INTAKE MANIFOLD AND OUTBOARD MOTOR

An intake manifold 2 suitable for an engine includes: a surge tank 100, die-molded to temporarily store intake air; and a plurality of branch pipes 211, 212, 213, 311, 312, 313, in communication with the surge tank. The surge tank 100 includes: a boss part 111, having a cylindrical shape; and boss reinforcement ribs 114, extending in a direction toward a center S of the boss part and connected with the boss part, the boss part and the boss reinforcement ribs being integrally formed on an outer wall of the surge tank.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serial No. 2023-061805, filed on Apr. 6, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The invention relates to an intake manifold suitable for an intake system of an engine, such as an outboard motor, and particularly relates to an intake manifold in which a boss part is die-molded on an outer wall of a surge tank and an outboard motor in which the intake manifold is mounted.

Description of Related Art

As a conventional intake manifold of an engine for an outboard motor, an intake manifold with a configuration as following is known: a left intake pipe and a left surge tank, disposed on a left outer side of a cylinder block of a V-type multi-cylinder engine and a right intake pipe and a right surge tank, disposed on a right outer side of the cylinder block of the V-type multi-cylinder engine, so as to surround the periphery of the cylinder block; and a throttle body, interposed between the left surge tank and the right surge tank (see, for example, Patent Document 1, Patent Document 2).

Also, as another intake manifold of an engine for an outboard motor, an intake manifold with a configuration as follows is known: a left intake pipe and a left surge tank, disposed on an outer side of a left cylinder head of a V-type multi-cylinder engine and a right intake pipe and a right surge tank, disposed on an outer side of a right cylinder head, so as to surround cylinder heads on both sides of the V-type multi-cylinder engine; and a throttle body, linked to the left surge tank. The left surge tank and the right surge tank are in connection and communication with each other, and multiple fixing parts formed to protrude from outer edge parts of the left surge tank and the right surge tank are provided (see, for example, Patent Document 3).

Moreover, as another intake manifold of an engine for an outboard motor, an intake manifold with a configuration as follows is known: the intake manifold is disposed in a region sandwiched by cylinder heads on both sides of a V-type multi-cylinder engine and includes: multiple intake pipes; a surge tank, formed on an upstream side of the intake ports; and a throttle body (electronically controlled throttle) connected with the surge tank (see, for example, Patent Document 4).

As described above, in the conventional intake manifolds, no other functional components are installed to the outer wall of the surge tank, so a boss part for installation is not provided.

Assuming that various functional components are to be fastened and fixed to the outer wall of the surge tank, it is necessary to provide dedicated boss parts while securing mechanical strength. Therefore, at the time of die-molding a boss part, together with a reinforcement rib for securing the mechanical strength, on the outer wall of the surge tank, there is a concern that a sink mark (indentation, sink hole) may occur due to local shrinkage during cooling after molding when the contact region between the boss part and the reinforcement rib increases. Such sink mark may deform the hole shape of the boss part and deteriorate the accuracy of the dimension. Therefore, in the case of fixing a nut to the boss part through outserting, the nut cannot be fixed firmly, and the reliability in terms of function may be affected.

PRIOR ART DOCUMENT(S)

Patent Document

The invention provides an intake manifold and an outboard motor including the intake manifold, which, at the time of integrally forming boss parts and reinforcement ribs through die-molding, are able to prevent a sink mark, etc., from occurring and secure mechanical strength, and are particularly able to firmly fix nuts through outsertion.

SUMMARY

An intake manifold according to an aspect of the invention is an intake manifold suitable for an engine and includes: a surge tank, die-molded to temporarily store intake air; and branch pipes, in communication with the surge tank. The surge tank includes: a boss part, having a cylindrical shape; and boss reinforcement ribs, extending in a direction toward a center of the boss part and connected with the boss part, the boss part and the boss reinforcement ribs being integrally formed on an outer wall of the surge tank.

DESCRIPTION OF THE EMBODIMENTS

An intake manifold according to an aspect of the invention is an intake manifold suitable for an engine and includes: a surge tank, die-molded to temporarily store intake air; and branch pipes, in communication with the surge tank. The surge tank includes: a boss part, having a cylindrical shape; and boss reinforcement ribs, extending in a direction toward a center of the boss part and connected with the boss part, the boss part and the boss reinforcement ribs being integrally formed on an outer wall of the surge tank.

In the electric device, it may also be configured that the surge tank includes a nut fixed to the boss part.

In the electric device, it may also be configured that the nut is outserted to the boss part.

In the electric device, it may also be configured that the boss reinforcement ribs are separated in a circumferential direction of the boss part to be disposed radially.

In the electric device, it may also be configured that at least a portion of the outer wall of the surge tank includes a plate-shaped outer wall formed in a plate shape, and the boss part and the boss reinforcement ribs are formed on the plate-shaped outer wall.

In the electric device, it may also be configured that a plate thickness of the boss reinforcement rib is equal to or less than a thickness of the boss part.

In the electric device, it may also be configured that the surge tank includes a lattice-like reinforcement rib formed integrally on the outer wall.

In the electric device, it may also be configured that the surge tank includes a lattice-like reinforcement rib formed integrally on the outer wall, and the boss reinforcement ribs are separated in a circumferential direction of the boss part to be disposed radially, and are connected with the lattice-like reinforcement rib.

In the electric device, it may also be configured that at least a portion of the outer wall of the surge tank includes a plate-shaped outer wall formed in a plate shape, and the boss part, the boss reinforcement ribs, and the lattice-like reinforcement rib are formed on the plate-shaped outer wall.

In the electric device, it may also be configured that the branch pipes include a first branch pipe module and a second branch pipe module each defining at least one branch passage, and the surge tank is formed in a cylindrical shape defining a first opening part and a second opening part on both ends, and includes: a first flange part, connected with the first branch pipe module on a periphery of the first opening part; a second flange part, connected with the second branch pipe module on a periphery of the second opening part; a third flange part, connected with a throttle body on a periphery of the inlet.

In addition, an outboard motor according to another aspect of the invention includes: an engine, having an intake system; a body, to which the engine is fixed; a propeller, rotated by a driving force of the engine; a functional component, having a predetermined function; and an engine cover, covering the engine. The intake system includes the intake manifold according to the above.

In the outboard motor, it may also be that the functional component is disposed in adjacency with the surge tank of the intake manifold, and the functional component is fastened and fixed to the boss part of the surge tank.

In the outboard motor, it may also be that the outer wall on which the boss part of the surge tank is formed extends in a vertical direction in a starting state of the engine.

According to the intake manifold with the above configuration, at the time of integrally die-molding the boss parts and the reinforcement ribs, a sink mark, etc., can be prevented from occurring, the mechanical strength can be secured, and, in particular, the nuts can be firmly fixed through outserting. In addition, by providing the intake manifold with such configuration, various functional components can be fixed to the intake manifold, and the outboard motor with high reliability can be provided.

In the following, the embodiments of the invention will be described with reference to the drawings.

An intake manifold according to the invention is die-molded by using a resin material, and is disposed between a throttle body and a cylinder head of an engine body, the throttle body being located downstream of an intake duct in an intake system of the engine. Here, as an embodiment, the case where the intake manifold is suitable for an engine of an outboard motor is described.

The outboard motor is a motor mounted to the rear part of a ship body to generate a propulsion force. As shown inFIGS.1and2, the outboard motor includes a body1, an engine2fixed to the body1, an engine cover3covering the engine2, a propeller4disposed below the body1, a gasket5used at the time of being installed to the ship body, a functional component P having a predetermined function, a power transmission system disposed in the body1and transmitting power of the engine2to the propeller4, and a fuel tank.

For the ease of description, the upright direction in which the outboard motor is mounted to the vehicle body is set as a vertical direction Z, the width direction of the outboard motor is set as a horizontal direction X, and the front-rear direction generating the propulsion force is set as a horizontal direction Y.

The engine2is a V-type six-cylinder internal combustion engine, and includes an engine body, an intake system, and an exhaust system. The engine body includes a cylinder block, a cylinder head, an oil pump, etc., and the intake system and the exhaust system are installed to the engine body.

The intake system includes an outside air introduction duct D, a throttle body TH, an intake manifold M, and a sensor unit U installed to the intake manifold M. Where necessary, the intake system may also include a resonator, a silencer, etc.

As shown inFIG.1, in a state of being installed to the engine2, the intake manifold is oriented so that three of six branch pipes are arranged in the vertical direction Z together. In a starting state of the outboard motor, i.e., the engine2, a surge tank100of the intake manifold M is disposed so that the outer wall (outer side wall110) of the surge tank100extends in the vertical direction Z.

As shown inFIGS.3to7, the intake manifold M is formed by: the surge tank100, temporarily storing intake air; a first branch pipe module200; and a second branch pipe module300. In addition, in the intake manifold M, nuts N are fixed to boss holes h of multiple boss parts111,121, and collars C are fixed to multiple circular holes122a.

The surge tank100is die-molded by using a resin material and formed in a cylindrical shape having an annular cross-section in a substantially rectangular shape to define a first opening part100aand a second opening part100bat two ends in the horizontal direction X and an internal space IS. In addition, the surge tank100includes an outer side wall110, an inner side wall120, a lower side wall130, an upper low wall140, a first flange part150, a second flange part160, an inlet170, and a third flange part180.

The outer side wall110forms a portion of the outer wall and is a plate-shaped outer wall formed in a plate shape to extend in the vertical direction Z in the starting state of the engine2. As shown inFIGS.8to10, the outer side wall110includes multiple boss parts111(111a,111b,111c,111d,111e,111f,111g,111h), a flange part112, a lattice-like reinforcement rib113, and boss reinforcement ribs114.

As shown inFIGS.11to14, the boss part111protrudes from the wall surface of the outer side wall110and is formed in a cylindrical shape with an axis S as the center. On the inner side of the cylindrical wall with a thickness Wt, a boss hole h into which the nut N is outserted (fit) is defined. The boss hole h is formed as being slightly thinned toward the bottom. At the time when the nut N is outserted in a state of being heated, a portion of the inner wall of the boss hole h slightly melts to fit the profile of the nut N and then hardened.

That is, as shown inFIG.8, the boss parts111a,111bare located at the substantially center of the outer side wall110, and, as shown inFIG.12, the nuts N are fit into the respective boss holes h.

In addition, as shown inFIG.8, the boss parts111c,111dare located at positions offset toward the lower side wall130on a side of the outer side wall110, and the nuts N are fit into the boss holes h of the boss parts111c,111d. The boss part111eis located at a position offset toward the upper side wall140on a side of the outer side wall110, and the nut N is fit into the boss hole h of the boss part111e. The boss part111fis located at a position offset toward the upper side wall140on the other side of the outer side wall110, and the nut N is fit into the boss hole h of the boss part111f. The boss part111gis located at a position offset toward the lower side wall130on the other side of the outer side wall110, and the nut N is fit into the boss hole h of the boss part111g. The boss part111his located at a position offset toward the lower side wall130on the other side of the outer side wall110, and the nut N is fit into the boss hole h of the boss part111h.

Here, the functional component P is fastened and fixed to the boss parts111a,111bby using bolts b1. Also, other functional components, such as a bracket fixing the engine cover3, a component for electronic control, and other components, are fastened and fixed to the boss parts111c,111d,111e,111f,111g,111hby using bolts (not shown).

As shown inFIG.8, the flange part112is located at a position offset toward the upper side wall140and at the substantial center of the outer side wall110. The flange part112includes a circular hole112ain communication with the internal space IS and two boss parts112b,112b. The nuts N are fixed to the two boss parts112b,112b, and the lattice-like reinforcement rib113is connected with the outer circumferential surfaces of the two boss parts112b,112b. The lattice-like reinforcement rib113extends in a direction toward the center of the boss part112bto be connected, and functions as a boss reinforcement rib.

In addition, the sensor unit U is fastened and fixed to the flange part112by using the bolts b2.

The lattice-like reinforcement rib113forms a plate shape protruding vertically from the wall surface of the outer side wall110, and is arranged in a lattice shape. In addition, by increasing the bending stiffness and the torsional stiffness, the lattice-like reinforcement rib113increases the overall surface stiffness, and increases the mechanical strength of the outer side wall110.

The boss reinforcement ribs114mainly increase the stiffness of the boss parts111and form a plate shape protruding vertically from the wall surface of the outer side wall110, and extend in a direction toward the centers (the axis S) of the boss parts111to be connected with the boss parts111. In addition, in the boss reinforcement rib114, a side opposite to the side connected with the boss part111is connected with the lattice-like reinforcement rib113. The boss reinforcement rib114is formed to increase the overall stiffness.

Here, as shown inFIG.11, a plate thickness Bt of the boss reinforcement rib114is formed in a dimension equal to or less than a thickness Wt of the boss part111. In this way, by forming the plate thickness Bt to be equal to or less than the thickness Wt, at the time of cooling after die-molding, a sink mark where the inner wall surface of the boss hole h is recessed can be particularly prevented from being generated.

It is noted that the plate thickness of the lattice-like reinforcement rib113is formed to be the same as the plate thickness of the boss reinforcement rib114.

In addition, as shown inFIG.11, multiple (five herein) boss reinforcement ribs114are connected with the outer circumferential surface of each of the boss parts111a,111b. That is, the five boss reinforcement ribs114extend along lines L orthogonal to the center (the axis S) of the boss part111a,111b, that is, toward the center (the axis S) of the boss part111a,111b, to be connected, and are separated in the circumferential direction of the boss part111a,111bto be disposed radially.

In addition, as shown inFIG.8, four boss reinforcement ribs114are connected with the outer circumferential surface of the boss part111c,111d. Here, like the above, the four boss reinforcement ribs114extend in a direction toward the center of the boss part111c,111dto be connected, and are separated in the circumferential direction of the boss part111c,111dto be disposed radially.

In addition, one of the boss reinforcement ribs114and a portion of the lattice-like reinforcement rib113are connected on the outer circumferential surface of the boss part111e. Here, like the above, the one boss reinforcement rib114extends toward the center of the boss part111eto be connected. Although the lattice-like reinforcement rib113extends in a direction slightly offset from the center of the boss part111eto be connected, the lattice-like reinforcement rib113still functions as a reinforcement rib of the boss part111e. In addition, the lattice-like reinforcement rib113and the boss reinforcement rib114are disposed to be separated from each other in the circumferential direction of the boss part111e.

In addition, a portion of the lattice-like reinforcement rib113extends in a direction toward the substantial center of the boss part111fto be connected to the outer circumferential surface of the boss part111f. Since the boss part111fis located in the vicinity of the upper side wall140, the strength is sufficient even if there is no boss reinforcement rib114, and the lattice-like reinforcement rib113also serves to provide reinforcement.

In addition, like the above, one of the boss reinforcements ribs114extends in a direction toward the center of the boss part111gto be connected to the outer circumferential surface of the boss part111g.
In addition, like the above, three of the boss reinforcement ribs114extend in a direction toward the center of the boss part111hto be connected to the outer circumferential surface of the boss part111h.

The inner side wall120forms a portion of the outer wall, and is formed to extend in the vertical direction Z and project in the horizontal direction X in the starting state of the engine2. As shown inFIGS.4,9, and10, the inner side wall120includes multiple boss parts121(121a,121b, and121b), a flange part122, a lattice-shape reinforcement rib123, boss reinforcement ribs124, and reinforcement ribs125.

The boss parts121aand121bare located at positions offset toward the lower side wall130in the projection part of the inner side wall120, and the nuts N are fit into the boss holes h of the boss parts121aand121b.

The flange part122is formed at a projection part of the inner side wall120, and includes four circular holes122. Collars C are fixed to the circular holes122a. In addition, the collars C are fixed through insertion or outsertion.

As shown inFIG.4, the lattice-like reinforcement rib123forms a plate shape protruding vertically from the wall surface of inner side wall120, and is disposed in a lattice shape. In addition, by increasing the bending stiffness and the torsional stiffness, the lattice-like reinforcement rib123increases the overall surface stiffness, and the mechanical strength of the inner side wall120is increased.

As shown inFIG.10, the boss reinforcement ribs124increase the stiffness of the boss part121a,121b, form a plate shape protruding vertically from the wall surface of the projection part of the inner side wall120, and are connected with the boss part121a,121b.

That is, the four boss reinforcement ribs124are respectively connected to the outer circumferential surface of the boss part121a,121b. Here, like the above, the four boss reinforcement ribs124extend in a direction toward the center of the boss part121a,121bto be connected, and are separated in the circumferential direction of the boss part121a,121bto be disposed radially. It is noted that a functional component, such as a stay supporting the intake manifold M, or other functional components are fastened and fixed to the boss parts121a,121bby using bolts (not shown).

As shown inFIG.10, the reinforcement rib125increases the stiffness of the projection part of the inner side wall120, and is formed in a plate shape that projects vertically from the wall surface.

The lower side wall130forms a portion of the outer wall, is disposed toward the lower side of the vertical direction Z in the starting state of the engine2, is formed in a substantially plate shape expanding in the horizontal direction, and includes, in the central region thereof, a curved wall131curved to be convex toward the outer side. The curved wall131may be formed at a position opposite to the inlet170in the vertical direction Z.

The upper side wall140forms a portion of the outer wall, is disposed toward the upper side of the vertical direction Z in the starting state of the engine2, and, defines, in the central region thereof, the inlet170and the third flange part180around the inlet170.

As shown inFIGS.7and9, the first flange part150is formed to be annular around the first opening part100aon a side in the horizontal direction X, and includes a bonding surface151bonded to the first branch pipe module200, five fitting holes152, and the nuts N fit into the fitting holes152. The nuts N are fixed to the fitting holes152through outsertion.

As shown inFIGS.7and10, the second flange part160is formed to be annular around the second opening part100bon the other side in the horizontal direction X, and includes a bonding surface161bonded to the second branch pipe module300, five fitting holes162, and the nuts N fit into the fitting holes162. The nuts N are fixed to the fitting holes162through outsertion.

The inlet170is a region where the intake air passing through the throttle body TH flows toward the internal space IS, and is formed as a circular opening toward the vertical direction Z in the starting state of the engine2.

As shown inFIGS.7,9, and10, the third flange part180is formed to be annular around the inlet170, and includes a bonding surface181bonded to the throttle body TH, four fitting holes182, and the nuts N fit into the fitting holes182. The nuts N are fixed to the fitting holes182through outsertion. The bonding surface181includes an annular seal groove181ato be fit with an annular seal member Sr.

The first branch pipe module200is formed by integrating two molded bodies die-molded by using a resin material. As shown inFIGS.3to7, the first branch pipe module200includes three branch pipes211,212,213, a collection duct part220, a flange part230, and a flange part240.

The three branch pipes211,212,213are formed to each define branch passages211a,212a,213athrough which the intake air flows and in communication with three intake ports of a bank (cylinder row) on a side of the engine2.

The collection duct part220has multiple reinforcement ribs221on the outer wall thereof, is formed upstream of the three branch pipes211,212,213to define an internal space, and is in communication with the internal space IS of the surge tank100. That is, the collection duct220functions as a space for temporarily storing intake air, like the surge tank100.

The flange part230serves to connect the three branch pipes211,212,213with each other and is bonded to the cylinder head of the engine2, and includes a bonding surface231and four circular holes232through which fastening bolts (not shown) pass through.

The flange part240is bonded to the first flange part150of the surge bank100, and includes a bonding surface including an annular seal groove to be fit with an annular seal member, and five circular holes242through which fastening bolts b3pass through.

The second branch pipe module300is formed by integrating two molded bodies die-molded by using a resin material. As shown inFIGS.3to5andFIG.7, the second branch pipe module300includes three branch pipes311,312,313, a collection duct part320, a flange part330, and a flange part340.

The three branch pipes311,312,313are formed to each define branch passages311a,312a,313athrough which the intake air flows and be in communication with three intake ports of a bank (cylinder row) on the other side of the engine2.

The collection duct part320has multiple reinforcement ribs321on the outer wall thereof, is formed upstream of the three branch pipes311,312,313to define an internal space, and is in communication with the internal space IS of the surge tank100. That is, the collection duct320functions as a space for temporarily storing intake air, like the surge tank100.

The flange part330serves to connect the three branch pipes311,312,313with each other and is bonded to the cylinder head of the engine2, and includes a bonding surface331and four circular holes332through which fastening bolts (not shown) pass through.

The flange part340is bonded to the second flange part160of the surge bank100, and includes a bonding surface including an annular seal groove to be fit with an annular seal member and five circular holes342through which fastening bolts b4pass through.

Then, a manufacturing and assembling process of the intake manifold M with the configuration is described.

Beforehand, the surge tank100, the first branch pipe module200, and the second branch pipe module300are respectively formed through die-molding by using a resin material.
At the time of assembling, the surge tank100, the first branch pipe module200, the second branch pipe module300, the nuts N, the bolts b1, b2, b3, b4, and the annular seal member (not shown) are prepared.

Firstly, the nuts N are assembled to the boss parts111(111a,111b,111c,111d,111e,111f,111g,111h) of the surge tank100through outsertion.

Specifically, as an example, a process of assembling the nut N to the boss part lila is as shown inFIGS.13to15.
In a state of being heated to a predetermined temperature, the nut N is disposed to be opposite to the boss hole h of the boss part111a, as shown inFIGS.13and14.
Then, the nut N is pressed and fit into the boss hole h, as shown inFIG.15. At this time, the inner wall part of the boss hole h partially melts to fit the profile of the nut N, and after being cooled down, the nut N is fixed to the boss hole h.

In the outsertion process, the boss part111ais molded to a predetermined dimension without a sink mark, so the nut N can be firmly fixed to the boss part111a.

The process of fitting the nut N as described above is performed on all of the boss parts111b,111ctoh,121a,121b. The same process of fitting the nut N is also performed on the boss part122band the fitting holes152,162,182.
In addition, the collars C are assembled to the circular hole122a. The collars C are inserted together at the time of die-molding. Nevertheless, the collars C may also be outserted after die-molding.

Then, the first branch pipe module200and the second branch pipe module300are assembled to the surge tank100.

Firstly, in the state in which the annular seal member is fit into the annular seal groove of the bonding surface241, the flange part240of the first branch pipe module200is bonded to the bonding surface151of the first flange part150of the surge tank100, and the bolts b3are inserted into the circular holes242and screwed into and tightened with the nuts N fit into the fitting holes152.

Then, in the state in which the annular seal member is fit into the annular seal groove of the bonding surface341, the flange part340of the second branch pipe module300is bonded to the bonding surface161of the second flange part160of the surge tank100, the bolts b4are inserted into the circular holes342and screwed into and tightened with the nuts N fit into the fitting holes162.

Accordingly, the assembling process of the intake manifold M is completed. It is noted that the order of assembling the first branch pipe module200and the second branch pipe module300merely serves as an example, and the components may also be assembled in a reversed order.

In addition, in the case where the intake manifold M is assembled as a portion of the intake air system of the engine2, then, the throttle body TH is assembled to the third flange part180of the surge tank100. That is, in the state in which the annular seal member Sr is fit into the annular seal groove181aof the bonding surface180of the third flange part180, the throttle body Th is bonded to the bonding surface181, and the bolts b5are screwed and tightened to the nuts N fit into the fitting holes182.

In addition, the sensor unit U is bonded to the flange part122, and the bolts b2are screwed and tightened to the nuts N of the boss parts112b.

In addition, the functional component P is disposed to be opposite to the boss parts111a,111bformed on the outer side wall110of the surge tank100, and the bolts b1are screwed and tightened to the nuts N fixed to the boss holes h.
Moreover, various functional components may be assembled to other boss parts111(111c,111d,111e,111f,111g,111h,121a,121b) when necessary.

As described above, the intake manifold M according to an embodiment is an intake manifold suitable for the engine2, and includes: the surge tank100, die-molded to temporarily store intake air; and multiple branch pipes211,212,213,311,312,313, in communication with the surge tank100. The surge tank100includes: the boss part111, having a cylindrical shape, and integrally formed on the outer wall (the outer side wall110) of the surge tank100; and boss reinforcement ribs114, extending in a direction toward the center of the boss part111and connected with the boss part111.

Accordingly, the contact region between the boss reinforcement rib114and the boss part111can become narrow, and the boss part111can be reinforced by the boss reinforcement rib114. Therefore, at the time of integrally forming the boss part111and the boss reinforcement rib114through die-molding, a sink mark, etc., can be prevented from occurring, and mechanical strength can be secured.

In addition, the surge tank100can have a configuration including the nuts N fixed to the boss parts111.

Accordingly, after the surge tank100is formed through die-molding, the deformation of the boss part111is suppressed or prevented. Therefore, the boss hole h can be formed in a desired size, and the nut N can be fixed firmly.
In particular, through outsertion of the nuts N to the boss part111, the nut N can be fixed through a simple process.

In addition, the boss reinforcement ribs114are formed to be separated in the circumferential direction of the boss part111to be disposed radially.

Accordingly, by increasing the intervals between the boss reinforcement ribs114, the contact region with the boss part111can reduced, and the boss part111can be reliably reinforced.

In addition, at least a portion of the outer wall of the surge tank100includes a plate-shaped outer wall (outer side wall110) formed in a plate shape, and the boss part111and the boss reinforcement rib114are formed on the plate-shaped outer wall (outer side wall110). Accordingly, by integrally forming the boss reinforcement rib114connected on the periphery of the boss part111, despite the outer wall is plate-shaped, the decrease in surface stiffness can be compensated by increasing the stiffness of the plate-shaped outer wall (outer side wall110).

In addition, the plate thickness Bt of the boss reinforcement rib114is formed to be equal or less than the thickness Wt of the boss part111.

Accordingly, at the time when the surge tank100is cooled off after die-molding, a sink mark where on the inner wall surface of the boss hole h of the boss part111is recessed can particularly be prevented from being generated.

In addition, the surge tank100is formed to include the lattice-like reinforcement rib113integrally formed on the outer wall (outer side wall110).

Accordingly, the surface stiffness can be increased by increasing the bending stiffness and the torsional stiffness of the outer wall (outer side wall110), and the overall mechanical strength of the surge tank100can be increased.

In addition, the surge tank100includes the integrally formed lattice-like reinforcement rib113on the outer wall (outer side wall110), and the boss reinforcement ribs114are separated in the circumferential direction of the boss part111and disposed radially, and are formed to be connected with the lattice-like reinforcement rib113.

Accordingly, the surface stiffness of the outer wall (outer side wall110) can be increased, the stiffness around the boss part111can be increased, and the overall mechanical strength can be increased.

In particular, at least a portion of the outer wall of the surge tank100includes a plate-shaped outer wall (outer side wall110) formed in a plate shape, and the boss part111, the boss reinforcement rib114, and the lattice-like reinforcement rib113are formed on the plate-shaped outer wall (outer side wall110). Accordingly, despite the outer wall is plate-shaped, the decrease in surface stiffness can be compensated for, and the overall mechanical strength can be increased.

In addition, the branch pipes211,212,213,311,312,313include the first branch pipe module200and the second branch pipe module300each defining at least one branch passage211a,212a,213a,311a,312a,313a. The surge tank100is formed in a cylindrical shape defining the first opening part100aand the second opening part100bon both ends, and includes: the first flange part150connected with the first branch pipe module200on the periphery of the first opening part100a; the second flange part160connected with the second branch pipe module300on the periphery of the second opening part100b; the inlet170through which the intake air flows in; and the third flange part180, connected with the throttle body TH on the periphery of the inlet170.

Accordingly, by forming the intake manifold M in three parts, molding becomes easy and, in particular, the die-molding of the surge bank100in which the boss parts111and the boss reinforcements rib114are integrally formed becomes easy.

In addition, the outboard motor with the above configuration includes: the engine2having the intake system; the body1to which the engine2is fixed; the propeller4rotated by the driving force of the engine2; the functional component P having a predetermined function; and the engine cover3covering the engine2. The intake system includes the intake manifold M according to the above.

In this way, by providing the intake manifold M having high mechanical strength in the intake system, a reliable outboard motor can be obtained.

In addition, the functional component P is disposed in adjacency with the surge tank100of the intake manifold M, and the functional component P is fastened and fixed to the boss parts111a,111bof the surge tank100.

In this way, the surge bank100of the intake manifold M can be used to fix the functional component P, and, compared with a case where a dedicated fixing member is provided separately, the number of components of the outboard motor can be reduced.

In addition, the outer wall (outer side wall110) where the boss parts111of the surge tank100are formed are formed to be disposed to extend in the vertical direction Z in the starting state of the engine2.

In this way, in the case where the functional component P is fixed to the boss parts111, even if the weight acts downward in the vertical direction Z on the functional component P or a bending stress or a shear stress is generated in the boss parts111due to vibration of the engine2, as the mechanical strength is increased by the boss reinforcement ribs114, the boss parts111can be prevented from being broken, and the initial function can be maintained.

According to the above, with the intake manifold M having the above configuration, at the time of integrally die-molding the boss parts111and the reinforcement ribs114, a sink mark, etc., can be prevented from occurring, the mechanical strength can be secured, and, in particular, the nuts N can be firmly fixed through outserting. In addition, according to the outboard motor including the intake manifold having the above configuration, various functional components P can be fixed to the intake manifold M and the reliability can be increased, while the dedicated component for fixing can be omitted.

Although the above embodiment illustrates a configuration that the nuts N are outserted to the boss parts111, the invention is not limited thereto. Other functional components may also be fit to the boss holes of the boss parts, and, particularly, in the case where an aluminum material is used, in place of resin material, for die-molding, female screws may also be formed through post-processing on the boss holes of the boss parts.

Although the above embodiment illustrates the case where the nuts N are fixed to the boss parts111through outsertion, the invention is not limited thereto. The nuts N may also be fixed through insertion.

In the embodiment, as the intake manifold, the intake manifold M formed by the surge tank100, the first branch pipe module200, and the second branch pipe module300is shown. However, the invention is not limited thereto. Intake manifolds of other separate configurations, or, if die-molding is possible, an intake manifold that is integrally molded as a whole may also be adopted.

As described above, according to the intake manifold of the invention, at the time of integrally die-molding the boss parts and reinforcement ribs, a sink mark, etc., can be prevented from occurring, and mechanical strength can be secured. In particular, since the nuts can be firmly fixed through outsertion, in addition to being applicable to the engine of the outboard motor, the intake manifold according to the invention is also applicable as the intake manifold of other engines.