• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.12
• /
• pp.75-81
• /
• 2008

A robust controller is proposed for regulating effectively the pressure of control cylinder of swash plate type variable displacement axial piston pump. In order to design a precise and robust pressure control system, a mathematical model for swash plate control system is identified by the signal compression method. Based on the identified mathematical model, an $H_{\infty}$ robust swash plate controller is designed which is robust to the variation of the load pressure. The precise and robust swash plate control characteristics are verified by experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.101-102
• /
• 2006

The purpose of this paper is pulsation-analysis of the swash plate type axial piston pump for excavator and the method of side branch hose application, which is used normally in construction equipments. In this paper, draw the mathematical modeling for pressure pulsation mechanism of the swash plate type axial piston pump for excavator, expression the flow pulsation in the pipelines by transfer matrix method, programmed simulation for pulsation by AMEsim software, and the reliability of that was verified by the comparison with the experimental results.

• Journal of Drive and Control
• /
• v.11 no.4
• /
• pp.53-60
• /
• 2014

This paper proposes a control scheme to reduce the power consumption of a variable displacement swash-plate type piston pump supplying oil to a valve-controlled hydraulic cylinder at constant pressure. Whenever flow rate demand was absent, the swash plate angle and the pump speed were changed to the minimum values required to compensate for the internal leakage flow. In response to command signals, the pump speed was changed in proportion to the absolute mean value of the speed component for position commands. At the same time, a pressure regulator was activated to maintain constant system pressure by precisely adjusting the pump speed with the swash plate angle fixed at the maximum. The conventional system consisting of a pressure-compensated variable displacement type pump is driven at a constant speed of 1,800rpm. By comparison, computer simulation and experimental results showed that idling power at stand-by status could be reduced by up to 70% by reducing the pump speed from 1,800rpm to 300rpm and the swash plate angle to the minimum.

• Journal of Drive and Control
• /
• v.11 no.4
• /
• pp.25-31
• /
• 2014

This paper details application of a DLC(Diamond Like Carbon)-coating to the swash plate and the ball joint of pistons that make sliding contact with the piston shoes of an axial piston pump. This process, aimed to reduce the frictional and leakage power losses of the hydrostatic piston shoe bearings at the low speed range. At lower speeds than 100rpm, the positive effects of the DLC-coating on the power loss reduction of the hydrostatic piston shoe bearings could be confirmed. These effects resulted in little improvement in volumetric efficiency of the test pump, but the mechanical efficiency could be raised by up to 5% at 100rpm; here, the DLC-coated swash plate played a more dominant role than the DLC-coated ball joint.

• Journal of Drive and Control
• /
• v.16 no.2
• /
• pp.43-50
• /
• 2019

The objective of this study was to reverse engineer a swash plate type piston pump mounted on a wheeled armored vehicle and to analyze the structure of the pump case. From the analysis, the weak parts were identified and corrected in the final design. Each element corresponding to the piston pump case was analyzed. The analytical method was given static boundary conditions, load conditions and confirmed displacement, strain, stress, and safety factor. Plastic deformation and damage were also confirmed and the component elements redesigned through structural analysis Structural analysis and vibration analysis were carried out for the components of the piston pump case. The piston pump model was finally modified by structural analysis and vibration analysis results for each component assembly, and a prototype was designed. Durability test and environmental test were carried out and the test results satisfied all of the requirements. Therefore, the analytical method presented in this study can be utilized as a methodology for element component design in the development of various piston pumps.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.7
• /
• pp.749-753
• /
• 2013

Hydraulic systems are used to transform mechanical energy and fluid energy into each other. Its applications are very wide over the whole industries such as automobiles, public works, rockets, machine tools, construction heavy equipments, airplaces and so on. They are hydraulic pumps that transform energy in the systems. In this study, with basic operation principles as a start point, I tried to understand how the rotating radius of a piston affects the lubrication characteristics in more practical conditions, a swash-plate with tilt angle zero capable of rotating motion and other devices was used. In this paper, a slipper was located on 45mm eccentricity from the center of a swash-plate. As a result, through this experiment, it was found that the rotating radius of a piston affects load capacity, leakage flow and lubrication characteristics and it is one of the important parts for improving the pump efficiency.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• 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.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.25 no.1
• /
• pp.89-95
• /
• 2016

This study investigated the design factors of the opening area in order to consider the kinematic stability of a valve plate, conducting an analysis of the reduction effects of pressure pulsation and flow ripple depending on the design factors, using the $SimulationX^{(R)}$ (Germany) hydraulic analysis program. Further, we performed a structure analysis to confirm the kinematic stability of the valve plate in a swash plate type piston pump, and analyzed the effects of pulsation on a 1-step V-type notch, 2-step V-type notch, and 2-step U-type notch to determine the effects of pulsation reduction. Finally, we show the effectiveness of our proposed design of the pre-compression sections on a valve plate in terms of low pulsation by using the hydraulic analysis program, $SimulationX^{(R)}$.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.741-744
• /
• 2002

The closed circuit pump is applied to control rotating speed and direction of hydraulic motor in hydrostatic transmission. To development of this pump, first of all the servo control regulator has to be designed. Mechanical-hydraulic type servo control mechanism is excellent to be compared with electronic-hydraulic type servo control valve to reliability and economy. In this paper to development positive and negative variable displacement type servo regulator, the hydro-mechanical servo control mechanism is calculated and designed with force balance of pilot piston and position feedback of servo piston.

• Tribology and Lubricants
• /
• v.24 no.6
• /
• 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.