US Patent 6938587 Hand held power tool

A power tool including a main section and a handle section. The main section includes an internal combustion engine and a housing at least partially surrounding the engine. The engine includes a cylinder, a spark plug, and a muffler. The handle shaft extending from the main section. The shaft forms a handle for the power tool and houses a drive shaft from the engine therein. The housing forms a cover section over a transmission assembly between the engine and the drive shaft. The cover section includes a scroll form to channel air flow pushed by the transmission assembly. The housing further comprises a spark plug boot to substantially prevent air from exiting the housing at the spark plug.