Muffler for portable engine

In a portable engine driven unit:

• an internal combustion engine including a cylinder and an exhaust port for said cylinder;
• an engine driven cooling fan;
• a shroud disposed around said engine and including means defining an outlet for cooling air flow discharged by said fan;
• a muffler mounted on said engine and disposed at least partially in said outlet in said shroud in the path of cooling air flow and in communication with said exhaust port for receiving exhaust gases from said cylinder, said muffler including means forming a hollow shell defining an expansion chamber, said shell having first and second spaced apart endwalls interconnected by a sidewall, means forming an opening in said shell for discharging exhaust gases from said chamber, means forming a deflector and positioned in relation to said opening to redirect the flow of exhaust gas exiting said shell, said deflector including a portion disposed adjacent said sidewall and spaced therefrom to form a slot along at least a portion of said sidewall for discharging exhaust gases from said muffler to flow over the exterior of said shell in substantially the same direction as the flow of cooling air, said deflector being disposed within an enclosure formed by said shroud in such a way that exhaust gases exiting said muffler mix with cooling air discharged by said fan and flow over said shell before flowing out of said outlet in said shroud.

A muffler for an internal combustion engine, said muffler comprising:

• means defining a hollow shell forming an expansion chamber, said shell including spaced apart endwalls and a peripheral sidewall, one of said endwalls including an inlet opening adapted to be in communication with an engine exhaust port for admitting exhaust gases to said chamber;
• a shield mounted on the other of said endwalls and formed such that a major portion of said shield stands off from said other endwall to define a space between said shield and said other endwall through which air may flow to reduce the surface temperature of said shield;
• an exhaust gas outlet opening in said shell disposed at a point on said shell remote from said shield;
• means forming a deflector disposed adjacent said outlet opening whereby exhaust gases exiting said shell through said outlet opening are redirected by said deflector through a first slot formed by said deflector and the sidewall of said shell;
• and
• said shield includes a skirt portion formed thereon and cooperable with said shell to form a second slot substantially flush with said sidewall of said shell whereby exhaust gas exiting said first slot flows over said sidewall and said second slot.