Ski boot

Abstract: A ski boot, in particular a telemark boot, having a shell (2) made of plastic material and in turn having a bottom wall (9), two lateral walls (6), a toe portion (5), and a flexible portion (11) extending crosswise with respect to the shell (2), from one side to the other of the bottom wall (9) at the metatarsus; and a frame (16) embedded in the shell (2) and having, integrally, two longitudinal elements (17, 18) extending along respective lateral walls (6) from a rear portion (15) of the shell (2) to an intermediate portion of the bottom wall (9) adjacent to respective lateral ends of the flexible portion (11), and a transverse structure (20) connected integrally to respective front ends (17a, 18a) of the longitudinal elements (17, 18) and defined by a flat bottom portion (21) embedded in the bottom wall (9), and by a top portion (22) extending along the connecting portion (12b) between the toe portion (5) and the flexible portion (11).

Description: The present invention relates to a ski boot, in particular for telemark skiing. As is known, telemark skiing calls for boots with a flexible metatarsal region to permit turning with the heel raised off the ski, as opposed to clamped rigidly as in conventional skiing. Telemark ski boots are traditionally made of leather to achieve the necessary degree of flexibility. In recent years, however, the trend has been towards plastic telemark ski boots, which are technically better, more attractive, stronger and more hardwearing than leather. To achieve the required degree of flexibility, the metatarsal region of plastic boots normally has a flexible-wall portion, the flexibility of which derives from it being made either to a particular - normally undulated - shape or of more flexible material than the rest of the shell. The use of plastic materials with different mechanical characteristics for more or less flexible parts of the boot is made possible by co-injection processes. Increasing the flexibility of one portion, however, may impair the torsional stiffness of the boot and, hence, ski control, performance and safety. By way of a solution to the problem, EPO-A-1 023 849 proposes a boot shell with stiffening ribs extending along the lateral walls of the shell, between an intermediate portion of the sole, close to the flexible-wall portion, and a rear portion of the shell at the heel. While improving torsional performance of the shell with respect to known boots, this solution has been found to still permit relatively severe torsional strain of the toe portion with respect to the rear portion of the shell. Moreover, the flexible portion tends to be slow in recovering its shape following deformation, and to retain a certain amount of permanent deformation after a given number of flexing cycles. EP-0 931 468 discloses a shell for sport shoes, in particular telemark ski boots, which comprises a frame embedded therein. The frame has a back portion designed to surround the whole heel area of the wearer, a toe cup and a foot resting surface which is substantially continuous but for a first transversal aperture below the metatarsal region. A second transversal aperture is provided in the toe cup above the metatarsal region, thereby forming a transversal bridge arranged at the rear of the metatarsal region. Although this shell provides for high flexibility but still good torsional properties, it is not free from the above-described problems concerning slow recovering of the undeformed shape after flexing, as well as the tendency to retain some permanent deformation. It is an object of the present invention to provide a plastic ski boot, in particular a telemark boot, designed to solve the aforementioned problems typically associated with known boots. This object is achieved by a ski boot as claimed in claim 1. A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a side view of a telemark boot in accordance with the present invention; Figure 2 shows a longitudinal section of the Figure 1 boot shell; Figure 3 shows a view in perspective of a stiffening frame of the Figure 2 shell; Figure 4 shows a plan view of the Figure 3 frame. Number 1 in Figure 1 indicates as a whole a ski boot, in particular a telemark boot. Boot 1 substantially comprises a shell 2 made of plastic material; a sole 3; and a shank 4 hinged to shell 2 at the ankle. Shell 2 (Figure 2) comprises integrally a toe portion 5; two lateral walls 6 forming a front opening 8 closed by a known tongue 7 (Figure 1); and a bottom wall or inner sole 9 closing the bottom of the shell and forming a heel portion 9a in relief. Inner sole 9 also forms a toe flange 9b projecting from toe portion 5 and cooperating in known manner with a clamp on the ski (not shown). An outer sole 10 made of elastomeric material is fixed to the bottom of inner sole 9 and forms, with inner sole 9, sole 3. Shell 2 also comprises a flexible portion 11 extending crosswise with respect to the shell, from one side to the other of sole 3, and substantially located at the metatarsus of the wearer, i.e. close to the toe portion 5 of shell 2. Flexible portion 11 has an undulated contour defined by two grooves 12 separated by a radiused intermediate portion 12a, conveniently extends obliquely to follow the natural bend axis of the foot, and has one end 11a, on the inner side of boot 1, located forwards with respect to an end 11b on the outer side of boot 1 (dash lines in Figure 4). Shank 4 is connected to lateral walls 6 of shell 2 by respective hinges 13 along the transverse hinge axis of the ankle; and boot 1 comprises a device 14 for controlling the tilt of shank 4 with respect to shell 2 and located at a rear portion 15 of the boot, substantially above the heel. Boot 1 comprises a stiffening frame 16 co-injected into shell 2 (Figure 2). Frame 16 (Figure 3) comprises two longitudinal elements 17, 18 embedded in respective lateral walls 6, and which extend from rear portion 15 of the boot, where they are joined, to respective lateral ends 11a, 11b of flexible portion 11, close to inner sole 9, where respective ends 17a, 18a are connected to a transverse stiffening structure 20 forming part of frame 16 and located close to flexible portion 11 so as to extend at least partly beyond flexible portion 11, towards toe portion 5, and so deform elastically alongside flexing of shell 2. Structure 20 is conveniently of closed annular shape, and comprises a flat bottom portion 21 embedded in inner sole 9; and an arc-shaped, substantially triangular-section top portion 22 extending crosswise with respect to shell 2 inside a rib 12b, which is parallel to grooves 12 and forms the connecting portion between flexible portion 11 and toe portion 5 of shell 2 and substantially along a plane roughly perpendicular to elements 17, 18. Bottom portion 21 extends rearwards from the ends of portion 22 (Figure 3), is of constant width (measured lengthwise of shell 2) along a lateral portion 21a adjacent to the inner side of the boot, and decreases gradually in width along a lateral portion 21b adjacent to the outer side, so as to form a substantially V-shaped intermediate central appendix 21c extending frontwards with respect to a bend portion of inner sole 9 located between ends 11a, 11b of flexible portion 11. Frame 16 also comprises a further transverse element 24 located in heel portion 9a of the inner sole and integrally connecting longitudinal elements 17, 18. Frame 16 is conveniently injection molded from plastic material chemically similar to but mechanically stiffer than that shell 2. When the material of shell 2 is injected onto frame 16 placed beforehand inside the mold, the surface of the frame 16 material softens to promote adhesion of the materials. The inner surfaces 25 of elements 17, 18 are conveniently flush with the inner surface of shell 2, and have transverse recesses 26; and elements 17, 18 have through openings 27 located at the ends of recesses 26 so that, when shell 2 is injected, the material of shell 2 "fills" recesses 26 through openings 27 to form "looplike" portions 30 surrounding corresponding portions of elements 17, 18 to secure frame 16 mechanically to shell 2. Preferably, elements 17, 18 have respective raised outer longitudinal ribs 28 which project from shell 2 (Figure 1) and provide for both accurately positioning frame 16 inside the injection mold and forming an ornamental motif, particularly when shell 2 and frame 16 are made from different coloured materials. Elements 17, 18 and portion 21 of frame 16 also have holes 31 for mechanically securing frame 16 to shell 2. In actual use, transverse structure 20, connected integrally to elements 17, 18, provides for drastically reducing the torsional strain of shell 2, and in particular toe portion 5, with respect to the rest of the shell. And since a telemark boot is only connected to the ski by the toe, reducing the torsional strain of the toe affords enormous advantages in terms of ski control. By virtue of structure 20, and in particular portion 21, the appendix 21c of which substantially participates in flexing shell 22 by substantially acting as a leaf spring, toe portion 5 is more resilient and the tendency of shell 2 to retain a certain amount of permanent deformation is reduced. The shape of portion 21 provides for obtaining the desired springback effect without excessively increasing the flexural stiffness of shell 2. By virtue of frame 16, shell 2 may be made fairly thin, thus reducing the overall weight of boot 1. Finally, the slant of flexible portion 11 greatly enhances the effectiveness and comfort of the boot when flexing, by favouring the natural movement of the foot. Clearly, changes may be made to boot 1 as described herein without, however, departing from the scope of the accompanying Claims.

Claims: A ski boot having a shell (2) made of plastic material and comprising a bottom wall (9), two lateral walls (6), a toe portion (5), a flexible portion (11) extending crosswise with respect to the shell (2) and located at the metatarsus close to said toe portion (5), and a stiffening frame (16) built into said shell (2) and integrally comprising two longitudinal stiffening elements (17, 18) extending along respective said lateral walls (6) of said shell (2) and having respective rear ends joined together at a rear portion (15) of the shell (2) and at a distance from said bottom wall (9), and respective front ends joined to said bottom wall (9) close to respective lateral ends (11a, 11b) of said flexible portion (11); said stiffening frame (16) further including a transverse structure (20) connected to said front ends (17a, 18a) of said longitudinal elements (17, 18), said transverse structure (20) comprising a bottom portion (21) embedded in said bottom wall (9) and extending close to said flexible portion (11) so as to deform elastically alongside flexing of said shell (2) and an arc shaped top portion (22) extending crosswise with respect to said shell (2) and substantially along a connecting portion (12b) between said flexible portion (11) and said toe portion (5). A boot as claimed in Claim 1, characterized in that said top portion (22) is housed in a rib (12b) of said shell (2) defining said connecting portion between said toe portion (5) and said flexible portion (11). A boot as claimed in any one of the foregoing Claims, characterized in that said flexible portion (11) has an undulated contour and extends obliquely between a more forward end (11a) on the inner side of said shell (2) and a more rearward end (11b) on the outer side of said shell (2). A boot as claimed in Claim 3, characterized in that said bottom portion (21) of said transverse structure (20) is flat and has a flexible front portion (21c) extending frontwards with respect to a bend portion of said bottom wall (9) located between the ends (11a, 11b) of said flexible portion (11). A boot as claimed in any one of the foregoing Claims, characterized by comprising retaining means (30) securing said frame (16) mechanically to said shell (2). A boot as claimed in Claim 5, characterized in that said retaining means comprise a number of looplike elements (30) forming part of said shell (2) and surrounding portions (17, 18) of said frame (16). A boot as claimed in Claim 6, characterized in that said longitudinal elements (17, 18) have respective inner surfaces (25) flush with an inner surface of said shell (2); and respective outer ribs (28) projecting on the outer sides of said lateral walls (6) of said shell (2). A boot as claimed in any one of the foregoing Claims, characterized in that said frame (16) comprises a transverse stiffening element (24) integrally connecting said longitudinal elements (17, 18) and embedded in a heel portion (9a) of said bottom wall (9).

Inventors: PARISOTTO DAVIDE, PARISOTTO, DAVIDE
Applicants: SCARPA CALZATURIFICIO SPA, CALZATURIFICIO S.C.A.R.P.A. S.P.A.
Application year: 2001
Main classification: A43B5
IPC codes: A43B5, A43B13, A43B23, B29D35