双怠速法机动车尾气排放检测结果的影响因素分析

Analysis on Factors that Influence the Testing Result of Motor Vehicle Exhaust Emission by the Double Idle Speed Method

针对双怠速法机动车尾气排放检测过程中经常大量出现过量空气系数(λ)不合格现象,结合相关标准和工作实践对影响检测结果的因素进行分析。结果显示,取样管路的气密性差、系统响应时间未达标准、测试软件程序设置错误、高怠速转速设置不合理及由于车辆特性导致的选用标准及操作错误均会导致λ测试结果超标,影响双怠速检测法的准确性。

In view of the unqualified excess air ratio （k） during the application of the double idle speed method,the article analyzed various factors affecting the testing results based on relevant standards and work practices. The testing results of k were affected by a series of factors including poor air tightness of the sampling lines,not up-to-standard system response time,set-up errors of the test software ,unreasonable settings of the high idle speed, and selection criteria and operation errors caused by vehicle characteristics. These factors also affected the accuracy of the double idle speed method.