PRODUCING METHOD OF WOUND MUFFLER, AND WOUND MUFFLER

TECHNICAL FIELD

The present invention relates to a producing technique of a wound muffler.

BACKGROUND ART

There has been disclosed a conventional technique regarding a muffler formed by winding a platy workpiece around a die so as to form a cylindrical main body, and inserting a silencer into an inside of the main body, that is, a so-called “wound muffler” (see Patent Literature 1 below, for example).

CITATION LIST
Patent Literature

Patent Literature 1: Japanese Patent Application Publication No, 2001-323809

SUMMARY OF THE INVENTION
Technical Problem

In the above patent literature, in order to extend an inlet pipe and an outlet pipe for exhaust gas of a silencer to an outside of an main body, a hole is opened in each cover that covers each aperture of the main body formed in a cylindrical shape. Each pipe of the silencer is extended from the hole formed in each cover to the outside.

In the above-configured related art, the structure of the wound muffler is limited. Specifically, after the main body is formed in a cylindrical shape, it is impossible to insert the silencer having a longer length in the radial direction than a diameter of each aperture of the cylindrical main body into the main body. Hence, the structure is limited to a structure in which each aperture of the main body is covered by each cover after the silencer is inserted in the main body formed in a cylindrical shape, and then each pipe of the silencer is extended from each cover.

In light of the above situation, the present invention provides a producing method of a wound muffler and a wound muffler capable of enlarging a silencer in length greater than a diameter of each aperture of a cylindrical main body after the silencer is inserted into the cylindrical main body, thereby enhancing flexibility of the structure.

Solution to Problem

Problems to be solved by the present invention are as above, and subsequently, means for solving the above problems will be explained.

Specifically, in claim 1, provided is a producing method of a wound muffler formed by inserting a silencer into an inside of a main body formed in a cylindrical shape, the silencer including an expandable part expandable in an axial direction in at least one of an inlet pipe for exhaust gas and an outlet pipe for exhaust gas, the method including: inserting the silencer into the inside of the main body with the expandable part of the silencer contracted; and thereafter, expanding the expandable part of the silencer so as to extend a front end of the pipe including the expandable part to an outside of the main body.

In claim 2, provided is a wound muffler formed by inserting a silencer into an inside of a main body formed in a cylindrical shape, the silencer including an expandable part expandable in an axial direction in at least one of an inlet pipe for exhaust gas and an outlet pipe for exhaust gas.

In claim 3, the expandable part includes mountain-folded portions and valley-folded portions, each mountain-folded portion to be a projecting portion if the expandable part is contracted, and each valley-folded portion to be a recessed portion if the expandable part is contracted, and the mountain-folded portions and the valley-folded portions are alternately arranged in a direction along a circumferential direction and along the axial direction of the pipe.

According to the present invention, in production of the wound muffler, it is possible to enlarge the silencer in length greater than the diameter of each aperture of the cylindrical main body after the silencer is inserted into the cylindrical main body, thereby enhancing flexibility of the structure of the wound muffler.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] FIG. 1(a) and FIG. 1 (b) are a perspective view and a plan view of a muffler according to a first embodiment, respectively.

[FIG. 2] FIG. 2(a) is a drawing showing a producing process of a pipe member, FIG. 2(b) is a drawing showing a process of disposing a contraction part in the pipe member, and FIG. 2(c) is a drawing showing a process of assembling an expandable pipe to a silencer.

[FIG. 3] FIG. 3 is a drawing showing a process of inserting the silencer into a main body.

[FIG. 4] FIG. 4(a) is a drawing showing a process of expanding the expandable part of the silencer, and FIG. 4(b) is a drawing showing a state in which Covers are fixed to the main body.

[FIG. 5] FIG. 5(a) is a plan view showing a muffler according to a second embodiment, and FIG. 5(b) is a sectional view taken along line X-X of FIG. 5(a).

MODES FOR CARRYING OUT THE INVENTION

Next, embodiments of the invention will be described.

The technical scope of the present invention is not limited to embodiments mentioned below, and the technical scope of the present invention extends widely over the whole scope of technical idea intended truly by the present invention which is disclosed by the matters described in the specification and the drawings.

First, with reference to FIGS. 1(a) and (b), a schematic configuration of a muffler 10 that is the first embodiment of a muffler according to the present invention will be described. For each component included in the muffler 10, stainless steel may be used as a main material thereof, for example. in the present specification, respective directions in the muffler 10 are defined by using arrows indicated in FIGS. 1(a) and (b),

As shown in FIGS. 1(a) and (b), the muffler 10 according to the present embodiment includes a cylindrical main body 11 having apertures in a frontward-rearward direction. The main body 11 is formed by winding a platy workpiece around a not-shown die, bringing both ends thereof to abut to each other, and joining these ends through lock-seaming or welding into a cylindrical shape. The main body 11 of the present embodiment is formed such that a front aperture 11a thereof has a shorter length in a rightward-leftward direction than that of a rear aperture 11b (see FIG. 3). The front aperture 11a is sealed by a front cover 12, and the rear aperture 11b is sealed by a rear cover 13, respectively.

Inside the main body 11, a silencer 20 is inserted. The silencer 20 includes a first platy separator 21 and a second platy separator 22 in each of which a number of holes (not shown) are formed. The first separator 21 and the second separator 22 are arranged with a distance therebetween in the rightward-leftward direction, and the first separator 21 is disposed rightward of the second separator 22.

The inside of the main body 11 in the muffler 10 is divided by the first separator 21 and the second separator 22 into a first expansion room R1, a second expansion room R2, and a third expansion room R3 in order from an upstream of exhaust gas (the right side in the muffler 10).

The silencer 20 includes an inlet pipe 23 introducing the exhaust gas from an outside of the muffler 10 to the first expansion room R1, and an outlet pipe 24 guiding the exhaust gas from the third expansion room R3 to the outside of the muffler 10.

Specifically, the inlet pipe 23 has an upstream end 23a located in a front outside of the muffler 10, and the inlet pipe 23 extends from the upstream end 23a in the rearward direction through a hole opened in the front cover 12 into the second expansion room R2. Furthermore, the inlet pipe 23 is bent at approximately 90° in the second expansion room R2 to extend rightward, and extends through the first separator 21 so that a downstream end 23b thereof enters the first expansion room R1. In this manner, the inlet pipe 23 brings the front outside of the muffler 10 to communicate with the first expansion room R1.

The outlet pipe 24 has an upstream end 24a located in the third expansion room R3, and the outlet pipe 24 extends from the upstream end 24a in the rightward direction, and extends through the second separator 22 and the first separator 21. In addition, the outlet pipe 24 extends through a hole 11c (see FIGS. 4(a) and (b)) opened in a right side of the muffler 10, and a downstream end 24b thereof extends to a right outside of the muffler 10. In this manner, the outlet pipe 24 brings the third expansion room R3 to communicate with the right outside of the muffler 10.

An upstream end 25a of an exhaust pipe 25 is connected to the downstream end 24b of the outlet pipe 24. The exhaust pipe 25 is disposed to be bent at approximately 90° so that a downstream end 25b thereof extends in the rearward direction.

As aforementioned, the muffler 10 according to the present embodiment is configured such that the exhaust gas is introduced via the inlet pipe 23 from the outside of the muffler 10 to the first expansion room R1, and the exhaust gas is further guided into the second expansion room R2 and into the third expansion room R3 in turns through the holes opened in the first separator 21 and in the second separator 22, and is then guided via the outlet pipe 24 and the exhaust pipe 25 from the third expansion room R3 to the outside of the muffler 10. In this process, exhaust noises from a vehicle body including the muffler 10 is reduced.

In the muffler 10 according to the present embodiment, the silencer 20 includes an expandable part 30 expandable in an axial direction (rightward-leftward direction) in the outlet pipe 24. Specifically, as shown in FIG. 2(b), in a middle of an expandable pipe 30P, mountain-folded portions Lu to be projecting portions if the expandable part 30 is contracted, and valley-folded portions Ld to be recessed portions if the expandable part 30 is contracted are alternately arranged in a direction along a circumferential direction and along the axial direction of the pipe, thereby forming the expandable part 30 to be expandable in the rightward-leftward direction. The expandable pipe 30P is connected as the downstream end 24b of the outlet pipe 24. The silencer 20 is inserted into the inside of the main body 11 in a state in which the expandable part 30 is contracted, and thereafter, the expandable part 30 is expanded. Through this, the downstream end 24b that is a front end of the outlet pipe 24 including the expandable part 30 is extended to the outside of the main body 11.

Next, with reference to FIG. 2 to FIG. 4, each step of producing the muffler 10 will be described.

First, as shown in FIG. 2(a), a platy member B is subjected to bending as indicated by an arrow A, and both ends thereof are brought to abut to each other to be joined by welding into a pipe member P. The producing process of the pipe member P may be fitted, and a general-purpose seamless pipe may be used as the pipe member P.

Next, as shown in FIG. 2(b), the expandable part 30 is formed in the pipe member P, thereby forming the expandable pipe 30P. Specifically, a die surface of each outer die Po formed in a recessed shape in a radially outward direction is pressed against the pipe member P in a radially inward direction from an outer circumferential surface of the pipe member P as indicated by arrows Fr of FIG. 2(b), and at the same time, a die surface of each inner die Pi formed in a projecting shape in the radially outward direction is pressed against the pipe member P via each sliding member Ps in the radially outward direction from an inner circumferential surface of the pipe member P as indicated by arrows Fs of FIG. 2(b). This operation is repetitively carried out while the pressing position is shifted in an axial direction and in a circumferential direction, thereby alternately forming the mountain-folded portions Lu and the valley-folded portions Ld so as to form the expandable part 30 in the middle of the pipe member P. The cylindrical portions in which no expandable part 30 is formed are respectively defined as an end 30a on the outlet pipe 24 side, and an end 30b on the exhaust pipe 25 side. In the present embodiment, the expandable part 30 is formed in an octagonal shape if viewed in the axial direction, but a configuration of folding the expandable part 30 in another polygonal shape may be employed. This means that the structure of the expandable part 30 may be changed depending on the structure of the muffler 10, the diameter of the pipe member P, and others.

Next, as shown in FIG. 2(c), the expandable pipe 30P is assembled to the silencer 20. Specifically, the end 30a of the expandable pipe 30P and the downstream side of the outlet pipe 24 are joined to each other by welding. Through this, the expandable part 30 is disposed to the outlet pipe 24 in the silencer 20. The end 30b of the expandable pipe 30P serves as the downstream end 24b of the outlet pipe 24.

Next, as shown in FIG. 3, the silencer 20 including the expandable part 30 is inserted into the main body 11, At this time, the silencer 20 is inserted from the front aperture 11a into the main body 11 as indicated by an arrow B in FIG, 3 with the expandable part 30 contracted (reduced in length in the rightward-leftward direction). It may be configured that the silencer 20 is inserted into the main body 11 from the rear aperture 11b, instead.

Next, as indicated in dotted lines W1 in FIG. 4(a), respective front ends of the first separator 21 and the second separator 22 are joined to an end of the front aperture 11a of the main body 11 by welding. At the same time, respective rear ends of the first separator 21 and the second separator 22 are joined to an end of the rear aperture 11b of the main body 11 by welding. Through this, the silencer 20 is fixed to the main body 11. It may be configured that the silencer 20 and the main body 11 are fixed to each other by a method other than welding, such as fixing tools.

As indicated by an arrow P in FIG. 4(a), a tensile force is applied to the downstream end 24b of the silencer 20 so as to expand the expandable part 30. Through this, as shown in FIG. 4(b), the downstream end 24b that is a front end of the outlet pipe 24 is extended through the hole 11c to the outside of the main body 11. The hole 11c may be opened in the platy workpiece at a stage before the main body 11 is formed into a cylindrical shape, or after the main body 11 is formed into a cylindrical shape.

As shown in FIG. 4(b), the front aperture 11a is sealed by the front cover 12, and the rear aperture 11b is sealed by the rear cover 13. At this time, the inlet pipe 23 is inserted into a hole previously opened in the front cover 12 so as to be extended through the front cover 12. Through this, the upstream end 23a is extended to the front outside of the muffler 10.

As indicated in dotted lines W2 in FIG. 4(b), the downstream end 24b of the outlet pipe 24 is joined to the hole 11c of the main body 11 by welding. Through this, the downstream end 24b is fixed to the main body 11. Subsequently, as shown in FIG. 1(b), the downstream end 24b and the upstream end 25a of the exhaust pipe 25 are joined to each other by welding, thereby assembling the exhaust pipe 25 to the muffler 10.

As aforementioned, the muffler 10 according to the present embodiment is a wound muffler formed by inserting the silencer 20 into the inside of the main body 11 formed in a cylindrical shape, the silencer 20 includes the expandable part 30 expandable in the axial direction in the outlet pipe 24 for exhaust gas, and the silencer 20 is inserted into the inside of the main body 11 with the expandable part 30 of the silencer 20 contracted, and thereafter, the expandable part 30 of the silencer 20 is expanded, thereby extending the downstream end 24b of the outlet pipe 24 to the outside of the main body 11.

As aforementioned, in the muffler 10 according to the present embodiment, after the silencer 20 is inserted into the cylindrical main body 11, the expandable part 30 of the silencer 20 is so expanded as to extend the downstream end 24h of the outlet pipe 24 to the outside of the main body 11. Through this, it is possible to enlarge the silencer 20 in length greater than the diameter (length in the rightward-leftward direction) of the front aperture 11a of the cylindrical main body 11, thus enhancing flexibility of the structure of the muffler 10. Specifically, without being limited to the structure of extending the pipe of the silencer 20 from the hole opened in the front cover 12 or in the rear cover 13, it is possible to extend the pipe from the hole (hole 11c in the present embodiment) opened in the main body 11. In other words, it is possible to enlarge the silencer 20 in length in a direction (rightward-leftward direction in the present embodiment) orthogonal to the direction in which the silencer 20 is inserted into the main body 11 (frontward-rearward direction in the present embodiment) so as to extend the pipe (outlet pipe 24 in the present embodiment).

Next, with reference to FIGS. 5(a) and (b), a schematic configuration of a muffler 110 that is the second embodiment of the muffler according to the present invention will be described. Hereinafter, respective directions in the muffler 110 are defined by using arrows indicated in FIGS. 5(a) and (b).

As shown in FIGS. 5(a) and (b), the muffler 110 according to the present embodiment includes a cylindrical main body 111 having apertures in the rightward-leftward direction. The left aperture of the main body 111 is sealed by a left cover 112, and the right aperture thereof is sealed by a right cover 113, respectively.

Inside the main body 111, a silencer 120 is inserted. The silencer 120 includes a first platy separator 121 and a second platy separator 122 in each of which a number of holes (not shown) are opened. The inside of the main body 111 in the muffler 110 is divided into the first expansion room R1, the second expansion room R2, and the third expansion room R3 in order from the upstream of the exhaust gas (right side in the muffler 110) by the first separator 121 and the second separator 122.

The silencer 120 includes an inlet pipe 123 introducing the exhaust gas from an outside of the muffler 110 to the first expansion room RI, and an outlet pipe 124 guiding the exhaust gas from the third expansion room R3 to the outside of the muffler lift

As aforementioned, the muffler 110 according to the present embodiment is configured such that the exhaust gas is introduced via the inlet pipe 123 from the outside of the muffler 110 to the first expansion room R1, the exhaust gas is further guided through the holes opened in the first separator 121 and in the second separator 122 into the second expansion room R2 and into the third expansion room R3 in turns, and is then guided via the outlet pipe 124 from the third expansion room R3 to the outside of the muffler 10. In this process, exhaust noises from a vehicle body including the muffler 110 is reduced.

In the muffler 110 according to the present embodiment, the silencer 120 includes an expandable part 130 expandable in the axial direction (frontward-rearward direction) in the inlet pipe 123. Specifically, as shown in FIGS. 5(a) and (b), mountain-folded portions and valley-folded portions are alternately arranged at a portion of the inlet pipe 123 intersecting an inner circumferential surface of the main body 111, thereby forming the expandable part 130 expandable in the frontward-rearward direction. The silencer 120 is inserted into the inside of the main body 111 in the rightward-leftward direction with the expandable part 130 contracted, and thereafter, the expandable part 130 is expanded in the frontward-rearward direction. Through this, a front end of the inlet pipe 123 including the expandable part 130 is extended to the outside of the main body 111 through a hole 111c.

As aforementioned, in the muffler 110 according to the present embodiment, after the silencer 120 is inserted into the cylindrical main body 111, the expandable part 130 of the silencer 120 is so expanded as to extend the front end of the inlet pipe 123 to the outside of the main body 111. Accordingly, it is possible to enlarge the silencer 120 in length greater than the diameter (length in the frontward-rearward direction) of the aperture of the cylindrical main body 111, thus enhancing flexibility of the structure of the muffler 110. Specifically, without being limited to the structure of extending the pipe of the silencer 120 from the hole opened in the left cover 112 or in the right cover 113, it is possible to extend the pipe from the hole (hole 111c in the present embodiment) opened in the main body 111. In other words, it is possible to enlarge the silencer 120 in length in a direction (frontward-rearward direction in the present embodiment) orthogonal to a direction in which the silencer 120 is inserted into the main body 111 (rightward-leftward direction in the present embodiment) so as to extend the pipe (inlet pipe 123 in the present embodiment).

In this manner, in the muffler according to the present invention, the pipe of which front end is extended to the outside of the main body by expanding the expandable part of the silencer may be at least one of the inlet pipe for the exhaust gas and the outlet pipe for the exhaust gas. It may be configured to provide the expandable part to both the inlet pipe for the exhaust gas and the outlet pipe for exhaust gas so as to extend each front end thereof to the outside of the main body.

In the muffler 10 according to the first embodiment and the muffler 110 according to the second embodiment, it is configured that the front end of the pipe (outlet pipe 24, inlet pipe 123) including the expandable part (30, 130) is extended from the hole (11c, 111c) opened in the main body (11, 111), but it may be configured that the front end is extended from a hole opened in any one of the covers.

REFERENCE SIGNS LIST

10 muffler

11 main body

20 silencer

24 outlet pipe

24
b downstream end

30 expandable part

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to enlarge the silencer in length greater than the diameter of each aperture of the cylindrical main body after the silencer is inserted into the cylindrical main body; therefore, the present invention is industrially useful.

PRODUCING METHOD OF WOUND MUFFLER, AND WOUND MUFFLER

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