Exhaust manifold

Abstract

An exhaust manifold 10 includes: an inner pipe 20 through which exhaust gas from an engine flows; an outer pipe 30 which is provided at an interval from an outer peripheral surface of the inner pipe 20 and covers the inner pipe 20 from the outside; and a second flange part 60 which supports the inner pipe 20 and the outer pipe 30 in a collective pipe part 14, and in which an opening 60a serving as a discharge port for the exhaust gas flowing through the inner pipe 20 is formed. The inner pipe 20 is inserted into an inner peripheral surface of the opening 60a of the second flange part 60, and the outer pipe 30 is abutted on an end surface 601 of the second flange part 60 outside the inner pipe 20. According to the above, durability against the thermal expansion generated in the inner pipe 20 and force transmitted from a downstream device can be improved.

Description

exhaust manifold

[0001] The present invention relates to an exhaust manifold.

[0002]

[0003] Conventionally, there has been known a technique relating to an exhaust manifold that includes an outer pipe and an inner pipe disposed at a distance inside the outer pipe and that is connected to a multi-cylinder internal combustion engine. For example, Patent Document 1 describes a double exhaust pipe for an engine that includes an outer pipe and an inner pipe, and that is joined and welded to a flange on the inner circumferential surface of the outer pipe and the inner pipe downstream in the flow direction of exhaust gas.

[0003] Japanese Unexamined Patent Publication No. 8-189349

[0004] However, in a structure in which both the outer pipe and the inner pipe are joined to the flange, as in the structure described in Patent Document 1, it may not be possible to prevent damage to the inner pipe due to thermal expansion.In addition, the exhaust manifold may be damaged by forces transmitted from downstream devices to the outer pipe and the inner pipe via the flange.

[0005] The present invention was made in consideration of these problems, and its purpose is to provide an exhaust manifold that can further improve durability against thermal expansion occurring in the inner pipe and forces transmitted from downstream devices.

[0006] In order to achieve the above object, the exhaust manifold of the present invention is an exhaust manifold comprising a plurality of branch pipe sections connected to each cylinder of an internal combustion engine and a collecting pipe section where the branch pipe sections join together, and comprising an inner pipe through which exhaust gas from the internal combustion engine flows, an outer pipe that covers the inner pipe from the outside, and a flange section that supports the inner pipe and the outer pipe in the collecting pipe section and has an opening that serves as an outlet for exhaust gas flowing through the inner pipe, wherein the inner pipe is inserted into the inner surface of the opening in the flange section, and the outer pipe is abutted against the end face of the flange section outside the inner pipe.

[0007] According to the exhaust manifold of the present invention, it is possible to further improve durability against thermal expansion occurring in the inner pipe and against forces transmitted from downstream devices.

[0008] Fig. 2 is a plan view showing an outline of an engine to which an exhaust manifold according to an embodiment is applied and its intake and exhaust system; Fig. 3 is a side view showing an outline of an engine to which an exhaust manifold according to an embodiment is applied and its intake and exhaust system; Fig. 4 is a perspective view of the exhaust manifold as viewed from above and downstream; Fig. 5 is a perspective view of the exhaust manifold as viewed from above and downstream; Fig. 6 is a perspective view of the exhaust manifold as viewed from above and downstream; Fig. 7 is a perspective view of the exhaust manifold as viewed from above and upstream; Fig. 8 is a cross-sectional view of the exhaust manifold taken along line A-A in Fig. 1; Fig. 9 is a cross-sectional view of the exhaust manifold taken along line B-B in Fig. 2;

[0009] An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a plan view showing an outline of an engine and its intake and exhaust system to which an exhaust manifold according to the embodiment is applied, and FIG. 2 is a side view showing an outline of an engine and its intake and exhaust system to which an exhaust manifold according to the embodiment is applied. As shown in the drawings, an exhaust manifold 10 according to the embodiment is connected to a multi-cylinder engine 1 (internal combustion engine) mounted on a vehicle. The exhaust manifold 10 has a plurality of branch pipes 12 connected to each exhaust port of a plurality of cylinders 2 of the engine 1 and a collecting pipe 14 where the plurality of branch pipes 12 converge. The exhaust manifold 10 discharges exhaust gas from the engine 1 that has flowed into each branch pipe 12 from the collecting pipe 14. In the following description, the arrangement direction of the plurality of cylinders 2 of the engine 1 will be referred to as the "arrangement direction X." Furthermore, the side of the exhaust gas flow facing the engine 1 will be referred to as the "upstream side," and the side opposite the engine 1 will be referred to as the "downstream side." In this embodiment, the arrangement direction X corresponds to the longitudinal direction of the vehicle to which the engine 1 is mounted. 1 and the upper side in FIG. 2 are the upper side in the up-down direction.

[0010] In this embodiment, a turbocharger 3 is provided downstream of the collecting pipe portion 14 of the exhaust manifold 10. As shown in FIG. 2 , the turbocharger 3 includes a first turbocharger 3A and a second turbocharger 3B. The first turbocharger 3A has a first turbine 3AT and a first compressor 3AC. The second turbocharger 3B has a second turbine 3BT and a second compressor 3BC and is connected to the first turbocharger 3A. The second turbocharger 3B is a turbocharger with a different weight from the first turbocharger 3A and is provided above the first turbocharger 3A. In this embodiment, the first turbocharger 3A is mainly used in the low rotation speed range of the engine 1. Meanwhile, the second turbocharger 3B is mainly used in the high rotation speed range of the engine 1 and is lighter in weight than the first turbocharger 3A. Exhaust gas discharged from the exhaust manifold 10 passes through the first turbine 3AT and the second turbine 3BT, passes through a purification device 4 including a catalyst, and is discharged to the outside from an exhaust pipe 5. At this time, the exhaust gas rotates the first turbine 3AT and the second turbine 3BT, which in turn rotates the first compressor 3AC and the second compressor 3BC. As a result, air from outside is drawn into the second compressor 3BC and the first compressor 3AC via the air cleaner 6 (FIG. 1), and is then compressed and sent to the intake side of the engine 1 by the rotation of each compressor. Note that an intercooler 7 for cooling the air is disposed between each compressor and the engine 1.

[0011] Next, the structure of the exhaust manifold 10 will be described with reference to FIGS. 3 to 9. FIGS. 3 to 5 are perspective views of the exhaust manifold 10 viewed from above and downstream. In FIG. 4, the cover 40, which will be described later, is omitted from the state shown in FIG. 3, and in FIG. 5, the outer pipe 30, which will be described later, is omitted from the state shown in FIG. 4. FIGS. 6 and 7 are perspective views of the exhaust manifold 10 viewed from above and upstream. In FIG. 6, the cover 40 is omitted, and in FIG. 7, the outer pipe 30, which will be described later, is omitted from the state shown in FIG. 6. In addition, FIG. 8 is a cross-sectional view of the exhaust manifold 10 taken along line A-A in FIG. 1, and FIG. 9 is a cross-sectional view of the exhaust manifold 10 taken along line B-B in FIG. 2. As shown in the drawings, the exhaust manifold 10 includes an inner pipe 20, an outer pipe 30, a cover 40, a first flange portion 50, and a second flange portion 60 (flange portion). The exhaust manifold 10 extends such that the direction X in which the cylinders 2 are arranged corresponds to the longitudinal direction.

[0012] The inner pipe 20, together with the outer pipe 30 (described later), constitutes the plurality of branch pipe sections 12 and the collecting pipe section 14 of the exhaust manifold 10, and is a hollow member through which exhaust gas flows. The branch pipe sections 12 of the inner pipe 20 are provided at intervals along the arrangement direction X of the cylinders 2, and the branch pipe sections 12 join together to form the collecting pipe section 14. As shown in Fig. 8 , an end 20a of the inner pipe 20 (the upstream end of each branch pipe section 12) is formed with an opening that communicates with the exhaust port of each cylinder 2. Furthermore, an end 20b of the inner pipe 20 (the downstream end of the collecting pipe section 14) is formed with an opening that communicates with the turbocharger 3 (the first turbine 3AT of the first turbocharger 3A).

[0013] The outer pipe 30 is a hollow member that covers the inner pipe 20 from the outside, and is open at an end 30a (the upstream end of each branch pipe 12) and an end 30b (the downstream end of the collecting pipe 14). The outer pipe 30 is formed roughly along the outer peripheral surface of the inner pipe 20 and is provided with a gap therebetween. As a result, as shown in Figures 8 and 9, an insulating layer of air is formed between the inner pipe 20 and the outer pipe 30, which reduces the temperature of the exhaust gas passing through the inner pipe 20 and suppresses thermal damage to peripheral equipment caused by the exhaust gas passing through the inner pipe 20.

[0014] The cover 40 is a hollow member that further covers the outer pipe 30 from the outside and is an insulator that has thermal and soundproofing functions. The cover 40 is formed in a shape that generally follows the outer peripheral surface of the outer pipe 30 and is provided with a gap therebetween. The cover 40 is joined to the outer peripheral surface of the outer pipe 30 via legs (not shown) that protrude from the outer peripheral surface of the outer pipe 30. As shown in FIG. 8 , the cover 40 is provided so as to externally cover a rib portion 70 (described later). An insulating material (not shown) is provided between the cover 40 and the outer pipe 30.

[0015] The first flange portion 50 is a plate-like member extending along the alignment direction X of the cylinders 2 and constitutes a mounting portion for the exhaust manifold 10 to the engine 1. The first flange portion 50 supports the inner pipe 20 and the outer pipe 30 in each branch pipe portion 12. Specifically, as shown in FIG. 7 , the first flange portion 50 has a plurality of openings 50 a formed at positions corresponding to the branch pipe portions 12 of the inner pipe 20. As shown in FIGS. 8 and 9 , the end portion 20 a of the inner pipe 20 is inserted (fitted) into the inner circumferential surface of the openings 50 a, and at least a portion of the end portion 20 a is joined to the inner circumferential surface of the openings 50 a by spot welding. Furthermore, as shown in FIG. 8 , the end portion 30 a of the outer pipe 30 is thrust into the first flange portion 50 on the outside of the inner pipe 20 and abuts against it, and joined by welding.

[0016] The second flange portion 60 is a plate-like member disposed opposite the first flange portion 50 and constitutes a mounting portion of the exhaust manifold 10 to the turbocharger 3 (the first turbine 3AT of the first turbocharger 3A). In the present embodiment, the second flange portion 60 is formed in a substantially triangular shape. However, the shape of the second flange portion 60 is not limited thereto and may be, for example, a rectangular or circular shape. The second flange portion 60 has an upstream end face 601 (opposite the turbocharger 3) and a downstream end face 602 (on the turbocharger 3 side). A rib portion 70 is formed on the end face 601 of the second flange portion 60, protruding annularly toward the upstream side around an opening 60a (described later). As schematically shown by dashed lines in FIGS. 3 to 5 , the rib portion 70 has a longitudinal portion 71 extending along the arrangement direction X of the cylinders 2 and a transverse portion 72 extending along the up-down direction perpendicular to the longitudinal portion 71 and formed shorter than the longitudinal portion 71. In this embodiment, the rib portion 70 has a generally elliptical shape with opposing long sides 71 and opposing short sides 72. With this configuration, the rib portion 70 has a different length (the length from one annular end to the other end) in the arrangement direction X and in a direction perpendicular to the arrangement direction X and the flow direction of the exhaust gas (the up-and-down direction in this embodiment).

[0017] The second flange portion 60 configured as described above supports the inner pipe 20 and the outer pipe 30 in the collecting pipe portion 14. Specifically, as shown in FIGS. 5 , 8 , and 9 , the second flange portion 60 has an opening 60a, which serves as an exhaust gas outlet, at a position of the inner pipe 20 corresponding to the collecting pipe portion 14. The end portion 20b of the inner pipe 20 is inserted into the inner circumferential surface of this opening 60a (fitted in to an extent that it is not completely fixed). Therefore, the inner pipe 20 is provided to the second flange portion 60 without being fixed by welding or the like. Meanwhile, as shown in FIGS. 8 and 9 , the very end of the end portion 30a of the outer pipe 30 protrudes into and abuts against an end face 601 of the second flange portion 60. In this state, the end portion 30a is inserted into and supported by the inner circumferential surface of the rib portion 70 and is joined to the rib portion 70 by welding. Since the outer pipe 30 has a larger diameter than the inner pipe 20, the outer pipe 30 abuts against the second flange portion 60 radially outside the inner pipe 20 (at a position spaced apart from the inner pipe 20).

[0018] As described above, the exhaust manifold 10 of the embodiment includes the inner pipe 20 through which exhaust gas from the engine 1 (internal combustion engine) flows, the outer pipe 30 that is provided at a distance from the outer peripheral surface of the inner pipe 20 and that, together with the inner pipe 20, forms a plurality of branch pipe sections 12 and a collecting pipe section 14, and the second flange section 60 (flange section) that supports the inner pipe 20 and the outer pipe 30 in the collecting pipe section 14 and has an opening 60a that serves as an outlet for exhaust gas flowing through the inner pipe 20. The inner pipe 20 is inserted into the inner peripheral surface of the opening 60a of the second flange section 60, and the outer pipe 30 is abutted against an end face 601 of the second flange section 60 outside the inner pipe 20.

[0019] With this configuration, the inner pipe 20 is inserted into the second flange portion 60. Therefore, even if thermal expansion occurs in the inner pipe 20, the connection between the inner pipe 20 and the second flange portion 60 is not released and deformation due to thermal expansion is absorbed. As a result, damage to the inner pipe 20 can be suppressed. Furthermore, since the outer pipe 30 abuts against the end face 601 of the second flange portion 60, the outer pipe 30 can withstand a force transmitted to the second flange portion 60 from a device (supercharger 3) arranged downstream of the exhaust manifold 10. Furthermore, since the outer pipe 30 abuts against the second flange portion 60 outside the inner pipe 20, the force transmitted from the supercharger 3 to the second flange portion 60 can be suppressed from being transmitted to the inner pipe 20, and the force can be withstood by the outer pipe 30, which has a larger diameter than the inner pipe 20, thereby improving durability. Furthermore, if the outer pipe 30 were inserted into the opening 60a in the same way as the inner pipe 20, the outer pipe 30 would need to be tapered toward the opening 60a, which would result in the outer pipe 30 having a portion (a portion with a tapered diameter) prone to stress concentration. According to the present embodiment, it is not necessary to tape the outer pipe 30 toward the opening 60a, and it is possible to prevent the outer pipe 30 from having a portion (a portion with a tapered diameter) prone to stress concentration. Therefore, according to the exhaust manifold 10 of the present embodiment, it is possible to further improve durability against thermal expansion occurring in the inner pipe 20 and against forces transmitted from downstream devices.

[0020] The second flange portion 60 also has a rib portion 70 that protrudes annularly from the end face 601 around the opening 60a, and the outer pipe 30 is inserted into the inner circumferential surface of the rib portion 70. With this configuration, the outer pipe 30 is stably supported by the rib portion 70, and the outer pipe 30 can be prevented from coming off the second flange portion 60. Furthermore, in this embodiment, the outer pipe 30 is welded to the rib portion 70 after being inserted into the inner circumferential surface of the rib portion 70. Therefore, even if a load is applied to the second flange portion 60 in the vertical direction or the arrangement direction X, the shear load applied to the welded portion between the outer pipe 30 and the rib portion 70 is alleviated, and the durability of the welded portion is improved.

[0021] Furthermore, the rib portion 70 has a different length in the arrangement direction X than in the direction perpendicular to the arrangement direction X and the exhaust gas flow direction (the up-down direction). This configuration increases the rigidity of the connection between the outer pipe 30 and the second flange portion 60 in the rotational direction around the exhaust gas flow direction as an axis. In other words, it is possible to improve the durability of the connection between the outer pipe 30 and the second flange portion 60 against vibrations and forces in specific directions.

[0022] Furthermore, the length of the rib portion 70 in the arrangement direction X (the length of the long portion 71) is longer than the length in the direction perpendicular to the arrangement direction X and the flow direction of the exhaust gas (the length of the short portion 72). In other words, the specific direction is the arrangement direction X. With this configuration, the arrangement direction X of each cylinder 2 extends in the longitudinal direction, and therefore, in the exhaust manifold 10 which is particularly prone to thermal expansion along the arrangement direction X, it is possible to improve durability against forces in the arrangement direction X that occur at the connection portion between the outer pipe 30 and the second flange portion 60 due to thermal expansion.

[0023] Furthermore, in the present embodiment, a first turbocharger 3A (turbocharger) including a first turbine 3AT (turbine) and a first compressor 3AC (compressor) that are aligned along the arrangement direction X of the cylinders 2 is provided downstream of the exhaust manifold 10, and the first turbine 3AT is attached to the second flange portion 60. That is, the first compressor 3AC is provided offset from the second flange portion 60 in the arrangement direction X. Even in this configuration in which vibration of the first compressor 3AC easily applies a torsional force to the second flange portion 60 via the first turbine 3AT in a rotational direction about the axis of the flow direction of the exhaust gas, the structure of the present embodiment can improve the durability of the connection portion between the outer pipe 30 and the second flange portion 60 as described above, and can appropriately protect the exhaust manifold 10.

[0024] Furthermore, in the present embodiment, the turbocharger 3 includes a first turbocharger 3A attached to the second flange portion 60 and communicating with the exhaust manifold 10, and a second turbocharger 3B disposed on one side of the first turbocharger 3A in the vertical direction and connected to the first turbocharger 3A, the second turbocharger 3B having a different weight from the first turbocharger 3A. That is, the second turbocharger 3B is disposed offset to one side of the second flange portion 60 in the vertical direction. In this configuration in which the second turbocharger 3B having a different weight from the first turbocharger 3A is disposed on one side of the first turbocharger 3A in the vertical direction, a force that causes torsion in the second flange portion 60 in a rotational direction about an axis corresponding to the flow direction of the exhaust gas is applied to the second flange portion 60. Even in this configuration in which a force that causes torsion is applied to the second flange portion 60, the structure of the present embodiment can improve the durability of the connection portion between the outer pipe 30 and the second flange portion 60 as described above, thereby appropriately protecting the exhaust manifold 10.

[0025] The exhaust manifold 10 further includes a cover 40 spaced apart from the outer peripheral surface of the outer pipe 30, and the cover 40 is provided so as to cover the rib portion 70 from the outside. With this configuration, the end portion 30b of the outer pipe 30 can be covered by the cover 40 and the rib portion 70, thereby improving the heat retention effect of the exhaust manifold 10 and the effect of suppressing heat damage to peripheral devices.

[0026] Although the description of the embodiment has been completed, aspects of the present invention are not limited to this embodiment. For example, the part to which the second flange portion 60 is attached does not have to be the turbocharger 3 (i.e., the turbocharger 3 may be omitted). Furthermore, the rib portion 70 is not limited to an elliptical shape and may be rectangular, for example. Furthermore, the rib portion 70 may be formed with both the long portion 71 and the short portion 72 having the same length. Furthermore, as long as the outer pipe 30 can be stably supported by the second flange portion 60, the rib portion 70 may be omitted from the second flange portion 60. Furthermore, the long portion 71 may be set in any direction, taking into account the magnitude of the force applied to the exhaust manifold 10.

[0027] REFERENCE SIGNS LIST 1 engine 2 cylinder 3 turbocharger 10 exhaust manifold 12 branch pipe section 14 collecting pipe section 20 inner pipe 30 outer pipe 40 cover 50 first flange section 60 second flange section 60a opening 70 rib section 71 long side section 72 short side section X arrangement direction

Claims

1. An exhaust manifold comprising a plurality of branch pipe sections connected to each cylinder of an internal combustion engine, and a manifold section formed by the convergence of the branch pipe sections, An internal pipe through which exhaust gas from the internal combustion engine flows, An outer tube is provided at a distance from the outer surface of the inner tube and covers the inner tube from the outside, The flange portion in the manifold section supports the inner pipe and the outer pipe, and has an opening formed therein that serves as an outlet for exhaust gas flowing through the inner pipe. Equipped with, The flange portion has a rib portion that protrudes annularly from the end face around the opening, The inner tube is inserted into the inner circumferential surface of the opening in the flange portion. The outer tube is inserted into the inner circumferential surface of the rib portion outside the inner tube and abuts against the end face of the flange portion. The ratio of the length of the inner tube end on the flange side along the cylinder arrangement direction to the length along the direction perpendicular to the arrangement direction and the exhaust gas flow direction is different from the ratio of the length of the outer tube end on the flange side along the arrangement direction to the length along the direction perpendicular to the arrangement direction and the exhaust gas flow direction. An exhaust manifold characterized by the following features.

2. (delete)

3. The exhaust manifold according to claim 1, characterized in that the length of the rib portion differs between the direction of arrangement and the direction perpendicular to the direction of arrangement and the direction of exhaust gas flow.

4. The exhaust manifold according to claim 3, characterized in that the length of the rib portion in the direction of arrangement is longer than the length in the direction perpendicular to the direction of arrangement and the direction of exhaust gas flow.

5. The outer tube is further provided with a cover that is spaced apart from the outer surface of the outer tube, The cover is provided so as to cover the rib portion from the outside. The exhaust manifold according to any one of claims 1, 3, to 4.

6. The exhaust manifold according to claim 3, wherein the rib portion and the flange-side end of the outer pipe are elliptical in shape.