Note: Descriptions are shown in the official language in which they were submitted.
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93-454
80LE CONSTRUCTION FOR A ~PORT8 SHOE
BACKGROUND OF THE INVENTION
The present invention relates to the construction of a shoe
sole for a sports shoe, comprising a wear sole and a resilient
layer placed between the upper and the wear sole.
In a prolonged sports performance, such as long-distance
running, attempts have been made to reduce the strain applied to
the feet and legs through the shoes. In this respect, it is
important that the shoe must be constructed in such a manner so as
to prevent extreme lateral movements of the ankle joint. For this
purpose, a number of different analytical methods have been
developed. These methods are directed to ascertaining the person's
personal and even foot-specific tendency of bending-in, i.e.,
pronation, and bending-out, i.e., supination, of the ankle joint,
especially during the initial shoe selection process. After the
type of the foot and the tendencies of bending of the ankle joint
have been established, it is possible to choose shoes that support
the foot in the correct way and specifically for the person
concerned.
The prior art methods intended for the shoe selection process
described above include, for example, recording a sample run that
takes place on a running mat on a video tape. From a slowed-down
video picture, it is possible to measure the angles of bending of
the ankle and, on this basis, to choose the sole construction that
guides the movement of the foot during a running step appropriately
and most accurately from among different shoes.
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U.s. Patent No. 4,917,105 (the specification of which is
incorporated by reference herein) describes a second method, i.e.,
the so-called knee-bend method. In this method, the construction
of the foot arch is examined on a mirror table, and the direction
and extent of the lateral movement of an ankle joint that is loaded
in a knee-bend position are measured. On the basis of these
measurements, the conclusions can be reached concerning the conduct
of the ankle in a running situation, and a combination of a shoe
and an orthopaedic insole that supports the foot in a suitable way
can be selected.
A third method is described in Finnish Patent Application No.
911830. This reference describes a method and device for measuring
how the load applied by a foot to the base is distributed. Other
methods and devices that should be mentioned in this connection
include those described in U.S. Patents Nos. 4,062,355, 3,358,373
and 2,175,116. These prior art references describe various methods
and devices for determining the posture and loading of a foot and,
on this basis, selecting a shoe and/or an insole of the correct
type.
The object of all of the methods mentioned above in the prior
art references is to establish the manner in which a foot loads the
shoe in a running situation and the manner in which the shoe should
support this load to prevent extreme lateral movements of the ankle
joint, which are detrimental in view of the strain applied to the
feet and legs. It is a common solution used in these prior art
methods and devices that the foot is inclined in relation to the
shoe by means of a particular orthopaedic insole. A large number
of solutions of orthopaedic insoles are known in the prior art from
different connections and references, and one of these solutions is
described, e.g., in Finnish Patent Application No. 912588,
corresponding to U.S. Patent Application Serial No. 07/890,911, the
specification of which is incorporated by reference herein.
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Shock absorption is also required in a sports shoe, which is
accomplished mainly by means of the compression of a resilient
material layer placed underneath the heel. A shoe constructed in
this manner is not capable of resisting the twisting produced by
the lateral movement of the ankle in all cases. Therefore, it has
proved necessary to develop shoe constructions in which the
vertical resilience of the sole is different in different areas in
the sole. Such a shoe guides the movement of the ankle dynamically
and thereby compensates for excessive pronation or supination
during a running step. In the prior art, a number of shoes of this
type are known, concerning which the following should be briefly
stated.
One of the earliest sole constructions of a running shoe which
attempted to guide the path of movement of the foot is described in
Finnish Patent No. 57,529 corresponding to U.S. Patent No.
4,102,061. This publication describes a shoe having a so-called
air-cushion construction in which a closed cavity space is formed
in the resilient part of the sole construction in an area of the
heel portion and possibly also in an area of the foot arch portion.
The cavity receives and attenuates the dynamic shocks applied to
the foot during a running step, while the sole construction of the
shoe, nevertheless, supports the foot at the same time in the
lateral direction.
A shoe sole construction of a second type is described in
Finnish Patent No. 71,866 corresponding to U.S. Patent No.
4,757,620, the specification of which is incorporated by reference
herein. In this reference, the sole construction of the shoe
comprises a spring and support construction which includes a
resilient tip part extending from the tip portion of the shoe
substantially to the area of the ball portion of the foot, a
resilient heel part and a more rigid body piece. The resilient
heel part becomes narrower in wedge shape from the rear edge of the
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shoe towards the tip and extends across the area of the heel
portion. The rigid body piece extends from the rear edge of the
shoe to the area of the ball portion and is placed against the heel
and against the arch of the foot. This type of sole construction
receives the shock impact applied to the heel at the stage of
lowering of the foot onto the ground quite efficiently and
adequately supports the arch of the foot at the so-called rolling
stage of the foot. By means of suitable shaping of the resilient
parts and the body piece, the sole construction can be made
suitable for feet of different types.
Further, in EP Patent No. 0,160,415, a sole construction for
a sports shoe is described in which the desired resilience and
support have been achieved by fitting parts of different shapes
and/or hardnesses in the area of the heel portion into the sole
construction. A large number of solutions of this type are known
in the prior art from different shoe manufacturers.
In all of the prior art shoes described above, the operation
of the sole construction is based on the use of different hardness
or different modulus of compression in different parts of the sole.
However, this causes a problem in the manufacturing process of the
shoe because controlling the different hardnesses of materials in
the manufacturing process and connecting these materials having
different hardnesses to each other are often quite difficult.
OBJECTS AND SUNMARY OF THE INVENTION
An object of the present invention is to provide a new and
improved shoe sole construction by whose means the drawbacks of the
prior art are substantially eliminated.
Another object of the present invention is to provide a new
and improved sole construction in particular for a sports shoe that
is well-suited for feet of different types.
It is another object of the present invention to provide a new
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and improved method for providing a sports shoe with a sole
construction having a desired support effect.
In view of achieving the objects stated above and others, the
present invention includes a resilient layer which is made entirely
of a substantially homogeneous material having a substantially
constant hardness. Perforations are formed in the resilient layer
in the areas of the heel portion and the foot arch portion. The
perforations extend through the resilient layer from the upper of
the shoe to the wear sole so as to prod~lce the desired properties
of resilience and attenuation and the desired effect of support in
the sole construction.
By means of the present invention, when compared to the prior
art devices, several advantages are obtained. In the resilient
layer in the sole construction of the shoe in accordance with the
present invention, only one material of the same constant hardness
throughout the whole layer is used. As a result, the drawbacks
related to the shoe sole manufacturing process have been
substantially eliminated. The desired dynamic properties of
resilience of the shoe and the desired support effect of the sole
have been achieved by forming perforations in the material of
constant hardness in the resilient layer. The shoe can then be
made suitable for feet of different types by appropriately varying
the location and shape of the perforations.
More generally stated, the present invention includes means to
provide a support effect for a foot placed in the shoe. The means
function to reduce the modulus of compression in specific
predetermined areas of the resilient layer and specifically, to
provide a smaller modulus of compression in an area of the hee~
portion of the foot and the arch portion of the foot and a larger
modulus of compression in an area of the ball portion and toes
portion of the foot. In a preferred embodiment, the means
constitute perforations formed in the resilient layer.
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The present invention also relates to a method for providing
a sports shoe with a desired support effect, comlprising the steps
of arranging a resilient layer between an upper of the shoe and a
lower wear sole and forming a plurality of perforations in the
resilient layer. The perforations extend through the resilient
layer from the upper to the wear sole and are arranged such that
the perforated area of the resilient layer is at a maximum in an
area of a rear part of the heel portion and decreases toward an
area of the foot arch portion. In this manner, the desired support
effect of the sole construction is accomplished. The arrangement
of perforations can be used to regulate the modulus of compression
of the resilient layer, and the different portions therein.
Other advantages and characteristic features of the invention
will come out later in the following detailed description of the
invention.
BRIEF DESCRIPTION OF T~E DRAWINGS
The following drawings are illustrative of embodiments of the
invention and are not meant to limit the scope of the invention as
encompassed by the claims.
Figure 1 is a general illustration of a shoe that includes a
sole construction in accordance with the present invention.
Figure 2 is a schematic top view of the resilient layer in a
sole construction in accordance with the present invention.
Figure 3 shows a bottom view of a resilient layer in a sole
construction of the embodiment as shown in Fig. 1.
Figure 4 is a schematic top view of the resilient layer in a
sole construction of a shoe for a deficiently pronating foot.
Figure 5 is a schematic top view of the resilient layer in a
sole construction of a shoe for an excessively pronating foot.
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DETAIL~D DESCRIPTION OF TNE INVENTION
Fig. 1 is a schematic illustration of a shoe in accordance
with the present invention which is denoted generally with
reference numeral 10. In a conventional manner, the shoe 10
comprises an upper 11 and a sole construction 12. The upper 11 and
the sole construction 12 are attached to each other in a suitable
and conventional way, for example by gluing. The sole construction
12 includes a resilient layer 13 and an outer sole 14, also
referred to as a lower wear sole, which constitutes the wear layer.
The outer sole 14 and the resilient layer 13 are joined together
preferably by gluing. The resilient layer 13 is illustrated in
more detail in Figs. 3 to 5.
Figs. 2 and 3 show the resilient layer 13 in a shoe sole
construction in accordance with the present invention which is
intended mainly for a so-called "neutral" foot, i.e., a foot which
does not have any substantial defects of posture. As stated above,
Fig. 2 shows the resilient layer 13 as viewed from above, i.e., a
top view, whereas Fig. 3 shows a corresponding resilient layer 13
as viewed from underneath, i.e., from the direction of the outer
sole 14 or a bottom view.
The resilient layer 13 is made of one and the same material
having a substantially constant hardness throughout. This material
is, in a normal manner, thicker in areas of the heel portion and
the arch portion of the foot (as shown in Fig. 1) and becomes
thinner in a suitable way towards an area of the ball portion and
the toes portion. As shown in Figs. 2 and 3, in the areas of the
heel portion and the arch portion of the foot, the resilient layer
13 is provided with perforations 16 passing through the resilient
layer 13 from the upper face 15 to the bottom face thereof. The
perforations 16 reduce the cross-sectional area of the resilient
layer 13 and thereby reduce, in the area of the perforations 16,
the modulus of compression of the resilient layer 13. The modulus
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of compression is proportional to the cross-sectional area of the
resilient layer. Thus, the perforations 16 are formed in the area
in the resilient layer 13 in which the elasticity of the sole is to
be increased.
As shown in Figs. 2-5, the sole construction contains a
plurality of individual perforations which are not connected to one
another. Instead, the perforations 16 are formed in the heel
portion, e.g., by removing individual and discrete portions of the
resilient layer, in the desired pattern to support the foot in
accordance with its pronation, supination or neutral stance. In
one embodiment, the perforations are circular and have a uniform
diameter.
The effect of the perforations on the modulus of compression
of the shoe can be calculated from the formula:
M2
f = ------, wherein
Ml
M1 = modulus of compression in a certain area before
perforations are formed therein,
M2 = modulus of compression in the same area after
perforations have been formed therein.
The modulus of compression of a homogeneous material of a
known hardness is directly proportional to the compression area and
can be ascertained from the following formulas:
Ml = a A1 ; M2 = a A2, wherein
a = material constant;
A, = area of the face to be examined;
A2 = the area from which the area of holes has been
reduced in the same area.
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In such a case, and assuming circular holes each having the
same diameter, the following equation is obtained:
7r . d2
A2 = Al - n -------- , wherein
n = number of holes in the area examined;
d = diameter of the holes.
By substituting the above equations into the formula, the
effect of the perforations on the modulus of compression is:
7r . d2
f = 1 - n
4 Al
The modulus of compression is affected by the number of holes (n)
and the diameter of the holes (d). The regulation of the amount of
holes and the size thereof provides a regulation of the modulus of
compression of the sole. Although in the example provided, the
holes have the same diameter, it is clearly obvious that the form,
size and position of the holes can vary within the entire resilient
layer.
If the modulus of compression is examined, e.g., in the area
~T. D2
A~ ------ as shown in Fig. 2), in which the number of holes is
7, the effect of
the perforations becomes:
d2
f 1 7 ________
D2
In view of the foregoing analysis, by means of the
perforations 16 it is possible to change the dynamic properties of
resilience of the resilient layer 13 of constant hardness in the
sole construction 12. For this reason, the perforated area is at
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the largest in the rear part of the heel portion of the sole. The
largest amount of perforations are formed at the rear part of the
heel portion because the highest elasticity and a maximum
capability of attenuation of shock are needed in this area in the
sole. During a running step, when the foot moves from the
"landing" stage, i.e., from the collision stage in which a high
capacity of elasticity and attenuation is required from the shoe,
to the so-called rolling stage, the downward movement of the center
of gravity of the runner stops and the foot prepares for a take-off
upwards and forwards for the next step. At this time, a high
pressure is applied to the area of the arch portion of the foot
and, by its effect, the sole construction of the shoe must not be
flattened excessively in order to prevent the runner's energy from
being lost due to deformations of the sole construction. Thus, the
support effect of the sole must be increased in a transition from
the area of the heel portion to the area of the arch portion of the
foot.
In a preferred embodiment of the invention, as shown in Figs.
2 and 3, the increase in the support effect is achieved by forming
the perforations such that the proportion of the perforations 16 in
the area of the resilient layer 13 is reduced (and the non-
perforated area is increased accordingly) in a direction from the
area of the heel portion toward the arch portion of the foot. This
provides a variably perforated resilient layer. In order that the
support effect of the sole on the foot should be increased in the
correct way, the perforations 16 have been formed preferably, as
shown in Figs. 2 and 3, as a "drop-shaped" area, which narrows
toward an area of the toes portion of the foot.
In a so-called "neutral case" shown in Figs. 2 and 3, the
perforated area is arranged so that a non-perforated area 17,18 at
both sides of the sole becomes larger to thereby increase the
support effect of the sole at both sides. In this manner, there is
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a decrease in the amount of perforations from the center region of
the sole to the edge or side portions and also from the heel
portion of the shoe to the toes portion.
The resilient layer 13a in the sole construction of a shoe as
shown in Fig. 4 is meant for a deficiently pronating foot, which
means that the support effect of the shoe must be higher at an
outside edge of the foot than at an inside edge. For this reason,
perforations 16a have been formed in the resilient layer 13a so
that the perforations 16a proceed from the heel along the inside
edge of the shoe while allowing a larger non-perforated area 17a to
remain at the outside edge of the shoe.
In a corresponding manner, the resilient layer 13b in the sole
construction of a shoe as shown in Fig. 5 is intended for an
excessively pronating foot, in which case the support effect of the
shoe must be higher at the inside edge of the foot than at the
outside edge. Thus, in this embodiment, perforations 16b are
formed to proceed from the heel portion along the outer edge of the
shoe to an area of the arch portion while a larger non-perforated
area 18b remains at the inner edge of the shoe.
In the embodiments of the present invention shown in Figs. 2
to 5, the complete shape of the perforated area 16,16a,16b can be
the same (e.g., for the same size and width shoe) while only the
position of the perforations that depends on the particular case
and posture of the wearer. In this manner, it is possible to lower
the cost of tools, because, in all cases, it would be possible to
prepare the perforations by means of the same tool, which is just
placed in different positions.
Figs. 2 to 5 also illustrate grooves arranged in the resilient
layer placed both in its upper face and in its lower face and
primarily in the area of the ball portion of the foot. The grooves
improve the resilience of bending of the sole construction.
The examples provided above are not meant to be exclusive.
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Many other variations of the present invention would be obvious to
those skilled in the art, and are contemplated to be within the
scope of the appended claims.
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