• 제목/요약/키워드: high pressure cylinder

검색결과 423건 처리시간 0.027초

승용 디젤 엔진의 실린더 차이 압력을 이용한 IMEP 추정 및 제어 알고리즘 개발 (Development of IMEP Estimation and Control Algorithm Using In-Cylinder Difference Pressure for Passenger Diesel Engines)

  • 정재성;오승석;박인석;선우명호
    • 대한기계학회논문집B
    • /
    • 제36권9호
    • /
    • pp.915-921
    • /
    • 2012
  • 이 연구에서는 실린더 압력과 모터링 압력의 차이인 차이 압력(difference pressure)을 이용하여 IMEP를 추정하는 방법을 제안하고, 추정된 IMEP를 $IMEP_{diff}$로 정의하였다. $IMEP_{diff}$는 차이 압력이 연소 시작 시점에서 연소 종료 시점까지만 존재하는 압력이라는 사실에 기반하여 이론적인 IMEP 계산식의 연산 구간을 최적화한 것으로 IMEP와 비교 시 $R^2$ 0.9955의 높은 선형관계를 보였다. 또한 이론적인 IMEP 계산 방법과 비교하여 21 %의 실린더 압력 데이터 및 31 %의 계산량만으로 IMEP 획득이 가능하여 실시간 제어에 용이하다. $IMEP_{diff}$ 추정 및 제어 성능은 엔진 실험을 통하여 검증하였으며, $IMEP_{diff}$ 제어를 통하여 실린더 간 토크 편차 감소를 확인하였다.

공기압 실린더 고속 구동시스템에서 파라미터 변화에 따른 쿠션성능 비교 (Comparison of Cushion Performance on Parameter Changes in High Speed Pneumatic Cylinder Driving System)

  • 김도태;장중걸
    • 드라이브 ㆍ 컨트롤
    • /
    • 제12권4호
    • /
    • pp.54-59
    • /
    • 2015
  • Due to the tendency to use high speed pneumatic cylinders to improve productivity, cushioning devices are adopted to decelerate the piston motion of pneumatic cylinders to reduce noise, vibration, and impact. This paper presents a comparison of the cushion characteristics of a high speed pneumatic cylinder with a relief valve type cushioning device. The system parameters selected are the damping coefficient, Coulomb friction, heat transfer coefficient, and cracking pressure of the relief valve in the air cushioning device. The integral of the time multiplied square error (ITSE) is used to quantitative measure the cushioning performance to assess the effect of varying these. The cushioning performance achieved good results when the ITSE is a minimum value. In a comparison of the piston displacement and velocity with the variations in system parameters, the heat transfer coefficients are not as significantly affected as the other. Also, the cracking pressure of the relief valve is mainly affected by the pressure and temperature in the cushion chamber.

COMPUTATION OF AERODYNAMIC SOUNDS AT LOW MACH NUMBERS USING FINITE DIFFERENCE LATTICE BOLTZMANN METHOD

  • Kang H. K;Tsutahara M;Shikata K;Kim E. R;Kim Y. T;Lee Y. H
    • 한국전산유체공학회지
    • /
    • 제10권1호
    • /
    • pp.8-15
    • /
    • 2005
  • Aerodynamic sounds generated by a uniform flow around a two-dimensional circular cylinder at Re=150 are simulated by applying the finite difference lattice Boltzmann method. Thethird-order-accurate up-wind scheme (UTOPIA) is used for the spatial derivatives, and the second-order-accurate Runge-Kutta scheme is applied for the time marching. We have succeed in capturing very small pressure fluctuations with the same frequency of the Karman vortex street compared with the pressure fluctuation around a circular cylinder. The propagation velocity of the acoustic waves shows that the points of peak pressure are biased upstream due to the Doppler effect in the uniform flow. For the downstream, on the other hand, it is faster. It is also apparent that the amplitude of sound pressure is proportional to r /sup -1/2/,r being the distance from the center of the circular cylinder. To investigate the effect of the lattice dependence, furthermore, 2D computations of the tone noises radiated by a square cylinder and NACA0012 with a blunt trailing edge at high incidence and low Reynolds number are also investigate.

직접분사식 디젤기관의 연소실내 공기유동강화가 연소과정에 미치는 영향 (The Effect of Combustion Process by Intensifying the Air Flow in Combustion Chamber of D.I. Diesel Engine)

  • 방중철
    • 한국자동차공학회논문집
    • /
    • 제15권5호
    • /
    • pp.153-159
    • /
    • 2007
  • The performance of a direct-injection type diesel engine often depends on the strength of air flow in the cylinder, shape of combustion chamber, the number of nozzle holes, etc. This is of course because the process of combustion in the cylinder was affected by the mixture formation process. In the present paper, high speed photography was employed to investigate the effectiveness of holes penetrated from the bottom of cavity wall to piston crown for some more useful utilization of air. The holes would function to improve mixing of fuel and air by the increase of air flow in the cylinder. The results obtained are summarized as follows, (1) Activated first of the combustion by shorten of ignition timing and rapid flame propagation (2) Raised the combustion peak pressure, more close to TDC the formation timing of peak pressure.

스파크 점화 기관에서 밸브오버랩이 잔류가스율 변화에 미치는 영향 (Effect of Operating Conditions on the Residual Gas Fraction in an SI Engine)

  • 장진영;박용국;배충식;김우태
    • 한국자동차공학회논문집
    • /
    • 제10권6호
    • /
    • pp.11-18
    • /
    • 2002
  • Residual gas fraction in an engine cylinder affects engine performance, efficiency and emission characteristics. With high residual gas fractions, a flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. In this work, the residual gas fraction was calculated by an engine simulation code, which was validated by the experimental data (cylinder pressure and emissions) obtained from 4-cyliner spark ignition engine. A comparison between experimental and computational calculation results was made. The residual gas is generated mostly at low engine speed by the larger pressure difference between the intake and exhaust port. As the valve overlap duration was increased, the amount of residual gas in the cylinder, the amount of HC emission in the exhaust gas and the variation of power output increased.

건설기계용 유압실린더 위치 제어시스템의 성능개선에 관한 연구 (A study on performance improvement of position control system in hydraulic cylinder for heavy construction machinery)

  • 한석재;박성환;이진걸
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
    • /
    • pp.1450-1454
    • /
    • 1996
  • Even though digital control type high speed solenoid valve is a little inferior to analog control type servo valve and proportional control valve in performance, it is cheap and has secure performance against pollutant and simple control circuit. But high speed solenoid valve is hardly used for heavy machinery instead of servo valve or proportional control valve that is used in severe condition because the valve itself is small capacity and it shows wide dead zone during on-off control and chattering of hydraulic cylinder by chattering of pressure. It is desirable to use low-priced and strong pollutant resistant high speed solenoid valve for obtaining reliability of operation from severe working condition because it isn't necessary to acquire response characteristic of high frequency when we consider the characteristic of heavy machinery operation. In this study, PWM control algorithm for pilot pressure control of large capacity pilot operating valve will be used for precision position control of heavy machinery hydraulic cylinder. Not only cost reduction of main control valve but also high reliability of heavy machinery in severe condition can be obtained by using this pilot operating spool valve with high speed solenoid valve.

  • PDF

고해상도수치기법에 의한 원형실린더 주위의 3차원 후류유동 특성연구 (High order computation on the three dimensional wakes past a circular cylinder)

  • 이상수;김재수;김태수
    • 한국전산유체공학회:학술대회논문집
    • /
    • 한국전산유체공학회 2008년도 춘계학술대회논문집
    • /
    • pp.622-625
    • /
    • 2008
  • While the research for flow over a circular cylinder has been actively carried out up to the present, it has been known that the flow has not been clarified even now. Various complex flow and aero-acoustic characteristics exist around a circular cylinder such as flow separation, wake and pressure wave propagation. In this paper, research was carried out for wake flow and aeroacoustics over a circular cylinders by using high order, high resolution techniques that are used in two dimensional aero- acoustic analysis. OpenMP parallel processing method was used. For the numerical result, the periodic characteristic of Strouhal Number due to vortex shedding was comparatively analyzed with other experiment values and two dimensional numerical results.

  • PDF

직분식 전기점화 엔진에서 PLIF기법에 의한 성층 혼합기의 분포특성 연구 (Study on the Fuel Vapor Distribution of the Stratified Charge in a DISI Engine by PLIF Technique)

  • 김성수
    • 동력기계공학회지
    • /
    • 제12권6호
    • /
    • pp.64-69
    • /
    • 2008
  • The spatial fuel distribution of the stratified charge of a high pressure 6-hole injector was examined in a single cylinder optical direct injection spark ignition(DISI) engine. The effects of in-cylinder charge motion, and fuel injection pressure, and coolant temperature were investigated using a planar LIF(Laser Induced Fluorescence) technique. It was confirmed that the in-cylinder tumble flow played more effective role in the spatial fuel distribution of the stratified charge than the swirl flow during the compression stroke and the fuel distribution area increased due to the activation of the fuel vaporization by the increase of the coolant temperature. But, the increase of the fuel supplying pressure could not change the pattern of the fuel vapor distribution against the expectation.

  • PDF

고압용 ACGT 시일의 접촉거동 특성에 대한 유한요소 해석 (on Contact Behaviour Characters of ACGT Seal for High pressure using Finite Element Analysis)

  • 최동열;김성원;김청균
    • 한국윤활학회:학술대회논문집
    • /
    • 한국윤활학회 2001년도 제34회 추계학술대회 개최
    • /
    • pp.350-355
    • /
    • 2001
  • Minimum clearance between the piston seal groove of a piston and cylinder bore to ensure against extrusion of the piston seal and leakage of working fluids is an important design parameter for a seal designer in hydraulic cylinder application. Contact force, critical pressure at which extrusion occurs, leakage rate, fluid film thickness and friction force have been analyzed for some design parameter such as clearance between cylinder wall piston, depth of rectangular groove and pressure of sealed hydraulic fluid. In this paper, we analyze displacement and stress of ACGT seal by finite element analysis to understand Contact Behaviour Characters

  • PDF

SI 엔진의 텀불 유동과 화염전파 (Tumble flow motion and flame propagation in a SI engine)

  • 지명석
    • 한국산업융합학회 논문집
    • /
    • 제2권2호
    • /
    • pp.155-163
    • /
    • 1999
  • In this study, single cylinder engines with different tumble ratio were made to find out in-cylinder fluid motion and flame propagation. Tumble ratio derived from the steady state flow rig test. Flame propagation speed was obtained using cylinder head gasket ionization probe and the piston ionization probe. And the combustion pressure in cylinder was measured to analyze the combustion characteristics. In case of high tumble engine, BSFC and BSHC were decreased and BSNOx was increased at part load test. Also BMEP and combustion peak pressure was increased at full load test. Tumble flow motion had an great effects on initial burning period rather than main burning period in part load test.

  • PDF