JPH0726527B2 - Engine exhaust muffler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an exhaust muffler for an engine mounted on a jet-propelled small boat, a motorcycle, and various other vehicles.

<Prior Art> For example, in a conventional jet-propelled small watercraft, in order to achieve the muffling effect of the exhaust gas, as is clear from the schematic diagram in FIG. 8, a water-cooled type watercraft installed in the hull (1). A long exhaust pipe (3) is led forward from an exhaust manifold (not shown) of the engine (2), while a water turbo box (exhaust muffler) functions as an expansion chamber at the bow of the boat body (1). ) (4) is stored and installed, and the front end opening of the exhaust pipe (3) is exposed to the water turbo box (4) so that the exhaust gas from the engine (2) becomes water after the engine is cooled. Together with being introduced into the water turbo box (4), the water is discharged from the top surface of the box (4) into the atmosphere through the discharge pipe (5).

That is, the exhaust gas of the engine (2) and its cooling water are
By performing mixed flow and heat exchange inside the exhaust pipe (3), the back pressure of the exhaust gas is reduced and at the same time, by further expanding and depressurizing the exhaust gas in the water turbo box (4), It achieves the effects of heat absorption and noise reduction from the surroundings.

<Problems to be Solved by the Invention> However, according to such a configuration, in order to prevent the output of the engine (2) from being reduced, the exhaust pipe (from the exhaust manifold to the water turbo box (4) ( Since 3) forms a generally linear exhaust passage, it is difficult to efficiently attenuate the exhaust sound unless the volume of the entire exhaust passage is set large. Due to the large size and weight of the exhaust pipe (3), the hull (1) has a limited size.
When designing, the overall weight balance and other factors will limit the design.

In this respect, motorcycles and other land vehicles do not have the water turbo box (4) as in the above-mentioned watercraft, and the water after engine cooling is not used for muffling the exhaust gas. ), It is necessary to make the volume even larger, or it is necessary to adopt an exhaust bypass structure by a complicated partition inside, which means that the vehicle body becomes large and heavy, and the output of the engine mounted on it. It also causes a drop.

Further, in the above-mentioned configuration of FIG. 8, it is also difficult to completely discharge the cooling water from the water turbo box (4). If this is left in the interior for a little bit, or if the cooling water is intentionally stored in order to increase the heat gradient of the exhaust gas, the cooling water becomes steam due to the exhaust heat,
Under the influence of back pressure and pulsation of exhaust gas, the water flows backward from the water turbo box (4) toward the engine (2) and penetrates into the cylinder to cause a start failure of the engine (2), or a crankshaft shift. There is a risk of rusting the bearings and other parts. The above-mentioned boat capsizes relatively easily, but the same problem will occur at that time.

As a countermeasure for such a problem, Japanese Patent Laid-Open No. 1-175597 is known. And, with this, water after engine cooling is not mixed with exhaust gas, and water jackets (23) (24) are provided around the exhaust pipe (17),
Insert the cooling water supply port (31) of the cooling water supply pipe (30) extended from the jacket (23) (24) into the jacket (2
3) It is connected to the outer case (28) of the expansion type muffler (18), which is separate from (3) and (24), so that exhaust gas can be cooled by cooling water from the outside.

However, in such a configuration of cooling from the outside, since a large amount of cooling water is required, the volume of the water jacket (23) (24) must be increased, and the machining cost becomes expensive, and High precision assembly is also difficult.
On top of that, in order to make it larger and heavier, it is also constrained by its design when mounted on a limited size ship (11), and it causes trouble even if it receives a slight vibration or shock. It will be.

<Means for Solving the Problem> The present invention intends to improve such a problem, and as a structure of an exhaust muffler useful for that purpose, a closed-type tubular container having a constant length forming an expansion chamber and the expansion chamber are provided. The first punching metal, which is attached to the body wall surface and the rear wall surface of the expansion body through the first sound absorbing material, is integrated with the front wall surface of the expansion chamber. A pair, a guide vane for generating vortex attached to the opening edge of the inlet, and a fixed length of cantilever that does not reach the rear wall from the front wall of the expansion chamber. A relatively thin cylindrical second punching metal that is fixedly supported so as to communicate with each other, and a thick cylindrical third punchin that is wound around the body wall surface of the second punching metal via a second sound absorbing material and is integrated. In order to form a muffling chamber inside the expansion chamber by covering the drum metal and the wall surface of the third punching metal with a constant gap, a constant length that does not reach the rear wall from the front wall of the expansion chamber. And a partition cover cylinder fixedly supported in a cantilevered state, the exhaust gas entering the expansion chamber from the inlet is swirled by the guide vanes, and collides with the rear wall surface in the expansion chamber. The main feature is that it is set to be turned and can be led out from the outlet through the muffling room.

<Embodiment> The specific construction of the present invention will be described in detail below with reference to the illustrated embodiment. FIG. 1 shows an overall outline of a jet-propelled small boat, and (10) is a fiber-reinforced plastic (FRP). )
It is a generic name for a boat made of a material such as a hollow closed type float structure. The engine room (11) is partitioned in the first half of the hull, while the upper surface of the second half is also operated. It is formed as a floor deck (12) for people to stand on. However, on the upper surface of the rear half of the hull (10), a seat for the operator to sit may be installed instead of the floor deck (12).

In the engine room (11), a water-cooled two-cycle engine (13), a fuel tank (14), etc. are stored and installed, and the engine (13) propels the jet through the propulsion shaft (15). Equipment (water jet pump)
(16) is driven so that propulsive force is applied to the hull (10).

In other words, the propulsion shaft (15) extends below the floor deck (12) along the center line of travel of the boat (10), and the front end of the propulsion shaft (15) extends through the clutch (17) to the engine. An impeller (18) is integrally and rotatably attached to the rear end of the propulsion shaft (15) while being integrally connected to a crankshaft (13) (not shown). (1
Reference numeral 9) is a water absorption duct as a pump case for receiving the impeller (18), which is formed below the floor deck (12) and whose front portion is a hull (1
0) It has an opening on the bottom.

When the propulsion shaft (15) is rotationally driven by the engine (13), water is sucked into the water absorption duct (19) by the impeller (18), and the water is sucked backward in the water absorption duct (19). It is accelerated and pressure-fed to the hull (10) by the steering nozzle (20) opening at the tail of the hull (10).
Will move forward. Needless to say, the operator can remotely control the steering nozzle (20) and swing it to the left and right to steer the boat body (10).

(21) is an exhaust pipe that is led out from the cylinder block of the engine (13) to the lower front side through an exhaust manifold, and (M) is an exhaust muffler that is communicatively connected near the end of the exhaust pipe. The exhaust gas is stored in the room (11), and exhaust gas is emitted from the muffler (M) to the atmosphere via the emission pipe (22).

In this regard, in the figure, although the exhaust pipe (21) is led obliquely downward from the engine (13) toward the front lower side, the discharge pipe (22) is installed in the front part of the boat body (10). On the contrary, the exhaust pipe (21) is extended from the engine (13) downward and rearward so that the discharge pipe (22) is installed at the rear part of the boat (10) and the tail of the boat (10) is reached. Of course, it may be decided to discharge the exhaust gas from the.

In any case, piping (not shown) is provided so that the cooling water of the engine (13) can be taken in from the high pressure portion of the water absorption duct (19) of the jet propulsion device (16), and the engine (13 ) Is cooled with water, and the cooling water after the action is introduced into the exhaust pipe (21) and the muffler (M), and the discharge pipe (22) is discharged together with the exhaust gas.
It is supposed to be released from.

In the present invention, the exhaust muffler (M) is made of stainless steel, light alloy or the like as shown in FIGS.

That is, the reference numeral (23) in the same figure is a closed type container tube having a constant length which forms the expansion chamber (a), and the body wall surface is a pipe material in a sliced state with a circular cross section, or a three-dimensionally bent three-dimensional pipe material. A pair of separate plate materials, which are made up of the converted plate material and serve as the front and rear wall surfaces, are assembled and fixed by means such as spot welding. However, the wall surface of the expansion chamber (a) may be formed to have an elliptical cross section, and thereafter, the wall surface may be curved as a convex curved surface or a concave curved surface, as is apparent from the modification of FIG. it can.

(24) is the first punching metal with a large number of small holes (25) which are scattered, and is made of glass wool, rock wool,
Through the first sound absorbing material (26) such as felt, the exhaust wall sound is attenuated by being attached integrally to the trunk wall surface and the rear wall surface in the expansion chamber (a) with a generally U-shaped cross section. It is supposed to work. In that case, as suggested from FIG. 3, the first sound absorbing material (2
6) and the installation of the first punching metal (24) can be omitted.

Further, (27) and (28) are the longitudinal center lines (O-
O) is a top and bottom distribution arrangement state, and is a pair of exhaust gas inlet and outlet formed respectively on the front wall surface of the expansion chamber (a), both of which are circular in cross section. (23) is located on the diameter line or on the major axis of the barrel (23) having an elliptical cross section.

Reference numeral (29) is a guide vane for generating vortex attached to the opening edge of the inlet port (27), and the exhaust gas entering the expansion chamber (a) from the inlet port (27) is swirled and swirled. The heavy cooling water mixed with the exhaust gas is shaken off and separated by the swirling centrifugal force, while the negative pressure action also occurs at the swirling center, so that the exhaust gas is directed to the rear wall surface of the expansion chamber (a). Collide straight ahead and vigorously, and pull out the outlet (2
It is possible to change the direction in the form of a smooth U-turn to the bottom where 8) exists.

In this respect, in FIGS. 3 and 4, to the inlet (27) on the front wall surface,
A separate introduction guide tube (30) that also functions as a hose joint is fitted and fixed in a penetrating state, and the guide tube (30)
Cut the rear end of the opening facing the expansion chamber (a) and twist a plurality of the split pieces into a spiral spiral shape in the overall one direction, so that the guide pieces (2
It is set so that it can function as 9). Also, the fifth
In the modified example shown in the figure, the introduction guide tube (30) is used as an extremely short mouthpiece, which is independent from the hose joint, and a guide vane (29) made of a split piece similar to the above is processed at the rear end of the opening. There is.

However, in installing the guide vanes (29), as long as the above-mentioned action can be given to the exhaust gas, as shown in another modified example of FIGS. 6 and 7, the opening of the introduction port (27) itself. The edge part is made especially thick, or the inlet (27) is fitted with a separate ferrule to make it thicker, and the inner wall surface of the thick opening is provided with a plurality of lead grooves. It may be determined that the lead groove is formed so as to function as the guide vane (29) by engraving into a spiral spiral shape in one direction. In any case, it is preferable that the twisting angle in one direction that creates the spiral spiral state is selected to be a value that does not give resistance to the exhaust gas.

On the other hand, (31) is a relatively thin cylindrical second punching metal which is integrally and inwardly projected rearward from the front wall surface of the expansion chamber (a) in a mating communication state with the outlet (28). Needless to say, the body wall surface is provided with a large number of small holes (32), but this is a fixed length (L1) that does not reach the rear wall surface of the expansion chamber (a), So to speak, it is in a cantilevered, horizontal frame. That is, a certain amount (S) of space is maintained between the overhanging rear end portion of the second punching metal (31) and the rear wall surface of the expansion chamber (a).

In that case, in FIGS. 3 and 4, the second punching metal (31) is fitted into the lead-out port (28) in a penetrating state so as to be integrated, and is exposed to the front from the front wall surface of the expansion chamber (a) and is small. The overhanging front end of the hole (32), which is not opened, is determined so as to also function as a hose joint. However, as shown in the modified example of FIG. 5, the second punching metal (31) thereof is provided.
Of course, it may be formed separately from the hose joint so as to project only from the front wall surface of the expansion chamber (a) toward the rear.

(33) is on the body wall of the second punching metal (31),
It is also a thick cylindrical third punching metal that is wound and integrated through the second sound absorbing material (34) such as glass wool, rock wool, felt, etc., and has a large number of small holes (35 Needless to say The length of the expansion chamber (a) that integrally projects rearward from the front wall surface of the expansion chamber (a) is also set to be equal to the constant length (L1) of the second punching metal (31).

Further, (36) defines a muffler chamber (b) inside the expansion chamber (a), and the exhaust gas accelerated and diffused by the guide vanes (29) is directed to the rear wall surface of the expansion chamber (a). It is a partition cover cylinder for preventing the first punching metal (31) (33) and its second sound absorbing material (34) from directly flowing into the interior of the partition cover cylinder before the collision. The cylindrical shape is slightly thicker than the punching metal (33) and is also integrally and inwardly projected rearward from the front wall surface of the expansion chamber (a).

That is, a slight fixed amount (D) of space is maintained between the body wall surface of the partition cover cylinder (36) and the body wall surface of the third punching metal (33). The small hole (35) of the (33) is not blocked by the partition cover cylinder (36).

Moreover, regarding the length (L2) of the partition cover cylinder (36) protruding rearward from the front wall surface of the expansion chamber (a), this is determined by the constant length (L2) of the second and third punching metals (31) (33). L
Although it may be set equal to 1), the exhaust gas accelerated and diffused by the guide vanes (29) is prevented from directly flowing in from the body wall surface of the third punching metal (33). The partition cover cylinder (36) is limited as long as it can be guided to collide with the rear wall surface of the expansion chamber (a).
As shown in Figs. 3 and 5, punching metal (3
1) A length (L2) shorter than the constant length (L1) of (33) by a fixed amount (W) is preferably projected from the front wall surface of the expansion chamber (a) rearward.

By covering and colliding with the rear wall surface of the expansion chamber (a), U
The exhaust gas, which has been turned in a turn shape, can be more smoothly flowed into the second and third punching metals (31) (33) from the rear, and the depressurizing and muffling effects of the exhaust gas can be beaten. is there.

In any case, the cylinder wall surface of the partition cover cylinder (36) is in close contact with the cylinder wall surface of the expansion chamber (a) at its lower end position without a gap, while the upper end position is also the longitudinal center of the instrument cylinder (23). It is biased on or below the line (OO). Therefore, the cooling water separated by the guide vanes (29) passes through the mutual gap (D) between the partition cover cylinder (36) and the third punching metal (33) and the center of the second punching metal (31) and From the outlet (28), it is surely discharged as a mist.

<Operation> According to the above configuration, the exhaust gas from the engine (13) is indicated by the solid arrow (x) in FIGS. 3 and 5, and the cooling water after engine cooling is indicated by the dotted arrow (y) in both figures. ), In a mixed flow state of the both, it is introduced from the exhaust pipe (21) to the exhaust muffler (M), and in the process, heat exchange between the exhaust gas and the cooling water is performed, and the heat gradient of the exhaust gas is correspondingly increased. However, as soon as they are introduced into the muffler (M), they are first expanded in the expansion chamber (a), so that a primary sound deadening effect is achieved.

At the time of introduction into the expansion chamber (a), a guide vane (29) for generating a swirl is attached to the inlet (27) of the front wall surface that defines the expansion chamber (a). In, the exhaust gas and the cooling water swirl and swivel together with each other, and the cooling water heavier than the exhaust gas is shaken off and separated by the centrifugal force to form the first sound absorbing material (26) in the expansion chamber (a). The result is penetration.

On the other hand, due to the swirling and swirling motion, a negative pressure action is generated in the central portion of the guide vane (29) in the expansion chamber (a), so that the exhaust gas separated by the cooling water splashing is separated from the acceleration state. It goes straight ahead, and when it collides with the rear wall surface of the expansion chamber (a), the direction is changed to a downward U-turn,
Subsequently, the second and third punching metals (31) (33) and the second sound absorbing material (34) that form the sound deadening chamber (b) will flow into the inside of the second sound absorbing material (34) very smoothly from the rear, and the secondary The muffling effect is achieved. Then, finally, it is discharged from the outlet port (28) through the discharge pipe (22) into the atmosphere.

In that case, the partition cover cylinder (36) is built in the lower position of the expansion chamber (a), and the second and third punching metal (31) forming the silencing chamber (b) is formed inside the partition cover cylinder (36). ) (33) and the second sound absorbing material (3
4) is stored and installed, so the above guide vanes (2
The exhaust gas accelerated and diffused by 9) inevitably collides with the rear wall surface of the expansion chamber (a), detours in a U-turn shape, and then into the muffling chamber (b), and surely from behind. Therefore, the exhaust gas will not flow in, and therefore the exhaust gas will not be subject to resistance, and the output of the engine (13) will not decrease.

Further, the lower end position of the partition cover cylinder (36) is in close contact with the cylinder wall surface of the expansion chamber (a), and the cylinder wall surface of the third punching metal (33) covered by this and the partition cover cylinder (36). ), A certain amount (D)
Since the gap between the 2nd punching metal (31)
And can be completely discharged from the outlet (28),
There is no risk of backflow in the direction of the engine (13).

In particular, if the exhaust muffler (M) as described above is formed to be long and the volumes of the expansion chamber (a) and the muffler chamber (b) are set to be large, the length of the exhaust pipe (21) is significantly increased. It can be shortened, and the partial extension of the exhaust pipe (21) eliminates the need to form an expansion chamber (so-called expansion champer), which makes it suitable for use on small boats of limited size and weight. It can be said to be more beneficial.

The exhaust muffler (M) of the present invention can be applied not only to the above-mentioned watercraft but also to motorcycles and other various land vehicles, and in that case, the cooling water can be separated. Since it is not necessary to consider the action, a pair of the exhaust gas inlet port (27) and the outlet port (28) may be formed on the front wall surface of the expansion chamber (a) so as to be laterally distributed.

Incidentally, when the exhaust muffler (M) according to the present invention is used for the above-mentioned boat, for example, the length of the barrel (23) -about 250 m.
m, same diameter-about 150 mm, overhanging length of second and third punching metal (31) (33) (L1) -about 130 to 160 mm, diameter of third punching metal (33) -about 50 mm, partition cover cylinder (36) diameter-about 60mm, the same length (L2) -about
90 to 100 mm, the diameter of the inlet port (27) and the outlet port (28) -all of which will be about 40 mm.

<Effects of the Invention> As described above, in the exhaust muffler (M) of the present invention, due to its constitution, the closed-type container tube (2) having a constant length that forms the expansion chamber (a) is formed.
3), a first punching metal (24) that is attached to the body wall surface and the rear wall surface in the expansion chamber (a) via the first sound absorbing material (26), and the expansion chamber (a) Introducing ports 27) and outlets (28), each of which has openings formed on the front wall of the
, A guide vane (29) for generating a vortex attached to the opening edge of the inlet (27), and a fixed length (L1 that does not reach the rear wall from the front wall of the expansion chamber (a)). ) Of the second punching metal (31), which is a relatively thin cylindrical punching metal (31) fixed and supported in a cantilever overhang state so as to match with and communicate with the outlet port (28). In addition, a thick cylindrical third punching metal (33) wound around the second sound absorbing material (34) and integrated with the third punching metal (33) with a constant gap (D) on the body wall surface. To cover the expansion chamber (a) with a silencing chamber (b) inside, so that the expansion chamber (a) also has a fixed length (L2) that does not reach the rear wall surface from the front wall surface. Partition cover tube (3
6) and the exhaust gas entering the expansion chamber (a) from the inlet (27) is swirled by the guide vanes (29) and the collision with the rear wall surface of the expansion chamber (a) is performed. By U
Since it is set so as to be turned and can be led out from the outlet (28) through the muffling chamber (b), when this is applied to the engine (13) mounted on the jet-propelled small boat, it is disclosed in Japanese Patent Laid-Open No. 1-175597. Although the problem of the prior art described at the beginning based on No. 8 and FIG. 8 can be completely solved and the muffling effect of the exhaust gas can be improved, the output reduction of the engine (13) and the start failure are surely prevented. There is a remarkable effect that can be.

That is, according to the present invention, the exhaust gas and the water after engine cooling are caused to flow together from the exhaust pipe (21) of the engine (13) into the exhaust muffler (M), so to speak, the exhaust gas is water-cooled in the exhaust passage. Although it is a system, it reduces back pressure and achieves sound deadening effect, but nevertheless surely prevents backflow of cooling water toward the engine (13) and troubles associated therewith. can do.

In the present invention, the expansion chamber (a) of the exhaust muffler (M) is covered.
A guide vane (29) for generating a vortex is fixedly attached to the inlet (27) of the front wall forming the exhaust gas, whereby exhaust gas and cooling water together in the expansion chamber (a) As soon as they entered, both of them made a spiral motion by themselves,
The centrifugal force causes the cooling water to be splashed and diffused separately from the exhaust gas, while the swirling exhaust gas is accelerated by the negative pressure action at its center, and the rear wall surface of the expansion chamber (a) is accelerated. The second and third punching metals (31) (33) and the second sound absorbing material (3) which collide straight to and are turned downward in a U-turn shape to form the sound deadening chamber (b).
This is because it will flow smoothly into the interior of 4) from the rear.

The exhaust sound is efficiently attenuated step by step by the expansion chamber (a) and the muffler chamber (b), and no resistance acts on the exhaust gas flowing in the exhaust muffler (M). The output performance of (13) can be remarkably improved, and the cooling water together with the exhaust gas can be reliably discharged from the outlet (28) of the exhaust muffler (M) through the discharge pipe (22). There is no worry of starting failure due to backflow to the engine (13).

The guide vane (29) itself does not rotate, and is fixedly attached to the front wall surface of the expansion chamber (a), and the muffling chamber (b) is provided at the lower position in the expansion chamber (a). It can be said that the second and third punching metals (31) (33) to be formed, the partition cover cylinder (36), and the like are housed and installed in order to achieve the above effects organically.

Also, compared to the above-mentioned Japanese Patent Laid-Open No. 1-175597, the required structure as a whole is remarkably simple and the mass production effect can be expected to the maximum, and as a small and lightweight exhaust muffler (M), There is also an effect that it can be mounted and used extremely easily and without restrictions on boats of limited size and weight. The present invention can be directly applied to an air-cooled on-board engine for motorcycles and other various land vehicles. This is because, when the present invention is mounted on a land vehicle and used, all the operational effects other than the discharge of the cooling water can be achieved in exactly the same manner.

In particular, if the construction of claim 2 is adopted, the second and third punching metals (31) (33) in which the exhaust gas accelerated and diffused by the guide vanes (29) form the sound deadening chamber (b).
Exhaust gas after changing its direction into a U-turn shape while preventing the risk of inflow from the body wall surface of the vehicle immediately and inevitably inducing a straight collision with the rear wall surface of the expansion chamber (a). Can be reliably and smoothly introduced from the rear of the muffling chamber (b), and the back pressure of the exhaust gas can be more effectively reduced, and the muffling effect can be further enhanced. is there.

Further, if the configuration described in claim 3 is adopted, there is an effect that the cooling water of the exhaust gas can be completely discharged from the muffler (M) especially when used in combination with a water-cooled engine of a boat. Further, if the constructions of claims 4 and 5 are adopted, the guide vane (29) which performs the above-mentioned action is extremely easily attached to the inlet port (27) which opens to the front wall surface of the expansion chamber (a). It can be said that they can be integrated, which is very useful in mass production.

[Brief description of drawings]

FIG. 1 is an overall schematic cross-sectional view of a jet-propelled small boat to which the present invention is applied, FIG. 2 is a front view showing an exhaust muffler thereof extracted, and FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 4 is a sectional view taken along line 4-4 of FIG. 3, FIG. 5 is a side sectional view showing a modification of the present invention corresponding to FIG. 3, and FIG. 6 is a side sectional view showing a modification of the guide vane. 7 is a sectional view taken along line 7-7 of FIG. 6, and FIG. 8 is a side sectional view showing a conventional product corresponding to FIG. (23) …… Container (24) (31) (33) …… Punching metal (26) (34) …… Sound absorbing material (27) …… Inlet port (28) …… Outlet port (29) …… Guide Vane (30) …… Introduction guide cylinder (36) …… Partition cover cylinder (a) …… Expansion chamber (b) …… Silence chamber (S) (D) …… A certain amount (L1) (L2) …… Overhang Length (M) …… Exhaust muffler

Claims (5)

[Claims] 1. A closed type container tube (23) having a constant length for forming an expansion chamber (a), and a first sound absorbing material (26) on a body wall surface and a rear wall surface in the expansion chamber (a). The first punching metal (24) integrated by pasting and the inlet (27) and outlet (2) that are respectively formed with openings on the front wall surface of the expansion chamber (a) are also arranged.
8), a guide vane (29) for generating vortex attached to the opening edge of the inlet (27), and a fixed length that does not reach the rear wall from the front wall of the expansion chamber (a). A relatively thin cylindrical second punching metal (31) fixedly supported so as to be in a cantilevered projecting state (L1) and in conformity with the outlet (28), and the second punching metal (31) A thick cylindrical third punching metal (33), which is wound around the body wall via the second sound absorbing material (34) and integrated, and the body wall of the third punching metal (33) has a constant gap (D). In order to form a muffling chamber (b) inside the expansion chamber (a) by keeping and covering it, a cantilever of a fixed length (L2) that does not reach the rear wall surface from the front wall surface of the expansion chamber (a). Partition cover tube (3
6) and the exhaust gas entering the expansion chamber (a) from the inlet (27) is swirled by the guide vanes (29) and the collision with the rear wall surface of the expansion chamber (a) is performed. By U
An exhaust muffler for an engine, which is set so that it can be turned and can be led out from a lead-out port (28) via a muffling chamber (b). 2. A second punching metal (31) and a third punching metal (33) forming a sound deadening chamber (b) are formed so as to extend rearward by a certain amount (W) longer than the partition cover cylinder (36). The exhaust muffler for an engine according to claim 1, wherein: 3. An inlet port (27) is formed above the longitudinal centerline (O-O) of the barrel (23), and an outlet port (28) is formed below it. An exhaust muffler for an engine according to claim 1. 4. An introduction guide cylinder (30) which can also function as a hose joint is integrally attached to the opening edge portion of the introduction port (27), and inside the expansion chamber (a) of the introduction guide cylinder (30). By cutting the rear end of the opening facing the and twisting a plurality of split pieces in a spiral shape in one overall direction, the split pieces can function as guide vanes (29) for generating vortex flow. The exhaust muffler for an engine according to claim 1, wherein the exhaust muffler is set. 5. The opening edge portion of the inlet (27) is made particularly thick, and a plurality of lead grooves are formed on the thick inner wall surface of the opening in a spiral shape spiraling in one direction. The exhaust muffler for an engine according to claim 1, characterized in that the lead groove is set so that the lead groove can function as a guide vane (29) for generating a swirl flow.