JP3447856B2 - Exhaust system for 4-cycle outboard motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outboard motor exhaust system equipped with a four-cycle engine.

[0002]

2. Description of the Related Art Conventionally, a two-cycle engine is generally used for outboard motors, and in the case of a two-cycle engine, the intake system is arranged on the crank chamber side, so that a space for arranging the exhaust system on the cylinder head side can be easily secured. . For example, in the case of a two-cycle V-type engine, since the exhaust passage can be integrally formed with the cylinder block so as to be located in the V bank, the problem that the width of the outboard motor becomes large due to the exhaust device is not a problem. Almost never happened.

[0003]

Recently, however, the adoption of a 4-cycle engine has been studied mainly from the viewpoint of exhaust gas purification. When a 4-cycle engine is adopted as an outboard engine, unlike the 2-cycle engine, both the intake system and the exhaust system are connected to the cylinder head side. May increase, which may hinder the downsizing that is particularly required for outboard motors.

The present invention has been made in view of the above circumstances, and when a four-cycle engine is adopted as an outboard motor, a four-cycle outboard motor capable of minimizing the expansion of the outboard motor width is provided. The purpose is to provide an exhaust system.

[0005]

According to a first aspect of the present invention, there is provided an exhaust system for a four-cycle outboard motor, in which a four-cycle engine is vertically arranged so that a crankshaft is substantially vertical during traveling. An exhaust guide for introducing gas into the muffler is connected so as to form a space between the exhaust pipe and the cylinder head, and the upstream end of the exhaust pipe is connected to the exhaust port that is open to one side in the ship width direction of the cylinder head. The exhaust pipe extends from the one side of the cylinder head to the center side in the engine width direction through the space between the cylinder head and the exhaust guide, and the exhaust pipe extends to the muffler of the exhaust guide at the engine center side. It is characterized in that it is connected to the communicating exhaust passage.

According to a second aspect of the present invention, in the first aspect of the present invention, the engine is a V-type engine in which cylinder portions having cylinders are arranged so as to form a V-shape (V bank). Extends from the outside of the cylinder head of each cylinder portion through the space between the cylinder head and the exhaust guide toward the V bank center side, and the exhaust pipes are connected to the exhaust passages of the exhaust guide at the V bank center side. It is characterized by

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 21 are views for explaining an outboard motor according to an embodiment of the present invention. FIG. 1 is a left side view, FIGS. 2 to 7 are plan views, and FIG. 8 is a sectional plane view of a crank chamber portion. FIG. 9, FIG. 9 is a rear view of the intake system, FIG. 10 is a rear view around the cam shaft, FIG. 11 is a sectional left side view of the intake system, and FIG.
Is a cross-sectional left side view, FIG. 13 is a view taken along the line XIII-XIII in FIG. 12,
FIG. 14 is a diagram for explaining the flow directions of lubricating oil and cooling water, and FIGS. 15, 16 and 17 are XV-XV lines and XVI- of FIG.
18 and 19 are sectional left side views near the oil pan, FIG. 20 is a sectional left side view of the exhaust manifold, and FIG. 21 is a sectional rear view of the exhaust manifold.

In the figure, reference numeral 1 is an outboard motor, which is mounted on a clamp bracket 3 fixed to a stern 2a of a hull 2 through a swivel arm 4 in a vertical direction around a tilt shaft 5 (arrow in FIG. 1). It is pivotally supported in the a direction) and is supported so as to be rotatable around the turning shaft 6 in the left-right direction (direction of arrow b in FIG. 2). The outboard motor 1 has an upper case 9 connected to a lower case 8 holding a screw 7 and a forward / reverse switching mechanism 7a, and cowling around an engine 10 mounted on the upper case 9 via an exhaust guide 40. It has a structure surrounded by 11.

Here, the cowling 11 is an injection-molded product of resin, and is divided into two parts, an upper culling 11b and a lower cowling 11c, which are separated by a mating surface 11a. The upper cowling 11b is a box-shaped member having an opening at the mating surface 11a, and has a die-cutting gradient whose cross-sectional shape decreases toward the upper side from the mating surface 11a.
Also, on the left near the upper end of the rear wall of the upper cowling 11b,
A pair of right outside air introduction openings 11d are formed. In addition,
The left and right outside air inlets 11d and 11d may be entirely used as outside air inlets.

The engine 10 is a water-cooled 4-cycle V-type 6-cylinder crankshaft vertically installed type engine. The cylinder block 12 of the engine 10 is V-shaped (V bank)
The left and right cylinder portions 12a, 12 formed so as to form
b and a common crankcase portion 12 integrally formed so as to connect the bottom portions of the cylinder portions 12a and 12b to each other.
and c. Here, as shown in FIG. 7, portions of the left and right cylinder portions 12a and 12b in the vicinity of the head-side mating surfaces of the V bank inner side walls are connected by a cover wall 12g, and the cover wall 12g and the inner side wall are connected to each other. The space surrounded by is a V bank space A that extends vertically in a tunnel shape.

Three cylinders (cylinder bores) 12d are formed in each of the cylinder portions 12a and 12b, and the cylinders of the left and right cylinder portions 12a and 12b are alternately offset in the crankshaft direction. It is arranged and formed. The crankcase portion 12c and the crankcase cover 17 connected to the front mating surface of the crankcase portion 12c form a pair of cylinders 12d and 12d offset from each other.
Crank recess 1 forming one crank chamber E with respect to
2e is formed.

Each piston 14 slidably inserted in each cylinder 12d is connected to a crankshaft 16 via a connecting rod 15. The journal portion 16a of the crankshaft 16 includes a bearing wall 12f formed in the crankcase portion 12c so as to form a boundary between the crank chambers E, and a bearing cap detachably attached to the bearing wall 12f. It is rotatably supported by 13 and.

A baffle plate (partition plate) 75 is provided in the crank chamber E. The baffle plate 75 is formed by molding a metal plate in which a large number of small holes are formed into substantially the same shape as the crankcase cover 17, and there is no space between the baffle plate 75 and the crankcase cover 17. The space is provided as an ascending passage E'for ascending the gas containing the oil mist.

The upper end of the ascending passage E'communicates with a chain chamber B having an oil separator function, which will be described later. The lubricating oil that has fallen to the lower end of the crank chamber E drops into the oil pan 41 through the oil return passage indicated by the dashed arrow H in FIG. Specifically, as shown in FIG. 15, the lubricating oil flows along the boundary wall surface between the pump chamber C and the crank chamber E, passes through the opening I of the upper guide 40a, and flows down into the recess K of the upper guide 40a. After that, it passes through the opening L and falls into the oil pan 41.

As will be described later, a starter motor 52 is provided on the front side of the crankcase cover 17, and the starter motor 52 of the crankcase cover 17 is provided.
The portion corresponding to is recessed inside the engine to prevent the outboard motor from bulging to the front side. Further, due to this recess, the width of the recess 17d portion of the ascending passage E'is narrower than the other portions.

The left and right cylinder parts 12a, 12b of the cylinder block 12 are joined to the rear side (the head side).
The left and right cylinder heads 18a and 18b are mounted on and are fastened to the cylinder block 12 by head bolts. The rear side mating surfaces (cover side mating surfaces) of both cylinder heads 18a and 18b are left and right head covers 19a and 19b.
The left and right cam chambers F and F are formed by being covered with b and extending in the crankshaft direction (vertical direction).

Two intake opening openings and exhaust valve openings are formed for each cylinder in the combustion recess 18c formed in the block-side mating surfaces of the cylinder heads 18a, 18b, and the intake valves for opening and closing the openings are formed. 20a and exhaust valve 20b are opened and closed by cam noses 21e of intake cam shaft 21a and exhaust cam shaft 21b, respectively.

The intake and exhaust cam shafts 21a and 21b are
The cylinder heads 18a, 18b and the head cover 19a,
Two cam chambers F and F are formed in parallel with the crankshaft 16. A cam sprocket 32a having a large diameter (twice the crank sprocket) is formed at the upper end of the left cylinder intake cam shaft 21a and the right cylinder exhaust cam shaft 21b.
32b is mounted and bolted and fixed by a bolt 21c. The cam sprockets 32a, 32b and the small-diameter crank sprocket 16b formed near the upper end of the crankshaft 16 are connected by a timing chain 33a. The timing chain 33a connects the cam chambers F and F with the crank chamber E and is arranged in the chain chamber B located at the upper end of the engine.

Here, the upper cowling 11b has a die-cutting gradient in which the cross-sectional shape becomes smaller toward the upper side as described above, but in the case of the present engine 10, FIG.
As shown in, the basic width dimension of the upper cowling 11b is determined based on the width (the horizontal dimension in the drawing) of the chain chamber B in which the cam sprockets 32a and 32b are arranged, and the width becomes narrower toward the upper side than that portion. The draft is set so that the width becomes wider toward the lower side.

A guide shaft 34 for supporting a guide sprocket 34a is arranged in the V bank space A, and the guide sprocket 34a guides the timing chain 33a along the V bank shape. .
The portion between the crank sprocket 16b and the cam sprocket 32b of the timing chain 33a and the portion between the cam sprocket 32b and the guide sprocket 34a are
It is guided by fixed guide plates 35a and 35b.

Furthermore, the timing chain 33a is also provided.
A movable tensioner plate 35c is slidably contacted between the left cam sprocket 32a and the crank sprocket 16b. A rear end portion of the tension plate 35c is pivotally supported by a pin 35d, and a front portion thereof is pressed by the pressing mechanism 36 toward the center of the engine. As a result, the tension of the timing chain 33 is adjusted so that it is always constant.

Each sprocket 16b, 32a, 32
b, 34a, the timing chain 33a, the guide plates 35a, 35b, and the tension plate 35c, the cylinder block 12, the crankcase cover 17,
Cylinder heads 18a, 18b and head cover 19
A chain chamber B in which a chain cover 37 is removably attached to the upper end opening of the Y-shape in plan view formed by a and 19b.
It is located inside.

Further, the intake and exhaust cam shafts 21a and 21b of each cylinder part have a smaller diameter (1) than the cam sprocket.
The intermediate chain 33b is wound around the intermediate sprockets 32c, 32c of about / 2). The intermediate sprocket 32c is located so as to be adjacent to the cam sprockets 32a, 32b at the upper end with the cam bearing 21d sandwiched therebetween, that is, below the cam sprocket 32a and at the highest position.

The crank chamber E and the cam chambers F, F communicate with each other in the chain chamber B. Although not shown, the chain chamber B is provided with an oil separator function of separating the lubricating oil component from the engine gas containing the oil mist introduced into the chamber. This feature
For example, it can be realized by making the inside of the chain chamber B into a maze structure.

A bulging portion 37a, which is substantially circular in a plan view, is bulged upward at a portion of the chain cover 37 facing the cam sprocket 32a, 32b so as to avoid interference with the sprocket fixing bolt 21c. Has been done.
The bulging portion 37a is located at the highest position in the chain chamber B. Exhaust holes 37b for exhausting gas in the engine are formed in the bulging portion 37a, and each exhaust hole 37b is connected to a downstream side of a throttle valve 28 of an intake system 22 described later by an exhaust hose 37c. .

The discharge hole 37b may be provided in a portion between the crank shaft and the cam shaft of the chain chamber B, as shown by a chain double-dashed line in FIG.

Further, each of the cylinder heads 18a and 18b described above.
The intake valve openings of the above are led to the inside of the V bank toward the rear of the hull by the intake ports 18d and 18d, and the intake system 22 is connected to the external connection openings of the intake ports 18d and 18d. The intake system 22 includes the left and right cylinder parts 12
Left and right are symmetrical so that the intake pipe lengths to a and 12b are made equal. That is, the left and right surge tanks 23a, 23
b is arranged in parallel with the crankshaft 16 on the rear side of the left and right head covers 19a and 19b, and the left and right surge tanks 23a and 23b and the intake ports 18d and 18d are connected to the intake manifold portion 23c and the intake air. The structure is such that they are connected and communicated via an intake plate 24 having a hole 24a, and the substantial intake pipe length is the same for all cylinders.

The intake plate 24 includes the intake ports 18d of the left and right cylinder heads 18a and 18b.
It is a plate-like member that is installed between the external connection openings of 18d so as to close the upper surface of the V bank. The intake plate 24 has an intake hole 24a which communicates the intake port 18d with the intake manifold portion 23c, and a fuel injection valve 26 is provided in the intake plate 24 from the intake hole 24a through the intake port 18d. The intake valve 20a is mounted so as to inject and supply fuel toward the back surface of the valve head.

The left and right surge tanks 23a, 23
b and the left and right intake manifold portions 23c, 23c are integrally cast, and the fuel is injected into each of the fuel injection valves 26 in the tunnel formed by the left and right intake manifold portions 23c, 23c. A fuel supply rail 25 to be supplied is inserted and arranged in the vertical direction. Further, a regulator 27 for adjusting the fuel pressure is attached to the upper end of the fuel supply rail 25. Here, the fuel supply rail 25 is fixed to a leg portion 24b provided upright on the intake plate 24. Therefore, the fuel supply rail 25, the intake plate 24, and the fuel injection valves 26 can be assembled in advance in separate steps. Further, the fuel flows into the supply rail 25 from the lower end thereof and is discharged through the regulator 27 at the upper end. Thereby, the air in the fuel can be easily removed.

Further, the left and right surge tanks 23a, 2
The left and right intake pipe portions (branch passages) 23d, 23d integrally formed at the upper end of 3b join together near the upper end of the engine and at the center in the width direction.
3e faces the front of the hull. And the merging pipe portion 23e
Throttle body 28 with a built-in throttle valve 28a
Is connected to the throttle body 28, and an introduction pipe 30 is connected to the throttle body 28 via a flexible bellows hose 29. The opening of the introduction pipe 30 is located at the upper end of the engine, the intake air is hard to receive the heat from the engine, and the rise of the intake air temperature is avoided.

The throttle body 28 is fixed to a bracket portion 24c formed by extending the upper end portion of the intake plate 24 upward together with the merging pipe portion 23e.
The throttle body 28 is located slightly above the upper wall of the cylinder block 12. The bellows hose 29 is for increasing the airtightness at the connecting portion between the introducing pipe 30 and the throttle body 28 and preventing the generation of noise due to the suction of air from the connecting portion. An introduction pipe 30 connected to the upstream side of the hose 29 is supported by a chain cover 37 via a rubber band 30a.

The left and right surge tanks 23a and 2a
A metal support plate 77 is provided between the rear surfaces of the 3b, and an electric component 78 such as a control box is mounted on the rear surface of the support plate 77. The support plate 77 not only functions as a heat sink that radiates the heat generated in the electrical component 78 to the surge tanks 23a and 23b to promote cooling of the electrical component 78, but also connects the left and right surge tanks 23a and 23b to each other. It also has the function of preventing the generation of vibration and noise by increasing the rigidity.

The left and right cylinder heads 18a, 18
The exhaust valve opening of b is led to the V bank outer wall surface (left and right wall surfaces) by the left and right exhaust ports 18e, 18e,
Symmetrically formed left and right exhaust systems 38a and 38b are connected to the left and right exhaust ports 18e and 18e.
Each of the exhaust systems 38a and 38b includes the above three exhaust ports 1
8e, an exhaust manifold 39 connected to the exhaust manifold 39, an exhaust pipe 40 connected to the exhaust manifold 39 via an exhaust guide 40 and an exhaust port 41a formed in an oil pan 41, and a muffler connected to the exhaust pipe 42. 65 and.

The exhaust manifold 39 is shown in FIGS.
As shown in FIG. 1, each of the cylinder parts 12 of the cylinder block 12 is merged with the three exhaust ports 18e.
a, 12b extending downward along the outer wall surface, passing between the cylinder heads 18a, 18b and the exhaust guide 40, and extending inside the V-bank, the exhaust guide 4
It is connected to the exhaust passage 40e of 0.

The exhaust manifold 39 has a double-pipe structure having a water-cooling jacket J and is integrally cast, and has a structure in which the outer periphery of an inner pipe portion 43 through which exhaust gas flows is surrounded by an outer pipe portion 44 constituting a water-cooling jacket. Has become. The exhaust manifold 39 has a body portion 39a located on the upper side.
And an elbow-shaped joint portion 39b located on the lower side, are divided into two parts at a horizontal position between the cylinder heads 18a, 18b and the exhaust guide 40, and both are connected by a rubber joint 45. ing. Since the horizontal portion is divided into two parts in this way, the workability when connecting the two parts by the rubber joint 45 can be improved.

The rubber joint 45 includes a rubber inner ring 45a for connecting the inner tube portions 43 to each other and an outer tube portion 44.
The inner ring 45a is fixed to the inner pipe portion 43 by a band 45c.

At the time of assembling the main body portion 39a and the joint portion 39b, the inner ring 45a is first fixed to the inner pipe portion 43 by the band 45c while the outer ring 45b is axially displaced to the position indicated by the broken line in FIG. Then, move the outer ring to the normal position. Since the rubber joint 45 having the two-divided structure and having the flexibility is used, the dimensional error between the external connection opening position of the exhaust port 18e of the cylinder head and the opening position of the exhaust passage 40e of the exhaust guide 40 is increased. Can be absorbed and the assembly is easy.

A support bracket 48 is fixed to the upper portion of the front wall surface 17a of the crankcase cover 17, and a generator 47 is attached to the support bracket 48 and an output shaft 47.
It is arranged with a facing upward and in parallel with the crankshaft 16. The driven pulley 47b mounted on the output shaft 47a of the generator 47 is connected to the drive pulley 51 mounted on the upper end of the crankshaft 16 by the transmission belt 50. The generator 47 is rotatable with respect to the support bracket 48 about the left side bolt 49, so that the extension of the belt 50 can be absorbed and the tension can be adjusted.

On the lower portion of the front wall surface 17a of the crankcase cover 17, a flange portion 17b is formed so as to bulge toward the front side in the form of an overhang.
A starter motor 52 is mounted on 7b with the output gear (pinion gear) 52a facing downward and in parallel with the crankshaft 16. The output gear 52a of the starter motor 52 meshes with a ring gear 53a formed on the outer circumference of the flywheel 53. The flywheel 53 is connected and fixed to the lower end of the crankshaft 16.

Reference numeral 52b is the starter motor 52.
Is a motor for moving a pinion gear, which raises the pinion gear 52a when the engine is started.

The lower end surface of the cylinder block 12 is formed with a flange portion 12h which forms a connection mating surface with the flange portion 17b of the crankcase cover 17.
The exhaust guide 40 is connected to the connection mating surface. An oil pan 41 and the above-described upper case 9 are connected to the lower mating surface of the exhaust guide 40, and the outer case 9 surrounds the outside of the oil pan 41.

The exhaust guide 40 introduces the exhaust gas into the muffler 65 and the outboard motor 1 into the hull 2
The upper guide 40a and the lower guide 40b are vertically divided into two parts. A support arm 82 is fixed to a mount member 81 bolted to the lower guide 40b, and the support arm 82 is supported by a clamp bracket 3 fixed to the hull 2 side.

Further, the exhaust guide 40 is provided on the vertical wall 4
A pump chamber (wheel chamber) C and an oil drop chamber D are separated by 0d. Furthermore, the lower guide 40 described above
The rear part of b is extended rearward from the upper guide part 40a, and a space is formed between the extended part and the cylinder heads 18a and 18b. An exhaust gas expansion chamber 74 is formed at the rear end of the rear extension. The expansion chamber 74 is a muffler chamber in the idle exhaust system for stabilizing the idling operation by discharging the exhaust gas into the atmosphere during the idling operation, and the lower guide 40b.
The structure is such that the opening of the recess 40h formed in the above is covered with the lid 74a.

The upper end opening of the pump chamber C is closed by the flange portions 17a and 12h formed at the lower end portions of the cylinder block 12 and the crankcase cover 17, so that water does not enter the pump chamber C. It is a closed space.

The flywheel 53 is in the pump chamber C.
A drive shaft 54 that is housed inside and that transmits engine rotation to the above-described screw 7 is connected to the flywheel 53 via a joint rod 55. The drive shaft 54
The crankshaft 16 and the crankshaft 16 constitute a linear output shaft. An oil pump 56 for pumping lubricating oil is disposed in the joint rod 55 portion of the drive shaft 54, that is, the portion between the lowermost journal portion 16a and the oil pan 41 arranged below the journal portion 16a. . The oil pump 56 includes the lateral wall 40c of the upper guide 40a and the lid member 5
An outer ring 58 is fixedly arranged in the pump case formed by 7 so as to be coaxial with the drive shaft 54, and is formed integrally with the outer ring 58 so as to be eccentric to the outer periphery of the joint rod 55. It is a trochoid pump which is adapted to rotate 55a. This trochoid pump 56
Is disposed in the closed pump chamber C, which prevents water from entering the pump.

The oil pump 56 can be provided below the lowermost journal portion 16a of the crankshaft 16, and such an oil pump arrangement structure has a flywheel provided at the upper end of the crankshaft. It can also be applied to other types of engines.

When the pump chamber C is hermetically sealed, there is a concern that the rotation of the flywheel 53 raises the air temperature and raises the internal pressure, and the flywheel 53 has a rotational resistance. Therefore, in order to avoid this, the air diffusing pipe 66 is provided so as to connect the atmosphere and the pump chamber C. Further, in order to prevent the invasion of water from the air diffuser 66, the air diffuser 66 has a shape extending upward and an upper end bent downward. Further, a drain hose 67 is attached to the pump chamber C so that when water enters, it can be drained.

The suction port 56a of the oil pump 56 is connected to the oil pan 41 by a suction passage 60, and the discharge port 56b is attached to the rear wall of the upper guide 40a of the exhaust guide 40 by the discharge passage 61. The oil filter 62 is communicatively connected. The oil filter 62 is arranged by utilizing the above-mentioned space created by extending the lower guide 40b of the exhaust guide 40 rearward.

The suction passage 60 is provided in the oil pan 41.
A suction pipe 60a arranged inside, a vertical hole 60b formed in the lower and upper guides 40b, 40a, and a horizontal hole 60c formed between the horizontal wall 40c and the lid member 57.
It is composed by. An oil strainer 83 made of wire mesh or the like is attached to the suction port of the suction pipe 60a.

The discharge passage 61 has a horizontal hole 61a formed between the horizontal wall 40c and the lid member 57, and the vertical wall 40.
It is constituted by a U-shaped hole 61b penetrating d and a horizontal cut hole 61c that crosses the oil drop chamber D. Where U
The bottom portion of the character hole 61b has the upper and lower guides 40a,
It is recessed on the mating surface of 40b. That is, the U-shaped hole 61 can be easily formed by dividing the exhaust guide 40 into upper and lower parts. Reference numeral 82 is a relief valve for avoiding an abnormal increase in the hydraulic pressure in the discharge passage 61.

The supply path 63 from the outlet of the oil filter 62 is mainly connected to the crankshaft lubrication system for supplying lubricating oil to the journal portion 16a of the crankshaft 16, the journals of the camshafts 21a and 21b, and the cam sliding surface. It is composed of a camshaft lubricating system for supplying lubricating oil, and both lubricating systems are arranged in series.

The crankshaft lubrication system includes the discharge passage 6
1, a horizontal cut hole 63a extending in parallel with the horizontal cut hole 61c, a vertical hole 63b extending upward in the vertical wall 40d, and a main gallery portion (crankshaft oil) extending further in the V bank bottom wall of the cylinder block 12 to the upper end. Supply passage) 63c. A branch hole 63d from the main gear portion 63c to the crank journal portion 16a branches from a higher place than the journal portion 16b and reaches the journal bearing portion 16d after being inclined obliquely downward. That is, the branch hole 63
d is an oil sump.

The camshaft lubrication system includes a block hole 63e formed in the upper end surface of the cylinder block 12 so as to branch from the upper end of the main gear portion 63b to the left and right, and subsequently to the camshaft bearing portion. Head holes 63 formed in the upper end surfaces of the cylinder heads 18a and 18b so as to communicate with the
f and the block hole 63e and the head hole 63f are camshaft oil supply passages. The head hole 63f communicates with an oil hole 21c formed in the shaft center of each cam shaft 21a, 21b.
Communicates with the camshaft bearing and the sliding surface of the cam nose.

The lubricating oil supplied to the upper end of the oil hole 21c through the block hole 63e and the head hole 63f flows down through the oil hole 21c and flows through the supply hole formed at a position corresponding to the cam shaft bearing portion. Through the camshaft bearing,
Lubricate the sliding surface of the cam nose.

The recovery passage 64 for recovering the lubricating oil supplied to the above parts to the oil pan 41 is constructed as follows. The recovery path of the lubricating oil supplied to the crankshaft journal bearing 16d and dropped into each crank chamber E through the gap between the bearing 16d and the journal portion 16a is
A lateral hole (recovery hole) 64a formed so as to communicate with the V bank space A in a portion (a portion near the center) of the crank recess 12e close to the main gear portion 63c, the V bank space A, and a return opening 63g. And the oil drop chamber D of the exhaust guide 40. Further, the crank recesses 12e are formed in a vertical hole 64b (FIGS.
(See) also communicates with the return opening 63g.

The recovery path of the lubricating oil supplied to the sliding surface between the cam shaft journal portion and the bearing portion or the sliding surface of the cam nose is connected to the bottom portions of the cam chambers F and F so that the lower end portions of the cylinder heads 18a and 18b can communicate with each other. A horizontal hole 64c formed in the cylinder axial direction and the cylinder block 12 so as to communicate with the horizontal hole 64c.
Each of the cylinder portions 12a and 12b has a lateral hole 64d formed in the cylinder-side mating surface on the head side, the opening 63g, and a path passing through the oil drop chamber D.

The cooling water system of the outboard motor 1 is constructed as follows. A cooling pipe 68 connected to a discharge port of a cooling water pump (not shown) disposed at the lower end of the drive shaft 54 is extended upward between the drive shaft 54 and the muffler 65 to extend the oil. It is connected to a cooling water passage 69 formed at the bottom of the pan 41, and is branched into left and right cylinder parts by branch passages 69a and 69a formed in a V shape in plan view, and each branch passage 69a is connected to an oil pan. The water cooling jackets J of the left and right exhaust manifolds 39 are communicatively connected to each other through vertical holes 41b formed in the vertical direction in 41 and a communication hole 40f formed in the lower guide 40b.

The upper end of the water cooling jacket J of each exhaust manifold 39 is connected to the lower end of the water cooling jacket of the left and right cylinders 12a, 12b of the cylinder block 12 via the cooling hose 70 and the pressure valve 71. 12i (see FIG. 20). The cooling water supplied to the cylinder parts 12a and 12b is the water cooling jacket of each cylinder part and each cylinder head 18
Passing through the water cooling jackets a and 18b, each cylinder part 12
It reaches the upper end of the water cooling jackets a and 12b.

The upper end of the water cooling jacket of each cylinder is connected to each return hole 40g of the upper guide 40a through a thermo valve 72 and a return hose 73, and each return hole 40g is connected to the lower guide 40b. Exhaust expansion chamber 40h
Connected to the drop hole 74b of the lid 74a of FIG.
Lead to. The cooling water led to the chamber 41n is supplied to the oil pan 4
From the first opening 41j to the exhaust pipe insertion hole 41h of the oil pan 41, it falls between the rear portion of the oil pan 41 and the upper case 9. Then, the muffler 65 falls and flows downward through the opening 65 a formed between the exhaust pipes 42, 42 in the upper case 9.

As described above, according to the in-engine gas discharge device of the outboard motor 1, the vertically arranged crankshaft 16,
Crankshaft sprockets 16b of the camshafts 21a, 21b,
In the case of a vertically installed engine, which is a chain chamber B that houses a timing chain 33a that connects the cam sprockets 32a and 32b, a discharge hole 37b is formed in a chain cover 37 that constitutes the ceiling wall of the chamber located at the highest position. Since the exhaust hose 37c is connected to the intake system, the gas in the engine can be sucked into the intake system and reliably discharged. Moreover, since the discharge hole 37b is formed in the bulging portion 37a which is bulged upward in order to avoid the interference with the cam shaft, the bulging portion 37a functions as a discharging chamber. There is no need to form a dedicated discharge chamber.

Further, in this case, since the chain chamber B communicates with both the crank chamber E and the cam chamber F, the gas containing blow-by gas and oil mist in the crank chamber E, and the oil mist in the cam chamber F. Both of the gases including the ascend toward the chamber B and are sucked and discharged from the discharge hole 37b to the intake path through the discharge hose 37c.

Further, each cylinder portion 1 of the chain cover 37
Since the discharge holes are formed in the portions of 2a and 12b facing the cam shaft, the cylinder portions 12a and
The gas in the engine from the cam chamber 12b can be reliably discharged.

The position of the discharge hole 37b is not limited to the position facing the cam shaft, and may be any position of the chain cover 37 forming the top wall of the chain chamber B.

Further, this in-engine gas discharging device is not limited to the V-type engine, but can be applied to an in-line engine having one cylinder portion.

Here, when the in-engine gas exhaust hole is formed in the chain chamber B as in the present in-engine gas exhaust device, the lubricating oil scattered from the timing chain is exhausted to the outside of the engine, and the lubricating oil exhaust amount increases. There is a concern that
In the outboard motor 1, since the oil separator function of separating the lubricating oil component in the gas in the engine is added to the inside of the chain chamber B, the discharge of the lubricating oil is suppressed.

Further, according to the lubricating oil supply apparatus for the outboard motor 1, the drive shaft 54 connected to the lower end of the crankshaft 16 via the flywheel 53 is arranged below the flywheel 53 and below. Since the oil pump 56 is coaxially attached to the portion between the oil pan 41 and the oil pan 41, the oil pump 56 is directly connected to the crankshaft, and is arranged parallel to the crankshaft so as to be driven via a gear or the like. The structure is much simpler than that of the above-mentioned one, and the space for disposing the oil pump is small, so that the downsizing which is particularly required for the outboard motor can be achieved. Further, since the oil pump 56 is driven at the same rotation speed as the engine rotation speed, it is easy to secure the oil amount and the oil pressure.

The oil pump 56 is replaced by the flywheel 5
3 is located between the oil pan 41 and the oil pan 41 and immediately above the oil pan 41, the suction head from the oil pump 56 to the oil level in the oil pan 41 can be small. It is easy to secure the oil amount and oil pressure, and the pump can be downsized.

Furthermore, the drive shaft 54 is vertically divided in the vicinity of the flywheel 53, and the rotary body of the oil pump 56 is attached to the outer peripheral surface of the joint rod (connection joint) 55 which is one of the divided bodies. Since the inner rotor 55a is machined and formed, the joint rod 55 is easy to handle at the time of machining due to the short length of the joint rod 55, and the machining work is easier than the case of machining the pump rotor on one drive shaft. .

In the outboard motor 1, the oil pan 41
Since the oil pump 56 is disposed between the mount member 81 fixed near the ship and the flywheel 53, the support arm 82 extends from the mount member 81 toward the hull side, so that the lower part of the outboard motor. Even if the splash generated in step 2 is scattered upward, the support arm 82 interferes with the oil pump 56 above the mount member. A large diameter flywheel 53 is provided above the oil pump 56.
Since it is provided, it becomes an obstacle and splashes applied from above are less likely to be applied to the oil pump 56. Therefore, entry of water into the oil pump 56 is reliably prevented.

Further, since the oil pump 56 is housed and arranged in the pump chamber (wheel chamber) C formed by the exhaust guide 40, the cylinder block 12 and the crankcase cover 17 to prevent the intrusion of water from the outside, Oil pump 5 especially required for outboard motors used at sea
The function of preventing water from entering 6 can be improved.

Further, in the outboard motor 1, since the lubricating oil suction passage 60 and the lubricating oil return passage (oil drop hole D) are formed in the exhaust guide 40 as a separate member formed separately from the cylinder block. For example, the passage can be formed more easily than when the passage is formed in the cylinder block 12. Further, in this case, since the exhaust guide 40 is divided into upper and lower halves and a part of the oil passage (the bottom of the U-shaped hole 61b) is formed between the divided surfaces, the oil passage can be formed more easily.

The lubricating oil supply device is not limited to the V-type engine, but can be applied to an in-line engine having one cylinder.

According to the oil filter arrangement structure of the outboard motor 1, a discharge passage 61 from the oil pump 56 to the engine is formed in the exhaust guide 40 connected to the lower ends of the cylinder block 12 and the crankcase cover 17, and Since the oil filter 62 is attached to the rear wall of the exhaust guide 40, it is possible to dispose the oil filter 62 in a space below the cylinder heads 18a and 18b and behind the rear wall of the exhaust guide in a side view. As compared with the case where the oil filter is arranged on the side wall of the cylinder block, for example, the width of the outboard motor can be prevented from increasing and the downsizing that is particularly required for the outboard motor can be secured. In this case, since the oil filter 62 is arranged below the center of the V bank in plan view, it is possible to more reliably prevent the outboard motor width from increasing.

Further, an oil pump 56 is arranged in the exhaust guide 40, and a suction passage 60 from the oil pan 41 to the oil pump 56 is provided in the exhaust guide 40.
Since the discharge passage 61 from the oil pump 56 to the oil filter 62 is formed, it is possible to avoid the problem that the outboard motor width is increased due to the arrangement of the oil pump.

According to the lubricating oil supply / recovery structure of the outboard motor 1, the oil supply passage from the oil pump 56 disposed between the flywheel 53 and the oil pan 41 to the lubricated portion such as the crankshaft journal portion. Also, since the flywheel portions 63b, D of the oil return passage from the lubricated portion to the oil pan 41 are formed so as to pass outside the outer periphery of the flywheel 53 when viewed in the crankshaft direction, the lubricating oil drops in particular. The flywheel 53 does not become a resistance in the recovery, and the recovery of the lubricating oil becomes easy.

A main gear portion (crankshaft oil supply passage) 63c for supplying lubricating oil from the oil pump 56 to the crankshaft journal portion 16a is provided in the bottom wall of the V bank of the cylinder block 12 substantially in parallel with the crankshaft 16. The V bank space A formed by connecting the inner walls of the V banks of the cylinder portions 12a and 12b to each other with the connecting wall 12g is used to form the lubricating oil from the crankshaft journal portion and the camshaft journal portion in the oil pan 41. Since the oil return passage for returning is used, in the V-type vertical engine, the relatively unused portion of the V bank bottom wall and the V bank space can be utilized, and therefore the supply passage and the return passage are formed in a linear shape and a large diameter. Therefore, it becomes easy to secure the amount of oil supply and the oil pressure, and the recovery resistance becomes smooth.

Further, since the branch hole 63d from the main gear portion 63c to each journal portion 16a is formed in an inclined shape so that the journal portion side becomes lower, the branch hole 63d functions as an oil sump. Therefore, when the engine is restarted, the journal 16a is lubricated by the lubricating oil in the oil sump, so that the lubricity at the time of starting can be secured.

Further, a lateral hole 64a (recovery hole) for collecting the lubricating oil from the crankshaft journal 16a into the V bank space A (oil return passage) connects the crank chamber E and the V bank space A. Since it is formed as described above, the amount of lubricating oil accumulated in the crank chamber can be reduced. Further, in this case, the cylinders (cylinder bores) 12d, 12 that are arranged offset
Since the space between d is used, a space for disposing the lateral hole 64a can be secured.

Since the camshaft oil supply passages 63e and 63f communicating from the upper end of the main gear portion (crankshaft oil supply passage) 63c to the bearing portion of the camshaft are formed in a branched manner, that is, the crankshaft oil supply passage is provided with a cam. Since the shaft oil supply passages are connected in series, the amount of oil supplied to the crankshaft journal can be increased more than the amount of oil supplied to the camshaft journal, and the required amount of each journal can be easily met.

In the above lubricating oil supply / recovery structure, the lubricating oil is made to flow downward from the upper end of the cam shaft, but conversely, the lubricating oil may be made to flow upward from the lower end of the cam shaft. In addition, the invention is not limited to the V-type engine, but can be applied to an in-line engine having only one cylinder portion.

It is also possible to branch the camshaft oil supply passage from the lower part of the crankshaft oil supply passage instead of the above-mentioned series connection. However, in this case, the amount of oil supplied to the crankshaft journal portion may be insufficient. There is. When such a configuration is adopted, an orifice for adjusting the amount of oil is arranged near the branch portion of the camshaft oil supply passage.

According to the exhaust system of the outboard motor 1, the left,
The upstream end of the exhaust manifold 39 is connected to the outer wall of the V bank of the right cylinder heads 18a and 18b, and the exhaust manifold 39 is connected to the space between the cylinder head and the exhaust guide 40 from the outside of the cylinder head by V. Since it is extended to the center of the bank and connected to the exhaust passage 40e of the exhaust guide 40 at the center of the V bank, the exhaust pipe arrangement using the lower space of the V bank, which is likely to be an empty space in the case of a V-type vertical engine. Installation is possible, and in the case of an outboard motor equipped with a 4-cycle V-type engine,
It is possible to avoid the expansion of the outboard motor width due to the arrangement of the exhaust pipe, and it is possible to cope with the downsizing that is particularly required in the case of the outboard motor.

The arrangement of the exhaust pipe in the above exhaust device is applicable not only to the V-type engine but also to the in-line engine.

Further, according to the auxiliary equipment arrangement structure of the outboard motor 1, when the V type engine is arranged vertically with the cylinder heads 18a and 18b facing the rear side of the hull, the V type engine is inserted with the crankshaft 16 interposed therebetween. Since the auxiliary machines such as the starter motor 52 and the generator 47 are arranged in the front space G opposite to the bank space, the rearward displacement of the center of gravity due to the cylinder head being located on the rear side of the hull is arranged on the front side of the auxiliary machines. The weight balance can be improved.

In particular, in the case of a V-type engine, since the widths of the left and right cylinder heads are wide, it is not preferable to arrange auxiliary equipment on the side of the engine because the outboard motor width becomes large. Therefore, arranging accessories in the front space G is advantageous not only in terms of weight balance but also in securing space.

Further, in the outboard motor 1, since the auxiliary equipments are arranged in the front space G, the weight balance in the longitudinal direction of the hull is obtained, and the starter motor 52 is provided at the lower part of the front space G and the generator 47 is provided at the upper part. The weight distribution in the vertical direction can also be obtained because the weights are distributed. Moreover, in this case, the flywheel 53 having the ring gear 53a at the lower end of the crankshaft, the drive pulley 51 at the upper end, the starter motor 52 at the lower part of the front space G, and the generator 47 at the upper part are arranged. 52 drive gear 5
2a can be directly meshed with the ring gear 53a,
Further, the drive pulley 51 is connected to the driven pulley 47 by the transmission belt 50.
The power transmission mechanism is extremely simple, such as simply connecting to b.

Further, in the case of a 4-cycle V-type engine, when the turning center line is set to the front side of the crankshaft, the state becomes further heavy on the rear side. However, in the outboard motor 1, the turning center line 6 is cranked. When the auxiliary machines are located on the front side of the shaft 16, the auxiliary machines are arranged on the front side of the turning center line 6,
The above-mentioned weight balance deviation correcting action becomes more effective.

The accessory arrangement structure described above can be applied not only to the V-type engine but also to the in-line engine.

According to the valve operating system of the outboard motor 1, a large-diameter cam sprocket is attached to the intake camshaft 21a on the inner side of the V bank for the left cylinder portion 12a, and to the V bank for the right cylinder portion 12b. Outer exhaust camshaft 21
Since it is mounted on b, it is possible to prevent the engine width from increasing due to the cam sprocket of the valve mechanism without increasing the V bank angle more than necessary.

That is, since the cam sprocket has a large diameter, providing a cam sprocket on both the intake and exhaust camshafts of each cylinder section increases the valve grip angle and the overall width of the engine. Further, when the cam sprocket is provided only on one cam shaft of each cylinder portion, if both cylinder portions are provided outside the V bank, the engine width also becomes large, while if both cylinder portions are provided inside the V bank, the V bank is provided. There is concern that the angle may become larger than necessary. In the outboard motor 1, when the cam sprocket is provided only on one cam shaft of each cylinder portion, the intake cam shaft 21a inside the V bank of the left cylinder portion 12a is
Regarding the right cylinder portion 12b, cam sprockets 32a, 32 are attached to the exhaust cam shaft 21b outside the V bank, respectively.
Since b is provided, the above problems can be avoided.

Further, in the outboard motor 1, since the large-diameter cam sprocket is not mounted on the outside of the V banks of both cylinder parts, only one cylinder part is arranged on the outside of the V bank, the width of the entire engine is more than necessary. It never grows. On the side of the cam shaft on which the cam sprocket is not mounted, the cross-sectional dimension of the upper cowling 11b can be made smaller from the mating surface 11a to the upper side without difficulty. This has the effect of avoiding an increase in size. By the way, if the engine width becomes large due to the arrangement of the cam sprockets, the size of the mating surface 11a of the upper cowling 11b also needs to be made that large, and the cowling 11 eventually becomes large.

The oil in the cam chamber F is agitated by the intermediate chain 33b while flowing down toward the oil outlet 64c while lubricating the cam bearing and the like. Since the oil is dropped below the chamber B, even if the oil dropped by the intermediate sprocket 32c or the intermediate chain 33b is agitated, it is agitated because the cam chain chamber B is located above the intermediate chain 33b. Almost no oil flows into the crank chamber E through the cam chain chamber B, so that the oil in the cam chamber F can be efficiently collected.

The valve operating device is not limited to the V-type engine, but can be applied to the in-line engine.

According to the intake device of the outboard motor 1, the left and right surge tanks 23a and 23b extending substantially parallel to the crankshaft are provided.
The head covers 19a of the cylinder parts 12a, 12b,
The left and right surge tanks 23a and 23b are symmetrically arranged along the line 19b, and the left and right surge tanks 23a and 23b are symmetrically branched.
Since they are merged into the merge passage 23e via d and 23d,
The amount of air distributed to each cylinder can be made uniform.

Further, the left and right surge tanks 23a, 2a, 2b
Since 3b and the intake port of each cylinder are connected by the intake manifold 23c having the same length, the left and right surge tanks 23
Since a and 23b have a large capacity, it is only the intake manifold of the same length that affects the substantial intake pipe length up to the intake port 18e of each cylinder, and therefore the substantial intake air to each cylinder is The pipe length can be the same for all cylinders.

Furthermore, the outside opening of the confluence passage 23e is provided with the outside air introduction port 1 formed in the upper portion of the cowling 11.
Since it is located in the vicinity of 1d, that is, at the upper end, it is possible to introduce the air in the upper portion of the cowling that is not affected by heat from the engine or the like, and to avoid the rise in intake air temperature. Further, since the outer opening is located at the highest position, it is possible to prevent jumping water from the sea surface from entering the engine.

Further, the left and right surge tanks 23a, 2
Since the 3d's are connected by the support plate 77 and the control unit 78 is attached thereto, the engine parts can be arranged by utilizing the V bank space.

Furthermore, since the throttle body 28 is attached to the extension portion 24c which extends upward from the intake plate 24 to which the fuel injection valve 26 is attached, a dedicated throttle body attachment bracket is not required, and the throttle body attachment structure is Can be simplified.

In the above outboard motor 1, a case has been described in which a pair of left and right surge tanks are provided. However, as shown in FIG. 22, a surge tank 90 common to the left and right cylinders is arranged in the center of the V bank. You can set it up. In this case, the structure is simplified such that the intake manifold portion 91 connecting the surge tank 90 and the intake port of each cylinder can be linear.

According to the cooling structure of the outboard motor 1, the cooling water passage 69 is passed through the bottom of the oil pan 41 disposed below the cylinder block 12 and is connected to the cooling jacket J of the exhaust pipe 39 to cool the exhaust pipe. Since the jacket J is connected to the engine cooling jacket K, the oil pan 41 and the exhaust pipe 39 can be provided without a separate cooling water passage by a simple structure in which the position of the cooling water passage up to the engine cooling jacket is simply devised. Cooling can be done.

Further, the cooling water channel 69 is branched to the left and right at the bottom of the oil pan 41, and the branched water channels 69a and 69a are connected to the engine cooling jacket K from the exhaust cooling jackets J for the cylinder portions. It is possible to improve the cooling balance of each cylinder by forming an independent cooling system for each cylinder.

Further, a thermostat valve 72 independent of each cooling system is provided on the outlet side of the engine cooling jacket K of each cooling system.
Since the cooling system is provided, independent temperature control can be performed for each cooling system, and the cooling balance of each cylinder portion can be further improved.

Furthermore, since the cooling water passing through the engine cooling jacket K is configured to drop into the water through the periphery of the oil pan 61 and the periphery of the muffler 65, the cooling water on the way back to the water is effectively used. Thus, the oil pan 41 and the muffler 65 can be effectively cooled.

The cooling structure described above is not limited to the V-type engine, but can be applied to an in-line engine having one cylinder.

According to the oil pan arrangement structure of the outboard motor 1, the exhaust manifolds 39, 39 from the cylinder portions 12a, 12b are vertically inserted into the rear portion of the exhaust guide 40 at a predetermined interval in the boat width direction. Connect and connect the bulging portion 41i of the oil pan 41 to both the exhaust manifolds 3
Since it is located between 9 and 39, in the case of a V-type vertical engine, the oil pan volume can be secured by utilizing the dead space generated between the left and right exhaust pipes.

Since the drain plug 80 is provided at the lower end of the bulging portion 41i and the oil level gauge 79 is inserted from the upper end of the bulging portion 41i, waste oil can be discharged from the lower portion of the bulging portion 41i arranged in the dead space. In addition, it is possible to refuel from the top and improve the inspection workability such as replenishment and replacement of lubricating oil.

Cooling water return ports 41j and openings 65a for returning the cooling water to the periphery of the oil pan 41 and the muffler 65 are provided on both sides of the bulging portion 41i of the exhaust guide 40.
The oil pan 41 and the muffler 65 can be cooled by the return water by utilizing the dead space described above.

Further, since the exhaust expansion chamber 74 of the idle exhaust system is provided at the rear portion of the exhaust guide 40, the exhaust expansion chamber installation space can be secured by utilizing the dead space. Further, in this case, since the concave portion 40h is formed on the upper surface of the lower guide 40b and the lid 74a is covered therewith, the concave portion can be formed by casting and salt accumulation can be avoided.

According to the lubricating oil replenishing structure of the outboard motor 1, the lubricating oil is placed vertically and the crankshaft journal portion 1 at the upper end of the engine is placed.
An oil return passage (V bank space A, oil drop hole D) for returning the lubricating oil that has lubricated 6a to the oil pan 41 is formed substantially parallel to the crankshaft 16, and lubricating oil is injected at the upper end of the oil return passage. An oil level gauge 7 having a length that forms an inlet 37e and reaches the inlet pan 41 at the inlet 37e.
Since 9'is attached, the oil inlet and the oil level gauge insertion port are shared, and the workability can be improved by the amount that the inlet opening / closing and the level gauge attachment / detachment work are performed at the same time.

The oil return passage is provided in the crankshaft 1
Since it is formed substantially parallel to 6 and communicates directly with the oil pan 21, the lubricating oil replenished from the inlet 37e immediately drops into the oil pan 41, and the oil level in the oil pan 41 rises. The waiting time until it becomes constant is greatly shortened, and workability can be improved also from this point.

According to the lubricating oil recovery structure of the outboard motor 1, the crankcase cover 17 and the baffle plate (partition plate) are provided.
A space between the upper end of the rising passage E'and the upper end of the rising passage E'communicates with a chain chamber B having an oil separator function formed at the upper end of the engine and the lower end of the crank chamber. From the oil pan 41
Since the oil return passage H communicating with the partition plate 7 is formed, the lubricating oil discharged from the crankshaft journal portion 16a is
5 falls along the inner surface of 5 and is collected in the oil pan 41, and the oil mist gas rises from the pores of the partition plate 75 to the chain chamber B through the ascending passage E ′, where the oil mist is removed from the air. It is separated, falls along the crankcase cover 17 or the partition plate 75, and is collected in the oil pan, so that the lubricating oil recovery efficiency can be improved.

The lubricating oil replenishing structure and the lubricating oil collecting structure are not limited to the V-type engine, but can be applied to an in-line engine having only one cylinder portion.

FIG. 23 shows the cam sprockets 32a, 32.
This is a modification of the arrangement structure of b. In this example, both of the cam sprockets 32a and 32b are attached to the intake cam shafts 21a and 21a located inside the V bank. As a result, the amount of outward protrusion of each of the left and right cylinder portions 12a and 12b is reduced, and the lateral width of the cowling 11 can be reduced.

[0114]

According to the exhaust system for a four-cycle outboard motor of the first aspect of the present invention, the upstream end of the exhaust pipe is connected to the exhaust port of the cylinder head which is open at one side in the ship width direction, and the exhaust gas is exhausted. The pipe extends from the one side of the cylinder head to the center side in the engine width direction through the space between the cylinder head and the exhaust guide, and is connected to the exhaust passage of the exhaust guide at the engine center side. The lower side of the cylinder head extends toward the center side in the engine width direction. Therefore, it is possible to avoid an increase in the width dimension of the lower portion of the cylinder head of the outboard motor, and it is possible to meet the demand for downsizing of the outboard motor.

According to the second aspect of the present invention, in the case of the V-type vertically installed engine, the exhaust pipe for each cylinder portion is passed from the outside of each cylinder head to the center side of the V bank through between the cylinder head and the exhaust guide. Since it is extended to the V type, it is possible to arrange the exhaust pipe by utilizing the lower space of the V bank, which tends to be an empty space in the case of the V type vertical engine, and it is possible to cope with the downsizing in the case of an outboard motor equipped with the V type engine. effective.

[Brief description of drawings]

FIG. 1 is a left side view of an outboard motor according to an embodiment of the present invention.

FIG. 2 is a plan view of the outboard motor.

FIG. 3 is a plan view of the outboard motor.

FIG. 4 is a plan view of the outboard motor.

FIG. 5 is a plan view of the outboard motor with a chain cover removed.

FIG. 6 is a plan view showing an oil passage at an upper end portion of the outboard motor.

FIG. 7 is a cross-sectional plan view of the outboard motor.

FIG. 8 is a cross-sectional plan view of a starter motor portion of the outboard motor.

FIG. 9 is a partial cross-sectional rear view of the intake system of the outboard motor.

FIG. 10 is a rear view showing a camshaft arrangement state of the outboard motor.

FIG. 11 is a left side view of a cross section of an intake system of the outboard motor.

FIG. 12 is a cross-sectional left side view of the outboard motor.

FIG. 13 is a view taken along line XIII-XIII in FIG.

FIG. 14 is a view for explaining the flow of lubricating oil and cooling water of the outboard motor.

15 is a sectional view taken along line XV-XV in FIG.

16 is a sectional view taken along line XVI-XVI of FIG.

FIG. 17 is a view taken along line XVII-XVII of FIG.

FIG. 18 is a sectional left side view of an exhaust guide portion of the exhaust system of the outboard motor.

FIG. 19 is a sectional left side view of an oil pan and a muffler portion of the outboard motor.

FIG. 20 is a sectional left side view of an exhaust manifold portion of the exhaust system of the outboard motor.

FIG. 21 is a sectional rear view of a joint portion of the exhaust system of the outboard motor.

FIG. 22 is a cross-sectional plan view showing a modified example of the surge tank portion of the intake device for the outboard motor.

FIG. 23 is a plan view showing a modified example of the arrangement of the cam sprocket of the outboard motor.

[Explanation of symbols]

1 outboard motor 10 4-cycle V-type engine 16 crankshaft 18a, 18b cylinder head 18e Exhaust port 39 Exhaust manifold (exhaust pipe) 40 Exhaust guide 40e exhaust passage 65 muffler

Claims (2)

(57) [Claims] 1. An exhaust system for a four-cycle outboard motor, in which a four-cycle engine is vertically arranged so that a crankshaft is substantially vertical when traveling, and an exhaust guide for introducing exhaust gas into a muffler is provided at a lower end of the engine. The exhaust pipe is connected to the cylinder head so that a space is formed between the cylinder head and the exhaust port, which is open at one side in the ship width direction of the cylinder head, and the exhaust pipe is connected from the one side of the cylinder head. Extending to the center side in the engine width direction through the space between the cylinder head and the exhaust guide,
An exhaust system for a four-cycle outboard motor, wherein the exhaust pipe is connected to an exhaust passage communicating with the muffler of the exhaust guide on the engine center side. 2. The engine according to claim 1, wherein the engine is a V-type engine in which cylinders in which cylinders are formed are arranged so as to form a V-shape (V bank), and the exhaust pipe is provided in each cylinder. The exhaust pipe extends from the outside of the cylinder head to the center of the V bank through the space between the cylinder head and the exhaust guide, and the exhaust pipes are connected to the exhaust passages of the exhaust guide at the center of the V bank. An exhaust system for a 4-cycle outboard motor.