An exhaust system for a motorcycle is configured to enhance output while maintaining a necessary noise level. The exhaust system includes an exhaust pipe connected to an engine, and a silencer connected to the exhaust pipe. The silencer includes a hermetically sealed outer cylinder and an inner cyli
An exhaust system for a motorcycle is configured to enhance output while maintaining a necessary noise level. The exhaust system includes an exhaust pipe connected to an engine, and a silencer connected to the exhaust pipe. The silencer includes a hermetically sealed outer cylinder and an inner cylinder disposed within the outer cylinder so as to extend along an axis of the outer cylinder. The outer cylinder has a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere. The inner cylinder includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion with a constant diameter, the throttle portion being connected to the reduced diameter portion, and an enlarged diameter portion connected to the throttle portion with a diameter which becomes larger in the downstream direction.
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1. An exhaust system for a motorcycle, comprising: an exhaust pipe connected to an engine; anda silencer connected to the exhaust pipe, the silencer comprising: a hermetically sealed first tubular body; anda second tubular body coaxially disposed within the first tubular body, the second tubular bod
1. An exhaust system for a motorcycle, comprising: an exhaust pipe connected to an engine; anda silencer connected to the exhaust pipe, the silencer comprising: a hermetically sealed first tubular body; anda second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes an outlet tube, the outlet tube comprising a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction wherein the outlet tube further comprises a large-diameter straight tube connected to a downstream end of the enlarged diameter portion, the diameter of the large-diameter straight tube being equal to the diameter of the downstream end opening of the enlarged diameter portion. 2. The exhaust system of claim 1, wherein a rear end of the enlarged diameter portion opens toward the atmosphere. 3. The exhaust system of claim 1, wherein the second tubular body further includes a porous tube having a plurality of holes, the porous tube including an upstream end connected to the exhaust pipe and a downstream end connected to the reduced diameter portion. 4. The exhaust system of claim 3, further comprising a sound absorbing material operatively stuffed between the porous tube and the first tubular body. 5. The exhaust system of claim 1, wherein the length of the reduced diameter portion is substantially equal to the entire length of the first tubular body. 6. The exhaust system of claim 1, wherein the first tubular body includes a main tube portion, a rear cover connected to a rear end portion of the main tube portion, and a front cover connected to a front end portion of the main tube portion, and wherein at least a portion of the second tubular body projects outward from a downstream end of the main tube portion of the first tubular body, the projecting portion being surrounded by the rear cover. 7. The exhaust system of claim 1, wherein the silencer further comprises an absorbing mechanism which permits the first tubular body and the second tubular body to slide relative to one another to absorb the difference between thermal expansion amounts of the first and second tubular bodies caused by a temperature difference between the first tubular body and the second tubular body. 8. The exhaust system of claim 1, wherein a pressure wave in the exhaust pipe is controlled by setting corresponding diameters and lengths of the reduced diameter portion and the enlarged diameter portion. 9. The exhaust system of claim 6, wherein a rear end opening of the enlarged diameter portion is disposed within a rear end opening of the rear cover. 10. The exhaust system of claim 9, wherein the peripheral edges of the two rear end openings are fixed. 11. The exhaust system of claim 1, wherein the throttle portion includes a straight tube portion and a bent tube portion. 12. A motorcycle comprising the exhaust system of claim 1. 13. An exhaust system for a motorcycle, comprising: an exhaust pipe connected to an engine; anda silencer connected to the exhaust pipe, the silencer comprising: a hermetically sealed first tubular body; anda second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the diameter of the upstream end of the enlarged diameter portion is equal to the constant diameter of the throttle portion, wherein the throttle portion is bent such that the longitudinal axis of the enlarged diameter portion is directed at a lower slope than a longitudinal slope of a main tube portion of the second tubular body in a state where the exhaust system is mounted on the motorcycle. 14. The exhaust system of claim 13, wherein the length of the reduced diameter portion is substantially equal to the entire length of a main tube portion of the first tubular body. 15. The exhaust system of claim 14, wherein the reduced diameter portion comprises a porous tube having a plurality of holes, the porous tube having a diameter that becomes smaller in the downstream direction. 16. The exhaust system of claim 15, wherein the silencer further comprises an absorbing mechanism which permits the first tubular body and the second tubular body to slide relative to one another to absorb the difference between thermal expansion amounts of the first and second tubular bodies caused by a temperature difference between the first tubular body and the second tubular body. 17. An exhaust system for a motorcycle, comprising: an exhaust pipe connected to an engine; anda silencer connected to the exhaust pipe, the silencer comprising: a hermetically sealed first tubular body; anda second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the diameter of the upstream end of the enlarged diameter portion is equal to the constant diameter of the throttle portion, wherein the silencer further comprises an absorbing mechanism which permits the first tubular body and the second tubular body to slide relative to one another to absorb the difference between thermal expansion amounts of the first and second tubular bodies caused by a temperature difference between the first tubular body and the second tubular body, and wherein the throttle portion includes a straight tube portion connected to the reduced diameter portion and a bent tube portion connected to the enlarged diameter portion such that the bent tube portion is disposed opposite to the straight tube portion with a gap therebetween. 18. The exhaust system of claim 17, wherein the absorbing mechanism comprises a support member attached to the inner surface of the first tubular body and which slidably supports the straight tube portion. 19. An exhaust system for a motorcycle, comprising: an exhaust pipe connected to an engine; anda silencer connected to the exhaust pipe, the silencer comprising: a hermetically sealed first tubular body; anda second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the diameter of the upstream end of the enlarged diameter portion is equal to the constant diameter of the throttle portion, wherein the throttle portion includes a straight tube portion and a bent tube portion, and wherein a gap is provided between the straight tube portion and the bent tube portion. 20. An exhaust system for a motorcycle, comprising: an exhaust pipe connected to an engine; anda silencer connected to the exhaust pipe, the silencer comprising: a hermetically sealed first tubular body; anda second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the throttle portion includes a straight tube portion connected to the reduced diameter portion and a bent tube portion connected to the enlarged diameter portion such that the bent tube portion is disposed opposite to the straight tube portion with a gap therebetween, wherein the gap is formed around an axis of the second tubular body so that the downstream end of the straight tube portion and the upstream end of the bent tube portion face each other on opposing sides of the gap.
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이 특허에 인용된 특허 (3)
Storm, Mark, Method and apparatus for improved noise attenuation in a dissipative internal combustion engine exhaust muffler.
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