Note: Descriptions are shown in the official language in which they were submitted.
2121919
PATENT
SHOE SHOCK ABSORPTION SYSTEM
BACKGROUND OF THE INVENTION
Shoes such as walking, running, tennis, basketball,
aerobic and soccer shoes must distribute the force of shoe-
support surface impact and fit tightly on the user's foot.
The force distribution and tightness of the fit needs to be
greatest when the largest forces are being applied between the
shoe and the support surface. It has been typical to rely on
the sole to distribute the force and to tighten the shoe as
much as possible, and physically bearable, to prevent or at
15 least min;m; ze relative movement of the foot in the shoe at
times when maximum forces are transmitted between the support
surface and the shoe. As a practical matter, the shock
absorption is usually inadequate and such a fit is excessively
tight during most times and quite frequently is uncomfortable,
can lead to numbness and, in extreme cases, can even result in
injuries. Thus, a compromise is frequently reached in the
design and composition of the sole and by tightening the shoe
on the foot more than is necessary for the small forces that
are applied and less than is desired to prevent relative
25 movement of the foot in the shoe when large forces are
applied. Consequently, the shock absorption characteristics
and the fit of such shoes is almost always other than what it
should be.
Up to now, little or no consideration has been given
to the shock absorption characteristics and the relative
tightness of street and sport shoes, particularly lightweight,
highly mobile shoes such as walking, running, tennis, track
and field and contact sport shoes. The lightness of such
shoes and the lack of an adequate analysis of the interaction
between the shoe, the user's foot and the support surface has
led to the practice of relying on the elastomer sole to
distribute the impact force and simply tightening the shoe to
suit the user's taste, feel or preference. In some instances,
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the shoe might be too loose and not infrequently, slipped
significantly relative to the foot such as during heel strike
when running or in a particularly strenuous maneuver such as a
sudden change in direction when turning. In addition, the
impact force to the foot has not been adequately distributed.
Upon closer analysis, however, it becomes apparent
that there are distinct phases in the use of a shoe,
particularly a sport shoe, when forces applied by the foot to
the shoe momentarily greatly exceed the normally encountered
forces. During heel strike, for example, there are forces
generated by both the player's weight which tend to
concentrate the impact force in the area of the heel and there
is the deceleration of the shoe which tends to move the foot
in a forward direction relative to the shoe. Such movements
may be relatively small, say in the order of no more than a
few millimeters but they are present and typically, they are
repeated thousands of times during play. This force distribu-
tion and foot slippage can lead to discomfort, skin irritation
from rubbing between the foot and the shoe, injury and energy
losses, which though small, are highly undesirable, particu-
larly in competitive sports.
SUMMARY OF THE INVENTION
The present invention greatly reduces or eliminates
relative movement between the foot and the shoe while improv-
ing the shock absorption characteristics by temporarily
increasing the tightness of the fit of the shoe on the foot as
a function of increased weight on the shoe sole during foot
strike and prolonging the tightening for a period of time
after the user of the shoe reduces the increased weight from
the sole. At the same time, the tightness of the fit can be
reduced when the foot is in its unweighted condition when
m;n;ml~m forces are exerted to prevent discomfort or possible
injury from an overtightening of the shoe for excessive
lengths of time. In particular, the present invention
increases the tightness of the fit when the foot weights the
sole or a dynamically movable footbed upon foot strike moving
the foot toward the bottom of the sole resulting in a tighten-
2121~19
3ing of the shoe. The invention also provides means for
prolonging this tightened condition and dispersing the energy
of foot strike impact by the movement of the shoe sole or the
footbed increasing distribution of impact force to the upper
foot.
Broadly speaking, therefore, the present invention
provides a shoe, which may be a street shoe or a sport shoe,
including an upper shell and a lower sole secured to the upper
shell, forming a comfortable close or snug fit on the foot
when the foot is in a generally unweighted condition. The
shoe also includes means for sensing when the user of the shoe
applies increased weight to the sole upon touching a support
surface for the shoe. There is tightening means responsive to
the sen~ing means for increasing the tightness of the fit of
the shoe on the foot of the user as the user applies increased
weight to the sole. There is additional means coupled to the
tightening means for maint~;n;ng the tightening of the
tightening means for a period of time after the user of the
shoe reduces his or her weight from the sole. The tightness
of the fit is increased and thus the distribution of the
impact force, when the foot is placed in a weighted condition
and this tightness is maintained for a predetermined period of
time. This is accomplished with means for sensing a relative
weighting or compression of the sole or the-downward movement
of a dynamically movable footbed and means operatively coupled
with the sensing means and the shoe for increasing and
maint~;n;ng the tightness of the fit of the shoe for a
predetermined period of time on the foot in response to a
relative loading of the lower extremity which moves the foot
toward the bottom of the sole of the shoe.
One embodiment of the invention provides a strap
assembly located on each side of the foot in the shoe. One
end of each strap is attached to the inside of the shoe shell
upper in the area of the foot instep. Each strap then passes
in a downward and rearward direction and is attached in the
area of the rear of the heel of the foot to the side of a
semirigid dynamically movable footbed. The footbed extends
from the toe end of the shoe to the heel end and is separated
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from the shoe sole in the heel area by a variable size
elastomer pad having specified loading and elastic rebound
characteristics, a low compression set and a very slow
recovery from compression such as a flexible polyurethane
material. Downward movement of the footbed in the heel region
toward the bottom of the sole during weighting pulls the
straps in a downward and rearward direction tightening the
straps over the foot instep, as a function of the extent to
which the foot heel and midfoot have moved toward the bottom
of the sole. The period of time that the shoe maintains the
tightened condition depends upon the recovery period of the
elastomer pad located between and secured to the dynamically
movable footbed and the upper surface of the sole of the shoe.
In use, the shoe upper is closed and tightened to a
lS comfortable close snug fit by a conventional lacing arrange-
ment. During foot strike, the dynamically movable footbed
moves in a downward direction pulling the straps in a downward
and rearward direction. The distance that the footbed moves
in the heel area is greater than the distance the footbed
moves in the midfoot area. Thus, there is tightening of the
straps and shoe over the instep. Since the elastomer pad
recovers at a slower rate than the rate of unweighting of the
foot heel, the shoe r~m~; nC tight on the foot for an extended
period of time. Thus, the means for maintaining the tighten-
ing of the tightening means includes a variable size slowrecovery elastomer pad. In a shoe, therefore, the tightness of the fit is
temporarily increased during foot strike when the foot is
weighted and moves toward the bottom of the sole and the
tightness is maint~;neA for a predetermined period of time.
Consequently, during those momPnts when large forces are
transmitted from the foot to the ground via the shoe, the shoe
fits the tightest, and distributes the impact force to the
instep of the foot thereby reducing movements of the foot in
the shoe.
To summarize, the present invention provides a
dynamic fitting system for shoes which allows a reduced
tightness snug unweighted condition for the foot when the
2121919
_ 5
tightness of the fit is at a ml niml~m and which increases and
maintains the tightness for a predetermined period of time and
distributes the shock force in response to movement of the
foot toward the bottom of the sole. This greatly enhances the
utility of a shoe in that it is tightest on the foot when the
foot is moved in a downward direction toward the bottom of the
sole which typically is the condition during which maximum
forces are transmitted between the foot and the shoe. Due to
the prolonged tightness of the fit, relative movements between
the foot and the shoe are m; nl ml zed. Yet, the discomfort and
possibility of injury which would accompany the use of a shoe
tightened to take into account maximum forces, which are
encountered for only fractions of a second, are eliminated,
because when the foot is in its relative unweighted condition,
or in a condition which deviates therefrom by only a minor
amount, the fit of the shoe can be such as to cause no
discomfort whatsoever.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevational view of a shoe provided
with a shock absorption system in an unweighted condition con-
structed in accordance with the present invention.
Fig. 2 is a vertical section through the shoe of
Fig. 1, ta~en along lines A-A of Fig. 1.
~ig. 3 is a partial vertical section through the
shoe of Fig. 1 taken along lines A-A of Fig. 1 constructed in
accordance with an alternative arrangement of the tightening
mechanism strap.
Fig. 4 is a partial top view of the shoe of Fig. 1.
Fig. 5 is a vertical section through the shoe of
Fig. 1, taken along lines A-A of Fig. 1 with the shock
absorption system in a weighted condition.
Fig. 6 is a side elevational view of a shoe
including a shock absorption system in an unweighted condition
constructed in accordance with another e-m-bodiment of the
present invention.
Fig. 7 is a side elevation view of the shoe of Fig.
6 in a weighted condition.
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.
Fig. 8 is an enlarged vertical section through the
shoe of Fig. 6, taken along lines B-B of Fig. 6.
Fig. 9 is an enlarged vertical section through the
recovery delaying friction mechanism of the shoe of Fig. 6.
Fig. 10 is a side elevational view of a shoe
including a shock absorption system constructed in accordance
with still another embodiment of the present invention.
Fig. 11 i9 a vertical section through the shoe of
Fig. 10, taken along lines C-C of Fig. 10.
Fig. 12 is an enlarged vertical section through the
recovery delaying valve mechanism of the shoe of Fig. 10.
Fig. 13 is an enlarged plan view of the recovery
delaying valve mechanism of the shoe of Fig. 10.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figs. 1-5, a shoe 1 has a lower sole 2
and an upper shell 3 secured to the lower sole and defining
the inside of the shoe within which the user places his or her
foot. The upper shell of the shoe includes a conventional,
typically V-shaped cut out 4 above the forefoot and midfoot
5 and extending generally from about the instep 6 towards the
front or toe end 7 of the shoe. A tongue 8 underlies the
cutout and is secured to the upper in the area of the toe end
of the shoe. The V-shaped cut out may be closed by a lace
9 passing through eyelets 10 arranged in the conventional
manner. The upper is further defined by a cuff 11 which is
usually located below the user~s ankle joint. The upper shell
3 includes a heel end 12 which surrounds and engages the
user's heel and which includes a semirigid heel counter 13.
Located within the shoe is a dynamically movable
footbed 16, which provides a means for sensing when the user
of the shoe applies increased weight to the lower sole 2 upon
touching a support surface for the shoe 1. The footbed
16 extends forwardly from the heel end of the shoe to the toe
area of the user's foot. The semirigid footbed 16 is separat-
ed from the shoe sole in the heel area by a variable size, low
compression set, very slow recovery segmented elastomer pad 17
with specified loading and elastic rebound characteristics
2121919
_ 7
which is secured to the footbed and sole. A less rigid
footbed may be used if the pad extends to the midfoot. One
end of a tightening mechanism strap 20 located on each side of
the shoe is attached to the inside of the shoe shell vamp, in
the area of the foot instep by a rivet 21 or the like. Each
strap 20 which may be padded and located between a liner and
the shoe shell passes in a downward and rearward direction and
is attached to the side of the footbed in the area of the heel
by a staple 22 or the like.
An alternative arrangement of the tightening
mechanism strap 20 directs the strap 20 through a slot 23 in
footbed 16. The strap 20, as shown in Fig. 3, is attached to
the inside of the upper shell 3 in the area of the heel by a
rivet 24 or the like.
In use, the shoe is closed and tightened to a close
snug fit by the lace arrangement. During foot strike, the
qensing means footbed 16 moves in a downward direction moving
the foot heel toward the bottom of the lower sole 2. The
tightening means strap 20 and thus the shoe 1 is temporarily
tightened over the instep distributing the force to the instep
and reducing movements of the foot in the shoe. This tight-
ness is maintained for a predetermined period of time after
the user of the show reduces his or her increased weight to
the qole due to the very slow recovery to the unweighted
condition of the segmented elastomer pad 17 secured to the
footbed and sole following unweighting of the sole. The
amount of force and length of time that the force is transmit-
ted from the lower sole 2 to the upper shell 3 and foot may be
varied by varying the size or construction of the segmented
elaqtomer pad 17. Directing the strap 20 through the nlot 23
in the footbed and attaching the strap to the inside of the
upper shell 3 provides a mechanical advantage, further
increasing the tightness of the strap 20 and shoe on the foot
as the footbed 16 is lowered toward the bottom of the lower
sole 2.
Referring to Figs. 6-9 in another embodiment of the
present invention, a shoe 30 has a lower sole 31 constructed
of a resilient material such as a compressible elastomer and
2 121919
an upper shell 32 constructed of flexible material such as
leather or nylon secured to the sole. The upper shell
includes a V-shaped cut out 33 above the forefoot and midfoot
in the vamp 34. A tongue 35 underlies the cut out and is
secured in the vicinity of the toe end of the shoe. The V-
shaped cut out can be closed by the lace 36 passing through
eyelets 37 arranged in the conventional manner or by Velcro~
straps known per se. The upper is further defined by a cuff
38 which is usually located below the user's ankle joint but
may be higher in basketball shoes or the like. The upper
shell 32 terminates in a heel end 39 which surrounds and
engages the user's heel and which includes a semirigid heel
counter 40. A strap 41, located on the outside of each side
of the shoe 30, is attached at the upper end respectively to
the upper shell vamp 34 and at the lower end to a bar 42 by a
rivet 48 or the like. The lower sole 31 can be constructed of
resilient material such as a compressible elastomer in one
layer or two layers or more, with one layer 51 requiring a
substantially smaller proportion of the user's weight to
compres9 than the second layer 52. The bar 42 is located on
each side of the outside of the shoe 30 and extends from the
lower end of the strap 41 to a location near the bottom of the
lower sole 31 and can include a member 43 located in the
bottom layer 52 of the compressible elastomer or the like
lower sole 31. This construction allows the sensing means bar
42 to partially tighten the tightening means strap 41 to
increase the tightness of the fit of the shoe and m;n;m;ze
slippage of the foot in the shoe before the much larger
proportion of the user's increased weight further tightens the
fit and distributes the increased force to the heel, midfoot
and forefoot. The bar is pivoted from each side of the shoe
30 by an adjustable pivot bolt 44 secured on each side of the
shoe in the semirigid heel counter 40 or side of the shoe.
The bar 42 includes a bar upper segment 45 and a bar lower
segment 46. The upper end of each strap 41 is secured above a
pleated section 47 in the vamp 34 of the upper shell 32 by
rivet 48 or the like. The adjustable pivot bolt 44 includes a
head 49. Coupled between the bolt head 49 and the bar 42 is a
2~21919
g
partially compressed coil spring 50. A coned disk spring may
be used.
In use, the shoe is closed and tightened to a close
snug fit by the lace arrangement. During foot strike, the
lower sole 31 is compressed pivoting the sensing means bar
lower segment 46 in an upward direction and the tightening
means bar upper segment 45 in a downward direction. This
movement pulls the strap 41 and the pleated section 47 of the
upper shell 32 in a downward and rearward direction tightening
the vamp and shell on the foot, distributing the force to the
midfoot and forefoot and reducing movements of the foot in the
shoe. This tightness is maintained for a predetermined period
of time due to the very slow recovery to the unweighted
position of the bar 42 as a result of the friction between the
coil spring 50 and the bar 42 and between bar 42 and heel
counter 40 following unweighting of the sole. The amount of
force and length of time that the force is transmitted from
the lower sole 31 to the upper shell 32 and foot may be varied
by varying the amount of compression and force of the compres-
sion spring 50, relative to the force of the resilient
compressible sole to return to the unweighted condition, by
means of the adjustable pivot bolt 44.
Referring to Figs. 10-13 in still another
embodiment, a shoe 60 has a resilient elastomer or the like
compressible lower sole 61 and an upper shell 62. The upper
shell 62 of the shoe 60 includes a conventional closure
arrangement. A lower bladder 63 is located within the
compressible lower sole 61 and has flap valves 64 that open in
an upward direction. Fluid passages 65 cnmml~nlcating with
smaller upper bladders 66 are located above the lower sole 61
within the shoe upper shell 62 in the area of the instep of
the foot. The fluid distensible bladders contain gas such as
FreonR or an oil or other flow material. The flap valves 64
located between lower bladder 63 and upper bladders 66 include
passages 67 which are smaller than passages 65 to slow the
rate of return of the fluid from the upper bladders 66 to the
lower bladder 63. This prolongs the tightness of the shoe on
the foot for a period of time after the user of the shoe
2121gl9
' -
reduces the increased weight from the sole and the
compressible resilient sole returns to the unweighted
condition. Footbed 68 which has a variable width from top to
bottom is located within the shoe and indents the upper
bladders forming an adjustable valve to vary and prolong the
amount of force transmitted from the lower bladder 63 and
upper bladders 66.
In use, the foot is placed inside of the shoe and
the shoe is closed and tightened to a close comfortable fit in
the conventional manner. During the weighting of foot strike,
the elastomer sole 61 is compressed by the impact force. This
movement compresses the sensing means lower bladder 63 forcing
fluid into the tightening means upper bladder 66 through the
passages 65 as flap valves 64 are forced open increasing the
tightness of the fit of the shoe on the foot distributing the
force to the foot. This tightness is maintained for a
predetermined period of time due to the very slow recovery to
the unweighted condition of the lower bladder 63 and lower
sole 61. This iq as a result of the slow flow of fluid
through the recovery delaying valve mechanism passages 67
closed flap valves 64 to the lower bladder 63 following a
period of time after the user of the shoe reduces the in-
creased weight from the sole. The amount of force and length
of time that the force is transmitted from the lower sole 61
to the upper shell 62 and foot may be varied by varying the
orientation of the footbed 68.
