Engine exhaust system

Abstract

To provide an exhaust system for engines, the exhaust system being capable of suppressing occurrence of booming noises of a vehicle body by suppressing deformations of bent parts of an exhaust pipe, while enhancing engine torque by using exhaust pulsation.SOLUTION: An exhaust system 1 includes: a silencer 14; an exhaust pipe 11; a pre-silencer 16; and a reinforcement member 17. The exhaust pipe 11 comprises: an upstream side exhaust pipe 12 connecting between an engine 20 and the pre-silencer 16; and a downstream side exhaust pipe 13 connecting between the pre-silencer 16 and the silencer 14. The upstream side exhaust pipe 12 has a bent part 12a (part A). The reinforcement member 17 has: fixation parts to be fixed to each stem on an upstream side and a downstream side of the bent part; and a bridge part bridging between the fixation parts. The bridge part of the reinforcement member 17 is arranged inside of bending of the bent part 12a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exhaust system for an engine, and more particularly to an exhaust system including an exhaust pipe having a bent portion. [Background technology]

[0002] A vehicle engine is equipped with an exhaust system that directs exhaust gases emitted from the engine to the rear of the vehicle. The engine exhaust system includes an exhaust pipe attached to an exhaust manifold and extending to the rear of the vehicle, and a silencer located at the rear of the vehicle and connected to the exhaust pipe.

[0003] Furthermore, in recent years, there has been a demand for further reduction in exhaust noise. To meet this demand, some engine exhaust systems are equipped with a pre-silencer that is inserted midway along the length of the exhaust pipe. An engine exhaust system equipped with such a pre-silencer is disclosed in Patent Document 1.

[0004] The engine exhaust system disclosed in Patent Document 1 includes an upstream exhaust pipe that connects an exhaust manifold and a silencer with a pre-silencer inserted therebetween, and a downstream exhaust pipe that connects the silencer and a tailpipe. In the engine exhaust system disclosed in Patent Document 1, the upstream exhaust pipe and the downstream exhaust pipe are connected by a plate-shaped rigid connector near the location where the silencer is located. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 61-102314 Summary of the Invention [Problem to be solved by the invention]

[0006] In the exhaust system equipped with the above-described pre-silencer, research and development has been conducted on increasing the length of the exhaust pipe in order to improve engine torque by utilizing exhaust pulsation. To achieve this, a structure with a bent portion in the exhaust pipe is adopted. By providing a bent portion in the exhaust pipe, the exhaust pipe length can be made longer than that of a straight exhaust pipe.

[0007] However, when a bent portion is provided in the exhaust pipe, the vibration level of the exhaust pipe increases when the engine is running, which can result in a noticeable booming noise in the vehicle body. As a result of extensive research by the present inventors into the relationship between the provision of a bent portion in the exhaust pipe and the generation of the booming noise in the vehicle body, they have discovered that the cause is thermal expansion (thermal elongation) of the exhaust pipe due to the heat of the exhaust gas passing through the exhaust pipe, which causes deformation of the bent portion.

[0008] The present invention is based on the above-mentioned research results, and aims to provide an engine exhaust device that can improve engine torque using exhaust pulsation while suppressing deformation of the bent parts in the exhaust pipe, thereby reducing the generation of muffled noise in the vehicle body. [Means for solving the problem]

[0009] An engine exhaust system according to one aspect of the present invention includes a silencer, an exhaust pipe, and a structure. The silencer is disposed under a floor of a vehicle body at a position spaced apart from the engine. The exhaust pipe connects the engine and the silencer and serves as a path for exhaust gas. The structure has an expanded section that is provided midway along the length of the exhaust pipe and has a larger diameter than the exhaust pipe.

[0010] In the engine exhaust device of this aspect, the exhaust pipe has an upstream exhaust pipe arranged in the path between the engine and the structure, and a downstream exhaust pipe arranged in the path between the structure and the silencer, and at least one of the upstream exhaust pipe and the downstream exhaust pipe has a bent portion bent in a V shape.

[0011] The exhaust system for an engine according to this aspect further includes a reinforcing member having an upstream fixing part fixed to an upstream pipe section upstream of the bent portion of the at least one exhaust pipe, a downstream fixing part fixed to a downstream pipe section downstream of the bent portion of the at least one exhaust pipe, and a bridging part connecting the upstream fixing part and the downstream fixing part and bridging the inside of the bend in the bent portion between the upstream pipe section and the downstream pipe section. The reinforcing member has a pair of side wall portions that face each other so as to sandwich the upstream pipe portion and the downstream pipe portion in the radial direction, and each of which is formed to extend across both fixing portions, and a base wall portion that is continuous with the pair of side wall portions so as to connect the respective end edges of the pair of side wall portions, and is formed to extend from the upstream fixing portion to the downstream fixing portion.

[0012] In the engine exhaust device according to the above aspect, a bent portion is formed in at least one of the exhaust pipes (hereinafter referred to as the "one exhaust pipe"). Therefore, the length of the one exhaust pipe (exhaust pipe length) can be adjusted by forming the bent portion, and the negative pressure wave generated by exhaust pulsation during the valve overlap period when both the intake valve and exhaust valve of the engine are open can be made to reach the exhaust port. Therefore, in the engine exhaust device according to the above aspect, residual gas in the cylinder can be scavenged in the desired engine rotation range, and engine torque can be improved by increasing volumetric efficiency.

[0013] Furthermore, the exhaust system for an engine according to the above aspect includes a reinforcing member having a bridging portion that bridges the bent portion of the one exhaust pipe on the inside of the bend, so that deformation of the bent portion can be suppressed even if the one exhaust pipe undergoes thermal expansion (thermal elongation) due to a temperature rise caused by the flow of exhaust gas. Therefore, the exhaust system for an engine according to the above aspect can suppress the generation of muffled noise in the vehicle body that is caused by deformation of the bent portion of the one exhaust pipe.

[0015] Also, The engine exhaust device according to the above aspect employs a reinforcing member having a U-shaped cross section, which is formed by a pair of side wall portions and a base wall portion being continuous. This allows for a larger cross-sectional modulus than when a reinforcing member made of a flat plate is employed, and deformation of the bent portion can be suppressed while preventing increases in weight and manufacturing costs.

[0016] In the engine exhaust device according to the above aspect, the pair of side wall portions of the reinforcing member may be formed so that the distance between them increases as they move from the side where the base wall portion continues to the other end edge side on the opposite side.

[0017] In the engine exhaust device according to the above aspect, the reinforcing member is configured so that the distance between the pair of side wall portions in the reinforcing member increases as it moves from the side where the base wall portion is continuous to the other end edge on the opposite side. Therefore, compared to a configuration in which the pair of side wall portions are parallel, the reinforcing member can be attached to one of the exhaust pipes without being formed with high dimensional precision.

[0018] In the engine exhaust device relating to the above aspect, the pair of side wall portions of the reinforcing member may have a portion in the longitudinal direction, in the bridging portion, formed so that the distance between the other end edges on the opposite side to the side where the base wall portion is continuous is wider than at other portions.

[0019] In the engine exhaust device according to the above aspect, the reinforcing member is configured so that the bridging portion of the reinforcing member has a portion (widened portion) where the distance between the other end sides is wider than other portions, so even if the distance between the upstream pipe portion and the downstream pipe portion tends to increase due to thermal expansion (thermal elongation) of the one exhaust pipe, the expansion can be absorbed by deformation of the widened portion of the reinforcing member. Therefore, in the engine exhaust device according to the above aspect, even if the one exhaust pipe tends to expand due to thermal expansion caused by the flow of exhaust gas, the reinforcing member can suppress deformation of the bent portion while suppressing release of the fixation between the reinforcing member and the one exhaust pipe.

[0020] In the engine exhaust device according to the above aspect, the base wall portion may be formed in a curved or bent shape so as to protrude in a direction opposite to the bending direction of the bent portion.

[0021] In the engine exhaust device according to the above aspect, the base wall portion of the reinforcing member is configured with a curved or other shape as described above. Therefore, even if the one pipe undergoes thermal expansion due to the flow of exhaust gas as described above, it is possible to prevent the fixing of the fixing portion of the reinforcing member to the upstream pipe portion and the downstream pipe portion of the one exhaust pipe from coming loose due to deformation of the base wall portion.

[0022] In the engine exhaust device according to the above aspect, the base wall portion may be arranged at each of the upstream fixing portion and the downstream fixing portion so that a gap is formed between the base wall portion and the outer peripheral surfaces of the upstream pipe portion and the downstream pipe portion.

[0023] In the engine exhaust system according to the above aspect, the base wall of each of the upstream and downstream fixed portions of the reinforcing member is disposed so as to leave a gap with respect to the outer circumferential surface of the first exhaust pipe, so that even if a foreign object such as a pebble gets between the base wall of the reinforcing member and the first exhaust pipe, the foreign object can be expelled through the gap, thereby suppressing noise caused by the pebble or other foreign object colliding with the reinforcing member or the first exhaust pipe.

[0024] In the engine exhaust device according to the above aspect, the reinforcing member may be formed by bending a metal plate material.

[0025] The engine exhaust device according to the above aspect employs a reinforcing member formed by bending a metal plate, which is advantageous in suppressing deformation of the bent portion due to thermal expansion of the exhaust pipe while suppressing increases in weight and manufacturing costs.

[0026] In the engine exhaust system according to the above aspect, the structure may be a pre-silencer, and the bent portion may be formed in at least the upstream exhaust pipe.

[0027] The engine exhaust device according to the above aspect employs a pre-silencer as a structure having an expanded pipe portion, and employs a configuration in which a bent portion is formed in the upstream exhaust pipe. However, since a reinforcing member is attached to the bent portion of the upstream exhaust pipe, it is possible to reduce exhaust noise and improve engine torque while suppressing deformation of the bent portion, thereby suppressing the generation of muffled noise in the vehicle body. An engine exhaust system according to another aspect of the present invention includes a silencer, an exhaust pipe, and a structure. The silencer is disposed under a vehicle floor at a position spaced apart from the engine. The exhaust pipe connects the engine and the silencer and is a path for exhaust gas. The structure has an expanded section that is provided midway along the length of the exhaust pipe and has a larger diameter than the exhaust pipe. In the engine exhaust device of this aspect, the exhaust pipe has an upstream exhaust pipe arranged in the path between the engine and the structure, and a downstream exhaust pipe arranged in the path between the structure and the silencer, and at least one of the upstream exhaust pipe and the downstream exhaust pipe has a bent portion bent in a V shape. The exhaust system for an engine according to this aspect further includes a reinforcing member having an upstream fixing part fixed to an upstream pipe section upstream of the bent portion of the at least one exhaust pipe, a downstream fixing part fixed to a downstream pipe section downstream of the bent portion of the at least one exhaust pipe, and a bridging part connecting the upstream fixing part and the downstream fixing part and bridging the inside of the bend in the bent portion between the upstream pipe section and the downstream pipe section. In the engine exhaust system according to this aspect, the structure is a pre-silencer, and the bent portion is formed in at least the upstream exhaust pipe. In the engine exhaust device according to the above aspect, a bent portion is formed in at least one of the exhaust pipes (hereinafter referred to as the "one exhaust pipe"). Therefore, the length of the one exhaust pipe (exhaust pipe length) can be adjusted by forming the bent portion, and the negative pressure wave generated by exhaust pulsation during the valve overlap period when both the intake valve and exhaust valve of the engine are open can be made to reach the exhaust port. Therefore, in the engine exhaust device according to the above aspect, residual gas in the cylinder can be scavenged in the desired engine rotation range, and engine torque can be improved by increasing volumetric efficiency. Furthermore, the exhaust system for an engine according to the above aspect includes a reinforcing member having a bridging portion that bridges the bent portion of the one exhaust pipe on the inside of the bend, so that deformation of the bent portion can be suppressed even if the one exhaust pipe undergoes thermal expansion (thermal elongation) due to a temperature rise caused by the flow of exhaust gas. Therefore, the exhaust system for an engine according to the above aspect can suppress the generation of muffled noise in the vehicle body that is caused by deformation of the bent portion of the one exhaust pipe. Furthermore, in the exhaust device for the engine according to the above aspect, a pre-silencer is used as a structure having an expanded pipe portion, and a configuration is adopted in which a bent portion is formed in the upstream exhaust pipe. However, since a reinforcing member is attached to the bent portion of the upstream exhaust pipe, it is possible to reduce exhaust noise and improve engine torque while suppressing deformation of the bent portion, thereby suppressing the generation of muffled noise in the vehicle body. [Effects of the Invention]

[0028] The engine exhaust device according to each of the above aspects can improve engine torque by using exhaust pulsation, while suppressing deformation of the bent portion of the exhaust pipe, thereby suppressing the generation of muffled noise in the vehicle body. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic diagram showing the configuration of a vehicle to which an exhaust system for an engine according to an embodiment is applied; [Figure 2] FIG. 2 is an enlarged view showing a part A in FIG. [Figure 3] FIG. 4 is a plan view showing a partial configuration of a reinforcing member. [Figure 4] FIG. 4 is a side view showing the configuration of a reinforcing member. [Figure 5] FIG. 4 is a plan view showing the configuration of a reinforcing member. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of an exhaust device for an engine according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for the essential configuration.

[0031] In the drawings used in the following description, "FR" indicates the front of the vehicle, "RR" indicates the rear of the vehicle, "LH" indicates the left side of the vehicle, and "RH" indicates the right side of the vehicle.

[0032] 1. Exhaust system 10 for engine 20 An exhaust device 10 for an engine 20 according to an embodiment will be described with reference to FIG.

[0033] An engine 20 is mounted in an engine room 1a of the vehicle 1. The engine 20 is a multi-cylinder engine having a plurality of cylinders (for example, six cylinders) 20a, and is mounted in a longitudinal orientation with the cylinders aligned along the front-to-rear direction of the vehicle 1.

[0034] An intake manifold 32 is attached to one side of the engine 20, and an exhaust manifold 40 is attached to the opposite side. The intake manifold 32 is a component that constitutes part of an intake system 30 of the engine 20. The intake system 30 has an intake pipe 31 that connects an air cleaner and the intake manifold 32.

[0035] The exhaust system 10 includes an exhaust pipe 11, a silencer 14, a tail pipe 15, a pre-silencer (a structure having an expanded pipe portion) 16, and a reinforcing member 17. The exhaust pipe 11 is made up of an upstream exhaust pipe 12 that connects the exhaust manifold 40 and the pre-silencer 16, and a downstream exhaust pipe 13 that connects the pre-silencer 16 and the silencer 14.

[0036] As shown in part A of FIG. 1 , the upstream exhaust pipe 12 has a bent portion 12a bent in a V-shape. The bent portion 12a of the upstream exhaust pipe 12 is provided to adjust the length of the upstream exhaust pipe 12 and improve the torque of the engine 20 in a desired engine rotation range. By providing a bent portion in the upstream exhaust pipe 12, the length of the upstream exhaust pipe 12 is increased compared to when the intake manifold 40 and the pre-silencer 16 are connected in a straight line. This allows the negative pressure wave generated by exhaust pulsation during the valve overlap period when both the intake valve and the exhaust valve of the engine 20 are open to reach the exhaust port. Therefore, by providing the bent portion 12a and adjusting the length of the upstream exhaust pipe 12 as shown in FIG. 1 , residual gas in the cylinder 20a can be scavenged in a desired engine rotation range, thereby increasing the volumetric efficiency and improving the torque of the engine 20.

[0037] The reinforcing member 17 is fixed to the upstream pipe portion and downstream pipe portion of the bent portion 12a in the upstream exhaust pipe 12 to suppress deformation of the bent portion 12a (deformation caused by thermal expansion when exhaust gas flows through the upstream exhaust pipe 12).

[0038] 2. Structure for fixing the reinforcing member 17 to the upstream exhaust pipe 12 The structure for fixing the reinforcing member 17 to the upstream exhaust pipe 12 will be described with reference to FIG.

[0039] As shown in FIG. 2, reinforcing member 17 is a member formed by bending a metal plate, and has fixing portions 17a and 17b, and a bridging portion 17c. Fixing portion 17a is fixed by welding (weld portion WP) to upstream pipe portion 12b, which is a portion of upstream exhaust pipe 12 that is upstream of bent portion 12a in the flow direction of exhaust gas. Fixing portion 17b is fixed by welding (weld portion WP) to downstream pipe portion 12c, which is a portion of upstream exhaust pipe 12 that is downstream of bent portion 12a in the flow direction of exhaust gas. Bridging portion 17c connects fixing portions 17a and 17b, and is provided so as to bridge the inside of the bend of bent portion 12a in the upstream exhaust pipe 12. Here, fixing portion 17a corresponds to the "upstream fixing portion," and fixing portion 17b corresponds to the "downstream fixing portion."

[0040] In this embodiment, the bent inner surface portion 12d on the inside of the bent portion 12a in the upstream exhaust pipe 12 and the opposing portion 17d (side wall end portions 17h, 17i described later) that faces the bent inner surface portion 12d in the bridging portion 17c of the reinforcing member 17 are arranged in a spaced-apart state.

[0041] When exhaust gas flows through the upstream exhaust pipe 12, a force that tends to stretch due to thermal expansion as shown by arrows B1 and B2 acts on the bent portion 12a in the upstream exhaust pipe 12. Even when such a force acts, the fixing of the reinforcing member 17 can prevent the bent portion 12a from deforming.

[0042] 3. Detailed structure of reinforcing member 17 The detailed structure of the reinforcing member 17 will be described with reference to FIGS.

[0043] 3, the reinforcing member 17 is integrally formed with a pair of side wall portions 17e, 17f that face each other so as to sandwich the upstream exhaust pipe 12 in the radial direction at each of the fixing portions 17a, 17b, and a base wall portion 17g that connects the ends of the pair of side wall portions 17e, 17f. Note that although Fig. 3 shows only the fixing portion 17b, the other fixing portion 17a and the bridging portion 17c are also formed with the same configuration.

[0044] The distance between side wall portions 17e and 17f increases from inner corners 17h, 17k, which are the connecting portions of side wall portion 17e and base wall portion 17g, toward side wall ends 17h, 17i (portions on the other end edges) of side wall portions 17e, 17f. That is, the distance between inner corners 17j, 17k is W1, whereas the distance between side wall ends 17h, 17i is W2, which is larger than W1. In this embodiment, W1 is smaller than the pipe diameter D of upstream exhaust pipe 12, and W2 is set to be equal to or larger than pipe diameter D.

[0045] 3, fixing portions 17a and 17b of reinforcing member 17 are welded to upstream exhaust pipe 12 so that base wall portion 17g leaves a gap SP with respect to the outer peripheral surface of upstream exhaust pipe 12. Gap SP is set to a dimension larger than that of foreign objects such as pebbles that are expected to occur on the route along which vehicle 1 travels.

[0046] Next, as shown in FIG. 4, when the reinforcing member 17 is viewed from the side, the bridging portion 17c of the reinforcing member 17 does not linearly bridge the fixed portions 17a and 17b, but rather has an arched shape. Specifically, the outer portion 17l of the bridging portion 17c has a shape such that a longitudinal center portion P1 is located on the opposite side of the bent portion 12a of the upstream exhaust pipe 12 (see FIG. 2, etc.) from the ends P2 and P3. Assuming an imaginary line L1 connecting P2 and P3 and an imaginary line L2 passing through P1 and parallel to L1, the outer portion 17l is formed so that P1 is located on the outside of the bend, as indicated by arrow C1, with a gap of H1 between them. In other words, the base wall portion 17g is curved so that the longitudinal center portion (P1) juts out toward the opposite side of the bending direction of the bent portion 12a.

[0047] Similarly, the bridge portion 17c Opposing part The (inner portion) 17d has a shape in which a longitudinal center portion P4 is located on the opposite side of the ends P5 and P6 from the bent portion 12a (see FIG. 2, etc.) of the upstream exhaust pipe 12. Assuming that there is an imaginary line L3 connecting P5 and P6 and an imaginary line L4 passing through P4 and parallel to L3, the inner portion 17d is formed so that P4 is located outside the bend, as shown by arrow C2, with a gap of H2.

[0048] As described above, in the reinforcing member 17, the distance between the pair of side wall portions 17e, 17f is set to increase from the connection portion with the base wall portion 17g toward the side wall end portions 17h, 17i (see FIG. 3). However, as shown in FIG. 5, each of the side wall portions 17e, 17f is not flat, but is bent so that the distance between the side wall end edge 17m of the side wall portion 17e and the side wall end edge 17n of the side wall portion 17f is larger at the longitudinal center portions P7, P10 than at other portions P8, P9, P11, P12. Specifically, assume an imaginary line L5 connecting both longitudinal ends P8, P9 of the bridging portion 17c at the side wall end edge 17m, and an imaginary line L6 passing through P7 on the imaginary center line LC and parallel to the imaginary line L5. Also, assume an imaginary line L7 connecting both longitudinal ends P11, P12 of the bridge portion 17c at the side-wall end edge 17n, and an imaginary line L8 passing through P10 on the imaginary center line LC and parallel to the imaginary line L7. In this case, the distance between the imaginary lines L5 and L7 is W3, while the distance between the imaginary lines L6 and L8 is W4, which is larger than W3. That is, the side wall portions 17e, 17f are formed with a protruding shape such that P7, P10 are located further outward in the opposing direction of the side wall portions 17e, 17f than P8, P9, P11, P12, as indicated by arrows E1, E2.

[0049] 4. Plate thickness of reinforcing member 17 In this embodiment, the thickness of the metal plate material constituting the reinforcing member 17 is set to be approximately the same as the thickness of the pipe material constituting the upstream exhaust pipe 12. Specifically, the thickness of the metal plate material constituting the reinforcing member 17 is set to be in the range of 70% to 130%, more preferably in the range of 80% to 120%, and even more preferably in the range of 90% to 110% of the thickness of the pipe material constituting the upstream exhaust pipe 12. For example, if the thickness of the pipe material constituting the upstream exhaust pipe 12 is 1.2 mm, the thickness of the metal plate material constituting the reinforcing member 17 can be set to be in the range of 0.8 mm to 1.5 mm.

[0050] The thickness of the reinforcing member 17 is merely an example, and is determined appropriately taking into consideration the relationship between the constituent material of the reinforcing member 17 and the constituent material of the upstream exhaust pipe 12, the difference in rigidity relative to the upstream exhaust pipe 12, etc.

[0051] 5.Effects In the exhaust device 10 according to this embodiment, a bent portion 12a is formed in the upstream exhaust pipe (one exhaust pipe) 12. Therefore, the formation of the bent portion 12a allows the length of the upstream exhaust pipe 12 to be longer than if it were formed straight, and this allows negative pressure waves generated by exhaust pulsation during the valve-open overlap period when both the intake valve and exhaust valve of the engine 20 are open to reach the exhaust port. Therefore, in the engine 20 to which the exhaust device 10 is applied, residual gas in the cylinder 20a can be scavenged in the desired engine rotation range, thereby improving torque due to increased volumetric efficiency.

[0052] Furthermore, the exhaust device 10 includes a reinforcing member 17 having a bridging portion 17c that bridges the bent portion 12a of the upstream exhaust pipe 12 on the inside of the bend, so that deformation of the bent portion 12a can be suppressed even if the upstream exhaust pipe 12 thermally expands (thermal elongates) due to a temperature rise caused by the flow of exhaust gas. Therefore, the exhaust device 10 can suppress the generation of muffled noise in the vehicle body that is caused by deformation of the bent portion 12a of the upstream exhaust pipe 12.

[0053] Furthermore, the exhaust device 10 employs a reinforcing member 17 having a U-shaped cross section, which is formed by integrally forming a pair of side wall portions 17e, 17f and a base wall portion 17g. This allows for a larger cross-sectional modulus than when a reinforcing member made of a flat plate is employed, which is advantageous in suppressing deformation of the bent portion 12a while suppressing increases in weight and manufacturing costs.

[0054] Furthermore, in the exhaust device 10, the reinforcing member 17 is configured so that the distance between the side wall portions 17e, 17f in the reinforcing member 17 gradually increases from the inner corners 17j, 17k to the opposite side wall ends 17h, 17i. Therefore, compared to a configuration in which the side wall portions are arranged parallel to each other, the reinforcing member 17 can be easily attached to the upstream exhaust pipe 12 without having to be formed with high dimensional precision.

[0055] In the exhaust device 10, the reinforcing member 17 is configured so that the bridge portion 17c of the reinforcing member 17 has portions (widened portions) P7 and P10 where the distance between the side wall end edges 17m and 17n is wider than the ends P8, P9, P11 and P12. Therefore, even if the distance between the upstream pipe portion 12b and the downstream pipe portion 12c increases due to thermal expansion of the upstream exhaust pipe 12, the reinforcing member 17 17 Part of this elongation can be absorbed by deformation of the widened portions P7, P10, and this makes it possible to prevent the fixing of the fixing portions 17a, 17b of the reinforcing member 17 from the upstream pipe portion 12b and the downstream pipe portion 12c of the upstream exhaust pipe 12 from coming loose. Therefore, in the exhaust device 10, even if the upstream exhaust pipe 12 tries to elongate due to thermal expansion caused by the flow of exhaust gas, it is possible to prevent the fixing of the fixing portions 17a, 17b of the reinforcing member 17 from the upstream pipe portion 12b and the downstream pipe portion 12c of the upstream exhaust pipe 12 from coming loose.

[0056] In addition, in the exhaust device 10, the base wall portion 17g of the reinforcing member 17 is configured to have a curved shape as shown in FIG. 4, so that the exhaust gas flows Upstream exhaust pipe Even if 12 thermally expands (thermally stretches), the stretching can be absorbed by the deformation of the base wall portion 17g, and the fixation between the fixing portions 17a, 17b of the reinforcing member 17 and the upstream pipe portion 12b and downstream pipe portion 12c of the upstream exhaust pipe 12 can be prevented from coming loose.

[0057] Furthermore, in the exhaust device 10, the base wall portion 17g of each of the fixing portions 17a, 17b of the reinforcing member 17 is disposed so as to leave a gap SP with respect to the outer peripheral surface of the upstream exhaust pipe 12. Therefore, even if a foreign object such as a pebble gets between the base wall portion 17g of the reinforcing member 17 and the outer peripheral surface of the upstream exhaust pipe 12, the foreign object can be expelled from the gap SP. Therefore, noise caused by a foreign object such as a pebble colliding with the reinforcing member 17 or the upstream exhaust pipe 12 can be suppressed.

[0058] Furthermore, the exhaust device 10 employs a reinforcing member 17 made by bending a metal plate, which is advantageous in suppressing deformation of the bent portion 12a due to thermal expansion of the upstream exhaust pipe 12 while suppressing increases in weight and manufacturing costs.

[0059] Furthermore, exhaust device 10 employs pre-silencer 16 as an example of a structure having an expanded pipe portion, and employs a configuration in which upstream exhaust pipe 12 is formed with bent portion 12a, but reinforcing member 17 is attached to bent portion 12a of upstream exhaust pipe 12, thereby reducing exhaust noise and improving the torque of engine 20 while suppressing deformation of bent portion 12a and thereby suppressing the generation of muffled noise in the vehicle body.

[0060] As described above, the exhaust device 10 of the engine 20 according to this embodiment can improve the torque of the engine 20 by using exhaust pulsation, while suppressing deformation of the bent portion 12a in the upstream exhaust pipe 12, thereby suppressing the generation of muffled noise in the vehicle body.

[0061] [Variations] An engine exhaust device 50 according to a modified example will be described with reference to Fig. 6. Note that Fig. 6 omits the illustration of the engine 20 and the reinforcing member 17 of the exhaust device 50. The reinforcing member 17 can be the same as the reinforcing member 17 employed in the above embodiment.

[0062] 6, an exhaust system 50 according to this modification also includes an exhaust pipe 51, a silencer 54, a tail pipe 55, a pre-silencer (a structure having an expanded pipe portion) 56, and a reinforcing member (not shown). The exhaust pipe 51 is made up of an upstream exhaust pipe 52 that connects the intake manifold and the pre-silencer 56, and a downstream exhaust pipe 53 that connects the pre-silencer 56 and the silencer 54.

[0063] The exhaust device 50 according to this modified example differs from the exhaust device 10 according to the above embodiment in the position at which the pre-silencer 56 is inserted relative to the exhaust pipe 51 and the arrangement of the upstream exhaust pipe 52 and the downstream exhaust pipe 53.

[0064] In the exhaust device 50, the upstream exhaust pipe 52 does not have a bend as large as that of the upstream exhaust pipe 12 of the above embodiment. Therefore, in the exhaust device 50, it is not necessarily necessary to attach a reinforcing member 17 to the upstream exhaust pipe 52.

[0065] Meanwhile, as indicated by arrows F1 to F4, four bent portions 53a to 53d are formed in downstream exhaust pipe 53. Therefore, in exhaust device 50, if a reinforcing member having a configuration similar to reinforcing member 17 of the above embodiment is attached to at least one of bent portions 53a to 53d in downstream exhaust pipe 53, the same effects as those of the above embodiment can be obtained.

[0066] [Other variations] In the above embodiment and modified example, the pre-silencer 16, 56 is used as an example of a structure having an expanded pipe portion, but in the present invention, it is also possible to use, for example, a catalyst as another example of a structure having an expanded pipe portion. That is, it is sufficient if the structure is inserted between the upstream exhaust pipe 12, 52 and the downstream exhaust pipe 13, 53 and generates pulsation reflection at the insertion point.

[0067] In the above embodiment and the above modified example, a reinforcing member 17 having a U-shaped cross section is used as the reinforcing member to be attached to the bending portions 12a, 53a to 53d, but in the present invention, a reinforcing member having a flat plate shape or an L-shaped cross section can also be used.

[0068] In the above embodiment, a reinforcing member 17 is attached to the bent portion 12a of the upstream exhaust pipe 12, and in the above modified example, a reinforcing member is attached to at least one of the bent portions 53a to 53d of the downstream exhaust pipe 53. However, in the present invention, when there are bent portions in both the upstream exhaust pipe and the downstream exhaust pipe, a reinforcing member can also be attached to the bent portions of both the upstream exhaust pipe and the downstream exhaust pipe.

[0069] In the above embodiment, as explained using Figure 3, a configuration is adopted in which the distance between a pair of side wall portions 17e, 17f in the reinforcing member 17 gradually increases as it moves from the side of the base wall portion 17g to the side of the opposite side wall end portions 17h, 17i. However, in the present invention, a configuration in which a pair of side wall portions are arranged in parallel can also be adopted.

[0070] 5, in the above embodiment, the bridge portion 17c of the reinforcing member 17 has portions P7, P10 formed in the longitudinal center of the side wall portions 17e, 17f that protrude outward in the width direction, but in the present invention, it is also possible to provide the side wall portions with inwardly recessed portions or with bellows shapes that continue in the longitudinal direction. That is, it is sufficient to provide the reinforcing member with portions that can absorb elongation so that the fixed portion of the reinforcing member does not come off the exhaust pipe when the exhaust pipe tries to elongate due to the flow of exhaust gas through the exhaust pipe.

[0071] Furthermore, in the above embodiment, as explained using FIG. 4, a curved configuration is adopted in which the base wall portion 17g of the reinforcing member 17 protrudes in the direction opposite to the bending direction of the bent portion 12a of the upstream exhaust pipe 12. However, in the present invention, a configuration can also be adopted in which the base wall portion of the reinforcing member has a bent portion that protrudes in the direction opposite to the bending direction of the bent portion.

[0072] In the above embodiment, a reinforcing member 17 made by bending a metal plate was used, but in the present invention, a reinforcing member made partially of a material other than metal can also be used, or a reinforcing member made entirely of a material other than metal can also be used.

[0073] The present invention can also employ a reinforcing member formed from a plate material with many holes, such as perforated metal. In this case, depending on the size of the holes, it is not necessarily necessary to leave a gap between the base wall at the fixing portion of the reinforcing member and the exhaust pipe. This is because it may be possible for foreign objects such as pebbles to be expelled to the outside through the holes.

[0074] In the above embodiment and modified example, a six-cylinder engine mounted in the engine compartment 1a in a longitudinal orientation is used as the engine 20, but the present invention is not limited to this. For example, the number of cylinders of the engine may be five or less or seven or more. Also, a configuration in which the engine is mounted in a transverse orientation relative to the engine compartment may be adopted. [Explanation of symbols]

[0075] 10,50 Exhaust system 11,51 Exhaust pipe 12,52 Upstream exhaust pipe 12a,53a,53b,53c,53d Bend part 12b Upstream pipe section 12c Downstream pipe section 13,53 Downstream exhaust pipe 14,54 silencer 16,56 Pre-silencer (structure with expanded tube section) 17 Reinforcement member 17a,17b Fixed part 17c Bridge 17e,17f Side wall part 17g Base wall 20 Engine

Claims

1. A silencer disposed under the floor of a vehicle body at a position spaced apart from the engine; an exhaust pipe connecting the engine and the silencer and serving as a path for exhaust gas; a structure having an expanded portion provided midway in the longitudinal direction of the exhaust pipe and having a diameter larger than that of the exhaust pipe; An exhaust system for an engine comprising: the exhaust pipe includes an upstream exhaust pipe disposed in the path between the engine and the structure, and a downstream exhaust pipe disposed in the path between the structure and the silencer, at least one of the upstream exhaust pipe and the downstream exhaust pipe has a bent portion bent in a V shape, The exhaust system of the engine comprises: a reinforcing member including an upstream fixing portion fixed to an upstream pipe portion that is upstream of the bent portion of the at least one exhaust pipe; a downstream fixing portion fixed to a downstream pipe portion that is downstream of the bent portion of the at least one exhaust pipe; and a bridging portion that connects the upstream fixing portion and the downstream fixing portion and bridges the inside of the bend in the bent portion between the upstream pipe portion and the downstream pipe portion, The reinforcing member is a pair of side wall portions that face each other so as to sandwich the upstream pipe portion and the downstream pipe portion in the radial direction, and that are formed so as to extend across both fixing portions; a base wall portion formed so as to be continuous with the pair of side wall portions and to extend from the upstream-side fixing portion to the downstream-side fixing portion so as to connect the respective end sides of the pair of side wall portions; having Engine exhaust system.

2. In the exhaust system of the engine described in claim 1, The pair of side wall portions of the reinforcing member are formed so that the distance between them increases from the side where the base wall portion is continuous to the other end side on the opposite side. Engine exhaust system.

3. In the exhaust system of the engine according to claim 1 or claim 2, The pair of side wall portions of the reinforcing member have a portion in the longitudinal direction formed such that the distance between the other end sides on the opposite side to the side where the base wall portion is continuous is wider than other portions of the bridge portion. Engine exhaust system.

4. In the exhaust system of the engine according to claim 1 or claim 2, The base wall portion is formed in a curved or bent shape so as to protrude in a direction opposite to the bending direction of the bent portion. Engine exhaust system.

5. In the exhaust system of the engine according to claim 1 or claim 2, the base wall portion is disposed at the upstream fixed portion and the downstream fixed portion so as to leave a gap with respect to the outer peripheral surfaces of the upstream pipe portion and the downstream pipe portion, respectively; Engine exhaust system.

6. In the exhaust system of the engine according to claim 1 or claim 2, The reinforcing member is formed by bending a metal plate material. Engine exhaust system.

7. In the exhaust system of the engine according to claim 1 or claim 2, the structure is a pre-silencer, The bent portion is formed at least in the upstream exhaust pipe. Engine exhaust system.

8. A silencer disposed under the floor of the vehicle body at a position spaced apart from the engine; an exhaust pipe connecting the engine and the silencer and serving as a path for exhaust gas; a structure having an expanded portion provided midway in the longitudinal direction of the exhaust pipe and having a diameter larger than that of the exhaust pipe; An exhaust system for an engine comprising: the exhaust pipe includes an upstream exhaust pipe disposed in the path between the engine and the structure, and a downstream exhaust pipe disposed in the path between the structure and the silencer, at least one of the upstream exhaust pipe and the downstream exhaust pipe has a bent portion bent in a V shape, The exhaust system of the engine comprises: a reinforcing member including an upstream fixing portion fixed to an upstream pipe portion that is upstream of the bent portion of the at least one exhaust pipe; a downstream fixing portion fixed to a downstream pipe portion that is downstream of the bent portion of the at least one exhaust pipe; and a bridging portion that connects the upstream fixing portion and the downstream fixing portion and bridges the inside of the bend in the bent portion between the upstream pipe portion and the downstream pipe portion, the structure is a pre-silencer, The bent portion is formed at least in the upstream exhaust pipe. Engine exhaust system.

Images