diesel engine

Abstract

To provide a technique for improving maintainability even when a diesel engine includes both of a DPF and an SCR as an exhaust gas aftertreatment device.SOLUTION: A diesel engine 1 includes an exhaust gas aftertreatment device 10 for purifying exhaust gas. The exhaust gas aftertreatment device 10 includes a first case and a second case. The first case is disposed above a cylinder head 3. The second case is disposed on one side in an engine longitudinal direction of the first case so as to extend in an engine width direction orthogonal to the engine longitudinal direction and a vertical direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a diesel engine, and more particularly to a diesel engine equipped with an exhaust aftertreatment device.

Background Art

[0002] Conventionally, in a diesel engine, as an exhaust aftertreatment device, a DPF (Diesel Particulate Filter) for collecting particulate matter in exhaust gas and an SCR (Selective Catalytic Reduction) for reducing NOx in exhaust gas are provided in the exhaust passage, and exhaust gas discharged from the engine is widely purified.

[0003] For example, Patent Document 1 discloses an exhaust gas purification device that includes a DPF and an SCR, and the DPF and the SCR are arranged side by side in the engine front-rear direction in a posture extending in the engine width direction and disposed above the engine.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, there are many parts that require regular maintenance (hereinafter, also referred to as "maintenance parts"), such as injectors and valves, on the upper part of the engine. Nevertheless, if the DPF and SCR are arranged above the engine as in the above Patent Document 1, when inspecting, repairing, replacing, etc. the maintenance parts, the DPF and / or SCR must be removed one by one, which makes it difficult to perform maintenance efficiently. ​

[0006] The present invention has been made in view of the above, and its objective is to provide a technology that improves maintainability even when a diesel engine is equipped with both a DPF and an SCR as an exhaust aftertreatment device. [Means for solving the problem]

[0007] To achieve the aforementioned objective, the diesel engine according to the present invention incorporates ingenious design features in the layout of the exhaust aftertreatment device having a DPF and an SCR.

[0008] A diesel engine according to one embodiment is a diesel engine equipped with an exhaust aftertreatment device for purifying exhaust gases. The exhaust aftertreatment device has a first case and a second case. The first case is positioned above the cylinder head, and the second case is positioned on one side of the engine's longitudinal direction compared to the first case, and extends in the engine's width direction perpendicular to the engine's longitudinal direction and vertical direction. [Effects of the Invention]

[0009] As described above, the diesel engine according to the present invention can improve maintainability even when equipped with both a DPF and an SCR as exhaust aftertreatment devices. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic perspective view showing a diesel engine according to an embodiment of the present invention. [Figure 2] Figure 1 is a schematic plan view showing the main components of the diesel engine. [Figure 3] This is a schematic perspective view showing the main components of a diesel engine. [Figure 4] Figure 3 is a schematic plan view showing the main components of the diesel engine. [Figure 5] This is a schematic perspective view showing the main components of a diesel engine. [Figure 6] This is a schematic perspective view showing the main components of a diesel engine. [Figure 7] Figure 1 is a schematic side view of the diesel engine, taken from the right side in the engine width direction, showing the main components of the engine. [Figure 8] Figure 5 is a schematic side view of the diesel engine, taken from the right side in the engine width direction, showing the main components of the engine. [Figure 9] Figure 1 is a schematic perspective view showing the right end of the SCR in the engine width direction in a diesel engine. [Figure 10] Figure 1 is a schematic perspective view showing the bracket in the diesel engine. [Figure 11] Figure 5 is a schematic perspective view showing the bracket in a diesel engine. [Figure 12] Figure 1 is a schematic front view of the diesel engine, showing the main components as seen from the front in the engine's longitudinal direction. [Figure 13] Figure 5 is a schematic front view of the diesel engine, showing the main components as seen from the front in the engine's longitudinal direction. [Figure 14] Figure 1 is a schematic perspective view showing the mounting configuration of the first bracket member in the diesel engine. [Figure 15] Figure 5 is a schematic perspective view showing the mounting configuration of the first bracket member in the diesel engine. [Figure 16] This is a schematic plan view of a conventional diesel engine. [Modes for carrying out the invention]

[0011] The embodiments for carrying out the present invention will be described below with reference to the drawings. In the following description, the direction parallel to the crankshaft CS (see dashed line in Figure 1) will be referred to as the engine longitudinal direction, and the direction perpendicular to the engine longitudinal direction and the vertical direction will be referred to as the engine width direction. In each figure, arrow Fw indicates the front side in the engine longitudinal direction, arrow Rh indicates the right side in the engine width direction, and arrow Up indicates the upper side in the vertical direction.

[0012] FIG. 1 is a perspective view schematically showing a diesel engine 1 according to an embodiment of the present invention, and FIG. 2 is a plan view schematically showing a main part of the diesel engine 1. As shown in FIGS. 1 and 2, this diesel engine 1 includes an engine main body portion 1a in which a cylinder head 3 is fastened to the upper part of a cylinder block 2, an exhaust manifold (not shown), an intake manifold (not shown), a flywheel (not shown) housed in a flywheel housing 5, a cooling fan 7, an EGR device (not shown), an intake throttle device (not shown), a turbocharger (not shown), and an exhaust aftertreatment device 10 for purifying exhaust gas.

[0013] The cylinder block 2 incorporates a plurality of pistons (not shown) that reciprocate up and down in a plurality of cylinders, and a crankshaft (crankshaft) CS that is connected to the pistons via connecting rods (not shown). An oil pan 4 for storing oil that circulates inside the diesel engine 1 and lubricates various parts is fixed to the lower part of the cylinder block 2.

[0014] An intake manifold is connected to the right side in the engine width direction of the cylinder head 3, while an exhaust manifold is connected to the left side in the engine width direction. That is, the diesel engine 1 of this embodiment is configured such that the left side in the engine width direction is the exhaust side and the right side in the engine width direction is the intake side. A head cover 3a is fixed to the upper part of the cylinder head 3.

[0015] As shown in FIG. 1, a flywheel housing 5 for housing a flywheel is provided on the rear side in the engine front-rear direction of the engine main body portion 1a. On the other hand, as shown in FIG. 2, a cooling fan 7 is provided on the front side in the engine front-rear direction of the engine main body portion 1a. The cooling fan 7 is configured to rotate when rotational power is transmitted from the crankshaft CS.

[0016] Furthermore, the diesel engine 1 of this embodiment is equipped with an EGR (Exhaust Gas Recirculation) device, which recirculates a portion of the exhaust gas discharged from each combustion chamber through the exhaust port to the exhaust manifold back to the intake side. By mixing a portion of the exhaust gas with the intake air in this way, it is possible to lower the combustion temperature and reduce nitrogen oxides (NOx) in the exhaust gas.

[0017] A turbocharger is provided on the exhaust side of the diesel engine 1. Fresh air, which has been filtered by an air cleaner (not shown), is compressed by the turbocharger, then sent to the intake manifold via the intake throttle device on the intake side. There, it is mixed with the recirculated exhaust gas in the intake manifold before being supplied to each cylinder.

[0018] The exhaust aftertreatment device (hereinafter also referred to as "ATD") 10 comprises a DPF (Diesel Particulate Filter) 20, an SCR (Selective Catalytic Reduction) 30, an SCR pipe 40 connecting the DPF 20 and the SCR 30, and a dosing module (urea injection device) 50 located upstream of the SCR pipe 40.

[0019] The DPF20 has a structure in which an oxidation catalyst (not shown) and a soot filter (not shown) are arranged in series and housed in a DPF casing 21. In this DPF20, when exhaust gas flows into the DPF casing 21 from the exhaust inlet (not shown) and passes through the soot filter, particulate matter contained in the exhaust gas is collected in the soot filter. Furthermore, when the exhaust gas passes through the oxidation catalyst, if the exhaust gas temperature exceeds the regeneration temperature, the oxygen heated to a high temperature by the action of the oxidation catalyst burns and removes the particulate matter accumulated in the soot filter, thereby regenerating the soot filter.

[0020] The SCR30 has a structure in which an SCR catalyst (not shown) for selective catalytic reduction of urea and an oxidation catalyst (not shown) are arranged in series and housed in an SCR casing 31. The upstream end of the SCR casing 31 is connected to the downstream end of the DPF casing 21 via a relatively long SCR pipe 40. In the SCR pipe 40, ammonia gas is generated when urea water is injected from the dosing module 50 into the exhaust gas flowing in from the DPF 20, and mixing of the exhaust gas and ammonia gas is promoted as it passes through the relatively long SCR pipe 40. In the SCR30, as the exhaust gas and ammonia gas flowing into the SCR casing 31 pass through the SCR catalyst, nitrogen oxides in the exhaust gas chemically react with ammonia and are reduced to nitrogen and water, and ammonia is reduced as it passes through the oxidation catalyst.

[0021] In this way, exhaust gas from which particulate matter has been removed by the DPF20 and nitrogen oxides have been reduced by the SCR30 is discharged from the tailpipe60 located at the downstream end of the SCR casing31.

[0022] -DPF and SCR layout- Figure 16 is a schematic plan view showing an example of a conventional diesel engine 101. The conventional diesel engine 101 is similar to the diesel engine 1 of this embodiment in that, as shown in Figure 16, it comprises an engine body 101a, a flywheel housing 105, a cooling fan 107, and an exhaust aftertreatment device 110 for purifying exhaust gases.

[0023] However, in conventional diesel engines 101, the DPF 120 and SCR 130 of the exhaust aftertreatment device 110, which are connected by an SCR pipe 140, are positioned side by side in the front-to-back direction of the engine, extending in the width direction of the engine, and are located on the upper side of the engine body 101a.

[0024] Incidentally, the upper part of the engine body 101a contains numerous components that require regular maintenance, such as injectors and valves (hereinafter also referred to as "maintenance parts"). Nevertheless, if the DPF 120 and SCR 130 are placed on the upper side of the engine body 101a, as in the conventional diesel engine 101, the upper part of the engine body 101a will be hidden, as shown in Figure 16. This presents a problem in that it becomes difficult to perform maintenance efficiently, as the DPF 120 and / or SCR 130 must be removed each time for inspection, repair, or replacement of maintenance parts.

[0025] Therefore, in the diesel engine 1 of this embodiment, the layout of the DPF 20 and SCR 30 is carefully designed. Specifically, in the diesel engine 1 of this embodiment, as shown in Figure 2, the DPF 20 is positioned above the engine body 1a (more precisely, above the head cover 3a) so as to extend in the engine's longitudinal direction, while the SCR 30 is positioned above the flywheel housing 5, which is further rear (on one side) than the DPF 20 in the engine's longitudinal direction, so as to extend in the engine's width direction. The SCR 30 is positioned above the flywheel housing 5 at a lower position than the DPF 20, and its central part in the engine's width direction is positioned so as to overlap with the crankshaft CS in a plan view.

[0026] Thus, the DPF20 is positioned above the engine body 1a and extends in the engine's longitudinal direction, while the SCR30 is positioned further rear than the DPF20 in the engine's longitudinal direction and extends in the engine's width direction. As shown in Figure 2, the DPF20 and SCR30 are arranged to form approximately an L-shape in a plan view.

[0027] As a result, the DPF20 and SCR30 are arranged in a roughly L-shape, and compared to a conventional diesel engine 101 in which the DPF120 and SCR130 extending in the engine width direction are arranged in the engine front-to-rear direction, the area of ​​the upper part of the engine body 1a that is exposed (not covered by the DPF20 and SCR30) can be increased, as shown in Figure 2. This allows for efficient inspection, repair, and replacement of maintenance parts without removing the DPF20 and / or SCR30, thus improving maintainability even when the exhaust aftertreatment device 10 is equipped with a DPF20 and SCR30.

[0028] -SCR pipe layout- The DPF20 has an exhaust outlet 22 (see Figure 12) at the front end (front end 20a) (the end furthest from the SCR30) for discharging exhaust gas after collecting particulate matter. The SCR30 has an exhaust inlet 32 ​​at the right end (right end 30a) in the engine width direction, while a tailpipe 60 is provided at the left end in the engine width direction. Thus, in the diesel engine 1, the exhaust outlet 22 of the DPF20 and the exhaust inlet 32 ​​of the SCR30 are connected by an SCR pipe 40, as shown in Figure 1.

[0029] Incidentally, the tailpipe 60, which is the downstream end of the ATD10, is connected to the vehicle body's exhaust pipe (not shown), so the tailpipe 60 is set in various positions on the SCR30 depending on the vehicle body's layout. In particular, whether the tailpipe 60 is set on the left or right side of the diesel engine 1 is very important from the vehicle's perspective, and it is desirable to be able to set the tailpipe 60 on either the left or right side of the diesel engine 1.

[0030] Figure 3 is a schematic perspective view showing the main components of diesel engine 1A, and Figure 4 is a schematic plan view showing the main components of diesel engine 1A. Note that diesel engine 1A is almost identical to diesel engine 1, and the same reference numerals are used for common components.

[0031] As shown in Figure 3, in the ATD10A of diesel engine 1A, the SCR30 is mounted symmetrically to the SCR30 of diesel engine 1. Therefore, the SCR30 has a tailpipe 60 at the right end in the engine width direction, while an exhaust inlet 32 ​​is provided at the left end in the engine width direction. Thus, in diesel engine 1A, the exhaust outlet 22 of the DPF20 and the exhaust inlet 32 ​​of the SCR30 are connected by an SCR pipe 40', as shown in Figure 1.

[0032] Thus, in diesel engine 1, the exhaust outlet 22 of the DPF 20 and the exhaust inlet 32 ​​of the SCR 30 are connected by an SCR pipe 40, whereas in diesel engine 1A, the exhaust outlet 22 of the DPF 20 and the exhaust inlet 32 ​​of the SCR 30 are connected by an SCR pipe 40' which is different from the SCR pipe 40. However, despite diesel engine 1 and diesel engine 1A having almost the same configuration, it is uneconomical to manufacture an SCR pipe 40' which is completely different from the SCR pipe 40.

[0033] Therefore, in this embodiment, the SCR pipes 40, 40' connecting the exhaust outlet 22 of the DPF 20 and the exhaust inlet of the SCR 30 have a straight pipe section 42 that extends in the front-rear direction of the engine at a position corresponding to the center in the engine width direction.

[0034] More specifically, both SCR pipe 40 and SCR pipe 40' are connected to the exhaust outlet 22 of the DPF 20 and have an upstream pipe section 41 that extends slightly forward in the engine's longitudinal direction before bending 180 degrees and extending to the rear in the engine's longitudinal direction. Both SCR pipe 40 and SCR pipe 40' are connected to the downstream end of the upstream pipe section 41 and have a straight pipe section 42 that extends in the engine's longitudinal direction at a position corresponding to the center in the engine's width direction. In this embodiment, as described above, the center of the SCR 30 in the engine's width direction is positioned to overlap with the crankshaft CS in a plan view. Therefore, the straight pipe section 42 that extends in the engine's longitudinal direction to overlap with the crankshaft CS in a plan view forms a roughly T-shape with the SCR 30 in a plan view.

[0035] As shown in Figures 1 and 2, the SCR pipe 40 has a downstream pipe section 43 which is connected to the downstream end of the straight pipe section 42, curves to the right in the engine width direction, extends to the right in the engine width direction above the SCR 30, then curves downward and connects to the exhaust inlet 32 ​​of the SCR 30.

[0036] In contrast, the SCR pipe 40' has a downstream pipe section 43' which is connected to the downstream end of the straight pipe section 42, curves to the left in the engine width direction, extends to the left in the engine width direction above the SCR 30, then curves downward and connects to the exhaust inlet 32 ​​of the SCR 30, as shown in Figures 3 and 4.

[0037] In this way, by connecting the exhaust outlet 22 of the DPF 20 and the upstream end of the straight pipe section 42 with the upstream pipe section 41, the exhaust gas that has collected particulate matter and is discharged from the exhaust outlet 22 of the DPF 20 can be flowed to the vicinity of the SCR 30 via the upstream pipe section 41 and the straight pipe section 42 in both the SCR pipe 40 and the SCR pipe 40'.

[0038] Thus, the straight pipe section 42 extends in the front-to-rear direction of the engine at a position corresponding to the center in the engine width direction, forming a T-shape with the SCR30 in a plan view. This allows the positional relationship between the downstream end of the straight pipe section 42 and the SCR30 to always be approximately the same. Therefore, regardless of where the exhaust inlet 32 ​​of the SCR30 is located in the engine width direction of the SCR30, it can be accommodated simply by changing the shape and length of the downstream pipe sections 43, 43'. This means that the upstream pipe section 41 and the straight pipe section 42 can be used with the same layout, regardless of changes in the shape or specifications of the SCR30.

[0039] Furthermore, since the downstream end of the straight pipe section 42 is always located near the center of the SCR30, whether the exhaust inlet 32 ​​of the SCR30 is located at the right end in the engine width direction of the SCR30, as in diesel engine 1, or at the left end in the engine width direction of the SCR30, as in diesel engine 1A, it is not necessary to make the downstream pipe sections 43, 43' extremely long. This increases the design flexibility of the SCR30 while suppressing an increase in the manufacturing cost of the SCR pipe 40.

[0040] Furthermore, by positioning the SCR30 lower than the DPF20, for example, SCR pipes 40,40' that extend in the front-to-rear direction of the engine at the same height as the DPF20 can be extended above the SCR30, thereby promoting the mixing of exhaust gas and ammonia gas (urea) as it passes through these relatively long SCR pipes 40,40'.

[0041] -Fixed structure of DPF and SCR- Figure 5 is a schematic perspective view showing the main components of diesel engine 1B, and Figure 6 is a schematic perspective view showing the main components of diesel engine 1C. Note that diesel engine 1B is almost identical to diesel engine 1, and diesel engine 1C is almost identical to diesel engine 1A, so the same reference numerals are used for common components.

[0042] The difference between diesel engine 1 and diesel engine 1B is that diesel engine 1B is a higher output specification than diesel engine 1, and consequently, the DPF20' of diesel engine 1B is longer in the engine-longitudinal direction than the DPF20 of diesel engine 1, and the SCR30' of diesel engine 1B is longer in the engine-width direction than the SCR30 of diesel engine 1. Similarly, the difference between diesel engine 1A and diesel engine 1C is that diesel engine 1C is a higher output specification than diesel engine 1A, and consequently, the DPF20' of diesel engine 1C is longer in the engine-longitudinal direction than the DPF20 of diesel engine 1A, and the SCR30' of diesel engine 1C is longer in the engine-width direction than the SCR30 of diesel engine 1A.

[0043] However, despite the fact that diesel engine 1 and diesel engine 1B have almost identical configurations except for the differing lengths of the DPF20,20' and SCR30,30', it is uneconomical to employ completely different fixed structures for the DPF20,20' and SCR30,30'. The same applies to diesel engine 1A and diesel engine 1C.

[0044] Therefore, in this embodiment, the DPF20,20' and SCR30,30' are fixed to the engine body 1a using a substantially similar fixing structure. Below, the fixing structures of the DPF20,20' and SCR30,30' in diesel engine 1 and diesel engine 1B will be described as representative examples.

[0045] Figure 7 is a schematic side view of the main parts of diesel engine 1, viewed from the right side in the engine width direction. Figure 8 is a schematic side view of the main parts of diesel engine 1B, viewed from the right side in the engine width direction. Figure 9 is a schematic perspective view of the right end of the SCR30 in diesel engine 1, viewed from the right side in the engine width direction. Note that in Figures 7 and 8, the SCR pipes 40 and 40' are omitted from the illustration for clarity.

[0046] In the diesel engine 1, the DPF 20 is supported at two points on the cylinder head 3 by fixing its front end 20a and its rear end (rear end) 20b in the engine's longitudinal direction to the cylinder head 3. The SCR 30 is also supported at two points on the engine body 1a by fixing its right end (right end) 30a in the engine's width direction to the flywheel housing 5, and fixing a flange portion 33 formed on the left side of the SCR casing 31 in the engine's width direction to the cylinder head 3.

[0047] On the other hand, in the diesel engine 1B, the DPF 20' is supported at two points by the cylinder head 3, with its front end 20a' and rear end 20b' fixed to the cylinder head 3. In addition, the SCR 30' is supported at two points by the engine body 1a, with its right end 30a' fixed to the flywheel housing 5, and its flange portion 33', formed slightly to the left in the engine width direction, fixed to the cylinder head 3.

[0048] More specifically, in diesel engine 1, the front end portion 20a of the DPF 20 is fixed to the front end of the cylinder head 3 via a DPF bracket 90 that is bolted to the front end portion 20a and the front end of the cylinder head 3, as shown in Figure 7. Similarly, in diesel engine 1B, the front end portion 20a' of the DPF 20' is fixed to the front end of the cylinder head 3 via a DPF bracket 90 that is bolted to the front end portion 20a' and the front end of the cylinder head 3, as shown in Figure 8.

[0049] On the other hand, in diesel engine 1, the right end portion 30a of SCR30 is fixed to the right end portion of flywheel housing 5 via an SCR bracket 91 that is bolted to the right end portion 30a and the right end portion of flywheel housing 5, as shown in Figures 7 and 9. Similarly, in diesel engine 1B, the right end portion 30a' of SCR30' is fixed to the right end portion of flywheel housing 5 via an SCR bracket 91 that is bolted to the right end portion 30a' and the right end portion of flywheel housing 5, as shown in Figure 8.

[0050] In contrast, in the diesel engine 1, the rear end portion 20b of the DPF 20 and the flange portion 33 of the SCR 30 are fixed to the rear end portion of the cylinder head 3 via a common bracket 70, as shown in Figure 7.

[0051] In this way, by fixing the DPF20 and SCR30 to the cylinder head 3 via a common bracket 70, it is possible to reduce the number of parts, resulting in weight reduction and cost savings compared to fixing them separately to the cylinder head 3 via separate brackets.

[0052] Furthermore, in the diesel engine 1B, as shown in Figure 8, the rear end portion 20b' of the DPF 20' and the flange portion 33' of the SCR 30' can be fixed to the rear end portion of the cylinder head 3 via a common bracket 70 used in the diesel engine 1. In other words, the bracket 70 is configured to be applicable to DPF 20, 20' and SCR 30, 30' of different lengths. The bracket 70 will be described in detail below.

[0053] The bracket 70 includes a first bracket member 71 that fixes the SCR30,30' to the cylinder head 3, and a second bracket member 72 that fixes the rear ends 20b,20b' (the ends closer to the SCR30,30') of the DPF20,20' to the first bracket member 71. In other words, the rear ends 20b,20b' of the DPF20,20' are fixed to the cylinder head 3 via the second bracket member 72 and the first bracket member 71.

[0054] As shown in Figures 7 and 8, the lower end 71a of the first bracket member 71 is bolted to the rear end of the cylinder head 3. The first bracket member 71 also has a flat mounting surface 71b formed at its upper end.

[0055] On the other hand, as shown in Figures 7 and 8, the second bracket member 72 has a substantially rectangular base portion 73 that is attached to the upper side of the flat mounting surface 71b of the first bracket member 71, and a mounting portion 75 that rises perpendicularly from the end of the base portion 73 so as to form a substantially L-shape in cross-section with the base portion 73, and is attached to the rear ends 20b, 20b' of the DPF 20, 20'. Note that the second bracket member 72 may have any configuration as long as it has at least a base portion 73 and a mounting portion 75 that form a substantially L-shape in cross-section.

[0056] Figure 10 is a schematic perspective view showing the bracket 70 in diesel engine 1, and Figure 11 is a schematic perspective view showing the bracket 70 in diesel engine 1B. The base portion 73 is configured to be attached to the first bracket member 71 by bolting in either orientation, as shown in Figures 7 and 10, where the inside of the L-shape faces the SCR30 side (the mounting portion 75 is on the front side in the engine's longitudinal direction and the base portion 73 is on the rear side in the engine's longitudinal direction), or as shown in Figures 8 and 11, where the inside of the L-shape faces the DPF20 side (the base portion 73 is on the front side in the engine's longitudinal direction and the mounting portion 75 is on the rear side in the engine's longitudinal direction). Furthermore, the mounting portion 75 is configured to be attached to the rear ends 20b, 20b' of the DPF 20, 20' by bolt fastening on either the outer surface of the L-shape (the surface opposite to the base portion 73 of the mounting portion 75) as shown in Figures 7 and 10, or the inner surface of the L-shape (the surface on the same side as the base portion 73 of the mounting portion 75) as shown in Figures 8 and 11.

[0057] As described above, in both diesel engine 1 and diesel engine 1B, the front ends 20a, 20a' of the DPF 20, 20' are fixed to the front end of the cylinder head 3 via the DPF bracket 90. Since the DPF 20' of diesel engine 1B is longer in the engine longitudinal direction than the DPF 20 of diesel engine 1, as shown in Figures 7 and 10, the rear end 20b of the DPF 20 in diesel engine 1 stops before the SCR 30 in the engine longitudinal direction, whereas the rear end 20b' of the DPF 20' in diesel engine 1B overlaps with a part of the SCR 30' in a plan view, as shown in Figures 7 and 10. In other words, the rear ends 20b, 20b' of the DPF 20, 20' are closer to the SCR 30, 30' in diesel engine 1B than in diesel engine 1.

[0058] Therefore, in the diesel engine 1, as shown in Figures 7 and 10, the base portion 73 is bolted to the mounting surface 71b of the first bracket member 71 with the inner side of the L-shape facing the SCR 30 side, and the outer surface of the L-shape of the mounting portion 75 is bolted to the rear end portion 20b of the DPF 20, thereby allowing the relatively short DPF 20 to be fixed to the cylinder head 3 via the second bracket member 72 and the first bracket member 71.

[0059] In contrast, in the diesel engine 1B, as shown in Figures 8 and 11, the base portion 73 is bolted to the mounting surface 71b of the first bracket member 71 with the inner side of the L-shape facing the DPF 20 side, and the inner surface of the L-shape of the mounting portion 75 is bolted to the rear end portion 20b of the DPF 20, thereby allowing the relatively long DPF 20' to be fixed to the cylinder head 3 via the second bracket member 72 and the first bracket member 71.

[0060] Thus, the second bracket member 72 is configured such that by changing the mounting direction relative to the first bracket member 71, DPFs 20 and 20' of different lengths can be fixed to the first bracket member 71.

[0061] As a result, even if the lengths of the DPF20 and 20' differ, the DPF20 and 20' can be fixed to the cylinder head 3 using the same bracket 70 without changing the shape of the first bracket member 71 and the second bracket member 72. Therefore, even if the lengths of the DPF20 and 20' differ, there is no need to manufacture a dedicated bracket each time, thus suppressing an increase in manufacturing costs.

[0062] The base portion 73 may also be configured to be attached to the mounting surface 71b of the first bracket member 71 via a bolt inserted through an elongated hole (not shown) formed in the base portion 73. With this configuration, the distance between the mounting portion 75 and the rear ends 20b, 20b' of the DPF 20, 20' can be greatly adjusted by changing the orientation of the base portion 73. In addition, the elongated hole allows for fine adjustment of the distance between the mounting portion 75 and the rear ends 20b, 20b' of the DPF 20, 20', so that the same bracket 70 can be used to accommodate DPF 20, 20' of various lengths.

[0063] Figure 12 is a schematic front view of the main parts of diesel engine 1, viewed from the front in the engine's longitudinal direction, and Figure 13 is a schematic front view of the main parts of diesel engine 1B, viewed from the front in the engine's longitudinal direction. Figure 14 is a schematic perspective view showing the mounting configuration of the first bracket member 71 in diesel engine 1, and Figure 15 is a schematic perspective view showing the mounting configuration of the first bracket member 71 in diesel engine 1B. Note that in Figures 12 and 13, the DPF bracket 90 is omitted from the illustration for clarity.

[0064] As described above, in both diesel engine 1 and diesel engine 1B, the right ends 30a, 30a' of SCR30, 30' are fixed to the right end of the flywheel housing 5 via the SCR bracket 91. Since the SCR30' of diesel engine 1B is longer in the engine width direction than the SCR30 of diesel engine 1, as can be seen by comparing Figure 12 and Figure 13, the flange portion 33' of SCR30' in diesel engine 1B is further from the first bracket member 71 in the engine width direction than the flange portion 33 of SCR30 in diesel engine 1.

[0065] Therefore, in this embodiment, the first bracket member 71 is configured to be attachable either directly or via a spacer 80 to a mounting member 77 fixed to the flange portions 33, 33' of the SCR30, 30'. More specifically, in the diesel engine 1, as shown in Figures 12 and 14, a substantially arc-shaped mounting member 77 with a larger diameter than the flange portion 33 is bolted to the flange portion 33 of the SCR30, and the first bracket member 71 is directly bolted to this mounting member 77. This allows the relatively short flange portion 33 of the SCR30 to be connected to the first bracket member 71 and fixed to the cylinder head 3 via the first bracket member 71.

[0066] In contrast, in the diesel engine 1B, as shown in Figures 13 and 15, a mounting member 77 is bolted to the flange portion 33' of the SCR30', and a first bracket member 71 is bolted to the mounting member 77 via a spacer 80. This allows the relatively long flange portion 33' of the SCR30' to be connected to the first bracket member 71 and fixed to the cylinder head 3 via the first bracket member 71.

[0067] This allows the SCR30 and 30' to be fixed to the cylinder head 3 using the same bracket 70, even if their lengths are different.

[0068] (Other Embodiments) The present invention is not limited to its embodiments and can be implemented in various other ways without departing from its spirit or main features.

[0069] In the above embodiment, the cooling fan 7 side of the diesel engines 1, 1A, 1B, and 1C is positioned towards the front of the engine in the longitudinal direction, and the flywheel side is positioned towards the rear of the engine in the longitudinal direction. However, the longitudinal direction of the diesel engines 1, 1A, 1B, and 1C does not necessarily have to coincide with the longitudinal direction of the work vehicle on which the diesel engines 1, 1A, 1B, and 1C are mounted. For example, the diesel engines 1, 1A, 1B, and 1C may be mounted on the work vehicle such that their longitudinal direction coincides with the longitudinal direction of the work vehicle, or they may be mounted on the work vehicle such that their longitudinal direction coincides with the width direction of the work vehicle.

[0070] Furthermore, in the above embodiment, the cylinder head 3 was configured with the left side in the engine width direction as the exhaust side and the right side in the engine width direction as the intake side. However, the cylinder head 3 may also be configured with the right side in the engine width direction as the exhaust side and the left side in the engine width direction as the intake side.

[0071] Thus, the embodiments described above are merely illustrative in all respects and should not be interpreted restrictively. Furthermore, any modifications or changes that fall within the equivalent scope of the claims are all within the scope of the present invention.

[0072] <Notes on the invention> Specifically, the present invention relates to a diesel engine equipped with an exhaust aftertreatment device for purifying exhaust gases.

[0073] Furthermore, this diesel engine has an exhaust aftertreatment system comprising a DPF that collects particulate matter contained in the exhaust gas and an SCR that reduces nitrogen oxides contained in the exhaust gas by adding urea. The DPF is arranged to extend in the engine longitudinal direction, which is parallel to the crankshaft, while the SCR is arranged to extend in the engine width direction, which is perpendicular to the engine longitudinal direction and the vertical direction, on one side of the engine longitudinal direction relative to the DPF.

[0074] In this configuration, the DPF is positioned to extend in the longitudinal direction of the engine, while the SCR is positioned on one side of the engine in the longitudinal direction and extends in the width direction of the engine. As a result, the DPF and SCR are positioned to form a roughly T-shape or L-shape in a plan view.

[0075] As described above, since the DPF and SCR are arranged in a roughly T-shape or L-shape, even if the DPF and SCR are positioned above the engine, the exposed (uncovered) area of ​​the upper part of the engine can be increased compared to when the DPF and SCR are aligned in the same direction. This allows for efficient inspection, repair, and replacement of maintenance parts without removing the DPF and / or SCR, thus improving maintainability even when both a DPF and SCR are equipped as exhaust aftertreatment devices.

[0076] Furthermore, in the above-mentioned diesel engine, the DPF is provided with an exhaust outlet at the end furthest from the SCR in the engine's longitudinal direction for discharging exhaust gas after collecting particulate matter, and the SCR pipe connecting the exhaust outlet of the DPF and the exhaust inlet of the SCR may have a straight pipe section extending in the engine's longitudinal direction at a position corresponding to the center in the engine's width direction.

[0077] With this configuration, for example, if the SCR pipe is configured with the upstream pipe section being upstream of the straight pipe section and the downstream pipe section being downstream of the straight pipe section, connecting the exhaust outlet of the DPF and the upstream end of the straight pipe section with the upstream pipe section allows the exhaust gas, after collecting particulate matter, discharged from the exhaust outlet of the DPF to flow through the upstream pipe section and the straight pipe section to the vicinity of the SCR.

[0078] Thus, since the straight pipe section extends in the front-to-rear direction of the engine at a position corresponding to the center in the engine width direction, it is possible to accommodate the location of the SCR's exhaust inlet in the engine width direction simply by changing the shape and length of the downstream pipe section. Therefore, the same layout of the upstream pipe section and straight pipe section can be used regardless of changes in the shape or specifications of the SCR.

[0079] Furthermore, since the downstream end of the straight pipe section is always located in the center in the engine width direction, even if the exhaust inlet of the SCR is located on one or the other side of the SCR in the engine width direction, it is not necessary to make the downstream pipe section extremely long. This increases the design flexibility of the SCR while suppressing an increase in the manufacturing cost of the SCR pipe.

[0080] Furthermore, in the diesel engine described above, the SCR is positioned lower than the DPF, and the SCR pipe further has a downstream pipe section connected to the downstream end of the straight pipe section, and the downstream pipe section may bend in the engine width direction from the downstream end of the straight pipe section, extend in the engine width direction above the SCR, and be connected to the exhaust inlet of the SCR.

[0081] With this configuration, by positioning the SCR lower than the DPF, for example, an SCR pipe that extends in the front-to-back direction of the engine at the same height as the DPF can be extended above the SCR, and the mixing of exhaust gas and ammonia gas (urea) can be promoted as the gas passes through such a relatively long SCR pipe.

[0082] Furthermore, in the above-mentioned diesel engine, the DPF is located above the cylinder head, while the SCR is located on one side of the cylinder head in the engine's longitudinal direction, and the engine may further include brackets for fixing the DPF and SCR to the cylinder head.

[0083] This configuration allows for weight reduction and cost savings due to a reduction in the number of parts, compared to the case where the DPF and SCR are separately fixed to the cylinder head via separate brackets.

[0084] Furthermore, in the diesel engine described above, the bracket comprises a first bracket member for fixing the SCR to the cylinder head and a second bracket member for fixing the end of the DPF closer to the SCR to the first bracket member, and the second bracket member may be configured to allow DPFs of different lengths to be fixed to the first bracket member by changing the mounting direction of the second bracket member to the first bracket member.

[0085] With this configuration, the second bracket member can be fixed to the first bracket member by changing the mounting direction of the second bracket member relative to the first bracket member. Therefore, even if the length of the DPF is different, the DPF and SCR can be fixed to the cylinder head using the same bracket without changing the shape of the first and second bracket members. Consequently, even if the length of the DPF is different, there is no need to manufacture a dedicated bracket each time, which helps to suppress increases in manufacturing costs.

[0086] Furthermore, in the diesel engine described above, the second bracket member includes at least a base portion attached to the first bracket member and a mounting portion rising from the end of the base portion and attached to the end of the DPF closer to the SCR, and the base portion is configured to be attachable to the first bracket member in either a position where the base portion side of the mounting portion faces the DPF side, or a position where the base portion side of the mounting portion faces the SCR side, and the mounting portion may be configured to be attachable to the end of the DPF closer to the SCR on either the base portion side of the mounting portion or the side opposite to the base portion side of the mounting portion.

[0087] With this configuration, for example, if the length of the DPF is relatively short (when the end of the DPF closer to the SCR is relatively far from the SCR), the base portion of the mounting portion is attached to the first bracket member with the base portion facing the SCR side, and the mounting portion is attached to the end of the DPF closer to the SCR on the opposite side of the base portion of the mounting portion, thereby fixing the DPF to the first bracket member via the second bracket.

[0088] On the other hand, for example, if the length of the DPF is relatively long (when the end of the DPF closer to the SCR is relatively close to the SCR), the base portion of the mounting portion can be attached to the first bracket member with the base portion facing the DPF, and the mounting portion can be attached to the end of the DPF closer to the SCR using the base portion of the mounting portion, thereby fixing the DPF to the first bracket member via the second bracket.

[0089] Furthermore, in the diesel engine described above, the base portion may be attached to the first bracket member via a fastening member inserted through an elongated hole formed in the base portion.

[0090] With this configuration, by changing the orientation of the base, the distance between the end of the DPF closest to the SCR and the second bracket member (mounting part) can be greatly adjusted. In addition, the elongated hole allows for fine adjustment of the distance between the end of the DPF closest to the SCR and the mounting part, so that the same bracket can be used to accommodate DPFs of various lengths.

[0091] Furthermore, in the diesel engine described above, the first bracket member may be attached directly or via a spacer to a mounting member fixed to a flange portion provided on the SCR.

[0092] With this configuration, even if the SCRs have different lengths, the same bracket can be used to secure them to the cylinder head. [Industrial applicability]

[0093] According to the present invention, even when both a DPF and an SCR are provided as exhaust aftertreatment devices, maintainability can be improved, making it extremely beneficial to apply to diesel engines equipped with exhaust aftertreatment devices. [Explanation of Symbols]

[0094] 1, 1A, 1B, 1C Diesel Engines 3 Cylinder head 10, 10A, 10B, 10C Exhaust aftertreatment device 20,20' DPF 20b,20b' Rear end 22 Exhaust outlet 30,30' SCR 32 Exhaust Inlet 33,33' Flange section 40,40' SCR pipe 42 Straight pipe section 43,43' Downstream pipe section 70 bracket 71 First bracket member 72 Second bracket member 73 Base section 75 Mounting part 77 Mounting components 80 Spacer CS Crankshaft (Crank Axle)

Claims

1. A diesel engine equipped with an exhaust aftertreatment device for purifying exhaust gases, The above exhaust aftertreatment device has a first case and a second case, The first case is positioned above the cylinder head, and the second case is positioned on one side of the engine's front-to-rear direction compared to the first case, extending in the engine's width direction perpendicular to both the front-to-rear and up-to-down directions. The system further includes brackets for fixing the first case and the second case to the engine body. A diesel engine comprising a bracket having a first bracket member for fixing the second case to the engine body and a second bracket member for fixing the end of the first case closer to the second case to the first bracket member.

2. In the diesel engine described in claim 1 above, The second bracket member includes at least a base portion attached to the first bracket member, and a mounting portion that rises from the end of the base portion and is attached to the end of the first case that is closer to the second case. The base portion described above is configured to be attachable to the first bracket member in either orientation, where the base portion of the mounting portion faces the first case, or where the base portion of the mounting portion faces the second case. A diesel engine in which the above-mentioned mounting portion is configured to be attachable to the end of the first case that is closer to the second case, on either the base side of the mounting portion or the side opposite to the base side of the mounting portion.

3. In the diesel engine described in claim 2 above, A diesel engine, wherein the base portion is attached to the first bracket member via a fastening member inserted through an elongated hole formed in the base portion.

4. In the diesel engine according to any one of the above claims 1 to 3, The first bracket member is attached to a mounting member fixed to a flange portion provided on the second case, either directly or via a spacer, in a diesel engine.

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