JP5865197B2 - Exhaust pipe - Google Patents

Description

  The present invention relates to an exhaust pipe that is provided on an exhaust gas outlet side of an exhaust conduit that guides exhaust gas of an engine of a traveling vehicle and lowers the temperature of the exhaust gas.

As a traveling vehicle equipped with a diesel engine, there is a traveling vehicle described in Patent Document 1.
In this traveling vehicle, an exhaust gas purification device (DPF: Diesel Particulate Filter) that purifies the exhaust gas of the engine in the exhaust gas distribution path for exhausting the exhaust gas discharged from the diesel engine to the atmosphere. ) Is provided. This exhaust gas purification device captures particulate matter (soot, particulates) contained in engine exhaust gas, and heats and captures the captured particulate matter. The exhaust gas that has passed through the exhaust gas purification device is discharged to the atmosphere through an exhaust pipe.

The exhaust gas discharged from the exhaust gas purification device is at a high temperature. Since exhausting high-temperature exhaust gas to the atmosphere may affect the surrounding environment, it is necessary to lower the temperature of the exhaust gas on the exhaust gas outlet side of the exhaust conduit.
On the other hand, there is an exhaust pipe disclosed in Patent Document 2 as an exhaust pipe that is provided on the exhaust gas outlet side of the exhaust pipe and lowers the temperature of the exhaust gas discharged from the exhaust pipe and discharges the exhaust gas to the atmosphere. .

This exhaust pipe allows exhaust gas discharged from the exhaust conduit to pass through and is discharged to the atmosphere. The exhaust pipe has two axial centers arranged in the direction along the exhaust gas passage direction and arranged side by side in the exhaust gas passage direction. It has an exhaust pipe.
The exhaust pipe on the upstream side in the exhaust gas passage direction is called an upstream exhaust pipe, and the exhaust pipe on the downstream side in the exhaust gas passage direction is called a downstream exhaust pipe.

The upstream exhaust pipe is fitted and connected to the exhaust gas outlet side of the exhaust pipe (tail pipe), and is fixed to the exhaust gas outlet side by a radial clamp.
The upstream side exhaust pipe and the downstream side exhaust pipe are connected by a pair of connecting members in the radial direction. In addition, the downstream end portion of the upstream exhaust pipe is a reduced diameter portion that gradually decreases in the exhaust gas passage direction, and the distal end side of this reduced diameter portion is inserted into the upstream end portion of the downstream exhaust pipe. A circumferential annular gap is formed between the outer surface of the reduced diameter portion and the upstream end opening edge of the downstream exhaust pipe, and this gap introduces outside air into the exhaust pipe. It is said that.

  In this exhaust pipe, engine exhaust gas is discharged from the upstream exhaust pipe and flows to the downstream exhaust pipe. By the exhaust gas flow flowing from the upstream exhaust pipe to the downstream exhaust pipe (by the Venturi effect), the outside air is sucked from the outside air inlet to the downstream exhaust pipe, and the sucked outside air is mixed with the exhaust gas. As a result, the temperature of the exhaust gas can be lowered.

JP 2010-11601 A Special table 2010-509545 gazette

In the conventional exhaust pipe, the exhaust gas of the engine discharged from the exhaust conduit is only cooled at the outlet portion of the exhaust gas, and the cooling effect of the exhaust gas is not sufficient.
Further, if the exhaust pipe provided on the exhaust gas outlet side of the exhaust pipe is made too long in order to lower the temperature of the exhaust gas discharged from the exhaust pipe, the exhaust efficiency is deteriorated or a problem in space is caused. Therefore, the exhaust pipe provided on the exhaust gas outlet side of the exhaust conduit is required to be compact in the exhaust gas passage direction while having a function of appropriately reducing the exhaust gas discharged from the exhaust conduit.

  Accordingly, in view of the above problems, the present invention provides an exhaust pipe capable of efficiently lowering the temperature of exhaust gas discharged from an exhaust conduit for guiding exhaust gas discharged from an engine at a short distance in the exhaust gas discharge direction. It is an issue to provide.

The technical means taken by the present invention to solve the technical problems are characterized by the following points.
In the invention according to claim 1, the exhaust gas is provided on the exhaust gas outlet side of the exhaust conduit that guides the exhaust gas so as to exhaust the exhaust gas of the engine to the atmosphere, and the exhaust gas discharged from the exhaust conduit is passed through to the atmosphere. An exhaust pipe for discharging,
A plurality of exhaust pipes arranged along the axis in the exhaust gas passage direction are arranged side by side in the exhaust gas passage direction,
In order to form an outside air inlet for sucking outside air into the exhaust pipe by the exhaust gas flow passing through these exhaust pipes, the exhaust pipe on the most upstream side in the exhaust gas passage direction has a diameter larger than that of the exhaust gas outlet side of the exhaust pipe. The exhaust pipe on the downstream side in the exhaust gas passage direction is formed larger in diameter than the exhaust pipe on the upstream side in the exhaust gas passage direction ,
Arrange the exhaust pipes at intervals in the axial direction,
The exhaust gas flow that flows from the exhaust pipe upstream of the exhaust gas passage direction to the exhaust pipe downstream of the exhaust gas passage direction flows from the upstream exhaust pipe to the downstream exhaust pipe. The guide member which guides to the outer peripheral side of this is provided .

In the invention according to claim 2 , in the middle of the exhaust pipe, a circumferential cut and a recess formed on the upstream side of the cut in the exhaust gas passage direction and recessed inward in the radial direction of the exhaust pipe An outside air intake port composed of the above is provided.
The invention according to claim 3 is characterized in that an attachment member for attaching the exhaust pipe separately from the exhaust conduit is provided.

The invention according to claim 4 is characterized in that the exhaust pipe on the most upstream side in the exhaust gas passage direction is arranged at an axial distance from the exhaust gas outlet of the exhaust conduit.

The present invention has the following effects.
According to the first aspect of the present invention, the exhaust gas of the engine discharged from the exhaust gas outlet of the exhaust conduit flows from the exhaust conduit to the exhaust pipe on the most upstream side in the exhaust gas passage direction. The outside air is sucked into the exhaust pipe from the outside air inlet formed between the exhaust conduit and the exhaust pipe, and the temperature of the exhaust gas can be lowered by mixing the outside air with the exhaust gas. Further, the exhaust gas discharged from the exhaust conduit is diffused when flowing to the exhaust pipe on the most upstream side in the exhaust gas passage direction formed larger in diameter than the exhaust gas outlet side of the exhaust conduit. The temperature of the exhaust gas can be lowered.

  Furthermore, the exhaust gas flow flowing from the exhaust pipe upstream in the exhaust gas passage direction of the adjacent exhaust pipe to the exhaust pipe downstream in the exhaust gas passage direction causes the downstream side from the outside air inlet formed between the exhaust pipes. The temperature of the exhaust gas can be lowered by sucking the outside air into the exhaust pipe and mixing the outside air with the exhaust gas. Further, the exhaust gas is diffused when flowing to the exhaust pipe downstream in the exhaust gas passage direction, which is formed larger in diameter than the exhaust pipe upstream in the exhaust gas passage direction, thereby reducing the temperature of the exhaust gas. be able to.

As described above, according to the first aspect of the invention, the exhaust gas discharged from the exhaust conduit is cooled at the exhaust gas outlet portion of the exhaust conduit and also at the middle portion of the exhaust conduit. Thus, the temperature of the exhaust gas discharged from the exhaust gas can be efficiently lowered at a short distance in the exhaust gas discharge direction.
Further, by arranging the exhaust pipes at intervals in the axial direction, the amount of outside air sucked into the exhaust pipe can be increased, and the temperature of the exhaust gas can be lowered efficiently.

The exhaust gas flow flowing from the exhaust pipe upstream in the exhaust gas passage direction to the exhaust pipe downstream in the exhaust gas passage direction is guided by the guide member and flows on the outer peripheral side of the downstream exhaust pipe. The exhaust gas flowing on the outer peripheral side of the downstream exhaust pipe has a higher flow rate as the guide member narrows the passage area of the exhaust gas flow. As a result, the effect of sucking outside air is improved, and the temperature of the exhaust gas can be lowered efficiently.

In addition, since the outside air inlet is formed on the outer peripheral side of the exhaust pipe, the temperature of the exhaust gas flowing through the exhaust pipe is higher on the pipe center side than on the pipe outer peripheral side. The exhaust gas can be uniformly cooled by guiding it to the pipe outer periphery side where the outside air is introduced.
According to the second aspect of the invention, the amount of outside air introduced into the exhaust pipe can be increased by the outside air intake provided in the middle of the exhaust pipe, and the temperature of the exhaust gas can be lowered efficiently.

According to the invention which concerns on Claim 3 , the support stability of an exhaust pipe can be improved by providing the attachment member for attaching the said exhaust pipe separately from an exhaust conduit.
According to the fourth aspect of the present invention, by arranging the exhaust pipe on the most upstream side in the exhaust gas passage direction at an axial distance from the exhaust gas outlet of the exhaust conduit, the outside air sucked into the exhaust pipe Can be increased, and the temperature of the exhaust gas can be efficiently lowered.

It is side surface sectional drawing of the exhaust pipe of 1st Embodiment. It is a side view of the state which attached the exhaust pipe. It is a rear view of the state which attached the exhaust pipe. (A) is the AA arrow directional cross section of FIG. 1, (b) is the BB arrow directional cross-sectional view of FIG. It is a side view of the tractor which attached the exhaust pipe. It is a side view of a tractor front part. It is a perspective view of the exhaust pipe attachment part of the tractor front part. It is a side surface partial sectional view of an exhaust pipe concerning a 2nd embodiment. It is a rear view of the exhaust pipe which concerns on 2nd Embodiment. It is a side partial sectional view of the exhaust pipe which concerns on 3rd Embodiment. (A) is a rear view of the exhaust pipe which concerns on 3rd Embodiment, (b) is CC sectional view taken on the line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 5, reference numeral 1 denotes a tractor (traveling vehicle) to which the exhaust pipe 2 of the present invention is attached. The tractor 1 has a vehicle body 5 supported by a pair of left and right front wheels 3 and a pair of left and right rear wheels 4 so as to be able to travel.
In the present embodiment, the vehicle body 5 includes a front engine 6, a clutch housing 7 connected to the rear part of the engine 6, and a hydrostatic continuously variable transmission ( HST) 8, a sheet metal structure housing frame 9 connecting the HST 8 and the clutch housing 7, a transmission case 10 connected to the rear part of the HST 8, a differential case 11 connected to the rear part of the transmission case 10, and the like. It is configured.

A cabin 12 is mounted at the rear of the vehicle body 5, a driver seat 13 is provided at the rear of the cabin 12, and a steering device 15 having a steering handle 14 and the like is provided in front of the driver seat 13.
The engine 6 is constituted by a water-cooled vertical diesel engine, and the engine 6 is covered with a hood 16 that can be opened and closed as shown in FIG. In the bonnet 16 (engine room), a radiator 17 disposed in front of the engine 6 and an exhaust gas purification device (DPF) 18 that purifies the exhaust gas of the engine 6, a battery (not shown), an oil cooler, An air cleaner, a hydraulic pump, etc. are accommodated.

A front axle frame 19 extends forward from the lower part of the engine 6, and a front axle case on which the front wheels 3 are mounted is supported on the front axle frame 19.
As shown in FIGS. 6 and 7, the front axle frame 19 includes a side plate 21 disposed on both the left and right sides of the engine 6, a front plate 22 that connects the front end sides of the left and right side plates 21, and an outer side of each of the left and right side plates 21. And a reinforcing plate 23 fixed to the side surface. The left-right plate 21 is made of a plate material that is long in the front-rear direction with the plate surface facing the left-right direction, and the rear portion is bolted to the side surface of the engine 6.

The radiator 17 is supported on the front axle frame 19, and a support plate 24 that supports a battery, an oil cooler, and the like is provided in front of the lower end side of the radiator 17. The support plate 24 is attached and supported by a bracket 25 fixed to the left and right side plates 21. The left and right sides of the support plate 24 extend from the front axle frame 19 to the left and right.
The exhaust gas purifying device 18 collects and removes particulate matter mainly composed of carbon contained in the exhaust gas of the engine 6, and collects the collected particulate matter by depositing it. In order to prevent the deterioration of the function, it has a self-cleaning function for heating and collecting the collected particulate matter for combustion. For this reason, the temperature of the exhaust gas of the engine 6 discharged from the exhaust gas purification device 18 is higher than the temperature of the exhaust gas of the general engine 6.

In this embodiment, as shown in FIG. 6, the exhaust gas purification device 18 is disposed above the rear portion of the engine 6, and the gas intake portion 26 of the exhaust gas purification device 18 is provided on the left side of the engine 6. The exhaust manifold 27 is connected via a connection pipe 28.
An exhaust gas inlet side 31 of the exhaust conduit 30 is connected to the gas discharge part 29 of the exhaust gas purification device 18. The exhaust conduit 30 guides the exhaust gas to exhaust the exhaust gas of the engine 6 purified by the exhaust gas purification device 18 to the atmosphere, and extends downward from the gas discharge portion 29 of the exhaust gas purification device 18. In addition, the pipe is routed through the left side of the engine 6 so as to reach the front and rear halfway part on the left side of the front axle frame 19.

  As shown in FIG. 7, the vicinity of the exhaust gas outlet 32 of the exhaust conduit 30 is supported by a support bracket 33 that is positioned in the front-rear halfway portion on the left side of the front axle frame 19 and attached to the reinforcing plate 23. . Further, the exhaust gas outlet 32 of the exhaust conduit 30 is directed forward, and the exhaust gas of the engine 6 is purified by the exhaust gas purification device 18 and then guided to the exhaust conduit 30 to the left side of the front axle frame 19. It reaches the middle part before and after, and is discharged forward from the exhaust gas outlet 32 of the exhaust conduit 30.

An exhaust pipe 2 is provided on the exhaust gas outlet 32 side of the exhaust conduit 30 to allow exhaust gas discharged from the exhaust conduit 30 to pass through to the atmosphere and to lower the temperature of the exhaust gas during passage of the exhaust gas. It has been. The exhaust pipe 2 allows exhaust gas exhausted forward from the exhaust conduit 30 to pass forward and exhausts forward.
As shown in FIGS. 6 and 7, in this embodiment, the exhaust pipe 2 is located in front of the exhaust gas outlet 32 of the exhaust conduit 30 and on the left side of the front part of the front axle frame 19 (left side plate). 21 on the left side).

The exhaust pipe 2 is positioned below the left side of the support plate 24 and has an attachment stay (attachment member) 34 attached to the support plate 24. Therefore, the exhaust pipe 2 is attached and fixed to the vehicle body 5 side separately from the exhaust gas outlet 32 side of the exhaust conduit 30. Further, the exhaust pipe 2 is located below the bonnet 16.
1 to 4 show an exhaust pipe 2 according to the first embodiment. The exhaust pipe 2 is formed of a cylindrical straight pipe having an axial center along the exhaust gas passage direction X (in the front-rear direction) and having an axial center in the front-rear direction (having the same diameter in the axial direction). Two exhaust pipes 36 and 37 are provided. These exhaust pipes 36 and 37 are arranged side by side in the exhaust gas passage direction X (in the front-rear direction).

  The exhaust pipe 36 on the downstream side (front side) in the exhaust gas passage direction X is formed larger in diameter than the exhaust pipe 37 on the upstream side (rear side) in the exhaust gas passage direction X. The front exhaust pipe 36 is formed to have a shorter axial length than the rear exhaust pipe 37. The rear exhaust pipe 37 (exhaust pipe in the exhaust gas passage direction X most upstream side) is formed larger in diameter than the exhaust gas outlet 32 side of the exhaust conduit 30.

  In this exhaust pipe 2, the rear exhaust pipe 37 is formed larger in diameter than the exhaust gas outlet 32 side of the exhaust conduit 30, so that the rear end side of the rear exhaust pipe 37 and the exhaust conduit 30 are connected. An annular gap (space) in the exhaust pipe circumferential direction is formed between the exhaust gas outlet 32 side, and this gap serves as an outside air introduction port 38 for introducing outside air into the exhaust pipe 37 on the rear side (this is the first gap). It is said to be an outside air inlet).

In the first embodiment, the exhaust gas outlet 32 side of the exhaust conduit 30 is inserted into the rear end side of the rear exhaust pipe 37, and the outer surface 39 of the exhaust conduit 30 on the exhaust gas outlet 32 side is A space between the rear end opening edge 40 of the rear exhaust pipe 37 is a first outside air introduction port 38.
Further, by forming the front exhaust pipe 36 to have a diameter larger than that of the rear exhaust pipe 37, the circumference of the exhaust pipe is between the rear end side of the front exhaust pipe 36 and the front end side of the rear exhaust pipe 37. An annular gap (space) in the direction is formed, and this gap serves as an outside air inlet 41 (referred to as a second outside air inlet) for introducing outside air into the front exhaust pipe 36.

Further, the front exhaust pipe 36 and the rear exhaust pipe 37 are arranged with a space W1 in the front-rear direction, and the opening edge 42 at the rear end of the front exhaust pipe 36 and the rear exhaust pipe 37 are arranged. A space between the opening edge 43 at the front end is a second outside air introduction port 41.
By disposing the front exhaust pipe 36 and the rear exhaust pipe 37 with a space W1 in the front-rear direction, the front exhaust pipe 36 is disposed between the rear end side of the front exhaust pipe 36 and the front end side of the rear exhaust pipe 37. The gap formed is widened, and the second outside air inlet 41 can be widened.

Further, a holding piece (holding member) 44 for holding the exhaust gas outlet 32 side of the exhaust conduit 30 concentrically with the rear exhaust pipe 37 is provided at the rear end side of the rear exhaust pipe 37. It has been.
The holding piece 44 is made of a plate material, and is provided so as to protrude rearward from the inner surface side of the rear exhaust pipe 37. In the present embodiment, the holding piece 44 is spaced at equal intervals in the circumferential direction of the rear exhaust pipe 37. One is provided. Note that two or four or more holding pieces 44 may be provided.

Each holding piece 44 is disposed so that the plate surface faces the circumferential direction of the rear exhaust pipe 37, and the exhaust pipe radial outer end 44 a (the end in the plate width direction) at the front portion of the holding piece 44. Part) is fixed to the inner surface of the exhaust pipe 37 on the rear side by welding.
An end face 44b on the exhaust pipe radial inner side of each holding piece 44 is in contact with an outer surface of the exhaust conduit 30 on the exhaust gas outlet 32 side, and holds the exhaust gas outlet 32 side of the exhaust conduit 30. .

The front exhaust pipe 36 and the rear exhaust pipe 37 are connected by a connecting piece (connecting member) 45 so as to be concentric and at a distance W1 in the front-rear direction.
The connecting piece 45 is made of a plate material, and in the present embodiment, three connecting pieces 45 are provided, and an equal interval is provided between the front exhaust pipe 36 and the rear exhaust pipe 37 in the circumferential direction of the exhaust pipes 36 and 37. Arranged. Note that two or four or more connecting pieces 45 may be provided.

Each connecting piece 45 is arranged such that the plate surface faces the circumferential direction of the exhaust pipes 36 and 37, and the rear portion of each connecting piece 45 is located on the outer surface side of the rear exhaust pipe 37. An end portion 45a (an end portion in the plate width direction) on the radially inner side of the exhaust pipe at the rear portion is welded and fixed to the outer surface of the exhaust pipe 37 on the rear side.
The front part of each connecting piece 45 is inserted into the front exhaust pipe 36, and the end 45b (end in the plate width direction) of the front part of the connecting piece 45 in the radial direction of the exhaust pipe is the front exhaust. The inner surface of the pipe 36 is fixed by welding.

An open L-shaped notch 46 is formed on the front side of each connecting piece 45 in the exhaust pipe radial direction and rearward and inward in the exhaust pipe radial direction.
The mounting stay 34 is made of a plate material, and is formed in an L shape in a front view from an upper wall 34a and a side wall 34b extending downward from an end on the inner side in the left-right direction of the upper wall 34a. Is fixed to the right side surface of the front portion of the rear exhaust pipe 37 by welding. The upper wall 34a of the attachment stay 34 is bolted to the support plate 24.

Between the rear end side of the front exhaust pipe 36 and the front end side of the rear exhaust pipe 37, a guide member 47 provided from the rear exhaust pipe 37 to the front exhaust pipe 36 is provided.
The guide member 47 is formed in a conical shape (a truncated conical shape) in which the front portion 48 is formed in a columnar shape and the rear portion 49 is reduced in diameter toward the rear, and the front and rear exhaust pipes 36 and 37 are formed. Are arranged concentrically.

The front portion 48 of the guide member 47 is inserted into the front exhaust pipe 36 from the rear side, is fitted into the L-shaped cutout portion 46 of each connection piece 45 from the rear side, and is connected to each connection piece 45. It is fixed to the front by welding.
The rear portion 49 of the guide member 47 has a front portion located in the front exhaust pipe 36, a rear portion protruding rearward from the front exhaust pipe 36, and a rear end portion inserted into the rear exhaust pipe 37. Has been.

In the exhaust pipe 2 configured as described above, the exhaust gas of the engine 6 exhausted from the exhaust gas purification device 18 is exhausted forward from the exhaust gas outlet 32 of the exhaust conduit 30, and the rear exhaust pipe 37 and the front side are exhausted. The exhaust pipe 36 is sequentially passed and discharged forward.
At this time, outside air is sucked from the first outside air inlet 38 into the rear exhaust pipe 37 by the exhaust gas flow flowing from the exhaust gas outlet 32 of the exhaust conduit 30 to the rear exhaust pipe 37. The sucked outside air can be mixed with the exhaust gas in the rear exhaust pipe 37, and the temperature of the exhaust gas can be lowered. Further, the exhaust gas discharged from the exhaust conduit 30 is diffused when flowing to the exhaust pipe 37 on the rear side formed larger in diameter than the exhaust gas outlet 32 side of the exhaust conduit 30, thereby also exhausting the exhaust gas. The gas temperature can be lowered.

  Further, even when the exhaust gas flows from the rear exhaust pipe 37 to the front exhaust pipe 36, the outside air is sucked into the front exhaust pipe 36 from the second outside air introduction port 41 by the exhaust gas flow. The sucked outside air can be mixed with the exhaust gas in the front exhaust pipe 36, and the temperature of the exhaust gas can be lowered. Further, the exhaust gas is diffused by flowing to the front exhaust pipe 36 having a diameter larger than that of the rear exhaust pipe 37, and the temperature of the exhaust gas can also be lowered by this.

Further, the exhaust gas flow flowing from the rear exhaust pipe 37 to the front exhaust pipe 36 is guided to the outer peripheral side of the front exhaust pipe 36 by the conical surface 49a of the rear portion 49 of the guide member 47, and the front exhaust pipe 36 36 flows on the inner peripheral side.
On the other hand, when the guide member 47 narrows the passage area of the exhaust gas flow, the exhaust gas guided to the outer peripheral side of the front exhaust pipe 36 by the guide member 47 has a high flow velocity. Thereby, the suction effect of the outside air sucked from the second outside air introduction port 41 is improved (the amount of outside air suction increases), and the temperature of the exhaust gas can be lowered efficiently.

Further, since the first outside air introduction port 38 is formed on the outer peripheral side of the rear end side of the rear exhaust pipe 37 and the speed of the exhaust gas discharged from the exhaust conduit 30 is high, the first outside air introduction port 38 is sucked from the first outside air introduction port 38. The outside air thus made is difficult to mix up to the pipe center side, and therefore, the temperature of the exhaust gas flowing through the rear exhaust pipe 37 is higher at the pipe center side than at the pipe outer peripheral side.
The exhaust gas at the center side of the pipe having a high temperature is guided to the outer peripheral side of the rear end of the front exhaust pipe 36 by the guide member 47, and from the second outside air inlet 41 provided on the rear end side of the front exhaust pipe 36. Mix with the outside air introduced.

As a result, the exhaust gas can be uniformly cooled.
As described above, the temperature of the exhaust gas discharged from the exhaust conduit 30 is lowered (primarily cooled) when flowing into the rear exhaust pipe 37 from the exhaust conduit 30, and from the rear exhaust pipe 37. The temperature is lowered (secondarily cooled) also when flowing into the front exhaust pipe 36, and the exhaust pipe 2 according to this embodiment determines the temperature of the exhaust gas discharged from the exhaust conduit 30 according to the exhaust gas discharge direction. Can be lowered efficiently at a short distance.

In the above-described configuration, the holding piece 44 may be fixed by welding to the exhaust conduit 30 (although the exhaust pipe 2 may be a part of the exhaust conduit 30), in this embodiment, the holding piece 44 is attached to the exhaust conduit 30. The exhaust pipe 2 is not fixed and can be attached and detached separately from the exhaust conduit 30.
Further, since it is a separate structure from the exhaust conduit 30, it can be inexpensive and can be easily improved, and can be easily provided in the existing exhaust conduit 30.

Moreover, the support stability of the exhaust pipe 2 can be improved by attaching the exhaust pipe 2 separately from the exhaust pipe 30.
8 and 9 show the exhaust pipe 2 according to the second embodiment.
In the exhaust pipe 2 of the second embodiment, the above-described guide member 47 is not provided, and the above-described holding piece 44 is not provided in the rear exhaust pipe 37. The rear exhaust pipe 37 is attached so that a space W2 in the axial direction of the rear exhaust pipe 37 is provided between the exhaust pipe 37 and the exhaust gas outlet 32 of the exhaust conduit 30. Different from the embodiment.

  In the second embodiment, the second outside air introduction port 41 is formed between the rear end opening edge 40 of the rear exhaust pipe 37 and the opening edge 50 of the exhaust gas outlet 32 of the exhaust conduit 30. Yes. Further, by arranging the rear exhaust pipe 37 forwardly away from the exhaust gas outlet 32 of the exhaust conduit 30, the rear exhaust pipe 37 is disposed between the rear end side of the rear exhaust pipe 37 and the exhaust gas outlet 32 side of the exhaust conduit 30. And the first outside air inlet 38 is widened. As a result, the amount of outside air introduced can be increased, and the temperature of the exhaust gas can be lowered.

In the second embodiment, the mounting stay 34 is formed of a flat plate, and the outer end side in the left-right direction is welded and fixed to the rear upper surface of the exhaust pipe 37 on the rear side. The inner end of the mounting stay 34 in the left-right direction is bolted to a bracket 51 fixed to the reinforcing plate 23, whereby the exhaust pipe 2 is mounted and supported on the front axle frame 19.
Other configurations are the same as those in the first embodiment.

10 and 11 show the exhaust pipe 2 according to the third embodiment.
In the exhaust pipe 2 of the third embodiment, an outside air intake 52 is provided in the middle of the rear exhaust pipe 37 in the front-rear direction. The point that the outside air intake 52 is provided is that the second air pipe 52 is provided. This is different from the embodiment, and other configurations are the same as those in the first embodiment and the second embodiment.

A plurality (three in this embodiment) of the outside air inlets 52 are provided at equal intervals in the circumferential direction of the rear exhaust pipe 37. The outside air inlet 52 is formed by making a circumferential cut 53 in the exhaust pipe 37 on the rear side, and forming a recess 54 extending toward the upstream side (rear) in the exhaust gas passage direction X from the cut 53. ing.
The recess 54 is formed to be recessed toward the radially inward side of the exhaust pipe 37 on the rear side, and the depth of the recess 54 gradually increases toward the downstream side (forward) in the exhaust gas passage direction X. The width of the exhaust pipe 37 in the circumferential direction of the rear side of the recess 54 is formed so as to gradually narrow toward the rear.

The outside air is sucked from the outside air inlet 52 by the exhaust gas flow flowing in the rear side exhaust pipe 37, and the outside air taken into the rear side exhaust pipe 37 from the outside air inlet 52 has a recess 54 in the exhaust gas passage direction X. Since it is formed so as to gradually become deeper as it goes downstream (forward), it flows in an oblique direction that moves to the center side of the rear exhaust pipe 37 as it goes forward.

The outside air intake 52 may be formed in the exhaust pipe 37 on the rear side of the first embodiment. Further, the outside air intake 52 may be formed in the front exhaust pipe 36 in each embodiment.
In each of the above embodiments, the exhaust pipe 2 may include three or more exhaust pipes 36 and 37.

  Also in the exhaust pipe 2 of the first embodiment, the holding piece 44 is eliminated, and the distance between the rear exhaust pipe 37 and the exhaust gas outlet 32 of the exhaust conduit 30 in the axial direction of the rear exhaust pipe 37. W2 may be provided.

6 Engine 30 Exhaust conduit 32 Exhaust gas outlet 34 Mounting member 36 Exhaust pipe (exhaust pipe on the downstream side in the exhaust gas passage direction)
37 Exhaust pipe (exhaust pipe upstream of exhaust gas passage direction)
38 Outside air inlet 41 Outside air inlet 47 Guide member 52 Outside air inlet 53 Notch 54 Recess X Exhaust gas passage direction W1 interval w2 interval

Claims (4)

Provided on the exhaust gas outlet (32) side of the exhaust conduit (30) for guiding the exhaust gas to exhaust the exhaust gas of the engine (6) to the atmosphere, and passes through the exhaust gas exhausted from the exhaust conduit (30) An exhaust pipe that discharges to the atmosphere,
A plurality of exhaust pipes (36, 37) arranged along the axis in the exhaust gas passage direction (X) and arranged side by side in the exhaust gas passage direction (X);
The exhaust gas passage direction is such that the exhaust gas flow passing through the exhaust pipes (36, 37) forms the outside air inlets (38, 41) for sucking outside air into the exhaust pipes (36, 37). (X) The exhaust pipe (37) on the most upstream side is formed larger in diameter than the exhaust gas outlet (32) side of the exhaust conduit (30) and the exhaust pipe (36) on the downstream side in the exhaust gas passage direction (X) The exhaust gas passage direction (X) is formed larger in diameter than the exhaust pipe (37) on the upstream side ,
The exhaust pipes (36, 37) are arranged with an interval (W1) in the axial direction,
Exhaust gas passage direction (X) provided in the exhaust pipe (37) on the upstream side to the exhaust pipe (36) on the downstream side in the exhaust gas passage direction (X).
An exhaust pipe , characterized in that a guide member (47) is provided for guiding the exhaust gas flow flowing from the downstream to the downstream exhaust pipe (36) to the outer peripheral side of the downstream exhaust pipe (36) . In the middle of the exhaust pipe (36, 37), a circumferential cut (53) and a radial direction of the exhaust pipe (36, 37) are formed upstream of the cut (53) in the exhaust gas passage direction X. The exhaust pipe according to claim 1 , further comprising an outside air intake (52) configured with a recess (54) recessed inward. The exhaust pipe according to claim 1 or 2 , further comprising an attachment member (34) for attaching the exhaust pipe separately from the exhaust conduit (30). Exhaust gas passage direction (X) The exhaust pipe (37) on the most upstream side is arranged at an axial distance (W2) from the exhaust gas outlet (32) of the exhaust conduit (30). The exhaust pipe according to any one of claims 1 to 3 .

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