• 한국항공우주학회지
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• 제35권3호
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• pp.231-237
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• 2007

EHA용 유압 펌프의 토크 맥동은 저속 회전 영역에서 실린더 위치의 제어에 외란으로 작용할 수 있다. 원칙적으로 피스톤 펌프에 의해 발생되는 반력 토크의 주기적인 변화는 실린더 압력의 파형과 밀접한 관계를 가지고 있다. 일정 속도로 회전하는 단방향 피스톤 펌프의 경우에는 밸브 플레이트의 예압각이나 노치를 활용하여 실린더 압력의 오버슈트나 변화율을 조절할 수 있다. 따라서 본 연구에서는 밸브 플레이트의 형상이 EHA용 사축식 유압 피스톤 펌프의 토크 맥동에 미치는 영향을 분석하였다. 그 결과로서, 양방향 회전형 유압 피스톤 펌프의 토크 맥동은 회전 속도의 영역에 무관하게 밸브 플레이트의 예압각이나 노치를 이용하여 개선하는 것이 불가능한 것으로 나타났다.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1565-1576
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• 2002

By way of driving a 2-way on/off solenoid hydraulic valve with a pulse width modulation (PWM) signal, control of the pressure in a certain volume is frequently used in various applications. However, the pressure built-up according to the duty ratio and carrier frequency of the PWM signal is not so well understood. In order to clarify the characteristics of 2-way valve hydraulic pressure control systems, in this paper two formula fur the mean and ripple of the load pressure were derived through theoretical analysis. And the accuracy of the derived formula were verified by comparison with the experimental test result. Generally 2-way valve systems are constructed as a bleed-off circuit, while 3-way valves are used as a control element in a meter-in circuit pressure control system. In a bleed-off circuit, the system supply pressure from a hydraulic power pack does not remain constant, but changes according to their external load. In turn, the relief valve in the hydraulic power pack reacts accordingly showing complicated dynamic behavior, which makes an analytical study difficult. In order to resolve the problem, simple but accurate empirical dynamic models fer a bleed-off system were used in the course of formula derivation. As the result, selection criteria for two major control parameters of the driving signal is established and the basic strategy to suppress the unnecessary pressure fluctuation can be provided for a hydraulic pressure control system using a 2-way on/off solenoid valve.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.281-286
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• 1998

In this paper, a Helmholtz resonator type hydraulic filter is proposed to absorb flow and pressure ripple produced from a axial piston pump. The basic principle of hydraulic filter is applied to propagation of preossure waves, reflection, absorption in cross section of discontinuity and resonance in the pipeline. This filter has advantage of the compact size and high degree of freedom of installation. The design scheme of hydraulic filter based on viscous wave theory are developed and manufactured two kinds of filter to investigate damping capability. It is experimently confirmed that these filter is absorbed to be about 20dB of flow and pressure ripple with high frequencies.

• 한국자동차공학회논문집
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• 제12권1호
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• pp.174-183
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• 2004

A program to analyze the performance characteristics of a hydraulic shimmy damper for automotive steering system was developed in this study. Dimensionless mathematical equations of the dynamics of shimmy damper for forward and reverse fluid flows were derived respectively and incorporated into the Simulink models. The program was validated by comparing the results of simulation and experiments for various frequencies of upstream ripple pressures into the damper. Low-pass filter characteristics of the shimmy damper at reverse flow was demonstrated which means that the shimmy damper could alleviate the high speed ripple pressures induced by the unbalance oscillation of tire in vehicle driving. The parameter sensitivity analysis was also conducted to identify the dominant parameters for the damper performance.

• 드라이브 ㆍ 컨트롤
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• 제4권3호
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• pp.38-46
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• 2007

• 드라이브 ㆍ 컨트롤
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• 제7권3호
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• pp.29-39
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• 2010

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

• 한국정밀공학회지
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• 제26권4호
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• pp.55-63
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• 2009

This paper reports on the theoretical and experimental study of the pressure ripples in a pressure unbalanced type vane pump which have widespread use in industry. Because they can infinitely vary the volume of the fluid pumped in the system by a control. Pressure ripples occur due to the flow ripples induced by geometry of side plate, leakage flow, reverse flow from the outlet volume produced by pressure difference between pumping chamber and outlet volume when the pumping chamber connected with the outlet volume. In this paper, we measured the pressure variation of a pumping chamber, reaction force on a cam ring, the mathematical model for analyzing the pressure ripples which included vane detachment and fluid inertia effects in notch area has been presented, and was applied to predict the level and the wave form of the pressure ripples according to operating conditions.

• 전기학회논문지
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• 제56권10호
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• pp.1751-1756
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• 2007

This paper presents a high performance pressure control scheme for SR(Switched Reluctance) type hydraulic oil pump using DITC(Direct Instantaneous Torque Control). SR drive has a good feature for pump applications due to a high efficiency, high speed and high torque characteristics. But, SR drive has high torque ripple in commutation region. So, the pump pressure variation is high in the region. In order to reduce the pressure variation, DITC combined with pressure control scheme is presented in this paper. A simple PI controller with flow and pressure limit, generates a reference torque to keep the constant actual pump pressure. The direct torque controller of SR drive generates inverter switching signals according to a control rule and a torque estimator. Computer simulation and experiemtal results show the validation of the proposed control scheme.

• 유공압시스템학회논문집
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• 제7권1호
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• pp.1-5
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• 2010

This paper presents the experimental results of the radial piston type oil pump with new mechanism for a metal diaphragm hydrogen compressor. Generally, metal diaphragm type hydrogen compressor systems are operated by oil hydraulic power. In this system an oil compensating pump has been demanded to compensate for a leakage oil head chamber. The metal diaphragm type hydrogen compressor consists of an oil compensating pump, commonly used hydraulic piston pump and driven by main crank shaft. The radial piston type oil compensating pump with new rolling contacted piston mechanism is developed and experimented. The developed piston element of the radial piston pump consists of piston, steel ball, return spring, two check valves, eccentric cam and ball racer. In this study, designed 4 type pistons as and orifice hole. Operating characteristics and pressure ripple characteristics are tested under no load to 60bar loaded with every 20bar increasing step and pressure ripple and flow rate are experimentally investigated.