Preferred embodiments of the present invention will be described with reference to
Referring to
The outboard motor S has a transmission mechanism including a drive shaft 5 coaxially connected to a lower end part 18b of the crankshaft 18, a reversing mechanism held in the gear case, and a propeller. The power of the internal combustion engine E is transmitted from the crankshaft 18 through the drive shaft 5 and the reversing mechanism to the propeller.
A mounting device for mounting the outboard motor S on the stern of a hull has a swivel shaft 6 fixed to the mount case 1 and the extension case 2, a swivel case 7 supporting the swivel shaft 6 for turning thereon, a tilting shaft 8 supporting the swivel case 7 so as to be turnable in a vertical plane, and a bracket 9 holding the tilting shaft 8 and attached to the stern of the hull. The mounting device holds the outboard motor S so as to be turnable on the tilting shaft 8 in a vertical plane relative to the hull and so as to be turnable on the swivel shaft 6 in a horizontal plane.
Referring to
Pistons 16 are fitted in the cylinders 11n for reciprocation in the cylinders 11n, respectively. The pistons 16 are connected by connecting rods 17, respectively, to the crankshaft 18 placed in a crank chamber 20 defined by the cylinder block 11 and the crankcase 12. The vertical crankshaft 18 is supported for rotation in main bearings 19 on the cylinder block 11 and the crankcase 12 with its center axis extended substantially parallel to a vertical direction. The cylinder head 13 is provided with combustion chambers 21 respectively opposed to the pistons 16 with respect to a direction parallel to the axes of the cylinders 11n, intake ports respectively opening into the combustion chambers 21, exhaust ports respectively opening into the combustion chambers 21, and spark plugs respectively facing the combustion chambers 21. The cylinder head 13 is provided with intake valves for opening and closing the intake ports, and exhaust valves for opening and closing the exhaust ports. The intake valves and the exhaust valves are driven for opening and closing operations in synchronism with the rotation of the crankshaft 18 by an overhead camshaft type valve train 23 disposed in a valve train chamber 22 defined by the cylinder head 13 and the head cover 14.
The valve train 23 includes a camshaft 24 provided with intake cams 25a and exhaust cams 25b, intake rocker arms 26a supported for rocking motions on a rocker arm shaft, and exhaust rocker arms 26b supported for rocking motions on a rocker arm shaft. The camshaft 24 is driven for rotation by the crankshaft 18 through a belt-drive transmission mechanism 50. The camshaft 24 has a center axis parallel to that of the vertical crankshaft 18. The intake valves and the exhaust valves are driven for opening and closing motions by the intake rocker arms 26a and the exhaust rocker arms 26b driven by the intake cams 25a and the exhaust cams 25b, respectively. The valve train 23 is a driven device provided with the camshaft 24, namely, a driven shaft, driven for rotation by the crankshaft 18.
Referring also to
The combustion gas discharged as exhaust gas from the combustion chambers 21 flows through the exhaust ports into an exhaust manifold passage formed in the cylinder block 11. Then, the exhaust gas is discharged through passages formed in the mount case 1, the exhaust pipe and the extension case 2 into the water.
The internal combustion engine E is provided with a lubrication system including the oil pan 15 placed below the cylinder block 11, the cylinder head 13 and the crankcase 12, an oil pump 29 (
Referring to
The belt-drive transmission mechanism 50 includes a drive pulley 51, a driven pulley 52, a belt 53 made of rubber, namely, an endless toothed belt, and a tension pulley 54 (
Referring to
The upper case 62 is provided with openings through which the upper end parts 18a and 24a and the boss 52c of the driven pulley 52 are extended, and a hand hole 42 for adjusting the position of the tension pulley 54. The hand hole 42 is covered with a cover 39. Joints between the upper end parts 18a and 24a and the boss 52c and the openings are sealed in an oil-tight fashion.
Referring to
The circular opening 41a is slightly greater than a circular flange 18c formed on the upper end part 18a of the crankshaft 18. Therefore, the flow of the gas between the crank chamber 20 and the belt chamber 63 through the opening 41a is very small and negligible as compared with the flow of the gas through the vent holes 70 and 71. Thus the gas flows between the crank chamber 20 and the belt chamber 63 substantially only through the vent holes 70, and the gas flows between the valve train chamber 22 and the belt chamber 63 substantially only through the vent holes 71.
The vent holes 70 and 71 lie below the belt 53. Suppose that the belt chamber 53 is divided into an inside area surrounded by the belt 53 and an outside area extending outside the belt 53 in a horizontal plane. The vent holes 70 and 71 are formed in the outside area, namely, an area extending between the belt-drive transmission mechanism 50 and the flange 61a. Therefore, the vent holes 70 and 71 do not overlap the belt-drive transmission mechanism 50 in a horizontal plane. Thus the lower case 61 serves as a shielding member or a partition wall entirely or substantially entirely isolating an overlying part of the belt-drive transmission mechanism 50 overlying the crank chamber 20 from the crank chamber 20 as viewed in a vertical direction or in a horizontal plane, and the vent holes 70 and 71 do not overlap the overlying part of the belt-drive transmission mechanism 50 corresponding to the crank chamber 20 as viewed in a horizontal plane. In this embodiment, the overlying part of the belt-drive transmission mechanism 50 includes at least a part 53a (
Referring to
More concretely, the crank chamber 20 contains therein oil drips and oil mist produced from oil splashed by the rotating crankshaft 18 and oil discharged from the main bearings 19, and blowby gases. An oil-containing gas, namely, a mixture of blowby gases and oil mist, is drawn from the crank chamber 20 through internal breather passages, not shown, formed in the cylinder block 11 and the cylinder head 13 into the valve train chamber 22 by intake manifold vacuum created in the breather chamber 45 while the internal combustion engine E is running. In the meantime, part of the oil-containing gas flows from the crank chamber 20 through the connecting passage 44, the space 43 and the vent holes 70 into the belt chamber 63, and then flows from the belt chamber 63 through the vent holes 71 into the valve train chamber 22. Oil is separated from the oil-containing gas drawn into the valve train chamber 22 in the breather chamber 45 to produce a gas not containing oil. The gas not containing oil flows from the breather chamber 45 through the breather pipe 46 into the inlet air silencer 27a. Then, the gas is taken together with intake air into the combustion chambers 21.
The lower case 61 intercepts the flow of oil drops scattered in the crank chamber 20 from the crank chamber 20 into the belt chamber 63 to suppress wetting the components of the belt-drive mechanism 50 including the belt 53 with the oil drops. The oil-containing gas flowing from the crank chamber 20 toward the belt chamber 63 is stopped and deflected from the direction toward the belt chamber 63 by the lower case 61 in the space 43, and then flows through the vent holes 70 into the belt chamber 63. When the oil-containing gas comes into contact with the lower case 61, part of the oil contained in the oil-containing gas adheres to the lower case 61 and hence the oil content of the oil-containing gas is reduced.
The transmission case 60 is provided therein with an internal wall W1 (
Referring to
The belt chamber 63 is a dual chamber including an inner chamber 63a extending on the inner side of the internal wall Wi and holding the entire belt-drive transmission mechanism 50, and an outer chamber 63b into which the vent holes 70 and 71 open. The internal wall Wi is provided with a plurality of connecting ports 73 and 74 by way of which the inner chamber 63a and the outer chamber 63b communicate with each other.
The connecting port 73 is a crank-chamber-side connecting port on the side of the crank chamber 20 with respect to a direction parallel to the axes of the cylinders. The connecting ports 74 are valve-train-chamber-side connecting ports on the side of the valve train chamber 22 with respect to a direction parallel to the axes of the cylinders. The connecting port 73 is a slit (
The respective sectional areas of the connecting ports 73 and 74 are smaller than those of the vent holes 70 and 71. The respective sectional areas of the connecting ports 73 and 74 are determined such that the flow of the oil-containing gas into the inner chamber 63a is restricted to the least possible extent and oil discharged through jet nozzles 80 to be described later can flow out smoothly from the inner chamber 63a. Since the oil for lubricating the belt 53 is supplied through the jet nozzles 80, the oil mist contained in the oil-containing gas does not need to be used for lubricating the belt 53. Thus the flow of the oil-containing gas from the crank chamber 20 through the connecting ports 73 and 74 into the inner chamber 63a is very small.
As obvious from
Referring also to
The operation and effect of the foregoing embodiment will be described.
The transmission case 60 defining the belt chamber 63 in the internal combustion engine E has the lower case 61 (the bottom wall W1) and isolates the belt chamber 63 from the crank chamber 20. The lower case 61 thus covers the part 53a of the belt 53 overlying the crank chamber 20 to screen the part 53a from oil drips scattered from the crank chamber 20 and the oil-containing gas flowing out from the crank chamber 20. Thus the belt 53 is prevented from being excessively exposed to the oil drops and the oil-containing gas from the crank chamber 20 by the lower case 61. Moreover the belt 53 is prevented from being excessively exposed to the blowby gases contained in the oil-containing gas.
Since the lower case 61 of the transmission case 60 serves as a screening or shielding member, the internal combustion engine E does not need any special shielding member. Thus the lower case 61 reduces the component parts and the cost of the internal combustion engine E.
The belt chamber 63 defined by the transmission case 60 is isolated from the crank chamber 20 such that the oil-containing gas does not flow from the crank chamber 20 directly toward the belt 53 and the oil is injected concentratedly on the belt 53 in the belt chamber 63 through the jet nozzles 80. The internal wall Wi of the transmission case 60 isolates the belt chamber 63 such that the oil-containing gas from the crank chamber 20 does not flow directly toward the belt-drive transmission mechanism 50 including the belt 53. Such a condition exposes the belt 53 to the oil-containing gas less than a condition where the oil-containing gas flows directly toward the belt 53. Thus the degradation of the belt 53 due to exposure to the oil and the blowby gases contained in the oil-containing gas can be retarded. Lubrication of the belt 53 with the oil injected through the jet nozzles 80 extends the life of the belt 53 and can extend maintenance interval. Since the oil for lubricating the belt 53 is injected through the jet nozzles 80 concentratedly onto the limited areas on the belt 53, an oil injecting rate at which the oil is injected onto the belt 53 and parts of the belt 53 to be lubricated can be easily determined as compared with a state where the belt 53 is lubricated with the oil contained in the oil-containing gas. Thus the belt 53 can be properly lubricated.
Since the lubrication of the belt 53 does not depend on the oil contained in the oil-containing gas, the flow of the oil-containing gas into the inner chamber 63a can be sharply cut and hence the belt 53 is exposed scarcely to the blowby gases contained in the oil-containing gas. Thus the degradation of the belt 53 due to exposure to the blowby gases can be effectively prevented.
An internal combustion engine E in a second embodiment of the present invention will be described with reference to
An upper end part Ea of an engine body serves as a lower case 61 (a bottom wall W1) of a transmission case 60 defining a belt chamber 63. An upper case 62 is joined to the upper end part Ea. An internal wall Wi is fastened to the upper end part Ea with bolts. The internal wall Wi has a vertically rising side wall 66 substantially entirely surrounding a belt-drive transmission mechanism 50, and a horizontally extending intermediate wall 67 having the shape of a plate and joined to the upper end of the side wall 66. The side wall 66 and the intermediate wall 67 are formed integrally in a single piece or formed separately and joined together.
In the second embodiment, the upper end part Ea of the engine body serves as the bottom wall W1 of the belt chamber 63. A top wall W2 of the belt chamber 63 includes the upper case 62 serving as an outer top wall, and the intermediate wall 67 serving as an inner top wall.
The belt chamber 63 is divided by the internal wall Wi into an inner chamber 63a holding the belt-drive transmission mechanism 50, and an outer chamber 63b. Vent holes 70 and 71 opens into the outer chamber 63b. Side wall 66 is provided with connecting holes 73 and 74.
A lubricating device is disposed between the upper case 62 and the intermediate wall 67 with respect to a vertical direction in the outer chamber 63b. The lubricating device has an oil separating structure 85 for separating oil contained in an oil-containing gas that flows from a crank chamber 20 through the vent holes 70 into the outer chamber 63b, and oil holes 86 through which the oil separated from the oil-containing gas by the oil separating structure 85 is dropped concentratedly onto a belt 53 included in the belt-drive transmission mechanism 50 in the inner chamber 63a.
The oil separating structure 85 includes two collecting parts of the intermediate wall 67 each having a taper surface 85a tapering down toward the oil hole 86, and baffle plates 85b, namely, gas-liquid separating means, disposed in a passage 68 through which the oil-containing gas flows so as to obstruct the flow of the oil-containing gas. The baffle plates 85b are extended vertically downward from the upper case 62 so as to be spaced apart from the taper surfaces 85a of the intermediate wall 67. All the baffle plates 85b may be extended vertically upward from the intermediate wall 67. Some of the baffle plates 85b may be extended downward from the upper case 61 and the rest may be extended vertically upward from the intermediate wall 67.
As the oil-containing gas flows into the passage 68 in a part of the outer chamber 63b over the intermediate wall 67 through the vent holes 70 and flows out from the passage 68 through the vent holes 71, the oil-containing gas comes into contact with the baffle plates 85b in the passage 68. Consequently, the oil contained in the oil-containing gas is separated from the oil-containing gas. The oil thus separated from the oil-containing gas drips onto and flows along the taper surfaces 85a. Then, the oil drips in oil drips through the oil holes 86 on a contact point where the belt 53 comes into contact with a drive pulley 51 and a contact point where the belt 53 comes into contact with a driven pulley 52.
The second embodiment exercises the following operation and effect in addition to the operation and effect exercised by the first embodiment.
The transmission case 60 is provided with the internal wall Wi isolating the belt chamber 63 from the crank chamber 20, the oil supply means includes the oil holes 86 formed in the top wall W2, the oil separated from the oil-containing gas from the crank chamber 20 by the baffle plates 85a and flowing on the top wall 67 of the top wall W2 drips through the oil holes 86 onto the belt 53 to lubricate the belt 53. Thus parts of the belt 53 onto which the oil drips can be easily determined and hence the belt 53 can be properly lubricated since the oil separated from the oil-containing gas and dripping through the oil holes 86 is used for lubricating the belt 53. Therefore, a breather chamber 45 of a breather structure may have a low oil separating function and hence the breather chamber 45 may be small.
Modifications of the foregoing embodiments will be described.
The internal wall Wi may surround the belt-drive transmission 50 entirely in a horizontal plane, excluding the connecting holes 73 and 74.
The driven device may be an accessory having a driven shaft, such as the oil pump 20 having the rotating shaft or another transmission mechanism.
A flywheel may be mounted on a lower end part 18b of the crankshaft 18, and the drive shaft 5 may be connected through the flywheel to the crankshaft 18.
The belt chamber 63 may be disposed within the engine body or under the engine body instead of being disposed above the engine body.
The vertical internal combustion engine may be a single-cylinder internal combustion engine and may be incorporated into a machine other than the outboard motor.
Number | Date | Country | Kind |
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2006-156681 | Jun 2006 | JP | national |