Note: Descriptions are shown in the official language in which they were submitted.
Shoe
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The present invention is directed to a shoe, especial1y for diabetics or
rheumatics, comprising a footbed, a cover layer on the footbed, a
cushion portion disposed in the footbed, especially in the middlefoot
range, heel range and/or toe range, and an intermediate sole.
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Such shoes which are upholstered in a special manner are known. They are
used in the orthopedic field, however, are also designed for human
beings which are very pain-sensitive at the foot, as for example
rheumatics. Furthermore, such shoes are used by diabetics who, in old
age, have frenquently nerve disturbances which manifest in an
- insensibility of the foot. Such human beings perceive pressure pain only
; in an incomplete manner or no more at all so that, if normal footwear is
worn, permanent damages of the foot result.
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During normal walking or running a horizontal forwardly directed
- component of movement of the foot in the shoe results so that the foot
has to receive corresponding thrust forces or shear forces. It is just
this component of movement which stresses the foot especially high and
;~ results in the above-mentioned permanent damages of the foot with
~ 20 diabetics or in pain appearances with human beings having expecially
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! sensitive feet, for example rheumatics.
In order to guard against these appearances specially upholstered shoes
have been developed which are upholstered in the ranges of the foot
mostly endangered, namely the middlefoot range, heel range and/or toe
range. However, one has observed that with the developments up to now
just the thrust loads and shear loads generated by the horizontal
component of forward movement of the foot can only be reduced in an
insufficient manner.
` It is the object of the invention to provide a shoe of the
above-described kind which offers an especially good wear comfort and
which especially reduces thrust loads and/or shear stresses of the foot
during forward movements of the same in the shoe.
According to the invention this object is achieved with a shoe of the
above-cited kind by the feature that the cushion portion has a
multi-layer structure and includes a soft upper layer, a hard
intermediate layer and a medium hard lower layer.
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-`~ Accordingly, the shoe according to the invention, which can be any kind
of shoe, especially a sandal, has the known footbed serving as static
~` framing with a cover layer disposed thereabove. A multi-layer cushion
`~, portion is inserted into the footbed and has, from above to below, a
soft layer, a hard layer and a medium hard layer. With such a
multi-layer structure optimum results have been obtained for achieving
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the above-cited object. It has been observed according to the invention
that the upper layer has to be formed correspondingly soft and has to
;~ have an especially low restoring force in order that the individual
~ 30 footbed of the patient can be formed. The intermediate layer has to be
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formed correspondingly hard and has to have a high restoring force in
order to provide for the support or the strength of the cushion portion.
The lower layer is formed medium hard and has a medium large restoring
force in order to enable that a bone of the foot having a lower location
can be pressed deeply into the cushioning. In this case, the
intermediate layer can be pressed into the lower layer on account of the
bone with the deeper location, so that the lower layer takes over a
corresponding function of protection and takes over corresponding
cushioning functions even for cases with especially deeply located
bones.
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Accordingly, the formation of the individual footbed and simultaneously
a sufficient support of the foot in the specially upholstered critical
range and a safe cushioning even of deeply located bones is achieved by
the inventive multi-layer structure of the cushion portion which has at
least the above-cited three layers. Thus, the invention represents an
essential improvement with respect to the incomplete solutions of the
; prior art. Especially, the thrust stresses and/or shear stresses of the
foot generated during a horizontal movement of the foot in the shoe are
damped to the greatest part by the elastic guidance of the foot through
the upper layer of the cushion portion, wherein the intermediate layer
` gives the foot a sufficient support effect so that the foot does not
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~~ "float" in the footbed. Such thrust stresses and/or shear stresses-are
;- sufficiently damped by the medium hard lower layer even with regard to
deeply located bones.
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The cushion portion can be disposed in the footbed in an areally
confined manner and can be associated with one or more critical ranges
of the foot. These critical ranges are especially the middlefoot range,
~' 30 heel range and/or toe range. So, according to a special embodiment of
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¦ the invention the cushion portion is located in the middtefoot range of
the footbed. According to a special embodiment the upper and
intermediate layers extend over the whole footbed, while the lower layer
is areally confined and especially covers only the middlefoot range,
heel range and/or toe range. In this case, the whole footbed is
cushioned by the two upper layers, while the lower layer, which takes
over a damping or protecting function for a deeply located bone or
inflammations, ulcera, cicatrizations and open wounds, is only provided
in the critical range in which this deeply located footbone etc. can
occur.
The footbed itself consists for example of the customary construction of
a cork-latex mixture. It has one or several recesses for the cushion
portion, wherein the cushion portion preferabty extends through the
lS footbed to the intermediate sole. A customary cover layer, preferably
` consisting of shamoy-dressed leather, is located on the upper side of
the footbed.
As regards the thickness of the cushion portion, the upper layer has
preferably a thickness of 1- 3 mm, the intermediate layer has preferably
a thickness of 2-- 4 mm, and the lower layer has preferably a thickness
; of 5 - 7 mm. Especially preferred values are 2 mm for the upper layer, 3
mm for the intermediate layer and 6 mm for the lower layer. Of course,
the thickness of the layers can be varied in adaption to the footbed.
-1 25 Accordingly, the above-indicated values are average values. The relative
large thickness of the lower layer results from the fact that the same
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is to enable that the intermediate layer can be pressed into the lower
layer with a deeply located bone etc., however, cannot be pressed
through to the intermediate sole.
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Open-cell foam rubber (cellular rubber) is a preferred mater~al for the
upper layer. The desired characteristics, as relative small restoring
ability for the formation of the individual footbed, can be obtained
with this material. The intermediate layer, which is especially hard and
strong compared with the two other layers, consists preferably of
closed-cell foam rubber (cellular rubber) which has the required high
restoring ability so that the intermediate layer can serve in a way as
support layer for the multi-layer structure. The lower layer consists
preferably of open-cell foam rubber (cellular rubber), wherein, however,
this material is harder than that of the upper layer and has a medium
restoring ability compared with the two other layers which is higher
than the restoring ability of the upper layer, however, smaller than
that of the intermediate layer.
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Preferably, the footbed is ground in a roll-like manner fore and aft in
order to guarantee a good step development.
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~ The intermediate sole of the shoe is formed, for example, as stiff sole
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m-~ or as rigidifying sole. This embodiment is especially suited for
diabetics since hereby punctual compressive stresses are uniformly
distributed on the foot. The desired load relief of the foot, especially
at the mentioned critical location, can be obtained hereby in connection
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~with the inventive cushion portion. It is recommended with regard to
especially pain-sensitive feet, for example with rheumatics, to replace
,~ 25 such a rigid intermediate sole by a soft intermediate sole which
generates a buffering effect and, if possible, can also result in a load
balancing.
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'~5,' The intermediate sole is preferably located in a hollow space of the
footbed. By this, it can be fixed at the footbed in an especially
- 6 - 2107831
favourable manner, and the shoe as a whole has a less weighty appearance
since its height is reduced. Furthermore, this embodiment can be
manufactured in an especially favourable manner.
According to a special embodiment of the invention a fourth layer
consisting of a deformable cushion material is located between the
three-layer structure of the cushion portion and the intermediate sole.
The deformable cushion material can be a deformable thermoplastic
cushion material which can be well adapted to the footbed in order to
realize an adaption to the roll of the footbed fore and aft. This fourth
layer has the function of an additional cushioning. Accordingly, such a
~- fourth layer is only used in special cases.
Of course, apart from this the footbed can be shaped at will and can be
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adapted to the respective shapes of the foot.
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Supplementary, it should be mentioned that the inventive cushion portion
` can be also located in the longitudinal arch of the footbed. Such an
embodiment is especially suited for a flat foot or a chacot foot.
An additional cushioning of the foot is obtained by means of the shaft
of the shoe. So, one embodiment of the invention has a shaft which
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$~ includes; from the outside to the inside, a leather layer, a reinforcing
~` band, a foam rubber layer and a lining leather layer. The outer leather
' 25 layer preferably consists of nappa leather. The foam rubber layer
(cellular rubber layer) is preferably a layer consisting of a
~, closed-cell foam rubber, wherein the layer preferably has a thickness of
3 mm. The lining leather is tanned in a vegetabile manner and is thus
free of chromium.
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According to an improvement of the inventive shoe the footbed is
provided with a longitudinal arch-support. A further embodiment is
characterized by the feature that the footbed has a heel inclination.
Preferably, the heel inclination extends over substantially the half of
5 the heel range of the footbed and ascends towards the inner edge of the
footbed.
Especially good results are obtained with a combination of both
features. 8y this, in connection with the inventive cushion portion with
multi-layer structure an especially good support of the foot is obtained
because punctual supporting, as a normal longitudinal arch-support or a
~` sustemtaculum support, which can cause pain, is avoided. With the kind
of support selected according to the invention it is possible to again
bring the foot of the diseased person (rheumatic, diabetic) into static
balance. Accordingly, the solution selected according to the invention,
-~ which is a solution for the complete area, is the consequent
continuation of the provided cushion portion with which also punctual
influences are avoided.
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Furthermore, the present invention is directed to an insole for a shoe,
especially for diabetics and rheumatics, which has a cushion portion
with multi-layer structure according to one of the preceding claims.
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In the following the invention is described in detail by means of an
` 25 example in connection with the drawings. Of the drawings:
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figure 1 shows the footbed of a shoe in three-dimensional
representation;
figure 2 shows the footbed of figure 1 with a portion cut away in
~ - 8 21~7 ~3 ~
order to show the structure of the cushion portion, in an
enlarged scale;
figure 3 shows a cross-section through the shaft material of the
shoe; and
figure 4 shows a part plan view and a cross-sectional view through
the heel portion of the shoe.
The footbed shown in figures 1 and 2 belongs to a shoe which is suited
for diabetics. The remaining parts of the shoe, with the exception of a
~ cross-section through the shaft material, are not shown since they have
; no importance for the invention and can be formed customarily. So, the
~-` shoe can be a sandal, for example.
~- The footbed 1 consists of the customary cork-latex-mixture and is
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~- adapted to the shape of the foot. It is formed in a trough-like manner
- and has on its underside a central recess for the arrangement of a rigid
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sole 8. A cover layer 4 consisting of shamoy-dressed leather is disposed
on the upper side of the footbed. This cover layer is customarily
formed.
,.....
The footbed has in the middlefoot range 3 (in the figures shown with
dashed lines) a recess which takes up a multi-layer cushion portion.
-~ 25 This multi-layer cushion portion includes three layers of which the two
-~ upper layers substantially extend over the whole footbed and terminate
at the footbed edges, while the lower layer is confined to the
middlefoot range. The cover layer 4 extends over the cushion portion so
that a uniform termination results on the upper side of the footbed. On
the underside the lower layer 7 adjoins the rigid sole 8.
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With such a cushion portion 3 with multi-layer structure the compressive
stresses and/or shear stresses of the foot in this range, especially
with deeply located bones etc., can be substantially reduced. A
sufficient cushioning of the foot is guaranteed, wherein the upper layer
5 provides for the formation of the individual footbed while the
intermediate layer 6 gives the cushioning the corresponding stability.
The lower layer 7 serves as buffering layer in order to enable that the
intermediate layer 6 can be pressed in with deeply located bones etc..
The upper layer 5 has an average thickness of 2 mm and consists of an
open-cell foam rubber NR which has the following material
characteristics:
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raw material base: SBR + NR
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ASTM grade: Re 42 - 43
strain-hardness: 35 - 91 kPa
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~- compression strain test: 50 - 60 %
- raw density: 180 - 280 kg/m3.
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This is a relative soft material which has a low restoring ability.
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The intermediate layer 6 consists of a closed-cell foam rubber and has a
j thickness of about 3 mm. The density of the material is 0.07 g/cm3, and
I the hardness/Shore is A 18. The material is relatively hard and strong
and has a high restoring ability.
The lower layer 7 consists of an open-cell foam rubber NRB and has an
average thickness of about 6 mm. The material is relatively strong and
hard and has the following characteristics:
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raw material base: SBR + NR
ASTM grade: RE 43
strain-hardness: 63 - 91 kPa
compression strain test: 45 - 55 %
raw density: 160 - 240 kg/m3.
The material of the lower layer 7 has a restoring ability which is
greater than that of the upper layer, however, smaller than that of the
intermediate layer. All the layers are bonded to one another and in the
footbed in a suitable manner.
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The rigid sole 8 can consist of hard paper (Pertinax), for example. This
~` is a thin material with a high strength and a low weight. The thickness
is about 3 mm. Such a rigid sole distributes the compression stress
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-, 15 uniformlY
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~ Figure 3 shows a cross-section through the shaft material for the shoe.
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; Also the shaft material is upholstered correspondingly in order to avoid
compression stresses of the foot. From the outside to the inside it
,"~ 20 consists of a nappa leather layer 10, a reinforcing band 11, a cushion
layer 12 of closed-cell foam rubber with a thickness of about 3 mm and a
s~ layer 13 of lining leather tanned in a vegetabile manner.
For comparison purposes, also cushions with four and five layers have
been tested. Different cushion grades and cushion arrangements were
used. However, the same did not result in an improved effect compared
- with the three-layer cushion. Accordingly, additional cushion layers can
be used, however, the three-layer cushion is completely sufficient.
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Figure 4 shows a part plan view and a cross-sectional view through the
heel portion of the shoe. As one can see from the figure, the footbed
has a longitudinal arch-support 14 which merges into a heel inclination
which is indicated at 15. The transition is areally so that punctual
stresses are avoided. The cross-section through the heel portion shows
that the heel inclination 15 extends over about half of the heel portion
in longitudinal direction and ascends from the center of the heel
portion up to the inner edge of the same. Accordingly, the heel
inclination 15 gradually merges into the shell edge of the footbed.
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