• 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.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.179-184
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• 2003

It has been recognized that the compressibility of hydraulic fluid, which is characterized by the value of its bulk modulus, heavily affects on the system behavior and performance. In practice, the value of the oil bulk modulus varies by the operational and structural characteristics of the hydraulic system. This study presents the theoretical derivation of the effective bulk modulus and describes an experimental impulse technique that allows accurate measurement of oil effective bulk modulus with pressure variation in a hydraulic system. Experimental and analytical results show that the value of the effective bulk modulus varies a lot in low pressure region by the effect of entrained air, while the effective bulk modulus can be estimated just using the oil and container bulk modulus on the other high pressure region.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2024-2030
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• 2003

Design for a quite operation of fluid power system requires the understanding of noise and vibration characteristics of the system. This paper presents a dynamic response for design of hydraulic circuit. Experimental investigations on the attenuation characteristics of pressure ripple in automotive power steering hydraulic pipe with dynamic response of hydraulic pipe line is examined. Also, a mathematical model of hydraulic pipe is proposed to support design of the hydraulic circuit and analyze the attenuation characteristics of pressure ripples in a hydraulic pipe line. And analyze the impedance characteristics to determine the postion to construct accumulator for attenuation the pressure pulsation. The experimental results show that the pulsation attenuation characteristics of hydraulic hoses is remarkably affected by the flexible metal tube inserted coaxially inside a hydraulic hose with a finite length as well as viscoelastic properties of hose wall. It is also shown that the predicted results by the model proposed here agree well with the measured results over a wied range of frequency;

• 드라이브 ㆍ 컨트롤
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• 제13권3호
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• pp.39-46
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• 2016

Flow and pressure ripple in swash plate type piston pumps is largely dependent on the design of notches(silencing grooves) in the valve plate. In uni-directional pumps, the basic design concept for notches in the valve plate could be said to be established. It is easily deduced that the design concept for notches in uni-directional pumps can not be simply applied to bi-directional pumps requested for EHA(electric hydrostatic actuators). To carry out systematic research on technological issues regarding notch applications to bi-directional piston pumps, five notch designs are devised. The effects of the notch designs on the characteristics of the pump are investigated by numerical simulations and experiments. Through this study, basic concepts about notch design for bi-directional piston pumps are suggested.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.158-165
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• 2008

Hydraulic power steering system has been adopted in seniority passenger and commercial vehicle system for an easy maneuverability and a smoother ride. In this study, hydraulic power steering system analysis model which includes hydraulics and mechanical sub-systems was developed using commercial software, AMESim in order to predict characteristics for various steering components. Each component which constructs system was modeled and verified by experimentally obtained characteristics curves of each components. The agreement between simulation and experimental results shows the validity of the simulation model. The parameter sensitivity analysis such as valve opening area, torsional stiffness for system design are carried out by the analysis and experimental method.

• 한국정밀공학회지
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• 제15권1호
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• pp.87-93
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• 1998

Pressure ripples of hydraulic vane pump results from flow ripples due to pump geometry and reverse flow through the discharge port due to compressibility of fluid and result in vibration and noise of connected hydraulic elements. In a balanced type vane pump, cam ring curve is important factor to influence the flow ripples. Therefore, to reduce the flow ripple, it has been required that optimal selection of seal region by proper design of cam ring and each port position, and notches for preventing the excessive reverse flow. This paper has been performed analytical study of compression characteristics with major design parameter in side plate and cam ring. and examined into the role of notch and radius reduction ratio.