Land vehicles – Ski or skate appliance or attachment – Ski pole
Patent
1995-09-01
1997-03-18
Camby, Richard M.
Land vehicles
Ski or skate appliance or attachment
Ski pole
135 65, A63B 5312
Patent
active
056115717
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a pole shaft for a cross-country ski pole, said shaft consisting of resin-bound fiber layers which provide the walls surrounding the continuous cavity of the shaft.
This type of fiber-reinforced pole shafts have been used in cross-country ski poles for a long time. In racing ski poles, the fibers primarily comprise carbon fibers while the general-purpose ski poles usually employ glass fiber or a combination of carbon and glass fibers. The binder resin comprises e.g. an epoxy resin or a polyester resin. It is prior known to make a cross-sectionally circular pole shaft downward tapered so as to place its centre of gravity higher up, i.e. to provide a lightweight lower end and a low air resistance for the lower end. Especially, when using racing ski poles, it is essentially important that a thrust be followed by bringing the pole as quickly as possible forward to a new thrust position. Thus, the weight of the lower end of a pole and the resulting moment of inertia as well as its air resistance must be made as negligible as possible. On the other hand, a pole shaft is required to have a certain strength especially against buckling, which constrains possibilities for the reduction of weight and diameter.
One aspect of the invention is the realization that the hazard of a pole buckling during a thrust is a little more unlikely to occur in lateral direction than backwards in the skiing direction. Thus, the pole can be made a little more flattened in lateral direction than in the skiing direction.
In terms of the position of the centre of gravity, strength, and aerodynamics, the optimum solution is achieved according to the invention in a manner such that the cross-section which is substantially circular or oval at the top end of a shaft gradually changes from the mid-section of a shaft downwards into a droplet shape and in the lower section of a shaft, at least over approximately one third of the length of a shaft, the length of said droplet shape in relation to the width increases while the cross-sectional area diminishes. It is further preferred that adjacent to the lower end of a shaft the droplet shape changes over a short transition zone into a shaft having a substantially circular cross-section and a diameter that is substantially less than the length of said droplet shape. Thus, the sleeve of a snow ring need not be subjected to any modifications as compared to the currently available solutions.
One embodiment of the invention will now be described in more detail with reference made to the accompanying drawing, in which
FIG. 1 shows a pole shaft of the invention in a side view and FIGS. 2-5 show sections in a larger scale taken along lines II--II, III--III, IV--IV and V--V in FIG. 1, the numerals for views and sections matching each other. FIG. 4A shows an alternative embodiment of section IV--IV, which is elliptical or oval.
The pole shaft consists e.g. of longitudinal and transverse fiber layers and it is hollow. The walls surrounding the shaft cavity can be of equal thickness or the wall thickness may fluctuate over various sections of the shaft length. In view of optimizing its strength, the position of its centre of gravity, and aerodynamics, the shaft tapers conically and at least in the lower section of the shaft, approximately over 1/3 of a shaft length L, i.e. a distance l 1 (which is e.g. appr. 50 cm), the cross-sectional shape of the shaft changes progressively downwards from a substantially circular or oval cross-section to a droplet shape. The top end of the shaft, at least down to about half-way, can be substantially circular or oval in cross-section. The ratio of the major diameter of an oval cross-section at the top end of the shaft to the minor diameter is not more than 2:1. When progressing down from half-way of the shaft, preferably e.g. over a distance l1, the cross-sectional shape changes gradually more and more towards a droplet shape in a manner such that the length of a droplet shape increases relative to its width. At the same time, the cross-sectio
REFERENCES:
patent: 5348346 (1994-09-01), Unger
Jaatinen Pauli
Manninen Taisto
Ripatti Markku
Camby Richard M.
Exel Oy
LandOfFree
Pole shaft for a cross-country ski pole does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pole shaft for a cross-country ski pole, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pole shaft for a cross-country ski pole will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1701056