Ski with a system for influencing its stiffness

Abstract: A system for changing the stiffness of a ski (107) includes a support plate (203) attachable to a ski and having a free end (207), and an adjustable stop (209) engageable with the free end of the support plate. This adjustable stop can make the system very soft such as for hard snow and very loose as for soft snow. The system can be positioned at different places on the ski to control the stiffness at different areas of the ski. A preferred embodiment however is a support plate for supporting the skiboot, to vary the underfoot stiffness of the ski.

Description: The invention relates to a ski provided with a system for influencing the stiffness of the underfoot area of a ski, this system comprising an elongated support means arranged in longitudinal direction of the ski, a first end portion of said support means fixed to the ski and a free end portion being movable in relation to the ski in longitudinal direction thereof, and an impedance means cooperating with said support means. Description of Background and Relevant Information A ski provided with such system is disclosed in EP-A 04 09 749 referring to a plate called Rossi-Bar which is slidably guided in longitudinal direction of the ski. The front and rear ends of said plate are engaged by spring means formed of elastomeric material and supported on the ski. The stiffness of the ski must be unavoidably increased under every condition, because the spring means exert a progressive force counteracting against flexing of the ski. An additional stiffness is caused by the fact, that the plate, which has the form of a rigid bar, is locked to the ski by clamps along the length of the plate, and it is the clamps which prevent the plate from sliding on the ski upon bending of the ski. Thus the plate reduces the bending of the ski. Important conditions affecting downhill skiers are the nature of the snow, the type of skiing to be done, the type of skis and bindings used and the skill of the skier. The snow and the ski run can vary during a day, while the ski and the skier are generally invariable. The snow can range from ice hard snow to very loose or soft snow, sometimes called powder snow. There are profound differences in skiing turns and speed according to the type of snow being skied upon. One primary characteristic of an ski is its ability to bend or flex as it carries a skier. A ski flexes and counterflexes, and keeps the skier in control as he or she follows the contour of a slope and enables a skier to manipulate the skis as he or she bounds and rebounds down the slope. In racing events, the snow can be ice hard both to increase the skier's speed and to avoid ruts in the snow. Hard snow may limit the bending of the skis. Turning is mainly accomplished in hard snow by the skier tilting the skis to dig the edges at the bottom of the ski into the snow by shifting his or her weight and body position. On the other hand, the ski can bend a large amount in powder snow. The longitudinal sides of skis are convex arcs, and it is through the use of the side cuts and bending of the ski that the skier turns; the edges of the skis are of much less importance in turning in powder snow. Regular snow, that is snow whose texture and packing is between hard snow and powder snow, presents other problems to the skier. Experience, communications with racers and other skiing experts, and testing, indicate that a ski stiffer underfoot of the ski boot may be preferable in very hard snow conditions while an overall more flexible ski appears to be preferable in soft snow conditions. An intermediate situation is preferable for snow of intermediate softness. It is also known that a ski loosely attached to the skier transfers little energy from the ski to the skier when the ski encounters obstacles, thus resulting in higher speed. However, a loose attachment results in loss of ski control in turns; hence it is desirable to have a loosely connected ski when traveling essentially in a straight line for greater speed and a tightly connected ski when making turns for greater control. The vibration characteristics of skis are also believed to be important. Skis have several vibration modes which are exhibited during skiing. High frequency vibrations break the contact between the ski bearing surface and the snow, which improves speed. On very hard snow conditions, the breaking of the contact between running surface and snow does not result in the same level of benefit but the ski still vibrates resulting in audible and perceptible chatter. A reduction in chatter is desirable in these condicions. Thus different requirements in underfoot stiffness and vibration exist depending on snow conditions. The ski designer, faced with the different kinds of snow, the different types of skiing, and variations in skiers and their bindings, can only develop skis which can handle all of these varying characteristics reasonably well but are not optimized for any specific condition. All ski bindings have an effect on ski stiffness underfoot. When a ski bends during skiing, the distance between the toe piece and the heel piece varies since they move relative to each other with the upward curvature of the ski. However, the length of the ski boot sole remains constant. Therefore, there is generally a limited movement rearwardly of the heelpiece in a clamp on the ski to keep it in contact with the boot. The force required to move the heel unit back results in a stiffening of the ski section directly under the binding and boot. It is believed that most ski bindings on the market fall into this category. Therefore ski manufacturers take this stiffening action of the binding system into consideration in the design of the ski. The underfoot stiffness of the ski binding combination is thus optimized for the type of skier and preferred snow conditions the ski was intended for. Different binding systems and separate devices to be used in conjunction with the ski and commercially available bindings have been manufactured to either increase or decrease the underfoot stiffness of the basic binding/ski configuration. Other devices can effect the normal vibration of an ski. Combinations which decrease stiffness underfoot may improve soft snow skiablility while deteriorating skiability towards the end of the hard snow spectrum. Combinations which increase stiffness have the opposite effect. In some systems, the binding is constructed to render the ski more flexible. In the ESS v.a.r. device, a boot support plate having a forward portion which is slidable in an channel on the ski, should render the ski more flexible. However, the support plate is fixed with additional fastening means to the ski, and thus is believed to limit its benefits on soft snow. The fixing of the support plate decreases the bending of the ski. The Tyrolia Freeflex system utilizes a flexible plate attached to the top of the ski. The plate is fixed to the ski at the toe of the binding and is held in place about the heel by a slidable clamp fixed on the ski. Both toe and heel binding units are affixed on the boot support plate. When the ski bends, the heel clamp moves closer to the toe unit but the flexible plate is allowed to slide rearwardly reducing the tendency of the heel unit to move towards the toe as in a normal binding configuration. The ski is thus allowed to flex more underfoot. The plate is allowed to move in the slidable clamp but is also held to the ski by an additional sliding point between the toe and the heel. This mounting configuration increases sliding friction and thus the overall decrease of ski stiffening is relatively small. Devices of this nature are disclosed in U.S. Patent 3 937 481. Most ski binding manufacturers produce bindings which increase the stiffness of skis. The stiffness of an ski provides a firm edge to drive into the snow for making turns in hard or intermediate snow. In this respect, it is much like an ice skater who drives his or her blade into the ice to make a turn. A flexible blade would detract from the skater making a turn, just as a very soft ski in the section directly below the boot would detract from the skier turning in hard snow. Some expert skiers performing giant slalom or super giant slalom have found that their turning ability is enhanced when they attach to the ski, such as by gluing, a thin plate on top of the ski in the binding area. This added plate increases the distance between the skier's boot and the edges of the ski, and enhances the leverage which the skier has to drive the edges of the ski into the snow. WIPO Document 83/03360 discloses a ski according to the preamble of claim 1, wherein glue and an elastomeric material hold a plate for supporting a toe piece and heel piece to the ski. The elastomeric material absorbs some of the vibration of the ski on the hard snow and relieves some of the discomforting noise of the ski rapidly smacking against the snow. Furthermore, the device stiffens the ski/plate/binding combination in the underfoot area of the ski improving edge control on hard snow. In U.S. Patent 3 937 481 mentioned earlier, a ski binding having an elongated plate is slidably mounted thereon for cushioning the skier when a forward abutment is encountered. Only the forward or toe portion of the system is fixed to the ski, so than the plate allegedly follows the bending of the ski. The device in fact impedes the bending of the ski since it is strapped to the ski in a number of places. A similar device with similar shortcomings is disclosed in Austrian Patent 373 786. A device of this type is sold under the name Derbyflex. It has been believed by many experts that raising the ski binding with such a plate detracts from the skier's ability to control the ski, since it was thought hat the skier had to be close to the snow to feel" the snow and ski accordingly. The present inventors and other manufacturers believe that this notion is wrong for most types of skiers, and that holding a ski boot somewhat high over the ski increases his or her ability to control the ski. Other patents disclosing ski bindings for increasing stiffness in skis include German Patent 21 35 450. Even though the added plate is beneficial, it only applies to skiing on hard snow where a stiffer underfoot ski is desirable. When used on softer or powder snow, the added stiffness detracts from the skier's ability to control the ski since easier bending adds to the turnability of the ski in soft snow. Other devices are known having moveable boot support plates on skis. For example, U.S. Patent 4 974 867 discloses a shock absorbing buffer disposed between a ski and a binding, and is not really related to the stiffness of the binding. The skill of the skier is another condition which the skiing apparatus should take into consideration. Although stiff skis are beneficial to good skiers in events such as giant slalom and super giant slalom, novice skiers should generally use flexible skis for all events, since they enable reasonable performance even though edge control in turns may be sacrificed. Brief Description of the Invention It is an object of the invention to improve a ski according to the preamble of claim 1 for controlling said ski according to the nature of the snow, the skiing to be done, the type of skis and/or the skill of the skier. It is a general object of the present invention to improve a ski according to the preamble of claim 1 for use with various types of snow, different degrees of skill of the skier and different skiing events, which system is efficient to manufacture and to use. The invention is characterized in that said impedance means comprises a stop cooperating with the free end portion of said support means, said stop being mounted on the ski in a preselected position in relation to said free end portion, so leaving an adjustable space between said free end portion and said stop, said stop is adapted to engage said free end portion upon longitudinal bending of the ski, whereby the stop only stiffens the ski when it engages the free end portion. In fundamental form, the invention includes a support means which is fixed, at a first end portion, to the ski, and a stop which is mounted on the ski and effectively engages the support means to change movement of the non-fixed free end portion of the support means as bending moments are applied to the ski. In its preferred form, the support means could be a support plate which supports a ski boot and runs substantially along the length of a ski boot and is attached to the ski. The plate is fixed to the ski at or near of its end. The other end of the plate is a free portion which slides longitudinally relative to the ski as the ski flexes or bends longitudinally about an axis or axes tranverse to the longitudinal direction of the ski. In this preferred embodiment, an adjustable stop is provided for selectively engaging the free portion of the plate to limit the relative movement of the plate on the ski. If the adjustable stop is moved away from the plate so that the plate cannot touch the stop, the plate becomes slidable relative to the ski as the ski bends. The adjustable stop can be moved to an intermediate position so that the plate can engage the stop only during turns where the ski bends beyond a determined amount, at which point the plate and stop become a stiffening member to preclude further bending of the ski at the plate and stop. As the ski unbends or before such bending occurs, there is a space between the stop and the plate so that the plate allows substantial bending of the ski. With respect to the foregoing discussion, it is an aspect of a preferred embodiment of the invention that the plate is fixed at its end, so that the other end of the plate is mounted for sliding relative to the ski, such as between lower and upper clamps or guides between which the plate can slide as the ski bends. An adjustable stop is provided near the free end. The adjustable stop can be moved between positions where it is totally disengaged from the ski plate or where it can engage or not engage the free end of the support plate according to the bending of the ski. The stop can be in different forms according to the various embodiments of the invention. It is possible that the plate be fixed in the ski and that the stop be slidable relative to the ski, with the same feature of controlling the stiffness of the ski as described above. According to a preferred embodiment the support plate includes an elongated main member, and a slide member which can be moved longitudinally on the main member to accommodate ski boots of different sizes. The rear or heel end of the main member is fixed to the ski, and the forward end of the main member has a bearing for the slide. At the forward end of the main member and slide member is an adjustable stop, which in this case is a disc cam. The disc cam is rotatable about an axis which is fixed to the ski. The disc cam has a set of surfaces which can be adjustably juxtapositioned to a forwardly facing surface on the slide member to control the amount in which the slide member and thus the support plate can slide on the ski, to thus control the bending or flexing of the ski. According to another embodiment of the invention, a support plate is fixed at one end to a ski, and has a slidable free end. The adjustable stop is a screw or screw driven member which is mounted in a housing fixed to the ski, and the screw can be adjusted to adjust the spacing between the stop and the plate. Brief Description of the Drawings The invention will be better understood when reference is had to the following drawings in which like numbers refer to like parts, and in which: FIG. 1 is a schematic drawing of a basic form of the invention, showing an engagement means as a support plate, and an impedance means as an adjustable stop, FIG. 2 shows a setting of the apparatus shown in FIG. 1, and FIG. 3 is a schematic drawing of the apparatus of FIG. 1, but with an adjustable clamp. Detailed Description of the Preferred Embodiments of the Invention The invention is directed to the changing of the stiffness of an ski. It includes a support means, which can be a member fixed relative to the impedance means described below (such as being fixed to a ski), and an impedance means which cooperates with the support means to change the stiffness of the ski. The support means moves relative to the ski as the ski bends, unless this movement is changed, such as by being restricted or stopped by the impedance means. In some forms of the invention, the support means is a plate fixed to the ski and the impedance means is a stop for engaging the plate to change - in this case increase - the stiffness of the ski by means of a discrete change such as to stop the articulation between the plate and the stop. The support means and the impedance means can be positioned at different places on the ski to control the stiffness at different areas of the ski. However, in its preferred embodiment, the support means is a support plate for supporting the ski boot on the ski, and the impedance means is an adjustable stop for engaging the support plate to vary the underfoot stiffness of the ski. The following discussion relates to various schematic drawings of different embodiments. A stiffness controlling assembly 101 is shown in FIG. 1. The assembly includes a support means which can be a support plate 103, one of whose ends 105 is fixed to the ski 107 as indicated by fastening member 108 and its second end 109 is a free end which can slide in a longitudinal direction of ski 107 within guide means such as a support clamp 111. For the sake of this discussion, second end 109 is closest to the forward end of the ski. An impedance means, shown here as an adjustable member, controll member or stop 113, can be moved forwards or rearwards to preselected positions as indicated by the arrow 115 within its holding member or clamp 117. As shown, adjustable stop 113 can be moved relative to plate 103 and ski 107, within clamp 117 as indicated by arrow 115. Referring to FIG. 3, a movable clamp 121 can be moved as well with stop 113 held therein for preliminary adjustments, such as by a store or ski shop, to set the stiffness controlling assembly for the type of ski and skill of the skier, as indicated by arrow 119. A space of variable distance between stop 113 and end 109 is designated by the letter S. When the ski is to have its bending unimpaired, stop 113 is moved away from plate 103 as shown in FIG. 1, with S having a relatively high value. Then, regardless of the bending of the ski 107, plate 103 cannot engage stop 113, and no additional stiffness is added to the ski. For an intermediate stiffening condition, as where the skier is making turns on regular snow, S is set to a moderate value as shown in FIG. 2, so that free end 109 only contacts stop 113 during turns when the ski bends sufficiently for the contact to occur, to avoid further bending and improve edge control. The assembly could be arranged so that stop 113 is only set for intermediate stiffness control as shown in FIG. 2 in which holder 117 would not allow the adjustment of stop 113. If S is very small, the ski becomes very stiff beneath plate 103, such setting is preferred, when the ski is to be turned in hard snow. The support plate 103 has been shown as an integral member, but it could include a number of members whose effect is as shown for stiffening the ski. Likewise, the adjustable member or stop can have different forms. The stop can comprise a retainer means which is adapted for being urged forwardly or backwardly by a screw to have an adjustable space S between contact surfaces of said retainer means and the free end portion of the support plate. The adjustable stop 113 can also be a disc cam which is rotatable about an axis fixed to the ski. Said disc cam can have a set of surfaces for cooperating with the free end portion 109 and being adjustably juxtapositioned to a facing surface of said free end portion 109. Various skis provided with a system for controlling the stiffness of the ski have been described above. The skier may manually, or perhaps with the ski pole or some other device, adjust the ski according to the type of stiffness to be desired. The skier need not have different skis for different types of snow of different abilities of the skier, and need not settle for a binding which is appropriate for only one type of skiing or which approximate different types of skiing but cannot adequately control the stiffness precisely for different types of skiing. Now, the skier need only adjust the ski for the type of stiffness desired and to participate in the skiing event. The settings can be changed as the skier desires. Furthermore, in some embodiments the skier can continuously adjust the stiffness of the ski. The adjustable member could be at places other than at the forward end of the support plate, such as at the rear end. Although many embodiments are given, it should be appreciated that other variations will fall within the scope of the invention.

Claims: A ski provided with a system for influencing the stiffness of the underfoot area of the ski, this system comprising an elongated support means (103) arranged in longitudinal direction of the ski (107), a first end portion (105) of said support means fixed to the ski and a free end portion (109) being movable in relation to the ski in longitudinal direction thereof, and an impedance means cooperating with said support means (103), characterized in that said impedance means comprises a stop (113) cooperating with the free end portion (109) of said support means (103) said stop being mounted on the ski in a preselected position in relation to said free end portion, so leaving an adjustable space (S) between said free end portion and said stop, said stop is adapted to engage said free end portion (109) upon longitudinal bending of the ski, whereby the stop (113) only stiffens the ski when it engages the free end portion. A ski provided with a system according to claim 1, characterized in that said support means (103) is formed by a support plate for supporting a ski binding. A ski provided with a system according to claim 1 or 2, characterized in that said stop (113) is adjustable for adjustment of the said space. A ski provided with a system according to claim 3, characterized in that said stop (113) is continously adjustable. A ski provided with a system according to one of claims 1 to 4, characterized in that said stop (113) has a movable clamp for preliminary adjustment. A ski provided with a system according to one of claims 1 to 5, characterized in that said stop (113) comprises retainer means having contact surfaces, said retainer means being rotatable by different amounts about an axis to locate said contact surfaces in the path of said free end portion (109) to operatively engage said free end portion by varying amounts. A ski provided with a system according to one of claims 1 to 6, characterized in that said stop (113) is a disc cam which is rotatable about an axis fixed to the ski and has a set of surfaces for being adjustably juxtapositioned to a facing surface of the free end portion (109). A ski provided with a system according to one of claims 1 to 7, charaterized in that the support plate (103) includes an elongated main member, and a slide member which can be moved longitudinally on the main member to accommodate ski boots of different sizes.

Inventors: LEHNER EDWIN, RUFFINENGO PIERO G, STEPANEK PREMEK, WAGNER LUDWIG, LEHNER, EDWIN, RUFFINENGO, PIERO G., STEPANEK, PREMEK, WAGNER, LUDWIG
Applicants: MARKER DEUTSCHLAND GMBH
Application year: 1991
Main classification: A63C5
IPC codes: A63C5, A63C9