U.S. patent number 3,892,077 [Application Number 05/462,548] was granted by the patent office on 1975-07-01 for insole.
Invention is credited to Philip Robert Hunter, George Watts, James Graham Wolstenholme.
United States Patent |
3,892,077 |
Wolstenholme , et
al. |
July 1, 1975 |
Insole
Abstract
In an insole for use in, or actually defining the sole of,
footwear, an envelope generally shaped like a foot or a portion of
a foot and preferably made of a plastics material such as
polyurethane or polyvinylchloride, and having a perimeter which is
adapted to remain of stable configuration under the weight of the
wearer, has at least one region containing a liquid having a
viscosity at 37.degree.C which is substantially equal to that of
glycerine at that temperature. The said region may be bounded at
the front by a transverse line in the vicinity of the metatarsal
head of the toes, by arcuate zones (concave in plan view) in the
vicinity of the instep and a substantially semi-circular end zone
in the vicinity of the heel of the foot.
Inventors: |
Wolstenholme; James Graham
(Mears Ashby, Northamptonshire, EN), Watts; George
(Mears Ashby, Northamptonshire, EN), Hunter; Philip
Robert (Holmer Green, Buckinghamshire, EN) |
Family
ID: |
23836836 |
Appl.
No.: |
05/462,548 |
Filed: |
April 19, 1974 |
Current U.S.
Class: |
36/44; 36/71 |
Current CPC
Class: |
A43B
7/28 (20130101); A43B 13/189 (20130101); A43B
17/14 (20130101) |
Current International
Class: |
A43B
7/14 (20060101); A43B 7/28 (20060101); A43b
013/38 () |
Field of
Search: |
;36/43,44,28,71 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawson; Patrick D.
Attorney, Agent or Firm: Cushman, Darby & Cushman
Claims
We claim:
1. An insole defined by an envelope having at least one flexible
side generally shaped like at least a portion of a foot and welded
about the perimeter;
a first zone in said envelope defining a single cavity bounded at
the front by a transverse line forward of the metatarsal heads of
the toes of the foot, by arcuate perimeter portions concave in plan
view on either side of the foot in the vicinity of the instep of
the foot and a substantially semi-circular end perimeter portion in
the vicinity of the heel, and said first zone containing a liquid
sealed inside; and
a second zone in said insole defining an empty zone bounded by a
portion of the perimeter of said insole at an area of arch support
and by a weld inwardly of said portion also in said area of arch
support.
2. An insole according to claim 1 wherein said liquid has a
viscosity at 37.degree. C substantially equal to that of glycerine
at that temperature.
3. An insole according to claim 1, wherein the envelope is made of
a plastics material.
4. An insole according to claim 3, wherein said material is
polyurethane film.
5. An insole according to claim 3, wherein the material is
polyvinylchloride.
6. An insole according to claim 5, wherein said envelope is made
from a sheet of said polyvinylchloride 0.020 inch thick.
7. An insole according to claim 4, wherein said film is 0.010 inch
thick.
8. An insole according to claim 1, wherein said first zone is
charged with between 5 and 60 cubic centimetres of glycerine.
9. An insole according to claim 1, wherein forward of the
metatarsal heads of the wearer's toes and separated from said
second zone by a weld, a third zone of said insole containing a
foam plastic material.
10. Footwear having an insole according to claim 1 forming part
thereof.
Description
This invention relates to an insole for use in footwear.
Although a pair of insoles would normally form a separate article
of commerce from, and be intended for insertion in, a pair of boots
or shoes, it could also conceivably be integral with, so as to form
part of, such footwear. Accordingly, for the purpose of this
specification, the term "insole" is intended to cover both the
possibilities and not to be regarded as limited to an article
separate from the boot or shoe in which it is intended to be worn;
that is to say, it is intended to connote an item in, or for use
in, footwear on which the underside of the wearer's foot rests.
With a view to increasing the comfort (or decreasing the
discomfort) of the wearer of footwear, many different kinds of
insole giving a "padding" or cushioning effect have previously been
proposed. It is an object of the present invention to provide an
insole capable of giving the wearer a greater degree of comfort by
giving the foot a greater degree of support in the manner required
in the course of its normal movements.
In an insole according to the present invention, an envelope has at
least one flexible side generally shaped like a foot or a portion
of a foot, a perimeter which is adapted to remain of stable
configuration when pressure is applied to the said side, and at
least one region in which the envelope is charged with a liquid
having a viscosity at 37.degree. C which has a value substantially
equal to that of glycerine at that temperature.
The said region is preferably bounded at the front by a transverse
line forward of the metatarsal heads of the toes, by arcuate
portions of the perimeter of the insole, concave in plan view, on
either side of the foot in the vicinity of the instep and a
substantially semi-circular end portion of the perimeter in the
vicinity of the heel.
The envelope is preferably made of a plastics material, such as
polyurethane film or polyvinylchloride, the said perimeter of which
is preferably defined by a weld.
Apart from the important viscosity characteristic of the said
liquid, the latter should also be innocuous (in the event of
failure of a said weld) and devoid of properties tending to inhibit
welding of the said perimeter.
If desired, the said envelope may be partly or entirely surrounded
by a further envelope or skin of like material, and additional
cushioning obtained by providing an air cushion in the space
between the two envelopes; in such a construction, a self-sealing
air valve may be provided for the purpose of "blowing up" the said
space with a predetermined amount of air, depending on the
orthopaedic requirements of the wearer.
One form of insole embodying the invention will now be described,
by way of example only, with reference to the accompanying
diagrammatic drawing which shows the right hand one of a pair of
said insoles in plan view.
Referring to the drawing, an envelope 1 consists of an upper and a
lower sheet of polyvinylchloride, defining a top and a bottom side
generally shaped like a foot.
These two sheets of PVC, each of which is 0.020 inch thick, are
joined together along a perimeter in the form of a weld seam 2 in
such a way that the configuration of the envelope remains stable
when pressure is applied to the upper side by the foot of the
wearer.
In a region 3, bounded by perimeter zones 4, 5 and 6, the envelope
is charged with between 5 and 60 cubic centimetres of glycerine,
the amount depending on the size of the insole.
A zone 7 of the envelope, forward of the metatarsal heads of the
wearer's toes and separated from the region 3 by the weld 5,
contains a foam plastics material. This zone 7 is desirable to
provide additional cushioning particularly for the benefit of
wearers suffering from "claw toes", the foamed material preferably
being foamed PVC.
A zone 8, separated from the region 3 by the arcuate weld 6 is left
empty; i.e. it contains neither the liquid contained in the region
3 nor the foamed PVC contained in the zone 7.
In the manufacture of an insole in accordance with the invention,
the envelope is first produced by welding together the two sheets
of PVC defining the two sides of the insole, leaving a small gap in
the weld through which the required quantity of liquid is
introduced, whereafter the perimeter is sealed off by closing up
the said gap by a further welding operation.
It will be appreciated that the quantity of liquid used in an
insole depends not only on the size of the insole (which is
produced in a range of sizes, similar to the usual range of sizes
of boots and shoes) but also on the orthopaedic or other medical
requirements of the wearer, particularly if the insole is to be
used to alleviate an orthopaedic disorder, rather than to add to
the comfort of walking of a wearer with normal healthy feet.
In order to provide the most comfortable rate of transference of
the cushioning effect along and across the insole, as pressure on
it is cyclically transferred to different parts of the said region,
the rate of flow of the liquid to and from those parts is a
critical characteristic, dependent on the hydraulic conditions
prevailing, of which the viscosity of the liquid probably
constitutes the most important parameter.
The invention also includes within its scope any footwear having an
insole as hereinbefore defined and described disposed therein or
forming part thereof. Indeed, certain special footwear, e.g. for a
particular remedial, sporting or other recreational requirement may
have merely one sole, such sole being constructed in the manner of
the said insole; hence the term "insole" should not be construed at
being limited to a sole which is necessarily associated with some
further and outer sole, since it may, also within the scope of the
invention, constitute the only sole of the footwear.
As an alternative to polyvinylchloride, the envelope 1 may consist
of an upper and a lower sheet of polyurethane film having a
thickness of, for example, between 0.005 inch and 0.015 inch, and
preferably a thickness of 0.010 inch.
* * * * *