US 3760056 A
An improved method for custom fitting an inflatable bladder (e.g., for ski boots or the like) to a portion of a person's anatomy (e.g., a wearer's foot). The inflatable bladder is made of a suitable elastomer (e.g., ether base polyurethane) which may be heated, distended and then cooled to room temperature to set the bladder in the distended shape. A preferred embodiment of the improved method comprises placing the inflatable bladder on a wearer's foot, placing the boot to be worn on the wearer's foot over the bladder, heating the bladder, inflating the bladder to a desired pressure to force the bladder into intimate contact with the wearer's foot and cooling the bladder to room temperature to set it in its distended shape. The bladder, which now conforms to the contour of the wearer's foot, is deflated and the boot and bladder are removed. When the bladder is later re-inflated, it will custom fit the wearer's foot.
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[ 3,760,056 Sept. 18, 1973 METHOD FOR CUSTOM FITTING AN INFLATABLE BLADDER TO A WEARERS FOOT  Inventor: Marion F. Rudy, Northridge, Calif.
 Assignee: Robert C. Bogert, Woodland Hills Calif.
22 Filed: Sept. 23, 1970 21 Appl. No.1 74,791
 US. Cl. 264/299, 36/25 AL, 36/2.5 N, 36/71, 128/90, 128/382, 264/DIG. 30,
 Int. Cl..... B29c 27/20, B29c 17/00, A43b 7/20  Field of Search 264/36, 222, 223, 264/230, DIG. 30; 18/5.1, 19 S, 19 R, 45 R; 128/382, 402, 90; 3/20;- 36/71, 2.5 R, 2.5 N,
OTHER PUBLICATIONS Glasstone, Samuel, Textbook of Physical Chemistry,
Arron 128/382 X Van Hostrand, New York, 1946, page 442.
Primary Examiner-Donald J. Arnold Assistant Examiner-W. E. Hoag Attorney-Bernard Kriegel  ABSTRACT An improved method for custom fitting an inflatable bladder (e.g., for ski boots or the like) to a portion of a persons anatomy (e.g., a wearers foot). The inflatable bladder is made ofa suitable elastomer (e.g., ether base polyurethane) which may be heated, distended and then cooled to room temperature to set the bladder in the distended shape. A preferred embodiment of the improved method comprises placing the inflatable bladder on a wearers foot, placing the boot to be worn on the wearers foot over the bladder, heating the'bladder, inflating the bladder to a desired pressure to force the bladder into intimate contact with the wearers foot and cooling the bladder to room temperature to set it in its distended shape. The bladder, which now conforms to the contour of the wearer's foot, is deflated and the boot and bladder are removed. When the bladder is later re-inflated, it will custom fit the wearer's foot. 1
Preferably, the elastomer from which the bladder is made will return to its original shape when reheated.
Thus, the bladder may be reheated to restore it to its 7 Claims, 6 Drawing Figures PATENTED SEP 1 a ma' snarl or 2 INVEA/ TOE. MQQ/aA/LRUDM WIM/ irraeA/Ey PATENTED SEP! 8 I973 Sum a or z IA/vEA/roe Mae/01v 1: R00 y METHOD FOR CUSTOM FITTING AN INFLATABLE BLADDER TO A WEARER S FOOT The present invention relates to an improved method for custom fitting an inflatable article to an object. More particularly, this invention relates to an improved method for custom fitting an inflatable bladder (e.g., for footwear, helmets, shoulder pads, etc.) to a portion of a persons anatomy (e.g., a foot, head, shoulders, etc.)
Various types of inflatable bladders have been proposed for use in sporting boots and the like (e. g., skiing, hiking, skating, orthopoedic and military boots). One such inflatable bladder is disclosed in applicants copending U. S. Patent application Ser. No. 51,841, filed July 2, 1970, now U.S. Pat. No. 3,685,176, issued Aug. 22, 1972 entitled Inflatable Article of Footwear. The inflatable bladder disclosed in that application comprises a plurality of interconnected tubes and cavities geometrically designed to provide a firm, but comfortable, restraining force on a wearers foot. In use, the bladder prevents relative lateral movement of the foot within the boot while permitting limited fore and aft movement of the leg. The bladder is preferably made of a suitable elastomeric material, such as ether base polyurethane. 1
Inflatable footwear bladders (of the type disclosed in the aforesaid co-pending application, for example) are manufactured in various foot sizes, and each bladder is designed to conform to the contour of the average foot of that size. However, such a bladder will not fit as well on a foot whose contour varies significantly from the contour of an average foot of that size.
The method of the present invention is designed to provide an effective, yet inexpensive technique for custom fitting such inflatable bladders or the like to feet or'other objects having complex contours.
According to a preferred embodiment of the invention, an inflatable bladder is custom fit to a particular foot in the following manner.
The bladder is first placed over the foot, and'the footwear (e. g., a ski boot) to be worn in conjunction with the bladder is placed on the foot over the bladder. The bladder is heated and then inflated to force it into intimate contact with the foot, the footwear exerting a constraining force on the bladder. Thereafter, the bladder is cooled, as to about room temperature, to set" the bladder in its distended shape, wherein it conforms to the contourof the foot. The bladder may then be deflated and the boot and bladder may be removed from the wearers foot. Whenever the bladder is placed on the wearers foot and inflated, it will closely conform to the exterior contour of the foot.
A relatively thin heating sock" (e. g., a sock havin electric heating elements therein) may be employed to heat the bladder before it is inflated. The sock is placed over the bladder before the boot is placed on the wearers foot and secured in closed position thereon. After the boot is donned, but before the bladder is inflated, the heating elements in the sock are energized to heat the bladder.
The steps of inflating and cooling the bladder may be performed simultaneously by employing a compressed gas (e. g., carbon dioxide) for inflating the bladder, which cools considerably in expanding into the bladder.
In use, the custom-fit bladder, when inflated, compensates for relatively severe variations in the size of the space between the wearers foot and the boot (caused, for example, by different sock thicknesses, swelling of the foot, etc.). Accordingly, a greater degree of pressure distribution control over the wearers foot is obtained when the custom-fit bladder is inflated and used.
The elastomeric material from which the bladder is made is preferably of a type which returns to its original size and shape when reheated. In other words, the bladder has heat shrink memory characteristics. Thus, the bladder may be custom fit to other feet by simply heating the bladder to restore it to its original shape and thereafter re-employing the method of the present invention.
Other features and advantages of the present invention will become apparent from the following more detailed description of a preferred embodiment.
In the drawings:
FIG. 1 is an isometric view illustrating the manner in which an inflatable bladder for a ski boot or the like and a heating sock are placed on a wearers foot preparatory to custom fitting the bladder to the foot;
FIG. 2 is an enlarged section taken along the line 2 2 of FIG. 1, showing the valve structure for inflating the bladder;
FIG. 3 is an enlarged fragmentary section taken along the line 3 3 of FIG. 1, showing the relationship of the arch of the wearers foot, the inflatable bladder, the heating sock, and the boot before the bladder is inflated', 5
FIG. 4 is an isometric view of a heating sock which may be employed to heat the bladder;
FIG. 5 is a cross-section taken along the line 5 5 of FIG. 1, showing the relationship of the wearers foot, the inflatable bladder, the heating sock, and the boot just prior to the time the bladder is heated and inflated; and
FIG. 6 is a cross-section similar to FIG. 5, showing the relationship of the wearers foot, the inflatable bladder, the heating sock and the boot after the bladder has been inflated to force it into intimate contact with the wearers foot.
While the preferred embodiment of the present invention described below and illustrated in the drawings is directed to custom fitting an inflatable bladder for a ski boot or the like to a wearers foot, it is to be understood that the improved method of this invention has numerous other applications.
The inflatable bladder 10 shown in the drawings is the improved bladder which is the subject of the aforesaid 'copending U. S. Patent application Ser. No.
51,84l/It is to be understood, of course, that the improved method of the present invention may be employed to custom fit othertypes of inflatable bladders to feet or other objects having complex contours.
The inflatable bladder 10, made of a suitable elastomeric material, is adapted to be disposed around the foot 12, ankle and lower leg portion 14 of the wearer' for exerting a holding force thereon. The bladder comprises two plies 16, 18 of elastomeric sheet material, such as non-porous, ether base polyurethane sheeting that is highly resistant to moisture degradation, extremely tough, and puncture resistant. Essentially, the inflatable bladder 10 is a sock-like member having a plurality of inflatable chambers, cavities and tubular portions 20 formed by the two sheets 16, 18. The tubular chambers 20 extend along and are disposed at different portions of the foot 12, ankle joint and lower leg.
' A manifold 22 interconnects the tubes 20 to provide uniform fluid pressure in all regions of the bladder.
The type and thickness of the elastomeric material and the cross-sectional dimensions of the tubes and cavities 20 are such that when the bladder is inflated to the desired pressure, the tubes and cavities will assume a substantially circular cross-sectional shape. The tubes will have varying degrees of rigidity, depending on the inflation pressure, and will be capable of supporting relatively high localized loads without collapsing.
The bladder employed in the method of the present invention is preferably separate from the ski boot 23 or other footwear with which it is employed.
The inner layer 18 of the bladder 10 is preferably covered with a layer of suitable resilient material 24, such as a cellular polyurethane foam which is readily yieldable and comformable. The foam layer 24, in turn, is covered with an inner liner 25 of lambs wool or the like. The foam and the lambs wool liner between the inflatable plies 16, 18, and the wearers sock 26, provide added comfort to the wearer and greater comformance of the bladder to the foot.
In practicing the method of the present invention, the bladder 10 to be custom fitted to the foot 12 is first placed over the sock 26 disposed on the wearers foot. Thereafter, a heating sock 28, particularly designed for use in the method of the present invention, is placed over the bladder 10 on the wearers foot. It will be noted that the forward edge 30 of the bladder 10 terminates behind the toes of the foot 12, and that the heating sock is cut to substantially cover the bladder and be substantially co-extensive therewith. However, the sock may be electrically connected so that discrete areas of the sock may be heated on a command basis.
The heating sock 28, best shown in FIG. 4, comprises a relatively thin sock-like member having electric heating elements (not shown) disposed therein. An electrical cord 32 containing the usual conductors is connected to the sock for energizing the heating elements, and an opening 34 is provided in the upper rear portion of the sock for accommodating the inflation valve 40 of the bladder, described hereinafter.
After the heating sock 28 has been donned, the ski boot 24 (or other footwear) to be worn in conjunction with the bladder is placed on the wearers foot over the sock 26, bladder 10 and heating sock 28 (FIG. The boot is buckled by means of closure devices 29 (FIGS. 5 and 6), which are described in some detail inthe aforesaid co-pending application, Ser. No. 51,841.
The cord 32 from the heating sock 28 is then connected to a conventional source of power (not shown) to energize the heatingelements in the sock and heat the sock and bladder to'a temperature well above room temperature (e. g., between about 125 F. and about 300 F.). When the bladder reaches the desired temperature, the application of current to the heating sock is discontinued and the bladder inflated to a sufficient pressure (e. g., between about 1 p. s. i. and about 17 p. s. i.) to force the inner lining 25 of the bladder into intimate contact with the foot 12 and the heating sock 28 into intimate contact with the boot 24 which provides an external constraining force on the bladder, the inner portions of which will substantially conform to the exterior contour of the foot.
The inflated bladder is then cooled sufiiciently, as to about room temperature, to set the bladder in its distended shape, wherein it conforms to the contour of the wearers foot 12.
The bladder is thereafter deflated and the boot 24 removed, as well as the heating sock 28 and the bladder. Whenever the bladder is replaced on the wearers foot 12 and inflated it will conform to the contour of the foot.
The temperature to which the bladder is heated and the pressure to which it is inflated are interdependent. The higher the temperature, the lower the pressure required to force the bladder into intimate contact with the foot to conform to its contours. The pressure must be sufficient to cause the bladder to conform to the wearers foot, but not so great that it will destroy the supporting characteristics and quality of the bladder.
The optimum temperature and pressure ranges will depend upon the heat absorbing and the polymer characteristics and the thickness of the particular elastomer employed. A range of materials are available with a large selection of stress-temperature vs. permanent-set characteristics. Where the bladder layers 16, 18 are ether base, polyurethane sheets, having wall thicknesses between about 0.010 and 0.020 inches, the optimum temperature range has been found to be about 300 F; and the optimum pressure to which the bladder should be inflated has been found to be between about 1 psi. and about 17 p. s. i., preferably about 4 p. s. i. The heated bladder need be left in the distended position for less than 1 minute. The inflating and cooling steps are preferably accomplished simultaneously by using a cold pressurized gas (e. g., carbon dioxide) to inflate the bladder, the expansion of the gas from its compressed state into the bladder at a lower pressure inherently providing the desired refrigeration effect.
As best shown in FlG. 2, the bladder 10 is inflated by means of a valve 40 opening into one of the tubes 20 adjacent the rear portion of the bladder. A valve body 41 is secured to an elastomer support plate 42 suitably attached to the inner surface of the outer layer 16 of the tube 20. The inner portion of the valve body 41 has a circumferential groove 43 in which the plate 42 is received. The valve body has a central outer passage 44 and a pierced inner passage 45 communicating with the interior of the tube. The elastomeric material of the valve body 41 inherently constricts and normally retains the pierced passage 45 closed. The valve body 41 extends through the opening 34 in the heating sock and through an enlarged rear opening 46 in the collar of the boot 24.
Inflation and deflation of the bladder can be accomplished by any suitable inflation means, such as the mechanism shown in the aforesaid co-pending U. S. Patent application, Ser. No. 51,841.
The bladder 10 is preferablyconstructed of a material which will return to its original, undistended shape when it is reheated; i. e., a material exhibiting heat shrink memory characteristics. Thus, the bladder may be reheated to restore its original shape, and the method of the present invention may thereafter be reemployed to custom fit the bladder to another foot.
While the method of the present invention has been described above with reference to custom fitting a particular inflatable bladder, designed for use in ski boots and the like, it is, of course, contemplated that the method of the present invention may be employed when itis desired to custom fit any inflatable bladder to a body having a complex contour.
1. In a method for custom fitting an inflatable and deflatable bladder to the exterior of an individual's foot,
the steps of: I
a. disposing an elastomeric plastic bladder having a heat shrink memory operational within a temperature range of about l25F to about 300F., and having opposed adjacent walls defining a plurality of chambers adjacent said foot,
b. disposing a heating member over said bladder,
c. disposing a boot over said heating member,.
d. heating said bladder to a temperature in the range from about l25F to about 300F.,
e. inflating said bladder to a pressure from about 1 psi to about 17 psi to conform said bladder to the shape of said foot and said boot,
f. cooling said bladder while inflated and disposed adjacent said foot and inside said boot, to set said bladder in the conformed shape, and
g. deflating said cooled and formed bladder, whereby the conformed shapes are retained and said bladder may be reinflated for use.
2. The method of claim 1 wherein said bladder is formed of an ether based polyurethane.
3. The method of claim 2 wherein the walls of said polyurethane are from about 0.01 to about 0.02 inches in thickness.
4. The method of claim 1 wherein said pressure is about 4 psi.
5. A method of claim 1 wherein said chambers are tubes disposed lengthwise of said foot.
6. The method of claim 1 wherein said cooling and inflating are effected simultaneously by the addition of a fluid at a temperature substantially below the temperature of the heating step.
7. The method of claim 6 wherein said fluid is compressed carbon dioxide.
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