SKIING

Technical Field

The present invention relates to a cross-country ski for classic crosscountry skiing, including a gliding phase and a kicking phase, comprising a common, continuous lower surface having a front and a rear glide zone and a central grip zone, the ski being formed with a central upward bent camber, which exerts a camber force against depression of the camber, such that in the gliding phase the ski is able to bear the weight of a skier while maintaining the central grip zone spaced from an underlying snow surface, whereas in the kicking phase, when the skier is exerting a kicking force towards the ski, the camber force is overcome and the grip zone is pressed towards the underlying snow surface, the ski additionally comprising a front part, a rear part and a camber regulating mechanism, said front part and said rear part being joined by an intermediate low flexural resistance portion of the ski having a reduced flexural resistance in comparison to adjacent portions of the ski, wherein the camber regulating mechanism has a high camber state and a low camber state where said high camber state is a state when the camber is maximally curved upwards and the grip zone is not in contact with the underlying snow surface, whereas the low camber state is a state when the camber is low and the grip zone is in contact with the underlying snow surface.

Background of the invention

A classic cross country ski is generally cambered in order to provide good gliding properties. This camber acts as an arched blade spring. The stiffness and height of the camber is selected to match the weight of the skier. When the skier applies all his weight on the proper position on one ski the stiffness of the camber should allow the grip zone to at least partly touch the snow. In addition, the contact between the grip zone and the snow is improved when the skier kicks his foot in a downward direction. The camber is often constructed in a manner such that the contact is further improved when the skier applies his weight and kicking force on the ball part of the foot. In the gliding phase, on the other hand the skier applies more weight towards the heel region. The grip zone of the ski has a surface with grip wax or any other means of resisting backward movement, such as scales, seal skin, anti- backward movement chemical coating, etc. This grip wax, or any other means, is only effective when in contact with the snow with significant pressure, in order to, during the kicking phase, stopping the ski from sliding back by the positive reaction that the underlying snow can then exercise on the ski.

For a traditional ski, basically adapted to classic cross-country strides, it can be noted that the aforementioned pressure distribution along the ski is not ideal. In an ideal situation all the forces from the skier's weight and kicking action should be distributed in the grip zone. The reason for this is to replace the glide in the gliding phase against the grip in the gripping phase. However, in skis with traditional camber a significant portion of the forces will be distri- buted in the gliding zones. The stiffer the camber is, the better the glide is, and the softer the camber is, the better the grip is. Professional ski racers usually have stiffer camber, due to the large kicking and poling forces they can apply. Recreational skiers usually have softer camber, which will give a poor glide.

There are various prior art that try to alleviate the alteration problem between grip and glide. In US4300786, US4221400, US7360782,

US 201 1/0233900 A1 and US4754989 different systems for statically changing the amount of camber resistance are described. This does not solve the alteration problem between gliding and gripping, it merely accomplishes a change towards better or worse glide and correspondingly worse or better grip.

In US5427400 a change in the characteristics of the camber is obtained by having more camber resistance when standing on the heel compared to when standing on the ball part of the foot. A slit in the base of the ski is used to solve this. This would likely not be significantly more efficient than placing the ball of the foot more towards the center of the camber, and the heel more towards the rear, which is the current state of the art used in skis on the market. Similarly in US 5829776 a change in the characteristics of the camber is obtained, but only by utilizing the pressing down of the heel which then activates a plate pushed forward to hook up with the front part of the binding for increased stiffness. This is quite limited since lower camber is achieved only when lifting the heel. The problem with this is that it forces the skier to lift the heel in order to decrease the camber. Lifting the heel does not normally occur in the initial part of the push down phase. Yet another problem with this approach is that the camber is stiffened when more weight is applied, whereas the ideal is that the camber should be less stiff when a lot of weight is applied in the kicking phase.

Summary of the invention

An object of the present invention is to overcome at least the mentioned disadvantages and provide a ski by which it is easier to achieve a good grip as well as a good glide in relation to prior art skies. At least this object is achieved by a ski according to claim 1 .

Accordingly, the basis of the invention is the insight that at least the above object may be achieved by a ski, which is formed with a low flexural resistance portion, having a low resistance against bending in comparison to adjacent portions of the ski, at an intermediate part of the ski in an area of a grip zone of a common, continuous lower surface. Moreover, the ski is provided with a camber regulating mechanism, which is bridging over the low flexural resistance portion and is designed such that it at least at an initial high camber state, at which the camber of the ski is maximally bent upwards, contributes to a camber force acting to maintain the high camber state and counteracts bending of the ski downwards, i.e. depressing of the camber, due to the weight and kicking action from the skier. The counteracting action of the camber regulating mechanism has a maximum at the high camber state or at a dead center position between the high camber state and a low camber state when the camber is depressed such that the grip zone bears against an underlying snow surface. As soon as the counteracting action of the camber regulating mechanism is overcome, by a sufficient kicking force from the skier, the overall, aggregated resistance against downward bending of the camber, which partly arises from the ski, i.e. primarily from the low flexural resistance portion of the ski, as well as from the camber regulating mechanism, the counteracting action against depression of the camber decreases such that the grip zone at the lower surface of the ski may securely bear against the snow surface without need for any large downward acting force from the skier.

Within this overall inventive idea, the invention can be varied and modified in many different ways. In the following detailed description accompanied by the drawings, a number of conceivable embodiments are presented. However, it is to be understood that also many other embodiments are possible within the overall scope of the invention as defined by the claims.

For example, the camber regulating mechanism can be designed such that the resistance against camber depression has a maximum at the highest camber state of the ski, after which the force acting against camber compression is decreasing, or it can be designed such that the required force for depressing the camber is increasing a small distance from the highest camber state of the ski until a so called dead centre position is reached, in which the force acting against depression of the camber has its maximum, after which the camber force is decreasing towards the low camber state. A camber regulating mechanism having a dead centre position can be designed such that the camber regulating mechanism essentially "collapses" after it has been passed over the dead centre position, such that the mechanism gives no further contribution to the camber force and instead the residing camber force comes entirely from the low flexural resistance portion of the ski. A camber regulating mechanism having no such dead center position, on the other hand, does not "collapse" but contributes with a gradually decreasing camber force towards the low camber state. Normally, a camber regulating mechanism according to the invention requires some form of spring member to bring back the mechanism to the high camber state when the kicking face is completed. The spring member could for example be a metallic coil spring or an elastic material, such as rubber or plastic. However, it could be conceivable to accomplish the resetting of the regulating mechanism to the high camber state without use of any spring member by letting for example an inherent elasticity in the ski, and particularly in the low flexural resistance portion of the ski, reset the mechanism into the high camber state.

Also, the low flexural resistance portion according to the invention may be designed in many different ways. In the hereinafter described and illustrated embodiments of the invention, the low flexural resistance portion, as seen in the longitudinal direction of the ski, is formed as a curved recess in the upper middle part of the ski. The recess is preferably covered by the camber regulating mechanism and is also preferably completely or partly filled with an elastic material, such as rubber or plastic in order to prevent penetration of snow and water into the recess. However, it is to be understood that the low flexure resistance portion also could be formed in many other ways which will lower the flexural resistance of the ski ^' s cross section in relation to adjacent portions of the ski. It would even be possible to form the low flexural resistance portion as a hinged joint being provided with a hinge mounting at the area just above the lower running surface of the ski.

A traditional camber acts similarly to a blade spring, and thus provides progressive resistance against the applied force. The camber of a ski accord- ing to this invention is a camber where the resistance initially acts as a normal progressive camber, but above a certain adjustable threshold in applied downward force or other action the camber collapses almost completely and thus distributes all the forces in the grip zone. In the following this state is called low camber state, and before the aforementioned collapse the ski is said to have a high camber state. Such a camber is obtained by different mechanisms which are further described in the embodiments and figures.

According to a first aspect of the present invention, the camber force is achieved by having a ski that comprises a front and a rear part. The parts are joined by a common, continuous lower surface. The lower surface has two glide sections, at the front and rear respectively, and one grip section in between. The front and rear parts are also joined by a low flexural resistance portion. The front and rear parts have a camber regulating mechanism at- tached to the upper surfaces of the front and rear parts of the ski which is bridging over the low flexural resistance portion. This camber regulating mechanism basically comprises a wedge that is wedged between the upper edges of the front and rear parts of the ski when the ski has a high camber state. This wedge is spring loaded so that it can be pushed down only if a downward force is applied which is larger than a predetermined and adjustable level. This downward force is created by the skier. When the skier applies enough force the wedge will be pushed down, and the upper parts of the front and rear parts of the ski will come closer together, thus putting the ski in a low camber state with good gripping properties. This low camber state will remain until the skier removes the downward force, then the spring loaded wedge will be pushed up between the upper parts of the front and rear sections again, and thus restoring the ski into a high camber state with good gliding properties.

According to a second aspect of the present invention, a camber regulating mechanism is achieved by having a ski that comprises a front and a rear part. The parts are joined by a common, continuous lower surface. The lower surface has two gliding sections, at the front and rear respectively, and one grip section. The front and rear parts are also joined by a low flexural re- sistance portion. The upper part of the rear part has an extension that extends out above the front part. At the end of this extension is a joint or hinge with a planar structure attached. This planar structure goes against the upper part of the front part of the ski with a slight forward angle. The planar structure is also spring loaded, so that it can only move if the ski is loaded with enough force. The mentioned angle is selected so that the spring does not have to be strong. When the ski is loaded with enough force the lower end of the planar structure will glide along the surface of the front part of the ski, which should have low friction. The upper part of the planar structure will rotate around the hinge attached to the extension. As the planar structure glides further the an- gle will change and thus less and less force is required to push it down.

Hence the extension will move downward until it touches the upper part of the front part. Thus the described mechanism have collapsed into a low camber state, and similarly to the first aspect of the invention this low camber state will remain until the skier removes the downward force, then the spring loaded planar structure will be pushed back again, and thus restoring the ski into a high camber state with good gliding properties. In a variant of this aspect of the invention the spring is located in the hinge attached to the extension instead.

According to a third aspect of the present invention, a ski according to the invention having a camber is achieved similarly to the second aspect except that instead of a hinge and a planar structure the extension pushes down on a canted wedge, which glides on the upper surface of the front part, and which is spring loaded. When enough force is applied the wedge glides away and the extension becomes free to collapse against the front part of the ski. The transitions between the different camber states are similar as the two first aspects of the invention.

According to a fourth aspect of the present invention, a ski according to the invention having a camber is achieved similarly to the third aspect of the invention except that instead of gliding at least one of the wedge and the extension has a rolling bearing for reduced friction.

According to a sixth aspect of the present invention, a ski according to the invention having a camber is achieved by having spring plate being formed with an arched cross section internally in the ski or externally to the ski. The spring has a property that it has two stable states, one where it is curved in one direction, and one where it is curved in the other direction. Between these two states there is a sharp transition point, where the force of the spring changes polarity. A double curvature spring is used with a transition point that gives the ski a dynamic camber as described for the other aspects of the invention. As a reference it can be mentioned that perhaps the most common use of double curvature springs is for self wrap around reflectors and toys.

According to a seventh aspect of the present invention, a ski according to the invention having a camber is achieved by having a ski with two gliding sections, at the front and rear respectively, and one grip section. The front and rear parts have upper surfaces that are joined by a camber regulating mechanism that is attached to these upper surfaces. This camber regulating mechanism basically comprises two plates that are joined together by three hinges, two of which are attached to the upper parts of the front and rear part of the ski, and one which attaches the two plates. Also part of the construction is a pushing spring that pushes the middle hinge upwards. The hinges are constructed with a limited range of motion that limits how high the spring can push the middle hinge. When no external force acts on the dynamic camber mechanism the ski takes a high camber state. When enough external down- ward force is applied to the mechanism, said mechanism collapses and the ski takes a low camber state. The ski returns to a high camber state when the external force is removed.

According to an eighth aspect of the present invention, a ski according to the invention having a camber is achieved by combining any of the above camber regulating mechanisms with electromechanical or electromagnetic mechanisms. All spring loaded parts can be replaced with electrical engines or electromagnets. By doing this it is possible to base the release point on other aspects than a force threshold. For example the release can be based on sensors such as accelerometers, pressure sensors, foot position, speed etc.

According to a ninth aspect of the present invention, a ski according to the invention having a camber is achieved by combining one of the previous camber regulating mechanisms with a ski binding. In particular the ski binding constitutes the spring part of the camber regulating mechanism. In addition the binding can be adjusted so that the activation of the camber regulating mechanism is not only controlled by the amount of force applied, but also the ratio of force between the ball and heel region of the binding.

An advantage with embodiments of the present invention is that they provide a ski with both good glide and grip properties simultaneously.

A further advantage is that since with the invention camber height can be designed with a significant gap between the lower surface and the snow it is possible to have structures with very good grip characteristics, such as fish scale etc.

Brief description of the drawings

Exemplary embodiments of the invention will hereinafter be described with reference to the accompanying drawings, in which:

Fig 1 illustrates a classic cross country ski which is loaded with approximately half of the skier's weight.

Fig 2 illustrates a classic cross country ski which is loaded with the

skier ^' s full, bodyweight.

Fig 3 illustrates a classic cross country ski which is loaded with the

skier ^' s full bodyweight plus the forces generated from a kicking action of the skier.

Fig 4 illustrates a classic cross country ski with a camber regulating mechanism according to the present invention and how the forces are distributed.

Fig 5 illustrates a classic cross country ski with a camber regulating mechanism according to a first embodiment.

Fig 6a-b illustrates an enlarged version of the mechanism in fig. 5 in a high camber state and a low camber state, respectively.

Fig 7 illustrates an enlarged version of second camber regulating mechanism. The mechanism is in high camber state.

Fig 8 illustrates an enlarged version of a third embodiment of a camber regulating mechanism. The mechanism is in high camber state. Fig 9 illustrates an enlarged version of a fourth embodiment of a camber regulating mechanism. The mechanism is in high camber state. Fig 10 illustrates an enlarged version of a fifth embodiment of a camber regulating mechanism. The mechanism is in high camber state. Fig 1 1 illustrates an enlarged version of a sixth embodiment of a camber regulating mechanism. The mechanism is in high camber state. Fig 12a-d illustrates a classic cross country ski according to a seventh embodiment of a camber regulating mechanism in form of a spring plate having an arched cross section.

Fig 13a-b illustrate enlarged versions of an eighth embodiment of a camber regulating mechanism.

Fig 14a-c illustrate enlarged versions of a ninth embodiment of a camber regulating mechanism.

Fig 15a-c illustrate enlarged versions of a tenth embodiment of a camber regulating mechanism.

Fig 16 illustrates a first embodiment of how the ski boot can be attached to the ski for optimal activation of the camber regulating mechanisms.

Fig 17 illustrates a second embodiment of how the ski boot can be attached to the ski for optimal activation of the camber regulating mechanisms.

Detailed description of embodiments of the invention

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like reference signs refer to like elements.

Moreover, those skilled in the art will appreciate that while the current invention is primarily described as a device that is part of a ski, the invention may also be embodied in ski bindings as well as other devices external to the ski that may perform the functions disclosed herein.

In addition is should be clear to those skilled in the art that the drawings are not completely detailed and in the correct scale. For the sake of illustrative purposes some parts are displayed larger and disproportionate compared to reality.

Fig. 1 illustrates an approximate overview of how the vertical forces affect a classic cross country ski 1 when it is partly loaded. This is for example a common situation when the skier is double poling, so that approximately half of the skier's weight is on one ski. In this case it can be seen that the force is distributed onto a common, continuous lower surface 2 of the ski 1 in a front glide zone 3 and a rear glide zone 4.

Fig. 2 illustrates a typical overview of how the vertical forces affect a classic cross country ski when it is loaded with most of the skier's weight. This is for example a common situation when the skier is gliding on one ski after kicking with the other, so that approximately the entire skier's weight is on one ski. In this case it can be seen that the force is distributed on the lower surface 2 of the ski 1 in the front glide zone 3 and the rear glide zone 4, but compared to fig. 1 it can be noted that now parts of the force also is distributed over a middle grip zone 5, as illustrated by dotted force lines. It should be obvious to anyone skilled in the art that for this reason the illustrated camber is not ideal for gliding on one ski.

Fig. 3 illustrates a typical overview of how the vertical forces affect a classic cross country ski when it is loaded with all of the skier's weight plus an additional force caused by a kick from the skier in the kicking phase. This is for example a common situation when the skier is skiing with alternating steps and is kicking to produce a forward momentum. In this case it can be seen that the force is distributed on the lower surface 2 of the ski 1 over the front glide zone 3 and the rear glide zone 4, but compared to fig. 2 it can be noted that now a significant part of the force is also distributed over the grip zone 5, as illustrated by the dotted force lines. However, most of the force is still distributed over the glide zones 3 and 4. Thus it should be obvious to anyone skilled in the art that the illustrated camber will not give an ideal grip.

Fig. 4 illustrates a typical overview of how the vertical forces will be distributed in the kicking phase when a ski according to the present invention is used. The total force comes from the skier's weight plus an additional force caused by the kick in the kicking phase. This is for example a common situation when the skier is skiing with alternating steps and is kicking to produce a forward momentum. In this case it can be seen that some force is distributed on the lower surface 2 of the ski 1 over the front glide zone 3 and the rear glide zone 4, but compared to fig. 3 it can be noted that now a only a very small part is distributed over the glide zones, and that most of the force is distributed over the grip zone 5, as illustrated by the dotter force lines. It should be obvious to anyone skilled in the art that a ski according to the invention will give a much better grip than a conventional classic cross-country ski.

Fig. 5 illustrates a typical overview of an embodiment of the invention.

A classic cross country ski 1 is shown being provided with a camber regulating mechanism 6 according to the invention. In all of the following figs. 5-17 also an intended position of a ski boot 7 is schematically illustrated, however without any ski binding since any type of ski binding for classical skiing could be used to connect the ski boot with the ski. In connection with the description of the following figs. 16 and 17, two examples of conceivable structures for operating a camber regulating mechanism will be presented.

In the enlarged views of figs. 6a and 6b is schematically illustrated a first embodiment of a ski according to the invention. The camber regulating mechanism according to this embodiment comprises a number of parts, of which only the most important ones are shown for clarify of presentation. The ski 1 is formed of a front part 1 ¹ and a rear part 1 ² , which are joined by an intermediate positioned low flexural resistance portion 8 having a lower flexural resistance in comparison to the adjacent portions of the front and rear parts 1 ¹ , 1 ² . The low flexural resistance portion is in this and the following embodiments realized by forming a recess 9 in the upper part of the ski.

Accordingly, the low flexural resistance portion 8 will function as a joint around which the ski easily can deflect when going from high camber state to low camber state and back again. Preferably, the recess 9 is filled with som kind of substance being elastic but having a low flexural rigidity. The ski is, as is mentioned before in relation to figs. 1 -4, provided with a common, continuous lower surface 2 having a front glide zone 3, a rear glide zone 4 and a grip zone in an area beneath the low flexural resistance portion 8. The camber regulating mechanism 6 is bridging over the low flexural resistance portion and interconnects the front and rear parts 1 ¹ , 1 ² such that the camber regulating mechanism, in a high camber state as is illustrated in fig. 6a, contributes to the overall camber force acting against depression of the camber. As can be seen from the figures, the grip zone 5 of the lower surface of the ski, is in the high camber state, as is illustrated in fig. 6a, cambered or arched upwards such that the grip zone 5 is not in contact with an underlying snow surface 16. In a low camber state on the other hand, the grip zone 5 bears against the snow surface 16, as is illustrated in fig. 6b. The camber regulating mechanism according to this embodiment, comprises two plates and more precisely a front plate 10, which is attached to the upper portion of the front part 1 ¹ , and a rear plate 1 1 , which is attached to the upper portion of the rear part 1 ² and they are positioned such that there is formed a small gap between them. A first angle member 12 is rotatable attached to the lower surface of the front plate 10 and is formed with an upward directed part 13, which is somewhat wedge-shaped. A second angle member 14 is rotatable attached to the upper surface of the rear plate 1 1 and is formed with a downward directed part. In the high camber state, according to fig. 6a, the upward directed part 13 of the first angle member 12 is positioned in the gap between the front and rear plates, such that depression of the camber is prevented. In the kicking phase, as is illustrated in fig. 6b, the second angle member 14 is pressed down by means of a not shown mechanism when the skier lifts the heel of the ski boot. This has to result that the upward directed wedge formed part 13 will be pressed out from the gap between the plates 10 and 1 1 by means of the downward directed part of the second angle member. Thereby, the front and rear plates 10, 1 1 can move closer to each other and the ski will assume a low camber state according to fig. 6b. When the kicking phase is completed and the skier lifts the ski, the camber regulating

mechanism will return to the high camber state, according to fig. 6a, by means of a spring member 15 which will press the upward directed part 13 into the gap between the plates 10, 1 1 . The spring member can be a coil spring, as is illustrated in the drawings, but it can also be constituted of an elastic substance positioned in the recess 9.

Fig. 7 illustrates an embodiment, which is similar to the embodiment of figs. 6a, 6b. The difference in this embodiment is that no angle members are provided. Instead, a wedge member 17, which is forced upwards by a spring member 15, projects over the upper surfaces of the plates 10, 1 1 and can be pressed downwards by means of a not shown mechanism when the skier lifts the heel from the ski in the kicking phase.

Figs. 8-1 1 illustrates embodiments of camber regulating mechanisms where a plate 18 is rigidly attached to the rear part 1 ² and extends out over the upper surface of the front part 1 ¹ such that there is formed a gap between the front part and the front end of the plate 18. In the various embodiments different mechanisms are provided in the gap which exerts a resistance force against lowering the front portion of the plate 18 towards the upper surface of the front part 1 ¹ and thereby depression of the camber. The resistance force is as largest in the beginning of the movement of the plate towards the front part of the ski and is successively decreasing when the plate and front part are approaching each other. In fig. 8 the mechanism comprises a plate 19, which is rotatable attached in its upper end to the lower surface of the plate 18 and is in its lower end slidable against the upper surface against the action of a spring member15, the spring force of which can be regulated by means of a threaded member 20. A stop member 26 prevents rotation of the plate 19 backwards and ensures a small initial angle between the plate and the upper surface of the ski which allows sliding when a sufficient force is applied to the plate 18. In fig 9 the plate 18 is provided with a projection 22, which is slidable against an inclined upper surface of a wedge member 21 against the action of a spring member 15. The embodiment according to fig. 10 is similar to fig. 9 with the only difference that the wedge member is provided with roller bearings 23 at the lower surface for the purpose of reducing friction. The embodiment according to fig. 1 1 is similar to the embodiment of fig. 8, but here a torsion spring 24 is integrated with the plate 24 which forces the plate to rotate counter-clockwise around the rotatable joint 25. Figs. 12a-12d illustrates an embodiment where the camber regulating mechanism comprises a spring plate 27, which is accommodated in a recess 9 inside the ski and which in a high camber state, according to figs. 12a and 12b, has an arched cross section as is seen in fig. 12b. In this high camber state, the spring plate 27 has a large resistance against bending and will contribute with a large camber force to the ski. However, when a sufficient kicking force is applied to the ski by the skier, as is illustrated in figs. 12c and 12d, the arched cross section will be flattened, as is illustrated in fig. 12d, which will drastically decrease the flexural resistance of the spring plate 27 and it will collapse as is shown in fig.12c. Thereby, the overall camber force of the ski will be lowered such that the grip zone 5 easily can be pressed down to bear against the snow surface 16.

Figs. 13a and 13b illustrates an embodiment having a front plate 10 attached to the front part 1 ¹ and a rear plate 1 1 attached to the rear part 1 ² . A gap is formed between the plates 10 and 1 1 in which two turnplates 28 are arranged. The turnplates 28 are rotatably attached to each other and to a respective edge of the plates 10 and 1 1 . In the high camber state, according to fig. 7, the turnplates 28 are somewhat angled upwards in relation to each other which will impart a large overall camber force to the ski. When applying a sufficient kicking force, as illustrated in fig. 13b, the turnplates 28 will rotate such that they become angled downwards in relation to each other. The camber force contribution from the camber regulating mechanism will then drastically decrease such that the residual camber force will essentially solely derive from the low flexural resistance portion 8 of the ski and the grip zone 5 can accordingly easily be pressed onto the snow surface 16. A spring member 15 is arranged for returning the camber regulating mechanism to the high camber state after the kicking phase.

Figs. 14a-14c illustrates an embodiment comprising two plates 30 and 31 , which are attached to the front part 1 ¹ and the rear part 1 ² of the ski, respectively. The ends of the plates 30, 31 includes engagement formations in form of step formations 32 and stop members 33. A spring member 15 is arranged to bring the plate 31 to an upper position, according to figs. 14a and 14b, in which the aggregate length of the two plates 30, 31 is as longest and which they adopt in the high camber state. Accordingly, abutting of the two plates 30, 31 against each other prevents depression of the camber. When in a kicking phase, the force from the spring member 15 is overcome, the plate will be pressed downwards in relation to the plate 30 and in this position the two plates 30, 31 can be displaced towards each other such that the aggregate length of the two plates will decrease, as is illustrated in fig. 14c. In this position the camber of the ski can easily be depressed for pressing the grip zone 5 against the snow surface 16.

Figs. 15a-15c discloses yet another embodiment of a ski according to the invention. Also here the camber regulating mechanism comprises two plates 34,35, which are attached to the front and rear parts 1 ¹ and 1 ² , respectively. Each of the plates 34, 35 is formed with a recess 37 in the ends facing each other and there is a small gap between them. Two turnplates 36 are positioned in the recesses, the edges of which bears against each other. A spring member 15 acts with an upward directed force on the turnplates 36 to bring to an upper high camber state, as is illustrated in figs. 15a and 15b. In this position the turnplates 36 prevent displacement of the plates 34 and 35 towards each other and accordingly the high camber state is maintained. In the kicking phase a not shown mechanism can act on the turnplates and force them downwards to the position illustrated in fig. 15c, preferably by means of a member which can be introduced through the gap between the plates 34 and 35. In this position the plates 34 and 35 can be displaced towards eachother and in this position the camber of the ski can easily be depressed for pressing the grip zone 5 against the snow surface 16.

Fig 16 illustrates a conceivable embodiment of an operating

mechanism to accomplish operating of a camber regulating mechanism according to the embodiment of figs. 6a-b. However it should be understood that the operating mechanism, with some minor adjustments, could be used to operate also the other camber regulating mechanisms as disclosed herein. The operating mechanism comprises a tilting plate 38, which is rotatably arranged around a rotary joint 39 on the upper surface of the rear part 1 ² of the ski. A not shown ski binding are to be attached to the tilting plate 38 in order to connect the ski to the ski boot 7. In a gliding phase, as is illustrated in fig. 16, the skier stands with heel towards the tilting plate 38 such that a forward end of the tilting plate 38 is positioned a distance above the camber regulating mechanism 6. The ski will then assume a high camber state in which the grip zone is not in contact with the snow surface. When on the other hand the skier in the kicking phase puts the weight and force towards the ball of the foot, the tilting plate 38 will tilt forward such that the camber regulating mechanism is depressed and the ski will assume the low camber state.

In fig. 17 is illustrated a second embodiment of an operating

mechanism in combination with yet another embodiment of a camber regulating mechanism. Here the operating mechanism comprises a bracket plate 40, which is attached to upper surface of the rear part 1 ² of the ski by means of two attachments 41 , which are arranged in the rear end and at an intermediate position and which maintain the bracket plate on a small distance from the upper surface. Accordingly, the forward end of bracket plate will extend over the camber regulating mechanism and by placing the weight and a kicking force towards the ball of the foot, the bracket plate 40 will deflect and can accordingly operate the camber regulating mechanism. This embodiment of the camber regulating mechanism is somewhat similar to the embodiment according to figs. 6a-b but with the difference that the bracket plate 40 acts directly onto a wedge member. On order to reinforce the bracket plate 40, an upward projecting flange 42 is arranged on the upper side of the bracket plate. The flange may be accomodated in a groove in the sole of the ski boot 7.

The present invention is not limited to the above-described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the invention, which is defined by the appending claims.

For example, instead of using spring members, the springs could be replaced by an electrical device, such as an electromagnet or an electrical engine. Furthermore, the release need not be activated by a force threshold. The activation could instead be based on electrical sensors such as accele- rometers, pressure sensors, speed sensors, the outputs of which are processed by a microprocessor. That microprocessor then activates the elec- trical engine or electromagnet.

In yet another variant the heel could be connected to the deactivation of the camber regulating mechanism, in such a way that the camber will only return to high camber state if the heel is lifted from the ski.

In yet another variant the heel could be connected to the activation of the camber regulating mechanism, in such a way that the camber will only transition to low camber state if the ratio between the heel pressure and the ball pressure is within a certain interval. For example if most of the weight is on the heel the transition to low camber state will not be activated.