• Title/Summary/Keyword: Piston offset

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A Study on the Effect of Piston Pin Offset on a Piston Motion and Kinetic Energy Loss (피스톤핀 옵셋이 피스톤운동과 운동에너지 손실에 미치는 영향에 관한 연구)

  • Han, D.J.;Choi, J.K.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.1 no.3
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    • pp.22-33
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    • 1993
  • A theoretical analysis of predicting the detailed motion of a piston-crank mechanism within piston-guide clearance is presented, and the analysis is applied to the piston motion in a gasoline engine. A piston movement program is developed to calculate the piston attitude relative to the bore, the piston to bore impact velocity and kinetic energy loss and the net transverse force acting on the piston. This paper presents the formulation of a set of differential equations governing the transverse and rotational motion of a piston. These equations of motion were solved by well established Runge-Kutta method. As a result of this study, it is possible to predict the effects of piston geometry and piston pin offset on a piston motion and kinetic energy loss.

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The Friction Characteristics of Crank Offset Engine : Theoretical Investigation (크랭크 오프셋 엔진의 마찰 특성 : 이론적 고찰)

  • Jo, Myeong-Rae;O, Dae-Yun;Kim, Jung-Su;Ha, Gyeong-Pyo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.8
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    • pp.1591-1598
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    • 2002
  • This paper reports on the effects of crankshaft offset on the engine friction. The effects of crank offset are investigated through the theoretical analysis. In this study, the mathematical models are presented fer evaluationg the friction level of each engine parts. Crank offset influences on the side force acted on the piston pin and sliding speed of piston. Crank offset is very effective to reduce the piston skirt friction. With application of crank offset, total engine friction decreases at low engine speed, but that increase as engine speed increases.

Analysis of the Effects of Bore Clearance Due to Skirt Profile Changes on the Piston Secondary Movements

  • Jang, Siyoul
    • KSTLE International Journal
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    • v.3 no.2
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    • pp.84-89
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    • 2002
  • Clearance movements of engine piston are very related to the piston impact to the engine block as well as many tribological problems. Some of the major parameters that influence these kinds of performances are piston profiles, piston offsets and clearance magnitudes. In our study, computational investigation is performed about the piston movements in the clearance between piston and cylinder liner by changing the skirt profiles and piston offsets. Our results show that curved profile and more offset magnitude to thrust side have better performance that has low side impact during the engine cycle.

Simulation of Secondary Motion of Piston Assemblies (피스톤 어셈블리의 2차 운동에 관한 시뮬레이션)

  • 오병근;조남효
    • Journal of the Korea Institute of Military Science and Technology
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    • v.3 no.2
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    • pp.231-243
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    • 2000
  • This paper describes a simulation of secondary motion of piston assemblies using PISDYN by Ricardo. Motions of the piston, pin, rod and skirt are separately calculated, by integrating equations of motion for individual components and dynamic degrees of freedom. The effects of engine speed at full load and pin offsets on the piston assembly secondary motions, forces and friction were investigated in parametric study for 4-cylinder gasoline engine. Results show that lateral displacement and friction loss of the piston increase as a function of engine speed. The lateral motion of the piston is affected by the change in pin offset. The minimum friction loss for the condition of 4800rpm WOT occurs at a pin offset of 1.6mm.

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EFFECTS OF SKIRT PROFILES ON THE PISTON SECONDARY MOVEMENTS BY THE LUBRICATION BEHAVIORS

  • Jang, S.;Cho, J.
    • International Journal of Automotive Technology
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    • v.5 no.1
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    • pp.23-31
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    • 2004
  • Secondary movements of piston in the bore clearance are closely related to the side impact to the engine block as well as many tribological problems. Some of the major parameters that influence these kinds of movements are piston profile shapes (barrel and flat), piston pin offsets and the magnitudes of bore clearances. In our study, computational investigations are performed about the piston movements in the bore clearance by changing the skirt profiles and piston offsets. In this work, it is found that curved profile and larger offset magnitude to thrust side provide better performance that has low side impact during the engine cycle.

Analysis of Frictional Power Loss Due to the Effects of Elastic Deformation in the Piston Skirt Profile (탄성변형을 고려한 피스톤 스커트의 마찰 손실 해석)

  • 조준행;장시열
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.11a
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    • pp.385-396
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    • 2000
  • The secondary motion of piston occurs due to the transient forces and moments in the clearances between piston skirt and cylinder liner The motions are very related to the skirt profile and the magnitude of piston-pin offset. Above all, the elastic deformation is another major effect on the piston secondary motion that has not been considered in the previous researches. In this work, the effects of elastic deformation of the piston skirt on the secondary piston motion are studied for the frictional power loss by using commercial softares, PISDYN and ANSYS.

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Study on the Clearance Design for Low Side Impacts of Engine Piston

  • Cho, Joon-Haeng;Jang, Si-Youl
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.427-428
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    • 2002
  • Clearance movements of engine piston are regarded very important because they cause impact vibrations as well as many tribological problems. Some of the major parameters that influence these kinds of performances are piston profiles, piston offsets and clearance magnitudes. In our study. computational investigation is performed about the piston movements in the clearance between piston and cylinder liner by changing the skirt profiles and piston offsets. Our results show that curved profile and more offset to thrust side have better performance with low side impact during the engine cycle.

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A Numerical Study of the Flow Field in the Combustion Chamber of the I.C Engine with Offset Valve (편심 밸브를 갖는 내연기관의 연소실 내부 유동장에 대한 수치적 연구)

  • 양희천;최영기;유홍선;고상근;허선무
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.8
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    • pp.1552-1565
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    • 1992
  • Three dimensional numerical calculations were carried out for two different combustion chambers with the offset valve in order to investigate the swirl and the squish effects on the flow fields. The modified K-.epsilon. turbulence model considering the change of the density under the condition of the rapid compression and expansion of the pistion was used. During the compression process, it was found that the squish flow which controls the subsequent combustion process was produced due to the piston bowl in the bowl piston type combustion chambers but not for the flat piston type. The swirl velocity close to the solid body rotation was maintained in the flat piston type combustion chambers, but for the bowl piston type a resulting from the change of the solid body rotation was generated in the radial-circumferential plane. For the swirl ratio effect, as the swirl ratio increases, it was found that a large and strong vortex was generated in the radial-circumferential plane of bowl piston type combustion chambers because of the strong inward flows from the combustion chamber wall. These computational results were compared with the results of LDA measurement.

A Novel Method for Calculating the Stroke of LPMSM for Driving Linear Compressor Using High Pass Filter (고역필터를 사용한 선형압축기 구동용 LPMSM의 새로운 스트로크 계산 기법)

  • Ahn, Jung-Ryol;Lee, Hong-Hee;Kim, Heung-Gun;Nho, Eui-Cheol;Chun, Tae-Won
    • The Transactions of the Korean Institute of Power Electronics
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    • v.11 no.1
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    • pp.7-13
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    • 2006
  • Linear compressors with a free piston driven by a linear motor are widely attention in the cooling apparatus such as refrigerator due to the high efficiency The stroke of piston in the linear compressor driven by LPMSM (Linear Permanent-Magnet Synchronous Motor) can be obtained from Integrating the input voltage and current of LPMSM, but it may be diverged due to dc components in the voltage and current. The strategy to prevent the divergence of stroke using both the high-pass filter and do offset compensation was suggested. The equations for the magnitude and phase of the stroke and also dc offset including the stroke are derived as a function of the cut-off frequency of HPF. The accurate stroke of a piston can be calculated by compensating for dc offset. The performance of the newly developed stroke calculation scheme has been verified by experimentally on a linear compressor drive system, where the control was implemented by a 16-bit DSP.

The Development of the Software for the Geometry Modeling and Generating CNC Machining Data of a Piston (피스톤의 형상 모델링 및 CNC 가공 데이터 산출용 소프트웨어 개발)

  • Lee, Cheol-Soo;Lee, Je-Phil;Kim, Seong-Bok
    • IE interfaces
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    • v.12 no.1
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    • pp.68-78
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    • 1999
  • A noncircular cutting such as a piston cutting has depended on the copy-machining because of its complex shape. But the copy-machining needs a master model and brings about a low quality of the piston caused by being worn out of the master model. And the lower cutting speed reduces the productivity. In this paper, for solving these problems, a specialized software system and its subsequent procedure are presented. The shape of a piston consists of an oval, an offset, recesses, and eccentricities. The paper describes these shapes as a consistent equation that is a function of the rotational angle and the position of longitudinal direction(Z-axis). It is simple to define the characteristic geometry of a piston and to generate a tool path for CNC machining. This paper proposes the a proper structure of a 4-axes CNC(Computerized Numerical Control) lathe for machining the piston. As well as X-axis and Z-axis, are attached to the machine a C-axis for rotation and a Y-axis for higher speedy prismatic motion parallel to X-axis.

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