Exhaust gas improvement of modern scooters by velocity control

Abstract

This paper investigates the improvement of the exhaust gas composition by applying a velocity-controlled Throttle-by-Wire-System on modern 50 cc scooters (Euro 5). Nowadays combustion-powered scooters are still inefficiently restricted, resulting in an unreasonably high fuel consumption and unfavorable exhaust emissions. The velocity control prevents restriction by negatively shifting the ignition timing and regulates the throttle valve opening instead. Injection quantity, engine speed, ignition timing, cylinder wall and exhaust temperature, oxygen sensor data, crankshaft position and in-cylinder pressure were acquired to measure engine parameters. In parallel, vehicle CAN bus data, such as throttle opening, acceleration command and velocity were recorded. For determination of the exhaust gas composition, five probes were sensing CO, CO${}_2$, NO${}_x$, O${}_2$ and HC in addition to the temperature and mass flow. A Peugeot Kisbee 50 4T (Euro 5) serves as test vehicle. The original and the optimized restriction were subjected to various gradients on a roller dynamometer at top speed. Thus, a statement can be made about all restricted operating points. Required resistance parameters were determined in a coast down test. When driving on level ground, a difference of 50% in the throttle opening leads to a 17% improvement in fuel economy. By measuring the engine parameters, optimum ignition timing could be proven with increasing internal cylinder pressure. Further, 17% reduction in exhaust gas flow was demonstrated. CO emissions decreased by a factor of 8.4, CO${}_2$ by 1.17 and HC by 2.1 while NO${}_x$ increased by a factor of 3.