Patent Application
20110078925
This application claims priority benefits of European Patent Application Number 09425388.7 filed Oct. 5, 2009, the entire disclosure of which is incorporated herein by reference.
The invention relates to a series of ski boots and a method for making such a series.
In the prior art, a ski boot is generally composed of a rigid shell, obtained by injection molding a plastic in a manufacturing mold, to which is attached a hinged plastic cuff, similarly obtained by injection molding and designed to cover the lower part of the leg. This assembly forms a ski boot upper made of plastic with a hardness of generally between 40 and 60 Shore D. The method of injection molding the shell and cuff requires very expensive manufacturing molds. The shell is designed to enclose the foot and corresponds to a given boot size. It comprises a rigid outer bootboard comprising standardized front and rear lips designed to engage with the jaws of a toepiece and a heelpiece, respectively, of a device for binding the boot to the ski. A “Zeppa” bootboard is generally built into the shell, followed by a comfort innerboot which usually contains an insole. It is known practice to provide a shell of a different size for each integer boot size—that is, the length of its bootboard, between the two lips, is different, and its overall dimensions are different to correspond to feet of different sizes, in accordance with standardized volumes according to the Mondopoint standard, for example. These shells therefore require a different manufacturing mold for each boot size. Next, it is known practice to provide two different half boot sizes for each shell by allowing two innerboots of slightly different volumes to be inserted or having two insoles of different thicknesses in the same shell, thus increasing the number of options for the skier. Next, the distance between the toepiece and heelpiece of the ski boot binding device is adjusted to the size of the outer bootboard of the ski boot for actual skiing.
This is a burdensome situation for the management of ski boots and skis, especially for ski equipment hire stores, which have to keep multiple series of ski boots in all sizes so that they can offer customers the right ski boot for their size. Next, when a customer has selected a boot, he or she needs a ski to fit: the heel-to-toe separation of the selected ski binding device rarely corresponds to the selected ski boot, because the previous hirer of the ski often had a different size of boot, which means the separation must be adjusted to fit it to the selected ski boot. Ski equipment hire stores thus have to undertake many adjustment operations, which takes up time and can lead to mistakes. They must also offer a series of boots in all integer and half sizes, which is a heavy investment.
To ameliorate this situation, document US2008196275 proposes a solution in which a series of boots extending from size 23 to size 34 uses only three different bootboards, that is to say three different lengths requiring only three different corresponding spacings between the front toepiece and the heelpiece of a device for binding a boot to a snowboard. This solution is therefore advantageous in that it greatly reduces the demands and the risk of error in setting up the ski boot binding device. To achieve this advantageous result, the solution proposes two boot shells of different sizes for each length of bootboard, making a total of six different shells. Each of these shells is then given two innerboots of different dimensions to produce two different boot sizes, which is how the desired twelve different boot sizes is achieved. The problem with this solution is that it requires six different manufacturing molds to produce the six different sizes of shells, so it is still expensive to purchase the complete series of boots. Also, innerboots compensate for the volumes of the shells to form two different sizes out of each boot shell: these inner boots must therefore have thick walls to form the small sizes, which is detrimental to the transmission of forces from the foot to the ski and reduces the overall performance of the boot.
Document EP1952711 proposes an alternative solution by a similar approach in which a series of boots can be used to create twelve boot sizes from four different bootboard lengths, and three different shells for each length of bootboard. This solution suffers from the same problem as the previous solution because it inevitably requires twelve different molds to produce twelve different shells.
Consequently, the prior art solutions allow the number of possible combinations of bootboard length to be reduced in order to reduce the necessary adjustments of the ski boot binding devices. However, they still require a heavy investment for the purchase of the complete series of boots to cover all boot sizes.
There is therefore a need for another solution that reduces the investment cost of obtaining a series of ski boots.
The concept of the invention provides an inner slipper that comprises a bootboard and side walls and can be integrated into a conventional rigid shell of a ski boot to reduce the boot size defined by this rigid shell.
The invention is defined more precisely in the claims.
These objects, features and advantages of the present invention will be set forth in detail in the following description of one particular embodiment presented without implying any limitation, with reference to the accompanying figures, of which:
The invention is based on a ski boot 1 comprising the normal known components, in a form such as that illustrated in
The rigid shell may incorporate a bootboard, such as a bootboard generally known as a Zeppa, which is made separately and inserted into the shell, to finalize the lower part of the shell, in a well known process. This Zeppa bootboard usually has a roughly horizontal upper surface and a projecting lower part designed to be housed in a longitudinal groove formed in the shell, along the bootboard of the boot, during the injection molding process. The advantage of this manufacturing method is that it produces not only a shell of a relatively constant thickness by injection molding but also the Zeppa by a simple and inexpensive molding process, the placing of which in the shell makes possible the final formation of the larger volume of material necessary in the bottom of the shell, with the simultaneous provision of thermal insulation where the Zeppa meets the shell. A comfort innerboot 10 corresponding in volume to the internal volume defined by the rigid upper is then inserted into this upper, where it will accommodate the skier's foot. The comfort innerboot conforms closely to the inner surface of the rigid upper of the boot to ensure good transmission of the forces of the skier to the ski to give good control of the skis. The innerboot has a much more flexible structure than the rigid upper of the boot to give some measure of comfort to the skier whose foot and lower leg are directly in contact with the innerboot.
The invention is based on the use of a complementary component called a slipper, which is designed to be inserted into the basically conventional rigid shell of a ski boot to reduce the size of this upper. In the rest of this description of the embodiment of the invention, the word “size” will be used to denote integer sizes, the dimensions of which are standardized. However, the word “size” can have a broader meaning, which will be explained later. The insertion of a slipper into an injection-molded shell, which will here be termed the rigid outer shell, gives an assembly forming a shell with a smaller internal volume and therefore a smaller size.
This kind of shell produced by assembling a slipper into a rigid outer shell then accommodates a normal comfort innerboot, as will be detailed later. This makes it possible for a single injection-molded shell, made from a single injection mold, to be used for several different sizes of ski boot. This represents a considerable cost saving in terms of the manufacture of the series of boots, owing in part to the low cost of producing the slipper.
Applying the Mondopoint standard, the walls of the first slipper therefore have a total thickness such as to reduce the internal length of the shell by 10 millimeters, and the walls of the second slipper 20′ similarly have a total thickness such as to reduce the internal length of the shell by 20 millimeters. Consequently, as shown particularly in
In the embodiment shown in
According to the invention, the slipper 20, 20′ is made by a simple and economical manufacturing method using expanded polyurethane to obtain a semi-rigid component with a hardness of around 25 Shore D, between 20 and 30 Shore D, and with side walls less than 20 millimeters in thickness. As a variant the slipper may be made of rubber, of a recycled material, so as to obtain an equivalent hardness. The slipper is a simple shape and made of an expanded material, allowing production by a simple process employing low pressure and an inexpensive mold, especially as there is no need to obtain a clean, precise finish. This method thus results in the integration of a slipper between the rigid outer upper and the flexible innerboot, the hardness of which is intermediate between that of the rigid outer upper 2, 3 of the boot and that of the comfort innerboot 10, representing a good compromise between the desired end performance of the boot and its comfort.
A slipper such as this makes it possible to modify the boot size of a rigid boot shell when inserted into the shell, without necessitating the manufacture of a different shell, of a different size, and therefore without necessitating the use of another shell manufacturing mold thereby greatly reducing the manufacturing costs. As illustrated, several slippers 20, 20′ having the same external volume but different internal volumes can be used, when inserted into a single shell, to obtain multiple boots of different sizes. With this approach, one shell can either be fitted with no slipper, or with a slipper 20 of a first size, or with a slipper 20′ of a second size, so that a given rigid shell can be used to form three ski boot shells of different sizes. As a variant, more than two slippers could be used in one shell.
However, the greater the thickness of the wall of the slipper, the less the overall stiffness of the boot, and the more it will be difficult to reduce the initial volume of the shell evenly. This could reduce the performance of the boot and reduce its comfort. For this reason the use of only two slippers, with walls having a maximum thickness of approximately 10 millimeters in one case and 20 millimeters in the other, represents a good compromise and an optimal solution.
The invention also relates to a series of several boots comprising in particular a number of boots that is a multiple of three, i.e. three, six, nine and twelve ski boots, in which a given shell is used to obtain three different sizes. For this purpose, for each shell it is possible to insert either the traditional Zeppa bootboard, or a first slipper 20, or a second slipper 20′ of smaller internal volume, and each slipper may or may not be connected to the Zeppa bootboard, which can optionally be incorporated into the slipper. This makes it possible to make as many as three assemblies equivalent to three different sizes of shells from a single rigid outer shell manufactured by plastic injection molding. It is thus possible for example to manufacture a series of six ski boots for Mondopoint sizes 22 to 27, from 25 to 30, or from 28 to 33. For three injection-molded shells, it is possible to obtain nine sizes, for example from 22 to 30, the smallest shell being used for sizes 22 to 24, the intermediate shell for sizes 25 to 27, and the largest shell for sizes 28 to 30. As a variant, the nine sizes may cover sizes 25 to 33. In the same way, a series of twelve sizes, from 22 to 33, may be envisioned, from four different shells. In all cases, a different comfort innerboot is inserted into each of the different resulting shells, their size corresponding to the shell defined by the optional assembly of the rigid outer shell with a slipper. The result is that no shell receives multiple innerboots of different sizes to form different integer sizes, which is an advantage. As an additional remark, one injection-molded cuff is made for each injection-molded shell, and so it is also possible to use the same number of different cuffs as the number of shells and therefore a smaller number of injection molds to obtain the different boots of the series. As a variant, it is possible to provide different cuffs for one and the same shell, such as a different cuff for each size, or the same cuff for two successive sizes, thus using for example three different cuffs for a series of six sizes of boot and therefore for two sizes of outer shell. Lastly, because the different sizes use only a small number of different shells, a series of boots requires a small number of different adjustments of a ski boot binding device, more precisely one adjustment for each rigid outer shell, which is a great advantage, as observed earlier.
Naturally, the invention is not limited to making the series of ski boots detailed above. Any other series could be envisioned, comprising the use of at least one slipper to reduce the size of an injection-molded shell to produce two different sizes from one injection-molded shell, depending on whether or not a slipper is inserted. Furthermore, the concept of the invention has been described with reference to the inexpensive manufacture of a series of boots, in order to obtain different integer sizes, according to the Mondopoint size standard. It would of course be obvious to exploit this same concept to obtain half-sizes, or sizes defined by any other standard. In particular, the same concept can be used to form different boots, of different internal widths, for example at the metatarsophalangeal articulation, in order to use one and the same shell for maximum comfort, in the case of a large width, or for greater performance, for example competition, in the case of a narrow width. Thus, the concept of the invention makes it possible to modify the internal dimension of a shell in all directions, not only its length. The term “size” is thus used here to denote the internal foot-enclosing volume offered by a boot, with reference to all directions.
The invention also relates to a method of making a ski boot shell, comprising a step of making a rigid outer shell by injection molding of a rigid plastic, which method includes a step of making a slipper, and then a step of inserting the slipper into the rigid outer shell. The step of making a slipper may consist in making it from an expandable plastic.
The invention also relates to a method of making a series of ski boots, comprising a step of making at least two identical outer shells 2 by injection molding of a rigid plastic, which method includes a step of making a slipper 20, then a step of inserting the slipper 20 into an outer shell 2, so obtaining at least two ski boot shells of different sizes and/or which method comprises a step of making two different slippers 20; 20′, and then a step of inserting each slipper 20; 20′ into an identical outer shell 2, so obtaining at least two ski boot shells of different sizes.
The slipper 20, 20′ has been illustrated by way of example but it could have other geometries without departing from the concept of the invention. The slipper may incorporate the structure of the traditional Zeppa and be incorporated in a shell instead of the Zeppa, or not incorporate it and be added along with the Zeppa in a shell. Again, its side walls may take other shapes, greater or lesser heights, less regular around the perimeter of the foot. However, these side walls are sufficient to reduce a particular shell by at least one size when inserted, and therefore they must have a minimum surface area distributed around the periphery of a skier's foot. The side walls of the slipper thus advantageously occupy the complete perimeter of the bootboard, in such a way that they can completely enclose a skier's foot, or more precisely the comfort innerboot comprising the foot of a skier. This perimeter does not have to be completely continuous, and grooves, openings or any form of interruption may be provided, without however excessively interrupting the side walls which occupy at least half of the perimeter of a foot in order to perform their function. Perforating the walls is a possible way of reducing the weight and cost of the slipper. Furthermore, these walls are of sufficient height to cover the side of a foot and reach at least somewhat on to the top of the foot, in order to define a sufficient volume around the foot.
The three components of the wall of the resulting boot, i.e. the wall of the outer shell, the wall of the slipper, and the wall of the comfort innerboot, are made with dimensions such as to press against each other in order to provide a boot that performs well in the transmission of forces from the foot to the ski.
An embodiment of the invention of this kind offers equipment hire stores great flexibility. In the first place, purchasing a series of boots is much cheaper. Secondly, since the same shell can be used for a plurality of different sizes by adding a removable element, a slipper, it is much less likely to run out of a certain size because it needs only have a sufficient quantity of slippers in stock to reduce this risk.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09425388.7 | Oct 2009 | EP | regional |
