• Title/Summary/Keyword: piston effect

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An analysis on power regeneration of hydrostatic pressure exchanger (정수압방식 동력회수장치의 구동동력 절감량 해석)

  • Ham, Y.B.;Choi, J.H.;Jeong, H.S.;Park, S.J.;Park, J.H.;Yun, S.N.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.4 no.3
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    • pp.7-12
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    • 2007
  • This paper presents an energy saving hydrostatic pressure exchanger for sea water desalination equipment. In a reverse osmosis(RO) system for desalinating sea water, more than 70 percent of the supplied sea water, brines which were impassable through RO membrane are bypassed, resulting in high energy losses. In this paper, a hydrostatic pressure exchanger consisting of an embedded water hydraulic piston motor and a water hydraulic piston pump was proposed and investigated in order to recover the energy of the bypassed brines. The pressurized brines are supplied to the embedded water hydraulic piston motor as power sources and the water hydraulic piston pump is driven by the output torque of the embedded water hydraulic piston motor as well as electric motor. Consequently, the energy of the bypassed brines can be recovered. To examine the electric energy saving characteristics of the hydrostatic pressure exchanger, a simulation model was constructed using commercial software and experiments were conducted. Through the results of simulation and experiment, the feasibility of the electric energy saving effect of the proposed hydrostatic pressure exchanger was investigated.

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Effect of Coating Layer Hardness on Frictional Characteristics of Diesel Engine Piston Ring (디젤엔진 피스톤 링 코팅 층의 경도에 따른 마찰특성)

  • Jang, J.H.;Joo, B.D.;Lee, H.J.;Kim, E.H.;Moon, Y.H.
    • Transactions of Materials Processing
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    • v.18 no.6
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    • pp.465-470
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    • 2009
  • The frictional behaviors of Cermets/Cr-Ceramics and Cu-Al coatings of piston ring were investigated. Friction tests were carried out by pin-on-disk test and materials properties of coating layer were analyzed by nano indentation tester. The effect of surface roughness of cylinder liner on the friction coefficient was analyzed. This study provided tribological data of hard and soft piston ring coatings against cylinder liner. The surface roughness does exert an influence on the average friction coefficient, with smoother surfaces generally yielding lower friction coefficients. In case of hard-coating, the scratch depth, width and pile-up height had close relationship with hardness. So the scratch width, depth and pile-up height increases with decreasing friction coefficient. But in case of soft-coating, the friction coefficients are strongly dependent on the morphological characteristics such as, scratch depth, width, pile-up height and elastic modulus.

Effect of Upset pressure on weldability in the Friction Welding of SM45C-Solid and SM45C-Pipe which is used in the Piston-Rod (경량화 피스톤 로드에 사용되는 SM45C/SM45C-Pipe의 마찰용접시 업셋압력이 미치는 영향)

  • Min, Byung-Hoon;Choi, Won-Yong;Min, Taeg-Ki
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.5
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    • pp.36-43
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    • 2008
  • This research is tendencious to manufacture solid piston-rod of shock absorber as hollow piston-rod using friction welding. The SM45C has been welded to the SM45C-pipe in order to investigate the effect of upset pressure on friction weldability. The friction time and upset pressure was variable conditions under the conditions of spindle revolution of 2,000rpm, friction pressure of 55MPa, and upset time of 2.0seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied of friction weld, and so the results were as follows. When the upset pressure is sufficient, gets the high tensile strength. The optimal welding conditions were n=2,000rpm, $P_1$=55MPa, $P_2$=95MPa, $t_1$=1.5sec, $t_2$=2.0sec when the total upset length is 4.5mm.

A study on the characteristics of dynamic pressure in cylinder pen of hydraulic axial piston pump (유압 액셜 피스톤 펌프의 실린더 포트 내부 비정상 압력특성에 관한 연구)

  • 김종기;정재연
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1999.06a
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    • pp.209-214
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    • 1999
  • Dynamic pressure is one of the major sources on noise emission in hydraulic axial piston pump. This paper reports an experimental study of dynamic pressure characteristics in the cylinder port of hydraulic axial piston pump. We investigated dynamic pressure with not only the effect of delivery pressure, rotational speed and temperature but also V-notches at the ends of the kidney ports in the valve plate. We experimented three valve plates with three type V-notches at the ends of the kidney ports, because V-notches of the valve plate is known of noise reduction. Finally, we hope this paper help to design of the valve plate in hydraulic axial piston pump.

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Development of Friction Torque Measurement Device for Spherical Hydrostatic Bearing (구면 정압베어링의 마찰토크 측정장치 개발)

  • 함영복;최영호;박경민;윤소남;김광영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.181-186
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    • 2002
  • Lately, as going on increasing in the demand of high power density(power/weight), it is necessary for hydraulic axial piston pump/motor to operate more high pressure and speed. But in these condition, there are some trouble like as friction loss. To reduce this friction loss, hydrostatic bearing is used far axial piston pump/motor frequently. In general, it is difficult to measure accurate friction torque of spherical hydrostatic bearing in the use of the existing devices. So, we have developed the measurement device using the reaction torque sensor to obtain the pure friction torque, fitted in the casing. In this report, we intend to make an introduction about this measurement device for friction torque of the spherical wear part and clarify the effect of friction characteristics on supply pressure and rotational speed with three types of pocket size by using this measurement device.

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The Lubrication Characteristics of Rotary Compressor for Refrigeration & Air-Conditioning (Part I ; The analysis of rolling piston behavior) (냉동 공조용 로터리 콤프레서의 윤활 특성 제1보 : 롤링 피스톤의 거동해석)

  • 조인성;오석형;정재연
    • Tribology and Lubricants
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    • v.12 no.4
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    • pp.43-51
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    • 1996
  • Rapid increase of refrigeration & air-conditioning system (r & a system) in modem industries brings attention to the urgency of research & development as a core technology in the area. And it is required to the compatibility problem of r & a system to alternative refrigerant for the protection of environment. Then, it is requested to study the lubrication characteristics of refrigerant compressor which is the core technology in the r & a system. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressor. Therefore, theoretical investigation of the lubrication characteristics of rotary compressor for r & a system is studied. The Runge-Kutta method is used for the analysis of the behavior of rolling piston in the rotary compressor. The results show that the rotating speed of shaft and the discharge pressure have an important effect upon the angular velocity of the rolling piston. This results give important basic data for the further lubrication analysis and design of the rotary compressor.

Pressure Variation Characteristics at Trapping Region in Oil Hydraulic Piston Pumps (유압 피스톤 펌프의 폐입구간에서 발생하는 압력변동 특성)

  • Kim, Jong-Ki;Jung, Jae-Youn;Rho, Byung-Joon;Song, Kyu-Keun;Oh, Seok-Hyung
    • 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

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A Study on the Hydrostatic Test of Slipper Pad for Hydraulic Piston Motor (유압 피스톤모터용 Slipper Pad의 정압시험에 관한 연구)

  • 함영복;김광영;김형의
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.645-649
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    • 1997
  • In case of swash plate type axial piston hydraulic motor, hydrostatic bearing used to achieve the lubrication effect on the mechanical sliding contact areas between the following parirs ; sliooer-pad and swash plate,piston and cylinder bore,valve plate and cylinder block, etc. This study discussed the basic charateristic for the hydrostatic slipper-pad bearings with the capillary or orifice restrictor under static load condition. And, we also development of hydrostatic bearing tester for hydrostatic balancing test of pistion & slipper-pad assembly, and some experimental data on supply pressure step responce are reported.

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Friction Characteristics of Piston Ring Pack with Consideration of Mixed Lubrication: Parametric Investigation

  • Kim, Ji-Young;Kim, Jee-Woon;Cho, Myung-Rae;Han, Dong-Chul
    • Journal of Mechanical Science and Technology
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    • v.16 no.4
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    • pp.468-475
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    • 2002
  • This paper reports on the friction characteristics of a piston ring pack with consideration of mixed lubrication. The analytical model is presented by using the average flow antral asperity contact model. The effect of operating condition, and design parameters on the MOFT, maximum friction force, and mean frictional power loss are investigated. Piston ring prick shows mixed and hydrodynamic lubrication characteristics. From the predicted results, it was fand that the ring tension and height of surface roughness have great influence on the frictional power losses in a ring pack. Especially, ring tension is a dominant factor for the reduction of friction loss and maintenance of oil film thickness.