• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.875-882
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• 2011

In the present study, the imbalance in the axial-thrust and variation in the volumetric efficiency that occurred during the trimming of impeller diameter were investigated. The present study was focused on low-specific-speed multistage centrifugal pumps with a balancing piston as the balancing mechanism. The effects of impeller trimming on the axial-thrust balance in multistage pumps with horizontal and vertical axes were compared. The results showed that impeller trimming resulted in an additional axial-thrust acting in direction of pump inlet. The axial-thrust imbalance due to impeller trimming was more severe in the vertical-axis pumps than in the horizontal-axis pumps. The rate of increase in the diameter of the balancing piston, which was proportional to the rate of impeller trimming, was evaluated to maintain the axial-thrust balance. Furthermore, a simultaneous increase in the piston length and piston diameter was more effective for reducing the axial-thrust imbalance along with the volumetric efficiency drop.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.52-57
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• 2016

A swash plate-type piston pump is a device used to discharge hydraulic fluid as the volume generated through the piston moves in the direction of the slope by adjusting the angle of its swash plate. In addition, the valve block internalized in the pump includes a flow path for intake from outside, a flow path for discharge, and a pilot conduit line to control discharge pressure and flux. In this study, a numerical analysis is conducted to improve the cracking of the valve block generated during process testing, and the developed pump is evaluated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.76-81
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• 2018

This study aims to provide ways to achieve structural improvements of the internal flow path of the discharge plenum of a swash plate piston pump valve block vulnerable to cracks. This paper corresponds to Part II, which consists of a structural interpretation of the internal flow path of the discharge plenum of the valve block. The simple model result reviewed in Part I was incorporated into the valve block model and five different design changes were reviewed as part of the study on the structural improvement of the internal flow path of the valve block.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.69-75
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• 2018

This study aims to provide ways to achieve structural improvements of the internal flow path of the discharge plenum of a swash plate piston pump valve block vulnerable to cracks. This paper corresponds to Part I, which consists of a structural analysis of the valve block, identification of the stress distribution and stress raisers, and creation of a Simple Model of the valve block to review the optimal design. Structural analysis was performed by assigning the same conditions as those found in the valve block model, and the design was reviewed by examining three different design improvement plans for the internal flow path of the discharge plenum.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2424-2429
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• 2015

In an oil hydraulic piston pump, the cylinder block and valve plate in high speed relative sliding motion have the characteristics which should be extremely controlled for the optimization of leakage and friction losses, and pressure-resistance design of them is very important for high pressure performance. But the studies on the stress analysis of those parts have not been performed briskly. Therefore, in this paper, the stress and displacement distributions of the cylinder block and valve plate in the oil hydraulic piston pump with a swash plate type are discussed through the static stress analysis using CATIA V5. The stress and displacement of the cylinder block are more influenced by the axial pressure than by the radial pressure, and are larger by approximately 66% and 30%, respectively. The results show that a review of the material and shape of the valve plate is required.

• 한국기계연구소 소보
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• s.18
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• pp.75-85
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• 1988

The distributor for hydraulic pumps or motors, particularly radial piston motors, include rotary member which has equally both surface shape for dynamic balance and two fixed members, located in both side of rotary member, which have equal surface shape for dynamic balance and circular ring which use to retain predetermined clearance between two fixed members. Rotary member must have valve part for flow-distribution and can have hydrostatic bearing for excellently dynamic balance. At least two annular steps located on said pressure plate which use in compensation of bolt expansion.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2071-2075
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• 2003

Pressure variation is one of the major sources on noise emission in the oil hydraulic piston pumps. Therefore, it is necessary to clarify about pressure variation characteristics of the oil hydraulic piston pumps to reduce noise. Pressure variations in a cylinder at trapping region were measured during pump working period with discharge pressures, rotational speeds. The effect of pre-compression of the discharge port with three types valve plates also investigated. It was found that the pressure variation characteristics of oil hydraulic piston pumps deeply related with pre-compression design of the discharge port. Also, it was found that the pressure overshoot at trapping region can reduce by use of pre-compression at the end of the discharge port in valve plate