Intake manifold for internal combustion engine

Abstract

 An intake manifold including an intake manifold body (15) including a collector (5) and a plurality of branches (2, 3. 4) joined with each other through a connecting wall (7, 8), and a resonator (6) including a resonator body member (14) fixed onto an outer surface of the intake manifold body. Each of the branches has a thickness larger than that of the connecting wall. The resonator includes a resonator neck (30) and a resonator volume chamber (31) communicated with the collector through the resonator neck. The resonator neck has a resonator neck passage (29) formed between a pair of opposed resonator neck walls connected with the resonator body member and the outer surface of the intake manifold body. The resonator neck is disposed above one of the branches and extends along the one of the branches.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an intake manifold for an internal combustion engine.

[0002] Intake manifolds for an internal combustion engine of an automobile are well known, in which there are provided a surge tank and a plurality of branches which are connected to the surge tank and supplies air to cylinders of the engine.

[0003] Japanese Patent Provisional Publication No. 2003-139001 discloses an intake manifold with a resonator that is provided for the purpose of reducing noise in the intake manifold. The intake manifold includes an upper shell and a lower shell which are joined with each other by vibration welding to form a plurality of individual pipes for distributing intake air to the engine cylinders and a resonance space. The upper shell is formed with a plurality of openings and a cover is fixed by vibration welding to the upper shell so as to cover the openings. A reflection or resonator chamber is formed between the upper shell and the cover and communicated with the resonance space through the openings.

SUMMARY OF THE INVENTION

[0004] However, in the intake manifold of the above-described conventional art, only an outer peripheral edge of the cover is fixed to the upper shell of the intake manifold and a joint portion to be fixed to the upper shell by vibration welding has an evenly wide width. Therefore, in a case where the reflection chamber is enlarged in volume, a wall thickness of the cover should be increased or the cover should be provided with a rib in order to ensure rigidity of the cover. This leads to increase in weight of the intake manifold.

[0005] It is an object of the present invention to solve the above-described problem in the technologies of the conventional art and to provide an intake manifold including a resonator in which rigidity of the resonator can be ensured without causing increase in total weight of the intake manifold.

[0006] In one aspect of the present invention, there is provided an intake manifold for an internal combustion engine, the intake manifold comprising:

an intake manifold body including a collector and a plurality of branches which are connected to the collector in parallel to each other and joined with each other through a connecting wall between the adjacent branches, the branches being adapted to distribute intake air to cylinders of the engine; and

a resonator including a resonator body member that is fixed onto an outer surface of the intake manifold body, the resonator body member cooperating with the outer surface of the intake manifold body to define a space inside the resonator,

wherein the outer surface of the intake manifold body is formed into a wave shape that includes a crest formed at each of the branches and a valley formed at the connecting wall,

wherein each of the branches defines a branch passage therein and has a thickness larger than that of the connecting wall,

wherein the resonator includes a resonator neck and a resonator volume chamber within the space, the resonator volume chamber being communicated with the collector through the resonator neck,

wherein the resonator neck has a resonator neck passage formed between a pair of resonator neck walls which are opposed to each other and connected with the resonator body member and the outer surface of the intake manifold body, and the resonator neck is disposed above one of the branches and extends along the one of the branches.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a perspective view of an intake manifold for an internal combustion engine, according to the present invention.

[0008] FIG. 2 is an exploded perspective view of the intake manifold of a first embodiment of the present invention.

[0009] FIG. 3 is a cross-section of an essential part of the intake manifold of the first embodiment, taken substantially perpendicular to a longitudinal direction of branches of the intake manifold.

[0010] FIG. 4 is a perspective view of the essential part of the intake manifold of the first embodiment, showing an intake manifold body.

[0011] FIG. 5 is a perspective view of the essential part of the intake manifold of the first embodiment, showing a resonator body when viewed from a rear side thereof.

[0012] FIG. 6 is a cross-section of the essential part of the intake manifold of the first embodiment, taken in the longitudinal direction of the branches of the intake manifold.

[0013] FIG. 7 is a view similar to FIG. 6, but shows a second embodiment of the intake manifold of the present invention.

[0014] FIG. 8 is a view similar to FIG. 6, but shows a third embodiment of the intake manifold of the present invention.

[0015] FIG. 9 is a view similar to FIG. 4, but shows the third embodiment of the intake manifold of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring now to FIG. 1 to FIG. 6, there is shown an intake manifold for a multi-cylinder internal combustion engine of a vehicle, according to a preferred embodiment of the present invention. In this embodiment, the intake manifold is applied to an in-line three-cylinder engine.

[0017] As shown in FIG. 1, intake manifold 1 includes three branches 2, 3, 4 that distribute intake air to three cylinders (not shown) of the engine, respectively, collector 5 that is disposed on an intake upstream side of branches 2, 3, 4, and resonator 6 that is communicated with collector 5. Intake manifold 1 is made of a resin material. Branches 2, 3, 4 are connected with collector 5 and extend in parallel to each other. Branches 2, 3, 4 are joined with each other through connecting walls 7, 8 that extend between adjacent two of branches 2, 3, 4. Specifically, adjacent branches 2 and 3 are joined with each other through connecting wall 7 that extends between branches 2 and 3, and adjacent branches 3 and 4 are joined with each other through connecting wall 8 that extends between branches 3 and 4. Intake air is introduced into an inside of intake manifold 1 through intake air inlet 9 that is disposed on an intake upstream side of collector 5. Intake air inlet 9 is opened to a mount surface of upstream-side flange 10 which is connected to an intake duct, not shown. Downstream-side flange 11 is formed at intake downstream ends of respective branches 2, 3, 4. Intake air outlets are opened to a mount surface of downstream-side flange 11 which is connected to a cylinder head, not shown. Upstream-side flange 10 and downstream-side flange 11 are formed in first intake manifold body member 12 of intake manifold body 15 as explained later.

[0018] As shown in FIG. 2, intake manifold 1 is substantially constituted of first intake manifold body member 12 as a lower shell, second intake manifold body member 13 as an upper shell and generally rectangular dish-shaped resonator body member 14. First intake manifold body member 12 and second intake manifold body member 13 cooperate with each other to form intake manifold body 15 that includes hollow collector 5 and hollow branches 2, 3, 4. Second intake manifold body member 13 and resonator body member 14 cooperate with each other to form resonator 6.

[0019] Intake manifold body 15 is formed by joining first intake manifold body member 12 and second intake manifold body member 13 with each other on a curved joint plane that extends along a curved profile of respective branches 2, 3, 4. Specifically, the curved joint plane extends in a longitudinal direction of branches 2, 3, 4 and in a direction of a row of branches 2, 3, 4 so as to continuously connect branches 2, 3, 4 to each other. The joint plane extends along central axes of branches 2, 3, 4 which extend in the longitudinal direction of branches 2, 3, 4. That is, the joint plane is designed to extend substantially along center lines of branch passages 16, 17, 18 which are formed in branches 2, 3, 4. In other words, before joining first intake manifold body member 12 and second intake manifold body member 13 with each other, intake manifold body 15 is split into first intake manifold body member 12 and second intake manifold body member 13 on the joint plane as a split plane.

[0020] Branches 2, 3, 4 are formed by first branch halves 2A, 3A, 4A of first intake manifold body member 12 and second branch halves 2B, 3B, 4B of second intake manifold body member 13 which are joined with each other on the joint plane. As shown in FIG. 3, branches 2, 3, 4 define branch passages 16, 17, 18, respectively, which extend in the longitudinal direction of branches 2, 3, 4. First branch halves 2A, 3A, 4A and second branch halves 2B, 3B, 4B have a generally half-ellipse shape in cross section. Connecting walls 7, 8 are formed by first connecting wall halves 7A, 8A of first intake manifold body member 12 and second connecting wall halves 7B, 8B of second intake manifold body member 13 which are jointed with each other on the joint plane.

[0021] As shown in FIG. 2, first intake manifold body member 12 includes upstream-side flange 10, downstream-side flange 11, first collector portion 5A of collector 5, first branch halves 2A, 3A, 4A of branches 2, 3, 4 and connecting wall halves 7A, 8A of connecting walls 7, 8. Upstream-side flange 10, downstream-side flange 11, first collector portion 5A of collector 5, first branch halves 2A, 3A, 4A and connecting wall halves 7A, 8A are integrally formed with first intake manifold body member 12. Each of first branch halves 2A, 3A, 4A has a trough-shaped opening that extends in a longitudinal direction of each of branch halves 2A, 3A, 4A. Connecting wall halves 7A and 8A extend between the adjacent branch halves 2A, 3A and the adjacent branch halves 3A and 4A, respectively.

[0022] First collector portion 5A of collector 5 serves as a major portion of collector 5. First collector portion 5A has a rectangular or elliptic opening on an upper surface thereof. As shown in FIG. 2, first branch halves 2A, 3A, 4A are connected with first collector portion 5A to thereby communicate the trough-shaped openings of first branch halves 2A, 3A, 4A with the opening of first collector portion 5A. The trough-shaped openings of first branch halves 2A, 3A, 4A are merged into the opening of first collector portion 5A. That is, first intake manifold body member 12 is configured to have a single opening that is continuously communicated with both first collector portion 5A and first branch halves 2A, 3A, 4A.

[0023] Second intake manifold body member 13 is also configured to have a single opening that is continuously communicated with both second collector portion 5B and second branch halves 2B, 3B, 4B and cover the single opening of first intake manifold body member 12. Specifically, as shown in FIG. 2 and FIG. 3, second intake manifold body member 13 includes second collector portion 5B of collector 5, second branch halves 2B, 3B, 4B of branches 2, 3, 4 and second connecting wall halves 7B, 8B of connecting walls 7, 8. Second collector portion 5B, second branch halves 2B, 3B, 4B and second connecting wall halves 7B, 8B are integrally formed with second intake manifold body member 13. Second collector portion 5B has an opening on a lower surface thereof which corresponds to the opening of first collector portion 5A. Each of second branch halves 2B, 3B, 4B has a trough-shaped opening that extends in a longitudinal direction of each of second branch halves 2B, 3B, 4B. Connecting wall halves 7B and 8B extend between the adjacent branch halves 2B, 3B and the adjacent branch halves 3B and 4B, respectively. Second branch halves 2B, 3B, 4B are connected with second collector portion 5B to thereby communicate the trough-shaped openings of second branch halves 2B, 3B, 4B with the opening of second collector portion 5B. The trough-shaped openings of second branch halves 2B, 3B, 4B are merged into the opening of second collector portion 5B.

[0024] As shown in FIG. 2, first connecting flange 19 is formed along peripheral edges of the trough-shaped openings of first branch halves 2A, 3A, 4A and a peripheral edge of the opening of first collector portion 5A of first intake manifold body member 12. First connecting flange 19 has a substantially uniform width that extends along outer peripheral edges of the trough-shaped openings of first branch halves 2A and 4A and the peripheral edge of the opening of first collector portion 5A. First connecting flange 19 extends between opposed peripheral edges of the trough-shaped openings of the adjacent first branch halves 2A, 3A, 4A and forms first connecting wall halves 7A, 8A.

[0025] First projection 20 is formed on an upper surface of first connecting flange 19. First projection 20 projects from the upper surface of first connecting flange 19 and continuously extends along the peripheral edge of the opening of first collector portion 5A and the peripheral edges of the trough-shaped openings of first branch halves 2A, 3A, 4A of first intake manifold body member 12. First projection 20 that extends along the outside peripheral edges of the trough-shaped openings of first branch halves 2A and 4A and the peripheral edge of the opening of first collector portion 5A is located in a substantially middle position in the width direction of first connecting flange 19. First projection 20 has a strap-shaped top surface serving as a connection surface that is connected with a connection surface of second projection 22 of second connecting flange 21 of second intake manifold body member 13 by vibration welding as explained later. The connection surface of first projection 20 extends over the entire length of first projection 20.

[0026] Second connecting flange 21 is formed along peripheral edges of the trough-shaped openings of second branch halves 2B, 3B, 4B and a peripheral edge of the opening of second collector portion 5B of second intake manifold body member 13. Second connecting flange 21 has a substantially uniform width that extends along outer peripheral edges of the trough-shaped openings of second branch halves 2B and 4B and the peripheral edge of the opening of second collector portion 5B. Second connecting flange 21 extends between opposed peripheral edges of the trough-shaped openings of the adjacent second branch halves 2B, 3B, 4B and forms second connecting wall halves 7B, 8B.

[0027] Second projection 22 is formed on a lower or rear surface of second connecting flange 21 and located corresponding to first projection 20 of first intake manifold body member 12. Second projection 22 projects from the lower surface of second connecting flange 21 and continuously extends along the outer peripheral edges of the trough-shaped openings of second branch halves 2B and 4B and the peripheral edge of the opening of second collector portion 5B. Second projection 22 that extends along the outer peripheral edges of the trough-shaped openings of second branch halves 2B and 4B and the peripheral edge of the opening of second collector portion 5B is located in a substantially middle position in the width direction of second connecting flange 21. Second projection 22 has a strap-shaped top surface serving as a connection surface that extends over the entire length of second projection 22 and is connected with the connection surface of first projection 20 of first connecting flange 19 by vibration welding. First projection 20 and second projection 22 are connected with each other through the vibration-welded connection surfaces.

[0028] First intake manifold body member 12 and second intake manifold body member 13 are joined with each other by connecting first projection 20 and second projection 22 with each other by vibration welding while applying a suitable pressure thereto in a mutually abutting state.

[0029] Branches 2, 3, 4 define branch passages 16, 17, 18 on the inside thereof and have a vertical dimension or thickness larger than that of connecting walls 7, 8. The vertical dimension or thickness of branches 2, 3, 4 is a distance that extends between outer surfaces of first branch halves 2A, 3A, 4A and outer surfaces of second branch halves 2B, 3B, 4B which are opposed to each other in a vertical direction perpendicular to the joint plane of first intake manifold body member 12 and second intake manifold body member 13. The vertical dimension or thickness of connecting walls 7, 8 is a distance that extends between outer surfaces of first connecting wall halves 7A, 8A and outer surfaces of second connecting wall halves 7B, 8B. Therefore, intake manifold body 15 has an outer surface formed into a wave shape that includes three crests formed at branches 2, 3, 4 and two valleys formed at connecting walls 7, 8. Specifically, the crests are formed by the outer surfaces of second branch halves 2B, 3B, 4B and the valleys are formed by the outer surfaces of second connecting wall halves 7B, 8B.

[0030] As shown in FIG. 2 to FIG. 4, second intake manifold body member 13 has third projection 23 on an outer surface thereof that forms a part of the outer surface of intake manifold body 15. Specifically, second intake manifold body member 13 includes support wall 13a for supporting resonator body member 14 which is connected with peripheral side wall 24 of resonator body member 14 and forms a peripheral side wall of resonator 6. Second intake manifold body member 13 further includes a wall that is opposed to a top wall of resonator body member 14 and forms a bottom wall of resonator 6. Support wall 13a extends from the outer surface of second intake manifold body member 13 toward peripheral side wall 24 of resonator body member 14 in a direction substantially perpendicular to the joint plane of first intake manifold body member 12 and second intake manifold body member 13. Support wall 13a is configured to have a generally rectangular shape in top plan view corresponding to peripheral side wall 24 of resonator body member 14. Third projection 23 projects from a tip end of support wall 13a toward an end of peripheral side wall 24 of resonator body member 14 in the direction substantially perpendicular to the joint plane of first intake manifold body member 12 and second intake manifold body member 13. Third projection 23 continuously extends over an entire periphery of support wall 13a.

[0031] Resonator body member 14 is fixed onto the outer surface of second intake manifold body member 13. Resonator body member 14 includes fourth projection 25 that projects from the end of peripheral side wall 24 toward third projection 23 of second intake manifold body member 13 and continuously extends over an entire periphery of peripheral side wall 24. Second intake manifold body member 13 and resonator body member 14 are joined with each other by connecting third projection 23 and fourth projection 25 with each other by vibration welding while applying a suitable pressure to third projection 23 and fourth projection 25 in a mutually abutting state. Hermetically sealed space 26 is thus formed inside resonator 6 and defined between an inside surface of resonator body member 14 and the outer surface of second intake manifold body member 13 which is opposed to the inside surface of resonator body member 14 as shown in FIG. 3. Space 26 is communicated with an inside space of collector 5 via communication hole 27 that extends through second intake manifold body member 13 as shown in FIG. 4.

[0032] Resonator 6 that is formed by second intake manifold body member 13 and resonator body member 14 is a so-called Helmholtz resonator. Resonator 6 includes resonator neck 30 and resonator volume chamber 31 that is communicated with collector 5 through resonator neck 30. Resonator neck 30 and resonator volume chamber 31 are formed within space 26 between the outer surface of second intake manifold body member 13 and the inside surface of resonator body member 14. Resonator neck 30 has elongated resonator neck passage 29 that is formed between a pair of resonator neck walls 28, 28. Resonator neck walls 28, 28 are opposed to each other and extend parallel to each other in the longitudinal direction of branch half 3B.

[0033] As shown in FIG. 6, resonator neck passage 29 has one end at which communication hole 27 is disposed. Resonator neck passage 29 is communicated with the inside space of collector 5 through communication hole 27. The other end of resonator neck passage 29 is opened into resonator volume chamber 31. Resonator neck 30 is disposed on one of branches 2, 3, 4 and extends along the one of branches 2, 3, 4. In this embodiment, resonator neck 30 is located on central branch 3 and extends along central branch 3. A cross section and a length of resonator neck passage 29 and a volume of resonator volume chamber 31 may be suitably set on the basis of a required resonance frequency of resonator 6. Dimensions of various portions of resonator body member 14 may be suitably modified on the basis of the required resonance frequency of resonator 6. A configuration of an outer surface of resonator 6 is not limited to such a wave form as that of the outer surface of intake manifold body 15 and may be formed into other shapes. In this embodiment, the outer surface of resonator 6 is formed into a relatively flat surface.

[0034] Each of resonator neck walls 28, 28 is connected with resonator body member 14 and the outer surface of second intake manifold body member 13. Resonator neck wall 28 is formed by joining rib 32 of second intake manifold body member 13 which extends on the outer surface of second intake manifold body member 13 in the longitudinal direction of branch half 3B, with rib 33 of resonator body member 14 which extends on an inside surface of the top wall of resonator body member 14 corresponding to rib 32. Specifically, as shown in FIG. 2 and FIG. 3, rib 32 extends in the longitudinal direction of branch half 3B and extends from an outer surface of branch half 3B toward the inside surface of the top wall of resonator body member 14 in the direction substantially perpendicular to the joint plane of first intake manifold body member 12 and second intake manifold body member 13. Rib 32 has grooved portion 34 on a tip end portion thereof which extends over an entire length of rib 32 in the longitudinal direction. As shown in FIG. 6 and FIG. 3, rib 33 extends in the longitudinal direction of branch 3 and extends from the inside surface of the top wall of resonator body member 14 toward the outer surface of branch half 3B in the direction substantially perpendicular to the joint plane of first intake manifold body member 12 and second intake manifold body member 13. Rib 33 has fifth projection 35 that projects from a tip end of rib 33 so as to be engaged with bottom 34a of grooved portion 34 of rib 32. Rib 32 and rib 33 are joined with each other by connecting grooved portion 34 and fifth projection 35 with each other by vibration welding while applying a suitable pressure to grooved portion 34 and fifth projection 35 in a mutually engaged state. Thus, resonator neck wall 28 is formed.

[0035] Resonator neck wall 28 includes a first connecting portion at which rib 32 of second intake manifold body member 13 and rib 33 of resonator body member 14 are joined with each other by vibration welding. That is, the first connecting portion is formed by connecting fifth projection 35 of resonator body member 14 with bottom 34a of grooved portion 34 of rib 32 by vibration welding. The first connecting portion is smaller in width that extends in a direction crossing the row of branches 2, 3, 4, than a second connecting portion at which third projection 23 of second intake manifold body member 13 and fourth projection 25 of peripheral side wall 24 of resonator body member 14 are joined with each other by vibration welding. In other words, the width of fifth projection 35 of rib 33 is smaller than the respective widths of third projection 23 of second intake manifold body member 13 and fourth projection 25 of resonator body member 14. Further, the width of fifth projection 35 of rib 33 is smaller than the width of second projection 22 of second intake manifold body member 13.

[0036] In the first embodiment explained above, the pair of resonator neck walls 28, 28 that form resonator neck 30 of resonator body member 14 serve as an intermediate pillar that is located at a middle portion of resonator body member 14. with the provision of resonator neck walls 28, 28, rigidity of resonator body member 14 can be enhanced without causing increase in wall thickness of resonator body member 14, namely, increase in weight of resonator body member 14.

[0037] Further, resonator neck 30 is located above the crest formed by the outer surface of central branch 3, thereby facilitating reduction in the cross section of resonator neck passage 29 in resonator neck 30. This provides advantage, especially, upon setting the resonance frequency to low frequency.

[0038] Resonator neck walls 28, 28 disposed within space 26 between the outer surface of second intake manifold body member 13 and resonator body member 14 are exposed to a uniform pressure from both a side of resonator volume chamber 31 and a side of resonator neck passage 29. On the other hand, peripheral side wall 24 of resonator body member 14 which is connected with the outer surface of intake manifold body 15 is exposed to atmospheric pressure from the outside of resonator 6 and also exposed to a pressure within space 26 which is different from the outside atmospheric pressure, from the inside of resonator 6. Therefore, peripheral side wall 24 of resonator body member 14 undergoes a stress larger than that acts on resonator neck walls 28, 28 due to the differential pressure. That is, the stress that acts on resonator neck walls 28, 28 is smaller than the stress that acts on peripheral side wall 24 of resonator body member 14. Accordingly, the stress that acts on the first connection portion of resonator neck walls 28, 28 which is formed by vibration welding becomes smaller than the stress that acts on the second connecting portion between the outer surface of second intake manifold body member 13 and peripheral side wall 24 of resonator body member 14 which is formed by vibration welding.

[0039] For the above-explained reason, the width of the first connecting portion between fifth projection 35 of rib 33 and grooved portion 34 of rib 32 can be smaller than the width of the second connecting portion between third projection 23 of second intake manifold body member 13 and fourth projection 25 of resonator body member 14. That is, the first connecting portion of respective resonator neck walls 28, 28 which is to be formed by vibration welding can be reduced in size as compared to the second connecting portion. Further, since a pressure or load that is required for holding rib 32 of second intake manifold body member 13 and rib 33 of resonator body member 14 in contact with each other when subjecting rib 32 and rib 33 to vibration welding can be lessened by the shape rigidity of resonator body member 14 and the outer surface of intake manifold body 15, it is not necessary to hold resonator body member 14 and intake manifold body 15 by a welding jig. Further, a welding flange that is required to use the welding jig can be omitted from resonator body member 14 and intake manifold body 15. This serves for reducing the weight of intake manifold body 1 and improving freedom in molding design of intake manifold 1. Further, owing to omission of the welding flange, the volume of resonator volume chamber 31 can be increased and a resonator having a lower frequency can be formed.

[0040] Further, resonator neck 30 and resonator volume chamber 31 of resonator 6 are formed by utilizing the outer surface of intake manifold body 15 in cooperation with resonator body member 14. That is, second intake manifold body member 13 forms the bottom wall and the peripheral side wall of resonator 6 in cooperation with resonator body member 14. This serves for reducing a wall that forms resonator 6 and thereby enhancing reduction in size and weight of intake manifold 1 as a whole.

[0041] Furthermore, in the first embodiment, the wave-shaped outer surface of intake manifold body 15 is covered with resonator body member 14 that has a relatively flat outer surface. Accordingly, the appearance of intake manifold 1 can be improved as well as the appearance of an engine room.

[0042] Referring to FIG. 7, a second embodiment of the intake manifold of the present invention will be explained hereinafter. The second embodiment differs from the first embodiment in that partition walls 42 and 43 are provided within resonator neck 30 of intake manifold 41. Like reference numerals denote like parts and therefore detailed explanations therefor are omitted.

[0043] As shown in FIG. 7, resonator neck 30 includes partition wall 42 that extends from second intake manifold body member 13 as viewed on a lower side in FIG. 7 toward resonator body member 14 as viewed on an upper side in FIG. 7, and partition wall 43 that extends from resonator body member 14 toward second intake manifold body member 13. Partition wall 42 is disposed adjacent to communication hole 27 on a side of the one end of resonator neck passage 29 and extends from the outer surface of second intake manifold body member 13 toward the inside surface of resonator body member 14. Partition wall 42 is inclined toward the other end of resonator neck passage 29. Partition wall 43 is located in a position displaced from partition wall 42 toward the other end of resonator neck passage 29 in the longitudinal direction of resonator neck passage 29. Partition wall 43 extends from the inside surface of resonator body member 14 toward the outer surface of second intake manifold body member 13.

[0044] These partition walls 42 and 43 are arranged to allow resonator neck passage 29 to meander within resonator neck 30 such that resonator neck passage 29 has a length longer than a length of resonator neck 30. In this embodiment, the intake air flow flowing and passing through resonator neck passage 29 within resonator neck 30 meanders as indicated by broken line P in FIG. 7. In other words, partition walls 42 and 43 cooperate with each other to provide a so-called labyrinth structure of resonator neck passage 29.

[0045] In the Helmholtz resonator, it is necessary to downsize the resonator volume chamber in order to stabilize the pressure within the intake manifold at an early stage. It is also necessary to reduce the cross section of the resonator neck in order to avoid deterioration in distribution of intake air in the intake manifold. Therefore, generally, tuning of resonance frequency of the Helmholtz resonator is conducted by increasing the length of the resonator neck, i.e., the length of the resonator neck passage provided within the resonator neck. The increased length of the resonator neck causes a complicated layout and construction of the resonator.

[0046] However, in the second embodiment, the length of resonator neck passage 29 within resonator neck 30 can be increased without changing the length of resonator neck 30. Accordingly, it is possible to design resonator neck 30 depending on resonance frequency without causing a relatively complicated layout and construction of resonator 6 and provide resonator 6 with a compact size. As a result, freedom of design of resonator 6 and intake manifold 41 can be enhanced.

[0047] The number of the partition walls that are provided on second intake manifold body member 13 and resonator body member 14, respectively, are not limited only to that in the second embodiment. Second intake manifold body member 13 and resonator body member 14 may be provided with a plurality of the partition walls, respectively. In such a case, the partition walls should be alternately arranged on the side of second intake manifold body member 13 and on the side of resonator body member 14. The total number of the partition walls may be an even number or an odd number if a meandering flow of intake air is produced within resonator neck passage 29. Further, only one partition wall may be provided on either one of second intake manifold body member 13 and resonator body member 14 within resonator neck 30.

[0048] Further, a length of a predetermined region of resonator neck passage 29 in which an S-shaped meandering flow is produced can be increased to a maximum by controlling a substantial cross section of the predetermined region of resonator neck passage 29 to a constant value, so that a whole length of resonator neck passage 29 within resonator neck 30 can be increased to a maximum. Here, the predetermined region of resonator neck passage 29 is a portion of resonator neck passage 29 which extends from communication hole 27 to clearance A defined between a tip end of partition wall 43 and the outer surface of second intake manifold body member 13. The substantial cross section of the predetermined region is a remainder of an actual cross section of resonator neck passage 29 which is formed by excluding a portion as a so-called dead space where there is generated substantially no flow of fluid such as air when the fluid passes through the predetermined region, from the actual cross section.

[0049] Referring to FIG. 8 and FIG. 9, a third embodiment of the intake manifold of the present invention will be explained hereinafter. The third embodiment differs from the first embodiment in that resonator neck 30 and resonator neck passage 29 are disposed on not central branch 3 but side branch 2. As shown in FIG. 8, in intake manifold 51, resonator neck 30 and resonator neck passage 29 within resonator neck 30 is located on branch 2 and extends along branch 2. Specifically, rib 32 with grooved portion 34 extends from an outer surface of branch half 2B of second intake manifold body member 13 in the longitudinal direction of branch half 2B and extends toward the inside surface of the top wall of resonator body member 14. On the other hand, as shown in FIG. 9, rib 33 with fifth projection 35 extends from the inside surface of the top wall of resonator body member 14. Rib 33 extends toward the outer surface of second intake manifold body member 13 so as to correspond to rib 32. Rib 32 and rib 33 are connected with each other to form resonator neck wall 28 by joining fifth projection 35 of rib 33 with bottom 34a of grooved portion 34 of rib 32 by vibration welding as explained in the first embodiment. Resonator neck 30 includes resonator neck wall 28 and a wall that is formed by third projection 23 of second intake manifold body member 13 and fourth projection 25 of the peripheral side wall 24 of resonator body member 14. Resonator neck passage 29 is formed between resonator neck wall 28 and the wall that is formed by third projection 23 and fourth projection 25. The wall formed by third projection 23 and fourth projection 25 serves as one of the pair of resonator neck walls 28, 28 in intake manifold 1 of the first embodiment. That is, in intake manifold 51 of this embodiment, one of the pair of resonator neck walls 28, 28 in intake manifold 1 of the first embodiment is omitted.

[0050] With the above construction of intake manifold 51 of the third embodiment, the production cost and the weight of intake manifold 51 can be reduced.

[0051] This application is based on prior Japanese Patent Application No. 2007-169867 filed on June 28, 2007, the entire content of which is hereby incorporated by reference.

[0052] Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims.

Claims

1. An intake manifold for an internal combustion engine, the intake manifold comprising:

an intake manifold body (15) including a collector (5) and a plurality of branches (2, 3, 4) which are connected to the collector in parallel to each other and joined with each other through a connecting wall (7, 8) between the adjacent branches, the branches being adapted to distribute intake air to cylinders of the engine; and

a resonator (6) including a resonator body member (14) that is fixed onto an outer surface of the intake manifold body, the resonator body member cooperating with the outer surface of the intake manifold body to define a space (26) inside the resonator (6),

wherein the outer surface of the intake manifold body (15) is formed into a wave shape that includes a crest formed at each of the branches and a valley formed at the connecting wall,

wherein each of the branches (2, 3, 4) defines a branch passage therein and has a thickness larger than that of the connecting wall,

wherein the resonator (6) includes a resonator neck (30) and a resonator volume chamber (31) within the space (26), the resonator volume chamber being communicated with the collector (5) through the resonator neck,

wherein the resonator neck (30) has a resonator neck passage (29) formed between a pair of resonator neck walls (28) which are opposed to each other and connected with the resonator body member (14) and the outer surface of the intake manifold body (15), and the resonator neck is disposed above one of the branches and extends along the one of the branches.

2. The intake manifold as claimed in claim 1, wherein the resonator neck (30) comprises a partition wall (42, 43) that allows the resonator neck passage (29) to meander in the resonator neck such that the resonator neck passage has a length longer than that of the resonator neck.

3. The intake manifold as claimed in claim 1 or 2, wherein the intake manifold body (15) comprises a rib (32) that projects from the outer surface of the intake manifold body toward an inside surface of the resonator body member, the resonator body member (14) comprises a rib (33) that projects from the inside surface of the resonator body member toward the outer surface of the intake manifold body and a peripheral side wall (24) that extends along an outer peripheral edge of the resonator body member toward the outer surface of the intake manifold body, and each of the resonator neck walls (28) includes a first connecting portion at which the rib (32) of the intake manifold body (15) and the rib (33) of the resonator body member (14) are joined with each other, wherein the first connecting portion is smaller in width that extends in a direction crossing the branches than a second connecting portion at which the peripheral side wall (24) of the resonator body member and the outer surface of the intake manifold body are joined with each other.

4. The intake manifold as claimed in one of claims 1 to 3, wherein the resonator (6) is a Helmholtz resonator.

5. The intake manifold as claimed in one of claims 1 to 4, wherein the first connecting portion and the second connecting portion are formed by vibration welding.

6. The intake manifold as claimed in claim 1, wherein the resonator neck passage (29) has one end communicated with an inside space of collector (5) through a communication hole (27) that extends through the intake manifold body member (15), and the other end opened into the resonator volume chamber (31).

7. The intake manifold as claimed in claim 3, wherein the rib (32) of the intake manifold body (15) comprises a grooved portion (34) and the rib (33) of the resonator body member (14) comprises a projection (35) that is engaged with the grooved portion and connected with the grooved portion, the grooved portion (34) and the projection (35) being disposed at the first connecting portion.

8. The intake manifold as claimed in claim 3, wherein the intake manifold body comprises a projection (23) that projects from the outer surface of the intake manifold body and the resonator body member comprises a projection (25) that projects from the peripheral side wall and is connected with the projection (23) of the intake manifold body, the projection (23) of the intake manifold body and the projection (25) of the peripheral side wall (24) of the resonator body member being disposed at the second connecting portion.

9. The intake manifold as claimed in claim 8, wherein the intake manifold body comprises a support wall (13a) for supporting the resonator body member, the support wall extending from the outer surface of the intake manifold body toward the peripheral side wall (24) of the resonator body member, the projection (23) of the intake manifold body projecting from an end of the support wall.

10. The intake manifold as claimed in one of claims 1 to 9, wherein the intake manifold body (15) comprises a first intake manifold body member (12) and a second intake manifold body member (13) which are joined with each other on a joint plane extending along a curved profile of the branches (2, 3, 4).

Drawing