用以改善熱分佈均勻性之車燈排氣結構之分析與驗證

Analysis and Investigation of the Venting Structure in a Vehicle Lamp to Improve the Uniformity of the Heat Distribution

陳伯仁(Po-Jen Chen)

指導教授 ： 莊為群

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2014年)

https://doi.org/10.6827/NFU.2014.00091

摘要

汽車頭燈除了影響行車的安全性外，在外觀造型上也是眾人討論的話題。而燈具內，點燈高溫造成如霧氣、零件熱熔、熱老化等狀況，也正好就是關係著安全以及外觀的重要因素。為了改善這些狀況，目前在燈具上均會增加通氣孔，目的是要藉由通氣孔使燈具內部熱空氣與外部的熱冷空氣產生自然對流，透過對流的方式來排去累積在燈具內的高溫，使燈具內能達到較均勻的熱分佈，另外也能將燈具內部飽和的水氣一併排出達到防止霧氣聚集不散的功能。而一般直接開孔式的通氣孔為了防塵會加上排氣蓋或排氣管，但在加上排氣蓋或排氣管後會直接影響通氣孔空氣對流的效能，故針對這兩者來作排熱效能上的比較。
本研究將相同的車燈、相同孔徑的通氣孔，區分為裝上排氣蓋及排氣管的兩種狀態，透過CFD軟體對燈具內部進行熱模擬分析，主要比較的是兩個狀態下，燈具內、外零件溫度的變化分布及燈具內部及排氣裝置處流場的分析。接著再透過實驗來驗證模擬的結果是否實際相符。
首先在軟體的模擬後發現，在裝上排氣管的狀態下，主要零件溫度均低於裝上排氣蓋的狀態，溫差最大處差值約5度。而透過流速的分析更能發現燈具內部的流速不同，而排氣管處流速約0.5 m/s，快於排氣蓋處的0.3 m/s。而在點燈實驗中，測量點處實際測得的溫度，裝置排氣管時所側得的溫度為66.9℃，裝置排氣蓋時所測得的溫度是71.2℃。
在模擬與實驗驗證相符之下，我們得到的結論是排氣管的排熱及對流的效能是優於排氣蓋的。

關鍵字

車燈 ； 排氣蓋 ； 排氣管 ； 通氣孔

並列摘要

The head lamp affecting traffic safety, and the appearance is also a focus. When the illumination to produce high temperature. Made such as fog, parts melt, thermal aging or other situations. These situations are just about safety and appearance. So, to improve these conditions, all the head lmap add vent. It help the lamp can be thermal convection. By thermal convection so that the internal temperature distribution. But in order to dust. Plus the vent tube or vent assembly will directly affect the performance of convection. So for these two parts for analysis.
In this study. We used the same sample to test these different equipment. One is vent tube, and the other one is vent assembly. Then, through CFD software analysis the flow field. Compare the inner and outer parts changes in temperature, and the air velocity of flow at the vent. Through the analysis could find, used vent tube, the temperature was lower than used the vent assembly. At the maximum temperature difference of about 5℃. And by the flow rate analysis could find, when used vent tube, the flow rate is about 0.5 m / s, when used vent assembly, the flow rate is about 0.3 m / s. So the vent tube is more fast than vent assembly.
In order to verify the correctness of the software analysis. We lighting fixtures to verify. Analysis shows that the position of the highest temperature, where the position at the top of the lamp envelope. So we measured this position. The temperature of vent tube is 66.9℃. And the temperature of vent assembly is 71.2℃ .
Compare the data of these two. The result is the performance by vent tube better than vent assembly.

並列關鍵字

head lamp ； vent ； natural convection ； vent tube ； vent assembly

參考文獻

[1] Lilian Hoines and Jianzhong Jiao, “Environment Leading to Condensation

Airflow on Automotive Lamp Venting,” SAE Technical Paper,1999。

[3] Hoines, L. and Jiao, J., “Effect of exterior airflow on automotive lamp

veting,” SAE paper 1998

[4] Bielecki,J.W., Chang, M. and Hoines, L., “Applying the law of diffusion to