired system.

• Journal of Mechanical Science and Technology
• /
• 제18권9호
• /
• pp.1668-1679
• /
• 2004

The design of an axial piston pump for electro-hydrostatic transmission systems requires accurate information where and how much the internal friction and flow losses are produced. This study is particularly focused on the friction losses of a bent-axis type hydraulic piston pump, aiming at finding out which design factors influence its torque efficiency most significantly. To this end, the friction coefficients of the pump parts such as piston heads, spherical joints, shaft bearings, and valve plate were experimentally identified by a specially constructed tribometer. Applying the experimental data to the equations of motion for pistons as well as to the theoretical friction models for the pump parts, the friction torques produced by them were computed. The accuracy of the computed results was confirmed by the comparison with the practical input torque of the pump. In this paper, it is shown that the viscous friction forces on the valve plate and input shaft bearing are the primary source of the friction losses of the bent-axis type pump, while the friction forces and moments on the piston are of little significance.

• 한국산업융합학회 논문집
• /
• 제19권3호
• /
• pp.125-132
• /
• 2016

The swash-type piston pump is a device that discharges as much volume of hydraulic oil generated as it moves the ramp by controlling the angle of the swash. This pump is suitable for high-speed high pressurization, and due to its useful characteristic being the variable capacity-type, it is used as a main pump for heavy equipment in various fields such as defense, shipbuilding, construction, etc. This study intends to obtain optimal design values by conducting a structural analysis in order to verify its reliability during the design process of the newly developed swash-type piston pump.