JP7600949B2 - Exhaust pipe insulation structure - Google Patents

Description

This disclosure relates to a thermal insulation structure for an exhaust pipe.

As an example of a conventional exhaust pipe insulation structure, there 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 several parts in the exhaust gas flow direction, and a protective shield member is provided to cover the outer periphery of the connection part. One end side of the protective shield member is fixed to the downstream heat insulator, while the other end side of the protective shield member is not fixed to the upstream heat insulator. An overlap part with a predetermined gap is provided between the inner periphery of the protective shield member and the outer periphery of the upstream heat insulator.

JP 2019-39325 A

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

This disclosure has been made to solve the above problems, and aims to provide an exhaust pipe insulation structure that can simultaneously drain water from inside the heat insulator and prevent foreign matter from adhering to the surface of the exhaust pipe.

The exhaust pipe insulation structure according to one aspect of the present disclosure is an exhaust pipe insulation structure connected to an internal combustion engine of a vehicle, in which the exhaust pipe has a protruding region that protrudes due to bending or swelling of the exhaust pipe, and is equipped with a first heat insulator that covers the exhaust pipe upstream of the protruding region, and a second heat insulator that covers the exhaust pipe downstream of the protruding region, in which the downstream end of the first heat insulator and the upstream end of the second heat insulator overlap to form a gap portion that runs along the circumferential direction of the exhaust pipe and communicates with the outside, and in which a wire mesh is arranged at least in the portion of the gap on the protruding direction side of the protruding region.

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 runs along the circumferential direction of the exhaust pipe and communicates with the outside. The formation of this gap allows water that has accumulated inside the heat insulator to be discharged to the outside through the gap. In addition, the wire mesh arranged 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.

The upstream end of the second heat insulator may be disposed radially outward of the exhaust pipe relative to 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.

The width of the wire mesh may be equal to or greater than the overlap width between 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.

The wire mesh may be arranged around the entire circumference of the exhaust pipe. In this case, foreign matter such as dead grass can be more reliably prevented from entering the heat insulator from the outside.

The wire mesh may be divided and arranged around the circumference of the exhaust pipe. In this case, the workability of assembling the exhaust pipe's insulation structure can be improved.

This disclosure makes it possible to drain water from inside the heat insulator while preventing foreign matter from adhering to the surface of the exhaust pipe.

1 is a side view showing a heat insulating structure of an exhaust pipe according to an embodiment of the present disclosure. FIG. FIG. 2 is an enlarged perspective view of a main portion of the heat insulating structure of the exhaust pipe shown in FIG. 1 . 3 is a cross-sectional view taken along line III-III in FIG. 2. 4 is a cross-sectional view taken along line IV-IV in FIG.

Below, a preferred embodiment of an exhaust pipe insulation structure according to one aspect of the present disclosure will be described in detail with reference to the drawings. In the following description, for convenience, the terms "upper" and "lower" are used based on the state in which the exhaust pipe is attached to the vehicle. In addition, the terms "upper" and "downstream" are used based on the flow direction of exhaust gas in the exhaust pipe.

Figure 1 is a side view showing an exhaust pipe insulation structure according to one embodiment of the present disclosure. As shown in the figure, the exhaust pipe insulation structure 1 is a structure in which the exhaust pipe 10 is insulated by 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 arranged to cover the exhaust pipe 10 upstream of the protruding region 19. The second heat insulator 30 is arranged to cover the exhaust pipe 10 downstream of the protruding region 19.

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 the 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, etc.

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 (e.g., urea water) into the SCR is disposed in the exhaust pipe 10. The injector 50 is attached to the wall of the exhaust pipe 10 so as to face the upstream side of the exhaust pipe 10.

The exhaust pipe 10 has an upstream connection section 11 and bent sections 12, 13, and 14. The connection section 11 is connected to another exhaust pipe arranged on the upstream side (the internal combustion engine side) of the exhaust pipe 10. The straight section 15 extending from the connection section 11 is inclined downward toward the injector 50 to match the piping path of the upstream exhaust pipe. The bent section 12 bends the exhaust pipe 10 so that the inclination of the straight section 16 extending downstream from the bent section 12 is smaller than the inclination of the straight section 15. The extension direction of the straight section 15 downstream of the bent section 12 is more aligned with the direction of the injector 50 than the straight section 15.

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 the 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 mounting 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.

These bends 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 the cross member of the suspension). In addition, the injector 50, which is installed to inject reducing agent toward the rear of the vehicle, makes it possible to inject reducing agent downstream inside the exhaust pipe 10.

The exhaust pipe 10 has a protruding region 19 that protrudes due to the 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 the bending of the bent portion 14. As an example, the protruding region 19 is a region that includes the point located vertically lowest (the 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 arranged inside the exhaust pipe 10. The dispersion plate is arranged, for example, inside the exhaust pipe 10 so as to face the injector. The dispersion plate has the function of stirring the exhaust gas passing through the exhaust pipe 10 and suppressing the variation in the exhaust oxygen concentration inside the exhaust pipe 10.

Figure 2 is an enlarged perspective view of the main part of the exhaust pipe insulation structure 1 shown in Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3.

As shown in Figures 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. When viewed from the axial direction of the exhaust pipe 10, the first heat insulator 20 has a left-right split structure with the heat shield plates 21, 22. Similarly, when viewed from the axial direction of the exhaust pipe 10, the second heat insulator 30 has a left-right split structure with the heat shield plates 31, 32.

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

The pair of heat shields 21, 22 constituting the first heat insulator 20 each include an arc portion 21a, 22a, a lower end portion 21b, 22b, and an upper end portion 21c, 22c. The overlapping portions of the lower end portions 21b, 22b are joined, and the overlapping portions of the upper end portions 21c, 22c are joined, 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, for example, by spot welding or the like, at joining positions that take into consideration the overall vibration suppression of the first heat insulator 20.

The pair of heat shields 31, 32 constituting the second heat insulator 30 each include an arc portion 31a, 32a, a lower end portion 31b, 32b, and an upper end portion 31c, 32c. The overlapping portions of the lower end portions 31b, 32b are joined, and the overlapping portions of the upper end portions 31c, 32c are joined, so that the second heat insulator 30 is formed into a cylindrical shape. The lower end portions 31b, 32b and the upper end portions 31c, 32c are joined, for example, by spot welding or the like, at joining positions that take into consideration the overall vibration suppression of the second heat insulator 30.

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 that gaps S3, S4 are formed that run along 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 positioned so as to be radially outward of the exhaust pipe 10 relative to the downstream end 20a of the first heat insulator 20.

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 composed of 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 composed of 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 portion 21b, 22b side and the exhaust pipe 10, and a gap portion S2 located between the step portions 23, 24 on the upper end portion 21c, 22c side and the exhaust pipe 10 are formed.

As shown in Fig. 3, in the overlapping portion R, the pair of heat shields 31, 32 are provided with stepped portions 33, 34 that bulge outward in the radial direction. The stepped portion 33 of the heat shield 31 is composed of two bent portions provided between the arc portion 31a and the lower end 31b, and two bent portions provided between the arc portion 31a and the upper end 31c. The stepped portion 34 of the heat shield 32 is composed of two bent portions provided between the arc portion 32a and the lower end 32b, and two bent portions provided between the arc portion 32a and the upper end 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.

As shown in Figures 3 and 4, a wire mesh 40 is arranged 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.

In this embodiment, the wire mesh 40 is arranged around the entire circumference of the exhaust pipe 10, including the gap portions S3 and S4. The wire mesh 40 is arranged with a substantially constant thickness in the gap portions S3 and S4. The wire mesh 40 is arranged 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.

When arranging the wire mesh around the entire circumference of the exhaust pipe 10, including the gaps 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, a pair of heat shields 31 and 32 are arranged 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, so that the wire mesh 40 can be easily arranged around the entire circumference of the exhaust pipe 10, including the gaps S3 and S4.

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 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.

In this embodiment, as shown in FIG. 4, the width W1 of the wire mesh 40 (width in the axial direction of the exhaust pipe 10) is equal to or greater 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 arranged around the entire circumference of the exhaust pipe 10, including the gap portions S3 and S4, from the open end of the upstream end 30a of the second heat insulator 30 to the entire overlap portion R in the axial direction of the exhaust pipe 10, and protruding beyond the overlap portion R toward the second heat insulator 30.

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 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 gap S3), as shown in FIG. 4.

In addition, 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 inside of the first heat insulator 20 and the second heat insulator 30 from the outside, as shown in FIG. 4. Therefore, in the exhaust pipe insulation structure 1, it is possible to both drain water from inside the heat insulators 20 and 30 and prevent foreign matter G from adhering to the surface of the exhaust pipe 10.

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 relative to the downstream end 20a of the first heat insulator 20. With this configuration, as shown in FIG. 4, when the vehicle is running, air from the outside can be taken into the heat insulators 20, 30 as cooling gas E for the exhaust pipe 10.

In the exhaust pipe insulation structure 1, the width W1 of the wire mesh 40 is equal to or greater 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. This ensures that the width W1 of the wire mesh 40 is sufficient, and further ensures that foreign matter G, such as dead grass, is prevented from entering the heat insulators 20 and 30 from the outside.

In the exhaust pipe insulation structure 1, the wire mesh 40 is arranged around the entire circumference 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 and 30 from the outside, even in the gap portion S3.

In the exhaust pipe insulation structure 1, the wire mesh 40 is divided and arranged in the circumferential direction of the exhaust pipe 10. This configuration improves the assembly workability of the exhaust pipe insulation structure 1.

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.

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 disposed in the circumferential direction of the exhaust pipe 10, but the number of divisions of the wire mesh 40 may be greater than this. Moreover, 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.

1...heat insulation 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 (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 ,
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 . the exhaust pipe has a connecting pipe that connects 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 exhaust pipe insulation structure as claimed 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. The exhaust pipe insulation structure according to claim 1, wherein a lower end of an upstream end of the second heat insulator is disposed lower than a lower end of a downstream end of the first heat insulator . 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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