用二氧化碳作为示踪气体检测汽车车灯的气密性

DETECTION OF THE LEAK IN AUTOMOBILE LAMPS USING TRACER CARBON DIOXIDE

汽车车灯的气密性是车灯生产过程中必需检测的质量指标。本文合理选用了二氧化碳为示踪气体，发展了三种测量车灯气密性的方法和设备。其中，光学法是基于二氧化碳与空气的折射率有差别，利用彩色纹影法和阴影法原理来判断泄漏；浓度分析法利用二氧化碳与空气的热导率有差别，在车灯内充有一定气压的二氧化碳后，用热传导型气体传感器来检测二氧化碳气的泄漏来判断车灯的气密性；气压检测法利用压力传感器测量车灯内充气后气压随时间的变化来判断泄漏的程度。由此，实现了从粗到细地检测车灯的泄漏情况，并能确定泄漏缝隙的具体位置和大小，帮助了解制造和装配工艺中的问题。

The airtight quality of automobile lamps is one of the criterions that must be measured and validated. In this paper carbon dioxide was rationally chose as a tracer gas and three ways and instruments were developed to detect the airtight quality of automobile lamps. The optic method, which based on the difference of the refractive indexes between carbon dioxide and air, estimate leaks according to principles of Schlieren and Shadow-graph. The concentration method is based on the difference of thermal conduc...