Patent Description:
For example, among work vehicles such as tractors used in orchards, livestock barns, and the like, in some work vehicles provided with an engine, a muffler is provided at a lower portion of the mechanical body due to restrictions on the height of the mechanical body, or the like. In these cases, in use environments such as orchards and livestock barns, combustibles such as fallen leaves may accumulate on the ground, so there is a demand to lower the temperature of the engine exhaust discharged from the muffler.

A tractor, which is an example of a work vehicle, may be provided with a configuration as disclosed in patent literature <NUM> as a configuration for lowering the temperature of engine exhaust.

In patent literature <NUM>, a first exhaust pipe from which engine exhaust is sent and a second exhaust pipe provided with an inlet having a larger outer diameter than an outlet of the first exhaust pipe are provided, wherein the outlet of the first exhaust pipe and the inlet of the second exhaust pipe are disposed in close proximity such that the outlet of the first exhaust pipe is disposed in the interior of the inlet of the second exhaust pipe.

When engine exhaust exits from the outlet of the first exhaust pipe and enters the interior of the second exhaust pipe from the inlet of the second exhaust pipe, outside air is drawn into the flow of the engine exhaust due to an ejector effect, brought into the interior of the second exhaust pipe from the inlet of the second exhaust pipe, and mixes with the engine exhaust. The temperature of the engine exhaust is thereby lowered by the outside air.

Patent literature <NUM> describes an apparatus for reducing the temperature of an exhaust gas for an engine of a construction machine. More particularly, patent literature <NUM> relates to an improved exhaust gas temperature reduction apparatus for an engine of a construction machine, in which when an exhaust gas generated in the combustion process of a smoke reduction device of an engine, preferably a diesel engine of the construction machine passes through a diffuser and a tail pipe, the exhaust gas is mixed with a cooling fan air flow and an external air so that a low-temperature exhaust gas can be discharged to the outside of an engine room.

Patent literature <NUM> describes an exhaust gas diffusion device introducing outside air into an outside air mixing cylinder, which has a larger inner diameter than an outer diameter of an exhaust side end part of an exhaust pipe that sends out exhaust gas of a vehicle engine and is arranged at a position where the exhaust gas from the exhaust pipe is received, and mixes introduced outside air with exhaust gas. The exhaust gas diffusion device comprises a wind direction member that promotes the mixing of the outside air and the exhaust gas by being arranged at an upstream position in a flow direction of the exhaust gas or an internal position of the exhaust pipe in the outside air mixing cylinder.

Patent literature <NUM> describes a device for cooling an exhaust gas stream having a discharge nozzle impinged by an exhaust gas flow. The discharge nozzle projects in an open end of an adjacent exhaust gas pipe such that a low pressure compared to the environment is generated in a suction area with passage of the exhaust gas flow. The suction area is formed between the discharge nozzle and the exhaust gas pipe. An adjusting unit is provided for changing the flow cross-section of the discharge nozzle. An independent claim is also included for a motor vehicle with an engine chamber.

Patent literature <NUM> describes an exhaust assembly including an exhaust pipe, a first venturi member at the inlet end of the pipe and a second venturi member at the outlet end of the pipe. A diffuser/mixer is mounted at the outlet end of the exhaust pipe. A shield pipe surrounds a portion of the exhaust pipe. A shield member is mounted to the shield pipe and covers a portion of the first venturi member. The first and second venturi members operate to combine ambient air with exhaust gases.

Patent literature <NUM> describes an exhaust stack for an internal combustion engine including an upstream segment having a proximal portion and a distal portion, and a downstream segment. The distal portion of the upstream segment has a non-circular cross section and at least partially defines a venturi opening. The downstream segment has a downstream proximal portion that at least partially defines the venturi opening. The distal portion defines a flow area that is less than or equal to a flow area of the proximal portion, and defines a perimeter that is greater than a perimeter of the proximal portion.

Patent literature <NUM> describes a tail pipe arrangement for an exhaust system of a vehicle. The tail pipe arrangement comprises an inlet, by which the surrounding air is introduced into the exhaust flow for cooling the exhaust flow. A primary pipe is provided, which introduces the exhaust gas area by area into an inlet opening of a secondary pipe in the flow direction.

In the above configuration of patent literature <NUM>, in order to bring in a large amount of outside air in order to lower the temperature of the engine exhaust, it is preferable to increase the flow speed of the engine exhaust at the outlet of the first exhaust pipe, and for the outlet of the first exhaust pipe, it is preferable to increase a portion (boundary surface) where the engine exhaust flow contacts the outside air.

In patent literature <NUM>, in order to increase the flow speed of the engine exhaust at the outlet of the first exhaust pipe, the outlet of the first exhaust pipe is squeezed to a flat shape to increase the flow speed of the engine exhaust. However, if the outlet of the first exhaust pipe is squeezed too much, the disadvantage of increased engine exhaust back pressure increases.

In order to increase the portion (boundary surface) where the engine exhaust flow contacts the outside air, increasing the diameters of the outlet of the first exhaust pipe and the inlet of the second exhaust pipe, and providing many configurations wherein the outlet of the first exhaust pipe and the inlet of the second exhaust pipe are disposed in close proximity are considered, but these lead to undesired larger or more complicated structures.

An object of the present invention is to configure a work vehicle such that when the outlet of the first exhaust pipe and the inlet of the second exhaust pipe are disposed in proximity, the temperature of the engine exhaust may be lowered by a large amount of outside air being drawn into the flow of engine exhaust and mixed into the engine exhaust without squeezing the outlet of the first exhaust pipe more than necessary.

A work vehicle according to the present invention comprises a first exhaust pipe for engine exhaust, and a second exhaust pipe provided with an inlet having an outer diameter larger than an outer diameter of an outlet of the first exhaust pipe, wherein the outlet of the first exhaust pipe and the inlet of the second exhaust pipe are disposed in proximity such that the outlet of the first exhaust pipe is disposed inside the inlet of the second exhaust pipe. The work vehicle further comprises a partition dividing a cross-section of the outlet of the first exhaust pipe into a plurality of divided regions when viewed from the flow direction and partitions the adjacent divided regions at intervals. A cross-section of the partition has a wedge shape tapering toward an upstream of the exhaust discharged from the outlet of the first exhaust pipe.

According to the present invention, the outlet of the first exhaust pipe and the inlet of the second exhaust pipe are disposed in proximity such that the outlet of the first exhaust pipe is disposed inside the inlet of the second exhaust pipe, the cross-section of the outlet of the first exhaust pipe is divided into a plurality of divided regions by the partition and the adjacent divided regions are partitioned at intervals by the partition.

According to the present invention, when the engine exhaust is discharged from the outlet of the first exhaust pipe, the flow of the engine exhaust is divided into a plurality of flows corresponding to the divided regions while passing through the plurality of divided regions due to the partition. Immediately after the partition, the plurality of flows of engine exhaust become independent flows, and after this, the plurality of flows of the engine exhaust are mixed with outside air and then converge. At the same time, because the region of the outlet of the first exhaust pipe is narrowed by the partition, the flow speed of the plurality of flows of engine exhaust is increased.

According to the present invention, in each of the plurality of flows of engine exhaust, the peripheral part of the divided region serves as the boundary surface, and thus, the sum of boundary surfaces of the plurality of flows of engine exhaust becomes the boundary surface of the engine exhaust when the partition is provided.

In contrast, the boundary surface of the engine exhaust when the partition is not provided is the peripheral part of the outlet of the first exhaust pipe.

Therefore, the boundary surface of engine exhaust when the partition is provided is larger than the boundary surface of the engine exhaust when the partition is not provided.

As described above, according to the present invention, by providing the partition, it is possible to increase the boundary surface of the engine exhaust while increasing the flow speed of the engine exhaust appropriately, and thus, it is possible to configure so that a large amount of outside air is drawn into the flow of engine exhaust, introduced into the interior of the second exhaust pipe from the inlet of the second exhaust pipe, and mixed with the engine exhaust, so that and the temperature of the engine exhaust can be reduced.

In the present invention, a cross-section of the partition has a wedge shape when viewed from a direction orthogonal to the flow direction, the wedge shape tapering toward an upstream of a flow of the exhaust discharged from the outlet of the first exhaust pipe.

According to the present invention, when the flow of engine exhaust is divided into a plurality of divided regions by the partition, the cross-sectional shape of the partition is wedge-shaped, and therefore, the flow of engine exhaust is guided along the partition, spaces in which engine exhaust cannot flow in regions downstream of the partition are more easily generated, and these spaces are more easily expanded further downstream. Thus, because the outside air is more easily mixed into a space wherein the engine exhaust cannot flow, it can be expected that the temperature of the engine exhaust is efficiently decreased.

According to an embodiment, the partition may be attached to the outlet of the first exhaust pipe.

According to an embodiment, at the outlet of the first exhaust pipe, the partition may be attached across one portion of the peripheral part and another portion of the peripheral part of the outlet, and therefore the outlet of the first exhaust pipe is reinforced by the partition.

According to an embodiment, the partition may be formed such that the areas of the plurality of divided regions are all the same when viewed from the flow direction.

According to this embodiment, when the flow of engine exhaust is divided into a plurality of flows by the partition as described above, the areas of the plurality of divided regions due to the partition are all the same, and the boundary surfaces of each of the plurality of flows of engine exhaust are substantially the same, and therefore, outside air can be expected to mix in each of the plurality of flows of engine exhaust substantially evenly and the temperatures of the engine exhaust of each of the plurality of flows of engine exhaust can be expected to decrease substantially evenly.

Thus, when the flows of the engine exhaust converge after being divided into a plurality of flows by the partition, it can be expected that the temperature of the engine exhaust will decrease substantially evenly.

According to an embodiment, the partition may extend radially outward from a center of the outlet of the first exhaust pipe when viewed from the flow direction.

According to this embodiment, since the partition is disposed and formed radially, it is possible to form the partition in a simple manner while giving the partition sufficient strength.

According to an embodiment, the work vehicle may further comprise a further partition, the further partition being a flat-shaped member having a plurality of openings.

According to this embodiment, since the further partition is formed in a flat shape having a plurality of openings, it is possible to form the further partition in a simple manner while giving the further partition sufficient strength.

According to an embodiment, the partition may be line symmetrical with respect to a virtual straight line passing through a center of the outlet of the first exhaust pipe when viewed from the flow direction.

According to this embodiment, it can be expected that the temperature of the engine exhaust will be reduced substantially evenly due to the outside air mixing with the engine exhaust along the line-symmetrical partition.

According to an embodiment, the work vehicle further comprises one or more notch parts extending from an end of the outlet of the first exhaust pipe to the direction opposite to the second exhaust pipe and is formed on the peripheral part of the outlet of the first exhaust pipe.

According to this embodiment, when the engine exhaust is discharged from the outlet of the first exhaust pipe, the flow of the engine exhaust is divided into a plurality of flows corresponding to the divided regions while passing through the plurality of divided regions due to the partition. Immediately after the partition, the plurality of flows of engine exhaust become independent flows, and after this, the plurality of flows of the engine exhaust are mixed with outside air and then converge. At the same time, because the region of the outlet of the first exhaust pipe is narrowed by the partition, the flow speed of the plurality of flows of engine exhaust is increased. When the engine exhaust is discharged from the outlet of the first exhaust pipe, the engine exhaust is also discharged from the notch part.

According to this embodiment, in each of the plurality of flows of engine exhaust, the peripheral part of the divided region serves as the boundary surface, and thus, the sum of boundary surfaces of the plurality of flows of engine exhaust becomes the boundary surface of the engine exhaust when the partition is provided.

When the engine exhaust is discharged from the outlet of the first exhaust pipe, the engine exhaust is also discharged from the notch part, so the peripheral part of the notch part also serves as the boundary surface. In this case, the peripheral part of the notch part is long due to the notch part extending from the end of the outlet of the first exhaust pipe to the direction opposite to the second exhaust pipe.

According to this embodiment, the boundary surface of engine exhaust when the partition is provided and the boundary surface of the engine exhaust when the notch part is provided are summed.

In contrast, the boundary surface of the engine exhaust when the partition and notch part are not provided is the peripheral part of the outlet of the first exhaust pipe.

Therefore, the boundary surface of engine exhaust when the partition and notch part are provided is larger than the boundary surface of the engine exhaust when the partition and notch part are not provided.

As described above, according to an embodiment, by providing the partition and notch part, it is possible to increase the boundary surface of the engine exhaust while increasing the flow speed of the engine exhaust appropriately, and thus, it is possible to configure so that a large amount of outside air is drawn into the flow of engine exhaust, introduced into the interior of the second exhaust pipe from the inlet of the second exhaust pipe, and mixed with the engine exhaust, so that and the temperature of the engine exhaust can be reduced.

According to an embodiment, the partition may be attached on the first exhaust pipe across a portion further separated to the direction opposite to the second exhaust pipe than the end of the notch part in the direction opposite to the second exhaust pipe, and the end of the outlet of the first exhaust pipe, and the partition may protrude from the end of the outlet of the first exhaust pipe toward the second exhaust pipe.

According to this embodiment, the partition is formed in a long shape in the flow direction, and therefore, when the flow of engine exhaust is divided into a plurality of flows by the partition as described above, the plurality of flows of engine exhaust each easily become independent flows. This is advantageous in that the peripheral parts of the divided regions of each of the plurality of flows of engine exhaust serve as the boundary surface.

According to an embodiment, the partition and the notch part may be line symmetrical with respect to a virtual straight line passing through a center of the outlet of the first exhaust pipe when viewed from the flow section.

According to this embodiment, it can be expected that the temperature of the engine exhaust will be reduced substantially evenly due to the outside air mixing with the engine exhaust along the line-symmetrical partition and notch part.

<FIG> illustrate a tractor that is an example of a work vehicle, wherein F shows a forward direction, B shows a backward direction, U shows an upward direction, and D shows a downward direction.

As illustrated in <FIG>, a mechanical body <NUM> is supported by right and left front wheels <NUM> and right and left rear wheels <NUM>. A diesel-type engine <NUM> is provided at a front portion of the mechanical body <NUM>, a driving unit <NUM> is provided at back portion of the mechanical body <NUM>, and a driver's seat <NUM> and a steering wheel <NUM> for the front wheels <NUM> are provided in the driving unit <NUM>. An arch-shaped ROPS frame <NUM> is provided between the engine <NUM> and the driving unit <NUM>.

As illustrated in <FIG> and <FIG>, exhaust of the engine <NUM> is fed to an exhaust purification device (not illustrated) (DPF) to remove particulates from the exhaust of the engine <NUM>. Next, the exhaust of the engine <NUM> is fed from the exhaust purification device (DPF) to an exhaust purification device <NUM> (SCR), and nitrogen oxide is removed from the exhaust of the engine <NUM>.

The exhaust purification device <NUM> is disposed along the horizontal or left-right direction between the engine <NUM> and the driving unit <NUM> (steering wheel <NUM>), and a round pipe shaped exhaust pipe <NUM> is extended downward from a right portion of the engine purification device <NUM>. A round pipe shaped first exhaust pipe <NUM> is connected to the exhaust pipe <NUM> and extended downward, and a round pipe shaped second exhaust pipe <NUM> is supported along the vertical or up-down direction on the bottom of the first exhaust pipe <NUM>.

With the above configuration, the exhaust of the engine <NUM> is fed from the exhaust purification device (not illustrated) (DPF) to the exhaust purification device <NUM> (SCR) and sent from the exhaust pipe <NUM> to the first exhaust pipe <NUM>, sent from an outlet <NUM> of a lower portion of the first exhaust pipe <NUM> to an inlet <NUM> of an upper portion of the second exhaust pipe <NUM> and discharged from an outlet <NUM> of a lower portion of the second exhaust pipe <NUM>.

As illustrated in <FIG> and <FIG>, four triangular notch parts <NUM> are formed at intervals of <NUM> degrees on a peripheral part of the outlet <NUM> of the first exhaust pipe <NUM>.

At the peripheral part of the outlet <NUM> of the first exhaust pipe <NUM>, two triangular notch parts <NUM> smaller than the notch parts <NUM> are formed on each of the four portions between the adjacent notch parts <NUM>, forming a total of eight notch parts <NUM>. A plurality of notch parts <NUM> are thereby formed across the entire periphery of the peripheral port of the outlet <NUM> of the first exhaust pipe <NUM>.

The notch parts <NUM>, <NUM> are formed with point symmetry with respect to a center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>).

As illustrated in <FIG>, when imagining virtual straight lines E1, E2, E3, E4 passing through the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the notch parts <NUM> are formed with line symmetry with respect to virtual straight lines E1, E2, E3, E4.

Notch parts <NUM>, <NUM> are formed to extend upward from end parts 13a, 13b of the outlet <NUM> of the first exhaust pipe <NUM> (opposite side of the second exhaust pipe <NUM>). Regarding end parts 13a, 13b of the outlet <NUM> of the first exhaust pipe <NUM>, the end part 13a adjacent to the notch parts <NUM> extends farther downward (to the second exhaust pipe <NUM> side) than the end part 13b between notch parts <NUM>.

As illustrated in <FIG>, and <FIG>, a plate material is folded into a triangular cross-section to form partitions <NUM>, <NUM> and the partitions <NUM>, <NUM> are combined so as to cross orthogonally and connect to each other. The partitions <NUM>, <NUM> are inserted into the notch parts <NUM> of the outlet <NUM> of the first exhaust pipe <NUM> and attached to the outlet <NUM> of the first exhaust pipe <NUM>.

Seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the orthogonally crossing portions of the partitions <NUM>, <NUM> are disposed at the center of the outlet <NUM> of the first exhaust pipe <NUM>. Seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM>, the partitions <NUM>, <NUM> are disposed and formed radially facing outward from the center of the outlet <NUM> of the first exhaust pipe <NUM>.

Due to the partitions <NUM>, <NUM> being formed by the plate material being bent to have a triangular cross-section, seen from the direction orthogonal to the direction A1 (see <FIG>) of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the cross-sectional shape of the partitions <NUM>, <NUM> is formed in a wedge shape tapering upstream of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM>.

The partitions <NUM>, <NUM> are formed with point symmetry with respect to the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>).

As illustrated in <FIG>, when imagining virtual straight lines E1, E2, E3, E4 passing through the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the partitions <NUM>, <NUM> are formed with line symmetry with respect to virtual straight lines E1, E2, E3, E4.

Even in a configuration in which the partitions <NUM>, <NUM> and the notch part <NUM> are combined, the configuration in which the partitions <NUM>, <NUM> and the notch part <NUM> are combined is formed with line symmetry with respect to the virtual straight lines E1, E2, E3, E4.

Outer ends 16a, 17a of the partitions <NUM>, <NUM> protrude radially outward from the outer peripheral portion of the outlet <NUM> of the first exhaust pipe <NUM>. The upper end parts 16b, 17b of the partitions <NUM>, <NUM> are positioned above the upper end part 19a of the notch part <NUM> (opposite side of the second exhaust pipe <NUM>) (see <FIG>), and the lower end parts 16c, 17c of the partitions <NUM>, <NUM> protrude downward from the end parts 13a, 13b of the outlet <NUM> of the first exhaust pipe <NUM> (to the second exhaust pipe <NUM> side) (see <FIG>).

Thus, the partitions <NUM>, <NUM> are attached on the first exhaust pipe across a portion further separated on the opposite side of the second exhaust pipe <NUM> than the end part 19a of the opposite side of the second exhaust pipe <NUM> of the notch part <NUM>, and the end part 13a of the outlet <NUM> of the first exhaust pipe <NUM>, and the partitions <NUM>, <NUM> protrude from the end parts 13a, 13b of the outlet <NUM> of the first exhaust pipe <NUM> towards the second exhaust pipe <NUM> side.

As illustrated in <FIG>, seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the region of the outlet <NUM> of the first exhaust pipe <NUM> is divided by the partitions <NUM>, <NUM> into four divided regions B1. A region of the notch part <NUM> is also included in the four divided regions B1, and the adjacent divided regions B1 are partitioned by the partitions <NUM>, <NUM> with intervals C1 of the width of the partitions <NUM>, <NUM>.

Thus, seen from the direction A1 (see <FIG>) of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM>, the areas of the four divided regions B1 are all the same.

When exhaust of the engine <NUM> is sent to the first exhaust pipe <NUM>, the exhaust of the engine <NUM> is divided into four flows corresponding to the divided regions B1 at the outlet <NUM> of the first exhaust pipe <NUM> while passing through the divided regions B1 due to the partitions <NUM>, <NUM>. Immediately after the partitions <NUM>, <NUM>, the four flows of exhaust of the engine <NUM> become independent flows, and after this, the four flows of exhaust of the engine <NUM> are mixed with outside air and then converge.

At the same time, the cross-sectional shape of the partitions <NUM>, <NUM> is formed in a wedge shape that tapers upstream of the flow of the exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM>, and thus, the region of the outlet <NUM> of the first exhaust pipe <NUM> is narrowed by the partitions <NUM>, <NUM> and flow of the exhaust of the engine <NUM> is obstructed by the partition <NUM>, <NUM>, causing the flow speed of the four flows of exhaust of the engine <NUM> to increase. A negative pressure space in which exhaust of the engine <NUM> cannot flow is more easily generated in the region downstream of the partitions <NUM>, <NUM>, and this negative pressure space is more easily expanded downstream.

In the flow corresponding to the divided regions B1 of the exhaust of the engine <NUM>, the boundary surface, which is the portions at which the flow of exhaust of the engine <NUM> contacts outside air, is the sum of a portion L1 corresponding to the lower end part 16c of the partition <NUM>, a portion L2 corresponding to the lower end part 17c of the partition <NUM>, two portions L3 corresponding to the peripheral parts of the two notch parts <NUM>, and three portions L4 corresponding to end parts 13a, 13b of the outlet <NUM> of the first exhaust pipe <NUM>.

Thus, the boundary surface when the partitions <NUM>, <NUM> and the notch parts <NUM> are provided is the sum of the boundary surfaces of the four flows corresponding to the divided regions B1 of the exhaust of the engine <NUM>.

As illustrated in <FIG>, the second exhaust pipe <NUM> is formed to have a larger diameter than the first exhaust pipe <NUM>, and the inlet <NUM> of the second exhaust pipe <NUM> is formed to have a larger outer diameter than the outlet <NUM> of the first exhaust pipe <NUM>. The outlet <NUM> of the second exhaust pipe <NUM> is formed so as to face laterally outward to the right from the mechanical body <NUM>.

As illustrated in <FIG>, in a side view (direction orthogonal to the direction A1 of the flow exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM>), the outlet <NUM> of the first exhaust pipe <NUM> and the inlet <NUM> of the second exhaust pipe <NUM> are disposed in proximity such that the outlet of the first exhaust pipe <NUM> (end parts 16c, 17c of the partitions <NUM>, <NUM>) and the outlet <NUM> of the second exhaust pipe <NUM> are disposed at small intervals C2.

As illustrated in <FIG>, seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the outlet <NUM> of the first exhaust pipe <NUM> and the partitions <NUM>, <NUM> are disposed in the interior of the inlet <NUM> of the second exhaust pipe <NUM>.

The peripheral part of the outlet <NUM> of the first exhaust pipe <NUM> and the peripheral part of the inlet <NUM> of the second exhaust pipe <NUM> are disposed at intervals C3. The outer end parts 16a, 17a of the partitions <NUM>, <NUM> and the peripheral part of the inlet <NUM> of the second exhaust pipe <NUM> are disposed at intervals C4 narrower than the intervals C3.

With the above configuration, the exhaust of the engine <NUM> is discharged from the outlet <NUM> of the first exhaust pipe <NUM>, is sent to the inlet <NUM> of the second exhaust pipe <NUM>, enters the interior of the second exhaust pipe <NUM>, and is exhausted from the outlet <NUM> of the lower portion of the second exhaust pipe <NUM>.

As described above (relationship between the partitions and notch parts and the outlet of the first exhaust pipe), by providing the partitions <NUM>, <NUM> and notch parts <NUM>, the flow speed of exhaust of the engine <NUM> can be appropriately increased.

A negative pressure space in which exhaust of the engine <NUM> cannot flow is more easily generated in the region downstream of the partitions <NUM>, <NUM>, and outside air more easily mixes in this negative pressure space.

The boundary surface when the partitions <NUM>, <NUM> and the notch parts <NUM> are provided is the sum of the boundary surfaces of the four flows corresponding to the divided regions B1 of the exhaust of the engine <NUM>.

Thus, a large amount of outside air is drawn into the flow of exhaust of the engine <NUM>, brought into the interior of the second exhaust pipe <NUM> from between the peripheral part of the outlet <NUM> of the first exhaust pipe <NUM> and the inlet <NUM> of the second exhaust pipe <NUM>, mixed into the exhaust of the engine <NUM>, and the temperature of the exhaust of the engine <NUM> is lowered.

In the configuration illustrated in <FIG>, the notch part <NUM> may be removed.

In a side view, in order to overlap the outlet <NUM> of the first exhaust pipe <NUM> and the inlet <NUM> of the second exhaust pipe <NUM>, the outlet <NUM> of the first exhaust pipe <NUM> may be disposed along the direction A1 (see <FIG>) of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> so as to slightly enter the interior of the inlet <NUM> of the second exhaust pipe <NUM>.

Partitions <NUM>, <NUM> may be provided in the inlet <NUM> of the second exhaust pipe <NUM> and the outlet <NUM> of the first exhaust pipe <NUM> may be disposed in proximity to the partitions <NUM>, <NUM>.

The invention may also configure the work vehicle so that the partitions <NUM>, <NUM> are configured to combine and connect to each other at angles other than <NUM> degrees so that the areas of the four divided regions B1 are not all the same while forming the partitions <NUM>, <NUM> with point symmetry with respect to the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 (see <FIG>) of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM>.

The cross-sectional shape of the partitions <NUM>, <NUM> may be formed in a wedge shape that is <NUM>/<NUM> of an elongated ellipse instead of a triangular wedge shape.

According to this configuration, the outer surfaces of the partitions <NUM>, <NUM> are not linear but arcuate in cross section, and therefore it can be expected that the flow of exhaust of the engine <NUM> along the outer surfaces of the partitions <NUM>, <NUM> will be smooth.

As illustrated in <FIG>, a partition <NUM> may be configured by a flat-shaped member or a flat plate and the partition <NUM> formed so that a plurality of arm portions 20a extend radially outward from the center of the outlet <NUM> of the first exhaust pipe <NUM> form the center of the partition <NUM>.

In the configuration illustrated in <FIG>, the arm portions 20a of the partition <NUM> are disposed with point symmetry with respect to the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>).

When imagining virtual straight lines E1, E2 passing through the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the partition <NUM> is formed with line symmetry with respect to virtual straight lines E1, E2. The virtual straight line E1 may be imagined so that it passes through a different arm portion 20a than the arm portion 20a illustrated in <FIG> of the partition <NUM>. The virtual straight line E2 may be imagined so that it passes through a different gap of arm portions 20a than the gap of arm portions 20a illustrated in <FIG> of the partition <NUM>.

One divided region B1 is formed by two adjacent arm portions 20a of the partition <NUM> and the peripheral part of the outlet <NUM> of the first exhaust pipe <NUM>. By setting the angles between adjacent arm portions 20a of the partition <NUM> to be all the same, the areas of the plurality of divided regions B1 are made all the same.

In this case, the number of arm portions 20a of the partition <NUM> is assumed to be <NUM>, <NUM>, <NUM>, and various other numbers. The angles between adjacent arm portions 20a of the partition <NUM> may be set to be different from each other, to configure so that the areas of the plurality of divided regions B1 are not all the same. In addition to the partition <NUM>, a notch part <NUM> illustrated in <FIG> and <FIG> may be formed on the outlet <NUM> of the first exhaust pipe <NUM>.

As illustrated in <FIG>, the partition <NUM> may be configured by a flat-shaped member or a flat plate, and a plurality of circular openings 20b of the same inner diameter opened to form the partition <NUM>.

One divided region B1 is formed by one opening 20b of the partition <NUM>. Because the openings 20b of the partition <NUM> have the same inner diameter, the areas of the plurality of divided regions B1 are all the same.

In the configuration illustrated in <FIG>, the openings 20b of the partition <NUM> are disposed with point symmetry with respect to the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>).

When imagining virtual straight lines E1, E2 passing through the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the partition <NUM> is formed with line symmetry with respect to virtual straight lines E1, E2. The virtual straight line E1 may be imagined so that it passes through a different inside opening 20b than the inside opening 20b illustrated in <FIG> of the partition <NUM>. The virtual straight line E2 may be imagined so that it passes through a different outside opening 20b than the outside opening 20b illustrated in <FIG> of the partition <NUM>.

In this case, the inner diameters of the plurality of opening 20b of the partition <NUM> may be set to be different from each other to configure so that the areas of the plurality of divided regions B1 are not all the same.

As illustrated in <FIG>, the partitions <NUM>, <NUM>, <NUM> may be removed to form a plurality of notch parts <NUM> across the entire periphery of the peripheral portion of the outlet <NUM> of the first exhaust pipe <NUM>.

In the plurality of notch parts <NUM>, instead of forming all the notch parts <NUM> at the same size, the notch parts <NUM> may be configured so that a mixture of different sizes are present, such as large notch parts <NUM> and small notch parts <NUM>.

In the configuration illustrated in <FIG>, the notch parts <NUM> are formed with point symmetry with respect to the center D1 (see <FIG>) of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>).

When imagining virtual straight lines E1, E2 passing through the center D1 of the outlet <NUM> of the first exhaust pipe <NUM> seen from the direction A1 of the flow of exhaust discharged from the outlet <NUM> of the first exhaust pipe <NUM> (see <FIG>), the notch parts <NUM> are formed with line symmetry with respect to virtual straight lines E1, E2.

The virtual straight line E1 may be imagined to that it passes through an end part of the second exhaust pipe <NUM> side of a different notch part <NUM> than the notch part <NUM> illustrated in <FIG>. The virtual straight line E2 may be imagined to that it passes through the center part of a different notch part <NUM> than the notch part <NUM> illustrated in <FIG>.

Instead of triangular notch parts <NUM>, notch parts <NUM> of various shapes such as U-shaped, rectangular, and semicircular may be formed, and a mixture of notch parts <NUM> with different shapes may be configured.

Claim 1:
A work vehicle comprising:
a first exhaust pipe (<NUM>) for engine exhaust; and
a second exhaust pipe (<NUM>) provided with an inlet (<NUM>) having an outer diameter larger than an outlet diameter of an outlet (<NUM>) of the first exhaust pipe (<NUM>), wherein
the outlet (<NUM>) of the first exhaust pipe (<NUM>) and the inlet (<NUM>) of the second exhaust pipe (<NUM>) are disposed in proximity such that the outlet (<NUM>) of the first exhaust pipe (<NUM>) is disposed inside the inlet (<NUM>) of the second exhaust pipe (<NUM>), and
the work vehicle further comprises a partition (<NUM>, <NUM>) dividing a cross-section of the outlet (<NUM>) of the first exhaust pipe (<NUM>) into a plurality of divided regions when viewed from an exhaust flow direction and partitioning the adjacent divided regions at intervals, wherein a cross-section of the partition (<NUM>, <NUM>) has a wedge shape tapering toward an upstream of the exhaust discharged from the outlet (<NUM>) of the first exhaust pipe (<NUM>).