Experimental Investigations Regarding the Potential of an Electronic Ignition Timing Control for a Lawn Mower Engine

In order to fulfill future regulations regarding emissions and CO₂ reduction, the small engine market inclines to migrate from carburetor systems to cleaner, more efficient electronic ignition controls and electronic fuel injection systems. When implementing such mechatronic systems in small engine applications, one has to consider specific boundary conditions like the lack of relevant sensors, limited possibilities in terms of space and of course the necessity to keep the costs as low as possible. Especially in the non-road mobile machinery (NRMM) segment, the absence of sensors makes it difficult to apply standard electronic control systems, which are based on engine related input signals provided by sensors. One engine related signal, which is even provided by the simplest engine setup, is some form of the crankshaft speed since it is essential for the functionality of the engine. In this paper, the potential of an electronic ignition timing control system based on this signal as well as experimental experiments are presented. A single cylinder lawn mower SI engine is used for the experiments, since it is representative for basic NRMM engine configurations. Under the restriction that the speed regulating centrifugal governor should not be manipulated, the potential of the electronic ignition control has been investigated with the focus on engine performance and noise emissions under transient load conditions.