JPH09195749A - Muffler for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an assembly property and reduce the manufacturing cost and weight. SOLUTION: The inside of an muffler is partitioned into an upstream chamber 14 and a downstream chamber 16 by a first separator 8. An opening 25 is provided in the first separator 8, and a tubular body 31d of valve element supporting member 31 is fitted to a flange 25a of the opening 25. A valve element 32 is swingingly supported on a pin 3b in stays 31e, 31e of the valve element supporting member 31. The valve element 32 is energized by a coil spring 42 so as to choke an opening 25. When the number of revolutions of an internal combustion engine is slow, the pressure in the upstream chamber 14 is less than the sum of the energizing force applied from the coil spring 42 and the pressure in the downstream chamber 16 so that the opening 25 is choked. When the number of revolutions is increased and the pressure attains to a predetermined value, the relationship is reversed. Thus the valve element 32 is separated away from the opening 25 to decrease an exhaust back pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for an internal combustion engine, and more specifically, the interior is divided into an exhaust gas upstream chamber and a downstream chamber by a separator, and the interior of the muffler is separated from the upstream chamber via a passage passing through the separator. The present invention relates to a muffler for an internal combustion engine in which exhaust gas flows to a downstream chamber.

[0002]

2. Description of the Related Art Conventionally, there is known a muffler for an internal combustion engine, the interior of which is divided into an upstream chamber and a downstream chamber of exhaust gas by a separator, and the exhaust gas flows from the upstream chamber to the downstream chamber through a passage passing through the separator. .

For example, International Publication Number WO95 / 1346
In FIG. 0, as shown in FIG. 11, a separator 508 is provided with a valve body 532 which is capable of inserting an inner pipe 526 and a bypass inner pipe 528 and closing / opening an opening end 528a of the bypass inner pipe 528. ing. The valve body 532 is swingably supported near the opening end 528a of the bypass inner pipe 528, and is biased toward the opening end 528a by a coil spring. For this reason,
The valve body 532 always closes the open end 528a.

When the rotational speed of the internal combustion engine is low, the pressure inside the bypass inner pipe 528 (that is, the pressure inside the upstream chamber 514) is smaller than the sum of the biasing force of the coil spring and the pressure inside the downstream chamber 516. Therefore, the open end 528a is closed. On the other hand, when the rotation speed increases and the pressure increases to the predetermined pressure, the two are reversed. Therefore, the valve body 532 is separated from the open end 528a, and the bypass inner pipe 528 is brought into a communication state.

According to the above-described internal combustion engine muffler, the valve body 532 can be appropriately opened and closed by the pressure of the exhaust gas, and since the valve body 532 is inside the muffler, external factors such as flying stones and salt damage can be prevented. It had the advantage of not receiving it.

[0006]

However, in the above-described muffler for an internal combustion engine, since the bypass inner pipe 528 is fixed to the separator 508 in a penetrating state, it is necessary to assemble the bypass inner pipe 528. The sex was not improved enough. Further, since the bypass inner pipe 528 is used, the cost is increased and the weight is increased.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a muffler for an internal combustion engine, which has an improved assembling property and which can reduce the manufacturing cost and the weight.

[0008]

Means for Solving the Problems and Effects of the Invention In order to solve the above problems, the invention according to claim 1 divides the inside into an upstream chamber and a downstream chamber of the exhaust gas by a separator, and forms a passage through the separator. In an internal combustion engine muffler through which exhaust gas flows from the upstream chamber to the downstream chamber through, an opening formed in the separator separately from the passage, and swingably attached to the separator, the opening is By providing a valve body that can be closed / opened and a biasing body that biases the valve body so that the opening is closed, when the pressure in the upstream chamber exceeds a predetermined pressure, the pressure is increased. By the action of the above, the valve body is separated from the opening portion to open the opening portion.

Here, the passage penetrating the separator may be a pipe (that is, an inner pipe) attached so as to penetrate the separator, or may be a through hole formed in the separator. Further, the inside of the muffler may be divided by a plurality of separators, and in this case, the opening, the valve element and the biasing element may be attached to at least one of the plurality of separators.

According to the muffler for an internal combustion engine of the first aspect, when the pressure in the upstream chamber is equal to or lower than the predetermined pressure, the valve body closes the opening of the separator by the urging force of the urging body and the pressure of the downstream chamber. On the other hand, when the pressure is equal to or higher than the predetermined pressure, the valve body separates from the opening portion and opens the opening portion against the biasing force of the biasing body due to the action of the pressure. Therefore, for example, when the number of revolutions of the internal combustion engine is low and the pressure of the exhaust gas is low, the opening of the separator is closed and the sound deadening effect is improved. On the other hand, when the rotational speed is high and the exhaust gas pressure is high, the back pressure is reduced because the opening is opened.

In the muffler for an internal combustion engine according to the first aspect of the invention, since the valve body pivotally mounted on the separator and the biasing body for biasing the valve body perform the above-described operation, the muffler as in the conventional art is used. Compared to the case of using a pipe, the number of parts is smaller, and the efficiency of the assembling work is improved, and the manufacturing cost and weight are reduced.

The invention according to claim 2 is the muffler for an internal combustion engine according to claim 1, wherein the valve element is axially supported by a stay formed by cutting and raising a part of the separator. And According to the muffler for an internal combustion engine according to the second aspect, in addition to the same effect as the first aspect, a part of the separator is cut and raised to form a stay, and the valve element is pivotally supported on the stay. The manufacturing cost and weight are further reduced as compared with the structure in which the stay is attached to the separator as a separate body.

The invention according to claim 3 is for an internal combustion engine in which the interior is partitioned by a separator into an upstream chamber and a downstream chamber of exhaust gas, and the exhaust gas flows from the upstream chamber to the downstream chamber through a passage passing through the separator. In the muffler, an opening formed in the separator separately from the passage, and a valve element attached to the separator so as to close the opening and urging itself in a direction of closing the opening. With the above configuration, when the pressure in the upstream chamber becomes equal to or higher than a predetermined pressure, the valve element is separated from the opening portion by the action of the pressure and opens the opening portion.

Here, the passage penetrating the separator may be an inner pipe or a through hole formed in the separator. Further, the inside of the muffler may be divided by a plurality of separators, and in this case, the opening and the valve body may be attached to at least one of the plurality of separators. Further, the valve element is made of, for example, a material having a spring property (preferably a material having heat resistance in consideration of the high temperature inside the muffler), specifically, Inconel 718 (Inconel is a trade name, the same applies hereinafter),
A valve element may be formed of SUS304 or the like, and the vicinity of the upper side of the valve element may be fixed to the separator so that the opening is closed by substantially the entire valve element.

According to the muffler for an internal combustion engine of the third aspect, when the pressure in the upstream chamber is equal to or lower than the predetermined pressure, the valve body closes the opening of the separator by the urging force of the valve body and the pressure in the downstream chamber. . On the other hand, when the pressure is equal to or higher than the predetermined pressure, the valve body separates from the opening portion and opens the opening portion against the biasing force of the valve element due to the action of the pressure. Therefore, for example, when the number of revolutions of the internal combustion engine is low and the pressure of the exhaust gas is low, the opening of the separator is closed and the sound deadening effect is improved. On the other hand, when the rotational speed is high and the exhaust gas pressure is high, the back pressure is reduced because the opening is opened.

Since the muffler for an internal combustion engine according to claim 3 performs the above-mentioned action by the valve element swingably attached to the separator, the number of parts is smaller than that in the case where the bypass inner pipe is used as in the conventional case. In addition, because it does not require a separate biasing element, the structure is further simplified,
The efficiency of the assembling work, the manufacturing cost and the weight can be reduced.

The invention according to claim 4 is the muffler for an internal combustion engine according to any one of claims 1 to 3, wherein an inlet pipe for introducing exhaust gas discharged from the engine to the upstream chamber side, and the downstream side An outlet pipe for discharging the exhaust gas on the chamber side to the outside is provided, and a passage passing through the separator is formed by one or more holes bored in the separator, and the pipe except for the inlet pipe and the outlet pipe is a pipe. Characterized by not using.

According to the internal combustion engine muffler of the fourth aspect, the number of parts is smaller than that in the case where the inner pipe is used as the passage penetrating the separator. Therefore, the structure is further simplified and the assembling work is improved. Efficiency, manufacturing cost and weight can be reduced.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the embodiment of the present invention
It is needless to say that the present invention is not limited to the following embodiments, and can take various forms within the technical scope of the present invention. [First Embodiment] FIG. 1 is a schematic configuration diagram of the first embodiment.
2 is a sectional view taken along the line AA of FIG. 1, FIG. 3 is a sectional view taken along the line BB of FIG. 1, and FIG. 4 is a sectional view taken along the line CC of FIG.

The muffler of the first embodiment comprises a housing 6 in which both ends of a cylindrical outer wall 1 are closed by a front end wall 2 and a rear end wall 4. The interior of the housing 6 is divided by the first separator 8 and the second separator 10 into three chambers, that is, an uppermost flow chamber 12, an upstream chamber 14, and a downstream chamber 16. The uppermost chamber 12 is the rear end wall 4
And formed by being surrounded by the second separator 10 and the outer wall 1,
The upstream chamber 14 is formed by being surrounded by the first separator 8, the second separator 10 and the outer wall 1, and the downstream chamber 16 is formed by being surrounded by the front end wall 2, the first separator 8 and the outer wall 1.

On the other hand, an inlet pipe 18, which is connected to an exhaust pipe of an internal combustion engine (not shown) through a catalyst device or the like, is inserted through the front end wall 2, the first separator 8 and the second separator 10, and the tip thereof is the most upstream. The chamber 12 is open and arranged. Further, the outlet pipe 20 is inserted through the first separator 8, the second separator 10 and the rear end wall 4, one end of which is opened to the downstream chamber 16 and the other end of which is opened to the outside to connect the downstream chamber 16 and the outside. It is arranged to do.

As shown in FIGS. 1 and 3, the second separator 10 is provided with a large number of through holes 22 which connect the most upstream chamber 12 and the upstream chamber 14. In addition, as shown in FIG. 2, the first separator 8 has an upstream chamber 14 and a downstream chamber 16.
An opening 25 (opening of the present invention) provided with four through holes 24 (passages of the present invention) and a flange 25a that communicate with each other is formed. A valve assembly 30 is attached to the opening 25 of the first separator 8.

FIG. 5 is an assembled perspective view of the valve assembly. As shown in FIG. 5, the valve assembly 30 is
The valve element support member 31, the valve element 32, the wire mesh 35, the coil spring 42, and the pin 36 are included. The valve body support member 31 has a central hole 31 provided at substantially the center of the main body 31a.
b, a taper portion 31c extending from the periphery of the central hole 31b toward the rear (to the right in the figure) so as to gradually reduce in diameter, and a first portion provided behind the taper portion 31c.
A cylindrical portion 31d fitted into the opening 25 of the separator 8;
Stays 31 provided on the left and right sides of the upper portion of the main body 31a
e, 31e.

The wire mesh 35 is composed of the valve body support member 31.
Is fixed to the inner peripheral surface of the tapered portion 31c. Valve 32
Is provided with a substantially frustoconical projection 32a near its center, and the outer peripheral surface of this projection 32a is formed in a shape overlapping and coinciding with the wire mesh 35 fixed to the taper 31c. Further, the rear end surface 32b of the convex portion 32a bulges in the exhaust gas flowing direction (that is, the direction from the upstream chamber 14 toward the downstream chamber 16) as shown in FIG. The valve element 32 is swingably attached to the stays 31e, 31e via a pin 36. In addition, as shown in FIG.
A cushioning material (wire mesh) 37 is interposed in the gap between e and 31e and the valve body 32. Further, the coil spring 42 has the pin 36 inserted through the axis thereof, one arm portion 42a of the coil spring 42 is fixed to the valve body support member 31, and the other arm portion 42b presses the valve body 32. Therefore, the valve body 32 can swing in the direction of the arrow in FIG. 4 about the pin 36, but by being urged toward the opening 25 side of the first separator 8 by the coil spring 42, the convex portion of the valve body 32 is urged. Three
2a is pressed by the wire mesh 35 provided on the taper portion 31c to overlap and coincide with each other to close the opening 25 (see the solid line in FIG. 4).

Next, the operation of the muffler of this embodiment will be described. Exhaust gas from the internal combustion engine is introduced into the most upstream chamber 12 via an inlet pipe 18, as shown by a dotted arrow in FIG. The exhaust gas is silenced by the expansion / resonance effect when introduced into the most upstream chamber 12, and subsequently introduced into the upstream chamber 14 through a large number of through holes 22 formed in the second separator 10 and expanded / extended again. Muted due to the resonance effect. Then, the exhaust gas in the upstream chamber 14 is introduced into the downstream chamber 16 through the four through holes 24 (see FIG. 2) formed in the first separator 8 and is further silenced by the expansion / resonance effect. In this way, the exhaust gas in the downstream chamber 16 in which the pressure pulsation is smoothed and silenced is discharged to the outside through the outlet pipe 20.

Here, the pressure in the upstream chamber 14 is still low,
For example, when the rotation speed of the internal combustion engine is low, the pressure difference between the upstream chamber 14 and the downstream chamber 16 is also small. At this time, the acting force exerted on the valve body 32 by the pressure in the upstream chamber 14 is smaller than the sum of the urging force of the coil spring 42 and the acting force exerted on the valve body 32 by the pressure in the downstream chamber 16. Therefore, the opening 25 of the first separator 8 is closed by the valve body 32, the resonance effect in the upstream chamber 14 is enhanced, and the sound deadening property is improved.

On the other hand, when the operating state of the internal combustion engine changes, for example, the number of revolutions of the internal combustion engine increases, the amount of exhaust gas increases, and the pressure increases to a predetermined pressure, the pressure in the upstream chamber 14 changes to the valve body. The acting force exerted on 32 is larger than the sum of the urging force of the coil spring 42 and the acting force exerted on the valve body 32 by the pressure in the downstream chamber 16. As a result, the valve element 32 is separated from the opening 25 of the first separator 8 against the latter force, and the opening 25 is opened (indicated by a chain line in FIG. 4). As a result, the upstream chamber 14 and the downstream chamber 16 are separated from each other by 4 of the first separator.
In addition to the two through holes 24 (see FIG. 2), the openings 25 communicate with each other.

As described above, when the pressure in the upstream chamber 14 becomes equal to or higher than the predetermined pressure, the opening 25 of the first separator 8 is opened and the bypass flow passage is separately formed. Even if the amount increases, it is quickly discharged to the downstream chamber 16. Therefore, the pressure in the upstream chamber 14 does not increase, and even if the pressure of the exhaust gas from the internal combustion engine increases, its back pressure does not increase. Further, even when the exhaust gas flow rate is increased, the pressure increase in the muffler can be suppressed to a low level, so that the air flow noise can be reduced.

By the way, when the valve element 32 closes the opening 25 of the first separator 8, the valve element 32 is opened from the open state (shown by the chain double-dashed line in FIG. 4) around the pin 36.
The convex portion 32a of the valve element 32 fits into the tapered portion 31c of the valve element support member 31 and closes the opening 25. At this time, the convex portion 32a of the valve body 32 is not tapered.
The collision force exerted on c is (1) dispersed in the collision direction and the outer radial direction, (2) dispersed as a frictional force between the convex portion 32a and the wire mesh 35, and (3) the wire mesh 3
5 absorbs the collision force, and so on.
Therefore, the collision noise generated when the valve body 32 closes the opening 25 can be suppressed.

The effects of the above first embodiment will be described below. A valve assembly 30 swingably attached to the first separator 8 and a coil spring 42 for urging the valve element 32.
In order to achieve the above-mentioned action, compared to the case where the bypass inner pipe is attached to the separator as in the conventional case and the valve assembly is attached to the opening end of the bypass inner pipe, the bypass inner pipe is not used, and the number of parts is small, The efficiency of the assembling work, the manufacturing cost and the weight can be reduced. Since the rear end surface 32b of the convex portion 32a of the valve body 32 is bulged in the exhaust gas flowing direction, the pressure change of the exhaust gas can be efficiently transmitted to the valve body 32, and more appropriate control of the valve body 32 is possible. I am trying. In the first embodiment, no pipe is used other than the inlet pipe 18 and the outlet pipe 20. That is,
In the first embodiment, since the through hole 22 is provided as a passage that penetrates the first separator 8, the number of parts is smaller than that in the case where an inner pipe is used as such a passage, the structure is further simplified, and the assembling work is easy. High efficiency, manufacturing cost and weight reduction are achieved. [Second Embodiment] FIG. 6 is a sectional view of a main portion of the second embodiment, and FIG. 7 is an assembled perspective view of a valve assembly of the second embodiment.

The second embodiment is the same as the first embodiment except that the valve support member 31 of the first embodiment is not used and the first separator 8 is processed to perform the function of the valve support member 31. The configuration is the same as the example. Therefore, the same constituent elements are given the same reference numerals and the description thereof is omitted.

The valve assembly 80 of the second embodiment is
The valve body 32, the wire mesh 35, the coil spring 42, and the pin 36 are included. Stays 81 and 81 are formed in the first separator 8 by cutting and raising a part thereof. The valve element 32 is swingably supported between the stays 81 via a pin 36. Further, the first separator 8 is formed with a tapered flange 75a.
That is, the tapered flange 75a extends from the peripheral edge of the opening 75 of the first separator 8 so as to gradually decrease in diameter rearward (to the right in FIG. 6). The wire mesh 35 is fixed to the inner peripheral surface of the tapered flange 75a.

Since the operation of the muffler of the second embodiment is the same as that of the first embodiment, its description will be omitted. The second embodiment has the following effects in addition to the effects of the first embodiment. That is, since the valve body support member 31 of the first embodiment is not required, the structure is simpler than that of the first embodiment, and the manufacturing cost and weight are further reduced. [Third Embodiment] FIG. 8 is a sectional view of a main portion of the third embodiment.

In the third embodiment, the valve body support member 31 of the first embodiment is not used, and the first separator 8 is processed so that the function of the valve body support member 31 is fulfilled. The configuration is the same as that of the first embodiment except that the valve body 82 is used. Therefore, the same constituent elements are given the same reference numerals and omitted.

The valve assembly 90 of the third embodiment is
It is composed of a valve body 82, a wire mesh 35, a coil spring 42, and a pin 36. A stay 91 similar to that of the second embodiment is formed on the first separator 8 by cutting and raising a part thereof.
91 (only one shown in FIG. 8) is formed. Further, the first separator 8 is formed with a tapered flange 95a. That is, the tapered flange 95a is the first
It extends from the periphery of the opening 95 of the separator 8 so as to gradually decrease in diameter toward the front (to the left in FIG. 8).
The wire mesh 35 is fixed to the outer peripheral surface of the tapered flange 95a.

The valve body 82 is provided with a substantially frustoconical projection 82a near the center thereof. The convex portion 82a projects in the direction of exhaust gas flow (leftward in FIG. 8). The inner peripheral surface of the convex portion 82a is formed in a shape that overlaps and coincides with the wire mesh 35 fixed to the outer peripheral surface of the tapered flange 95a. The rear end surface 82b of the convex portion 82a is a flat surface. The valve body 82 is connected to the stay 9 via the pin 36.
It is swingably attached to Nos. 1 and 91.

Since the operation and effect of the muffler of the third embodiment are the same as those of the second embodiment, the description thereof will be omitted. [Fourth Embodiment] FIGS. 9A and 9B are explanatory views of the main part of the fourth embodiment, wherein FIG. 9A is an assembled perspective view and FIG. 9B is a sectional view.

The fourth embodiment is the same as the first embodiment except that the opening 25, the flange 25a and the valve assembly 30 of the first embodiment are changed, and thus the same components are designated by the same reference numerals. , The description is omitted. The valve body 132 is
The rectangular mounting member 133 is formed to have a size that fits into the opening 125 provided in the first separator 8 and is formed by rivets or the like.
Is joined to. The valve body 132 is made of ordinary stainless steel having no spring property, for example, SUS409LT-E. On the other hand, the mounting member 133
Is a material having elasticity, for example, Inconel 718, S
It is formed of US304 or the like and corresponds to the biasing body of the present invention. This valve body 132 has a mounting member 133.
With rivets 136, 136 through the two holes of the first
It is fixed to the separator 8. In this way, the valve body 132
In the state where the attachment member 133 is fixed to the first separator 8, is urged by the spring property of the attachment member 133 so as to close the opening 125.

The operation of the muffler of the fourth embodiment will be described. When the pressure in the upstream chamber 14 is below a predetermined pressure, the mounting member 1
Due to the urging force of 33 and the pressure of the downstream chamber 16, the valve element 132
Closes the opening 125 of the first separator 8. On the other hand, when the pressure in the upstream chamber 14 is equal to or higher than the predetermined pressure, the valve body 132 is separated from the opening 125 and opens the opening 25 against the biasing force of the mounting member 133 due to the action of the pressure (dashed line in FIG. 9). reference). Therefore, for example, when the rotation speed of the internal combustion engine is low and the pressure of the exhaust gas is low, the opening 1 of the first separator 8 is
Since 25 is closed, the sound deadening effect is improved. On the other hand, when the rotational speed is high and the exhaust gas pressure is high, the back pressure is reduced because the opening is opened. The muffler of the fourth embodiment has the effects of and of the first embodiment. [Fifth Embodiment] FIGS. 10A and 10B are explanatory views of the main part of the fifth embodiment. FIG. 10A is an assembled perspective view and FIG. 10B is a sectional view.

The fifth embodiment is the same as the first embodiment except that the opening 25, the flange 25a and the valve assembly 30 of the first embodiment are changed. Therefore, the same components are designated by the same reference numerals. , The description is omitted. The valve body 232 is
Material having spring property, for example, Inconel 718, SUS
The rectangular mounting portion 23 is formed by 304.
2a and a valve body 232b having a size capable of closing the opening 225 provided in the first separator 8. Mounting part 2
The bent portion 23 is provided at the boundary between the valve body 32a and the valve body 232b.
2c is provided. This valve body 232 has a pin 23
It is fixed to the first separator 8 through the two holes of the attachment portion 232a by the reference numerals 6 and 236. When the mounting portion 232a is fixed to the first separator 8, the valve body 232 is
It urges itself to close the opening 225.

The operation of the muffler of the fifth embodiment will be described. When the pressure in the upstream chamber 14 is equal to or lower than the predetermined pressure, the valve body 232
Due to its own biasing force and the pressure in the downstream chamber 16, the valve body 232
Closes the opening 225 of the first separator 8. On the other hand, when the pressure in the upstream chamber 14 is equal to or higher than the predetermined pressure, the valve body 232 resists its own urging force and the like due to the action of the pressure, and the bending portion 232 is prevented.
The opening 225 is opened apart from the opening 225 while being bent at c (see the alternate long and short dash line in FIG. 10). Therefore, for example, when the rotation speed of the internal combustion engine is low and the pressure of the exhaust gas is low, the opening 225 of the first separator 8 is closed, so that the sound deadening effect is improved. On the other hand, when the rotational speed is high and the exhaust gas pressure is high, the back pressure is reduced because the opening is opened.

This fifth embodiment has the following effects in addition to the effects of and of the first embodiment. That is, since the fifth embodiment does not require the coil spring 42 used in the first to third embodiments, the structure is simpler than that of the first to third embodiments, and the manufacturing cost and weight are further reduced. It

In the fifth embodiment, the bent portion 232c is provided so that the valve body 232 bends at this portion. However, if the valve body 232 is made of a spring material, the bent portion 232c is especially provided. Even without the valve body 232, the valve body 232 can bend.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a sectional view taken along line CC of FIG.

FIG. 5 is an assembled perspective view of the valve assembly of the first embodiment.

FIG. 6 is a sectional view of a main part of the second embodiment.

FIG. 7 is an assembled perspective view of the valve assembly of the second embodiment.

FIG. 8 is a sectional view of a main part of the third embodiment.

FIG. 9 is an explanatory diagram of a main part of the fourth embodiment, (a)
Is a perspective view of assembly, and FIG.

FIG. 10 is an explanatory diagram of a main part of the fifth embodiment,
(A) is an assembly perspective view, (b) is sectional drawing.

FIG. 11 is an explanatory diagram of a conventional internal combustion engine muffler.

[Explanation of symbols]

6 ... Housing, 8 ... First separator, 10 ... Second separator, 12 ... Uppermost flow chamber, 14 ... Upstream chamber, 16 ...
Downstream chamber, 18 ... Inlet pipe, 20 ...
Outlet pipe, 22 ... through hole,
24 ... through hole, 25 ... opening,
25a ... Flange, 30 ... Valve assembly, 31 ... Valve body support member, 31c ... Tapered portion, 31e ... Stay, 32 ... Valve body,
35 ... Wire mesh, 36 ...
・ Pin, 42 ・ ・ ・ Coil spring,

Claims (4)

[Claims] 1. A muffler for an internal combustion engine, the interior of which is divided into an upstream chamber and a downstream chamber of exhaust gas by a separator, and the exhaust gas flows from the upstream chamber to the downstream chamber through a passage that penetrates the separator. Separately, an opening formed in the separator, a valve body swingably attached to the separator and capable of closing / opening the opening, and a biasing element for closing the opening. For an internal combustion engine in which the valve body is separated from the opening by the action of the pressure when the pressure in the upstream chamber becomes equal to or higher than a predetermined pressure, and the opening is opened. Muffler. 2. The muffler for an internal combustion engine according to claim 1, wherein the valve element is axially supported by a stay formed by cutting and raising a part of the separator. 3. A muffler for an internal combustion engine, the interior of which is divided into an upstream chamber and a downstream chamber of exhaust gas by a separator, and the exhaust gas flows from the upstream chamber to the downstream chamber through a passage that penetrates the separator, wherein Separately, by providing an opening formed in the separator, and a valve body attached to the separator so as to close the opening, and urging itself in the direction of closing the opening, A muffler for an internal combustion engine, wherein when the pressure in the upstream chamber becomes equal to or higher than a predetermined pressure, the valve element is separated from the opening by the action of the pressure to open the opening. 4. An inlet pipe for introducing exhaust gas discharged from an engine to the upstream chamber side, and an outlet pipe for discharging exhaust gas from the downstream chamber side to the outside, and a passage passing through the separator is in the separator. The muffler for an internal combustion engine according to any one of claims 1 to 3, wherein the muffler is formed by one or more bored holes and no pipe is used except the inlet pipe and the outlet pipe.