JPS60216016A - Muffler device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce exhaust gas noise, by defining first and second expansion chambers in the outer cylinder of a muffler and by providing a first exhaust pipe connecting between the first expansion chamber and the exhaust gas outlet and a second exhaust pipe connecting between the second expansion chamber and the exhaust gas outlet. CONSTITUTION:The inside of a muffler outer cylinder 11 is divided into first and second expansion chambers 15, 16, and further there are provided an exhaust gas inlet pipe 17 piercing through the first expansion chamber 15, a first exhaust gas outlet pipe 18 piercing through the first expansion chamber 15, opened at its one end to the second expansion chamber 16 and formed therein with communication holes 19 in the part which confronts the first expansion chamber 15, a second exhaust outlet pipe 20 piercing through the second expansion chamber 16 and opened at its one end to the first expansion chamber 15 while merged into and connected to, at its the other end, the first exhaust gas outlet pipe 18 which is provided therein with a shut-off valve 30. When the flow rate of exhaust gas the valve 30 is closed to constitute a two stage structure expansion type muffler section to reduce noise due to pulsation in exhaust gas while when the flow rate of exhaust gas is large, the valve 30 is opened to lower the pressure of exhaust gas to enhance the output of the engine to restrain noise due to secondary generated stream.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an improvement in an exhaust silencer for an internal combustion engine.

BACKGROUND ART For example, there are various types of exhaust muffling devices used in automobiles, one of which is shown in Fig. 1 (for example, the one shown in Fig.
Publication No. 11).

This is because both ends of the muffler outer cylinder 1 are closed with end plates 2 and 3, and a first expansion chamber 5 and a second expansion chamber 6 are formed inside the muffler outer cylinder 1 with a partition plate 4 in between. Then, the exhaust gas flowing from the exhaust inlet pipe 7 passing through the first expansion chamber 5 passes through the second expansion chamber 6 as shown by the arrow and connects to the communication 'r provided in the partition plate 4. ! ! 8 to the first expansion chamber 5, then make a U-turn again from the first expansion chamber 5 and move to the first expansion chamber 5.
The exhaust gas is discharged outside the vehicle through an exhaust outlet pipe 9 passing through the expansion chamber 6.

Such an exhaust silencing device has a two-stage U-turn structure, so that it can exhibit a silencing effect in a wide frequency range, and is particularly effective in silencing fundamental order components of exhaust pulsation in a low engine speed range.

However, since such a conventional exhaust silencer has a complicated structure, it is easy to cause vortices and turbulence in the exhaust flow, especially when high-frequency engine rotation and large exhaust current flow occur. There is a problem that noise is generated and exhaust noise becomes louder. Furthermore, there are also problems in that the exhaust pressure is large and the output of the engine is reduced when the engine speed is high and the exhaust flow rate is large.

OBJECTS OF THE INVENTION The present invention was proposed in view of the above-mentioned conventional problems, and aims to reduce exhaust pulsation noise etc. when the engine exhaust flow rate is small, as well as reduce exhaust noise when the engine exhaust flow rate is large.
It is an object of the present invention to provide an exhaust silencing device for an internal combustion engine that obtains the exhaust noise in the exhaust direction due to a decrease in exhaust pressure.

Structure of the present invention The present invention provides first and second
an expansion chamber; an exhaust inlet pipe that passes through the first expansion chamber and has one end connected to the engine and the other end opening into the second expansion chamber; and an exhaust inlet pipe that passes through the first expansion chamber and has one end connected to the second expansion chamber a first exhaust outlet pipe that opens into the chamber and has a communication hole formed in a portion facing the first expansion chamber; The second exhaust outlet pipe is connected to the first exhaust outlet pipe, and the second exhaust outlet pipe is formed in the middle of the first exhaust outlet pipe to open and close the passage of the first exhaust outlet pipe in accordance with the rotation of the engine. be.

Example Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 2 is a sectional view showing the exhaust silencer according to the present invention, in which reference numeral 11 indicates muffler outer cylinders 12 and 13 having an elliptical cross section.
The front and rear end plates 14, which close the L muffle outer cylinder 11, are provided in the muffler outer cylinder 11, and #$1 expansion chamber 1b,! : m2
A partition plate 17 separates the expansion chamber 16 from the front end plate 12.
and the first expansion chamber 15 through the partition plate 14, and one end 17a is connected to an engine (not shown), and the other end 17a is connected to an engine (not shown).
b is an exhaust inlet pipe 18 that opens into the second expansion chamber 16;
passes through the first expansion chamber 1b via the front end plate 12 and the partition plate 14, one end 18a opens into the second expansion chamber 16, and the other end 18'b passes through the front end plate 12, and the muffler This is a first exhaust outlet pipe that opens to the outside and has a plurality of communication holes 19 at a portion facing the first expansion chamber 15 . As shown in the figure, the first exhaust outlet pipe 18i is one end 22 of a U-shaped exhaust pipe 22 that is bent into a U-shape to ensure a constant length.
It is fitted in a.

In addition, a second
This is a second exhaust outlet pipe that penetrates the expansion chamber 16, has one end 20a open to the first expansion chamber 1b, and the other end 20b 77 to open to the outside. , 21 is a Y-shaped merging pipe, one end 21a of the Y-shaped end is connected to the other end 20b of the second exhaust outlet pipe 20, and the other end 21b of the Y-shaped end is connected to the U
It fits into the other end 22b of the prison exhaust pipe 22. In other words, the merging pipe 21 line, the second exhaust outlet pipe addition and the U-shaped exhaust pipe 2
It is formed so that the exhaust air from 2 flows together smoothly.

Further, an on-off valve 30 for opening and closing the passage of the first exhaust outlet pipe 18 is disposed in the middle of the first exhaust outlet pipe 18, that is, near the outside of the front end plate 12 of the muffler outer cylinder 11.

As shown in the same figure, this opening/closing ff3 is controlled by a butterfly-type valve body 31 provided in the passage, and a solenoid 3 connected to the valve body 31 via a drive shaft 32 and a rotating arm 33.
Opening and closing are controlled by a control circuit 35 according to the rotation range of the engine.

According to the above configuration, the engine speed range (for example, 400O
r-p-m or less), the control circuit 35 detects this and turns the solenoid 34 off as shown in FIG.
"F" and the valve body 31 is in the closed state.

Therefore, the exhaust gas flowing into the second expansion chamber 16 from the exhaust inlet pipe 17 flows from the second expansion chamber 16 to the first expansion chamber 16 as shown by the arrow in the figure.
Make a U-turn into the exhaust outlet pipe 18 and open the first exhaust outlet pipe 18.
The exhaust gas flows into the first expansion chamber 15 through the communication hole 19, then makes a U-turn again, flows into the second exhaust outlet pipe 20, enters the confluence pipe 21, and is discharged outside the vehicle. In other words, by allowing the exhaust gas to flow through such a double U-turn structure expanded silencing section, the silencing effect can be achieved over a wide range of frequencies.
Exhaust pulsation noise that occurs in the low engine speed range is also sufficiently reduced.

On the other hand, engine high rotation range (e.g. 4000 rpm or more)
In this case, the control circuit 35 turns on the solenoid 34 to close the valve body 31, as shown in FIG.

Therefore, the exhaust gas flowing into the @2 expansion chamber 16 from the exhaust inlet pipe 17 flows from the second expansion chamber 16 to the first expansion chamber 16 as shown by the arrow in the figure.
It makes a U-turn into the exhaust outlet pipe 18, enters the confluence pipe 21, and is discharged outside the vehicle. That is, since the exhaust gas passes through the U-turn SEIZO expansion type noise reduction part and the porous expansion type noise reduction part,
Compared to the staged U-turn structure expansion type silencer, the exhaust flow path is simpler, thereby avoiding an increase in exhaust pressure in the engine's high rotation range, preventing a decrease in engine output, and suppressing secondary airflow noise. . Moreover, when the main stream of exhaust gas passes through the communication hole 19, the exhaust noise in the viable bacteria frequency range is also sufficiently reduced.

Furthermore, since the exhaust flow paths of the two buildings can be integrated into one muffler outer cylinder 11, the entire apparatus can be made more compact.

Effects of the present invention As described above, the exhaust silencing device for an internal combustion engine according to the present invention has
The exhaust flow path is switched according to the rotation of the engine, and when the exhaust flow rate is low, a two-stage U-turn structure expansion type muffling section is configured, so it has a sufficient muffling effect in a wide frequency range and exhaust pulsation noise. Demonstrate. On the other hand, when the exhaust flow rate is large, the single-stage U-turn structure expansion type noise reduction part and the multi-hole expansion type noise reduction part are formed into an S configuration, so the exhaust passage is simple, the exhaust pressure can be lowered, and the engine output direction can be increased. Secondary airflow noise is suppressed, and the exhaust radiation dose in the medium and high frequency ranges can be sufficiently reduced. Historically, two expansion chambers can be used to configure a two-stage U-turn structure expansion type muffling section, a single-stage U-turn structure expansion type muffling section, and a multi-hole expansion type muffling section. can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional exhaust silencer for an internal combustion engine.
FIG. 2 is a sectional view showing the exhaust silencing device of the present invention, and FIG. 3 is a sectional view showing the exhaust silencing device in a state where the on-off valve is open. 11...Muffler outer cylinder, lb...First expansion chamber, 16
...Second expansion chamber, 170, exhaust inlet pipe, 18, Φ, first exhaust outlet pipe, 19, 0 communication hole, 2υ, second exhaust outlet pipe, holder...opening/closing valve. 2 people outside Figure 1

Claims (1)

[Claims] (1) First and second expansion chambers formed inside the muffler outer cylinder, and an exhaust manifold that passes through the first expansion chamber, has one end connected to the engine, and the other end opens into the second expansion chamber. a first exhaust outlet pipe that passes through the first expansion chamber, has one end open to the second expansion chamber, and has a communication hole formed in a portion facing the first expansion chamber; and the second expansion chamber. It penetrates and one end is #! A second exhaust outlet pipe that opens into the expansion chamber and whose other end is connected to the first exhaust outlet pipe, and a second exhaust outlet pipe that is formed in the middle of the first An exhaust muffling device for an internal combustion engine, comprising an on-off valve that closes a passage of an outlet pipe.