Exhaust system for a vehicle

Abstract

An exhaust device of a vehicle is provided. The exhaust device mounted on the vehicle includes an inner pipe (30) through which exhaust gas of an internal combustion engine flows, and an outer pipe (40a, 40b) provided on an outer periphery of a portion of the inner pipe (30). An end portion (52) of the outer pipe (40a, 40b) is formed to have a smaller diameter than the other portion of the outer pipe (40a, 40b), and is fixed to an outer peripheral surface of the inner pipe (30). A region of the outer pipe (40a, 40b) from another end portion (54) to a vicinity of the end portion (52) is a free region (50) separated from the outer peripheral surface of the inner pipe (30).

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Japanese Patent Application No. 2022-039105, filed on March 14, 2022, the entire contents of which, including the description, claims, drawings and abstract, are incorporated herein by reference. Technical Field

[0003] This disclosure relates to an exhaust system for a vehicle, and more particularly to an exhaust pipe section having an outer pipe disposed on the outer periphery of an inner pipe through which exhaust gases from an internal combustion engine flow. Background Technology

[0004] A dual-structure exhaust pipe has been known for some time, comprising an inner pipe for the flow of exhaust gases from a vehicle's internal combustion engine, and an outer pipe spaced apart from the outer periphery of the inner pipe. Patent Document 1 discloses a structure in which the exhaust gases are delivered to an exhaust purification device while maintaining a high temperature. The exhaust purification device includes a catalyst for purifying the exhaust gases, and the catalyst is activated by passing the high-temperature exhaust gases through it, thereby improving the purification efficiency of the exhaust gases achieved by the catalyst.

[0005] Furthermore, the dual-structure exhaust pipe also provides the effect of preventing the heat from exhaust gases from being transferred to the surrounding structures.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2010-144710 Summary of the Invention

[0009] When an outer tube is installed on the outer circumference of a portion of the inner tube, a structure is considered to reduce the diameter of both ends of the outer tube in its extension direction and fix these two ends to the outer circumferential surface of the inner tube in order to hold the outer tube relative to the inner tube. However, the inner tube becomes hot due to the flow of exhaust gas inside, making it prone to stretching due to thermal expansion. On the other hand, the outer tube, not being in direct contact with the exhaust gas, is less likely to become hot compared to the inner tube, and therefore less prone to stretching due to thermal expansion. Therefore, due to the difference in stretching between the inner and outer tubes, there is a possibility that the fixing parts at both ends of the outer tube, which are fixed to the inner tube, may peel off.

[0010] The purpose of this disclosure is to prevent the peeling off of the fixing part that fixes the outer tube to the inner tube in an exhaust device in which an outer tube is provided on the outer periphery of a part of the inner tube.

[0011] The exhaust system of the vehicle disclosed herein is an exhaust system mounted on a vehicle, characterized in that it comprises: an inner pipe for supplying exhaust gases from an internal combustion engine; and an outer pipe disposed on the outer periphery of a portion of the inner pipe, one end of the outer pipe being formed to have a smaller diameter compared to the other portions of the outer pipe and being fixed to the outer peripheral surface of the inner pipe, wherein the region of the outer pipe from the other end to near the first end becomes a free region separated from the outer peripheral surface of the inner pipe.

[0012] In the exhaust system of the vehicle disclosed herein, a sliding mesh may also be provided between the inner circumferential surface of the free region of the outer pipe and the outer circumferential surface of the inner pipe.

[0013] In the exhaust system of the vehicle disclosed herein, the outer pipe may also be provided on the outer periphery of the inner pipe located at the front side of the vehicle where the battery pack is mounted on the vehicle.

[0014] In the exhaust device of the vehicle disclosed herein, the inner pipe may be configured such that, from the upstream side to the downstream side in the direction of exhaust gas flow, it sequentially includes an upstream straight portion, a flexural portion, and a downstream straight portion, and one end of the outer pipe is fixed to the outer peripheral surface of the downstream portion of the upstream straight portion of the inner pipe, and the free region of the outer pipe extends across at least a portion of the flexural portion of the inner pipe and the downstream straight portion of the inner pipe.

[0015] In the exhaust system of the vehicle involved in this disclosure, the inner pipe may also be formed by connecting multiple inner pipe sections together, and one end of the outer pipe and the joint of the two inner pipe sections are aligned and welded together.

[0016] According to this disclosure, since the fixing part of the outer tube that is fixed to the inner tube is only one point in the extension direction of the outer tube, even if the extension difference between the inner tube and the outer tube is generated due to thermal expansion, the peeling of the fixing part can be suppressed. Attached Figure Description

[0017] Figure 1 This is a top view showing the exhaust system of the vehicle according to the embodiment.

[0018] Figure 2 An enlarged top view of the exhaust pipe section used for heat damage countermeasures.

[0019] Figure 3 for Figure 1 AA sectional view.

[0020] Figure 4 is a B-B sectional view of the exhaust pipe portion for the countermeasure against heat damage. Figure 1

[0021] Figure 5 is a sectional view of a portion of the exhaust pipe portion for the countermeasure against heat damage, which is related to another embodiment.

[0022] Figure 6 is a plan view of the exhaust pipe portion for the countermeasure against heat damage, which is related to a comparative technique. DETAILED DESCRIPTION

[0023] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings. The structures described hereinafter are examples for explanation, and can be appropriately changed in accordance with the specifications of a vehicle, and the like. In the case where a plurality of embodiments and modified examples, and the like are described hereinafter, initially, a case where features thereof are appropriately combined and used is assumed. In all the drawings, the same symbols are attached to the same elements, and overlapping description is omitted.

[0024] In each drawing, the direction of the arrow mark FR indicates the front of the vehicle, the direction of the arrow mark UP indicates the upper of the vehicle, and the direction of the arrow mark RH indicates the right of the vehicle. Further, in the following description, the upstream and the downstream indicate the upstream and the downstream of the direction in which exhaust gas of an internal combustion engine flows.

[0025] Figure 1 is a plan view of the exhaust device 10 related to the embodiment. In Figure 1 , the direction in which exhaust gas flows is indicated by an arrow mark with hatching. The exhaust device 10 is mounted on a hybrid vehicle. The hybrid vehicle is an automobile in which an internal combustion engine and an electric motor (both not shown) are used as driving sources. The electric motor is supplied with electric power from a battery pack 90, and thereby driven.

[0026] Exhaust gas discharged from the internal combustion engine flows through the exhaust device 10 shown in Figure 1 , and is discharged to the outside of the vehicle. The exhaust device 10 successively has a catalyst device 14, a sub-muffler 16, an exhaust pipe portion 18 for the countermeasure against heat damage, and a main muffler 20 from the upstream toward the downstream. The exhaust pipe portion 18 for the countermeasure against heat damage is a characteristic portion of the present embodiment.

[0027] According to the situation of the space in the vehicle cabin, and the like, it is necessary to arrange the battery pack 90 in the vicinity of the exhaust device 10 as shown in Figure 1 . Since exhaust gas at a high temperature flows through the exhaust device 10, the surroundings of the exhaust device 10 become hot. In order to reduce the heat from the exhaust device 10 to the battery pack 90, the exhaust pipe portion 18 for the countermeasure against heat damage is provided. ​

[0028] Figure 2 An enlarged plan view of the exhaust pipe portion 18 for a heat damage countermeasure. The exhaust pipe portion 18 is provided with an inner pipe 30 through which exhaust gas flows, and two outer pipes 40a, 40b provided on the outer periphery of the inner pipe 30. The inner pipe 30 and the outer pipes 40a, 40b are cylindrical and are stainless steel members.

[0029] The inner pipe 30 is provided with, in order from the upstream toward the downstream, a straight portion 70a, a bent portion 72a, a straight portion 70b, a bent portion 72b, and a straight portion 70c. The outer pipes 40a, 40b have an L shape. The outer pipe 40a is welded to the outer peripheral surface of the straight portion 70a and extends across the bent portion 72a and a portion of the straight portion 70b. The outer pipe 40b is welded to the outer peripheral surface of the straight portion 70b and extends across the bent portion 72b and a portion of the straight portion 70c. Since the outer pipe 40a and its periphery, and the outer pipe 40b and its periphery have the same structure, hereinafter, the outer pipe 40a and its periphery will be described as representatives of them.

[0030] Figure 3 An A-A sectional view of Figure 1 In Figure 3 , the direction in which the exhaust gas flows is shown by a hollow arrow mark. As Figure 3 indicated, the inner pipe 30 is formed by connecting a plurality of inner pipe segments 30S1, 30S2, 30S3 together. The members are connected together by welding at a joint 34C1 at which the downstream side end portion of the inner pipe segment 30S1 and the upstream side end portion of the inner pipe segment 30S2 meet. The members are connected together by welding at a joint 34C2 at which the downstream side end portion of the inner pipe segment 30S2 and the upstream side end portion of the inner pipe segment 30S3 meet. In addition, the joints 34C1, 34C2 can be connected by means other than welding.

[0031] The outer pipe 40a is provided, in order from the upstream toward the downstream, with a narrow pipe region 42, a transition region 46, and a main body region 48. The narrow pipe region 42 is a region that is formed to have a smaller (narrower) diameter than the other portions of the outer pipe 40a and that meets the outer peripheral surface of the inner pipe 30. The transition region 46 is a region in which the diameter changes from the upstream toward the downstream. The main body region 48 is a region that extends with a constant diameter.

[0032] The narrow pipe region 42 (the upstream side end portion 52) of the outer pipe 40a is aligned with the joint 34C1 of the two inner pipe sections 30S1, 30S2 and is collectively welded together. Thus, the narrow pipe region 42 of the outer pipe 40a is fixed to the outer peripheral surface of the inner pipe 30, thereby forming a fixed portion 60. In addition, by collectively welding the joint 34C1 of the inner pipe sections and the outer pipe 40a, it is possible to reduce the manufacturing man-hours. The transition region 46 and the main body region 48 of the outer pipe 40a become free regions 50 that are separated from the outer peripheral surface of the inner pipe 30.

[0033] An annular sliding net 62 is provided between the inner peripheral surface of the free region 50 of the outer pipe 40a and the outer peripheral surface of the inner pipe 30. The sliding net 62 is a member in which a cable material is woven into a net shape. The sliding net 62 is fixed to only one of the outer peripheral surface of the inner pipe 30 and the inner peripheral surface of the outer pipe 40a and is able to slide with respect to the other. Thus, the sliding net 62 is able to move in the axial direction of the pipe when a difference in thermal expansion is generated between the inner pipe 30 and the outer pipe 40a. By the sliding net 62, the free region 50 of the outer pipe 40a is supported by the inner pipe 30.

[0034] Figure 4 For Figure 1 a B-B sectional view. In the vehicle, a heat insulator 80 is provided between the exhaust pipe portion 18 and the battery pack 90. In addition, the heat insulator 80 is omitted in the other drawings.

[0035] Next, the effects of the exhaust device 10 of the present embodiment will be described.

[0036] According to the above-described embodiment, as shown in Figure 1 , the outer pipes 40a, 40b are provided on the outer periphery of the inner pipe 30 in the portion of the exhaust device 10 in the vicinity of the battery pack 90. Therefore, it is possible to reduce the convective heat (heat transferred via air) and the radiant heat (heat transferred by infrared rays) from the exhaust device 10 to the battery pack 90, thereby making it possible to reduce the atmospheric temperature around the battery pack 90. As shown in Figure 1 , although in the case where the exhaust device 10 is located in front of the battery pack 90 in the vehicle, the heat of the exhaust device 10 is easily blown onto the battery pack 90 by the running wind of the vehicle, according to the above-described embodiment, it is possible to effectively reduce the heat. Since the outer pipes 40a, 40b cover the entire periphery of the inner pipe 30, the heat insulating performance is high, and the heat damage countermeasure effect is large.

[0037] Further, the above-described embodiment is not limited to the case where the outer pipes 40a, 40b are provided on the outer periphery of the inner pipe 30 in the portion of the exhaust device 10 in the vicinity of the battery pack 90. For example, as shown in Figure 3As shown, only the upstream side end portion 52 of the outer tube 40a is fixed to the outer peripheral surface of the inner tube 30, and the region (transition region 46 and main body region 48) of the outer tube 40a from the downstream side end portion 54 to the vicinity of the upstream side end portion 52 becomes a free region 50 that is separated from the outer peripheral surface of the inner tube 30. Therefore, in the case where the inner tube 30 is stretched more than the outer tube 40a (a difference in the stretch between the inner tube 30 and the outer tube 40a is generated) due to the flow of high-temperature exhaust gas through the inner tube 30, peeling of the fixed portion 60 of the outer tube 40a that is fixed to the inner tube 30 can be suppressed.

[0038] Further, according to the above-described embodiment, since the space between the outer tube 40a and the inner tube 30 does not become a structure that is connected to the inside of the inner tube 30, water or the like that enters the space does not flow into the inner tube 30. For example, as Figure 3 As shown in the modified structure of the exhaust pipe portion 18, by providing a gap between the inner tube segments 30S2, 30S3 and connecting the downstream side end portion 54 of the outer tube 40a to the inner tube segment 30S3, it is possible to become a structure that connects the space between the outer tube 40a and the inner tube 30 to the inside of the inner tube 30. However, in such a modified structure, water generated by the combustion of fuel by the internal combustion engine can remain in the space between the outer tube 40a and the inner tube 30, and thereafter, since the water in the space flows to the downstream side of the inner tube 30 and freezes, there is a risk of clogging the inside of the inner tube 30. However, as with the above-described embodiment, by making the space between the outer tube 40a and the inner tube 30 a structure that is independent of the inside of the inner tube 30, it is possible to eliminate such a risk.

[0039] Further, the above-described embodiment is as Figure 2 As shown, the outer tube 40a is fixed at the downstream side portion of the straight portion 70a of the inner tube 30, and the outer tube 40b is fixed at the downstream side portion of the straight portion 70b of the inner tube 30. Here, the downstream side portion of the straight portion 70a refers to a region of one-half on the downstream side in the entire straight portion 70a. The same structure applies to the straight portion 70b. With such a structure, when the inner tube 30 that is inside the outer tubes 40a, 40b is stretched due to thermal expansion, it is possible to suppress the case where the outer peripheral surface of the flexure portions 72a, 72b (inner tube) comes into contact with the inner peripheral surface of the outer tubes 40a, 40b. In relation to this, the outer tube 40b will be described below as an example.

[0040] As shown in the modified structure of the exhaust pipe portion 18, by providing a gap between the inner tube segments 30S2, 30S3 and connecting the downstream side end portion 54 of the outer tube 40a to the inner tube segment 30S3, it is possible to become a structure that connects the space between the outer tube 40a and the inner tube 30 to the inside of the inner tube 30. However, in such a modified structure, water generated by the combustion of fuel by the internal combustion engine can remain in the space between the outer tube 40a and the inner tube 30, and thereafter, since the water in the space flows to the downstream side of the inner tube 30 and freezes, there is a risk of clogging the inside of the inner tube 30. However, as with the above-described embodiment, by making the space between the outer tube 40a and the inner tube 30 a structure that is independent of the inside of the inner tube 30, it is possible to eliminate such a risk. Figure 2 As shown, the upstream side end portion of the outer tube 40b is fixed at the downstream side portion of the straight portion 70b (upstream side straight portion), and thus the distance L from the fixed portion 60 to the flexure portion 72b is short. The free region of the outer tube 40b extends across the flexure portion 72b and a portion of the straight portion 70c (downstream side straight portion).

[0041] Figure 6 A plan view of another exhaust pipe portion 118 as a comparative technique is shown. In the comparative technique, a shorter outer pipe 140a is provided at the upstream side, and a longer outer pipe 140b (corresponding to the outer pipe 40b of the present application) is provided at the downstream side. The upstream side end portion of the outer pipe 140b is fixed at the upstream side portion of the straight portion 70b (a region of the half on the upstream side in the entire straight portion 70b), so that the distance L from the fixed portion 60 to the bent portion 72b is longer. Figure 2

[0042] As shown in FIG. 6, since the extension amount of the inner pipe 30 caused by thermal expansion from the fixed portion 60 to the bent portion 72b is increased in the case where the distance L is longer, the possibility that the outer peripheral surface of the inner pipe 30 comes into contact with the inner peripheral surface of the outer pipe 40b at the portion indicated by the symbol R is increased. When the outer peripheral surface of the inner pipe 30 comes into contact with the inner peripheral surface of the outer pipe 40b, there is a risk that the fixed portion 60 is peeled off by the shear stress applied to the fixed portion 60 at the outer pipe 40b. Figure 6 Figure 6 Figure 2 As shown in FIG. 6, since the extension amount of the inner pipe 30 caused by thermal expansion from the fixed portion 60 to the bent portion 72b is increased in the case where the distance L is longer, the possibility that the outer peripheral surface of the inner pipe 30 comes into contact with the inner peripheral surface of the outer pipe 40b at the portion indicated by the symbol R is increased. When the outer peripheral surface of the inner pipe 30 comes into contact with the inner peripheral surface of the outer pipe 40b, there is a risk that the fixed portion 60 is peeled off by the shear stress applied to the fixed portion 60 at the outer pipe 40b. Figure 2 Figure 6 Figure 6

[0043] Next, a modification example will be described. In the embodiment described above, as shown in FIG. 6, the upstream side end portion 52 of the outer pipe 40a is fixed to the outer peripheral surface of the inner pipe 30, and the region of the outer pipe 40a from the downstream side end portion 54 to the vicinity of the upstream side end portion 52 becomes the free region 50. However, as shown in FIG. 7, it is also possible to provide a structure in which the downstream side end portion 54 of the outer pipe 40a is fixed to the outer peripheral surface of the inner pipe 30 and the region of the outer pipe 40a from the upstream side end portion 52 to the vicinity of the downstream side end portion 54 becomes the free region 50 (exhaust pipe portion 18A). Figure 3 Figure 5

[0044] ​​​​​​​​Further, in the above-described embodiment, the exhaust pipe portion 18 for the heat damage countermeasure is provided with respect to the battery pack 90. However, the exhaust pipe portion 18 for the heat damage countermeasure can be provided with respect to other members such as a fuel tank.

[0045] Further, in the above-described embodiment, the outer pipe 40a (or 40b) is arranged on the outer periphery of the inner pipe 30 to provide the exhaust pipe with a double structure. However, two or more outer pipes can be arranged on the outer periphery of the inner pipe 30 in a manner to be spaced apart in the radial direction to provide the exhaust pipe with a triple or more structure.

Claims

1. An exhaust system for a vehicle, mounted on a vehicle, characterized in that, have: The inner pipe is for the flow of exhaust gases from the internal combustion engine; An outer tube, which is disposed on the outer periphery of a portion of the inner tube, One end of the outer tube is formed to have a smaller diameter compared to the rest of the outer tube, and is fixed to the outer circumferential surface of the inner tube. The region of the outer tube from one end to the front of the other end becomes a free region separated from the outer circumferential surface of the inner tube. The outer tube has a corner on its inner surface between one end and the proximal end. The inner tube is formed by connecting multiple inner tube sections together. At the joint between the two inner tube sections, a double inner tube section is provided, which overlaps a portion of one inner tube section with a portion of the other inner tube section. One end of the outer tube is fixed to the outer circumferential surface of the double inner tube. The corner of the outer tube is positioned such that the position of the corner of the outer tube in the direction in which the inner tube extends coincides with the position of the end portion of the inner tube segment extending in the opposite direction to the direction in which the free region of the outer tube extends relative to the double inner tube.

2. The exhaust system for a vehicle as described in claim 1, characterized in that, A sliding mesh is provided between the inner circumferential surface of the free region of the outer tube and the outer circumferential surface of the inner tube.

3. The exhaust system for a vehicle as described in claim 1, characterized in that, The outer tube is provided on the outer periphery of the inner tube located at the front side of the vehicle where the battery pack is mounted on the vehicle.

4. The vehicle exhaust system as described in claim 2, characterized in that, The outer tube is provided on the outer periphery of the inner tube located at the front side of the vehicle where the battery pack is mounted on the vehicle.

5. The exhaust system for a vehicle as described in claim 1, characterized in that, The inner tube, from the upstream side of the exhaust gas flow direction to the downstream side, sequentially includes an upstream straight section, a flexible section, and a downstream straight section. One end of the outer tube is fixed to the outer circumferential surface of the downstream portion of the upstream straight section of the inner tube. The free region of the outer tube extends across at least a portion of the flexural portion of the inner tube and the downstream straight portion of the inner tube.

6. The exhaust system for a vehicle as described in claim 2, characterized in that, The inner tube, from the upstream side of the exhaust gas flow direction to the downstream side, sequentially includes an upstream straight section, a flexible section, and a downstream straight section. One end of the outer tube is fixed to the outer circumferential surface of the downstream portion of the upstream straight section of the inner tube. The free region of the outer tube extends across at least a portion of the flexural portion of the inner tube and the downstream straight portion of the inner tube.

7. The exhaust system for a vehicle as described in claim 3, characterized in that, The inner tube, from the upstream side of the exhaust gas flow direction to the downstream side, sequentially includes an upstream straight section, a flexible section, and a downstream straight section. One end of the outer tube is fixed to the outer circumferential surface of the downstream portion of the upstream straight section of the inner tube. The free region of the outer tube extends across at least a portion of the flexural portion of the inner tube and the downstream straight portion of the inner tube.

8. The exhaust system for a vehicle as described in claim 4, characterized in that, The inner tube, from the upstream side of the exhaust gas flow direction to the downstream side, sequentially includes an upstream straight section, a flexible section, and a downstream straight section. One end of the outer tube is fixed to the outer circumferential surface of the downstream portion of the upstream straight section of the inner tube. The free region of the outer tube extends across at least a portion of the flexural portion of the inner tube and the downstream straight portion of the inner tube.

9. The exhaust system of a vehicle as described in any one of claims 1 to 8, characterized in that, One end of the outer tube and the joint of the two inner tube sections are aligned and welded together.

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