Engine device

Abstract

Provided is an engine device in which an exhaust gas purification device is provided by means of a support base, and in which a space that is open on both sides in the crankshaft direction is provided between a cylinder head cover and the support base.

Description

[0001] This application is a divisional application of the invention application with application number 201780085883.2, application date December 19, 2017, and invention title "Engine Device". Technical Field

[0002] This invention relates to an engine device equipped with an exhaust gas purification system. Background Technology

[0003] Recently, with the application of high-level emission restrictions related to diesel engines (hereinafter referred to as engines), there is a demand for exhaust gas purification devices to be installed on agricultural vehicles and construction machinery equipped with engines, which purify the air pollutants in the exhaust gas. As an exhaust gas purification device, diesel particulate filters (DPFs) for capturing particulate matter (smoke, particles) in exhaust gas are known (for example, see Patent Documents 1-3, etc.).

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-077621

[0006] Patent Document 2: Japanese Patent Application Publication No. 2013-173428

[0007] Patent Document 3: Japanese Patent No. 5449517 Summary of the Invention

[0008] In order to compactly mount the exhaust gas purification device on the upper part of the engine, a high-rigidity support platform is required. From the perspective of vibration and strength, it is necessary to ensure the rigidity of the support platform while also making it lightweight.

[0009] The technical challenge of this invention is to provide an engine device that has been improved by studying the above-mentioned situation.

[0010] The engine assembly of the present invention is equipped with an exhaust gas purification device above the cylinder head by means of a support platform. The support platform includes: a flat portion for mounting the exhaust gas purification device; and a plurality of legs that protrude downward from the flat portion and are fixed to the cylinder head. The flat portion and the legs are integrally formed. On the other hand, adjacent legs are arched relative to each other.

[0011] For example, the engine device of the present invention may also be configured such that: an exhaust manifold and an intake manifold are separately arranged on the exhaust side and intake side of the cylinder head that are opposite to each other; the support platform is arranged above one of the two sides of the cylinder head that intersect the exhaust side and the intake side; and the foot includes: an exhaust side foot fixed to the exhaust side; an intake side foot fixed to the intake side; and a central foot fixed to the one side.

[0012] Alternatively, the engine device of the present invention may be configured such that a cooling fan is provided on the other side of the two sides of the cylinder head, a cooling air passage is formed between the cylinder head cover on the cylinder head and the support platform, and cooling air from the cooling fan flows through the cooling air passage.

[0013] Furthermore, the engine device of the present invention may also be configured to include: an EGR device that causes a portion of the exhaust gas discharged from the exhaust manifold to return to the intake manifold as EGR gas; an EGR cooler that cools the EGR gas; and an exhaust pressure sensor that detects the exhaust gas pressure in the exhaust manifold, wherein the EGR cooler and the exhaust pressure sensor are mounted on one side of the cylinder head.

[0014] Alternatively, the engine device of the present invention may be configured such that the intake manifold is integrally formed on the intake side of the cylinder head, and the intake side foot is fixed to the upper surface of the intake manifold.

[0015] The present invention relates to an engine assembly in which an exhaust gas purification device is mounted on a support platform above the cylinder head. The support platform includes: a flat portion for mounting the exhaust gas purification device; and multiple legs that protrude downwards from the flat portion and are fixed to the cylinder head. The flat portion and the legs are integrally formed. Furthermore, adjacent legs are arched relative to each other. Therefore, the integrally formed structure and the aforementioned arched shape enable weight reduction while ensuring the rigidity of the support platform. Additionally, by making the support platform a one-piece component, the number of parts can be reduced. Moreover, the arched gaps between the multiple legs prevent the formation of heat accumulation around the legs of the support platform. For example, this prevents thermal damage to electronic components such as sensors mounted around the legs and avoids insufficient cooling of cooling components such as the EGR cooler.

[0016] For example, the engine device of the present invention is configured such that an exhaust manifold and an intake manifold are separately arranged on the exhaust side and intake side of the cylinder head, which are opposite to each other. A support platform is disposed above one of the two sides of the cylinder head that intersect the exhaust side and the intake side, and has as feet: an exhaust side foot fixed to the exhaust side; an intake side foot fixed to the intake side; and a central foot fixed to the aforementioned one side. This allows the support platform to be fixed to a total of three surfaces of the cylinder head: the exhaust side, the intake side, and the aforementioned one side, thereby improving the support rigidity of the exhaust gas purification device. In addition, by making the height and size of the arch between the intake side foot and the central foot, and the arch between the exhaust side foot and the central foot, different, or by making the lengths of the intake side foot and the exhaust side foot different, the vibrations of the intake side and the exhaust side can be canceled out by the support platform, thereby reducing the vibration of the exhaust gas purification device.

[0017] Furthermore, the engine device of the present invention is configured such that a cooling fan is provided on one of the two sides of the cylinder head, and a cooling air passage is formed between the cylinder head cover and the support platform on the cylinder head. Cooling air from the cooling fan flows through the cooling air passage, thereby guiding the cooling air from the cooling fan to the one side of the cylinder head through the cooling air passage, and appropriately cooling the area around the one side of the cylinder head.

[0018] Furthermore, the engine device of the present invention is configured to include: an EGR device that allows a portion of the exhaust gas discharged from the exhaust manifold to return to the intake manifold as EGR gas; an EGR cooler that cools the EGR gas; and an exhaust pressure sensor that detects the exhaust gas pressure in the exhaust manifold. The EGR cooler and the exhaust pressure sensor are mounted on one side of the cylinder head, thereby enabling the cooling of the EGR cooler to be promoted by the cooling air guided to the aforementioned side from the cooling fan via the cooling air passage, and preventing thermal damage to the exhaust pressure sensor.

[0019] Furthermore, the engine assembly of the present invention has an intake manifold integrally formed on the intake side of the cylinder head, and an intake side foot is fixed to the upper surface of the intake manifold, thereby enabling the intake side foot to be mounted and securely fixed to the robust intake manifold. Additionally, since the bolts securing the intake side foot to the intake manifold can be tightened or loosened from above the cylinder head, the aforementioned support platform can be installed and disassembled while the EGR device, located on the side of the intake side of the cylinder head, is mounted on the intake manifold, improving the assembly workability and maintainability of the engine assembly. Attached Figure Description

[0020] Figure 1 This is a summary front view of one embodiment of the engine device.

[0021] Figure 2 This is a summary rear view of this embodiment.

[0022] Figure 3 This is a summary left view of this embodiment.

[0023] Figure 4 This is a summary right view of this embodiment.

[0024] Figure 5 This is a top view summarizing this implementation method.

[0025] Figure 6 This is a magnified left view showing an overview of the two-stage supercharger.

[0026] Figure 7 This is an enlarged overview view showing the area around the two-stage supercharger.

[0027] Figure 8 This is an enlarged view showing a summary rear view around the two-stage supercharger.

[0028] Figure 9 This is a magnified top view showing the outline around the low-pressure stage turbocharger, with part of the cylinder head cover removed.

[0029] Figure 10 This is a schematic perspective view illustrating the installation structure of the low-pressure stage booster.

[0030] Figure 11 This is an enlarged view showing the outline of the support platform supporting the exhaust gas purification device.

[0031] Figure 12 This is a magnified summary left view showing the area around the support platform.

[0032] Figure 13 The right view shows an enlarged overview of the area around the support platform.

[0033] Figure 14 This is an enlarged top view showing the outline around the support platform.

[0034] Figure 15 This is a schematic exploded perspective view illustrating the installation structure of the support platform and the exhaust gas purification device.

[0035] Figure 16 Is Figure 14 The left view of the support platform and exhaust gas purification device is shown at section A-A.

[0036] Figure 17 This is a magnified overview of the main view around the cylinder head.

[0037] Figure 18 This is an enlarged top view showing a summary view of the front part of the cylinder head.

[0038] Figure 19 This is a magnified summary left view showing the front portion of the cylinder head.

[0039] Figure 20 This is a schematic perspective view showing the cylinder head without the front portion and part of the EGR cooler.

[0040] Figure 21 This is a top sectional view showing the structure of the exhaust flow path and intake flow path in the cylinder head.

[0041] Figure 22 This is a summary front view showing the configuration of the wiring harness around the front of the cylinder head.

[0042] Figure 23 This is a top-view summary showing the configuration of the wiring harness around the front of the cylinder head. Detailed Implementation

[0043] Hereinafter, embodiments in which the present invention is embodied will be described based on the accompanying drawings. First, referring to... Figures 1-5 The overall structure of engine 1, which is an example of an engine device, will be described below. In this embodiment, engine 1 is a diesel engine. It should be noted that, in the following description, regarding engine 1, the two sides parallel to the crankshaft 5 (the sides separated by the crankshaft 5) are referred to as "left and right", the side where the flywheel housing 7 is provided is referred to as "front side", and the side where the cooling fan 9 is provided is referred to as "rear side". For convenience, the above settings are used as the reference for the positional relationship of engine 1 around its perimeter and vertically.

[0044] like Figures 1-5 As shown, an intake manifold 3 is arranged on one side of the engine 1 parallel to the crankshaft 5, and an exhaust manifold 4 is arranged on the other side. In this embodiment, the intake manifold 3 is integrally formed with the cylinder head 2 on the right side. The exhaust manifold 4 is provided on the left side of the cylinder head 2. The cylinder head 2 is mounted on a cylinder block 6 that houses the crankshaft 5 and pistons (not shown).

[0045] The front and rear ends of the crankshaft 5 protrude from the front and rear sides of the cylinder block 6. A flywheel housing 7 is fixedly mounted on the side of the engine 1 that intersects with the crankshaft 5 (in this embodiment, the front side of the cylinder block 6). A flywheel 8 is disposed within the flywheel housing 7. The flywheel 8 is fixedly mounted on the front end of the crankshaft 5 and is configured to rotate integrally with the crankshaft 5. The flywheel 8 is configured to transfer the power of the engine 1 to the working part of the work machinery (e.g., a hydraulic excavator, a lifting forklift, etc.). A cooling fan 9 is provided on the other side of the engine 1 that intersects with the crankshaft 5 (in this embodiment, the rear side of the cylinder block 6). The fan 9 is configured to transmit rotational force from the rear end of the crankshaft 5 to the cooling fan 9 via a belt 10.

[0046] An oil pan 11 is disposed on the lower surface of the cylinder block 6. Lubricating oil accumulates in the oil pan 11. The lubricating oil in the oil pan 11 is drawn by a lubricating oil pump (not shown) and supplied to the various lubrication points of the engine 1 via an oil cooler 13 and an oil filter 14 disposed on the right side of the cylinder block 6. The lubricating oil pump is located at the connection between the cylinder block 6 and the flywheel housing 7, and is disposed on the right side of the cylinder block 6. The lubricating oil supplied to each lubrication point then returns to the oil pan 11. The lubricating oil pump is configured to be driven by the rotation of the crankshaft 5.

[0047] like Figure 4 As shown, a fuel supply pump 15 for supplying fuel is installed on the right side of the engine 1 at the connection between the cylinder block 6 and the flywheel housing 7. The fuel supply pump 15 is located below the EGR device 24. Furthermore, a common rail 16 is arranged between the intake manifold 3 of the cylinder head 2 and the fuel supply pump 15. The common rail 16 is fixed to the upper front part of the right side of the cylinder block 6. Each of the four cylinders has an injector (not shown) with an electromagnetically controlled fuel injection valve on the upper surface of the cylinder head 2, which is covered by the cylinder head cover 18.

[0048] Each injector is connected to a fuel tank (not shown) mounted on the work vehicle via a fuel supply pump 15 and a cylindrical common rail 16. Fuel from the fuel tank is pumped from the fuel supply pump 15 to the common rail 16, where the high-pressure fuel is stored. The fuel injection valves of each injector are opened and closed to inject the high-pressure fuel in the common rail 16 from each injector into each cylinder of the engine 1.

[0049] like Figure 2 as well as Figure 5As shown, a leakage reduction device 19 is provided on the upper surface of the cylinder head cover 18, which covers the intake valve and exhaust valve (not shown) located on the upper surface of the cylinder head 2. This leakage reduction device 19 takes in leakage gas that leaks from the combustion chamber of the engine 1 to the upper surface of the cylinder head 2. The leakage outlet of the leakage reduction device 19 is connected to the intake section of the two-stage turbocharger 30 via a reduction hose 68. After the lubricating oil components are removed in the leakage reduction device 19, the leakage gas returns to the intake manifold 3 via the two-stage turbocharger 30.

[0050] like Figure 3 As shown, an engine starting device 20 is installed on the flywheel housing 7 on the left side of the engine 1. The engine starting device 20 is located below the exhaust manifold 4. The engine starting device 20 is installed on the left side of the rear side of the flywheel housing 7, below the connection between the cylinder block 6 and the flywheel housing 7.

[0051] like Figure 2 As shown, a cooling water pump 21 for lubrication is located on the left side of the rear side of the cylinder block 6. An alternator 12, which generates electricity using the power of the engine 1, is located to the left of the cooling water pump 21. Rotational power is transmitted from the front end of the crankshaft 5 to the cooling fan 9, alternator 12, and cooling water pump 21 via belt 10. Cooling water from the radiator (not shown) of the work vehicle is supplied to the cooling water pump 21 by driving it. Furthermore, cooling water is supplied to the cylinder head 2 and cylinder block 6 to cool the engine 1.

[0052] like Figure 3 As shown, the cooling water pump 21 is positioned at a height lower than that of the exhaust manifold 4, and the cooling water inlet pipe 22, which connects to the cooling water outlet of the radiator, is fixedly installed on the left side of the cylinder block 6 and at a height approximately the same as that of the cooling water pump 21. On the other hand, as... Figure 2 as well as Figure 5 As shown, a cooling water outlet pipe 23, which is connected to the cooling water inlet of the radiator, is fixedly installed on the rear right side of the upper surface of the cylinder head 2. The cylinder head 2 has a cooling water drain section 35 at its right rear corner, and a cooling water outlet pipe 23 is provided on the upper surface of the cooling water drain section 35.

[0053] like Figure 4 as well as Figure 5As shown, the EGR device 24 is located on the right side of the cylinder head 2. The EGR device 24 includes: a collector 25, which is a relay line that mixes the recirculated exhaust gas (EGR gas from the exhaust manifold 4) of the engine 1 with fresh gas (outdoor air from the air purifier) ​​and supplies it to the intake manifold 3; an intake throttling component 26, which connects the collector 25 to the air purifier; a recirculated exhaust gas pipe 28, which is part of a return line connected to the exhaust manifold 4 via the EGR cooler 27; and an EGR valve component 29, which connects the collector 25 to the recirculated exhaust gas pipe 28.

[0054] In this embodiment, the collector 25 of the EGR device 24 is connected to the right side of the intake manifold 3, which is integrally formed with the cylinder head 2 to constitute the right side of the cylinder head 2. That is, the outlet opening of the collector 25 is connected to the inlet opening of the intake manifold 3 located on the right side of the cylinder head 2. Furthermore, the EGR gas inlet of the recirculation exhaust gas pipe 28, located at the front of the right side of the cylinder head 2, is connected to the EGR gas outlet of the EGR gas passage located within the cylinder head 2. The collector 25 is installed on the intake manifold 3, and the recirculation exhaust gas pipe 28 is installed on the cylinder head 2, thereby fixing the EGR device 24 to the cylinder head 2.

[0055] For the EGR unit 24, the intake manifold 3 and the intake throttling component 26 for introducing fresh gas are connected via the collector 25. The EGR valve component 29, connected to the outlet side of the recirculated exhaust gas pipe 28, is connected to the collector 25. The collector 25 is formed into an approximately cylindrical shape with a relatively long front and rear. The intake throttling component 26 is fastened to the gas intake side (front side in the length direction) of the collector 25 by bolts. The gas discharge side of the collector 25 is fastened to the inlet side of the intake manifold 3 by bolts. It should be noted that the EGR valve component 29 adjusts the amount of EGR gas supplied to the collector 25 by adjusting the opening of the EGR valve located inside it.

[0056] Fresh gas is supplied to collector 25, and EGR gas (a portion of the exhaust gas discharged from exhaust manifold 4) is supplied to collector 25 from exhaust manifold 4 via EGR valve component 29. The fresh gas and EGR gas from exhaust manifold 4 mix in collector 25, and then the mixture in collector 25 is supplied to intake manifold 3. That is, a portion of the exhaust gas discharged from engine 1 to exhaust manifold 4 returns to engine 1 from intake manifold 3, thereby reducing the maximum combustion temperature under high load operation and reducing the emission of NOx (nitrogen oxides) from engine 1.

[0057] like Figure 1 as well as Figures 3 to 5As shown, the EGR cooler 27 is fixed to the front side of the cylinder head 2. Cooling water and EGR gas flowing inside the cylinder head 2 flow in and out relative to the EGR cooler 27, cooling the EGR gas within the EGR cooler 27. A pair of left and right EGR cooler connecting parts 33 and 34 are provided on the front side of the cylinder head 2 for connecting the EGR cooler 27. Furthermore, the EGR cooler 27 is connected to the front side of the EGR cooler connecting parts 33 and 34. That is, the EGR cooler 27 is positioned above the flywheel housing 7 and in front of the cylinder head 2 in a manner that separates the rear side of the EGR cooler 27 from the front side of the cylinder head 2.

[0058] like Figures 1 to 3 as well as Figure 5 As shown, a two-stage turbocharger 30 is arranged on the left side of the cylinder head 2. The two-stage turbocharger 30 includes a high-pressure stage turbocharger 51 and a low-pressure stage turbocharger 52. The high-pressure stage turbocharger 51 has: a high-pressure stage turbine housing 53 with a built-in turbine (not shown); and a high-pressure stage compressor housing 54 with a built-in fan impeller (not shown). The low-pressure stage turbocharger 52 has: a low-pressure stage turbine housing 55 with a built-in turbine (not shown); and a low-pressure stage compressor housing 56 with a built-in fan impeller (not shown).

[0059] In the exhaust path of the two-stage turbocharger 30, the high-pressure stage turbine housing 53 is connected to the exhaust manifold 4, and the low-pressure stage turbine housing 55 is connected to the high-pressure stage turbine housing 53 via a high-pressure exhaust gas pipe 59. An exhaust connecting pipe 119 is connected to the low-pressure stage turbine housing 55. The high-pressure exhaust gas pipe 59 is formed of a flexible pipe. In this embodiment, a portion of the high-pressure exhaust gas pipe 59 is formed in a serpentine shape.

[0060] The tailpipe (not shown) is connected to the exhaust connection pipe 119 via the exhaust gas purification device 100. The exhaust gas discharged from each cylinder of the engine 1 to the exhaust manifold 4 is discharged to the outside through the tailpipe via the two-stage turbocharger 30 and the exhaust gas purification device 100.

[0061] In the intake path of the two-stage turbocharger 30, the low-pressure stage compressor housing 56 is connected to the air purifier via the air supply pipe 62, and the high-pressure stage compressor housing 54 is connected to the low-pressure stage compressor housing 56 via the low-pressure fresh gas passage pipe 65. The intake throttling component 26 of the EGR device 24 is connected to the high-pressure stage compressor housing 54 via the intercooler (not shown). The fresh gas (outdoor air) drawn into the air purifier is dusted and purified by the air purifier, and then delivered to the intake manifold 3 via the two-stage turbocharger 30, intercooler, intake throttling component 26, collector 25, etc., and is also supplied to each cylinder of the engine 1.

[0062] The exhaust gas purification device 100 is a device used to capture particulate matter (PM) and other particles in exhaust gas. For example... Figures 1-5 As shown, the exhaust gas purification device 100 has an approximately cylindrical shape that extends relatively long in the left-right direction intersecting the crankshaft 5 when viewed from above. In this embodiment, the exhaust gas purification device 100 is disposed above the front side of the cylinder head 2. The exhaust gas purification device 100 is supported on the front of the cylinder head 2 by means of the left support bracket 117, the right support bracket 118, and the support platform 121.

[0063] The exhaust gas intake side and exhaust gas discharge side are separately located on the left and right sides of the exhaust gas purification device 100 (one end and the other end along the length direction). The exhaust gas inlet pipe 116 of the exhaust gas intake side of the exhaust gas purification device 100 is connected to the exhaust outlet of the low-pressure stage turbine housing 55 of the two-stage turbocharger 30 via the exhaust connection component 120 and the straight exhaust connection pipe 119. The exhaust connection component 120 has an approximately L-shaped exhaust gas passage when viewed from the side. The exhaust connection component 120 is fixed to the left side of the support platform 121. The exhaust gas discharge side of the exhaust gas purification device 100 is connected to the exhaust gas intake side of the tailpipe (not shown).

[0064] The exhaust gas purification device 100 has the following structure: a diesel oxidation catalyst 102, such as platinum, and a honeycomb-structured particulate filter 103 are arranged in series inside. In this structure, nitrogen dioxide (NO2) generated by the oxidation of the diesel oxidation catalyst 102 is drawn into the particulate filter 103. Particulate matter contained in the exhaust gas of the engine 1 is captured by the particulate filter 103 and continuously removed by oxidation with nitrogen dioxide. Therefore, in addition to removing particulate matter (PM) from the exhaust gas of the engine 1, the content of carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas of the engine 1 is also reduced.

[0065] The exhaust gas purification device 100 includes: an upstream side box 105, which has an exhaust gas inlet pipe 116 on its outer peripheral surface; an intermediate box 106 connected to the upstream side box 105; and a downstream side box 107 connected to the intermediate box 106. The upstream side box 105 and the intermediate box 106 are connected in series to form a gas purification housing 104 made of heat-resistant metal material. A diesel oxidation catalyst 102 and a particulate filter 103 are housed within the gas purification housing 104 via a cylindrical inner box (not shown). Furthermore, the downstream side box 107 contains an inner box (not shown) with numerous silencing holes, and a ceramic fiber silencing material is filled between the downstream side box and the inner box, thus forming a silencer.

[0066] When exhaust gas passes through the diesel oxidation catalyst 102 and the particulate filter 103, if the exhaust gas temperature exceeds the regeneration temperature (e.g., about 300°C), the diesel oxidation catalyst 102 oxidizes the nitric oxide in the exhaust gas into unstable nitrogen dioxide. Furthermore, the oxygen released when nitrogen dioxide reverts to nitric oxide oxidizes and removes particulate matter accumulated in the particulate filter 103, thereby restoring the particulate matter capture capacity of the particulate filter 103 and regenerating it.

[0067] Next, refer to Figures 6-10 The structure and installation configuration of the two-stage turbocharger 30 will be described below. The two-stage turbocharger 30 utilizes the fluid energy of the exhaust gas discharged from the exhaust manifold 4 to compress the fresh gas flowing into the intake manifold 3 of the cylinder head 2. The two-stage turbocharger 30 is configured to include: a high-pressure stage turbocharger 51 connected to the exhaust manifold 4; and a low-pressure stage turbocharger 52 connected to the high-pressure stage turbocharger 51.

[0068] like Figure 7 as well as Figure 8 As shown, the high-pressure stage turbocharger 51 is positioned on the left side of the exhaust manifold 4. The low-pressure stage turbocharger 52 is positioned above the exhaust manifold 4. That is, the small-capacity high-pressure stage turbocharger 51 is positioned opposite the left side of the exhaust manifold 4, while the large-capacity low-pressure stage turbocharger 52 is positioned opposite the left side of the cylinder head 2 and the cylinder head cover 18. Therefore, in the space on the left side of the cylinder head 2, not only can the exhaust manifold 4 and the two-stage turbocharger 30 be arranged compactly within a square frame in both front and rear views, but the uppermost position of the two-stage turbocharger 30 can also be positioned lower than the uppermost position of the engine 1. Therefore, this contributes to the miniaturization of the engine 1.

[0069] In addition, such as Figure 3 as well as Figure 6 As shown, viewed from the left side of the engine 1, the low-pressure stage turbocharger 52 is located on the left side of the cylinder head 2 and in front of the high-pressure stage turbocharger 51. Therefore, space can be expanded below the low-pressure stage turbocharger 52 for arranging other application components around the front left side of the cylinder block 6. For example, an external auxiliary device such as a hydraulic pump that operates using the rotational force of the crankshaft 5 can be arranged between the low-pressure stage turbocharger 52 and the engine starting device 20.

[0070] like Figures 6-8As shown, the high-pressure stage turbocharger 51 includes: a high-pressure stage turbine housing 53; a high-pressure stage compressor housing 54 disposed behind the high-pressure stage turbine housing 53; and a high-pressure stage central housing 72 connecting the two housings 53 and 54. The high-pressure stage turbine housing 53 includes: a high-pressure stage exhaust inlet 57 connected to the exhaust manifold outlet 49 of the exhaust manifold 4; and a high-pressure stage exhaust outlet 58 connected to the upstream end of the high-pressure exhaust gas pipe 59. The high-pressure stage compressor housing 54 includes: a high-pressure stage fresh gas inlet 66 connected to the downstream end of the low-pressure fresh gas passage pipe 65; and a high-pressure stage fresh gas supply port 67 connected to the intercooler (not shown). It should be noted that the upstream end of the pipe refers to the end on the upstream side of the airflow, and the downstream end refers to the end on the downstream side of the airflow.

[0071] On the other hand, the low-pressure stage turbocharger 52 includes: a low-pressure stage turbine housing 55; a low-pressure stage compressor housing 56 disposed behind the low-pressure stage turbine housing 55; and a low-pressure stage central housing 75 connecting the two housings 55 and 56. The low-pressure stage turbine housing 55 includes: a low-pressure stage exhaust inlet 60 communicating with the downstream end of the high-pressure exhaust gas pipe 59; and a low-pressure stage exhaust outlet 61 communicating with the upstream end of the exhaust connecting pipe 119. The low-pressure stage compressor housing 56 includes: a low-pressure stage fresh gas inlet 63 communicating with the downstream end of the supply gas pipe 62; and a low-pressure stage fresh gas supply port 64 communicating with the upstream end of the low-pressure fresh gas passage pipe 65.

[0072] The exhaust manifold 4 has an exhaust outlet 49 that opens to the left. Furthermore, the high-pressure stage exhaust inlet 57 of the high-pressure stage turbine housing 53 opens towards the exhaust manifold 4, while the high-pressure stage exhaust outlet 58 opens forward. Additionally, the low-pressure stage exhaust inlet 60 of the low-pressure stage turbine housing 55 opens downward, while the low-pressure stage exhaust outlet 61 opens forward.

[0073] like Figures 6-8 As shown, in the two-stage supercharger 30, the high-pressure stage compressor housing 54 has a high-pressure stage fresh gas inlet 66 that opens rearward, while the high-pressure stage fresh gas supply port 67 opens downward. The low-pressure stage compressor housing 56 is configured such that the low-pressure stage fresh gas inlet 63 opens rearward, while the low-pressure stage fresh gas supply port 64 protrudes from the left side and faces rearward. Furthermore, the downstream end of the U-shaped low-pressure fresh gas passage pipe 65 is connected to the high-pressure stage fresh gas inlet 66, while the low-pressure stage fresh gas supply port 64 is connected to the upstream end of the low-pressure fresh gas passage pipe 65.

[0074] like Figures 6-8As shown, the exhaust outlet 49 of the exhaust manifold 4 is connected to the high-pressure exhaust inlet 57 of the high-pressure stage turbine housing 53 via bolts at the flange portion. This secures the high-pressure stage turbocharger 51 to the robust exhaust manifold 4. Furthermore, the high-pressure exhaust outlet 58 of the high-pressure stage turbine housing 53 is connected to the downstream end (rear end) of the approximately L-shaped high-pressure exhaust pipe 59 via bolts at the flange portion. On the other hand, the low-pressure exhaust inlet 60 of the low-pressure stage turbine housing 55 is connected to the upstream end (upper end) of the high-pressure exhaust pipe 59 via bolts at the flange portion. The approximately L-shaped high-pressure exhaust pipe 59 is constructed of flexible piping, and in this embodiment, a conical tube portion 59a is provided in the portion extending in the front-rear direction.

[0075] like Figure 9 as well as Figure 10 As shown, the low-pressure stage turbocharger 52 is fixed to the left side (exhaust side) of the cylinder head 2. In this embodiment, a low-pressure stage turbocharger mounting portion 131 is provided at the forward position of the central part of the left side of the cylinder head 2 (see also...). Figure 12 , Figure 16 , Figure 19 The low-pressure stage turbocharger mounting section 131 is located above the exhaust manifold 4 and opposite the low-pressure stage turbine housing 55. The low-pressure stage turbocharger 52 is mounted on the low-pressure stage turbocharger mounting section 131 by means of an approximately L-shaped mounting bracket 132. The mounting bracket 132 includes: a turbocharger side planar portion 132a, which is arranged in the left-right direction; and a cover side planar portion 132b, which protrudes forward from the right end of the turbocharger side planar portion 132a.

[0076] The supercharger side face 132b of the mounting bracket 132 is fixedly mounted to the right edge of the front side of the low-pressure stage compressor housing 56 by means of bolts 133. The cover side face 132a of the mounting bracket 132 is fixedly mounted to the low-pressure stage supercharger mounting part 131 by means of a pair of front and rear bolts 133. Thus, the low-pressure stage supercharger 52 is fixed to the robust cylinder head 2.

[0077] In this embodiment, the low-pressure stage turbocharger 52 is fixed to the left side (exhaust side) of the cylinder head 2, and the high-pressure stage turbocharger 51 is fixed to the exhaust manifold 4. Therefore, the high-pressure stage turbocharger 51 and the low-pressure stage turbocharger 52 constituting the two-stage turbocharger 30 can be separated and securely fixed to the robust cylinder head 2 and the exhaust manifold 4, respectively. In addition, since the low-pressure stage turbocharger 52 is connected to the support platform 121 fixed to the front of the cylinder head 2 via the exhaust connecting pipe 119 and the exhaust connecting member 120, not only can the low-pressure stage turbocharger 52 be reliably fixed to the engine 1, but the two-stage turbocharger 30 can also be reliably fixed to the engine 1.

[0078] Furthermore, since the high-pressure stage exhaust outlet 58 of the high-pressure stage turbocharger 51 and the low-pressure stage exhaust inlet 60 of the low-pressure stage turbocharger 52 are connected via a flexible high-pressure exhaust pipe 59, the risk of low-cycle fatigue damage to the high-pressure exhaust pipe 59 due to thermal expansion can be reduced. Furthermore, the stress exerted on the two-stage turbochargers 30 due to thermal expansion of the high-pressure exhaust pipe 59 can also be reduced. As a result, the stress exerted on the connection between the high-pressure stage turbocharger 51 and the exhaust manifold 4, and on the connection between the low-pressure stage turbocharger 52 and the cylinder head 2, can be reduced, preventing poor connection and damage to connecting components.

[0079] like Figure 9 as well as Figure 10 As shown, a rib 135 is provided inside the cylinder head 2, extending from the low-pressure stage turbocharger mounting portion 131 toward the right side (intake side) of the cylinder head 2. The rib 135 protrudes upward from the bottom surface 136 of the cylinder head. This increases the rigidity around the low-pressure stage turbocharger mounting portion 131 in the cylinder head 2, preventing deformation of the cylinder head 2 caused by the installation of the low-pressure stage turbocharger 52. Furthermore, a valve arm mechanism mounting seat 137, continuously extending in the left-right direction relative to the right end of the rib 135, protrudes upward from the bottom surface 136 of the cylinder head. This increases the rigidity of the rib 135, thereby increasing the rigidity around the low-pressure stage turbocharger mounting portion 131.

[0080] It should be noted that in this embodiment, engine 1 is an OHV type engine, and the space surrounded by cylinder head 2 and cylinder head cover 18 constitutes a valve arm chamber. Figure 9 As shown, the valve arm chamber houses the injector 138 and the valve mechanism. Multiple valve arm mechanism mounting seats 137 are equally spaced in the front-rear direction. Each valve arm mechanism mounting seat 137 has a valve arm shaft support 139 for supporting the valve arm shaft (not shown). Multiple valve arms 140 are axially supported on the valve arm shaft in a swing-free manner. The configuration is such that each valve arm 189 swings around the valve arm shaft, thereby causing the intake and exhaust valves (not shown) of each cylinder to open and close.

[0081] like Figure 3 , Figure 5 as well as Figure 6As shown, viewed from the left, the low-pressure stage turbocharger 52 is positioned close to the front side (one side) of the cylinder head 2, while the low-pressure stage exhaust outlet 61 of the low-pressure stage turbine housing 55 faces the front side of the cylinder head 2. Furthermore, the exhaust inlet pipe 116, which constitutes the exhaust inlet of the exhaust gas purification device 100, is positioned near the corner where the front side and right side (exhaust side) of the cylinder head 2 intersect. Therefore, the exhaust connecting pipe 119 and the exhaust connecting component 120 can be shortened and simplified. The exhaust connecting pipe 119 is a piping used to connect the low-pressure stage exhaust outlet 61 of the low-pressure stage turbocharger 52 and the exhaust inlet pipe 116 of the exhaust gas purification device 100. This allows the exhaust gas supplied to the exhaust gas purification device 100 to be maintained at a high temperature, preventing a decrease in the regeneration capacity of the exhaust gas purification device 1.

[0082] It should be noted that in this invention, as long as the exhaust inlet of the exhaust gas purification device 100 is located near the corner where the front side (one side) and the right side (exhaust side) of the cylinder head 2 intersect, the same effects as described in this embodiment can be obtained regardless of the mounting position and arrangement direction of the exhaust gas purification device 100. For example, the exhaust gas purification device 100 can be arranged horizontally in front of the cylinder head 2 and above the flywheel housing 7 (for example, see Japanese Patent Application Publication No. 2011-012598), or it can be arranged horizontally from front to back (along the direction of the crankshaft 5) above the cylinder head 2 (for example, see Japanese Patent Application Publication No. 2016-079870).

[0083] like Figure 3 , Figure 5 as well as Figure 6 As shown, a leak reduction device 19 for taking in leaked gas is provided on the cylinder head 2. The leak reduction device 19 is mounted and fixed on the upper surface of the cylinder head cover 18, which covers the upper surface of the cylinder head 2. Above the cylinder head 2, the leak outlet 70 of the leak reduction device 19 is positioned near the rear side (another side) of the cylinder head 2, facing the left side. In addition, the low-pressure stage fresh gas inlet 63 of the low-pressure stage compressor housing 56 of the low-pressure stage turbocharger 52 opens to the rear. A gas supply pipe 62 extending in the front-rear direction is connected to the low-pressure stage fresh gas inlet 63. As a result, the gas supply pipe 62 can be positioned near the leak outlet 70, the size of the reduction hose 68 used to connect the leak outlet 70 to the gas supply pipe 62 can be shortened, and freezing inside the reduction hose 68 can be prevented in low-temperature environments.

[0084] like Figure 6As shown, regarding the low-pressure stage compressor housing 56 and the high-pressure stage compressor housing 54, the low-pressure stage fresh gas inlet 63, the low-pressure stage fresh gas supply port 64, and the high-pressure stage fresh gas inlet 66 all open in the same direction (rearward). Therefore, the configuration facilitates the connection of the air supply pipe 62, which communicates with the air purifier, to the low-pressure stage fresh gas inlet 63, and facilitates the connection of the low-pressure stage fresh gas passage pipe 65 to both the low-pressure stage fresh gas supply port 64 and the high-pressure stage fresh gas inlet 66, thereby improving assembly operability.

[0085] Additionally, the low-pressure fresh gas passage pipe 65 includes: an approximately U-shaped metal pipe 65a, one end of which is fastened to the high-pressure fresh gas inlet 66 by bolts via a flange connection; and a resin pipe 65b, which connects the other end of the metal pipe 65a to the low-pressure fresh gas supply port 64 of the low-pressure compressor housing 56. Thus, the metal pipe 65a of the low-pressure fresh gas passage pipe 65 is fixed to the high-pressure compressor housing 54 with high rigidity, while the resin pipe 65b can mitigate assembly errors between the low-pressure compressor housing 56 and the metal pipe 65a and connect them.

[0086] Furthermore, the low-pressure fresh gas supply port 64 of the low-pressure compressor housing 56 extends diagonally upwards and to the left from the lower left portion of the outer peripheral surface of the low-pressure compressor housing 56 and bends backwards. This increases the curvature of the bent portion of the low-pressure fresh gas passage pipe 65 (metal pipe 65a). Consequently, turbulence within the low-pressure fresh gas passage pipe 65 is suppressed, allowing compressed air discharged from the low-pressure compressor housing 56 to be smoothly supplied to the high-pressure compressor housing 54.

[0087] like Figure 8 As shown, the high-pressure stage turbocharger 51 has a downward-extending fresh gas supply port 64 on the lower right side of the outer peripheral surface of the high-pressure stage compressor housing 54. The high-pressure stage compressor housing 54 is connected to a high-pressure fresh gas passage pipe 71, which is connected to an intercooler, through which compressed air is supplied to the intercooler. Additionally, a cooling water inlet pipe 22 opening to the left is provided below the high-pressure stage compressor housing 54. A cooling water pipe 150 connected to the radiator is connected to the cooling water inlet pipe 22. Therefore, since the high-pressure fresh gas passage pipe 71 and the cooling water pipe 150 can be centrally arranged, not only is the piping structure on the main unit side for the engine 1 simplified, but it also facilitates assembly and maintenance.

[0088] In addition, such as Figure 2 , Figure 4 as well as Figure 5As shown, a cooling water outlet pipe 23, an air supply pipe 62, and an intake throttling component 26 are arranged at the rear of the engine 1 (on the side of the cooling fan 9). Therefore, on the main unit side of the engine 1, with the radiator, air purifier, and intercooler utilizing the cooling air from the cooling fan 9 positioned behind the cooling fan 9, not only can the size of the cooling water piping connected to the radiator and the new air piping connected to the air purifier and intercooler be shortened, but the piping connection work can also be centralized. Therefore, not only are the assembly and maintenance operations on the main unit side easier, but the various components connected to the engine 1 can also be efficiently arranged on the main unit side.

[0089] like Figures 6-8 As shown, in the high-pressure stage turbocharger 51, the high-pressure lubricating oil supply pipe 73 and the high-pressure lubricating oil return pipe 74 are connected to the upper and lower parts of the outer peripheral surface of the high-pressure stage central housing 72, which is the connecting part between the high-pressure stage turbine housing 53 and the high-pressure stage compressor housing 54. In the low-pressure stage turbocharger 52, the low-pressure lubricating oil supply pipe 76 and the low-pressure lubricating oil return pipe 77 are connected to the upper and lower parts of the outer peripheral surface of the low-pressure stage central housing 75, which is the connecting part between the low-pressure stage turbine housing 55 and the low-pressure stage compressor housing 56.

[0090] The lower end of the high-pressure lubricating oil supply pipe 73 is connected to a connecting member 78a located at the center of the left side of the cylinder block 6, while the upper end is connected to the upper part of the high-pressure stage central housing 72 of the high-pressure stage turbocharger 51. A connecting joint 78b is provided at the upper part of the high-pressure stage central housing 72, which connects the upper end of the high-pressure lubricating oil supply pipe 73 to the lower end of the low-pressure lubricating oil supply pipe 76. The upper end of the low-pressure lubricating oil supply pipe 76 is connected to a connecting member 78c located at the upper part of the low-pressure stage central housing 75 of the low-pressure stage turbocharger 52. Thus, lubricating oil flowing in the oil passage within the cylinder block 6 is supplied to the high-pressure stage central housing 72 of the high-pressure stage turbocharger 51 via the high-pressure lubricating oil supply pipe 73, and to the low-pressure stage central housing 75 of the low-pressure stage turbocharger 52 via both the high-pressure lubricating oil supply pipe 73 and the low-pressure lubricating oil supply pipe 76.

[0091] The high-pressure lubricating oil supply pipe 73 is guided rearward and upward from the connecting member 78a on the left side of the cylinder block 6, passing between the high-pressure stage compressor housing 54 and the cylinder block 6, and directed to a position opposite the left side of the cylinder head 2. Furthermore, the high-pressure lubricating oil supply pipe 73 bypasses the rear end of the exhaust manifold 4 and passes through the right side of the high-pressure stage central housing 72 to the connecting joint 78b. Meanwhile, the low-pressure lubricating oil supply pipe 76 has an approximately L-shaped profile when viewed from the side, and is guided from the connecting joint 78b along the high-pressure stage turbocharger 51 and the high-pressure exhaust pipe 59 to the connecting member 78c. In this way, by shortening the dimensions of the lubricating oil supply pipes 73 and 76 and configuring them to be surrounded by the two-stage turbocharger 30, which is a high-rigidity component, lubricating oil can be efficiently supplied to the two-stage turbocharger 30, while also preventing damage to the lubricating oil supply pipes 73 and 76 from external forces.

[0092] Furthermore, for the high-pressure lubricating oil return pipe 74, one end (lower end) above the connecting member 78a is connected to the end face of the connecting joint 80 located at the center of the left side of the cylinder block 6. The other end (upper end) of the high-pressure lubricating oil return pipe 74 is connected to the lower part of the outer peripheral surface of the high-pressure stage central housing 72 of the high-pressure stage turbocharger 51. Additionally, one end (lower end) of the low-pressure lubricating oil return pipe 77 is connected to a connecting portion protruding obliquely upwards from the middle of the connecting joint 80. On the other hand, the other end (upper end) of the low-pressure lubricating oil return pipe 77 is connected to the lower part of the outer peripheral surface of the low-pressure stage central housing 75 of the low-pressure stage turbocharger 52. Therefore, the lubricating oil flowing in the high-pressure stage turbocharger 51 and the low-pressure stage turbocharger 52 converges at the connecting joint 80 from the lower part of the central housings 72 and 75 via the lubricating oil return pipes 74 and 77, and returns to the oil passage within the cylinder block 6.

[0093] The high-pressure lubricating oil return pipe 74 extends from below the high-pressure stage turbine housing 53, passing below the exhaust outlet 49 of the exhaust manifold 4, towards the connecting joint 80. Conversely, the low-pressure operation return pipe 77 passes between the high-pressure exhaust pipe 59 and the exhaust manifold 4, and extends towards the connecting joint 80. By shortening the dimensions of the lubricating oil return pipes 74 and 77 and configuring them to be covered by the two-stage turbocharger 30, which is a high-rigidity component, lubricating oil can be efficiently supplied to the two-stage turbocharger 30, while also preventing damage to the lubricating oil return pipes 74 and 77 from external forces.

[0094] Next, refer to Figures 11-16 The following describes the installation structure of the exhaust gas purification device 100. The exhaust gas purification device 100 is composed of an upstream side box 105, an intermediate box 106 and a downstream side box 107 connected in series in the above order, and is arranged horizontally above the front part of the cylinder head 2.

[0095] The connection between the upstream side box 105 and the intermediate box 106 is formed by a pair of thick plate-shaped clamping flanges 108 and 109 clamping and connecting them from both sides in the direction of exhaust gas movement. Specifically, the clamping flanges 108 and 109 clamp the connecting flange located at the downstream opening edge of the upstream side box 105 and the connecting flange located at the upstream opening edge of the intermediate box 106, thereby connecting the downstream side of the upstream side box 105 and the upstream side of the intermediate box 106 to form the gas purification housing 104. At this time, bolts are used to fasten the clamping flanges 108 and 109, thereby connecting the upstream side box 105 and the intermediate box 106 in a way that allows for assembly and disassembly.

[0096] Furthermore, the connection between the intermediate box 106 and the downstream side box 107 is held and connected from both sides in the direction of exhaust gas movement by a pair of thick plate-shaped clamping flanges 110 and 111. That is, the clamping flanges 108 and 109 clamp the connecting flange provided at the downstream opening edge of the intermediate box 106 and the connecting flange provided at the upstream opening edge of the downstream side box 107, thereby connecting the downstream side of the intermediate box 106 and the upstream side of the downstream side box 107 in a way that allows for disassembly and assembly.

[0097] An exhaust gas inlet pipe 116 is provided on the outer periphery of the exhaust inlet side of the upstream side box 105. The exhaust gas intake side of the exhaust gas inlet pipe 116 is connected to the low-pressure stage exhaust outlet 61 of the two-stage turbocharger 30 (see reference) via an exhaust connecting component 120, which serves as an exhaust relay, and an exhaust connecting pipe 119. Figure 6 (etc.) connected. The exhaust connection component 120 is configured in an approximately L-shape when viewed from the side, with the exhaust intake side located at the rear and connected to the exhaust connection pipe 119, and the exhaust discharge side located at the top and connected to the exhaust inlet pipe 116 of the exhaust gas purification device 100. For example Figure 11 , Figure 12 as well as Figure 16 As shown, the exhaust connection component 120 is installed on the front of the left side of the support platform 121 in a detachable manner using a pair of upper and lower bolts 122, 122.

[0098] like Figure 11 and Figure 15 As shown, the exhaust gas purification device 100 is mounted on the front of the cylinder head 2 by means of left and right support brackets 117, 118 and support platform 121. The exhaust gas purification device 100 includes: a left bracket fastening foot 112, which is welded and fixed to the lower part of the outer peripheral surface of the upstream side box 105; and a right bracket fastening foot 113, which is formed on the lower part of the clamping flange 110.

[0099] The left and right support brackets 117 and 118 are approximately L-shaped, and have a horizontal portion and an upright portion protruding upward from the left and right outer ends of the horizontal portion. The horizontal portion of the left support bracket 117 is fixed to the left side of the upper surface of the flat portion 121a of the support platform 121 by means of a pair of front and rear bolts. The horizontal portion of the right support bracket 118 is fixed to the right edge of the upper surface of the flat portion 121a of the support platform 121 by means of a pair of front and rear bolts. The left and right bracket fastening feet 112 and 113 of the exhaust gas purification device 100 are respectively installed on the left and right support brackets 117 and 118 by means of a pair of front and rear bolts and nuts.

[0100] A cutout 118a is formed on the upper surface of the upright portion of the right support bracket 118, which allows the heads of bolts used to fasten the lower parts of the clamping flanges 110 and 111 to be temporarily placed. When the exhaust gas purification device 100 is assembled to the engine 1, with the left and right support brackets 117 and 118 and the exhaust connection component 120 mounted on the support platform 121, the heads of the bolts used to fasten the lower parts of the clamping flanges 110 and 111 can be aligned with the cutout 118a of the right support bracket 118. This allows the exhaust gas purification device 100 to be aligned relative to the engine assembly 1, and facilitates the bolt fastening operation when assembling the exhaust gas purification device 100 to the engine 1, improving assembly workability.

[0101] like Figures 11-16 As shown, the flat portion 121a of the support platform 121 has an approximately L-shaped shape, with the right side longer than the left side when viewed from above. The flat portion 121a is configured to cover the front of the cylinder head 2 along its front and right sides when viewed from above. The exhaust gas purification device 100 is mounted above the flat portion 121a.

[0102] Furthermore, the support platform 121 has multiple feet 121b, 121c, 121d, and 121e that protrude downwards from the flat portion 121a and are fixed to the cylinder head 2. A convex arch is formed on the upper side between the feet 121b, 121c, 121d, and 121e. Regarding the cylinder head 2, an exhaust-side mounting portion 123b is provided at the front of the left side, a first central mounting portion 123c is provided at the upper part of the center of the front side, a second central mounting portion 123d is provided at the right edge of the front side, and an intake-side mounting portion 123e is provided at the front end of the upper surface of the integrally formed intake manifold 3 on the right side.

[0103] The lower end of the exhaust-side foot 121b is fixed to the exhaust-side mounting portion 123b by means of a pair of front and rear bolts. The lower end of the first central foot 121c is fixed to the first central mounting portion 123c by means of one bolt. The lower part of the second central foot 121d is fixed to the second central mounting portion 123d by means of a pair of upper and lower bolts. The intake-side foot 121e has a pair of front and rear bolt insertion holes that extend through in the vertical direction, and is mounted to the intake-side mounting portion 123e by means of a pair of front and rear bolts inserted into these bolt insertion holes.

[0104] like Figure 11 , Figures 13-15 as well as Figure 21 As shown, an intake manifold 3 is integrally formed on the right side of the cylinder head 2. Furthermore, an intake-side foot 121e is fixed to an intake-side mounting portion 123e, which is located on the intake manifold 3. Therefore, the intake-side foot 121e can be mounted and securely fixed to the robust intake manifold 3. Additionally, the front and rear bolts used to fix the intake-side foot 121e to the intake manifold 3 can be tightened or loosened from above the cylinder head 2. Therefore, for example, the EGR device 24 (see reference 24) located on the right side of the cylinder head 2 can be mounted on the intake manifold 3. Figure 5 The support platform 121 is installed and disassembled while the engine 1 is in the state of being installed in the intake manifold 3, thereby improving the assembly workability and maintainability of the engine 1.

[0105] like Figure 11 , Figure 13 as well as Figure 15 As shown, a pair of reinforcing ribs 124, 124 are provided protruding from the bottom of the intake-side mounting portion 123e and on the right side and lower surface of the intake manifold 3. The reinforcing ribs 124, 124 extend vertically, thereby increasing the strength of the intake manifold 3 around the intake-side mounting portion 123e. This prevents deformation of the intake manifold 3 and cylinder head 2 caused by the mounting of the support platform 121 onto the intake manifold 3.

[0106] like Figures 11-16As shown, the support platform 121 is integrally formed with a flat portion 121a and feet 121b, 121c, 121d, and 121e. Furthermore, an arch is formed between the feet 121b, 121c, 121d, and 121e, thus achieving weight reduction while ensuring the rigidity of the support platform 121. Additionally, by making the support platform 121 an integrally formed component, the number of parts can be reduced. Moreover, by forming an arched gap between the feet 121b, 121c, 121d, and 121e, heat accumulation around the feet 121b, 121c, 121d, and 121e can be prevented. Therefore, for example, thermal damage to electronic components around the feet of components such as the exhaust pressure sensor 151 (described later) can be prevented, and insufficient cooling of cooling components such as the EGR cooler 27 can be avoided.

[0107] Furthermore, the support platform 121 includes: an exhaust-side foot 121b, which is fixed to the left side of the cylinder head 2; an intake-side foot 121e, which is fixed to the right side of the cylinder head 2; and central feet 121c and 121d, which are fixed to the front side of the cylinder head 2. Therefore, the support platform 121 can be fixed to a total of three surfaces—the right side, the left side, and the front side—of the cylinder head 2, thereby improving the support rigidity of the exhaust gas purification device 100.

[0108] like Figure 11 , Figure 13 as well as Figure 15 As shown, the height and size (width) of the arches between the intake-side foot 121e and the second central foot 121d, between the central feet 121c and 121d, and between the exhaust-side foot 121b and the first central foot 121c are all different. Furthermore, the vertical length of the exhaust-side foot 121b is different from the vertical length of the intake-side foot 121e. By appropriately designing the lengths of these arches and feet, the vibrations on the intake and exhaust sides can be canceled out by the support platform 121, thereby reducing the vibration of the exhaust gas purification device 100.

[0109] like Figure 11 and Figure 16 As shown, the flat portion 121a and the feet 121b, 121c, 121d, and 121e of the support platform 121 are arranged to be spaced apart from the cylinder head cover 18. This forms a cooling air passage 148 between the support platform 121 and the cylinder head cover 18, from which a cooling fan 9 (see reference 1) located at the rear of the engine 1 is supplied. Figure 3Cooling air 149 (etc.) flows through the cooling air passage 148. Therefore, the cooling air 149 from the cooling fan 9 can be guided to the front side of the cylinder head 2 via the cooling air passage 148, and the area around the front side of the cylinder head 2 can be properly cooled. In this embodiment, since the EGR cooler 27 and the exhaust pressure sensor 151 (described later) are mounted on the front side of the cylinder head 2, the cooling air 149 guided from the cooling fan 9 to the front side of the cylinder head 2 via the cooling air passage 148 can promote the cooling of the EGR cooler 27 and prevent thermal damage to the exhaust pressure sensor 151.

[0110] Next, refer to Figures 17-21 The following describes the structure around the front side of cylinder head 2. Figure 21 As shown, the cylinder head 2 has multiple intake airflow paths 36 for introducing fresh gas into multiple intake ports (not shown); and multiple exhaust airflow paths 37 for discharging exhaust gas from multiple exhaust ports. Furthermore, an intake manifold 3, which converges the multiple intake airflow paths 36, is integrally formed on the right side of the cylinder head 2. The integral construction of the cylinder head 2 and the intake manifold 3 improves the airtightness of the intake manifold 3 relative to the intake airflow paths 36 and also enhances the rigidity of the cylinder head 2.

[0111] On the right side of the exhaust manifold 4, which connects to the left side of the cylinder head 2, an EGR gas outlet 41, communicating with the upstream EGR gas passage 31 within the cylinder head 2, and an exhaust inlet 42, communicating with multiple exhaust flow paths 37, open side-by-side in the front-rear direction. An exhaust manifold 43, communicating with the EGR gas outlet 41 and the exhaust inlet 42, is formed within the exhaust manifold 4. An exhaust manifold exhaust outlet 49, communicating with the exhaust manifold 43, opens at the rear of the left side of the exhaust manifold 4. If exhaust gas from the exhaust flow path 37 of the cylinder head 2 flows into the exhaust manifold 43 through the exhaust inlet 42, a portion of the exhaust gas, as EGR gas, flows from the EGR gas outlet 41 into the upstream EGR gas passage 31 within the cylinder head 2, while the remaining exhaust gas flows from the exhaust manifold exhaust outlet 49 into the two-stage turbocharger 30 (see reference). Figure 7 wait).

[0112] The cylinder head 2 has an exhaust manifold 4 connected to the left side (exhaust side) opposite the right side (intake side) where the intake manifold 3 is integrally formed, and an EGR cooler 27 connected to the front side (one of the two sides intersecting the exhaust side). Left and right EGR cooler connecting portions 33 and 34 protrude forward from the left and right edges (left and right front corners) of the front side of the cylinder head 2. The EGR cooler 27 is connected to the front sides of the left and right EGR cooler connecting portions 33 and 34. EGR gas passages 31 and 32 and cooling water passages 38 and 39 are formed within the EGR cooler connecting portions 33 and 34.

[0113] Since EGR gas passages 31 and 32 and cooling water passages 38 and 39 are formed in the EGR cooler connection parts 33 and 34, there is no need to install cooling water pipes and EGR gas pipes between the EGR cooler 27 and the cylinder head 2. Therefore, EGR gas and cooling water will not affect the expansion and contraction of the pipes, which not only ensures the sealing of the connection parts with the EGR cooler 27, but also improves the resistance to external factors such as heat and vibration (construction stability), and allows for a compact structure.

[0114] like Figure 17 , Figure 20 as well as Figure 21 As shown, an upstream EGR gas passage 31 is provided in the left EGR cooler connection 33, and a downstream EGR gas passage 32 is provided in the right EGR cooler connection 34. The upstream EGR gas passage 31 is roughly L-shaped when viewed from above, with one end opening on the front and left sides of the left EGR cooler connection 33, respectively, and connecting the lower left rear portion of the EGR cooler 27 to the EGR gas outlet 41 located on the front right side of the exhaust manifold 4. The downstream EGR gas passage 32 is also roughly L-shaped when viewed from above, with one end opening on the front and right sides of the right EGR cooler connection 34, respectively, and connecting the upper right rear portion of the EGR cooler 27 to the EGR gas inlet of the recirculation exhaust gas pipe 28.

[0115] A downstream cooling water passage 38 is formed within the left EGR cooler connection portion 33, guiding water from the front side of the left EGR cooler connection portion 33 to the rear. The downstream cooling water passage 38 is positioned higher than the upstream EGR gas passage 31, and is used to transport cooling water discharged from the upper left rear portion of the EGR cooler 27 to the cooling water passage within the cylinder head 2. Additionally, an upstream cooling water passage 39 is formed within the right EGR cooler connection portion 34, guiding water from the front side of the right EGR cooler connection portion 34 to the rear. The upstream cooling water passage 39 is positioned lower than the downstream EGR gas passage 32, and is used to transport cooling water flowing through the cooling water passage within the cylinder head 2 to the lower right rear portion of the EGR cooler 27.

[0116] like Figures 17-20As shown, an exhaust pressure sensor 151 for detecting the exhaust gas pressure in the exhaust manifold 4 is provided on the front side of the cylinder head 2. The exhaust pressure sensor 151 is mounted on an exhaust pressure sensor mounting portion 152, which protrudes forward from the upper part of the center of the front side of the cylinder head 2. The exhaust pressure sensor mounting portion 152 is located between the left and right EGR cooler connecting portions 33 and 34. In the engine 1 of this embodiment, the left edge of the exhaust pressure sensor mounting portion 152 is continuously formed relative to the upper part of the right edge of the left EGR cooler connecting portion 33.

[0117] The exhaust pressure sensor 151 is connected to the exhaust manifold 4 via an exhaust pressure bypass path 153 and an exhaust pressure detection pipe 154. The exhaust pressure bypass path 153 is located within the cylinder head 2, and the exhaust pressure detection pipe 154 connects the exhaust pressure bypass path 153 to the exhaust manifold 4. The exhaust pressure bypass path 153 extends from the front end of the left side of the cylinder head 2 towards the right, passing through the interior of the left EGR cooler connection 33 and leading into the exhaust pressure sensor mounting portion 152. Furthermore, the exhaust pressure bypass path 153 bends forward within the exhaust pressure sensor mounting portion 152, opening at the front side of the exhaust pressure sensor mounting portion 152. A hole-filling member 155 is installed on the front side of the exhaust pressure sensor mounting portion 152 to seal the end of the exhaust pressure bypass path 153.

[0118] like Figure 18 As shown, the exhaust pressure sensor mounting part 152 has a sensor mounting hole 152a, which extends downward from its upper surface and is connected to the exhaust pressure bypass path 153. When the exhaust pressure sensor 151 is mounted in the sensor mounting hole 152a, the lower end of the exhaust pressure sensor 151 is exposed in the exhaust pressure bypass path 153.

[0119] On the other hand, the exhaust pressure testing pipe 154 is positioned above the exhaust manifold 4 on the left side of the front of the left side of the cylinder head 2. A mounting base 156 for the testing pipe protrudes upwards from the front portion of the upper surface of the exhaust manifold 4. A rear connector component 157 is mounted on the upper surface of the testing pipe mounting base 156. Furthermore, a front connector component 158 ​​is mounted at the end of the exhaust pressure bypass path 153, which opens at the front end of the left side of the cylinder head 2. The front end of the exhaust pressure testing pipe 154 is connected to the exhaust pressure bypass path 153 via the front connector component 158. The rear end of the exhaust pressure testing pipe 154 is connected to the exhaust convergence section 43 (see reference 43) within the exhaust manifold 4 via the rear connector component 157. Figure 21Connection. It should be noted that an exhaust gas temperature sensor 159 is installed on the upper surface of the testing piping mounting base 156, and further forward than the rear connector component 157. The exhaust gas temperature sensor 159 is used to detect the temperature of the exhaust gas flowing in the exhaust manifold 43 within the exhaust manifold 4.

[0120] Heat conducted from the high-temperature exhaust manifold 4 to the exhaust pressure detection pipe 154 diffuses through the front connector component 158 ​​into the cylinder head 2. This prevents the heat from the exhaust manifold 4 and the exhaust pressure detection pipe 154 from being directly conducted to the heat-sensitive exhaust pressure sensor 151. Therefore, it prevents malfunctions and false alarms of the exhaust pressure sensor 151 caused by the heat from the exhaust manifold 4 and the exhaust pressure detection pipe 154, and also shortens the length of the exhaust pressure detection pipe 154. Furthermore, the shortened length of the exhaust pressure detection pipe 154 improves its reliability and simplifies its configuration, reducing design time and improving the manufacturability and assemblability of the engine 1.

[0121] like Figure 17 as well as Figure 20 As shown, a downstream cooling water passage 38 is provided near the exhaust pressure bypass path 153 within the left EGR cooler connection 33, thus efficiently reducing the gas temperature within the exhaust pressure bypass path 153. Therefore, the heat transferred from the gas in the exhaust pressure bypass path 153 to the exhaust pressure sensor 151 is contained within an acceptable range, and the exhaust pressure bypass path 153 is shortened, making it easier to form an exhaust pressure bypass path 153 facing the cylinder head 2. Furthermore, since the exhaust pressure bypass path 153 passes through the interior of the left EGR cooler connection 33 and the exhaust pressure sensor mounting portion 152, which protrude from the front side of the cylinder head 2, the gas within the exhaust pressure bypass path 153 can be efficiently cooled, preventing malfunctions or false alarms of the exhaust pressure sensor 151 caused by heat. Furthermore, the exhaust pressure sensor 151 is mounted on the exhaust pressure sensor mounting part 152, which is located between a pair of EGR cooler connecting parts 33 and 34 and protrudes from the front side of the cylinder head 2. Therefore, the exhaust pressure sensor 151 can be cooled efficiently, and the exhaust pressure sensor 151 can be prevented from malfunctioning or malfunctioning due to heat.

[0122] In addition, such as Figure 19As shown, the front connector component 158 ​​is mounted at a position higher than the upper surface of the detection piping mounting base 156. The exhaust pressure detection piping 154 extends from the rear connector component 157 in a left-forward direction, bends to the right and is guided diagonally upward past the exhaust gas temperature sensor 159, and then connects to the front connector component 158 ​​along the left side of the cylinder head 2, generally horizontally facing forward. The end of the exhaust pressure detection piping 154 on the front connector component 158 ​​side is positioned higher than the end on the rear connector component 157 side. Therefore, oil and moisture contained in the exhaust gas can be prevented from liquefying within the exhaust pressure detection piping 154 and seeping into the exhaust pressure bypass path 153, enabling accurate detection of exhaust gas pressure.

[0123] like Figures 17-21 As shown, the structure with protruding EGR cooler connection portions 33 and 34 eliminates the need for piping for EGR gas to connect the exhaust manifold 4, EGR cooler 27, and EGR device 24, thus reducing the number of connection points in the EGR gas passage. Therefore, in engine 1 where NOx reduction is achieved using EGR gas, not only can EGR gas leakage be reduced, but deformation caused by stress changes due to piping expansion and contraction can also be suppressed. Furthermore, since EGR gas passages 31 and 32 and cooling water passages 38 and 39 are formed within the EGR cooler connection portions 33 and 34, the shapes of each passage 31, 32, 38, and 39 formed within the cylinder head 2 can be simplified, allowing the cylinder head 2 to be easily cast without the use of complex cores.

[0124] Furthermore, since the left EGR cooler connection 33 on the exhaust manifold 4 side and the right EGR cooler connection 34 on the intake manifold 3 side are separated, the mutual influence caused by the thermal deformation of the EGR cooler connections 33 and 34 can be suppressed. Therefore, not only can gas leakage, coolant leakage, and damage be prevented at the connection points between the EGR cooler connections 33 and 34 and the EGR cooler 27, but the rigidity balance of the cylinder head 2 can also be maintained. In addition, since the volume of the front side of the cylinder head 2 can be reduced, the cylinder head 2 can be made lighter. Furthermore, since the EGR cooler 27 can be configured to be separated from the front side of the cylinder head 2, with space in front of and behind the EGR cooler 27, cooling air can flow around the EGR cooler 27, thereby improving the cooling efficiency of the EGR cooler 27.

[0125] like Figure 17As shown, a downstream cooling water passage 38 and an upstream EGR gas passage 31 are arranged vertically above and below the left EGR cooler connection 33, and a downstream EGR gas passage 32 and an upstream cooling water passage 39 are arranged vertically above and below the right EGR cooler connection 34. Furthermore, the cooling water inlet of the downstream cooling water passage 38 and the EGR gas inlet of the downstream EGR gas passage 32 are positioned at the same height, while the cooling water outlet of the upstream cooling water passage 39 and the EGR gas outlet of the downstream EGR gas passage 32 are positioned at the same height.

[0126] Because the structure includes EGR gas passages 31 and 32 and cooling water passages 38 and 39 within the separate and protruding EGR cooler connection portions 33 and 34, the effects of thermal deformation on both sides of the EGR cooler connection portions 33 and 34 are mitigated. Furthermore, within the EGR cooler connection portions 33 and 34, the EGR gas flowing through the EGR gas passages 31 and 32 is cooled by cooling water flowing through the cooling water passages 38 and 39, thereby suppressing the thermal deformation of the EGR cooler connection portions 33 and 34 themselves. Moreover, in each connection portion of the EGR cooler connection portions 33 and 34, the EGR gas passages 31 and 32 and the cooling water passages 38 and 39 are arranged with their vertical height positions interchanged. Therefore, the heat distribution in the EGR cooler connection portions 33 and 34 is in opposite vertical directions, which can reduce the effects of thermal deformation in the height direction of the cylinder head 2.

[0127] Next, refer to Figure 22 and Figure 23 A portion of the wiring harness structure disposed around the front side of the cylinder head 2 will be described. In the engine 1 of this embodiment, a wiring harness assembly 171, which bundles multiple wiring harnesses, is disposed along the right side of the cylinder head cover 18 in the longitudinal direction. The wiring harness assembly 171 branches from a main wiring harness assembly (not shown), which extends from an external connection wiring harness connector (not shown) mounted on the engine 1.

[0128] The front end of the wiring harness assembly 171 is disposed between the cylinder head cover 18 and the intake side foot 121e of the support platform 121. Near the right front corner of the cylinder head cover 18, the wiring harness assembly 171 branches into an EGR valve wiring harness 172, an EGR gas temperature sensor wiring harness 173, and a sensor wiring harness assembly 174. The EGR valve wiring harness 172 passes between the second central foot 121d and the intake side foot 121e of the support platform 121 and is electrically connected to the EGR valve component 29. The EGR gas temperature sensor wiring harness 173 passes between the second central foot 121d and the intake side foot 121e and is electrically connected to the EGR gas temperature sensor 181, which detects the exhaust gas temperature in the recirculated exhaust gas pipe 28.

[0129] Sensor harness assembly 174 is guided to the left from harness assembly 171 and bends downward at the front right side of the cylinder head cover 18. The front end of sensor harness assembly 174 branches into rotation angle sensor harness assembly 175 and exhaust pressure sensor harness 176. Exhaust pressure sensor harness 176 is guided to the left from harness assembly 174 through the first central foot 121c of cylinder head cover 18 and support platform 121 and is electrically connected to exhaust pressure sensor 151.

[0130] The rotation angle sensor harness assembly 175 extends downward from the sensor harness assembly 174 along the front side of the cylinder head 2. Furthermore, the rotation angle sensor harness assembly 175 bends to the left at a position directly above the flywheel housing 7 and is guided towards the lower left corner of the front side of the cylinder head 2. The rotation angle sensor harness assembly 175 branches into a crankshaft rotation angle sensor harness 177 and a camshaft rotation angle sensor harness 178. The crankshaft rotation angle sensor harness 177 is connected to the crankshaft rotation angle sensor 182 (see reference) mounted on the upper left side of the front of the flywheel housing 7. Figure 1 Electrical connection. The camshaft rotation angle sensor harness 178 is connected to the camshaft rotation angle sensor 183 mounted on the upper left edge of the flywheel housing 7 (see reference). Figure 1 Electrical connection.

[0131] like Figure 17 As shown, locking member mounting portions 185 and 186 are formed vertically arranged at the center of the left and right sides of the front side of the cylinder head 2. The upper locking member mounting portion 185 is positioned on the upper part of the front side of the cylinder head 2 between the right EGR cooler connection portion 34 and the first central mounting portion 123c. The lower locking member mounting portion 186 is positioned on the lower part of the front side of the cylinder head 2 between the left and right EGR cooler connections 33 and 34, and is positioned directly below the upper locking member mounting portion 185.

[0132] like Figure 22 and Figure 23 As shown, the rotation angle sensor harness assembly 175, which is opposite to the front side of the cylinder head 2, is mounted on the front side of the cylinder head 2 by means of the locking members 187 and 188 of the locking member mounting portions 185 and 186 mounted on the upper and lower sides. Moreover, the rotation angle sensor harness assembly 175 is guided from the harness assembly 174 through the right EGR cooler connection portion 34 and the first central foot 121c of the support platform 121, and between the cylinder head 2 and the EGR cooler 27, to a position opposite to the lower edge of the front side of the cylinder head 2.

[0133] EGR coolers 27 are mounted on a pair of left and right EGR cooler connectors 33 and 34 that protrude forward on the front side of the cylinder head 2. Furthermore, a space is formed between the back of the EGR cooler 27 and the cylinder head 2. By arranging the rotation angle sensor harness assembly 175 in this space along the vertical direction, the rotation angle sensor harness assembly 175 can be protected, and its layout design is easy.

[0134] Additionally, a space is formed between the side of the cylinder head cover 18 and the support platform 121. The wiring harness assemblies 171 and 174, as well as the wiring harnesses 172, 173, and 176, are arranged in this space, thereby protecting these wiring harnesses and the wiring harness assemblies and facilitating the layout design of the wiring harnesses.

[0135] like Figures 1 to 10 As shown, the engine 1 includes: an exhaust manifold 4 disposed on one side of the cylinder head 2, i.e., the exhaust side (e.g., the left side); and a two-stage turbocharger 30 driven by exhaust gases discharged from the exhaust manifold 4. The two-stage turbocharger 30 includes: a high-pressure stage turbocharger 51 connected to the exhaust manifold 4; and a low-pressure stage turbocharger 52 connected to the high-pressure stage turbocharger 51. Since the high-pressure stage turbocharger 51 is disposed to the side of the exhaust manifold 4 and the low-pressure stage turbocharger 52 is disposed above the exhaust manifold 4, the exhaust manifold 4 and the two-stage turbocharger 30 can be compactly arranged within an approximately rectangular frame, thereby enabling miniaturization of the engine 1. Furthermore, since the high-pressure stage exhaust outlet 58 of the high-pressure stage turbocharger 51 and the low-pressure stage exhaust inlet 60 of the low-pressure stage turbocharger 52 are connected via a high-pressure exhaust pipe 59, which is an example of a flexible pipe, the risk of low-cycle fatigue damage to the high-pressure exhaust pipe 59 caused by thermal elongation can be reduced.

[0136] In engine 1, since the low-pressure stage turbocharger 52 is fixed to the exhaust side of cylinder head 2 and the high-pressure stage turbocharger 51 is fixed to exhaust manifold 4, the high-pressure stage turbocharger 51 and the low-pressure stage turbocharger 52 constituting the two-stage turbocharger 30 can be separated and securely fixed to the robust cylinder head 2 and exhaust manifold 4. Furthermore, since the high-pressure stage exhaust outlet 58 of the high-pressure stage turbocharger 51 and the low-pressure stage exhaust inlet 60 of the low-pressure stage turbocharger 52 are connected via a flexible high-pressure exhaust pipe 59, the stress exerted on the two-stage turbocharger 30 due to the thermal expansion of the high-pressure exhaust pipe 59 can be reduced. As a result, the stress exerted on the connection between the high-pressure stage turbocharger 51 and the exhaust manifold 4, and the stress exerted on the connection between the low-pressure stage turbocharger 52 and the cylinder head 2, can be reduced, preventing poor connection of these connections and damage to the connecting parts.

[0137] Furthermore, the cylinder head 2 has ribs 135 extending from the low-pressure stage turbocharger mounting portion 131 on the exhaust side toward the intake side (e.g., the right side) opposite to the exhaust side. Therefore, the rigidity around the low-pressure stage turbocharger mounting portion 131 in the cylinder head 2 can be improved, and deformation of the cylinder head 2 caused by mounting the low-pressure stage turbocharger 52 relative to the cylinder head 2 can be prevented.

[0138] Furthermore, the engine 1 includes an exhaust gas purification device 100 for purifying the exhaust gas from the engine 1. The exhaust gas inlet pipe 116, serving as the exhaust inlet of the exhaust gas purification device 100, is located near the corner where one of the two sides of the cylinder head 2 intersects with the exhaust side. Viewed from the exhaust side, the low-pressure stage turbocharger 52 is positioned close to one of these sides, and the low-pressure stage exhaust outlet 61 of the low-pressure stage turbocharger 52 faces that side. Therefore, for the engine 1, the exhaust connecting pipe 119 and the exhaust connecting component 120 can be shortened and simplified. The exhaust connecting pipe 119 is an example of a piping system for connecting the low-pressure stage exhaust outlet 61 of the low-pressure stage turbocharger 52 to the exhaust gas inlet pipe 116 of the exhaust gas purification device 100. This allows the exhaust gas supplied to the exhaust gas purification device 100 to be maintained at a high temperature, preventing a decrease in the regeneration capacity of the exhaust gas purification device 100.

[0139] Furthermore, above the cylinder head 2, on the opposite side of the cylinder head 2 (near the aforementioned side), facing the exhaust side, is a leakage outlet 70 of the leakage recovery device 19, and a low-pressure fresh gas inlet 63 of the low-pressure stage turbocharger 52 is also positioned facing the aforementioned opposite side. Additionally, the air supply pipe 62 is connected to the low-pressure fresh gas inlet 63 of the low-pressure stage turbocharger 52, and the leakage outlet 70 is connected to the air supply pipe 62 via a recovery hose 68. Therefore, for the engine 1, by positioning both the leakage outlet 70 of the leakage recovery device 19 and the air supply pipe 62 connected to the low-pressure fresh gas inlet 63 of the low-pressure stage turbocharger 52 on the cylinder head 2 near the aforementioned opposite side, the recovery hose 68 can be shortened, and measures to prevent freezing inside the recovery hose 68 are unnecessary.

[0140] like Figures 1 to 5 as well as Figures 11-16As shown, the engine 1 is equipped with an exhaust gas purification device 100 above the cylinder head 2 via a support platform 121. The support platform 121 includes: a flat portion 121a for mounting the exhaust gas purification device 100; and a plurality of legs 121b, 121c, 121d, and 121e protruding downward from the flat portion 121a and fixed to the cylinder head 2. The flat portion 121a and the legs 121b, 121c, 121d, and 121e are integrally formed. In addition, the legs 121b, 121c, 121d, and 121e are arched relative to each other. Therefore, the rigidity of the support platform 121 and its arched shape can be ensured and weight reduction can be achieved through the aforementioned integral forming structure and arched shape. Furthermore, by making the support platform 121 an integrally formed component, the number of components can be reduced. Furthermore, since an arched gap is formed between the multiple feet 121b, 121c, 121d, and 121e, it is possible to prevent the formation of heat accumulation around the feet of the support platform 121. For example, it is possible to prevent thermal damage to electronic components such as the exhaust pressure sensor 151, which is an example of a sensor mounted around the feet, and to prevent insufficient cooling of cooling components such as the EGR cooler 27.

[0141] Engine 1 has a structure in which the exhaust manifold 4 and intake manifold 3 are separately arranged on the exhaust side and intake side of the cylinder head 2, which are opposite each other. Support 121 is disposed above one of the two sides of the cylinder head 2, which intersect the crankshaft 5 axially, and has the following features as feet: an exhaust side foot 121b fixed to the exhaust side; an intake side foot 121e fixed to the intake side; and central feet 121c and 121d fixed to the aforementioned side. Therefore, engine 1 can fix support 121 to three surfaces of the cylinder head 2—the exhaust side, the intake side, and the aforementioned side—thereby improving the support rigidity of the exhaust gas purification device 100. Furthermore, by making the height and size of the arch between the exhaust-side foot 121b and the first central foot 121c, and the arch between the intake-side foot 121e and the second central foot 121d different, or by making the lengths of the exhaust-side foot 121b and the intake-side foot 121e different, the vibrations of the intake side and the exhaust side can be canceled out by the support platform 120, thereby reducing the vibration of the exhaust gas purification device 100.

[0142] Furthermore, the engine 1 has a cooling fan 9 on one of the two sides of the cylinder head 2. A cooling air passage 148 is formed between the cylinder head cover 18 and the support platform 121 on the cylinder head 2, through which cooling air 149 from the cooling fan 9 flows. Therefore, the engine 1 can guide the cooling air from the cooling fan 9 to one side of the cylinder head 2 via the cooling air passage 148, thereby appropriately cooling the area around that side of the cylinder head 2.

[0143] Furthermore, the engine 1 is configured to include: an EGR device 24, which allows a portion of the exhaust gas discharged from the exhaust manifold 4 to return as EGR gas to the intake manifold 3; an EGR cooler 27, which cools the EGR gas; and an exhaust pressure sensor 151, which detects the exhaust gas pressure within the exhaust manifold 4. The EGR cooler 27 and the exhaust pressure sensor 151 are mounted on one side of the cylinder head 2. Therefore, cooling air 149 guided from the cooling fan 9 through the cooling air passage 148 to the aforementioned side can promote cooling of the EGR cooler 27 and prevent thermal damage to the exhaust pressure sensor 151.

[0144] Furthermore, in engine 1, since the intake manifold 3 is integrally formed on the intake side of cylinder head 2, and the intake side foot 121e is fixed to the upper surface of the intake manifold 3, the intake side foot 121e can be mounted and securely fixed to the robust intake manifold 3. Additionally, since the bolts securing the intake side foot 121e to the intake manifold 3 can be tightened or loosened from above cylinder head 2, the support platform 121 can be installed and disassembled while the EGR device 24, located on the side of the intake side of cylinder head 2, is mounted on the intake manifold 3, thus improving the assembly workability and maintainability of engine 1.

[0145] like Figures 1 to 5 as well as Figures 17-21As shown, engine 1 includes: an exhaust manifold 4 disposed on the exhaust side of cylinder head 2; and an exhaust pressure sensor 151 that detects the exhaust gas pressure within the exhaust manifold 4. The exhaust pressure sensor 151 is mounted on cylinder head 2, and the exhaust manifold 4 and exhaust pressure sensor 151 are connected via an exhaust pressure bypass path 153 disposed within cylinder head 2 and an exhaust pressure detection pipe 154 for connecting the exhaust pressure bypass path 153 to the exhaust manifold 4. Therefore, heat dissipation of the exhaust pressure detection pipe 154 can be achieved using cylinder head 2. Thus, engine 1 can prevent malfunction or false alarm of exhaust pressure sensor 151 caused by heat from the exhaust manifold 4 and exhaust pressure detection pipe 154, and can also shorten the length of exhaust pressure detection pipe 154. Furthermore, by shortening the length of the exhaust pressure detection pipe 154, the reliability of the exhaust pressure detection pipe 154 can be improved, and the configuration of the exhaust pressure detection pipe 154 becomes easier, reducing design time and improving the manufacturability and assemblability of the engine 1. Furthermore, in the engine 1, a cooling water passage 38 is provided within the cylinder head 2 and near the exhaust pressure bypass path 153, thus efficiently reducing the gas temperature within the exhaust pressure bypass path 153. Therefore, the engine 1 can reduce the heat conducted from the gas in the exhaust pressure bypass path 153 to the exhaust pressure sensor 151 to an acceptable range, and the exhaust pressure bypass path 153 can be shortened, making it easier to form the exhaust pressure bypass path 153 leading to the cylinder head 2.

[0146] Engine 1 is configured to include: an EGR device 24, which allows a portion of the exhaust gas discharged from the exhaust manifold 4 to return as EGR gas to the intake manifold 3; and an EGR cooler 27, which cools the EGR gas. Cylinder head 2 has a pair of EGR cooler connection portions 33, 34 protruding from one of its two sides intersecting the exhaust side. Cooling water passage 38 passes through one EGR cooler connection portion 33 and connects to the EGR cooler 37. Exhaust pressure bypass path 153 passes through the EGR cooler connection portion 33. Therefore, engine 1 can efficiently cool the gas within the exhaust pressure bypass path 153, preventing malfunction or false alarm of the exhaust pressure sensor 151 due to heat.

[0147] Furthermore, the exhaust pressure sensor 151 is mounted on the exhaust pressure sensor mounting portion 152, which protrudes from one side of the cylinder head 2 between a pair of EGR cooler connecting portions 33 and 34. Therefore, the engine 1 can efficiently cool the exhaust pressure sensor 151, preventing malfunctions or false alarms caused by heat.

[0148] It should be noted that the structure of each part in this invention is not limited to the embodiments shown in the figures, and various changes can be made without departing from the spirit of this invention.

[0149] Explanation of reference numerals in the attached figures:

[0150] 1: Engine (engine unit); 2: Cylinder head; 3: Intake manifold; 4: Exhaust manifold; 30: Two-stage turbocharger; 51: High-pressure stage turbocharger; 52: Low-pressure stage turbocharger; 59: High-pressure exhaust gas piping (flexible piping); 131: Low-pressure stage turbocharger mounting section; 135: Rib; 100: Exhaust gas purification device; 116: Exhaust gas inlet pipe (exhaust inlet of the exhaust gas purification device); 19: Leakage reduction device; 70: Leakage outlet; 63: Low-pressure stage fresh gas inlet (fresh gas inlet of the low-pressure stage turbocharger); 62: Air supply pipe; 68: Reduction hose.

Claims

1. An engine assembly, wherein an exhaust gas purification device is mounted on a support platform, characterized in that, Between the cylinder head cover and the support platform, there is a space that is open on both sides in the crankshaft direction.

2. The engine device according to claim 1, characterized in that, The space is provided between the cylinder head cover on the cylinder head and the lower part of the support platform.

3. The engine device according to claim 1, characterized in that, An opening is provided between the cylinder head cover and the support platform.

4. The engine device according to claim 3, characterized in that, The opening is located above one of the two sides of the cylinder head that intersect with the exhaust side and the intake side, and a cooling fan is provided on the other side of the two sides.

5. The engine device according to claim 4, characterized in that, The support platform has a mounting part for mounting the exhaust gas purification device above the opening.

6. The engine device according to claim 1, characterized in that, The support platform has a curved portion on its upper surface side.

7. The engine device according to claim 6, characterized in that, The space is a cooling air passage, in which cooling air from the cooling fan flows.

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