Note: Descriptions are shown in the official language in which they were submitted.
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ATHLETJC BOOT FOR ABSORBING SHOCK
DESCRIPTION
TECHNICAL FIELD:
The invention relates to an athletic boot and is especially applicable to an
athletic
boot for use during skiing or snowboarding.
BACKGROUND ART:
Skiers and snowboarders canbe subjected to considerable impact forces on their
feet,
ankles and legs when travelling down a slope. Such impact forces can occur
when the skier
or snowboarder rides over uneven terrain, jumps or moguls, or performs
airborne
manoeuvres. In extreme cases, the impacts can be forceful enough to sustain
serious injury.
In less extreme cases, such as travelling over minor variations in the snow
cover, the impact
forces can cause vibrations which result in a rough ride on the ski or
snowboard.
It is known to provide shock absorbing means external to a ski boot to absorb
vertical
impact forces. For instance, inflatable airbags have been attached to a ski
below the ski boot
to absorb shock and vibration. U.S. patents Nos. 2,330,731 and 2,350,130
disclose foot rests
for skis which have inflatable rubber air bags which have their marginal edges
attached to
the ski by nails. It is also known to attach a spring board on a ski beneath
the ski boot as
disclosed in U.S. patent No.4,139,214. According to US 4,979,761, in which the
foregoing
patents were discussed, these existing ski suspensions have not been capable
of effectively
absorbing such impact forces while also providing effective ski control. In
particular, it is
difficult for the skier to control forces applied to the edges of the ski when
turning.
These limitations have been addressed by U.S. patent No. 4,979,761, which
discloses
an external suspension system having a pair of spaced suspension plates
positioned between
the ski boot and the ski. Springs and foam material are interposed between the
plates for
dampening shock and lateral stabilization is achieved by hinged links which
prevent twisting
of the plates relative to each other in a lateral direction and allow the
skier to transfer forces
through the ski boot to the ski edges. The arrangement is not entirely
satisfactory, however,
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in that it is complicated, with many interconnected and/or moving parts, and
is
inconveniently mounted on the ski using nuts and bolts.
U.S. patent No. 5,243,773 discloses a more simple design in which a rubber
dampening layer is provided between the sole of the boot and an external sole
plate. This
arrangement might provide better stability and control because the dampening
plate is
relatively thin, so the foot is closer to the lateral edges ofthe ski.
However, the limited range
of movement of the foot, upon impact, is insufficient to provide adequate
shock absorption.
Other known ski boot designs provide the shock absorbing devices within the
boot,
for example by means of an inner boot or liner that moves verticallywith
respect to the outer
shell of the boot. U,S, patent No. 4,845,338 (Lakic) and U.S. patent No.
5,692,321
(Holstine) each disclose such a ski boot which comprises an air-filled bag
positioned
between the sole of the outer shell of the boot and the sole of the inner
boot. A second air
bag is positioned above the instep of the inner boot and is in air flow
communication with
the lower air bag. (Although, in Lakic's case, the main function of the air
bags is to warm
the foot, Lakic states that the air circulation system can be used to provide
shock absorption.)
Thus, in each case, when a wearer's weight bears down upon the sole of the
inner boot, the
latter moves downwards with respect to the main boot shell so that air is
forced from the
lower air bag to the air bag positioned above the instep. According to Lakic
and Holstine,
such an arrangement of air bags maintains support around the skier's ankle
when the lower
air bag is compressed.
Although such an arrangement may aid in lessening impact forces during skiing,
it
suffers from the disadvantage that it is complicated and expensive to
manufacture. This is
because, unlike a conventional ski boot, it comprises both the usual outer
shell and an inner
shell. Furthermore, since the inner and outer shells need to be relatively
loose to be movable
relative to one another, the boot would likely not provide adequate support
around the user's
leg, ankle and foot. Although this problem might be solved by tightening the
buckles, this
would limit relative movement of the inner boot and outer shell, which, in
turn, would
prevent the boot from absorbing shocks. Moreover, the dampening effect of the
air bag
would not be entirely satisfactory, since, the transfer of air from the lower
air bag to the
upper air bag would tend to reduce any air cushioning effect.
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DISCLOSURE OF INVENTION:
The present invention seeks to eliminate, or at least mitigate, the
disadvantages of
such known athletic boots, or at least provide an alternative.
According to the present invention, there is provided an athletic boot for
absorbing
vertical impact force exerted by a user comprising a sole plate, a boot body
that is movably
mounted to the sole plate so that at least a heel portion of the boot body can
be displaced
upwardly with respect to the sole plate, a bag containing air disposed between
the sole plate
and the boot body for resiliently biasing the boot body away from the sole
plate, and means
acting between the boot body and the sole plate to provide shock absorption in
the vertical
direction and stabilization in the lateral direction.
In a preferred embodiment of the invention, the means acting between the boot
body
and the side plate comprises a shock absorber attached to the boot body,
preferably to the
ankle portion, and to the sole plate, respectively, to act therebetween.
Separate stabilizing
means inhibit lateral movement of the boot body with respect to said sole
plate. Preferably,
the stabilizing means connects the heel portion of the boot body to the sole
plate and permits
relative upwards movement therebetween while inhibiting relative lateral
movement
therebetween.
The foregoing and other objects, features, aspects and advantages of the
present
invention will become more apparent from the following detailed description,
taken in
conjunction with the accompanying drawings, of a preferred embodiment of the
invention,
which is described by way of example only.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figure 1 is a perspective view of an impact-absorbing ski boot;
Figure 2 is a rear elevational view of the ski boot;
Figure 3 is a side elevational view of the ski boot;
Figure 4 is a bottom plan view of the ski boot taken along the line 4-4 of
Figure 3;
Figure 5 is a side elevational view of a sole plate and the bottom sole of the
ski boot;
Figure 6 is a partial cross-sectional view of the ski boot;
Figure 7 is a vertical cross-sectional view of a pair of stabilizers mounted
one on each
side of the ski boot;
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Figure 8 is a longitudinal cross-sectional view of one of apair of stabilizers
according
to an alternative embodiment;
Figure 9 is a side view of yet another embodiment of the invention;
Figure 10 is a partial cross-sectional view through a heel portion of the ski
boot taken
on the line X-X of Figure 9;
Figure 11 is a plan view of a sole plate of the ski boot of Figure 9; and
Figures 12A and 12B are front and side views, respectively, of a part of a
stabilizer
of the ski boot.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS:
In the drawings, identical or similar elements in the different Figures have
the same
reference numeral, with a prime signifying a modification.
Referring to Figures 1 and 2, a ski boot 10 comprises a boot body 12 having a
toe
portion 14 coupled to a frontal portion of a sole plate 16 by a pivot 18. The
boot body 12
is of the conventional front-entry kind comprising a hard plastic shell 20 and
a cuff portion
22 for enclosing the lower leg of a wearer when in use, but the shell 20 does
not have the
usual formations for attachment to the ski bindings, Instead, the front 24 and
rear 26
portions of the sole plate 16 are shaped to fit within a conventional binding
mounted on a'
ski.
The front portion of the boot body 12 comprises a tongue 28 that opens
outwardly
to receive a user's foot. Fastening buckles 30A, 30B and 3 OC are positioned
over the tongue
to secure the upper portion of the boot body in a snug conforming fit about
the wearer's
ankle and foot. The buckles 30A, 30B and 30C can be adjusted in a conventional
manner
to control the degree of movement of the foot and ankle within the boot body
12.
An airbag 32 is positioned between the sole 34 of the boot body 12 and the
sole plate
16. The heel portion 36 of the boot body 12 is connected to the sole plate 16
by stabilizers
38A and 38B positioned on either side of the rear of the boot body 12. An air
shock
absorber 40 is attached at its one end to the sole plate 16 and, at the other,
to the rear of the
boot body 12 at a position near the top of the ankle portion of the boot.
Referring to Figures 4, 5 and 6, the pivot 18 comprises an upper bracket 42
mounted
on the underside of the boot body with a central hole 44 extending through it.
The upper
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bracket 42 is received between a pair of spaced lower brackets 46A and 46B
which are
integral with the sole plate 16. The lower brackets 46A and 46B have
respective aligned
holes 48A and 48B (not shown) extending through them. A pivot pin 50 (see
Figure 6)
extends through the aligned holes 48A and 48B in the pair of brackets and the
hole 44
5 extending through upper bracket 42, A grease nipple 52 is positioned in the
sole plate 16
adjacent the lower brackets 46A and 463 to allow for the application of grease
to the pivot
joint.
As shown in Figure 4, the air bag 32 extends along the underside of the boot
sole 34
and is secured by a layer of adhesive (not shown), The air bag 32 curves
inwardly at regions
adjacent the stabilizers 38A and 38B and at a region adjacent the base of the
shock absorber
40, to provide clearance. A sealed opening 54 formed in the front region of
the air bag 32
provides clearance around the front pivot 18, which projects through it. The
air bag 32 is
completely sealed around its perimeter and does not communicate with other air
bladders or
cavities. The air bag 32 is made of a material that is flexible, durable and
resistant to
puncturing. A suitable material is radial grade rubber, such as that used in
air bags of
commercial vehicles, which, though not particularly elastic, is sufficiently
flexible that the
sidewalls can flex as the air bag is compressed under loading and then recover
their initial
shape after the load is removed. Typically, the rubber might be about 1/8 inch
thick.
A pressure gauge 56 positioned on the rear of the air bag 32 provides the user
with
a visual indication of the pressure level within the air bag 32. A short tube
58 containing
a valve for inflating the air bag 32, and adjusting the air bag pressure,
extends from the rear
of the air bag 32 (see Figures 2 and 3) and is clipped to the rear of the boot
body by clip 59.
Similarly, the gauge 56 may also be clipped to the boot body. Of course, the
gauge 56 could
be integrated with the valve, conveniently built into a screw-on valve cap.
Figure 2 shows a conventional air shock absorber 40 mounted on the rear of the
boot
body which comprises a cylinder 60 and a piston rod 62 which is received in
the cylinder 60.
A piston head (not shown) is mounted to one end of the piston rod 62 and
slides within the
cylinder 60. The base of the piston rod 62 is mounted on the sole plate 16 by
a ball and
socket joint 64. An adjustable valve 66 positioned on one end of the cylinder
60 allows the
dampening factor of the shock absorber 40 to be varied to suit, for example,
the weight of
the user, the skill level of the user, and so on.
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The air shock absorber 40 is not shown in greater detail since the design is
conventional. An example of a suitable air shock absorber 40, which is used in
a bicycle
suspension system, is disclosed in US patent No. 6,592,108, to which the
reader is directed
for reference.
The pair of stabilizers 3 8A and 3 8B connect the boot body 12 to the sole
plate 16 and
support the heel 36 of the boot body 12 as it is displaced up and down with
respect to the sole
plate 16. Referring also to Figure 7, the stabilizers 38A and 38B comprise a
pair of shafts
68A and 68B mounted on a pair of lower bosses 70A and 70B projecting from
respective
opposite sides of a rear portion of the sole plate 16. The shafts 68A and 68B
extend through
a pair of upper bosses 69A and 69B that project from respective sides of the
rear of the boot
body 12. Tice shafts 68A and 68B are slidably received in a pair of bushings
72A and 72B
extending through the upper bosses 69A and 69B. The bosses 69A and 69B may be
formed
integrally with the boot body 12, conveniently when moulding it. Likewise, the
lower bosses
70A and 70B may be formed integrally with the sole plate 16 during
manufacture.
Both ends of the shafts 68A and 68B are screw-threaded. Their respective lower
ends
are screwed into metal nut inserts 74A and 74B in the lower bosses 70A and
70B,
respectively, and their upper ends are screwed into adjustable caps 76A and
76B,
respectively. Grease nipples 78A and 78B extend through the bosses 69A and 69B
and
bushings 72A and 72B, respectively, to allow for the application of grease
between the shafts
68A and 68B and the bushings 72A and 72B. Rubber stops 80A and 80A' fit around
respective opposite end portions of shaft 68A and rubber stops 80B and BOB"
fit around
respective opposite end portions of shaft 68B. To keep snow and debris out of
the stabilizers,
rubber boots 81A and 81A' fit around the end portions of shaft 68A and rubber
boots 81B
and 81 B' fit around the end portions of shaft 68B.
The design of the stabilizers allows the upper bosses 69A and 69B formed in
the boot
body to slide up and down on their respective shafts 68A and 68B, the rubber
stops BOA,
80A', BOB and 80B' serving to cushion the impact between the bosses 69A and
69B and the
end caps at one extreme and the sole plate 16 at the other extreme, The
adjustable caps 76A
and 76B allow a user to adjust the overall range of travel.
=n
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Figure 6 shows the position of the boot body 12 before an impact force is
exerted on
its sole 34 by a wearer. In this position, the heel portion 36 of the boot
body 12 is pivoted
upwardly about the pivot pin 50 due to the biasing action ofthe air bag 32.
The upper bosses
69A and 69B on the sides of the boot body 12 are displaced on their respective
shafts 68A
and 68B towards the upper ends of the stabilizers 38A and 38B. When an impact
force is
applied, the heel portion 36 of the boot body 12 is pivoted downwardly and the
bosses 69A
and 69B are displaced on their respective shafts 68A and 68B towards the sole
plate 16.
When the heel 36 is displaced upwards, i.e., when the weight of the user is no
longer
bearing upon the boot sole 34, the air shock absorber 40 is in a fully
extended position. As
the user's weight bears down on the sole 34 of the boot body, the air bag 32
acts as a spring
to resist the movement of the heel 36 of the boot body 12 towards the sole
plate 16. The air
shock absorber 40 acts in a conventional manner to limit the speed with which
the boot
moves towards the sole plate 16. The shock absorber 40 will also control
rebound forces,
i.e., inhibit bouncing. Thus, the air shock absorber 40 and air bag 32 act
together as an "air
suspension system".
The pressure in the air bag 32 can be adjusted according to the skier's
performance
level and weight. For example, novice skiers may prefer an air bag 32 with
less of a biasing
effect by releasing air through valve 58. Moreover, as previously mentioned,
the adjustable
caps 76A and 76B of the stabilizers can be adjusted to vary the degree in
which the upper
bosses 69A and 69B can slide upwards on the stabilizers 38A and 38B.
The pressure gauge 56 may be calibrated to show actual air pressure, or a
series of
indications of performance level that correspond to particular pressures in
the air bag 32.
Typically, a high pressure would indicate an advanced level and a low pressure
would
indicate a novice level.
The rear of the boot may be recessed to form a groove that partially
accommodates
and locates the valve 58. A pair of arms could extend from the side of the
groove to secure
the valve in place. A similar arrangement may be used for the pressure gauge
56.
Alternatively, the valve 58 may project through a hole formed in the rear of
the boot
body 12. In this case, the valve 58 would be connected to a line that
communicated with the
air bag 32 and that passed through a hole formed in the bottom of the boot
body 12 and the
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hole in the rear of the boot body 12. The pressure gauge 56 may be connected
to a similar
line,
The present invention comprehends various other modifications, For instance,
Figure
6 shows a modification in which the sole plate 16 is made of a plastics
material rather than
metal. In this case, the pair of brackets 46A' and 46B' are mounted to the
sole plate 16' by
a metal plate 84 that is moulded within the sole plate 16.
The air bag 32 need not extend over the full length of the sole 34, but could
simply
be positioned under the heel portion 36. Also, the air bag 32 could be secured
to the boot
body 12 by releasable clips or rivets. An advantage of using releasable clips
is that the air
bag 32 could be easily replaced when damaged or worn. Also, the air bag 32
need not be
prepared of radial grade rubber, but could be made of any plastics material
that provides the
necessary elasticity and durability.
Although in the above embodiment the ski boot comprises a single sole plate
16, the
air bag 32 could instead be attached to a second sole plate secured to the
sole 34 of the boot
body. In this case, the air bag 32 would be interposed between the two sole
plates.
Figure 8 shows one of a pair of stabilizers 38B' according to an alternative
embodiment of the invention. The stabilizer 38B' is similar to the above-
described
embodiment; however, it differs in that the upper end of the boss 69B' is
closed and the shaft
68B' has an enlarged head 86 slidablyreceived in a cavity 88 formed in the
closed upper end
90 of the boss 69B'. The enlarged head 86 serves as a stop, abutting against
the upper end
of bushing 72B' and is a clearance fit within the cavity 88. A rubber stop 92
is fitted in the
upper end of the cavity 88 to cushion the impact between the end wall 94 of
the cavity 88
and the enclosed upper end 90 of the shaft. A rubber stop may also be fitted
around the shaft
to cushion the impact between the enlarged head and the bottom of the cavity.
A similar
stabilizer is provided on the opposite side of the rear of the boot. Such an
arrangement
allows the boss to move up and down on the stabilizers while the closed cavity
prevents
snow and debris from entering the stabilizer.
It is envisaged that the cavity could be equipped with a bushing and the
enlarged
head could be a sliding fit within it.
A further embodiment of the invention will now be described with reference to
Figures 9 to 12B. In many respects, the ski boot shown in Figure 9 is
identical to that
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described with reference to Figure 1 to 5 so only the parts that differ,
specifically the
stabilizer arrangement and the frontal pivot arrangement, will be described.
Moreover, for
clarity of depiction, certain elements, such as the air shock absorber 40 and
valve tube 5$, are
not shown.
Thus, in the ski boot 10' shown in Figure 9, the alternative stabilizers 38A'
and 38B'
are identical so only one of than, stabilizer 38A', will be described. The
stabilizer 38'
comprises a flange 102A upstanding from the edge portion of the sole plate 16'
at a position
adjacent the heel of the ski boot body 12'. An elongate vertical slot 104A
extends through the
flange 102A and aligns with a similar elongate slot 106A in a metal plate 108A
moulded into
the flange 102A so that an inwardly-facing surface of the metal plate 108A,
having a
longitudinal channel 11 OA therein, is exposed at the interior surface of the
flange 102A.
A nylon slide plate I12A is moulded into the side of the ski boot body 12' so
that it
protrudes from the side of the heel portion of the boot body 12' and engages
slidingly in the
channel 110A in the opposed surface of metal guide plate 108A in the flange
102A. A
tubular guide pin 114A protrudes outwardly from a metal reinforcing insert
(not shown) in
the nylon slide plate 112A and extends through the aligned slots 104A and
106A. The length
of the slots 104A/106A limits the travel of the guide pin 114A and, hence, the
up and down
movement of the nylon slide plate I IOA relative to the metal guide plate
I08A.
The lowermost end of the slots 104A/106A may be spaced from the sole plate 16'
by a
distance sufficient to protect against the air bag being totally compressed by
a high impact
loading. Conversely, the position of the uppermost end of the slots 104AI106A
will limit the
upwards movement of the boot body 12' relative to the sole plate 16' and keep
the two
together while helping to maintain a desired "unloaded" pressure in the air
bag.
A grease nipple 118A attached to the end of the tubular guide pin I14A allows
the
slidingly-cooperating bearing surfaces of the metal guide plate 108A and nylon
slide plate
112A, respectively, to be lubricated.
The flanges 102A and 102B may be separate or, as shown by dashed line in
Figure 10,
opposite side portions of a flange member 102' extending around the rear of
the sole plate
16'. The latter arrangement may provide increased stiffness. The stiffness
might be further
increased, if desired, by forming the metal plates 108A and 108B as opposite
end
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portions of a bifurcate metal plate extending around the flange member 102'
and/or through
the heel portion of the sole plate 16'.
It should be noted that, whereas the ski boot 10 shown in Figures 1 to 5 has a
single,
central pivot 18, the ski boot 10' shown in Figures 9 to 12B has a pair of
pivots 18A and 18B
5 spaced apart on either side of the longitudinal axis of the ski boot 12'.
Thus, as shown in
Figures 10 and 11, the sole plate 16' has two pairs of upstanding pivot
brackets 46A and
46B. Two single upper brackets 42A and 42B depend from the underside of the
boot body
12', each being received between a respective pair of the sole plate brackets
and secured in
place by pivot pins 50A and 50B, respectively, extending through aligned holes
in the
10 respective brackets. The pivots 18A and I 8B extend through sealed openings
54A and 54B,
respectively, in the air bag 32'.
It should be appreciated that this double-pivot arrangement enhances stability
and
could be used instead of the single pivot 18 in the ski boots described with
reference to
Figure 1 to 8,
INDUSTRIAL APPLICABILITY
Advantageously, embodiments ofthis invention provide a ski bootwith a
suspension
system comprising an air bag, an air shock absorber and stabilizers that
together provide
absorption of severe impact forces, a very smooth ride over uneven terrain and
lateral control
along the ski edges as the boot body moves up and down with respect to the
sole plate.
Furthermore, embodiments of the invention provide an impact absorbing ski boot
that is
simple and inexpensive to manufacture since existing boot designs can be
easily modified
so that the sole plate and air bag can be mounted on the sole of the boot
body. Also,
embodiments of the invention provide a ski boot having a suspension system
that can be
adjusted to attain a desired level of shock absorption.
Although an embodiment of the invention has been described and illustrated in
detail, it is to be clearly understood that the same is by way of illustration
and example only
and not to be taken by way of the limitation, the spirit and scope of the
present invention
being limited only by the appended claims.
