JP4278789B2 - Silencer for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a silencer for an internal combustion engine, and more particularly to a valve body that opens and closes an inner pipe thereof.
[0002]
[Prior art]
Generally, a silencer for an internal combustion engine includes a main body that is partitioned into a plurality of chambers by a partition, an inlet pipe and an outlet pipe that communicate with two different chambers of the main body, and the two different chambers that penetrate the partition. It has an inner pipe that communicates and a valve body that opens and closes the inner pipe. When the internal combustion engine rotates at low speed, the valve body closes the inner pipe to improve the noise reduction effect. Is supposed to decrease.
[0003]
By the way, in the conventional silencer, a bracket is provided on the outer peripheral surface of one end of the inner pipe, and one end of the valve body is rotatably connected to the bracket. A coil spring is provided between the valve body and the bracket, and the inner pipe is closed by abutting the valve body against the opening end of the inner pipe with this coil spring (see Japanese Patent Laid-Open No. 9-170425). ).
[0004]
[Problems to be solved by the invention]
A conventional silencer for an internal combustion engine requires a bracket for attaching it to the inner pipe and a coil spring for opening and closing the valve body, and the number of parts increases accordingly, the structure becomes complicated, There was a problem that the manufacturing cost increased.
Further, the end of the inner pipe opposite to the end to which the valve element is attached is flared, and the outer diameter of the end is increased in a tapered shape. For this reason, if a valve body etc. are previously attached to the inner pipe, the inner pipe cannot be inserted into the partition wall and cannot be attached to the main body. Therefore, the valve body and the like are attached after the inner pipe is attached to the main body. However, since the inner space of the main body is narrow for the work of attaching the inner pipe, there is a problem that it is very difficult to attach the valve body or the like to the inner pipe.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention communicates a main body that is partitioned into a plurality of chambers, an inlet pipe and an outlet pipe that communicate with two different chambers of the main body, and the two chambers. In the silencer for an internal combustion engine comprising an inner pipe to be opened and a valve body for opening and closing the inner pipe, the valve body is disposed inside the inner pipe and one end thereof is fixed to the inner surface of the inner pipe. The fixed one end side portion is elastically deformed so that the other end portion of the valve body is rotated in the axial direction of the inner pipe around the one end fixing portion, so that the inner pipe can be opened and closed. It is characterized in that at least one end side portion of the valve body is formed in a corrugated cross section so as to be elastically deformable.
In this case, it is desirable that at least a portion of the inner pipe where the valve body is installed is formed in a quadrangular cross section, and the valve body is formed in a quadrangular shape corresponding to the inner pipe. Further, it is desirable to increase the pitch of the wavy portion of the valve body on the fixed end side.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
1 to 3 show an embodiment of the present invention. A silencer A for an internal combustion engine according to this embodiment includes a hollow main body 1 having a cylindrical shape or an elliptical cylindrical shape. The inside of the main body 1 is divided into three chambers 3A, 3B, 3C by two partition walls 2A, 2B. The inside of the main body 1 may be partitioned into two chambers by one partition, or may be partitioned into four or more chambers by three or more partitions.
[0007]
The main body 1 is provided with an inlet pipe 4 and an outlet pipe 5. One end of the inlet pipe 4 is connected to the exhaust side of an engine (not shown). The other end of the inlet pipe 4 passes through one side wall (the left side wall in FIG. 1) of the main body 1, the chambers 3C and 3B, and the partition walls 2B and 2A and opens into the chamber 3A. A large number of small holes 4a are formed in a portion of the inlet pipe 4 facing the chamber 3B. Therefore, engine exhaust gas is introduced into the chambers 3A and 3B. One end of the outlet pipe 5 is open to the chamber 3C. The other end of the outlet pipe 5 passes through the partition walls 2B and 2A, the chambers 3B and 3A, and the other side wall of the main body 1 (the right side wall in FIG. 1) and protrudes outside the main body 1.
[0008]
Two inner pipes 6 and 7 are provided inside the main body 1. One inner pipe 6 is fixed to the partition 2B so as to penetrate through the partition 2B, and one end opens into the chamber 3B and the other end opens into the chamber 3C. At the end of the inner pipe 6 facing the chamber 3B, a tapered diameter-expanded portion 6a is formed by flaring. The other inner pipe 7 penetrates the partition walls 2A and 2B and the chamber 3B, and has one end opened to the chamber 3A and the other end opened to the chamber 3C. The end portion of the inner pipe 7 facing the chamber 3A is flared to form a tapered enlarged diameter portion 7a.
[0009]
A valve body 8 is provided inside the inner pipe 7 on the side of the chamber 3 </ b> C so that its center substantially coincides with the axis of the inner pipe 7. The valve body 8 closes the inner pipe 7 while the pressure of the exhaust gas is low as in idling. Therefore, at that time, the exhaust gas of the engine flows into the chamber 3B from the small hole 4a, and is discharged to the outside through the inner pipe 6, the chamber 3C, and the outlet pipe 5. As a result, the silencing effect is improved. On the other hand, when the pressure of the exhaust gas is high, such as during high-speed rotation, the valve body 8 opens the inner pipe 7. Accordingly, a part of the exhaust gas flows into the chamber 3C through the inner pipe 6 in the same manner as when idling, while many other exhaust gases flow into the chamber 3A from the inlet pipe 4 and pass through the inner pipe 7 to the chamber. It flows into 3C. This reduces the exhaust resistance of the exhaust gas and prevents the pressure from increasing. The exhaust gas that has flowed into the chamber 3 </ b> C is discharged to the outside through the outlet pipe 5.
[0010]
The valve body 8 is made of a metal plate material, for example, a stainless steel plate material, and is formed in a circular shape corresponding to the inner pipe 7. A flat fixing portion 81 is formed on a part of the outer peripheral side of the valve body 8 by bending the valve body 8 at a substantially right angle. On the other hand, a flat portion 71 corresponding to the fixed portion 81 is formed on the inner peripheral surface of the inner pipe 7 by crushing one side portion. The fixed portion 81 is fixed to the flat portion 71 by spot welding, arc welding, or other fixing means, whereby the valve body 8 is fixed to the inner peripheral surface of the inner pipe 7. The flat portion 71 may be formed on any of the upper, lower, left and right side portions of the inner peripheral surface of the inner pipe 7, but it is formed on the upper portion as in this embodiment, whereby the valve body 8 is It is desirable to rotate around the upper end.
[0011]
In the valve body 8, the half on the fixed portion 81 side is a wavy portion 82, and the opposite half is a flat plate portion 83. The wavy portion 82 is formed by bending a portion between the fixing portion 81 and the substantially central portion of the valve body 8 at a predetermined pitch to form a large number of irregularities having a substantially U-shaped cross section extending in parallel with the fixing portion 81. Has been. Therefore, as shown by an imaginary line in FIG. 2, the wavy portion 82 is elastically deformable so that the flat plate portion 83 can be rotationally displaced in the axial direction of the inner pipe 7 around the fixed portion 81. When the portion 82 is elastically deformed, the valve body 8 opens the inner pipe 7, and the valve body 8 closes the inner pipe 7 when the waved portion 82 returns to its original shape. The outer diameter of the valve body 8 is slightly smaller than the inner diameter of the inner pipe 7 so that the outer peripheral surface of the valve body 8 does not abut against the inner peripheral surface of the inner pipe 7 when the valve body 8 rotates.
[0012]
In the silencer A configured as described above, the valve body 8 closes the inner pipe 7 when the pressure of the exhaust gas supplied to the chamber 3A is low as during idling. Therefore, exhaust noise can be reduced. On the other hand, when the pressure of the exhaust gas supplied to the chamber 3A increases, the wave-like portion 82 of the valve body 8 is elastically deformed by the pressure of the exhaust gas to open the inner pipe 7, as indicated by an imaginary line in FIG. Therefore, the exhaust resistance of the exhaust gas can be reduced and the pressure can be prevented from becoming excessively high.
[0013]
Thus, in the silencer A, since the valve body 8 itself can be elastically deformed, it is not necessary to use a bracket and a coil spring. Therefore, the number of parts can be reduced by that amount, whereby the structure can be simplified and the manufacturing cost can be reduced.
[0014]
Note that the valve body 8 can be elastically deformed even if the thickness of the valve body 8 is reduced instead of forming the wave-like portion 82. However, when the thickness of the valve body 8 is made thin and can be elastically deformed, the pressure of the exhaust gas and the opening of the inner pipe 7 by the valve body 8 are only changed slightly. The relationship with will change greatly. For this reason, it is necessary to maintain the thickness of the valve body 8 with high accuracy, and as a result, the manufacturing cost of the valve body 8 is increased. In this regard, when the wavy portion 82 is formed, the variation in the thickness of the valve body 8 can be absorbed by the pitch of the concaves and convexes constituting the wavy portion 82, the radius of curvature, etc., and these are also highly accurate. There is no need. Therefore, the manufacturing cost of the valve body 8 can be reduced.
[0015]
Moreover, since a bracket, a coil spring, etc. are unnecessary, the valve body 8 can be arrange | positioned inside the inner pipe 7. FIG. When the valve body 8 is disposed inside the inner pipe 7, the inner pipe 7 to which the valve body 8 is attached can be inserted into the partition walls 2A and 2B from the end on the valve body 8 side. Therefore, the valve body 8 can be attached to the inner pipe 7 in advance. Therefore, the valve body 8 can be easily attached to the inner pipe 7.
[0016]
Furthermore, when the valve body 8 is disposed inside the inner pipe 7, the amount of protrusion from the inner pipe 7 when the valve body 8 is opened is compared with the case where the valve body 8 is disposed outside the inner pipe 7. Can be small. Of course, if the valve body 8 is arranged further away from the opening of the inner pipe 7, it is possible to prevent the valve body 8 from protruding from the inner pipe 7 at all. Therefore, even if the distance between the left end of the inner pipe 7 in FIG. 1 and the side wall of the main body 1 facing the inner pipe 7 is narrow, the inner pipe 7 can be disposed in the main body 1 without any problem. In other words, the distance between the left end portion of the inner pipe 7 and the side wall of the main body 1 can be reduced, whereby the silencer A can be reduced in size.
[0017]
Next, another embodiment of the present invention will be described. In the following embodiments, only components that are different from the above embodiments will be described, and the same components will be denoted by the same reference numerals, and description thereof will be omitted.
[0018]
4 and 5 show a second embodiment of the present invention. In this embodiment, the entire valve body 8 is a wave-shaped portion 82 except for the fixing portion 81.
[0019]
FIGS. 6 and 7 show a third embodiment of the present invention which is a further modification of the embodiment shown in FIGS. 4 and 5. A bracket 9 is fixed to the inner peripheral surface of the inner pipe 7. Has been. The bracket 9 replaces the flat portion 71 of the above-described embodiment, and the fixing portion 81 of the valve body 8 is fixed to the bracket 9.
[0020]
In the embodiment shown in FIG. 8, the inner pipe 7 has a rectangular or square cross section, and the valve body 8 is formed in a rectangular or square shape correspondingly. In this way, even if the size of the valve body 8 is the same as the size of the inside of the inner pipe 7, the outer peripheral surface (both left and right side surfaces) of the inner pipe 7 is opened when the valve body 8 is opened and rotated. It does not hit the inner surface. Therefore, the gap between the valve body 8 and the inner pipe 7 at the time of closing can be suppressed to a necessary minimum size. Moreover, the process can be easily performed by making the valve body 8 square.
[0021]
In the embodiment shown in FIG. 9, the pitch and the radius of curvature of the corrugations constituting the wavy portion 82 are increased on the fixed portion 81 side. If it does in this way, the internal stress which acts on the wavelike part 82 can be made small on the fixed part 81 side.
[0022]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the number of parts of the silencer for an internal combustion engine, thereby simplifying the structure and reducing the manufacturing cost. Moreover, an inner pipe can be easily attached to a main body in the state which attached the valve body beforehand. Furthermore, the space | interval of the mutually opposing part of an inner pipe and a main body can be narrowed, and the effect that a silencer can be reduced in size by it is acquired.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a first embodiment of the present invention.
FIG. 2 is an enlarged view of an X circle part in FIG. 1;
FIG. 3 is a view on arrow Y of FIG.
FIG. 4 is a cross-sectional view similar to FIG. 2 showing a second embodiment of the present invention.
FIG. 5 is a view on arrow X in FIG. 4;
FIG. 6 is a cross-sectional view similar to FIG. 2, showing a third embodiment of the present invention.
7 is a view on arrow X of FIG. 6;
FIG. 8 is a view similar to FIG. 3 showing a fourth embodiment of the present invention.
FIG. 9 is a cross-sectional view similar to FIG. 2, showing a fifth embodiment of the present invention.
[Explanation of symbols]
A Silencer 1 for Internal Combustion Engine Body 3A Chamber 3B Chamber 3C Chamber 4 Inlet pipe 5 Outlet pipe 7 Inner pipe 8 Valve body 82 Wave portion

Claims (2)

A main body divided into a plurality of chambers, an inlet pipe and an outlet pipe communicating with two different chambers of the main body, an inner pipe communicating the two chambers, and a valve body for opening and closing the inner pipe In a silencer for an internal combustion engine comprising:
The valve body is disposed inside the inner pipe, and one end portion thereof is fixed to the inner surface of the inner pipe. The fixed one end side portion is elastically deformed, and the other end portion of the valve body is fixed to the one end fixing portion. The valve body is pivoted in the axial direction of the inner pipe so that the inner pipe can be opened and closed . A silencer for an internal combustion engine, wherein the pitch of the wavy portion is increased on the fixed end side .   2. The muffler for an internal combustion engine according to claim 1, wherein at least a portion of the inner pipe where the valve body is installed is formed in a square shape in cross section, and the valve body is formed in a square shape corresponding to the inner pipe. vessel.

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