Exhaust gas muffler for a two-stroke engine
AssigneeAndreas Stihl
InventorsHartmut Fischer, Jurgen Grassmuck, Michael Wissmann, Albert Dreher
Life of this patent
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Abstract
The invention is directed to an exhaust gas muffler for a two-cycle engine, especially for a handheld portable tool, such as a chain saw. In exhaust gas mufflers equipped with a catalyzer, the formation of flame from the fuel-containing exhaust gases exiting from the muffler must be prevented. These exhaust gases are intensely overheated because of the exothermal process in the catalyzer. The muffler according to the invention includes a catalyzer which establishes a connection between separate component chambers of the muffler housing. The muffler can be mounted directly on the motor outlet.
Claims17
An exhaust gas muffler for a two-stroke engine, especially for a handheld portable tool such as a chain saw, the engine including a cylinder and a piston conjointly defining a combustion chamber wherein combustion gases are generated during operation of the engine, the exhaust gas muffler comprising:
- a housing having an inner housing wall surface defining an interior space;
- a catalyzer disposed in said interior space and including an enclosure wall having an outer enclosure wall surface;
- mounting means for mounting said catalyzer in said interior spacer so as to cause said outer enclosure wall surface to be in spaced relationship to said inner housing wall surface on all sides of said catalyzer;
- said mounting means and said catalyzer conjointly partitioning said interior spacer into first sand second chambers;
- said housing having an inlet in said first chamber communicating with the combustion chamber of the engine so that the exhaust gases can pass into first chamber;
- said catalyst defining a catalytic chamber for interconnecting said first and second chambers and for exothermally converting the exhaust gas and passing the converted exhaust gas to said second chamber;
- said housing having an outlet in said second chamber for passing the exothermally converted exhaust gas out of said muffler;
- said housing including a first housing part having said inlet formed therein and a second housing part having said outlet formed therein;
- said housing parts being joined together at a common interface;
- said mounting means being a partition wall supporting said catalyzer therein;
- and,
- said partition wall being welded gastight to said second housing part thereby placing said partition wall downstream of said common interface.
An exhaust gas muffler for a two-stroke engine, especially for a handheld portable tool such as a chain saw, the engine including a fan for generating a cool air flow and the engine further including a cylinder and a piston conjointly defining a combustion chamber wherein combustion gases are generated during operation of the engine, the exhaust gas muffler comprising:
- a housing having an inner housing wall surface defining an interior space;
- a catalyzer disposed in said interior space and including an enclosure wall having another enclosure wall surface;
- mounting means for mounting said catalyzer in said interior space so as to cause said outer enclosure wall surface to be in spaced relationship to said inner housing wall surface on all sides of said catalyzer;
- said mounting means and said catalyzer conjointly partitioning said interior space into first and second chambers;
- said housing having an inlet in said first chamber communicating with the combustion chamber of the engine so that the exhaust gases can pass into said first chamber;
- said catalyzer defining a catalytic chamber for interconnecting said first and second chambers and for exothermally converting the exhaust gas and passing the converted exhaust gas to said second chamber;
- said housing having an outlet in said second chamber for passing the exothermally converted exhaust gas out of said muffler;
- and,
- pipe means extending from said outlet of said second chamber for conducting the exothermally converted exhaust gas into said cool air flow for mixing said exothermally converted exhaust gas with the latter.
An exhaust gas muffler for a two-stroke engine, especially for a handheld portable tool such as a chain saw, the tool having a rearward end and defining a longitudinal axis and a side wall extending in the direction of said axis, the engine including a fan for generating a cool air flow and the engine further including a cylinder and a piston conjointly defining a combustion chamber wherein combustion gases are generated during operation of the engine, the exhaust gas muffler comprising:
- a housing having an inner housing wall surface defining an interior space;
- a catalyzer disposed in said interior space and including an enclosure wall having an outer enclosure wall surface;
- mounting means for mounting said catalyzer in said interior space so as to cause said outer enclosure wall surface to be in spaced relationship to said inner housing wall surface on all sides of said catalyzer;
- said mounting means and said catalyzer conjointly partitioning said interior space into first and second chambers;
- said housing having an inlet in said first chamber communicating with the combustion chamber of the engine so that the exhaust gases can pass into said first chamber;
- said catalyzer defining a catalytic chamber for interconnecting said first and second chambers and for exothermally converting the exhaust gas and passing the converted exhaust gas to said second chamber;
- said housing having an outlet in said second chamber for passing the exothermally converted exhaust gas out of said muffler;
- a pipe extending outwardly from said outlet for conducting said exothermally converted exhaust gas away from said second chamber;
- and,
- said pipe being mounted so as to extend toward the rearward end of said tool and along said side wall and being disposed in said cool air flow so as to permit said cool air flow to skim over said pipe thereby cooling the exothermally converted exhaust gas passing therethrough.
An exhaust gas muffler for a two-stroke engine, especially for a handheld portable tool such as a chain saw, the engine including a cylinder and a piston conjointly defining a combustion chamber wherein combustion gases are generated during operation of the engine, the exhaust gas muffler being a replacement muffler for an existing muffler, the replacement muffler comprising:
- a housing having an inner housing wall surface defining an interior space;
- a catalyzer disposed in said interior space and including an enclosure wall having an outer enclosure wall surface;
- mounting means for mounting said catalyzer in said interior space so as to cause said outer enclosure wall surface to be in spaced relationship to said inner housing wall surface on all sides of said catalyzer;
- said mounting means and said catalyzer conjointly partitioning said interior space into first and second chambers;
- said housing having an input pipe communicating with the combustion chamber of the engine and extending through said first chamber and past said catalyzer for conducting the exhaust gases into said second chamber;
- said catalyzer defining a catalytic chamber for interconnecting said first and second chambers and for exothermally converting the exhaust gas and passing the converted exhaust gas from said second chamber to said first chamber;
- and,
- said housing having an outlet in said first chamber for passing the exothermally converted exhaust gas out of said muffler.
Dependencies are inferred from the claim text.