JP2008138633A - Injector mounting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injector mounting structure in which an injector is protected from scattering stones and heat and further the support stiffness of a fuel-feeding pipe is improved. <P>SOLUTION: A holding member 60 which is fitted into the injector 50 and has a holding hole 61 communicating with an exhaust pipe 12a is provided in the exhaust pipe 12a of an engine 11 in which an exhaust gas purifying catalyst or the like is interposed at a downstream of a mounting portion of the injector 50 for performing fuel injection with the fuel as an additive agent. The holding member 60 is provided with an injector cover 70 that covers a portion arranged outside the exhaust pipe 12a of the injector 50 and supports the injector 50 fitted into the holding hole 61 between the holding member 60. Then, the end 90a of a fuel-feeding pipe 90 is coupled to the injector cover 70 with a mounting bolt 91 having a groove 91a, while the fuel-feeding pipe 90 communicates with an fuel intake 51 of the injector 50 via the groove 91a of the mounting bolt 91. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injector mounting structure, and is particularly useful for protecting an injector mounted on an exhaust passage of an internal combustion engine from flying stones, heat damage, and the like.

  There is a risk of adverse effects on the environment such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) in exhaust gas discharged from engines mounted on automobiles, especially diesel engines. It contains a lot of pollutants and particulate matter (PM). For this reason, in general, for example, a three-way catalyst for decomposing (reducing, etc.) the pollutants and a particulate filter for capturing PM in an exhaust passage through which exhaust gas discharged from the engine passes. Etc., so that the exhaust gas is discharged into the atmosphere as harmless as possible.

  In such a particulate filter, since PM accumulates in the filter and the passage resistance increases with use, it is necessary to perform a regeneration process as necessary. As such regeneration processing, a heating device is provided in the particulate filter, and PM is burned and removed by heating. However, fuel (light oil) is added to the oxidation catalyst provided upstream of the particulate filter. A method is also proposed in which an exothermic reaction is caused by flowing a hydrocarbon-based liquid such as) and the particulate filter is regenerated by this heat (see, for example, Patent Document 1).

  In diesel engines, nitrogen oxides (NOx) are particularly likely to be generated. For this reason, in order to efficiently decompose NOx in exhaust gas, for example, many so-called NOx storage catalysts that decompose and reduce (reduce) NOx by repeatedly adsorbing and reducing NOx are often employed in diesel engines. ing.

  Such a NOx occlusion catalyst decomposes (reduces) adsorbed NOx, and therefore it is necessary to appropriately supply a reducing agent from the outside to the NOx occlusion catalyst. For this reason, in general, fuel (light oil) or the like is injected into the exhaust passage as a reducing agent so as to be supplied to the NOx storage catalyst. As an example, there is one in which a NOx reducing agent is injected toward a NOx storage catalyst by an injector provided in an exhaust pipe (see, for example, Patent Document 2).

  However, since the injector is provided around the exhaust pipe, there is a possibility that the injector may be damaged by the rock jumping off the road surface when the automobile travels, and various techniques for protecting the injector there have been proposed. As an example, there is one in which the injector is fixed to the exhaust pipe so as to be hidden between the exhaust pipe and an oil filter (peripheral structure) disposed around the exhaust pipe (for example, see Patent Document 3). .

JP 2002-89237 A JP-A-2005-214100 JP 2004-218596 A

  However, when protecting the injector from stepping stones or the like as described in Patent Document 3, a portion exposed to the outside of the exhaust passage of the injector still remains depending on the shape of the surrounding structure. Is difficult. Furthermore, the mounting position of the injector depends on the arrangement of the surrounding structures, and the injector may not be mounted at a location suitable for the mounting position of the NOx storage catalyst.

  Further, it is disclosed that the injector is held by a boss portion provided in the exhaust pipe. In this way, the larger the portion held by the boss portion of the injector, the better the support rigidity of the injector, but heat from the exhaust pipe is more easily transmitted to the injector, resulting in damage to the injector or resin connector. There is a possibility that the portion may be melted. Conversely, if the portion held by the boss part of the injector is made small so that heat from the exhaust pipe is difficult to be transmitted, the support rigidity of the injector will decrease, and in addition, the support rigidity of the injector will decrease, There is also a possibility that the support rigidity of the fuel supply pipe to be connected also decreases.

  In view of such circumstances, an object of the present invention is to provide an injector mounting structure that protects an injector from flying stones, heat damage, and the like, and improves the support rigidity of the injector and the fuel supply pipe.

  In order to achieve the above object, the injector mounting structure according to claim 1 is provided with a protective member that covers a portion of the injector disposed outside the exhaust passage when the injector is attached with the injection port facing the exhaust passage. In addition, the protective member is provided with a supply portion that is supplied with an additive and communicates with the additive intake port of the injector.

  In the invention of claim 1, since the injector is covered with a protective member, the injector is protected from the flying stone by the protective member, and even when the flying stone hits the protective member directly, the shock is absorbed by the buffering space, The impact of stepping stones on the injector can be suppressed.

  Further, since the additive supply path is attached to a rigid protective member, the support rigidity of the additive supply path is improved.

  The injector mounting structure according to claim 2 is the injector mounting structure according to claim 1 or 2, wherein a holding member is mounted on the injector mounting portion of the exhaust passage, and the holding member includes: A holding hole for locking the injector is provided, the protective member is fixed to the holding member, and the injector locked in the holding hole is sandwiched between the holding member and the holding member. .

  In the invention of claim 2, the support rigidity of the injector is further improved by sandwiching the injector between the holding member and the protective member.

  According to a third aspect of the present invention, there is provided the injector mounting structure according to the second aspect, wherein the holding member has a coolant flow path formed around the holding hole.

  In invention of Claim 3, the heat | fever of the waste gas which flows through an exhaust passage is absorbed, and an injector can be protected from a heat | fever.

  According to a fourth aspect of the present invention, there is provided the injector mounting structure according to the second or third aspect, wherein the protective member is provided in the vicinity of the additive intake port of the injector via a buffer space. In the buffer space, a seal member is interposed between the injector and the protective member.

  In invention of Claim 4, an additive leakage can be prevented.

  An injector mounting structure according to claim 5 is the injector mounting structure according to any one of claims 2 to 4, wherein an additive supply pipe having an additive supply path is screwed into the supply portion. The additive is fixed to the protection member by a bolt, and the additive supply pipe communicates with an additive intake port of the injector through an additive flow path formed in the mounting bolt.

  In the invention of claim 5, the additive supply path can be stably fixed to the protective member using the mounting bolt, and the additive from the additive supply path can be supplied to the injector.

  According to the present invention, since the protective member covers the injector, even when a stepping stone collides with the protective member, the impact from the stepping stone to the injector is reduced. Further, even if heat is transmitted from the exhaust pipe or the like to the protective member, the heat is hardly transmitted to the injector, and the injector can be protected from heat damage. In addition, since the protective member is provided with a supply unit that supplies the additive to the injector, the supply path of the additive can be integrated, and the mountability is improved.

  Further, according to the present invention, the injector is sandwiched between the holding member and the protective member. For this reason, by reducing the part held by the holding member of the injector as much as possible, heat from the exhaust pipe or the like is hardly transmitted to the injector, and sufficient support rigidity of the injector can be ensured. Furthermore, since the fuel supply path for supplying fuel to the injector is attached to the supply part of such a protective member, the support rigidity is improved as compared with the case where it is directly attached to the injector.

  Prior to describing an injector mounting structure according to an embodiment of the present invention, an example of an exhaust gas purification apparatus for an internal combustion engine including an exhaust passage to which the injector is mounted will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an exhaust emission control device according to the present embodiment. As shown in FIG. 1, the exhaust purification device 10 has a plurality of exhaust purification catalysts and exhaust purification filters, and the plurality of exhaust purification catalysts and exhaust purification filters are installed in a vehicle. An exhaust pipe (exhaust passage) 12 of a cylinder diesel engine (hereinafter simply referred to as an engine) 11 is interposed.

  The engine 11 includes a cylinder head 13 and a cylinder block 14, and a piston 16 is accommodated in each cylinder bore 15 of the cylinder block 14 so as to be reciprocally movable. A combustion chamber 17 is formed by the piston 16, the cylinder bore 15, and the cylinder head 13. The piston 16 is connected to a crankshaft 19 via a connecting rod 18 so that the crankshaft 19 is rotated by the reciprocating motion of the piston 16.

  An intake port 20 is formed in the cylinder head 13, and an intake pipe (intake passage) 22 including an intake manifold 21 is connected to the intake port 20. The intake port 20 is provided with an intake valve 23, and the intake port 20 is opened and closed by the intake valve 23. An exhaust port 24 is formed in the cylinder head 13, and an exhaust pipe (exhaust passage) 12 including an exhaust manifold 25 is connected to the exhaust port 24. The exhaust port 24 is provided with an exhaust valve 26. Like the intake port 20, the exhaust port 24 is opened and closed by the exhaust valve 26. A turbocharger 27 is provided in the middle of the intake pipe 22 and the exhaust pipe 12, and an exhaust purification catalyst and an exhaust purification catalyst that constitute the exhaust purification apparatus 10 are disposed downstream of the turbocharger 27 of the exhaust pipe 12. A filter is installed.

  The turbocharger 27 has a turbine (not shown) and a compressor connected to the turbine. When exhaust gas flows from the engine 11 into the turbocharger 27, the turbine is rotated by the flow of the exhaust gas, and the rotation of the turbine. Along with this, the compressor rotates to suck air from the intake pipe 22a into the turbocharger 27 and pressurize it. The air pressurized by the turbocharger 27 is supplied to each intake port 20 of the engine 11 through the intake pipe 22b.

  The cylinder head 13 is provided with an electronically controlled fuel injection valve 31 that directly injects fuel into the combustion chamber 17 of each cylinder. The fuel injection valve 31 has a predetermined fuel pressure from a common rail (not shown). Controlled high pressure fuel is supplied.

  Here, in the present embodiment, a diesel oxidation catalyst (hereinafter simply referred to as an oxidation catalyst) 32 and a NOx occlusion catalyst 33, which are exhaust purification catalysts, and an exhaust purification filter are provided in the exhaust pipe 12 on the downstream side of the turbocharger 27. A diesel particulate filter (DPF: Diesel Particulate Filter: hereinafter referred to as DPF) 34 is arranged in order from the upstream side. As will be described in detail later, an injector 50 for injecting fuel (light oil) as a reducing agent (additive) into the exhaust pipe 12a is provided in the exhaust pipe 12a between the turbocharger 27 and the oxidation catalyst 32. ing.

The oxidation catalyst 32 is formed, for example, by supporting a noble metal such as platinum (Pt) or palladium (Pd) on a honeycomb structure carrier made of a ceramic material. In the oxidation catalyst 32, when exhaust gas flows, nitrogen monoxide (NO) in the exhaust gas is oxidized to generate nitrogen dioxide (NO ₂ ). In addition, in order for the oxidation reaction in the oxidation catalyst 32 to occur, the oxidation catalyst 32 needs to be heated to a predetermined temperature or higher. Therefore, the oxidation catalyst 32 may be disposed as close to the engine 11 as possible. preferable. This is because the oxidation catalyst 32 is heated by the heat of the engine 11 and the oxidation catalyst 32 can be heated to a predetermined temperature or higher in a relatively short time even when the engine is started.

The NOx occlusion catalyst 33 is, for example, a noble metal such as platinum (Pt) or palladium (Pd) supported on a honeycomb structure carrier made of aluminum oxide (AL ₂ O ₃ ) and barium (Ba) as an occlusion agent. An alkali metal or alkaline earth metal is supported. The NOx storage catalyst 33 temporarily stores NOx in the oxidizing atmosphere, that is, NO ₂ generated by the oxidation catalyst 32, or NO remaining in the exhaust gas without being oxidized by the oxidation catalyst 32. In a reducing atmosphere containing carbon (CO), hydrocarbon (HC), etc., NOx is released and reduced to nitrogen (N ₂ ) or the like.

Most of the NO ₂ produced by the oxidation catalyst 32 is adsorbed / decomposed (reduced) by the NOx storage catalyst 33, and the remaining NO _{2 that} has not been adsorbed / decomposed is purified by the reaction in the DPF 34. Yes.

  Normally, most of the exhaust gas discharged from the engine 11 is occupied by NO and the amount of HC is very small. Therefore, the inside of the NOx storage catalyst 33 becomes an oxidizing atmosphere, and the NOx storage catalyst 33 only adsorbs NOx. NOx that has been released is not decomposed (reduced). For this reason, when a predetermined amount of NOx is adsorbed to the NOx storage catalyst 33, fuel (light oil) as an additive is injected from the injector 50 fixed to the exhaust pipe 12a between the turbocharger 27 and the oxidation catalyst 32. It has become so. As a result, the exhaust gas mixed with the fuel passes through the oxidation catalyst 32 and is supplied to the NOx storage catalyst 33. The inside of the NOx storage catalyst 33 becomes a reducing atmosphere, and the adsorbed NOx is decomposed (reduced).

  The DPF 34 is, for example, a filter having a honeycomb structure formed of a ceramic material. In the DPF 34, an exhaust gas passage 38 having an upstream end opened and a downstream end closed, and a downstream end are provided. Exhaust gas passages 39 opened and closed at the upstream end are alternately arranged. The exhaust gas first flows into the exhaust gas passage 38 whose upstream end is opened, and the exhaust whose downstream end is opened from the porous wall surface provided between the adjacent exhaust gas passages 39. The gas flows into the gas passage 39 and flows downstream, and in this process, particulate matter (PM) in the exhaust gas collides with the wall surface or is adsorbed and captured.

The trapped PM is oxidized (combusted) by NO ₂ in the exhaust gas and discharged as CO ₂ , and NO ₂ remaining in the DPF 34 is decomposed into N ₂ and discharged. That is, the DPF 34 can purify the exhaust gas and greatly reduce PM and NOx emissions. Moreover, the performance of the DPF 34 is regenerated to some extent by burning PM.

Here, since NOx is normally adsorbed by the NOx storage catalyst 33 as described above, the amount of NO _{2 in} the exhaust gas supplied to the DPF 34 is small, and PM is gradually deposited on the DPF 34. When a predetermined amount of PM accumulates in the DPF 34, a predetermined amount of fuel is injected from the injector 50 fixed to the exhaust pipe 12a. As described above, when the fuel is mixed with the exhaust gas, the adsorbed NOx is reduced by the NOx occlusion catalyst 33. Therefore, NOx (NO ₂ ) contained in the exhaust gas is not adsorbed by the NOx occlusion catalyst 33. To the DPF 34. As a result, PM combustion in the DPF 34 is promoted.

  An exhaust temperature sensor 40 is provided in the vicinity of the upstream side of the oxidation catalyst 32, the NOx storage catalyst 33 and the DPF 34, and the downstream side of the DPF 34, and the plurality of exhaust temperature sensors 40 provide the oxidation catalyst 32, The temperature of the exhaust gas flowing into the NOx storage catalyst 33 and the DPF 34 and the temperature of the exhaust gas discharged from the oxidation catalyst 32, the NOx storage catalyst 33 and the DPF 34 are detected. Further, an oxygen concentration sensor 41 for detecting the oxygen concentration in the exhaust gas is provided in the vicinity of the upstream side of the oxidation catalyst 32 and the DPF 34. The vehicle is provided with an electronic control unit (ECU) (not shown). The ECU includes an input / output device, a storage device for storing a control program and a control map, a central processing unit, a timer and a counter. There is a kind. The ECU performs comprehensive control of the engine 11 and the exhaust purification device 10 based on information from the sensors.

  Here, the attachment structure of the injector 50 according to the present embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view of the mounting portion of the injector. As shown in the drawing, the injector 50 is held by a holding member 60 so that a nozzle 52 which is an injection port at a tip portion faces the exhaust pipe 12a through an opening 12b provided in the exhaust pipe 12a. A portion arranged outside the exhaust pipe 12a is covered with a buffer space 80 by an injector cover 70 which is a protective member.

  The holding member 60 is provided with a holding hole 61 into which the tip end side of the injector 50 is fitted. In addition, a cooling fluid channel 62 that is a cooling fluid channel is formed around the holding hole 61 of the holding member 60. The cooling fluid channel 62 includes a cooling fluid inlet 63 and a cooling fluid discharge port. A cooling system such as a radiator (not shown) is connected via 64. The holding member 60 has a shape in which the injector 50 is fitted into the holding hole 61, but is not limited thereto, and the holding member 60 may have a shape that locks the injector 50 so that the injector 50 does not fall into the exhaust pipe 12a. For example, there may be a gap between the injector 50 and the holding hole 61.

  The tip of the injector 50 is fitted in the holding hole 61 of the holding member 60, and the nozzle 52 at the tip of the injector 50 is inserted into the exhaust pipe 12 a through the opening 12 b communicating with the holding hole 61. I'm here. A fuel inlet 51 for taking in high-pressure fuel from a fuel supply pipe 90 (additive supply path) is provided at the rear end of the injector 50. Further, an ECU connection portion 53 with an electronic control unit (ECU) (not shown) is provided on the side portion of the injector 50.

  The injector cover 70 has a portion (hereinafter referred to as “injector 50”) located on the rear end side of a portion fitted in the holding hole 61 of the injector 50 (hereinafter referred to as “fitting portion of the injector 50”). 50 ”is covered through a buffer space 80 which is a buffer space, and is fixed to the holding member 60 by a fixing bolt 73. Further, a protruding portion 72 directed toward the injector 50 is provided at a portion of the injector cover 70 on the holding member 60 side, and the protruding portion 72 sandwiches the injector 50 with the holding member 60.

  Here, the buffer space 80 refers to a space between the injector 50 and the inner surface of the injector cover 70. In the present embodiment, since the tip end side of the injector 50 is fitted to the holding member 60, the space between the covering portion of the injector 50 and the inner surface of the injector cover 70 is a buffer space 80. The buffer space 80 reduces the impact when flying stones or the like collide with the injector cover 70, and suppresses the heat transmitted to the injector cover 70 from being transmitted to the injector 50. The size of the buffer space 80 is not particularly limited, but is preferably as large as possible. It is because it can respond to a bigger impact and can also transfer heat of higher temperature. The buffer space 80 may be an open space or a closed space.

  Here, the attachment part of the injector cover 70 and the fuel supply pipe | tube 90 is demonstrated in detail using FIG.3 and FIG.4. 3 is an exploded perspective view of FIG. 2, and FIG. 4 is an assembled sectional view thereof. As shown in the drawing, a supply passage 74 is formed in the injector cover 70 and communicates with the fuel intake 51 of the injector 50. Further, a seal member 93 is interposed between the injector 50 and the injector cover 70 in the buffer space 80 near the fuel intake 51.

  The fuel supply pipe 90 has an annular end portion 90a, and a slit 90b serving as a fuel outlet is provided along the circumferential direction of the inner periphery on the inner peripheral surface of the end portion 90a.

  The mounting bolt 91 is inserted into the end 90 a of the fuel supply pipe and the washer 92 and screwed into the supply path 74. In addition, a hole 91 a that is a fuel flow path extends in the radial direction and the axial direction inside the mounting bolt 91, and communicates with the slit 90 b of the fuel supply pipe 90. As a result, the fuel flows as shown by the arrow in FIG. 4 and is supplied to the injector 50.

  As described above, according to the mounting structure of the injector 50 according to the present embodiment, the injector cover 70 covers the injector 50 through the buffer space 80, so that the injector 50 is protected from flying stones by the injector cover 70, Even when a flying stone hits the injector cover 70 directly, the shock is absorbed by the buffer space 80, and the influence of the impact from the flying stone or the like on the injector 50 is suppressed.

  Further, if the injector cover 70 is formed larger, the buffer space 80 becomes larger and the rigidity of the injector cover 70 is improved. Therefore, since it becomes stronger with respect to impacts from flying stones, the frequency with which the injector cover 70 is worn out and replaced is reduced, and the running cost on the injector cover 70 can be reduced.

  Furthermore, since air generally has a lower thermal conductivity than solids, the buffer space 80 also functions to suppress the transfer of heat from, for example, the engine room or the injector cover 70. Thereby, compared with the case where the injector cover 70 directly covers the injector 50 without passing through the buffer space 80, the injector 50 can be protected from heat damage.

  In addition, the injector 50 is sandwiched between the injector cover 70 and the holding member 60. For this reason, even when the holding member 60 is thinned, sufficient support rigidity of the injector 50 can be ensured. Further, in this case, since the number of fitting parts of the injector 50 is reduced, it is difficult for heat to be transferred from the exhaust pipe 12a to the injector 50 via the holding member 60, and the injector 50 can be more suitably protected from heat damage.

  The fuel supply pipe 90 is attached to an injector cover 70 fixed to the holding member 60. That is, since the fuel supply pipe 90 is attached to the injector cover 70 with improved support rigidity, the support rigidity of the fuel supply pipe 90 is also improved as compared with the case where the fuel supply pipe 90 is directly attached to the injector 50. is doing. Further, since the injector 50, the injector cover 70, and the fuel supply pipe 90 are integrally formed, it is easy to fix them to the exhaust pipe 12a via the holding member 60. This is particularly useful when installing an injector 50 or the like on an exhaust pipe of a small automobile in which a sufficient work space cannot be secured.

  Further, in the present embodiment, since the coolant flow path 62 is provided in the holding member 60, heat from the exhaust gas flowing in the exhaust pipe 12a can be absorbed, and the injector 50 can be prevented from being melted.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, in the above-described embodiment, as the exhaust purification device 10, the exhaust pipe (exhaust passage) 12 includes the oxidation catalyst 32 and the NOx storage catalyst 33 that are exhaust purification catalysts, and the DPF 34 that is an exhaust purification filter. Although the example which has arrange | positioned in order of the oxidation catalyst 32, the NOx storage catalyst 33, and DPF34 from the upstream was given, arrangement | positioning and kind of these exhaust gas purification catalysts and exhaust gas purification filters are not specifically limited. For example, as shown in FIG. 5A, the NOx storage catalyst 33, the oxidation catalyst 32, and the DPF 34 may be arranged in this order in the exhaust pipe 12 on the downstream side of the turbocharger 27. Further, for example, as shown in FIG. 5B, the NOx occlusion catalyst 33 and the DPF 34 may be sequentially arranged in the exhaust pipe 12 downstream of the turbocharger 27 without providing the oxidation catalyst 32. . Further, for example, as shown in FIG. 5 (c), it is possible to provide only the DPF 34A having a catalytic function without providing the exhaust purification catalyst. That is, only the DPF 34A, which is an exhaust purification filter that also serves as an exhaust purification catalyst, may be provided. In any case, the present invention can be adopted as long as it has an injector that injects an additive such as fuel upstream of the exhaust purification catalyst or the exhaust purification filter.

It is a figure which shows schematic structure of the exhaust gas purification apparatus which concerns on this embodiment. It is sectional drawing of the attaching part of the injector which concerns on this embodiment. It is a disassembled perspective view of the attachment structure of the injector which concerns on this embodiment. It is an assembly sectional view of the attachment structure of the injector concerning this embodiment. It is a schematic block diagram which shows the modification of the exhaust gas purification apparatus which concerns on this embodiment.

Explanation of symbols

11 Engine 12 Exhaust pipe 22 Intake pipe 27 Turbocharger 32 Oxidation catalyst 33 NOx storage catalyst 34 DPF
50 Injector 51 Fuel Inlet 52 Nozzle 60 Holding Member 61 Holding Hole 70 Injector Cover 80 Buffer Space 90 Fuel Supply Pipe 91 Mounting Bolt

Claims (5)

When attaching the injector with the injection port facing the exhaust passage, a protective member is provided that covers a portion of the injector disposed outside the exhaust passage,
The injector mounting structure, wherein the protective member is provided with a supply portion that is supplied with an additive and communicates with the additive intake port of the injector. In the injector mounting structure according to claim 1,
A holding member is attached to the attachment portion of the injector in the exhaust passage,
The holding member is provided with a holding hole for locking the injector,
The injector mounting structure, wherein the protection member is fixed to the holding member, and an injector locked in the holding hole is sandwiched between the holding member and the holding member. In the injector mounting structure according to claim 2,
The injector mounting structure, wherein the holding member has a coolant flow path formed around the holding hole. In the injector mounting structure according to claim 2 or claim 3,
The protective member is provided in the vicinity of the additive inlet of the injector through a buffering space, and a sealing member is interposed in the buffering space between the injector and the protective member. Injector mounting structure characterized by In the injector mounting structure according to any one of claims 2 to 4,
An additive supply pipe having an additive supply path is fixed to the protective member by a mounting bolt screwed into the supply part,
The injector mounting structure, wherein the additive supply pipe communicates with an additive intake port of the injector via an additive flow path formed in the mounting bolt.

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