Intake manifold

Abstract

To provide an intake manifold that suppresses a pressure loss while improving a pressure resisting strength.SOLUTION: An intake manifold 1 made of a resin is applied to an engine, and has a surge tank 2 into which intake air flows, and branch pipes 3a, 3b that are branched from the surge tank 2 and connected to intake ports of the engine. The intake manifold has a pillar portion 20 that penetrates through an internal space of the surge tank 2 and connects an inner wall 12 and an outer wall 13 facing each other. A cross section of the pillar portion 20 perpendicular to an extending direction thereof has an oval shape elongated in a passing direction of the intake air inside the surge tank 2.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a structure of an intake manifold used in an engine. [Background technology]

[0002] In recent years, plastic intake manifolds have been widely used in engines. For example, Patent Document 1 describes a plastic intake manifold used in a multi-cylinder engine used in an outboard motor, etc. This intake manifold is integrally formed with a surge tank and branch pipes branching from the surge tank and extending to each cylinder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-54472 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of intake manifolds used in relatively large engines such as outboard motors, the size of the intake manifold increases along with the size of the engine, but because the manifold is made of resin, it is difficult to obtain sufficient pressure resistance. One possible solution is to increase the pressure resistance of the intake manifold by installing a support pillar connecting the opposing walls in the center of the surge tank. However, this creates problems as the support pillar obstructs the flow of intake air inside the surge tank, increasing pressure loss and reducing intake performance.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide an intake manifold which has improved pressure resistance and reduced pressure loss. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the intake manifold of the present invention is applied to an engine having multiple cylinders, and is an intake manifold having a surge tank into which intake air flows, and a branch pipe branching off from the surge tank and connecting to an intake port of the engine, wherein the surge tank has an internal space formed between opposing first and second wall surfaces, the first and second wall surfaces are connected by a support portion that penetrates approximately the center of the internal space, and a cross section perpendicular to the extension direction of the support portion has an oval shape that is long in the direction in which the intake air passes through the internal space.

[0007] Preferably, a plate-shaped reinforcing rib is provided connecting the support portion to at least one of the first wall surface and the second wall surface, and the reinforcing rib is arranged to extend along the direction in which the intake air passes through the internal space.

[0008] Preferably, the cross-sectional area of ​​the transverse section of the support portion varies depending on the position in the extension direction of the support portion.

[0009] Preferably, the intake manifold is configured by connecting a first member having either the first wall surface or the second wall surface, and a second member having the other of the first wall surface and the second wall surface and the support portion.

[0010] Preferably, the intake manifold is made of resin. Effect of the Invention

[0011] According to the intake manifold of the present invention, by providing a support part with an oval cross section in the center of the surge tank, the diameter in one direction is made longer than that of a support part with a circular cross section, and the strength of the support part itself can be increased. Also, by making the end part of the support part connected to the first or second wall surface longer in one direction to have an oval shape, the circumferential distance and area of ​​the end part of the support part can be increased, and the strength of the connection part between the end part of the support part and the first or second wall surface can be increased. This makes it possible to increase the pressure resistance strength of the entire intake manifold. Furthermore, by making the cross section of the support portion long along the intake air flow inside the surge tank of the intake manifold, it is possible to reduce the obstruction of the intake air flow and suppress an increase in pressure loss. [Brief description of the drawings]

[0012] [Figure 1] 1 is a side view of an outboard motor equipped with an engine that employs an intake manifold according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a front view of an intake manifold according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a rear view of the intake manifold of the present embodiment. [Figure 4] FIG. 2 is a side view of the intake manifold of the present embodiment. [Diagram 5] 4 is a perspective view showing the internal structure of a surge tank portion of a second housing in the embodiment. FIG. [Figure 6] 5A to 5C are diagrams showing the shape of a fixing portion of a support portion in a first housing of the present embodiment. [Figure 7] 5A to 5C are explanatory diagrams showing a cross-sectional shape of a support column in the first housing of the present embodiment. [Figure 8] 13 is an explanatory diagram of a cross-sectional shape of a support part in a first housing of a reference embodiment. FIG. [Figure 9] 1 is an example of a graph comparing the pressure resistance of a reference embodiment with the pressure resistance of this embodiment. [Figure 10] 1 is an example of a graph comparing the pressure loss of a reference embodiment with the pressure loss of this embodiment. [Figure 11] FIG. 1 is a diagram illustrating an example of a visualization of the flow of intake air in an intake manifold in the reference embodiment and the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1 is a side view of an outboard motor OM equipped with an engine E that employs an intake manifold 1 according to one embodiment of the present invention. In FIG. 1, a part of an engine cover EC of the outboard motor OM is cut away to show the inside. FIG. 2 is a front view of the intake manifold 1 according to one embodiment of the present invention. FIG. 3 is a rear view of the intake manifold 1. FIG. 4 is a side view of the intake manifold 1. For ease of explanation, as shown in FIG. 1, the up-down direction in an example in which the intake manifold 1 is attached to the engine E of the outboard motor OM is defined as the Z direction, the left-right width direction of the outboard motor OM (the front-rear direction in FIG. 1) is defined as the X direction, and the front-rear direction of the outboard motor OM (the front-rear direction of the ship S) is defined as the Y direction.

[0015] As shown in FIG. 1, an intake manifold 1 of this embodiment is used in a relatively large multi-cylinder engine such as an engine E that drives a propeller P of an outboard motor OM.

[0016] The intake manifold 1 of this embodiment is attached to an engine E having, for example, three cylinders aligned vertically. As shown in Figures 2 to 4, the intake manifold 1 includes a surge tank 2 having a predetermined volume and receiving intake air from a throttle valve, and three branch pipes 3a, 3b, and 3c connecting the surge tank 2 to the intake ports of the engine cylinders. The three branch pipes 3a, 3b, and 3c are aligned in the Z direction and extend in the Y direction from one side of the surge tank 2 in the Y direction.

[0017] The intake manifold 1 is made of resin and is divided in the X direction into a first housing 10 (first member) and a second housing 11 (second member). The first housing 10 is located on the engine side, and the second housing 11 is located on the opposite side of the engine with respect to the first housing 10. An internal space for the surge tank 2 and each of the branch pipes 3a, 3b, and 3c is formed between an inner wall 12 (first wall surface) of the first housing 10 installed along the side of the engine and an outer wall 13 (second wall surface) of the second housing 11.

[0018] An intake port 15 for introducing intake air into the surge tank 2 is provided on the inner wall 12 of the first housing 10 at a position facing the internal space of the surge tank 2. The intake port 15 is provided at a position in the Y direction on the opposite side to the branch pipes 3a, 3b, and 3c from the center position of the surge tank 2 in the Y direction.

[0019] Fig. 5 is a perspective view showing the internal structure of the surge tank 2 of the second housing 11. Fig. 6 is a view of a portion of the first housing 10 that receives welding of the support column 20, as viewed from the second housing 11 side. Fig. 7 is a view showing the shapes of the support column 20 and the reinforcing rib 30 as viewed from the direction A shown in Fig. 5, and is an explanatory view of the cross-sectional shape of the support column 20.

[0020] 5, a support column 20 extending in the X direction from the outer wall 13 toward the first housing 10 is formed in approximately the center of the surge tank 2 in the second housing 11, more specifically, in approximately the center position of the surge tank 2 in the Z direction and the Y direction. The tip of the support column 20 abuts against a recess 21 provided on the internal space side of the inner wall 12 of the first housing 10 shown in Fig. 6. The recess 21 is formed by recessing the internal space side of the surge tank 2.

[0021] The first housing 10 and the second housing 11 are fixed to each other by, for example, vibration welding at the outer periphery and at the joints of the branch pipes 3a to 3c. In addition, the contact portion between the tip of the support part 20 of the second housing 11 and the recess 21 of the first housing 10 is also fixed by vibration welding or the like. Note that the tip surface 20a of the tip of the support part 20 that contacts and is welded to the recess 21 has a shape substantially similar to a cross section perpendicular to the extension direction of the support part 20, and is an ellipse that is long in the Y direction.

[0022] As shown in Figures 2 and 3, the outer periphery of the first housing 10 is provided with several bosses having bolt holes 25 for fixing the intake manifold 1 to the engine. Also, as shown in Figures 4 and 6, the recess 21 of the first housing 10 is provided with a cylindrical protrusion 26 that protrudes toward the second housing 11 in the X direction. A hole 27 penetrates the center of the protrusion 26 in the protruding direction (X direction). The tip of the support 20 of the second housing 11 is provided with a protrusion insertion hole 28 into which the protrusion 26 is inserted. A cylindrical collar (not shown) having approximately the same length as hole 27 is inserted into hole 27. With respect to intake manifold 1 in which first housing 10 and second housing 11 are welded together by inserting protrusion 26 into protrusion insertion hole 28, a bolt is inserted into the collar inserted into hole 27 of protrusion 26 from the second housing 11 side to penetrate first housing 10, and the tip of the bolt is fastened to a female thread (not shown) for fixing provided on engine E. In this way, intake manifold 1 is fixed to engine E at several points on the outer periphery as well as at the center of surge tank 2. The size and protruding length of the tip of the protrusion 26 are set so that the head of the bolt inserted into the hole 27 together with the collar comes into contact with the tip of the protrusion 26 and does not come into contact with the second housing 11. Therefore, in the center of the surge tank 2, the first housing 10 is fixed to the engine E by the bolt, and the second housing 11 is fixed to the engine E via the welded first housing 10.

[0023] 7, in this embodiment, a cross section perpendicular to the extension direction of the support portion 20 (XY direction cross section) is an ellipse that is long in the Y direction, similar to the tip surface 20a of the support portion 20. The support portion 20 is located between the intake port 15 of the intake manifold 1 and the branch pipes 3a to 3c in the Y direction, so that the intake air that flows from the intake port 15 into the surge tank 2 and heads toward the branch pipes 3a to 3c passes in the vicinity of the support portion 20 so as to flow in the Y direction. Therefore, the cross section of the support portion 20 is an ellipse that is long in the intake air passing direction.

[0024] The support column 20 is located approximately in the center of the surge tank 2 in the Z direction, and is located approximately in the same position in the Z direction as the central branch pipe 3b of the three branch pipes 3a to 3c. Therefore, the cross section of the support column 20 has an ellipse extending toward the branch pipe 3b.

[0025] 4, 5 and 7, a reinforcing rib 30 is provided which connects the outer wall 13 of the second housing 11 and the support portion 20. The reinforcing rib 30 is a plate-shaped member which connects the side wall of the support portion 20 on the branch pipe 3b side and the inner wall surface of the outer wall 13 of the second housing 11, and extends in the Y direction toward the branch pipe 3b side.

[0026] As described above, the intake manifold 1 of this embodiment is configured by connecting the first housing 10 and the second housing 11, and is provided with the support portion 20 that connects the inner wall 12 of the first housing 10 and the outer wall 13 of the second housing 11 in the center of the surge tank 2. The cross section perpendicular to the extension direction (X direction) of the support portion 20 has an oval shape that is long in the intake air passing direction (Y direction) inside the surge tank 2, and the elliptical tip surface 20a of the support portion 20 of the second housing 11 and the first housing 10 are welded and connected in the center of the surge tank 2.

[0027] In the intake manifold 1 of this embodiment, when the intake pressure rises, the inner wall 12 and the outer wall 13 of the surge tank 2 deform in a direction moving away from each other, and when the intake pressure drops, the inner wall 12 and the outer wall 13 of the surge tank 2 deform in a direction moving closer to each other. Therefore, the inner wall 12 and the outer wall 13 move with the fluctuation of the intake pressure, which makes it easy for stress to concentrate on the welded part of the support part 20.

[0028] In contrast, in this embodiment, the cross section of the support part 20 is an ellipse with the major axis in the Y direction. Therefore, compared to a reference embodiment in which the support part 40 is a circle with the same diameter as the minor axis of the support part 20 as shown in FIG. 8 described later, the cross-sectional area and circumferential distance of the support part 20 can be increased. This improves the strength of the support part 20 itself, and increases the area of ​​the welded part between the tip surface 20a of the support part 20 and the first housing 10, thereby increasing the strength of the welded part. In particular, by increasing the cross-sectional area of ​​the welded part where stress is concentrated due to the fluctuation of the intake pressure as described above, the stress concentration can be effectively alleviated, and damage (peeling) of the welded part between the first housing 10 and the second housing 11 can be suppressed, and the pressure resistance strength of the intake manifold 1 can be greatly increased.

[0029] Furthermore, since the support portion 20 is elliptical with the longer axis on the side in the direction in which the intake air passes through the surge tank 2, even if the cross-sectional area of ​​the support portion 20 is increased from that of a circle, the flow of intake air passing near the support portion 20 is not obstructed, and an increase in pressure loss within the surge tank 2 can be suppressed.

[0030] In addition, since the reinforcing rib 30 is provided to connect the outer wall 13 of the second housing 11 and the support portion 20, it is possible to increase the strength of the vicinity of the base portion of the support portion 20 of the second housing 11. Therefore, it is possible to further increase the pressure resistance strength of the intake manifold 1.

[0031] Furthermore, since the reinforcing ribs 30 extend in the intake air passing direction, an increase in pressure loss within the surge tank 2 due to the provision of the reinforcing ribs 30 can be suppressed.

[0032] FIG. 8 is a diagram showing the cross-sectional shape of the support part in the first housing of the reference embodiment. FIG. 9 is an example of a graph comparing the pressure resistance of the reference embodiment with that of this embodiment. FIG. 10 is an example of a graph comparing the pressure loss of the reference embodiment with that of this embodiment. FIG. 11 is an example of a diagram visualizing the flow of intake air in an intake manifold. The reference embodiment is an intake manifold 41 in which the cross section of the support part 40 is a circle having the same diameter as the minor diameter of the support part 20 of this embodiment as shown in FIG. 8 and does not have the reinforcing rib 30, and other parts are the same as the intake manifold 1 of this embodiment. In FIG. 10, the pressure loss from the intake port 15 to the port #1 of the branch pipe 3a, from the intake port 15 to the port #2 of the branch pipe 3b, and from the intake port 15 to the port #3 of the branch pipe 3c are shown in bar graphs for (A) the reference embodiment and (B) this embodiment, respectively. In addition, in Figure 10, the solid line indicates the average value of the three pressure losses from intake port 15 to ports #1 to #3, the dashed and dotted lines indicate the pressure losses within surge tank 2 among the pressure losses from intake port 15 to each of ports #1 to #3, and the dashed lines indicate the pressure losses in each of the branch pipes 3a to 3c.

[0033] In FIG. 11, of the intake air flowing from intake port 15 to each of ports #1 to #3, the flow of intake air from intake port 15 to port #2 is indicated by a solid line.

[0034] When the intake manifold 1 of this embodiment is compared through an experiment with an intake manifold 41 of a reference embodiment in which the support portion 40 has a circular cross section and does not have the reinforcing rib 30, it was found that the intake manifold 1 of this embodiment has a significantly improved pressure resistance strength compared to the reference embodiment, as shown in Fig. 9. This makes it possible to achieve a pressure resistance strength Rs1 higher than that required for the intake manifold 1, for example.

[0035] On the other hand, as shown in FIG. 10, it was found that the pressure loss was substantially the same in this embodiment and the reference embodiment for all of ports #1 to #3.

[0036] In FIG. 10, port #1 has a higher pressure loss than ports #2 and #3. This is mainly due to the fact that branch pipe 3a in this embodiment has a more complex shape than the other branch pipes 3b and 3c.

[0037] In addition, for ports #1 and #3, the pressure loss is slightly higher in this embodiment than in the reference embodiment, but for port #2, the pressure loss is almost the same in the reference embodiment and this embodiment. This is because the flow straightening effect of the reinforcing rib 30 on the intake air is largely reflected in port #2, which passes through the branch pipe 3b closest to the support portion 20.

[0038] Although the description of the embodiment is finished above, the aspects of the present invention are not limited to the above embodiment. For example, of making the cross section of the support portion 20 of the intake manifold 1 elliptical and providing the reinforcing rib 30, only making the cross section of the support portion 20 elliptical may be performed.

[0039] Furthermore, the elliptical shape of the support pillar 20 and the shape of the reinforcing rib 30 may be changed as appropriate. For example, the cross section of the support pillar 20 may be oval, with the width in the Z direction gradually narrowing toward the downstream side in the intake direction, or may be egg-shaped, other than an ellipse, as long as it is an oval shape that is longer in the Y direction, which is the intake air passage direction, than in the Z direction.

[0040] Furthermore, the position of the support portion 20, the shape of the support portion 20 such as the extending direction of the cross section, and the extending direction of the reinforcing rib 30 may be appropriately changed depending on the arrangement of the branch pipes 3a-3c relative to the surge tank 2, the shape of the branch pipes 3a-3c, and the shape of the internal space of the surge tank, i.e., depending on the manner in which the intake air passes through the intake manifold 1. For example, the support portion 20 may be shaped so that the cross-sectional area of ​​the cross section varies depending on the position in the extending direction of the support portion 20, thereby further reducing the pressure loss in the intake manifold 1.

[0041] In this embodiment, the support column 20 is provided on the second housing 11 on the opposite side to the engine E side, but the support column 20 may be provided on the first housing 10 on the engine E side.

[0042] In this embodiment, three branch pipes 3a to 3c are provided for a three-cylinder engine E, but the present invention is not limited to this and can be applied to engines with any number of cylinders. Furthermore, the installation direction of the intake manifold 1 is not limited. Furthermore, the present invention can be widely applied to intake manifolds for engines other than those for outboard motors. [Explanation of symbols]

[0043] 1. Intake manifold 2. Surge tank 3a, 3b, 3c branch pipe 10 First housing (first member) 11 Second housing (second member) 12 Inner wall (first wall) 13 Exterior wall (second wall) 20 Support section 30 Reinforcing rib

Claims

1. An intake manifold that is applied to an engine having a plurality of cylinders and includes a surge tank into which intake air flows, and a branch pipe that branches off from the surge tank and connects to an intake port of the engine, The surge tank has an internal space formed between a first wall surface and a second wall surface facing each other, The first wall surface and the second wall surface are connected by a support portion that penetrates substantially the center of the internal space, A cross section perpendicular to the extension direction of the support portion has an oval shape that is long in the direction in which the intake air passes through the internal space. An intake manifold for an engine.

2. a plate-shaped reinforcing rib connecting the support portion to at least one of the first wall surface and the second wall surface, The reinforcing rib is disposed so as to extend along the intake air passing direction.

2. The engine intake manifold of claim 1.

3. The cross-sectional area of ​​the cross section of the support portion varies depending on the position in the extension direction of the support portion.

2. The engine intake manifold of claim 1.

4. The intake manifold is A first member having one of the first wall surface and the second wall surface, and a second member having the other of the first wall surface and the second wall surface and the support portion are connected to each other.

2. The engine intake manifold of claim 1.

5. The intake manifold is made of resin.

2. The engine intake manifold of claim 1.

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