• Title, Summary, Keyword: Idle stability

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Effect of Value Timing on Residual Gas Fraction and Combustion Characteristics at Part Load Condition in an SI Engine (가솔린 엔진의 밸브타이밍 변화가 부분부하 조건에서 잔류가스량 및 연소특성에 미치는 영향)

  • 김철수;송해박;이종화;유재석;조한승
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.4
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    • pp.26-33
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    • 2000
  • In-cylinde flow and mixture formation are key contributors to both idle stability and combustion stability at part load condition in SI engine. The real time measurements of air-fuel ration and in- cylinder residual gas fraction are particularly important to obtain a better understanding of the mechanisms for combustion and emissions especially during cold start and throttle transient condition. This paper reports the cycle resolved measurements of residual gas fraction and equivalence ration near speak plug with value timing change and their effects on combustion characteristics at part load. The results showed that the effect of intake value opening on the residual gas fraction was smaller than that of exhaust valve closing because of the decreases of exhaust gas reverse flow from exhaust port. The variation of equivalence ratio near spark plug increased with the increase of value overlap and it closely related with heat release rate and combustion stability

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A Study for Measurements of In-Cylinder Residual Gas Fraction using Fast Response FID in an SI Engine (스파크점화기관에서 고속응답 FID를 이용한 실린더내 잔류가스량 측정에 관한 연구)

  • 송해박;조한승;이종화;이귀영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.1
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    • pp.80-89
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    • 1998
  • The residual gas in an spark-ignition engine is one of important factors on emissions and performance such as combustion stability. With high residual gas fractions, 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. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating parameters. In the present study, the quantitative measurement technique of residual gas fraction was studied by using Fast Response Flame Ionization Detector(FRFID). The measuring technique and model for estimation of residual gas fraction were reported in this paper. By the assuming that the raw signal from FRFID saturates with the same slope for firing and misfiring cycle, in-cylinder hydrocarbon(HC) concentration can be estimated. Residual gas fraction can be obtained from the in-cylinder HC concentration measured at firing and motoring condition. The developed measurement and calibration procedure were applied to the limited engine operating and design condition such as intake manifold pressure and valve overlap. The results show relevant trends by comparing those from previous studies.

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A Study on Geotechnical Stability of the Sludge Mixed Soil (슬러지가 혼합된 지반의 공학적 안정 특성에 관한 연구)

  • Hwang, Sung-Pil;Jeoung, Jae-Hyeung
    • Journal of Korean Society of Disaster and Security
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    • v.10 no.1
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    • pp.55-60
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    • 2017
  • The dyeing sludge can be weakened by inflow of rainfall or absorption of moisture after it is buried in a waste landfill. This study tested the dyeing sludge and earth/sand mixture to check the problem when the dehydrated dyeing sludge is buried in a waste landfill. When the dyeing sludge was left idle with high water content inside a landfill with poor draining for a long period, the water permeability decreased to around 3/100 level and the compressibility increased by 1.4 times compared to the dyeing sludge at a dyeing factory. The study result indicated that it was important to reduce the water content inside the landfill for stability. Also, the facilities to secure the drainage path and eliminate leachate were needed.

Effective resource selection and mobility management scheme in mobile grid computing (모바일 그리드 컴퓨팅에서 효율적인 자원 확보와 이동성 관리 기법)

  • Lee, Dae-Won
    • The Journal of Korean Association of Computer Education
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    • v.13 no.1
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    • pp.53-64
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    • 2010
  • In this paper, we tried to enable a mobile device as a resource to access to mobile grid networks. By advanced Internet techniques, the use of mobile devices has been rapidly increased. Some researches in mobile grid computing tried to combine grid computing with mobile devices. However, according to intrinsic properties of mobile environments, mobile devices have many considerations, such as mobility management, disconnected operation, device heterogeneity, service discovery, resource sharing, security, and so on. To solve these problems, there are two trends for mobile grid computing: a proxy-based mobile grid architecture and an agent-based mobile grid architecture. We focus on a proxy-based mobile grid architecture with IP-paging, which can easily manage idle mobile devices and grid resource status information. Also, we use SIP(Session Initiation Protocol)to support mobility management, mobile grid services. We manage variation of mobile device state and power by paging cache. Finally, using the candidate set and the reservation set of resources, we perform task migration. The performance evaluation by simulation, shows improvement of efficiency and stability during execution.

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Peak Power Control for Improvement of Stability in Multi-core System (멀티코어 시스템의 안정성 향상을 위한 피크파워 제어 알고리즘)

  • Park, Sung-Hwan;Kim, Jae-Hwan;Ahn, Byung-Gyu;Jung, Il-Jong;Lee, Seok-Hee;Chong, Jong-Wha
    • Proceedings of the IEEK Conference
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    • pp.747-748
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    • 2008
  • In this paper, we propose a new algorithm for task scheduling consisting of subtask partitioning and subtask priority scheduling steps in order to keep the peak power under the system specification. The subtask partitioning stepis performed to minimize the idle operation time for processors by dividing a task into multiple subtasks using the least square method developed with power consumption pattern of tasks. In the subtask priority scheduling step, a priority is assigned to a subtask based on the power requirement and the power variation of subtask so that the peak power violation can be minimized and the task can be completed within the execution time deadline.

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AUTOMATIC TUNING OF FUZZY OPTIMAL CONTROL SYSTEM

  • Hoon-Kang;Lee, Hong-Gi-;Kim, Yong-Ho-;Jeon, Hong-Tae
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.1195-1198
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    • 1993
  • We investigate a systematic design procedure of automated rule generation of fuzzy logic based controller for uncertain dynamic systems such as an engine dynamic model.“Automated Tuning”means autonomous clustering or collection of such meaningful transitional relations in the state-space. Optimal control strategies are included in the design procedures, such as minimum squared error, minimum time, minimum energy or combined performance criteria. Fuzzy feedback control systems designed by the cell-state transition method have the properties of closed-loop stability, robustness under parameter variabtions, and a certain degree of optimality. Most of all, the main advantage of the proposed approach is that reliability can be potentially increased even if a large grain of uncertainty is involved within the control system under consideration. A numerical example is shown in which we apply our strategic fuzzy controller design to a highly nonlinear model of engine idle speed contr l.

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

  • 장진영;박용국;배충식;김우태
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.6
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    • pp.11-18
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    • 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.

An Experimental Study on Spark Timing Effect for Fast warmup of Catalyst to Cold Start Operation of an SI Engine (가솔린기관의 냉시동시 촉매 가열 촉진을 위한 점화시기 영향에 대한 실험적 연구)

  • Kwon, Y.W.;Ham, S.H.
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.4
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    • pp.101-108
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    • 2011
  • On cold start operation of an SI engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of spark timing. Combustion stability is also considered at the same time. Exhaust gas temperature and pressure of combustion chamber are measured to investigate the effects of spark timings on cold start and idle performance. Experiments showed that retarded spark timing promotes the combustion at the end of expansion stroke and increases exhaust gas temperature during cold start.

Congestion Control for the ABR Service of ATM networks with Multiple Congested Nodes and Multicast Connections (다수의 혼잡 노드와 멀티개스트 연결을 가지는 비동기 전송망의 ABR 서비스에 대한 혼잡 제어)

  • Nho, Ji-Myong;Lim, Jong-Tae
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.8
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    • pp.629-637
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    • 2000
  • Unbalance between user requirements and insufficient network resources makes a congestion. In the future since the communication networks will have very heavy traffic congestion will be more serious. The ATM networks was recommended to support the B-ISDN service for the future multimedia communication. In thie sense of congestion avoidance and recovery the ABR service category in ATM networks allows the feedback flow control mechanism to dynamically allocate the idle bandwidth of the network to users fairly and to control the network congestion rapidly In this paper we introduce a congestion control scheme using systematical approach to confirm robust stability with respect to unknown round trip delay for the network which has both unicast and multicast connections.

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An Experimental Study on the Safety Standard of Electronic Throttle Control System (전자식 가속제어장치 안전기준에 대한 실험적 고찰)

  • Yun, Kyungcheol;Yong, Geejoong
    • Journal of Auto-vehicle Safety Association
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    • v.11 no.1
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    • pp.48-54
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    • 2019
  • Optimal engine control is needed to cope with the global environmental regulations that are globally enforced. For optimum engine control, the electronic throttle control system (ETCS) is a prerequisite. Automotive makers are having an effect on reducing emissions and improving fuel economy by applying ETCS which is designed to secure stability. The ETCS controls the output of the throttle valve by passing the output value of the accelerator position sensor (APS) to the engine control unit (ECU). In this study, the authors investigated the safety standards of domestic and overseas accelerator control system and tried to understand how the air flow control affects the engine output by replacing the throttle. The authors suggest an improvement proposal of safety standard based on the result of driving evaluation by various modes.