車上診斷系統（OBD）之污染排放管制應用之研究

Application Studies of Automotive Onboard Diagnostic Systems

隨著車上診斷系統（on-board diagnostic, OBD）新車法規實施，OBD 檢驗方法也將逐步納 入使用中車輛污染排放之檢驗制度。但現行 OBD 系統對於車輛污染元件改裝及實施 OBD 檢驗 時可能出現「未準備就緒（Not Ready）」碼，造成檢驗錯誤結果仍未有相關對策。因此本研究 針對車輛污染元件改裝在 OBD 檢驗過程可能之弊端及 OBD 之「準備就緒（readiness status, RS）」 狀態進行實車試驗以提出相對應策略。實車試驗選用五台國內不同廠牌車型，分別模擬在車輛 故障未修復條件下清除故障碼，以及車輛其他原因所造成未準備就緒狀態下，行駛四種不同行 車型態以評估在完成行車型態後是否為準備就緒狀態。另外，再選定一部符合我國四期汽油車 輛污染排放標準之測試車，分別更換四種不同觸媒轉換器後，於車輛污染排放實驗室進行污染 測試。試驗結果顯示現有之行車型態並不適用於 OBD 檢驗方法，而使用中車輛污染排放定期 檢驗，如果僅使用惰轉污染檢驗，則除了拆除整個觸媒載體之排放會不符合排放標準外，其餘 改裝型式觸媒排氣管都可輕易通過惰轉及 OBD 排放檢測。針對實驗結果，本研究提出適用於 OBD 檢驗的通用型行車型態，在污染元件改裝防弊上，建議實施 OBD 檢驗時，應實施更嚴謹 的車輛污染排放控制元件外觀目視檢查，並研擬車輛污染排放控制元件之售後市場零件認證制 度。

Onboard diagnostic（OBD）systems are used to monitor and diagnose the functions of automotive engine components for exhaust emission monitoring. In many countries, OBD systems are required for new vehicles and involved in the inspection and maintenance of used vehicles. In this regard, OBD systems have some problems, including "fraudulent behavior" and "not ready" status. This study investigated possible fraudulent behaviors and readiness status indications in OBD system inspections. To investigate readiness status, five cars were selected from different automobile dealerships. Each vehicle with "not ready" status possibly due to malfunction or an unknown cause was run through four different driving cycles. After completion of each cycle, the readiness status was reassessed. To investigate fraudulent behavior, a test vehicle that met Taiwan's Phase 4 emission standards for gasoline engine vehicles was selected. Four catalysts were individually installed in the test vehicle, and an emission test was conducted in a laboratory. The experimental results showed that the completion of four driving cycles is not suitable for OBD inspection when a vehicle has "not ready" status. During idle emission inspection, only the empty catalyst did not meet the emission standard| all other modified catalysts easily passed the idle and OBD emission tests. In view of these results, this study proposes a general-purpose driving cycle suitable for OBD emission testing. In addition, this study recommends that vehicle pollution components be more rigorously assessed during OBD system inspections and that an aftermarket parts certification system be developed for emission control.