JP2014100982A - Intake structure of outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake structure of an outboard engine capable of achieving excellent combustion efficiency by improving intake efficiency and packing efficiency.SOLUTION: In the intake structure of an outboard engine in which the air taken from an air intake port 42 provided on a swollen part 41 formed protrusively on the upper surface of an engine cover 4A for covering an upper part of the outboard engine is fed to a throttle body and sucked, the air intake port 42 includes an openable/closable louver 43 opened forward, and a space for allowing communication between the air intake port 42 and the throttle body is provided separately from an engine room.

Description

  The present invention relates to an intake structure that supplies combustion air to an engine mounted on an outboard motor.

  In an outboard motor including an internal combustion engine housed in an engine room formed by an engine cover, a configuration is known in which an opening for taking in combustion air is provided behind the engine cover (for example, Patent Document 1). , 2). In such an outboard motor, the air taken into the engine cover is sent into the engine room. And after flowing through the space near the engine housed in the engine room, it is sent to the combustion chamber.

JP 2007-8416 A JP 2008-88881 A

  However, according to the above configuration, the opening is provided behind the engine cover, that is, in a direction opposite to the forward direction of the outboard motor. Will be adopted. In such intake method, intake resistance is generated and intake efficiency is deteriorated, resulting in a problem that engine output is reduced.

  Further, according to the above configuration, the air taken into the engine cover flows in the vicinity of the engine, and after being warmed, is sucked into the throttle body and sent to the combustion chamber. For this reason, charging efficiency will deteriorate, and there exists a problem that combustion efficiency and fuel consumption deteriorate.

  The present invention has been made in view of this point, and an object of the present invention is to provide an outboard motor intake structure that achieves excellent combustion efficiency by improving intake efficiency and charging efficiency.

  An intake structure for an outboard motor according to the present invention is an intake structure for an outboard motor that feeds air taken in from an air intake to a throttle body for intake, and the air intake opens forward. The louver includes an openable / closable louver, and a space communicating the air intake port and the throttle body is provided separately from an engine room.

  According to this configuration, since the air intake port has a louver that can be opened and closed while opening forward, it is possible to allow the traveling wind to directly flow into the air intake port by traveling the hull. Intake efficiency is greatly improved compared to a configuration in which an air intake is provided behind the engine cover. In addition, by controlling the opening / closing function of the louver, it is possible to prevent a large amount of water from entering from the air intake port, so that it is possible to obtain a high water entry preventing effect. Further, since the space that communicates the air intake port and the throttle body is provided separately from the engine room, the combustion air passes through the air flow path in the space isolated from the engine room, and then the throttle body. Supplied to the engine. That is, since the combustion air is not heated by being exposed to a high-temperature engine on the way to the engine, intake charging efficiency is improved. Accordingly, it is possible to improve the intake efficiency and the charging efficiency while preventing water intrusion and the like, and to realize an outboard motor intake structure having an excellent combustion efficiency.

  In the above-described outboard motor intake structure, a bulging portion is formed on the upper surface of the engine cover that covers the upper portion of the outboard motor, and the inner space formed by the bulging portion is formed inside the engine cover. It is preferable to provide a chamber and convert the dynamic pressure of the air taken from the air intake into a static pressure in the expansion chamber. In this case, in the expansion chamber, the dynamic pressure of the air taken in from the air intake port can be supplied to the throttle body in a state converted to a static pressure, so that the combustion air is burned while utilizing the ram pressure generated during traveling. The chamber can be supplied.

  In the above-described outboard motor intake structure, a separator for gas-liquid separation is provided in the middle of the air flow path in the space, and the separator includes a flat plate-like portion covering the intake port of the throttle body and the separator. It is preferable to include a skirt portion that extends downward from the front end portion of the flat plate-like portion. In this case, since a separator for gas-liquid separation is provided in the middle of the air flow path of the space that communicates the air intake port and the throttle body, moisture or the like that has entered from the air intake port collides with the separator. The gas and liquid are separated and fall to the bottom of the expansion chamber, so that moisture and the like can be prevented from entering the intake port of the throttle body.

  Furthermore, in the above-described outboard motor intake structure, it is preferable that the throttle body is disposed rearwardly of the air intake port. In this case, since the throttle body is spaced apart from the air intake port, the intake body can be circulated in accordance with the separation distance by ensuring a long distance between the air intake port and the throttle body. Since the path becomes long, it is possible to easily separate moisture contained in the intake air, and effectively prevent water from entering the throttle body.

  Furthermore, in the intake structure of the outboard motor, a drainage passage that communicates the inside and the outside of the space and discharges the water inside the space to the outside is provided. A backflow prevention mechanism for preventing water from flowing in from the outside to the inside is provided, and the backflow prevention mechanism is preferably either or both of an S-shaped tube and a one-way valve. In this case, since the backflow prevention mechanism is provided in the drainage passage, the water once drained through the drainage passage can be prevented from backflowing and returning to the inside of the expansion chamber.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the intake structure of the outboard motor which implement | achieves the outstanding combustion efficiency by improving intake efficiency and filling efficiency.

It is a left side view showing the appearance of the outboard motor according to the present embodiment. It is a left view which shows the schematic block diagram of the said outboard motor. It is a cross-sectional schematic diagram which shows the engine cover periphery of the outboard motor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a left side view showing an appearance of an outboard motor 1 having an intake structure according to an embodiment of the present invention. FIG. 2 is a left side view illustrating a schematic configuration diagram of the outboard motor 1 having the intake structure according to the embodiment of the present invention. In the following, for convenience of explanation, the front of the outboard motor 1 is indicated by an arrow Fr, and the rear of the outboard motor 1 is indicated by an arrow Rr.

  The outboard motor 1 includes an outboard motor main body 2 that generates driving force by transmitting a driving force from the mounted engine 21 (see FIG. 2) to the propeller 22, and the outboard motor main body 2 is connected to the stern portion of the hull ( And a mounting bracket device 3 for mounting to the (transom) 100.

  As shown in FIG. 2, the outboard motor main body 2 has an engine 21 mounted on the upper portion, and can drive the lower propeller 22. As the engine 21, for example, a multi-cylinder engine such as a V-type 6-cylinder engine can be adopted. Note that the detailed description of the internal structure of the engine 21 is omitted here.

  The entire outboard motor main body 2 is covered with an exterior cover. In particular, the engine 21 is covered with an engine cover 4 that is an exterior. The engine cover 4 is configured by integrally combining an engine cover 4A that forms an upper cover or a top cover that covers the upper part of the engine cover 4 and an engine cover 4B that forms a lower cover or a lower cover. By such an engine cover 4, the inside of the engine room in which the engine 21 is accommodated has a sealed structure and is shielded from the outside air.

  An under plate 5 described later is disposed between the engine cover 4A and the engine cover 4B. The engine 21 is disposed in an engine room formed by the under plate 5 and the engine cover 4B. The space formed by the engine cover 4 </ b> A is substantially isolated from the engine room by the under plate 5.

  The engine 21 is mounted vertically so that the crankshaft 23 faces the vertical direction. A drive shaft 24 is connected to the crankshaft 23. The propeller 22 is attached to one end of the propeller shaft 25. With this configuration, the rotational force of the engine 21 is transmitted to the propeller shaft 25 via the drive shaft 24, and the propeller 22 rotates forward or reverse. As a result, the hull obtains a forward (reverse) side or reverse (reverse) side propulsive force.

  The engine 21 is connected to a throttle body (not shown) that controls the amount of intake air to the engine 21. The upper end surface of the throttle body, that is, the upper end portion of the intake passage is connected to a throttle body connecting pipe 7 that opens upward on the lower side of the engine cover 4A. The throttle body connecting pipe 7 is disposed near the rear end of the engine room.

  The mounting bracket device 3 includes a clamp bracket 31 and a swivel bracket 32. The clamp bracket 31 is detachably provided on the stern portion 100 of the hull. The swivel bracket 32 supports the outboard motor main body 2 so as to be rotatable in the horizontal direction, and supports the outboard motor main body 2 via the swivel shaft 33 so as to be rotatable in the vertical direction with respect to the clamp bracket 31. With this configuration, the outboard motor main body 2 is attached in a state in which it can turn in the horizontal direction (steering direction) and the vertical direction (in the tilt direction) with respect to the hull.

  FIG. 3 is a schematic cross-sectional view showing the periphery of the engine cover 4A. The engine cover 4A is configured by molding, for example, carbon fiber reinforced plastic (CFRP). The engine cover 4A generally has a shape that opens downward. The engine cover 4A has an elliptical shape that is generally long in the front-rear direction when viewed from above, and is curved so as to be convex upward as a whole.

  The engine cover 4 </ b> A has a bulging portion 41 that protrudes upward on the front side thereof, an air inlet 42 provided at the front end of the bulging portion 41, and a louver that adds an opening / closing function to the air inlet 42. 43.

  The bulging portion 41 is formed in an inclined surface shape in which the front end portion is inclined slightly forward from the vertical in a side view, and while maintaining a curved shape convex upward from the front end portion, It is gently inclined. The air inlet 42 is provided to open forward at the front end of the bulging portion 41. In addition, on the front side of the lower edge of the air intake 42, the upper surface of the engine cover 4A is a gently inclined surface with a front lowering.

  The louver 43 is attached to the air intake 42 and is for switching the open / closed state of the air intake 42. By changing the direction of the louver 43, the intake direction can be adjusted, and switching between opening and closing is possible. Such a louver 43 is provided in order to prevent foreign matter from entering from the air intake 42.

  3A, the louver 43 has a plurality of slit-like flow paths parallel to each other in the vertical direction of the outboard motor 1 with the longitudinal direction of the outboard motor 1 being the longitudinal direction. In addition, the louver 43 has a plurality of parallel slit-shaped channels that are inclined with respect to the front-rear direction of the outboard motor 1 in the closed position shown in FIG. 3B. The louver 43 is switched from the open position shown in FIG. 3A to the closed position shown in FIG. 3B by rotational movement so that the rear side is obliquely upward by an automatic or manual operation.

  As described above, the engine cover 4A and the bulging portion 41 on the upper surface thereof are generally formed as a curved surface or a curve that is convex upward, and have a rounded shape as a whole. The inside of the bulging portion 41 has a hollow structure that substantially corresponds to the outer shape, and the inside and outside of the bulging portion 41 communicate with each other through the air intake 42.

Next, the internal configuration of the engine cover 4A will be described.
An inner space 41A is formed inside the engine cover 4A by a bulging portion 41 having a convex shape upward. An under plate 5 is disposed between the engine cover 4A and the engine cover 4B. The under plate 5 is disposed so as to overlap the engine cover 4A so as to close the opening on the lower side of the engine cover 4A. With this configuration, the expansion chamber 6 including the inner space 41 </ b> A is formed between the engine cover 4 </ b> A and the under plate 5. By providing the under plate 5, the expansion chamber 6 is substantially isolated from the engine room formed in the engine cover 4B. The expansion chamber 6 has a function of converting the dynamic pressure of the air taken in from the air intake 42 into a static pressure. In the expansion chamber 6, the dynamic pressure of the air taken in from the air intake 42 can be supplied to the throttle body in a state where it is converted into a static pressure, so that combustion air is supplied to the combustion chamber while utilizing the ram pressure generated during traveling. It becomes possible to do.

  The under plate 5 is formed by molding, for example, carbon fiber reinforced plastic (CFRP). Similarly to the engine cover 4A, the under plate 5 has an elliptical shape that is generally long in the front-rear direction when viewed from above, and is provided with a bottom 51 that is bent so as to protrude downward. The bottom 51 is formed so as to gradually become deeper from the rear to the front. The bottom 51 is provided with a drain hole 52 and a guide pedestal 53 for airflow guide, and a separator 54 is disposed above the guide pedestal 53.

  The drain hole 52 is provided at the front end portion of the bottom portion 51, and the upper end of the drain pipe 8 is connected thereto. The water accumulated in the expansion chamber 6 is discharged to the outside through the drainage passage constituted by the drainage hole 52 and the drainage pipe 8. Since the drain hole 52 is provided at the lowest position in the front end portion of the bottom portion 51, that is, the bottom portion 51, the drain hole 52 can be drained from the drain hole 52 including the case where the outboard motor 1 is tilted.

  In the middle of the drainage passage constituted by the drainage pipe 8, a backflow prevention mechanism for preventing the backflow of drainage is provided. As the backflow prevention mechanism, a configuration in which the drain pipe 8 is an S-shaped pipe having a bent portion 8a curved or bent in an S shape can be applied. Since the bent portion 8a of the drainage pipe 8 hinders the flow of water, it is possible to prevent or suppress the backflow of water through the drainage pipe 8. Further, since the backflowed water is attenuated in the bent portion 8a, the water can be prevented from flowing back into the expansion chamber 6. Furthermore, when the air containing water flows backward, the water contained in the air collides with the inner wall surface of the bent portion 8a to separate the air and the water. For this reason, it is possible to prevent water from flowing back into the expansion chamber 6.

  Further, as the backflow prevention mechanism, a one-way valve 9 that allows the drainage to flow only in the drainage direction indicated by the arrow W as shown in FIG. In addition, as a backflow prevention mechanism, the structure provided only with one of the bending part 8a and the one-way valve 9 may be sufficient, and the structure provided with both may be sufficient.

  The guide pedestal 53 is provided so as to protrude upward from the bottom 51 so as to surround the upper end opening 7 a of the throttle body connecting pipe 7 disposed near the rear end of the under plate 5. The guide pedestal 53 has, for example, a substantially truncated cone shape, and an opening 53a is provided on the top thereof. The opening 53 a is provided so as to correspond to the upper end opening 7 a of the throttle body connecting pipe 7. Further, the outer peripheral surface of the guide pedestal 53 constitutes an inclined surface 53b that is inclined toward the opening 53a.

  The separator 54 is provided in order to prevent moisture and the like from entering the throttle body connecting pipe 7 that opens upward. The separator 54 includes a flat plate portion 54a that covers the opening 7a of the throttle body connecting pipe 7, and a skirt portion 54b that extends downward and is formed by bending along the front edge of the flat plate portion 54a. , And is configured. The side edge and the rear edge of the flat plate portion 54 a are connected to the inner wall surface of the under plate 5. The separator 54 is configured such that the rear end of the bulging portion 41 is located between the front end and the rear end.

  The skirt portion 54 b is configured such that a lower end portion thereof is located below the opening portion 53 a of the guide pedestal 53 and above the bottom portion 51 of the under plate 5. The skirt portion 54 b is configured such that the lower end portion thereof is positioned below the lower end portion of the air intake port 42.

  Next, the flow of combustion intake air supplied to the engine 21 in the outboard motor 1 configured as described above will be described.

  As the hull carrying the outboard motor 1 travels, outside air flows from the air intake 42 provided in the bulging portion 41 of the engine cover 4A. The air taken in from the air inlet 42 enters the expansion chamber 6 through the inner space 41A inside the bulging portion 41 as shown by a broken line arrow A in FIG. 3A, and enters the lower side of the skirt portion 54b of the separator 54. Then, the air is supplied from the opening 53a of the guide base 53 to the throttle body through the upper end opening 7a of the throttle body connecting pipe 7.

  At this time, as shown by an arrow W in FIG. 3A, the water or the like contained in the spray or intake air is separated into gas and liquid by colliding with the separator 54 and falls to the bottom 51 of the under plate 5. Since the bottom 51 of the under plate 5 is a front-lowering inclined surface, water flows forward (that is, toward the side opposite to the throttle body). Then, the water that has flowed down accumulates in the front portion of the bottom 51 and flows down from the drain hole 52 to the drain pipe 8. Thereafter, the water is drained to the outside of the outboard motor 1.

  That is, even if moisture or the like enters the expansion chamber 6 from the air intake 42, the moisture or the like is prevented from flowing into the intake 10 of the throttle body from the upper end opening 7a of the throttle body connecting pipe 7. In particular, since the opening 53a of the guide base 53 is provided near the rear portion of the expansion chamber 6, the water that has entered the expansion chamber 6 flows down in a direction away from the intake port 10 of the throttle body. For this reason, it is possible to effectively prevent the water that has entered the expansion chamber 6 from flowing toward the intake port 10 of the throttle body and staying in the vicinity of the intake port 10 of the throttle body.

  Since the drain pipe 8 is provided with a backflow prevention mechanism, the water once drained through the drainage passage can be prevented from flowing back into the expansion chamber 6. Further, water does not enter the expansion chamber 6 from the outside of the outboard motor 1 through the drainage passage.

  Even when the outboard motor 1 is tilted, the drain hole 52 is always provided at the lowest part of the bottom 51. For this reason, regardless of the attitude of the outboard motor 1, the water that has entered the expansion chamber 6 can be quickly discharged.

  Further, the outboard motor 1 includes a louver 43 at the air intake 42. By setting the louver 43 to the closed position, as shown by an arrow W in FIG. 3B, the water or the like contained in the spray or intake air is separated into gas and liquid by colliding with the louver 43 and falls onto the engine cover 4A. . In addition, since the upper surface of the engine cover 4A is a front-lowering inclined surface on the front side of the lower edge of the air intake port 42, it is possible to prevent the dropped water droplets or the like from rising along the upper surface of the engine cover 4A. Thereby, it is possible to effectively prevent moisture and the like from entering the air intake 42.

  The open / close function of the louver 43 is, for example, that the ram pressure is used to the maximum when the hull is traveling at a high speed, and the closed position is used when the hull is traveling at a low speed. It can be controlled manually or automatically to prevent intrusion.

  In the outboard motor 1 according to the embodiment of the present invention, the air intake 42 is provided in the engine cover 4A that covers the upper portion of the outboard motor 1, and the air intake 42 opens forward. With this configuration, as the hull travels, it is possible to allow the traveling wind to flow directly into the air intake 42, so that the intake efficiency is significantly higher than the configuration in which the air intake is provided behind the engine cover. Thus, the combustion efficiency of the engine 21 can be improved.

  In addition, the intake structure in the outboard motor 1 supplies the air taken in from the air intake 42 to the intake 10 of the throttle body in the space inside the engine cover 4A, that is, the expansion chamber 6, for intake. In the intake structure, the expansion chamber 6, which is a space communicating the air intake 42 and the throttle body, is isolated from the engine room by the under plate 5. Therefore, the intake structure is disposed above the engine 21 in a state of being isolated from the engine 21 in the engine room.

  The air taken in from the air intake 42 enters the expansion chamber 6 and enters the lower side of the skirt portion 54b of the separator 54 as shown by a dashed arrow A in FIG. The air is supplied from the upper end opening 7a of the throttle body connecting pipe 7 to the intake 10 of the throttle body. In this way, the combustion air is supplied from the throttle body to the engine 21 through the air flow path in the space isolated from the engine room. That is, since the combustion air is not heated by being exposed to the high-temperature engine 21 on the way to the engine 21, the intake air charging efficiency is increased, and the combustion efficiency of the engine 21 can be improved.

  Further, even when a large amount of water has entered from the air intake 42, the entered water falls to the flat plate-like portion 54 a of the separator 54, and further falls to the bottom 51 of the underplate 5 through the skirt 54 b. . Therefore, the water that has entered the expansion chamber 6 does not directly enter the intake port 10 of the throttle body via the upper end opening 7 a of the throttle body connecting pipe 7. That is, since the flat plate portion 54a of the separator 54 serves as a ceiling wall of the throttle body connecting pipe 7 and the intake 10 of the throttle body and functions as a shielding plate against the intruded water, a high water infiltration preventing effect is obtained. . Since the side edge and the rear edge of the flat plate portion 54a are connected to the inner wall surface of the underplate 5, water does not enter through the side edge and the rear edge of the flat plate portion 54a.

  Further, by controlling the opening / closing function of the louver 43 attached to the air intake 42, it is possible to prevent a large amount of water from entering the air intake 42. That is, by providing the louver 43 in the closed position and further including the separator 54, it is possible to obtain a high water entry preventing effect on the throttle body connecting pipe 7 and the intake port 10 of the throttle body. The opening / closing state of the louver 43 can be adjusted according to the traveling speed of the hull and the state of the water surface.

  Further, the air intake 42 is provided in a bulging portion 41 provided so as to protrude from the upper surface of the engine cover 4A. By causing the bulging portion 41 to protrude from the upper surface of the engine cover 4A, an air flow hitting the bulging portion 41 is temporarily received, and an air stagnation state is formed at the air intake 42. Basically, there is no such stagnation state outside or near the outer periphery of the air inlet 42, and the air flow rate is relatively high. For this reason, the spray or the like warps from the air intake 42 in the form of being pulled by the outer air flow having a high flow velocity. Also in this respect, an invasion preventing effect such as splashing can be obtained.

  As described above, it is possible to realize high intake performance by making the air intake 42 open forward to facilitate intake, but preventing splashes other than intake air from entering the air intake 42. .

  Further, since the air intake 42 is provided on the upper surface of the engine cover 4 </ b> A that covers the upper portion of the outboard motor 1, the air intake 42 is disposed at the highest position in the outboard motor 1. With this configuration, there are as few obstacles to the inflow air as possible in front of the air intake 42, and a smooth inflow air flow can be obtained with respect to the air intake 42. Moreover, since the air intake 42 is disposed at a higher position from the water surface, it is possible to effectively prevent the invasion of waves and the like.

  Further, in the outboard motor 1, the throttle body is disposed behind the air intake 42 and separated from the rear. That is, the air intake 42 is disposed near the front end of the engine cover 4A, and the throttle body connecting pipe 7 is disposed near the rear end of the engine cover 4A. Thus, by ensuring a long distance between the air intake 42 and the throttle body, the flow path of the intake air becomes longer according to the separation distance, so that it is easy to separate moisture contained in the intake air, and the throttle It is possible to effectively prevent water from entering the body side. Further, by increasing the separation distance between the air intake port 42 and the throttle body, the volume of the expansion chamber 6 can be increased and the charging efficiency of the intake air can be increased.

  Further, a bulging portion 41 is provided on the upper surface of the engine cover 4 </ b> A covering the upper portion of the outboard motor 1, and the rear end of the bulging portion 41 is disposed between the front end and the rear end of the separator 54. An air intake 42 is provided at the front end of the bulging portion 41, and the lower end of the air intake 42 is disposed above the lower end of the skirt 54 b of the separator 54. With this configuration, even when a large amount of water enters from the air intake 42, the entered water can be reliably dropped onto the upper surface of the flat plate portion 54 a of the separator 54. Further, the water that has entered from the air intake 42 contacts either the flat plate portion 54 a of the separator 54 or the skirt portion 54 b and then falls to the bottom 51 of the under plate 5. Therefore, it is possible to avoid a situation in which a large amount of water that has entered from the air intake port 42 falls directly to the bottom 51 of the under plate 5 and the water splash enters the upper end opening 7 a of the throttle body connecting pipe 7.

  In addition, this invention is not limited to the said embodiment, It can implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  The intake structure of the present invention can be applied to, for example, a water bike as well as an outboard motor.

DESCRIPTION OF SYMBOLS 1 Outboard motor 2 Outboard motor main body 21 Engine 22 Propeller 23 Crankshaft 24 Drive shaft 25 Propeller shaft 3 Mounting bracket device 31 Clamp bracket 32 Swivel bracket 33 Swivel shaft 4, 4A, 4B Engine cover 41 Expansion part 41A Inner space 42 Air inlet 43 Louver 5 Underplate 51 Bottom 52 Drainage hole 53 Guide base 53a Opening 53b Inclined surface 54 Separator 54a Flat plate portion 54b Skirt 6 Expansion chamber 7 Throttle body connecting pipe 7a Upper end opening 8 Drainage pipe 8a Bending part 9 One-way valve 10 Throttle body inlet 100 Stern

Claims (5)

An outboard motor intake structure that feeds air taken from the air intake to the throttle body for intake,
The air intake port has a louver that opens forward and can be opened and closed,
An outboard motor intake structure, wherein a space communicating the air intake port and the throttle body is provided isolated from an engine room.   A bulge is formed on the upper surface of the engine cover that covers the upper part of the outboard motor, and an expansion chamber including an inner space formed by the bulge is provided inside the engine cover. 2. The outboard motor intake structure according to claim 1, wherein the dynamic pressure of the air taken from the air intake is converted into a static pressure.   A separator for gas-liquid separation is provided in the middle of the air circulation path in the space, and the separator extends a flat plate portion covering the upper side of the intake port of the throttle body and a front end portion of the flat plate portion downward. The outboard motor intake structure according to claim 1, further comprising a skirt portion.   The outboard motor intake structure according to any one of claims 1 to 3, wherein the throttle body is disposed rearwardly of the air intake port. A drainage passage is provided that communicates the inside and outside of the space, and discharges the water inside the space to the outside.
The drainage passage is provided with a backflow prevention mechanism for preventing water from flowing from the outside to the inside of the space,
The outboard motor intake structure according to any one of claims 1 to 4, wherein the backflow prevention mechanism is both or one of an S-shaped tube and a one-way valve.

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