JP2001182523A - Sub-muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sub-muffler capable of reducing exhaust system vibration at the time of idling and excellently maintaining riding comfortableness, even if the sub-muffler of an internal combustion engine is provided on a downstream side of a main muffler. SOLUTION: An inlet pipe 22a is connected with an outlet pipe 22b on a downstream side by a slidable connecting part 44. The outlet pipe 22b is supported by a sub-muffler outer cylinder 2a side via a separator 48 for reinforcing. Therefore, a vibration system with the main muffler as a node is up to the inlet pipe 22a. Therefore, mass of the vibration system becomes small and mass m can be reduced in an equation [f=(1/2π) (k/m)1/2] of a resonance vibration frequency f expressed by mass m and a spring constant k. As a result, the resonance vibration frequency f does not lower up to an iding area, large vibration of an exhaust system at the time of idling can be prevented and seating comfortableness can be excellently maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sub-muffler used in an exhaust system of an internal combustion engine, and more particularly to a sub-muffler provided downstream of a main muffler.

[0002]

2. Description of the Related Art In an internal combustion engine used for an automobile or the like, a configuration in which a main muffler and a sub-muffler are combined is known. This sub-muffler is mounted for the purpose of eliminating insufficient muffling of the main muffler when the exhaust system is long.

For example, in a typical passenger car, FIG.
As shown by the solid line in (A), a sub-muffler is mounted on the upstream side of the main muffler. In such a configuration, the vibration generated from the internal combustion engine is in a vibration mode as indicated by a broken line in the figure with the main muffler having a large mass as a node.

[0004]

On the other hand, in an RV-type vehicle, the sub-muffler may be arranged downstream of the main muffler as shown in FIG. In such a configuration, the vibration generated from the internal combustion engine is in a vibration mode as shown by a broken line in the figure.
That is, since the main muffler vibrates as a node, FIG.
Compared with the case of (A), when the sub-muffler is located downstream of the main muffler, the length of the tail pipe downstream of the main muffler is longer or the sub-muffler is arranged at the end of the tail pipe. Because of this, the resonance frequency tends to change to a lower frequency side and its amplitude tends to increase.

[0005] For this reason, there is a possibility that resonance will occur at a relatively large amplitude in the idling rotation range as compared with the case where the sub muffler is located upstream of the main muffler. When such vibrations occur, the muffled noise during idling or the vibrations of the floor and the steering wheel may increase to deteriorate the ride comfort.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sub-muffler capable of reducing the vibration of an exhaust system during idling and maintaining good ride comfort even if the sub-muffler is provided downstream of the main muffler.

[0007]

The means for achieving the above object and the effects thereof will be described below. The sub-muffler according to claim 1 is a sub-muffler provided downstream of a main muffler in an exhaust system of an internal combustion engine,
The exhaust conduit inside the sub-muffler outer cylinder includes an inlet-side exhaust conduit and an exhaust conduit downstream of the inlet-side exhaust conduit, except that the inlet-side exhaust conduit is connected via a connection that suppresses vibration transmission inside the sub-muffler outer cylinder. It is not connected to other components.

In the sub-muffler provided downstream of the main muffler, inside the sub-muffler outer cylinder, the inlet-side exhaust pipe is not connected to other components except through a connection for suppressing vibration transmission. Examples of such a connection portion include a connection portion in which the inlet-side exhaust conduit and the downstream-side exhaust conduit can relatively move to some extent, such as a floating structure, that is, a non-rigid connection portion.
For this reason, the vibration system having the main muffler as a node is up to the inlet-side exhaust conduit, and does not include the downstream exhaust conduit, the sub-muffler outer cylinder, and the downstream. Therefore,
The mass of the vibration system is reduced, and the resonance frequency does not decrease to the idle rotation range. Therefore, a large vibration of the exhaust system at the time of idling can be prevented, and the riding comfort can be maintained satisfactorily.

According to a second aspect of the present invention, in the configuration of the first aspect, the inlet-side exhaust conduit and the downstream-side exhaust conduit are connected at the connection portion inside the sub-muffler outer cylinder, and the inlet-side exhaust is provided. The conduit is not connected to any other components inside the sub-muffler outer cylinder except for the connection portion.

As described above, the connecting portion for suppressing the transmission of vibration
The inlet-side exhaust pipe may be provided between the inlet-side exhaust pipe and the downstream-side exhaust pipe, and the inlet-side exhaust pipe may not be connected to any other components except for the connection portion inside the sub-muffler outer cylinder.

With such a configuration, the vibration system having the main muffler as a node extends to the exhaust pipe on the inlet side, and the mass of the vibration system is reduced. In this manner, large vibrations of the exhaust system at the time of idling can be prevented, and the riding comfort can be maintained satisfactorily.

According to a third aspect of the present invention, there is provided the sub-muffler according to the second aspect, wherein the connecting portion is configured such that the inlet side exhaust pipe and the downstream side exhaust pipe can relatively move. .

With such a configuration, a connecting portion for suppressing vibration transmission can be realized, and large vibration of the exhaust system at the time of idling can be prevented, so that good riding comfort can be maintained.

A sub-muffler according to a fourth aspect is characterized in that, in the configuration according to the second or third aspect, a downstream exhaust pipe is supported on the sub-muffler outer cylinder side inside the sub-muffler outer cylinder.

As described above, regarding the exhaust pipe on the downstream side,
It may be supported on the sub-muffler outer cylinder side. Even if this support does not go through the connecting portion, there is no problem because the vibration system having the main muffler as a node is up to the inlet side exhaust conduit. In this manner, large vibrations of the exhaust system at the time of idling can be prevented, and the riding comfort can be maintained satisfactorily.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, the downstream exhaust conduit is supported on the sub-muffler outer cylinder side at or near the connection portion. .

As described above, the exhaust pipe on the downstream side is supported on the sub-muffler outer cylinder side at or near the connection portion, so that the exhaust pipe on the downstream side can be sufficiently firmly supported by the sub-muffler outer cylinder. it can.

According to a sixth aspect of the present invention, in the configuration of the fourth or fifth aspect, the downstream exhaust conduit is provided with:
The sub muffler outer cylinder is supported by being connected to the sub muffler outer cylinder through a separator that partitions the inside of the sub muffler outer cylinder into a plurality of sections.

For the support on the downstream side of the exhaust conduit, a separator that reinforces the sub-muffler outer cylinder can be used without providing a special support member. Therefore, the weight of the sub-muffler does not increase.

[0020] The sub-muffler according to the seventh aspect is characterized in that:
6. In the configuration according to any one of items 6, the inlet-side exhaust conduit and the downstream-side exhaust conduit are arranged such that one of the inlet-side exhaust conduit and the downstream-side exhaust conduit accommodates the other at the connection portion. And are slidably connected.

As described above, even with a simple slide mechanism in which one of the exhaust pipe on the inlet side and the exhaust pipe on the downstream side is configured to house the other inside, the vibration system using the main muffler as a node is It can be up to the inlet side exhaust conduit. Therefore, a large vibration of the exhaust system at the time of idling can be prevented, and the riding comfort can be maintained satisfactorily.

According to an eighth aspect of the present invention, in the configuration of the seventh aspect, the inlet-side exhaust conduit and the downstream-side exhaust conduit are such that a downstream exhaust conduit end at the connection portion is an inlet-side exhaust conduit end. The housing is slidably connected by housing the unit inside, and the outer peripheral portion of the downstream end of the exhaust pipe is supported on the sub-muffler outer cylinder side.

As described above, in the connection portion, the end of the exhaust pipe on the downstream side is outward, and the outer peripheral portion is supported on the sub-muffler outer cylinder side. Thus, the end of the exhaust pipe on the downstream side can be firmly supported by the sub-muffler outer cylinder, and at the same time, large vibration of the exhaust system during idling can be prevented, so that good riding comfort can be maintained.

According to a ninth aspect of the present invention, in the configuration of the seventh or eighth aspect, the inlet-side exhaust conduit and the downstream-side exhaust conduit are slidably connected to each other with a wire mesh therebetween at the connection portion. It is characterized by having.

By connecting the inlet side exhaust pipe and the downstream side exhaust pipe so as to be slidable by using the wire mesh at the connection part, vibration is transmitted to the downstream side exhaust pipe via the connection part. Can be prevented more reliably.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is an explanatory view of a vertical cross-sectional structure of a sub-muffler 2 to which the above-described invention is applied. FIG. 2 is a schematic explanatory view showing an arrangement of the sub-muffler 2 and other components in an exhaust system of an internal combustion engine (here, a gasoline engine; hereinafter, referred to as an “engine”) mounted on an automobile. In this exhaust system, two front pipes 8, 10, two catalytic converters 12, 14, two center pipes 16, 18, which are respectively connected to the two exhaust manifolds 4, 6 from the upstream side, these two center pipes 16, A main muffler 20, a tail pipe (corresponding to an exhaust pipe) 22, and a sub-muffler 2 are arranged to introduce the exhaust gas from 18. These components are fastened by the fastening portions 24, 26, 28, 30, 32.

Therefore, the exhaust of the engine discharged from each of the exhaust manifolds 4, 6 is purified by the three-way catalyst in the catalytic converters 12, 14, and
After passing through the main muffler 20 and the sub-muffler 2, the sound is silenced and discharged to the outside.

As shown in FIG. 1, the sub-muffler 2 is an inlet pipe (corresponding to an inlet-side exhaust pipe) forming a part of the sub-muffler outer cylinder 2a and the tail pipe 22.
22a, and an outlet pipe (corresponding to an exhaust pipe downstream of the inlet-side exhaust pipe) 22b forming a part of the tail pipe 22. The sub-muffler outer cylinder 2a has a shape in which both ends of a peripheral wall 34 of a cylinder or an elliptical cylinder are sealed by side walls 36 and 38. The inlet pipe 22a penetrates the upstream side wall 36, and the downstream end 40 is disposed inside the sub-muffler outer cylinder 2a. The outlet pipe 22b penetrates the downstream side wall 38, and has an upstream end 42 disposed inside the sub-muffler outer cylinder 2a. The inlet pipe 22a is connected to the upstream side wall 36 by arc welding.
A joining portion 36a is formed over the entire circumference of a. Further, a joint 38a is formed between the outlet pipe 22b and the downstream side wall 38 over the entire circumference of the outlet pipe 22b by arc welding.

The upstream end 4 of the outlet pipe 22b
Reference numeral 2 denotes a connecting portion which has an enlarged diameter and accommodates the downstream end portion 40 of the inlet pipe 22a to suppress the transmission of vibration.
4 are formed. In the connection portion 44, a wire mesh 46 is disposed between the outer peripheral surface of the downstream end 40 of the inlet pipe 22a and the inner peripheral surface of the upstream end 42 of the outlet pipe 22b. The wire mesh 46 is disposed on the entire outer peripheral surface of the downstream end portion 40 of the inlet pipe 22a and spot-welded. As a result, the inlet pipe 22a and the outlet pipe 22b are slidable in the axial direction against vibration and other distortions, and are relatively movable in the radial direction by bending of the wire mesh 46.

A reinforcing separator 48 is provided between the connecting portion 44 and the sub-muffler outer cylinder 2a. The reinforcing separator 48 is a plate-like member that divides the inside of the sub-muffler outer cylinder 2a into two parts. The connecting part 44 is disposed in a through hole formed in the center thereof, and an outlet is formed at a peripheral part 48a of the through hole. It is joined to the outer peripheral surface of the upstream end 42 of the pipe 22b by spot welding. The outer peripheral edge 48b of the reinforcing separator 48 is joined to the inner peripheral surface of the peripheral wall 34 of the sub-muffler outer cylinder 2a by spot welding. In FIG. 1, the reinforcing separator 48 has a schematic shape of only a cut surface. Other figures also show the schematic shape of only the cut surface of the reinforcing separator.

Therefore, the connecting portion 44 is supported by the sub-muffler outer cylinder 2a on the outlet pipe 22b side.
That is, the inlet pipe 22a is supported by the sub-muffler outer cylinder 2a via the wire mesh 46 and the outlet pipe 22b.

In the inside of the sub-muffler outer cylinder 2a, silencers 50 and 52 are formed in the inlet pipe 22a and the outlet pipe 22b, and a communication hole 48c is formed in the reinforcing separator 48. Communicates with the interior space.

FIG. 3 shows the measurement results of the vibration level in the tail pipe 22 in the above-described configuration. This measurement result indicates the engine speed (r
pm) with respect to the vibration level (dB). In FIG. 3, the solid line is the measurement result when the sub-muffler 2 having the configuration shown in FIGS. The broken line is shown as a comparative example. In this comparative example, FIG.
As shown in (A), the reinforcing separator 1048 directly supports not the outlet pipe 1022b but the inlet pipe 1022a in the connecting portion 1044.

As can be seen from the measurement results of FIG. 3, the vibration level in the comparative example shown by the broken line is very high in the idle region, but is sufficiently low in the first embodiment shown by the solid line. That is, in the configuration of the first embodiment, a difference between the vibration levels as shown by hatching in the drawing occurs between the configuration and the comparative example.

As a comparative example, as shown in FIG. 7B, when a sub-muffler of a type in which the inlet pipe and the outlet pipe are not divided is used, as in the case of FIG. The vibration level is very high in the region.

According to the first embodiment described above, the following effects can be obtained. (I). The inlet pipe 22a and the downstream outlet pipe 22b are connected by a connecting portion 44 for suppressing vibration transmission. Then, inside the sub muffler outer cylinder 2a, the sub muffler outer cylinder 2
The outlet pipe 22b is supported on the side a. Substantial support for the inlet pipe 22a is provided via the connection portion 44 and the outlet pipe 22b. Although the inlet pipe 22a is joined to the upstream side wall 36 at the joint 36a,
With such joining alone, vibration is not rigid, and there is no sufficient support effect against vibration due to the bending of the upstream side wall 36.

Therefore, the vibration system having the main muffler 20 as a node is up to the inlet pipe 22a, and does not include the outlet pipe 22b, the sub-muffler outer cylinder 2a, and the downstream side. Therefore, the mass of the vibration system is reduced, and the mass m can be reduced in the equation [f = (1 / 2π) √ (k / m)] of the resonance vibration frequency f represented by the mass m and the spring constant k. . From this, the resonance vibration frequency f is in the idling rotation range (FIG. 3: 600 to 700r).
pm). Therefore, large vibrations of the exhaust system at the time of idling can be prevented, and good riding comfort can be maintained.

(B). The connecting portion 44 connects the inlet pipe 22a and the outlet pipe 22b so as to be slidable and relatively movable in the radial direction using a wire mesh 46 therebetween. Thus, transmission of vibration to the outlet pipe 22b through the connection portion 44 can be more reliably prevented.

(C). The support on the outlet pipe 22b side is directly provided at the connection portion 44 by the reinforcing separator 48.
At the downstream side wall 38.
Together with 8a, the sub-muffler outer cylinder 2a can sufficiently support the outlet pipe 22b. In addition, the support of the outlet pipe 22b does not require any special support member, and uses the reinforcing separator 48 that reinforces the sub-muffler outer cylinder 2a. Therefore, the weight of the sub-muffler 2 does not increase.

(D). Since the connecting portion 44 is slidable in the axial direction and relatively movable in the radial direction by using the wire mesh 46, the thermal stress can be absorbed by the sub-muffler 2, thereby improving the durability reliability.

[Other Embodiments] In the first embodiment, the upstream end 42 of the outlet pipe 22b whose diameter has been expanded as shown in FIG.
Was joined to a reinforcing separator 48. Fig. 4
As shown in (A), the diameter of the downstream end 140 of the inlet pipe 122a is expanded, and
When the upstream end 142 of the outlet pipe 2b is housed inside, the outlet pipe 12
A reinforcement separator 148 may be joined to 2b to support the outlet pipe 122b.

Also, instead of supporting the outlet pipes 22b and 122b on the upstream side of the sub-muffler outer cylinders 2a and 102a as shown in FIG. 1 or FIG.
As shown in (B), the outlet pipe 222b may be supported by the reinforcing separator 248 at the center of the sub-muffler outer cylinder 202a.

Also, as shown in FIGS. 5A and 5B, connecting portions 344 and 444 are provided downstream of the sub-muffler outer cylinders 302a and 402a, and at or near the connecting portion 444. At the outlet pipe 322
b, 422b may be supported by the reinforcing separators 348, 448.

As shown in FIGS. 6A and 6B, the connecting portions 544 and 644 are connected to the sub-muffler outer cylinder 502a,
The outlet pipe 52 is provided at a center portion of the outlet pipe 602a at or near the connection portion 644.
2b and 622b may be supported by the reinforcing separators 548 and 648.

The support by the reinforcing separator is on the outlet pipe side. However, if a slide mechanism such as each of the above-described connecting parts is interposed between the reinforcing separator and the inlet pipe, or the reinforcing separator is used. If it is interposed between the sub-muffler outer cylinder and the sub-muffler outer cylinder, the inlet pipe side may be supported on the sub-muffler outer cylinder side by a reinforcing separator.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional configuration explanatory view of a sub-muffler according to a first embodiment.

FIG. 2 is a schematic explanatory view showing an arrangement of a sub-muffler and other components in an exhaust system of the engine according to the first embodiment.

FIG. 3 is a graph showing measurement results of a vibration level of the first embodiment and a comparative example.

FIG. 4 is a longitudinal sectional configuration explanatory view showing another example.

FIG. 5 is a vertical cross-sectional configuration explanatory view showing another example.

FIG. 6 is a longitudinal sectional configuration explanatory view showing another example.

FIG. 7 is a longitudinal sectional configuration explanatory view showing a comparative example.

FIG. 8 is an explanatory diagram showing a vibration mode of an exhaust system.

[Explanation of symbols]

2 ... Sub muffler, 2a ... Sub muffler outer cylinder, 4,6 ... Each exhaust manifold, 8,10 ... Front pipe,
12, 14: catalytic converter, 16, 18: center pipe, 20: main muffler, 22: tail pipe, 2
2a ... inlet pipe, 22b ... outlet pipe, 24, 26, 28, 30, 32 ... fastening part, 34 ... peripheral wall, 36, 38 ... side wall, 36a, 38a ... joining part, 40
... downstream end, 42 ... upstream end, 44 ... connection, 46
... wire mesh, 48 ... separator for reinforcement, 48a
... peripheral part, 48b ... outer peripheral part, 48c ... communication hole, 50,
52: silencer hole, 122a: inlet pipe, 122b
... outlet pipe, 140 ... downstream end, 142 ...
Upstream end, 144 connection part, 148 reinforcement separator, 202a sub-muffler outer cylinder, 222b outlet pipe, 248 reinforcement separator, 302a, 40
2a: Sub-muffler outer cylinder, 322b, 422b: Outlet pipe, 344, 444: Connection, 348, 448
... Reinforcing separator, 502a, 602a ... Sub-muffler outer cylinder, 522b, 622b ... Outlet pipe, 54
4,644 ... connection part, 548,648 ... reinforcement separator.

Claims (9)

[Claims] 1. A sub-muffler provided downstream of a main muffler in an exhaust system of an internal combustion engine, wherein an exhaust conduit inside a sub-muffler outer cylinder includes an inlet-side exhaust conduit and an exhaust conduit downstream of the inlet-side exhaust conduit. The sub-muffler is characterized in that the inlet-side exhaust conduit is not connected to any other components inside the sub-muffler outer cylinder except through a connection for suppressing vibration transmission. 2. The structure according to claim 1, wherein the inlet-side exhaust conduit and the downstream-side exhaust conduit are connected at the connection portion inside the sub-muffler outer cylinder, and the inlet-side exhaust conduit is connected to the sub-muffler outer cylinder. The sub-muffler is characterized in that the sub-muffler is not connected to any other components except for the connection portion. 3. The sub-muffler according to claim 2, wherein the connection portion is configured such that an inlet-side exhaust conduit and a downstream-side exhaust conduit are relatively movable. 4. The sub-muffler according to claim 2, wherein a downstream exhaust pipe is supported by the sub-muffler outer cylinder inside the sub-muffler outer cylinder. 5. The sub-muffler according to claim 4, wherein the exhaust pipe on the downstream side is supported by the sub-muffler outer cylinder at or near the connection. 6. The exhaust pipe on the downstream side according to claim 4 or 5, wherein the exhaust pipe on the downstream side is supported by being connected to the sub-muffler outer cylinder via a separator that partitions the inside of the sub-muffler outer cylinder into a plurality of sections. A sub-muffler characterized by the following. 7. The exhaust pipe according to claim 4, wherein the exhaust pipe on the inlet side and the exhaust pipe on the downstream side are one of the exhaust pipe on the inlet side and the exhaust pipe on the downstream side at the connection portion. The sub-muffler is slidably connected such that the other is housed inside. 8. An exhaust pipe according to claim 7, wherein the end of the exhaust pipe on the inlet side and the end of the exhaust pipe on the downstream side at the connection portion accommodate the end of the exhaust pipe on the inlet side. A sub-muffler, wherein the sub-muffler is connected so as to be slidable, and the outer peripheral portion of the downstream end of the exhaust pipe is supported by the sub-muffler outer cylinder. 9. The structure according to claim 7, wherein the inlet-side exhaust conduit and the downstream-side exhaust conduit are slidably connected with a wire mesh therebetween at the connection portion. Sub muffler to do.