Plastic Ski Boot

The present invention relates to a plastic ski boot adapted to be releasably attached to a ski and, when out of the ski binding, facilitating safe and comfortable standing and walking by the wearer.

Modern ski boots formed of plastic materials have provided, when releasably attached to skis, greatly improved control and performance. Difficulties have, however, been encountered when walking or standing with plastic boots due to the configuration and low friction characteristics of their lowers required for conventional bindings, and further due to the stiffness and required forward lean angle built into the boots. In other words, the specific boot characteristics required for conventional toe and heel ski bindings render the boots unsuitable for safe and comfortable walking or standing.

To provide safer walking characteristics, attachments have been devised to clip on to boot lowers for changing the sole configuration and providing a non-slip walking surface. Such clip on arrangements are bulky to carry, difficult to attach to the boot when at the mountain in cold weather, and hence have not found wide use.

The present invention provides a plastic ski boot which can be both releasably attached to a ski and safely and comfortably used for walking by the wearer. To provide these advantageous characteristics, the inventive ski boot includes a binding attachment member mounted on the boot lower between the toe and heel. In addition, plastic on the sole assists in spacing the attachment member from the toe and heel walking surfaces. In one embodiment, the plastic is a high friction walking material provided on the walking surfaces of the boot.

Rather than using the sole extensions fore and aft and an essentially flat sole required by applicable standards for conventional toe and heel bindings, the inventive boot incorporates an upwardly curved toe portion and a beveled heel portion which, together with the high friction walking material, renders the inventive ski boot safe and comfortable for walking purposes. Transverse ridges formed in hard plastic at the curved and beveled portions can be used to increase the boot's bite into hard snow and ice, further increasing its safety.

Another embodiment incorporates a boot upper and lower formed with a lesser forward lean angle for comfortable standing and walking. When attached to a ski, a ski binding cooperates with the attachment member on this boot embodiment to provide a proper forward lean angle for skiing.

The invention will be better understood when the following description is read in connection with the accompanying drawings.

FIG. 1 illustrates a plastic ski boot incorporating the invention and suitable for releasable attachment to a ski and for standing and walking;

FIG. 2 is a cross-sectional view of the boot shown in FIG. 1, partially broken away, on the view line 2--2 in FIG. 3, illustrating the invention in greater detail; and

FIG. 3 is a bottom view of the ski boot shown in FIG. 1.

Referring to the invention in greater detail with particular reference to FIG. 1, a plastic ski boot 10 is formed of a boot upper 11 and a boot lower 12 including a sole 13, the upper and lower being adjustably clamped by buckles 14. Mounted on the boot lower 12 is a binding attachment member 15 positioned between the sole toe portion 16 and the sole heel portion 17. Plastic material 18 assists in spacing the member 15 from the toe and heel walking surfaces. Preferably the plastic 18 is formed of a high friction material suitable for walking surfaces, for example a thermoplastic rubber of durometer 60 Shore A can be used. Lesser portions of the boot can be covered by the plastic 18 (FIG. 2), depending on the binding used and the configuration of the boot. Moreover, some or all of the plastic 18 can be low friction material if required by the binding arrangement.

The toe portion 16 is shaped to facilitate walking, here shown with an upward curve. The curve at the toe can be on the order of two inches for small boot sizes to on the order of 31/2 inches for larger sizes. The only requirements are sufficient room for the foot, insulation inside the boot, and sufficient flat surface for standing on the binding.

The heel portion is shaped with a bevel for safer and more comfortable walking.

The toe and heel shapes are not in compliance with applicable standards (for example DIN 7880 German Standards) for conventional toe and heel bindings. Such standards require extensions fore and aft of the foot for engagement with such bindings. Such extensions, however, interfere with normal walking and are particularly dangerous on steps and uneven surfaces. With the use of a ski binding engaging and releasably holding the attachment member 15, located between the toe and heel portions, there is no need for the dangerous and unsightly extensions on the boot. Thus the operative contact surfaces of the binding to the boot do not act directly on the boot lower, but act through the attachment member to the boot.

When conventional ski bindings are used, applicable standards require a particular glide friction for the glide region of the boot sole since the boot normally rests on a glide element of polytetrafluoethylene on the ski surface. With the inventive boot, the attachment member remains with the boot, the binding remains with the ski, and the two are attached releasably. Preferably the boot sole is spaced from the ski surface, hence its high friction characteristics do not interfere with binding release.

The attachment member 15, best shown in FIG. 3, can be in the form of a flat plate provided with wings 19 on both sides to cooperate with a binding attachment 20 (details not shown) mounted on a binding plate 21 affixed to a ski 22. Flat transverse ridges 21a on the plate 21 support the boot 10 when the member 15 is held by the binding attachment 22. Note that the boot 10 is spaced from the surface of the ski 22. The binding releases when forces of a certain magnitude are exerted between the boot and the ski without interference from the small surface areas of contact between the ridges 21a and the boot sole 13. If desired, however, low friction material can be used on the boot sole at the areas of contact between the ridges 21a and the sole.

The member 15, lightened by an opening 15a, is mounted on the boot lower by screws 23 threadedly received by a plate 24, also lightened by openings, embedded in the boot sole 13. With this arrangement, the flexibility of the boot lower can be designed without regard to the torsional, compressional and flexural stiffness requirements of the boots used with conventional toe and heel bindings. Moreover, in addition to the use of high friction walking material on the sole, the toe and heel ends can be made from plastic material harder than normal for boots, for example 45 Shore D to 65 Shore D. The harder toe and heel areas can be formed with sharp toe ridges 16a and the sharp heel ridge 17a to cause the boot sole to penetrate hard snow and ice, thus increasing walking security.

If a ski binding attachment is used which requires movement between the boot and binding (but not a conventional toe and heel binding), the inventive boot can utilize low friction material where the boot contacts the binding or the ski surface.

Referring to FIG. 1, the boot 10 there shown is formed with the boot upper and lower providing an angle somewhat less than a normal forward lean angle for skiing purposes. The plate 21 is tapered forwardly on the ski to add an additional amount of forward lean for the desired forward lean. The boot when out of the binding is then more comfortable for standing and walking.

In an exemplary embodiment of the invention, a boot upper and lower provide a boot angle of 8 to 10 degrees, a comfortable angle for standing and walking in the boot when out of the ski binding. This should be contrasted with the normal forward lean angles of from 14 to 25 degrees with 16 degrees nominal, all of which provides an uncomfortable standing or walking position. With the boot angle of 8 to 10 degrees, the binding plate 21 can be tapered to provide an additional forward lean angle of on the order of 8 degrees, thus providing a desired forward lean angle with the boot in the binding of from 16 to 18 degrees.

It will be understood that the above described embodiments are merely exemplary and that persons skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such modifications and variations are intended to be within the scope of the invention as defined in the appended claims.