JP3470679B2 - Outboard intake system with 4-cycle multi-cylinder engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-cycle multi-cylinder
This is related to the intake system of an outboard motor equipped with an engine.
In the engine case consisting of the case and the upper case
Four-stroke engine with the crankshaft pointing up and down
The present invention relates to an air intake device for an outboard motor equipped with an air conditioner. 2. Description of the Related Art A ship propulsion device is provided with an inboard engine depending on its arrangement.
(Inboard engine), inboard / outboard motor (inboard / outboard)
Drive engine), outboard motor (outboard engine)
N). [0003] Outboard motors are often used in small ships,
Attached to the outside of the part. This outboard motor
An engine is installed, and a drive
The outboard motor is rotated left and right.
The hull is turned by doing this. The outboard motor has a two-stroke engine.
Many of these are seen, but recently four cycles
Some have a built-in engine. [0005] Such an internal combustion engine for an outboard motor includes an actual engine.
As disclosed in Japanese Unexamined Patent Publication No. 3-68521, a supercharger is
Outboard internal combustion engine equipped with a turbocharger and cylinder
Cooling water that covers the outer circumference of the intake pipe between each port
A passage for circulating water outside the vessel through the passage and the supply air cooling water passage.
Some have a data pump. [0006] By the way, four cycles
For outboard motors equipped with engines,
The cylinder block becomes hot, so this cylinder block
The branch pipe of the intake manifold, which is located near the
Heat from the dust block, causing the intake air temperature to rise.
Problem, which reduces the charging efficiency of the intake air
Cause the engine output to drop, causing a practical disadvantage.
There was an inconvenience of being. For this reason, a conventional outboard motor, for example,
Japanese Patent Application Laid-Open No. 68521/68521 discloses an intake manifold.
The branch pipe of the mold has a double pipe structure. That is, the branch pipe
The inside of the inner tube is used as an intake passage, and the inner tube is
An annular water jacket is formed between the
The cooling water into the water jacket
Cooling the branch pipe of the intake manifold and charging the intake
This prevents a decrease in engine output due to a decrease in efficiency. However, in the above-described measures, the intake
Because the manifold branch pipe was formed into a double pipe structure,
The structure of the intake manifold is complicated, and this intake manifold
Increases the manufacturing cost of the
Was inconvenient. In addition, a four-cycle multi-cylinder engine has
The intake manifold that guides intake air to each cylinder
An intake branch pipe, surge tank, etc. are attached.
Two engine cycles, etc.
There is a problem that the size of the engine is large. like this
When installing a 4-cycle multi-cylinder engine on an outboard motor
That the engine is covered by the engine case
From the intake branch pipe or surge tank in the engine case
To secure the space for the engine, engine parts, etc.
And it has a good intake supply function.
It is difficult to arrange the intake branch pipe in a form that can secure
There is an inconvenience. [0010] Accordingly, the present invention provides
Lower case and upper case to eliminate inconvenience
In the engine case consisting of
Formed approximately vertical cylinders in the vertical direction
Cylinder block and the front of the cylinder block in the traveling direction
On the side, there is a crankshaft with the axis centered vertically inside
Equipped with a crankcase and advancement of the cylinder block
Cylinder head with a valve operating mechanism on the rear side in the
And formed between each cylinder and the cylinder head.
In the direction intersecting with the traveling direction in plan view of each combustion chamber
On one side and the other side via the intake valve and exhaust valve, respectively, the intake port
Port and the exhaust port, and open the cylinder block.
Downstream end on one side in the direction intersecting the traveling direction in plan view
Are connected to each intake port of the cylinder head.
An intake manifold having an intake branch pipe is provided, and
Direction that intersects the traveling direction of the block
On the other side, an exhaust passage communicating with the exhaust port is provided.
Intake of an outboard motor equipped with a four-cycle multi-cylinder engine
In the apparatus, each of the intake branch pipes is connected to the plurality of cylinders.
Arrange them in the vertical direction according to the number of
Travel through each intake branch pipe upstream of the intake port
While bending in a substantially right-angle direction so as to point forward.
Traveling direction along the side wall at a distance from the binder block
Extending forward, the upstream end of each intake branch pipe is a surge tank
To form the intake manifold, and the intake port
Extend forward in the direction of travel connecting the
Axial length with respect to the traveling direction of multiple intake branch pipes
The side is different in the side view, and the intake at the bottom
Set the length of the branch pipe in the side view to the side of the top intake branch pipe.
It is set to fall backward longer than the length in
Between the branch pipe and the cylinder block
Side reaches the cylinder head and crankcase
A space for arranging engine parts is provided.
It is characterized in that engine parts are arranged in between. DESCRIPTION OF THE PREFERRED EMBODIMENTS An outboard motor intake device according to the present invention
Each intake manifold in the intake manifold has multiple cylinders
Together with the cylinder vertically.
Head upstream from the intake port of the pad
So that it bends in a direction substantially perpendicular to the cylinder block
Extending substantially forward along the side wall across the side wall and extending upstream
The surge tank converges to the surge tank
From the intake manifold to the intake port of each cylinder.
It can be arranged easily, and the intake branch pipe and cylinder block
The front and rear sides in the traveling direction are between the cylinder head and the cylinder head.
And a space for engine parts to reach the crankcase
The engine components in this engine component placement space.
As a result, between the intake branch pipe and the cylinder block
Placing engine parts using the engine parts placement space
Connection between the intake port and the surge tank
Of multiple intake branch pipes extending forward in the traveling direction
Length in the axial direction with respect to the direction
The length of the lowermost intake manifold in side view.
The rear lower part is longer than the length of the upper intake branch pipe in side view.
Setting the surge tank to the engine
To the top of the case and above the engine
Can be arranged. An embodiment of the present invention will be described below in detail with reference to the drawings.
This will be described in detail. 1 to 8 show an embodiment of the present invention.
It is. 3 to 6, reference numeral 2 denotes an outboard motor, and reference numeral 4 denotes a mid.
Unit. Of the middle unit 4 of the outboard motor 2
In front of the traveling direction (right side in FIG. 7), the outboard motor 2 is
An outboard motor holder 6 is provided for attachment to a body (not shown).
ing. The outboard motor holding portion 6 has a tilting portion for the outboard motor 2.
A tilt shaft 8 is attached. In the middle unit 4, FIG.
As shown in FIG.
Have been. Oil is placed on the upper side near the drive shaft 10.
Lupine 12 is provided, and the exhaust tube is
A probe 14 is provided. The drive shaft 10 is provided with an
The driving force of the crankshaft 34 of the engine 36 is
Through the gears (not shown) in the rearward direction (in FIG. 4)
(To the left).
is there. A gear case is provided below the middle unit 4.
A base 16 is attached. In this gear case 16
The gear connected to the lower end of the drive shaft 10
(Not shown) is accommodated. Also, this gear case
The gear 16 has a propeller connected to the gear (not shown).
18 is rotatably mounted. Further, on the upper part of the middle unit 4,
The engine case 20 is attached. This engine
The case 20 includes a lower case 22 and an upper case 24.
It consists of. The upper case 24 has an upper part
Side is recessed, and this recessed portion
An air inlet 26 opening upward (upward in FIG. 7) is formed.
Have been. Further, the cross section is substantially L-shaped at the recessed portion.
A cover 28 is attached. This cover part
28 has a rear portion (left in FIG. 7) when attached to a recessed portion.
An opening 30 is formed on the side (side). The engine case 20 has a
The crankshaft 34 is moved up and down
A four-cycle multi-cylinder engine 36
Have been. The engine 36 is, as shown in FIGS.
And an end composed of a lower case 22 and an upper case 24.
In the gin case 20, a substantially horizontal axis whose axis is oriented in the traveling direction
Up and down the first to fourth cylinders 48-1 to 48-4
A cylinder block 38 formed by overlapping in the direction
The shaft center is set up and down in front of the
Crankcase with a crankshaft 34 oriented in one direction
Stub crankshaft holding section 44 and cylinder block 3
8, a cylinder head provided with a valve mechanism 87 on the rear side in the traveling direction.
C and 40 are provided respectively. That is, the cylinder block of the engine 36 is
Is disposed at a substantially central portion of the engine accommodating portion 32.
Have been. The rear side of the cylinder block 38 in the traveling direction
(Left side in FIG. 1)
Cylinder head covering cylinder head 40 and valve operating mechanism 87
The cover 42 and the cover 42 are sequentially attached. The front side in the traveling direction of the cylinder block 38
(Right side in FIG. 1), the crankshaft holding portion 44
Therefore, the crankshaft 34 whose axis is oriented in the vertical direction is
Supported. This cylinder block 38 has an engine
The engine water jacket 46 that cools the
Is provided. In the cylinder block 38, FIG.
As shown in the figure, a plurality of substantially horizontal
The first to fourth cylinders 48-1 to 48-4 are vertically
They are formed in layers. These first to fourth cylinders
48-1 to 48-4 include first to fourth pistons 50-1.
To 50-4 are reciprocally arranged. The first to fourth pistons 50-1 to 50-
4 via the first to fourth connecting rods 52-1 to 52-4.
Are connected to the crankshaft 34 respectively. The cylinder head 40 has first to fourth
Between the cylinders 48-1 to 48-4 and the cylinder head 40
In the plan view of each combustion chamber 54 formed between the
One side and the other side of the cross direction (lower and upper in FIG. 1)
Side), the intake valve 62 and the exhaust valve
The intake port 56 and the exhaust port 74 are connected via the air valve 82.
It is provided with an opening. Here, the first to fourth cylinders 48-1 to 48-4
8-4 have the same shape, so that the second
Only the cylinder 48-2 will be described, and the first, third and fourth cylinders will be described.
Descriptions of the solders 48-1, 48-3, and 48-4 are omitted. The engine 36 has a cylinder head 4
0, the second piston 50-2, and the second cylinder 48-2.
Thus, a combustion chamber 54 is formed. In a plan view of the cylinder head 40,
On one side (lower side in FIG. 1) in the direction intersecting with the traveling direction
Is formed with an intake port 56 communicating with the combustion chamber 54.
Have been. The intake port 56 constitutes an intake device.
A second intake branch pipe 66-2 of an intake manifold 64 described later.
Are connected to each other. this
Below the second intake branch pipe 66-2 close to the intake port 56
At the flow end, an injector for injecting fuel into the intake port 56 is provided.
Cutter 58 is provided. Intake of the intake port 56
The opening 60 is formed by the intake valve 62 that forms the valve mechanism 87.
It is opened and closed. Further, the plan view of the cylinder head 40
In the direction crossing the traveling direction
Side), an exhaust port 74 communicating with the combustion chamber 54 is provided.
Is formed. The exhaust port 74 has a cylinder block.
The exhaust passage, which is an exhaust passage provided on the other side in the traveling direction of the lock 38,
The air branching section 76 and the exhaust collecting section 78 communicate with each other. Previous
The exhaust port 80 of the exhaust port 74 constitutes a valve operating mechanism 87.
The valve is opened and closed by an exhaust valve 82 that operates. The cylinder head
The door 40 has a slight inclination at a substantially central portion of the combustion chamber 54.
And an ignition plug 84 is attached. The intake manifold 64 includes the first to the first
Four intake manifolds 66-1 to 66-4 and the first to fourth intakes
Surge arranged upstream of branch pipes 66-1 to 66-4
And a tank 70. This surge tank
A throttle body 72 is provided upstream of 70.
I have. More specifically, the intake manifold 64 is shown in FIG.
As shown in the figure, on one side of the traveling direction of the cylinder block 38,
The downstream end is attached to the cylinder head 40 and the first to fourth
Connect to each intake port 56 of cylinders 48-1 to 48-4
A plurality of first to fourth intake branch pipes 66-1 to 66-4
Provided. First to fourth intake branch pipes 66-1 to 66-4
Are attached to the downstream end attached to the cylinder head 40.
Injectors 58 for injecting fuel into the air ports 56, respectively.
Mounted and provided. First to fourth intake branch pipes 66-1 to 66-4
Is the number of the plurality of first to fourth cylinders 48-1 to 48-4.
Along with the vertical direction in side view as shown in FIG.
As shown in Fig. 1, cylinder heads are arranged in parallel.
40 above the first to fourth intake ports 48-1 to 48-4
Curved almost perpendicularly so that the flow side is directed forward in the traveling direction
While the side wall 39 is spaced from the cylinder block 38.
Extend almost forward in the direction of travel, and
And is provided so as to converge with the ridge 36. The surge tank 36
A position forward of the crankshaft holding portion 44 (in FIG.
(Right side). The intake manifold 64 is shown in FIG.
As described above, the intake ports of the first to fourth cylinders 48-1 to 48-4.
Direction of connection between the port 56 and the surge tank 36
A plurality of first to fourth intake branch pipes 66-1 extending forward.
The length in the axial direction with respect to the traveling direction of 66-4 in side view
And the lowermost first intake branch pipe 66
-1 in the side view, the uppermost fourth intake branch pipe
66-4 set to fall backward longer than the length in side view
are doing. Thereby, as shown in FIG.
The air branch pipes 66-1 to 66-4 and the cylinder block 38
The front and rear sides in the traveling direction are between the cylinder heads 40.
And the crankshaft holding portion 44 serving as a crankcase.
An engine component arrangement space 41 is formed and provided. The rear side in the traveling direction of the cylinder head 40
(Left side in FIG. 7), the cylinder head 40
Valve train chamber 86 is formed by cylinder head cover 42
Have been. The valve operating chamber 86 includes a valve operating mechanism.
Operate the intake and exhaust valves 62 and 82 constituting 87
A cam shaft 88 is provided. The camshaft 88 has suction
-The exhaust cams 90A and 90B are fixed. Rear side in the traveling direction in the cylinder head 40
(Left side in FIG. 1), a breather plate 92 is provided.
To form a breather chamber 94. An outboard motor equipped with the engine 36
2 is the traveling direction in plan view of the cylinder block 38
On one side (lower side in FIG. 1)
First to fourth intake branch pipes 66-1 of the intake manifold 64.
Of the engine parts at the side of the engine 36 at 66-66-4
A space for cooling the intake air, which is an engine component, is
A tap jacket 96 is provided. More specifically, as shown in FIG. 1, FIG. 2 and FIG.
And communication between the first and second intake branch pipes 66-1 and 66-2.
Plate-shaped first connecting portion 98-1 and second and third intake branches
A plate-shaped second communication part 9 for communicating between the pipes 66-2 and 66-3.
8-2 and the third and fourth intake branch pipes 66-3 and 66-4
And a plate-shaped third communication portion 98-3 for communicating the
The first to fourth intake branch pipes 66-1 to 66-4 are connected to the first to third stations.
The entangled portions 98-1 to 98-3 are integrally connected. The first to fourth intake branch pipes 66-1 to 66-6
6-4 and before and after the first to third communication parts 98-1 to 98-3
At the end, as shown in FIG.
And substantially parallel in the vertical direction, and the engine 36
First and second protrusions 100-1 and 100-1 protruding toward the side
00-2, and the first and second protrusions 100-1,
100-2 is connected to the first to fourth intake branch pipes 66-1 to 66-66.
-4 and the first to third communication parts 98-1 to 98-3 integrally
Form. Of the first to fourth intake branch pipes 66-1 to 66-4
First and fourth intake branch pipes 66-1, 66 located at the upper and lower ends
-4, as shown in FIG.
Substantially parallel in the horizontal direction, and the engine 3
6 and the first and second protrusions
The third and the third connecting the upper and lower ends of the parts 100-1 and 100-2
The four protrusions 100-3 and 100-4 are formed integrally.
First to fourth intake branch pipes 66-1 to 66-4 and first to third
Connecting portions 98-1 to 98-3 and first to fourth projecting portions 100-
1 to 100-4, toward the engine 36 side
Form an open concave space. The third and fourth protrusions 1
00-3 and 100-4 have a cooling water pipe mounting portion 10
4 and 104 are provided respectively. Further, the first to the first sides which are the open sides of the concave space.
Each of the fourth protrusions 100-1 to 100-4 is associated with a distal end portion thereof.
A plate-shaped water jacket cover 102 to be provided is provided,
Engines of the first to fourth intake branch pipes 66-1 to 66-4
36 side part, the first to third communication parts 98-1 to 98-3
And the first to fourth projecting portions 100-1
~ 100-4 and water jacket cover 102
Therefore, a large capacity engine component for intake air cooling
The water jacket 96 is formed. The water jacket 96 for cooling the intake air is provided.
Cooling water in the cooling water circulation path for normal engine cooling
It is supplied by another cooling water circulation path. Next, the operation will be described. The outboard motor 2 comprises an intake manifold 64.
The first to fourth intake branch pipes 66-1 to 66-4 and the first
To the third connecting portions 98-1 to 98-3 and the first to fourth projecting portions 1
00-1 to 100-4 and water jacket cover 10
2, the first to fourth intake branch pipes 66-1 to 66-
4 in the engine component placement space 41 on the side of the engine 36
A water jacket 96, which is an engine part, is provided
You. When the outboard motor 2 is driven, the intake manifold 6
To 4th intake branch pipes 66-1 to 66-4
Water jacket on the side of the engine 36
Cooling water is supplied to the engine 96 and heat is absorbed by the heat of the engine 36.
Prevents the temperature of the air manifold 64 from rising and improves the charging efficiency of the intake air
Is prevented from decreasing. Thus, the structure of the intake manifold 64 is described.
Without complicating the structure, it will be a simple mold structure
The first to fourth intake branch pipes 66 of the intake manifold 64
Water jacket 96 can be easily formed on 1-66-4
The production cost of the intake manifold 64 is kept low.
It is economically advantageous. Further, the water jacket 96 is
To the engine 36 side of the fourth intake branch pipes 66-1 to 66-4
Parts and engines of the first to third communication parts 98-1 to 98-3
Part 36 side, the first to fourth protrusions 100-1 to 100-100
-4 and the water jacket cover 102
The intake manifold by the heat of the engine 36 side.
To prevent the temperature of the airfield 64 from rising, improving the charging efficiency of the intake air.
It is practically advantageous and can be used for the first to fourth intake air
Sides of the manifolds 66-1 to 66-4 that are separated from the engine 36
Between the engine case 20 and the intake manifold 64
The lack of a water jacket means that
Reduce the gap between the gin case 20 and the intake manifold 64
And contributes to making the engine case 20 more compact.
obtain. Furthermore, the first to fourth intake branch pipes 66-1 to 66-6
6-4 engine 36-side portion and first to third communication portions 98
-1 to 98-3 on the engine 36 side and the first to fourth protrusions
Outer parts 100-1 to 100-4 and water jacket cover
-102 water for cooling intake air with a large capacity
By forming the jacket 96, the first to fourth
Intake branch pipes 66-1 to 66-4 and water jacket 9
6 can increase the contact area, and cool the intake air reliably
Can be. Further, a water jacket for cooling the intake air is provided.
Cooling water circulation for normal engine cooling
Supply by a separate cooling water circulation path
And independent of the temperature control of the engine 36
The temperature can be controlled, which is practically advantageous. The intake device of the outboard motor 2 has an intake manifold.
The first to fourth intake branch pipes 66-1 to 66-4 of the
In accordance with the number of the plurality of first to fourth cylinders 48-1 to 48-4,
In parallel with each other in the vertical direction,
Upstream of each intake port 56 of the nozzle 40 in the traveling direction.
Cylinder block while bending in a substantially right angle direction
Forward along the side wall 39 at a distance from the
And the upstream end converges to the surge tank 70
From the surge tank 70 to the first to fourth cylinders 48.
-1 to 48-4 toward the respective intake ports 56.
4 Smoothly arrange the intake branch pipes 66-1 to 66-4.
Can be. For this reason, the intake device of this outboard motor 2
The first to fourth intake branch pipes 66 without impairing the air supply function
-1 to 66-4 and surge tank 70 in engine case 2
0, and the entire engine 36 can be
Can be customized. The intake device of the outboard motor 2 has a syringe.
First to fourth intake branch pipes arranged on one side of the double lock 38
66-1 to 66-4 and between the cylinder block 38
The front and rear sides in the traveling direction are the cylinder head 40 and the
Engine component arrangement space 4 reaching link shaft holding portion 44
1 is provided in the engine part arrangement space 41.
By placing the parts, the engine parts placement space 41
Water jar for cooling the intake, which is an engine component
A bracket 96 can be provided, and the cylinder block 3
8 is provided with an exhaust passage on the other side.
There is no hindrance to the arrangement of the jacket 96. For this reason, the intake device of this outboard motor 2
In the engine case 20, the air does not interfere with other parts.
The water jacket 96, which is a
Can be. Further, the intake device of this outboard motor 2
How to connect between port 56 and surge tank 70
A plurality of first to fourth intake branch pipes 66-1 extending forward in the front direction
The length in the axial direction with respect to the traveling direction of
Visually different from each other, and the first intake branch at the bottom
The length in the side view of the pipe 66-1 is set to the fourth intake
Fall backward longer than the length of the branch pipe 66-4 in side view
Setting the surge tank 70 to engine
The upper part inside the casing 20 and the upper part with respect to the engine 36
Can be arranged. In the outboard motor 2, the engine case 20
To avoid water droplets in the air taken in
Air inlet 2 as far as possible from the water surface
Generally, 6 is provided. For this reason, the intake device of the outboard motor 2 is
The upper part of the engine case 20 and the engine 36
The surge tank 70 is located at the top.
Does not contain water droplets in the upper part of the engine case 20
Guides air that is not thermally affected by air or engine 36
And supply it to the first to fourth cylinders 48-1 to 48-4.
Can be The surge tank 70 has a capacity of an intake passage.
It is a functional part for increasing the amount partially,
It is lightweight for a large size. Because of this,
Put the large surge tank 70 in the upper part of the engine case 20
The outboard motor 2 placed in the
20 is removed.
Engine parts can be made less visible,
The appearance of the housing 36 can be improved. As described above, the outboard motor of the outboard motor according to the present invention has the following features.
From the surge tank to the intake port of each cylinder.
The intake manifold can be arranged smoothly,
Engine parts distribution between the manifold and the cylinder block
Engine parts can be arranged using the installation space,
Place the surge tank in the upper part of the engine case
Can be located at the top with respect to. Therefore, the outboard motor intake device of the present invention
The intake branch pipe and surge without impairing the intake supply function
The tank can be placed inside the engine cover,
The entire gin can be made compact, and other parts
Engine parts without interfering with
And the top of the engine case contains water droplets.
No air or air that is not thermally affected by the engine
And can be supplied to each cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view taken along line II of FIG. 7 showing an embodiment of the present invention. FIG. 2 is an enlarged side view of a main part of the outboard motor. FIG. 3 is a front view of the outboard motor. FIG. 4 is a left side view of the outboard motor. FIG. 5 is a rear view of the outboard motor. FIG. 6 is a right side view of the outboard motor. FIG. 7 is a sectional view taken along line VII-VII in FIG. 5; FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 1; [Description of Signs] 2 Outboard Motor 4 Middle Unit 16 Gear Case 18 Propeller 20 Engine Case 22 Lower Case 24 Upper Case 26 Air Inlet 28 Cover 32 Engine Storage 34 Crankshaft 36 Engine 41 Space 46 Engine Water Jacket 64 Intake Manifold 66 Intake branch pipe 68 Intake branch passage 70 Surge tank 72 Throttle body 98 Communication section 100 Projection section 102 Water jacket cover

Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02B 67/00 F02M 35/10 301P F02M 31/20 B63H 21/26 G 35/16 D (72) Inventor Nobuyuki Shomura Takatsukacho, Hamamatsu-shi, Shizuoka 300 Suzuki Co., Ltd. (72) Inventor Hidehiko Yoshioka 300, Takatsuka-cho, Hamamatsu City, Shizuoka Prefecture Suzuki Co., Ltd. (72) Jiro Saiga 300, Takatsuka-cho, Hamamatsu City, Shizuoka Prefecture Suzuki Co., Ltd. (56 References JP-A-3-172570 (JP, A) JP-A-4-175456 (JP, A) JP-A-4-295170 (JP, A) JP-A-60-4492 (JP, A) 1-111174 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 35/16 B63H 21/26

Claims (1)

(57) [Claim 1] A cylinder block formed by vertically stacking a plurality of substantially horizontal cylinders whose axes are directed in a traveling direction in an engine case including a lower case and an upper case. A crankcase having a crankshaft with an axis oriented in the vertical direction on the front side in the traveling direction of the cylinder block, and a cylinder head having a valve mechanism on the rear side in the traveling direction of the cylinder block. Of each combustion chamber formed between each cylinder and the cylinder head.
It is opened an intake port and an exhaust port through the respective intake and exhaust valves on one side and the other side in the direction orthogonal to the traveling direction in a plan view, viewed from the smell of the cylinder block
The downstream end on one side in the direction orthogonal to the traveling direction is disposed an intake manifold having a plurality of intake branch pipes to contact each intake port of the cylinder head and intersects the traveling direction in a plan view of the cylinder block Te In an outboard motor intake device equipped with a four-cycle multi-cylinder engine having an exhaust passage communicating with the exhaust port on the other side in the direction, each of the intake branch pipes is connected to the plurality of cylinders. The cylinders are arranged in parallel in the vertical direction in accordance with the number, and each of the intake branch pipes on the upstream side of the intake port of the cylinder head is bent in a substantially perpendicular direction so as to be directed forward in the traveling direction, and the side portions are spaced apart from the cylinder block. Extends almost forward along the wall in the direction of travel
And, an upstream end of the respective intake branch pipes constituting said intake manifold by converging the surge tank, the progress of the plurality of intake branch pipes that extend forward in the traveling direction for connecting the intake port and the surge tank respectively made different in a side view an axial length with respect to the direction, and the length in the side view of the bottom of the intake branch pipe set to the rear edge longer than the length in the side view of the top of the intake branch pipe, the intake Between the branch pipe and the cylinder block, the front and rear sides in the traveling direction are as described above.
The engine component arrangement space reaching the cylinder head and the crankcase is provided, engines in the engine component arrangement space
An outboard motor intake system equipped with a four-cycle multi-cylinder engine, characterized by the placement of parts .