Exhaust pipe insulation structure

Abstract

To provide a heat insulation structure of an exhaust pipe capable of draining the inside of a heat insulator and suppressing attachment of foreign matters to a surface of the exhaust pipe.SOLUTION: A heat insulation structure 1 of an exhaust pipe is a structure connected to an internal combustion engine of a vehicle, and the exhaust pipe 10 includes a first heat insulator 20 having a protruding region 19 protruding by bending or swelling of the exhaust pipe 10 and covering the exhaust pipe 10 at an upstream side with respect to the protruding region 19, and a second heat insulator 30 covering the exhaust pipe 10 at a downstream side with respect to the protruding region 19. A downstream-side end portion 20a of the first heat insulator 20 and an upstream-side end portion 30a of the second heat insulator 30 are overlapped so as to form clearance parts S3, S4 communicated with the external and extending along a circumferential direction of the exhaust pipe 10, and a wire mesh 40 is disposed on at least the clearance part S3.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a thermal insulation structure for an exhaust pipe. [Background technology]

[0002] An example of a conventional exhaust pipe insulation structure is an exhaust pipe with an exhaust gas insulation structure described in Patent Document 1. In this conventional exhaust pipe insulation structure, the exhaust pipe is divided into multiple parts in the exhaust gas flow direction, and a protective shield member is provided to cover the outer periphery of the joints. One end of the protective shield member is fixed to the downstream heat insulator, while the other end of the protective shield member is not fixed to the upstream heat insulator. An overlapping portion having a predetermined gap is provided between the inner periphery of the protective shield member and the outer periphery of the upstream heat insulator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-39325 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned exhaust pipe insulation structure, it is necessary to drain the water inside the heat insulator as a corrosion prevention measure. In a typical structure, the heat insulator is provided with a drain hole, but if foreign matter such as dead grass gets into the drain hole, the foreign matter may easily adhere to the surface of the exhaust pipe.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an insulating structure for an exhaust pipe that can simultaneously drain water from inside the heat insulator and prevent foreign matter from adhering to the surface of the exhaust pipe. [Means for solving the problem]

[0006] An insulating structure for an exhaust pipe according to one aspect of the present disclosure is an insulating structure for an exhaust pipe connected to an internal combustion engine of a vehicle, the exhaust pipe having a protruding region that protrudes due to bending or bulging of the exhaust pipe, and comprising a first heat insulator covering the exhaust pipe upstream of the protruding region, and a second heat insulator covering the exhaust pipe downstream of the protruding region, the downstream end of the first heat insulator and the upstream end of the second heat insulator overlap so as to form a gap portion that runs circumferentially around the exhaust pipe and communicates with the outside, and a wire mesh is arranged in the gap portion, at least in the portion on the protruding direction side of the protruding region.

[0007] In this exhaust pipe insulation structure, the downstream end of the first heat insulator and the upstream end of the second heat insulator overlap to form a gap that is circumferentially aligned with the exhaust pipe and communicates with the outside. The formation of this gap allows water that has accumulated in the heat insulator to be discharged to the outside through the gap. In addition, the wire mesh disposed in at least the portion of the gap on the protruding direction side of the protruding region can prevent foreign matter such as dead grass from entering the heat insulator from the outside. Therefore, this exhaust pipe insulation structure can simultaneously drain water from inside the heat insulator and prevent foreign matter from adhering to the surface of the exhaust pipe.

[0008] The upstream end of the second heat insulator may be disposed radially outward of the downstream end of the first heat insulator. With this configuration, when the vehicle is running, air from the outside can be taken into the heat insulator as a cooling gas for the exhaust pipe.

[0009] The width of the wire mesh may be equal to or greater than the overlapping width of the downstream end of the first heat insulator and the upstream end of the second heat insulator. In this case, the width of the wire mesh can be sufficiently secured, and foreign matter such as dead grass can be more reliably prevented from entering the heat insulator from the outside.

[0010] The wire mesh may be disposed around the entire circumference of the exhaust pipe, which can more reliably prevent foreign matter such as dead grass from entering the heat insulator from the outside.

[0011] The wire mesh may be divided and disposed in the circumferential direction of the exhaust pipe, which can improve the workability of assembling the heat insulating structure of the exhaust pipe. Effect of the Invention

[0012] According to the present disclosure, it is possible to both drain water from inside the heat insulator and prevent foreign matter from adhering to the surface of the exhaust pipe. [Brief description of the drawings]

[0013] [Figure 1] 1 is a side view showing a heat insulating structure of an exhaust pipe according to an embodiment of the present disclosure. [Diagram 2] 2 is an enlarged perspective view of a main part of the heat insulating structure of the exhaust pipe shown in FIG. 1. [Diagram 3] 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A preferred embodiment of a heat insulating structure for an exhaust pipe according to one aspect of the present disclosure will be described in detail below with reference to the drawings. In the following description, for convenience of explanation, the terms "upper" and "lower" are used based on the installation state of the exhaust pipe to the vehicle. In addition, the terms "upper" and "downstream" are used based on the flow direction of exhaust gas in the exhaust pipe.

[0015] 1 is a side view showing an exhaust pipe insulation structure according to an embodiment of the present disclosure. As shown in the figure, the exhaust pipe insulation structure 1 is a structure that insulates an exhaust pipe 10 with a first heat insulator 20 and a second heat insulator 30. The exhaust pipe 10 has a protruding region 19 that protrudes vertically downward due to bending or swelling of the exhaust pipe 10. The first heat insulator 20 is disposed so as to cover the exhaust pipe 10 upstream of the protruding region 19. The second heat insulator 30 is disposed so as to cover the exhaust pipe 10 downstream of the protruding region 19.

[0016] The exhaust pipe 10 is connected to an internal combustion engine mounted on a vehicle, and constitutes an exhaust passage that discharges exhaust gas generated by combustion in a combustion chamber of the internal combustion engine. When connected to the internal combustion engine, the exhaust pipe 10 extends, for example, along the front-rear direction of the vehicle. An example of an internal combustion engine is a diesel engine. Examples of vehicles to which the exhaust pipe insulation structure 1 is applied include passenger cars, pickup trucks, buses, dump trucks, and the like.

[0017] On the upstream side of the exhaust pipe 10, for example, a turbocharger, a DOC (Diesel Oxidation Catalyst), a DPF (Diesel Particulate Filter), etc. are provided. On the downstream side of the exhaust pipe 10, for example, an SCR (Selective Catalytic Reduction) is provided. In the example of FIG. 1, an injector 50 for injecting a reducing agent (for example, urea water) into the SCR is disposed in the exhaust pipe 10. The injector 50 is attached to a wall of the exhaust pipe 10 so as to face the upstream side of the exhaust pipe 10.

[0018] The exhaust pipe 10 has a connection part 11 on the upstream side and bent parts 12, 13, and 14. Another exhaust pipe arranged on the upstream side (internal combustion engine side) of the exhaust pipe 10 is connected to the connection part 11. A straight part 15 extending from the connection part 11 is inclined downward toward the injector 50 to match the piping path of the upstream exhaust pipe. The bent part 12 bends the exhaust pipe 10 such that the inclination of a straight part 16 extending downstream from the bent part 12 is smaller than the inclination of the straight part 15. The extension direction of the straight part 15 downstream of the bent part 12 is more aligned with the direction of the injector 50 than the straight part 15.

[0019] The bent portion 13 is provided near the base end of the injector 50. The bent portion 13 bends the exhaust pipe 10 so that the inclination of a straight portion 17 downstream of the bent portion 13 is greater than the inclination of the straight portion 16. The straight portion 17 downstream of the bent portion 13 extends downward toward the attachment position of the injector 50. The bent portion 14 bends the exhaust pipe immediately downstream of the bent portion 13 so that the straight portion 18 downstream of the injector 50 extends along the axial direction of the injector 50. The straight portion 18 downstream of the injector 50 extends at a slight upward inclination with respect to the horizontal plane.

[0020] These bent portions 12, 13, and 14 allow the piping path of the exhaust pipe 10 to avoid interference with, for example, the lower structure of the vehicle (such as a cross member of the suspension). Also, by using an injector 50 attached so as to inject the reducing agent toward the rear of the vehicle, the reducing agent can be injected downstream inside the exhaust pipe 10.

[0021] The exhaust pipe 10 has a protruding region 19 that protrudes due to bending of the bent portion 14. That is, in the exhaust pipe 10, a certain range downstream of the bent portion 14 is the protruding region 19 formed by bending the bent portion 14. As an example, the protruding region 19 is a region that includes a point located vertically lowest (a point with the smallest height above ground) in the exhaust passage including the exhaust pipe 10. In the protruding region 19, a dispersion plate (not shown) is disposed inside the exhaust pipe 10. The dispersion plate is disposed, for example, inside the exhaust pipe 10 so as to face the injector. The dispersion plate has a function of stirring the exhaust gas passing through the exhaust pipe 10 and suppressing variations in the exhaust oxygen concentration inside the exhaust pipe 10.

[0022] Fig. 2 is an enlarged perspective view of a main part of the heat insulating structure 1 for an exhaust pipe shown in Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3.

[0023] 2 and 3, the first heat insulator 20 has a pair of heat shield plates 21, 22 provided along the outer surface of the exhaust pipe 10 upstream of the protruding region 19. The second heat insulator 30 has a pair of heat shield plates 31, 32 provided along the outer surface of the exhaust pipe 10 downstream of the protruding region 19. The first heat insulator 20 has a left-right split structure made up of the heat shield plates 21, 22 when viewed from the axial direction of the exhaust pipe 10. Similarly, the second heat insulator 30 has a left-right split structure made up of the heat shield plates 31, 32 when viewed from the axial direction of the exhaust pipe 10.

[0024] The heat shield 21 is disposed on one side in the horizontal direction of the first heat insulator 20. The heat shield 22 is disposed on the other side in the horizontal direction of the first heat insulator 20. The heat shield 31 is disposed on one side in the horizontal direction of the second heat insulator 30. The heat shield 32 is disposed on the other side in the horizontal direction of the second heat insulator 30. The heat shields 21, 22, 31, and 32 are formed, for example, by pressing or the like, and each has a substantially semicircular cross section. The heat shields 21, 22, 31, and 32 can be made of, for example, stainless steel or the like.

[0025] Each of the pair of heat shield plates 21, 22 constituting the first heat insulator 20 includes arc portions 21a, 22a, lower end portions 21b, 22b, and upper end portions 21c, 22c. The overlapping portions of the lower end portions 21b, 22b are joined together, and the overlapping portions of the upper end portions 21c, 22c are joined together, so that the first heat insulator 20 is formed into a cylindrical shape. The lower end portions 21b, 22b and the upper end portions 21c, 22c are joined together by spot welding or the like, for example, at joining positions that take into consideration vibration suppression of the entire first heat insulator 20.

[0026] Each of the pair of heat shield plates 31, 32 constituting the second heat insulator 30 includes arc portions 31a, 32a, lower end portions 31b, 32b, and upper end portions 31c, 32c. The second heat insulator 30 is formed into a cylindrical shape by joining the overlapping portions of the lower end portions 31b, 32b and the upper end portions 31c, 32c together. The lower end portions 31b, 32b and the upper end portions 31c, 32c are joined by spot welding or the like at joining positions that take into consideration the overall vibration suppression of the second heat insulator 30.

[0027] The downstream end 20a of the first heat insulator 20 and the upstream end 30a of the second heat insulator 30 have an overlapping portion R so as to form gaps S3, S4 that are aligned in the circumferential direction of the exhaust pipe 10 and communicate with the outside. In this embodiment, the upstream end 30a of the second heat insulator 30 has an expanded diameter at the overlapping portion R and is disposed so as to be on the outer side in the radial direction of the exhaust pipe 10 relative to the downstream end 20a of the first heat insulator 20.

[0028] As shown in FIG. 3, in the overlapping portion R, the pair of heat shield plates 21, 22 are provided with step portions 23, 24 that bulge outward in the radial direction. The step portion 23 of the heat shield plate 21 is formed by one bent portion provided between the arc portion 21a and the lower end portion 21b, and one bent portion provided between the arc portion 21a and the upper end portion 21c. The step portion 24 of the heat shield plate 22 is formed by one bent portion provided between the arc portion 22a and the lower end portion 22b, and one bent portion provided between the arc portion 22a and the upper end portion 22c. As a result, between the first heat insulator 20 and the exhaust pipe 10, a gap portion S1 located between the step portions 23, 24 on the lower end portions 21b, 22b side and the exhaust pipe 10, and a gap portion S2 located between the step portions 23, 24 on the upper end portions 21c, 22c side and the exhaust pipe 10 are formed.

[0029] 3, in the overlapping portion R, the pair of heat shield plates 31, 32 are provided with stepped portions 33, 34 that bulge outward in the radial direction. The stepped portion 33 of the heat shield plate 31 is composed of two bent portions provided between the arc portion 31a and the lower end portion 31b, and two bent portions provided between the arc portion 31a and the upper end portion 31c. The stepped portion 34 of the heat shield plate 32 is composed of two bent portions provided between the arc portion 32a and the lower end portion 32b, and two bent portions provided between the arc portion 32a and the upper end portion 32c. As a result, between the first heat insulator 20 and the second heat insulator 30, a gap portion S3 is formed between the step portions 23, 24 on the lower end portions 21b, 22b side and the step portions 33, 34 on the lower end portions 31b, 32b side, and a gap portion S4 is formed between the step portions 23, 24 on the upper end portions 21c, 22c side and the step portions 33, 34 on the upper end portions 31c, 32c side.

[0030] 3 and 4, a wire mesh 40 is disposed in the gap at least in the portion on the extension direction side (here, the vertically downward side) of the extension region 19. The wire mesh 40 is formed of, for example, stainless steel. The wire mesh 40 allows liquids such as water to pass through while capturing foreign matter such as dead grass.

[0031] In this embodiment, the wire mesh 40 is disposed around the entire circumferential direction of the exhaust pipe 10, including the gap portions S3 and S4. The wire mesh 40 is disposed with a substantially constant thickness in the gap portions S3 and S4. The wire mesh 40 is disposed in a compressed state between the arc portions 21a and 22a of the heat shield plates 21 and 22 of the first heat insulator 20 and the arc portions 31a and 32a of the heat shield plates 31 and 32 of the second heat insulator 30.

[0032] When arranging the wire mesh all around the exhaust pipe 10 in the circumferential direction, including the gap portions S3 and S4, the wire mesh 40 can be joined in advance by spot welding to one of the downstream end 20a of the first heat insulator 20 and the upstream end 30a of the second heat insulator 30. In this state, the pair of heat shields 31 and 32 are arranged so as to cover the downstream end 20a of the first heat insulator 20, and the lower ends 31b and 32b and the upper ends 31c and 32c are joined by spot welding or the like, whereby the wire mesh 40 can be easily arranged all around the exhaust pipe 10 in the circumferential direction, including the gap portions S3 and S4.

[0033] In this embodiment, as shown in Fig. 3, the wire mesh 40 is divided and arranged in the circumferential direction of the exhaust pipe 10. In the example of Fig. 3, the wire mesh 40 is divided into two parts, left and right, and a pair of arc portions 40a, 40b are brought into contact with each other at positions corresponding to the gap portions S3, S4, respectively, to form a ring shape as a whole. The contact portions of the arc portions 40a, 40b may simply be in contact with each other, or may be joined by adhesion, welding, or the like.

[0034] 4, in this embodiment, the width W1 of the wire mesh 40 (width in the axial direction of the exhaust pipe 10) is equal to or larger than the overlap width W2 between the downstream end 20a of the first heat insulator 20 and the upstream end 30a of the second heat insulator 30. As a result, the wire mesh 40 is disposed all around the exhaust pipe 10 in the axial direction, including the gap portions S3 and S4, over the entire overlap portion R from the open end of the upstream end 30a of the second heat insulator 30 and protruding toward the second heat insulator 30 beyond the overlap portion R.

[0035] As described above, in the exhaust pipe insulation structure 1, the downstream end 20a of the first heat insulator 20 and the upstream end 30a of the second heat insulator 30 overlap with each other so as to form gaps S3, S4 that run along the circumferential direction of the exhaust pipe 10 and communicate with the outside. The formation of the gaps S3, S4 makes it possible to discharge water W that has accumulated in the heat insulators 20, 30 to the outside through the gaps S3, S4 (particularly the gap S3), as shown in FIG.

[0036] Furthermore, in the exhaust pipe insulation structure 1, the wire mesh 40 arranged at least in the portion of the protruding direction side of the protruding region 19 can prevent foreign matter G such as dead grass from entering the first heat insulator 20 and the second heat insulator 30 from the outside, as shown in Fig. 4. Therefore, the exhaust pipe insulation structure 1 can simultaneously drain water from inside the heat insulators 20, 30 and prevent foreign matter G from adhering to the surface of the exhaust pipe 10.

[0037] In the exhaust pipe insulation structure 1, the upstream end 30a of the second heat insulator 30 is disposed radially outward of the exhaust pipe 10 with respect to the downstream end 20a of the first heat insulator 20. With this configuration, as shown in Fig. 4, air from the outside can be taken into the heat insulators 20, 30 as cooling gas E for the exhaust pipe 10 while the vehicle is running.

[0038] In the exhaust pipe insulation structure 1, the width W1 of the wire mesh 40 is equal to or larger than the overlapping width W2 between the downstream end 20a of the first heat insulator 20 and the upstream end 30a of the second heat insulator 30. This ensures a sufficient width W1 of the wire mesh 40, and more reliably prevents foreign matter G, such as dead grass, from entering the heat insulators 20, 30 from the outside.

[0039] In the exhaust pipe thermal insulation structure 1, the wire mesh 40 is disposed around the entire circumferential direction of the exhaust pipe 10. This makes it possible to more reliably prevent foreign matter G, such as dead grass, from entering the heat insulators 20, 30 from the outside, also in the gap portion S3.

[0040] In the exhaust pipe insulation structure 1, the wire mesh 40 is divided and arranged in the circumferential direction of the exhaust pipe 10. With such a configuration, the efficiency of assembling the exhaust pipe insulation structure 1 can be improved.

[0041] The present disclosure is not limited to the above embodiment. For example, in the above embodiment, the upstream end 30a of the second heat insulator 30 is disposed radially outward of the exhaust pipe 10 relative to the downstream end 20a of the first heat insulator 20, but this arrangement may be reversed. That is, the downstream end 20a of the first heat insulator 20 may be disposed radially outward of the exhaust pipe 10 relative to the upstream end 30a of the second heat insulator 30.

[0042] The wire mesh 40 does not necessarily have to be disposed around the entire circumference of the exhaust pipe 10. For example, the wire mesh 40 may be disposed only in the gap portion S3 located on the protruding direction side of the protruding region 19. Water that accumulates in the heat insulators 20, 30 is guided to the gap portion S3 located vertically downward. Therefore, by disposing the wire mesh 40 at least in the gap portion S3, it is possible to both drain water from inside the heat insulators 20, 30 and suppress adhesion of foreign matter G to the surface of the exhaust pipe 10. In the above embodiment, the wire mesh 40 is divided into two and arranged in the circumferential direction of the exhaust pipe 10, but the number of divisions of the wire mesh 40 may be greater than this. In addition, the wire mesh 40 does not necessarily have to be divided, and a ring-shaped wire mesh 40 may be used. The width W1 of the wire mesh 40 may be less than the overlap width W2 between the downstream end 20a of the first heat insulator 20 and the upstream end 30a of the second heat insulator 30. Even in this case, the above-mentioned action and effect are sufficiently exhibited. [Explanation of symbols]

[0043] 1...insulating structure of exhaust pipe, 10...exhaust pipe, 19...projection area, 20...first heat insulator, 20a...downstream end, 30...second heat insulator, 30a...upstream end, 40...wire mesh, S3, S4...gap portion, W1...width of wire mesh, W2...overlap width.

Claims

1. A thermal insulation structure for an exhaust pipe connected to an internal combustion engine of a vehicle, The exhaust pipe has a protruding region that protrudes due to bending or bulging of the exhaust pipe, a first heat insulator covering the exhaust pipe upstream of the protruding area; a second heat insulator covering the exhaust pipe downstream of the protruding area, a downstream end of the first heat insulator and an upstream end of the second heat insulator overlap each other so as to form a gap portion that is aligned in a circumferential direction of the exhaust pipe and communicates with the outside, A wire mesh is disposed in at least a portion of the gap portion on a protruding direction side of the protruding region, the second heat insulator is divided and arranged in a circumferential direction of the exhaust pipe so that parts of the second heat insulator overlap each other, and a step portion that bulges in a radial direction of the exhaust pipe is provided at an overlapping portion between the divided parts, A thermal insulation structure for an exhaust pipe, wherein the gap portion is formed between the downstream end of the first heat insulator and the upstream end of the second heat insulator by the step portion.

2. The exhaust pipe has a connecting pipe connecting an upstream pipe and a downstream pipe, 2. The heat insulating structure of an exhaust pipe according to claim 1, wherein an overlapping portion between a downstream end of the first heat insulator and an upstream end of the second heat insulator is located radially outside the connecting pipe.

3. An insulating structure for an exhaust pipe as described in claim 1 or 2, wherein the wire mesh has a constant thickness in the gap portion and is arranged in a compressed state between the arc portion of the first insulator and the arc portion of the second insulator.

4. An insulating structure of an exhaust pipe described in any one of claims 1 to 3, wherein a lower end of the upstream end of the second heat insulator is positioned lower than a lower end of the downstream end of the first heat insulator.

5. A thermal insulation structure for an exhaust pipe connected to an internal combustion engine of a vehicle, The exhaust pipe has a protruding region that protrudes due to bending or bulging of the exhaust pipe, a first heat insulator covering the exhaust pipe upstream of the protruding area; a second heat insulator covering the exhaust pipe downstream of the protruding area, a downstream end of the first heat insulator and an upstream end of the second heat insulator overlap each other so as to form a gap portion that is aligned in a circumferential direction of the exhaust pipe and communicates with the outside, A wire mesh is disposed in at least a portion of the gap portion on a protruding direction side of the protruding region, A heat insulating structure for an exhaust pipe, wherein a width of the wire mesh is equal to or greater than an overlap width between a downstream end of the first heat insulator and an upstream end of the second heat insulator.

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