Abstract:
A stiffening or damping apparatus for sliding boards or skis, comprising a force transmission blade ( 20 ) attached to the sliding board ( 10 ) for transmitting vibrational, twisting or bending energy and a clutch element for engaging the force transmission blade. The clutch element ( 26 ) can be constructed to engage in both directions of ski bend over only a portion of total possible movement, or to frictionally engage ( 44 ) in only one direction of ski bending. These clutch devices allows the ski to be damped or stiffened only for small ranges of vibrational movement or to be inhibited in a single direction of bend or torsion.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Invention  
           [0002]    This invention relates to a control apparatus for varying the damping or stiffness characteristics of a sliding board, snowboard or ski according to the nature of the snow, the activity of the user and the dynamic conditions encountered, to improve the quality of the skiing and safety of the skier.  
           [0003]    2. Description of Background and Relevant Information  
           [0004]    Modern skis and sliding boards are typically built with a multiplayer composite construction consisting of resilient materials. Skis usually include features for damping the vibrations of the ski resulting from the spring characteristics of the resilient materials interacting with the varied and uneven terrain encountered by a skier. An example of ski construction incorporated viscoelastic material is depicted by Caldwell (U.S. Pat. No. 3,537,717). In other cases, devices are affixed to skis to dampen vibration as illustrated by (U.S. Pat. No. 6,270,108).  
           [0005]    Despite these improvements, difficulties in controlling the vibrations of skis still persist. A ski or sliding board must transition rapidly and dynamically from the unflexed state utilized in straight running to and from the flexed state corresponding to the arc of a turn. The ease of flexing the ski into a turn and the return of energy from the bent ski to the skier upon completion of a turn are both impeded by a damping. Therefore damping devices on current skis are tuned to provide minimal damping so as not to result in a an overdamped or ‘dead’ ski as mentioned by Julien (U.S. Pat. No. 6,267,402). Because of this constraint on damping forces, ski vibration, chatter and other negative effects of insufficient damping persist.  
           [0006]    Insufficient damping in a turn allows the ski edge to bounce or chatter, causing loss of static friction in the established turning groove or carve. The ski will then dynamically bounce, skid, rebound and regrip into a longer turn radius bend. This causes the skier to lose balance towards the inside of the turn due to the reduced centrifugal force in the larger radius turn. Damping is also desired during straight ahead running to improve stability and ride smoothness.  
           [0007]    Total ski stiffness and ski stiffness distribution also greatly impacts the suitability of a ski for different conditions, terrain, and skiing style. Increased ski stiffness increases the skier&#39;s control, but can knock the skier off balance when large bumps in the terrain are encountered. Many skiers buy multiple pairs of skis for different conditions, for example, soft mogul skis for bumpy terrain and stiff skis for fast speeds and icy terrain. Devices for changing ski flexibility based on the absolute amount of bend in a ski are shown by Stepanek et al. (U.S. Pat. No. 5,301,976) and Le Masson (U.S. Pat. No. 5,597,170). These devices allow the flex modulus of the ski to change positively or negatively according to the amount of ski flex, to be more adaptable to terrain conditions and skiing style. A ski with a configurable flex pattern along the length of the ski is shown by Chernega (U.S. Pat. No. 4,577,886).  
           [0008]    Another method of selectively engaging damping or biasing elements of a ski is shown by Bonvallet (U.S. Pat. No. 5,806,875). The skier&#39;s weight presses on a clutch element to engage damping. The Comp 1400 Piston ski binding currently manufactured by Marker LTD. features a hydraulic piston with differential damping in extension and rebound.  
           [0009]    Even with these improvements, a number of problems exist with existing ski damping and biasing systems:  
           [0010]    a) Strong damping cannot be applied to the system without causing over damping during the transition between straight running and flexed turn conditions. Thus skiers must continue to contend with chatter and vibration that could be quieted by stronger damping. The skier weight engaged system shown by Bonvallet will engage at the beginning of a turn, restraining the bending of the ski into the flexed turn arc shape, and thus must also have constrained damping to avoid an overdamped condition during this transition.  
           [0011]    b) Damping cannot be selectively applied to a ski in both of its steady state conditions of straight running or flexed turn arc. The bias system shown by Stepanek can engage during a turn, but cannot adapt equally to both small and large radius turns. Le Masson&#39;s design functions selectively during straight running, but cannot engage damping or modulus during turning conditions.  
           [0012]    c) Stiffening cannot be increased to increase skier control, without a corresponding increase in upsetting forces applied to the skier by the terrain when larger bumps or transitions are encountered. Stepanek&#39;s design provides some relief in this situation, but does not assist the skiers control during a steady state turn by increasing ski stiffness during the turn.  
           [0013]    d) Damping engagement cannot be maintained regardless of terrain. When a skier using the Bonvallet design encounters bumps in a turn, the engaging spring force will be released, disengaging damping precisely when most needed. The unweighted ski will return to a flat shape faster, causing greater skier loss of balance. The damping in steady state turn conditions should remain engaged to resist ski rebound regardless of skier loading forces.  
           [0014]    e) Damping or stiffening cannot be selectively applied based on the current incremental direction of flex of the ski. Suspension systems for vehicles employ a damping system where different levels of damping are applied during compression and rebound. For snowboards and skis in a steady state turn, differential damping or stiffening that strongly resists extension without impeding maintenance of flexion is desired, to prevent the ski from rebounding into a larger turn radius.  
           [0015]    Marker&#39;s piston binding can accomplish directionally differential damping, but a piston is inherently a damping device and not ideal for directional bias application, if that is the desired result. Additionally, hydraulic pistons are a relatively heavy, large and expensive way to accomplish selective engagement for a ski application, where the energies to be dissipated are small.  
           [0016]    f) Differential directional damping possibilities for the front and rear of the ski to maximizing the energy return characteristics of a ski are not utilized. A slalom racer utilizes a ski with a soft shovel and stiff tail. The skier leans forward during turn initiation to heavily load the front of the ski and bend the ski into the flexed turn shape as quickly as possible. The skier leans back and pushes off the stiff, bent tail of the ski after the turn is completed to spring off the tail and accelerate in the direction of the next gate. Heavy directional rebound damping or biasing in the shovel of the ski could be applied to stabilize the turn with minimal effect on the racers ability to accelerate out of the turn. Disengaging damping forces on the tail of the ski during transition to and from flexed conditions would maximize energy return for the racer.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0017]    The invention provides for a clutch mechanism that can engage or disengage a damping and/or stiffening mechanism for a sliding board. In one embodiment, the clutch operates in both directions over a limited range, and disengages for large excursions in either direction. This can allow a relatively strong damping mechanism to be applied in steady state straight running and turning conditions, but disengaged for the transition between states so as not to impede the speed of changing modes. This clutch mechanism can also allow the resiliency of a ski to be reduced to better soak up large bumps, with a stiffening member that engages to increase control during steady state straight running or turning conditions.  
           [0018]    In another embodiment, the clutch operates over only one direction of bending. This allows the net damping or stiffness of the ski to be varied under compression and extension to reduce rebound, without the need for a hydraulic cylinder.  
           [0019]    In both embodiments, the clutch may not lock entirely, but may allow slippage that allows the ski to move with an added frictional resistance.  
         OBJECTS AND ADVANTAGES  
         [0020]    It is an object of the invention to improve the skiers control, balance and grip during varying conditions.  
           [0021]    It is another object of the invention to maximize the efficiency in which stored energy may be utilized by the skier.  
           [0022]    It is another object of the invention to minimize the negative effects during transitions that a damping or stiffening members may exert on the skier&#39;s ability to flex a ski into a turning condition or straighten a ski for straight running conditions.  
           [0023]    It is another object of the invention to maximize the damping or stiffening force that may be applied to assist the stability of the ski in a steady state turn or straight running condition.  
           [0024]    It is an object of the present invention to provide a clutch for engaging and disengaging a damping member for damping a ski.  
           [0025]    It is another object of the present invention to provide a clutch for engaging and disengaging a stiffening member for stiffening a ski.  
           [0026]    It is another object of the present invention to provide a damping system for damping a ski, having a damping member which is engageable and disengageable depending upon a skiing condition.  
           [0027]    It is another object of the present invention to provide a stiffening system for stiffening a ski, having a stiffening member which is engageable and disengageable depending upon a skiing condition.  
           [0028]    It is yet another object of the present invention to provide a damping or stiffening system that engages for small vibration induced changes in ski shape but that disengages for large changes in ski radius shape induced by the skier.  
           [0029]    It is yet another object of the present invention to provide a stiffening or damping system that can be selectively engaged during rebound of the ski but disengaged for compression of the ski, or vice versa.  
           [0030]    It is another object of the invention to be able to apply different clutch engagement strategies to the front and rear ski segments to maximize skier performance in racing conditions.  
           [0031]    Another object of the invention is to be able to adjust the range of motion over which damping or biasing is activated.  
           [0032]    These and other objects will become apparent from the following description of preferred embodiments taken together with the accompanying drawings and the appended claims. 
       
    
    
     BRIEF DESCRIPITION OF THE DRAWINGS  
       [0033]    In the drawings, closely related figures have the same number, but different alphabetic suffixes.  
         [0034]    FIGS.  1 A-D show a stiffening device on a ski, and close up side views of two different clutches, and an end view of a clutch.  
         [0035]    FIGS.  2 A-F show prior art concerning selectively engageable stiffening or dampening devices and the force versus displacement graphs associated with them. The later figures show the configurations and force versus displacement graphs for the present invention.  
         [0036]    FIGS.  3 A-D show operational engagement of a two way clutch over a limited range.  
         [0037]    FIGS.  4 A-F show alternate embodiments of two way clutches.  
         [0038]    FIGS.  5 A-D show alternate embodiments of single direction clutches.  
         [0039]    FIGS.  6 A-E show alternate configuration of clutched damping and stiffening devices, including use of such devices in a binding mounting platform or binding system.  
         [0040]    FIGS.  7 A-C show methods for altering the range of motion over which a clutch operates or the strength of the engagement force. 
     
    
     REFERENCE NUMERALS IN DRAWINGS  
       [0041]    [0041] 10  sliding board  50  eccentric  
         [0042]    [0042] 12  toe binding  52  axel  
         [0043]    [0043] 14  heel binding  54  resilient material  
         [0044]    [0044] 16  damping member  56  friction collar  
         [0045]    [0045] 18  stiffening member  58  friction collar tunnel  
         [0046]    [0046] 20  force transmission blade  60  viscoelastic damping material  
         [0047]    [0047] 22  pinch tunnel  62  directionally molded elastic  
         [0048]    [0048] 24  friction surface  70  piston cylinder  
         [0049]    [0049] 26  roller  72  piston rod  
         [0050]    [0050] 27  pocket  74  piston  
         [0051]    [0051] 28  clutch plate  76  valve aperture  
         [0052]    [0052] 30  engagement spring  78  flap valve  
         [0053]    [0053] 42  claw clutch  80  variable diameter valve  
         [0054]    [0054] 44  claw clutch slide  90  rolling ramp clutch plate  
         [0055]    [0055] 46  directional molded fingers  92  rolling ramp clutch slide  
         [0056]    [0056] 48  molded fingers  
         [0057]    [0057] 100  binding platform  104  nested ramp  
         [0058]    [0058] 102  ski boot  106  adjustment screw  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0059]    A typical embodiment of the present invention is depicted in FIG. 1A (side view). A flexible sliding board or ski  10  is shown with typical toe  12  and heel  14  bindings mounted. The embodiment of the invention consists of a force transmission rod or blade  20  secured to the ski at one end by screws, adhesives or a binding piece. The force transmission blade passes through a pinch tunnel  22  or stirrup at the other end. Bending motion of the ski moves the force transmission rod back and forth through the pinch tunnel. The force transmission blade may have internal dampening or stiffening characteristics, or may be constructed to minimize those characteristics.  
         [0060]    A close up view of the interior of the pinch tunnel containing a two way directional clutch is shown in FIG. 1B (side view). A roller  26  reciprocates back and forth with the force transmission blade, through a narrowed space in the pinch tunnel. When the roller is in the constricted portion of the tunnel, pinching force on the force transmission blade is increased, causing increased friction between the force transmission blade and the friction surface  24 . When movement in one direction allows the roller to enter a pocket  27 , pinching force and frictional engagement of the pinch tunnel with the force transmission rod is reduced. The engagement spring  30  will encourage the roller to re-enter the constricted portion of the pinch tunnel when the force transmission blade reciprocates back in the other direction.  
         [0061]    A close of up view of the interior of the pinch tunnel containing a single directional clutch is shown in FIG. 1C (side view). When the force transmission rod operates in the direction of engagement, the claw clutch slide  44  moves up the ramps of the claw clutch to a position that increases the pinching force on the force transmission blade. The blade can then continue to move in that direction with the maximum friction force that can be applied by the pinch tunnel. When the force transmission blade reciprocates back forward the claw clutch slide relaxes back down into a more open position, reducing friction in the pinch tunnel. Construction of the pinch tunnel as a bent member attached to the ski is shown in FIG. 1D (end view) along with the force transmission rod and clutch.  
         [0062]    Prior art is shown in FIGS. 2A-2C. FIG. 2A shows a force transmission rod that engages as the ski is bent, and a force versus displacement graph showing the characteristic increase in stiffness of this arrangement. FIG. 2B shows a force transmission rod that is released from a pinch tunnel as the ski is bent, and the force diagram showing the characteristic decrease in stiffness. FIG. 2C shows a force transmission rod connected to a piston  74  in a piston cylinder  70  attached to the ski. The piston is equipped with different sized valve apertures  76  and flap valves  78  so that resistance is greater in one direction (rebound) than the other. The force graph shows resistance in the bending direction determined by the stiffness of the ski, but moderated in the return direction by the energy absorption of the piston fluid. Damping is dependent upon rate of ski movement, so is shown as multiple lines.  
         [0063]    Characteristics of the embodiments of the present invention are shown in FIGS. 2D-2F. FIG. 2D shows a two direction, limited range clutch. The force graph shows how the engagement of the clutch stiffens the ski at initial conditions to increase control, and also at the terminal range of motion for three different sized turns that utilize different amounts of bending in the sliding board. FIG. 2E shows how a single direction, limited engagement clutch that allows upward bending, but resists rebound with a constant frictional force. FIG. 2F shows a two direction clutch attached to a damping member  16 . The force characteristic curve shows damping occurring in initial conditions and at the terminal end of bending where the ski will be bent in a steady state during turn conditions. The damping is disengaged during transition movements between these two steady states to allow rapid turn initiation and completion.  
         [0064]    The engagement operation of a two way clutch is illustrated in FIGS. 3A-3D. In FIG. 3A the ski is unbent, the clutch is engaged, and small reciprocal vibrations are being damped. In FIG. 3B, the ski begins bending into a turn and the clutch roller moves into a pocket in the pinch tunnel, releasing damping engagement. In FIG. 3C, the ski continues bending into the turn unimpeded by the force transmission blade. In FIG. 3D, the ski begins straightening and the clutch roller re-engages in the constrained portion of the pinch tunnel, damping rebound at the fullest extent of the ski&#39;s bend.  
         [0065]    Different embodiments of two way, limited range clutches are shown in FIGS. 4A-4F. FIG. 4A shows a pinch tunnel equipped with roller engagement element as previously explained. FIG. 4B shows molded fingers  48  constructed of plastic, rubber or viscoelastic material, that provide maximal engagement at the fully vertical position, but that relax pinching within the pinch tunnel when bent over in either direction by movement of the force transmission blade. FIG. 4C depicts an eccentric  50  mounted on an axel  52  in the pinch tunnel, where maximum pinch force is applied in the vertical position. Resilient material  54  encourages re-engagement of the eccentric when the force transmission blade reciprocates in the other direction. FIG. 4D shows a friction collar wrapped around the force transmission blade. The friction collar applies maximum friction when passing through the constrained portion of the friction tunnel, and relaxes friction when resting in a pocket at either end of movement. Friction between the friction collar and the force transmission blade is greater than friction between the collar and the pinch tunnel sides, so that the friction collar will re-enter the constrained portion.  
         [0066]    Another embodiment is shown in FIG. 4E, where viscoelastic material  60  optionally covered with a friction material is designed to deform due to movement of the force transmission blade. When the material deforms by bending over in either direction, the pinch engagement force with the force transmission blade is reduced. FIG. 4F shows a piston and cylinder with an additional variable diameter valve  80  that partially engages with the damping fluid. The engagement with the fluid causes the valve to follow the movements of the piston, and constrain movement of the piston over a limited range by blocking a valve aperture during part of the following movement.  
         [0067]    Different embodiments of one way clutches are shown in FIGS. 5A-5D. FIG. 5A shows a directionally molded material  62  of plastic, elastic or viscoelastic material that relaxes pinch force when folded over by movement of the force transmission blade in one direction, but increases force by jamming in the other direction. FIG. 5B shows a claw clutch, the operation of which was explained previously. FIG. 5C shows a rolling ramp clutch plate  90  and slide  92  that operates similarly to the claw clutch, but with reduced friction. FIG. 5D shows directionally molded fingers  46  of plastic or elastic material that fold over for movement of the force transmission rod in one direction.  
         [0068]    Various arrangements of the present invention are show in FIGS. 6A-6E. In FIG. 6A a stiffening  18  or damping member is attached to the remote end of the force transmission rod. In FIG. 6B the clutch is integrated with a stiffening or dampening member at the local end of the force transmission rod. In FIG. 6C an dampening member is integrated as part of the pinch tunnel. In FIGS. 6D and 6E the clutch mechanism, damping element and force transmission element are integrated with the binding platform  100 , mounting plate or binding mechanism.  
         [0069]    Possibilities for changing the range of engagement of clutches and amount of pinch force and friction are shown in FIGS.  7 A-C. In FIG. 7A, a mechanism of nested ramp  104  elements is shown that allows for adjustment of the range where pinch force is applied in a pinch tunnel. FIG. 7B depicts use of an adjustment screw  106  to provide a variable stop for constraining the maximum engagement force of a claw clutch. FIG. 7C shows an adjustment screw used to increase or decrease the pinching force between a friction material and the force transmission blade.  
       Summary  
     Ramifications and Scope  
       [0070]    Accordingly, significant improvements in sliding board performance can result from use of the invention. The invention will allow use of stronger damping forces during turning and straight running conditions without impeding the dynamic transitions of the sliding board. The invention allows damping or biasing forces to be applied during turns of different sizes that correspond to different degrees of bending in the ski. The engagement of damping can be applied independent of terrain conditions or skier weight distribution. The damping or biasing can be directionally applied without the requirement for a heavy and expensive hydraulic cylinder. The increased range of damping and stiffening strategies provided by the invention can be applied to different portions of the ski to maximize the skier&#39;s ability to utilize energy stored in the bend of the ski.  
         [0071]    Although the descriptions above contain many specificities, these should not be construed as limiting the scope of the invention, but merely as providing illustrations of the some of the presently preferred embodiments of the invention. For example, the sliding board could be a ski, snowboard, monoski, toboggan, etc. The placement of force transmission, clutch and damping or stiffening elements can be re-arranged into many visually different but operationally similar configurations.  
         [0072]    Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.