Exhaust pipe structure

Abstract

To provide an exhaust pipe structure capable of suppressing leakage of a reductant from abutting surfaces of flanges.SOLUTION: An exhaust pipe structure 1 comprises: an exhaust pipe 2; an injector 6 that introduces a reductant into the exhaust pipe 2; and a connection part K that connects an upstream side pipe 31 and a downstream side pipe 32 on the downstream side of the injector 6. In the connection part K, a flange 35 provided at a downstream side end part 33 of the upstream side pipe 31, and a flange 36 provided at an upstream side end 34 of the downstream side pipe 32 are connected via a gasket 38. The downstream side end part 33 of the upstream side pipe 31 has a protrusion portion 37 that protrudes toward the downstream side with respect to the gasket 38. The upstream side end part 34 of the downstream side pipe 32 is arranged so as to surround the outside of the protrusion portion 37.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to an exhaust pipe structure.

Background Art

[0002] As a conventional exhaust pipe structure, for example, there is one described in an exhaust gas purification device for an internal combustion engine described in Patent Document 1. This conventional exhaust gas purification device includes an exhaust pipe, a selective reduction type NOx catalyst provided in the exhaust pipe via a support member, and a reducing agent addition valve disposed in the exhaust pipe upstream of the NOx catalyst. In the exhaust pipe, a bent portion for blocking the reducing agent added from the addition valve is provided at a position between the addition valve and the NOx catalyst.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Due to factors such as the mounting space for the vehicle, in the exhaust pipe structure, a connection portion between pipes via a flange may be provided at a position between the reducing agent addition valve and the NOx catalyst. In such a connection portion, a gasket is interposed between the mating surfaces of the flanges, but it is conceivable that the reducing agent may leak from the mating surfaces of the flanges over a long period of use. If the reducing agent leaks, the reducing agent may adhere to the outer surface portion of the flange, and the appearance of the connection portion may be impaired.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide an exhaust pipe structure capable of suppressing the leakage of the reducing agent from the mating surfaces of the flanges.

Means for Solving the Problems

[0006] An exhaust pipe structure according to one aspect of the present disclosure is an exhaust pipe structure connected to an internal combustion engine of a vehicle, and includes an exhaust pipe, an injector for introducing a reducing agent into the exhaust pipe, and a connection portion that connects an upstream pipe and a downstream pipe on the downstream side of the injector. In the connection portion, a flange provided at the downstream end of the upstream pipe and a flange provided at the upstream end of the downstream pipe are joined via a gasket. The downstream end of the upstream pipe has a protruding portion that protrudes downstream of the gasket, and the upstream end of the downstream pipe is disposed so as to surround the outside of the protruding portion.

[0007] In this exhaust pipe structure, the downstream end of the upstream pipe protrudes downstream of the gasket, and the upstream end of the downstream pipe is disposed so as to surround the outside of the protruding portion. According to such a configuration, the protruding portion at the downstream end of the upstream pipe can function as a shielding member that shields the gasket from the exhaust gas flowing through the exhaust pipe. Therefore, it is possible to suppress the reducing agent flowing together with the exhaust gas from adhering to the gasket, and to prevent the reducing agent from leaking from the mating surface between the flanges due to long-term use.

[0008] In the connection portion, the downstream end of the upstream pipe and the upstream end of the downstream pipe may be a downwardly inclined portion that inclines downward toward the downstream. In this case, it is possible to suppress the reducing agent that has passed through the protruding portion from flowing into the gasket side, and the protruding portion at the downstream end of the upstream pipe can act more effectively as a shielding member.

[0009] The downstream pipe may have a bent portion that reverses the inclination direction from downward to upward on the downstream side of the downwardly inclined portion. In this case, it is possible to accumulate the reducing agent flowing together with the exhaust gas near the bent portion. In this accumulation portion, since the temperature of the exhaust pipe becomes high due to the exhaust gas, the evaporation of the reducing agent can be promoted. Therefore, it is possible to effectively suppress the reducing agent from adhering to the gasket, and to more reliably prevent the reducing agent from leaking from the mating surface between the flanges.

[0010] At the edge of the upstream end of the downstream pipe, a claw portion that bends toward the central axis side of the downstream pipe may be provided. In this case, the claw portion can more reliably suppress the reducing agent that has passed through the protruding portion from flowing around to the gasket side. Therefore, the adhesion of the reducing agent to the gasket can be more effectively suppressed, and the leakage of the reducing agent from the mating surface between the flanges can be more reliably suppressed.

Advantages of the Invention

[0011] According to the present disclosure, an exhaust pipe structure capable of suppressing the leakage of a reducing agent from the mating surface between flanges is provided.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, a preferred embodiment of the exhaust pipe structure according to one aspect of the present disclosure will be described in detail. Hereinafter, for the sake of convenience of explanation, the terms "upper" and "lower" are used based on the mounting state of the exhaust pipe to the vehicle. Also, the terms "upstream" and "downstream" are used based on the flow direction of the exhaust gas in the exhaust pipe.

[0014] FIG. 1 is a side view showing the upstream side of the exhaust pipe structure according to an embodiment of the present disclosure. FIG. 2 is a side view showing the downstream side of the exhaust pipe structure shown in FIG. 1. As shown in FIGS. 1 and 2, the exhaust pipe structure 1 is a structure in which the exhaust pipe 2 is insulated by a first heat insulator 3 and a second heat insulator 4. As shown in FIG. 1, the exhaust pipe 2 has an overhanging region 5 that protrudes vertically downward due to the bending or bulging of the exhaust pipe 2. The first heat insulator 3 is disposed so as to cover the exhaust pipe 2 on the upstream side of the overhanging region 5. The second heat insulator 4 is disposed so as to cover the exhaust pipe 2 on the downstream side of the overhanging region 5.

[0015] The exhaust pipe 2 is connected to an internal combustion engine mounted on a vehicle and constitutes an exhaust passage for discharging exhaust gas generated by combustion in the combustion chamber of the internal combustion engine. The exhaust pipe 2 extends, for example, along the longitudinal direction of the vehicle in a state of being connected to the internal combustion engine. An example of the internal combustion engine is a diesel engine. Examples of vehicles to which the exhaust pipe structure 1 is applied include passenger cars, pickup trucks, buses, dumps, and the like.

[0016] On the upstream side of the exhaust pipe 2, 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 2, for example, an SCR (Selective Catalytic Reduction) is provided. In the example of FIG. 1, an injector 6 for injecting a reducing agent (for example, aqueous urea) into the SCR is attached to the wall portion of the exhaust pipe 2.

[0017] On the upstream side of the exhaust pipe 2, as shown in FIG. 1, a connection end portion 7 and bending portions 8, 9, 10 are provided. Another exhaust pipe arranged on the upstream side (the internal combustion engine side) of the exhaust pipe 2 is connected to the connection end portion 7. A straight portion 11 extending from the connection end portion 7 is inclined downward toward the injector 6 in accordance with the piping path of the upstream exhaust pipe. The bending portion 8 bends the exhaust pipe 2 such that the downward inclination of a straight portion 12 extending downstream of the bending portion 8 is smaller than the downward inclination of the straight portion 11. The extending direction of the straight portion 12 downstream of the bending portion 8 is along the direction of the injector 50 rather than the straight portion 11.

[0018] The bending portion 9 is provided near the base end portion of the injector 6. The bending portion 9 bends the exhaust pipe 2 such that the downward inclination of a straight portion 13 downstream of the bending portion 9 is larger than the downward inclination of the straight portion 12. The straight portion 13 downstream of the bending portion 9 extends downward toward the mounting position of the injector 6. The bending portion 10 bends the exhaust pipe 2 immediately downstream of the bending portion 9 such that a straight portion 14 downstream of the injector 6 extends generally along the axial direction of the injector 6. The straight portion 14 downstream of the injector 6 extends substantially parallel to the horizontal plane.

[0019] Due to these bending portions 8, 9, 10, the piping path of the exhaust pipe 2 is a path that can avoid interference with, for example, the lower structure of the vehicle (e.g., the cross member of the suspension). Further, an injector 6 attached to inject a reducing agent toward the rear of the vehicle enables the injection of the reducing agent downstream inside the exhaust pipe 2.

[0020] The exhaust pipe 2 has an overhanging region 5 that protrudes due to the bending of the bending portion 10. That is, in the exhaust pipe 2, a certain range including the bending portion 10 is the overhanging region 5 formed by the bending of the bending portion 10. The overhanging region 5 is, as an example, a region including the point located most vertically downward (the point with the minimum ground height) in the exhaust passage including the exhaust pipe 2. A dispersion plate 15 is disposed inside the exhaust pipe 2 in the overhanging region 5.

[0021] The dispersion plate 15 has a plurality of fins that swirl the exhaust gas flowing in the exhaust pipe 2 in the circumferential direction. The dispersion plate 15 is disposed inside the exhaust pipe 2 so as to face the injector 6. In addition to the function of suppressing the variation in the exhaust oxygen concentration in the exhaust pipe 2, the dispersion plate 15 has a function of stirring and mixing the reducing agent introduced into the exhaust pipe 2 from the injector 6 with the exhaust gas.

[0022] Downstream of the straight portion 14, bending portions 16 and 17 are further provided. The bending portion 16 bends the exhaust pipe 2 such that the straight portion 18 downstream of the bending portion 16 inclines upward. The bending portion 17 bends the exhaust pipe 2 such that the straight portion 19 downstream of the bending portion inclines downward. The inclination direction of the straight portion 18 and the inclination direction of the straight portion 19 are in a reversed state at the bending portion 17.

[0023] On the downstream side of the exhaust pipe 2, as shown in FIG. 2, a connection end portion 21 and a bending portion 22 are provided. The connection end portion 21 is a portion connected to the above-described SCR. In the vicinity of the connection end portion 21, the diameter of the exhaust pipe expands toward the edge of the connection end portion 21. The bending portion 22 refracts the exhaust pipe 2 such that the straight portion 23 downstream of the bending portion 22 (on the connection end portion 21 side) inclines upward. The inclination direction of the straight portion 23 and the inclination direction of the straight portion 19 are in a reversed state at the bending portion 22.

[0024] Next, a more detailed configuration of the exhaust pipe structure 1 described above will be described. Due to relationships such as the mounting space for the vehicle, the exhaust pipe structure 1 is provided with a connection portion K that connects the upstream pipe 31 and the downstream pipe 32 on the downstream side of the injector 6. FIG. 3 is a side view showing the connection portion and the downstream side thereof. FIG. 4 is an enlarged cross-sectional view of the main part showing the vicinity of the connection portion.

[0025] As shown in FIGS. 3 and 4, the connection part K is provided at a position corresponding to the straight part 19 on the downstream side of the exhaust pipe structure 1. As described above, the straight part 19 is in a state of being inclined downward by the bent part 17. Therefore, at the connection part K, the downstream end part 33 of the upstream pipe 31 and the upstream end part 34 of the downstream pipe 32 are downward inclined parts F that are inclined downward toward the downstream side.

[0026] In the configuration of the connection part K, a flange 35 is provided at the downstream end part 33 of the upstream pipe 31. The flange 35 is provided at a position upstream by about the thickness of the flange 35 from the edge 33a of the downstream end part 33 of the upstream pipe 31. Thereby, a protruding part 37 that protrudes more than the flange 35 is formed at the downstream end part 33 of the upstream pipe 31.

[0027] A gasket 38 is provided on the outer peripheral side of the protruding part. The gasket 38 is a member that seals the mating surface P between the flanges 35 and 36 in the connection part K. The gasket 38 has sealing performance against high-temperature exhaust gas, but may not have sealing performance against liquid (here, urea water which is a reducing agent). A flange 36 corresponding to the flange 35 is provided at the upstream end part 34 of the downstream pipe 32. The flange 36 is provided at the edge 34a of the upstream end part 34 of the downstream pipe 32.

[0028] In the connection part K, the upstream pipe 31 and the downstream pipe 32 are connected by joining the flanges 35 and 36 via the gasket 38. In the connection part K, the gasket 38 is located on the mating surface P between the flanges 35 and 36, and the protruding part 37 of the downstream end part 33 of the upstream pipe protrudes more downstream than the gasket 38 and enters the inside of the upstream end part 34 of the downstream pipe 32. The upstream end part 34 of the downstream pipe 32 is arranged so as to surround the outside of the protruding part 37, and the edge 34a of the upstream end part 34 of the downstream pipe 32 is in a state of being abutted against the gasket 38.

[0029] As shown in Fig. 3, the downstream pipe 32 has the above-described bent portion 22. In the bent portion 22, the inclination direction of the exhaust pipe 2 on the downstream side of the downward inclined portion F is reversed from downward to upward. As a result, in the downstream pipe 32, a reservoir portion W for storing the reducing agent flowing together with the exhaust gas is formed near the bent portion 22. In the reservoir portion W, for example, the condensed water generated in the exhaust pipe 2 accumulates, and the reducing agent accumulates in the reservoir portion W in a state of being mixed with the condensed water. In the reservoir portion W, the evaporation of the reducing agent is promoted because the temperature of the exhaust pipe 2 becomes high due to the exhaust gas.

[0030] As described above, in the exhaust pipe structure 1, the downstream end portion 33 of the upstream pipe 31 protrudes to the downstream side of the gasket 38, and the upstream end portion 34 of the downstream pipe is arranged so as to surround the outside of the protruding portion 37. According to such a configuration, the protruding portion 37 of the downstream end portion 33 of the upstream pipe 31 can function as a shielding member for shielding the gasket 38 from the exhaust gas flowing through the exhaust pipe 2. Therefore, it is possible to suppress the adhesion of the reducing agent flowing together with the exhaust gas to the gasket 38, and to suppress the leakage of the reducing agent from the mating surface P between the flanges 35 and 36 due to long-term use.

[0031] In the exhaust pipe structure 1, since the leakage of the reducing agent is suppressed, the reducing agent does not adhere to the outer surface portion of the flanges 35 and 36, and the appearance of the connection portion K is kept good. Further, in the exhaust pipe structure 1, even when a gasket 38 having no sealing property against liquid is used, the leakage of the reducing agent from the mating surface P between the flanges 35 and 36 can be suppressed by the configuration of the connection portion K described above. This contributes to avoiding an increase in the cost of the exhaust pipe structure 1.

[0032] In the exhaust pipe structure 1, in the connection portion K, the downstream end portion 33 of the upstream pipe 31 and the upstream end portion 34 of the downstream pipe 32 form a downward inclined portion F that inclines downward toward the downstream side. With such a configuration, it is possible to suppress the reducing agent that has passed through the protruding portion 37 from flowing around to the gasket 38 side, and the protruding portion 37 of the downstream end portion 33 of the upstream pipe 31 can act more effectively as a shielding member.

[0033] In the exhaust pipe structure 1, the downstream pipe 32 has a bent portion 22 that reverses the inclination direction on the downstream side of the downward inclined portion F. As a result, it becomes possible to accumulate the reducing agent flowing together with the exhaust gas near the bent portion 22. In this accumulation portion W, since the temperature of the exhaust pipe 2 becomes high due to the exhaust gas, evaporation of the reducing agent can be promoted. Therefore, adhesion of the reducing agent to the gasket 38 can be more effectively suppressed, and leakage of the reducing agent from the mating surface P between the flanges 35 and 36 can be more reliably suppressed.

[0034] FIG. 5 is an enlarged cross-sectional view of a main part showing the vicinity of the connection portion of the exhaust pipe structure according to the modification. As shown in the figure, in the exhaust pipe structure 1 according to the modification, at the connection portion K, a claw portion 40 that bends toward the central axis side of the downstream pipe 32 is provided at the edge 34a of the upstream end portion 34 of the downstream pipe 32. The tip of the claw portion 40 may be in contact with the outer periphery of the protruding portion 37 of the downstream end portion 33 of the upstream pipe 31, or may be in a slightly separated state.

[0035] According to such a configuration, the claw portion 40 can more reliably suppress the reducing agent that has passed through the protruding portion 37 from turning toward the gasket 38 side. Therefore, adhesion of the reducing agent to the gasket 38 can be more effectively suppressed, and leakage of the reducing agent from the mating surface P between the flanges 35 and 36 can be more reliably suppressed.

Explanation of reference numerals

[0036] 1... Exhaust pipe structure, 2... Exhaust pipe, 6... Injector, 22... Bent portion, 31... Upstream pipe, 32... Downstream pipe, 33... Downstream end portion, 34... Upstream end portion, 34a... Edge, 35, 36... Flanges, 37... Protruding portion, 38... Gasket, 40... Claw portion, F... Downward inclined portion, K... Connection portion.

Claims

1. An exhaust pipe structure connected to an internal combustion engine of a vehicle, comprising: an exhaust pipe; an injector for introducing a reducing agent into the exhaust pipe; a connection part that connects an upstream pipe and a downstream pipe on the downstream side of the injector, wherein at the connection part, a flange provided at the downstream end of the upstream pipe and a flange provided at the upstream end of the downstream pipe are joined via a gasket; the downstream end of the upstream pipe has a protruding portion that protrudes downstream of the gasket; the upstream end of the downstream pipe is arranged to surround the outside of the protruding portion; the exhaust pipe has a first upward inclined portion in a part between the injector and the connection part, and a second upward inclined portion on the downstream side of the connection part.

2. The exhaust pipe structure according to claim 1, wherein at the connection part, the downstream end of the upstream pipe and the upstream end of the downstream pipe are downward inclined portions that incline downward toward the downstream side.

3. The exhaust pipe structure according to claim 2, wherein the downstream pipe has a bent portion that reverses the inclination direction from downward to upward on the downstream side of the downward inclined portion.

4. The exhaust pipe structure according to any one of claims 1 to 3, wherein a claw portion is provided at the edge of the upstream end of the downstream pipe, and the claw portion bends toward the central axis side of the downstream pipe to block the path of the gas flowing through the exhaust pipe toward the gasket.

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