JP2018200040A - Aftertreatment device of engine - Google Patents

Abstract

To improve heat insulating property while securing air-tightness between an exhaust pipe and an injector, in an aftertreatment device of an engine.SOLUTION: An aftertreatment device 10 of an engine includes an exhaust pipe 1, an injector 2, and an insulator 3. The injector 2 has a mounting portion 21 fastened and fixed to the exhaust pipe 1 by a bolt 4, and a seal face 22 formed substantially on the same plane as an end face 21a of the mounting portion 21 and disposed in airtight contact with the exhaust pipe 1. The exhaust pipe 1 has a mounting face 13 kept into contact with the seal face 22, and a recessed portion 14 recessed from the mounting face 13 by a thickness of the insulator 3. The insulator 3 is fastened with the injector 2 and fixed to the exhaust pipe 1 by the bolt 4 in a state of being held between the recessed portion 14 of the exhaust pipe 1 and the mounting portion 21 of the injector 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an aftertreatment device in which an insulator is interposed between an exhaust pipe of an engine and an injector attached to the exhaust pipe.

  Conventionally, as an after-treatment device for purifying engine exhaust, an exhaust purification additive such as urea water or ammonia water is injected into an exhaust pipe by an injector, and the additive and a catalyst disposed in the exhaust pipe are used for exhaust. Those which oxidize and reduce the components therein are known. In such an aftertreatment device, in order to activate the catalyst, it is a problem to suppress a temperature drop of the exhaust gas.

  In response to this problem, various structures have been proposed in which heat insulation of the exhaust pipe is enhanced to suppress heat dissipation of the exhaust pipe. For example, in the exhaust emission control device described in Patent Document 1, a heat insulating structure in which a heat insulating material is interposed between an outer shell and an inner shell is employed in a casing (exhaust pipe) that forms an exhaust passage.

  Moreover, in the exhaust emission control device of Patent Document 1, an injection nozzle (injector) is mounted on a rectifying body that extends so as to cross the casing, and a part of the nozzle body of the injection nozzle, a flange portion, Is covered from the outside by a heat insulating member (insulator). Thereby, the heat radiation from the injection nozzle is suppressed, and the heat insulation between the injection nozzle and the rectifier is enhanced.

JP 2009-115051

  However, since the heat insulating structure of the injector as described in Patent Document 1 is intended for an injector that is attached to a rectifier that extends so as to cross the exhaust pipe, it is attached to the exhaust pipe. It cannot be applied as it is to the injector. Further, in general, in the post-processing device in which the injector is mounted on the exhaust pipe, the mounting portion of the injector and the exhaust pipe is formed in a complicated shape so as to be airtight, so that the airtightness of the mounting portion is secured, It is difficult to place an insulator between the injector and the exhaust pipe.

  This case has been devised in view of the above-described problems, and an object of the engine aftertreatment device is to improve heat insulation while ensuring airtightness between the exhaust pipe and the injector.

(1) An engine aftertreatment device disclosed herein includes an exhaust pipe through which exhaust flows, an injector that injects an additive for purifying exhaust gas into the exhaust pipe, and an interposition between the exhaust pipe and the injector. The injector is formed on a plane substantially flush with an end surface of the mounting portion, and is provided in airtight contact with the exhaust pipe. The exhaust pipe has a mounting surface with which the seal surface abuts, and a recessed portion that is recessed by the thickness of the insulator from the mounting surface, and the insulator is disposed on the exhaust pipe. In a state of being sandwiched between the recess and the mounting portion of the injector, the bolt is fastened together with the injector by the bolt and fixed to the exhaust pipe.
Thereby, the airtightness between the injector and the exhaust pipe is ensured in a state where the insulator is sandwiched between the exhaust pipe and the injector.

  According to the engine aftertreatment device of the disclosure, it is possible to improve heat insulation while ensuring airtightness between the exhaust pipe and the injector.

It is a fragmentary sectional view of the aftertreatment device of the engine concerning an embodiment. It is a principal part enlarged view of FIG. It is a disassembled perspective view of the post-processing apparatus of FIG.

With reference to the drawings, an aftertreatment device for an engine as an embodiment will be described. The embodiment described below is merely an example, and there is no intention of excluding various modifications and technical applications that are not explicitly described in the following embodiment.
In the following description, upstream and downstream are defined based on the flow direction of the exhaust gas of the engine to which the present post-processing device is applied.

[1. Constitution]
The engine aftertreatment device 10 according to the present embodiment purifies exhaust gas from an engine mounted on a vehicle (not shown). As shown in FIG. 1, the aftertreatment device 10 includes an exhaust pipe 1 through which exhaust flows, an injector 2 attached to the exhaust pipe 1, and a heat shield plate interposed between the exhaust pipe 1 and the injector 2. (Insulator) 3.

  The exhaust pipe 1 is for guiding exhaust from the cylinder of the engine to the outside of the vehicle. The exhaust pipe 1 of the present embodiment is configured by connecting a plurality of pipe-like members. The exhaust pipe 1 includes a seat portion 11 to which the injector 2 is attached, and a hole portion 12 penetrating the seat portion 11. The seat portion 11 is formed with a plurality of screw holes 11h into which bolts 4 for fixing the injector 2 to the exhaust pipe 1 are screwed.

  The hole 12 is a portion where the tip 2 a of the injector 2 is disposed, and communicates with the exhaust passage in the exhaust pipe 1. A catalyst (not shown) for exhaust gas purification is provided at a portion downstream of the seat portion 11 of the exhaust pipe 1. 1 and FIG. 2 in which a part of FIG. 1 is enlarged are partial cross-sectional views of the post-processing device 10, and each member other than the injector 2 and the bolt 4 is a plane including the central axis of the two bolts 4. The disconnected state is shown.

  A heat shield pipe 5 is provided on the outer periphery of the exhaust pipe 1. The heat shield tube 5 is for suppressing the heat of the exhaust from being released to the outside of the exhaust tube 1. That is, the heat shield pipe 5 has a function of insulating the exhaust pipe 1. The heat shield tube 5 of this embodiment is formed in a pipe shape by combining two semi-cylindrical members. The heat shield tube 5 has a hole portion 5 a for exposing the seat portion 11 of the exhaust pipe 1 to the outside of the heat shield tube 5. In other words, the heat shield tube 5 is provided so as to cover a portion of the exhaust pipe 1 excluding the seat portion 11.

  An insulating air layer S is provided between the outer peripheral wall of the exhaust pipe 1 and the inner peripheral wall of the heat shield pipe 5. A heat insulating material 6 is disposed in a part of the air layer S. The heat insulating material 6 is a glass mat, for example, and is fixed to both the outer peripheral wall of the exhaust pipe 1 and the inner peripheral wall of the heat shield pipe 5. The heat insulating material 6 has both a function of improving the heat insulating property in the air layer S and a function of strengthening fixing of the exhaust pipe 1 and the heat shield pipe 5.

  The injector 2 is for injecting an exhaust purification additive into the exhaust pipe 1 from an injection hole formed in the tip end portion 2a. The injector 2 includes a plurality of attachment portions 21 that are fastened and fixed to the seat portion 11 of the exhaust pipe 1 with bolts 4, and a seal surface 22 that is provided in airtight contact with the seat portion 11 of the exhaust pipe 1. Hereinafter, the central axis O of the injection hole through which the injector 2 injects the additive is referred to as “injection axis O”.

  As shown in FIG. 3, each attachment portion 21 has a bolt hole 21 h through which the bolt 4 is inserted, and is formed at a position where it does not overlap the injection shaft O. Each of the attachment portions 21 of the present embodiment has a substantially cylindrical shape. The central axis of each bolt hole 21h is parallel to the injection axis O. Moreover, in the attachment part 21, the end surface 21a arrange | positioned facing the seat part 11 of the exhaust pipe 1 is made into a plane.

  As shown in FIG. 2, the seal surface 22 is formed in substantially the same plane as the end surface 21 a of the attachment portion 21. The seal surface 22 of the present embodiment is an annular plane with the injection axis O as the center. In this embodiment, the case where the sealing surface 22 is formed in the gasket 7 provided in the front-end | tip part 2a of the injector 2 is illustrated.

  The gasket 7 is a member for enhancing the airtightness between the injector 2 and the exhaust pipe 1. The gasket 7 has a cylindrical portion 7a disposed along a wall portion surrounding the hole portion 12 of the exhaust pipe 1, and a flange portion 7b extending outward from an end portion of the cylindrical portion 7a. The seal surface 22 is formed on the surface of the flange portion 7 b of the gasket 7.

  As shown in FIGS. 1 and 3, the injector 2 is supplied with electric power from an additive supply unit 23 to which an additive is supplied, two cooling water supply / discharge units 24 and 24 to which cooling water is supplied and discharged. Power supply unit 25. A hose (not shown) is connected to each of the additive supply unit 23 and the cooling water supply / discharge unit 24. A harness (not shown) is connected to the power supply unit 25. Hereinafter, these portions 23 to 25 are collectively referred to as connector portions 23 to 25. The connector portions 23 to 25 of the present embodiment are all provided close to the exhaust pipe 1.

  The heat shield plate 3 is for suppressing the heat of the exhaust from being released to the outside of the exhaust pipe 1 and suppressing the injector 2 from absorbing the heat of the exhaust. In other words, the heat shield plate 3 has a heat insulating function for the exhaust pipe 1 and a heat shield function for the injector 2. The heat shield plate 3 is formed, for example, by pressing a plate-like stainless steel having a substantially uniform thickness. The thickness (plate thickness) of the heat shield plate 3 is determined according to the heat insulating property and heat shield property required for the heat shield plate 3.

  The heat shield plate 3 of the present embodiment is shaped to close the hole 5a of the heat shield tube 5. Specifically, the heat shield plate 3 includes a main body portion 31 formed in a flat plate shape and two flange portions 32 and 33 extending from the outer edge of the main body portion 31.

  The main body portion 31 is a portion that is sandwiched between the seat portion 11 of the exhaust pipe 1 and the attachment portion 21 of the injector 2, and has a function of suppressing heat transfer from the seat portion 11 of the exhaust pipe 1 to the injector 2. As shown in FIGS. 2 and 3, the main body 31 includes a through hole 31 a formed so as to overlap the hole 12 of the exhaust pipe 1 and a plurality of bolt holes 31 h through which the bolt 4 is inserted. The diameter of the through hole 31 a of the main body 31 is made larger than the diameter of the hole 12 of the exhaust pipe 1 by the amount of the mounting surface 13 provided in the seat part 11 of the exhaust pipe 1. Details of the mounting surface 13 will be described later.

  The two flange portions 32, 33 are a first flange portion 32 extending from a part of the outer edge of the main body portion 31 in the direction in which the injector 2 injects the additive, and a first flange portion from the remaining outer edge of the main body portion 31. 32 and a second flange portion 33 extending to the opposite side. The first flange portion 32 has a function of suppressing heat dissipation from the seat portion 11 of the exhaust pipe 1 and is provided so as to surround the outer periphery of the seat portion 11. A gap is provided between the first flange portion 32 and the exhaust pipe 1.

  On the other hand, the second flange portion 33 has a function of reducing radiant heat transmitted from the exhaust pipe 1 to the connector portions 23 to 25 of the injector 2 and is provided so as to be interposed between the heat shield pipe 5 and the injector 2. A gap is provided between the second flange portion 33 and the heat shield tube 5. As shown in FIG. 2, the heat insulating material 8 is disposed in the gap between the second flange portion 33 and the heat shield tube 5. The heat insulating material 8 is fixed to the second flange portion 33. The heat insulating material 8 is, for example, a glass mesh or a stainless mesh, and has a function of improving the heat insulating property in the gap between the second flange portion 33 and the heat shield tube 5.

  Here, the seat 11 of the exhaust pipe 1 will be described in detail. The seat 11 of the exhaust pipe 1 is provided with a mounting surface 13 with which the seal surface 22 of the injector 2 abuts and a recess 14 that is recessed from the mounting surface 13 by the thickness of the heat shield plate 3. The attachment surface 13 has substantially the same shape as the seal surface 22. That is, the attachment surface 13 of the present embodiment is an annular flat surface. The attachment surface 13 is provided at a position surrounding the hole 12 of the exhaust pipe 1.

  The recess 14 is a part dug down from the mounting surface 13 in the seat 11. The bottom surface of the recess 14 is a plane substantially parallel to the mounting surface 13. The main body 31 of the heat shield 3 is disposed in the recess 14. In the present embodiment, when the main body 31 of the heat shield 3 is disposed in the recess 14, a clearance (a minute gap) between the recess 14 and the edge surrounding the through hole 31 a of the heat shield 3. Each shape of the concave portion 14 and the through hole 31a of the heat shield plate 3 is set.

  Hereinafter, a procedure for assembling the injector 2 and the heat shield 3 to the exhaust pipe 1 will be described. As shown in FIG. 3, first, the heat shield plate 3 is overlaid on the seat portion 11 of the exhaust pipe 1. Specifically, the main body of the heat shield plate 3 so that the screw hole 11h formed in the seat portion 11 of the exhaust pipe 1 and the bolt hole 31h penetrating the main body portion 31 of the heat shield plate 3 communicate with each other. The part 31 is disposed in the recess 14 of the exhaust pipe 1.

  Next, the injector 2 to which the gasket 7 is attached is overlaid on the heat shield plate 3. Specifically, each attachment of the injector 2 to the main body 31 of the heat shield 3 so that the bolt hole 31h of the heat shield 3 and the bolt hole 21h penetrating through the attachment 21 of the injector 2 communicate with each other. The end surface 21a of the part 21 is brought into contact. In this state where the injector 2 is disposed in contact with the heat shield plate 3, the screw hole 11h of the exhaust pipe 1, the bolt hole 31h of the heat shield plate 3, and the bolt hole 21h of the injector 2 communicate with each other. Provided.

  Next, the bolt 4 is inserted through the bolt hole 21 h of the injector 2 and the bolt hole 31 h of the heat shield 3 in order, and is screwed into the screw hole 11 h of the exhaust pipe 1. Thereby, the injector 2 and the heat shield 3 are fixed to the exhaust pipe 1. That is, the heat shield 3 is clamped together with the injector 2 by the bolt 4 and fixed to the exhaust pipe 1 while being sandwiched between the recess 14 of the exhaust pipe 1 and the mounting portion 21 of the injector 2. As described above, in the post-processing apparatus 10, the bolt 4 used for fixing the injector 2 is shared by the heat shield plate 3.

[2. Action, effect]
(1) In the injector 2 described above, the end surface 21a of the mounting portion 21 and the seal surface 22 provided on the gasket 7 are formed on substantially the same plane. For this reason, when the attachment destination is a flat surface, the injector 2 is secured to both the end surface 21a of the mounting portion 21 and the seal surface 22 in close contact with the flat surface.

  On the other hand, the exhaust pipe 1 described above is provided with an attachment surface 13 with which the seal surface 22 abuts and a recess 14 that is recessed from the attachment surface 13 by the thickness of the heat shield plate 3. In the aftertreatment device 10 described above, the injector 2 and the heat shield plate 3 are attached to the exhaust pipe 1 in a state where the heat shield plate 3 is sandwiched between the recess 14 of the exhaust pipe 1 and the mounting portion 21 of the injector 2. Fixed. In this way, by disposing the heat shield plate 3 in the recess 14 that is recessed by the thickness of the heat shield plate 3, the exhaust pipe 1 while the seal surface 22 of the injector 2 and the mounting surface 13 of the exhaust pipe 1 are brought into close contact with each other. The heat shield plate 3 can be sandwiched between the injector 2 and the injector 2. That is, when the heat shield plate 3 is disposed in the recess 14 of the exhaust pipe 1, the mounting surface 13 of the exhaust pipe 1 and the surface of the heat shield plate 3 can be positioned on substantially the same plane. For this reason, in the state which has arrange | positioned the heat shield 3 between the exhaust pipe 1 and the injector 2, the airtightness between the exhaust pipe 1 and the injector 2 is securable.

  Further, since the heat shield plate 3 is provided, heat dissipation of the exhaust pipe 1 can be suppressed, so that a decrease in exhaust gas temperature can be suppressed. Thereby, activation of the catalyst arrange | positioned in the exhaust pipe 1 can be accelerated | stimulated. At the same time, since the heat transmitted from the exhaust pipe 1 to the injector 2 is reduced, the temperature rise of the injector 2 can be suppressed. Thereby, the injector 2 can be protected. Therefore, according to the post-processing device 10 described above, it is possible to improve heat insulation while ensuring airtightness between the exhaust pipe 1 and the injector 2.

  In addition, since the above-described heat shield plate 3 is fastened together with the injector 2 by bolts 4 and fixed to the exhaust pipe 1, it is possible to save the trouble of fixing the heat shield plate 3 to the exhaust pipe 1 and to reduce the number of parts. It can contribute to reduction. That is, by sharing the bolt 4 used for fixing the injector 2 for fixing the heat shield plate 3, the heat shield plate 3 can be fixed simultaneously with fixing the injector 2, and the injector 2 and the heat shield plate 3. The number of bolts can be reduced as compared with the case where a dedicated bolt is used for each of the above. Therefore, according to the post-processing device 10 described above, an increase in weight can be suppressed and an increase in cost can be suppressed.

  Moreover, in the post-processing apparatus 10 mentioned above, since the space for arrange | positioning the heat insulation board 3 is ensured by providing the recessed part 14 in the exhaust pipe 1, it is not necessary to change the shape of the injector 2. FIG. For this reason, an existing product can be used for the injector 2. Therefore, the cost concerning the injector 2 can be suppressed.

  Further, the exhaust pipe 1 is easier to process than the injector 2, and therefore, by providing the recess 14 in the exhaust pipe 1, the space of the heat shield plate 3 can be secured by changing the shape of the injector 2. Manufacturing can be facilitated. Furthermore, it can respond easily when changing the thickness of the heat shield plate 3.

  (2) Since the heat shield plate 3 described above has the first flange portion 32 provided so as to surround the outer periphery of the seat portion 11 of the exhaust pipe 1, heat dissipation of the exhaust pipe 1 can be further suppressed. Thereby, the temperature fall of exhaust_gas | exhaustion can be suppressed more. Moreover, since the heat shield plate 3 described above has the second flange portion 33 provided so as to be interposed between the heat shield tube 5 and the injector 2, the heat transmitted from the exhaust pipe 1 to the injector 2 can be further reduced. Can do. Thereby, the temperature rise of the injector 2 can be suppressed more.

  In particular, since the second flange portion 33 extends from the main body portion 31 of the heat shield plate 3 to the side opposite to the direction in which the injector 2 injects the additive, the heat transmitted to the connector portions 23 to 25 of the injector 2 is reduced. It can contribute to reduction. For this reason, while contributing to protection of the connector parts 23-25, deterioration of the connector parts 23-25 can be suppressed.

  Moreover, the heat insulation between the exhaust pipe 1 and the injector 2 can be further improved by disposing the heat insulating material 8 between the second flange portion 33 and the heat shield pipe 5. For this reason, while being able to suppress the temperature fall of exhaust_gas | exhaustion more, the injector 2 can be protected more reliably.

[3. Modified example]
Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the invention. Each structure of this embodiment can be selected as needed, or may be combined appropriately.

  The first flange portion 32 and the second flange portion 33 of the heat shield plate 3 described above may be omitted. That is, as long as the heat shield plate 3 has at least the main body 31, it is possible to improve heat insulation while ensuring airtightness between the exhaust pipe 1 and the injector 2 as described above. Moreover, the trouble of fixing the heat shield plate 3 to the exhaust pipe 1 can be saved, and the number of parts can be reduced.

  In the above-described embodiment, the case where the seal surface 22 of the injector 2 is provided as the surface of the gasket 7 is illustrated. However, the seal surface 22 may be a flat surface provided in airtight contact with at least the exhaust pipe 1. The surface of the gasket 7 is not limited. For example, when the gasket 7 is not provided, the seal surface 22 may be provided at a corresponding portion of the injector 2. Moreover, the structure of the gasket 7 is not limited to what was mentioned above, For example, the cylindrical part 7a may be abbreviate | omitted.

  In addition, each kind of the catalyst provided in the exhaust pipe 1 and the additive injected by the injector 2 may be appropriately determined according to the components in the exhaust gas to be purified by the post-processing device 10, and is not particularly limited. . For example, a reduction catalyst may be employed as the above-described catalyst, and urea water or ammonia water may be employed as an additive to purify NOx in the exhaust gas. Alternatively, an oxidation catalyst is employed as the above-described catalyst, an unburned fuel is employed as an additive, the exhaust temperature is increased by oxidizing the unburned fuel with the oxidation catalyst, and the exhaust gas collected in the filter PM (Particulate Matter) may be burned.

1 Exhaust pipe 2 Injector 3 Heat shield (insulator)
4 Bolt 10 Post-processing device 13 Mounting surface 14 Recess 21 Mounting portion 21a End surface 22 Seal surface

Claims (1)

An exhaust pipe through which exhaust flows;
An injector for injecting an exhaust purification additive into the exhaust pipe;
An insulator interposed between the exhaust pipe and the injector,
The injector has a mounting portion fastened and fixed to the exhaust pipe with a bolt, and a seal surface that is formed on substantially the same plane as the end surface of the mounting portion and is provided in airtight contact with the exhaust pipe,
The exhaust pipe has an attachment surface with which the seal surface abuts, and a recess that is recessed by the thickness of the insulator from the attachment surface,
The insulator is clamped between the recess of the exhaust pipe and the mounting portion of the injector, and is fastened together with the injector by the bolt and fixed to the exhaust pipe. , Engine aftertreatment device.

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