• Title/Summary/Keyword: Valve plate

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Hybrid control of the swash plate-type variable displacement hydraulic piston pump for an EHA (EHA용 가변용적형 사판식 유압 피스톤 펌프의 하이브리드 제어)

  • Kwon, Yong-Cheol;Hong, Yeh-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.4
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    • pp.291-298
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    • 2013
  • In this paper a new hybrid-type control system is proposed which reduces the pump speed of an electro-hydraulic actuator consisting of a pressure-compensated variable displacement piston pump and a valve-controlled hydraulic cylinder, whenever the flow rate demand is low. In order to avoid interfering with the pressure regulator which also has an effect on swash plate angle, the pump speed is changed in proportion to the mean value of the speed component of position commands. Additionally a pressure switch is employed to prevent the system pressure from getting lower than a reference value. Based on computer simulation & experimental results, it is shown that the hybrid control can save the idling power up to 44% at a stand-by mode by reducing the pump speed from 1,800 rpm to 600 rpm without affecting the dynamic response of the electro-hydraulic actuator.

A Study on Characteristics of a Compensator System for Swash Plate Type Axial Piston Pump (사판식 액시얼 피스톤 펌프의 가변용량 시스템의 특성에 관한 연구)

  • Kim, Shin;Oh, Suk-Hyung;Jung, Jae-Youn
    • Tribology and Lubricants
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    • v.14 no.4
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    • pp.15-22
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    • 1998
  • Recently, the importance of variable displacement piston pump is increasing in industrial world. Especially, most consumers require various range of pressures and flow rates. Pressure compensator is a system controlling flow rate in piston pump at low cost and, therefore, satisfies the need of consumers. However, the system has serious problems, such as response and leakage. The response and leakage are affected by clearance between actuator piston and cylinder, roughness of surface, and spool overlap. In this paper, these effects are investigated experimentally, and optimal clearance and chamfer is obtained. While diameter of cylinder is fixed and diameter of actuator piston is changed in this experiment, response and leakage are measured. Also parameters such as roughness and processing accuracy are changed for piston of fixed clearance. Experimental setup modelled into several parts of actuator piston, cylinder, spool, and swash plate. Input pressure is changed by function generator and proportional valve. The result of this experiment shows that leakage increases very much in proportion to the increase of clearance, and especially leakage occurs enormously when clearance is more than 0.002. The response is not good because as clearance increases leakage increases and as clearance decreases viscous damping effect increases. Accordingly, it is found out that optimal clearance range exists for tile response, within about 0.0012∼0.0014, at this time. Futhermore, the better roughness and geometrical accuracy of actuator piston are, the smaller are leakage and friction. The paper informs that response and leakage are influenced by and geometrical accuracy of actuator piston, roughness of surface, and the clearance between actuator piston and cylinder, and that optimal design of actuator piston in the pressure compensator is possible.

Tribological Failure Analysis of Automatic Transmission in a Passenger Car (승용차 자동변속기의 고장사례에 관한 트라이볼로지적 고찰)

  • Kim, Chung-Kyun;Lee, Il-Kwon
    • Tribology and Lubricants
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    • v.21 no.5
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    • pp.227-235
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    • 2005
  • This paper presents a tribological study on the failure cases of automatic transmission components in a passenger car. The automatic transmission system is composed of torque converter, clutch, brake, planetary gear, and valve body controlling oil pressure of an automatic transmission fluid. The most largest influence components in an automatic transmission are a torque converter and clutch plate in which are influenced by a wear and torque converting energy loss. The failure case study of an automatic transmission indicates that the tribological design and maintenance technologies should be considered as a key design concept. This means that the failure and power energy loss come from the friction, wear and a oil leakage of an automatic transmission, which is related to the oil seal and O-ring seal failures.

A New Record of Sea Urchin (Echinoidea: Stomopneustoida: Glyptocidaridae) from the Yellow Sea, Korea

  • Lee, Taekjun;Shin, Sook
    • Animal Systematics, Evolution and Diversity
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    • v.29 no.4
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    • pp.312-315
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    • 2013
  • Sea urchins were collected from waters adjacent to Daludo Island and Mohang harbor in the Yellow Sea, and were identified into Glyptocidaris crenularis A. Agassiz, 1864, of the family Stomopneustidae within the order Stomopneustoida, based on morphological characteristics. This species has two unique morphological characteristics: the ambulacral plate is composed of three primary plates and two demi-plates, and a valve of globiferous pedicellaria consists of with a well-developed long terminal hook and a unique stalk equipped with one to six long lateral processes covering membranes, resembling fins. It is newly recorded in Korea and is described with photographs. This brings the total number of sea urchins reported from the Yellow Sea, Korea, to seven.

Evaluation of the Laser Weldability of Inconel 713C alloy (인코넬 713C 합금의 레이저 용접성 평가)

  • Kang, Minjung;Kim, Cheolhee;Kim, Young-Min
    • Journal of Welding and Joining
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    • v.35 no.1
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    • pp.68-73
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    • 2017
  • During welding of Ni based superalloy, hot cracking was usually happen in the fusion zone of a weld. In this study, the laser weldability of Inconel 713C alloy for the turbocharger wastegate valve (WGV) was evaluated with various welding conditions, such as laser power, welding speed, shielding gas. Welding conditions were optimized by bead-on-plate (BOP) and butt joint welding. For the evaluation of laser weldability, bead shapes and weld microstructures were investigated and tensile test was conducted. The fracture surfaces were investigated for the understanding the cause of the fracture.

A Study on Design and Control of Electro-Hydraulic Pump System (전기.유압펌프 시스템의 설계 및 제어에 관한 연구)

  • 박성환;하석홍;이진걸
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.4
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    • pp.1062-1070
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    • 1995
  • The study deals with controlling the velocity of hydraulic motor with PI controller through the control of displacement pump which has higher efficiency than valve-controlled system. This was done as follows. First, we modified original displacement pump and designed this electrohydraulic puma system. Second, after experimenting static and dynamic characteristics, we identified system parameter of approximated model. Lastly, to control the velocity of hydraulic motor we controlled the angle of the swash plate of displacement pump. Test carried out in the laboratory shows that transient and steady state response could be improved by PI controller reducing power loss.

A Study on Flow Characteristics of ERF Between Two Parallel-Plate by Using PlV (평형평판 간극사이에서 PIV를 이용한 ER유체의 유동특성에 관한연구)

  • Jung Wan-Bo;Park Young-Seuk
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.1
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    • pp.56-62
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    • 2006
  • An experimental investigation was performed to study the characteristics of ER(Electro-Rheological) fluid flow in a horizontal rectangular tube with or without D.C voltage. To determine some characteristics of the ER flow, 2D PIV(Particle Image Velocimetry) technique is employed for velocity measurement. This research found the mean velocity distribution with 0kV/mm, 1.0kV/mm and 1.5kV/mm for Re = 0, 0.62, 1.29 and 2.26. When the strength of the electric field increased, the cluster of ERF are clearly strong along the test tube and the flow rate decreased. In this study, the rheology of ER fluid stagnating or flowing through a dispersion meter will be investigated by PIV method. And then the ER effect, which appears at the ER valves and their appliance will be visualized.

An Experimental Study on the Performance of Automobile Air Conditioning System with Variations of Charging Conditions (냉매충전량 변화에 따른 자동차에어컨 성능의 실험적 고찰)

  • 이건호;정종대;최규환;유정열
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.2
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    • pp.203-211
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    • 1998
  • The system performance of an automobile air conditioning system with variations of charging conditions has been investigated experimentally. An automobile air conditioning system was composed of laminated type evaporator, parallel flow type condenser, swash plate type com-pressor, externally equalized thermostatic expansion valve and receiver drier. The objective of this study was to quantify the influence of the refrigerant charge under the steady state operation of an automobile air conditioning system. The results indicated that a 10% undercharge caused a 10% reduction in the capacity of evaporator.

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A study on dynamic characteristics of sheet type check valves in PZT pump for small liquid delivery (미소유체 이송용 압전펌프를 위한 시트형 체크밸브의 동특성에 관한 연구)

  • Ham Y.B.;Noh J.H.;Shin D.S.;Park J.H.;Kim H.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1087-1090
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    • 2005
  • In precision machinery systems for medical and chemical applications, micropumps with a low pulsation have been demanded and investigated for accurate delivery of a small amount of liquid. This study proposes sheet type check valves instead of ball type check valves for PZT pumps and performs some tests on dynamics characteristics of check valves having different design parameter with variable frequency. The selected materials of check valves is NBR, PP film, Polyimide and Stainless steel(SUS304). In the experiment, dynamic characteristics of stainless steel thin plate have better performance than others.

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Fabrication of Biochip Using Gray-scale Photolithography (Gray-scale photolithography를 이용한 바이오칩 제작)

  • Bae, Young-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.1
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    • pp.137-141
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    • 2008
  • Biochip, which implements bioanalytical process on a tiny surface, is one of candidates for medical diagnosis, drug screening, and molecular sensing. In general, a type of biochip based on microfluidics is composed of microcomponents including microchannel, pump, and valve, which require complicated processes. In this study, gray-scale photolithography(GSPL) was applied to fabricate a biochip with multiple layers. A mould for casting PDMS(polydimethylsiloxane) channel, was fabricated using GSPL. A gray-photomask was prepared by printing gray patterns on a high-quality glossy paper followed by photoreducing by 10:1 onto the photo-film. The formation of multiple layers was studied according to the change of gray level of pattern and the developing time. A biochip composed of a weir(multiple layer structure) and a reaction chamber in a single microchannel was fabricated in a glass plate. Finally, we investigated the application of biochip to antigen-antibody reaction by packing the microbead coated with antibody.