Engine device

Abstract

The present invention relates to an engine device provided with a cylinder head in which an intake flow path for introducing fresh air into an intake port and an exhaust flow path for discharging exhaust gas from an exhaust port are formed, the engine device being characterized in that cooling water flow paths are provided on one of the left and right side walls and one of the front and rear side walls of the cylinder head.

Description

[0001] This application is a divisional application of the invention application with application number 201780078943.8, application date November 9, 2017, and invention title "Engine Device". Technical Field

[0002] This invention relates to engine devices. Background Technology

[0003] Conventionally, cylinder heads with intake and exhaust ports are constructed such that intake manifolds and exhaust manifolds are connected to their left and right sides (see Patent Document 1). Furthermore, as a countermeasure against exhaust gases from diesel engines, etc., the following technology is known: an EGR (Exhaust Gas Recirculation) device is installed that allows a portion of the exhaust gas to flow back to the intake side, thereby suppressing the combustion temperature and reducing the amount of NOx (nitrogen oxides) in the exhaust gas (see Patent Documents 2-4).

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 3876139

[0006] Patent Document 2: Japanese Patent No. 3852255

[0007] Patent Document 3: Japanese Patent Application Publication No. 2002-235607

[0008] Patent Document 4: Japanese Patent No. 5387612 Summary of the Invention

[0009] However, the space available for diesel engines varies depending on the type of vehicle they are used in (construction machinery, agricultural machinery, etc.). In recent years, however, the demand for lightweight and compact designs has often limited the available space. Therefore, it is necessary to achieve a compact layout of the diesel engine's components. Furthermore, in addition to the limited space, the cylinder head requires a high-rigidity structure because it connects and supports components such as the EGR unit and turbocharger to it.

[0010] Furthermore, the cylinder head structure of the engine disclosed in Patent Documents 2 and 3 is such that an EGR gas flow path is formed within the cylinder head. However, when an EGR gas flow path is formed in the cylinder head, the following problems arise: it becomes a complex structure as in Patent Document 2, the freedom of the path layout is reduced, and the processing time and processing cost increase.

[0011] Furthermore, when the EGR cooler is connected via piping, the EGR gas temperature rises due to diesel engine heat, causing the EGR gas volume to increase. This makes it difficult to maintain a sufficient EGR gas supply, hindering NOx reduction in exhaust gases. On the other hand, excessive cooling of the EGR gas due to exposure of the EGR piping to cooling air from the cooling fan can also negatively impact combustion within the cylinders. Therefore, to supply EGR gas at an appropriate temperature, it is necessary to study the suitable configuration and cooling structure of various diesel engine components. Additionally, uneven mixing of EGR gas and fresh air can lead to deviations in the amount of EGR gas supplied to multiple cylinders, potentially affecting combustion and NOx reduction in each cylinder and reducing diesel engine operating efficiency.

[0012] The technical challenge of this invention is to provide an improved engine device by studying the current situation as described above.

[0013] This invention relates to an engine device comprising: a cylinder head having multiple intake air passages for introducing fresh air into multiple intake ports and multiple exhaust air passages for discharging exhaust gas from multiple exhaust ports; an exhaust manifold communicating with the exhaust air passages; and an EGR cooler for cooling EGR gas, which is part of the exhaust gas from the exhaust manifold. The intake manifold, where the multiple intake air passages converge, is integrally formed with one of the left or right sides of the cylinder head. The EGR cooler is connected to one of the front or rear sides of the cylinder head. Furthermore, an EGR gas passage and a cooling water passage communicating with the EGR cooler are provided at the portion of the cylinder head connected to the EGR cooler.

[0014] In the aforementioned engine device, the cylinder head may be configured such that an outer peripheral wall is erected, which surrounds the region connected to the exhaust manifold starting from the boundary relative to the intake manifold, and L-shaped cooling water flow paths are provided on the left and right side walls and the front and rear side walls of the outer peripheral wall.

[0015] In the aforementioned engine device, the cylinder head can be configured such that it is fastened to the cylinder block by a plurality of bolts inserted through the left and right side walls and the front and rear side walls of the outer peripheral wall.

[0016] In the aforementioned engine device, the cylinder head may be configured such that it has a cooling water drain section on the front and rear sides and at a position adjacent to the end of the intake manifold, which communicates with the cooling water flow path provided on the outer peripheral wall.

[0017] In the aforementioned engine device, it can be configured such that a pair of connecting bases connected to the EGR cooler are provided on one of the front and rear sides of the cylinder head, and the pair of connecting bases respectively have an EGR gas flow path and a cooling water flow path arranged vertically and passing through each other.

[0018] In the aforementioned engine device, one side of the connecting base may be configured to have an EGR gas flow path disposed above the cooling water flow path, and the other side of the connecting base may be configured to have an EGR gas flow path disposed below the cooling water flow path.

[0019] Invention Effects

[0020] According to the present invention, the cylinder head and intake manifold are integrated, thereby improving the gas sealing performance of the intake manifold relative to the intake airflow path and increasing the rigidity of the cylinder head. Furthermore, by connecting auxiliary components such as the EGR device and turbocharger to the cylinder head, not only is their support rigidity improved, but the number of components in the intake-side sealing parts of the cylinder head is also reduced.

[0021] According to this invention, the EGR cooler is directly connected to the cylinder head, eliminating the need for cooling water piping and EGR gas piping between the EGR cooler and the cylinder head. Therefore, it is unaffected by piping expansion and contraction caused by EGR gas and cooling water, ensuring not only the sealing of the connection to the EGR cooler but also improving resistance to external factors such as heat and vibration (structural stability), and allowing for a compact design. Furthermore, since the EGR gas flow path and cooling water flow path are formed in the connecting base, the shape of each flow path formed within the cylinder head is simplified, allowing for easy casting of the cylinder head without the need for complex cores.

[0022] According to this invention, since a cooling water flow path is formed along the outer peripheral wall of the cylinder head, the sidewall with the cooling water flow path is constructed like a beam, thereby improving the rigidity of the cylinder head against warping. Therefore, when the cylinder head is manufactured by casting, warping during the subsequent separation of the casting is improved. Furthermore, the cooling water flows through the cooling water flow path on the outer peripheral wall, thereby suppressing bolt elongation (thermal deformation) caused by combustion heat within the cylinder, enabling the cylinder head to be connected to the cylinder block with high rigidity without compromising the cylinder's sealing performance.

[0023] According to this invention, an EGR gas flow path and a cooling water flow path are provided within a separately protruding connecting base, thereby mitigating the effects of thermal deformation on both sides of the connecting base. Furthermore, within the connecting base, the EGR gas flowing in the EGR gas flow path is cooled by cooling water flowing in the cooling water flow path, thus suppressing the thermal deformation of the connecting base itself. Moreover, since the EGR gas flow path and the cooling water flow path are arranged in a manner that alternates their respective vertical height positions on the connecting base, the heat distribution in the connecting base is in opposite vertical directions, which can reduce the effects of thermal deformation in the height direction of the cylinder head. Attached Figure Description

[0024] Figure 1 This is the front view of the engine.

[0025] Figure 2 This is a rear view of the engine.

[0026] Figure 3 This is a left view of the engine.

[0027] Figure 4 This is a right view of the engine.

[0028] Figure 5 This is a top view of the engine.

[0029] Figure 6 This is a bottom view of the engine.

[0030] Figure 7 This is a three-dimensional view of the engine viewed from a diagonal front.

[0031] Figure 8 This is a three-dimensional view of the engine viewed from a slightly rearward angle.

[0032] Figure 9 This is a magnified 3D view of the cylinder head from the intake manifold side.

[0033] Figure 10 This is an exploded 3D view of the cylinder head from the exhaust manifold side.

[0034] Figure 11 This is an exploded 3D view of the cylinder head from the intake manifold side.

[0035] Figure 12 This is a top view of the cylinder head.

[0036] Figure 13 This is the front view of the cylinder head.

[0037] Figure 14 This is a sectional perspective view of the cylinder head and EGR device.

[0038] Figure 15It is a three-dimensional cross-sectional view of the cylinder head and exhaust manifold.

[0039] Figure 16 This is a sectional perspective view of the part of the cylinder head that connects to the EGR cooler.

[0040] Figure 17 This is a top view of the cylinder head and cylinder block.

[0041] Figure 18 yes Figure 17 A schematic cross-sectional view at line A-A.

[0042] Figure 19 yes Figure 17 A three-dimensional sectional view at the E-F-G line.

[0043] Figure 20 This is a top sectional view showing the structure of the cooling water passages in the cylinder head.

[0044] Figure 21 It is a top sectional view showing the structure of the exhaust flow path and intake flow path in the cylinder head.

[0045] Figure 22 This is a top view of the EGR device.

[0046] Figure 23 This is a cross-sectional perspective view of the EGR device.

[0047] Figure 24 This is a cross-sectional view of the part of the cylinder head that connects to the EGR cooler.

[0048] Figure 25 This is an exploded view of the part of the cylinder head that connects to the EGR cooler.

[0049] Figure 26 This is a rear view of the EGR cooler.

[0050] Figure 27 This is a rear view showing the structure of the cooling water flow path on the side of the cooling water pump inside the engine.

[0051] Figure 28 It is an exploded perspective view showing the installation structure of the cooling water pump and the cooling water inlet pipe.

[0052] Figure 29 This is a top view showing the cooling water flow path inside the cylinder block using a partial cross-section. Detailed Implementation

[0053] Hereinafter, embodiments in which the present invention is embodied will be described based on the accompanying drawings. First, referring to... Figures 1 to 8The overall structure of the diesel engine (engine unit) 1 will be described below. It should be noted that in the following description, the two sides parallel to the crankshaft 5 (the sides separated by the crankshaft 5) are referred to as the left and right sides, the side where the flywheel housing 7 is located is referred to as the front side, and the side where the cooling fan 9 is located is referred to as the rear side. For convenience, the above directions are used as the reference for the four directions and the vertical positional relationship of the diesel engine 1.

[0054] like Figures 1 to 8 As shown, an intake manifold 3 is disposed on one side of the diesel engine 1 parallel to the crankshaft 5, and an exhaust manifold 4 is disposed on the other side. In this embodiment, the intake manifold 3 is integrally formed with the cylinder head 2 on the right side, and the exhaust manifold 4 is disposed on the left side of the cylinder head 2. The cylinder head 2 is mounted on a cylinder block 6 which houses the crankshaft 5 and pistons (not shown).

[0055] 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 diesel 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 configured to be supported on the front end of the crankshaft 5 and rotate integrally with the crankshaft 5. It is configured to extract power from the diesel engine 1 to the working part of the working machinery (e.g., a hydraulic excavator, forklift, etc.) via the flywheel 8. A cooling fan 9 is provided on the other side of the diesel engine 1 that intersects with the crankshaft 5 (in this embodiment, the rear side of the cylinder block 6). It is configured to transmit rotational force from the rear end of the crankshaft 5 to the cooling fan 9 via a V-belt 10.

[0056] An oil pan 11 is disposed on the lower surface of the cylinder block 6. Lubricating oil is stored in the oil pan 11. The lubricating oil in the oil pan 11 is drawn by an oil pump (not shown) disposed on the right side of the cylinder block 6, at the portion connected to the flywheel housing 7, and supplied to each lubrication point 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 lubrication point then returns to the oil pan 11. The oil pump (not shown) is configured to be driven by the rotation of the crankshaft 5.

[0057] A fuel supply pump 15 for supplying fuel is installed on the part of the cylinder block 6 that connects to the flywheel housing 7. The fuel supply pump 15 is located below the EGR device 24. The 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 located above the fuel supply pump 15. Each of the four cylinders with electromagnetically controlled fuel injection valves is provided with an injector 17 (see reference) on the upper surface of the cylinder head 2 covered by the cover 18. Figure 17 ).

[0058] Each injector 17 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 in the fuel tank is pressurized from the fuel supply pump 15 to the common rail 16, thereby storing high-pressure fuel in the common rail 16. The fuel injection valves of each injector 17 are individually controlled to open and close, thereby injecting the high-pressure fuel in the common rail 16 from each injector 17 into each cylinder of the diesel engine 1.

[0059] The intake valve 136 and exhaust valve 137 (see reference) are located on the upper surface of the cylinder head 2. Figure 17 A leaked gas reduction device 19 is provided on the upper surface of the cover 18 covering the cylinder head 2. This device 19 introduces leaked gas from the combustion chamber of the diesel engine 1 to the upper surface of the cylinder head 2. The leaked gas outlet of the leaked gas reduction device 19 is connected to the intake section of the secondary turbocharger 30 via a reduction hose 68. After the lubricating oil components are removed in the leaked gas reduction device 19, the leaked gas is reduced to its original state via the secondary turbocharger 30 and then sent to the intake manifold 3.

[0060] An engine starter 20 is installed on the flywheel housing 7, and the engine starter 20 is located below the exhaust manifold 4. The engine starter 20 is installed on the flywheel housing 7 below the connection between the cylinder block 6 and the flywheel housing 7.

[0061] On the left side of the rear surface of the cylinder block 6, below the cooling fan 9, is a cooling water pump 21 for lubrication. The cooling water pump 21 and the cooling fan 9 are driven together by the rotation of the crankshaft 5 and the V-belt 10 used to drive the cooling fan. The cooling water pump 21 supplies coolant from the radiator (not shown) of the work vehicle to itself. Furthermore, coolant is supplied to the cylinder head 2 and the cylinder block 6 to cool the diesel engine 1.

[0062] A cooling water pump 21 is positioned below the exhaust manifold 4. A cooling water inlet pipe 22, which communicates with the radiator's cooling water outlet, is fixedly installed on the left side of the cylinder block 6 at the same height as the cooling water pump 21. On the other hand, a cooling water outlet pipe 23, which communicates with the radiator's cooling water inlet, is fixedly installed above the rear surface of the cylinder head 2. The cylinder head 2 has a cooling water drain section 35 protruding rearward from the intake manifold 3, and the cooling water outlet pipe 23 is provided on the upper surface of this drain section 35.

[0063] The inlet side of the intake manifold 3 is connected to the air purifier (not shown) via the collector (EGR main housing) 25 of the EGR device 24 (exhaust gas recirculation device), which will be described later. Fresh air (outdoor air) drawn in by the air purifier is cleaned and purified by the air purifier, and then delivered to the intake manifold 3 via the collector 25, and then 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 formed with the cylinder head 2 to constitute the right side surface 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 located on the right side surface of the cylinder head 2. It should be noted that, in this embodiment, as described later, the collector 25 of the EGR device 24 is connected to the air purifier via the intercooler (not shown) and the secondary turbocharger 30.

[0064] The EGR device 24 includes: a collector 25 serving as a relay line, which mixes the recirculated exhaust gas (EGR gas from the exhaust manifold 4) of the diesel engine 1 with fresh air (outdoor air from the air purifier) ​​and supplies the mixed gas 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 forms part of a return line connected to the exhaust manifold 4 via an EGR cooler 27; and an EGR valve component 29, which connects the collector 25 to the recirculated exhaust gas pipe 28.

[0065] The EGR device 24 is located on the right side of the intake manifold 3 of the cylinder head 2. That is, the EGR device 24 is fixed to the right side of the cylinder head 2 and communicates with the intake manifold 3 inside the cylinder head 2. For the EGR device 24, the collector 25 is connected to the intake manifold 3 on the right side of the cylinder head 2, and the EGR gas inlet of the recirculation exhaust gas pipe 28 is fixed by connecting to the front portion of the intake manifold 3 on the right side of the cylinder head 2. Furthermore, the EGR valve component 29 and the intake throttle component 26 are connected to the front and rear ends of the collector 25, respectively, and the EGR gas outlet of the recirculation exhaust gas pipe 28 is connected to the rear end of the EGR valve component 29.

[0066] 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 into or out of the EGR cooler 27, where the EGR gas is cooled. EGR cooler connecting bases 33 and 34, which connect the EGR cooler 27, protrude from the left and right sides of the front side of the cylinder head 2, thereby connecting the EGR cooler 27 to the connecting bases 33 and 34. In other words, 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 end face of the EGR cooler 27 from the front side of the cylinder head 2.

[0067] A two-stage turbocharger 30 is disposed on the side (left side in this 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 with a built-in turbine impeller (not shown) and a high-pressure compressor 54 with a built-in blower impeller (not shown). The low-pressure turbocharger 52 includes a low-pressure turbine 55 with a built-in turbine impeller (not shown) and a low-pressure compressor 56 with a built-in blower impeller (not shown).

[0068] The exhaust gas inlet 57 of the high-pressure turbine 53 is connected to the exhaust manifold 4. The exhaust gas inlet 60 of the low-pressure turbine 55 is connected to the exhaust gas outlet 58 of the high-pressure turbine 53 via the high-pressure exhaust gas pipe 59. The exhaust gas intake end of the exhaust gas discharge pipe (not shown) is connected to the exhaust gas outlet 61 of the low-pressure turbine 55. On the other hand, the fresh air supply side (fresh air outlet side) of the air purifier (not shown) is connected to the fresh air intake (fresh air inlet) 63 of the low-pressure compressor 56 via the air supply pipe 62. The fresh air intake 66 of the high-pressure compressor 54 is connected to the fresh air supply port (fresh air outlet) 64 of the low-pressure compressor 56 via the low-pressure fresh air passage pipe 65. The fresh air intake side of the intercooler (not shown) is connected to the fresh air supply port 67 of the high-pressure compressor 54 via the high-pressure fresh air passage pipe (not shown).

[0069] The high-pressure turbocharger 51 is connected to and fixed to the left side of the exhaust manifold 4 via the exhaust outlet 58. Conversely, the low-pressure turbocharger 52 is connected to and fixed above the exhaust manifold 4 via the high-pressure exhaust pipe 59 and the low-pressure fresh air passage pipe 65. In other words, the small-diameter high-pressure turbocharger 51 and the exhaust manifold 4 are arranged side-by-side below the large-diameter low-pressure turbocharger 52, thereby arranging the secondary turbocharger 30 to surround the left and upper surfaces of the exhaust manifold 4. Specifically, the exhaust manifold 4 and the secondary turbocharger 30 are arranged in a rectangular shape in rear view (front view) and are compactly fixed to the left side of the cylinder head 2.

[0070] Next, see below, for reference Figures 9 to 21 as well as Figure 27 The structure of cylinder head 2 will be explained. For example... Figures 9 to 21 as well as Figure 27As shown, the cylinder head 2 has multiple intake air passages 36 that introduce fresh air into multiple intake ports 141, and multiple exhaust air passages 37 that discharge exhaust gas from multiple exhaust ports 142. Furthermore, the intake manifold 3, where the multiple intake air passages 36 converge, is integrally formed with the right side portion of the cylinder head 2. By integrating the cylinder head 2 and the intake manifold 3, the gas sealing performance of the intake manifold 3 relative to the intake air passages 36 can be improved, and the rigidity of the cylinder head 2 can also be increased.

[0071] The cylinder head 2 is configured such that an exhaust manifold 4 is connected to the left side opposite to the right side where the intake manifold 3 is located, and an EGR cooler 27 is connected to the front side (flywheel housing 7 side side) adjacent to the left and right sides. Furthermore, the connecting bases (EGR cooler connecting bases) 33 and 34 connected to the EGR cooler 27 are formed to protrude from the front side of the cylinder head 2, and EGR gas flow paths (EGR gas relay flow paths) 31 and 32 and cooling water flow paths (cooling water relay flow paths) 38 and 39 are formed in the connecting bases 33 and 34.

[0072] The connecting bases 33 and 34, which connect to the EGR cooler 27, form EGR gas relay flow paths 31 and 32 and cooling water flow paths 38 and 39, thus eliminating the need for cooling water piping and EGR gas piping between the EGR cooler 27 and the cylinder head 2. Therefore, it is not affected by piping expansion and contraction caused by EGR gas and cooling water, ensuring not only the sealing of the part connected to the EGR cooler 27, but also improving the resistance to external factors such as heat and vibration (construction stability). Furthermore, it allows for a compact design.

[0073] The cylinder head 2 has an upstream EGR gas relay flow path 31 that connects to the front side from the left front portion, and the EGR gas outlet 41 located at the front end of the exhaust manifold 4 connects to the upstream EGR gas relay flow path 31. Additionally, the cylinder head 2 has a downstream EGR gas relay flow path 32 that connects to the front side from the right front portion (in front of the intake manifold 3), and the EGR gas inlet of the recirculation exhaust gas pipe 28 connects to the downstream EGR gas relay flow path 32. The cylinder head 2 has EGR cooler connecting bases 33 and 34 that protrude forward from the left and right edges of its front side (the left and right front corners of the cylinder head 2). The upstream EGR gas relay flow path 31 is located within the connecting base 33, and the downstream EGR gas relay flow path 32 is located within the connecting base 34.

[0074] The EGR device 24 is connected to the intake manifold 3, which protrudes from the right side of the cylinder head 2. The intake manifold 3 is configured such that it is located near the rear of the right side of the cylinder head 2 (towards the cooling fan 9), and the lower part of the right side of the cylinder head 2 protrudes to the right, with an intake inlet 40 at its center in the front-rear direction. The intake outlet 83 of the 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.

[0075] A connecting base 34, which connects to the EGR cooler 27, protrudes forward and is located on the right side of the cylinder head 2 (flywheel housing 7 side). An EGR gas outlet for the downstream EGR gas relay flow path 32 is provided on the right side of the connecting base 34. Furthermore, one end of the recirculation exhaust gas pipe 28 of the EGR device 24 is connected to the right side of the connecting base 34, thereby allowing the collector 25 of the EGR device 24 to communicate with the downstream EGR gas relay flow path 32 within the cylinder head 2 via the recirculation exhaust gas pipe 28 and the EGR valve component 29.

[0076] A cooling water drain section (thermostat housing) 35, with an open upper surface communicating with the cooling water outlet pipe (thermostat cover) 23, protrudes rearward and is located on the rear right side of the cylinder head 2 (towards the cooling fan 9). A thermostat (not shown) is housed inside this section. The cooling water drain section 35 is offset rearward on the right side of the cylinder head 2, allowing the V-belt 10 wound around the fan pulley 9a for fixing the cooling fan 9 to pass through the space below the cooling water drain section 35, thereby shortening the longitudinal length of the diesel engine 1. The cooling water drain section 35 also protrudes from the right side of the cylinder head 2, and the intake manifold 3 and the cooling water drain section 35 are arranged in a front-to-back configuration on the right side of the cylinder head 2.

[0077] A connecting base 33, which connects to the EGR cooler 27, protrudes forward and is located on the left side of the cylinder head 2 (flywheel housing 7 side). An EGR gas inlet for the upstream EGR gas relay flow path 31 is provided on the left side of the connecting base 33. That is, on the left side of the cylinder head 2, the EGR gas inlet of the upstream EGR gas relay flow path 31 and the exhaust outlets of multiple exhaust flow paths 37 are arranged in a front-rear direction. On the other hand, 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 relay flow path 31 and an exhaust inlet 42 communicating with multiple exhaust flow paths 37 are arranged in a front-rear direction. Therefore, since the EGR inlet and exhaust outlet are arranged on the same side of the cylinder head 2, airtightness (gas sealing) can be easily ensured by clamping a gasket 45 at the connection between the cylinder head 2 and the exhaust manifold 4.

[0078] An exhaust manifold 43, which connects to the EGR gas outlet 41 and the exhaust inlet 42, is internally located within the exhaust manifold 4 along its length in the rear-to-rear direction. An exhaust outlet 44, which connects to the exhaust manifold 43, opens on the rear left side of the exhaust manifold 4. If the exhaust manifold 4 allows exhaust gas from the exhaust flow path 37 of the cylinder head 2 to flow into the exhaust manifold 43 through the exhaust inlet 42, a portion of the exhaust gas becomes EGR gas and flows from the EGR gas outlet 41 into the upstream EGR gas relay flow path 31 of the cylinder head 2. The remaining exhaust gas flows from the exhaust outlet 44 into the second-stage turbocharger 30.

[0079] On the front side of the cylinder head 2, a pair of EGR cooler connecting bases 33 and 34 are respectively provided on the exhaust manifold 4 side and the intake manifold 3 side. Furthermore, the EGR cooler connecting base 33 has an upstream EGR gas relay flow path 31 that connects the exhaust manifold 4 and the respective EGR gas flow path of the EGR cooler 27. On the other hand, the EGR cooler connecting base 34 has a downstream EGR gas relay flow path 32 that connects the EGR device 24 and the respective EGR gas flow path of the EGR cooler 27. Additionally, the EGR cooler connecting base 33 has a downstream cooling water flow path 38 for discharging cooling water from the EGR cooler 27. On the other hand, the EGR cooler connecting base 34 has an upstream cooling water flow path 39 for supplying cooling water to the EGR device 24 and the EGR cooler 27.

[0080] By forming a structure in which the EGR cooler connecting bases 33 and 34 protrude, the EGR gas piping that connects the exhaust manifold 4, EGR cooler 27, and EGR device 24 separately is eliminated, reducing the number of connecting points in the EGR gas flow path. Therefore, for the diesel engine 1 that uses EGR gas to reduce NOx, not only can EGR gas leakage be reduced, but deformation caused by stress changes due to piping expansion and contraction can also be suppressed. In addition, since the EGR cooler connecting bases 33 and 34 form EGR gas relay flow paths 31 and 32 and cooling water flow paths 38 and 39, the shapes of each flow path 31, 32, 38, and 39 formed in the cylinder head 2 are simplified, thus allowing the cylinder head 2 to be easily cast without the need for a complex core.

[0081] Since the EGR cooler connecting base 33 on the intake manifold 3 side and the EGR cooler connecting base 34 on the exhaust manifold 4 side are separated, the influence of thermal deformation of the connecting bases 33 and 34 on each other can be suppressed. Therefore, not only can gas leakage and damage at the connection between the EGR cooler connecting bases 33 and 34 and the EGR cooler 27 be prevented, 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, the EGR cooler 27 can be configured to be separated from the front side of the cylinder head 2, forming a structure with space in front of and behind the EGR cooler 27. Therefore, cooling air can flow around the EGR cooler 27, thus improving the cooling efficiency of the EGR cooler 27.

[0082] A downstream cooling water flow path 38 and an upstream EGR gas relay flow path 31 are arranged vertically above and below the EGR cooler connecting base 33. A downstream EGR gas relay flow path 32 and an upstream cooling water flow path 39 are arranged vertically above and below the EGR cooler connecting base 34. Furthermore, the cooling water inlet of the downstream cooling water flow path 38 and the EGR gas inlet of the downstream EGR gas relay flow path 32 are located at the same height. Conversely, the cooling water outlet of the upstream cooling water flow path 39 and the EGR gas outlet of the downstream EGR gas relay flow path 32 are located at the same height.

[0083] By incorporating separate and protruding EGR cooler connecting bases 33 and 34 within EGR gas relay flow paths 31 and 32 and cooling water flow paths 38 and 39, the effects of thermal deformation on both sides of the EGR cooler connecting bases 33 and 34 are mitigated. Furthermore, within the EGR cooler connecting bases 33 and 34, the EGR gas flowing in the EGR gas relay flow paths 31 and 32 is cooled by cooling water flowing in the cooling water flow paths 38 and 39, thus suppressing the thermal deformation of the EGR cooler connecting bases 33 and 34 themselves. Moreover, in each EGR cooler connecting base 33 and 34, the EGR gas relay flow paths 31 and 32 and the cooling water flow paths 38 and 39 are arranged with their vertical height positions interchanged. Therefore, the heat distribution of the EGR cooler connecting bases 33 and 34 is in opposite vertical directions, thereby reducing the effects of thermal deformation in the height direction of the cylinder head 2.

[0084] The cylinder head 2 is connected to the lower periphery of the cover 18 by means of an outer peripheral wall that rises upward from the periphery of its upper surface. That is, the gasket 46 is composed of an outer peripheral wall including left and right side walls 46a and 46b and front and rear side walls 46c and 46d. Furthermore, bolt holes (cover-cover fastening bolt holes) 135 are provided through the upper end face (top) of each side wall 46a to 46d for engaging with cover fastening bolts 133 that are connected to the cover 18. In addition, bolt through holes (cylinder head fastening through holes) 136 are provided through the upper end face (top) of the right side wall 46b and the front and rear side walls 46c and 46d for inserting cylinder head fastening bolts 186 that are connected to the cylinder block 6.

[0085] The gasket 46 has multiple openings 47 on its right side wall 46a, through which the fuel pipe 48, which connects the injector 17 and the common rail 16 located on the cylinder head 2, passes. By forming a structure in which the gasket 46 is integrally provided on the top of the cylinder head 2, not only can the rigidity of the cylinder head 2 be improved and the deformation of the cylinder head 2 itself be reduced, but also the components connected to the cylinder head 2 can be supported with high rigidity.

[0086] The cover 18 is connected to the gasket 46 of the cylinder head 2 by means of cover fastening bolts 133, thereby forming a valve arm chamber covered by the gasket 46 and the cover 18, which houses the injector 17 and the valve mechanism 187 described later. In the area of ​​the cylinder head 2 surrounded by the gasket 46, an injector mounting seat 138 for fixing the injector 17, a valve mechanism mounting seat 139 for fixing the valve mechanism 187, and a bolt fastening connection seat 140 for fixing the cylinder head fastening bolts 186 are provided from the bottom surface upwards. The upper end surfaces of the valve mechanism mounting seat 139 and the bolt fastening connection seat 140 are at the same height as the upper end surface of the gasket 46, and are provided with bolt through holes (cylinder head connection through holes) 136 for inserting the cylinder head fastening bolts 186.

[0087] The cylinder head 2 is fastened to the cylinder block 6 using cylinder head fastening bolts 186 that are inserted into the through holes 135 of the cylinder head fastening bolts 135 provided on the right side wall 46b of the gasket 46, the front and rear side walls 46c and 46d, the valve mechanism mounting seat 139, and the bolt fastening connection seat 140. Intake ports 141 and 142, which are opened and closed by intake valves 136 and 137 respectively, are located below the injector mounting seat 138 on the bottom surface of the cylinder head 2. Furthermore, within the cylinder head 2, multiple intake airflow paths 36 branching from the intake manifold 3 on the right side of the cylinder head 2 extend toward the intake port 141 below the injector mounting seat 138. Additionally, multiple exhaust airflow paths 37 communicating with the exhaust manifold 4 fixed to the left side of the cylinder head 2 extend toward the exhaust port 142 below the injector mounting seat 138.

[0088] An EGR cooler 27 is connected to the front side of the cylinder head 2. Furthermore, EGR gas relay paths (EGR gas flow paths) 31 and 32, and cooling water relay paths (cooling water flow paths) 37 and 38, are provided at the connection point between the cylinder head 2 and the EGR cooler 27. By directly connecting the EGR cooler 27 to the cylinder head 2, there is no need to install cooling water piping or EGR gas piping between the EGR cooler 27 and the cylinder head 2. Therefore, it is not affected by piping expansion or contraction caused by EGR gas or cooling water, ensuring not only the sealing of the connection point with the EGR cooler 27, but also improving the cylinder head 2's resistance to external variations based on heat, vibration, etc. (structural stability), and allowing for a compact design.

[0089] A gasket 46 is erected on the cylinder head 2, formed by an outer peripheral wall surrounding the region (forming the valve arm chamber) that connects to the exhaust manifold 4 starting from the boundary relative to the intake manifold 3. Furthermore, a cooling water confluence passage 143 forming an L-shaped cooling water flow path is provided on the right side wall 46b and the front side wall 46c of the gasket 46. Since the cooling water confluence passage 143 is formed along the gasket 46 constituting the outer peripheral wall of the cylinder head 2, the side walls 46b and 46c with the cooling water confluence passage 143 are constructed like beams, improving the rigidity against warping of the cylinder head 2. Therefore, when the cylinder head 2 is manufactured by casting, warping during the subsequent separation process is improved.

[0090] The cylinder head 2 is securely fixed to the cylinder block 6 using multiple cylinder head fastening bolts 186 inserted into the right side wall 46b and the front and rear side walls 46c and 46d of the gasket 46. At this time, coolant flows in the coolant manifold 143 in the right side wall 46b and the front side wall 46c, thereby suppressing the elongation (thermal deformation) of the cylinder head fastening bolts 186 caused by combustion heat in the cylinder, and rigidly connecting the cylinder head 2 to the cylinder block 6 without compromising the cylinder's sealing performance. The cylinder head 2 has a coolant drain section 35 on its rear side, adjacent to the end of the intake manifold 3, which communicates with the coolant manifold 143 provided in the gasket 46.

[0091] Specifically, the upstream side of the cooling water manifold 143 extends along the front sidewall 46c in the left-right direction, and its left end (the upstreammost point) communicates with the downstream cooling water relay flow path 38 provided on the EGR cooler connecting base 33 on the left side of the front side of the cylinder head 2. Furthermore, the downstream side of the cooling water manifold 143 extends along the right sidewall 46b in the front-rear direction, and its rear end (the downstreammost point) communicates with the cooling water drain section 35. Additionally, the downstream flow path of the cooling water manifold 143 provided on the right sidewall 46b branches towards the exhaust manifold 4 and communicates with the cooling water jacket 144 that surrounds the intake flow path 36 and the exhaust flow path 37. Thus, each cylinder can be cooled uniformly within the cylinder head 2.

[0092] The cooling water jacket 144 is configured to surround the bolts with through holes 135 below the valve mechanism mounting seat 139 and the bolt fastening connection seat 140, thereby cooling the cylinder head fastening bolts 186 that pass through the cylinder head 2 and screw onto the cylinder block 6. Therefore, the flow of cooling water in the cooling water jacket 144 suppresses the elongation (thermal deformation) of the cylinder head fastening bolts 186 caused by combustion heat in the cylinder or heat from exhaust gases passing through the exhaust passage 37, enabling the cylinder head 2 to be rigidly connected to the cylinder block 6 without compromising the cylinder's sealing performance.

[0093] The upstream cooling water relay path 39 is connected to the front end of the cooling water rail 185 located on the right side of the cylinder block 6 via the upper and lower cooling water flow paths. Furthermore, a cooling water inlet 328, supplied by the cooling water pump 21, is formed at the rear end of the cooling water rail 185. Thus, the cooling water supplied by the cooling water pump 21 is supplied to the EGR cooler 27 through the cooling water rail 185 and the upstream cooling water relay path 39.

[0094] Cooling water from the EGR cooler 27 flows into the cooling water manifold 143 of the cylinder head 2 via the downstream cooling water relay passage 38. The cooling water from the cooling water manifold 143 is then distributed to the cooling water jackets 144 provided for each cylinder within the cylinder head 2, thereby cooling each part of the cylinder head 2. It should be noted that the cooling water jackets 144 of the cylinder head 2 are connected to the cooling water jackets 184 of the cylinder block 6, and the cooling water in the cooling water jackets 144 of the cylinder head 2 is discharged into the cooling water rail 185 after being supplied to the cooling water jackets 184 of the cylinder block 6.

[0095] Furthermore, the cooling water drain passage 145, which extends downward through the cooling water drain section 35, is connected to the cooling water return passage 146 located inside the rear end face of the cylinder block 6. As a result, a portion of the cooling water flowing from the cooling water confluence passage 143 of the cylinder head 2 into the cooling water drain section 35 returns to the pump suction port 334 of the cooling water pump 21 via the cooling water return passage 146 of the cylinder block 6.

[0096] Next, see below, for reference Figures 9-15 , Figure 22 as well as Figure 23 The structure of the EGR device 24 will be explained. For example... Figures 9-15 , Figure 22 as well as Figure 23 As shown, the EGR device 24 includes a collector (main housing) 25 that mixes fresh air and EGR gas and supplies it to the intake manifold 3. The intake manifold 3 and the intake throttling component 26 for introducing fresh air are connected and communicated via the collector 25. The EGR valve component 29, which is connected to the outlet side of the recirculated exhaust gas pipe 28, is connected and communicated with the collector 25.

[0097] Within the collector 25, the fresh air flow direction and the EGR gas flow direction are orthogonal or intersecting at an obtuse angle. The direction in which the mixture of EGR gas and fresh air is drawn into the intake manifold 3 becomes a direction that intersects both the fresh air flow direction and the EGR gas flow direction. Furthermore, the fresh air inlet 81 for supplying fresh air and the EGR gas inlet 82 for supplying EGR gas open on the front and rear sides of the collector 25, respectively, while the intake outlet 83, connected to the intake manifold 3, opens on the left side of the collector 25. The EGR gas inlet 82 and the intake outlet 83 are positioned at the same height, while the fresh air inlet 81 and the EGR gas inlet 82 are positioned at different heights.

[0098] Within the collector 25, the fresh air introduced into the fresh air inlet 81 from the intake throttling component 26 flows in an L-shaped bend from the front-to-back direction to the up-and-down direction. On the other hand, the EGR gas introduced into the EGR gas inlet 82 from the EGR valve component 29 flows obliquely upward. Therefore, the EGR gas flows in the direction of the fresh air flow, making it easy for the EGR gas to mix with the fresh air. In addition, the mixed gas of fresh air and EGR gas flows in an L-shaped bend from the up-and-down direction to the left-and-right direction and flows into the intake manifold 3 from the intake outlet 83. The outlet direction of the mixed gas is not only the direction of the fresh air introduction and the direction of the EGR gas introduction, but also intersects with the flow direction of the fresh air and EGR gas within the collector 25. Therefore, the mixing distribution of EGR gas into the fresh air can be made uniform.

[0099] As described above, within the collector 25, the EGR gas flow direction is at an angle of 90° or more relative to the fresh air flow direction, and the fresh air and EGR gas flow intersect. This results in a more uniform mixing distribution of the EGR gas relative to the fresh air, suppressing EGR gas deviation within the intake manifold 3. Consequently, the EGR gas concentration in the intake air supplied to the multiple intake air passages 36 of the cylinder head 2 is made uniform, thereby suppressing deviations in combustion in each cylinder of the diesel engine 1. As a result, black smoke generation is suppressed, maintaining good combustion in the diesel engine 1 and reducing NOx levels. That is, misfires are prevented in specific cylinders, and exhaust gas purification (cleaning) is achieved through the recirculation of EGR gas.

[0100] The collector 25 is formed by connecting an upper outer shell (first outer shell) 84 with a fresh air inlet 81 and a lower outer shell (second outer shell) 85 with an EGR gas inlet 82 and an air outlet 83. By forming the collector 25 into an upper outer shell 84 and a lower outer shell 85 that can be divided vertically, a mixing flow path in which the EGR gas flow and the fresh air flow intersect at an angle of 90° or more can be easily formed within the collector 25. Therefore, the collector 25 can be made of a high-rigidity casting, and it can also be made of aluminum-based casting to achieve lightweight construction.

[0101] A downstream EGR gas flow path (first EGR gas flow path) 86a, which is part of the EGR gas flow path 86 for supplying EGR gas, and a mixing chamber 87 for mixing fresh air and EGR gas are provided on the upper housing 84. An upstream EGR gas flow path (second EGR gas flow path) 86b, which connects the downstream EGR gas flow path 86a and the EGR gas inlet 82, and a mixed gas flow path 88, which supplies the mixed gas obtained by mixing fresh air and EGR gas from the mixing chamber 87 to the intake manifold 3, are provided on the lower housing 85.

[0102] An EGR gas inlet 82 is provided in the lower outer casing 85, while a fresh air inlet 81 and a mixing chamber 87 are provided in the upper outer casing 84. Therefore, in the mixing chamber 87, the fresh air flowing in from the fresh air inlet 81 and the EGR gas flowing in from the lower outer casing 85 flow in a cross-flow manner, thereby achieving efficient mixing of the fresh air and EGR gas. Furthermore, by providing an air inlet outlet 83 in the lower outer casing 85, the fresh air flowing into the upper outer casing 84 is directed towards the lower outer casing 85, thereby achieving homogenization of the mixing of the EGR gas flowing towards the upper outer casing 84 with the fresh air. Additionally, the EGR gas flow path 86, the mixing chamber 87, and the mixed gas flow path 88 can be compactly configured within the collector 25, thereby enabling miniaturization of the collector 25.

[0103] Viewed from above, the downstream EGR gas flow path 86a is offset to the side opposite to the side where the intake outlet 83 is located (the right side) with respect to the central axis of the mixing chamber 87, such that the downstream EGR gas flow path 86a and the upstream EGR gas flow path 86b are connected, thereby making the EGR gas flow path 86 spiral. That is, the EGR gas flow path 86 formed by the downstream EGR gas flow path 86a and the upstream EGR gas flow path 86b becomes a shape that bends in a way that expands towards the side opposite to the intake outlet 83 (the right side) when viewed from above. Furthermore, the bottom of the upstream EGR gas flow path 86b is formed by an inclined surface (an inclined surface towards the rearward and upward side) extending from the EGR gas inlet 82 towards the upper outer casing 84.

[0104] The portion of the mixing chamber 87 that connects to the EGR gas flow path 86 is located on the opposite side of the inlet outlet 83. Therefore, the EGR gas flowing into the mixing chamber 87 is guided by the fresh air flow to the inlet outlet 83, thereby enabling the EGR gas to be uniformly mixed with the fresh air. Furthermore, the EGR gas flowing from the EGR gas flow path 86 into the mixing chamber 87 flows in the opposite direction to the airflow from the mixing chamber 87 towards the mixed gas flow path 88. Therefore, within the mixing chamber 87, the fresh air and EGR gas flow in contact with each other, thereby ensuring smooth mixing of the EGR gas and the fresh air.

[0105] Furthermore, as the EGR gas flows along the spiral EGR gas flow path 86, it becomes a swirling flow forming a clockwise vortex as it flows into the mixing chamber 87. This turbulent EGR gas flows in the opposite direction to the fresh air flow, thus smoothly mixing with the fresh air flowing inside the mixing chamber 87 as it flows in. Therefore, within the collector 25, the fresh air and EGR gas can be stirred and efficiently mixed before being introduced into the intake manifold 3 (ensuring smooth dispersion of the EGR gas in the mixture), more reliably suppressing deviations (unevenness) in the gas mixture within the collector 25. As a result, a less uneven mixture can be distributed to each cylinder of the diesel engine 1, suppressing deviations in the amount of EGR gas between cylinders. Therefore, black smoke production can be suppressed, maintaining good combustion in the diesel engine 1 and reducing NOx levels. Furthermore, by making the EGR gas flow path 86 spiral, sufficient vortexing is given to the EGR gas flowing into the mixing chamber 87, thus enabling the collector 25 to be made shorter in the front-to-back direction.

[0106] The lower surface flange 84a of the upper housing 84 and the upper surface flange 85a of the lower housing 85 are fastened together with bolts to form a collector 25 with openings in three directions (front-rear and left-side) (fresh air inlet 81, EGR gas inlet 82, and air inlet outlet 83). The upper housing 84 is configured such that the fresh air outlet of the intake throttling component 26 is fastened to the rear surface flange 84b, which has the fresh air inlet 81, by bolts. The opening degree of the intake valve (butterfly valve) 26a located inside the intake throttling component 26 is adjusted, thereby adjusting the amount of fresh air supplied to the collector 25.

[0107] The EGR gas outlet of the EGR valve assembly 29 is securely connected to the front surface flange 85b of the lower housing 85, which has an EGR gas inlet 82, by means of a rectangular tubular relay flange 89 and bolts. The opening degree of the EGR valve (not shown) located inside the EGR valve assembly 29 is adjusted, thereby adjusting the supply of EGR gas to the collector 25. The reed valve 90, inserted into the EGR gas inlet 82, is fixed inside the front surface flange 85b of the lower housing 85. Furthermore, the relay flange (gasket) 89, which is securely connected to the front surface flange 85b by bolts, covers the front of the reed valve 90, thereby positioning the reed valve 90 on the side of the EGR gas inlet 82 of the EGR gas flow path 86 within the collector 25.

[0108] An EGR gas outlet 89a, communicating with an EGR gas inlet 82, is provided on the rear surface of the relay flange 89, which connects to the collector 25. Valve connecting seats 89b and 89c, connected to the EGR valve component 29, protrude from the front surface of the relay flange 89, and the openings of the valve connecting seats 89b and 89c communicate with the EGR gas outlet of the EGR valve component 29. In the relay flange 89, EGR gas converges at the EGR gas inlets of the upper and lower valve connecting seats 89b and 89c, and flows from the EGR gas inlet 82 through the reed valve 90 into the EGR gas flow path 86 within the collector 25.

[0109] The EGR valve component 29 is configured such that an EGR valve (not shown) is provided in the EGR gas flow path 29f provided in the valve body 29e, and an actuator 29d for adjusting the opening of the EGR valve is provided above the valve body 29e. The EGR valve component 29 is connected to the front of the collector 25 via a relay flange 89 with the vertical direction as the length direction. On the rear surface of the lower valve body 29e, the EGR valve component 29 has outlet side flanges 29a and 29b that are respectively connected to the valve connecting seats 89b and 89c of the relay flange 89. On the other hand, the front surface of the EGR valve component 29 has an inlet side flange 29c, which has an EGR gas inlet that communicates with the EGR gas outlet of the recirculated waste gas pipe 28.

[0110] EGR valve component 29 is configured such that when EGR gas cooled by EGR cooler 27 flows into the EGR gas inlet of inlet flange 29c via downstream EGR gas relay flow path 32 of EGR cooler connecting base 34 and recirculation exhaust gas pipe 28, the EGR gas is split upwards and downwards through EGR gas flow path 29f of valve body 29e. Furthermore, the flow rate of the EGR gas split upwards and downwards via EGR gas flow path 29f is adjusted by the EGR valve, causing the gas to flow from the EGR gas outlet of the upper and lower outlet flanges 29a and 29b into relay flange 89.

[0111] The recirculation exhaust gas pipe 28 includes a gas pipe section 28a, which is bent into an L-shape when viewed from above; and a flat reinforcing rib 28b, which protrudes from the inner circumference of the outer wall of the gas pipe section 28a. Furthermore, the recirculation exhaust gas pipe 28 is configured such that an outlet flange 28c, connected to the inlet flange 29c of the EGR valve component 29, is located at one end (rear end) of the gas pipe section 28a, while an inlet flange 28d, connected to the right side of the EGR cooler connecting base 34, is located at the other end (left end) of the gas pipe section 28a. Additionally, a sensor mounting base 28e for mounting an EGR gas temperature sensor is provided on the upper surface of the bent portion of the gas pipe section 28a of the recirculation exhaust gas pipe 28.

[0112] Because the EGR device 24 can be configured to shorten the length of the collector 25, the distance between the EGR valve component 29 and the intake throttle component 26 can be shortened, resulting in a shorter front-to-back length of the EGR device 24. Furthermore, since the EGR valve component 29 is configured with the actuator 29d positioned above, the uppermost parts of the EGR valve component 29, the collector 25, and the intake throttle component 26 can be at the same height. Therefore, not only can the vertical height of the EGR device 24 be lowered, but its horizontal width can also be narrower. Thus, because the EGR device 24 is compactly configured, it can be easily connected to the right side of the cylinder head 2, which is integrally formed with the intake manifold 3, simply by adjusting the recirculated exhaust gas pipe 28. This also contributes to the miniaturization of the diesel engine 1.

[0113] The recirculation exhaust gas pipe 28 is configured such that flat reinforcing ribs 28b connect both ends of the gas pipe section 28a. This configuration results in high rigidity of the recirculation exhaust gas pipe 28 and increases the support strength of the front end of the EGR device 24 relative to the cylinder head 2. Furthermore, the recirculation exhaust gas pipe 28 is configured such that flat reinforcing ribs 28b are provided along the EGR gas flow path 28f within the gas pipe section 28a. This increases the heat dissipation area of ​​the gas pipe section 28a due to the reinforcing ribs 28b, thereby improving the cooling effect of the EGR gas flowing in the EGR gas flow path 28f. As a result, it facilitates the cooling of the gas mixture refined by the EGR device 24, and easily maintains the NOx reduction achieved using the gas mixture at an appropriate level.

[0114] Next, see below, for reference Figures 9-16 as well as Figures 24-26 The structure of the EGR cooler 27 will be explained. For example... Figures 9-16 as well as Figures 24-26 As shown, the EGR cooler 27 includes: a heat exchange section 91, which is formed by alternating layers of cooling water flow paths and EGR gas flow paths; and a pair of left and right flanges 92 and 93, which are disposed at the left and right ends of one side of the heat exchange section 91. A cooling water outlet 94 and a cooling water inlet 95 are separately disposed on the left and right flanges 92 and 93, while an EGR gas inlet 96 and an EGR gas outlet 97 are separately disposed on the left and right flanges 92 and 93. Furthermore, the left and right flanges 92 and 93 are connected to the front side of the cylinder head 2, and the EGR cooler 27 is fixed to the cylinder head 2.

[0115] By forming a structure in which openings for cooling water and EGR gas are respectively provided on the left and right flange portions 92 and 93, the flange portions 92 and 93 can be constructed from common components, and the material cost of the flange portions 92 and 93 can be reduced. Furthermore, the flange portions 92 and 93 are configured such that through holes 94 to 97 for cooling water and EGR gas are respectively provided in the flat plate connecting to the cylinder head 2, thus facilitating the manufacture of the EGR cooler 27. In addition, the connection between the flange portions 92 and 93 and the heat exchange section 91 can be minimized, thereby reducing the amount of heat transferred from the cylinder head 2 to the heat exchange section 91, and improving the cooling effect of the EGR gas in the heat exchange section 91.

[0116] The EGR cooler 27 is structured such that flanges 92 and 93 protrude from the rear surface of the heat exchange section 91, thereby creating a space between the heat exchange section 91 and the cylinder head 2. Therefore, the EGR cooler 27 is configured such that a large portion of the front and rear surfaces of the heat exchange section 91 are exposed to the outside air, and heat is also dissipated from the heat exchange section 91. Thus, the cooling effect of the EGR gas in the EGR cooler 27 is improved. Therefore, compared to the case where the rear and front surfaces of the heat exchange section 91 are installed, the number of layers of the heat exchange section 91 can be reduced, and the front and rear length of the EGR cooler 27 can be shortened, thus enabling miniaturization of the diesel engine 1.

[0117] A cooling water outlet 94 and an EGR gas inlet 96 are provided on the left flange portion 92, while a cooling water inlet 95 and an EGR gas outlet 97 are provided on the right flange portion 93. Furthermore, the cooling water outlet 94 and the EGR gas inlet 96 are arranged vertically on the left flange portion 92, and the EGR gas outlet 97 and the cooling water inlet 95 are arranged vertically on the right flange portion 93. Additionally, the cooling water outlet 94 and the EGR gas outlet 97 are positioned at the same height, as are the cooling water inlet 95 and the EGR gas inlet 96.

[0118] At this time, the left and right flange portions 92 and 93 of the EGR cooler 27 are connected to the EGR cooler connecting bases 33 and 34, which are formed to protrude from the front side of the cylinder head 2, respectively. Furthermore, the upstream EGR gas relay flow path 31 and the downstream cooling water relay flow path 38 of the left EGR cooler connecting base 33 are connected to the EGR gas inlet 96 and the cooling water outlet 94 of the left flange portion 92, respectively. The downstream EGR gas relay flow path 32 and the upstream cooling water relay flow path 39 of the right EGR cooler connecting base 34 are connected to the EGR gas outlet 97 and the cooling water inlet 95 of the right flange portion 93, respectively.

[0119] The connecting bases 33 and 34 of the flange portions 92 and 93 connecting to the EGR cooler 27 form EGR gas relay flow paths 31 and 32 and cooling water flow paths 38 and 39, and the EGR gas inlet 96 and outlet 97 and the cooling water outlet 94 and inlet 95 are connected at the flange portions 92 and 93. Therefore, there is no need to install cooling water piping and EGR gas piping between the EGR cooler 27 and the cylinder head 2. Therefore, it is not affected by the expansion and contraction of piping caused by EGR gas and cooling water, and the sealing of the connection between the EGR cooler 27 and the cylinder head 2 can be ensured. Furthermore, the resistance of the EGR cooler 27 to external factors such as heat and vibration is improved, and it can be compactly installed in the cylinder head 2.

[0120] Because the structure is such that a cooling water outlet 94 and an EGR gas inlet 96 are provided above and below the flange portion 92, and an EGR gas outlet 97 and a cooling water inlet 95 are provided above and below the flange portion 93, flange portions 92 and 93 of the same shape can be installed on the heat exchange portion 91 inverted positions. Therefore, the number of components constituting the EGR cooler 27 can be reduced, the EGR cooler 27 has good assemblability, and component costs are reduced.

[0121] Furthermore, flange portion 92 is provided with a cooling water outlet 94 and an EGR gas inlet 96 for cooling water or EGR gas with a large heat output, while flange portion 93 is provided with a cooling water inlet 95 and an EGR gas outlet 97 for cooling water or EGR gas with a smaller heat output. Therefore, not only is the deformation caused by the thermal deformation of flange portions 92 and 93 suppressed, but the influence caused by the thermal deformation of each other is also reduced because flange portions 92 and 93 are separately constructed, thus preventing damage and malfunction of the EGR cooler 27.

[0122] In a rear view, the coolant outlet 94 and coolant inlet 95 of the EGR cooler 27 are positioned diagonally, as are the EGR gas inlet 96 and EGR gas outlet 97. By supplying or discharging EGR gas and coolant of different heat values ​​from these diagonally opposite positions, thermal deformation of the connection between the EGR cooler 27 and the cylinder head 2 can be mitigated, thereby suppressing deflection and loosening of the connection. Therefore, leakage of EGR gas and coolant from the EGR cooler 27 and cylinder head 2 is prevented, and a decrease in connection strength is also prevented.

[0123] A plate-shaped sealing gasket 98 is clamped between the cylinder head 2 and the flanges 92 and 93, mounted on the left and right flanges 92 and 93 respectively. O-rings 99, which are ring-shaped sealing components, are embedded in the cooling water inlet and cooling water outlet of the cylinder head 2, which are respectively connected to the cooling water outlet 94 and cooling water inlet 95 of the flanges 92 and 93. The O-rings 99 are covered by the flanges 92 and 93.

[0124] Since the separate flange portions 92 and 93 are connected to the connecting bases 33 and 34 of the cylinder head 2 via the sealing gasket 98, tension is applied to the sealing gasket 98 due to the thermal deformation of the portion connected to the cylinder head 2. Therefore, at the respective connecting portions of the EGR gas inlet 96 and the EGR gas outlet 97, the sealing performance of the sealing gasket 98 is improved, preventing leakage of EGR gas flowing between the cylinder head 2 and the EGR cooler 27. In addition, since the O-ring 99 is embedded in the space formed by the coolant inlet and outlet of the connecting bases 33 and 34 of the cylinder head 2 and the rear end faces of the flange portions 92 and 93, when coolant flows, the connecting portions of the connecting bases 33 and 34 and the flange portions 92 and 93 abut against the O-ring 99, ensuring the sealing performance of the connecting portions of the coolant inlet and outlet. Therefore, even if the EGR cooler 27, which is used to allow liquid and gas to flow in and out, is connected to the cylinder head 2, the sealing of the liquid and gas can be ensured, and leakage of EGR gas and cooling water can be prevented.

[0125] Through holes 100 for bolt fastening are provided on the outer periphery and outer side of flange portions 92 and 93. That is, there are 5 through holes 100 on the upper, lower, and left sides of the left flange portion 92, and 5 through holes 100 on the upper, lower, and right sides of the right flange portion 93. Therefore, through holes 100 are provided on the upper side of the coolant outlet 94, the lower side of the EGR gas inlet 96, and the left side between the coolant outlet 94 and the EGR gas inlet 96 of the left flange portion 92. Thus, when fastened to the connecting base 33 of the cylinder head 2 by bolts, the sealing of the coolant outlet 94 and the EGR gas inlet 96 is ensured. Similarly, through holes 100 are provided on the right flange 93, 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. Thus, when the cooling water inlet 95 and the EGR gas outlet 97 are fastened to the cylinder head 2 by means of bolts, the sealing of the cooling water inlet 95 and the EGR gas outlet 97 is ensured.

[0126] A sealing gasket 98 is formed by bonding two plates 98a and 98b, each having through holes 101 to 103, together. EGR gas passes through the through hole 101, and cooling water passes through the through hole 102. A fastening bolt is inserted into the through hole 103. The sealing gasket 98 is configured such that the inner periphery of the EGR gas through hole 101 branches in a warped manner along the front-back direction, and the opening area of ​​the cooling water through hole 102 is larger than the opening area of ​​the cooling water inlets and outlets 94 and 95.

[0127] For the sealing gasket 98, the inner periphery of the EGR gas through hole 101 in the front side plate 98a is warped forward, and the inner periphery of the EGR gas through hole 101 in the rear side plate 98b is warped rearward. The front side plate 98a and the rear side plate 98b are then welded together, thereby forming a Y-shaped cross-section of the inner periphery of the EGR gas through hole 101. By forming the inner periphery of the EGR gas through hole 101 into a warped shape, the front and rear surfaces of the inner periphery of the EGR gas through hole 101 are in close contact with the end faces of the connecting bases 33 and 34 and the flange portions 92 and 93, thereby ensuring sufficient airtightness.

[0128] The sealing gasket 98 is configured such that the opening of the cooling water through hole 102 is larger than the opening of the cooling water inlet / outlet 94, 95, thereby allowing the O-ring 99 to be inserted into the cooling water through hole 102. That is, the O-ring 99, which fits into the cooling water through hole 102 of the sealing gasket 98, seals the connection between the cooling water inlet / outlet of the flange portions 92, 93 and the cooling water relay paths 38, 39 in the connecting bases 33, 34.

[0129] Furthermore, the connecting bases 33 and 34 of the cylinder head 2 are respectively provided with cooling water inlets and outlets in a stepped shape. This results in an opening diameter larger than the flow path diameter of the cooling water relay paths 38 and 39 in the connecting bases 33 and 34. The O-ring 99 is fitted with the outer periphery of the cooling water relay paths 38 and 39 relative to the cooling water inlets and outlets of the connecting bases 33 and 34. That is, the O-ring 99 is inserted into the sealing gasket 98 and fitted with the stepped portion of the cooling water inlet and outlet of the connecting bases 33 and 34, thereby being held by the connecting bases 33 and 34 and the flanges 92 and 93. Therefore, cooling water passes through the inner side of the O-ring 99, which is made of elastic material. As a result, the O-ring 99 deforms in a way that expands outwards, ensuring the sealing of the cooling water by tightly contacting the connecting bases 33 and 34 and the flanges 92 and 93.

[0130] The annular O-ring 99 has an inner circumferential portion that expands forward and backward, and is deformed by the cooling water passing through the inner circumferential portion of the O-ring, causing the front and rear edges of the inner circumferential portion to protrude forward and backward. This ensures that the inner circumferential portion of the O-ring 99 is in close contact with the connecting bases 33 and 34 and the flanges 92 and 93, thereby improving the cooling water sealing of the connection between the cylinder head 2 and the EGR cooler 27.

[0131] Furthermore, the annular O-ring 99 is formed with its inner circumferential portion expanding forward and backward, and having a concave portion on its inner circumferential surface. That is, the inner circumferential surface of the O-ring 99 is formed by a Y-shaped cross-section that curves forward and backward, so that it is pressed by the cooling water passing through the inner circumferential portion of the O-ring, and the front and rear edges of the inner circumferential portion protrude further forward and backward. This improves the tightness of the inner circumferential portion of the O-ring 99 with the connecting bases 33 and 34 and the flange portions 92 and 93, thereby improving the cooling water sealing performance of the connection between the cylinder head 2 and the EGR cooler 27.

[0132] Next, refer to Figures 17-19 The structure of the cylinder block 6 and the valve mechanism will be described below. The cylinder block 6 includes: a crankcase 171 that houses the crankshaft 5; and cylinder bores 173 for each of the four cylinders, each housing a piston 172. Each piston 172 is configured to be connected to the crankshaft 5 via a connecting rod 174 and to slide freely up and down within the cylinder bore 173.

[0133] Additionally, the cylinder block 6 includes: a cam chamber 176 that houses the camshaft 175; a cylinder block-side pushrod chamber 178 (pushrod chamber) that houses the lower end of the pushrod 177; and a tappet retainer 180 that holds the tappet 179 in a sliding position. The tappet 179 is positioned between the intake cam 175a or exhaust cam 175b of the camshaft 175 and the pushrod 177, transmitting the driving force of the camshaft 175 to the pushrod 177.

[0134] The cam chamber 176 extends along the longitudinal direction of the engine 1 to the left of the cylinder bore 173. The cam chamber 176 communicates with the crankcase 171. The camshaft 175 has a set of intake cams and exhaust cams for each cylinder, and a camshaft journal pivotally supported on a bearing portion of the cam chamber 176 is provided between the sets of intake and exhaust cams. The cam chamber 176 is divided into multiple partitioned cam chambers 181 for each set of intake and exhaust cams of the camshaft 175 (for each cylinder). In this embodiment, the cam chamber 176 is divided into four partitioned cam chambers 181.

[0135] The cylinder block side pushrod chamber 178 is disposed above the cam chamber 176 and is divided for each cylinder. In this embodiment, four cylinder block side pushrod chambers 178 are provided in the longitudinal direction of the engine 1. In addition, a communication hole 182 is formed on the mating surface of the cylinder block 6 and the cylinder head 2 for each cylinder block side pushrod chamber 178. Furthermore, the lower end of two pushrods 177 are inserted into each cylinder block side pushrod chamber 178 and the communication hole 182. A tappet holding portion 180 is formed between the cam chamber 176 and the cylinder block side pushrod chamber 178, separating the cam chamber 176 and the cylinder block side pushrod chamber 178. In addition, the cylinder block 6 is configured such that a bypass passage 183 is formed between the tappet holding portion 180 and the cylinder bore 173, which connects the cylinder block side pushrod chamber 178 and the cam chamber 176.

[0136] Additionally, the cylinder block 6 includes a cooling water jacket 184 disposed around the cylinder bore 173, and a cooling water track 185 extending in the longitudinal direction. The cooling water track 185 is positioned lower than the cooling water jacket 184 on the right side of the cylinder bore 173. Furthermore, the cooling water track 185 extends approximately along the irregularities of the cylinder bores 173 of the four cylinders when viewed from above. Also, when viewed from above, the cooling water track 185 is positioned at a different axis than the cylinder head fastening bolts 186 used to secure the cylinder head 2 to the cylinder block 6.

[0137] The cylinder head 2 is fastened to the cylinder block 6 by means of cylinder head fastening bolts 186. The upper surface of the cylinder head 2 is covered by a cover 18. The space inside the cover 18 forms a valve arm chamber. A valve mechanism 187 associated with the camshaft 175 is disposed inside the cover 18. In addition, an intake valve 136 and an exhaust valve 137 are provided inside the cylinder head 2 corresponding to each cylinder. The engine 1 of this embodiment is a four-valve engine with two intake valves 136 and two exhaust valves 137 for each cylinder.

[0138] Furthermore, engine 1 is an OHV type engine, and the valve mechanism 187 includes: tappets 179 and pushrods 177, which are actuated by the intake cam and exhaust cam of the camshaft 175; and valve arms 189, which swing around a valve arm shaft 188 that is horizontally elongated and located within the cover 18 by the up-and-down movement of the pushrods 177. The upper end of the pushrods 177 protrudes into the cover 18 via a cylinder head-side pushrod chamber 190 provided in the cylinder head 2. The upper end of the pushrods 177 is connected to one end of the valve arm 189. The other end of the valve arm 189 abuts against two intake valves 136 or two exhaust valves 137 via a valve bridge 191. The configuration is as follows: the push rod 177 moves up and down due to the rotation of the camshaft 175, thereby causing each valve arm 189 to swing around the valve arm shaft 188, thereby causing the intake valve 136 group and the exhaust valve 137 group of each cylinder to open and close.

[0139] The crankcase 171 communicates with the cylinder head side pushrod chamber 190 of the cylinder head 2 via the cam chamber 176, bypass passage 183, and cylinder block side pushrod chamber 178. Leaking gas in the crankcase 171 moves towards the cylinder head 2 via the cam chamber 176, bypass passage 183, and cylinder block side pushrod chamber 178. It should be noted that the cylinder head side pushrod chamber 190, cylinder block side pushrod chamber 178, bypass passage 183, and cam chamber 176 also serve as an oil drop path for the lubricating oil in the cover 18 to return to the crankcase 171 side.

[0140] As described above, in the engine 1 of this embodiment, the tappet retainer 180 separates the cam chamber 176 from the cylinder block side pushrod chamber 178. Furthermore, a bypass passage 183, connecting the cylinder block side pushrod chamber 178 to the cam chamber 176, is formed between the tappet retainer 180 and the cylinder bore 173. This creates a zigzag leakage gas path, which includes the cam chamber 176, the bypass passage 183, and the cylinder block side pushrod chamber 178, and bypasses the tappet retainer 180. Therefore, for the engine 1, by causing the leakage gas to collide with the wall surface in this zigzag leakage gas path, it is possible to promote the adhesion of lubricating oil to the wall surface, increase the amount of lubricating oil captured in the leakage gas by combining the atomized lubricating oil with each other, and thereby reduce the amount of lubricating oil flowing from the crankcase 171 side to the cylinder head 2 side via the cam chamber 176, the bypass passage 183, and the cylinder block side pushrod chamber 178.

[0141] Next, see below, for reference Figures 27-29 The structure of the cooling water pump 21 and the cooling water inlet pipe 22 will be described, etc. Figures 27-29 As shown, a cooling water pump mounting part 319 is protruding near the rear side of the left side of the cylinder block 6, which supplies cooling water to the cooling water pump 21 (see reference). Figure 2 (etc.) installation; and inlet pipe mounting base 320, which supplies cooling water inlet pipe 22 (refer to Figure 3 (etc.) Installation. The cooling water pump mounting part 319 and the inlet pipe mounting seat 320 are integrally formed with respect to the cylinder block 6. In addition, the rear side of the inlet pipe mounting seat 320 is connected to the cooling water pump mounting part 319. The cooling water pump mounting part 319 and the inlet pipe mounting seat 320 are provided to protrude away from the crankshaft 5, thereby improving the rigidity, strength and cooling efficiency of the cylinder block 6.

[0142] The cooling water pump 21 for cooling water circulation is fastened to the rear side 312 of the cylinder block 6 and the cooling water pump mounting part 319 by means of bolts. The cooling water pump 21 is generally configured to include a base plate part 331, a cover plate part 332 and a pump pulley 333.

[0143] The base plate 331 and the cover plate 332 are configured such that cover bolts 347 are inserted from the side of the cover plate 332 and fastened to the through bolt holes provided at five locations on the periphery of the base plate 331 and the through holes of the cover plate 332 corresponding to the through bolt holes, thereby making the periphery parts tightly connected and fixed to each other.

[0144] Furthermore, the cooling water pump 21 is configured such that mounting bolts 348 are inserted into nine through holes located at the periphery of the base plate 331 and the cover plate 332, thereby securing the plates 331 and 332 to the cylinder block 6 with the bolts in a mutually tightened state. The tightening of the mounting bolts 348 ensures that the periphery of the base plate 331 and the cover plate 332 are tightly connected and fixed to each other. Additionally, the periphery of the cooling water outlet 327 of the cylinder block 6 and the periphery of the pump inlet 334 of the cooling water pump 21 are tightly connected and fixed to each other. Furthermore, the periphery of the cooling water inlet 328 of the cylinder block 6 and the periphery of the pump outlet 335 of the cooling water pump 21 are tightly connected and fixed to each other. In the arrangement of bolts 347 and 348 along the periphery of the cooling water pump 21, one or two mounting bolts 348 are positioned between adjacent cover bolts 347 and 347.

[0145] By connecting the base plate portion 331 and the cover plate portion 332 with the cover bolt 347, the cooling water pump 21 can be circulated as a single component, and the installation operation of assembling the cooling water pump 21 to the cylinder block 6 with the assembly bolt 348 becomes easier.

[0146] The base plate 331 includes: a pump inlet 334, which is connected to a cooling water flow path outlet 327 that opens in a portion near the left side of the rear side of the cylinder block 6, including, for example, a cooling water pump mounting portion 319; and a pump outlet 335, which is connected to a cooling water inlet 328 that opens in a portion near the left side of the rear side of the cylinder block 6.

[0147] The peripheral portions of the base plate 331 and the cover plate 332 are closely joined to form an internal cooling water flow path 336 connecting the pump inlet 334 and the pump outlet 335. An annular sealing member is disposed at the joint between the base plate 331 and the cover plate 332, surrounding the pump inlet 334, the pump outlet 335, and the internal cooling water flow path 336. The cover plate 332 supports the pump shaft 337, on which an impeller is fixedly mounted, allowing it to rotate freely. A pump pulley 333 is fixedly mounted at the other end of the pump shaft 337.

[0148] A cooling water inlet 329 is provided on the left side of the cylinder block 6. The cooling water inlet 329 opens into an inlet pipe mounting seat 320 protruding from the left side. Inside the cylinder block 6, an approximately L-shaped cooling water passage 338 (cooling water passage) is formed, connecting the cooling water inlet 329 opening on the left side and the cooling water outlet 327 opening on the rear side.

[0149] A pair of bolt holes are formed in the inlet pipe mounting base 320 across the cooling water flow path inlet 329, so that the cooling water inlet pipe 22 (cooling water inlet component) with cooling water inlet 339 is detachably fastened to the inlet pipe mounting base 320 by bolts. A piping communicating with the cooling water outlet of the radiator is connected to the cooling water inlet pipe 22. Cooling water from the radiator is drawn into the engine 1 through the cooling water inlet pipe 22, and introduced into the cylinder block 6 through the cooling water flow path 338 in the cylinder block and the cooling water pump 21 from the cooling water inlet 328.

[0150] In the engine 1 of this embodiment, the cooling water inlet pipe 22, which has a cooling water inlet 339, is detachably installed at the cooling water flow path inlet 329, which communicates with the pump suction port 334 of the cooling water pump 21. Therefore, the position of the cooling water inlet 339 can be changed simply by changing the shape of the cooling water inlet pipe 22. Thus, the position of the cooling water inlet 339 of the cooling water pump 21 can be changed easily without causing significant changes to the design or increasing manufacturing costs.

[0151] Furthermore, the cooling water outlet 327, which supplies cooling water from the radiator to the cooling water pump 21, and the cooling water inlet 328, which introduces cooling water from the cooling water pump 21 into the cylinder block 6, are separately positioned on the left and right sides of the cylinder block 6. Additionally, the pump-internal cooling water flow path 336, connecting the cooling water outlet 327 and the cooling water inlet 328, is positioned from near the left side of the cylinder block 6 to near the right side. With this configuration, the cooling water passing through the pump-internal cooling water flow path 336 is cooled by the cooling fan 9 (see reference 9) as it moves from the cooling water outlet 327 to the cooling water inlet 328. Figure 2 The cooling air is used for cooling. 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, thus improving the cooling efficiency of the engine 1.

[0152] It should be noted that the structure of each part of the invention is not limited to the illustrated embodiments, and various modifications can be made without departing from the spirit of the invention.

[0153] Explanation of reference numerals in the attached figures

[0154] 1 engine

[0155] 2. Cylinder head

[0156] 3. Intake manifold

[0157] 4. Exhaust manifold

[0158] 5 Crankshaft

[0159] 6 cylinder block

[0160] 7. Flywheel housing

[0161] 8 Flywheel

[0162] 9. Cooling fan

[0163] 24 EGR unit

[0164] 25 Collector (EGR Main Casing)

[0165] 26. Intake throttling component

[0166] 27 EGR Cooler

[0167] 28 Recirculating exhaust gas pipe

[0168] 29 EGR valve components

[0169] 31 Upstream EGR gas relay flow path

[0170] 32 Downstream EGR gas relay flow path

[0171] 33EGR Cooler Connection Base

[0172] 34EGR Cooler Connection Base

[0173] 35 Cooling water drain section

[0174] 36. Intake airflow path

[0175] 37 Exhaust Flow Path

[0176] 38. Downstream cooling water relay flow path

[0177] 39. Upstream side cooling water relay flow path

[0178] 40 Air Inlet

[0179] 41 EGR gas outlet

[0180] 42 Exhaust Inlet

[0181] 43 Exhaust junction

[0182] 44 Exhaust outlet

[0183] 45 Sealing gasket

[0184] 46 Padding

[0185] 47. Opening

[0186] 48 Fuel pipe

[0187] 91 Heat Exchange Section

[0188] 92 Flange portion

[0189] 93 Flange portion

[0190] 94 Cooling water outlet

[0191] 95 Cooling water inlet

[0192] 96 EGR gas inlet

[0193] 97 EGR gas outlet

[0194] 98 sealing gasket

Claims

1. An engine assembly comprising a cylinder head having an intake flow path for introducing fresh air into an intake port and an exhaust flow path for discharging exhaust gas from an exhaust port. The engine device is characterized in that... Cooling water flow paths are provided on the left and right side walls and the front and rear side walls of the cylinder head.

2. The engine device according to claim 1, characterized in that, The engine assembly includes: an exhaust manifold communicating with the exhaust flow path; and an EGR cooler for cooling EGR gas, which is part of the exhaust gas from the exhaust manifold. The EGR cooler is connected to one of the front and rear sides of the cylinder head. An EGR gas flow path and a cooling water flow path, which are connected to the EGR cooler, are provided at the location of the cylinder head where the EGR cooler is located.

3. The engine device according to claim 1 or 2, characterized in that, The cylinder head is fastened to the cylinder body by a plurality of bolts inserted through the left and right side walls and the front and rear side walls of the outer peripheral wall.

4. The engine device according to any one of claims 1 to 3, characterized in that, The intake manifold, where the intake airflow paths converge, is formed on one side of the cylinder head. The cylinder head has a cooling water drain section on the front and rear sides, and at a position adjacent to the end of the intake manifold, which communicates with the cooling water flow path provided on the outer peripheral wall.

5. The engine device according to claim 2, characterized in that, A pair of connecting bases connected to the EGR cooler are provided on one of the front and rear sides of the cylinder head. The pair of connecting bases have an EGR gas flow path and a cooling water flow path arranged vertically and passing through each other.

6. The engine device according to claim 5, characterized in that, One side of the connecting base is configured to have an EGR gas flow path above the cooling water flow path, and the other side of the connecting base is configured to have an EGR gas flow path below the cooling water flow path.

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