WO2004016329A1

WO2004016329A1 - A system for the minimization of torsion, and control of flexural stiffness for snowboards and skis

Info

Publication number: WO2004016329A1
Application number: PCT/GR2003/000033
Authority: WO
Inventors: Markos Chatzikyriakakis
Original assignee: Markos Chatzikyriakakis
Priority date: 2002-08-16
Filing date: 2003-07-25
Publication date: 2004-02-26
Also published as: GR1004144B; AU2003285015A1

Abstract

A system positioned on the top surface of a snowboard or a ski, and minimizes torsional displacements and with some further adjustment can be made to control flexural stiffness. The system is imposed externally on the snowboard and solves the problem of torsional inadequacy, which has not yet been sufficiently resolved by the methods presented so far in the industry (which focus in the core structure and material distribution within it). Concluding, with the presented system a new totally different approach is used to control the torsional rigidity and flexural stiffness of a snowboard or ski (both pre-manufacture and post-manufacture).

Description

A SYSTEM FOR THE MINIMIZATION OF TORSION, AND CONTROL OF FLEXURAL STIFFNESS FOR SNOWBOARDS AND SKIS

The invention consists of a system (mechanism), which, is positioned at the top front (nose) and rear (tale) of a snowboard. The system maximizes the torsional rigidity, (thus minimizes torsional displacements), of the snowboard whereas the flexural stiffness is retained unaffected. Furthermore, with some minor modifications the system can be made to provide the ability to control the flexural stiffness of the snowboard. Finally, the present invention can be modified to be fitted on skis, producing the same results as stated above.

Snowboards that are currently produced and sold in the market are constructed with a core made from a special quality wood or other synthetic material, which is covered at the top with epoxy enriched fiberglass. The base of a snowboard consists of polyethylene or other similar materials, whereas at the top part and side walls plastic materials such as ABS are used. Throughout the left and right sides of a snowboard metal edges are placed. The above mentioned material, is finally assembled and pressurized into special moulds producing a snowboard in its final form.

Together with the fiberglass present inside a snowboard, other materials can be used, such as carbonfibre or KEVLAR. These materials and their distribution within the snowboard define its flexural stiffness and torsional rigidity.

For the appropriate comprehension of the invention, a description of the principles that govern the motion of a snowboard is provided. In addition, the significance of the torsional rigidity (which is of interest in this case) and flexural stiffness characteristics are analyzed in respect to their effects on performance of the snowboard. When a snowboard is moving at a sufficiently high speed turning is achieved by the anterior or posterior (depending on the direction) lateral displacement of the rider's center of mass. As a result, the snowboard is angulated in relation to the horizontal snow plane. Due to the geometry of the snowboard (wider at the front and rear) and the centripetal force produced by the rider's mass, the snowboard flexes (magnitude proportional to angulation) thus, describing an arc with its metallic edges. The turning radius is equal to the arc radius described by the board's edges. Depending on the type and brand, the snowboard's arc varies to produce the desired (by the manufacturer) performance characteristics. This arc is measured by the so called sidecut radius, which is the radius of the complete circle described by the theoretical expansion of the arc outlined by the snowboard's metallic edges. Thus, a deep (large radius) arc described by the snowboard edge, infers a small theoretical circle, leading to a snowboard which is able to perform shorter and swifter turns and vice versa.

The length and width of the snowboard are also very important parameters, influencing the behavior of the board on the snow. The general concept is that a long and slender snowboard is faster, but less agile and vice versa.

In terms of their flexural stiffness, snowboards are categorized in soft and hard boards. Soft boards are faster and more agile in relation to the harder ones, which however offer greater control and the ability to turn with much higher velocities.

Finally, torsional rigidity is of paramount importance when turning. The excess torsional angular displacement of the board while turning is the unwanted effect which causes the snowboard to loose traction with the snow due to insufficient angulation of the front (nose) and rear (tail) of the board. The insufficient angulation is produced due to the inβrtial forces acting on the board while turning and the inability of the materials within the board to provide a constant and sufficient torsional rigidity throughout its length. Thus, the front (nose) and rear (tail) of the snowboard experience greater torsional moments due to their wider geometry resulting to a reduction to the angulation of the board at these regions.

As a result of the reduction in angulation of the front (nose) and rear (tail) regions the arc described by the board edge in contact with the snow is distorted and does not describe part of a circle but a distorted curvilinear section. Thus, the ability of the snowboard to turn accurately and with stability is greatly decreased.

By examining the snowboards which have been commercially available throughout the past it is evident that the relationship between torsional rigidity and flexural stiffness is proportional. This means that when increasing the torsional rigidity of a board, its flexural stiffness is also increased.

However, the optimum combination of these two characteristics is high torsional rigidity and low flexural stiffness, as previously mentioned.

The majority of the attempts made so far to provide a solution to this problem focused on the internal structure of snowboards. Variations in the materials used and their distribution within the core were attempted, however without significant results. Due to the proportional relation of the two characteristics, suffer in torsion snowboards were produced but all of them featured the unwanted effect of stiffening in flexion also. A small number of attempts upon solution have been conducted using a different approach focusing on the surface of the snowboard. However, these attempts have not produced significant results and did not manage to eliminate the torsional displacements of the board at high turning speeds.

The present invention, which is externally added on the snowboard, completely solves the above mentioned problems and produces a snowboard which experiences no torsional displacements, whereas at the same time leaves flexural stiffness unaffected and provides the ability to control it.

The advantages of the present invention are many and are discussed below. By maximizing torsional rigidity, (minimizing the torsional displacements), the control and accuracy of the snowboard during turning (carving) is greatly enhanced, thus providing the rider the ability to perform faster.

The snowboards and skis in general, are manufactured using synthetic materials, which are influenced by temperature variations, altitude and operational time (aging). With the present invention these crucial parameters are completely isolated from the performance of the snowboard/ski, as torsional rigidity and flexural stiffness are defined by the external system presented, bypassing the previous parameters stated.

Furthermore, by using this invention, the technical characteristics presented by the manufacturer, (sidecut radius etc.), will form a more realistic picture in terms of its real performance.

The latter can been comprehended by assessing the sidecut radius while it is distorted (in a normal snowboard) during turning, thus displaying a different value than that prescribed by the manufacturer.

Furthermore, by using the presented invention, rider's will have the opportunity of using softer boards (in flexural stiffness), thus faster boards without having the disadvantage of low torsional rigidity.

Finally, by modifying the invention slightly the ability to fully control and adjust the flexural stiffness of the board/ski is also possible.

The mechanism presented is identical for the front and rear part of the snowboard/ski. It can be positioned only at the front or at both front and rear parts depending on the rider's needs. The same invention can be implemented on skis and water skis by simply adjusting its geometrical characteristics as to fit on the required device (ie ski, water ski). The mechanism (Diagram 1, positioned on the front part of a snowboard, Diagram 2, the mechanism alone) consists of the following components. (a) One metallic or other material rigid bar (Diagram 2 no. 1 and Diagram 4, enlarged), which is positioned perpendicularly along the length of the board, (Diagram 1, between points A and B), and at the point where the effective edge of the board starts (defined in Diagram 1 as the distance between points A and C). On the upper part of this bar, (Diagram 4 no. 1), a pin is attached firmly (Diagram 4 no. 4).

(b) The mechanism that allows isolation of the flexural stiffness characteristic (Diagram 2, no. 2 and Diagram 5, alone), which is positioned directly under the front and/or rear binding, and consists of a track and ball device (Diagram 5, no. 5), which allow the longitudinal displacements (front and back) of the wagon (diagram 5, no. 6). On the upper segment of the wagon a pin is firmly attached (Diagram 5, no. 7). T e entire mechanism leads to a plate with holes (Diagram 5, no. 8), from which screws pass through and mount the binding and plate on the snowboard. The main characteristic of this track-wagon system is that the wagon is completely free to move along the length of the board (front-rear), whereas all other motions are completely prohibited. Inside the track-wagon device, a small adjustable damper can be attached, (Diagram 6, no. 9), or a selection of different stiffness springs , which will control the wagon's motion and thus adjust the flexural stiffness of the board. This damper or spring is required only if the ability to adjust the flexural stiffness of the board is of interest

(c) A bar (Diagram 2, no 3), from a rigid metallic or synthetic material, which is positioned throughout the length of the central axis of the board and is connected at one end with the pin (no.4), positioned on the rigid bar (no.1), and at the other end attached with the pin no.7. Instead of using one bar, the invention can be modified to feature two or more bars which will be connect as previously stated (one end at the rigid bar no.1 and at the other end with the pin no.7). Another version of the presented invention is the system illustrated in Diagrams 7 (placed only on the front part of a snowboard), 8 (isometric view) and 9 (side view). This system employs a different approach in satisfying the same core need and successfully maximizes the torsional rigidity of the snowboard.

In this system the no.3 rigid bar and the no.2 mechanism are modified. The rigid bar (no.3) consists of two parts telescopically connected, thus discarding the need for a track-wagon mechanism (no.2). The telescopic mechanism (Diagram 8, no.10,11), consists of two or more bars with square or rectangular cross-sectional areas, which slide inside one another, and thus providing the same end result as the track-wagon mechanism (Diagram 8, no.12). Furthermore, the mounting base has been simplified, and consists of a single pin (no.13).

In this version of the invention, adjustment of the flexural stiffness can be achieved by introducing a damper or a spring in the internal or external space of the telescopic bars (Diagram 10, no.14).

By employing one of the above present versions of the invention, the user experiences a system which completely removes torsional displacements of the snowboard while carving, without any effects on the flexural stiffness characteristic produced by the manufacturer. Furthermore, the flexural stiffness characteristic can be adjusted if necessary and desired by the user.

The invention can be comprehended further by assessing the diagrams provided, which present the following:

Diagram 1, depicts an isometric view of a snowboard with the mechanism positioned at its front part and also illustrates the segment which forms the effective edge (distance between points A and C).

Diagram 2, presents an isometric view of the mechanism with its three main components (1, 2 and 3).

Diagram 3, presents a side view of the system.

Diagram 4, presents the front rigid bar (1) which is oriented perpendicular on the board with its firm positioned pin (4).

Diagram 5, presents the system which ensures the unaffected flexural stiffness (2), and its core components (5, 6, 7, 8).

Diagram 6, presents the same mechanism as diagram 5 but with the addition of a damper (9), in order to adjust flexural stiffness. Diagram 7, presents a modification of the system, with the use of a telescopic bar on a snowboard.

Diagram 8, presents the system with the telescopic bar (10, 11) and the different rear mounting plate (12), with its pin (13).

Diagram 9, presents a side view of the system with the telescopic bar. Diagram 10, presents another modification of the system with the telescopic bar, and the external addition of a damper (14) to adjust flexural stiffness.

Claims

1. A system for the minimization of torsional displacements of the snowboard, which comprises of three parts (1), (2) and (3), that combine together to form one system.

The metallic or other material rigid bar (1), is attached with screws or by epoxy resin perpendicularly to the snowboard's axis at the point where the effective edge of the snowboard forms (A-f^"). A pin (4) is placed on the bar as shown.

The mechanism which preserves flexural stiffness unaffected (2), is positioned directly under the front and sometimes also rear binding (depending on the user's desire). This mechanism is a track and wagon component with ball bearings (5), and provides a joint with only one degree of freedom. One translation (6) (wagon moving in parallel with the snowboard's axis). A pin (7) is firmly attached on the mechanism as shown. The entire mechanism is mounted on a drilled plate using the binding screws, as shown. The vital characteristic of the track and wagon component is that it provides a single degree of freedom joint completely removing any other rotations or displacements. In particular, torsional displacements with respect to the snowboard's axis are removed.

The metallic or other material rigid bar (3), is aligned in parallel to the snowboard's axis, and is mounted using the pin (4) on the perpendicular rigid bar (1). At the other end the rigid bar (3) is mounted on the track and wagon mechanism (2), using a pin (7).

2. The system for the minimization of torsional displacements, according to claim 1, can be modified by replacing the parallel rigid bar (3) by two or more rigid bars which will be positioned in an arc manner, attaching their front end with the perpendicular bar (1). At their rear end, the bars can be attached to mechanism (2) using pin (7).

3. The parallel rigid bar (3) or the two or more rigid bars which may replace it, according to claims 1 and 2, can have quadrilateral or rectangular or eliptic or circular cross- section.

4. The system for the minimization of torsional displacements, according to claims 1 , 2 and 3, is characterized by the fact that internal to the mechanism for the preservation of flexural stiffness (2), and in particular, to the rear of the track (5) and wagon (6) arrangement a damper (9) or/and spring can be introduced. The damper or/and spring will be able to adjust to an extend the translatJonal motion of the single degree of freedom joint

The adjustable spring will be able to modify the flexural stiffness of the snowboard, whereas the damper will provide an adjustable damping characteristic to the snowboard.

5. The system for the minimization of torsional displacements, according to claim 1, can be modified by replacing the parallel rigid bar (3), with a telscopic boom consisting of two (10) or more (11) articulating bars moving one inside the other. The front end of the telescopic boom will be mounted on the perpendicular bar (1) using a pin as previously. At the rear end, the telescopic boom will be mounted using a pin (13) on a simple base plate (12), as shown. Θ.The system for the minimization of torsional displacements, according to claims 1 and 5, is characterized by the fact that the previously stated telescopic boom (10)(11), can have an rectangular, quadrilateral oreliptJcal cross-section.

7.The system for the minimization of torsional displacements, according to claims 1,5 and 6, is characterized by the fact that the previously stated telescopic boom (10)(11), can feature externally or internally a damper or/and spring, which will control the translational telescopic motion of the boom (in/out motion). Thus, the upward and downward motion of the snowboard tips (nose and tail) will be controlled, leading to control of the flexural stiffness of the snowboard.