Engine device

Abstract

To arrange a two-stage supercharger as compactly as possible when arranging the two-stage supercharger in a Diesel engine.SOLUTION: An engine device 1 comprises an exhaust manifold 4 and a supercharger 30. The supercharger 30 is configured as a two-stage supercharger consisting of a high-pressure supercharger 51 connected to the exhaust manifold 4 and a low-pressure supercharger 52 connected to the high-pressure supercharger 51. An exhaust outlet of the high-pressure supercharger 51 and an exhaust inlet of the low-pressure supercharger 52 are located at different positions in a crankshaft direction. The low-pressure supercharger 52 is located above the high-pressure supercharger 51.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an engine device equipped with a turbocharger. [Background technology]

[0002] Conventionally, in order to increase the air density in the cylinder of an engine for the purpose of improving engine output and fuel efficiency, a turbocharger that compresses fresh air using exhaust energy has been installed in an engine device (see Patent Document 1). In a diesel engine, a large amount of high-density air is supplied into the cylinder to combust a large amount of fuel, not only increasing the engine output and engine torque but also suppressing premixed combustion by promoting the mixing of fuel and air, thereby reducing NOx emissions.

[0003] Furthermore, since a single-stage turbocharger using one turbocharger has limitations in terms of meeting the requirements for a high-output engine, an engine equipped with a two-stage turbocharger in which two turbochargers are connected in series at the high-pressure stage and the low-pressure stage has been proposed (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4517550 [Patent Document 2] Patent No. 5237785 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the mounting space for diesel engines varies depending on the work vehicle (construction machinery, agricultural machinery, etc.) on which they are to be mounted, but in recent years, due to demands for lighter weight and compactness, mounting space is often restricted (narrow). For this reason, it is necessary to layout the components of diesel engines in a compact manner. In addition to the problem of mounting space restrictions, a highly rigid structure is required for the cylinder head, as components such as the EGR device and turbocharger are connected to and supported by the cylinder head.

[0006] In addition, when the high-pressure stage and low-pressure stage turbochargers in a two-stage turbocharger are arranged above and below at positions spaced apart from the exhaust manifold as in the engine device of Patent Document 2, the moment acting on the exhaust manifold outlet supporting the two-stage turbocharger increases, resulting in a decrease in the support rigidity of the two-stage turbocharger. Also, since the bypass route provided on the turbine side of the high-pressure stage is an external pipe, the piping structure of the two-stage turbocharger becomes complicated, and assembly to the engine device becomes cumbersome.

[0007] The present invention has as its technical object to provide an engine device which has been improved upon by examining the current situation as described above. [Means for solving the problem]

[0008] An engine device according to one aspect of the present application is an engine device including an exhaust manifold and a turbocharger. The turbocharger is configured as a two-stage turbocharger including a high-pressure turbocharger connected to the exhaust manifold and a low-pressure turbocharger connected to the high-pressure turbocharger. The low-pressure turbocharger is located above the high-pressure turbocharger. [Brief description of the drawings]

[0009] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a perspective view of the engine as seen obliquely from the front. [Figure 8] FIG. 2 is a perspective view of the engine as seen obliquely from the rear. [Figure 9] FIG. 2 is an enlarged perspective view of the cylinder head as seen from the intake manifold side. [Figure 10] FIG. 2 is an exploded perspective view of the cylinder head as viewed from the exhaust manifold side. [Figure 11] FIG. 2 is an exploded perspective view of the cylinder head as viewed from the intake manifold side. [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. 2 is a cross-sectional perspective view of a cylinder head and an EGR device. [Figure 15] FIG. 2 is a cross-sectional perspective view of a cylinder head and an exhaust manifold. [Figure 16] FIG. 2 is a cross-sectional perspective view of a connecting portion of the cylinder head with an EGR cooler. [Figure 17] FIG. 2 is a cross-sectional perspective view of the EGR device. [Figure 18] FIG. 2 is a plan view of the EGR device. [Figure 19] FIG. 2 is an exploded perspective view of the EGR device. [Figure 20] FIG. 4 is an exploded view of a connection portion of the cylinder head with the EGR cooler. [Figure 21] FIG. 4 is a cross-sectional view of a connecting portion of the cylinder head with an EGR cooler. [Figure 22] FIG. 2 is a left side view of the engine for explaining the arrangement of a two-stage turbocharger. [Diagram 23] FIG. [Figure 24] FIG. [Diagram 25] FIG. 2 is a left side view of the two-stage turbocharger. [Figure 26]FIG. 2 is a perspective view of a two-stage turbocharger. [Figure 27] FIG. 2 is a right side view of the two-stage turbocharger. [Figure 28] FIG. [Figure 29] FIG. 4 is a partial cross-sectional view of a cooling water pump mounting portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the overall structure of a diesel engine (engine device) 1 will be described with reference to Figs. 1 to 8. In the following description, both sides parallel to the crankshaft 5 (both sides sandwiching the crankshaft 5) will be referred to as the left and right, the side where the flywheel housing 7 is installed will be referred to as the front side, and the side where the cooling fan 9 is installed will be referred to as the rear side, and for the sake of convenience, these will be used as the basis for the four sides and the vertical positional relationship of the diesel engine 1.

[0011] 1 to 8, an intake manifold 3 is disposed on one side parallel to a crankshaft 5 of a diesel engine 1, and an exhaust manifold 4 is disposed on the other side. In this embodiment, the intake manifold 3 is molded integrally with the cylinder head 2 on the right side thereof, and the exhaust manifold 4 is disposed on the left side thereof. The cylinder head 2 is mounted on a cylinder block 6 that incorporates the crankshaft 5 and pistons (not shown).

[0012] The front and rear ends of the crankshaft 5 protrude from both the front and rear side surfaces of the cylinder block 6. A flywheel housing 7 is fixed to one side (in the embodiment, the front side surface of the cylinder block 6) of the diesel engine 1 that intersects with the crankshaft 5. A flywheel 8 is disposed in the flywheel housing 7. The flywheel 8 is journaled on the front end side of the crankshaft 5 and is configured to rotate integrally with the crankshaft 5. The power of the diesel engine 1 is adapted to be taken out via the flywheel 8 to a working section of a work machine (e.g., a hydraulic excavator, a forklift, etc.). A cooling fan 9 is provided on the other side (in the embodiment, the rear side surface of the cylinder block 6) of the diesel engine 1 that intersects with the crankshaft 5. The rotational force is adapted to be transmitted from the rear end side of the crankshaft 5 to the cooling fan 9 via a V-belt 10.

[0013] An oil pan 11 is disposed on the underside of the cylinder block 6. Lubricating oil is stored in the oil pan 11. The lubricating oil in the oil pan 11 is sucked by an oil pump (not shown) disposed on the right side of the cylinder block 6, which is a connecting portion between the cylinder block 6 and the flywheel housing 7, and is supplied to each lubricated part of the diesel 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 supplied to each lubricated part is then returned to the oil pan 11. The oil pump (not shown) is configured to be driven by the rotation of the crankshaft 5.

[0014] A fuel supply pump 15 for supplying fuel is attached to the connecting portion of the cylinder block 6 with the flywheel housing 7, and the fuel supply pump 15 is disposed below the EGR device 24. A common rail 16 is fixed to the side of the cylinder block 6 below the intake manifold 3 of the cylinder head 2, and is disposed above the fuel supply pump 15. On the upper surface of the cylinder head 2 covered with a head cover 18, injectors (not shown) for each of the four cylinders, each having an electromagnetic open / close control type fuel injection valve, are provided.

[0015] 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, and the high-pressure fuel is stored in the common rail 16. By controlling the opening and closing of a fuel injection valve of each injector, the high-pressure fuel in the common rail 16 is injected from each injector into each cylinder of the diesel engine 1.

[0016] The upper surface of the head cover 18 that covers the intake valve and exhaust valve (not shown) provided on the upper surface of the cylinder head 2 is covered with a head cover 18. A blow-by gas reduction device 19 is provided to take in the blow-by gas that has been removed. A blow-by gas outlet of the blow-by gas reduction device 19 is connected to the intake section of the two-stage turbocharger 30 via a return hose 68. The blow-by gas from which the lubricating oil components have been removed in the blow-by gas reduction device 19 is returned to the intake manifold 3 via the two-stage turbocharger 30.

[0017] An engine starter 20 is attached to the flywheel housing 7, and is disposed below the exhaust manifold 4. The engine starter 20 is attached to the flywheel housing 7 at a position below the joint between the cylinder block 6 and the flywheel housing 7.

[0018] A cooling water pump 21 for lubricating the cooling water is disposed below the cooling fan 9 at a position near the left rear surface of the cylinder block 6. The cooling water pump 21 is driven together with the cooling fan 9 via a cooling fan drive V-belt 10 by the rotation of the crankshaft 5. Cooling water in a radiator (not shown) mounted on the work vehicle is supplied to the cooling water pump 21 by the drive of the cooling water pump 21. The cooling water is then supplied to the cylinder head 2 and the cylinder block 6 to cool the diesel engine 1.

[0019] The cooling water pump 21 is disposed below the exhaust manifold 4, and a cooling water inlet pipe 22, which is connected to the cooling water outlet of the radiator, is fixed to the left side surface of the cylinder block 6 at the same height as the cooling water pump 21. Meanwhile, a cooling water outlet pipe 23, which is connected to the cooling water inlet of the radiator, is fixed to the upper rear surface of the cylinder head 2. The cylinder head 2 has a cooling water drainage section 35 that protrudes rearward from the intake manifold 3, and the cooling water outlet pipe 23 is installed on the upper surface of the cooling water drainage section 35.

[0020] The inlet side of the intake manifold 3 is connected to an air cleaner (not shown) via a collector (EGR main body case) 25 of an EGR device 24 (exhaust gas recirculation device) described later. Fresh air (outside air) sucked into the air cleaner is cleaned and purified by the air cleaner, then sent to the intake manifold 3 via the collector 25 and supplied to each cylinder of the diesel engine 1. 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 molded with the cylinder head 2 and forms the right side of the cylinder head 2. That is, the outlet opening of the collector 25 of the EGR device 24 is connected to the inlet opening of the intake manifold 3 provided on the right side of the cylinder head 2. In this embodiment, the collector 25 of the EGR device 24 is connected to the air cleaner via an intercooler (not shown) and a two-stage turbocharger 30, as described later.

[0021] The EGR device 24 has a collector 25 as a relay pipeline that mixes the recirculated exhaust gas (EGR gas from the exhaust manifold 4) of the diesel engine 1 with fresh air (external air from the air cleaner) and supplies the mixture to the intake manifold 3, an intake throttle member 26 that connects the collector 25 to the air cleaner, a recirculated exhaust gas pipe 28 that is part of the return pipeline connected to the exhaust manifold 4 via an EGR cooler 27, and an EGR valve member 29 that connects the collector 25 to the recirculated exhaust gas pipe 28.

[0022] The EGR device 24 is disposed on the right side of the intake manifold 3 in the cylinder head 2. That is, the EGR device 24 is fixed to the right side surface of the cylinder head 2 and communicates with the intake manifold 3 inside the cylinder head 2. The EGR device 24 is fixed such that a collector 25 is connected to the intake manifold 3 on the right side surface of the cylinder head 2, and an EGR gas inlet of a recirculation exhaust gas pipe 28 is connected and fixed to a front portion of the intake manifold 3 on the right side surface of the cylinder head 2. In addition, an EGR valve member 29 and an intake throttle member 26 are connected to the front and rear of the collector 25, respectively, and an EGR gas outlet of the recirculation exhaust gas pipe 28 is connected to the rear end of the EGR valve member 29.

[0023] The EGR cooler 27 is fixed to the front side of the cylinder head 2, and the cooling water and EGR gas flowing inside the cylinder head 2 flow in and out of the EGR cooler 27, where the EGR gas is cooled. EGR cooler connection seats 33, 34 for connecting the EGR cooler 27 are protrudingly provided at left and right positions on the front side of the cylinder head 2, and the EGR cooler 27 is connected to the connection seats 33, 34. In other words, the EGR cooler 27 is disposed above the flywheel housing 7 and in front of the cylinder head 2, with the rear end face of the EGR cooler 27 and the front side of the cylinder head 2 spaced apart.

[0024] The two-stage turbocharger 30 is disposed to the side (left side in the embodiment) of the exhaust manifold 4. The two-stage turbocharger 30 includes a high-pressure turbocharger 51 and a low-pressure turbocharger 52. The high-pressure turbocharger 51 includes a high-pressure turbine 53 incorporating a turbine wheel (not shown) and a high-pressure compressor 54 incorporating a blower wheel (not shown), while the low-pressure turbocharger 52 includes a low-pressure turbine 55 incorporating a turbine wheel (not shown) and a low-pressure compressor 56 incorporating a blower wheel (not shown).

[0025] An exhaust inlet 57 of the high-pressure turbine 53 is connected to the exhaust manifold 4, an exhaust inlet 60 of the low-pressure turbine 55 is connected to an exhaust outlet 58 of the high-pressure turbine 53 via a high-pressure exhaust gas pipe 59, and an exhaust gas intake end of an exhaust gas discharge pipe (not shown) is connected to an exhaust outlet 61 of the low-pressure turbine 55. Meanwhile, a fresh air supply side (fresh air outlet side) of an air cleaner (not shown) is connected to a fresh air intake port (fresh air inlet) 63 of the low-pressure compressor 56 via an air intake pipe 62, a fresh air intake port 66 of the high-pressure compressor 54 is connected to a fresh air supply port (fresh air outlet) 64 of the low-pressure compressor 56 via a low-pressure fresh air passage pipe 65, and a fresh air intake side of an intercooler (not shown) is connected to a fresh air supply port 67 of the high-pressure compressor 54 via a high-pressure fresh air passage pipe 71.

[0026] The high-pressure turbocharger 51 is connected to an exhaust outlet 58 of the exhaust manifold 4 and fixed to the left side of the exhaust manifold 4, while the low-pressure turbocharger 52 is connected to the high-pressure turbocharger 51 via a high-pressure exhaust gas pipe 59 and a low-pressure fresh air passage pipe 65 and fixed above the exhaust manifold 4. That is, the small-diameter high-pressure turbocharger 51 and the exhaust manifold 4 are arranged side by side on the left and right below the large-diameter low-pressure turbocharger 52, so that the two-stage turbocharger 30 is arranged to surround the left side and top of the exhaust manifold 4. That is, the exhaust manifold 4 and the two-stage turbocharger 30 are arranged in a rectangular shape when viewed from behind (when viewed from the front), and are compactly fixed to the left side of the cylinder head 2.

[0027] Next, the configuration of the cylinder head 2 will be described below with reference to Figs. 9 to 16. As shown in Figs. 9 to 16, the cylinder head 2 is formed with a plurality of intake passages 36 that introduce fresh air into a plurality of intake ports (not shown) and a plurality of exhaust passages 37 that guide exhaust gas from a plurality of exhaust ports. An intake manifold 3 that collects the plurality of intake passages 36 is formed integrally with the right side of the cylinder head 2. By forming the cylinder head 2 and the intake manifold 3 integrally, it is possible to improve the gas sealing performance from the intake manifold 3 to the intake passages 36 and to increase the rigidity of the cylinder head 2.

[0028] The exhaust manifold 4 is connected to the left side surface of the cylinder head 2, which is opposite to the right side surface on which the intake manifold 3 is formed, and the EGR cooler 27 is connected to the front side surface (the side surface on the flywheel housing 7 side) adjacent to the left and right side surfaces. Connection seats (EGR cooler connection seats) 33, 34 that connect to the EGR cooler 27 are formed protruding from the front side surface of the cylinder head 2, and EGR gas flow paths (EGR gas relay flow paths) 31, 32 and cooling water flow paths (cooling water relay flow paths) 38, 39 are formed within the connection seats 33, 34.

[0029] By configuring the EGR gas relay passages 31, 32 and the cooling water passages 38, 39 in the connecting pedestals 33, 34 to which the EGR cooler 27 is connected, it is not necessary to provide a cooling water pipe and an EGR gas pipe between the EGR cooler 27 and the cylinder head 2. Therefore, not only can the sealing performance at the connecting portion with the EGR cooler 27 be ensured without being affected by the expansion and contraction of the pipes due to the EGR gas or the cooling water, but the resistance (structural stability) to external variables such as heat and vibration is improved and a compact configuration can be achieved.

[0030] The cylinder head 2 has an upstream EGR gas relay passage 31 that communicates from the front part of the left side surface to the front side surface, and an EGR gas outlet 41 provided on the front end side of the exhaust manifold 4 communicates with the upstream EGR gas relay passage 31. The cylinder head 2 also has a downstream EGR gas relay passage 32 that communicates from the front part of the right side surface (in front of the intake manifold 3) to the front side surface, and an EGR gas inlet of the recirculation exhaust gas pipe 28 communicates with the downstream EGR gas relay passage 32. The cylinder head 2 has EGR cooler connection seats 33, 34 that protrude forward from both left and right edges of the front side surface (front left corner and front right corner of the cylinder head 2). The upstream EGR gas relay passage 31 is provided in the connection seat 33, and the downstream EGR gas relay passage 32 is provided in the connection seat 34.

[0031] The EGR device 24 is connected to the intake manifold 3 protruding from the right side of the cylinder head 2. The intake manifold 3 is provided near the rear (cooling fan 9 side) of the right side of the cylinder head 2 and is configured by protruding a lower portion of the right side of the cylinder head 2 to the right, with an intake inlet 40 at the center position between the front and rear. An intake outlet 83 of a collector 25 of the EGR device 24 is connected to the intake inlet 40 of the intake manifold 3 protruding from the right side of the cylinder head 2, and the EGR device 24 is fixed to the right side of the cylinder head 2.

[0032] A connecting base 34 that connects to the EGR cooler 27 protrudes forward from the front right side surface (flywheel housing 7 side) of the cylinder head 2, and an EGR gas outlet of the downstream EGR gas relay passage 32 opens on the right side surface of the connecting base 34. One end of the recirculation exhaust gas pipe 28 of the EGR device 24 is connected to the right side surface of the connecting base 34, so that the collector 25 of the EGR device 24 communicates with the downstream EGR gas relay passage 32 in the cylinder head 2 via the recirculation exhaust gas pipe 28 and the EGR valve member 29.

[0033] A cooling water drainage section (thermostat case) 35, which has an open upper surface and is connected to the cooling water outlet pipe (thermostat cover) 23, is provided at the rear of the right side surface of the cylinder head 2 (the cooling fan 9 side) and protrudes rearward, and a thermostat (not shown) is installed inside the cooling water drainage section 35. Since the cooling water drainage section 35 is offset at the rear of the right side surface of the cylinder head 2, the V-belt 10 wound around the fan pulley 9a to which the cooling fan 9 is fixed can be passed through the space below the cooling water drainage section 35, and the length of the diesel engine 1 in the front-rear direction can be shortened. The cooling water drainage section 35 also protrudes from the right side surface of the cylinder head 2, and the intake manifold 3 and the cooling water drainage section 35 are provided side by side in the front-rear direction on the right side surface of the cylinder head 2.

[0034] A connecting base 33 that connects to the EGR cooler 27 is provided protruding forward from the front of the left side surface of the cylinder head 2 (the flywheel housing 7 side), and an EGR gas inlet 96 of the upstream EGR gas relay passage 31 opens on the left side surface of the connecting base 33. That is, on the left side surface of the cylinder head 2, the EGR gas inlet 96 of the upstream EGR gas relay passage 31 and the exhaust outlets of the multiple exhaust passages 37 open side by side in the front-rear direction. On the other hand, on the right side surface of the exhaust manifold 4, which is the connecting surface with the left side surface of the cylinder head 2, an EGR gas outlet 41 that communicates with the upstream EGR gas relay passage 31 and an exhaust inlet 42 that communicates with the multiple exhaust passages 37 open side by side in the front-rear direction. Therefore, since the EGR inlet and the exhaust outlet are provided side by side on the same surface of the cylinder head 2, the connecting portion between the cylinder head 2 and the exhaust manifold 4 can easily ensure airtightness (gas sealing property) by sandwiching one gasket 45.

[0035] An exhaust collecting section 43 communicating with an EGR gas outlet 41 and an exhaust inlet 42 is disposed inside the exhaust manifold 4 with its longitudinal direction being the front-rear direction, and an exhaust outlet 44 communicating with the exhaust collecting section 43 is opened on the rear left side surface of the exhaust manifold 4. When exhaust gas from the exhaust passage 37 of the cylinder head 2 flows into the exhaust collecting section 43 through the exhaust inlet 42, part of the exhaust gas becomes EGR gas and flows from the EGR gas outlet 41 into the upstream EGR gas relay passage 31 of the cylinder head 2, and the remainder of the exhaust gas flows from the exhaust outlet 44 into the two-stage turbocharger 30.

[0036] A pair of left and right EGR cooler connection seats 33, 34 are provided on the front side of the cylinder head 2, one on the exhaust manifold 4 side and the other on the intake manifold 3 side. The EGR cooler connection seat 33 is provided with an upstream EGR gas relay passage 31 that connects the EGR gas passages of the exhaust manifold 4 and the EGR cooler 27. The EGR cooler connection seat 34 is provided with a downstream EGR gas relay passage 32 that connects the EGR gas passages of the EGR device 24 and the EGR cooler 27. The EGR cooler connection seat 33 is provided with a downstream cooling water passage 38 through which the cooling water is discharged from the EGR cooler 27. The EGR cooler connection seat 34 is provided with an upstream cooling water passage 39 that supplies the cooling water to the EGR device 24 and the EGR cooler 27.

[0037] By configuring the EGR cooler connection seats 33, 34 to protrude, piping for EGR gas that connects the exhaust manifold 4, the EGR cooler 27, and the EGR device 24 is not necessary, and the number of connection points in the EGR gas flow path is reduced. Therefore, in the diesel engine 1 that aims to reduce NOx by EGR gas, not only can EGR gas leakage be reduced, but deformation due to stress changes caused by expansion and contraction of the piping can be suppressed. In addition, since the EGR gas relay flow paths 31, 32 and the cooling water flow paths 38, 39 are configured in the EGR cooler connection seats 33, 34, the shapes of the flow paths 31, 32, 38, 39 configured in the cylinder head 2 are simplified, and the cylinder head 2 can be easily cast without using a complex core.

[0038] Since the EGR cooler connection seat 33 on the intake manifold 3 side and the EGR cooler connection seat 34 on the exhaust manifold 4 side are spaced apart, mutual influence due to thermal deformation of the connection seats 33, 34 can be suppressed. Therefore, not only can gas leakage and damage at the connection portion between the EGR cooler connection seats 33, 34 and the EGR cooler 27 be prevented, but also the rigidity balance of the cylinder head 2 can be maintained. In addition, since the volume of the front side surface of the cylinder head 2 can be reduced, the weight of the cylinder head 2 can be reduced. Furthermore, since the EGR cooler 27 can be arranged away from the front side surface of the cylinder head 2 and a configuration can be formed with spaces in front and behind the EGR cooler 27, cooling air can be circulated around the EGR cooler 27, and the cooling efficiency of the EGR cooler 27 can be improved.

[0039] The downstream cooling water passage 38 and the upstream EGR gas relay passage 31 are arranged above and below the EGR cooler connection seat 33, and the downstream EGR gas relay passage 32 and the upstream cooling water passage 39 are arranged above and below the EGR cooler connection seat 34. The cooling water inlet of the downstream cooling water passage 38 and the EGR gas inlet of the downstream EGR gas relay passage 32 are arranged 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 relay passage 32 are arranged at the same height.

[0040] By providing the EGR gas relay passages 31, 32 and the cooling water passages 38, 39 inside the EGR cooler connecting pedestals 33, 34 that are separately protruding, the influence of thermal deformation in both the EGR cooler connecting pedestals 33, 34 is mitigated. In addition, in the EGR cooler connecting pedestals 33, 34, the EGR gas flowing through the EGR gas relay passages 31, 32 is cooled by the cooling water flowing through the cooling water passages 38, 39, and the thermal deformation itself in the EGR cooler connecting pedestals 33, 34 is also suppressed. Furthermore, in each of the EGR cooler connecting pedestals 33, 34, the EGR gas relay passages 31, 32 and the cooling water passages 38, 39 are arranged at the vertical height positions interchanged. Therefore, the heat distribution in the EGR cooler connecting pedestals 33, 34 is vertically reversed, and the influence of thermal deformation in the height direction in the cylinder head 2 can be reduced.

[0041] The cylinder head 2 is provided with a spacer 46 that is connected to the bottom periphery of the head cover 18 by an outer peripheral wall that stands upright from the top periphery of the cylinder head 2. The spacer 46 has a number of openings 47 on the right side, through which a fuel pipe 48 that connects an injector (not shown) provided in the cylinder head 2 to the common rail 16 passes. By providing the spacer 46 integrally above the cylinder head 2, the rigidity of the cylinder head 2 is increased, which not only reduces distortion of the cylinder head 2 itself, but also allows each part connected to the cylinder head 2 to be supported with high rigidity.

[0042] Next, the configuration of the EGR device 24 will be described below with reference to Figures 9 to 11, 14, 15, and 17 to 19. As shown in Figures 9 to 11, 14, 15, and 17 to 19, the EGR device 24 includes a collector (main body case) 25 that mixes fresh air and EGR gas and supplies the mixture to the intake manifold 3, and the intake manifold 3 and an intake throttle member 26 for introducing fresh air are connected in communication with each other via the collector 25. The collector 25 is connected in communication with an EGR valve member 29 that is connected to the outlet side of a recirculation exhaust gas pipe 28.

[0043] In the collector 25, the fresh air flow direction and the EGR gas flow direction intersect at a right angle or at an obtuse angle, and the direction in which the mixed gas of EGR gas and fresh air is sucked into the intake manifold 3 intersects with both the fresh air flow direction and the EGR gas flow direction. A fresh air inlet 81 to which fresh air is supplied and an EGR gas inlet 82 to which EGR gas is supplied are opened separately on both front and rear side surfaces of the collector 25, and an intake outlet 83 connected to the intake manifold 3 is opened on the left side surface of the collector 25. The EGR gas inlet 82 and the intake outlet 83 are arranged at the same height position, and the fresh air inlet 81 and the EGR gas inlet 82 are arranged at different height positions.

[0044] In the collector 25, the fresh air introduced from the intake throttle member 26 to the fresh air inlet 81 flows in an L-shaped curve from the front-rear direction to the up-down direction, while the EGR gas introduced from the EGR valve member 29 to the EGR gas inlet 82 flows obliquely upward. Therefore, the EGR gas flows in such a way that it flows in the direction of the fresh air flow, and the EGR gas is easily mixed with the fresh air. In addition, the mixed gas of the fresh air and the EGR gas flows in an L-shaped curve from the up-down direction to the left-right direction, and flows into the intake manifold 3 from the intake outlet 83. The discharge direction of the mixed gas intersects not only the introduction direction of the fresh air and the introduction direction of the EGR gas, but also the flow direction of the fresh air and the EGR gas in the collector 25, so that the mixed distribution of the EGR gas into the fresh air can be made uniform.

[0045] As described above, in the collector 25, the EGR gas flow direction relative to the fresh air flow direction is at an angle of 90° or more, and the fresh air flow and the EGR gas flow cross, so that the mixed distribution of the EGR gas relative to the fresh air is uniform, and the uneven flow of the EGR gas in the intake manifold 3 can be suppressed. As a result, the EGR gas concentration of the intake air supplied to each of the multiple intake passages 36 in the cylinder head 2 is uniformized, and the variation in the combustion action of each cylinder in the diesel engine 1 can be suppressed. As a result, the generation of black smoke is suppressed, and the amount of NOx can be reduced while maintaining a good combustion state of the diesel engine 1. In other words, the purification (cleaning) of the exhaust gas by the recirculation of the EGR gas can be achieved without causing misfire in a specific cylinder.

[0046] Collector 25 is configured by connecting an upper case (first case) 84 having a fresh air inlet 81 and a lower case (second case) 85 having an EGR gas inlet 82 and an intake outlet 83. By configuring collector 25 so that it can be separated into upper and lower cases 84 and 85, it is possible to easily configure a mixing flow path in which the EGR gas flow and the fresh air flow intersect at an angle of 90° or more within collector 25. Therefore, not only can collector 25 be configured from a highly rigid casting, but by using an aluminum-based casting, it is also possible to reduce the weight.

[0047] A downstream EGR gas flow passage (first EGR gas flow passage) 86a, which is a part of an EGR gas flow passage 86 through which the EGR gas flows, and a mixing chamber 87 that mixes fresh air and EGR gas are provided in the upper case 84. An upstream EGR gas flow passage (second EGR gas flow passage) 86b that connects the downstream EGR gas flow passage 86a with the EGR gas inlet 82, and a mixed gas flow passage 88 that supplies the mixed gas of fresh air and EGR gas from the mixing chamber 87 to the intake manifold 3 are provided in the lower case 85.

[0048] Since the EGR gas inlet 82 is provided in the lower case 85, while the fresh air inlet 81 and the mixing chamber 87 are provided in the upper case 84, the fresh air flowing in from the fresh air inlet 81 and the EGR gas flowing in from the lower case 85 flow in a crossing manner in the mixing chamber 87, and the fresh air and the EGR gas are efficiently mixed. Furthermore, since the intake outlet 83 is provided in the lower case 85, the fresh air flowing in the upper case 84 tends to flow toward the lower case 85, and the EGR gas flowing toward the upper case 84 is uniformly mixed with the fresh air. Also, the EGR gas passage 86, the mixing chamber 87, and the mixed gas passage 88 can each be configured compactly within the collector 25, and the collector 25 can be made smaller in size.

[0049] In plan view, the downstream EGR gas passage 86a is offset from the side (left side) where the intake outlet 83 is provided with respect to the central axis of the mixing chamber 87 to the side (right side) opposite thereto, and the downstream EGR gas passage 86a and the upstream EGR gas passage 86b are connected to each other, forming the EGR gas passage 86 in a spiral shape. That is, the EGR gas passage 86 formed by the downstream EGR gas passage 86a and the upstream EGR gas passage 86b is curved so as to bulge toward the opposite side (right side) from the intake outlet 83 in plan view. The bottom of the upstream EGR gas passage 86b is formed by an inclined surface (inclined surface toward the rear and upper side) from the EGR gas inlet 82 toward the upper case 84.

[0050] Since the communicating portion of the mixing chamber 87 with the EGR gas passage 86 is on the opposite side to the intake outlet 83, the EGR gas flowing into the mixing chamber 87 is guided by the flow of fresh air and reaches the intake outlet 83, so that the EGR gas can be uniformly mixed with the fresh air. Also, since the EGR gas flowing from the EGR gas passage 86 into the mixing chamber 87 flows in a direction against the flow from the mixing chamber 87 toward the mixed gas passage 88, the fresh air and the EGR gas flow so as to collide with each other in the mixing chamber 87, so that the EGR gas is smoothly mixed with the fresh air.

[0051] Furthermore, since the EGR gas flows along the spiral EGR gas flow passage 86, the EGR gas flows into the mixing chamber 87 as a swirling flow that forms a clockwise vortex. Since the turbulent EGR gas flows in a direction opposite to the flow of the fresh air gas, the EGR gas flows into the mixing chamber 87 and is smoothly mixed with the fresh air flowing therein. Therefore, in the collector 25, the fresh air and the EGR gas can be efficiently mixed while being stirred before being sent to the intake manifold 3 (the EGR gas can be smoothly dispersed in the mixed gas), and the variation (unevenness) in the gas mixed state in the collector 25 can be more reliably suppressed. As a result, the mixed gas with little unevenness can be distributed to each cylinder of the diesel engine 1, and the variation in the amount of EGR gas between each cylinder can be suppressed, so that the generation of black smoke can be suppressed and the amount of NOx can be reduced while maintaining a good combustion state of the diesel engine 1. Furthermore, by forming the EGR gas passage 86 in a spiral shape, the EGR gas flowing into the mixing chamber 87 is given sufficient swirling ability, so that the length of the collector 25 in the front-rear direction can be made short.

[0052] A lower flange 84a of the upper case 84 and an upper flange 85a of the lower case 85 are bolted together to form the collector 25 having openings in three directions (front-rear and left directions) (fresh air inlet 81, EGR gas inlet 82, and intake outlet 83). The upper case 84 has a rear flange 84b, which opens into the fresh air inlet 81, and the fresh air outlet of the intake throttle member 26 is bolted to the rear flange 84b. The intake throttle member 26 adjusts the amount of fresh air supplied to the collector 25 by adjusting the opening of an intake valve (butterfly valve) 26a inside the intake throttle member 26.

[0053] The lower case 85 has a front flange 85b, which opens into the EGR gas inlet 82, and an EGR gas outlet of the EGR valve member 29 is bolted to the front flange 85b via a rectangular tubular intermediate flange 89. The EGR valve member 29 adjusts the amount of EGR gas supplied to the collector 25 by adjusting the opening of an EGR valve (not shown) inside the EGR valve member 29. A reed valve 90 inserted into the EGR gas inlet 82 is fixed inside the front flange 85b of the lower case 85. An intermediate flange (spacer) 89, which is bolted to the front flange 85b, covers the front of the reed valve 90, so that the collector 25 has the reed valve 90 installed on the EGR gas inlet 82 side of the EGR gas flow passage 86.

[0054] An EGR gas outlet 89a communicating with the EGR gas inlet 82 is opened in the rear surface of the intermediate flange 89, which is connected to the collector 25. Valve connecting seats 89b, 89c connecting to the EGR valve member 29 are protrudingly provided on the front surface of the intermediate flange 89, and the openings of the valve connecting seats 89b, 89c communicate with the EGR gas outlet of the EGR valve member 29. In the intermediate flange 89, the EGR gas is merged into the EGR gas inlets at the upper and lower valve connecting seats 89b, 89c, and flows from the EGR gas inlet 82 through a reed valve 90 into an EGR gas flow passage 86 in the collector 25.

[0055] The EGR valve member 29 has an EGR valve (not shown) provided in an EGR gas flow passage 29f provided in a valve body 29e, an actuator 29d for adjusting the opening degree of the EGR valve provided above the valve body 29e, and is connected to the front of the collector 25 via an intermediate flange 89 with the vertical direction as the longitudinal direction. The EGR valve member 29 has upper and lower outlet side flanges 29a, 29b provided on the rear surface of the lower valve body 29e, which are connected to valve connecting seats 89b, 89c of the intermediate flange 89, respectively. On the other hand, the front surface of the EGR valve member 29 is provided with an inlet side flange 29c provided with an EGR gas inlet that communicates with the EGR gas outlet of the recirculation exhaust gas pipe 28.

[0056] In the EGR valve member 29, when the EGR gas cooled by the EGR cooler 27 flows into the EGR gas inlet of the inlet side flange 29c through the downstream EGR gas relay passage 32 of the EGR cooler connection seat 34 and the recirculation exhaust gas pipe 28, the EGR gas is distributed upward and downward through the EGR gas passage 29f of the valve body 29e. Then, the EGR gas flowing upward and downward through the EGR gas passage 29f has its flow rate adjusted by the EGR valve, and flows into the relay flange 89 from the EGR gas outlets in the upper and lower outlet side flanges 29a, 29b.

[0057] The recirculation exhaust gas pipe 28 has a gas pipe section 28a bent into an L-shape in plan view, and a flat rib 28b protruding from the inner periphery of the outer wall of the gas pipe section 28a. The recirculation exhaust gas pipe 28 has an outlet side flange 28c at one end (rear end) of the gas pipe section 28a, which is connected to an inlet side flange 29c of the EGR valve member 29, and an inlet side flange 28d at the other end (left end) of the gas pipe section 28a, which is connected to the right side of the EGR cooler connection seat 34. The recirculation exhaust gas pipe 28 has a sensor mounting seat 28e for mounting an EGR gas temperature sensor on the upper surface of the bent portion of the gas pipe section 28a.

[0058] Since the length of the collector 25 of the EGR device 24 can be shortened, the distance between the EGR valve member 29 and the intake throttle member 26 can be shortened, and as a result, the front-rear length of the EGR device 24 can be shortened. In addition, since the EGR valve member 29 is configured with the actuator 29d provided at the top, the tops of the EGR valve member 29, the collector 25, and the intake throttle member 26 can be made to be at the same height, so not only can the vertical height of the EGR device 24 be reduced, but also the lateral width of the EGR device 24 can be narrowed. Therefore, since the EGR device 24 is configured compactly, it can be easily connected to the right side of the cylinder head 2 formed integrally with the intake manifold 3 by simply adjusting the recirculation exhaust gas pipe 28, and this contributes to the miniaturization of the diesel engine 1.

[0059] The recirculation exhaust gas pipe 28 is configured with a flat rib 28b connected to both ends of the gas pipe section 28a, so that the recirculation exhaust gas pipe 28 is configured with high rigidity and also increases the support strength of the front end side of the EGR device 24 to the cylinder head 2. In addition, the recirculation exhaust gas pipe 28 is configured with a flat rib 28b provided along the EGR gas flow path 28f in the gas pipe section 28a, so that the rib 28b increases the heat dissipation area in the gas pipe section 28a, thereby enhancing the cooling effect of the EGR gas flowing through the EGR gas flow path 28f. As a result, it contributes to cooling the mixed gas refined by the EGR device 24, and has the effect of easily maintaining the NOx amount reduction effect of the mixed gas in an appropriate state.

[0060] Next, the configuration of the EGR cooler 27 will be described below with reference to Figures 9 to 11, 13 to 16, and 20 to 21. As shown in Figures 9 to 11, 13 to 16, and 20 to 21, the EGR cooler 27 includes a heat exchanger 91 in which cooling water passages and EGR gas passages are alternately stacked, and a pair of left and right flanges 92, 93 provided at both left and right ends of one side of the heat exchanger 91. A cooling water outlet 94 and a cooling water inlet 95 are provided on the left and right flanges 92, 93, respectively, while an EGR gas inlet 96 and an EGR gas outlet 97 are provided on the left and right flanges 92, 93, respectively. The left and right flanges 92, 93 are connected to the front side of the cylinder head 2, and the EGR cooler 27 is fixed to the cylinder head 2.

[0061] By providing an opening for cooling water and an opening for EGR gas in each of the pair of left and right flanges 92, 93, not only can the flanges 92, 93 be made of a common member, but also the material costs for the flanges 92, 93 can be reduced. In addition, the flanges 92, 93 are formed by drilling through holes 94-97 for cooling water and EGR gas in a flat plate for connection to the cylinder head 2, so that the EGR cooler 27 can be easily manufactured. In addition, the connection portion between the flanges 92, 93 and the heat exchanger 91 can be minimized, so that the amount of heat transferred from the cylinder head 2 to the heat exchanger 91 can be reduced, and the cooling effect of the EGR gas in the heat exchanger 91 can be improved.

[0062] The EGR cooler 27 has flanges 92, 93 protruding from the rear surface of the heat exchanger 91, thereby forming a space between the heat exchanger 91 and the cylinder head 2. Therefore, a wide range of the front and rear surfaces of the heat exchanger 91 of the EGR cooler 27 is exposed to the outside air, and heat is also radiated from the heat exchanger 91, improving the cooling effect of the EGR gas in the EGR cooler 27. Therefore, compared to the case where the front surface of the rear surface of the heat exchanger 91 is attached, the number of layers in the heat exchanger 91 can be reduced, and the front-to-rear length of the EGR cooler 27 can be shortened, so that the diesel engine 1 can be made more compact.

[0063] A cooling water outlet 94 and an EGR gas inlet 96 are provided in the left flange portion 92, while a cooling water inlet 95 and an EGR gas outlet 97 are provided in the right flange portion 93. The cooling water outlet 94 and the EGR gas inlet 96 are provided above and below in the left flange portion 92, while the EGR gas outlet 97 and the cooling water inlet 95 are provided above and below in the right flange portion 93. The cooling water outlet 94 and the EGR gas outlet 97 are disposed at the same height, while the cooling water inlet 95 and the EGR gas inlet 96 are disposed at the same height.

[0064] At this time, left and right flange portions 92, 93 of the EGR cooler 27 are connected to EGR cooler connecting seats 33, 34 formed to protrude from the front side surface of the cylinder head 2. The upstream EGR gas relay passage 31 and the downstream cooling water relay passage 38 in the left EGR cooler connecting seat 33 communicate with the EGR gas inlet 96 and the cooling water outlet 94 in the left flange portion 92, respectively, and the downstream EGR gas relay passage 32 and the upstream cooling water relay passage 39 in the right EGR cooler connecting seat 34 communicate with the EGR gas outlet 97 and the cooling water inlet 95 in the right flange portion 93, respectively.

[0065] EGR gas relay passages 31, 32 and cooling water passages 38, 39 are formed in connection bases 33, 34 to which flange portions 92, 93 of the EGR cooler 27 are connected, and an EGR gas inlet 96 and outlet 97 and a cooling water outlet 94 and inlet 95 are connected to the flange portions 92, 93. Therefore, it is not necessary to provide a cooling water pipe and an EGR gas pipe between the EGR cooler 27 and the cylinder head 2. Therefore, it is possible to ensure sealing at the connection portion between the EGR cooler 27 and the cylinder head 2 without being affected by the expansion and contraction of the pipes due to the EGR gas or the cooling water, and the EGR cooler 27 has improved resistance to external variables such as heat and vibration, and can be installed compactly in the cylinder head 2.

[0066] Since the flange portion 92 is provided with a cooling water outlet 94 and an EGR gas inlet 96 at the top and bottom, while the flange portion 93 is provided with an EGR gas outlet 97 and a cooling water inlet 95 at the top and bottom, the flange portions 92 and 93, which have the same shape, are attached to the heat exchange portion 91 upside down. Therefore, the number of types of parts constituting the EGR cooler 27 can be reduced, the EGR cooler 27 can be easily assembled, and the parts cost can be reduced.

[0067] Furthermore, the flange portion 92 is provided with a cooling water outlet 94 and an EGR gas inlet 96 through which cooling water or EGR gas with a large amount of heat passes, while the flange portion 93 is provided with a cooling water inlet 95 and an EGR gas outlet 97 through which cooling water or EGR gas with a small amount of heat passes. Therefore, not only is distortion due to thermal deformation in each of the flange portions 92 and 93 suppressed, but the flange portions 92 and 93 are configured as separate bodies and are less affected by each other's thermal deformation, so that damage or failure of the EGR cooler 27 can be prevented.

[0068] In the EGR cooler 27, a cooling water outlet 94 and a cooling water inlet 95 are arranged diagonally in a rear view, and an EGR gas inlet 96 and an EGR gas outlet 97 are arranged diagonally. Since the EGR gas and the cooling water, which have different amounts of heat, are supplied or discharged from diagonal positions, thermal deformations at the connection portion between the EGR cooler 27 and the cylinder head 2 are mitigated, and bending or loosening of the connection portion can be suppressed. Therefore, not only can leakage of the EGR gas and the cooling water be prevented from occurring between the EGR cooler 27 and the cylinder head 2, but also a decrease in the connection strength can be prevented.

[0069] A plate-shaped gasket 98 is sandwiched between the cylinder head 2 and the flange portions 92, 93 so as to bridge the left and right flange portions 92, 93. O-rings 99, which are ring-shaped sealing members, are embedded in the cooling water inlet and the cooling water outlet of the cylinder head 2, which communicate with the cooling water outlet 94 and the cooling water inlet 95 of the flange portions 92, 93, respectively, and the O-rings 99 are covered by the flange portions 92, 93.

[0070] Since the flange parts 92, 93, which are separate bodies, are connected to the connecting seats 33, 34 of the cylinder head 2 via the gasket 98, tension acts on the gasket 98 due to thermal deformation at the connecting parts with the cylinder head 2. Therefore, the sealing property (sealing property) by the gasket 98 is improved at the connecting parts of the EGR gas inlet 96 and the EGR gas outlet 97, and leakage of EGR gas between the cylinder head 2 and the EGR cooler 27 can be prevented. In addition, since the O-ring 99 is embedded in the space formed by the cooling water inlet and cooling water outlet of the connecting seats 33, 34 of the cylinder head 2 and the rear end faces of the flange parts 92, 93, when the cooling water flows, the communicating parts of the connecting seats 33, 34 and the flange parts 92, 93 come into contact with the O-ring 99, and the sealing property (sealing property) of the connecting parts at the cooling water inlet / outlet 94, 95 can be ensured. Therefore, even if the EGR cooler 27 through which liquid and gas flow in and out is connected to the cylinder head 2, sealing properties for both the liquid and the gas can be ensured, and leakage of both the EGR gas and the cooling water can be prevented.

[0071] Through holes 100 for bolt fastening are drilled in the outer peripheral portions of the flange portions 92, 93. That is, the left flange portion 92 has five through holes 100 on the top, bottom, and left side, and the right flange portion 93 has five through holes 100 on the top, bottom, and right side. Therefore, the left flange portion 92 is provided with the through holes 100 on the upper side of the cooling water outlet 94, the lower side of the EGR gas inlet 96, and the left side between the cooling water outlet 94 and the EGR gas inlet 96, so that when the left flange portion 92 is fastened with a bolt to the connecting base 33 of the cylinder head 2, sealing properties are ensured at the cooling water outlet 94 and the EGR gas inlet 96. Similarly, the right flange portion 93 is provided with the through holes 100 on the lower side of the cooling water inlet 95, the upper side of the EGR gas outlet 97, and the right side between the cooling water inlet 95 and the EGR gas outlet 97, so that when the right flange portion 93 is fastened with a bolt to the connecting base 34 of the cylinder head 2, sealing properties are ensured at the cooling water inlet 95 and the EGR gas outlet 97.

[0072] The gasket 98 is formed by bonding together two plates 98a, 98b having through holes 101-103, with EGR gas passing through the through hole (EGR gas through hole) 101, cooling water passing through the through hole (cooling water through hole) 102, and a fastening bolt being inserted into the through hole (bolt through hole) 103. The gasket 98 has a shape in which the inner peripheral edge of the EGR gas through hole 101 is branched so as to be warped back in the front-rear direction, and the opening area of ​​the cooling water through hole 102 is configured to be larger than the opening areas of the cooling water inlets and outlets 94, 95.

[0073] In the gasket 98, the inner peripheral edge of the EGR gas through hole 101 in the front plate 98a is warped forward, while the inner peripheral edge of the EGR gas through hole 101 in the rear plate 98b is warped rearward, and by bonding the front plate 98a and the rear plate 98b together by welding, the inner peripheral edge of the EGR gas through hole 101 has a Y-shaped cross section. By making the inner peripheral edge of the EGR gas through hole 101 have a shape warped forward and backward, the front and rear surfaces of the inner peripheral edge of the EGR gas through hole 101 are brought into close contact with the end faces of the connecting pedestals 33, 34 and the flange portions 92, 93, respectively, and sufficient airtightness can be ensured.

[0074] The gasket 98 is configured so that the opening of the cooling water through hole 102 is wider than the cooling water inlets and outlets 94, 95, and an O-ring 99 is inserted into the cooling water through hole 102. In other words, the communication portion between the cooling water inlets and outlets 94, 95 of the flange portions 92, 93 and the cooling water relay flow paths 38, 39 in the connecting seats 33, 34 is sealed by the O-ring 99 fitted into the cooling water through hole 102 of the gasket 98.

[0075] In addition, the connecting seats 33, 34 of the cylinder head 2 open the cooling water inlets 94, 95 with a step, respectively, so that the openings are larger than the flow path diameters of the cooling water relay flow paths 38, 39 in the connecting seats 33, 34, and an O-ring 99 is fitted to the outer periphery of the cooling water relay flow paths 38, 39 with respect to the cooling water inlets 94, 95 of the connecting seats 33, 34. That is, the O-ring 99 is inserted into the gasket 98 and fitted to the step portions of the cooling water inlets 94, 95 in the connecting seats 33, 34, and is sandwiched between the connecting seats 33, 34 and the flange portions 92, 93. Therefore, as the cooling water passes inside the O-ring 99 made of an elastic material, the O-ring 99 deforms so as to expand outward, and is in close contact with the connecting seats 33, 34 and the flange portions 92, 93, ensuring sealing of the cooling water.

[0076] The ring-shaped O-ring 99 has an inner circumferential portion that bulges forward and backward, and is pressed by the cooling water passing through the inner circumferential portion of the O-ring 99, so that the front and rear edges of the inner circumferential portion deform to protrude forward and backward. This brings the inner circumferential portion of the O-ring 99 into close contact with the connecting seats 33, 34 and the flange portions 92, 93, improving the sealing performance for the cooling water at the connecting portion between the cylinder head 2 and the EGR cooler 27.

[0077] The ring-shaped O-ring 99 has an inner circumferential portion that bulges forward and backward and has a recess on its inner circumferential surface. That is, by forming the inner circumferential surface of the O-ring 99 into a Y-shaped cross section that is curved backward and forward, the O-ring 99 is pressed by the cooling water passing through the inner circumferential portion, causing the front and rear edges of the inner circumferential portion to protrude further forward and backward, thereby increasing the adhesion between the inner circumferential portion of the O-ring 99 and the connecting seats 33, 34 and the flange portions 92, 93. Therefore, the sealing performance of the cooling water at the connecting portion between the cylinder head 2 and the EGR cooler 27 can be improved.

[0078] Next, the configuration of the two-stage turbocharger 30 will be described below with reference to Fig. 22 to Fig. 27 etc. As shown in Fig. 22 to Fig. 27, the two-stage turbocharger 30 compresses fresh air flowing into the intake manifold 3 of the cylinder head 2 by using the fluid energy of exhaust gas discharged from the exhaust manifold 4. The two-stage turbocharger 30 is composed of a high-pressure turbocharger 51 connected to the exhaust manifold 4 and a low-pressure turbocharger 52 connected to the high-pressure turbocharger 51.

[0079] The high-pressure turbocharger 51 is disposed on the left side of the exhaust manifold 4, and the low-pressure turbocharger 52 is disposed above the exhaust manifold 4. That is, the small-capacity high-pressure turbocharger 51 is disposed facing the exhaust manifold 4, while the large-capacity low-pressure turbocharger 52 is disposed above the exhaust manifold 4 that is installed protruding leftward with respect to the cylinder head 2. Therefore, not only can the exhaust manifold 4 and the two-stage turbocharger 30 be compactly disposed in the space on the left side of the cylinder head 2, but also the top position of the two-stage turbocharger 30 can be lower than the top position of the diesel engine 1. Therefore, not only can the diesel engine 1 be made more compact, but the low-pressure turbocharger 52 can be disposed closer to the cylinder head 2, and the two-stage turbocharger 30 can be fixed with high rigidity.

[0080] The high-pressure turbocharger 51 includes a high-pressure turbine 53 communicating with the exhaust outlet 44 of the exhaust manifold 4, and a high-pressure compressor 54 that supplies compressed air to the intake manifold 3. The high-pressure compressor 54 communicates with a fresh air inlet 81 (see FIG. 17, etc.) of the intake throttle member 26 via an intercooler (not shown), thereby supplying compressed air to the intake manifold 3 via the EGR device 24. On the other hand, the low-pressure turbocharger 52 includes a low-pressure turbine 55 whose exhaust inlet communicates with the exhaust outlet of the high-pressure turbine 53 via an exhaust-side relay pipe, and a low-pressure compressor 56 whose fresh air outlet communicates with the fresh air inlet of the high-pressure compressor 54 via a fresh air-side relay pipe. The low-pressure compressor 56 is disposed above the high-pressure turbine 53, and the high-pressure compressor 54 is disposed on one side, front or rear, of the high-pressure turbine 53, while the low-pressure turbine 55 is disposed on the other side, front or rear, of the low-pressure compressor 56.

[0081] The exhaust manifold 4 has an exhaust outlet 44 for discharging exhaust gas opening toward one of the left and right sides. The high-pressure turbine 53 has an exhaust inlet 57 opening toward the exhaust manifold 4, while having an exhaust outlet 58 opening toward the front. The low-pressure turbine 55 has an exhaust inlet 60 opening toward the downward direction, while having an exhaust outlet 61 opening toward the front.

[0082] The exhaust outlet 44 of the exhaust manifold 4 and the exhaust inlet 57 of the high-pressure turbine 53, which face each other, are bolted together with a flange, and the high-pressure turbocharger 51 is fixed to the left side of the exhaust manifold 4. Then, the exhaust outlet 58 of the high-pressure turbine 53 is bolted to one end (rear end) of an L-shaped high-pressure exhaust gas pipe 59 (exhaust side relay pipe) with a flange, while the exhaust inlet 60 of the low-pressure turbine 55 is bolted to the other end (upper end) of the high-pressure exhaust gas pipe 59 with a flange, and the low-pressure turbocharger 52 is fixed above the high-pressure turbocharger 51.

[0083] The high-pressure turbine 53 is connected to the exhaust manifold 4 by flange connection to support the high-pressure turbocharger 51 with high rigidity, and then the low-pressure turbine 55 is connected by flange connection to the upper surface of the high-pressure exhaust gas pipe 59 connected to the front of the high-pressure turbocharger 51, so that the low-pressure turbocharger 52 can be supported from below by the high-pressure turbocharger 51. In addition, since the low-pressure turbocharger 52 is installed toward the upper side of the exhaust manifold 4, the center of gravity of the low-pressure turbocharger 52 is located above the connection position between the exhaust manifold 4 and the high-pressure turbocharger 51. Therefore, the two-stage turbocharger 30 can be supported around the diesel engine 1 with high rigidity and in a compact manner.

[0084] The high-pressure compressor 54 has a fresh air intake 63 (fresh air inlet) open toward the rear, and a fresh air supply port 64 (fresh air outlet) open toward the bottom. On the other hand, the low-pressure compressor 56 has a fresh air intake 66 (fresh air inlet) open toward the rear, and a fresh air supply port 67 (fresh air outlet) protruding from the left side and facing rearward. One end of a U-shaped low-pressure fresh air passage pipe 65 (fresh air side relay pipe) is fixed to the fresh air intake 63 (fresh air inlet) of the high-pressure compressor 54, and the other end of the low-pressure fresh air passage pipe 65 is connected to the fresh air supply port 67 (fresh air outlet) of the low-pressure compressor 56.

[0085] The high-pressure compressor 54 and the low-pressure compressor 56 are connected by a U-shaped low-pressure fresh air passage pipe 65 at the rear, and the front part of the low-pressure turbocharger 52 can be fixed to the high-pressure turbocharger 51 supported with high rigidity by the exhaust manifold 4. The low-pressure compressor 56 has a fresh air intake port 66 and a fresh air supply port 67 extending in the same direction (rearward) and is configured to be easily connected to the intake pipe 62 and the low-pressure fresh air passage pipe 65 that communicate with an air cleaner (not shown), respectively, thereby improving the ease of assembly.

[0086] The low-pressure fresh air passage pipe 65 is composed of a metal pipe 65a, one end of which is bolted to the fresh air intake port 66 of the high-pressure compressor 54 by flange connection, and a resin pipe 65b that communicates the other end of the metal pipe 65a with the fresh air supply port 67 of the low-pressure compressor 56. As a result, the low-pressure fresh air passage pipe 65 is configured such that the metal pipe 65a is fixed to the high-pressure compressor 54 with high rigidity, while the resin pipe 65b allows communication between the low-pressure compressor 56 and the metal pipe 65a while mitigating assembly errors between them.

[0087] Since the fresh air supply port 67 of the low-pressure compressor 56 is configured to protrude leftward from the left side surface of the low-pressure compressor 56 and then point toward the upper rear side, the curvature of the bent portion of the low-pressure fresh air passage pipe 65 (metal pipe 65a) is made large. Therefore, the generation of turbulence in the low-pressure fresh air passage pipe 65 is suppressed, and the compressed air discharged from the low-pressure compressor 56 is smoothly supplied to the high-pressure compressor 54.

[0088] A blow-by gas reduction device 19 that takes in blow-by gas is installed on the cylinder head 2. The blow-by gas reduction device 19 is placed and fixed on the upper surface of a head cover 18 that covers the upper surface of the cylinder head 2. A blow-by gas outlet 70 provided at the rear of the blow-by gas reduction device 19 is connected to an air intake pipe 62 that is connected to a fresh air intake port 66 (fresh air inlet) of the low-pressure compressor 56 via a return hose 68. The air intake pipe 62 is also arranged between a low-pressure fresh air passage pipe 65 (fresh air side relay pipe) and the cylinder head 2.

[0089] Since the intake pipe 62 is connected to the rear of the low-pressure turbocharger 52, which is an upper component of the two-stage turbocharger 30, and is disposed close to the cylinder head 2, the distance between the blow-by gas return device 19 disposed above the cylinder head 2 and the intake pipe 62 can be shortened. Therefore, the return hose 68 can be shortened, and freezing inside the return hose 68 in a low-temperature environment can be prevented. Since the intake pipe 62 is disposed in the space surrounded by the low-pressure fresh air passage pipe 65 and the cylinder head 2, damage due to external force at the connection part with the resin pipe connected to the air cleaner (not shown) can be prevented.

[0090] The high-pressure turbocharger 51 has a fresh air supply port 64 that opens downward and protrudes from the lower surface of the high-pressure compressor 54 on the cylinder head 2 side. The high-pressure compressor 54 is connected to a high-pressure fresh air passage pipe 71 that communicates with an intercooler (not shown), and supplies compressed air to the intercooler through the high-pressure fresh air passage pipe 71. A cooling water inlet pipe 22 that opens toward the left side is provided below the high-pressure compressor 54. By piping the high-pressure fresh air passage pipe 71 to the rear left side surface of the cylinder block 6 together with a cooling water pipe that communicates with a radiator (not shown), it can be connected to the cooling water inlet pipe 22 and the fresh air supply port 64 of the high-pressure compressor 54. Therefore, the piping arrangement of the cooling water pipe and the high-pressure fresh air passage pipe 71 can be consolidated, so that not only can the piping structure on the machine side on which the diesel engine 1 is mounted be simplified, but also the assembly and maintenance work can be easily performed.

[0091] In addition, the diesel engine 1 has the cooling water outlet pipe 23, the air intake pipe 62, and the intake throttle member 26 arranged above the cylinder head 2 and on the cooling fan 9 side. Therefore, when a radiator (not shown), an air cleaner (not shown), and an intercooler (not shown) that use the cooling air from the cooling fan 9 are arranged behind the cooling fan 9 on the main machine on which the diesel engine 1 is mounted, not only can the cooling water piping connected to the radiator and the fresh air piping communicating with the air cleaner and the intercooler be shortened, but the piping connection work can be performed all at once. This not only facilitates the assembly work and maintenance work on the main machine side, but also allows the various parts to be connected to the diesel engine 1 to be efficiently arranged on the main machine side.

[0092] At the exhaust outlet 58 of the high-pressure turbine 53, there are provided a turbine exhaust hole 58a for discharging the exhaust gas that rotates a turbine wheel (not shown), a bypass hole 58b that connects the exhaust inlet 57 and the exhaust outlet 58, and a wastegate valve 69 for opening and closing the bypass hole 58b. By providing the turbine exhaust hole 58a and the bypass hole 58b in parallel at the exhaust outlet 58 of the high-pressure turbine 53, it is possible to set whether or not the compression operation by the high-pressure turbocharger 51 is performed according to the rotation speed of the diesel engine 1. Therefore, the two-stage turbocharger 30 efficiently uses exhaust energy to stabilize the amount of fresh air supplied to the combustion chamber, and the amount of black smoke emission can be reduced while increasing the engine output.

[0093] In addition, since the bypass path from the exhaust manifold 4 to the low-pressure turbine 55 is formed by opening the bypass hole 58b of the high-pressure turbine 53, it is necessary to lay only the high-pressure exhaust gas pipe 59 that communicates between the high-pressure turbine 53 and the low-pressure turbine 55, and no bypass piping is required to communicate between the exhaust manifold 4 and the low-pressure turbine 55. Therefore, not only is the piping structure in the two-stage turbocharger 30 simplified, but the space around the two-stage turbocharger 30 can be expanded, and for example, a hydraulic pump (not shown) for a work machine can be arranged vertically in parallel with the engine starter 20 below the front side of the two-stage turbocharger 30.

[0094] In the high-pressure turbocharger 51, a high-pressure hydraulic oil supply pipe 73 and a high-pressure hydraulic oil return pipe 74 are connected to the top and bottom of a center housing 72, which is the connecting portion between the high-pressure turbine 53 and the high-pressure compressor 54. Similarly, in the low-pressure turbocharger 52, a low-pressure hydraulic oil supply pipe 76 and a low-pressure hydraulic oil return pipe 77 are connected to the top and bottom of a center housing 75, which is the connecting portion between the low-pressure turbine 55 and the low-pressure compressor 56.

[0095] The high-pressure hydraulic oil supply pipe 73 has a lower end connected to a connecting member 78 installed on the left side surface of the cylinder block 6, and an upper end connected to the upper surface of the center housing 72 of the high-pressure turbocharger 51. A connecting joint 79 that communicates the upper end of the high-pressure hydraulic oil supply pipe 73 with the lower end of the low-pressure hydraulic oil supply pipe 76 is installed on the upper surface of the center housing 72 of the high-pressure turbocharger 51. The upper end of the low-pressure hydraulic oil supply pipe 76 is connected to the upper surface of the center housing 75 of the low-pressure turbocharger 52. As a result, the hydraulic oil flowing through the oil passage in the cylinder block 6 is supplied to the center housing 72 of the high-pressure turbocharger 51 through the high-pressure hydraulic oil supply pipe 73, and is also supplied to the center housing 75 of the low-pressure turbocharger 52 through the high-pressure hydraulic oil supply pipe 73 and the low-pressure hydraulic oil supply pipe 76.

[0096] The high pressure hydraulic oil supply pipe 73 passes between the cylinder head 2 and the cylinder block 6 and the high pressure turbocharger 51, and is arranged to bypass the rear of the exhaust outlet 44 of the exhaust manifold 4. The low pressure hydraulic oil supply pipe 76 is arranged in an L-shape so as to run along the upper surface of the high pressure turbocharger 51 and the center housing 75 of the low pressure turbocharger 52. In this way, by shortening the hydraulic oil supply pipes 73, 76 and piping them so as to be surrounded by the two-stage turbocharger 30, which is a highly rigid component, the hydraulic oil can be efficiently supplied to the two-stage turbocharger 30, and at the same time, damage to the hydraulic oil supply pipes 73, 76 due to external forces can be prevented.

[0097] The high pressure hydraulic oil return pipe 74 has one end (lower end) connected to the tip (left tip) of a connecting joint 80 installed on the left side of the cylinder block 6, while the other end (upper end) is connected to the lower surface of the center housing 72 of the high pressure supercharger 51. In addition, the low pressure hydraulic oil return pipe 77 has one end (lower end) connected to the branched upper end of the connecting joint 80, while the other end (upper end) is connected to the lower surface of the center housing 75 of the low pressure supercharger 52. Therefore, the hydraulic oil flowing through each of the high pressure supercharger 51 and the low pressure supercharger 52 is joined at the connecting joint 80 from the low pressure hydraulic oil return pipes 74, 77 below the center housings 72, 75 and returned to the oil passage in the cylinder block 6.

[0098] The high pressure hydraulic oil return pipe 74 is arranged to bypass the rear of the exhaust outlet 44 of the exhaust manifold 4. The low pressure hydraulic oil return pipe 77 passes between the cylinder head 2 and the cylinder block 6 and the high pressure turbocharger 51, and is arranged to bypass the front of the exhaust outlet 44 of the exhaust manifold 4. In this way, by shortening the hydraulic oil return pipes 74, 77 and piping them so as to be surrounded by the two-stage turbocharger 30, which is a highly rigid component, hydraulic oil can be efficiently supplied to the two-stage turbocharger 30, and at the same time, damage to the hydraulic oil return pipes 74, 77 due to external forces can be prevented.

[0099] Next, the configurations of the cooling water pump 21 and the cooling water inlet pipe 22 will be described below with reference to Figures 28 and 29. As shown in Figures 28 and 29, a cooling water pump mounting portion 319 to which the cooling water pump 21 (see Figure 2, etc.) is attached and an inlet pipe mounting seat 320 to which the cooling water inlet pipe 22 (see Figure 3, etc.) is attached are protrudingly provided on a portion of the left side surface of the cylinder block 6 near the rear side surface. The cooling water pump mounting portion 319 and the inlet pipe mounting seat 320 are integrally formed with the cylinder block 6. A portion of the inlet pipe mounting seat 320 on the rear side surface side is connected to the cooling water pump mounting portion 319. The cooling water pump mounting portion 319 and the inlet pipe mounting seat 320 are protrudingly provided in a direction away from the crankshaft 5, and can improve the rigidity, strength, and cooling efficiency of the cylinder block 6.

[0100] A cooling water pump 21 for circulating cooling water is bolted to the rear side surface 312 of the cylinder block 6 and a cooling water pump attachment portion 319. The cooling water pump 21 is roughly composed of a base plate portion 331, a cover plate portion 332, and a pump pulley 333.

[0101] The base plate portion 331 and the cover plate portion 332 are fixed to each other in close contact with each other at their peripheral portions by inserting and fastening cover bolts 347 from the cover plate portion 332 side into five through bolt holes provided on the peripheral portion of the base plate portion 331 and into the through holes in the cover plate portion 332 that correspond to the through bolt holes.

[0102] The cooling water pump 21 is fastened to the cylinder block 6 by bolts 348 inserted into through holes provided at nine locations on the periphery of the base plate portion 331 and the cover plate portion 332. Fastening the mounting bolts 348 causes the peripheries of the base plate portion 331 and the cover plate portion 332 to be tightly fixed to each other, and also causes the periphery of the cooling water passage outlet 327 of the cylinder block 6 to be tightly fixed to the periphery of the pump suction port 334 of the cooling water pump 21, and further causes the periphery of the cooling water inlet 328 of the cylinder block 6 to be tightly fixed to the periphery of the pump discharge port 335 of the cooling water pump 21. In the arrangement of the bolts 347, 348 along the periphery of the cooling water pump 21, one or two mounting bolts 348 are arranged between adjacent cover bolts 347, 347.

[0103] Since the base plate portion 331 and the cover plate portion 332 are connected by the cover bolt 347, the cooling water pump 21 can be distributed as a single component and the installation work when mounting the cooling water pump 21 to the cylinder block 6 by the mounting bolt 348 is facilitated.

[0104] The base plate portion 331 is provided with a pump suction port 334 connected to a cooling water passage outlet 327 opened in a portion toward the left side of the rear side of the cylinder block 6, including the portion of the cooling water pump mounting portion 319, and a pump discharge port 335 connected to a cooling water inlet 328 opened in a portion toward the left side of the rear side of the cylinder block 6.

[0105] The base plate portion 331 and the cover plate portion 332 are brought into close contact with each other at their peripheral edges to form an in-pump cooling water passage 336 that connects a pump suction port 334 and a pump discharge port 335. An annular seal member that surrounds the pump suction port 334, the pump discharge port 335, and the in-pump cooling water passage 336 is disposed at the contact portion between the base plate portion 331 and the cover plate portion 332. The cover plate portion 332 rotatably supports a pump shaft 337 to one end of which an impeller is fixed. A pump pulley 333 is fixed to the other end of the pump shaft 337.

[0106] A cooling water passage inlet 329 opens into the left side surface of the cylinder block 6. The cooling water passage inlet 329 opens into an inlet pipe mounting seat 320 protruding from the left side surface. A substantially L-shaped intra-block cooling water passage 338 (cooling water passage) is formed inside the cylinder block 6, connecting the cooling water passage inlet 329 opening into the left side surface and the cooling water passage outlet 327 opening into the rear side surface.

[0107] A pair of bolt holes are formed in the inlet pipe mounting seat 320 on either side of a cooling water passage inlet 329, and a cooling water inlet pipe 22 (cooling water inlet member) having a cooling water inlet 339 is detachably bolted to the inlet pipe mounting seat 320. A pipe leading to a cooling water outlet of the radiator is connected to the cooling water inlet pipe 22. Cooling water from the radiator is taken into the engine 1 through the cooling water inlet pipe 22, passes through an intra-block cooling water passage 338 and the cooling water pump 21, and is introduced into the cylinder block 6 from a cooling water inlet port 328.

[0108] In the engine 1 of this embodiment, the cooling water inlet pipe 22 having the cooling water inlet 339 is detachably attached to the cooling water passage inlet 329 connected to the pump suction port 334 of the cooling water pump 21, so the position of the cooling water inlet 339 can be changed simply by changing the shape, etc. of the cooling water inlet pipe 22. This allows the position of the cooling water inlet 339 of the cooling water pump 21 to be changed easily and without incurring major design changes or increases in manufacturing costs.

[0109] In addition, a cooling water passage outlet 327 that supplies the cooling water from the radiator to the cooling water pump 21 and a cooling water inlet 328 that introduces the cooling water from the cooling water pump 21 into the cylinder block 6 are arranged on the left and right sides of the cylinder block 6. Furthermore, an in-pump cooling water passage 336 that connects the cooling water passage outlet 327 and the cooling water inlet 328 is arranged from a portion close to the left side surface of the cylinder block 6 to a portion close to the right side surface. With this configuration, the cooling water passing through the in-pump cooling water passage 336 is cooled by cooling air from the cooling fan 9 (see FIG. 2) while moving from the cooling water passage outlet 327 to the cooling water inlet 328. Therefore, the cooling water can be cooled in the cooling water pump 21 before being introduced into the cylinder block 6 from the cooling water inlet 328, and the cooling efficiency of the engine 1 can be improved.

[0110] The configuration of each part in the present invention is not limited to the illustrated embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0111] <Notes on the invention> An engine device according to one embodiment includes an exhaust manifold and an intake manifold arranged in a cylinder head, and a turbocharger that compresses fresh air flowing into the intake manifold using fluid energy of exhaust gas discharged from the exhaust manifold, the turbocharger being configured as a two-stage turbocharger consisting of a high-pressure turbocharger connected to the exhaust manifold and a low-pressure turbocharger connected to the high-pressure turbocharger, and the low-pressure compressor of the low-pressure turbocharger has a fresh air inlet provided closer to the cylinder head than the fresh air outlet.

[0112] In the above engine apparatus, the fresh air outlet may be provided so as to protrude from one of the left and right sides of the low-pressure compressor.

[0113] In the above engine apparatus, the low-pressure compressor may have the fresh air inlet and the fresh air outlet facing one side, either forward or backward.

[0114] In the above engine system, a fresh air inlet of a high-pressure compressor of the high-pressure supercharger may be oriented toward the one of the front and rear sides.

[0115] In the above engine apparatus, the high-pressure supercharger may be disposed on one of the left and right sides of the exhaust manifold, and the low-pressure supercharger may be disposed above the exhaust manifold.

[0116] According to the above configuration, the fresh air inlet of the low-pressure supercharger is disposed in the space surrounded by the fresh air outlet of the low-pressure supercharger and the cylinder head, which not only contributes to the miniaturization of the engine device but also prevents damage due to external forces at the connection portion with the plastic pipe that connects to the air cleaner (not shown).

[0117] Moreover, an engine device according to one aspect of the present application is an engine device including an exhaust manifold and an intake manifold arranged in a cylinder head, and a supercharger that compresses fresh air flowing into the intake manifold by fluid energy of exhaust gas discharged from the exhaust manifold, the supercharger being configured as a two-stage supercharger having a high-pressure supercharger connected to the exhaust manifold and a low-pressure supercharger connected to the high-pressure supercharger, and the center of the low-pressure supercharger is arranged closer to the cylinder head than the center of the high-pressure supercharger in a plan view.

[0118] An engine apparatus according to an aspect of the present application is an engine apparatus including a turbocharger that compresses fresh air flowing into an intake manifold by fluid energy of exhaust gas discharged from an exhaust manifold. The turbocharger is configured as a two-stage turbocharger including a high-pressure turbocharger connected to the exhaust manifold and a low-pressure turbocharger connected to the high-pressure turbocharger. An exhaust gas pipe connecting an exhaust outlet of the high-pressure turbocharger and an exhaust inlet of the low-pressure turbocharger is connected to the high-pressure turbocharger along one direction in a plan view and is connected to the low-pressure turbocharger along a vertical direction.

[0119] An engine apparatus according to one aspect of the present application is an engine apparatus including a turbocharger that compresses fresh air flowing into an intake manifold by using fluid energy of exhaust gas discharged from an exhaust manifold. The turbocharger is configured as a two-stage turbocharger including a high-pressure turbocharger connected to the exhaust manifold and a low-pressure turbocharger connected to the high-pressure turbocharger. An exhaust outlet of the high-pressure turbocharger and an exhaust inlet of the low-pressure turbocharger are disposed at different positions in the crankshaft direction. [Explanation of symbols]

[0120] 1 Engine 2. Cylinder head 3. Intake manifold 4 Exhaust manifold 5 Crankshaft 6 Cylinder block 7 Flywheel housing 8 Flywheel 9 Cooling Fan 51 High pressure turbocharger 52 Low pressure turbocharger 53 High Pressure Turbine 54 High Pressure Compressor 55 Low Pressure Turbine 56 Low Pressure Compressor 57 Exhaust inlet 58 Exhaust outlet 58a Turbine exhaust hole 58b Bypass hole 59 High pressure exhaust gas pipe 60 Exhaust inlet 61 Exhaust outlet 62 Air supply pipe 63 Fresh air intake 64 Fresh air supply port 65 Low pressure fresh air passage pipe 65a metal tube 65b Resin pipe 66 Fresh air intake 67 Fresh air supply port 68 Reduction Hose 69 Wastegate valve 70 Blow-by gas outlet 71 High pressure fresh air passage pipe 72 Center Housing 73 High pressure hydraulic oil supply pipe 74 High pressure hydraulic oil return pipe 75 Center Housing 76 Low pressure hydraulic oil supply pipe 77 Low pressure hydraulic oil return pipe 78 Connecting member 79 Connecting joints 80 Connecting joint

Claims

1. An engine device including an exhaust manifold and a turbocharger, the turbocharger is configured as a two-stage turbocharger including a high-pressure turbocharger connected to the exhaust manifold and a low-pressure turbocharger connected to the high-pressure turbocharger, The low pressure turbocharger is located above the high pressure turbocharger. Engine equipment.

2. An exhaust inlet of the low-pressure turbocharger is disposed closer to the flywheel in the crankshaft direction than an exhaust outlet of the high-pressure turbocharger. The engine apparatus according to claim 1 .

3. An exhaust gas pipe connecting an exhaust outlet of the high-pressure turbocharger and an exhaust inlet of the low-pressure turbocharger is connected to the high-pressure turbocharger along one direction in a plan view and is connected to the low-pressure turbocharger along a vertical direction.

3. An engine device according to claim 1 or 2.

4. The center of the low-pressure supercharger is disposed closer to the cylinder head than the center of the high-pressure supercharger in a plan view. The engine device according to any one of claims 1 to 3.

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