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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/23915

Title: 液化石油氣引擎之空燃比適應控制
Air-Fuel Control of Automotive engines
Authors: 沈志忠;鄭元良;葉承溱
Contributors: NTOU:Department of Mechanical and Mechatronic Engineering
國立臺灣海洋大學:機械與機電工程學系
Keywords: 空燃比控制;空油比控制;引擎空燃比控制
Air to fuel ratio;engine control;LPG engine control
Date: 1998-11
Issue Date: 2011-10-20T08:08:42Z
Publisher: 中國機械工程學會第15屆全國學術研討會論文集
Abstract: 由於汽車廢氣排放標準日益格,汽車之燃料控制系統必須提供精確之空燃比(Air-FuelRatio),以達到三元觸媒轉化器之最高轉換效率.本研究將先以噴油引擎之空燃比控制模擬為基礎,再針對實際三氣缸液化石油氣引擎,做其空燃比控制實驗.  引擎模式包括進氣歧管空氣動態,致動器動態,四衝程引擎之時間延遲及含氧感測器動態等.由於含氧感測器只能提供一具有時間延遲(time delay )且落後之訊號,若以傳統控制設計,則將因其延遲因素而造成系統反應速度之減緩.改善之道可根據引擎模式以前饋控制(feed-forward)增加暫態反應速度,並以回授控制低穩態誤差.  在噴油引擎控制方面,由於引擎之動態系統參數與引擎轉速及負載有關,而且也隨著引擎的磨損,老化及維修狀況而改變,使得引擎系統參數具有不確定性.為了處理其不確定性問題,可事先鑑別出引擎在不同條件之參數變化,以增益編排方法來設計其前饋及回授控制器;另外使用適應性控制方法,在不同操作條件下,辦識引擎參數並隨之調整控制器參數,以達到理想之空燃比控制.由模擬結果可發現,適應性控制器及增益編排控制器皆能有效的改善其暫態響應.  在液化石油氣引擎控制方面,則根據引擎在不同工作條件之參數鑑別結果,設計回授及前饋控制器.由實驗結果,回授控制器能控制其穩態性能,卻不能有效控制其暫態響應,而前饋控制器能提高系統反應速度,增進其暫態響應.
Due to increasingly stringent environmental regulations, the automobilefuel control system has to provide precise air-fuel ratio (AFR) to achievethe highest pollutant conversion effciency for three-way catalyzer converterand to lower the emissions. The objective of this study is to apply control design technique to the AFR control of a liquefied using a fuel-injected engine model. The control design is then applied to the LPG engine and verifiedby experiments. The engine model includes intake manifold dynamics, actuator dynamics,O2sensor dynamics, and cycle delay inherent in a four-stroke engine process.Since the exhaust O2 sensor only provides a delayed and lagged AFR signal tothe controller, the conventional proportional and integral (PI) feedbackcontrol will slow down the system response. To achieve a high bandwidth closed- loop control of AFR, modern observer-based control can be used as a feed-forword control. As the parameters of fuel-injected engines depend on the engine operatingconditions, as well as engine wear, aging or lack of maintenance, the engine model suffersfrom model uncertainty. Two control methodologies are used to deal with theengine parameter uncertainties.One is the gain-scheduling technique in whichfeed- forword and feedback controls are designed under different operating conditions. The other is the adaptive technique in which the control parametersare tuned on-line during various operating conditions. Simulation resultsindicate that adaptive method or gain-scheduling method can improve AFR transient behavior. In the aspect of the LPG engine, the feed-forword and feedback controllers are designed based on the engine parameters from system identification.Experiment results verify that feedback control is only effective under steady-state operating conditions and feed-forward control can improve the AFR transient performance considerably.
URI: http://ntour.ntou.edu.tw/handle/987654321/23915
Appears in Collections:[機械與機電工程學系] 期刊論文

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