Abstract: An exhaust muffler of an internal combustion engine has pipe sections on the inflow side and on the outflow side, respectively, and a muffler housing that is in communication with the pipe sections. The muffler housing, which includes an outer casing and end walls, is made at least in sections of a plastic material.

Abstract: A silencer for an exhaust system of a combustion engine, more preferably of a motor vehicle, has two end face bottoms facing away from each other, a closed circumferential jacket, at least one silencer insert, at least one inlet pipe and at least one outlet pipe. At least one of the pipes extends through the jacket into the silencer interior and is fastened to the jacket. The manufacture can be simplified if the pipe extending through the jacket has a cone, if the silencer insert on an intermediate pipe has a mating cone which engages in the cone.

Abstract: An engine includes an exhaust conduit having an exhaust port on an end of the exhaust conduit. The exhaust conduit has an angled inside surface that has a cross section that widens toward the exhaust port. The engine further includes a muffler having a housing with an intake pipe. The intake pipe is inserted through the exhaust port such that the intake pipe is wedged into the angled inside surface of the exhaust conduit.

Abstract: A muffler of a motorcycle having an outside diameter greater than the outside diameter d1 of a rectilinear portion of a branch pipe is disposed at a transverse portion of an exhaust pipe. Since the muffler is formed to be roughly elliptic in sectional shape, the outside diameter of the muffler is represented by a major diameter da as the length in the direction of a major axis and a major diameter db as the length in the direction of a minor axis. When the muffler is disposed between a swing arm and a seat to be along the transverse portion of the exhaust pipe, the muffler can be disposed on the more vehicle front side while securing the capacity thereof. Therefore, protrusion of the muffler toward the rear of the vehicle is suppressed, and the external appearance of a vehicle rear portion is enhanced.

Abstract: A silencer cover adapts to a heat expansion of a silencer even when, for example, the silencer cover has a large size and is attached to the silencer over an area from the front to the rear. A silencer cover is provided for a silencer connected to a downstream end of an exhaust pipe of an engine. The silencer cover is fixed to a fixing support provided to the silencer. The silencer is heat-expanded with the fixing support part fixed as a base. The fixing support part is provided at a front end portion, in a vehicle front-rear direction, of the silencer. With a tail pipe constituting a rear end portion of the silencer, the rear end portion of the silencer is provided with a slide structure in which the silencer cover is slidably supported.

Abstract: The invention relates to an exhaust gas after-treatment device for an internal combustion engine, including a housing into which an exhaust pipe that opens into a mixing chamber penetrates. The mixing chamber is shaped as a pot and reverses a direction of flow of the incoming exhaust gas whereby it returns the exhaust gas radially outside of the exhaust pipe. An open end of the pot-shaped mixing chamber opens into a collecting space which is designed so that it supplies the exhaust gas to at least one downstream SCR catalytic converter.

Abstract: An exhaust device in which a portion of an exhaust pipe covered by an exhaust pipe cover is rationalized. An exhaust device of a vehicle includes a muffler disposed in a rear part of the vehicle, an exhaust pipe extending from a front surface of a cylinder of an engine to the muffler while passing along an outer side of the engine in a lateral direction, a first exhaust pipe cover covering an entire periphery of an exhaust pipe front portion located near the outer side of the engine in the lateral direction, and a second exhaust pipe cover covering an outer side of an exhaust pipe rear portion located behind the engine.

Abstract: A chain saw includes a body in which an engine for driving a saw chain is laterally housed; a top handle provided above the body; and a muffler arranged below the engine, in which an exhaust outlet for discharging exhaust from the front side of the body to the outside opens forward from the front side of the body. Accordingly, not only the exhaust can be discharged forward from the front side of the body, but also the exhaust sound can be propagated forward so that less exhaust sound is heard by the operator, thereby improving the work environment.

Abstract: A tube comprises a series of guides with each successive guide smaller than a next prior guide forms an effective funnel with a smaller end extending toward into a larger end of a next adjacent guide. The larger end of the next adjacent guide extends past the smaller end of that prior guide and loops back to taper into smooth connection to the outside of the smaller end of that prior guide therein creating a cavity in the guide. Gas passing rapidly past the cavities causes a Bernoulli effect that reduces pressure within the cavities. Because the mouth of the guides is large, a vortex is induced from a shearing interface between gases within the cavity and the main flow of gas moving down the tube. A less energetic layer of gas is created that buffers tube guides from main gas flow through the tube center.

Abstract: A silencer for an exhaust system, more preferably of a motor vehicle, is provided with a silencer insert arranged in a silencer housing. The silencer includes a jacket, with at least one pipe section penetrating a through-opening of the jacket. Through welding of the pipe section to the silencer insert a weld seam formed pressure-tight between pipe section and jacket is relieved of mechanical load.

Abstract: A muffler combination includes two pipe units each having a cylindrical shell and having an entrance and an exit, an inlet tube connected to the entrance, an outlet tube connected to the exit, and a housing engaged in each of the cylindrical shells, the housings each include three openings formed on one side and two orifices formed on the other side, the cylindrical shells are disposed parallel to each other, and the entrance and the inlet tube of one of the cylindrical shells is located closer to the exit and the outlet tube of the other cylindrical shell whose entrance and inlet tube are located closer to the exit and the outlet tube of the cylindrical shell.

Abstract: A radiated sound reducing structure that reduces radiated sound generated in a pipe through which gas passes includes a first pipe and a second pipe that is arranged inside the first pipe and has, on an outer peripheral surface, a linear contact portion that is in linear contact with a portion of an inner peripheral surface of the first pipe. Also, a radiated sound reducing structure in a pipe through which gas passes includes a first pipe and a second pipe formed in a pseudo-cylindrical concave polyhedral shell that is arranged inside the first pipe and has, on an outer peripheral surface, a point contact portion, that is in point contact with a portion of the inner peripheral surface of the first pipe.

Abstract: An exhaust apparatus is provided with an exhaust gas pipe for discharging to the atmosphere an exhaust gas discharged from an internal combustion engine. The exhaust gas pipe has an upstream open end connected to the sound deadening device positioned at the upstream side of an exhaust gas discharging direction, and a downstream open end through which the exhaust gas is discharged to the atmosphere. At least one of the exhaust gas upstream side and the exhaust gas downstream side of the exhaust gas pipe has a diameter expansion structure expanded in diameter toward one of the upstream open end and the downstream open end. The exhaust apparatus comprises a plate provided in the diameter expansion structure to be held in opposing relationship with the discharge direction of the exhaust gas and having an open portion formed to pass through the plate in the discharge direction of the exhaust gas.

Abstract: A condensed water discharge apparatus is capable of smoothly excreting residual condensed water in a muffler. The device may include a through hole formed at the bottom of a muffler case, an inflow pipe communicated to the muffler case and in which exhaust gas flows, an exhaust pipe communicated to the atmosphere so that exhaust gas is exhausted from the muffler case thereto, a thermoelement, and a control valve mounted at the through hole so as to selectively open/close the through hole when driving or stopped by sliding about the through hole.

Abstract: A silencer for a two-stroke engine includes a first chamber and a second chamber, wherein a flow channel is provided between an outlet of a combustion chamber and the first chamber. A high charge degree of the combustion chamber has a pressure ratio in the region of the outlet which reduces or prevents an escape of fresh gas from the combustion chamber. The flow channel between the outlet and the first chamber is flow-favorably shaped in such a manner that the exhaust gas that flows out of the outlet because of its mass inertia predominantly flows into the first chamber and following charging of the first chamber flows back again and as a result a back pressure is formed in the direction of the combustion chamber.

Abstract: A ram intake unit mounted on a front portion of a frame structure of a motorcycle includes an acoustic material disposed along an inner wall of a ram air intake duct for absorbing induction noises, which duct forms an induction system through which an incoming wind can be introduced towards a motorcycle combustion engine, and a holder disposed inwardly of the acoustic material for securing the acoustic material to the ram air intake duct.

Abstract: An exhaust outlet 34 is formed at the center of a rear end wall 46 of a tail cap 21 closing a rear end opening of a muffler body 20, and a tail pipe 30 is connected at its rear end to the exhaust outlet 34. The exhaust outlet 34 is formed through a tail pipe supporting member 35 mounted on the rear end wall 46. The tail pipe supporting member 35 is formed with an annular mud guiding groove 37 opening rearward around the exhaust outlet 34. The mud accumulated on the rear end wall 46 is guided into the mud guiding groove 37 and moved in the mud guiding groove 37 owing to its capillarity. Accordingly, the mud can be moved down along the mud guiding groove 37 and smoothly dropped to the ground, thus preventing the clogging of the exhaust outlet 34 with the mud on the rear end wall 46.

Abstract: In a muffler which includes an outer tube which configures an outer wall, an inner tube provided in the outer tube and having punching holes formed therein, and a sound absorbing material filled between the outer tube and the inner tube, and which is attached to an exhaust pipe for exhausting exhaust gas from an engine, the number of punching holes at portions of the inner tube which have a great length to the outer tube is set greater than the number of punching holes at portions of the inner tube which have a small length to the outer tube in comparison with the portions having the great length.

Abstract: A vehicle, such as a motorcycle, can include an engine, an exhaust pipe, and a silencer. The silencer can include a main body and first and second pipes. An upstream end of the first pipe can be connected to the exhaust pipe, and be provided in the main body. The second pipe can be provided apart from the first pipe on the downstream side of the first pipe, coaxially with the first pipe, and extending through a downstream lid of an outer tube of the main body. The downstream portion of the first pipe can have an inner diameter that gradually decreases from the upstream side toward the downstream end. The upstream end of the second pipe can be provided in the main body and have a larger inner diameter than the inner diameter of the downstream end of the first pipe.

Abstract: A motorcycle includes a spark arrester having an increased surface area without any undue increase in the length of a silencer or the width of the motorcycle. The motorcycle includes a rear wheel and a silencer provided on a side of the rear wheel. The silencer includes an outer tube and a spark arrester which is tubular and is disposed inside the outer tube, the longitudinal axis of the spark arrester being oriented in a longitudinal direction of the outer tube. In a sectional plane which is perpendicular or substantially perpendicular to the longitudinal direction of the outer tube and the spark arrester, the outer tube has an outside dimension in a height direction greater than an outside dimension of the outer tube in a lateral direction, and the spark arrester has an outside dimension in the height direction greater than an outside dimension of the spark arrester in the lateral direction.

Abstract: Disclosed are apparatus and methodology for reducing noise and wear in a flapper configured exhaust tip for a marine exhaust system. A metallic flapper is located at an end portion of an exhaust tip of the exhaust pipe. An elastomeric flapper assembly is provided covering the exhaust tip and includes a lip portion configured to provide noise reduction by functioning as a stop for a tip portion of the metallic flapper. The metallic flapper is positioned such that a tip thereof contacts the elastomeric flapper assembly rather than the metallic exhaust pipe. Such contact with an elastomeric flapper assembly reduces noise previously produced by flapper contact with the hot exhaust pipe.

Abstract: A vehicular muffler is configured and arranged to smoothly introduce exhaust gas into a sound-absorbing material disposed inside of an outer case which has a plurality of relatively short inner sleeves therein. The muffler includes a porous plate which is disposed inside of the outer case, and which is connected to an exhaust pipe, and the porous plate is operatively connected to an outlet pipe which discharges an exhaust gas to the outside environment through an opening formed in an outlet side of the outer case. In one embodiment, the inner sleeves are arranged substantially parallel to each other, and are fluidly connected to a joint exhaust feed pipe disposed inside the outer case. The inner sleeves are connected to the outlet pipe on the outlet side of the outer case.

Abstract: An exhaust-pipe structure for a saddle-ride type vehicle includes expansion paths each having a capacity appropriate for the output capacity of a corresponding cylinder. A front exhaust pipe and a rear exhaust pipe extend from a front cylinder and a rear cylinder constituting a V-type engine, respectively. A silencer is connected to rear end portions of the front and rear exhaust pipes. As expansion chambers, the silencer is provided with a lower first chamber led from the front cylinder and an upper first chamber led from the rear cylinder. A protruding space protruding from the lower first chamber is formed so that the capacity of the lower first chamber led from the front cylinder is larger than the capacity of the upper first chamber led from the rear cylinder.

Abstract: An exhaust system for a straddle-type vehicle, such as a motorcycle, which achieves miniaturization and also provides a reduced noise output. The exhaust system is connectable to an engine of an associated vehicle and includes an exhaust pipe and a silencer. The silencer comprises an outer housing and an inner core accommodated in the outer housing. A sound absorbing material is arranged on an outer surface of a side wall of the inner core in a manner to come into close contact therewith. An air space is provided between an outer surface of the sound absorbing material and an inner surface of the outer housing.

Abstract: An exhaust device for a straddle type vehicle allowing a compact design while still satisfying the sound deadening characteristic requirements is provided. The exhaust device for a straddle type vehicle comprising: an exhaust pipe that is connected to an engine; a silencer that is connected to the exhaust pipe wherein the exhaust pipe is provided with a Helmholtz resonator, and the Helmholtz resonator is filled with a sound absorbing material. The Helmholtz resonator is formed with an opening that communicates with the inside of the exhaust pipe. The opening is formed in a place where the sound pressure in the exhaust pipe is high during the operation of the engine.

Abstract: An exhaust muffler (1) for an exhaust system of an internal combustion engine, especially of a motor vehicle, includes two front-side end panels (2) facing away from each other, a circumferential jacket (3) closed in the circumferential direction, at least one exhaust muffler insert (4), with at least one inlet pipe (5) and with at least one outlet pipe (6). At least one of the pipes (5, 6) extends through the jacket (3) into the interior (8) of the exhaust muffler and is fastened to the jacket (3). Manufacture can be simplified if the pipe (5, 6) extending through the jacket (3) has a cone (10) at its inner end, if the exhaust muffler insert (4) has a countercone (11) and if the cone (10) meshes with the countercone (11).

Abstract: An exhaust device for an engine cam include a flow rectifying device for rectifying a flow of an exhaust gas. The flow rectifying device is disposed in an upstream end of an inner pipe, and comprises protrusions projecting inwardly. The exhaust gas engaging the flow rectifying device has passed through a curved portion of the inner pipe. The inner pipe also includes a muffler having a plurality of vent holes disposed in an inner portion thereof, and an outer pipe surrounding the inner pipe, defining an angular chamber therebetween.

Abstract: A muffler apparatus for a vehicle, may include a muffler housing; baffle plates that are disposed in the muffler housing and divides an internal space of the muffler housing; an intake pipe that is supported by at least one of the baffle plates and takes in exhaust gas; and an exhaust pipe that is supported by at least one of the baffle plates and takes in the exhaust gas discharged from the intake pipe and discharges the exhaust gas outside the muffler housing, and of which a pipe line of the exhaust pipe circulates through the internal space of the muffler housing.

Abstract: A system for reducing an acoustic load of a fluid flow includes a first pipe. The first pipe includes a first end and a second end and a first aperture and a second aperture, the first and second apertures being intermediate the first and second ends. A second pipe includes a first end and a second end and a third aperture intermediate the first and second ends. The second pipe is connected at its first end to the first pipe at the first aperture. A bypass pipe includes a first end connected to the second aperture of the first pipe and a second end connected to the third aperture of the second pipe. A method of reducing an acoustic load of a flow in a standpipe connected to a first pipe configured to carry a main flow includes providing a bypass flow from the first pipe to the standpipe.

Abstract: A motorcycle has a muffler 40, a muffler cover 50 for covering a part of a side surface (outer peripheral surface) of the muffler 40 and an end cap 60 for covering the muffler 40 from a rear side thereof. The end cap 60 is separately formed from the muffler cover 50 and disposed away from the muffler cover 50. The muffler cover 50 is mounted on the muffler 40 in a manner such that a central axis of the muffler cover 50 is offset from a central axis of the muffler 40 in a radial direction.

Abstract: A marine muffler comprises an elongate cylindrical housing having an inlet and an outlet and defining an internal volume partitioned, by an angularly disposed internal baffle, into a lower chamber in communication with the inlet and an upper chamber in communication with the outlet. A vertically disposed duct is insertably secured to the baffle to allow exhaust gas and exhaust cooling water to flow from the lower inlet chamber to upper outlet chamber. The exhaust duct may preferably be further adapted with internal structure forming a plurality of individual flow conduits or passages. The duct is preferably positioned such that a plurality of flow passage inlets are positioned in proximity to the lower cylindrical housing wall, with flow passage outlets positioned in proximity to the upper housing wall. The lower duct wall may further be adapted with sidewall apertures for improving exhaust flow dynamics therethrough.

Abstract: Disclosed is an exhaust system (100) for an internal combustion engine, comprising a first exhaust train that is provided with a penetrable first muffler (120), especially a rear muffler, and at least one second exhaust train which encompasses a second penetrable muffler (122), particularly a rear muffler. The structure of the first muffler (120) differs from that of the second muffler (122).

Abstract: The present invention relates to a balance pipe assembly for a vehicle exhaust system including at least a pair of exhaust pipes or pipe shaped portions, and a further pipe or pipe shaped portion extending between the exhaust pipes or pipe shaped portions so as to act as a balance pipe. The assembly further includes at least one of the exhaust pipes or pipe shaped portions including means adapted to reduce the pressure of exhaust gasses passing there through at a position downstream of the balance pipe or pipe shaped portion.

Abstract: A housing for a flue gas unit is provided that includes a closed jacket and two end walls as well as an insert with inlet pipe an outlet pipe and retaining walls, wherein one of the pipes exits from the housing jacket radially. The housing jacket is cut out around the one pipe, the cutout is closed by a concave closing panel adapted to the shape of the cutout, and the closing panel has an opening for the radial pipe end.

Abstract: A support structure for an exhaust pipe includes left and right side frames disposed on a lower side of a rear floor and a back panel extending downward from the rear floor joined to rear end portions of the side frames. Reinforcing plates join the back panel on a vehicle rear side in positions facing the rear of the side frames. Stays extending in a rearward direction mount to the respective reinforcing plates and support a bumper member. A muffler disposed below the rear floor and on a front side of the back panel or an exhaust pipe connected thereto, is supported on a vehicle body by a hanger rubber. A flange portion that is formed with a reinforcing plate extends rearwardly and perpendicularly therefrom. A hanger rubber mounts to the flange portion to support the muffler or exhaust pipe.

Abstract: A muffler for a vehicle is disposed in a channel for discharging exhaust gas from the engine. The muffler uniformly reduces all of a flow-induced noise, a high-frequency noise, and a low-frequency booming noise generated by the exhaust gas passing through the channel, and maximize effect of reducing the noises to keep the vehicle silent and comfortable.

Abstract: An exhaust system for a motorcycle engine including a header having an upstream end adjacent a combustion chamber of the engine and having a downstream end opposite the upstream end. The exhaust system includes a catalytic converter positioned downstream of the combustion chamber and configured to improve the emissions quality of exhaust gases discharged from the combustion chamber. The exhaust system further includes a perforated section at least partially defining an exhaust passageway, the perforated section disposed adjacent the downstream end of the header. A resonator chamber is in fluid communication with the perforated section. The resonator chamber is configured to allow expansion of the exhaust gases in the exhaust passageway through the perforated section.

Abstract: One embodiment of the invention includes a product including a fuel-cell exhaust diffuser; an air funnel; and at least two exhaust tubes attached to the diffuser.

Abstract: A vehicle (1) is provided with an exhaust pipe (2) extending from an engine mounted in the front part of the vehicle to a branch part (24) in the rear part of the vehicle, and right and left branch pipes (25, 26) extending from the branch part to mufflers (5, 6) on both right and left sides. The branch part (24) is arranged so as to be offset to the side of either one muffler (5) of the right and left mufflers with respect to the center in the vehicle width direction; the exhaust pipe has an upstream part (2, 21) laid linearly to a bend part (22) positioned in the center in the vehicle width direction near the rear end of a fuel tank, and an oblique part (23) laid slantwise from the bend part toward the branch part; and the length of the branch pipe (25) having a longer distance to the muffler is approximately equal to the length of the oblique part (23).

Abstract: A muffler for efficiently reducing noise. Front side exhaust pipes and rear side exhaust pipes extend from front cylinders and rear cylinders, respectively, of a V-type water-cooled 4-cylinder engine and are operatively connected to a catalyst chamber disposed below a crankcase. The catalyst chamber is connected to an exhaust chamber located to the rear thereof in which exhaust gas is expanded. An outlet pipe laterally projects from a lateral surface of a rear end portion of the exhaust chamber and is connected to a front pipe projecting from the lateral surface of the front portion of a muffler. The front pipe is transversely inserted into the muffler to increase a cross-section ratio, thereby efficiently reducing noise.

Abstract: A muffler for a vehicle, such as a scooter type motorcycle, comprises an inner tubular member and an outer tubular member. An inner surface of the outer tubular member faces an outer surface of the inner tubular member. A ring shaped or annular member is positioned between the outer surface of the inner tubular member and the inner surface of the outer tubular member. The annular member has a substantially hollow cross section and is elastically deformable in a direction perpendicular to a longitudinal axis of the inner tubular member and the outer tubular member.

Abstract: An exhaust outlet 34 is formed at the center of a rear end wall 46 of a tail cap 21 closing a rear end opening of a muffler body 20, and a tail pipe 30 is connected at its rear end to the exhaust outlet 34. The exhaust outlet 34 is formed through a tail pipe supporting member 35 mounted on the rear end wall 46. The tail pipe supporting member 35 is formed with an annular mud guiding groove 37 opening rearward around the exhaust outlet 34. The mud accumulated on the rear end wall 46 is guided into the mud guiding groove 37 and moved in the mud guiding groove 37 owing to its capillarity. Accordingly, the mud can be moved down along the mud guiding groove 37 and smoothly dropped to the ground, thus preventing the clogging of the exhaust outlet 34 with the mud on the rear end wall 46.

Abstract: A noise reduction structure for a hybrid vehicle in which a cover covers at least part of an air intake system connected to an engine capable of giving power to a driving wheel, an exhaust muffler constituting part of an exhaust system connected to the engine, and an electric motor capable of giving power to the driving wheel. When at least part of the air intake system, the exhaust muffler constituting part of an exhaust system, and the electric motor is covered with the common cover, heat generated by the exhaust muffler is prevented from affecting the electric motor. The rotational axis of the electric motor extends in a longitudinal direction of a body frame and is disposed forwardly of the central position of the exhaust muffler extending in the longitudinal direction.

Abstract: An exhaust system for a vehicle features a pipe finisher including an inner sleeve. The inner sleeve has a reduced diameter portion spaced upstream from a downstream end of the inner sleeve. An exhaust pipe disposed in the inner sleeve, the exhaust pipe including a radially outward extending projection downstream of the reduced diameter portion of the inner sleeve.

Abstract: A motorcycle having a tail pipe formed from a pair of branch pipes that branch from a main pipe and that ensures a sound absorbing effect. A muffler has a casing that surrounds a rear section of an exhaust pipe, and a sound absorbing material that is filled between the casing and the rear section of the exhaust pipe. The rear section of the exhaust pipe includes a main pipe that is connected to the exhaust pipe and that extends to the rear, and first and second branch pipes that are connected to and branch from the main pipe and extend to the rear. A cross sectional area of the casing, when viewed from an exhaust gas flow direction becomes larger as the casing extends toward the branch pipe side.

Abstract: The diffuser can be used at an end of a vehicle exhaust system. The diffuser can have a generally hollow body with an inlet for receiving exhaust gasses from a substantially vertically-extending component of the vehicle exhaust system, and a substantially flat outlet grate through which the exhaust gasses are to be released to the atmosphere, the outlet grate being configured and adapted for use in a roof of the vehicle, in an aligned position therewith, with the hollow body of the diffuser positioned inside the vehicle and below the outlet grate.

Abstract: A muffler structure in which a subassembly formed by fixing an inner cylinder and a separator is not welded to the outer cylinder in welding an overlapping portion of a sheet metal wrapped around the subassembly. A subassembly is formed by fixing an inner cylinder and a separator. An outer cylinder is formed by first wrapping a sheet metal around the subassembly and next welding an overlapping portion of the sheet metal. The subassembly is formed with a recess opposed to a welded portion of the outer cylinder.

Abstract: A double-flow exhaust system for an internal-combustion engine, having exhaust-gas-carrying pipes and at least one muffler and catalyst housing. A separate end muffler is provided for each exhaust line, on which the end mufflers are both fluidically connected by at least one preferably mountable connection pipe.

Abstract: A sheet metal is rolled double to form a cylinder having an inner plate 2 and an outer plate 3, and form an overlapped portion 4, with their circumferential end portions 2a and 3a crossed in the circumferential direction. Between the inner plate 2 and the outer plate 3, a plurality of line grooves 5 are formed to extend outward of an outer tube 1, with their tip end portions facing with each other to be apart from each other by a predetermined distance from a peripheral edge of one of the inner plate and outer plate, and these line grooves 5 are arranged in parallel with each other along a longitudinal direction of the outer plate 3. And, at least one portion of the overlapped portion positioned between the neighboring line grooves is joined by welding W.

Abstract: A muffler structure capable of suppressing generation of abnormal noise in the muffler even when the outer and the inner tubes expand thermally. Provided is a double-pipe muffler structure including an inner tube and an outer tube. In the muffler structure, an annular front step portion and an annular rear step portion are formed in the inner tube, while the step portions is brought into contact, from inside, with the outer tube and thus are supported by the outer tube. The outer tube supports the front and the rear step portions by being brought into close contact with the step portions partially and elastically.