Binding for snowboards

A binding for snowboards and the including binding base plates (1a, 1b) which are attached on the snowboard, two binding carrier plates (2a, 2b) which are provided with fastening apparatuses in order to be fastened to one shoe of the rider of the snowboard, with holding elements (3a, 3b) being provided on the binding base plates (1a, 1b) which are designed to hold the binding carrier plates (2a, 2b), but to release the same at a predetermined releasing force, and with a connecting element being provided in order to forcibly release the other binding carrier plate (2a, 2b) from the binding base plate (1a, 1b) during the release of one binding carrier plate (2a, 2b). A secure release is achieved in such a way that guide elements (8a, 8b, 13a, 13b) are provided on the binding base plates (1a, 1b) which allow the release of the binding carrier plate (2a, 2b) only in the longitudinal direction of the snowboard.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a binding for snowboards and the which
 includes binding base plates that are attached on the snowboard, two
 binding carrier plates which are provided with fastening apparatuses in
 order to be fastened to one shoe of the rider of the snowboard, with
 holding elements being provided on the binding base plates which are
 designed to hold the binding carrier plates, but to release the same at a
 predetermined releasing force, and with a connecting element being
 provided in order to forcibly release the other binding carrier plate from
 the binding base plate during the release of a binding carrier plate.
 2. The Prior Art
 In the field of skis the safety bindings have generally been accepted for a
 long time in order to protect the skier from excessive forces in the event
 of falls or the like. Similarly, bindings were developed for snowboards
 for the same purpose. However, as the rider of a snowboard stands with
 both legs transversally to the longitudinal axis of the snowboard, or
 diagonally on the same, the requirements placed on such a safety binding
 differ from those in the case of skiers. It is a particularly important
 aspect that it is ensured in snowboards that, in the event of the opening
 of one binding, the other binding also opens simultaneously.
 From CH-A 681 062 a safety binding for snowboards or the like is known in
 which the bindings are mutually connected by way of a connecting rod. As a
 result of this connecting rod, the opening of the one binding also leads
 to the opening of the other binding. The release of the binding occurs
 through a torsional moment about the normal axis, as is also known in ski
 bindings. The special properties of a snowboard in comparison with skis
 are not taken sufficiently into account in such a safety binding.
 Moreover, from EP-A 0 352 662 a sport sliding board is known which
 comprises two bindings which are mutually coupled in order to release
 simultaneously. In this case the release also occurs by the torsional
 moments about the normal axis or by tilting moments about the longitudinal
 axis.
 Further apparatuses for coupling the release of bindings are known from
 FR-A 2 651 143 and from WO 93/16768.
 The common feature in all such apparatuses is that, although the joint
 release of two bindings is ensured more or less properly, the conventional
 approach is used for the release per se.
 It is the object of the present invention to avoid these disadvantages and
 to provide a binding for snowboards which is optimally adjusted to the
 special kinematic properties and those of the dynamics of movement of such
 a sports device.
 SUMMARY OF THE INVENTION
 This object is achieved in accordance with the invention in such a way that
 guide elements are provided on the binding base plates which allow the
 release of the binding carrier plate only in the longitudinal direction of
 the snowboard.
 The invention is based on the finding that the torsional strain of the legs
 of a snowboard rider does not represent an actual value. Riding or falling
 scenarios which exclusively entail an excessively large torsional strain
 of the rider's legs do not occur in practice or only to a negligible
 extent. Situations are more critical in which intolerable forces are
 exerted in the longitudinal direction of the snowboard. This is the case,
 for example, when the snowboard is abruptly stopped at high speeds by an
 obstruction or lands on a hard spot after a jump with the forward or
 rearward end. Excessive torsional trains occur as an accompanying
 phenomenon in such situations, if at all, so that a binding which releases
 as a result of the longitudinal forces is sufficient in order to cope with
 the dangerous situations that occur in practice.
 Simplified kinematics of the opening process are achieved by the present
 invention, so that the binding is of a simpler arrangement and shows a
 higher operational security. This is an important aspect, as such a safety
 binding must operate reliably under very unfavourable ambient
 temperatures. Low temperatures, snow and the formation of ice and the like
 must not disadvantageously influence the operation of such a binding. As a
 result of its constructional arrangement, the binding in accordance with
 the invention is capable of being produced to a large extent of carbon
 fibres. In this way it is possible to achieve an extraordinary tenacity at
 low weight.
 A particularly stable embodiment is achieved in particular in such a way
 that preferably the connecting element is arranged as a connecting link
 which is in connection with the binding carrier plates by way of
 positive-locking releasable connections and which is held on the snowboard
 movable in the longitudinal direction in a captive manner. It may be
 provided in this respect that the connecting link is pretensioned by
 springs in the unloaded condition into a middle position. In this way the
 rider can step into the binding substantially more easily after the
 opening.
 It has proved to be particularly favourable from a constructional point of
 view if spring bolts are provided on the binding base plates which are
 arranged movable in the transversal direction of the snowboard and which
 comprise holding noses and if recesses are provided in the binding base
 plates for latching the spring bolts, with the holding noses fixing the
 binding carrier plates in the upward direction. The recesses are
 particularly preferably sloped, namely in a conical manner in order to
 allow the latching of the binding carrier plates in the perpendicular
 direction downwardly from above. In this way the stepping into the binding
 is made perpendicular from above. The rider has the possibility to support
 the stepping-in process with their entire body weight.
 It is possible that four spring bolts be provided for each binding carrier
 plate, which bolts are substantially arranged on the corners of a
 rectangle which is parallel to the longitudinal axis of the snowboard.
 In a particularly preferable embodiment of the invention it is provided,
 however, that two spring bolts are provided for each binding carrier
 plate, with advantageously two fixed holding means being arranged for
 guiding the binding carrier plates on the binding base plates. The
 advantage of this embodiment is that by reducing the number of active
 holding elements the adjustability of the binding is facilitated, as only
 two spring bolts need to be adjusted. The fixed holding means can
 simultaneously assume the role of the guide elements in this embodiment. A
 further advantage of this embodiment is that the spring bolts in this
 embodiment must be pretensioned stronger at the same releasing force than
 in the variant with four spring bolts. Any adhering snow is pressed out
 more securely from the binding when stepping in. Furthermore, it is
 preferable that such a binding comprises fewer movable parts and therefore
 comes with a simpler arrangement.
 It is particularly favourable if limit stop buffers are provided in the
 binding base plate, which in the case that the binding carrier plate is
 obliquely positioned limit the movement of the binding carrier plate in
 such a way that it snaps into the fixed holding means. As owing to the
 fixed holding means any introduction of the shoe from above is no longer
 possible in the zone of the fixed holding means, the stepping-in process
 in this embodiment occurs in such a way that the binding carrier plate is
 guided obliquely below the fixed holding means and is then tilted
 downwardly about the fixed holding means on reaching the latching
 position, with the holding noses snapping into the spring bolts. A stop is
 formed by the limit stop buffers which limits the movement of the binding
 carrier plate, so that the position for stepping in no longer has to be
 actively sought by the rider. The limit stop buffers, however, are of a
 height which is dimensioned such that when the binding carrier plate is
 horizontal there is no obstruction to the opening movement.
 In a further preferred embodiment of the invention it is provided that the
 recesses of the binding carrier plates are laterally limited by shoulders
 whose height differ forwardly and rearwardly. Generally, the shoulders of
 the recesses of the two bindings will be arranged in a mirror-inverted
 manner, so that the one binding will have a lower opening force forwardly
 and the other binding a lower opening force rearwardly. The connecting
 link finally achieves that the releasing force is the sum total of the
 releasing forces of the two bindings in the respective direction. In the
 case of the similar projection of all spring bolts the releasing force of
 forwardly and rearwardly is equivalent. As a result of the opposite
 adjustment of the spring bolts, it is very easy to set a different forward
 and rearward releasing force. This is highly desirable and advantageous
 for a number of riding situations and styles.
 The invention is now explained in closer detail by reference to the
 embodiments shown in the drawings, which:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The binding of FIGS. 1 and 2 consists of a forward and a rear binding base
 plate 1a and 1b which hold a forward and rear binding carrier plate 2a and
 2b. Four holding elements 3a, 3b are provided on each binding base plate
 1a, 1b which hold the binding carrier plates 2a, 2b at their edges. The
 holding elements 3a, 3b are arranged as spring bolts whose arrangement
 will be explained below in closer detail.
 In contrast to a ski, a snowboard is arranged so as to receive relatively
 large torsional strains about the release axis. An experienced rider will
 actively use the torsion to influence the riding behaviour by exerting
 opposing tilting moments on the bindings. During this it is possible to
 cause a torsion of up to 20.degree.. In addition, the board is deflected
 under load. In order to prevent twisting or erroneous releases by the
 rigid connection by the connecting link 6, the binding base plate on the
 snowboard is arranged displaceable within limits in the longitudinal
 direction on the snowboard. Connecting rods 4 are provided to maintain the
 precise distance between the binding base plates 1a, 1b. The connecting
 link 6 is held on the binding base plates 1a, 1b in a captive manner
 between the connecting rods 4 by way of fixing means 5a, 5b. As an
 alternative to this, it is also possible that only one connecting rod is
 provided immediately below the connecting link. In this way it is possible
 to achieve an even more precise adherence to the distance of the binding
 base plates 1a, 1b in the zone of the connecting link.
 The connecting link 6 comprises at its two ends omega-shaped holding
 projections 7a, 7b which engage in a positive-locking manner in respective
 recesses of the binding carrier plates 2a, 2b. The holding projections 7a,
 7b are upwardly arranged in a truncated way in order to facilitate the
 introduction of the binding carrier plates 2a, 2b from above. Four pins
 8a, 8b are attached on the binding base plates 1a, 1b at the side of the
 binding carrier plates 2a, 2b, which pins represent the guide elements for
 the lateral guidance of the binding carrier plates 2a, 2b.
 The rider steps into this binding in such a way that the binding carrier
 plates 2a, 2b, which are connected with the rider's feet by way of holding
 elements (not shown), can be inserted perpendicularly from above onto the
 binding base plate 1a, 1b. The binding carrier plates 2a, 2b
 simultaneously snap into the spring bolts 3a, 3b of the binding base
 plates 1a, 1b and are centred in their correct position by the pins 8a,
 8b. Furthermore, the engagement of the binding carrier plates 2a, 2b
 occurs in the holding projections 7a, 7b of the connecting link 6. The
 binding base plate 1b is screwed onto the snowboard (not shown in closer
 detail) by screws (not shown). The binding base plate 1a is movably
 fastened to the snowboard through screws 9 which are arranged in oblong
 holes 9a. Screw bores 10 on the binding carrier plates 2a, 2b are provided
 for fastening the fastening apparatuses for the boots.
 The embodiment of FIG. 3 is distinguished from the foregoing embodiment in
 that the binding carrier plates 2a, 2b are each held by two spring bolts
 3a, 3b and that furthermore two fixed holding means 13a, 13b are provided.
 The fixed holding means 13a, 13b guide the binding carrier plates 2a, 2b
 laterally and hold them upwardly. Limit stop buffers 12 are provided on
 the binding base plates 1a, 1b in order to facilitate stepping into the
 binding. Furthermore, springs 15a, 15b are inserted in this embodiment in
 the oblong holes 6a, 6b of the connecting link, which springs pretension
 the connecting link 6 in the unstrained condition in its middle position.
 This not only allows the rider to step into the binding more easily, but
 an additional effect is achieved which is that the required releasing
 force is increased by the force which is required for displacing the
 connecting link. However, the characteristics of the release are also
 changed. The release under load caused by an impact, i.e., during an
 extremely short-term action of force, is changed only very little. Slower
 acting forces, are absorbed by the springs 15a, 15b to a relevant extent.
 In this way erroneous releases in deep snow which are caused by strong
 forces acting upon the snowboard can be better avoided.
 An automatic braking apparatus 11 is arranged in the type of a ski stop
 with an actuating bow 11a on the binding base plate 1b and below the
 binding carrier plate 2b in the known manner.
 FIGS. 4 and 5 show the forward and rear section of the binding in
 accordance with the invention pursuant to FIG. 3 in a more detailed
 representation.
 FIG. 6 shows a holding element with a spring bolt. Its arrangement is
 illustrated. The holding element is generally indicated with reference
 numeral 3, because it can principally be used both for the forward as well
 as the rear binding. The holding element 3 consists of a casing 16 which
 is connected by way of screws 17 with the binding base plate 1a or 1b. A
 slide 18 is displaceably arranged in the casing 16, which slide is
 pretensioned by a spring 21. The coil spring 21 is wound around a screw 19
 and extends between a nut 20 of the screw 19 and an inner wall 16a of the
 casing 16. The pretensioning force of spring 21 and thus the releasing
 force of the binding can be set by turning screw 19. A holding nose 22 is
 provided which comprises a surface 22a which is inclined upwardly in a
 semi-conical shape. The holding nose 22 holds binding carrier plate 2,
 which is shown only schematically, by engaging in a recess 23 which is
 laterally limited by shoulders 24 and 25. The height h of the shoulder 24
 from a randomly chosen reference plane e which is parallel to the
 longitudinal axis of the snowboard is smaller than the height H of the
 shoulder 25 from the same reference plane e. In this way the releasing
 force of the spring bolt in the direction of arrow 26 can be smaller than
 in the direction opposite to this.
 The holding nose 22 is extendable to such an extent that it is impossible,
 when the binding is released, to be pushed back again into the binding
 inadvertently by a reversal of the outwardly acting forces. This would be
 very dangerous, particularly if only one binding were to close again.
 However, as the holding nose extends to such an extent that a movement of
 the binding carrier plate 2a, 2b is prevented as it impinges upon the side
 area of the holding nose 22, this danger can securely be prevented.
 FIG. 7 shows a binding in accordance with the invention in a sectional
 view. The left half shows a fixed holding means 13, whereas the right half
 shows a spring bolt 3, both of which are fastened on a binding base plate
 1. This figure also shows the recess 23 and the bevelled surface 22a of
 slide 22.
 FIG. 8 schematically explains stepping into the binding of the embodiment
 of FIGS. 3 to 7. The binding carrier plate 2 is inserted in an inclined
 condition below the fixed holding means 13, with the limit stop buffers 12
 facilitating the insertion. After contact the binding carrier plate 2 is
 brought downwardly into the dot-dash position, so that the spring bolts 3a
 snap in and hold the binding carrier plate 2.
 The present invention allows production of a binding of a very simple
 arrangement which optimally considers the specific particularities of
 snowboards and is highly resistant and insensitive to rough operation at
 low temperatures and different snow conditions.
 It is furthermore advisable to provide a teflon coating, preferably of the
 metal parts, in order to prevent any adherence of snow to the highest
 possible extent.