FR2679147A1 - DEVICE FOR MODIFYING THE PRESSURE DISTRIBUTION OF A SKI ON ITS SLIDING SURFACE. - Google Patents

Abstract

A device for altering the pressure distribution of a ski, particularly a downhill ski, on the gliding surface thereof. The device includes an elongated element (6) capable of withstanding compressive forces and extending lengthwise next to the neutral axis of the ski (1) along part of its length. At least one end (10, 20) of the elongated element (6) is raised relative to said neutral axis of the ski (1) and engages a longitudinal abutment (12, 22) which is rigidly fastened to the ski. The device further comprises a device for compressively urging said elongated element (6) against the abutment (12, 22) in a longitudinal direction which is approximately parallel to the longitudinal axis of the ski.

Description

DEVICE FOR MODIFYING THE PRESSURE DISTRIBUTION OF A SKI ON ITS SLIDING SURFACE
The invention relates to a device for modifying the pressure distribution of a ski, such as in particular an alpine ski, on its sliding surface.

 The skis which are used for the practice of alpine skiing consist of relatively long boards, on which the skier's shoes are retained, most often by fastening elements. The boots and the fasteners are located approximately in the middle area of the ski, which is commonly called the skate.

 The skis present in themselves, at rest, a natural camber; they also have a certain flexibility. During skiing, the ski deforms elastically to respond to the various stresses to which it is subjected on the part of the skier, and by reaction of the surface on which it slides.

 The main stress to which the ski is subjected, coming from the skier, is generated by the weight of the skier. This weight is located approximately in the area of the ski skate.

 The ski is also stressed by the binding elements. It is in fact known that the fastening elements pinch the shoe. To do this, the rear fixing element is generally slidably mounted, and it is returned elastically towards the front by springs which are called recoil springs. The reaction to this pinching action is transmitted by the binding elements to the ski. This reaction is different, however, depending on whether the front fastening element and the rear fastening element are secured to the ski, or whether the front fastening element is secured to the ski, and the rear fastening element is connected to the front fastener by inextensible means, such as a blade.

 It is known that one can modify the behavior of the ski on snow, and in particular its conduct, by influencing its camber, or else on the longitudinal distribution of the ski on snow. By playing on this pressure distribution, it is known that one can make the ski more or less pivoting or more or less guiding, that is to say that one can promote its ability to turn easily or to present great driving stability.

 For skis which are currently on the market, the pressure distribution of the ski on the snow is determined mainly by the internal structure of the ski, and by the method of assembly of the binding elements to the ski, that is to say with or without connecting blade between the front and rear elements. The pressure distribution can also be influenced by the thrust intensity given to the recoil spring.

 There are devices with attached part which make it possible to modify the pressure distribution of the ski on the snow. European patent application No. 183 586 describes a blade of elastic material attached above the ski, between the binding elements and the ski. This blade has, at its front end and its rear end, sliders by which a portion of the forces to which the ski is subjected passes vertically, but this device has the disadvantage of having modest performance, for a large amount of space, it is suitable for the case where the two feet of the skier are in support for the same ski, to prevent the entire weight of the skier from being concentrated in the skate area, but it would be ill-suited in the case of a pair of traditional skis.

 Also known, according to European patent application No. 409 749, is a device consisting of a plate raised relative to the upper surface of the ski, held between two longitudinal stops. Elastic damping means are interposed between the plate and the stops, and the preload exerted on these elastic means is adjustable. The bindings are mounted, for their part, on the plate. This device gives good results, but its disadvantage is that the plate is raised relative to the ski on all its length, so it behaves like a stiffener for the ski, and therefore it disrupts the flexion movements of the ski. In addition, the plate induces an identical prestress on the ski towards the front and towards the rear of the skate. .

 One of the aims of the present invention is to propose a device which overcomes these drawbacks, and which makes it possible to prestress, in an adjustable manner, the ski in front and behind the skate area.

 Another object of the present invention is to provide a device which has a reduced bulk.

 Another object of the present invention is to provide a device which only moderately influences the flexibility of the skate during ski flexions.

 Other objects and advantages of the present invention will appear during the description which follows, this description being however given by way of indication, and not limitation.

The device according to the invention, intended to modify the pressure distribution of a ski on its sliding surface, is characterized in that it comprises
- a slender member capable of withstanding compression stresses, which extends in a longitudinal direction near the neutral fiber of the ski over part of its length, and at least one end part of which is raised relative to the neutral fiber of the ski,
a longitudinal stop integral with the ski, against which the raised end of the elongate member is in abutment,
- And means for urging the elongate member in compression against the stop, in a longitudinal direction approximately parallel to the longitudinal axis of the ski.

 The invention will be better understood by referring to the description below, as well as to the accompanying drawings which form an integral part thereof.

 - Figure 1 shows, in perspective, a partial view of a ski, in its area of the skate, which is equipped with fastening elements and a device according to a first embodiment of the invention.

 - Figure 2 is a side view, in section, of the construction shown in Figure 1.

 - Figure 3 is a side view, in section, of a construction illustrating another embodiment of the invention.

 - Figure 4 is a top view, in section, of the central part of the construction of Figure 3.

 - Figure 5 is a side view, in partial section, of a construction according to another alternative embodiment of the invention.

 FIG. 6 represents, in perspective, one of the elements of the construction of FIG. 5.

 FIG. 7 is a side view, in section, of a detail of the construction of FIG. 5.

 There is shown, in Figure 1, a ski 1 in its central region of the skate. In this zone, the ski 1 is surmounted by a front binding element 2, and a rear binding element 3 for retaining a boot on the ski. The fastening elements shown 2 and 3 are secured to the ski by screwing, and, preferably, a wedge 4, 5 is interposed between the upper surface of the ski and the base of each of the elements 2, 3. As is known , The rear fixing element 3 is slidably mounted in a slide, and it can move backwards against the elastic return force of one or more recoil springs.

 The elements shown are individual elements for retaining the front and rear end of the boot, and they are each secured to the ski. This is not limiting, and the invention also applies to other types of bindings, in particular to binding elements where the front binding element is secured to the ski, and the rear binding element is connected to the front element by an inextensible blade. Also, the invention applies to fasteners of the plate type, and to any other known type of fasteners.

 According to the invention, the ski 1 is equipped, in its region of the skate, with a slender member capable of working on compression. In FIG. 1, this member is represented in the form of a slender blade 6, which extends above the upper surface of the ski, in the area of the skate. This blade can work in compression, and preferably also has flexural qualities. It is made of any suitable material, and for example of composite material.

 The blade 6 extends over a large part of its length in the immediate vicinity of the neutral fiber of the ski, and at least one of its ends is raised relative to the neutral fiber of the ski. Referring to Figure 2, it is visible that the blade 6 extends against the upper surface of the ski, over the part of its length between the front end of the front wedge 4, and the rear end of the rear wedge 5.

The two wedges 4 and 5 moreover have, in their lower part, a longitudinal groove 8, 9, which extends over their entire length, and whose dimensions in section correspond substantially to the dimensions in section of the blade 6. The two grooves 8 and 9 constitute, for the blade 6, a longitudinal guide groove and holding the blade against the upper surface of the ski.

 On the side of the front binding element 2, the blade 6 has an end portion 10 which is raised relative to the upper surface of the ski. The end 11 of this part 10 bears against a longitudinal stop 17 secured to the ski. This stop comprises a housing 12 secured to the ski in front of the fastening element 2 by any suitable means, and in the example illustrated, by screwing. The housing has a longitudinal orifice 13, inside which is guided a piston 14. The piston is in direct contact with the end 11 of the blade 6 by its rear face, and preferably, it has at this level means such as a dihedral shaped cutout, at the bottom of which the end 11 of the blade finds a stable support. The piston 14 is guided inside the orifice 13, and it is pushed elastically backwards. by a spring 15, the preload of which can be adjusted by means of a threaded plug 16 which is screwed into a threaded part of the orifice 13.

 In the area of the end 11, the blade makes, with the horizontal, a relatively small angle, of the order of 10 to 20, in such a way that most of the thrust generated by the spring 15 is transmitted to the end portion 10 of the blade 6, in the form of a compression stress, and that moreover the end 11 of the blade is offset from the neutral fiber of the ski. This stress causes, by reaction, a moment which is proportional to the compression force exerted on the blade and the height at which the end 11 is located relative to the surface of the ski. This moment is transmitted to the part of the ski located in front of the skate area. This moment tends to plunge this part of the ski down.

 In the same way, the end part 20 of the blade, which is situated behind the wedge 5, is raised relative to the upper surface of the ski. The end 21 of the blade bears against a stop 27 constituted by a housing 22 secured to the ski, a piston 24 guided inside an orifice 23 in the housing, urged forward by a spring 25, the preload is adjustable by means of a threaded plug 26.

 Preferably, between the front and rear fixing elements, a jumper 28 straddles the blade 6.

The rider is joined to the ski. The role of the rider 28 is to prevent the blade 6 from buckling between the fastening elements 2 and 3. In addition, it can receive means such as a screw 29 for securing the blade 6 in the middle of the ski. In this way, in the absence of the screw 29, the compressive stresses generated by the springs 15 and 25 are balanced, and the moments induced by reaction, on the front part and the rear part of the ski, are substantially equal, or at least a variation of one of the moments also causes a variation of the other.

 On the other hand, in the presence of the screw 29, the moment induced on the front part of the ski by the spring 15, and the moment induced on the rear part of the ski by the spring 25, can be adjusted independently of one another. . It is the screw 29 which absorbs the differences in thrust between the spring 15 and the spring 25.

Since, in this zone, the blade 6 is located against the upper face of the ski, therefore close to its neutral fiber, the stresses at this level do not cause a significant change in the characteristics of the ski.

 The area in which the blade 6 can be secured to the ski is not limiting. This joining can be done in the area of the jumper 28, the shims 4 and 5, or at any other place. According to a construction variant, the blade 6 could be constructed in two portions each extending from the rider 28 towards each fixing element. At the rider 28, the ends of the two blade portions would be secured to the ski, for example by a screw.

 It should also be observed that the blade is, over a large part of its length, against the upper surface of the ski, and therefore in close proximity to the neutral fiber of the ski. Thus, the compression stresses, generated by the springs 15 and 25, are not significantly influenced by the bending of the ski, unlike what could happen if the blade 16 was raised relative to the upper surface of the ski on the whole of its length. It should be noted, in this regard, that the grooves 8 and 9 of the shims 4 and 5 ensure guiding of the blade without opposing its longitudinal sliding movement.

 The plugs 16 and 26 and the springs 15 and 25 generate the compression stresses in the blade 6. But the springs also serve as safety for the blade 6 by absorbing increases in compression stresses, in particular during strong flexions of the ski.

 These springs 15 and 25 could be replaced by blocks of elastically compressible material, in particular blocks of viscoelastic material.

 They could also be deleted. In this case, the compressive stress of the blade 6 would only be generated by the plugs 16 and 26.

 FIG. 3 illustrates a variant according to which the elongate member is constituted by two rods 30 and 31 folded in a "U" shape which extend longitudinally so that the ends of the branches are opposite one another. As in the previous case, the rods 30 and 31 extend over part of their length just above the upper surface of the ski, that is to say in the immediate vicinity of the neutral fiber. As in the previous case, the rods 30 and 31 pass right through part1 in a longitudinal direction, the shims located under the front and rear fastening elements, and extend in front and behind these elements. The front end part 32 of the front rod 30, and the rear end part 33 of the rear rod 31 are raised relative to the upper surface of the ski. The front ends 34 and rear 36 are also in abutment against stops 37 and 38.

Each of the stops is constituted by a base 39 secured to the ski, crossed in a longitudinal direction, by a screw 40 which ends in a head 41. It is on this head that the end 34 or 36 of the rods is supported.

 Between the front fixing element 2 and the rear fixing element 3, there is a block 42 secured to the ski, for example by screwing. The block 42 has two longitudinal holes 43 and 44, inside which the opposite ends are guided of the rods 30 and 31 for a longitudinal sliding movement. Two springs 45 resiliently push the front rod 30 forward, each taking support on the one hand on the wall of the block 42, and on the other hand on washers 46 integral with the rod 30. In the same way, springs 47 push the rear rod 31 backwards. The operation of this construction is similar to what has been described previously in the case where the blade 6 is secured to the ski in its intermediate part. These are the springs 45 and 46 which induce, on the front part and on the rear part of the ski, a moment tending to plunge the part of the ski in question.

Each of these moments can be adjusted individually by one of the stop adjustment screws 37 and 38.

 FIG. 5 represents another alternative embodiment, according to which the elongate member is constituted by a blade 56 similar to the blade 6 of FIG. 1. This blade 56 extends in the immediate vicinity of the neutral fiber of the ski, in its intermediate zone, and in front of and behind the fastening elements 2 and 3, its end parts are raised relative to the upper surface of the ski, so that the front and rear ends of the blade 56 are in abutment against front and rear stops 58 and 59.

 In the variant illustrated in FIGS. 5 to 7, the stops 58 and 59 are of the same type. They each comprise a stirrup 60, the branches 61 and 62 of which terminate downwards and inwards by lugs 63 and 64. These lugs are intended to be engaged under the bases of the fastening elements 2 and 3, and they have orifices the location of which corresponds to the locations of the screws for assembling the binding elements to the ski. The two legs 63 and 64 meet towards the median longitudinal axis of the ski so as to form a guide groove 71 for the blade 56.

 The central part 65 of the stirrup 60 is raised relative to the upper surface of the ski when the stirrup is in place. It has a threaded longitudinal opening 66, into which a plug 67 is screwed.

In the example illustrated, a compression spring 68 is housed inside the plug 67, and a piston 69 is guided by the plug 67 for a longitudinal sliding movement. The plug 69 ends on the side of the blade with a dihedral-shaped cutout in which the end 57 of the blade comes to bear.

 According to a preferred embodiment, the fastening elements 2 and 3 are mounted not on two independent shims, but on a single shim 70 which extends continuously between the legs of two stirrups 58 and 59. The shim 70 has a thickness equal to the thickness of the legs 62 and 63. This wedge 70 has, in its lower part, a guide groove for the blade 56. In addition, it has means for locally locking the blade 56 relative to the ski. These means are represented in the form of an orifice 72 which passes right through the wedge 70 and the blade 56, into which a screw 73 can be introduced to secure this assembly to the ski locally. The location of the orifice 72 is not limiting.

 It can also be emphasized that the shim 70 prevents the blade 56 from buckling between the fastening elements 2 and 3, for relatively high compression forces.

 The operating mode of the present construction is substantially the same as that of the construction which has been described in relation to FIG. 1. The difference is however that the stresses which the blade 56 induces in skiing are exerted in the areas of the ski where the fasteners are assembled.

It is also in these same zones that the stresses which result from the thrust of the recoil springs of the rear binding element 3 are transmitted to the ski. Furthermore, the present construction is substantially simpler, insofar as it does not does not require the assembly on the ski of elements distinct from the binding elements.

 As a variant, the blade 56 could be made in two portions, each portion having one end secured to the ski at the level of the wedge 70, and one end raised relative to the surface of the ski and bearing against a longitudinal stop.

 Also, the springs 68 could be replaced by blocks of elastically compressible material, in particular of viscoelastic material, or else they could be eliminated.

 Naturally, the present description is given for information only, and other implementations of the invention could be adopted, without going beyond the scope of the latter.

 In particular, it goes without saying that one could equip the ski only with part of the construction, that is to say a blade, or a rod, which would extend in the immediate vicinity of the neutral fiber of the ski from one of its ends, and the other end of which is raised relative to the upper surface of the ski, behind the rear binding element, or in front of the front binding element, and in abutment against a stop, as described above.

 In this way, only a part of the ski, front or rear, could be prestressed so as to modify the pressure distribution of the ski on the snow.

Claims (9)

 1- Device intended to modify the pressure distribution of a ski, such as in particular an alpine ski, on its sliding surface, characterized in that it comprises:  - a slender member (6,30,31,56) capable of withstanding compression stresses, which extends in a longitudinal direction near the neutral fiber of the ski (1) over part of its length, and of which at least one end portion (10,20,32,33) is raised relative to the neutral fiber of the ski,  a longitudinal stop (17,18,37,38,58,59) integral with the ski, against which the end (11,21,34,36,57) raised from the elongate member is in abutment,  - And means (16, 26, 40, 67) for urging the elongate member in compression against the stop, in a longitudinal direction approximately parallel to the longitudinal axis of the ski.  2- Device according to claim 1, characterized in that the other end of the elongate member (6,30,31,56) is also raised relative to the neutral fiber of the ski, and that the end bears against a longitudinal stop (17,18,37,38,58,59) integral with the ski.  3- Device according to claim 1 or 2, characterized in that the elongate member (6,56) is secured to the ski in the part of its length which extends in the immediate vicinity of the neutral fiber of the ski.  4- Device according to claim 2, characterized in that the elongate member (30,31) is guided in the part of its length which extends in the immediate vicinity of the ski for a translational movement in a longitudinal direction.  5- Device according to claim 1, characterized in that the stop is a block (12,22,39) secured to the ski beyond one or the other of the front and rear fixing elements (2,3 ).  6- Device according to claim 1 wherein the boot is retained in abutment on the ski by a front binding element (2) and a rear binding element (3), characterized in that the stop is constituted by a stirrup (60 ) whose branches (61,62) are integrally connected to the ski in the area where the base of the binding element is itself secured to the ski, the central part (65) of which is raised relative to the upper surface of the ski, and has means (67, 69) constituting a longitudinal stop for the end of the elongate member (56).  7- Device according to claim 1, characterized in that the means for urging the elongate member in compression comprise an elastic device (15,25,45,56,68) capable of generating a pushing force, and adjustable means (16,26,40,67) to force the elastic device to compress the blade according to an adjustable thrust.  8- Device according to claim 1, characterized in that the elongate member is constituted by at least one rod (30,31) oriented longitudinally and guided for a translational movement in a longitudinal direction, that part of the length the rod is held close to the neutral fiber of the ski, that one end of the rod is raised relative to the upper surface of the ski, that said end portion (34, 36) is in abutment against a stop (37, 38) integral with the ski, that the other end of the rod is guided for a longitudinal translational movement and is in abutment against at least one compression spring (45,47), and that the stop (37,38) has screw means (40) for biasing the rod in compression against the return force of the spring.  9- Device according to claim 1, characterized in that the elongate member is a compression blade (6,56), one end of which is bent upwards so that the end (10,20,57) is raised relative to the upper surface of the ski, that said end is in abutment against a movable piston (14,24,69) longitudinally against the return force of a spring (15,25,68) which resiliently pushes the piston in blade direction.