engine

Abstract

To provide an engine capable of suppressing increase in pressure loss in an exhaust gas communication pipe connecting a supercharger and an aftertreatment device.SOLUTION: An engine 1 includes an engine body 2, a supercharger 20, an exhaust emission control device 40 and an exhaust gas communication pipe 25. The supercharger 20 is connected to the engine body 2. The exhaust emission control device 40 purifies exhaust gas discharged from the supercharger 20. The exhaust gas communication pipe 25 connects the supercharger 20 and the exhaust emission control device 40. The exhaust gas communication pipe 25 includes: a first connection member 60 connected to the supercharger 20; and a second connection member 70 connecting the first connection member 60 and the exhaust emission control device 40. A downstream end part 62 of the first connection member 60 includes an inner peripheral surface 62a having a circular cross section. An upstream end part 61 of the first connection member 60 includes an inner peripheral surface 61a having a cross section with a different shape that is different from that of the inner peripheral surface 62a of the downstream end part 62.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an engine. [Background technology]

[0002] Conventionally, there has been known an engine that includes an engine body, a turbocharger connected to the engine body, an aftertreatment device that purifies exhaust gas discharged from the turbocharger, and an exhaust communication pipe that connects the turbocharger and the aftertreatment device (see, for example, Patent Document 1). Patent Document 1 describes a harvester that includes an engine body, a turbocharger, an exhaust gas purification device that purifies exhaust gas discharged from the turbocharger, and an exhaust pipe that connects the turbocharger and the exhaust gas purification device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-2 A Summary of the Invention [Problem to be solved by the invention]

[0004] The turbocharger described in Patent Document 1 has an exhaust pipe connection part that is connected to an exhaust pipe. Generally, the gas flow path of the exhaust pipe connection part is circular. In other words, the exhaust pipe connection part has an inner circumferential surface that has a circular cross section.

[0005] However, in some cases, the exhaust pipe connection portion has an inner circumferential surface with a cross section that is irregularly shaped other than a circular shape. In this case, if the gas flow path of the exhaust pipe is formed in an irregular shape, the pressure loss of the exhaust gas when passing through the gas flow path of the exhaust pipe will be large.

[0006] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an engine that can suppress an increase in pressure loss in an exhaust communication pipe that connects a turbocharger and an aftertreatment device. [Means for solving the problem]

[0007] An engine according to one aspect of the present invention comprises an engine body, a turbocharger, an aftertreatment device, and an exhaust communication pipe. The turbocharger is connected to the engine body. The aftertreatment device purifies exhaust gas discharged from the turbocharger. The exhaust communication pipe connects the turbocharger and the aftertreatment device. The exhaust communication pipe includes a first connecting member connected to the turbocharger and a second connecting member connecting the first connecting member and the aftertreatment device. The downstream end of the first connecting member has an inner circumferential surface with a circular cross section. The upstream end of the first connecting member has an inner circumferential surface with a cross section of an irregular shape different from the inner circumferential surface of the downstream end. [Effects of the Invention]

[0008] According to the present invention, an engine can be provided that can suppress an increase in pressure loss in an exhaust communication pipe that connects a turbocharger and an aftertreatment device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view showing the structure of an engine according to an embodiment of the present invention from the front. [Figure 2] 1 is a perspective view showing the structure of an engine according to an embodiment of the present invention from the rear. FIG. [Figure 3] 1 is a perspective view showing the structure of a turbocharger, an exhaust communication pipe, and an exhaust gas purification device of an engine according to an embodiment of the present invention. FIG. [Figure 4] 1 is a perspective view showing the structure of a supercharger for an engine according to an embodiment of the present invention. FIG. [Figure 5] 1 is a side view showing the structure of an exhaust communication pipe of an engine according to an embodiment of the present invention. [Figure 6] 2 is a front view showing the structure of a first connecting member of the engine according to one embodiment of the present invention. FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. [Figure 8] FIG. 7 is a cross-sectional view taken along line VIII-VIII in FIG. 6. [Figure 9] 1 is a diagram showing the structure of a turbocharger and an exhaust communication pipe of an engine according to an embodiment of the present invention, viewed from the rear. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of an engine according to the present invention will be described with reference to the drawings. Note that in the drawings, the same or corresponding parts are designated by the same reference symbols and description thereof will not be repeated. In this specification, for ease of understanding, a first direction X, a second direction Y, and a third direction Z that intersect with each other are appropriately described. The first direction X and the second direction Y are approximately parallel to the horizontal direction, and the third direction Z is approximately parallel to the vertical direction. In this specification, the first direction X, the second direction Y, and the third direction Z are perpendicular to each other, but they do not have to be perpendicular. Hereinafter, one side X1 of the first direction X indicates the left side of the engine, and the other side X2 of the first direction X indicates the right side of the engine. Furthermore, one side Y1 of the second direction Y indicates the front side (front side) of the engine, and the other side Y2 of the second direction Y indicates the back side (rear side) of the engine. Furthermore, one side Z1 of the third direction Z indicates the upper side, and the other side Z2 of the third direction Z indicates the lower side. However, the left-right direction, the front-rear direction, and the up-down direction are defined merely for the convenience of explanation, and do not limit the orientation of the engine according to the present invention when used or assembled.

[0011] An engine 1 according to one embodiment of the present invention will be described with reference to Figures 1 to 9. Figure 1 is a perspective view showing the structure of engine 1 according to one embodiment of the present invention from the front. Figure 2 is a perspective view showing the structure of engine 1 according to one embodiment of the present invention from the rear. Engine 1 is mounted on a work machine such as an agricultural machine, a construction machine, or a civil engineering machine, for example.

[0012] As shown in Figures 1 and 2, engine 1 includes an engine body 2, an oil pan 6, a cooling fan 7, and a crankshaft 10. Engine body 2 includes a left side portion 2a. Left side portion 2a is an example of a "first side portion" in the present invention. Engine body 2 also includes a combustion chamber (not shown), a cylinder block 3, a cylinder head 4, and a head cover 5.

[0013] A crankshaft 10 is disposed inside the cylinder block 3. The crankshaft 10 is an output shaft. The crankshaft 10 is disposed along the front-rear direction. Both ends of the crankshaft 10 protrude from the cylinder block 3 to the outside.

[0014] The cylinder block 3 includes a right side surface (not shown), a left side surface 3a, and a mounting portion 3b. The mounting portion 3b is located at the front and rear portions of each of the right and left sides 3a of the cylinder block 3. The mounting portion 3b is fixed to the chassis (not shown) of the work machine using bolts via vibration-damping members such as rubber.

[0015] The cylinder head 4 is disposed above the cylinder block 3. The engine 1 further includes an intake manifold (not shown) and an exhaust manifold 11. The intake manifold is disposed on the right side surface (not shown) of the cylinder head 4. The intake manifold supplies air to each cylinder (not shown) of the engine body 2. The exhaust manifold 11 is disposed on the left side surface 4a (see Figure 2) of the cylinder head 4. The exhaust manifold 11 is connected to the cylinder head 4. Exhaust gas is discharged from the cylinder head 4 to the exhaust manifold 11.

[0016] The head cover 5 is disposed above the cylinder head 4 and covers the upper part of the cylinder head 4.

[0017] The oil pan 6 is disposed below the engine body 2. That is, the oil pan 6 is disposed below the cylinder block 3. The oil pan 6 stores lubricating oil. The lubricating oil in the oil pan 6 is supplied to each part of the engine 1 and then returns to the oil pan 6.

[0018] The cooling fan 7 is disposed in front of the engine body 2. The engine 1 further includes a belt 12 disposed in front of the engine body 2. Rotational driving force is transmitted to the cooling fan 7 from the front end of the crankshaft 10 via the belt 12.

[0019] The engine 1 further includes a flywheel 13 and a flywheel housing 13a. The flywheel housing 13a is disposed rearward of the engine body 2. The flywheel housing 13a accommodates the flywheel 13. The flywheel 13 is attached to the rear end of the crankshaft 10. The rotational driving force of the crankshaft 10 is transmitted via the flywheel 13 to the working parts of the work machine.

[0020] Continuing to refer to Figures 1 and 2, the structure around the engine body 2 will be described. The engine 1 further includes a supercharger 20, an intake pipe 23, a supercharger pipe (not shown), and an exhaust communication pipe 25. The supercharger 20 increases the pressure of air supplied to the engine body 2. The supercharger 20 is disposed on the left side of the head cover 5. In other words, the supercharger 20 is disposed on the left side 2a of the engine body 2. The supercharger 20 includes a compressor case 21 and a turbine case 22. The compressor case 21 incorporates a blower wheel (not shown). The turbine case 22 incorporates a turbine wheel (not shown).

[0021] The intake pipe 23 is connected to an intake inlet of the compressor case 21. The supercharging pipe is connected to an intake outlet of the compressor case 21.

[0022] The exhaust manifold 11 extends rearward from the front portion on the left side surface 4a of the cylinder head 4. The exhaust manifold 11 is connected to an exhaust inlet of a turbine case 22. An exhaust communication pipe 25 is connected to an exhaust outlet of the turbine case 22. The exhaust communication pipe 25 is connected to a tailpipe (not shown) via an exhaust gas purification device 40, which will be described later. Therefore, exhaust gas discharged from each cylinder (not shown) of the engine body 2 into the exhaust manifold 11 is discharged to the outside via the turbine case 22 of the turbocharger 20, the exhaust communication pipe 25, the exhaust gas purification device 40, the tailpipe, etc. The detailed structure of the area around the exhaust communication pipe 25 will be described later.

[0023] The engine 1 also includes an exhaust gas purification device 40 and a support member 50. The exhaust gas purification device 40 is an example of the "aftertreatment device" of the present invention. The exhaust gas purification device 40 collects particulate matter and the like in the exhaust gas. The exhaust gas purification device 40 is fixed to the engine body 2. In this embodiment, the exhaust gas purification device 40 is fixed to the engine body 2 via the support member 50. The exhaust gas purification device 40 is disposed above the engine body 2. Specifically, for example, a pair of support members 50 are provided. The pair of support members 50 are disposed at the front and rear of the engine 1, respectively. The support members 50 are fixed to the cylinder head 4 using screws. The support member 50 supports the exhaust gas purification device 40.

[0024] In this embodiment, as described above, the exhaust gas purification device 40 is fixed to the engine body 2. Therefore, the engine 1 can be fixed to the chassis (not shown) of the work machine with the exhaust gas purification device 40 fixed to the engine body 2. Therefore, the installation work of the engine 1 can be simplified compared to, for example, a case where the engine body 2 and the exhaust gas purification device 40 are separately fixed to the chassis (not shown) of the work machine.

[0025] The exhaust gas purification device 40 purifies exhaust gas by removing, for example, NOx, CO, HC, and particulate matter contained in the exhaust gas. The exhaust gas purification device 40 has a DPF (Diesel Particulate Filter) device 41, an SCR (Selective Catalytic Reduction) device 42, and a connecting pipe 43. The DPF device 41 has, for example, a substantially cylindrical case 41a, and an oxidation catalyst and a filter housed in the case 41a. The oxidation catalyst and the filter reduce the NOx, HC, CO, and particulate matter contained in the exhaust gas.

[0026] The SCR device 42 has, for example, a substantially cylindrical case 42a, and an SCR catalyst and an oxidation catalyst housed in the case 42a. The SCR catalyst and the oxidation catalyst reduce NOx contained in the exhaust gas.

[0027] The DPF device 41 is disposed on the left side above the engine body 2, and the SCR device 42 is disposed on the right side above the engine body 2. A connecting pipe 43 connects the DPF device 41 and the SCR device 42. In this embodiment, the connecting pipe 43 connects the rear of the DPF device 41 to the front of the SCR device 42. After flowing from the front to the rear of the DPF device 41, the exhaust gas flows into the SCR device 42 via the connecting pipe 43 and then flows from the front to the rear of the SCR device 42. The exhaust gas is then released to the outside via an exhaust pipe (not shown) connected to the SCR device 42.

[0028] The engine 1 also includes an EGR (Exhaust Gas Recirculation) cooler 30 and a cooling water outlet pipe 31. The exhaust manifold 11 extends to the rear end of the left side surface 4a of the cylinder head 4. The rear end 11a of the exhaust manifold 11 is connected to the EGR cooler 30. A portion of the exhaust gas in the exhaust manifold 11 is sent to the EGR cooler 30. The cooling water outlet pipe 31 is connected to the left side surface 3a of the cylinder block 3. The cooling water that has cooled the cylinder block 3 is discharged into the cooling water outlet pipe 31. The cooling water outlet pipe 31 is also connected to the EGR cooler 30. The exhaust gas in the EGR cooler 30 is cooled by the cooling water passing through the cooling water outlet pipe 31.

[0029] Next, the structure around the exhaust communication pipe 25 of the engine 1 of this embodiment will be described with reference to Figures 3 to 9. First, the structure of the turbocharger 20 will be described with reference to Figures 3 and 4. Figure 3 is a perspective view showing the structures of the turbocharger 20, exhaust communication pipe 25, and exhaust gas purification device 40 of the engine 1 of this embodiment. Figure 4 is a perspective view showing the structure of the turbocharger 20 of the engine 1 of this embodiment.

[0030] As shown in Figures 3 and 4, the turbocharger 20 has a connecting pipe connection part 221 connected to the exhaust connecting pipe 25. The connecting pipe connection part 221 is provided in the turbine case 22. As shown in Figure 4, the turbocharger 20 further has an opening 222, a wastegate port (also referred to as a bypass path) 223, and a wastegate valve 224. The opening 222 is disposed inside the connecting pipe connection part 221. The opening 222 is an outlet that discharges exhaust gas from the inside of the turbine case 22 to the exhaust connecting pipe 25. The opening 222 has a circular shape. In this embodiment, "circular shape" means a substantially perfect circular shape.

[0031] The wastegate port 223 is provided adjacent to the opening 222. In this embodiment, the opening 222 and the wastegate port 223 are formed in the same wall portion 222a. The wastegate port 223 is opened and closed by a wastegate valve 224. The wastegate valve 224 opens and closes the wastegate port 223 by an actuator 26 having a link mechanism 26a. By opening the wastegate port 223, the wastegate valve 224 prevents the gas pressure inside the turbine case 22 from becoming too high.

[0032] The communication pipe connection portion 221 has a sidewall portion 225 that surrounds the wastegate port 223 and the wastegate valve 224. The sidewall portion 225 has an inner circumferential surface 225a. The inner circumferential surface 225a surrounds the opening 222, the wastegate port 223, and the wastegate valve 224. For this reason, the inner circumferential surface 225a has a shape other than a circle. When viewed from the front-to-rear direction, the inner circumferential surface 225a may have, for example, a substantially elliptical shape or a substantially rectangular shape, but in this embodiment, the shape does not have an axis of symmetry.

[0033] Next, the structure of the exhaust communication pipe 25 will be described with reference to Figures 3 and 5 to 8. Figure 5 is a side view showing the structure of the exhaust communication pipe 25 of the engine 1 of this embodiment. Figure 6 is a view showing the structure of the first connecting member 60 of the engine 1 of this embodiment from the front (one side Y1 in the second direction Y).

[0034] As shown in FIGS. 3 and 5 , the exhaust communication pipe 25 has a first connecting member 60 and a second connecting member 70. The first connecting member 60 is connected to the turbocharger 20. The second connecting member 70 connects the first connecting member 60 to the exhaust gas purification device 40. In this embodiment, the second connecting member 70 has a bellows portion 71 and a downstream connecting portion 72. The bellows portion 71 and the downstream connecting portion 72 are formed of a metal such as stainless steel. The exhaust communication pipe 25 further has metal connecting bands (also referred to as V-clamps) 75a, 75b, and 75c (see FIG. 3 ). The connecting band 75a connects the first connecting member 60 to the bellows portion 71. The connecting band 75b connects the bellows portion 71 to the downstream connecting portion 72. The connecting band 75c connects the downstream connecting portion 72 to the DPF device 41 of the exhaust gas purification device 40.

[0035] The first connecting member 60 is formed by, for example, casting, etc. The first connecting member 60 has an upstream end 61 connected to the turbocharger 20 and a downstream end 62 connected to the second connecting member 70.

[0036] As shown in FIG. 6, the downstream end portion 62 has an inner circumferential surface 62a with a circular cross section. On the other hand, the upstream end portion 61 has an inner circumferential surface 61a with an irregular shape different from the inner circumferential surface 62a of the downstream end portion 62. The inner circumferential surface 61a has substantially the same shape as the inner circumferential surface 225a of the communication pipe connection portion 221 of the turbocharger 20 (see FIG. 4) when viewed from the front-rear direction. Therefore, while a portion of the inner circumferential surface of the first connecting member 60 has an irregular shape different from a circular shape, the inner circumferential surface of the second connecting member 70 can be circular. Therefore, for example, compared to when the inner circumferential surface of the second connecting member 70 has an irregular shape, it is possible to suppress an increase in pressure loss when exhaust gas passes through the inside of the exhaust communication pipe 25. Note that the flow path cross-sectional area of the upstream end portion 61 (the area of the region surrounded by the inner circumferential surface 61a) is larger than the flow path cross-sectional area of the downstream end portion 62 (the area of the region surrounded by the inner circumferential surface 62a).

[0037] 7 is a cross-sectional view taken along line VII-VII in FIG. 5. As shown in FIG. 7, the first connecting member 60 has a right side portion 601 that faces the left side portion 2a of the engine body 2. In this embodiment, the outer surface of the right side portion 601 has a flat portion 601a that follows the left side portion 2a of the engine body 2. Therefore, the first connecting member 60 can be disposed close to the engine body 2, which prevents the overall size of the engine 1 from increasing in the width direction (first direction X). The right side portion 601 is an example of the "second side portion" in the present invention.

[0038] The first connecting member 60 also has a left side portion 602 facing the right side portion 601. In this embodiment, the outer surface of the left side portion 602 has a flat surface portion 602a that follows the flat surface portion 601a of the right side portion 601. In other words, the outer surface of the left side portion 602 has a flat surface portion 602a that follows the left side portion 2a of the engine body 2. This further prevents the entire engine 1 from becoming larger in the width direction (first direction X).

[0039] In this embodiment, the right side portion 601 and the left side portion 602 are formed to have a substantially constant thickness. The right side portion 601 and the left side portion 602 include portions 601b and 602b, respectively, that extend along the left side portion 2a of the engine body 2.

[0040] As shown in FIGS. 5 to 7, in this embodiment, the first connecting member 60 has a curved portion 63 disposed between the upstream end 61 and the downstream end 62. The curved portion 63 has an inner portion 631 located on the inside of the bend and an outer portion 632 located on the outside of the bend. As shown in FIG. 7, the inner surface 631a of the inner portion 631 has a cross section including a straight portion 631b. Therefore, unlike when the inner surface 631a of the inner portion 631 is formed so as to protrude toward the inside of the bend, for example, as shown by the two-dot chain line in FIG. 7, the radius of curvature when the exhaust gas passes through the curved portion 63 can be prevented from becoming too small. This makes it easier for the exhaust gas to flow smoothly.

[0041] Furthermore, the outer surface 632a of the outer portion 632 has a cross section that includes a straight portion 632b. Therefore, unlike when, for example, the outer surface 632a of the outer portion 632 is formed so as to protrude outward from the bend, it is possible to prevent the length of the first connecting member 60 in the second direction Y from increasing.

[0042] In this embodiment, the inner portion 631 and the outer portion 632 are formed to have a substantially constant thickness. The curved portion 63 has a substantially rectangular cross section.

[0043] 8 is a cross-sectional view taken along line VIII-VIII in FIG. 6. As shown in FIGS. 5 and 8, the upstream end 61 of the first connecting member 60 opens in one direction (one side Y1 in the second direction Y). The downstream end 62 also opens in one direction (one side Y1 in the second direction Y). That is, the first connecting member 60 is curved by approximately 180°. Therefore, when the first connecting member 60 expands due to the heat of exhaust gas while the engine 1 is running, the upstream portion (here, the upper portion) of the first connecting member 60 extends rearward (the other side Y2 in the second direction Y) with respect to the turbocharger 20, while the downstream portion (here, the lower portion) of the first connecting member 60 extends forward (one side Y1 in the second direction Y) with respect to the curved portion 63. This prevents the end face 62b of the downstream end 62 from being displaced in the front-rear direction (the second direction Y) relative to the end face 61b of the upstream end 61. As a result, it is possible to prevent the position of the end face 62b of the downstream end 62 from moving in the front-rear direction (second direction Y).

[0044] Furthermore, the end face 61b of the upstream end 61 and the end face 62b of the downstream end 62 are disposed on approximately the same plane S60. Therefore, when manufacturing the first connecting member 60, surface processing of the end faces 61b and 62b can be performed simultaneously. Furthermore, the positional accuracy (manufacturing error) of the end face 62b relative to the end face 61b can be improved. Therefore, when assembling the engine 1, the positional accuracy of the end face 62b relative to the exhaust gas purification device 40 can be improved, thereby preventing difficulties in attaching the second connecting member 70 to the exhaust gas purification device 40. In other words, assembly of the engine 1 becomes easier.

[0045] Furthermore, by arranging the end face 61b of the upstream end 61 and the end face 62b of the downstream end 62 on approximately the same plane S60, it is possible to further prevent the end face 62b of the downstream end 62 from moving in the front-to-rear direction (second direction Y) even when the first connecting member 60 expands due to the heat of exhaust gas while the engine 1 is running. Therefore, it is possible to reduce the force acting on the second connecting member 70.

[0046] Furthermore, in this embodiment, as described above, the second connecting member 70 has the bellows portion 71 that is connected to the first connecting member 60. The bellows portion 71 is a pipe having a bellows shape. Therefore, the bellows portion 71 can absorb the thermal expansion of the exhaust connecting pipe 25 caused by the high-temperature exhaust gas, and therefore, damage to the exhaust connecting pipe 25 can be easily prevented.

[0047] FIG. 9 is a view showing the structure of the turbocharger 20 and the exhaust communication pipe 25 of the engine 1 of this embodiment from the rear (the other side Y2 in the second direction Y). As shown in FIGS. 3 and 9, the second connecting member 70 is arranged above or below (below in this case) the turbocharger 20. Therefore, for example, compared to when the second connecting member 70 is arranged to the side of the turbocharger 20 (one side X1 in the first direction X), the second connecting member 70 can be arranged closer to the engine body 2. This makes it possible to prevent the entire engine 1 from becoming larger in the width direction (first direction X). In this embodiment, the entire bellows portion 71 and a part of the downstream connecting portion 72 of the second connecting member 70 are arranged below the turbocharger 20.

[0048] The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments and can be embodied in various forms without departing from the spirit and scope of the present invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above embodiments. For example, some components may be omitted from all components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. The drawings mainly show each component schematically to facilitate understanding, and the thickness, length, number, spacing, etc. of each component shown may differ from the actual components due to the convenience of drawing. Furthermore, the materials, shapes, dimensions, etc. of each component shown in the above embodiments are merely examples and are not particularly limited. Various modifications are possible within a scope that does not substantially deviate from the effects of the present invention.

[0049] For example, in the above embodiment, an example has been shown in which the upstream end 61 of the first connecting member 60 opens in one direction and the downstream end 62 opens in the other direction. That is, although an example has been shown in which the first connecting member 60 is curved by approximately 180 degrees, the present invention is not limited to this. The first connecting member 60 may be curved by less than 180 degrees or by more than 180 degrees.

[0050] In the above embodiment, the end face 61b of the upstream end 61 and the end face 62b of the downstream end 62 of the first connecting member 60 are arranged on approximately the same plane S60, but the present invention is not limited to this. The end face 61b of the upstream end 61 and the end face 62b of the downstream end 62 of the first connecting member 60 do not have to be arranged on approximately the same plane S60.

[0051] In the above embodiment, the second connecting member 70 is configured by two pipes (the bellows portion 71 and the downstream connecting portion 72), but the present invention is not limited to this. The second connecting member 70 may be configured by one pipe or three or more pipes.

[0052] In the above embodiment, the multiple pipes (first connecting member 60, bellows portion 71, downstream connecting portion 72) that make up the exhaust communication pipe 25 are connected using connecting bands 75a and 75b, but the present invention is not limited to this. For example, the pipes may be connected by welding them together.

[0053] In the above embodiment, the exhaust gas purification device 40 is fixed to the engine body 2, but the present invention is not limited to this. The engine body 2 and the exhaust gas purification device 40 may be fixed separately to the chassis. [Industrial Applicability]

[0054] The present invention is useful in the field of engines. [Explanation of symbols]

[0055] 1: Engine 2: Engine body 2a: Left side (first side) 20: Turbocharger 25: Exhaust connecting pipe 40: Exhaust gas purification device (aftertreatment device) 60: First connecting member 61: Upstream end 61a: Inner peripheral surface 61b: End face 62: Downstream end 62a: Inner surface 62b: End face 63: Curved section 70: Second connecting member 71: Bellows section 221: Connecting pipe connection 222: Opening 223: Wastegate port 224: Wastegate valve 225a: Inner peripheral surface 601: Right side (second side) 601a: Flat part 631: Inner part 631a: Inner surface 631b: Straight section S60: Same plane

Claims

1. The engine body and a supercharger connected to the engine body; an aftertreatment device that purifies exhaust gas discharged from the turbocharger; an exhaust communication pipe connecting the turbocharger and the aftertreatment device; Equipped with The exhaust communication pipe is a first connecting member connected to the turbocharger; a second connecting member that connects the first connecting member to the post-processing device; Including, The downstream end of the first connecting member has an inner circumferential surface with a circular cross section, the upstream end of the first connecting member has an inner circumferential surface having a cross section with a modified shape different from that of the inner circumferential surface of the downstream end, the second connecting member has a bellows-shaped bellows portion connected to the downstream end of the first connecting member, The engine, wherein the bellows portion is disposed above or below the supercharger.

2. the engine body has a first side portion on which the supercharger is disposed, the first connecting member has a second side portion opposite the first side portion; The engine of claim 1 , wherein an outer surface of the second side has a planar portion along the first side.

3. The first connecting member has a curved portion disposed between the upstream end and the downstream end, the curved portion has an inner portion located on the inside of the bend, 3. An engine according to claim 1 or claim 2, wherein the inner surface of the inner portion has a cross section having a straight portion.

4. the first connecting member has a curved portion disposed between the upstream end and the downstream end, The upstream end is open in one direction, The downstream end portion is open in the one direction, The engine according to claim 1 or 2, wherein the second connecting member is disposed above or below the supercharger.

5. The engine according to claim 4 , wherein an end surface of the upstream end portion and an end surface of the downstream end portion are disposed on substantially the same plane.

6. The engine according to claim 1 , wherein the aftertreatment device is fixed to the engine body.

7. The turbocharger is a connecting pipe connection portion connected to the exhaust connecting pipe; an opening disposed inside the communication pipe connection portion and through which the exhaust gas passes; a wastegate port adjacent to the opening and opened and closed by a wastegate valve; and The engine according to any one of claims 1 to 6, wherein the communication pipe connection portion has an inner circumferential surface having a cross section that is an irregular shape different from a circular shape.

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