JPH0842336A - Manufacture for corrosion resistant muffler - Google Patents

Abstract

PURPOSE:To provide a method for producing a corrosion resistant muffler for attaining noise absorption and sound insulation by filling and outer pipe provided on the outer periphery part of an outlet pipe with a noise absorbing material without the fusion loss of the noise absorbing material, and by bending and welding works in a production process. CONSTITUTION:In an outer pipe attaching process, the other end of an outer pipe 8 with its one end opened is fixed to the periphery of the small hole opened part 4 of an outlet pipe 4. In a frame assembling process, an inlet pipe 1 and the outlet pipe 4, are attached to an inner plate 6 and an outer plate 5 disposed in a muffler, and inner pipes 2 and 3 are attached, if necessary. In a coating process, the front and back surfaces of a member forming a frame are coated with a corrosion resistant material and burnt. In a noise absorbing material filling process, a part between the outlet pipe 4 and the outer pipe 8 is filled with a noise absorbing material 9. In an outer pipe diameter reducing process, the diameter of one end of the outer pipe 8 is reduced. In a final process, an outer shell is cylindrically attached to the periphery of the frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a corrosion-resistant muffler, and more particularly to a method for producing a corrosion-resistant muffler in which corrosion-resistant processing is applied to an inexpensive material which is weak against corrosion and which has improved corrosion resistance. .

[0002]

2. Description of the Related Art Conventionally, a muffler (hereinafter referred to as a muffler) for reducing exhaust noise is provided in an exhaust system of a vehicle equipped with an internal combustion engine. By the way, since the exhaust gas discharged from the internal combustion engine contains water, etc., if the vehicle is used for a long period of time, the muffler will be corroded, holes will be opened and the exhaust gas will leak, and the noise reduction effect will be reduced. There is a risk of becoming low.

In Japanese Utility Model Application Laid-Open No. 62-107076, therefore, it is possible to improve the fire resistance, heat resistance, and corrosion resistance of the exhaust system equipment by coating the inner surface of the exhaust system equipment with a ceramic such as alumina. Has been described.
This coating is effective in suppressing the cost of the muffler to be used when a material such as iron which is weak against corrosion but is inexpensive is subjected to a corrosion preventing treatment such as ceramic coating or enamel.

On the other hand, with the recent improvement in performance of internal combustion engines,
There are problems that the exhaust noise increases and noise of a specific frequency occurs. To solve this problem, a large number of small holes are formed in the outer peripheral portion of the outlet pipe of the muffler, and a chamber filled with a sound absorbing material such as glass wool is formed by an outer pipe around the small hole forming portion. Noise is being reduced.

[0005]

However, a large number of small holes are formed in the outer peripheral portion of the outlet pipe of the muffler,
In order to prevent corrosion of the muffler that is sound-absorbing and sound-insulating by forming a chamber filled with a sound absorbing material such as glass wool around the small hole perforation by an outer pipe,
When a ceramic or the like is coated by using the technique described in Japanese Patent No. 107076, the sound absorbing material such as glass wool may be melted and damaged by the heat of firing. Further, in a muffler provided with a ceramic coat, a heat-resistant enamel coat or the like, if the bending process is performed in the manufacturing process, the coating film may be peeled off.

Therefore, according to the present invention, a large number of small holes are formed in the outer peripheral portion of the outlet pipe of the muffler, and a chamber filled with a sound absorbing material such as glass wool is formed by the outer pipe around the small hole forming portion. In the muffler that absorbs and protects sound, a ceramic coating, a heat-resistant enamel coat, etc. are applied without melting the sound absorbing material due to firing heat, and a method for producing a corrosion-resistant muffler that does not impair corrosion resistance in the manufacturing process. It is intended to be provided.

[0007]

A method for manufacturing a corrosion-resistant muffler according to a first aspect of the present invention which achieves the above object, is a tubular shape in which exhaust gas discharged from an internal combustion engine is closed at both ends with outer plates. It is configured so that it is guided by an inlet pipe into the housing of the housing, and the exhaust pipe exhausts the exhaust gas from the inside of the housing, and it has corrosion resistance, and a large number of small holes are formed in the outlet pipe inside the housing. A method for manufacturing a corrosion-resistant muffler, in which an outer pipe having both ends reduced in diameter to the outer diameter of the outlet pipe is attached to the periphery of the small hole drilling part through a sound absorbing material, And a step of attaching an outer pipe to an outlet pipe for fixing the other end of the outer pipe in a state where one end is opened around the small hole drilling part, and an inner plate arranged in the cylindrical casing. And before Outer plate, the inlet pipe, the outlet pipe, and a frame assembly step of attaching the inner pipe, if necessary, coating a corrosion-resistant material on the front and back of the members constituting the assembled frame, a coating step of firing, A sound absorbing material filling step of filling a sound absorbing material between the outlet pipe and the outer tube, an outer tube diameter reducing step of reducing the diameter of one end of the outer tube opening, and a final step of attaching an outer shell in a cylindrical shape around the frame. And a process.

In this final step, the frame may be fixed to the outer shell via a heat resistant elastic body. Further, in the method for producing a corrosion-resistant muffler of the second aspect of the present invention which achieves the above-mentioned object, the exhaust gas discharged from the internal combustion engine is supplied by an inlet pipe into a cylindrical casing whose both ends are closed by outer plates. It is constructed so as to guide and mute sound, and exhaust gas is exhausted from the inside of the housing with an outlet pipe, and has corrosion resistance, and a large number of small holes are formed in the outlet pipe inside the housing. A method for manufacturing a corrosion-resistant muffler, in which an outer pipe, both ends of which are reduced in diameter to the outer diameter of the outlet pipe, is attached to the periphery of the portion through a sound absorbing material, wherein the small hole drilling portion of the outlet pipe is provided. Outer pipe mounting step to the outlet pipe that fixes the other end of the outer pipe in a state where one end is opened around the periphery of the inner pipe and the outer plate arranged in the tubular casing, A frame assembling process for attaching the inlet pipe, the outlet pipe, and an inner pipe as necessary, a first coating process for coating the front and back of members constituting the assembled frame with a corrosion-resistant material, and firing, and the outlet Sound absorbing material filling step of filling a sound absorbing material between the pipe and the outer tube, outer tube diameter reducing step of reducing the diameter of one end of the outer tube opening, and joining of the outer shell attached around the frame and the frame A second coating step of further coating the portion with a corrosion resistant material, and supplying a refrigerant to the outlet pipe to which the outer pipe is fixed,
The final step is to attach the outer shell around the frame by firing to form a tubular shape.

[0009]

According to the method of manufacturing a corrosion-resistant muffler of the first aspect of the present invention, one end is opened around the small hole drilling portion of the outlet pipe in the step of attaching the outer pipe to the outlet pipe. The other end of the outer pipe is fixed, and in the frame assembly process, the inner plate arranged in the tubular casing, the outer plate, the inlet pipe, the outlet pipe, and the inner pipe as necessary are attached, and the coating process is performed. In, in the front and back of the members constituting the assembled frame is coated with a corrosion-resistant material and fired, in the sound absorbing material filling step, the sound absorbing material is filled between the outlet pipe and the outer tube, and in the outer tube diameter reducing step, One end of the outer tube that opens is reduced in diameter, and in the final step, the outer shell is attached in a tubular shape around the frame.

In this final step, the frame may be fixed to the outer shell via the heat resistant elastic body. Further, according to the method for producing a corrosion-resistant muffler of the second aspect of the present invention, in the step of attaching the outer pipe to the outlet pipe, one end is opened around the small hole drilling portion of the outlet pipe. The other end of the outer pipe is fixed, and in the frame assembling process, the inner plate arranged in the tubular casing, the outer plate, the inlet pipe, the outlet pipe, and the inner pipe as necessary are attached, In the coating process, the front and back of the members that make up the assembled frame are coated with a corrosion resistant material and fired, and in the sound absorbing material filling process, the sound absorbing material is filled between the outlet pipe and the outer pipe to reduce the outer pipe diameter. The outer end of the outer tube is reduced in diameter, and is attached to the periphery of the frame in the second coating step. And the junction with the frame, is further coated corrosion resistance material, in the final step, while the refrigerant is supplied to the outlet pipe outer tube is fixed, the outer shell around the frame is attached to the cylindrical shape by sintering.

[0011]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1A is an external view showing the external appearance of a corrosion-resistant muffler 10 manufactured by the method for manufacturing a corrosion-resistant muffler of the present invention. The corrosion-resistant muffler 10 (hereinafter simply referred to as muffler 10) has a shape in which both ends of a cylindrical outer shell 7 are closed by outer plates 5, and an inlet pipe 1 for introducing exhaust gas from an internal combustion engine to the outer plate 5
And an outlet pipe 4 for discharging exhaust gas is connected.

FIG. 1 (b) shows the muffler 10 by cutting it into upper and lower halves in order to explain the internal structure of the muffler 10 of FIG. 1 (a) (FIG. 1 (b) is for explanation). Muffler 10
Is cut up and down, and the members forming the muffler 10 are not vertically divided in this way). The interior of the muffler 10 is divided into four spaces by three inner plates 6 arranged in parallel with the outer plate 5.

The inlet pipe 1 is extended to a space, and a large number of small holes 11 communicating with the inside are bored in the outer peripheral portion of the space of the inlet pipe 1. The end portion of the outlet pipe 4 is located in the space, and the outer pipe 8 is concentrically attached to the space of the outlet pipe 4 and the space portion. Both ends of the outer pipe 8 are reduced diameter portions 8a, which are fixed to the outer peripheral portion of the outlet pipe 4. Further, inside the muffler 10, a first inner pipe 2 that communicates the spaces with each other and a second inner pipe 3 that communicates the spaces with each other are provided. In the space of the first inner pipe 2, a large number of small holes 21 similar to the small holes 11 described above are provided in the outer peripheral portion. Also, 2
The outer plates 5 and the three inner plates 6 are provided with mounting holes H for hermetically inserting the inlet pipe 1, the first and second inner pipes 2, 3, the outlet pipe, and the outer pipe 8. Has been.

FIG. 2 is a partially enlarged perspective view of the outer pipe 8 shown in FIG. 1 (b) in which a part of the outer pipe 8 is cut away in order to explain the structure of the mounting portion of the outer pipe 8. . A large number of small holes 41 communicating with the inside of the outlet pipe 4 are bored in the outer peripheral portion of the outlet pipe 4 covered with the outer pipe 8 similarly to the small holes 11 described above. A space (chamber) between the outer pipe 8 and the outer peripheral portion of the outlet pipe 4 inside is filled with a sound absorbing material 9 such as glass wool.

FIG. 3 (a) is a perspective view showing the structure of the inner plate 6 shown in FIG. 1 (b), which partitions the space. As shown in FIG.
In order to connect the inner plate 6 to the inner peripheral portion of the outer shell 7 shown in (a), a bent portion 6a that is bent over the entire circumference is formed. And the inner plate 6
A mounting hole H for inserting the inlet pipe 1, the first inner pipe 2, and the outer pipe 8 is provided in the flat plate portion of.

Next, a method of manufacturing the muffler 10 having the above-described structure according to the first embodiment of the present invention will be described. In the first embodiment, first, as shown in FIG. 3 (b), the inner plate 6 shown in FIG. 3 (a) is provided with an inlet pipe 1 made of an inexpensive material such as iron and a first inner pipe. A pipe 2 and an outlet pipe 4 to which an outer pipe 8 whose one end is open (only this member is made of a SUS material, details will be described later) are fixed by welding or the like. The inlet pipe 1, the first inner pipe 2, and the outlet pipe 4 have small holes 11, 21 and 41 pre-drilled in necessary portions. The outer cylinder 8 is located at a portion that covers the small hole 41 of the outlet pipe 4, and is securely attached to the outlet pipe 4 by a reduced diameter portion 8a provided only at one end or by spot welding or the like. Outlet pipe 4
The outer cylinder 8 is joined and fixed to the inner plate 6 by welding or the like.

Subsequently, as shown in FIG. 3 (c), two more inner plates 6 ', 6 "(where the inner plate 6 is mounted are attached to the assembly (assembly) in the state of FIG. 3 (b). For the sake of clarity, the inner plate 6 on the inlet pipe 1 side is designated as 6'and the inner plate 6 on the outlet pipe 4 side is designated as 6 ") and is attached at a predetermined interval. The second inner pipe 3 is preliminarily fixed to the inner plate 6 ″ by welding or the like.
After this, the outer plate 5 is attached to the inlet pipe 1 side with a predetermined gap from the inner plate 6 ',
An outer plate 5 ′ (in order to clarify the mounting position of the outer plate, the outer plate 5 on the outlet pipe 4 side is referred to as 5 ′) is attached to the outlet pipe 4 side with a predetermined distance from the inner plate 6 ″. It is fixed by being joined by welding.

As described above, the inlet pipe 1, the first inner pipe 2, the second inner pipe 3, the outlet pipe 4, the outer plates 5, 5 ', and the three inner plates 6, 6', 6 "are formed. The assembled assembly will be referred to as an inner assembly hereinafter.The inner assembly assembled as shown in Fig. 3 (c) is shown in Fig. 4 (a).
As shown in, the inlet pipe 1, the first inner pipe 2, the second inner pipe 3, the outlet pipe 4,
Outer plates 5, 5 ', 3 inner plates 6,
Corrosion-resistant material is coated on the front and back of 6 ', 6 ". Actually, the inner assembly is coated with ceramic or enamel. At this time, the outer cylinder 8 of the outlet pipe 4 has one end thereof. The coating is performed with the opening left open, and then the coating material is baked.

As shown in FIG. 4 (b), the inner assembly thus entirely coated is followed by a sound absorbing material 9 such as glass wool in the space between the outlet pipe 4 and the outer pipe 8. Is filled. After that, in the inner assembly, as shown in FIG. 4C, the diameter of the opening of the outer pipe 8 is reduced, and the free end of the outer pipe 8 is fixed on the outer circumference of the outlet pipe 8. Are sealed in the outer tube 8.

In the step of reducing the diameter of the outer tube 8 shown in FIG. 4 (c), the outer tube 8 is deformed and the ceramic coating is peeled off, or the enamel baking is cracked and peeled off, and cracks are generated. It is conceivable that the corrosion characteristics will be significantly reduced. Therefore, only the material forming the outer pipe 8 is a material having a high durability against corrosion (for example, the above-mentioned S
US material) is used.

Thereafter, the bent portions 5a, 5a ', 6a, 6a', 6a "of the outer plates 5, 5'and the three inner plates 6, 6 ', 6" shown in FIG. An expandable sealant 12 is attached as shown in FIG. 5 (a). An intumam mat may be used for the expandable sealing material 12. Then, the expansive sealing material 1 is attached to the outer shell 7 which is coated in advance with a corrosion-resistant material on both sides.
The inner assembly with the 2 attached is fitted as shown in FIG. 5 (b). The inner assembly and the outer shell 7 are fixed to each other by the clamp 13 shown in part B of FIG. 5 (b).
Done by

As described above, the reason why the inner assembly is attached to the outer shell 7 via the expansive sealing material 12 is that when the inner assembly is fixed to the outer shell 7 by spot welding as in the conventional case, a coating layer for ceramic coating or enamel baking is applied. This is because the welding process causes scratches. Expandable seal material 1
2 is an outer shell 7 and inner plates 6, 6 ', 6 "
It is possible to prevent gas leakage (reduction in sound deadening performance) between the outer shell 7 and the inner plates 6, 6 ', 6 "due to the difference in the amount of thermal expansion of the inner plates 6, 6', 6". The outer shell 7 is reliably supported by "" to prevent vibration (radiated sound) of the outer shell 7.

FIG. 6 (a) is a partially enlarged sectional view of the portion A of FIG. 5 (b), and FIG. 6 (b) is a partially enlarged sectional view of the portion B of FIG. 5 (b). As shown in FIGS. 6 (a) and 6 (b), groove portions 6b and 7b are formed on the bent portion 6a of the inner plate 6 and the bent portion 5a of the outer plate 5 over the entire circumference. An expansive seal member 12 is attached to 6b and 7b. Also, as shown in FIG. 5 (b), the outer plate 5
The free end portion 5c of the bent portion 5a and both end portions 7c of the outer shell 7 are folded back in a substantially U-shape outside the mating surface of the both. Therefore, this U-shaped portion 5
When the clamp 13 having a cross-sectional shape as shown in FIG. 6B is fitted into the c and 7c from the outside, the inner assembly and the outer shell 7 are fixed via the sealing material 12. It suffices if the clamp 13 is attached to the outer shell 7 at several places all around.

In this way, since the outer plate 5 and the outer shell 7 can be joined together without any deformation after coating, the coating material does not crack or peel off, and the outer plate 5 and the outer shell 7 do not occur.
It is possible to use a low-cost ordinary steel (steel for enamel), and it is possible to reduce the cost of the muffler 10.

In the muffler 10 having the above-described structure, the sealing material 12 is sandwiched between the outer plate 6 and the inner plate 6 and the outer shell 7 to join them, so that each room shown in FIG. It is possible to prevent the exhaust gas from leaking during the period between and. Further, the outer plate 6 and the inner plate 6 and the outer shell 7 are joined to each other through the sealing material 12 and do not come into direct contact with each other to damage each other, so that the durability of the muffler 10 is improved.

Further, the muffler 1 having the above-mentioned structure
No. 0, the manufacturing method of the second embodiment of the present invention will be described. The manufacturing method of the corrosion resistant muffler of the second embodiment is as follows.
The manufacturing method up to that point is the same as the method for manufacturing the corrosion-resistant muffler of the first embodiment. That is, also in the method of manufacturing the corrosion-resistant muffler of the second embodiment, the inner assembly is formed, and the front and back are coated with the corrosion-resistant material.
The manufacturing method from (b) to FIG. 4 (c) is performed in the same manner as the manufacturing method of the first embodiment. Therefore, the description of the manufacturing method up to FIG. 4C is omitted.

In the method of manufacturing the corrosion-resistant muffler of the second embodiment, the inner assembly coated with the corrosion-resistant material on the front and back sides is the outer plate 5, 5'and the three inner plates 6, 6 ', 6 ″ Bent portions 5a, 5a ′, 6
The outer shell coated with a corrosion-resistant material on the front and back sides is the same as the method of joining the inner assembly and the outer shell in the conventional manufacturing method of the muffler without attaching the expansive sealing material 12 to a, 6a ', 6a ". Fitted in 7.

However, as described above, if the inner assembly is fixed to the outer shell 7 by spot welding in the same manner as in the conventional method, the coating layer of ceramic coating or enamel baking will be scratched by the welding process. Therefore, in the present invention, before the coated inner assembly is fitted into the outer shell 7 by press fitting, as shown in FIG. 7 (a), the outer plate 5, 5'and the three inner plates 6, 6 ' , 6 ″, the bent portions 5a, 5a ′, 6a, 6a ′, 6a ″ are further coated with a corrosion resistant material 14 such as a ceramic coating material or an enamel material.

As described above, if the coating of the joint portion of the inner assembly with the outer shell 7 is doubled, the coating layer is damaged by the welding process after the inner assembly is press-fitted into the outer shell 7. Less likely. Figure 7 (b) is Figure 7 (a)
7 shows the muffler 10 assembled by the process of FIG. 7B, and thereafter, the free end 5c of the bent portion 5a of the outer plate 5 of the muffler 10 shown in FIG. 7B and both ends of the outer shell 7 are shown. The part 7c is joined by a winding process.

In the muffler 10 of this embodiment, as shown in FIG.
As shown in (b), since the free end portion 5c of the bent portion 5a of the outer plate 5 projects ahead of the end portion 7c of the outer shell 7, the bent portion 5a of the outer plate 5 has an end portion of the outer shell 7. The free end portion 5c protruding first from 7c is folded back to the end portion 7c side of the outer shell 7 and
After sandwiching the end portion 7c of the, the tightening process is performed.

However, as in the conventional case, the free end 5c of the bent portion 5a of the outer plate 5 of the muffler 10 and the both ends 7c of the outer shell 7 may be joined by folding or winding as they are. The enamel processing part will be broken and peeled off. Therefore, as shown in FIGS. 8 (a) to 8 (c), the free end portion 5c of the bent portion 5a of the outer plate 5 and both ends of the outer shell 7 are folded before the outer plate 5 and the outer shell 7 are folded and tightened. Further, a coating process of applying a corrosion resistant material 14 such as a ceramic coating material or an enamel material to the portion 7c is performed.

In this coating process, first, as shown in FIG.
As shown in (a), the free end portion 5c of the bent portion 5a of the outer plate 5 protruding first from the end portion 7c of the outer shell 7
The anticorrosion material 14 is recoated. Then, in FIG.
As shown in (b), the free end portion 5c of the bent portion 5a of the outer plate 5 protruding ahead of the end portion 7c of the outer shell 7
However, the end portion 7c of the outer shell 7 is sandwiched by being folded back toward the end portion 7c of the outer shell 7. Next, the anticorrosion material 14 is recoded on the portion of the outer plate 5 to be wound, and the recoating portion is wound as shown in FIG. 8C. Further, in this embodiment, the corrugated end is recoated with the corrosion resistant material 14.

By thus re-coating the deformed portions in advance, cracking and peeling of the coating material at the joint between the outer plate 5 and the outer shell 7 can be suppressed, and the cost of the outer plate 5 and the outer shell 7 can be reduced. Ordinary steel (steel for enamel) can be used, and the cost of the muffler 10 can be reduced. After the end portions of the muffler 10 are joined by tightening as described above, cooling air that is a refrigerant is introduced from either the inlet pipe 1 or the outlet pipe 4 (in the embodiment shown in FIG. 9, Cooling air is introduced from the outlet pipe 4 by the pump 16), and the sound absorbing member 9 filled in the outer pipe 8 of the outlet pipe 4
While cooling (in this embodiment, glass wool), the outer plates 5, 5'and the inner plates 6, 6 ',
The joint between 6 ″ and the outer shell 7 is locally heated,
The joint is fired. This localized heating is shown in FIG.
The high-frequency heating device 15 shown in FIG.

By this firing, the ceramic coating and the enamel are re-baked, and there is no risk of exposing the base material (iron material in this embodiment) due to peeling of the ceramic coating or the enamel. Offered at low cost.

[0035]

As described above, according to the present invention,
A large number of small holes are drilled on the outer circumference of the muffler outlet pipe, and a chamber filled with a sound absorbing material such as glass wool is formed by an outer tube around the holed parts to absorb and protect sound. It is possible to prevent the muffler from being melted and damaged by the heat of baking, and to prevent the base material from being exposed due to peeling even if the muffler is bent in the manufacturing process.

[Brief description of drawings]

1A is an external view showing the appearance of a muffler produced by the method for producing a corrosion-resistant muffler of the present invention, and FIG. 1B is a sectional view showing the internal structure of the corrosion-resistant muffler of FIG. It is a perspective view explaining.

FIG. 2 is a partially cutaway perspective view illustrating a configuration of an outer pipe mounting portion of the outlet pipe shown in FIG. 1 (b).

3 (a) is a perspective view showing the structure of the inner plate shown in FIG. 1 (b), and FIG. 3 (b) illustrates a state in which an inlet pipe, an outlet pipe, and an inner pipe are attached to this inner plate. FIG. 3C is a manufacturing process diagram illustrating a state in which an inner plate, an outer plate, and an inner pipe are further attached to the state of (b).

4 (a) is a manufacturing process diagram showing a state in which a corrosion-resistant material is coated on the muffler assembly in the state of FIG. 3 (c), and FIG. 4 (b) shows the outlet pipe and the outer pipe in the state of (a). Manufacturing process drawing showing the state where the sound absorbing material is filled in between, (c) is
It is a manufacturing process drawing which shows the state where the opening part of the outer tube of the state of (b) was diameter-reduced.

5A is a manufacturing process diagram showing a state in which a sealing material is attached to the bent portions of the inner plate and the outer plate in the state of FIG. 4C, and FIG. 5B is a muffler in the state of FIG. It is a manufacturing process figure showing the state where the outer shell was fitted in the assembly.

6 (a) is a partially enlarged sectional view of a portion A in FIG. 5 (b), (b).
FIG. 6 is a partially enlarged sectional view of a B part in FIG. 5 (b).

FIG. 7 (a) is a manufacturing process drawing showing a state in which the bent portions of the inner plate and the outer plate of the muffler assembly in the state of FIG. 4 (c) are further coated with a corrosion-resistant material and press-fitted into the outer shell. 8] is a manufacturing process drawing showing the muffler in the state assembled by the process of (a).

FIGS. 8 (a) to 8 (c) are diagrams for explaining the end treatment process in the portion C in FIG. 7 (b), and FIG. 8 (a) is a view showing that the outer shell and the bent portion of the outer plate are further coated with a corrosion-resistant material. Manufacturing process drawing showing the state of coating, (b) is a manufacturing process drawing showing the state of re-coating the anticorrosion material on the part to be tightened after bending the coating treatment part of (a), (c) is
It is a manufacturing process figure explaining the state which carried out the winding-up process of the re-coating process part of (b), and the re-coating of the corrosion-resistant material to the end part which carried out the winding-up process.

FIG. 9 is a manufacturing process diagram showing a process of locally heating and firing the inner plate and the joint between the outer plate and the outer shell while supplying the refrigerant from the outer pipe to the muffler assembly in the state of FIG. 7 (b). Is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inlet pipe 2 ... 1st inner pipe 3 ... 2nd inner pipe 4 ... Outlet pipe 5 ... Outer plate 6 ... Inner plate 7 ... Outer shell 8 ... Outer pipe 8a ... Reduced diameter part 9 ... Sound absorbing material 10 ... Present invention Muffler 11 manufactured by: small hole 12 expansive sealing material 13 clamp 14 corrosion resistant material 21 small hole 41 small hole H mounting hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sumio Ogawa 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Ichiro Marumoto 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Yoshio Mizoguchi 1-1 Yanagisawa, Nagamine, Koda-cho, Nukata-gun, Aichi Prefecture Futaba Sangyo Co., Ltd.

Claims (3)

[Claims] 1. An exhaust gas exhausted from an internal combustion engine is guided by an inlet pipe into a cylindrical casing whose both ends are closed by outer plates, and the exhaust gas is discharged from the inside of the casing through an outlet pipe. Being configured,
It has corrosion resistance, and a large number of small holes are bored in the outlet pipe in the housing, and both ends are reduced to the same diameter as the outer diameter of the outlet pipe through a sound absorbing material around the holed portion. A method for manufacturing a corrosion-resistant muffler to which an outer pipe is attached, wherein the outlet pipe fixes the other end of the outer pipe in a state where one end is opened around the small hole drilling portion of the outlet pipe. A step of attaching the outer pipe to the outer casing, a frame assembly process of attaching the inlet pipe, the outlet pipe, and, if necessary, the inner pipe to the inner plate and the outer plate arranged in the tubular casing, and The coating step of coating the front and back of the members constituting the frame with a corrosion resistant material and firing, and filling a sound absorbing material between the outlet pipe and the outer pipe A sound-absorbing material filling step, an outer tube diameter reducing step of reducing the diameter of one end of the outer tube opening, and a final step of cylindrically mounting an outer shell around the frame. Production method. 2. The method for manufacturing a corrosion-resistant muffler according to claim 1, wherein in the final step, the frame is fixed to the outer shell via a heat resistant elastic body. . 3. Exhaust gas discharged from an internal combustion engine is guided by an inlet pipe into a cylindrical casing whose both ends are closed by outer plates, and is silenced so that the exhaust gas is discharged from the inside of the casing through an outlet pipe. Being configured,
It has corrosion resistance, and a large number of small holes are bored in the outlet pipe in the housing, and both ends are reduced to the same diameter as the outer diameter of the outlet pipe through a sound absorbing material around the holed portion. A method for manufacturing a corrosion-resistant muffler to which an outer pipe is attached, the outlet pipe fixing the other end of the outer pipe in a state in which one end is opened around the small hole drilling portion of the outlet pipe. A step of attaching the outer pipe to the outer casing, a frame assembly process of attaching the inlet pipe, the outlet pipe, and, if necessary, the inner pipe to the inner plate and the outer plate arranged in the tubular casing, and The first coating step of coating the front and back of the members forming the frame with a corrosion-resistant material and baking the same, and filling the space between the outlet pipe and the outer pipe with a sound absorbing material. A sound absorbing material filling step of filling, an outer tube diameter reducing step of reducing the diameter of one end of the outer tube opening, and a joint portion between the outer shell attached around the frame and the frame is further coated with a corrosion resistant material. A corrosion-resistant muffler comprising: a second coating step; and a final step in which a coolant is supplied to the outlet pipe to which the outer pipe is fixed, and an outer shell is attached in a cylindrical shape by firing around the frame. Manufacturing method.