Vertical internal combustion engine

Details Vertical internal combustion engine Vertical internal combustion engine

2000-08-02

2001-09-04

Kwon, John (Department: 3747)

Internal-combustion engines

Vibration compensating device

Balancing arrangement

C123S1960CP

Reexamination Certificate

active

06283080

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a vertical internal combustion engine having a crankshaft directed substantially in a vertical direction, particularly a vertical internal combustion engine for an outboard motor.
In a 4-stroke cycle vertical internal combustion engine disclosed in Japanese Laid-Open Patent Publication No. Hei 7-149290, a flywheel is provided on a lower end of a crankshaft directed in a vertical direction integrally and a lubricating oil pump is disposed above the flywheel. Further, at a position above the flywheel, a drive gear is provided on the crankshaft integrally and a speed increasing mechanism is interposed between the drive gear and the lubricating oil pump so that the lubricating oil pump is rotationally driven at a higher speed than that of the crankshaft.
In a 4-stroke cycle vertical internal combustion engine disclosed in Japanese Laid-Open Patent Publication No. Hei 8-100616, a lubricating oil pump is directly connected to a lower end of a cam shaft directed vertically.
According to the engine disclosed in the above-mentioned Japanese Publication No. Hei 7-149290, since the lubricating oil pump rotates at a higher speed than the crankshaft, even if the lubricating oil pump is small-sized, a high discharge ability is obtainable. However, owing to the lubricant oil pump positioning below a bearing portion of the internal combustion engine for pivotally supporting the crankshaft, a part of the crankshaft extending downward from the bearing portion becomes long so that it is difficult to support the flywheel having a large inertial mass stably from a viewpoint of vibration.
According to the engine disclosed in the above-mentioned Japanese Publication No. Hei 8-100616, since no lubricating oil pump is disposed above the flywheel, the flywheel can be arranged near the internal combustion engine and as the result the flywheel having large inertial mass can be supported stably. However, since rotational speed of the cam shaft is a half of that of the crankshaft, there are inconveniences that the discharge ability is low and the lubricating oil pump becomes large necessarily.
Some vertical internal combustion engines for outboard motors in which balancer shafts are used for reducing vibration are disclosed in Japanese Laid-Open Patent Publications Nos. Sho 63-192693, Hei 3-224894and Hei 4-337143.
The Japanese Publication 63-192693and 3-224894disclose balancer mechanisms for offsetting and reducing the primary vibration in an in-line 2-cylinder 4-stroke cycle internal combustion engine.
On the one hand, the Japanese Publication 4-337143discloses a balancer mechanism in a 4-stroke cycle in-line 4-cylinder engine which aims at reducing the secondary vibration because the engine has an advantage that the primary vibration does not occur fundamentally. However, as secondary vibration becomes larger, the balancer becomes large-sized more and it becomes necessary to care about balancer shaft supporting constructions and lubricating passages.
The Japanese Laid-Open Patent Publication No. Hei 3-33416 discloses a water-cooled 4-stroke cycle internal combustion engine for propelling ships in which a suction system is arranged on one side and an exhaust system and a cartridge type oil filter are arranged on another side. As shown in
FIG. 8
of the above publication, lubricating oil having passed through the oil filter is supplied to a cam shaft pivot portion through some oil passages to lubricate the cam shaft pivot portion.
In a water-cooled 4-stroke cycle internal combustion engine for propelling ships disclosed by the Japanese Laid-Open Patent Publication No. Hei-8-100616 too, a lubricating oil passage connected between an oil filter disposed near a suction system on a front face of a crankcase and a valve moving system is arranged on the side of an exhaust system.
However, in the internal combustion engine of the publication 3-33416, an electric parts box as well as the oil filter cartridge is disposed on the side of the exhaust system and therefore if the electric parts box becomes large for meeting demands to electric control system, it is difficult to dispose the oil filter cartridge at the same position.
In the internal combustion engine of the publication 8-100616, the oil filter is disposed on a front face of the crankcase and maintenance work is easy. But since an oil passage for lubricating oil after passing through the oil filter is provided in a exhaust system, the oil passage is long to increase flow resistance, capacity of the oil pump has to be improved and amount of oil is necessarily increased.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a vertical 4-stroke internal combustion engine enabling a better arrangement of a flywheel and a lubricating oil pump. Another object of the present invention is to provide an outboard motor having such an internal combustion engine mounted. A further object of the present invention is to provide such an internal combustion engine having a lubricating device suitable for providing a balancer mechanism.
According to the present invention, there is provided a vertical internal combustion engine having a crankshaft directed substantially in a vertical direction, a flywheel provided on a lower end of the crankshaft integrally and an oil pan provided under the flywheel, wherein a lubricating oil pump driven by the crankshaft to rotate is disposed under the flywheel.
The flywheel is positioned close by the main body of the internal combustion engine so that the flywheel is supported stably irrespective of any variation of its rotational speed.
In the above internal combustion engine, a rotor of the lubricating oil pump may be positioned on a lower portion of the crankshaft and driven to rotate together with the crankshaft. According to this engine, a driving system of the lubricating oil pump can be simplified and weight lightening and reduced cost can be achieved. In addition, because the lubricating oil pump can be rotated at the same rotational speed as the crankshaft, discharge ability of the lubricating oil pump can be improved without making the lubricating oil pump large-sized.
According to another aspect of the present invention, there is provided a 4-stroke cycle vertical internal combustion engine, having an internal combustion engine main body housing a crankshaft directed substantially in a vertical direction; a flywheel provided on a lower end of the crankshaft integrally; an oil pump body forming a flywheel chamber for housing the flywheel; a oil pan disposed below the flywheel; a mount case separated from the oil pump body and having a return oil passage arranged below the oil pump body for returning lubricating oil from the internal combustion engine main body to the oil pan and a lubricating oil passage for gathering lubricating oil which has lubricated the crankshaft from a periphery of the pump body toward a center of the crankshaft and returning the lubricating oil to the oil pan; and a lubricating oil pump disposed under the oil pump body.
According to this engine, when the lubricating oil pump is disassembled for maintenance, the flywheel and the oil pump body are not required to be removed, so that disassembling and assembling work can be carried out efficiently and easily.
Further, since the flywheel chamber can be closed, adhesion of lubricating oil to the flywheel can be prevented so that a loss of power and deterioration of the lubricating oil can be avoided.
The mount case may be connected to an under surface of the internal combustion engine main body oil-tightly surrounding the oil pump body to enable smoother return of the lubricating oil.
By using the above vertical internal combustion engine of the present invention as an engine for an outboard motor having cylinders arranged substantially along a lengthwise plane of a ship, it is possible to lower the center of gravity of the outboard motor by lowering position of the internal combustion engine for improving stability of the ship.
According to the other aspect of the present inve

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