Note: Descriptions are shown in the official language in which they were submitted.
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SHOE WITH TWO-PIECE HINGED SOLE AND DETACHABLE HEEL
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to variable
height footwear with flexible soles and, more
particularly, to hinged soles and shoes with detachable
heels.
2. Description of the Related Art
Variable height shoe designs typically allow a
20 single shoe sole and shoe upper combination to be worn
with a variety of detachable heels having different
heights. Variable height shoes are described, far
example, in U.S. Patent No. 4,400,893 to Musci, U.S.
Patent No. 4,494,323 to Latraverse, U.S. Patent No.
4,670,996 to Dill, and U.S. Patent No. 4,805,320 to
Goldenberg. While these patents describe shoe designs
that provide the advantages of heels that can be detached
and replaced with heels of various heights, many such shoe
designs require special tools, such as wrenches or keys,
to remove and replace the heels. Even when special tools
are not required, often a special locking latch must be
released or a complex twisting motion is necessary.
Detachable heel shoes also can be rather complex
structures that are relatively difficult to manufacture.
Many variable height shoe designs can be rather
uncomfortable to wear. Frequently, this is due to 'the
fact that a shoe ordinarily is optimized for a particular
heel height. Both the flexibility of the shoe sole and
upper, and the curvature of the sole, for example, can
vary greatly depending on the height of the heel. A
particular degree of flexibility that is appropriate for
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one heel height might not provide a Comfortable shoe for
another heel height. Similarly, a relatively flat sole
might be most comfortable far a low height, but a
relatively curved sole might be needed for a greater
height.
In particular, a shoe having a heel that is
relatively high will generally have a greater degree of
torsional stiffness and a more curved sole than a low-
heeled shoe. The extra stiffness is necessary because a
high heel places the foot in an extended orientation with
a generally small heel contact area that mak~s the walking
motion inherently unstable. The curved sole enhances the
stiffness of the shoe structure. When a high heel first
strikes the ground during walking, it is not unusual for
the foot to wobble slightly until the front of the shoe is
brought down, firmly planting the wearer's toes on the
ground and stabilizing the foot. The shoe's extra
torsional stiffness reduces and tendency for the shoe to
fall over when the heel strikes the ground, twisting the
wearer's ankle, and makes walking easier. A low~heeled
shoe will generally be more flexible because the foot
flexes more during walking with a low heel than with a
high heel.
Thus, if a flexible, low-heel shoe were fitted
with relatively high heels, there likely would not be
enough torsional rigidity and stiffness in the shoe for
the wearer to maintain balance and counteract the natural
instability of a high heel. Conversely, if a.stiff, high-
heel shoe were fitted with relatively low heels, the shoe
likely would be too stiff to collapse down to the low heed.
position and would not be sufficiently flexible to allow
a natural, comfortable walking motion. This distinction
is not recognized by conventional detachable-heel shoes.
Consequently, detachable-heel shoes have not provided
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sufficient convenience and comfort to become very popular,
despite the advantage of greater wardrobe variety.
Another problem encountered with conventional
detachable-heel shoes is that the shoe upper will visibly
distort while the shoe is at rest <~s heels of different
height are removed and replaced. ~rhe distortion occurs
because the angle between the front sole portion and rear
sole portion changes as heels of different height are
removed and replaced, and the upper front portion of the
shoe bends and distorts as the angle changes. Therefore,
the upper must have sufficient excess material and
flexibility to flex outwardly as the heel height is
increased to accommodate the bending. As a result, the
shoe upper loses its smooth appearance when it is at rest
and acquires a wrinkled appearance. This detracts from
the overall aesthetic appeal of the shoe. A similar
distortion occurs with fixed height shoes during walking,
but is not ordinarily viewed as an aesthetic problem.
U.S. Patent No. 2,599,970 to Baryons, in FIG. 2,
illustrates the distortion that occurs during walking for
a fixed-height shoe.
As noted above, another factor influencing
comfort is the fact that a shoe with a low heel is
ordinarily provided with a relatively flat sole, but a
shoe with a high heel is ordinarily provided with a
relatively curved, arched sole. This is done to enhance
the rigidity of the shoe structure so that heel wobbling
will be minimized. Also, a curved sole is impractical for
a variable height shoe because the curvature can conform
to the arch of a wearer's foot only at one particular
height, and will not conform exactly at any other height.
From the discussion above, it should be apparent
that there is a need for a comfortable and durable shoe,
such as provided by a hinged shoe design, that also offers
CA 02058389 1998-12-17
the added flexibility of detachable heels. The present
invention satisfies this need.
SUMMARY OF THE INVENTION
Thus in one embodiment the present invention provides a
shoe having a hinge sole assembly comprising, a forward sole
section having an upper surface and a lower surface and a most
forward point; and a rear sole section having an upper surface
and a lower surface and a most rearward point; and hinge means
connecting said rear sole section to said forward sole section
in pivotable connection along a straight hinge line; and a
sole perimeter having a most medial point and a most lateral
point; and wherein a reference line passing through the most
forward point of said forward sole section and the most
rearward point of said rear sole section defines a
longitudinal axis, and wherein a medial reference line
parallel to the longitudinal axis which passes through the
most medial point of said sole perimeter defines one point on
the sole perimeter through which the hinge line of said hinge
means passes, and wherein a lateral reference line parallel to
the longitudinal axis which passes through the most lateral
point of said sole perimeter defines the other point on the
sole perimeter through which the hinge line of said hinge
means passes.
In another embodiment, the invention provides a shoe for
receiving and supporting a foot of a wearer, and having a
hinged sole assembly, comprising a forward sole section having
an upper surface and a lower surface; and a rear sole section
having an upper surface and a lower surface; and hinge means
CA 02058389 1998-12-17
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connecting said rear sole section to said forward sole section
in pivotable connection along a straight hinge line; and
wherein said hinge means passes under the lowest point of the
first metatarsal head and the lowest point of the fifth
metatarsal head of the wearer's foot.
In certain embodiments disclosed herein they are shown as
a shoe design with a detachable heel that can simply be pulled
straight off and pushed straight on. Thus, the heels can be
provided in varying heights, the shoe does not lose its
comfortable fit even when the heel height is changed, and no
special tools are required for heel removal and replacement.
The inventor has discovered that a detachable heel is
advantageously provided in conjunction with a flat, rigid rear
sole that provides sufficient fore and aft flexibility for the
wearer's comfort but that also provides the torsional
stiffness necessary for stability with high heels. This
combination of flexibility and rigidity is achieved by
constructing the shoe with a hinged sole having a hinge line
that passes under the first and fifth metatarsal heads of the
foot of the wearer. The inventor has discovered that this is
the only hinge line that will provide for complete comfort to
the wearer yet will be structurally secure enough to prevent
heel wobbling or collapse. The comfort provided by the hinge
allows the sole to be constructed of extremely rigid
materials, such as metal, to which a simple detachable heel
construction can be incorporated. The hinge allows fore and
aft pivoting only along the hinge line and therefore provides
the required torsional stiffness. Thus, changing from a
relatively low heel to a relatively high heel does not degrade
the fit between the wearer's
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foot and the shoe, due to the flat rear sole, and complete
stability is maintained, preventing heel twisting due to
the lateral rigidity of the hinge at any heel height.
BRIEF DESCRIPTION CAF THIE DRAWINGS
FIG. 1 is a side sectional view of a shoe
constructed in accordance with the present invention.
FIG. 2 is a plan view of a shoe constructed in
accordance with the present invention.
FIG. 3 is a representation of the anatomical
structure of a foot in relation to the hinge line provided
by the shoe illustrated in FIGS. 1 and 2.
FIG. 4 is a plan view of the shoe illustrated in
FIGS. 1 and 2 showing the shoe in relation to the hinge
line provided by the shoe illustrated in FIGS. 1 and 2.
FIG. 5 is a side sectional view of the sole and
heel structure of the shoe illustrated in FIG5. 1 and 2.
FIG. 6 is a detailed side sectional view of the
heel structure of the shoe illustrated in FIG. 5.
FIGS. 7A, 7B, and 7C are side views of
alternative hinge constructions for the shoe illustrated
in FIGS. 1-5.
FIGS. gA and 8B are side and plan views,
resgectively, of another alternate embodiment of the hinge
construction for the shoe illustrated in FIGS. 1-5.
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DESCRIPTION OF THE FREFERRED EME~ODIMENTS
Referring to FIGS. 1 and 2, a shoe 10
constructed in accordance with the present invention
includes a front section 12 having a rigid sole 14 and a
flexible front upper 16 that is connected to a rear
section 18 having a flat, rigid sole 20 and a flexible
rear upper 22. The uppers provide a means for attaching
the shoe 10 to the foot of a wearer (not illustrated).
The front and rear sections 12 and 18 are connected by a
hinge coupling 24 such that the two sections can rotate
freely in relation to each other without the forward upper
section 16 coming into contact with the rear upper section
22 throughout the normal range of movement for a wearer's
foot. The shoe 10 includes a heel 26 attached to the
underside of the rear sole section 20. The heel 26 can be
removed from the sole and can be replaced with a heel
having a different height. The hinge 24 allows the front
section 12 and the rear section 18 to pivot relative to
each other to provide sufficient flexibility between the
two sections to provide for a comfortable shoe, while the
rigid sole and hinge cooperate to provide sufficient
torsional stiffness to provide a stable walking platform
even for relatively high heels.
FIG. 2 is a plan view of the shoe 10 for the
right foot of a wearer, with the pivot line of the hinge
24 indicated by the line 30. The outboard end of the
hinge line intersects the shoe perimeter where the
curvature of the perimeter changes from outward curvature
32 to inward curvature 34. This point is approximately
where the front of the fifth metatarsal bone of the foot
of the wearer is positioned. The inboard end of the hinge
line 30 also intersects the shoe perimeter where the
curvature changes from outward curvature 36 to inward
curvature 38. This end of the hinge line is approximately
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where the front of the first metatarsal bone of the foot
of the wearer is positioned.
The position of the hingsa line 3o relative to
the anatomical structure of a wearer.'s foot can be better
understood by referring to FIG. 3, which shows the foot
bones of the wearer superimposed over the pivot line 30 of
the hinge 24. FIG. 3 shows that the h.ing~ line 30 is
aligned with a line that passes from the head of the first
metatarsal bone 40 to the head of the fifth metatarsal
bone 42.
In addition to determining the hinge line 30 by
examining the bone structure of the foot, the hinge line
can also be determined by physically examining a plan
drawing of a right shoe for a particular shoe size. For
example, FIG. 4 shows a plan view outline 46 of the
perimeter of a particular size shae. This outline can be
obtained, for example, by the wearer standing normally
while wearing a shoe or with feet on a flat piece of paper
holding a slight inward pressure on the toes so that each
big toe points slightly inward toward the other toes, as
if wearing enclosed toe shoes. The perimeter of the
wearer's shoe or foot can then be traced to approximately
define the perimeter 46 of the shoe.
Using the traced shoe perimeter 46, two parallel
lines 48 and 50 can be drawn such that each line touches
only one point on the shoe perimeter and the distance
between the parallel lines is maximized. The first line
48 will touch the shoe perimeter at a first point 52,
while the second line 50 will touch the shoe perimeter at
a second point 54. A line 56 drawn through the points 52
and 54 defines what is referred to as the long axis of the
shoe. A line 58 that is drawn parallel to the long axis
such that it touches the inside perimeter 46 of the shoe
at only one point 60 defines the intersection of the hinge
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line 30 with the inside perimeter of the shoe. A second
line 62 drawn parallel to the long axis and touching the
outer perimeter 46 of the shoe at only one point 64
defines the intersection of the hinge line 30 with the
outside shoe perimeter. The points 60 and 64 on the shoe
perimeter are the points in the forward half of the shoe
at which the shoe perimeter curvature changes from outward
curvature away from the long axis to inward curvature
toward the long axis. The line connecting the two points
corresponds to the hinge line 30 and should coincide with
the Line that passes just under the forwardmost points of
the first and fifth metatarsal bones of the wearer as
illustrated in FIG. 3. This hinge line is not
perpendicular to the long axis of the shoe, as is the case
with most conventional hinged' shoes. Rather, the hinge
line provides flexibility where demanded by the anatomy of
'the foot.
FIG. 5 shows the sole sections 14 and 20 of the
shoe 10 without the upper sections 16 and 22, for
simplicity. The forward sole section 14 can be curved as
desired for comfort and style. The rear sole section 20
is flat so that when the heel 26 is replaced with a heel
of a different height, the geometrical relationship
between the rear sole section and the foot of the wearer
is unchanged. That is, the sole retains its initial
orientation relative to the wearer's foot throughout its
range of motion. The heel 26 is preferably attached to
the rear sole section by two studs 66 and 68 that project
downwardly from the bottom surface of the sole 20 and are
received by respective sockets 70 and 72 in the heel 26.
The studs, for example, can be attached to the rear sole
section 20 by riveting. As is most clearly illustrated in
FIG. 2, the studs 66 and 68 are placed on the sole 20
slightly out of alignment with the long axis (FIG. 4} of
the shoe 10. That is, the forwardmost stud 66 is ahead of
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and slightly to the left or right of the second stud 68
relative to the long axis 56 (FIG. 4).
The studs 66 and 68 are shown in greater detail
in FIG. 6 and provide an easy means of attaching the heel
26 to the shoe 10 and simply require a pulling motion on
the bottom of the heel for heel removal. Friction is
maintained between the studs and the heel sockets by a
quick release ball 74 that moves within a laterally
extending shaft 76 in each stud. The balls 74 are pushed
to the outside of the shaft against a rim 78 by an inner
spring 80. When the studs 66 and 68 are pressed into the
heel sockets 70 and 72; the balls 74 are pushed back into
the lateral shafts 76, partially compressing the springs
80. The balls thus push against the walls of the heel
sockets, maintaining friction that prevents the heels from
falling off. Other means of attaching the heel will be
apparent to those skilled in the art.
FIGS. 7A, 7B, and 7C illustrate various means of
implementing the hinge 24 to connect the front sole
section l4 and rear sole section 20. In FIGS. 7A and 7B,
a hinge 82 having a first mounting flange 84 and a second
mounting flange 86 coupled together by hinge barrels 88
and a hinge pin 89 can be attached to the underside of the
front sole section 14 and rear sole section 20. The
mounting flanges can be attached to the soles in a number
of ways, such as by riveting or gluing. If the sole
sections and the mounting flanges are constructed of
metal, then the flanges can be attached by welding. The
hinge barrels 88 can be oriented to either face upwardly
as in FIG. 7A or can be oriented to face downwardly as in
FIG. 7B. Alternatively; a hinge connection can be formed
by bonding two flexible strips 88 and 90 to the upper and
lower surfaces of the front sole 14 and rear sole 20 such
that each strip extends from one sole section to the other
while the sole sections are held abutting each other. The
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two sole sections can then pivot about a fixed axis while
maintaining the required torsional J°igidity.
An alternate means of coupling the front sole
section 14 and rear sole section :>.0 can advantageously
comprise hinge barrels integrally formed in the sole
sections, as illustrated in FIGS. 8A and 8B. The sole
sections 14 and 20 can be constructed from a relatively
rigid material, such as aluminum. In such a case, the
ends of each sole section adjacent to the other sole
section can be provided with a plurality of hinge barrels
92 with a hinge shaft 94 passing therethrough. When the
sole sections are to be assembled, the hinge barrels 92
are interdigitated so that the shaft 94 passing through
each hinge barrel is aligned with the shafts of the
remaining hinge barrels. An elongated hinge pin 96 can
then be inserted through 'the aligned shafts and can then
be left in place and secured, for example, by flattening
the ends of the hinge pin.
In any of the hinges described above, the rigid
sole sections and connecting hinge cooperate to provide a
shoe sole with a great deal of torsional stiffness so that
there is no lateral twisting between the forward sole
section and the year sole section. This allows balancing
forces from the toes to be applied against the forward
sole section to control any instability of the shae that
might occur from wearing a high heel. Thus, the rear sole
section 20 is free to flex toward the forward sole section
14 by rotating in a direction perpendicular to the hinge
line 30 but cannot twist laterally in a direction parallel
to the hinge line.
A shoe constructed in accordance with the
present invention is designed such that the forward sole
section and upper maintain a fixed position with respect
to the front of the wearer's foot and the rear sole
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section and upper maintain a fixed position with respect
to the rear of the wearer's foot. All flexing of the shoe
and foot are confined exclusively to the stated hinge
line. Experimentation has shown that this design does not
inhibit any walking or even dancing motions of the foot
that the wearer may wish to make.
It has been found that the weight-bearing
sections of the bottom of a normal foot flex along the
above-mentioned hinge line and that complete comfort can
be achieved with a shoe that flexes in only this way. Not
only does the described hinge line provide for full, free,
and comfortable movement of the foot, but no number of
other hinge lines will give comparable full and free
movement. A shoe constructed in accordance with the
present invention removes all structural laads on the
cushioning of the shoe so that, when the shoe and foot
flex, padding on the sole does not move with respect to
the foot.
It has been found that the area on a
conventional shoe that distorts and resists motion the
mast is the upper section above the area of the sole that
includes the hinge line of the present invention. Tn a
shoe constructed in accordance with the present invention,
there is no upper part in this shoe area, which is totally
open. Thus, the shoe is very rigid and can be well
padded in the areas where the foot does not flex, but is
completely open on top in the areas where flexing occurs.
This causes the shoe to behave like an extension of the
foot, eliminating twisting and chafing movements of foot
against shoe.
A shoe in accordance with the present invention
can be fitted with heels of different heights and will be
attractive and feel comfortable. Changes in heel height
cause the same flexing of the shoe that walking does.
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Because the upper section of the sYioe is open where the
shoe flexes, there will be no distori~ion of the upper when
the heel height is changed. The sole is hinged to flex
freely without twisting or changing the position of the
foot in relation to the sole and therefore changes in heel
height era readily accommodated. It has been found irhat
such shoes feel as if one is standing or walking on a flat
surface ire contrast to the "perched'° sensation of typical
high heels with their characteristic arched vertical
curvature.
The present invention has been described above
in terms of presently preferred embodiments so that an
understanding of the present invention can be conveyed.
There are, however, many configurations for hinged shoes
with detachable heels that are not specifically described
herein, but with which the present invention is
applicable. The present invention should therefore not be
seen as limited to the particular embodiments described
herein, but rather, it should be understood that the
present invention has applicability with respect to a wide
variety of detachable heel shoes. All modifications,
variations, or equivalent arrangements that are within the
scope of the attached claims should therefore be
considered to be within the scope of the invention.
