Exhaust pipe structure for vehicle

Details Exhaust pipe structure for vehicle Exhaust pipe structure for vehicle

1998-12-28

2001-02-06

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

Common receiver having inlets from plural cylinder

C060S302000, C060S322000

Reexamination Certificate

active

06182447

ABSTRACT:

The contents of Application No. TOKUGANHEI 9-361456 filed on Dec. 26, 1997 in Japan is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust pipe structure for a vehicle, and more particularly, to an exhaust pipe structure suitable for an engine body having a front engine block and a rear engine block.
A related exhaust pipe structure for a vehicle includes a front exhaust pipe connected to a front engine block, a rear exhaust pipe connected to a rear engine block and an exhaust collecting chamber (see Japanese Patent Application Laid-open No. 60-50216). The front exhaust pipe extends from a front portion of an engine body, curves downward and extends rearward of the vehicle body. The rear exhaust pipe extends downward and curves rearward such as to form an L-shape. The front and rear exhaust pipes are connected to the exhaust collecting chamber which is connected to a main exhaust pipe.
SUMMARY OF THE INVENTION
In the above structure, however, lengths of the front and rear exhaust pipes are different. Therefore, there is a possibility that vibration noises having different natural frequencies between the front and rear exhaust pipes, and sound vibration performance is deteriorated. Further, there is a possibility that exhaust pulsation is disordered in the exhaust collecting chamber where exhaust gas flowing through the front and rear exhaust pipes join, and output is declined.
Therefore, it is an object of the present invention to provide an exhaust pipe structure for a vehicle engine capable of enhancing the sound vibration performance, and avoiding a declination of output due to disorder of exhaust pulsation.
To achieve the above object, according to the present invention, an exhaust pipe structure for a vehicle comprises a front exhaust pipe, a rear exhaust pipe and a confluence portion. The front exhaust pipe extends downward from a front portion of an engine and curves rearward. The rear exhaust pipe has an upstream portion and a downstream portion. The upstream portion extends downward from a rear portion of the engine. The downstream portion extends forward from a lower end of the upstream portion and curves rearward. The rear exhaust pipe has substantially the same length as that of the front exhaust pipe. Rear ends of the front and rear exhaust pipes are joined at the confluence portion.
In the above structure, the rear exhaust pipe from the rear portion of the engine includes the downstream portion extending forward from the lower end of the upstream portion and curving rearward, and is formed to have substantially the same length as the front exhaust pipe. Therefore, natural frequencies of the front and rear exhaust pipes are substantially aligned, vibration due to resonance is reduced, and the sound vibration performance is enhanced.
Further, since the front and rear exhaust pipes have substantially the same length, disorder of exhaust pulsation in the confluence portion of both the exhaust pipes is prevented from being generated, and output is enhanced.


REFERENCES:
patent: 5129476 (1992-07-01), Kikuchi et al.
patent: 5325666 (1994-07-01), Rutschmann
patent: 5398504 (1995-03-01), Hirota et al.
patent: 5438830 (1995-08-01), Matsumura
patent: 5582004 (1996-12-01), Rutschmann
patent: 60-50216 (1985-03-01), None
patent: 410252492A (1998-09-01), None

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