JP2003104287A - Engine cover for outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rigid engine cover for an outboard motor. SOLUTION: In the outboard motor 1, an engine 2 arranged in an extension part 8a formed on an upper end part of a drive shaft housing 8 is covered by the box shaped engine cover 3 made of a synthetic resin. The engine cover 3 is constituted of two divided members, a lower cover 3a fixed on the outboard motor 1 side and covering a lower part of the engine 2, and a detachable upper cover 3b for covering an upper part of the engine 2. An aperture 21 is opened on a bottom surface of the lower cover 3a. A metal plate member 22 is fixed on the aperture 21, and the lower cover 3a and the metal plate member 22 are integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine cover for an outboard motor.

[0002]

2. Description of the Related Art In a small outboard motor, an engine is mounted on an upper portion of a drive shaft housing that also serves as a holder, and the periphery thereof is covered with a box-shaped engine cover. The engine cover is usually formed so that it can be divided into upper and lower parts, and it is roughly divided into two parts, a lower cover that is fixed to the outboard motor side and covers the lower part of the engine, and a removable upper cover that covers the upper part of the engine. ing.

Many materials for the engine cover are made of aluminum die cast, and many lower covers are directly fixed to the drive shaft housing.

[0004] In recent years, from the viewpoint of weight reduction and cost reduction, some engine covers are made of synthetic resin.

[0005]

However, since the lower cover made of synthetic resin lacks in rigidity, it has a problem that the assembling property is not good and the fixing to the engine becomes unsatisfactory.

Further, since the lower cover is made of synthetic resin, it is difficult to mount it on the high heat portion, and the sealing property for cooling water, lubricating oil, exhaust gas, etc. is low.

Conventionally, the rigidity of the lower cover has been increased by using a resin material having a higher rigidity or by increasing the wall thickness, but the increase in weight and cost is inevitable, and the lower cover has excellent heat resistance and sealability. Has no effect.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine cover for an outboard motor having high rigidity.

Another object of the present invention is to provide an engine cover for an outboard motor, which has improved heat resistance and sealability.

[0010]

In order to solve the above problems, an engine cover for an outboard motor according to the present invention has an extension portion formed at an upper end portion of a drive shaft housing as described in claim 1. In an outboard motor in which the periphery of the engine is covered with a box-shaped synthetic resin engine cover, the engine cover is fixed to the outboard motor side and covers a lower part of the lower part of the engine, and the upper part of the engine. And a detachable upper cover for covering the lower cover, the opening is opened in the bottom surface of the lower cover, and a metal plate member is fixed to the opening to fix the lower cover and the metal plate member. Are integrated.

In order to solve the above-mentioned problems, as described in claim 2, exhaust holes for exhaust gas, rising water holes and cooling water holes are formed in the metallic plate member. , The lower surface of the engine and the upper surface of the extension portion are fastened together and integrated with the metallic plate member interposed therebetween.

Further, in order to solve the above-mentioned problems,
As described in claim 3, a seal member is interposed between the lower surface of the engine and the upper surface of the metallic plate member and between the upper surface of the extension portion and the lower surface of the metallic plate member, respectively. .

Further, in order to solve the above-mentioned problems, as described in claim 4, the metallic plate member is a flat plate member.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a right side view showing an example of an outboard motor according to the present invention. As shown in FIG. 1, the outboard motor 1 has a vertical (vertical) engine 2, and its periphery is covered with a box-shaped engine cover 3. A steering handle 4 extends forward from a lower front portion (right side in the drawing) of the engine 2, and a throttle grip 5 for adjusting an engine output is provided at a tip thereof.

The engine cover 3 is made of, for example, a synthetic resin which is vertically separable. The engine cover 3 is fixed to the outboard motor 1 side, and includes a lower cover 3a for covering the lower periphery of the engine 2. , And a detachable upper cover 3b that covers the upper part of the engine 2 and is largely divided into two parts. On the other hand, a fuel tank 6 is arranged in a space in front of the engine 2 inside the engine cover 3. This fuel tank 6
The fuel filler port 6a extends upward, and the engine cover 3
It projects upward and is closed by the fuel cap 7.

A drive shaft housing 8 is provided below the lower cover 3a. An extension portion 8a is integrally formed on the upper end portion of the drive shaft housing 8, and the engine 2 is arranged above the extension portion 8a.
A gear case 9 is provided below the drive shaft housing 8.
Is provided. A propeller shaft 10 is rotatably supported inside the gear case 9, and a propeller 11 is provided at the rear end thereof.

A crankshaft 12 is vertically installed (vertical) in the engine 2 so as to be oriented substantially vertically. A drive shaft 13 connected to the lower end of the crank shaft 12 extends downward in the drive shaft housing 8, and the lower end of the drive shaft 13 is connected to the propeller shaft 10 via a bevel gear 14. Output of engine 2, namely crankshaft 12
Is transmitted to the propeller shaft 10 via the drive shaft 13 and the bevel gear 14 to rotate the propeller 11.

The upper part of the drive shaft housing 8 is integrated with the clamp bracket 15 and the swivel bracket 1
The clamp bracket 15 is rotatably supported by 5a, and is fixed to the transom 16a of the hull 16. That is, the outboard motor 1 is rotatably provided on the hull 16, and is configured to be able to steer the hull 16 by swinging the steering handle 4 in a horizontal direction to change the orientation of the entire outboard motor 1. It

FIG. 2 is a vertical sectional view of the engine 2 portion. As shown in FIGS. 1 and 2, the engine 2 used in the present embodiment is, for example, a 4-cycle single-cylinder engine provided with an OHV type valve mechanism 17, and the engine 2 is mainly located in front of the outboard motor 1 ( Crank cases 18a, 18 that are arranged on the right side in FIG. 1 and FIG.
b and the rear side of the crankcases 18a and 18b (see FIG. 1).
And a cylinder block 19 formed integrally with the upper part 18a of the crankcase and a cylinder head 20 arranged on the rear side (left side in FIGS. 1 and 2) of the cylinder block 19. Composed of and.

FIG. 3 is a plan view of the lower cover 3a.
The state where the engine 2 is removed is shown. 4 is a sectional view taken along the line IV-IV in FIG. Further, FIG. 5 is a bottom view of the engine 2, and FIG. 6 is a top view of the extension portion 8a. And FIG. 7 shows the lower cover 3a.
FIG.

As shown in FIGS. 3, 4 and 7, an opening 21 is opened at the center of the bottom surface of the lower cover 3a. The opening 21 is closed from the inside of the lower cover 3a by an engine support plate 22. Get off. The engine support plate 22 is, for example, a flat metal plate member having a thickness of about 3 mm, and is a plate member made of aluminum in the present embodiment. For example, the plurality of rivets 2 are used.
It is integrally fixed to the lower cover 3a by 3.

The lower surface of the engine 2 (the bottom surface of the lower portion 18b of the crankcase and the bottom surface of the cylinder head 20) and the upper surface of the extension portion 8a formed at the upper end of the drive shaft housing 8 are interposed between the engine support plate 22. Are sandwiched in between and fastened together by, for example, a plurality of bolts 24 to be integrated.

A shaft hole 25 is formed in the engine support plate 22, and the drive shaft 13 extends downward through the shaft hole 25. Further, an exhaust hole 26 for exhaust gas, a rising water hole 27 and a dropping water hole 28 for cooling water, which will be described later, are formed in the engine support plate 22, respectively.

As shown in FIG. 2, the lower part 18b of the crankcase also serves as an oil pan 29, and a predetermined amount of lubricating oil (not shown) is stored therein. Further, as shown in FIG. 5, a pump chamber 30 is formed in the bottom surface of the lower portion 18b of the crankcase, and an oil pump 31 is arranged inside thereof.

The cylinder block 19 is provided with a cylindrical cylinder 32 extending in a direction orthogonal to the crankshaft 12 in a side view toward the front-rear direction (left and right in FIGS. 1 and 2) of the outboard motor 1 and a cylinder head. A rear portion of the valve 20 is opened to form a valve operating chamber 33 for accommodating the valve operating mechanism 17 therein, and the valve operating chamber 33 is closed by a cylinder head cover 34. Also, the cylinder head 2
At 0, a combustion chamber 35 aligned with the cylinder 32 is formed. An ignition plug (not shown) is connected to the combustion chamber 35 from the outside.

A piston 36 is slidably inserted into the cylinder 32, and the piston 36 and the crankshaft 1
2 is connected to the cylinder 32 by a connecting rod 37.
The reciprocating movement of the piston 36 therein is converted into the rotational movement of the crankshaft 12. A flywheel / magnet device 38 for power generation and a rope / recoil type manual engine starting device 39 are provided at the upper end of the crankshaft 12.

An intake port 40 and an exhaust port 41 connected to the combustion chamber 35 are formed in the cylinder head 20.
An intake valve 42 and an exhaust valve 43 that open and close both ports 40 and 41 are provided in the cylinder head 20.

The exhaust port 41 extends downward in the cylinder head 20 toward the extension portion 8a, and from the exhaust hole 26 formed in the engine support plate 22 to the exhaust passage 44 formed in the extension portion 8a, the drive shaft housing 8 It is configured to discharge the exhaust gas to the outside of the machine through the inside. Further, a carburetor (not shown) that constitutes an intake device is arranged above the cylinder block 19, and its downstream side is connected to an intake port 40 that opens to the upper surface of the cylinder head 20 via an inlet pipe 45.

By the way, this engine 2 adopts a water cooling type engine cooling system, and the cooling water passage structure is as follows.

As shown in FIG. 1, a water intake port 46 is formed in the gear case 9, and the cooling water such as seawater and lake water taken in from the water intake port 46 is cooled by a water pump 47 driven by the drive shaft 13. Four
It is pressure-fed toward the engine 2 via 8.

A cooling water passage 49 is formed in the extension portion 8a by the partition wall 8b which is partitioned from the exhaust passage 44 and the engine support plate 22 which is interposed between the lower portion of the engine 2 and the cooling water passage 49. The downstream end of the cooling water pipe 48 is guided to. Also, this cooling water passage 49
Extend toward the bottom of the cylinder head 20.

On the other hand, a water jacket 50 is formed around the intake port 40 and the exhaust port 41 formed in the cylinder head 20. The water jacket 50 penetrates the cylinder head 20 in the vertical direction, and a cooling water inlet 51 is formed on the lower surface of the cylinder head 20 and a cooling water outlet (not shown) is formed on the upper surface of the cylinder head 20. The engine support plate 22 between the lower surface of the cylinder head 20 and the upper surface of the extension portion 8a.
A rising water hole 27 having substantially the same cross-sectional shape as that of the cooling water inlet 51 of the water jacket is formed therein, and the cooling water in the cooling water passage 49 is guided to the water jacket 50 via the rising water hole 27.

Combustion chamber 3 formed in cylinder head 20
A water jacket 52 is also formed on the periphery of 5, and the cooling water from the cooling water outlet of the cylinder head 20 is guided to the water jacket 52. In addition, the water jacket 53 also surrounds the cylinder 32 of the cylinder block 19.
The water jacket 53 is formed in the combustion chamber 35.
Is arranged at a position facing the water jacket 52.

Further, a drop water passage 53b (see FIG. 5) extends downward from the water jacket 53 around the cylinder 32, and the cooling water after cooling the engine 2 is dropped through the engine support plate 22. It is discharged from 28 to the exhaust passage 44 in the extension portion 8a. The cooling water discharged into the exhaust passage 44 is discharged to the outside of the machine through the drive shaft housing 8 together with the exhaust gas.

FIG. 8 is an enlarged view of the main part VIII surrounded by a circle in FIG. As shown in FIGS. 2 and 8, between the lower surface of the engine 2 (the bottom surface of the lower portion 18b of the crankcase and the bottom surface of the cylinder head 20) and the upper surface of the engine support plate 22, and between the upper surface of the extension portion 8a and the engine support plate. Sealing members such as gaskets 54 and 55 are provided between the lower surface and
The pump chamber 30, the exhaust passage 44, and the cooling water passage 49 are kept liquid-tight (airtight).

A space is provided between the bottom surface of the lower portion 18b of the crankcase and the upper gasket 54 to form an air layer 56, and the exhaust gas and cooling water passing through the extension portion 8a are dropped. It prevents the heat of water from being transferred to the lubricating oil in the oil pan 29.

On the other hand, as shown in FIGS. 2, 4 and 7, a main intake port 57 is formed on the bottom surface of the lower cover 3a, for example, in front of the opening 21. Further, in order to prevent the inside of the engine cover 3 from becoming a negative pressure state, for example, a plurality of auxiliary intake ports 58 are formed on the bottom surface of the lower cover 3a, for example, on both sides of the opening 21. Then, as shown in FIG. 3 and FIG. 9 which is a cross-sectional view taken along the line IX-IX of FIG. 3, a return portion 59 is provided on the peripheral portion of the engine support plate 22 so as to cover above the sub intake port 58. The return portion 59 prevents seawater and the like from entering the engine cover 3 through the auxiliary intake port 58.

Next, the operation of this embodiment will be described.

The lower cover 3a and the engine support plate 22 are integrally formed by fixing the opening 21 opened at the central portion of the bottom surface of the synthetic resin lower cover 3a so as to be closed by the engine support plate 22 which is a metallic plate member. As a result, it is possible to obtain sufficient rigidity while utilizing the weight reduction and cost reduction effects of the synthetic resin member.

Since the engine support plate 22 is provided with the exhaust hole 26 for exhaust gas, the rising water hole 27 and the dropping water hole 28 for the cooling water, the lower surface of the engine 2 with the engine support plate 22 interposed therebetween ( The bottom surface of the lower portion 18b of the crankcase and the bottom surface of the cylinder head 20) and the upper surface of the extension portion 8a formed at the upper end of the drive shaft housing 8 can be fastened together to be integrated. As a result, the number of parts and the number of assembling steps can be reduced as compared with the conventional mounting of the lower cover alone, and the assembling step is also simplified.

Further, between the lower surface of the engine 2 (the bottom surface of the lower portion 18b of the crankcase and the bottom surface of the cylinder head 20) and the upper surface of the engine support plate 22, and between the upper surface of the extension portion 8a and the engine support plate 2.
The seal member (gasket 54,
55), the pump chamber 30 and the exhaust passage 4
4 and the cooling water passage 49 can be enhanced in liquid tightness (airtightness), and a gap is provided between the bottom surface of the lower part 18b of the crankcase and the upper gasket 54 to form the air layer 56. The heat of the exhaust gas and the cooling water dropped through the extension portion 8a is prevented from being transferred to the lubricating oil in the oil pan 29.

If the engine support plate 22 is made of a flat plate-shaped metallic plate member, the processing becomes easy, the assembling property is improved, and the cost can be reduced.

[0044]

As described above, according to the engine cover of the outboard motor of the present invention, sufficient rigidity can be obtained as well as weight reduction and cost reduction.

Further, the number of parts and the number of assembling steps can be reduced and simplified.

Further, the liquid tightness (air tightness) of the exhaust, lubrication, cooling system and the like is improved.

[Brief description of drawings]

FIG. 1 is a right side view of an outboard motor showing an embodiment of an engine cover of the outboard motor according to the present invention.

FIG. 2 is a vertical sectional view of an engine portion.

FIG. 3 is a plan view of the lower cover with the engine removed.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a bottom view of the engine.

FIG. 6 is a top view of an extension portion.

FIG. 7 is a bottom view of the lower cover.

FIG. 8 is an enlarged view of a main part VIII surrounded by a circle in FIG.

9 is a sectional view taken along line IX-IX in FIG.

[Explanation of symbols]

1 outboard motor 2 engine 3 engine cover 3a Lower cover 3b upper cover 8 drive shaft housing 8a extension part 18a, 18b crankcase 20 cylinder head 21 opening 22 Engine support plate (metal plate member) 26 Exhaust gas exhaust holes 27 Rising water hole for cooling water 28 Cooling water drop hole 54,55 Gasket (seal member)

Claims (4)

[Claims] 1. An outboard motor having a box-shaped synthetic resin engine cover covering the periphery of an engine disposed in an extension formed at the upper end of a drive shaft housing, wherein the engine cover is fixed to the outboard motor side. The lower cover that covers the lower part of the engine and the detachable upper cover that covers the upper part of the engine are configured separately, and an opening is formed in the bottom surface of the lower cover. An engine cover for an outboard motor, wherein a plate member is fixed to the lower cover and the metallic plate member are integrated. 2. An exhaust gas exhaust hole, a rising water hole and a cooling water hole for cooling water are formed in the metallic plate member, and the metallic plate member is sandwiched between the exhaust plate and the lower surface of the engine and the extension. The engine cover for an outboard motor according to claim 1, wherein the upper surface of the part is fastened together and integrated. 3. The seal member according to claim 1, wherein a seal member is provided between the lower surface of the engine and the upper surface of the metallic plate member and between the upper surface of the extension portion and the lower surface of the metallic plate member. Engine cover for outboard motors. 4. The engine cover for an outboard motor according to claim 1, 2 or 3, wherein the metallic plate member is a flat plate member.