JPH0441912A - Exhaust device for engine - Google Patents

Abstract

PURPOSE:To facilitate the tuning for reducing booming noise by connecting two tail pipes to the second expansion chamber of a muffler partitioned into multiple expansion chambers, and forming a resonator chamber with the portion partitioned by a cover provided in the middle of one of two tail pipes. CONSTITUTION:A partition plate 8 is provided in a muffler 5 to form expansion chambers 9, 10, and the expansion chambers 9, 10 are communicated by a pipe 11 provided on the partition plate 8. An exhaust pipe 2 connected to an engine at one end is opened to the first expansion chamber 9 across the second expansion chamber 10, and tail pipes 6, 7 are opened to the second expansion chamber 10 across the first expansion chamber 9. A cover 12 is fitted in the middle of one tail pipe 7, and the portion from the opening section of the second expansion chamber 10 of the tail pipe 7 to the cover 12 functions as a resonator chamber. When the position of the cover 12 is changed, the volume of the resonator chamber is changed, and the tuning for reducing the level of booming noise is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust system for an engine used in an automobile.

(Prior Art) As shown in FIGS. 3 and 4, an exhaust pipe 2 is provided under the floor of an automobile body l, and exhaust gas from an engine 3 is passed from a catalytic converter 4 to the atmosphere through a muffler 5. It should be discharged. A tail vibro 7 is attached to the rear end of the muffler 5. Note that the shaded areas in these figures indicate that a heat shield plate has been installed, and the muffler 5
Even if the engine has multiple cylinders, there is only one piece, and this can provide sufficient noise reduction, but the tail pipe is used to prevent exhaust efficiency from decreasing due to high back pressure. It is necessary to have a sufficient opening area. For this purpose, one tailpipe is sufficient if the tailpipe has a certain diameter, but due to appearance requirements, especially in sporty cars, two tailpipes are required. There are many.

FIG. 6 shows two tail vibros 7 provided at the rear of the muffler 5, and FIG. 7 shows its internal structure. A partition plate 8 is provided inside the muffler 5, and an expansion chamber 9. It is divided into two chambers. A vibrator 11 is attached to the partition fli8, and the expansion chambers 9 and 10 are communicated with each other.

The exhaust pipe 2, whose one end (not shown) is connected to the engine, straddles the expansion chamber 10 and opens into the 11-stage expansion chamber 9, and the tail vibro 7 crosses the expansion chamber 9 and opens into the rear-stage expansion chamber! It opens at 0.

(Problem to be Solved by the Invention) In the muffler 5 having such a structure, the exhaust gas entering the expansion chamber 9 from the exhaust pipe 2 is expanded here, and then enters the expansion chamber IO from the vibrator 11 and expanded again. and expansion room 10
From there, two tail vibro will be included in number 7. The exhaust gases are muffled by this expansion. The size of the muffler 5 is determined depending on the characteristics of the engine, but in some cases, "muffled noise" may not be removed. Therefore, in order to eliminate this "muffled sound", a resonator chamber (resonance chamber) is sometimes provided. Actual fairness 1-21
The invention disclosed in Japanese Patent No. 124 relates to this technique.

Providing a resonator chamber effectively suppresses muffled noise J, but providing a resonator chamber within the muffler 5 increases the external dimensions of the muffler and reduces the volume of the muffler body. In order to finely adjust the resonant frequency, it is necessary to change the volume of the resonator chamber.

However, since the device described in this publication does not have an adjustment mechanism, it is not possible to change the volume of the resonator chamber.

The present invention has been made in view of this point, and provides an engine exhaust system that allows tuning over a large range of 5 without changing the capacity of the muffler itself, and without changing the appearance from conventional ones. This is what we provide.

(Means for Solving the Problems) The present invention provides a first method for solving the problems described above.
As shown in the figure and FIG. 2, the interior is partitioned into a plurality of expansion chambers 9. Two tail vibrators 7 are connected to the expansion chamber IO at the rear stage of the muffler 5 formed in the IO, and one of the two tail vibros 7 (tail vibrator 7) is provided with a lid 12 in the middle. Expansion chamber 1 after the closed lid 12
The configuration is such that the 0 side portion is formed as a resonator chamber.

(Operation j With the above configuration, the exhaust gas that has entered the inside of the muffler 5 is muffled by the expansion and in the process of being discharged from the tail vibro, it enters the tail vibro 7 whose middle part is blocked by M12, and here The resonance reduces the exhaust level of the exhaust sound.The exhaust gas is then exhausted to the outside from the tail vibro which is not subjected to 5M12.By changing the position of N+2 in the tail vibrator 7, the muffled sound J can be reduced. Tuning to reduce this can be easily performed.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIG. A partition plate 8 is provided inside the muffler 5, and the muffler 5 is divided into two expansion chambers 9 and 10 by the partition plate 8. A vibrator f1 is attached to the partition plate 8, and the expansion chamber 9
．． The exhaust pipe 2, whose one end (not shown) is connected to the engine, straddles the expansion chamber 10 in the rear stage and opens into the expansion chamber 9 in the front stage; It opens to the rear expansion chamber +[1.

A cock 12 is attached to the middle (near the tip) of one of the two tail vibrators 7, and this tail vibrator 7 is closed from the inside. Since this tail vibrator 7 opens into the rear stage expansion chamber 10 together with the other tail vibrator as described above, a resonator chamber is formed between this opening and the rooster 12.

In the muffler 5 having such a structure, the exhaust gas entering the expansion chamber 9 from the exhaust pipe 2 is transferred from the vibrator 11 to the expansion chamber I.
n, enters the tail vibro which opens from the expansion chamber 10 into this expansion chamber IO, and is discharged into the atmosphere.

The portion of the tail vibe 7 formed in the resonator chamber does not enter the exhaust gas flow path, but resonates with the exhaust pressure in the expansion chamber 10, reducing the exhaust level of exhaust sound.

The material of the lid 13 must be sufficiently resistant to the temperature of the exhaust gas, and it is preferable to use a mounting structure that allows for positioning within the tail vibe 7. Specifically, it is made of a metal plate or ceramic. It is conceivable to take measures to prevent the plate etc. from loosening and screw it into the tail vibe 7, but
A part of the tail vibe 7 is manufactured as a unit,
This may be connected in the middle of the tail pipe 7.If such a unit is used and the position of the lid 12 is changed within the length β range as shown in FIG. 2, the frequency as a resonator can be adjusted. It becomes easier to adjust the F4 characteristics.

FIG. 5 shows that when the position of the lid 12 is changed in this way,
This figure shows that the peak value of the resonance frequency changes as shown by A and B in the figure.

(Effects of the Invention) As explained above, the present invention connects two tail pipes to the expansion chamber at the rear stage of the muffler whose interior is partitioned to form a plurality of expansion chambers, and one of the two tail pipes is The structure is such that a lid is provided in the middle to close it off, and the expansion chamber side after the lid is formed as a resonator chamber, so it has a simpler structure than the one described in the above-mentioned publication. A necessary and sufficient resonator effect can be obtained. Since there is no need to increase the external dimensions of the muffler, there will be no problems with mounting it to the vehicle body, and the interior dimensions will not be narrowed.The volume of the resonator chamber can be changed, allowing tuning to reduce the level of "muffled noise" etc. becomes easier. Since two tailpipes are attached to the muffler, the appearance remains unchanged from the conventional one.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an embodiment of the present invention, Fig. 2 is a cross-sectional view of the car shown in Fig. 1 with the lid position changed, Fig. 3 is a bottom view of the automobile, and Fig. 4 is a cross-sectional view of the car shown in Fig. 1. Fig. 5 is a graph showing the characteristics when changing the position of the lid in Fig. 1. Fig. 6 is a perspective view showing the area around the muffler. A-A showing the conventional structure of the one in Figure 6
FIG. 2... Exhaust pipe 5... Muffler 6.7... Tail pipe 8... Partition plate 9.10... Expansion chamber 11... Vibe 12... Lid Figure 1 Figure 3 Figure 2 figure. Ward 4/1 5... 7 Hula 6.7 Tail bar Eve 8 Ixty'r, wood receiver. 9,]o...'S chamber 11...pipe 12.

Claims (1)

[Claims] (1) Two tail pipes are connected to the expansion chamber at the rear stage of the muffler, which has been partitioned into multiple expansion chambers, and one of the two tail pipes is closed by providing a lid in the middle. An engine exhaust system characterized in that a portion on the expansion chamber side downstream of the lid is formed as a resonator chamber.