JPH08121162A - Exhaust muffler for working machine - Google Patents

Abstract

PURPOSE: To prevent rain drops from entering an exhaust muffler and prevent pollusion due to exhaust gas. CONSTITUTION: A bent portion 56 is formed on the way of a secondary side exhaust pipe 51 standing from an exhaust muffler body 42, while an exhaust opening at its leading end is stood upward. The bent portion 56 is stood upward to an exhaust opening 53 and then bent downward. A small hole 57 is opened to a lower side of the bent portion 56. The bent portion 56 is positioned in an exhaust passage for cooling wind to a radiator 31 for an engine, and faced to a core 60 of the radiator 31 at an upstream side of the exhaust muffler body 42. Rain drops entering a secondary side exhaust pipe 51 from the small hole 57 are dropped outside the secondary side exhaust pipe 51. Exhaust gas leaking from the small hole 57 is smoothly discharged outside through the exhaust passage together with the cooling wind, so as to prevent pollusion around the noise absorbing box by the exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust muffler for an engine-driven working machine such as a compressor or a generator.

[0002]

2. Description of the Related Art FIG. 10 schematically shows an example of a conventional compressor. A soundproof box 1 is provided with a vertical partition wall 2 at the left end of the soundproof box 1, and an opening 3 is formed in the partition wall 2. Then, in the soundproof box 1, an engine 5 equipped with a fan 4 and driving a compressor body, an engine radiator 6 and a compressor oil cooler 7 which are air-cooling heat exchange devices, and an exhaust silencer exhaust gas are provided. The muffler 8 is arranged. The engine 5
Is located on the right side of the partition wall 2, and the engine radiator 6 and the compressor oil cooler 7 are located on the partition wall 2 side.
It is located between the opening 3 and the fan 4. The exhaust muffler 8 is located on the left side of the partition wall 2. The exhaust muffler body 11 of the exhaust muffler 8 is located in the lower portion of the soundproof box 1. The primary exhaust pipe 12 from the exhaust manifold of the engine 5 is connected to the exhaust muffler body 11.
Further, the secondary side exhaust pipe (tail pipe) 13 rising from the exhaust muffler main body 11 extends horizontally from the front surface of the exhaust muffler main body 11, bends in an approximately S shape, and the tip end stands vertically upward. The exhaust port 14 is located at the tip of the exhaust port.

When the compressor body is driven by the engine 5 during operation, the rotation of the fan 4 causes the engine radiator 6, the compressor oil cooler 7, and the opening 3 of the partition wall 2 as indicated by the arrow. An air flow of cooling air flowing out from the upper opening of the muffler chamber 15 on the left side of the partition wall 2 in the soundproof box 1 is generated. As a result, the engine radiator 6 and the compressor oil cooler 7 are cooled. Cooling water for the engine 5 passes through the engine radiator 6 and is cooled. Oil for lubricating and cooling the compressor body passes through the compressor oil cooler 7, and the oil is cooled. Exhaust gas from the engine 5 sequentially passes through the primary exhaust pipe 12, the exhaust muffler body 11 and the secondary exhaust pipe 13 and is exhausted from the exhaust opening 14.

By the way, since the tip of the secondary side exhaust pipe 13 on the side of the exhaust opening 14 stands substantially upward, rainwater and the like enter the secondary side exhaust pipe 13 through the exhaust opening 14, but this water is exhausted. Entering the muffler body 11 causes internal corrosion and other problems,
Black water is blown back at startup. Therefore, the secondary exhaust pipe 13 is formed with a small hole 16 for draining water.
Conventionally, the small hole 16 is formed below the end of the exhaust muffler main body 11 side which is the lowermost part of the secondary side exhaust pipe 13.

[0005]

However, in the conventional exhaust muffler 8 described above, the small hole 16 for draining water is provided in the secondary side exhaust pipe.
Since it was formed at the end of the exhaust muffler body 11 side which is the lowermost part of 13, there was the following problem. Exhaust muffler body 11
Is in the lower part 15a of the muffler chamber 15, but the lower part 15a of the muffler chamber 15 is at a position outside the exhaust passage of the cooling air,
This is the place where the flow of cooling air creates turbulence and accumulates. The small hole 16 is also located in the lower portion 15a of the muffler chamber 15. The exhaust gas of the engine 5 naturally leaks from the small hole 16, but due to the turbulent flow, the exhaust gas leaking from the small hole 16 is diffused, and soot falls in the lower portion 15a of the muffler chamber 15. Therefore, the area around the small hole 16 is easily soiled, and the small hole 16
Exhaust gas leaking from the exhaust is also discharged from the gap between the joining portions 17 of the members constituting the soundproof box 1.
17 is particularly easy to get dirty.

The present invention is intended to solve such a problem, and prevents rainwater and the like from entering the exhaust muffler main body from the secondary side exhaust pipe, and at the same time, prevents exhaust gas leaking from the secondary side exhaust pipe. It is an object of the present invention to provide an exhaust muffler for a working machine that can prevent its surroundings from becoming dirty.

[0007]

In order to achieve the above-mentioned object, the invention of claim 1 sandwiches an air-cooling type heat exchange device in a soundproof box, and has an engine on one side and a work driven by this engine. In the exhaust muffler of the working machine in which the machine body is disposed and the exhaust muffler of the engine is disposed on the other side, the exhaust opening of the secondary side exhaust pipe extending from the exhaust muffler body is disposed substantially upward, and In the middle of the pipe path from the exhaust muffler main body to the exhaust opening, a bent portion is provided in which the secondary side exhaust pipe once rises substantially upward and then bends downward, and at the bottom of this bent portion, the inside of the pipe is provided. A small hole that communicates with the outside of the pipe is opened, and the small hole of the bent portion is disposed above either the core of the air-cooling type heat exchange device or the upper wall of the exhaust muffler body.

According to a second aspect of the present invention, in the exhaust muffler of the working machine according to the first aspect of the invention, the bent portion is provided in an exhaust passage for cooling air that has passed through the air-cooling type heat exchange device. .

In order to achieve the above object, a third aspect of the present invention is such that an air-cooling type heat exchange device is sandwiched in a soundproof box and an engine and a working machine body driven by the engine are arranged on one side. In the exhaust muffler of the working machine in which the exhaust muffler of the engine is arranged on the other side, the exhaust opening of the secondary side exhaust pipe extending from the exhaust muffler main body is arranged substantially upward, and from the muffler main body to the exhaust opening. In the middle of the pipe path to reach, a slanted connection part that connects the upper pipe to the outer peripheral side of the lower pipe and is directed obliquely upward is provided, and at the lower end of this slanted connection part, between the peripheral walls of both pipes, And a communication passage communicating with the outside of the pipe, and the communication passage is disposed above either the core of the air-cooling type heat exchange device or the upper wall of the exhaust muffler body.

[0010]

In the exhaust muffler of the working machine according to the first aspect of the invention, the exhaust gas from the engine driving the working machine is discharged through the exhaust muffler. At this time, the exhaust gas passes through the secondary exhaust pipe from the exhaust muffler body and is exhausted from the exhaust opening. The exhaust opening is erected almost upward, but the rainwater entering the secondary exhaust pipe through the exhaust opening is
In the secondary exhaust pipe, the liquid temporarily accumulates in a bent portion that is recessed downward, and then falls out of the secondary exhaust pipe through a small hole at the bottom of the bent portion. This prevents rainwater from entering the exhaust muffler body. Further, the air-cooled heat exchange device between the engine and the exhaust muffler is cooled by the cooling air passing through the air-cooled heat exchange device, but the bent portion with the small holes is located below the core of the air-cooled heat exchange device or above the exhaust muffler body. The exhaust gas leaked from the small holes is quickly discharged along with the cooling air because it is arranged at a position avoiding the turbulent portion above the wall.

Further, in the exhaust muffler for a working machine according to a second aspect of the present invention, the bent portion is in an exhaust passage corresponding to a laminar flow portion of the cooling air that has passed through the air-cooling type heat exchange device and leaks from a small hole. Exhaust gas is discharged more reliably and quickly.

Further, in the exhaust muffler of the working machine according to the third aspect of the present invention, rainwater or the like that has entered the secondary side exhaust pipe from the exhaust opening is passed through the communication passage at the inclined connection portion in the secondary side exhaust pipe. Immediately flows out of the secondary side exhaust pipe. That is, since the sloping connection portion is directed obliquely upward toward the exhaust opening side, rainwater and the like flow downward along the lower side in the sloping connection portion, but the communication passage has the upper pipe on the outer peripheral side. Since it is located between the peripheral walls of the pair of connected pipes, the rainwater and the like are smoothly discharged from the communication passage. The action of the positional relationship between the inclined connection portion and the air-cooling type heat exchange device or the exhaust muffler body is the same as that of the invention of claim 1.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. Reference numeral 21 is a soundproof box, and the soundproof box 21 is a combination of a plurality of members. A vertical partition wall 22 is provided on the left side of the soundproof box 21, and a muffler chamber 23, which is a duct, is defined on the left side of the partition wall 22. The upper surface of the muffler chamber 23 has an opening 24, and the partition wall 22 also has an opening 25.

On the right side of the partition wall 22 in the soundproof box 21, there is an engine radiator 31 which is an air-cooling type heat exchange device.
Further, an oil cooler 32 for a compressor, an engine 34 equipped with a fan 33, a compressor body 35 which is a working machine body driven by the engine 34, and the like are arranged. The engine radiator 31 faces the opening 25 of the partition wall 22, and a compressor oil cooler 32 is arranged on the right side of the engine radiator 31. Further, the fan 33 faces the compressor oil cooler 32.

On the other hand, an exhaust muffler 41 which is a silencer of the engine 34 is arranged in the muffler chamber 23. The exhaust muffler 41 has an exhaust muffler main body 42 arranged in the lower part of the muffler chamber 23. The exhaust muffler main body 42 has a cylindrical shape, and is supported on the bottom surface of the soundproof box 21 by a mounting bracket 43 with the axial direction in the front-back direction. The other end of the primary side exhaust pipe 44, one end of which is connected to the exhaust manifold of the engine 34, is connected to an inflow port 45 at the lower end of one end surface of the exhaust muffler body 42. The primary side exhaust pipe 44 penetrates the partition wall 22 and is supported by the soundproof box 21 by a mounting bracket 46.

Further, one end of a secondary side exhaust pipe 51 is connected to an outlet 50 at the center of one end face of the exhaust muffler main body 42. The secondary side exhaust pipe 51 is bent horizontally to the front from the outlet 50, then bent and rises upward, further bent downward, and then bent upward and rises upward. This final rise is the exhaust opening 52,
The opening at the upper end is the exhaust opening 53. The secondary exhaust pipe 51 is supported by the soundproof box 21 by a mounting member 54. As described above, in the middle of the conduit of the secondary side exhaust pipe 51, from the exhaust muffler main body 42 side toward the exhaust opening 53 side,
There is a bent portion 56 that has once risen vertically and then bent obliquely downward. At the bottom of this bent portion 56, a small hole 57 for draining water that communicates the inside and outside of the pipe is formed. Although only one small hole 57 is provided in this embodiment, a plurality of small holes 57 may be provided. The bent portion 56 includes the lower end 58a of the core 58 of the engine radiator 31 and the exhaust muffler body.
It is located above the upper wall of 42, and is located in the exhaust path 59 for the cooling air that has passed through the engine radiator 31. The lower end 58a of the core 58 of the radiator 31 for the engine
In the case where the height of the exhaust muffler differs from the height of the upper wall of the exhaust muffler main body 42, the bent portion 56 may be located above either one of them.

Next, the operation of the above configuration will be described. During operation, the compressor body 35
Is driven. At this time, the rotation of the fan 33 causes the rotation of FIG.
A flow of cooling air is generated as indicated by an arrow. This cooling air passes through an oil cooler 32 for the compressor and a radiator 31 for the engine to cool them, and further the openings of the partition wall 22.
It is discharged from 25 through the muffler chamber 23 through the upper opening 24. Then, the cooling water of the engine 34 is cooled by passing through the engine radiator 31. Further, oil for lubricating and cooling the compressor body 35 is cooled by passing through the compressor oil cooler 32.

Further, the exhaust gas of the engine 34 is an exhaust muffler.
Discharged via 41. That is, the exhaust gas flows from the exhaust manifold of the engine 34 through the exhaust pipe 44 of the primary side into the exhaust muffler main body 42, as shown by the arrows in FIGS. 1 and 2.
It enters inside, passes through the inside of the secondary side exhaust pipe 51, and is discharged from the exhaust opening 53. And, rainwater and the like that have entered the secondary side exhaust pipe 51 through this upward exhaust opening 53 are
In the secondary exhaust pipe 51, the secondary exhaust pipe 51 is temporarily accumulated in a bent portion 56 having a downward recessed shape, and as shown by an arrow in FIG. 51 Fall outside. This prevents rainwater from entering the exhaust muffler body 42. Therefore, it is possible to prevent black water from being blown back at the time of subsequent start.

Further, the secondary side exhaust pipe 51 is provided through the small hole 57.
Although a small amount of exhaust gas leaks from the exhaust gas, the leaked exhaust gas is discharged to the outside of the soundproof box 21 by riding on the cooling air for the compressor oil cooler 32 and the engine radiator 31. At this time, the bent portion 56 of the secondary side exhaust pipe 51 having the small hole 57
Is in the upper part of the muffler chamber 23, in the cooling air exhaust passage 59,
Since the cooling air is positioned in the laminar flow, the leaked exhaust gas is surely and promptly discharged. That is, the lower portion of the muffler chamber 23, particularly the lower end 58a of the core 58 of the engine radiator 31 and the exhaust muffler body 42.
Turbulence is likely to occur in a place lower than the upper wall of the engine, but since the bent portion 56 is located above the lower end 58a of the core 58 of the engine radiator 31 and the upper wall of the exhaust muffler main body 42, laminar flow is generated. Exhaust gas is smoothly discharged without staying in the soundproof box 21 by riding on the cooling wind. Therefore, it is possible to prevent the pollution due to the leaked exhaust gas, especially the vicinity of the mating portion 60 of the members constituting the soundproof box 21 from becoming dirty.

Further, the above-described effects can be obtained by only changing the bent shape of one secondary side exhaust pipe 51, which is advantageous in manufacturing and does not increase the cost.

Next, a second embodiment of the present invention will be described with reference to FIG. In each of the following embodiments, the parts corresponding to those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the second embodiment, the bent portion 61 is
The shape of is slightly different from that of the first embodiment, and the function and effect are the same as those of the first embodiment.

FIG. 4 shows a third embodiment of the present invention. In the third embodiment, the secondary side exhaust pipe 51 extends upward from the exhaust muffler main body 42 side toward the exhaust opening 53 side. After standing up, it is bent obliquely upward, and further, the exhaust opening 52 stands up almost upward. An inclined connection portion 68 in which an upper pipe 67 is connected to an outer peripheral side of a lower pipe 66 is provided in a portion of the secondary exhaust pipe 51, which is directed obliquely upward in the middle of the pipeline. The pipes 66, 67 are fixed to each other by welding or a belt on the upper side of the inclined connection portion 68, but at the lower end of the inclined connection portion 68 between the peripheral walls of the pipes 66, 67 in the axial direction. A communication passage 69 is formed to connect the inside and outside of the pipe along the side. The inclined connection portion 68 having the communication passage 69 is formed at the lower end 58a of the core 58 of the engine radiator 31 or the main body of the exhaust muffler.
It is located above the upper wall of 42, and the cooling air exhaust path 59
Located inside.

Rainwater, etc., which has entered the secondary side exhaust pipe 51 through the exhaust opening 53, has an inclined connecting portion 68 as indicated by an arrow.
Through the communication passage 69 located in the secondary exhaust pipe 51 promptly and reliably. That is, since the inclined connection portion 68 is directed obliquely upward toward the exhaust opening 53 side, rainwater or the like flows downward along the lower side in the inclined connection portion 68, but the communication passage 69 is the upper pipe. The rainwater and the like are smoothly discharged from the communication passage 69 because the rainwater and the like are located between the peripheral walls of the pair of pipes 66, 67 connected with the outer peripheral side of 67. Therefore, it is possible to prevent rainwater and the like from entering the exhaust muffler main body 42.

Exhaust gas is, as shown by the arrow, 2
In the secondary exhaust pipe 51, the exhaust gas does not easily leak from the secondary exhaust pipe 51 through the communication passage 69 because it flows in the direction opposite to the direction from the inside to the outside of the communication passage 69. In addition, the inclined connection portion 68 having the communication passage 69 is located above the lower end 58a of the core 58 of the engine radiator 31 or the upper wall of the exhaust muffler main body 42, and is located in the cooling air exhaust passage 59. The exhaust gas leaking from the inside of the secondary side exhaust pipe 51 through the communication passage 69 is also quickly and reliably discharged to the outside of the soundproof box 21 by riding on the cooling air. Therefore, the inside of the soundproof box 21 is not contaminated by the leaked exhaust gas.

FIG. 5 shows a fourth embodiment of the present invention. In the fourth embodiment, the exhaust muffler main body 42 is arranged with its axial direction vertical, and the circumference of the exhaust muffler main body 42 is shown. There is an inlet 45 at the bottom of the surface, whereas the exhaust muffler body 42
Has an outlet 50 to which a secondary exhaust pipe 51 is connected. The shape of the bent portion 56 of the secondary side exhaust pipe 51 is the same as the first
Similar to the embodiment, the bent portion 56 has a small hole 57 for draining water.
There is.

FIG. 6 shows a fifth embodiment of the present invention. In the fifth embodiment, instead of the upper end surface of the exhaust muffler main body 42 in the fourth embodiment, the peripheral surface is a secondary side. Exhaust pipe 51
There is an outlet 50 to which is connected. The shape of the bent portion 56 of the secondary side exhaust pipe 51 is the same as in the first embodiment and the fourth embodiment.
It is similar to the embodiment.

FIG. 7 shows a sixth embodiment of the present invention. In contrast to the first embodiment, in which the small hole 57 for draining water is formed by drilling with a drill or the like, In the sixth embodiment, a small hole 71 for draining water is formed by cutting and raising. Various other shapes and methods of forming the small holes for draining water are possible.

FIG. 8 shows a seventh embodiment of the present invention. In the seventh embodiment, a resonator 76 is provided in the middle of the conduit of the secondary side exhaust pipe 51, so that the exhaust opening 53 side is provided. The bent portion 77 is formed so as to rise once and then bend downward. A small hole 78 for draining water is formed in the lower wall portion of the resonator 76, which is the lowermost portion of the bent portion 77.

FIG. 9 shows an eighth embodiment of the present invention. In this eighth embodiment, a chamber 81 is provided below the exhaust opening 52 in the secondary side exhaust pipe 51 to form a resonator. At the same time, a bent portion 82 that once rises toward the exhaust opening 53 side and then bends downward is formed.
Then, a small hole 83 for draining water is formed in the lower wall of the chamber 81.
To form an opening.

The present invention is not limited to the above embodiment, and various modifications can be made. For example,
The arrangement of each part in the exhaust muffler and the shape of the secondary side exhaust pipe can be various other than the above-mentioned embodiments. For example, the exhaust opening of the secondary exhaust pipe may be slightly lateral. Further, in the above embodiment,
Although the working machine was a compressor, the present invention can be applied to an exhaust muffler of a working machine such as a generator other than the compressor.

[0031]

According to the first aspect of the invention, the exhaust opening of the secondary side exhaust pipe from the exhaust muffler body is arranged so as to be directed upward, and in the secondary side exhaust pipe, to the exhaust opening side. A bent portion is provided which rises substantially upwards and bends downward, and a small hole is opened at the bottom of this bent portion so that rainwater or the like that enters the secondary side exhaust pipe from the exhaust opening is bent. And its small holes can be used for drainage, preventing rainwater from entering the exhaust muffler body. Further, since the bent portion and its small hole are arranged at a position corresponding to the laminar flow portion of the cooling air passage above the core of the air-cooling type heat exchange device or above the upper wall of the exhaust muffler body, the exhaust gas leaked from the small hole. Can be discharged by being placed on the cooling air for the air-cooling type heat exchange device, and therefore, pollution due to leaked exhaust gas can be prevented.

Further, according to the second aspect of the present invention, since the bent portion is provided in the exhaust passage of the cooling air that has passed through the air-cooling type heat exchange device, the exhaust gas leaked from the small holes can be more reliably and smoothly discharged. Therefore, it is possible to more reliably prevent the inside of the soundproof box from being contaminated by the leaked exhaust gas.

Further, according to the invention of claim 3, the exhaust opening of the secondary side exhaust pipe from the exhaust muffler main body is arranged upward, and the lower side pipe is provided in the secondary side exhaust pipe. Since the upper pipe is connected to the outer peripheral side of the pipe, the inclined connecting portion is provided obliquely upward toward the exhaust opening side, and the communication passage is provided between the peripheral walls of both pipes at the lower end thereof. Rainwater that has entered the side exhaust pipe can smoothly flow out of the secondary passage to the outside of the secondary exhaust pipe, and rainwater and the like can be prevented from entering the exhaust muffler body. Further, since the communication passage of the inclined connection portion is arranged below the core of the air-cooling heat exchange device or above the upper wall of the exhaust muffler body, the exhaust gas leaking from the communication passage is used as cooling air for the air-cooling heat exchange device. Therefore, the leaked exhaust gas can prevent the inside of the soundproof box from being contaminated.

[Brief description of drawings]

FIG. 1 shows a first embodiment of an exhaust muffler of a working machine of the present invention, and is a front view with a soundproof box in section.

FIG. 2 is a side view showing a cross section of the above soundproof box.

FIG. 3 shows a second embodiment of the exhaust muffler of the working machine of the present invention, and is a sectional view of a part of the secondary side exhaust pipe.

FIG. 4 shows a third embodiment of the exhaust muffler of the working machine of the present invention, and is a front view with a part in section.

FIG. 5 shows a fourth embodiment of the exhaust muffler of the working machine of the present invention and is a front view with a part in section.

FIG. 6 is a front view showing a fifth embodiment of an exhaust muffler of a working machine according to the present invention, a part of which is a cross section.

FIG. 7 shows a sixth embodiment of the exhaust muffler of the working machine of the present invention, and is a sectional view of a part of the secondary side exhaust pipe.

FIG. 8 shows a seventh embodiment of the exhaust muffler of the working machine of the present invention, and is a front view with a part in section.

FIG. 9 shows an eighth embodiment of the exhaust muffler of the working machine of the present invention and is a front view with a part in section.

FIG. 10 is a schematic view showing an example of an exhaust muffler of a conventional work machine, (a) is a front view in which a soundproof box is shown in section, and (b) is shown.
FIG. 3 is a side view of a soundproof box in a cross section.

[Explanation of symbols]

 21 Soundproof box 31 Engine radiator (air-cooled heat exchanger) 32 Compressor oil cooler (air-cooled heat exchanger) 34 Engine 35 Compressor body (work machine body) 41 Exhaust muffler 42 Exhaust muffler main body 51 Secondary exhaust Pipe 52 Exhaust opening 53 Exhaust opening 56 Bent portion 57 Small hole 58 Core 59 Exhaust passage 61 Bent portion 66, 67 Pipe 68 Inclined connection portion 69 Communication passage 71 Small hole 77 Bent portion 78 Small hole 82 Bent portion 83 Small hole

Claims (3)

[Claims] 1. An air-cooled heat exchange device is sandwiched in a soundproof box,
In an exhaust muffler of a working machine in which an engine and a working machine body driven by the engine are arranged on one side, and an exhaust muffler of the engine is arranged on the other side, exhaust gas from a secondary side exhaust pipe extending from the exhaust muffler body The opening is arranged substantially upward, and the secondary side exhaust pipe once rises substantially upward and then bends downward in the middle of the pipe path from the exhaust muffler body to the exhaust opening. A bent portion is provided, and a small hole that communicates the inside and the outside of the pipe is opened at the bottom of this bent portion, and the small hole of the bent portion is formed under the core of the air-cooling heat exchange device or on the upper wall of the exhaust muffler body. An exhaust muffler for a working machine, characterized in that it is arranged above either one. 2. The exhaust muffler for a working machine according to claim 1, wherein the bent portion is provided in an exhaust passage for cooling air that has passed through the air-cooling type heat exchange device. 3. An air-cooling type heat exchange device is sandwiched in a soundproof box,
In an exhaust muffler of a working machine in which an engine and a working machine body driven by the engine are arranged on one side, and an exhaust muffler of the engine is arranged on the other side, exhaust gas from a secondary side exhaust pipe extending from the exhaust muffler body The opening is arranged almost upward, and the upper pipe is connected to the outer peripheral side of the lower pipe in the middle of the pipe path from the muffler body to the exhaust opening. And a communication passage that communicates the inside and outside of the pipe is provided between the peripheral walls of both pipes at the lower end of the inclined connection portion, and the communication passage is formed below the core of the air-cooling heat exchange device or the exhaust muffler body. An exhaust muffler for a working machine, which is arranged above either one of the upper walls of the work machine.