Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
1999-11-23
2001-09-04
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
C123S1960CP
Reexamination Certificate
active
06283083
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a lubricating construction for outboard motors. More specifically, the present invention relates to a lubricating construction for outboard motors which supplies a sufficient amount of a lubricating oil to valve end sections of the outboard motor.
A four-cycle engine includes a valve gear device provided in a cylinder head. Respective sliding portions in the valve gear device are continuously subjected to lubrication with a lubricating oil conducted by way of oil passages.
In conventional outboard engines, so-called valve end sections, that is, contact points between heads of intake and exhaust valves and ends of rocker arms for opening and closing the valves, in a valve gear device lack means for supplying a lubricating oil directly thereto. Lubrication of the valve end sections depends upon the splashing of a lubricating oil which scatters in the cylinder head.
A cam shaft is vertically positioned in a conventional engine, such as an engine for outboard motors, in which a crank shaft is positioned vertically. A thrust force acting in an axial direction of the cam shaft is born by a thrust bearing construction provided at a lowermost portion of a cylinder head, in which the cam shaft is housed. The thrust bearing construction supports a lower end of the cam shaft.
However, lubrication of valve end sections cannot be adequately performed only by the splashing of a lubricating oil which scatters in a cylinder head. Specifically, with a vertical-type engine, such as an engine mounted on an outboard motor, upwardly positioned valve end sections for cylinders cannot be adequately supplied with a lubricating oil. As a result, such valve end sections must be have a greater hardness relative to the normal case. This increases manufacturing costs and prevents use of common parts.
Where a thrust bearing construction is arranged at a lowermost portion of a cylinder head, it is difficult to mount and dismount a cam shaft. This results in an unfavorable assembly and maintenance quality.
Also, in the case where a thrust bearing construction is arranged above a cylinder head, a sufficient amount of lubricating oil does not spread over sliding surfaces of the thrust bearing construction and the cam shaft for the above described reasons. Therefore, such conventional arrangements are unfavorable due to the possibility that abrasion may result on poorly lubricated sliding surfaces.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a lubricating construction for outboard motors which overcomes the foregoing problems.
It is a further object of the present invention to provide a lubricating construction for outboard motors which is capable of supplying a sufficient amount of lubricating oil to valve end sections of the engine.
It is another object of the present invention to provide a lubricating structure for outboard motors which enhances the layout of a thrust bearing mechanism.
To solve the above described problems, in one aspect of the present invention, a lubricating construction for outboard motors, having a valve gear device, such as a cam shaft, provided in a cylinder head of an engine and a drive mechanism of the cam shaft provided at a lower end of the cam shaft, includes a closed space formed above a bearing boss, which supports an upper end of the cam shaft. This closed space is integrally formed with the cylinder head. Oil passages are provided in the cylinder head for conducting a lubricating oil into the closed space.
Also, to solve the above described problems, in another aspect of the present invention, a lubricating construction for outboard motors, having a valve gear device, such as a cam shaft, in a cylinder head of an engine and a drive mechanism of the cam shaft provided at a lower end of the cam shaft, includes a cover member provided above a bearing boss, which supports an upper end of the cam shaft. A closed space is provided in the cover member to be separate from the cylinder head. Oil passages are provided in the cylinder head for conducting a lubricating oil into the closed space.
Further, to solve the above described problems, in a further aspect of the present invention, a lubricating construction for outboard motors, having a valve gear device, such as a cam shaft, provided in a cylinder head of an engine and a drive mechanism of the cam shaft provided at an upper end of the cam shaft, includes a seal housing provided above the cylinder head to support an upper end of the cam shaft. A closed space is provided in the seal housing to be separate from the cylinder head. Oil passages are provided in the cylinder head for conducting a lubricating oil into the closed space.
In a feature of the present invention, a lubricating construction for outboard motors further includes oil dropping passages formed on a lower surface of the closed space immediately above the valve gear device. The lubricating oil in the closed space drops, through these oil dropping passages, onto the valve gear device.
Briefly stated, the present invention provides an oil chamber at an upper portion of an outboard engine which provides lubrication to a valve gear device within a cylinder head of the outboard engine. Oil passages provide engine oil into the oil chamber. Oil dropping passages on the bottom of the oil chamber permits the oil to flow from the oil chamber into the cylinder head. The oil dropping passages are positioned to provide sufficient lubrication to the valve end sections of the engine. As a result, the valve end sections are made from material of normal hardness, thereby reducing manufacturing costs.
According to an embodiment of the present invention, there is provided an outboard motor engine comprising: a cylinder head having a valve gear device; the valve gear device includes a cam shaft; at least one bearing boss supporting the cam shaft in the cylinder head; a cavity above an uppermost bearing boss; the uppermost bearing boss supporting an upper end of the cam shaft; and oil passages for conducting oil into the cavity.
According to a feature of the present invention, there is provided an outboard motor engine comprising: a cylinder head having a valve gear device; the valve gear device includes a cam shaft; at least one bearing boss supporting the cam shaft in the cylinder head; a cavity above an uppermost bearing boss; the uppermost bearing boss supporting an upper end of the cam shaft; oil passages for conducting oil into the cavity; oil dropping passages in a lower portion of the cavity, wherein oil is communicated between the cavity and the cylinder head; and the oil dropping passages being located such that oil dropping from the oil dropping passages lubricates at least one of the at least one intake valve, the at least one exhaust valve, the intake rocker arm, the exhaust rocker arm, the intake rocker shaft, the exhaust rocker shaft, and the cam shaft.
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Kawasaki Naoki
Ohta Mitsuhiko
Huynh Hai
Kamen Noah P.
Morrison Law Firm
Suzuki Motor Corporation
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