• 설비공학논문집
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• 제14권4호
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• pp.293-303
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• 2002

For successful design of component, performances of one-tank plate type evaporator, gas-liquid separation type condenser, swash plate type compressor and thermostatic expansion valve for automotive air conditioner are investigated experimentally. Heat transfer characteristics in the evaporator are examined by means of air temperature, relative humidity, air volume flow, outlet refrigerant pressure and superheat, and heat transfer characteristics in the condenser are examined by means of air temperature, air velocity and inlet refrigerant pressure. Pressure drops for both evaporator and condenser are measured arid empirical correlations are derived. Volumetric efficiencies and isentropic efficiencies for trio types of compressors with different capacity are measured and compared. Thermostatic expansion valve is tested to investigate the pressure variation according to temperature changes.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.329-334
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• 2003

Design of pre-compression region(trapping region) of the valve plate is an important element to minimize the pressure fluctuation in a cylinder and in discharge process, and pump noise. In this study, we tried to prove what the characteristics of the oil hydraulic pump would be according to the angle of the trapping region. Three kinds of asymmetrical valve plates were used. As a result, we found that by designing the trapping region, the slope of the pressure rise in the cylinder port from low-pressure suction region to high-pressure discharge region is relaxed and the pressure fluctuation width and the discharge pressure pulsation are reduced. Therefore, because the pump gets smooth pressure fluctuation and low fluid Impact, the pump noise is reduce.

• 한국정밀공학회지
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• 제18권1호
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• pp.74-81
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• 2001

Dynamic pressure is one of the major sources on noise emission in oil hydraulic piston pump. This paper reports an experimental study of dynamic pressure characteristics in the cylinder bore of oil hydraulic piston pump. We experimently measured dynamic pressure at BDC with delivery pressure, rotational speed and oil temperature. Because the V-grooves at the ends of the kidney ports with three types valve plates. We hope this paper help to design of the valve plate in oil hydraulic piston pump.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.52-64
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• 1996

This paper presents an active position control of a single-rod cylinder system featuring an electrorheological(ER) fluid-based valve. The ER fluid consisting of silicone oil and chemically treated particles is firstly composed and its Bingham property is tested as a function of imposed electric field. A multi-channel plate type of ER valve is then designed and manufactured on the basis of the field-dependent Bingham model. Performance test of the ER valve is undertaken by evaluating pressure drop with respect to the number of electrode as well as the intensity of the electric field. Subsequently, the ER valve-cylinder system is constructed and its governing equation of motion is derived. A neural control scheme for position control of the cylinder is formulated by incorporating proportional-plus-derivative(PD) controller and implemented. Experimental results of both regulating and tracking control responses are presented in order to demonstrate the efficacy of the proposed ER valve-cylinder control system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1123-1126
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• 2003

In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-Valve are measured by varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. The pressure drop according to the strength of electric field by differential pressure gauge in the present ER-Valve was used. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.358-365
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• 2006

The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to $40\sim50%$.

• 항공우주시스템공학회지
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• 제12권2호
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• pp.7-14
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• 2018

본 연구에서는 소형 압전유압펌프가 적용된 브레이크 시스템의 부하압 개선을 위해 체크밸브에 대한 연구를 수행하였다. 가압 과정에서 부하의 정상상태 압력은 챔버압과 부하압이 체크밸브에 작용하는 단면적 비에 영향을 받는다. 체크밸브 유로 덮개는 역류 방지를 위해 유로의 단면적보다 넓게 제작되었기 때문에 단면적 비 조절을 위해 박판 스프링 형 체크밸브에 부가질량을 부착하는 방식을 제안하였다. 부가질량 부착에 의한 부하압 개선 효과를 확인하기 위해 상용코드를 이용하여 소형 압전유압펌프가 적용된 단순 브레이크 시스템의 모델링을 수행하였다. 모델링의 검증을 위해 부가질량이 부착되지 않은 박판 스프링 형 체크밸브를 적용한 펌프의 가압 실험결과와 시뮬레이션 결과를 비교하였다. 검증된 아메심 모델링에 부가질량을 추가하였고 시뮬레이션을 통해 단면적 비 조절에 의한 고 부하압 형성 효과를 확인하였다. 부가질량 추가에 따른 소형 압전유압펌프 구성품을 새롭게 설계/제작한 후 브레이크 시스템의 가압 성능 실험을 수행하여 부하압 35% 의 성능 개선을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.828-833
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• 2003

This work analyzes the effects of the independent variation of different geometric dimensions of compressor valves on the effective flow and force areas using a circular valve plate, such as different geometry of the valve seat, and the valve reed is opened and closed by pressure pulsation, the flow characteristic of the refrigerant passing the valve is very important. In the present study, a circular disk with inclination is assumed to be the valve reed of a reciprocating compressor and numerical analysis of three dimensional velocity fields are performed for theradial flow through the valve model. The effective flow and force area which are required to predict the efficiency of the valve are required to predict the efficiency of the valve are measured and compared with the numerical analysis in this research.

• 한국정밀공학회지
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• 제16권12호
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• pp.31-39
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• 1999

Previous researches and experiments have already verified that the primary noise source of high pressure tandem axial thpe piston pump is fluid-borne noise from the process of oil distribution between the kidney-shaped port and valve plate. So, many researchers have improved pressure gradients and reduced sound levels by applying pre-compression and pre-decompression metering grooves to valve plate. In practice however, the sound level of th high pressure tandem axial type piston pump is still undesirable. This paper testified the effect of pumping phase of the piston on vibration and noise of th high pressure tandem axial type piston pump on the best of theoretical research in $this^(1)$. Therefore considering the pumping phase of the piston when assembling the tandem axial type piston pump, it is possible to reduce 1.5~2[dB]of sound level.

• 유공압시스템학회논문집
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• 제6권3호
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• pp.1-9
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• 2009

Noise reduction for hydraulic pump is strongly demanded in the market with its efficiency and durability. In order to meet this demand, it is necessary to reveal mechanism for noise and relationship between the important factors. In this paper, mathematical model for cylinder pressure which is primary reason of pulsation and sound noise were established, and examined its pressure profile by simulation. Also, the valve plate of three kind types are manufactured and tested for piston pressure, pressure pulsation, and sound power level based on the tentative standard which is officially recognized.