Advanced Emission Control for Single Cylinder Engines 2005-26-017

Emission control for all automotive engines has been in existence for over 30 years in most parts of the world. Of late, emissions from all internal combustion engines have come under scrutiny, and even been legislated in some regions of the world. In particular, manufacturers of motorcycles, mopeds, small lawn and garden equipment, chainsaws, personal watercraft and snow mobiles have had to clean up their exhaust by either engine redesign or incorporation of exhaust after treatment devices.

One particular application of interest is the control of emissions from small single cylinder 2-stroke engines. Considering the size of the engines and the devices, there often isn't scope for a separate catalytic converter and a muffler. So the catalytic device has to be incorporated within the muffler. These engines typically put out very high levels of unburned hydrocarbons, and carbon monoxide - along with high amounts of oxygen. With a monolithic honeycomb oxidation catalyst, the oxidation reactions generate very high exotherms, resulting in the catalyst self-deactivating, and also a severe thermal management problem in the exhaust muffler. Thus, alternate catalytic devices are needed, to reduce the emissions and, at the same time, manage the heat within the muffler as well.

This paper describes one such device or process, which offers a durable emission control system that can be tailored to fit in the confined space of a small engine muffler and at the same time, produce the required level of emission control for the projected life of the device or vehicle, as the case may be.