JP4255358B2 - Resonator structure in exhaust system for internal combustion engine - Google Patents

Description

  The present invention relates to a resonator in an exhaust system for an internal combustion engine that silences a relatively low specific frequency that causes secondary noise (humidity) generated in the passenger compartment, among exhaust noise from the engine, by resonance. Concerning structure.

  As a conventional resonator structure in this type of exhaust system for an internal combustion engine, for example, as shown in FIG. 4, outer plates (partition walls) 102 and 103 are attached to both front and rear ends of a laterally cylindrical outer shell 101, and both end openings are provided. The silencer chamber is formed by closing the chamber, and further, the silencer chamber is partitioned in the front-rear direction by the inner plate 104 (partition wall), so that the resonance chamber 105 constituting the resonator and the sound absorbing chamber constituting the sound absorbing silencer are formed. 106, and an exhaust pipe 107 is provided in a state of penetrating the outer plates 102 and 103 and the inner plate 104, and a resonance pipe is formed in a hole formed in the exhaust pipe 107 passing through the resonance chamber 105. By connecting and fixing one end of 108, the resonance tube 108 is protruded into the resonance chamber 105, so that the There is obtained by constituting the resonator HOLZ type (e.g., see Patent Document 1.).

JP-A-9-88570 (Specification (page 2), FIG. 1)

However, the conventional resonator structure in the exhaust system for an internal combustion engine has the following problems.
The resonance frequency f at which the Helmholtz type resonator resonates is generally represented by the following Hemholtz equation.
f = C × 2π × √S / L × V
C is the speed of sound, S is the cross-sectional area of the resonance tube, L is the length of the resonance tube, and V is the volume of the resonance chamber.

  Therefore, in order to effectively reduce the primary booming noise of the internal combustion engine of 2000 rpm or less, it is necessary to increase the volume V of the resonance chamber or to increase the length L of the resonance tube. Since the resonance pipe 108 in the example protrudes from the peripheral wall of the exhaust pipe 107 in one direction in the resonance chamber 105 and the resonance frequency is set by the length of the resonance pipe 108 to be protruded, the resonance chamber 105 is set. Limited by internal space.

Further, in the conventional resonance tube 108, only exhaust noise of a limited specific frequency can be reduced.
Further, the resonance pipe 108 of the conventional example is cantilever attached to the exhaust pipe 107, and stress due to vibration is concentrated on the root portion of the resonance pipe 108 as an attachment portion, so that there is a problem in terms of durability. .

  The problem to be solved by the present invention is that exhaust noise of a specific frequency can be reduced without being restricted by the resonance chamber space, and the specific frequency to be reduced can be easily set, and the durability is improved. It is another object of the present invention to provide a resonator structure in an exhaust system for an internal combustion engine that can be reduced, and to expand a range of specific frequencies that can be reduced.

In order to solve the above-mentioned problem, a resonator structure in an exhaust system for an internal combustion engine according to claim 1 is a resonator structure in an exhaust system for an internal combustion engine in which a resonance pipe projects from an exhaust pipe penetrating the resonance chamber toward the resonance chamber. The resonance tube is configured by an outer cylinder that covers the outer periphery of the exhaust pipe in the resonance chamber, and the outer cylinder is attached to the outer periphery of the exhaust pipe by narrowing the diameter of one opening edge thereof, An opening edge defines the resonance chamber and is fixed to a partition wall through which the exhaust pipe passes, and a communication hole is formed in each of a peripheral wall of the exhaust pipe surrounded by the outer cylinder and a peripheral wall of the outer cylinder ,
The outer cylinder has a means in which one of the narrowed opening edges is slidably mounted on the outer periphery of the exhaust pipe .

  In the resonator structure in an exhaust system for an internal combustion engine according to claim 1, as described above, the resonance pipe is constituted by an outer cylinder covering the outer circumference of the exhaust pipe in the resonance chamber, and the peripheral wall of the exhaust pipe surrounded by the outer cylinder. Since the communication holes are formed in the peripheral wall of the outer cylinder and the outer cylinder, the resonance tube does not protrude greatly into the resonance chamber, thereby reducing exhaust noise of a specific frequency without being restricted by the space of the resonance chamber The effect of being able to do it is acquired.

  In addition, the specific frequency to be reduced can be easily set by changing the size and position of the connecting hole.

In addition, the outer cylinder is mounted on the outer periphery of the exhaust pipe by narrowing the diameter of one opening edge, and the other opening edge is fixed to the partition wall, so that the fixed state against vibration is fixed. Can be reliably maintained, thereby improving durability. Furthermore, the other opening edge portion of the outer cylinder is fixed to the partition wall, so that the outer cylinder serves as a reinforcing rib. As a result, the rigidity of the partition wall is increased, so that the rigidity of the resonance chamber can be increased. It becomes like this.
Further, the outer cylinder has a structure in which the narrowed opening edge of the outer cylinder is slidably attached to the exhaust pipe, so that the sliding portion absorbs the difference in thermal expansion between the exhaust pipe and the outer cylinder. This can prevent deformation of the member due to thermal stress.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

The resonator structure in the exhaust system for the internal combustion engine of the first embodiment corresponds to the inventions described in claims 1 and 2 .
First, a resonator structure in an exhaust system for an internal combustion engine according to the first embodiment will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a resonator structure in an exhaust system for an internal combustion engine according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1. As shown in FIGS. The silencer chamber is formed by attaching the outer plates 2 and 3 to both front and rear ends of the laterally cylindrical outer shell 1 and closing the openings on both ends.

  The silencer chamber is partitioned by an inner plate (partition wall) 4 into a front (left side in FIG. 1) resonance chamber 5R and a rear (right side in FIG. 1) sound absorption chamber 5F. 3 and an exhaust pipe 6 through which exhaust from the engine circulates in a state of passing through the axial center portion of the inner plate 4.

  A large number of small holes 6a communicating with the sound absorbing chamber 5F are formed in the peripheral wall of the exhaust pipe 6 in the sound absorbing chamber 5F, and the sound absorbing chamber 5F is filled with a sound absorbing material 7 such as rock wool or glass wool. ing.

Further, an outer cylinder 8 constituting a resonance pipe is provided in a state surrounding the outer periphery of the exhaust pipe 6 in the resonance chamber 5R.
That is, the outer cylinder 8 is mounted so as to be slidable on the outer periphery of the exhaust pipe 6 by narrowing the diameter of one opening edge, and the other opening edge is formed between the sound absorbing chamber 5F and the resonance chamber 5R. A space is defined and the exhaust pipe 6 is fixed to the inner plate 4 through which it is welded or the like.

  A communication hole 61 is formed in one place on the peripheral wall of the rear end (right side in FIG. 1) of the exhaust pipe 6 surrounded by the outer cylinder 8 so as to communicate between the exhaust pipe 6 and the outer cylinder 8. In addition, communication holes 81, 81, 81 communicating between the inside of the outer cylinder 8 and the inside of the resonance chamber 5 </ b> R are formed at three locations on the peripheral wall at the front (left side in FIG. 1) of the outer cylinder 8 (FIG. 2). reference).

  The outer cylinder 8 is assembled by first mounting the outer cylinder 8 on the outer periphery of the exhaust pipe 6. At this time, the opening edge of the outer cylinder 8 on the narrowed side can be slid with respect to the exhaust pipe 6. Attach to the state. Next, the exhaust pipe 6 is passed through the axial center portion of the inner plate 4, and in this state, the other opening edge of the outer cylinder 8 is fixed to the side surface of the inner plate 4 by welding or the like.

Next, operations and effects of the first embodiment will be described.
Since the resonator structure in the exhaust system for the internal combustion engine according to the first embodiment is configured as described above, the cross-sectional area of the annular space formed between the exhaust pipe 6 and the outer cylinder 8 and the communication holes 61 and 81 are formed. The opening area of the resonance tube is determined by the opening area, and the length of the resonance tube is determined by the distance from the communication hole 61 to each communication hole 81, 81, 81.

In addition to the volume of the resonance chamber 5R, by setting the opening area of the resonance tube, the opening areas of the communication holes 61 and 81, and the length of the resonance tube, a specific frequency region that can be silenced is arbitrarily determined. be able to.
That is, it is possible to easily set a specific frequency to be reduced simply by changing the size and position of the communication holes 61 and 81.

  Further, since the resonance tube is constituted by the outer cylinder 8 covering the outer periphery of the exhaust pipe 6 in the resonance chamber 5R, the outer cylinder 8 constituting the resonance tube does not protrude greatly into the resonance chamber 5R. There is an effect that exhaust noise of a specific frequency can be reduced without being restricted by the space in the resonance chamber 5R.

  Further, the outer cylinder 8 is attached to the outer periphery of the exhaust pipe 6 by narrowing the diameter of one opening edge portion thereof, and the other opening edge portion is fixed to the inner plate 4. Thus, it is possible to reliably maintain the fixed state, thereby improving durability.

  Furthermore, the other opening edge of the outer cylinder 8 is fixed to the inner plate 4 so that the outer cylinder 8 serves as a reinforcing rib, thereby increasing the rigidity of the inner plate 4 and, as a result, the silencer. It becomes possible to increase the rigidity of the chamber.

  In addition, by forming the three communication holes 81 on the outer cylinder 8 side, the width of the silencing region is widened, and a large silencing volume can be obtained especially on the high frequency side. (Corresponding to claim 2).

  Further, the outer cylinder 8 has a structure in which the narrowed opening edge of the outer cylinder 8 is slidably attached to the exhaust pipe 6, thereby sliding the difference in thermal expansion between the exhaust pipe 6 and the outer cylinder 8. It can be absorbed by the portion, and thereby deformation of the member due to thermal stress can be prevented. (Corresponding to claim 4).

  Further, in the conventional example shown in FIG. 4, when the resonance tube 108 is attached to the hole provided in the peripheral wall of the exhaust pipe 107, the circumferential angle of the resonance tube 108 with respect to the hole is determined and the position of the resonance tube 108 is matched. In this embodiment, the circumferential positional relationship between the communication hole 61 formed in the peripheral wall of the exhaust pipe 6 and the outer cylinder 8 constituting the resonance pipe has a degree of freedom. Therefore, it is possible to easily assemble without using a jig or the like, thereby improving the assemblability.

  Next, another embodiment will be described. In the description of the other embodiments, the same components as those of the first embodiment are not shown, or the same reference numerals are given and the description thereof is omitted, and only the differences are described.

The resonator structure in the exhaust system for the internal combustion engine of the second embodiment corresponds to the invention described in claims 1 to 3 .
As shown in the sectional view of FIG. 3, the resonator structure in the exhaust system for the internal combustion engine according to the second embodiment has three communication holes 81, 81, 81 formed on the outer cylinder 8 side. It is different from the first embodiment in that it is formed with its position shifted in the direction.

  That is, in the second embodiment, since the distance from the communication hole 61 to each of the communication holes 81, 81, 81 is different, there are three types of resonance tubes having different lengths. The frequency range can be expanded. (Corresponding to claim 3).

  Therefore, in the resonator structure in the exhaust system for the internal combustion engine of the second embodiment, the same effect as the first embodiment can be obtained, and the specific frequency region that can be silenced by only one outer cylinder 8 can be expanded. An additional effect is obtained.

  Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment, and design changes and the like within a scope not departing from the gist of the present invention are included in the present invention.

For example, in the embodiment, the three communication holes 81, 81, 81 are formed on the outer cylinder 8 side, but only one may be formed, and the number of the formation is arbitrary.
In the embodiment, the sound absorbing chamber 5F is provided side by side, but only the sound absorbing chamber 5F may be provided alone.

  Further, in the embodiment, one opening edge portion of the outer cylinder 8 is fixed to the inner plate 4 side, but can be fixed to the outer plate 3 side, and when the sound absorption chamber 5F and the resonance chamber R5 are switched back and forth, Alternatively, when only the resonance chamber 5R is provided, it may be fixed to the outer plate 2 side.

1 is a cross-sectional view showing a resonator structure in an exhaust system for an internal combustion engine according to a first embodiment. It is sectional drawing in the II-II line of FIG. FIG. 5 is a cross-sectional view showing a resonator structure in an exhaust system for an internal combustion engine according to a second embodiment. It is sectional drawing which shows the resonator structure in the exhaust system for internal combustion engines of a prior art example.

Explanation of symbols

1 outer shell 2 outer plate 3 outer plate 4 inner plate (partition wall)
5F Sound absorption chamber 5R Resonance chamber 6 Exhaust pipe 6a Small hole 61 Communication hole 7 Sound absorbing material 8 Outer cylinder (resonance tube)
81 communication hole

Claims (3)

In the resonator structure in the exhaust system for an internal combustion engine in which the resonance pipe protrudes from the exhaust pipe penetrating the resonance chamber toward the resonance chamber,
The resonance pipe is formed of an outer cylinder that covers the outer periphery of the exhaust pipe in the resonance chamber, and the outer cylinder is attached to the outer periphery of the exhaust pipe by narrowing the diameter of one opening edge thereof, and the other opening An edge defines the resonance chamber and is fixed to a partition wall through which the exhaust pipe passes,
Communication holes are formed in the peripheral wall of the exhaust pipe surrounded by the outer cylinder and the peripheral wall of the outer cylinder ,
A resonator structure in an exhaust system for an internal combustion engine, wherein one of the narrowed opening edges is slidably mounted on the outer periphery of the exhaust pipe .   2. A resonator structure for an exhaust system for an internal combustion engine according to claim 1, wherein said communication hole is formed at one location on a peripheral wall of said exhaust pipe and at a plurality of locations of said outer cylinder. Resonator structure in the system.   3. A resonator structure in an exhaust system for an internal combustion engine according to claim 2, wherein the plurality of communication holes formed on the outer cylinder side are formed in a state in which the positions are shifted in the axial direction of the outer cylinder. A resonator structure in an exhaust system for an internal combustion engine.

Images