Study of OBD stageII Misfire Detection System for Small Motorcycles 2019-32-0511
In recent years, the shift to Fuel Injection (FI) system for motorcycles has been accelerated in response to the enhancement of exhaust emission regulations and the improvement of fuel efficiency for global environmental protection. In addition, On Board Diagnostics (OBD) was introduced to inform users of vehicle abnormalities and failures and prevent from emission failure in the market. OBD stageII requires enlargement of requirements and threshold detection. Seven items are presented in the EU5, Bharat Stage 6 (BS6). The misfire detection in small motorcycles has several problems.
First, for the small motorcycle, a single-cylinder engine is the main and its combustion behavior cannot be compared with other cylinders. Consequently, it is difficult to detect misfire. For misfire detection, we focused on the difference in crank angular velocity during combustion stroke between normal combustion and misfire. The greatest gap was in crank angular velocity occurs at 0-180° crank angle [°CA]. With that, misfire detection control is established.
We confirmed from the above control that misfire could be detected in the whole engine speed or load within the regulation. As a countermeasure against erroneous detection at the time of actual running, the rotational fluctuation caused by misfire and the rotational fluctuation caused by disturbance were separated from the pattern of the rotational fluctuation caused by road surface vibration, and the control for preventing from erroneous detection was constructed. We actually traveled on various road surfaces and confirmed that there were no erroneous detections.
As a result, we could construct a control for preventing from erroneous detection in an actual road while securing a sufficient misfire detection rate.