Internal combustion engine

Abstract

Provided is an internal combustion engine that is advantageous in terms of improving exhaust purification performance by means of an exhaust purification device.　An internal combustion engine (10) comprises: a first supercharger (28) connected to an exhaust passage of the internal combustion engine (10); a second supercharger (30) connected to the first supercharger (28) and disposed side by side with the first supercharger (28); and an exhaust purification device (20) connected to the second supercharger (30) and extending from the second supercharger (30) side to the first supercharger (28) side. The exhaust purification device (20) is disposed adjacent to the first supercharger (28) and the second supercharger (30). High-temperature exhaust discharged from an engine body (12) flows through the first supercharger (28), the second supercharger (30), and the exhaust purification device (20) in a path that makes a U-turn. Since the heat of the exhaust is gradually removed as the exhaust passes through the first supercharger (28), the second supercharger (30), and the exhaust purification device (20), the temperature of the exhaust gradually decreases in the order of the first supercharger (28), the second supercharger (30), and the upstream side and downstream side of the exhaust purification device (20).

Description

internal combustion engine

[0001] The present invention relates to an internal combustion engine using two superchargers in combination.

[0002] An internal combustion engine known as a two-stage turbo engine is provided with two turbochargers with different capacities (see Patent Document 1). This internal combustion engine includes a first turbocharger located upstream of an exhaust passage and a second turbocharger located downstream of the first turbocharger and having a larger capacity than the first turbocharger. The first turbocharger, which has a smaller capacity, efficiently supercharges the engine in the low to medium rotational speed range, while the second turbocharger, which has a larger capacity, efficiently supercharges the engine in the medium to high rotational speed range. An exhaust purification device is also provided downstream of the second turbocharger in the exhaust passage. The exhaust purification device includes an oxidation catalyst (DOC) or a three-way catalyst (TWC) that purifies exhaust gas, and a particulate filter located downstream of the catalyst that captures particulates in the exhaust gas. Because catalysts perform best when their temperature reaches their activation temperature, it is preferable for their temperature to be maintained at a relatively high level. Furthermore, since the particulate filter is regenerated by burning the trapped particulates, it is preferable that the temperature of the particulate filter be maintained at a relatively high temperature. Thus, maintaining the temperature of the exhaust gas purification device at a relatively high temperature is important in order to ensure the purification performance of the exhaust gas.

[0003] JP 2017-180154 A

[0004] On the other hand, since high-temperature exhaust gas flows through the first turbocharger and the second turbocharger, the first turbocharger and the second turbocharger become hot, and heat radiated from the first turbocharger and the second turbocharger is transferred to the surroundings. Therefore, it is conceivable to use this transferred heat to heat the exhaust purification device and improve the exhaust purification performance of the exhaust purification device. However, in the technology of the above-mentioned Patent Document 1, the second turbocharger is disposed below the first turbocharger, and the exhaust purification device is disposed at a location further below and away from the second turbocharger, so that heat from the first turbocharger and the second turbocharger is not easily transferred to the exhaust purification device. The present invention has been made in consideration of such circumstances, and its object is to provide an internal combustion engine that is advantageous in improving the exhaust purification performance of the exhaust purification device by using the heat from the first turbocharger and the second turbocharger to heat the exhaust purification device.

[0005] To achieve the above object, one embodiment of the present invention is characterized in that it includes a first turbocharger connected to an exhaust passage of an internal combustion engine, a second turbocharger connected to the first turbocharger and arranged side by side with the first turbocharger, and an exhaust purification device connected to the second turbocharger and extending from the second turbocharger side to the first turbocharger side, wherein the exhaust purification device is arranged adjacent to the first turbocharger and the second turbocharger. Another embodiment of the present invention is characterized in that the exhaust purification device includes a catalyst that purifies exhaust gases and a particulate filter that is arranged downstream of the catalyst and traps particulates in the exhaust gas, wherein the catalyst is adjacent to the second turbocharger and the particulate filter is adjacent to the first turbocharger. Another embodiment of the present invention is characterized in that the exhaust purification device extends in a vertical direction laterally of an engine body in a vehicle width direction, and the first turbocharger and the second turbocharger are arranged side by side vertically in front of the exhaust purification device. In one embodiment of the present invention, an intercooler that cools intake air is provided in front of the first turbocharger, the exhaust gas purification device extends below the first turbocharger, and a portion of the exhaust gas purification device located below the first turbocharger overlaps with the intercooler in the vehicle front-rear direction. In another embodiment of the present invention, the second turbocharger is used in the higher rotation range than the first turbocharger, and the second turbocharger does not overlap with the intercooler in the vehicle front-rear direction.

[0006] According to one embodiment of the present invention, an engine includes a first turbocharger, a second turbocharger connected to the first turbocharger and arranged side by side with the first turbocharger, and an exhaust gas purification device connected to the second turbocharger and extending from the second turbocharger side to the first turbocharger side, wherein the exhaust gas purification device is arranged adjacent to the first turbocharger and the second turbocharger. Therefore, high-temperature exhaust gas discharged from the engine body flows through a path that makes a U-turn through the first turbocharger, the second turbocharger, and the exhaust gas purification device, and the entire exhaust gas purification device is heated by the first turbocharger and the second turbocharger, which is advantageous in suppressing a temperature drop in the exhaust gas purification device and in suppressing a temperature drop in the catalyst and improving the exhaust gas purification performance of the exhaust gas purification device. Furthermore, when the exhaust gas purification device comprises a catalyst and a particulate filter arranged downstream of the catalyst, the catalyst being adjacent to the second turbocharger, and the particulate filter being adjacent to the first turbocharger, heat from the second turbocharger is transferred to the catalyst, thereby efficiently heating the catalyst, which is advantageous for improving exhaust gas purification performance, and heat from the first turbocharger, which has a higher temperature than the second turbocharger, is transferred to the particulate filter, thereby heating the particulate filter, and a temperature drop in the particulate filter can be suppressed, which is also advantageous for efficiently performing regeneration processing of the particulate filter. Furthermore, if the exhaust purification device extends in the vertical direction laterally of the engine body in the vehicle width direction, and the first turbocharger and the second turbocharger are arranged vertically in front of the exhaust purification device, the first turbocharger and the second turbocharger block the traveling wind, thereby preventing the traveling wind from directly hitting the exhaust purification device, which is advantageous for preventing a temperature drop in the exhaust purification device due to the traveling wind and is more advantageous for improving the exhaust purification performance of the exhaust purification device. Furthermore, if an intercooler that cools the intake air is provided in front of the first turbocharger, the exhaust purification device extends below the first turbocharger, and the portion of the exhaust purification device below the first turbocharger overlaps with the intercooler in the vehicle fore-and-aft direction, this is advantageous for preventing the first turbocharger from being excessively cooled by the traveling wind that has increased in temperature by passing through the intercooler and hitting it, which is more advantageous for preventing a temperature drop in the exhaust purification device and improving the exhaust purification performance of the exhaust purification device.Furthermore, if the second supercharger, which is used in a higher rotation range than the first supercharger, is arranged so as not to overlap with the intercooler in the vehicle longitudinal direction, the traveling wind will hit the second supercharger directly without passing through the intercooler, and the second supercharger will be efficiently cooled by the traveling wind. Therefore, it is possible to suppress the rise in temperature of the intake air pressure-fed from the second supercharger to the engine body, which is advantageous in improving the charging efficiency of the internal combustion engine and increasing the output of the internal combustion engine.

[0007] It is a side view of the internal combustion device according to the embodiment as seen from the vehicle width direction, a plan view of the internal combustion device according to the embodiment as seen from above, and a front view of the internal combustion device according to the embodiment as seen from the front of the vehicle.

[0008] Next, an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the symbol FR indicates the front of the vehicle, the symbol RH indicates the width direction of the vehicle, and the symbol UP indicates the top of the vehicle. In this embodiment, the internal combustion engine is a diesel engine that uses light oil as fuel, but the present invention is of course also applicable to a gasoline engine that uses gasoline as fuel.

[0009] 1 to 3, the internal combustion engine 10 includes an engine body 12, an air cleaner 14, an intercooler 16, a supercharger 18, an exhaust purification device 20, and an engine ECU (not shown) that controls the engine body 12 and the supercharger 18. In this embodiment, the internal combustion engine 10 is disposed in a space in front of the vehicle in front of the dash panel. As shown in Figures 1 and 3, the engine body 12 includes a cylinder head 1202 and a cylinder block 1204 connected to a lower part of the cylinder head 1202. A valve mechanism 1206 that operates intake valves and exhaust valves is provided above the cylinder head 1202.

[0010] As shown in Fig. 2, an intake manifold 22 that supplies intake air to each cylinder chamber is connected to a side wall of the cylinder head 1202 facing one side in the vehicle width direction. An exhaust manifold 24 that discharges exhaust gas from each cylinder chamber is connected to a side wall of the cylinder head 1202 facing the other side in the vehicle width direction. As shown in Fig. 1, a downstream end 2402 of the exhaust manifold 24 is connected to a first turbine housing 28A of a first supercharger 28 of the supercharger 18, which will be described later. As shown in Fig. 1, the air cleaner 14 removes dust from the intake air and is connected via a first intake pipe 26A to a second compressor housing 30B of a second supercharger 30 of the supercharger 18, which will be described later. The intercooler 16 uses a refrigerant to cool the intake air that has been heated by being compressed in the first supercharger 28 and the second supercharger 30. The refrigerant, which has absorbed heat from the intake air and whose temperature has increased, is cooled by the airflow passing through the intercooler 16. As shown in Fig. 2, the intake air inlet of the intercooler 16 is connected to a first compressor housing 28B of the first supercharger 28 via a second intake pipe 26B, and the intake air outlet of the intercooler 16 is connected to the upstream end of the intake manifold 22 via a third intake pipe 26C. As shown in Figs. 1, 2, and 3, the intercooler 16 has a horizontally long rectangular plate shape and is provided in front of the first supercharger 28 with its longitudinal direction facing the vehicle width direction and its thickness direction facing the vehicle front-rear direction. As shown in Fig. 3, the intercooler 16 and the first supercharger 28 overlap in the vehicle front-rear direction. On the other hand, the intercooler 16 and the second supercharger 30 do not overlap in the vehicle front-rear direction, and the second supercharger 30 protrudes above the intercooler 16. In other words, when viewed from the front, the first supercharger 28 is located within the outline of the intercooler 16, while the second supercharger 30 is located outside the outline of the intercooler 16.

[0011] The supercharger 18 is a two-stage turbocharger and includes a first supercharger 28 and a second supercharger 30 connected to the first supercharger 28 and having a larger capacity than the first supercharger 28. The first supercharger 28 is mainly used in the low vehicle speed range, and the second supercharger 30 is mainly used in the high vehicle speed range. As shown in FIGS. 1, 2, and 3, in this embodiment, the supercharger 18 is provided close to one side wall of the engine body 12 in the vehicle width direction. As shown in FIG. 3, the first supercharger 28 is disposed to the side of the cylinder head 1202, and the second supercharger 30 is disposed above the first supercharger 28 and to the side of the valve train 1206. Therefore, the second supercharger 30 is disposed vertically adjacent to the first supercharger 28. Here, the direction in which the rotation shaft of the turbocharger extends is called the axial direction of the turbocharger. In this embodiment, the first turbocharger 28 and the second turbocharger 30 are arranged with their axial directions pointing approximately in the fore-and-aft direction of the vehicle and their axial directions being approximately parallel to each other.

[0012] As shown in FIG. 1 , the first supercharger 28 includes a first turbine wheel (not shown), a first turbine housing 28A, a first compressor wheel (not shown), a first compressor housing 28B, a first rotating shaft (not shown), and a first bearing housing 28C. The first turbine housing 28A is connected to a downstream end 2402 of the exhaust manifold 24 that constitutes the exhaust passage and houses the first turbine wheel. As shown in FIGS. 1 , 2 , and 3 , the first compressor housing 28B is connected to the intake manifold 22 via a second intake pipe 26B and the intercooler 16 and houses the first compressor wheel. Note that in FIG. 2 , the first compressor housing 28B and a second compressor housing 30B (described later) are depicted overlapping, and the first turbine housing 28A and a second turbine housing 30A (described later) are depicted overlapping. 3, the first turbine housing 28A and the first compressor housing 28B are illustrated overlapping each other, and the second turbine housing 30A and the second compressor housing 30B are illustrated overlapping each other. The first bearing housing 28C connects the first turbine housing 28A and the first compressor housing 28B, and the first turbine wheel and the first compressor wheel are connected by a first rotating shaft, which is supported by the first bearing housing 28C via a bearing. Therefore, the first turbine wheel is driven to rotate by exhaust gas discharged from the exhaust manifold 24, which in turn drives the first compressor wheel to rotate via the first rotating shaft. As a result, intake air supplied from the second compressor housing 30B via an intake-side connecting passage 34 (described later) is pressure-fed to the intake manifold 22 via the second intake pipe 26B and the intercooler 16.

[0013] As shown in FIG. 1 , the second turbocharger 30 includes a second turbine wheel (not shown), a second turbine housing 30A, a second compressor wheel (not shown), a second compressor housing 30B, a second rotating shaft (not shown), and a second bearing housing 30C. The second turbine housing 30A is connected to the first turbine housing 28A via an exhaust-side connecting passage 32 and houses the second turbine wheel. The second compressor housing 30B is connected to the air cleaner 14 via a first intake pipe 26A and to the first compressor housing 28B via an intake-side connecting passage 34 and houses the second compressor wheel. The second bearing housing 30C connects the second turbine housing 30A and the second compressor housing 30B. The second turbine wheel and the second compressor wheel are connected by a second rotating shaft, and the second bearing housing 30C supports the second rotating shaft via a bearing. Therefore, the second turbine wheel is rotated by the exhaust gas supplied from the first turbine housing 28A through the exhaust side connection passage 32, which in turn rotates the second compressor wheel via the second rotating shaft, thereby causing the intake air introduced from the air cleaner 14 through the first intake pipe 26A to be pressurized from the second compressor housing 30B to the first compressor housing 28B via the intake side connection passage 34.

[0014] 1 , the turbocharger 18 is further provided with an exhaust-side bypass passage 36A, an exhaust-side bypass valve 36B, an intake-side bypass passage 38A, and an intake-side bypass valve 38B. The exhaust-side bypass passage 36A connects the downstream end 2402 of the exhaust manifold 24 to the second turbine housing 30A, and distributes exhaust gas discharged from the exhaust manifold 24 to the second turbine housing 30A, bypassing the first turbine housing 28A. The exhaust-side bypass valve 36B is provided in the exhaust-side bypass passage 36A, and adjusts the flow rate of exhaust gas distributed to the second turbine housing 30A, with its opening controlled by the engine ECU. The intake-side bypass passage 38A connects the second compressor housing 30B to the second intake pipe 26B, and distributes intake air in the second compressor housing 30B to the second intake pipe 26B, bypassing the first compressor housing 28B. The intake side bypass valve 38B is provided in the intake side bypass passage 38A, and adjusts the flow rate of the intake air distributed to the second intake pipe 26B, and its opening degree is controlled by the engine ECU.

[0015] When the rotation speed of the engine body 12 is in the low to medium rotation speed range, the exhaust-side bypass valve 36B and the intake-side bypass valve 38B are controlled to close so as to reduce the flow rate of exhaust distributed from the exhaust manifold 24 to the second turbine housing 30A and the flow rate of intake air distributed from the second compressor housing 30B to the second intake pipe 26B, respectively, so that most of the supercharging operation is performed by the first supercharger 28. When the rotation speed of the engine body 12 is in the medium to high rotation speed range, the exhaust-side bypass valve 36B and the intake-side bypass valve 38B are controlled to open so as to increase the flow rate of exhaust distributed from the exhaust manifold 24 to the second turbine housing 30A and the flow rate of intake air distributed from the second compressor housing 30B to the second intake pipe 26B, respectively. In this way, in the low to medium rotation range, supercharging is efficiently performed by the small-capacity first supercharger 28, and in the medium to high rotation range, supercharging is efficiently performed by the large-capacity second supercharger 30. In other words, the first supercharger 28 and the second supercharger 30 are used appropriately depending on the rotation speed of the internal combustion engine 10. Note that the configurations of the bypass passages and bypass valves and the control of the bypass valves for switching the supercharging operation by the first supercharger 28 and the second supercharger 30 are not limited to the present embodiment, and various conventionally known configurations and controls of two-stage turbochargers can be used in the present invention.

[0016] As shown in FIG. 1 , the exhaust gas purification device 20 is disposed laterally in the vehicle width direction of the engine body 12 and rearward of the first supercharger 28 and the second supercharger 30 in the vehicle longitudinal direction. The exhaust gas purification device 20 includes a casing 40, a catalyst 42 and a particulate filter 44 housed in the casing 40. The casing 40 is elongated in the vertical direction and extends from the second supercharger 30 side to the first supercharger 28 side. The casing 40, the second turbine housing 30A of the second supercharger 30, and the first turbine housing 28A of the first supercharger 28 are disposed adjacent to each other in the vehicle longitudinal direction. In other words, the exhaust gas purification device 20, the first supercharger 28, and the second supercharger 30 are disposed in close proximity to each other. As shown in FIGS. 1 and 3 , the casing 40 of the exhaust gas purification device 20 extends downward beyond the first supercharger 28. A portion of the casing 40 of the exhaust purification device 20 located below the first turbocharger 28 overlaps with the intercooler 16 in the vehicle longitudinal direction, in other words, as shown in Fig. 3 , when viewed from the front, most of the portion of the casing 40 of the exhaust purification device 20 located below the first turbocharger 28 is located within the outline of the intercooler 16. The catalyst 42 is disposed in the upper half of the casing 40, and the particulate filter 44 is disposed in the lower half of the casing 40. Therefore, in the vehicle longitudinal direction, the catalyst 42 is disposed adjacent to the second turbine housing 30A of the second turbocharger 30, and the particulate filter 44 is disposed adjacent to the first turbine housing 28A of the first turbocharger 28.

[0017] 1, a portion of the casing 40 of the exhaust purification device 20 near the upper end is connected to the second turbine housing 30A of the second turbocharger 30 via a first exhaust pipe 46A, and a lower end of the casing 40 of the exhaust purification device 20 is connected to a second exhaust pipe 46B that is open to the atmosphere. The exhaust gas supplied to the exhaust purification device 20 from the first exhaust pipe 46A is purified by passing through a catalyst 42 inside the casing 40, and then passes through a particulate filter 44 to remove particulates, and the exhaust gas from which the particulates have been removed is discharged into the atmosphere via the second exhaust pipe 46B.

[0018] When the internal combustion engine 10 is a diesel engine as in the present embodiment, an oxidation catalyst (DOC) that purifies exhaust gas is used as the catalyst 42, and a diesel particulate filter (DPF) is used as the particulate filter 44. On the other hand, when the internal combustion engine 10 is a gasoline engine, a three-way catalyst (TWC) that purifies exhaust gas is used as the catalyst 42, and a gasoline particulate filter (GPF) is used as the particulate filter 44. The catalyst 42 and the particulate filter 44 are not limited to those in the present embodiment, and various conventionally known catalysts 42 and particulate filters 44 can be used.

[0019] Furthermore, since the catalyst 42 performs well when its temperature rises to its activation temperature, it is preferable that the catalyst 42 be maintained at a relatively high temperature so that the temperature of the catalyst 42 does not drop. Furthermore, the particulate filter 44 needs to be regenerated by burning and removing particulates that have accumulated on the particulate filter 44 so that it does not become clogged with particulates. The regeneration process is performed by a conventionally known method, such as operating the engine body 12 in a state that increases the temperature of the exhaust gas or supplying unburned gas to the catalyst 34. Therefore, in order to efficiently perform the regeneration process of the particulate filter 44, it is preferable that the temperature of the particulate filter 44 be maintained at a relatively high temperature so that it does not drop.

[0020] Next, the operation of the internal combustion engine 10 will be described. As shown in Figures 1, 2, and 3, when the engine body 12 is operating, exhaust gas discharged from the engine body 12 is supplied from the exhaust manifold 24 to the first turbine housing 28A, thereby driving the first turbine wheel to rotate, and then to the second turbine housing 30A, thereby driving the second turbine wheel to rotate, as indicated by the solid arrows in the figures. The exhaust gas is then introduced into the exhaust purification device 20 via the first exhaust pipe 46A. Meanwhile, as indicated by the dashed arrows in the figures, intake air supplied from the air cleaner 14 to the second compressor housing 30B via the first intake pipe 26A is pressurized by the second compressor wheel to the first compressor housing 28B, and then pressurized by the first compressor wheel to the intercooler 16 via the second intake pipe 26B to be cooled. The cooled intake air is then pressurized and delivered to the engine body 12 from the third intake pipe 26C via the intake manifold 22. At this time, the exhaust-side bypass valve 36B and the intake-side bypass valve 38B are each controlled according to the rotation speed of the engine body 12, and the exhaust and intake are distributed to the exhaust-side bypass passage 36A and the intake-side bypass passage 38A, respectively, thereby allowing the first supercharger 28 and the second supercharger 30 to be used appropriately, as described above.

[0021] In this embodiment, the engine is provided with a first turbocharger 28 connected to an exhaust passage of the internal combustion engine 10, a second turbocharger 30 connected to the first turbocharger 28 and arranged alongside the first turbocharger 28, and an exhaust purification device 20 connected to the second turbocharger 30 and extending from the second turbocharger 30 side to the first turbocharger 28 side, and the exhaust purification device 20 is arranged adjacent to the first turbocharger 28 and the second turbocharger 30. Therefore, as shown by the solid arrows in Fig. 1 , high-temperature exhaust gas discharged from the engine body 12 flows in a route that makes a U-turn through the first turbocharger 28, the second turbocharger 30, and the exhaust purification device 20. Since heat is gradually removed from the exhaust gas as it passes through the first turbocharger 28, the second turbocharger 30, and the exhaust gas purification device 20, the exhaust gas temperature gradually decreases in the order of the first turbocharger 28, the second turbocharger 30, and the upstream and downstream of the exhaust gas purification device 20. In this embodiment, the first turbocharger 28, which has a high exhaust gas temperature, and the downstream portion of the exhaust gas purification device 20, which has a low exhaust gas temperature, are adjacent to each other, and therefore, heat from the first turbocharger 28 is transferred to the downstream portion of the exhaust gas purification device 20, thereby heating the downstream portion of the exhaust gas purification device 20, which is likely to have a relatively low temperature, and thereby suppressing a decrease in the temperature of the downstream portion of the exhaust gas purification device 20. Furthermore, since the second turbocharger 30, which has a lower exhaust gas temperature than the first turbocharger 28, is adjacent to an upstream portion of the exhaust gas purification device 20, which has a higher exhaust gas temperature than the downstream portion of the exhaust gas purification device 20, heat from the second turbocharger 30, although lower than that of the first turbocharger 28, is transferred to the upstream portion of the exhaust gas purification device 20, heating the upstream portion of the exhaust gas purification device 20 and suppressing a drop in the temperature of the upstream portion of the exhaust gas purification device 20. Therefore, since the entire exhaust gas purification device 20 is heated by the first turbocharger 28 and the second turbocharger 30, this is advantageous in suppressing a drop in temperature of the exhaust gas purification device 20 and is advantageous in improving the exhaust gas purification performance of the exhaust gas purification device 20.

[0022] 1 , the exhaust purification device 20 includes a catalyst 42 that purifies exhaust gas, and a particulate filter 44 that is disposed downstream of the catalyst 42 and traps particulates in the exhaust gas, the catalyst 42 being adjacent to the second turbocharger 30, and the particulate filter 44 being adjacent to the first turbocharger 28. Therefore, heat from the second turbocharger 30 is transferred to the catalyst 42, thereby efficiently heating the catalyst 42, which is advantageous for improving exhaust purification performance, and since the first turbocharger 28, which has a higher temperature than the second turbocharger 30, is disposed adjacent to the particulate filter 44, heat from the first turbocharger 28 is transferred to the particulate filter 44, thereby heating the particulate filter, and a temperature drop in the particulate filter 44 can be suppressed, which is advantageous for efficiently performing regeneration processing of the particulate filter 44.

[0023] 1 , in this embodiment, the exhaust purification device 20 extends in the vertical direction laterally in the vehicle width direction of the engine body 12, and the first supercharger 28 and the second supercharger 30 are arranged side by side, one above the other, in front of the vehicle of the exhaust purification device 20. Therefore, the traveling wind is blocked by the first supercharger 28 and the second supercharger 30, and the traveling wind is prevented from directly hitting the exhaust purification device 20, which is advantageous in preventing a temperature drop in the exhaust purification device 20 due to the traveling wind and is more advantageous in improving the exhaust purification performance of the exhaust purification device 20.

[0024] 1 and 3 , in this embodiment, the intercooler 16 that cools the intake air supplied from the first turbocharger 28 is provided in front of the first turbocharger 28, the exhaust gas purification device 20 extends below the first turbocharger 28, and the portion of the exhaust gas purification device 20 located below the first turbocharger 28 overlaps with the intercooler 16 in the vehicle front-rear direction. Therefore, the portion of the exhaust gas purification device 20 located below the first turbocharger 28 is exposed to the running air that has passed through the intercooler 16. A refrigerant that cools the intake air whose temperature has been increased by being compressed by the first turbocharger 28 and the second turbocharger 30 flows through the intercooler 16, and therefore the running air that has passed through the intercooler 16 absorbs heat from the refrigerant, and the temperature of the running air is therefore higher than before passing through the intercooler 16. Therefore, the first turbocharger 28 is also hit by the running wind, whose temperature has increased by passing through the intercooler 16, which is advantageous in preventing the first turbocharger 28 from being excessively cooled, thereby preventing a drop in temperature of the exhaust purification device 20 and being more advantageous in improving the exhaust purification performance of the exhaust purification device 20.

[0025] Furthermore, in this embodiment, the second supercharger 30 is a supercharger that supercharges the engine body 12 in the medium to high rotational speed range, and is a supercharger that is used in a higher rotational speed range than the first supercharger 28. When the vehicle is running at high speed, the flow rate or heat quantity of exhaust gas discharged from the engine body 12 is greater than when the vehicle is starting or running at low speed, and therefore the second supercharger 30 is more likely to experience an excessive temperature rise. In this embodiment, the second supercharger 30 is disposed so as not to overlap with the intercooler 16 in the vehicle longitudinal direction. Therefore, the traveling wind directly hits the second supercharger 30 without passing through the intercooler 16, and the second supercharger 30 is efficiently cooled by the traveling wind. Therefore, by suppressing an excessive temperature rise in the second supercharger 30, it is possible to suppress a temperature rise in the intake air pressure-fed from the second supercharger 30 to the engine body 12, which is advantageous for improving the charging efficiency of the internal combustion engine 10 and increasing the output of the internal combustion engine 10.

[0026] In the present embodiment, the case of a longitudinally mounted front engine in which the engine body 12 is disposed at the front of the vehicle body has been described. However, depending on the case of a transversely mounted engine, a rear engine in which the engine body 12 is disposed at the rear of the vehicle body, or a midship engine in which the engine body 12 is disposed at the center of the vehicle body, the location and extension direction of the exhaust purification device 20 relative to the engine body 12 may be changed as appropriate, and the locations and arrangement directions of the first supercharger 28 and the second supercharger 30 may also be changed as appropriate. Therefore, the location and extension direction of the exhaust purification device 20 and the locations and arrangement directions of the first supercharger 28 and the second supercharger 30 are not limited to those described in the embodiment.

[0027] Furthermore, in this embodiment, the case where the first turbine housing 28A of the first supercharger 28 is connected to the cylinder head 1202 via the intake manifold 22 has been described, but the first turbine housing 28A of the first supercharger 28 only needs to be connected to the exhaust passage, and various conventionally known configurations can be used, such as the first turbine housing 28A of the first supercharger 28 being directly connected to the cylinder head 1202.

[0028] 10 Internal combustion engine 12 Engine body 1202 Cylinder head 1204 Cylinder block 1206 Valve mechanism 14 Air cleaner 16 Intercooler 18 Supercharging device 20 Exhaust purification device 22 Intake manifold 24 Exhaust manifold 2402 Downstream end 26A First intake pipe 26B Second intake pipe 26C Third intake pipe 28 First supercharger 28A First turbine housing 28B First compressor housing 28C First bearing housing 30 Second supercharger 30A Second turbine housing 30B Second compressor housing 30C Second bearing housing 32 Exhaust side connecting passage 34 Intake side connecting passage 36A Exhaust side bypass passage 36B Exhaust side bypass valve 38A Intake side bypass passage 38C Intake side bypass valve 40 Casing 42 Catalyst 44 Particulate filter 46A First exhaust pipe 46B Second exhaust pipe

Claims

1. A first supercharger connected to an exhaust passage of an internal combustion engine, a second supercharger connected to the first supercharger and arranged side by side with the first supercharger, and an exhaust purification device connected to the second supercharger and extending from the second supercharger side to the first supercharger side, wherein the exhaust purification device, the first supercharger, and the second supercharger are arranged adjacent to each other. An internal combustion engine characterized by this.

2. The exhaust purification device includes a catalyst for purifying exhaust gas and a particulate filter disposed downstream of the catalyst for collecting fine particles in the exhaust gas. The catalyst is adjacent to the second supercharger, and the particulate filter is adjacent to the first supercharger. The internal combustion engine according to claim 1, characterized by this.

3. The exhaust purification device extends in the vertical direction on the side in the vehicle width direction of the engine body, and the first supercharger and the second supercharger are arranged side by side vertically in front of the vehicle of the exhaust purification device. The internal combustion engine according to claim 1, characterized by this.

4. An intercooler for cooling intake air is provided in front of the first supercharger. The exhaust purification device extends to a position below the first supercharger. A portion of the exhaust purification device located below the first supercharger overlaps the intercooler in the vehicle longitudinal direction. The internal combustion engine according to claim 3, characterized by this.

5. The second supercharger is used in a high rotation range of the internal combustion engine compared to the first supercharger, and the second supercharger does not overlap the intercooler in the vehicle longitudinal direction. The internal combustion engine according to claim 4, characterized by this.

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