| US 7,448,204 B2 | ||
| Exhaust system for an engine | ||
| Hidehiro Nishimura, Shizuoka-ken (Japan); Junichi Ooba, Shizuoka-ken (Japan); and Osamu Takii, Shizuoka-ken (Japan) | ||
| Assigned to Yamaha Hatsudoki Kabushiki Kaisha, Shizuoka (Japan) | ||
| Filed on Dec. 19, 2005, as Appl. No. 11/311,067. | ||
| Application 11/311067 is a continuation of application No. PCT/JP2004/007924, filed on Jun. 07, 2004. | ||
| Claims priority of application No. 2003-174735 (JP), filed on Jun. 19, 2003; and application No. 2004-084603 (JP), filed on Mar. 23, 2004. | ||
| Prior Publication US 2006/0150617 A1, Jul. 13, 2006 | ||
| Int. Cl. F01N 3/00 (2006.01) | ||
| U.S. Cl. 60—284 [60/289; 60/297; 60/300; 60/312] | 28 Claims |
| 15. An engine system, comprising:
an exhaust port for releasing combusted gas from an engine;
an exhaust system comprising:
an exhaust pipe coupled with the exhaust port, the exhaust pipe comprising a first location having a first cross-sectional
area, a second location having a second cross-sectional area, and a third location having a third cross-sectional area;
a first catalyst disposed at the first location in the exhaust pipe, the first catalyst configured to provide a reduction
action;
a second catalyst disposed at the second location in the exhaust pipe a set distance downstream of the first catalyst, the
second catalyst configured to provide an oxidation action;
a secondary air induction pipe for introducing air into the exhaust pipe at the third location, the secondary air induction
pipe being connected to the exhaust pipe between the first and the second catalysts at a location where the secondary air
induction pipe is in fluid communication with the first catalyst and a temperature difference between the first and the second
catalysts in a cold start transient phase is within a predetermined range; and
a muffler that surrounds a portion of the exhaust pipe, the muffler being disposed downstream of the first catalyst, and the
second catalyst being disposed inside the muffler, wherein the secondary air induction pipe is connected to a part of the
exhaust pipe inside the muffler;
wherein the third cross-sectional area is less than at least one of the first and the second cross-sectional areas.
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