JP6520366B2 - Internal combustion engine supercharging system - Google Patents

Description

  The present invention relates to a supercharging system for an internal combustion engine, and more particularly to a supercharging system for an internal combustion engine that is applied to an internal combustion engine having a plurality of cylinders and includes a turbocharger having a plurality of scroll portions.

  Conventionally, as a supercharging system for an internal combustion engine, a supercharging system having a turbocharger for supercharging intake, which is applied to an internal combustion engine having an EGR path for recirculating a part of exhaust gas in an exhaust path to an intake path is known. (See, for example, Patent Document 1). The EGR passage recirculates part of the exhaust gas in the exhaust passage to the intake passage by utilizing a pressure difference between the exhaust pressure in the exhaust passage and the intake pressure in the intake passage. Thus, the combustion temperature of the internal combustion engine can be reduced to reduce NOx by recirculating a part of the exhaust gas to the intake passage.

  Also, in recent years, there has been known a supercharging system using a turbocharger having a plurality of scroll portions in order to effectively utilize exhaust pulsation by suppressing the interference of exhaust introduced into the turbocharger (for example, the aforementioned patent) Reference 1). Specifically, Patent Document 1 discloses a supercharging system using a twin scroll turbocharger having two scroll units, a first scroll unit and a second scroll unit. According to this supercharging system, the exhaust gases discharged from the first cylinder group (# 1 and # 4 cylinders) which cause no interference of exhaust pulsations are joined halfway and introduced to the first scroll portion of the turbocharger, The exhaust gases discharged from the second cylinder group (# 2 and # 3 cylinders) causing no interference of exhaust pulsations are joined halfway and introduced into the second scroll portion of the turbocharger. Thus, the interference of the exhaust introduced into the turbocharger is suppressed, and the exhaust loss is effectively used to reduce the pumping loss to improve the fuel consumption.

JP, 2011-241723, A

  In the case of the supercharging system as described above, for example, when the internal combustion engine has a high load, the supercharging amount by the turbocharger increases and the supercharging pressure becomes high, and as a result, the exhaust pressure and the intake pressure become substantially the same. It is conceivable. In this case, the amount of exhaust gas (EGR amount) that passes through the EGR passage and is recirculated to the intake passage is limited, so it becomes difficult to reduce NOx. In this regard, if it is possible to increase the pressure of the exhaust gas discharged from the cylinders, it is possible to increase the amount of exhaust gas recirculating to the intake passage, but for example, when the exhaust pressures of a plurality of cylinders are increased together The pumping loss is increased, and the fuel consumption is deteriorated. In addition, when the exhaust pressure of some of the cylinders is increased, the increase in the exhaust pressure of some of the cylinders may affect the other cylinders communicated with the cylinders by the exhaust passage.

  The present invention has been made in view of the above, and it is an object of the present invention to reduce the amount of exhaust gas returned to the intake passage without raising the exhaust pressure of a plurality of cylinders together while suppressing the influence on the other cylinders. An object of the present invention is to provide a supercharging system for an internal combustion engine that can be restrained from being limited.

The supercharging system for an internal combustion engine according to the present invention for achieving the above object is applied to an internal combustion engine having a first cylinder group and a second cylinder group respectively constituted of a plurality of cylinders without interference of exhaust pulsation. A turbocharged system having a triple scroll type turbocharger having a first scroll portion, a second scroll portion, and a third scroll portion, wherein a specific cylinder which is one of the first cylinder group and the first scroll are provided; A first exhaust passage communicating with the first cylinder group, a second exhaust passage communicating the cylinders other than the specific cylinder in the first cylinder group and the second scroll portion, the second cylinder group and the third cylinder group And a third exhaust passage communicating with the scroll portion, wherein the first exhaust passage is connected to the first scroll portion without merging halfway with the second exhaust passage and the third exhaust passage. Wherein the EGR passage way and the intake of said sucked into the internal combustion engine of the first exhaust passage connecting the middle of the intake passage passes through said plurality of cylinders other than the specific cylinder of the internal combustion engine the exhaust pressure of the specific cylinder And an exhaust pressure raising structure that raises the pressure more than the exhaust pressure of the fuel cell.

  According to the present invention, by raising the exhaust pressure of a specific cylinder (one cylinder) by the exhaust pressure raising structure, the exhaust gas whose exhaust pressure has been raised can be recirculated to the intake passage by the first exhaust passage and the EGR passage. it can. Thus, it is possible to suppress the exhaust amount flowing back to the intake passage from being restricted while suppressing the exhaust pressures of the plurality of cylinders from rising together. As a result, it is possible to effectively reduce the NOx while avoiding the limitation of the amount of exhaust gas recirculated to the intake passage while effectively suppressing the increase of the pumping loss and the fuel efficiency deterioration due to the increase. In addition, since the first exhaust passage does not join midway with the second exhaust passage and the third exhaust passage, an increase in the exhaust pressure of a specific cylinder affects other cylinders even if the exhaust pressure of the specific cylinder is increased. It has no effect.

  In the present invention, the exhaust pressure raising structure is configured such that the cross-sectional area of the inlet of the first scroll portion is smaller than the cross-sectional areas of the inlets of the second scroll portion and the third scroll portion. May be

  According to this configuration, the inlet of the first scroll portion exerts the function as a throttle to raise the exhaust pressure of the first exhaust passage connected to the inlet of the first scroll portion, thereby raising the exhaust pressure of the specific cylinder. It can be done.

  In the present invention, the cross-sectional areas of the inlets of the first scroll portion, the second scroll portion, and the third scroll portion are the same, and the exhaust pressure increase structure is characterized in that the EGR passage in the first exhaust passage is It may be constituted by an orifice or an exhaust pressure control valve which is disposed at a portion downstream of the connection point of.

  According to this configuration, the exhaust pressure on the upstream side of the orifice in the first exhaust passage or the portion where the exhaust pressure adjustment valve is disposed is increased by the orifice or the exhaust pressure adjustment valve to increase the exhaust pressure of the specific cylinder. It can be done.

It is a schematic diagram of the supercharging system of the internal combustion engine which concerns on Embodiment 1 of this invention. It is a schematic diagram of the supercharging system of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a schematic diagram of the supercharging system of the internal combustion engine which concerns on Embodiment 3 of this invention.

(Embodiment 1)
Hereinafter, a supercharging system 1 for an internal combustion engine (hereinafter referred to as a supercharging system 1) according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of the supercharging system 1 according to the first embodiment. The supercharging system 1 is mounted on a vehicle. The type of vehicle is not particularly limited, but in the present embodiment, a large vehicle such as a bus or a truck is used as an example. The supercharging system 1 includes an internal combustion engine 10, an intake passage 20 through which intake air (A) passes, an exhaust passage 30 through which exhaust gas (G) passes, and a control device 40 that controls the internal combustion engine 10. Although the type of the internal combustion engine 10 is not particularly limited, a diesel engine is used as an example in the present embodiment.

  The internal combustion engine 10 is provided with a plurality of cylinders 11, and in the present embodiment, four cylinders 11 are provided as an example. Specifically, the internal combustion engine 10 is provided with # 1 to # 4 cylinders 11 arranged in one direction. Ignition is performed in order of the cylinder 11 of # 1, the cylinder 11 of # 3, the cylinder 11 of # 4, and the cylinder 11 of # 2. In this case, the # 1 cylinder 11 and the # 3 cylinder 11 have adjacent exhaust strokes, the # 3 cylinder 11 and the # 11 cylinder 11 have adjacent exhaust strokes, and the # 4 cylinder 11 and the # 2 cylinder 11 The exhaust strokes are next to each other. On the other hand, the # 1 cylinder 11 and the # 4 cylinder 11 do not have adjacent exhaust strokes, and the # 2 cylinders 11 and the # 11 cylinder 11 do not have adjacent exhaust strokes. Therefore, the open valve periods of the exhaust valves of the # 1 cylinders 11 and # 4 cylinders do not overlap, and the open valves of the exhaust valves of the # 2 cylinders 11 and # 3 cylinders do not overlap.

  In the # 1 cylinder 11 and the # 4 cylinder 11 whose exhaust strokes are not adjacent to each other, no interference of exhaust pulsation occurs even when the exhaust gases discharged from these cylinders 11 are merged. Similarly, the # 2 cylinder 11 and the # 3 cylinder 11 whose exhaust strokes are not adjacent to each other do not cause interference of exhaust pulsation even when the exhaust gases discharged from these cylinders 11 are merged. In the present embodiment, the # 1 cylinders 11 and # 4 cylinders 11 where no exhaust pulsation interference occurs are referred to as the first cylinder group, and the # 2 cylinders 11 and # 3 cylinders 11 where no exhaust pulsation interference occurs. Is referred to as a second cylinder group.

  As another example, for example, in the case where the internal combustion engine 10 has a total of six cylinders 11 of # 1 to # 6, for example, # 1, # 2 as the first cylinder group in which the interference of one exhaust pulse does not occur. And # 3 cylinders 11 can be used, and the # 11, # 5, and # 6 cylinders 11 can be used as the second cylinder group in which the other exhaust pulsation interference does not occur.

  The downstream end of the intake passage 20 is an intake manifold 21, and the downstream end of the intake manifold 21 is branched and connected to each cylinder 11. Details of the exhaust passage 30 will be described later.

  The control device 40 is an electronic control unit (Electric Control Unit) including a microcomputer having a CPU, a ROM, a RAM, and the like, and controls the fuel injection timing of the internal combustion engine 10, the fuel injection amount, and the like. Integrately control the driving condition. The control device 40 according to the present embodiment also controls the operation of a throttle valve 80 and an EGR valve 91 described later.

  The supercharging system 1 also includes an air cleaner 50, a turbocharger 60, a charge air cooler (CAC) 70, and a throttle valve 80. The air cleaner 50, a compressor 62, which will be described later, of the turbocharger 60, the CAC 70, and the throttle valve 80 are disposed in the intake passage 20 sequentially from the upstream side. The intake air (air) sucked into the intake passage 20 passes through the air cleaner 50 to remove impurities. Then, the intake air is supercharged by the compressor 62, cooled in the CAC 70, and the flow rate is adjusted by the throttle valve 80 to flow into each cylinder 11. The details of the turbocharger 60 will be described later.

  The supercharging system 1 also includes an EGR (Exhaust Gas Recirculation) system for recirculating a part of the exhaust gas of the exhaust passage 30 to the intake passage 20. The EGR system according to the present embodiment includes an EGR passage 90, an EGR valve 91, and an EGR cooler 92. The EGR passage 90 connects the middle of the exhaust passage portion 31 d (described later) of the exhaust passage 30 and the portion of the intake passage 20 between the throttle valve 80 and the intake manifold 21. Is returned to the intake passage 20. Hereinafter, the exhaust gas passing through the EGR passage 90 is referred to as EGR gas. The EGR valve 91 is disposed in the EGR passage 90, and receives an instruction from the control device 40 to adjust the flow rate of the EGR gas. The EGR cooler 92 is disposed in the EGR passage 90 and cools the EGR gas.

  The supercharging system 1 also includes an EAT (Exhaust after-treatment) 100 that purifies the exhaust of the exhaust passage 30. The EAT 100 is disposed in the middle of the exhaust passage portion 31 e described later of the exhaust passage 30. The exhaust gas having passed through the turbine 61 is purified by passing through the EAT 100 and discharged to the outside.

  The turbocharger 60 is a device for supercharging intake air taken into the internal combustion engine 10. The turbocharger 60 has a turbine 61, a compressor 62, a connecting shaft 63 connecting the turbine 61 and the compressor 62, a turbine housing 64 accommodating the turbine 61, and a compressor housing 65 accommodating the compressor 62. There is. The turbine 61 is disposed in the exhaust passage 30, and rotates by receiving energy of the exhaust. The rotation of the turbine 61 rotates the compressor 62 connected to the turbine 61 to supercharge the intake air of the intake passage 20.

  Further, the turbine housing 64 includes three scrolls, specifically, a first scroll 66, a second scroll 67, and a third scroll 68, as scroll passages through which the exhaust gas supplied to the turbine 61 passes. There is. That is, the turbocharger 60 is a triple scroll turbocharger.

  The exhaust passage 30 includes an exhaust passage portion 31 e located downstream of the turbine housing 64 and exhaust passage portions 31 a to 31 d located upstream of the turbine housing 64. The exhaust passage portion 31 a communicates the cylinder 11 of # 1 with the inlet (the inlet of the exhaust) of the second scroll portion 67 of the turbine 61. The exhaust passage portion 31 b communicates the cylinder 11 of # 2 with the inlet of the third scroll portion 68. The exhaust passage portion 31 c communicates the # 3 cylinder 11 with the inlet of the third scroll portion 68. The exhaust passage portion 31 d communicates the cylinder 11 of # 4 with the inlet of the first scroll portion 66. In the present embodiment, the exhaust passage portion 31 b and the exhaust passage portion 31 c join midway along the downstream side to become one passage and are connected to the inlet of the third scroll portion 68. In addition, the exhaust passage 31a is connected to the inlet of the second scroll 67 without joining halfway with the other exhaust passage, and the exhaust passage 31d does not join halfway with the other exhaust passage. It is connected to the entrance of section 66.

  That is, the exhaust passage portion 31d according to the present embodiment includes the # 11 cylinder 11 (which corresponds to a specific cylinder) which is one cylinder 11 of the first cylinder group (# 1 and # 4) and the first scroll portion. The exhaust passage portion 31a corresponds to a first exhaust passage communicating with the valve 66, and a second exhaust passage communicating a cylinder other than the specific cylinder in the first cylinder group (the first cylinder 11) and the second scroll portion 67. The exhaust passage portion 31 b and the exhaust passage portion 31 c correspond to a passage, and correspond to a third exhaust passage communicating the second cylinder group (# 2 and # 3) with the third scroll portion 68. Then, the exhaust passage portion 31d as the first exhaust passage does not merge with the exhaust passage portion 31a as the second exhaust passage and the exhaust passage portions 31b and 31c as the third exhaust passage, without being joined to the first scroll portion 66. Connected Further, the EGR passage 90 connects the middle of the exhaust passage portion 31 d as the first exhaust passage and the middle of the intake passage 20.

Referring to FIG. 1, supercharging system 1 further includes an exhaust pressure raising structure 110. The exhaust pressure raising structure 110 sets the exhaust pressure of the # 4 cylinder 11 which is a specific cylinder higher than the exhaust pressure of a plurality of cylinders 11 (# 1, # 2, # 3 cylinders 11) other than the specific cylinder of the internal combustion engine 10. It is a structure to raise. Note that, when raising the exhaust pressure of the # 4 cylinder 11, the exhaust pressure increase structure 110 sets the maximum value of the exhaust pressure of the # 4 cylinder 11 to the maximum value of the exhaust pressure of each of the # 1 to # 3 cylinders. It may be higher, the average value of the exhaust pressure of the # 4 cylinder 11 may be higher than the average value of the exhaust pressure of each of the # 1 to # 3 cylinders, or the same timing of the exhaust stroke The exhaust pressure of the # 4 cylinder 11 may be made higher than the exhaust pressure of each of the # 1 to # 3 cylinders 11 in comparison.

The exhaust pressure raising structure 110 according to the present embodiment has a structure in which the cross sectional area (mm ² ) of the inlet of the first scroll 66 is smaller than the cross sectional area of the inlet of each of the second scroll 67 and the third scroll 68. It is configured. In this case, the exhaust pressure of the exhaust passage 31d connected to the inlet of the first scroll portion 66 can be increased by the inlet of the first scroll portion 66 exerting a function as a throttle, whereby # 4 The exhaust pressure of the cylinder 11 can be made higher than the exhaust pressure of the plurality of other cylinders 11.

  In the present embodiment, the cross-sectional area of the inlet of the second scroll portion 67 and the cross-sectional area of the inlet of the third scroll portion 68 are the same. However, in the configuration of the present embodiment, the cross-sectional area of the inlet of the first scroll 66 may be set smaller than the cross-sectional area of the inlet of each of the second scroll 67 and the third scroll 68. The cross-sectional area of the inlet of the scroll portion 67 may not be the same as the cross-sectional area of the inlet of the third scroll portion 68.

  According to the present embodiment described above, the exhaust pressure is increased by increasing the exhaust pressure of the # 4 cylinder 11 (that is, one cylinder 11) which is a specific cylinder by the exhaust pressure raising structure 110. The exhaust passage portion 31 d and the EGR passage 90 can return to the intake passage 20. Thus, it is possible to suppress the exhaust amount flowing back to the intake passage 20 from being restricted while suppressing the exhaust pressures of the plurality of cylinders 11 from rising together. As a result, while effectively suppressing the increase in pumping loss and the fuel efficiency deterioration due to this, it is possible to suppress the limitation of the amount of exhaust gas (the amount of EGR gas) recirculated to the intake passage 20 to effectively reduce NOx. be able to.

  Further, since the exhaust passage portion 31d does not join midway with the other exhaust passage portions 31a, 31b, 31c, even if the exhaust pressure of the # 4 cylinder 11 is increased, the exhaust pressure of the # 4 cylinder 11 is It is possible to suppress that the rise affects the other cylinders 11. That is, according to the present embodiment, it is possible to suppress the restriction of the amount of exhaust gas recirculated to the intake passage 20 without increasing the exhaust pressure of the plurality of cylinders 11 while suppressing the influence on the other cylinders 11. Can.

  According to the present embodiment, the exhaust pressure in the exhaust passage 31d can be increased without separately providing the exhaust passage 31d with an exhaust pressure raising member such as an orifice or an exhaust pressure adjusting valve. Damping of the power of the exhaust of the portion 31d by these exhaust pressure raising members is suppressed. That is, according to the present embodiment, the motive power of the exhaust of the exhaust passage portion 31 d can be introduced to the turbocharger 60 as it is. Thereby, the supercharging efficiency of the turbocharger 60 can be improved.

  In the present embodiment, the # 11 cylinder 11 is used as the specific cylinder, but the invention is not limited to this. Any one cylinder 11 of the # 1 to # 4 cylinders 11 may be used as the specific cylinder. It may be used. For example, when the # 1 cylinder 11 is used as the specific cylinder, the exhaust passage 31a is connected to the first scroll 66, the exhaust passage 31d is connected to the second scroll 67, and the EGR passage is The reference numeral 90 is connected to the exhaust passage 31a.

Second Embodiment
FIG. 2 is a schematic view of a supercharging system 1a according to a second embodiment of the present invention. Supercharged system 1a
1 mainly includes a turbocharger 60a instead of the turbocharger 60 and an exhaust pressure rise structure 110a by an orifice (aperture) 111 instead of the exhaust pressure rise structure 110, mainly in FIG. It differs from the supercharging system 1 shown.

  The turbocharger 60 a includes a turbine housing 64 a in place of the turbine housing 64. The turbine housing 64a differs from the turbine housing 64 of FIG. 1 in that the cross sectional area of the inlet of the first scroll 66a is the same as the cross sectional area of the inlet of each of the second scroll 67 and the third scroll 68. There is. That is, the cross-sectional areas of the inlets of the first scroll 66a, the second scroll 67, and the third scroll 68 according to the present embodiment are the same.

  The exhaust pressure raising structure 110a is configured as shown in FIG. 1 in that the exhaust pressure raising structure 110a is constituted by an orifice 111 disposed downstream of the connection point (point C) of the EGR passage 90 in the exhaust passage 31d as the first exhaust passage. This is different from the exhaust pressure raising structure 110 shown in FIG. The other configuration of the supercharging system 1a is the same as that of the supercharging system 1, and thus the description thereof is omitted.

  Also in the present embodiment, the exhaust pressure on the upstream side of the portion where the orifice 111 of the exhaust passage 31d is disposed can be increased by the orifice 111, whereby the exhaust pressure of the # 4 cylinder 11 is increased. be able to. Thus, it is possible to suppress the exhaust amount flowing back to the intake passage 20 from being restricted while suppressing the exhaust pressures of the plurality of cylinders 11 from rising together. As a result, it is possible to effectively reduce the NOx while effectively suppressing the deterioration of the fuel efficiency.

  Further, according to the present embodiment, the exhaust pressures of the plurality of cylinders 11 are both equal in that the cross-sectional areas of the inlets of the first scroll portion 66, the second scroll portion 67, and the third scroll portion 68 are the same. The rise is effectively suppressed.

  Further, since the exhaust passage portion 31d does not join midway with the other exhaust passage portions 31a, 31b, 31c, even if the exhaust pressure of the # 4 cylinder 11 is increased, the exhaust pressure of the # 4 cylinder 11 is The influence of the rise on the other cylinders 11 is suppressed. That is, also in the present embodiment, it is possible to suppress the restriction of the exhaust amount flowing back to the intake passage 20 without increasing the exhaust pressure of the plurality of cylinders 11 while suppressing the influence on the other cylinders 11. it can.

  In the present embodiment, as in the case of the first embodiment, the cylinders 11 other than the cylinder 11 of # 4 may be used as the specific cylinders. For example, when the # 1 cylinder 11 is used as a specific cylinder, the orifice 111 is disposed in the exhaust passage 31a, and the EGR passage 90 is connected to the exhaust passage 31a.

(Embodiment 3)
FIG. 3 is a schematic view of a supercharging system 1b according to a third embodiment of the present invention. The supercharging system 1b differs from the supercharging system 1a according to the second embodiment mainly shown in FIG. 2 in that the supercharging system 1b is provided with an exhaust pressure raising structure 110b by an exhaust pressure adjusting valve 112 instead of the exhaust pressure raising structure 110a. There is. The other configuration of the supercharging system 1b is the same as that of the supercharging system 1a, and thus the description thereof is omitted.

  The exhaust pressure raising structure 110b is configured by the exhaust pressure adjusting valve 112 disposed downstream of the connection point (point C) of the EGR passage 90 in the exhaust passage portion 31d as the first exhaust passage. This is different from the exhaust pressure raising structure 110a shown in FIG. The exhaust pressure adjustment valve 112 is controlled by the control device 40 to raise the exhaust pressure of the portion on the upstream side of the exhaust pressure adjustment valve 112 of the exhaust passage 31 d.

  Specifically, the exhaust pressure adjustment valve 112 according to the present embodiment receives a command from the control device 40, and the valve closing amount is determined according to the EGR gas amount required for the internal combustion engine 10 (referred to as the required EGR gas amount). By increasing the pressure, the exhaust pressure of the exhaust passage 31 d is increased according to the required EGR gas amount. More specifically, the exhaust pressure adjustment valve 112 receives an instruction from the control device 40 and increases the valve closing amount as the required EGR gas amount increases, and the exhaust pressure of the exhaust passage 31d increases as the required EGR gas amount increases. Raise the air pressure. Thus, the amount of exhaust gas (the amount of EGR gas) recirculated to the intake passage 20 can be increased according to the required amount of EGR gas. The control device 40 acquires the required EGR gas amount based on the load of the internal combustion engine 10 (specifically, the fresh air amount or the like).

  Also in the present embodiment, the exhaust pressure control valve 112 can increase the exhaust pressure on the upstream side of the portion where the exhaust pressure control valve 112 of the exhaust passage portion 31 d is disposed. Exhaust pressure can be increased. Thus, it is possible to suppress the exhaust amount flowing back to the intake passage 20 from being restricted while suppressing the exhaust pressures of the plurality of cylinders 11 from rising together. As a result, it is possible to effectively reduce the NOx while effectively suppressing the deterioration of the fuel efficiency.

  Further, since the exhaust passage portion 31d does not join midway with the other exhaust passage portions 31a, 31b, 31c, even if the exhaust pressure of the # 4 cylinder 11 is increased, the exhaust pressure of the # 4 cylinder 11 is The influence of the rise on the other cylinders 11 is suppressed. That is, also in the present embodiment, it is possible to suppress the restriction of the exhaust amount flowing back to the intake passage 20 without increasing the exhaust pressure of the plurality of cylinders 11 while suppressing the influence on the other cylinders 11. it can.

  Further, according to the supercharging system 1b, since the exhaust pressure of the exhaust passage 31d can be increased according to the required EGR gas amount, the excess exhaust pressure increase can be effectively suppressed to effectively deteriorate the fuel efficiency. It can be suppressed.

  In the present embodiment, as in the second embodiment, the cylinders 11 other than the cylinder 11 of # 4 may be used as the specific cylinders. For example, when the # 1 cylinder 11 is used as a specific cylinder, the exhaust pressure adjustment valve 112 is disposed in the exhaust passage 31a, and the EGR passage 90 is connected to the exhaust passage 31a.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various changes and modifications may be made within the scope of the present invention as set forth in the claims. Is possible.

1, 1a, 1b Internal combustion engine supercharging system 10 Internal combustion engine 11 cylinder 20 intake passage 31a exhaust passage (second exhaust passage)
31b, 31c exhaust passage (third exhaust passage)
31d Exhaust passage (first exhaust passage)
60, 60a Turbocharger 66, 66a 1st scroll part 67 2nd scroll part 68 3rd scroll part 90 EGR passage 110, 110a, 110b Exhaust pressure rise structure 111 Orifice 112 Exhaust pressure control valve

Claims (3)

A triple scroll having a first scroll portion, a second scroll portion, and a third scroll portion, which is applied to an internal combustion engine having a first cylinder group and a second cylinder group respectively configured by a plurality of cylinders not causing interference of exhaust pulsations In a supercharging system with a turbo charger of the
A first exhaust passage communicating a specific cylinder, which is one of the first cylinder group, with the first scroll portion, a cylinder other than the specific cylinder in the first cylinder group, and the second scroll A second exhaust passage communicating with the engine unit, and a third exhaust passage communicating the second cylinder group and the third scroll unit,
The first exhaust passage is connected to the first scroll portion without merging halfway with the second exhaust passage and the third exhaust passage.
An EGR passage connecting a middle of the first exhaust passage and a middle of an intake passage through which the intake air taken into the internal combustion engine passes ;
An exhaust pressure increase structure for raising the exhaust pressure of the specific cylinder higher than the exhaust pressure of a plurality of cylinders other than the specific cylinder of the internal combustion engine.   The exhaust pressure raising structure according to claim 1, wherein a cross-sectional area of an inlet of the first scroll portion is smaller than a cross-sectional area of an inlet of each of the second scroll portion and the third scroll portion. Internal combustion engine supercharging system. The cross-sectional areas of the respective inlets of the first scroll unit, the second scroll unit, and the third scroll unit are the same.
The supercharging of the internal combustion engine according to claim 1, wherein the exhaust pressure raising structure is constituted by an orifice or an exhaust pressure control valve disposed at a portion downstream of the connection point of the EGR passage in the first exhaust passage. system.

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