JP2010031769A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device sufficiently inhibiting a temperature rise of a connector connected to an injector and preventing poor supply of an additive into an exhaust gas passage by the injector. <P>SOLUTION: This device includes the injector 50 injecting the additive into the exhaust gas passage, an installation member 60 including an installation hole 61 in which the injector 50 is installed and a cooling water path 62 disposed around the installation hole 61 and supplied with cooling water, and a heat protector 90 disposed around the connector 85 connecting the injector 50 and wiring 80 for sending electric signal to the injector 50. The heat protector 90 is fixed at an outer circumference part of the installation member 60 in such a manner that the same can exchange heat with cooling water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust purification device that purifies exhaust gas discharged from an engine.

  In exhaust gas exhausted from engines mounted on automobiles, especially diesel engines, carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM) ) Etc. are included. 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. to purify the exhaust gas and release it into the atmosphere.

  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 a hydrocarbon-based liquid such as) is introduced to cause an exothermic reaction and the particulate filter is regenerated by this heat.

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

  Since such NOx trap catalyst decomposes (reduces) adsorbed NOx, it is necessary to appropriately supply a reducing agent (additive) from the outside to the NOx trap catalyst. For this reason, in general, fuel (light oil) or the like is supplied as a reducing agent into the exhaust passage so as to be supplied to the NOx trap catalyst. For example, there is one in which fuel is injected into an exhaust passage by an injector provided in an exhaust pipe, and exhaust gas mixed with the fuel is supplied to a NOx trap catalyst (see, for example, Patent Document 1).

  Since NOx trap catalyst also adsorbs sulfur oxide (SOx) together with NOx, fuel (reducing agent) is supplied to the NOx trap catalyst to raise the temperature of the NOx trap catalyst, thereby decomposing (reducing) SOx. Things are also done.

  In addition, since the injector that injects an additive such as fuel into the exhaust pipe (exhaust passage) is exposed to high-temperature exhaust gas, for example, burnout or so-called deposit accumulates and the nozzle is clogged. Such a problem may occur.

  In order to solve such a problem, for example, a water jacket (cooling water channel) is formed around the injector, and cooling water is introduced into the water jacket and circulated to suppress an increase in the temperature of the injector. There are some (see, for example, Patent Document 2).

JP-A-2005-214100 JP 2004-044483 A

  By the way, such an injector is connected to a wiring for sending an electric signal for needle operation or the like by a connector. This connector is formed of a material having a relatively low heat-resistant temperature such as a resin material, for example.

  The injector is heated not only by the heat of the exhaust gas but also by the heat from the engine. For this reason, even if it is cooled with cooling water as described above, the temperature of the connector exceeds the heat resistance temperature due to the heat from the engine, the connector is burned out, and the additive may not be injected from the injector. In order to solve such a problem, generally, a heat protector for heat insulation is provided around a connector connected to the injector.

  However, the provision of a heat protector may not sufficiently suppress the temperature rise of the connector connected to the injector, and further measures are desired.

  The present invention has been made in view of such circumstances, and provides an exhaust emission control device that sufficiently suppresses the temperature rise of the connector connected to the injector and prevents the supply failure of the additive into the exhaust passage by the injector. The purpose is to do.

  A first aspect of the present invention that solves the above problem is an injector that is provided upstream of an exhaust purification catalyst that is interposed in an exhaust passage communicating with an engine and injects an additive into the exhaust passage; A mounting member having a mounting hole in which the injector is mounted, a cooling water passage that is arranged around the mounting hole and supplied with cooling water, and the wiring for sending an electrical signal to the injector are connected to the mounting member. A heat protector disposed around the connector, and the heat protector is fixed to the outer periphery of the mounting member so as to be able to exchange heat with the cooling water.

  In this 1st aspect, since a heat protector is cooled with the cooling water which circulates through the cooling water channel of a mounting member, the heat shield effect by a heat protector improves.

  According to a second aspect of the present invention, the outer peripheral portion of the mounting member is provided with an uneven portion including a plurality of protrusions and recesses, and the heat protector is engaged with the uneven portion. And the heat protector is fixed to the mounting member in a state where the engaging portion is engaged with the concavo-convex portion.

  In this 2nd aspect, since the uneven | corrugated | grooved part and an engaging part are provided and the contact area of a mounting member and a heat protector is large, a heat protector is cooled more effectively with cooling water.

  According to a third aspect of the present invention, the outer shape of the mounting member is substantially circular, and the protrusions and the recesses are formed in a spiral shape, and the heat protector is screwed to the mounting member. In the exhaust emission control device according to the second aspect,

  In the third aspect, the heat protector can be effectively cooled, and the heat protector can be fixed to the mounting member very easily and reliably.

  According to a fourth aspect of the present invention, in the second aspect, the ridge and the recess are linearly formed along the axial direction of the mounting hole of the mounting member. In the exhaust purification system.

  In the fourth aspect, the heat protector can be fixed to the mounting member very easily by simply sliding the heat protector along the axial direction of the mounting hole.

  According to a fifth aspect of the present invention, the heat protector is integrally provided with a fixing portion that protrudes inward and that abuts against a flange portion of the injector and fixes the injector. In the exhaust emission control device according to any one of the first to fourth aspects.

  In the fifth aspect, the injector is fixed to the mounting member at the same time as the heat protector is fixed to the mounting member.

  In the present invention, the heat protector fixed to the mounting member can sufficiently suppress the temperature rise of the connector connected to the injector and suppress burnout.

  Further, the heat protector can be easily fixed to the mounting member. Furthermore, the injector can be fixed by a heat protector. That is, the number of parts can be reduced, and the work can be facilitated, so that the cost can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail.

(Embodiment 1)
FIG. 1 is a diagram illustrating a schematic configuration of an engine including an exhaust purification 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 trap catalyst 33 which are exhaust purification catalysts, an exhaust purification filter, and an exhaust pipe 12 downstream 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. Further, as will be described in detail later, an injector that injects fuel (light oil) as a reducing agent (additive) into the exhaust pipe (exhaust passage) 12a in the exhaust pipe 12a between the turbocharger 27 and the oxidation catalyst 32. 50 is provided.

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.

In the NOx trap catalyst 33, for example, a noble metal such as platinum (Pt) or palladium (Pd) is supported on a honeycomb structure carrier made of aluminum oxide (AL ₂ O ₃ ), and barium (Ba) or the like is used as a storage agent. An alkali metal or alkaline earth metal is supported. The NOx trap 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.

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

  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 trap catalyst 33 becomes an oxidizing atmosphere, and the NOx trap 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 trap catalyst 33, fuel (light oil) as an additive is injected from the injector 50 fixed to the exhaust pipe 12 a between the turbocharger 27 and the oxidation catalyst 32. It has become so. As a result, the exhaust gas mixed with fuel passes through the oxidation catalyst 32 and is supplied to the NOx trap catalyst 33. The inside of the NOx trap catalyst 33 becomes a reducing atmosphere, and the adsorbed NOx is decomposed (reduced). The NOx trap catalyst 33 occludes and decomposes (reduces) sulfur oxide (SOx) as well as nitrogen oxide (NOx).

  The DPF 34 is a filter having a honeycomb structure made of, for example, a ceramic material. In the DPF 34, for example, an exhaust gas passage 38 in which an upstream end is opened and a downstream end is 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 trap 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 NOx trapped by the NOx trap catalyst 33 is reduced, so that NOx (NO ₂ ) contained in the exhaust gas is not absorbed by the NOx trap 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 trap catalyst 33 and the DPF 34, and in the vicinity of the downstream side of the DPF 34, respectively. The temperature of the exhaust gas flowing into the NOx trap catalyst 33 and the DPF 34 and the temperature of the exhaust gas discharged from the oxidation catalyst 32, the NOx trap 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.

  2A and 2B are diagrams showing the main part of the exhaust gas purification apparatus according to Embodiment 1, wherein FIG. 2A is a side view and FIG. 2B is a cross-sectional view. As shown in FIG. 2, an injector 50 for injecting fuel as a reducing agent is arranged in a direction substantially orthogonal to the exhaust pipe (exhaust passage) 12a, and the mounting member 60 fixed to the exhaust pipe 12a and this mounting It is held by a fixing member 70 fixed to the member 60. Specifically, a mounting hole 61 that is a through hole into which the injector 50 is mounted is formed at the center of the mounting member 60. The injector 50 is mounted in the mounting hole 61 in a state where the flange portion 51 provided on the outer peripheral portion thereof is in contact with the fixing member 70, and the tip surface 53 where the nozzle 52 opens is exposed in the exhaust pipe 12a. It is fixed to the mounting member 60. In the present embodiment, the fixing member 70 is fixed to the mounting member 60 by a fastening member 75 such as a bolt as shown in FIG.

  The mounting member 60 is provided with an annular cooling water channel 62 around the mounting hole 61. Although not shown, a supply path for supplying cooling water and a discharge path for discharging cooling water circulated through the cooling water path 62 are connected to the cooling water path 62, respectively. , The injector 50 is cooled, and the temperature rise of the injector 50 is suppressed.

  Further, a wire 80 for operating a needle (not shown) is connected to a portion protruding from the mounting member 60 of the injector 50 by a connector 85. A heat protector 90 is provided around the connector 85 connected to the injector 50 in this manner (around the injector 50) so as to surround the connector 85 and shield heat from the engine 11. Yes. The heat protector 90 is fixed to the outer peripheral portion of the mounting member 60 to which the injector 50 is mounted.

  Thus, by providing the heat protector 90 and shutting off the heat from the engine 11, the connector 85 is prevented from being heated beyond the heat-resistant temperature and being burned out. Further, the heat protector 90 is fixed to the outer peripheral portion of the mounting member 60 so as to be able to exchange heat with the cooling water in the cooling water passage 62. As a result, the heat protector 90 is cooled by the cooling water circulating through the cooling water passage 62 of the mounting member 60, and the ambient temperature around the heat protector 90 is lowered, so that the heat from the engine 11 is more effectively blocked (heat shielded). . Therefore, the burnout of the connector 85 can be further reliably suppressed.

  Here, in the present invention, on the outer peripheral surface of the mounting member 60, irregularities comprising a plurality of ridges 63 protruding outward and a plurality of ridges 64 defined by the plurality of ridges 63. A portion 65 is formed. In the present embodiment, each of the ridges 63 and the ridges 64 constituting the concavo-convex portion 65 are provided independently in the circumferential direction of the mounting member 60. Further, an uneven portion 65 is formed on the entire outer peripheral surface of the mounting member 60. On the other hand, the heat protector 90 is provided with an engaging portion 91 that engages with the concave and convex portion 65 of the mounting member 60. The engaging portion 91 is formed in a concavo-convex shape so as to engage with the convex strip portion 63 and the concave strip portion 64. That is, the heat protector 90 is fixed to the mounting member 60 in a state where the entire surface of the concavo-convex portion (outer peripheral surface) 65 of the mounting member 60 is in contact. The method for fixing the heat protector 90 to the mounting member 60 is not particularly limited. For example, the heat protector 90 is constituted by two members divided in the axial direction (vertical direction in the figure) of the mounting hole 61, and each member is brought into contact with the outer peripheral surface of the mounting member 60 and fixed with bolts or the like. do it.

  In such a configuration of the present embodiment, since the contact area of the heat protector 90 with the mounting member 60 can be secured relatively wide, the cooling effect of the heat protector 90 by the cooling water circulating through the cooling water passage 62 is increased, The heat shielding effect by the heat protector 90 is improved. Therefore, it is possible to more reliably suppress the connector 85 from being burned out by the heat of the engine 11.

  Furthermore, in the present embodiment, the outer peripheral surface 62 a outside the cooling water channel 62 is also formed in an uneven shape along the shape of the uneven portion 65. As a result, the thickness of the outer wall of the cooling water passage 62 becomes relatively thin over the entire concave and convex portion 65, so that the cooling effect of the heat protector 90 by the cooling water is further enhanced. Of course, the shape of the cooling water channel 62 is not particularly limited as long as the heat protector 90 can be sufficiently cooled.

  In the present embodiment, the ridges 63 constituting the concavo-convex portions 65 are continuously provided over the circumferential direction of the mounting member 60. Of course, the ridges 63 are provided in the circumferential direction of the mounting member 60. It may be provided intermittently.

(Embodiment 2)
FIGS. 4A and 4B are diagrams showing the main part of the exhaust emission control device according to the second embodiment, wherein FIG. 4A is a side view and FIG. 4B is a cross-sectional view.

  The present embodiment is a modification of the shape of the uneven portion of the mounting member and the engaging portion of the heat protector. That is, in this embodiment, as shown in FIG. 4, each of the protrusions 63 </ b> A and the recesses 64 </ b> A constituting the uneven part 65 </ b> A of the mounting member 60 </ b> A is formed in a mountain shape, and on the outer peripheral surface of the mounting member 60 </ b> A. It is formed in a spiral shape. On the other hand, the engaging portion 91A of the heat protector 90A is also formed in a spiral shape in accordance with the shape of the uneven portion 65A. That is, each of the concavo-convex portion 65A and the engaging portion 91A is a so-called triangular screw. Then, the engaging portion 91A is screwed into the concavo-convex portion 65A, and the heat protector 90A is fixed to the mounting member 60A.

  In such a configuration of the present embodiment, the heat protector 90A can be fixed to the mounting member 60A extremely easily and reliably, and the working efficiency is improved. Further, the member for fixing the heat protector 90A to the mounting member 60A is not necessary, and the number of parts is reduced. Therefore, cost can be reduced. Of course, also in the configuration of the present embodiment, since the cooling effect of the heat protector 90A is increased as in the first embodiment, the connector 85 can be prevented from being burned by the heat of the engine 11.

  In the present embodiment, the example in which the uneven portion 65A and the engaging portion 91A are so-called triangular screws has been described, but the shapes of the uneven portion 65A and the engaging portion 91A are not particularly limited, and for example, FIG. As shown in FIG. 5, it may be formed in a waveform and may be a so-called round screw, or may be a so-called square screw or trapezoidal screw. In any case, the heat protector 90A can be easily and reliably fixed to the mounting member 60A.

(Embodiment 3)
FIGS. 6A and 6B are diagrams showing the main part of the exhaust gas purification apparatus according to the third embodiment, where FIG. 6A is a side view and FIG. 6B is a cross-sectional view taken along line AA ′.

  In the above-described embodiment, the ridges and the ridges constituting the concavo-convex part are formed along the circumferential direction of the mounting member. On the other hand, in this embodiment, as shown in FIG. 6, the protrusions 63 </ b> B and the recesses 64 </ b> B constituting the concavo-convex part 65 </ b> B are arranged along the axial direction of the mounting hole 61 (vertical direction in FIG. Formed. Further, the engaging portion 91B of the heat protector 90B is also formed along the axial direction of the mounting hole 61 in accordance with the shape of the uneven portion 65B. Other configurations are the same as those in the above-described embodiment.

  Even in such a configuration, as a matter of course, the cooling effect of the heat protector 90 </ b> B is increased as in the first embodiment, so that the connector 85 can be prevented from being burned out by the heat of the engine 11.

  In the configuration of the present embodiment, the heat protector 90B can be fitted to the outer periphery of the mounting member 60B simply by sliding the heat protector 90B along the axial direction of the mounting hole 61 of the mounting member 60B. That is, there is an effect that the heat protector 90B can be more easily fixed to the mounting member 60B. Further, since the heat protector 90B can be fitted to the outer periphery of the mounting member 60B simply by sliding, the fixing member 70 (see FIG. 3) for fixing the injector 50 is integrally provided on the inner surface of the heat protector 90B. You may do it. Thereby, the injector 50 can be fixed to the mounting member 60B at the same time when the heat protector 90B is fitted into the mounting member 60B, and the working efficiency is further improved. Further, since the number of parts is reduced, the cost can be further reduced.

(Other embodiments)
Although the 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, the uneven portion is provided on the entire outer peripheral surface of the mounting member, but, of course, the uneven portion may be provided on a part of the outer peripheral surface of the mounting member. In the above-described embodiment, the configuration in which the cooling water channel is provided in the mounting member is illustrated, but the present invention is not limited thereto. For example, the heat protector has a double structure and communicates with the cooling water channel of the mounting member. A second cooling water channel may be provided. Thereby, the heat-shielding effect by a heat protector further improves.

  Further, 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 trap catalyst 33 that are exhaust purification catalysts, and the DPF 34 that is an exhaust purification filter. Although an example in which the oxidation catalyst 32, the NOx trap catalyst 33, and the DPF 34 are arranged in this order from the upstream side is given, the arrangement and types of the exhaust purification catalyst and the exhaust purification filter are not particularly limited. For example, as shown in FIG. 7A, the NOx trap 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. 7B, the NOx trap catalyst 33 and the DPF 34 may be sequentially arranged in the exhaust pipe 12 on the downstream side of the turbocharger 27 without providing the oxidation catalyst 32. . Further, for example, as shown in FIG. 7C, a configuration may be adopted in which only the DPF 34A having a catalytic function is provided 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.

  In the above-described embodiment, the NOx trap catalyst that decomposes (reduces) NOx using fuel (light oil) as a reducing agent is exemplified as the exhaust gas purification catalyst that decomposes (reduces) NOx, but is not limited thereto. For example, a so-called SCR (Selective Catalytic Reduction) that selectively adsorbs NOx in exhaust gas to a catalyst and injects ammonia or urea as a reducing agent from an injector to decompose (reduce) NOx may be used.

  In the above-described embodiment, the example in which the reducing agent is added as the additive has been described. However, the additive is not limited to the purpose of the reducing action, and if it is added to the exhaust system, for example, by combustion A fuel for the purpose of raising the temperature may be used.

  Furthermore, in the above-described embodiment, an example of the configuration of an intake / exhaust system including a turbocharger as a supercharger is shown. However, the present invention is not particularly limited thereto. For example, the supercharger is not necessarily provided. Further, a cooling exhaust gas recirculation device having a cooling exhaust gas recirculation passage between the exhaust passage and the intake passage, that is, a so-called EGR device may be provided.

1 is a diagram illustrating a schematic configuration of an exhaust purification device according to Embodiment 1. FIG. It is the side view and sectional drawing which show the principal part of the exhaust gas purification apparatus which concerns on Embodiment 1. 1 is a cross-sectional view showing a main part of an exhaust purification device according to Embodiment 1. FIG. It is the side view and sectional drawing which show the principal part of the exhaust gas purification apparatus which concerns on Embodiment 2. FIG. 6 is a cross-sectional view showing a modification of the exhaust gas purification apparatus according to Embodiment 2. It is the side view and sectional drawing which show the principal part of the exhaust gas purification apparatus which concerns on Embodiment 3. It is a schematic block diagram which shows the modification of an exhaust gas purification apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Exhaust purification apparatus 11 Engine 12 Exhaust pipe 13 Cylinder head 14 Cylinder block 15 Cylinder bore 16 Piston 17 Combustion chamber 18 Connecting rod 19 Crankshaft 20 Intake port 21 Intake manifold 22 Intake pipe 23 Intake valve 24 Exhaust port 25 Exhaust manifold 26 Exhaust valve 27 Turbo Charger 31 Fuel injection valve 32 Oxidation catalyst 33 NOx trap catalyst 38 Exhaust gas passage 39 Exhaust gas passage 40 Exhaust temperature sensor 41 Oxygen concentration sensor 50 Injector 51 Flange portion 60 Mounting member 61 Mounting hole 62 Cooling water path 63 Convex portion 64 Convex portion 65 Concavity and convexity part 70 Fixing member 80 Wiring 85 Connector 90 Heat protector 91 Engagement part

Claims (5)

An injector provided upstream of an exhaust purification catalyst interposed in an exhaust passage communicating with the engine and injecting an additive into the exhaust passage; a mounting hole in which the injector is mounted; and a periphery of the mounting hole And a heat protector disposed around a connector connecting the injector and a wiring for sending an electrical signal to the injector. ,
The exhaust gas purification apparatus, wherein the heat protector is fixed to an outer peripheral portion of the mounting member so as to be able to exchange heat with the cooling water.   The outer peripheral portion of the mounting member is provided with an uneven portion composed of a plurality of ridge portions and concave ridge portions, while the heat protector is provided with an engaging portion that engages with the uneven portion. 2. The exhaust emission control device according to claim 1, wherein the protector is fixed to the mounting member in a state where the engaging portion is engaged with the uneven portion.   The outer shape of the mounting member is substantially circular, the ridges and the recesses are formed in a spiral shape, and the heat protector is screwed to the mounting member. The exhaust emission control device according to 2.   The exhaust emission control device according to claim 2, wherein the convex strip portion and the concave strip portion are linearly formed along the axial direction of the mounting hole of the mounting member.   5. The heat protector is integrally provided with a fixing portion that protrudes inward and that is fixed to the flange portion of the injector so as to fix the injector. The exhaust emission control device according to claim 1.

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