Diesel engine

A diesel engine is provided with an exhaust after-treatment device for purifying exhaust gas. The exhaust after-treatment device comprises a DPF that collects a particulate matter included in the exhaust gas, and an SCR that reduces nitrogen oxides included in the exhaust gas through addition of urea. The DPF is arranged to extend in an engine front-rear direction, which is a direction parallel to a crankshaft (CS), while the SCR is arranged to extend in an engine width direction rearward of the DPF in the engine front-rear direction.

This application is a national phase entry under 35 U.S.C. § 371 of PCT Patent Application No. PCT/JP2021/039634, filed Oct. 27, 2021, which claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2020-192649, filed Nov. 19, 2020, all of which are incorporated by reference.

TECHNICAL FIELD

The present invention relates to a diesel engine, and in particular to a diesel engine provided with an exhaust after-treatment device.

BACKGROUND ART

Conventionally, it has been widely conducted in a diesel engine that as an exhaust after-treatment device a Diesel Particulate Filter (DPF), which collects particulate matter in exhaust gas, and a Selective Catalytic Reduction (SCR), which causes NOx in the exhaust gas to be reduced by reduction reaction are provided in an exhaust passage, thereby performing purifying treatment for the exhaust gas discharged from an engine.

For example, Patent Literature 1 discloses an exhaust gas purifier equipped with a DPF and an SCR, which are arranged in a front-rear direction of the engine above the engine in such a posture that they extend in the engine width direction.

CITATION LIST

Patent Literature

DISCLOSURE OF INVENTION

Problems to be Solved by the Invention

By the way, there are many parts on an upper side of the engine that require periodic maintenance, such as injectors, valves, etc. (hereinafter, also referred to as “maintenance parts”). Nevertheless, as disclosed in the abovementioned Patent Literature 1, if the DPF and SCR are located on the upper side of the engine, there is a problem that when performing inspection, repair, replacement, etc. of the maintenance parts, it is difficult to perform maintenance efficiently because the DPF and/or SCR must be removed every time.

In light of the foregoing, the present invention has been made, and an object of the present invention is to provide a technology capable of improving maintainability of diesel engines, even if both a DPF and an SCR are provided as exhaust after-treatment devices.

Means for Solving the Problems

In order to achieve the aforementioned object, the present invention is made to provide the diesel engine with a devised layout of the exhaust after-treatment system with a DPF and an SCR.

Specifically, the present invention covers the diesel engines equipped with an exhaust after-treatment device that purifies exhaust.

In the diesel engine, the exhaust after-treatment device has 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, and the DPF is located extending in an engine front-rear direction parallel to a crankshaft, while the SCR is located extending in an engine width direction orthogonal to both the engine front-rear direction and an up-down direction, on one side of the engine front-rear direction with respect to the DPF.

According to this configuration, the DPF is located extending in the engine front-rear direction, while the SCR is located on one side in the engine front-rear direction with respect to the DPF extending in the engine width direction, so that the DPF and the SCR can be arranged to form a substantially T shape or a substantially L shape in plan view.

Since the DPF and the SCR are arranged to form a substantially T shape or a substantially L shape, even when the DPF and the SCR are arranged above the engine, the area of the upper side of the engine (not covered by the DPF and the SCR) can be increased compared to the case where the DPF and the SCR extending in the same direction are arranged side by side in the same direction. This makes it possible to perform efficient inspection, repair, and replacement of maintenance parts without removing the DPF and/or the SCR, thereby improving maintainability even when the DPF and the SCR are provided as the exhaust after-treatment device.

In the diesel engine mentioned above, the DPF may have an exhaust outlet at an end on a far side from the SCR in the engine front-rear direction to discharge the exhaust gas that collected the particulate matter, and an SCR pipe connecting the exhaust outlet of the DPF and an exhaust inlet of the SCR may have a straight pipe section extending in the engine front-rear direction at a position corresponding to a center in the engine width direction.

According to this configuration, for example, when the upstream side of the straight pipe section in the SCR pipe is defined as the upstream pipe section and the downstream side of the straight pipe section in the SCR pipe is defined as the downstream pipe section, by connecting the exhaust outlet of the DPF and the upstream end of the straight pipe section by the upstream pipe section, the exhaust gas, which is discharged from the exhaust outlet of the DPF after particulate matter is collected, can flow up to the vicinity of the SCR30through the upstream pipe section and through the straight pipe section.

The straight pipe section extends in the engine front-rear direction at a position corresponding to the center in the engine width direction, so that no matter where the exhaust inlet of the SCR is located in the SCR in the engine width direction, the same layout of the upstream pipe section and the straight pipe section can be used without being affected by changes in the shape, standard, etc. of the SCR, since it is possible to handle only by changing the shape or the length of the downstream pipe section.

Since the downstream end of the straight pipe section is always located in the center of the engine width direction, even if the exhaust inlet of the SCR is located on one side or the other side in the engine width direction in the SCR, the downstream pipe section does not need to be extremely long, this make it possible to reduce a cost for manufacturing the SCR pipe from increasing while to increase the design freedom of the SCR.

Furthermore, in the diesel engine mentioned above, the SCR may be located at a position lower than the DPF, and the SCR pipe further may have a downstream pipe section connected to a downstream end of the straight pipe section, and the downstream pipe section may bend at the downstream end of the straight pipe section in the engine width direction, extend in the engine width direction above the SCR, and connect with the exhaust inlet of the SCR.

According to this configuration, by locating the SCR at a position lower than the DPF, for example, the SCR pipe, which are the same height as the DPF and extends in the engine front-rear direction, can be extended up to above the SCR, so that during passing through such relatively long SCR pipe, the mixing of the exhaust gas and the ammonia gas (urea) can be accelerated.

In the diesel engine mentioned above, the DPF may be located on an upper side of a cylinder head, while the SCR may be located on one side of in the engine front-rear direction with respect to the cylinder head, and the diesel engine further may comprise a bracket to secure the DPF and the SCR to the cylinder head.

According to this configuration, compared to the case where the DPF and the SCR are fixed separately to the cylinder head via separate brackets, it is possible to attain light weight and cost down due to reduction of the number of parts.

Furthermore, in the diesel engine mentioned above, the bracket may have a first bracket member to fix the SCR to the cylinder head and a second bracket member to fix an end of the DPF closer to the SCR to the first bracket member, and the second bracket member may enable the DPF with a different length to be fixed to the first bracket member by changing a mounting direction to the first bracket member.

According to this configuration, the second bracket member is configured to be able to fix the DPFs with different lengths to the first bracket member by changing the mounting direction to the first bracket member, so that even when the lengths of the DPFs are different, the DPF and the SCR can be fixed to the cylinder head without changing the shape, etc. of the first bracket member and the second bracket member, in other words, using the same bracket. Therefore, even when the length of the DPF is different, there is no need to manufacture a dedicated bracket every time, thereby reducing the manufacturing cost from increasing.

In the diesel engine mentioned above, the second bracket member may have at least a base portion attached to the first bracket member and a mount portion rising from an end of the base portion and attached to the end of the DPF closer to the SCR, the base portion may be attachable to the first bracket member with any of postures in which a base portion side of the mount portion faces a DPF side and the base portion side of the mount portion faces an SCR side, and the mount portion may be attachable to the end of the DPF closer to the SCR at any of a surface on a base portion side of the mount portion and a surface opposite to the base portion side of the mount portion.

According to this configuration, for example, when the length of the DPF is relatively short (when the end closer to the SCR in the DPF is relatively far from the SCR), the base portion is attached to the first bracket member with a posture that the base portion side of the mount portion faces the SCR side, as well as the mount portion is attached on the side opposite to the base portion side of the mount portion to the end of the DPF closer to the SCR. This makes it possible to fix the DPF to the first bracket member via the second bracket.

On the other hand, for example, when the length of the DPF is relatively long (when the end closer to the SCR in the DPF is relatively closer to the SCR), the base portion is attached to the first bracket member with a posture that the base portion side of the mount portion faces the DPF side, as well as the mount portion is attached on the base portion side of the mount portion to the end of the DPF closer to the SCR. This makes it possible to fix the DPF to the first bracket member via the second bracket.

Furthermore, in the diesel engine mentioned above, the base portion may be attached to the first bracket member via a fastening member that is inserted through a long hole formed in the base portion.

According to this configuration, the same bracket can be used to handle the DPF with various lengths, since a distance between the end of the DPF closer to the SCR and the second bracket member (mount portion) can be largely adjusted by changing the posture of the base portion as well as the long hole enables the distance between the end of the DPF closer to the SCR and the mount portion to be finely adjusted.

In the diesel engine mentioned above, the first bracket member may be attached directly or via a spacer to a mounting member fixed to a flange provided on the SCR.

According to this configuration, the same bracket can be used to secure the SCR to the cylinder head, even when the length of the SCR is different.

Effect of the Invention

As explained above, according to the diesel engine of the present invention, the maintainability thereof can be improved even if both the DPF and the SCR are provided as exhaust after-treatment devices.

DESCRIPTION OF EMBODIMENTS

Embodiments for carrying out the present invention will be described below with reference to the accompanying drawings. In the following, a description is given in such a manner that a direction parallel to a crankshaft CS is defined as an engine front-rear direction, and a direction orthogonal to both the engine front-rear direction and an up-down direction is defined as an engine width direction. Also, in each of the drawings, an arrow Fw indicates the front side in the engine front-rear direction, an arrow Rh indicates the right side in the engine width direction, and an arrow Up indicates the upper side in the up-down direction.

FIG.1is a perspective view schematically illustrating a diesel engine1according to an embodiment of the present invention, andFIG.2is a plan view schematically illustrating a main part of the diesel engine1. As shown inFIGS.1and2, the diesel engine1includes an engine body1awith a cylinder head3fastened to the top of a cylinder block2, an exhaust manifold (not shown), an intake manifold (not shown), a flywheel (not shown) housed in a flywheel housing5, a cooling fan7, an EGR system (not shown), an intake throttle system (not shown), a turbocharger (not shown), and an exhaust after-treatment device10that purifies exhaust air.

The cylinder block2contains a plurality of pistons (not shown) which reciprocates up and down within a plurality of cylinders, respectively, and a crankshaft (crankshaft shaft) CS which is connected to the pistons via connecting rods (not shown). The oil pan4to store oil which is circulated in the diesel engine1to lubricate each part is fixed to a lower side of the cylinder block2.

While the intake manifold is connected to the cylinder head3on the right side in the engine width direction, the exhaust manifold is connected to the cylinder head3on the left side in the engine width direction. In other words, the diesel engine1according to the present embodiment is configured so 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 cover3ais fixed to the top of the cylinder head3.

As shown inFIG.1, a flywheel housing5which houses the flywheel is provided on the rear side in the engine front-rear direction of the engine body1a. On the other hand, as shown inFIG.2, the cooling fan7is provided on the front side of the engine body1ain the engine front-rear direction. The cooling fan7is rotated by rotational power transmitted from the crankshaft CS.

The diesel engine1according to the present embodiment is also equipped with an EGR system, so that a portion of the exhaust gas discharged from each combustion chamber to the exhaust manifold via the exhaust port is returned (recirculated) to the intake side. In this way, by mixing a portion of the exhaust gas with the intake air, a combustion temperature can be lowered and thus nitrogen oxides (NOx) in the exhaust gas can be reduced.

A turbocharger is installed on the exhaust side of the diesel engine1. Fresh air having been dusted out by the air cleaner (not shown) is compressed by the turbocharger, sent to the intake manifold via an intake throttle device on the intake side, and then mixed with the returned exhaust gas in the intake manifold to be supplied to each cylinder.

Exhaust After-Treatment Device (hereinafter, also referred to as “ATD”)10has a DPF (Diesel Particulate Filter)20, an SCR (Selective Catalytic Reduction)30, an SCR pipe40connecting the DPF20and the SCR30, and a dosing module (a Urea injection system)50which is installed on the upstream side of the SCR pipe40.

The DPF20is structured such that an oxidation catalyst (not shown) and a soot filter (not shown) are arranged in series, and are accommodated in a DPF casing21. In the DPF20, when exhaust gas flowing into the DPF casing21from an exhaust introduction port (not shown) passes through the soot filter, particulate matter in the exhaust gas is collected by the soot filter. Furthermore, when the exhaust gas passes through the oxidation catalyst, if an exhaust gas temperature exceeds a regenerable temperature, the particulate matter deposited on the soot filter is combustion-removed by oxygen getting higher temperature due to oxidation catalyst action, and the soot filter is regenerated.

An SCR30is structured such that an SCR catalyst for urea selective catalytic reduction (not shown) and an oxidation catalyst (not shown) are arranged in series, and are accommodated in an SCR casing31. An upstream end of the SCR casing31is connected to a downstream end of the DPF casing21via the SCR pipe40that is relatively long. In the SCR pipe40, ammonia gas is generated by injecting urea water from the dosing module50to the exhaust gas flowing into from the DPF20, so that mixing of the exhaust gas and the ammonia gas is promoted during passing through the relatively long SCR pipe40. In the SCR30, when the exhaust gas and the ammonia gas flowing into the SCR casing31pass through the SCR catalyst, the nitrogen oxides in the exhaust gas chemically react with ammonia, and are reduced to nitrogen and water, as well as the ammonia is reduced when the exhaust gas and the ammonia gas pass through the oxidation catalyst.

In this way, exhaust gas, from which particulate matter is removed by the DPF20and nitrogen oxides are reduced by SCR30, is discharged from a tail pipe60provided at the downstream end of the SCR casing31.

Layout of DPF and SCR

FIG.16is a plan view schematically illustrating a conventional diesel engine101. As shown inFIG.16, the conventional diesel engine101is similar to the diesel engine1according to the present embodiment in that the conventional diesel engine101also has an engine body101a, a flywheel housing105, a cooling fan107, and an exhaust after-treatment device110that purifies exhaust.

However, in the conventional diesel engine101, the DPF120and the SCR130of the exhaust after-treatment device110, which are connected by the SCR pipe140, are arranged side by side on the top of the engine body101ain the engine front-rear direction with a posture that the DPF120and the SCR130extend in the engine width direction.

By the way, there are many parts on an upper side of the engine body101athat require periodic maintenance, such as injectors, valves, etc. (hereinafter, also referred to as “maintenance parts”). Nevertheless, as in the conventional diesel engine101, if the DPF120and the SCR130are arranged on the upper side of the engine body101a, the upper part of the engine body101ais hidden, as shown inFIG.16. Therefore, there is a problem that when performing inspection, repair, replacement, etc. of the maintenance parts, it is difficult to perform maintenance efficiently because the DPF120and/or SCR130must be removed every time.

In the diesel engine1according to the present embodiment, a layout of DPF20and SCR30is devised. Specifically, as shown inFIG.2, in the diesel engine1according to the present embodiment, the DPF20is located above the engine body1a(more precisely, above the head cover3a) extending in the engine front-rear direction, while the SCR30is located above the flywheel housing5which is on the rear side (one side) from the DPF20in the engine front-rear direction. The SCR30is located above the flywheel housing5so that the SCR30is located at a position lower than the DPF20as well as a center of the SCR30in the engine width direction overlaps the crankshaft CS in plan view.

As shown inFIG.2, the DPF20and the SCR30are arranged to form a substantially L shape in plan view because the DPF20is located on the upper side of the engine body1aextending in the engine front-rear direction, while the SCR30is located on the rear side from the DPF20in the engine front-rear direction extending in the engine width direction.

Since the DPF20and the SCR30are arranged to form a substantially L shape, as shown inFIG.2, the area of the upper side of the engine body1a(not covered by the DPF20and the SCR30) can be increased compared to the conventional diesel engine101in which the DPF120and the SCR130extending in the engine width direction are arranged side by side in the engine front-rear direction. This makes it possible to perform efficient inspection, repair, and replacement of maintenance parts without removing the DPF20and/or SCR30, thereby improving maintainability even when the DPF20and the SCR30are provided as the exhaust after-treatment device10.

Layout of SCR Pipe

In the DPF20, an exhaust outlet22(seeFIG.12), from which the exhaust gas is discharged after particulate matter is collected, is provided at the end of the front side (front end20a) (the end farther from SCR30) in the engine front-rear direction. In addition, in the SCR30, an exhaust inlet32is provided at the end of the right side (right end30a) in the engine width direction, while a tail pipe60is provided at the end of the left side in the engine width direction. As shown inFIG.1, in the diesel engine1, the exhaust outlet22of the DPF20and the exhaust inlet32of the SCR30are connected by the SCR pipe40.

By the way, since the tail pipe60, which is at a position of the most downstream of an ATD10, is connected to an exhaust pipe on the side of the vehicle body (not shown), the tail pipe60can be set at various positions in the SCR30depending on the layout of the vehicle body. In particular, it is very important from the vehicle body's view which side of the diesel engine1the tail pipe60is set on, and it is desirable that the tail pipe60can be set on any right or left side of the diesel engine1.

FIG.3is a perspective view schematically illustrating a main part of the diesel engine1A, andFIG.4is a plan view schematically illustrating a main part of the diesel engine1A. The diesel engine1A is substantially the same as the diesel engine1, and the same components are denoted by an identical symbol or numeral.

As shown inFIG.3, in an ATD10A of the diesel engine1A, the SCR30is installed in such an arrangement that the SCR30of the diesel engine1A is a mirror image of the SCR30of the diesel engine1. Therefore, in the SCR30, the tail pipe60is provided at the end of the right side in the engine width direction, while the exhaust inlet32is provided at the end of the left side of the engine width direction. In the diesel engine1A, the exhaust outlet22of the DPF20and the exhaust inlet32of the SCR30are connected by a SCR pipe40′, as shown inFIG.1.

In this way, in the diesel engine1, the exhaust outlet22of the DPF20and the exhaust inlet32of the SCR30are connected by the SCR pipe40, while in the diesel engine1A, the exhaust outlet22of the DPF20and the exhaust inlet32of the SCR30are connected by the SCR pipe40′ different from the SCR pipe40. However, it is uneconomical to manufacture the SCR pipe40′ that is completely different from the SCR pipe40, even though the diesel engine1and the diesel engine1A have substantially the same configuration.

Therefore, in the present embodiment, the SCR pipes40,40′ that connect the exhaust outlet22of the DPF20and the exhaust inlet of the SCR30have a straight pipe section42that extends in the engine front-rear direction at a position corresponding to the center in the engine width direction.

More specifically, both the SCR pipe40and the SCR pipe40′ are connected to the exhaust outlet22of the DPF20and have an upstream pipe section41that extends slightly toward the front side in the engine front-rear direction and then bends 180 degrees to extend toward the rear side in the engine front-rear direction. Both the SCR pipe40and the SCR pipe40′ are connected to a downstream end of the upstream pipe section41and have a straight pipe section42that extends in the engine front-rear direction at a position corresponding to the center in the engine width direction. In the present embodiment, as described above, the center of the SCR30in the engine width direction is located so as to overlap the crankshaft CS in plan view, so that the straight pipe section42extending in the engine front-rear direction so as to overlap the crankshaft CS in plan view forms a substantially T shape along with the SCR30in plan view.

As shown inFIGS.1and2, the SCR pipe40has a downstream pipe section43that is connected to the downstream end of the straight pipe section42, bends to the right side in the engine width direction, extends to the right side in the engine width direction above the SCR30, and then bends downward to connect to the exhaust inlet32of the SCR30.

In contrast, as shown inFIGS.3and4, the SCR pipe40′ has a downstream pipe section43′ that is connected to the downstream end of the straight pipe section42, bends to the left side in the engine width direction, extends to the left side in the engine width direction above the SCR30, and then bends downward to connect to the exhaust inlet32of the SCR30.

In this way, by connecting the exhaust outlet22of the DPF20and the upstream end of the straight pipe section42by the upstream pipe section41, in both the SCR pipe40and the SCR pipe40′, the exhaust gas, which is discharged from the exhaust outlet22of the DPF20after particulate matter is collected, can flow up to the vicinity of the SCR30through the upstream pipe section41and through the straight pipe section42.

The straight pipe section42extends in the engine front-rear direction at a position corresponding to the center in the engine width direction so that the straight pipe section42forms a T shape along with the SCR30in plan view, so that a positional relationship between the downstream end of the straight pipe section42and the SCR30can be always substantially the same. Therefore, no matter where the exhaust inlet32of the SCR30is located in the SCR30in the engine width direction, the same layout of the upstream pipe section41and the straight pipe section42can be used without being affected by changes in the shape, standard, etc. of the SCR30, since it is possible to handle only by changing the shape or the length of the downstream pipe sections43and43′.

Since the downstream end of the straight pipe section42is always located in the vicinity of the center of the SCR30, even if the exhaust inlet32of the SCR30is located at the end of the right side in the engine width direction in the SCR30as shown in the diesel engine1, or even if the exhaust inlet32of the SCR30is located at the end of the left side in the engine width direction in the SCR30as shown in the diesel engine1A, the downstream pipe sections43and43′ do not need to be extremely long, this make it possible to reduce a cost for manufacturing the SCR pipe40from increasing while to increase the design freedom of the SCR30.

Furthermore, by locating the SCR30at a position lower than the DPF20, for example, the SCR pipes40,40′, which are the same height as the DPF20and extend in the engine front-rear direction, can be extended up to above the SCR30, so that during passing through such relatively long SCR pipes40,40′, the mixing of the exhaust gas and the ammonia gas (urea) can be accelerated.

Fixing Structure of DPF and SCR

FIG.5is a perspective view schematically illustrating a main part of the diesel engine1B, andFIG.6is a perspective view schematically illustrating a main part of the diesel engine1C. Since the diesel engine1B is substantially the same as the diesel engine1, and the diesel engine1C is substantially the same as the diesel engine1A, the same components are denoted by an identical symbol or numeral.

There is a difference between the diesel engine1and the diesel engine1B that the diesel engine1B has a higher power specification than the diesel engine1, and accordingly, the DPF20′ of the diesel engine1B is formed so as to be longer than the DPF20of the diesel engine1in the engine front-rear direction, and the SCR30′ of the diesel engine1B is formed so as to be longer than the SCR30of the diesel engine1in the engine width direction. Similarly, there is a difference between the diesel engine1A and the diesel engine1C that the diesel engine1C has a higher power specification than the diesel engine1A, and accordingly, the DPF20′ of the diesel engine1C is formed so as to be longer than the DPF20of the diesel engine1A in the engine front-rear direction, and the SCR30′ of the diesel engine1C is formed so as to be longer than the SCR30of the diesel engine1A in the engine width direction.

However, it is uneconomical to employ completely different fixing structures for the DPFs20and20′ and for the SCRs30and30′, respectively, even though the diesel engine1and the diesel engine1B have substantially the same configuration except for the difference in length between the DPFs20and20′ and the difference in length between the SCRs30and30′. Similarly, this can be also applied to a relationship between the diesel engine1A and the diesel engine1C.

Therefore, the DPFs20and20′ and the SCRs30and30′ are fixed to the engine bodies1aby a substantially identical fixing structure, respectively. As a representative example, a fixing structure of the DPF20and the SCR30in the diesel engine1and a fixing structure of the DPF20′ and the SCR30′ in the diesel engine1B are described below.

FIG.7is a side view seen from the right side in the engine width direction, which schematically illustrates a main part of the diesel engine1,FIG.8is a side view seen from the right side in the engine width direction, which schematically illustrates a main part of the diesel engine1B, andFIG.9is a perspective view schematically illustrating an end of the SCR30on the right side in the engine width direction in the diesel engine1. For simplicity of drawing, the SCR pipe40and the SCR pipe40′ are omitted inFIGS.7and8.

In the diesel engine1, the DPF20is supported at two points on the cylinder head3by fixing the front end20aand the end of the rear side (rear end)20bin the engine front-rear direction to the cylinder head3. The SCR30is supported at two points on the engine body1aby fixing the end of the right side (right end)30ain the engine width direction to the flywheel housing5and fixing a flange portion33formed on the left side of the SCR casing31in the engine width direction to the cylinder head3.

On the other hand, also in the diesel engine1B, the DPF20′ is supported at two points on the cylinder head3by fixing the end of the front side (front end)20a′ in the engine front-rear direction and the end of the rear side (rear end)20b′ in the engine front-rear direction to the cylinder head3. Furthermore, the SCR30′ is supported at two points on the engine body1aby fixing the end of the right side (right end)30a′ in the engine width direction to the flywheel housing5and fixing a flange portion33′ formed on the left side of the SCR casing31′ in the engine width direction to the cylinder head3.

More specifically, as shown inFIG.7, in the diesel engine1, the front end20aof the DPF20is fixed to the front end of the cylinder head3via a DPF bracket90that is fastened with bolts to the front end20aand the front end of the cylinder head3. Similarly, as shown inFIG.8, also in the diesel engine1B, the front end20a′ of the DPF20′ is fixed to the front end of the cylinder head3via a DPF bracket90that is fastened with bolts to the front end20a′ and the front end of the cylinder head3.

On the other hand, as shown inFIGS.7and9, in the diesel engine1, the right end30aof the SCR30is fixed to the right end of the flywheel housing5via a SCR bracket91that is fastened with bolts to the right end30aand the right end of the flywheel housing5. Similarly, as shown inFIG.8, in the diesel engine1B, the right end30a′ of the SCR30′ is fixed to the right end of the flywheel housing5via the SCR bracket91that is fastened with bolts to the right end30a′ and the right end of the flywheel housing5.

As shown inFIG.7, in the diesel engine1, the rear end20bof the DPF20and the flange portion33of the SCR30are fixed to the rear end of the cylinder head3via a common bracket70.

By fixing the DPF20and the SCR30to the cylinder head3via the common bracket70, compared to the case where the DPF20and the SCR30are fixed separately to the cylinder head3via separate brackets, it is possible to attain light weight and cost down due to reduction of the number of parts.

Also in the diesel engine1B, as shown inFIG.8, the rear end20b′ of the DPF20′ and the flange portion33′ of the SCR30′ can be fixed to the rear end of the cylinder head3via the common bracket70used in the diesel engine1. Namely, the bracket70is configured to be applicable to the DPFs20and20′ that have different lengths and the SCRs30and30′ that have different lengths. Such the bracket70is described in detail below.

The bracket70has a first bracket member71that secures the SCRs30and30′ to the cylinder head3, and a second bracket member72that secures the rear ends20band20b′ (the end closer to the SCRs30and30′) of the DPFs20and20′ to the first bracket member71. In other words, the rear ends20band20b′ of the DPFs20and20′ are fixed to the cylinder head3via the second bracket member72and the first bracket member71.

As shown inFIGS.7and8, a lower end71aof the first bracket member71is fastened with bolts to the rear end of the cylinder head3. The first bracket member71has a flat mount surface71bat its upper end.

On the other hand, as shown inFIGS.7and8, the second bracket member72has a substantially rectangular-shaped base portion73attached to the upper side of the flat mount surface71bof the first bracket member71, and a mount portion75which rises orthogonally from the end of the base portion73so as to form a substantially L-shaped cross section along with the base portion73and is attached to the rear ends20band20b′ of the DPFs20and20′. The second bracket member72can be of any configuration as long as it has at least the base portion73and the mount portion75that form a substantially L-shaped cross section together.

FIG.10is a perspective view schematically illustrating the bracket70in the diesel engine1, andFIG.11is a perspective view schematically illustrating the bracket70in the diesel engine1B. The base portion73is configured to be able to be fastened with bolts to the first bracket member71with any of postures in which as shown inFIGS.7and10, the inside of the L shape faces the SCR30side (the mount portion75is on the front side in the engine front-rear direction and the base portion73is on the rear side in the engine rear-back direction), and in which as shown inFIGS.8and11, the inside of the L shape faces the DPF20side (the base portion73is on the front side in the engine front-rear direction and the mount portion75is on the rear side in the engine rear-back direction). The mount portion75is configured to be able to be fastened with bolts to the rear ends20band20b′ of the DPFs20and20′ at any of surfaces which is, as shown inFIGS.7and10, the outside of the L shape (surface opposite to the base portion73in the mount portion75), and which is, as shown inFIGS.8and11, the inside of the L shape (the same side surface as the base portion73in the mount portion75).

As described above, in both diesel engine1and diesel engine1B, the front ends20aand20a′ of the DPFs20and20′ are fixed to the front end of the cylinder head3via the DPF bracket90. Since the DPF20′ of the diesel engine1B is longer than the DPF20of the diesel engine1in the engine front-rear direction, as shown inFIGS.7and10, the rear end20bof the DPF20in the diesel engine1stops before the SCR30in the engine front-rear direction. On the other hand, as shown inFIGS.7and10, the rear end20b′ of DPF20′ in diesel engine1B overlaps a part of the SCR30′ in plan view. This means that the rear ends20band20b′ of the DPFs20and20′ are closer to the SCRs30and30′ in diesel engine1B than in diesel engine1.

Therefore, in the diesel engine1, as shown inFIGS.7and10, the base portion73is fastened with bolts to the mount surface71bof the first bracket member71with a posture that the inside of the L shape faces the SCR30side, as well as the outside of the L shape of the mount portion75is fastened with bolts to the rear end20bof the DPF20. This makes it possible to fix the relatively short DPF20to the cylinder head3via the second bracket member72and the first bracket member71.

In contrast, in the diesel engine1B, as shown inFIGS.8and11, the base portion73is fastened with bolts to the mount surface71bof the first bracket member71with a posture that the inside of the L shape faces the DPF20side, as well as the inside of the L shape of the mount portion75is fastened with bolts to the rear end20bof the DPF20. This makes it possible to fix the relatively short DPF20′ to the cylinder head3via the second bracket member72and the first bracket member71.

In this way, the second bracket member72is configured to be able to fix the DPFs20and20′ with different lengths to the first bracket member71by changing a mounting orientation to the first bracket member71.

This makes it possible to fix the DPFs20and20′ even whose lengths are different to the cylinder head3without changing the shape, etc. of the first bracket member71and the second bracket member72, in other words, using the same bracket70. Therefore, even when the lengths of the DPFs20and20′ are different, there is no need to manufacture a dedicated bracket every time, thereby reducing the manufacturing cost from increasing.

The base portion73may be configured to be fastened to the mount surface71bof the first bracket member71via bolts that are inserted through a long hole (not shown) formed in the base portion73.

This configuration allows the same bracket70to be used to handle the DPFs20and20′ with various lengths, since a distance between the mount portion75and the rear ends20band20b′ of the DPFs20and20′ can be largely adjusted by changing the posture of the base portion73as well as the long hole enables the distance between the mount portion75and the rear ends20band20b′ of the DPFs20and20′ to be finely adjusted.

FIG.12is a front view seen from the front side in the engine front-rear direction, which schematically illustrates a main part of the diesel engine1, andFIG.13is a front view seen from the front side in the engine front-rear direction, which schematically illustrates a main part of the diesel engine1B.FIG.14is a perspective view schematically illustrating a mounting form of the first bracket member71in the diesel engine1, andFIG.15is a perspective view schematically illustrating a mounting form of the first bracket member71in the diesel engine1B. For simplicity of drawing, the DPF bracket90is omitted inFIGS.12and13.

As mentioned above, in both diesel engine1and diesel engine1B, the right ends30aand30a′ of the SCRs30and30′ are fixed to the right end of the flywheel housing5via the SCR bracket91. Since the SCR30′ of the diesel engine1B is longer in the engine width direction than the SCR30of the diesel engine1, as can be seen fromFIGS.12and13, the flange portion33′ of the SCR30′ in the diesel engine1B is further away from the first bracket member71in the engine width direction than the flange portion33of the SCR30in the diesel engine1.

Therefore, in the present embodiment, the first bracket member71is configured to be able to be mounted on a mounting member77fixed to the flange portions33and33′ of the SCRs30and30′ directly or via a spacer80. In more detail, as shown inFIGS.12and14, in the diesel engine1, a substantially arc-shaped mounting member77with a larger diameter than the flange portion33is fastened with bolts to the flange portion33of the SCR30, and the first bracket member71is fastened with bolts directly to the mounting member77. This allows the flange portion33of the relatively short SCR30to be connected to the first bracket member71and secured to the cylinder head3via the first bracket member71.

In contrast, as shown inFIGS.13and15, in the diesel engine1B, the mounting member77is fastened with bolts to the flange portion33′ of the SCR30′, and the first bracket member71is fastened with bolts to the mounting member77via the spacer80. This allows the flange portion33′ of the relatively long SCR30′ to be connected to the first bracket member71and secured to the cylinder head3via the first bracket member71.

This allows the same bracket70to be used to secure the SCRs30and30′ to the cylinder head3, even when the lengths of the SCRs30and30′ are different.

OTHER EMBODIMENTS

It should be noted that the present invention is not limited to the embodiments, and can be carried out in various other forms without departing from a spirit or main features of the present invention.

In the embodiment mentioned above, in the diesel engines1,1A,1B, and1C, the cooling fan7side is defined as the front side in the engine front-rear direction, and the flywheel side is defined as the rear side in the engine front-rear direction. However, the front-rear direction of the diesel engines1,1A,1B, and1C does not necessarily coincide with the front-rear direction of the work vehicle on which the diesel engines1,1A,1B, and1C are mounted. For example, the diesel engines1,1A,1B, and1C may be mounted on the work vehicle so that the front-rear direction of the diesel engines1,1A,1B, and1C coincides with the front-rear direction of the work vehicle, or the diesel engines1,1A,1B, and1C may be mounted on the work vehicle so that the front-rear direction of the diesel engines1,1A,1B, and1C coincides with the body-width direction of the work vehicle.

Furthermore, in the embodiment mentioned above, the cylinder head3is configured in such a way that the left side in the engine width direction is defined as the exhaust side, and the right side in the engine width direction is defined as the intake side. However, the configuration is not limited thereto, and the cylinder head3may be configured in such a way that the right side in the engine width direction is defined as the exhaust side, and the left side in the engine width direction is defined as the intake side.

Thus, the embodiments described above are merely examples in all respects, and should not be restrictively construed. Furthermore, modifications and changes deemed to be within a range of the equivalents of the claims all fall within the scope of the present invention. The present application claims the benefit of priority to Japanese Patent Application No. 2020-192649, filed with the JPO as of Nov. 19, 2020. The entirety thereof is incorporated herein by reference.

INDUSTRIAL APPLICABILITY

According to the present invention, since the maintainability thereof can be improved even if both the DPF and the SCR are provided as exhaust after-treatment devices, it is extremely beneficial to apply the present invention to the diesel engines equipped with the exhaust after-treatment devices.

DESCRIPTION OF REFERENCE NUMERALS