Internal-combustion engines – Poppet valve operating mechanism – Camshaft drive means
Reexamination Certificate
1999-11-02
2001-06-26
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Camshaft drive means
C474S111000, C474S140000, C474S150000
Reexamination Certificate
active
06250268
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an attachment structure for a cam chain of a valve gear for a four-cycle engine.
2. Description of Related Art
Conventionally, a cam chain guide for guiding a cam chain in a manner that allows the cam chain to slide and a cam chain tensioner for maintaining tension of the cam chain are provided at a valve gear of a four-cycle engine (for example, refer to Japanese Patent Laid-open Publication No. Hei. 10-77905). One end of such a chain guide is supported by a bolt at an attachment member such as a crankcase etc.
A certain amount of attachment rattling occurs at the cam chain support part which causes noise to occur in accompaniment with vibrations of the moving cam chain, with this noise being particularly noticeable when the engine is rotating at a high-speed. The pressing force of the cam chain tensioner can, however, be regulated in order to prevent this noise so as to make the cam chain more tense, but this causes friction between the cam chain tensioner and the cam chain to increase which in turn influences the output of the engine.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to effectively reduce the noise arising at the cam chain guide attachment part without increasing the pressing force of the cam chain guide more than is necessary.
In order to resolve the aforementioned problems, in a first aspect of the present invention, a cam chain guide attachment structure for a cam chain guide for slidably guiding a cam chain is provided at a valve gear of an engine and is supported at one end by an attachment member. Projections projecting a prescribed amount towards the attachment member are then provided at an attachment surface facing the attachment member at an attachment end section of the cam chain guide.
In a second aspect of the present invention, in addition to the first aspect of the present invention, annular recesses for accepting deformation of the projections are formed along the projections.
In a third aspect of the present invention, in addition to the first aspect of the present invention, the projections are formed on a side surface of the cam chain guide. This means that the cam chain guide side surface is then substantially parallel to the plane of rotation of the cam chain.
In a fourth aspect of the present invention, in addition to the first aspect of the present invention, the cam chain guide has an attachment hole at the attachment end section, is supported by the attachment member fitting into the attachment hole, and the projections are formed at an inner peripheral surface of the attachment hole.
In a fifth aspect of the present invention, in addition to the first aspect of the present invention, the cam chain guide is made of resin and the projections are integrally formed with the cam chain guide.
In a sixth aspect of the present invention, in addition to the first aspect of the present invention, the cam chain guide is made of metal, and the projections are formed integrally at the attachment end section by baking a rubber member.
According to the first aspect of the present invention, when the attachment end section of the cam chain guide is supported at the attachment member, projections provided at the attachment surface of the attachment end section project a prescribed amount in the direction of the attachment member. This portion is then deformed while coming into contact with the attachment member side first and attachment rattling is therefore eliminated. Noise caused by the attachment part of the cam chain guide can therefore be effectively reduced and the effect of the pressing force of the cam chain tensioner on the output of the engine can be reduced, since the pressing force of the cam chain tensioner does not have to be increased more than is necessary.
According to the second aspect of the present invention, when the attachment end section of the cam chain guide is supported at the attachment member, even if the projections deform, this deformation is accepted by annular recesses formed at the peripheries of the projections and the relationship of the dimensions of the attachment portion therefore does not change.
According to the third aspect of the present invention, since the projections are formed at a side surface of the cam chain guide, attachment is such that the projections are simultaneously deformed when the cam chain guide is attached from the side.
According to the fourth aspect of the present invention, when the attachment member is fitted into the attachment hole provided at the attachment end section of the cam chain guide, the projections formed at the inner peripheral surface of the attachment hole come into contact with the outer periphery of the attachment member and attachment rattle in the radial direction of the attachment member is annulled.
According to the fifth aspect of the present invention, the projections can be integrally formed at the time of molding by making the cam chain guide out of resin.
According to the sixth aspect of the present invention, even if the cam chain guide is made of metal, a rubber member is baked onto the attachment end section. The projections can therefore be integrally formed with this rubber member and the present invention can therefore also be applied to a metal cam chain guide. The forming of the projections is straightforward and only requires small changes to a mold for baking the rubber member.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 4832664 (1989-05-01), Groger et al.
patent: 5318482 (1994-06-01), Sato et al.
patent: 5366418 (1994-11-01), Fukushima et al.
patent: 5665019 (1997-09-01), Sheffer et al.
patent: 6013000 (2000-01-01), Moretz
patent: 6095938 (2000-08-01), Kumakura
patent: 10-77905 (1998-03-01), None
Iizuka Toru
Iwase Noritoshi
Takahashi Katsunori
Tezuka Yoshihiro
Birch & Stewart Kolasch & Birch, LLP
Honda Giken Kogyo Kabushiki Kaisha
Lo Weilun
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