JP3508664B2 - Sub muffler - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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 in an automobile or the like, a structure in which a main muffler and a sub muffler are combined is known. This sub-muffler is attached for the purpose of eliminating insufficient muffling of the main muffler when the exhaust system is long.

For example, FIG. 8 shows a typical passenger car.
As shown by the solid line in (A), a sub muffler is attached on the upstream side of the main muffler. In such a structure, the vibration generated from the internal combustion engine becomes a vibration mode as shown 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 or the like, 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 the vibration mode as shown by the broken line in the figure.
In other words, since the main muffler vibrates as a node,
Compared to the case of (A), when the sub muffler is located downstream of the main muffler, the length of the tail pipe on the downstream side of the main muffler is longer and the sub muffler is arranged at the end of the tail pipe. As a result, the resonance frequency changes to the low frequency side and its amplitude tends to increase.

Therefore, there is a possibility that the sub-muffler resonates with a relatively large amplitude in the idle rotation range as compared with the case where the sub-muffler is located upstream of the main muffler. When such vibration occurs, the muffled sound at the time of idling or the vibration of the floor or the steering becomes large, which may deteriorate the riding comfort.

It is an object of the present invention to provide a sub-muffler that can maintain good ride comfort by reducing vibration of the exhaust system during idling even if the sub-muffler is provided downstream of the main muffler.

[0007]

[Means for Solving the Problems] Means for attaining the above-mentioned objects and their effects 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 comprises an inlet-side exhaust conduit and an exhaust conduit downstream of the inlet-side exhaust conduit, and the inlet-side exhaust conduit is provided inside the sub-muffler outer cylinder except through a connecting portion that suppresses vibration transmission. It is characterized in that it is not connected to other configurations.

In the sub-muffler provided downstream of the main muffler, inside the sub-muffler outer cylinder, the inlet-side exhaust conduit is not connected to other components except through a connecting portion for suppressing vibration transmission. Examples of such a connection part include a connection part, such as a floating structure, in which the inlet side exhaust conduit and the downstream side exhaust conduit are relatively movable, that is, a non-rigid connecting part.
Therefore, the vibration system having the main muffler as a node extends to the inlet side exhaust pipe, and does not include the downstream side exhaust pipe, the sub-muffler outer cylinder, and the downstream thereof. Therefore,
The mass of the vibration system is reduced, and the resonance frequency does not fall to the idle rotation range. Therefore, it is possible to prevent a large vibration of the exhaust system during idling and maintain a good riding comfort.

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

In this way, the connecting portion for suppressing the vibration transmission is
It may be provided between the inlet-side exhaust conduit and the downstream-side exhaust conduit, and the inlet-side exhaust conduit may not be connected to any other structure inside the sub-muffler outer cylinder except for the connecting portion.

With this structure, 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 way, large vibrations of the exhaust system at the time of idling can be prevented, and the ride comfort can be maintained well.

According to a third aspect of the present invention, in the sub-muffler according to the second aspect, the connecting portion is configured such that an inlet side exhaust pipe and a downstream side exhaust pipe are relatively movable. .

With such a structure, it is possible to realize a connecting portion for suppressing vibration transmission, prevent a large vibration of the exhaust system during idling, and maintain a good ride comfort.

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

Thus, for the exhaust pipe on the downstream side,
It may be supported on the sub-muffler outer cylinder side. Even if this support is not made 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 pipe. In this way, large vibrations of the exhaust system at the time of idling can be prevented, and the ride comfort can be maintained well.

A sub-muffler according to a fifth aspect of the present invention is characterized in that, in the structure according to the fourth aspect, the exhaust pipe on the downstream side is supported on the sub-muffler outer cylinder side near the connecting portion or the connecting portion. .

As described above, by supporting the exhaust pipe on the downstream side on the sub-muffler outer cylinder side at the connection portion or in the vicinity of this connection portion, 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 sub-muffler of the fourth or fifth aspect, the exhaust pipe on the downstream side is
The sub-muffler outer cylinder is supported by being connected to the sub-muffler outer cylinder side via a separator that divides the inside of the sub-muffler outer cylinder into a plurality of sections.

For supporting the exhaust pipe side on the downstream side, a separator which reinforces the sub-muffler outer cylinder can be used without providing a special supporting member. Therefore, the weight of the sub muffler is not increased.

The submuffler according to claim 7 is the submuffler according to any one of claims 4 to 4.
In the configuration according to any one of 6 above, the inlet side exhaust conduit and the downstream side exhaust conduit are configured such that one of the inlet side exhaust conduit and the downstream side exhaust conduit accommodates the other inside thereof at the connecting portion. It is characterized in that it is slidably connected.

Even with a simple slide mechanism in which one of the inlet-side exhaust pipe and the downstream-side exhaust pipe is housed in the other, the vibration system having the main muffler as a node It can be up to the inlet side exhaust conduit. Therefore, it is possible to prevent a large vibration of the exhaust system during idling and maintain a good riding comfort.

In the sub-muffler according to claim 8, in the structure according to claim 7, the inlet side exhaust conduit and the downstream side exhaust conduit have a downstream side exhaust conduit end at an inlet side inlet side exhaust conduit end. It is characterized in that it is slidably connected by accommodating the parts inside, and that the outer peripheral part of the end part of the exhaust conduit on the downstream side is supported on the sub-muffler outer cylinder side.

As described above, in the connecting portion, the end of the exhaust pipe on the downstream side is placed outside, and the outer peripheral portion supports the sub-muffler on the outer cylinder side. As a result, the end of the exhaust pipe on the downstream side can be firmly supported by the sub-muffler outer cylinder, large vibration of the exhaust system at the time of idling can be prevented, and good riding comfort can be maintained.

According to a ninth aspect of the submuffler of the seventh aspect or the eighth aspect, the inlet side exhaust conduit and the downstream side exhaust conduit are slidably connected at the connecting portion with a wire mesh therebetween. It is characterized by

Thus, by connecting the inlet side exhaust conduit and the downstream side exhaust conduit slidably by using the wire mesh between the connecting parts, vibration is transmitted to the downstream side exhaust conduit through the connecting part. Can be prevented more reliably.

[0026]

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

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

As shown in FIG. 1, the sub-muffler 2 is an inlet pipe (corresponding to an inlet side exhaust pipe) which forms a part of the sub-muffler outer cylinder 2a and the tail pipe 22.
22a, and an outlet pipe (corresponding to an exhaust pipe on the downstream side 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 elliptic cylinder are sealed by side walls 36 and 38. Further, the inlet pipe 22a penetrates through the upstream side wall 36 and has its downstream end 40 arranged inside the sub-muffler outer cylinder 2a. The outlet pipe 22b penetrates the downstream side wall 38 and has its upstream end 42 arranged inside the sub-muffler outer cylinder 2a. The inlet pipe 22a and the upstream side wall 36 are arc-welded to each other by arc welding.
A joint portion 36a is formed over the entire circumference of a. Further, the outlet pipe 22b and the downstream side wall 38 are joined by arc welding to form a joint 38a over the entire circumference of the outlet pipe 22b.

The upstream end 4 of the outlet pipe 22b
2 has an enlarged diameter, and the connecting portion 4 that suppresses vibration transmission by accommodating the downstream end 40 of the inlet pipe 22a.
4 is forming. In the connecting portion 44, a wire mesh 46 is arranged 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 arranged on the entire outer peripheral surface of the downstream end 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 vibrations and other strains, and are also relatively movable in the radial direction by the 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-shaped member that divides the inside of the sub-muffler outer cylinder 2a into two parts. The connecting portion 44 is arranged in the through hole formed in the center of the sub muffler outer cylinder 2a, and the outlet is provided at the peripheral portion 48a of the through hole. It is joined by spot welding to the outer peripheral surface of the upstream end 42 of the pipe 22b. Then, the outer peripheral edge portion 48b of the reinforcing separator 48 is spot welded to the inner peripheral surface of the peripheral wall 34 of the sub muffler outer cylinder 2a. Note that, in FIG. 1, the reinforcing separator 48 shows a schematic shape of only a cut surface. In other figures, the reinforcing separator also shows a schematic shape of only the cut surface.

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 on the sub-muffler outer cylinder 2a side via the wire mesh 46 and the outlet pipe 22b.

Inside the sub-muffler outer cylinder 2a, muffler holes 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, so that the sub-muffler outer cylinder 2a is formed. Communicates with the interior space of.

FIG. 3 shows the measurement result of the vibration level of the tail pipe 22 having the above-mentioned structure. The result of this measurement is the engine speed (r
Vibration level (dB) with respect to pm) is measured. The solid line in FIG. 3 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 side but the inlet pipe 1022a side in the connection portion 1044.

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

As a comparative example, as shown in FIG. 7 (B), even when a sub muffler of a type in which the inlet pipe and the outlet pipe are not divided is used, it is idle as in the case of FIG. 7 (A). The vibration level is very high in the area.

According to the first embodiment described above, the following effects can be obtained. (I). The inlet pipe 22a and the outlet pipe 22b on the downstream side are connected by a connecting portion 44 that suppresses vibration transmission. Then, inside the sub-muffler outer cylinder 2a, the sub-muffler outer cylinder 2 is interposed via the reinforcing separator 48.
The outlet pipe 22b is supported on the a side. Substantial support for the inlet pipe 22a is provided via the connecting portion 44 and the outlet pipe 22b. Although the inlet pipe 22a is joined to the upstream side wall 36 at the joint portion 36a,
With such joining alone, the upstream side wall 36 is not rigid and is not sufficiently rigid to support vibrations due to the bending of the upstream side wall 36.

Therefore, the vibration system having the main muffler 20 as a node extends up to the inlet pipe 22a, and does not include the outlet pipe 22b, the sub-muffler outer cylinder 2a, and the downstream thereof. Therefore, the mass of the vibration system becomes small, and the mass m can be made small in the formula [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 idle rotation range (FIG. 3: 600 to 700 r).
pm). Therefore, it is possible to prevent a large vibration of the exhaust system during idling, and it is possible to maintain good riding comfort.

(B). The connecting portion 44 connects the inlet pipe 22a and the outlet pipe 22b slidably using the wire mesh 46 and relatively movable in the radial direction. As a result, it is possible to more reliably prevent the vibration from being transmitted to the outlet pipe 22b via the connecting portion 44.

(C). The support on the outlet pipe 22b side is provided directly at the connecting portion 44 at the reinforcing separator 48.
Since it is supported by the joint part 3 on the downstream side wall 38,
Together with 8a, the sub-muffler outer cylinder 2a can sufficiently firmly support the outlet pipe 22b. Further, since the outlet pipe 22b is supported by using the reinforcing separator 48 that reinforces the sub-muffler outer cylinder 2a without providing a special supporting member, the weight of the sub-muffler 2 is not increased.

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

[Other Embodiments] In the first embodiment, the upstream end 42 of the outlet pipe 22b, which has been expanded in diameter as shown in FIG.
The reinforcing separator 48 was joined to the. In addition to this,
As shown in (A), the diameter of the downstream end portion 140 of the inlet pipe 122a is increased so that the outlet pipe 12
In the case where the upstream end 142 of 2b is housed inside, the outlet pipe 12 is provided near the connecting portion 144.
A reinforcing separator 148 may be joined to 2b to support the outlet pipe 122b.

Also, the outlet pipes 22b and 122b are not supported 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.

As shown in FIGS. 5A and 5B, connecting portions 344 and 444 are provided on the downstream side of the sub-muffler outer cylinders 302a and 402a, and at or near the connecting portion 344. At the outlet pipe 322
b and 422b may be supported by the reinforcing separators 348 and 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 the central portion of the 602a, and at the connecting portion 544 or in the vicinity of the connecting portion 644.
2b and 622b may be supported by the reinforcing separators 548 and 648.

The support by the reinforcing separator was on the outlet pipe side. However, if a sliding mechanism such as the above-mentioned connecting portions is interposed between the reinforcing separator and the inlet pipe, or the reinforcing separator is used. And the sub muffler outer cylinder, the inlet pipe side may be supported by the reinforcing separator on the sub muffler outer cylinder side.

[Brief description of drawings]

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

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

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

FIG. 4 is a vertical cross-sectional configuration explanatory view showing another example.

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

FIG. 6 is a vertical cross-sectional configuration explanatory view showing another example.

FIG. 7 is a vertical cross-sectional configuration explanatory view showing a comparative example.

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

[Explanation of symbols]

2 ... Sub muffler, 2a ... Sub muffler outer cylinder, 4, 6 ... Exhaust manifolds, 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 portion, 42 ... Upstream end portion, 44 ... Connection portion, 46
… Wire mesh, 48… Reinforcing separator, 48a
... peripheral portion, 48b ... outer peripheral portion, 48c ... communication hole, 50,
52 ... Silencer hole, 122a ... Inlet pipe, 122b
... Outlet pipe, 140 ... Downstream end, 142 ...
Upstream end portion, 144 ... Connection portion, 148 ... Reinforcing separator, 202a ... Sub muffler outer cylinder, 222b ... Outlet pipe, 248 ... Reinforcing separator, 302a, 40a
2a ... Sub muffler outer cylinder, 322b, 422b ... Outlet pipe, 344, 444 ... Connection part, 348, 448
... Reinforcing separator, 502a, 602a ... Sub-muffler outer cylinder, 522b, 622b ... Outlet pipe, 54
4,644 ... Connection part, 548,648 ... Reinforcing separator.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01N 1/08 F01N 7/02 F01N 7/08

Claims (9)

(57) [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 the sub-muffler outer cylinder comprises an inlet-side exhaust conduit and an exhaust conduit downstream from the inlet-side exhaust conduit. The sub-muffler is characterized in that the inlet-side exhaust pipe is not connected to any other structure inside the sub-muffler outer cylinder except through a connecting portion that suppresses vibration transmission. 2. The structure according to claim 1, wherein the exhaust pipe on the inlet side and the exhaust pipe on the downstream side are connected at the connecting portion inside the outer pipe of the sub muffler, and the exhaust pipe on the inlet side is inside the outer pipe of the sub muffler. Then, the sub-muffler is characterized in that it is not connected to any other structure other than the connection portion. 3. The sub-muffler according to claim 2, wherein the connecting portion has a structure in which an inlet side exhaust pipe and a downstream side exhaust pipe are relatively movable. 4. The sub-muffler according to claim 2 or 3, wherein the exhaust pipe on the downstream side is supported by the sub-muffler outer cylinder side inside the sub-muffler outer cylinder. 5. The sub-muffler according to claim 4, wherein the exhaust pipe on the downstream side is supported on the sub-muffler outer cylinder side at the connection portion or in the vicinity of the connection portion. 6. The structure 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 side via a separator that divides the interior of the sub-muffler outer cylinder into a plurality of sections. A sub muffler characterized by that. 7. The structure according to any one of claims 4 to 6, wherein one of the inlet side exhaust conduit and the downstream side exhaust conduit is one of the inlet side exhaust conduit and the downstream side exhaust conduit at the connecting portion. The sub-muffler is characterized in that the other is slidably connected so as to accommodate the other inside. 8. The structure according to claim 7, wherein the exhaust pipe on the inlet side and the exhaust pipe on the downstream side have the exhaust pipe end on the downstream side accommodates the exhaust pipe end on the inlet side in the connecting portion. Thus, the sub-muffler is slidably connected, and the outer peripheral portion of the downstream end of the exhaust conduit is supported by the sub-muffler outer cylinder side. 9. The structure according to claim 7, wherein the exhaust pipe on the inlet side and the exhaust pipe on the downstream side are slidably connected to each other through the wire mesh at the connecting portion. Sub muffler to do.