Land vehicles – Wheeled – Occupant propelled type
Patent
1996-11-29
1999-01-12
Hurley, Kevin
Land vehicles
Wheeled
Occupant propelled type
2802883, B62K 1902
Patent
active
058576908
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a bicycle frame, of composite material, of the sort which comprise a diagonal down tube connected by a bottom bracket crankset housing to a seat tube and to two chain stays extending backward, diverging from the bottom bracket crankset housing, a seat stay connecting the ends of the chain stays to a top part of the seat tube, and a longitudinal top tube connecting the seat tube to a steering bush which provides the link between this longitudinal tube and the top end of the diagonal down tube.
Bicycle frames of composite material, that is to say of material based on carbon fibers or equivalent fibers, has the advantage of a substantial reduction in weight.
Current frames of composite material can be split, in practical terms, into two major families, namely monocoque frames and frames with composite joints or aluminum joints.
Monocoque frames are produced by molding as a single piece, or possibly by overmolding two parts made beforehand.
This method of manufacture requires a substantial amount of tooling so as to be able to cater for the entire customer demand; a minimum of twelve sizes seems to be necessary for a product at this end of the range, in order to meet the broad spectrum of cyclists' builds.
Tooling investment costs for this type of monocoque-frame manufacture are very high.
Furthermore, the concept of the monocoque frame penalizes the product itself. This is because the operation of molding takes place using a lost core, generally one made of polyurethane or of a foam of an equivalent substance. The weight increase imposed by the molding core which remains inside the tubes of the frame is a substantial drawback because it goes against reducing the weight of the frame. Sometimes inflatable cores are used during molding to avoid lost cores, but the use of such inflatable cores is tricky; what is more, the mold quality is insufficient and requires the added expense of finishing work.
Frames with composite joints, constituting the second family mentioned earlier, are made in a conventional manner. Tubular elements of composite material are bonded together at joints.
The joints are made of composite material, which allows an appreciable weight-saving in comparison to conventional types of joint made of aluminum.
This technology of frames with composite joints makes it possible to produce frames which exhibit good performance both as regards the weight and as regards the mechanical qualities, but the production of joints made of composite material proves expensive and tricky.
Furthermore, there are still just as many assembly and manufacturing operations as there are with a frame with joints made of aluminum or of light alloy. There are also a large number of bonded connections. This results in a high manufacturing cost.
The object of the invention, above all, is to overcome the drawbacks of the two major families of composite frame mentioned earlier. The invention aims, in particular, to provide a frame of composite material which is as rigid as possible and particularly reliable and robust, but which still has an acceptable manufacturing cost.
According to the invention, a bicycle frame of composite material of the sort defined earlier is characterized in that it comprises a first subassembly molded as a single piece consisting at least of the diagonal down tube, of the bottom bracket crankset housing, of the seat tube, of the two chain stays and of the bottom part of the steering bush, and a second subassembly molded as a single piece consisting of the longitudinal top tube, of a seat joint and of the top part of the steering bush, these two subassemblies being joined together by bonding.
Advantageously, the diagonal down tube, the seat tube and the longitudinal top tube have no mold core inside them.
The seat stay generally constitutes a third subassembly molded as a single piece, the top end of which is connected by bonding to a seat stay joint provided on the seat tube and each bottom end of which is connected to a lug itself connected to the rear part of a chain stay.
REFERENCES:
patent: 5253890 (1993-10-01), Takamiya et al.
patent: 5271784 (1993-12-01), Chen et al.
patent: 5445400 (1995-08-01), Martin et al.
Hurley Kevin
Time Sport International
LandOfFree
Bicycle frame of composite material, molds for obtaining such a does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bicycle frame of composite material, molds for obtaining such a , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bicycle frame of composite material, molds for obtaining such a will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1507443