Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
2001-05-22
2003-05-06
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
Reexamination Certificate
active
06557515
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a structure for lubricating a valve-operating device in an OHC engine.
In the prior art, OHV (overhead valve) and OHC (overhead camshaft) general-purpose engines have been widely used as power sources for mowers, power sprayers, power generators, etc. In an OHC engine, a valve-operating cam is provided on the cylinder head side, and is driven by a chain, a cogged belt, or the like, in synchronization with a crankshaft. A slipper of a rocker arm, which is provided to rock around a rocker shaft, slidably contacts with the valve-operating cam, so that the rocker arm is rocked by the rotation of the valve-operating cam so as to open/close an intake/exhaust valve.
In such a general-purpose engine, in order to lubricate a valve-operating system such as a chain, a sprocket, or a valve-operating cam, the chain or the cogged belt is used as an oil carrier so as to lubricate the valve-operating cam or the slipper. For example, Japanese Patent Laid-Open Publication No. Hei. 9-151720 proposes a system in which a wall portion is provided along an extended straight portion of a slack side of a timing belt, and oil droplets are thrown by a centrifugal force onto the wall portion, thereby making the oil droplets into minute droplets, so as to lubricate the various portions of the valve-operating system.
However, while such a lubricating system as disclosed in Japanese Patent Laid-Open Publication No. Hei. 9-151720 improves the lubrication by making the oil into minute droplets and diffusing them across the entire valve-operating device, the oil may not be sufficiently supplied onto the slidable contact surfaces between the valve-operating cam and the slipper. In other words, while there is an effect of uniformly lubricating the entire device, it had a problem that the oil is not effectively supplied to a specific portion which particularly requires good lubrication and which most requires oil supply.
SUMMARY OF THE INVENTION
An object of the present invention is to reliably supply a lubricating oil to slidable contact surfaces between the valve-operating cam and the slipper, which most requires oil supply.
In order to achieve the above mentioned object, there is provided a structure for lubricating a valve-operating device provided on a cylinder head side of an OHC engine, having a driving member for driving the valve-operating device in synchronization with a crankshaft and supplying a lubricating oil to the valve-operating device from an oil pan. The structure comprises an oil guide portion provided in a ceiling portion of a cover member mounted on a top of the cylinder head along a rotational direction of the driving member to face the driving member for guiding the flow of the lubricating oil separated from the driving member to a certain direction, and an oil dripping portion provided in the ceiling portion adjacent to the oil guide portion and protruding toward the valve-operating device for dripping the lubricating oil guided by the oil guide portion onto the valve-operating device.
According to the present invention, the lubricating oil, which has been separated from the driving member, can be collected by the oil guide portion, and supplied to the valve-operating device via the oil dripping portion. Therefore, it is possible to effectively supply the oil to a portion which particularly requires lubrication, thereby improving to decrease the frictional resistance of the valve-operating device and thus improving the product reliability.
The present invention also provides a cover member for covering a top of a cylinder head of an OHC engine and for accommodating a valve-operating device and a driving member for driving the valve-operating device in synchronization with a crankshaft. The cover member comprises an oil guide portion provided to face the driving member for guiding the flow of lubricating oil separated from the driving member to a certain direction, and an oil dripping portion provided adjacent to the oil guide portion and protruding toward the valve-operating device for dripping the lubricating oil guided by the oil guide portion onto the valve-operating device.
According to the cover member of the present invention, the lubricating oil, which has been separated from the driving member, can be collected by the oil guide portion, and supplied to the valve-operating device via the oil dripping portion. Therefore, it is possible to effectively supply the oil to a portion that particularly requires lubrication, thereby improving to decrease the frictional resistance of the valve-operating device and thus improving the product reliability.
REFERENCES:
patent: 5038732 (1991-08-01), Matayoshi et al.
patent: 5058542 (1991-10-01), Grayson et al.
patent: 5642701 (1997-07-01), Oswald et al.
patent: 5709185 (1998-01-01), Aizawa et al.
patent: 5992355 (1999-11-01), Shichinohe et al.
patent: 6138633 (2000-10-01), Prior
patent: 9151720 (1997-06-01), None
Furuya Akira
Sakai Takao
Benton Jason
Farber Martin A.
Fuji Jukogyo Kabushiki Kaisha
Kamen Noah P.
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