MUFFLER

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Japanese Patent Application No. 2024-186566 filed on October 23, 2024 with the Japan Patent Office, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a muffler.

As disclosed in Japanese Unexamined Patent Application Publication No. H10-205324, a muffler including a diffuser pipe and a catalyst tube arranged inside the diffuser pipe is known. The muffler includes a plate-shaped stay joined to an outer-circumferential surface of the catalyst tube and to an inner-circumferential surface of the diffuser pipe, and the catalyst tube is fixed to the diffuser pipe by the stay.

SUMMARY

However, in the muffler disclosed in Japanese Unexamined Patent Application Publication No. H10-205324, in a case in which an end of the catalyst tube is joined to a component such as a diffuser pipe, if thermal elongation occurs in the catalyst tube, stress may concentrate on the stay, leading to damage to the stay or its nearby area.

It is desirable that one aspect of the present disclosure reduces influence of thermal elongation.

One aspect of the present disclosure is a muffler to be installed in a vehicle, and the muffler comprises a shell member, an opening end portion, an inner pipe, and at least one stay. The shell member includes therein a flow path for exhaust gas from an engine. The opening end portion surrounds an opening to allow an inside and an outside of the shell member to communicate with each other. The inner pipe is joined to the opening end portion and arranged to extend from the opening to the inside of the shell member. The at least one stay is a plate-shaped elongated member extending in a longitudinal direction of the at least one stay and including a first surface and a second surface opposite to each other in a thickness direction thereof. In addition, the at least one stay includes a first joint portion, a second joint portion, and a body portion. The first joint portion is provided at a first end of the at least one stay in the longitudinal direction and joined to an outer-circumferential surface of the inner pipe. The second joint portion is provided at a second end of the at least one stay in the longitudinal direction and joined to an inner-circumferential surface of the shell member. The body portion is provided between the first joint portion and the second joint portion, and extends in the longitudinal direction. The at least one stay is arranged such that the longitudinal direction of the at least one stay is inclined with respect to an extending direction of the inner pipe. The second joint portion is located closer to the opening than the first joint portion is. The at least one stay is arranged such that the first surface faces the outer-circumferential surface of the inner pipe.

In the above-described configuration, since the first surface of the at least one stay faces the outer-circumferential surface of the inner pipe, the at least one stay can deform in accordance with thermal elongation of the inner pipe. In addition, since the longitudinal direction of the at least one stay is inclined with respect to the extending direction of the inner pipe, the at least one stay can be made longer, thereby reducing a difference in length of the thermal elongation between the inner pipe and the at least one stay. Accordingly, it is possible to inhibit occurrence of damage to the at least one stay due to the thermal elongation, thereby reducing the influence of the thermal elongation.

In one aspect of the present disclosure, the shell member may be a pipe-shaped member extending in the extending direction of the inner pipe, and include, at respective opposite ends thereof, a first opening and a second opening. The inner pipe may be joined to the opening end portion surrounding the first opening of the shell member. The second joint portion may be located closer to the first opening than the first joint portion is.

The above-described configuration makes it possible to reduce the influence of the thermal elongation.

In one aspect of the present disclosure, the body portion may extend in a substantially planar manner.

The above-described configuration allows the at least one stay to deform appropriately in accordance with the thermal elongation of the inner pipe.

In one aspect of the present disclosure, the body portion may include a protrusion.

The above-described configuration makes it possible to improve rigidity of the at least one stay.

In one aspect of the present disclosure, the at least one stay may further include a perpendicular portion that is located between the body portion and the first joint portion and that extends in a substantially planar manner in a direction substantially perpendicular to the extending direction of a part of the inner pipe joined to the opening end portion.

The above-described configuration makes it possible to press the at least one stay effectively by a jig in a process of manufacturing the muffler.

In one aspect of the present disclosure, a part of the inner pipe including an end located in a space inside the shell member may be formed as an inclined part inclined downward toward the end.

The above-described configuration makes it possible to effectively discharge the condensed water accumulated inside the inner pipe.

In one aspect of the present disclosure, the second joint portion may be joined to the shell member at a location where an antinode of resonance is generated in the shell member.

The above-described configuration makes it possible to effectively inhibit vibrations of the shell member due to resonance.

In one aspect of the present disclosure, the at least one stay may comprise two or more stays.

The above-described configuration makes it possible to reduce an influence of the thermal elongation.

In one aspect of the present disclosure, respective second joint portions of the two or more stays may be provided at different locations in a circumferential direction around the inner pipe.

The above-described configuration makes it possible to reduce the influence of the thermal elongation.

BRIEF DESCRIPTION OF THE DRAWINGS

An example embodiment of the present disclosure will be described hereinafter with reference to the accompanying drawings, in which:

FIG. 1A is a side view showing an internal structure of a shell member of a muffler of a first embodiment in a transparent manner;

FIG. 1B is a perspective view of a stay of the first embodiment;

FIG. 1C is an explanatory diagram of the shell member of the first embodiment, in which resonance occurs;

FIG. 2 is a diagram for explaining that the inner pipe to which stays are joined is pressed into the shell member, in a process of manufacturing the muffler of the first embodiment;

FIG. 3A is a diagram for explaining that an inner pipe to which a stay is joined is pressed into a shell member, in a process of manufacturing a muffler of a second embodiment; and

FIG. 3B is a side view showing an internal structure of a shell member of a muffler of a third embodiment in a transparent manner.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[1. First Embodiment]

(1) Overview

A muffler 1 of a first embodiment is configured to be installed in a vehicle and cause an exhaust gas from an engine of the vehicle to flow downward (see FIG. 1A). As an example, the muffler 1 may be formed as a small-sized sub-muffler. The muffler 1 has a double-pipe structure extending along an axis A, which is a virtual straight line, and comprises a shell member 2 corresponding to an outer tube, an inner pipe 3 corresponding to an inner tube, and a stay 4.

(2) Shell Member

The shell member 2 is a cylindrical member extending straight along the axis A and includes therein a flow path for the exhaust gas (see FIG. 1A), as an example. A cross section of the shell member 2 perpendicular to the axis A (hereafter, simply referred to as a “cross section”) is circular, as an example, and the axis A passes through the center of the cross section of the shell member 2, as an example. The shell member 2 comprises a first opening 20, a second opening 21, a first opening end portion 20A, a second opening end portion 21A, a first tapered portion 22, a second tapered portion 23, and a middle portion 24.

First and Second Openings

The first and second openings 20 and 21 are circular openings located at a first end and a second end of the shell member 2, respectively. As an example, the first opening 20 is formed as an exhaust gas inlet of the muffler 1, and the second opening 21 is formed as an exhaust gas outlet of the muffler 1. However, the present disclosure is not limited thereto. The second opening 21 may be formed as the exhaust gas inlet of the muffler 1, and the first opening 20 may be formed as the exhaust gas outlet of the muffler 1.

First and Second Opening End Portions

The first and second opening end portions 20A and 21A are cylindrical portions surrounding the first and second openings 20 and 21, respectively.

First and Second Tapered Portions

The first and second tapered portions 22 and 23 are respectively provided adjacent to the first and second opening end portions 20A and 21A. Each of the first and second tapered portions 22 and 23 has a shape inclined with respect to the axis A in a side view, and a cross section of each of the first and second tapered portions 22 and 23 is larger toward the center of the shell member 2 along the axis A.

Middle Portion

The middle portion 24 is a cylindrical portion extending along the axis A. The first and second tapered portions 22 and 23 are located at respective ends of the middle portion 24.

(3) Inner Pipe

The inner pipe 3 is a cylindrical member extending straight along the axis A (see FIG. 1A), as an example. The axis A passes through the center of a cross section of the inner pipe 3.

A first end of the inner pipe 3 is inserted into the first opening end portion 20A, and a portion of an outer-circumferential surface 32 of the inner pipe 3 located near the first end is joined (e.g., welded) to the first opening end portion 20A. The inner pipe 3 extends from the first opening end portion 20A to an inside of the shell member 2 along the axis A.

Specifically, a first opening 30 located at the first end of the inner pipe 3 is arranged to overlap with the first opening 20 of the shell member 2, and a second opening 31 located at a second end of the inner pipe 3 is arranged in a space inside the shell member 2. As a result, the exhaust gas entering the muffler 1 from the first opening 20 first passes through the inner pipe 3 and then flows into a space between the inner pipe 3 and the shell member 2. Finally, the exhaust gas flows out of the muffler 1 from the second opening 21.

(4) Stay

The stay 4 is provided to support the inner pipe 3 and is a plate-shaped elongated member extending along a longitudinal direction L. The stay 4 includes a first surface 45 and a second surface 46 opposite to each other in a thickness direction of the stay 4 (see FIGS. 1A and 1B). The stay 4 comprises a body portion 40, a first joint portion 41, and a second joint portion 42.

Body Portion

The body portion 40 is a plate-shaped elongated portion extending along the longitudinal direction L. As an example, the body portion 40 has a substantially planar shape and a substantially rectangular shape extending in the longitudinal direction L. However, the present disclosure is not limited thereto, and the shape of the body portion 40 may be appropriately determined. Specifically, for example, the body portion 40 may have a bent shape or a curved shape, or may be bent or curved at two or more locations arranged along the longitudinal direction L.

The body portion 40 includes a protrusion 43 protruding toward a second surface 46 side. The protrusion 43 is located substantially in the center of the body portion 40 in a width direction thereof and extends along the longitudinal direction L, as an example. The position and/or the shape of the protrusion 43 are not limited thereto and may be appropriately determined, and the body portion 40 may include two or more protrusions.

Between the protrusion 43 of the body portion 40 and the second joint portion 42, a positioning hole 44 passing through the body portion 40 is provided. The positioning hole 44 is used to position the stay 4 when the stay 4 is joined to the inner pipe 3 in a process of manufacturing the muffler 1, as an example.

First and Second Joint Portions

The first and second joint portions 41 and 42 are plate-shaped portions respectively provided at first and second ends of the stay 4 in the longitudinal direction L. In other words, the first and second joint portions 41 and 42 are adjacent to respective ends of the body portion 40 opposite to each other in the longitudinal direction L. The first and second joint portions 41 and 42 are substantially rectangular, as an example. The first and second joint portions 41 and 42 extend from the respective ends of the body portion 40 in the longitudinal direction L. An angle d1 and an angle d2, which are respectively formed between the first joint portion 41 and the body portion 40 and between the second joint portion 42 and the body portion 40, are obtuse. The first and second joint portions 41 and 42 are respectively joined (e.g., welded) to the outer-circumferential surface 32 of the inner pipe 3 and to an inner-circumferential surface 25 of the shell member 2.

Inclination of Stay

The longitudinal direction L of the stay 4 and the body portion 40 is inclined with respect to the axis A, in other words, with respect to an extending direction of the inner pipe 3 and the shell member 2. Specifically, the second joint portion 42 is located closer to the first opening 30 of the inner pipe 3 with respect to the body portion 40, and the first joint portion 41 is located closer to the second opening 21 with respect to the body portion 40. The second joint portion 42 is located closer to the first opening 30 than the first joint portion 41 is.

First and Second Surfaces

The first and second surfaces 45 and 46 of the stay 4 respectively face the outer-circumferential surface 32 of the inner pipe 3 and the inner-circumferential surface 25 of the shell member 2. As an example, the stay 4 extends along the axis A when the stay 4 is viewed in the thickness direction. However, the present disclosure is not limited thereto, and the stay 4 may extend in a direction inclined with respect to the axis A when the stay 4 is viewed in the thickness direction.

(5) Position of Stay

A position of the stay 4 may be appropriately determined. Specifically, for example, the stay 4 may be provided closer to the first opening 20 with respect to the center of the inner pipe 3 along the axis A. This makes it possible to reduce stress to be applied to the stay 4 when thermal elongation occurs in the inner pipe 3, thereby inhibiting an influence of the thermal elongation more efficiently, compared with a case in which the stay 4 is provided closer to the second opening 21 with respect to the center.

Alternatively, for example, the stay 4 may be provided closer to the second opening 21 than the above-described center of the inner pipe 3. This makes it possible to inhibit resonance in the inner pipe 3, compared with in a case in which the stay 4 is provided closer to the first opening 20 than the center.

In another example, the position of each of the first and second joint portions 41 and 42 of the stay 4 may be determined so as to inhibit vibrations in the inner pipe 3 or the shell member 2.

Specifically, as shown in FIG. 1C, the second joint portion 42 of the stay 4 may be provided at any of positions, for example, where antinodes 24A, 24B, and 24C of resonance of first, second, and third modes are generated in the middle portion 24 of the shell member 2. The second joint portions 42 of the two or more stays 4 may be provided at the positions of the antinodes 24A to 24C of the resonance of the first to third modes. In still another example, the first joint portions 41 of the stays 4 may be provided at positions, for example, where antinodes of resonance are generated in the inner pipe 3.

(6) Number of Stay

In FIG. 1A, as an example, the stay 4, which is one in number, is provided in the muffler 1, but the number of stays 4 may be appropriately determined. In a case in which the two or more stays 4 are provided in the muffler 1, the stays 4 may be provided at different positions about the axis A in a circumferential direction (i.e., around the inner pipe 3), as shown in FIG. 2. In other words, the stays 4 may be arranged not to overlap with each other when the inner pipe 3 is viewed along the axis A.

Here, the process of manufacturing the muffler 1 includes steps (1) through (5) described below, as an example.

(1) The first joint portions 41 of the stays 4 are welded to the inner pipe 3.

(2) An intermediate shell member 2A is formed such that the first opening end portion 20A and the first tapered portion 22 are formed at a first end of the intermediate shell member 2A, and such that an opening 26, instead of the second opening end portion 21A and the second tapered portion 23, is formed at a second end of the intermediate shell member 2A.

(3) The inner pipe 3 to which the stays 4 are welded is pressed into an inside of the intermediate shell member 2A from the opening 26.

(4) The portion of the inner pipe 3 near the first end thereof and the first opening end portion 20A of the intermediate shell member 2A are welded, and the second joint portions 42 of the stays 4 and the middle portion 24 of the shell member 2 are welded.

(5) At the second end of the intermediate shell member 2A, the second opening end portion 21A and the second tapered portion 23 are formed.

In step (3), in a state in which the second joint portions 42 of the stays 4 welded to the inner pipe 3 are in contact with the inner-circumferential surface 25 of the shell member 2, the inner pipe 3 is pressed into the shell member 2. At this time, in order to inhibit the stays 4 from being damaged, it is desirable to press the inner pipe 3 into the shell member 2 by pressing the end portion surrounding the second opening 31 of the inner pipe 3 and the stays 4 using a pressing jig.

In this regard, by providing the stays 4 at the different positions in the circumferential direction, it is possible to press all the stays 4 using the pressing jig. As a result, pressing in step (3) can be performed efficiently.

[2. Second Embodiment]

The muffler 1 of a second embodiment is different from that of the first embodiment, in terms of the configuration of the stay 4. The muffler 1 of the second embodiment will be described below focusing on differences from that of the first embodiment.

Specifically, in the second embodiment, the stay 4 further comprises a perpendicular portion 47 (see FIG. 3A). The perpendicular portion 47 is a plate-shaped portion that is located between the body portion 40 and the first joint portion 41 and that extends in a substantially planar manner in a direction substantially perpendicular to the axis A. The perpendicular portion 47 extends from a first end of the stay 4 to a second end of the stay 4 in the width direction, as an example.

In step (3) described above in the process of manufacturing the muffler 1 of the second embodiment, a pressing jig 5 configured to be suitable for the stays 4 of the second embodiment is used. Specifically, the pressing jig 5 has at least one contact surface 50 that extends in a substantially planar manner. The at least one contact surface 50 faces substantially perpendicular to the axis A when pressing the inner pipe 3 and so on. The pressing jig 5 presses the inner pipe 3 and the stay 4 in a state in which the at least one contact surface 50 is in contact with the perpendicular portion 47.

[3. Third Embodiment]

The muffler 1 of a third embodiment is different from the first embodiment, in terms of the configuration of the inner pipe 3. The muffler 1 of the third embodiment will be described below focusing on differences from that of the first embodiment.

Specifically, in the third embodiment, the inner pipe 3 includes a regular part 33 and an inclined part 34 (see FIG. 3B). The regular part 33 includes the first opening 30, and the inclined part 34 is adjacent to the regular part 33 and includes the second opening 31.

Similarly to the first embodiment, the regular part 33 extends along the axis A, and the axis A passes through the center of a cross section of the regular part 33.

In contrast, the inclined part 34 extends in a direction inclined with respect to the axis A. The inclined part 34 extends straight, as an example, but is not limited thereto and may be curved.

The muffler 1 of the third embodiment is installed in a vehicle such that the inclined part 34 is inclined downward toward the second opening 31.

[4. Effects]

(1) For a muffler having a double-pipe structure as described in the embodiments above, a technique is known to support an inner pipe by a separator that is a plate-shaped member extending substantially orthogonally to an axis of the muffler and that is provided to surround the inner pipe. Another technique is also known to support the inner pipe by two or more short stays connecting the inner pipe and the shell member. When these techniques are adopted, thermal elongation in the inner pipe may cause stress to concentrate on one or more joints between the inner pipe and the shell member, or on one or more joints between the inner pipe and the separator or the stays, thereby leading to damage to the one or more joints.

Here, although the problem described above may be addressed by not using such a separator or stays, damage may occur due to vibrations caused by exhaust pulsation, or damage or noise may occur due to resonance generated in the inner pipe.

Alternatively, by providing a cushioning material (e.g., a wire mesh) at the one or more joints between the inner pipe and the shell member, it may be possible to inhibit stress from concentrating on the joint during the thermal elongation of the inner pipe. However, providing the cushioning material increases a manufacturing cost. In addition, condensed water accumulated inside the shell member may pass through the cushioning material and flow into an exhaust pipe connected to the muffler, thereby causing the exhaust pipe to be blocked or the condensed water to freeze inside the exhaust pipe, so that it may become impossible to start the engine.

In contrast, according to the above-described embodiments, since the first surface 45 of the stay 4 faces the outer-circumferential surface 32 of the inner pipe 3 and the second surface 46 faces the inner-circumferential surface 25 of the shell member 2, the stay 4 can deform in accordance with the thermal elongation of the inner pipe 3. More specifically, for example, the angle d1 formed by intersection of the first joint portion 41 and the body portion 40 and the angle d2 formed by intersection of the second joint portion 42 and the body portion 40 vary in accordance with the thermal elongation of the inner pipe 3. In addition, since the longitudinal direction L of the stay 4 is inclined with respect to the axis A, the stay 4 can be made longer, thereby reducing a difference in length of the thermal elongation between the inner pipe 3 and the stay 4. Accordingly, it is possible to inhibit occurrence of damage to the stay 4 due to the thermal elongation, thereby reducing the influence of the thermal elongation.

The stay 4 is expected to make a space occupancy ratio of the cross section of the shell member 2 smaller than that of the separator. As a result, an internal space of the shell member 2 can be utilized effectively.

In addition, since the stay 4 has a simpler structure than the separator, the stay 4 is manufactured more easily, thereby making it possible to ensure stable quality.

Even when the two or more stays 4 are provided, it is possible to weld the stays 4 to the inner pipe 3 in a single welding step, thereby streamlining the welding step.

In addition, it is possible to inhibit the vibrations and noise effectively by determining the positions of the first and second joint portions 41 and 42 of each of the stays 4, taking into consideration characteristics of the resonance in the shell member 2 and the inner pipe 3.

(2) The body portion 40 of the stay 4 extends in a substantially planar manner. This allows the stay 4 to deform appropriately in accordance with the thermal elongation of the inner pipe 3.

(3) The body portion 40 of the stay 4 includes the protrusion 43. This makes it possible to improve rigidity of the stay 4.

(4) The stay 4 of the muffler 1 of the second embodiment includes the perpendicular portion 47 extending in a substantially planar manner in the direction substantially perpendicular to the axis A. As a result, in step (3) in the process of manufacturing the muffler 1, by pressing the perpendicular portion 47 with the contact surface 50, which extends in a substantially planar manner, of the pressing jig 5, it is possible to press, into the intermediate shell member 2A, the inner pipe 3 to which the stays 4 are joined. This makes it possible to press the stays 4 effectively by the pressing jig 5 in the process of manufacturing the muffler 1.

(5) In the third embodiment, the part of the inner pipe 3 that includes the second opening 31 is formed as the inclined part 34 inclined downward toward the second opening 31.

[5. Other Embodiments]

(1) In the above-described embodiments, the muffler 1 has the double-pipe structure, and the shell member 2 and the inner pipe 3 each have a cylindrical shape extending straight. However, the present disclosure is not limited thereto, and, for example, both or one of the shell member and the inner pipe may have a curved shape. In such a case, although it may be difficult to support the inner pipe by the above-described separator, use of the stay 4 enables the inner pipe to be supported securely.

The shell member may be a tubular member, not cylindrical, having a cross section that is substantially elliptical or substantially rectangular, for example. Furthermore, in this case, the inner pipe may be provided to extend from the opening provided in the outer-circumferential surface of the shell member, and similarly to the above-described embodiments, the inner pipe may be supported by the stay inclined with respect to the axis of the inner pipe.

(2) Two or more functions of a single element in the above-described embodiments may be performed by two or more elements, and a single function of a single element may be performed by two or more elements. Two or more functions performed by two or more elements may be performed by a single element, and a single function performed by two or more elements may be performed by a single element. Part of the configuration in the above-described embodiments may be omitted. At least a part of the configuration in the above-described embodiments may be added to or replace another configuration in the above-described embodiments.

[6. Technical Ideas Disclosed Herein]

[Item 1]

A muffler to be installed in a vehicle, comprising: a shell member including therein a flow path for exhaust gas from an engine; an opening end portion surrounding an opening that allows an inside and an outside of the shell member to communicate with each other; an inner pipe joined to the opening end portion and arranged to extend from the opening to the inside of the shell member; and at least one stay that is a plate-shaped elongated member extending in a longitudinal direction thereof and including a first surface and a second surface opposite to each other in a thickness direction of the at least one stay, the at least one stay including: a first joint portion provided at a first end of the at least one stay in the longitudinal direction and joined to an outer-circumferential surface of the inner pipe, a second joint portion provided at a second end of the at least one stay in the longitudinal direction and joined to an inner-circumferential surface of the shell member, and a body portion that is provided between the first joint portion and the second joint portion and that extends in the longitudinal direction, the at least one stay being arranged such that the longitudinal direction of the at least one stay is inclined with respect to an extending direction of the inner pipe, the second joint portion being located closer to the opening than the first joint portion is, and the at least one stay being arranged such that the first surface faces the outer-circumferential surface of the inner pipe.

[Item 2]

The muffler according to Item 1, wherein the shell member is a pipe-shaped member extending in the extending direction of the inner pipe, the shell member including, at respective opposite ends thereof, a first opening and a second opening, the inner pipe is joined to the opening end portion surrounding the first opening of the shell member, the second joint portion is located closer to the first opening than the first joint portion is.

[Item 3]

The muffler according to Item 1 or 2, wherein the body portion extends in a substantially planar manner.

[Item 4]

The muffler according to any one of Items 1 to 3, wherein the body portion includes a protrusion.

[Item 5]

The muffler according to any one of Items 1 to 4, wherein the at least one stay further includes a perpendicular portion that is located between the body portion and the first joint portion and that extends in a substantially planar manner in a direction substantially perpendicular to the extending direction of a part of the inner pipe joined to the opening end portion.

[Item 6]

The muffler according to any one of Items 1 to 5, wherein a part of the inner pipe including an end located in a space inside the shell member is formed as an inclined part inclined downward toward the end.