活塞式單缸氣動引擎複合四行程內燃機怠速啟動可行性分析

The Feasibility Study of Idle Start in Single-cylinder Piston-type Air Hybrid Engines

周芳興(Chou, Fang Hsing)

指導教授 ： 黃智永

國立清華大學/工學院/動力機械工程學系/碩士(2015年)

摘要

本研究希望藉由單缸氣動引擎複合內燃機四行程引擎，將氣動引擎作為怠速啟動使用，等到達一定轉速再切換為內燃機引擎。首先根據單缸活塞式氣動引擎的運作模式經由適當假設與熱力學循環並使用MATLAB軟體進行理論分析計算。為了驗證理論分析的正確性，本研究同時建立實驗平台進行量測，改裝市售的光陽 cherry 100 cc 內燃機引擎成四行程氣動引擎，並將實驗結果與理論結果進行比較分析。
實驗部分將引擎進氣口連接高壓氣體作為動力源使之運轉，因四行程氣動引擎運作中會有等熵壓縮行程且進排氣閥門皆為關閉，會造成缸內壓力過大使引擎停止運轉，因此在火星塞的位置利用耐壓管線與耐壓鋼瓶連接成高壓暫存區(緩衝區)，降低此行程中的缸內高壓。實驗中改變不同緩衝區體積與不同進氣壓力來探討怠速啟動時的氣動引擎效能表現，最後選擇緩衝區體積為1.5 L與進氣壓力5 bar作為怠速啟動條件。因實驗所使用的cherry 100引擎為二閥門引擎，其火星塞在測試時移除作為緩衝區連接使用，為使氣動引擎順利複合內燃機所以進一步提出四閥門引擎的設計理念，可以善加利用四個閥門中的一個或兩個閥門進行緩衝區連接且保留原火星塞位置，且提出了三種不同設計理念探討其效能輸出。最後設計一款二行程與四行程轉換機構，可使氣動引擎以二行程怠速啟動，待引擎達到一定轉速後再藉由凸輪轉換機構切換成四行程內燃機模式持續運轉。此機構同時可在煞車模式下切換回氣動引擎進行二行程煞車能量回收，以增加儲氣瓶的回收壓力，並可供氣動引擎怠速啟動使用。

關鍵字

氣動引擎 ； 怠速啟動 ； 單缸複合 ； 複合引擎 ； 活塞式氣動引擎

並列摘要

The study aims to investigate feasibility of a single cylinder piston-type compressed air engine assisting to an internal combustion engine for idle start. The engine will be started as compressed air engine mode at beginning and it will later switch to internal combustion mode once the engine speed reaches to higher rpm. In this study, a theoretical analysis using thermodynamics and compressed air model has been carried out with MATLAB to understand the engine performance as well as fluid characteristics. A commercial available 100 c.c. single cylinder four-stoke internal combustion engine is modified to a 100 c.c. four-stroke air-powered engine to test the torque and power output. The experimental results have been compared with the data from theoretical analysis.
A four-stroke compressed air engine has been modified with the inlet valve to operate with high pressure compressed air before the experiments. A buffer tank is connected to the four-stroke air-engine operation through the spark plug hole due to high cylinder pressure resulted from the isentropic compression. Different buffer tank volumes have been examined during the experiment for the torque and power output. The buffer tank with volume of 1.5 litters and compressed air pressure of 5 bar is used for the subsequent tests of idle-start.
A four-stroke engine with four valves is also examined theoretically to find the feasibility of idle-start which can select one or two valves to connect with buffer region instead of using the spark plug hole. An exchangeable cam mechanism which can switch the two-stroke mode operation to/from four-stroke mode has also been studied, this mechanism can be used to start the engine as two–stroke compressed air engine then switch to four-stroke internal combustion mode. It can also be used to switch the four-stroke internal combustion mode back to two-stroke mode for regenerative braking and recycling the compressed air.

並列關鍵字

air engines ； air hybrid engines ； single cylinder ； idle start

參考文獻

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