JP4424016B2 - Exhaust manifold for internal combustion engines - Google Patents

Description

  The present invention relates to an exhaust manifold of an internal combustion engine, and more particularly to an improvement of an exhaust manifold that collects exhaust systems of at least three cylinders arranged in series in one flow path.

In Patent Document 1, as an exhaust manifold applied to an exhaust system of one bank of a V-type 8-cylinder internal combustion engine, a common junction pipe extending linearly in the cylinder row direction and an exhaust port of each cylinder are connected. And four branch pipes are disclosed. The four branch pipes are arranged substantially in parallel, connected to the junction pipes along the tangential direction of the circular cross section of the junction pipe, and each branch pipe with respect to the flow direction of the junction pipes, It is comprised so that it may join at the merge angle of 67.5 degrees or less.
Japanese Patent Laid-Open No. 10-317953

  In the exhaust manifold described above, the lengths of the four branch pipes extending from the exhaust port of each cylinder to the common merging pipe are equal to each other, so that the outlet of the merging pipe end from the exhaust port of each cylinder. The pipe length to the flange will be different for each cylinder. For example, in the specific example disclosed in Patent Document 1, the exhaust systems of four cylinders # 1, # 3, # 5, and # 7 are assembled, but ## which is farthest from the outlet flange # The one cylinder exhaust system has the longest pipe length, and the # 7 cylinder exhaust system closest to the outlet flange has the shortest pipe length.

  In this way, if the actual pipe length is different in each cylinder, sounds with slightly different frequencies overlap with the exhaust pulsation, so that the quality of the exhaust sound deteriorates and becomes annoying noise.

  Further, since each branch pipe is connected to the merge pipe with a relatively large merge angle, the flow direction change at the merge section becomes large, resulting in an increase in ventilation resistance and a decrease in the output of the internal combustion engine.

  In recent years, in order to further improve the exhaust gas purification of the internal combustion engine, the position of the catalytic converter is arranged as upstream as possible in the exhaust system so that the catalyst temperature rises early after the internal combustion engine is started. It is requested. Therefore, from this point of view, the total length of the exhaust manifold that collects the exhaust systems of a plurality of cylinders is naturally limited, and it is desirable to make it as short as possible.

  An object of the present invention is to achieve the equalization of the exhaust pipe length of each cylinder while reducing the overall length of the exhaust manifold as much as possible, and further to reduce the ventilation resistance.

An exhaust manifold of an internal combustion engine according to the present invention collects exhaust systems of at least three cylinders arranged in series in a single flow path at a downstream end portion, from a cylinder located at the front end. A first exhaust pipe extending rearward along the cylinder row direction of the internal combustion engine and reaching the downstream end is provided. The remaining of the plurality of second exhaust pipes extending respectively from cylinders, each of the end portions, and the Te first axial different points odor of the exhaust pipe joins the first exhaust pipe said. Further, the second exhaust pipe extends from each cylinder so as to wrap around the outer periphery of the first exhaust pipe when viewed from the front of the engine, and from the direction different from the cylinder head side in the circumferential direction. It merges with the first exhaust pipe. In other words, the first exhaust pipe is configured so as to reach the downstream end portion from the foremost end cylinder at a substantially shortest distance without being unnecessarily curved. The second exhaust pipes of the other cylinders extend so as to wrap around the outer periphery of the first exhaust pipe so that the pipe length can be sufficiently secured.

  Therefore, the exhaust pipe length of each cylinder can be easily made equal without unnecessarily increasing the overall length of the exhaust manifold from the exhaust port to the downstream end.

  In each joining portion where the second exhaust pipe joins the first exhaust pipe, the central axis of the end of the first exhaust pipe and the central axis of the end of the second exhaust pipe form. The merging angle is substantially 0 °. That is, the end portion of the first exhaust pipe and the end portion of the second exhaust pipe that join each other are arranged in parallel to each other. As a result, the exhaust flow flowing through the first exhaust pipe and the exhaust flow flowing through the second exhaust pipe smoothly merge.

  Desirably, the second exhaust pipe extends from each cylinder to the front of the engine, and U-turns backward to join the first exhaust pipe. The upstream end of the second exhaust pipe desirably projects obliquely from the mounting flange toward the front of the engine, and the upstream end of the first exhaust pipe, on the contrary, It is desirable to project obliquely from the mounting flange toward the rear of the engine. By configuring in this way, equalization of the pipe length of each cylinder can be realized in a smaller exhaust manifold.

  According to the exhaust manifold of the internal combustion engine according to the present invention, the exhaust pipe length of each cylinder can be set within a limited length without increasing the overall length of the exhaust manifold from the exhaust port to the downstream end. It becomes possible to lengthen and improve the sound quality of the exhaust sound.

  Further, since the exhaust flow of each cylinder merges substantially in parallel, the ventilation resistance is reduced.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  1 to 6 show an embodiment in which the present invention is configured as an exhaust manifold 1 that collects exhaust systems of one bank of a V-type 6-cylinder internal combustion engine. For example, the cylinder head 2 of one bank The exhaust systems of the three cylinders, # 1, # 3, and # 5, are gathered in one flow path to the catalyst converter (not shown). 1 is a plan view of the exhaust manifold 1 as viewed from above the internal combustion engine, FIG. 2 is a bottom view as viewed from below the internal combustion engine, and FIG. 3 is a side view as viewed from the rear of the internal combustion engine. FIG. 5 is a side view seen from the front of the internal combustion engine, FIG. 5 is a front view seen from the side of the internal combustion engine, and FIG. 6 is a perspective view seen obliquely rearward and upward.

  The exhaust manifold 1 includes a first exhaust pipe extending rearward along the cylinder row direction (crankshaft axis direction) of the internal combustion engine from the exhaust port of the # 1 cylinder, which is the foremost cylinder, and an exhaust port of the # 3 cylinder. A second exhaust pipe for # 3 cylinder that extends and merges with the first exhaust pipe at a point relatively upstream, and extends from an exhaust port of the # 5 cylinder and relatively downstream from the first exhaust pipe In this embodiment, more specifically, the first exhaust pipe is connected to the exhaust port of the # 1 cylinder. # 1 branch pipe 11, intermediate pipe 12 constituting a first joining section described later, and outlet pipe 13 comprising a second joining section described later and a front tube connecting flange 14 at the downstream end. It is divided into and. The second exhaust pipe for the # 3 cylinder is composed of a # 3 branch pipe 15 connected to the exhaust port of the # 3 cylinder, and the second exhaust pipe for the # 5 cylinder is the exhaust of the # 5 cylinder. The # 5 branch pipe 16 is connected to the port. The upstream ends of the branch pipes 11, 15, 16 are welded to a mounting flange 17 common to each cylinder for mounting the exhaust manifold 1 to the side surface of the cylinder head 2. The front tube connecting flange 14 is connected to a front tube (not shown) having a catalytic converter.

  In the first exhaust pipe composed of the # 1 branch pipe 11, the intermediate pipe 12 and the outlet pipe 13, the upstream portion 11a of the # 1 branch pipe 11 connected to the mounting flange 17 is substantially L-shaped. In addition to being curved in this way, the front tube connecting flange 14 is substantially straightened from the # 1 cylinder without being curved unnecessarily. In particular, since the front tube extends under the vehicle floor, the first exhaust pipe as a whole extends obliquely downward from the # 1 cylinder (see FIG. 5). In the example shown in the figure, the outlet pipe 13 is slightly loosely curved as shown in FIGS. 1 and 6 due to restrictions on the positional relationship with other components in the vehicle. It has become. Similar to the # 3 branch pipe 15 and the # 5 branch pipe 16, the # 1 branch pipe 11 is obtained by processing a metal pipe into a predetermined curved shape and cross-sectional shape by hydraulic processing or the like. The upstream end of the # 1 branch pipe 11 projects obliquely from the mounting flange 17 toward the rear of the engine. The intermediate tube 12 is formed in a slightly tapered cylindrical shape having a flat inlet portion 12a and an outlet portion 12b having a D-shaped cross section. The downstream end portion 11b of the # 1 branch pipe 11 is straight at a position biased toward the inlet portion 12a of the intermediate pipe 12, particularly one of the inlet portions 12a (the side closer to the cylinder head 2 when viewed from above). Connected and welded together. The outlet pipe 13 has a cylindrical shape with a flat inlet portion 13a, gradually approaches a perfect circular shape from the inlet portion 13a toward the downstream side, and the front tube connecting flange 14 is welded to the downstream end portion. ing. The outlet portion 12b of the intermediate pipe 12 is connected in a straight line at a position that is biased toward the inlet portion 13a of the outlet pipe 13, particularly one of the inlet portions 13a (the side closer to the cylinder head 2 when viewed from above). And it is welded.

  On the other hand, the # 3 branch pipe 15 as a whole has a shape that is curved so as to be substantially C-shaped or substantially U-shaped, and the upstream portion 15a connected to the mounting flange 17 has The intermediate portion 15b protrudes obliquely from the mounting flange 17 toward the front of the engine, crosses over the # 1 branch pipe 11, and curves downward so as to wrap around the outer periphery of the # 1 branch pipe 11. . Then, it curves downward toward the downstream side of the # 1 branch pipe 11 while curving downward from the vicinity immediately after crossing over the upper portion of the # 1 branch pipe 11, and the downstream end portion 15 c is downstream of the # 1 branch pipe 11. It is located side by side in parallel with the side tip portion 11b. The downstream end 15c is located on the opposite side of the inlet 12a of the intermediate pipe 12, particularly the # 1 branch pipe 11 in the inlet 12a (the side opposite to the cylinder head 2 when viewed from above). Are connected and welded in a straight line. That is, the # 3 branch pipe 15 serving as the second exhaust pipe extends from the # 3 cylinder so as to be wound around the # 1 branch pipe 11 and from the direction opposite to the cylinder head 2 in the circumferential direction. # 1 joins the flow path of the branch pipe 11. Here, the tube length of the # 3 branch tube 15 is set equal to the tube length of the # 1 branch tube 11.

  FIG. 9 is an exploded view showing the # 1 branch pipe 11 and the # 3 branch pipe 15 with the intermediate pipe 12 removed, and FIGS. 10 and 11 show only the intermediate pipe 12 from the inlet side and the outlet side. FIG. As shown in the figure, a partition plate 21 is welded and fixed to the center portion of the inlet portion 12a having a flat oval shape in the intermediate tube 12, and thereby the inlet portion 12a is partitioned into a "θ" shape. . The downstream tip portion 11b of the # 1 branch pipe 11 and the downstream tip portion 15c of the # 3 branch pipe 15 are each processed into a D-shaped cross section so as to correspond to the pair of D-shaped opening shapes. , Respectively, are fitted into each D-shaped opening of the inlet portion 12a and welded. Note that the diameter of the peripheral edge of the inlet 12a of the intermediate pipe 12 is slightly increased stepwise so as to form a fitting part that fits outside the # 1, # 3 branch pipes 11, 15. .

  The # 5 branch pipe 16 for the # 5 cylinder, like the above-described # 3 branch pipe 15, has a generally curved shape so as to form a substantially C-shape or a substantially U-shape, and is attached The upstream portion 16a connected to the flange 17 protrudes obliquely from the mounting flange 17 toward the engine front, and the intermediate portion 16b crosses over the intermediate tube 12, and the outer periphery of the intermediate tube 12 Curve downward to wrap around. And it curves toward the downstream side of the intermediate pipe 12 while curving downward from the vicinity immediately after crossing the upper part of the intermediate pipe 12, and the downstream end portion 16c is arranged in parallel with the outlet portion 12b of the intermediate pipe 12. Located at. The downstream end 16c is located at the inlet 13a of the outlet pipe 13, particularly at a position opposite to the intermediate pipe 12 in the inlet 13a (on the side opposite to the cylinder head 2 when viewed from above). Connected in a straight line and welded. That is, the # 5 branch pipe 16 serving as the second exhaust pipe extends from the # 5 cylinder so as to be wound around the intermediate pipe 12 serving as the first exhaust pipe, and is opposite to the cylinder head 2 when viewed in the circumferential direction. From the direction in which the flow passes, it merges into the flow path of the intermediate pipe 12. Here, the # 5 branch pipe 16 is curved so as to make a greater detour from the exhaust port position to the front and above the engine than the # 3 branch pipe 15, and the pipe length thereof is larger than that of the # 3 branch pipe 15. Is also long. More preferably, the curved shape of the # 5 branch pipe 16 is set so as to be longer than the # 3 branch pipe 15 by the length of the intermediate pipe 12. Thereby, the substantial pipe length of each cylinder from each exhaust port to the front tube connecting flange 14 is equal.

  7 is an exploded view showing the intermediate pipe 12 and the # 5 branch pipe 16 with the outlet pipe 13 removed, and FIG. 8 is an exploded view showing the intermediate pipe 12 with the # 5 branch pipe 16 further removed. FIG. 12 is a perspective view showing only the outlet pipe 13 from the inlet side, and FIG. 13 is a perspective view of a state in which the intermediate pipe 12 is combined with this. As shown in the drawing, a partition plate 22 is welded and fixed to an intermediate portion (specifically, a position deviated from the center to one side) of the inlet portion 13a having a flat oval shape of the outlet pipe 13, and thereby the inlet portion. 13a is partitioned in a “θ” shape. Then, the outlet portion 12b of the intermediate pipe 12 and the downstream end portion 16c of the # 5 branch pipe 16 are respectively machined into a D-shaped cross section so as to correspond to the pair of D-shaped opening shapes, respectively. It fits in each D-shaped opening of 13a, and is welded. The peripheral edge of the inlet portion 13a of the outlet pipe 13 is the same as the peripheral edge of the inlet portion 12a of the intermediate pipe 12 described above so as to form a fitting portion that fits outside the intermediate pipe 12 and the # 5 branch pipe 16. However, it is expanding slightly step by step. In addition, when the opening shape of the inlet portion 12a of the intermediate pipe 12 and the opening shape of the inlet portion 13a of the outlet pipe 13 are compared with each other, as is apparent from FIG. The dimensions of the major axis direction are almost the same, and the outlet pipe 13 is larger.

  FIG. 14 is a cross-sectional view of the vicinity of the intermediate pipe 12 and the outlet pipe 13 serving as a merging portion. As shown in the figure, the second exhaust pipe for the # 3 cylinder consisting of the # 3 branch pipe 15 is the intermediate pipe compared to the first exhaust pipe consisting of the # 1 branch pipe 11, the intermediate pipe 12 and the outlet pipe 13. 12 merge at the inlet 12a side. In other words, the flow path of the # 1 branch pipe 11 and the flow path of the # 3 branch pipe 15 merge with each other in the first merge section 31 constituted by the intermediate pipe 12. Here, the central axis L1 at the end of the # 1 branch pipe 11 and the central axis L3 at the end of the # 3 branch pipe 15 are parallel to each other, that is, the merging angle formed by both is substantially 0 °. It is. It should be noted that the length of the section in which the downstream end portion 11b of the # 1 branch pipe 11 and the downstream end portion 15c of the # 3 branch pipe 15 are parallel to each other is the exhaust gas flowing into the first junction 31 from both. The length is set appropriately so that a spiral flow is not generated by the flow. The intermediate pipe 12 serving as the first junction 31 extends downstream with a sufficiently large passage cross-sectional area, and the exhaust flows from the # 1 and # 3 branch pipes 11 and 15 are mixed while flowing in a straight line. To do.

  Similarly, the second exhaust pipe for the # 5 cylinder including the # 5 branch pipe 16 joins the intermediate pipe 12 serving as the first exhaust pipe on the inlet portion 13a side of the outlet pipe 13. In other words, the flow path of the intermediate pipe 12 and the flow path of the # 5 branch pipe 16 merge with each other at the second merge section 32 constituted by the inlet section 13a side portion of the outlet pipe 13. Here, the central axis L4 at the end of the intermediate pipe 12 and the central axis L5 at the end of the # 5 branch pipe 16 are parallel to each other, that is, the merging angle formed by both is substantially 0 °. . The length of the section in which the downstream end portion 16c of the # 5 branch pipe 16 and the intermediate pipe 12 are parallel to each other is set so that a spiral flow is not generated by the exhaust flow flowing into the second merge portion 32 from both. It is set to an appropriate length. The upstream side portion of the outlet pipe 13 serving as the second merging portion 32 extends downstream with a sufficiently large passage cross-sectional area, and the exhaust flow from the intermediate pipe 12 and the # 5 branch pipe 16 is linear. Mix while flowing.

  FIG. 15 schematically shows the pipe structure of the exhaust manifold 1, and as described above, the first exhaust pipe including the # 1 branch pipe 11, the intermediate pipe 12, and the outlet pipe 13 is the whole. As shown in FIG. 2, the # 3 branch pipe 15 and the # 5 branch pipe 16 having a U-turn shape are joined together while winding around the # 1 cylinder. Is substantially 0 °. Further, FIG. 16 shows the downstream end portion 11b of the # 1 branch pipe 11 and the # 3 branch on the projection view seen from the arrow X direction of FIG. 15 so that the central axis of the first exhaust pipe is seen from the front. The positions of the three ends of the downstream end portion 15c of the pipe 15 and the downstream end portion 16c of the # 5 branch pipe 16 are shown. As shown in FIG. Adjacent to each other. From the inside, the downstream end 11b of the # 1 branch pipe 11, the downstream end 15c of the # 3 branch pipe 15, and the downstream end 16c of the # 5 branch pipe 16 from the inner side with the mounting flange 17 as the innermost side. They are arranged in order, but the three are arranged so that the outer ones are relatively slightly higher.

  In the exhaust manifold 1 configured as described above, the # 3 branch pipe 15 and the # 5 branch pipe 16 are configured to wrap around the outer periphery of the first exhaust pipe, thereby avoiding an increase in the overall size. The substantial tube length of each cylinder from each exhaust port to the flange 14 for connecting the front tube can be made equal, and the sound quality of the exhaust sound can be improved. In particular, the upstream end portion of the # 1 branch pipe 11 projects obliquely from the mounting flange 17 to the rear of the engine and passes through the shortest distance to the front tube connecting flange 14. The # 3 and # 5 branch pipes 15 and 16 have their upstream ends projecting obliquely forward from the mounting flange 17 toward the front of the engine and U-turns, so that the branch pipes 11, 15 and 16 are projected to the side. The position of the flange 14 for connecting the front tube can be reduced, and the position of the flange 14 for connecting the front tube can be relatively located in front of the engine (that is, the overall length of the exhaust manifold can be reduced).

  In terms of the sound quality of the exhaust sound, it is desirable that the difference in tube length between the shortest tube length and the longest tube length among the three cylinders is 50 mm or less. In the configuration of the above embodiment, this condition is easily set. It is possible to meet

  In addition, since the merging angles at the merging portions 31 and 32 are both 0 ° and the two flows are mixed while flowing substantially in parallel, the airflow resistance at the merging portion can be minimized. Thereby, the volume efficiency in a high-speed area improves.

  Further, the intermediate pipe 12 and the outlet pipe 13 constituting the joining portions 31 and 32 are separate parts, and the branch pipes 11, 15, and 16 are individually manufactured, and then are integrated by welding. Therefore, manufacture and assembly of each part become easy. In particular, the end portions of the branch pipes 11, 15, 16 and the end portions of the intermediate pipe 12 are welded in the form of being inserted into the openings of the intermediate pipe 12 and the outlet pipe 13, respectively. Will be excellent.

  In the above embodiment, as shown in FIG. 16, the downstream tip 11b of the # 1 branch pipe 11, the downstream tip 15c of the # 3 branch pipe 15, and the downstream tip 16c of the # 5 branch pipe 16 are provided. The persons are arranged in a horizontal row on the projection view. However, as shown in FIG. 17, it is also possible that these three persons are arranged adjacent to each other so as to form a vertex of a triangle. Such a configuration can be realized, for example, by winding the # 5 branch pipe 16 around the outer circumference of the intermediate pipe 12 over a larger angle range and joining the outlet pipe 13 below the intermediate pipe 12. . With such a configuration, there is an advantage that the rigidity of the exhaust manifold 1 integrated by welding can be obtained higher.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the exhaust manifold for one bank of a V-type 6-cylinder internal combustion engine, but is limited to one bank of a V-type 8-cylinder internal combustion engine. An exhaust manifold or an exhaust manifold of an in-line four-cylinder internal combustion engine can be used.

The top view which looked at the exhaust manifold of one Example from the upper direction of the internal combustion engine. The bottom view which similarly looked at the exhaust manifold from the lower part of an internal-combustion engine. The side view which similarly looked at the exhaust manifold from the back of an internal-combustion engine. The side view which similarly looked at the exhaust manifold from the front of an internal-combustion engine. The front view which similarly looked at the exhaust manifold from the side of the internal combustion engine. The perspective view which similarly looked at the exhaust manifold from the diagonally backward and upper point. An exploded view showing the intermediate pipe and the # 5 branch pipe with the outlet pipe removed. Further, the exploded view showing the intermediate pipe with the # 5 branch pipe removed. An exploded view showing the # 1 branch pipe and the # 3 branch pipe with the intermediate pipe removed. The perspective view which showed only the intermediate pipe from the entrance side. The perspective view which showed only the intermediate pipe from the exit side. The perspective view which showed only the exit pipe | tube from the entrance side. The perspective view of the state which combined the intermediate pipe with the exit pipe. Sectional drawing of the vicinity of the intermediate pipe and outlet pipe used as a confluence | merging part. Explanatory drawing which showed typically the pipe line structure of an exhaust manifold. Explanatory drawing which shows the positional relationship of the downstream front-end | tip part of each branch pipe seen from the arrow X direction of FIG. FIG. 17 is an explanatory view similar to FIG. 16, showing an embodiment in which the positional relationship between the downstream end portions of the branch pipes is varied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exhaust manifold 11 ... # 1 branch pipe 12 ... Intermediate pipe 13 ... Outlet pipe 15 ... # 3 branch pipe 16 ... # 5 branch pipe 17 ... Mounting flange 31 ... 1st junction part 32 ... 2nd junction part

Claims (8)

In an exhaust manifold of an internal combustion engine that collects exhaust systems of at least three cylinders arranged in series in one flow path at a downstream end,
A first exhaust pipe extending rearwardly from the cylinder located at the foremost end along the cylinder row direction of the internal combustion engine and reaching the downstream end;
Extend from each of the remaining cylinders, and each of the end portions, and a plurality of second exhaust pipes merging into a first exhaust pipe the Te said first axial different points odor of the exhaust pipe,
And the merging angle formed by the central axis of the end portion of the first exhaust pipe and the central axis of the end portion of the second exhaust pipe at each merging portion is substantially 0 °,
When viewed from the front of the engine, the second exhaust pipe extends from each cylinder so as to wrap around the outer periphery of the first exhaust pipe, and the first exhaust pipe extends from the direction different from the cylinder head side in the circumferential direction. An exhaust manifold for an internal combustion engine, wherein the exhaust manifold merges with an exhaust pipe of the engine.   2. The exhaust manifold for an internal combustion engine according to claim 1, wherein an end of the first exhaust pipe and an end of the second exhaust pipe that join each other are arranged in parallel to each other.   3. The internal combustion engine according to claim 1, wherein the second exhaust pipe extends from each cylinder toward the front of the engine, and U-turns backward to join the first exhaust pipe. 4. Exhaust manifold.   The exhaust manifold for an internal combustion engine according to claim 3, wherein an upstream end portion of the second exhaust pipe protrudes obliquely from the mounting flange toward the front of the engine.   The exhaust manifold of the internal combustion engine according to claim 4, wherein an upstream end portion of the first exhaust pipe projects obliquely from the mounting flange toward the rear of the engine.   An exhaust manifold that collects the exhaust systems of three cylinders into one flow path, and the three of the two second exhaust pipe ends and the first exhaust pipe are the center of the first exhaust pipe. 6. An exhaust manifold for an internal combustion engine according to claim 1, wherein the exhaust manifolds are adjacent to each other in a horizontal row on a projected view of the shaft as viewed from the front.   An exhaust manifold that collects the exhaust systems of three cylinders into one flow path, and the three of the two second exhaust pipe ends and the first exhaust pipe are the center of the first exhaust pipe. 6. An exhaust manifold for an internal combustion engine according to claim 1, wherein the exhaust manifolds are adjacent to each other so as to form an apex of a triangle on a projection as viewed from the front.   The exhaust manifold for an internal combustion engine according to any one of claims 1 to 7, wherein an exhaust pipe length of each cylinder to the downstream end is equal.

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