Machine element or mechanism – Elements – Gear casings
Reexamination Certificate
2001-05-30
2004-07-27
Bucci, David A. (Department: 3682)
Machine element or mechanism
Elements
Gear casings
Reexamination Certificate
active
06766714
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a mounting structure for rigidly mounting to a device body a case member covering a portion exposed from the device body. More particularly, the invention relates to a mounting structure of a case member for covering a portion exposed from an internal combustion engine where a power transmitting mechanism, for example, is located.
2. Description of the Related Art
A cam chain cases used to cover a valve driving mechanism disposed in a crank shaft end portion of an internal combustion engine has been detachably attached rigidly to the body of an internal combustion engine with bolts at positions along its outer circumferential periphery, as shown in Japanese Patent Laid-Open Publication No. hei 7-83069.
A central portion of the cam chain case disclosed on the same publication is liable to yieldingly deform in a rectangular direction with respect to a case plane portion. In particular, because of a low rigidity of a peripheral portion of a through hole at the central portion of the cam chain case at an end surface of the engine, through which a shaft of a water pump passes, the central portion of the cam chain case is liable to vibrate.
For the purpose of preventing it, the cam chain case has a plurality of bolt boss portions surrounding the through hole such that bolts in threading engagement with the engine body through the bolt boss portions rigidly couple the cam chain case central portion to the engine body to prevent or alleviate vibrations of the central portion.
Japanese Utility Model Laid-Open Publication No. hei 4-91210 discloses a lubricating system disposed in a space defined between a cam chain case and the body of an internal combustion engine to supply lubricant oil to a timing chain (cam chain) for transmitting rotation of a crank shaft to a cam shaft. In this lubricating system, a projecting portion is formed on an oil pump body attached to a cylinder block, and the projecting portion defines an oil path communicating with tan oil path in the cylinder block and an oil jet hole for jetting oil from the oil path toward a portion of the timing chain to be lubricated. Thus, the oil path in the cylinder block and the oil path of the projecting portion are connected through a hollow pin fit in both oil paths when the oil pump body is coupled to the cylinder block.
In the above-introduced structure configured to attach the cam chain case to the engine body, the needs for a number of bolt boss portions at the central portion of the cam chain case and about an opening and the need for a number of bolts inevitably increase the number of parts, and also increase steps for applying and fixing bolts. Therefore, it has been difficult to reduce the cost and the weight.
In the conventional timing chain lubricating system, the need for the hollow pin also involves the drawbak of again increasing the number of parts and the assembling steps. Further, since the projecting portion having the oil path and the oil jet hole is made, in case a bolt boss portion is formed on the cam chain case or the engine body to prevent vibrations of the cam chain case as indicated above, even when a close positional relation is required from the viewpoint of preventing vibrations of the cam chain case and the viewpoint of lubrication of the cam chain, for example, near sprockets the cam chain wraps, existence of the projecting portion in addition to the bolt boss portions may cause a constraint in the positional relation. Thus, it is often difficult to make the bolt boss portions or the projecting portion at appropriate positions.
SUMMARY OF TIE INVENTION
It is therefore an object of the invention to provide a case member mounting structure capable of increasing the bending rigidity of a case member and preventing vibrations of the case member and simultaneously capable of reducing the number of parts and the number of assembling steps and significantly reducing the cost and the weight.
According to the invention, there is provided a case member mounting structure characterized in that at least one projecting portion is formed on one or both of an inner surface of a case member and an outer wall surface of a device body to contact the inner wall surface of the case member having an outer circumferential portion fastened to said device body by a plurality of fastening means and to contact the outer wall surface of the device body on which the case member is to be fastened, and a seal member is provided on a contact surface at a distal end of the projecting portion.
According to the invention, since the fastening means for coupling the projecting portion of the case member to the device body is not required, or the number of parts as the fastening means can be reduced, it is possible to reduce the assembling steps as much as the number of parts reduced, and to significantly decrease the manufacturing cost and the weight.
According to a more preferable aspect of the invention, there is provided a case member mounting structure characterized in that at least one projecting portion is formed on one or both of an inner surface of a case member for covering a driving force transmission mechanism and an outer wall surface of a body of an internal combustion engine to contact the inner wall surface of the case member having an outer circumferential portion fastened to the body by a plurality of fastening means and to contact the outer wall surface of the body on which the case member is to be fastened, and a seal member is provided on a contact surface at a distal end of the projecting portion.
With this structure, bolt boss portions required for fastening the engine case member to the engine body with bolts are not required any more, or decreased. Moreover, the fastening means for coupling the projecting portion of the engine case member to the engine body is not necessary, or the number of parts as the fastening means can be reduced. Therefore, it is possible to reduce the assembling steps as much as the number of parts reduced, and to significantly decrease the manufacturing cost and the weight.
Additionally, unlike the boss portions of the aforementioned conventional technique, which are required to have a diameter greater than the maximum outer diameter of bolts to enable holes to be made for receiving the bolts therethrough or therein, even in case there is no allowance in the space defined between the engine case member and the engine body due to the existence of members disposed in that space, the projecting portions have a larger freedom in shape and size, such as being configured as elongated ribs, and are reduced in restrictions regarding their positional relation. Therefore, the projecting portions can be made in effective locations from the viewpoint of preventing vibrations and noises without disturbing the function of the engine.
The seam member may be a liquid seal member coated on one or both of contact surfaces at distal ends of the projecting portions.
With this structure, as the liquid seal member cures, the projecting portions on the inner surface of the case member are rigidly bonded to the device body or engine body. Alternatively, projecting portions on the outer wall surface of the device body or engine body are rigidly bonded to the case member. Therefore, rigidity against the bending force in directions rectangular to the planar portion of the case member is remarkably increased, and vibrations of the case member are suppressed.
The seal member may be a resilient seam member for engagement with at least one of contact surfaces at the distal ends of the projecting portions.
With this arrangement, the outer wall surface of the device body or engine body and the inner wall surface of the case member are elastically coupled, and transmission of vibrations from the device body or engine body to the case member is prevented.
The contact surfaces at the distal ends of the projecting portions may be configured to lie on a common plane to that of the outer wall surface of the device body or engine body, or of t
Ishimura Yuuji
Iwata Kazuyuki
Tanaka Atsushi
Yoshida Keiko
Bucci David A.
Honda Giken Kogyo Kabushiki Kaisha
Smith Julie K.
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