Note: Descriptions are shown in the official language in which they were submitted.
2,409,954 ! CA 02409954 2007-11-01
DISCLOSURE
Ski having a variable Bending Rigidity
05
characteristics, according to which skis are favourably.
rated'are those that reduce extreme variations in
longitudinal ski to terrain weight distributions for
negotiating undulating terrain, providing increased speed,
stability and liveliness.
In the ski according to this invention, ski flexing
determines.the longitudinal ski bending rigidity
characteristics, more particularly, the characteristics
related to longitudinal weight distribution when
encountering undulating terrain.
This invention discloses three related embodiments which
provide said characteristics.
Prior Art:
In conventional prior art skis, the longitudinal bending
rigidity is substantially constant and is independent of ski
flexing.
Skis having variable bending rigidity, in which the
longitudinal bending rigidity increases with ski flexing are
shown, amongst others, in Canadian Patent 2,338,608 which
teaches a ski wherein the longitudinal bending rigidity
increases with ski flexing through sliding motion limiting
means.
.\
-i-
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2,409,954 CA 02409954 2007-11-01
Other.prior art skis take advantage of leaf springs wherein
more springs become engaged, contributing to the bending
rigidity, as the ski is'flexed.
05 unlike the class of prior art skis mentioned above, in which
the bending rigidity increases with an increase in the
amount of ski flexing, in the ski according to this
invention, the bending rigidity decreases with an increase
in the amount of ski flexing, providing improved weight
distribution and increased liveliness.
Canadian Patent application, nr. 2,344,095, filed April 20
2001, entitled "Torsionally responsive ski" describes in
general terms a dual flex mode 5ki in which a first flexing
mode is determined by prior art ski bending rigidity in
combination with the bending rigidity of an overlying
flexible element and wherein a second flexing mode is
determined exclusively by prior art ski bending rigidity.
Operating Principle:
The ski according to this invention comprises pre-stressed
elements which.provide the flex related variable bending
rigidity.
Embodiments and modus operandi taking advantage of the
variable bending rigidity according to this invention, are
disclosed in the following description which shows and
describes various embodiments which express the best mode to
optimize a ski simultaneously for two or more different
magnitudes of terrain depressions.
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2,409,954 CA 02409954 2007-11-01
Brief description of the drawings
Figure 1 is a side elevational view of a conventional
prior art ski.
05 Figure 2 is a side elevational view of a conventional
prior art ski encountering a moderate terrain depression.
Figure 3 is a side elevational view of a conventional
.prior art ski encountering a moderate terrain depression and
wherein the ski is more flexible than the ski shown in
figures 1 and 2.
Figure 4 is a side elevational view of the ski shown in
figure 3, encountering a more severe terrain depression.
Figure 5 is a side elevational view of a conventional
prior art ski encountering a more severe terrain depression
and wherein the ski is more flexible than the ski shown in
figure 4.
Figure 6 is an exploded side elevational view of the
ski according to this invention.
Figure 7 is a side elevational view of the ski assembly
according to this invention.
Figure 8 is a side elevational view of the ski assembly
shown in figure 7, encountering a moderate terrain
depression.
Figure 9 is a side elevational view of the ski assembly
shown in figure 7, encountering a more severe terrain
depression.
Figure 10 is an exploded side elevational view of the
02409954 2007-11-01
2,409,954 ~ CA
ski according to this invention, haying multiple spring
elements.
Figure 11 is a side elevational view of the ski
05 assembly according to this invention.
Figure 12 is a side elevational view of the ski
assembly shown in figure 11, encountering a moderate terrain
depression.
Figure 13 is a side elevational view of the ski
assembly shown in figure 11, encountering a more severe
terrain depression.
Figures 14 through 19 are diagrammatic side elevational
views showing various binding supporting configurations.
Figure 20 is a plan view of a ski according to this
invention.
Figure 21 is a section taken along the plane of line
21-21 of the ski shown in figure 20 Figure'22 is a section taken along the
plane of line
22-22 of the ski shown in figure 20.
Figure 23 .is a plan view of a ski according to this
invention encountering a moderate terrain depression wherein
the ski is centrally flexed downwardly.
Figure 24 is a section taken along the plane of line
24-24 of the ski shown in figure 23, encountering a moderate
terrain depression wherein the ski is centrally flexed
downwardly.
Figure 25 is a section taken along the plane of line
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2,409,954 CA 02409954 2007-11-01
25-25.of the ski shown in figure 23, encountering a moderate
terrain depression wherein the ski is centrally flexed
downwardly.
05 Figure 26 is a plan view of a ski according to this
invention.
Figure 27 is a section taken along the plane of'line
27-27 of the ski shown in figure 26.
Figure 28 is a section taken along the plane of line
28-28 of the ski shown in figure 26.
Figure 29 is a plan view of a ski according to this
invention,.encountering a moderate terrain depression
wherein the ski is centrally fl.exed downwardly.
Figure 30 is a section taken.along the plane of line
30-30 of the ski shown in figure 29, encountering a moderate
terrain depression wherein the ski is centrally flexed
downwardly.
Figure'31 is a section taken along the plane of line
31-31 of the ski shown in figure 29, encountering a moderate
terrain depression wherein the ski is centrally flexed
downwardly.
Figure 32 is a side elevational view of a mandrel onto
which is deposited a fibre reinforced plastic layer.
Figure 33 is a section taken along the plane of line
33-33 of the mandrel shown in figure 32.
Figure 34 is a side elevational vi'ew of two identical
fibre reinforced plastic layers.
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2,409,954 CA 02409954 2007-11-01
Figure 35 is a side elevational view of a fibre
reinforced laminated plastic layer.
Figure 36 is a section taken along the plane of line
05 36-36 of figure 35.
A detailed description of this invention, with
reference to the drawings follows, explaining the advantages
of a ski having a variable bending rigidity, wherein the
modus operandi of three embodiments of the ski according to
this invention, having different longitudinal bending
rigidities, is compared to that of a conventional prior art
ski while encountering different terrain depressions.
In the following disclosure, pre-stressed, pre-tension
and pre-compression refers to conditions present without any
external force being exerted onto the ski.
Figure 1 is a side elevational view of a conventional
prior art ski 100, having a tip area'101, a tail area 102, a
top reinforcing sheet 103, a bottom reinforcing sheet 104
and a core of which the thickness is determined by the
spacing between top reinforcing sheet 103 and the bottom
reinforcing sheet 104, in which the longitudinal bending
rigidity is related to the core thickness, the elasticity of
the top reinforcing sheet 103 and the bottom reinforcing
sheet 104. As shown, the ski is not subjected to any
external forces and does not show conventional camber in
order to distinguish clearly between conventional camber and
the camber being part of the ski according to this
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r , ,
2,409,954 CA 02409954 2007-11-01
, .,
invention.
Figure 2 shows ski 100 encountering a moderate terrain
depression 105 and wherein ski 100 is urged towards
05 conforming to the terrain by a force F, which in
co-operation with the longitudinal bending rigidity causes
ski 100 to centrally flex downwardly.
Downwardly exerted force F is opposed by upwardly exerted
forces F 1 and F 2 which combined, equal force F and exert a
localized upward counter pressure towards tip area 101 and
tail area 102.
The localized character of these pressure areas is
undesirable and is indicative of inferior gliding
characteristics. A more equalized longitudinal load
distribution onto the terrain is known to improve the
gliding characteristics of a ski.
Figure 3 shows ski 110, being similar to ski 100, but
wherein the longitudinal bending rigidity is reduced
relative to ski 100, shown in figures 1 and 2, to optimize
ski 110 for terrain depression 105.
ski 110 is shown encountering moderate terrain depression
105 and wherein the ski is urged downwardly by a force F and
conforms to the terrain depression 105.
The opposed forces, exerted onto the ski by the surface of
terrain depression 105, as shown, arrows F 3, 4, 5, and 6,
indicate a significant and desirable equalization of the
longitudinal weight distribution relative to that of ski 100
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2,409,954 CA 02409954 2007-11-01
shown in figure 2.
Figure 4 shows ski 110 of figure 3 encountering terrain
depression 115, which is more severe than terrain depression
05 105.
Ski 110 is urged towards conforming to the surface of
terrain depression 115 by force F, which in co-operation
with the bending rigidity causes ski 110 to flex downwardly.
Downwardly exerted force F is opposed by upwardly exerted
forces F 1 and F 2, which equal force F and exert
undesirable upward localized counter pressures towards tip
area 111 and tail area 112 as stated before.
The localized character of thes.e pressure areas is
indicative of inferior gliding characteristics, since
optimum gliding characteristics depend on a more equal
longitudinal weight distribution.
Although the longitudinal bending rigidity of ski 110 has
been optimized for moderate terrain depression 105 through a
decrease in its longitudinal bending rigidity, it is clearly
not optimum for the more severe terrain depression 115.
Figure 5 shows ski 120 being urged to conform to
terrain depression 115.
To optimize ski 120 for terrain depression 115, the
longitudinal bending rigidity is still further reduced
relative to ski 110 shown in figures 3 and 4.
The longitudinal weight distribution, as indicated by the
length of arrows F 7, 8, 9 and 10, approximates the weight
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2,409,954 CA 02409954 2007-11-01
distribution indicated by arrows F 3, 4, 5, and 6, shown in
figure 3, indicating a significant and desirable improvement
of the longitudinal weight distribution, relative to ski
110, shown in figure 4.
05
From the foregoing, it is clear that a conventional prior
art ski, wherein the longitudinal bending rigidity is
constant and in which the longitudinal bending rigidity is
optimized to provide equal weight distribution for
conforming to moderate terrain depression 105, does not
provide optimum weight distribution when encountering more
severe terrain depression 115 and vice versa, unless the
longitudinal bending rigidity is reduced.
Further, it is clear that the ski according to this
invention, in which the bending rigidity decreases with an
increase in ski flexing, will provide a more equalized
weight distribution than a ski in which the bending rigidity
is constant or a ski wherein the bending rigidity increases
with an increase in ski flexing.
First Embodiment
Figure 6 is an exploded side elevational view of the
first embodiment of the ski according to this invention,
showing a spring element 200, having a central downward
unstressed camber, a forward end 201, a rearward end 202, a
top surface, a bottom surface 203 and a core.
separately shown is ski runner 204 having forward and
rearward mounting means 205 and 206, a central area disposed
-9-
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CA 02409954 2007-11-01
2,409,954
between the forward and rearward mounting means, having a
central upward unstressed camber, a tip area 208, a tail
area 209, a top surface 207, a bottom surface 210 and a
05 core, wherein the longitudinal bending rigidity of the
central area approximates the longitudinal bending rigidity
of spring element 200 and wherein the unstressed camber of
the central area approximates the unstressed camber of
spring element 200.
Figure 7 shows ski runner 204 which is vertical
hingedly, longitudinal slidably secured to forward end 201
and rearward end 202 of spring element 200, via the forward
and rearward mounting means 205.and 206, forming a pre-
stressed ski assembly, wherein the central area of the ski
runner top surface 207 longitudinal slidably engages spring
element bottom surface 203.
The process of assembly forces the spring element and ski
runner to become pre-stressed.
When spring element 200 and ski runner central area top
surface 207 are intimate slidably engaged, the longitudinal
bending rigidity of the central area of the ski assembly is
the sum total bending rigidity of spring element 200 and the
ski runner central area.
The camber of the central area of the ski assembly, as shown
. in figure 7, is determined by a the sum of the unstressed
camber and bending rigidity of spring element 200 and the
unstressed camber and bending rigidity of the ski runner
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2,409,954 CA 02409954 2007-11-01
central area, as shown in figure 6.
It will be noted that the camber of the ski assembly shown
in figure 7 is considerably less than the camber of the ski
05 runner shown in figure 6.
The difference in camber being indicative of the amount of
pre-stress.
Figure 8 shows ski runner 204, being part of the ski
assembly, subjected to downwardly exerted force F,
conforming to terrain depression 105 in a manner similar to
that described with reference to ski 110 as shown in figure
3. The longitudinal bending rigidity of the ski assembly is
configured to be similar to that of ski 110, shown in
figures 3 and 4, and wherein the longitudinal weight
distribution of the ski assembly, when encountering terrain
depression 105, is similar to that of ski 110 shown in
figure 3, providing a ski assembly of which the longitudinal
weight distribution is optimum for terrain depression 105.
The central downward spring camber as shown, is less than
the unstressed downward spring camber shown in figure 6,
indicating that the spring element is contributing to the
bending rigidity of the ski runner central area.
The longitudinal weight distribution as indicated by arrows
F 3, 4, 5 and 6 is identical to that shown in figure 3.
Figure 9 shows the ski runner 204 conforming to terrain
depression 115, wherein the central downward flexing of the
ski runner central area exceeds the unstressed downward
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,
2,409,954 CA 02409954 2007-11-01
camber of spring element 200, causing ski runner central
area top surface 207 and spring element bottom surface 203,
to disengage and spring element 200 to cease contributing to
05 the bending rigidity of the ski runner central area.
The point of disengagement between ski runner top surface
and spring element bottom surface is referred to as the
point of transition.
As shown, in figures 8 and 9, the amount of unstressed
central downward camber of spring element 200 determines the
point of transition at which the ski runner central d,ownward
flexing changes the ski flex characteristics from an initial
flex mode into a less rigid final flex mode.
In figures 6 through 9, the mounting means are shown to be
disposed adjacent to the ends of the spring elements and
provide for a vertically hinged movement between the spring
element and the ski runner and wherein at least one of the
mounting means permits longitudinal slidable movement
between the ski runner and the spring element.
The initial longitudinal bending rigidity is determined by
the ski runner in combination with the spring element.
The final longitudinal bending rigidity, which is less than
the initial longitudinal bending rigidity, is determined by
the ski runner.
The ski assembly shown in figures 8 and 9, shows two
different ski flexing related bending rigidities, affording
optimization for two different terrain depression
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2,409,954 CA 02409954 2007-11-01
magnitudes.
optimization of the longitudinal bending rigidity for more
than two terrain depression magnitudes intermediate that of
05 terrain depressions 105 and 115, is implemented by replacing
single spring element 200, shown in figures 6 through 9, by
two or more spring elements which provide multi stage
bending rigidity.
Figure 10 is an exploded side elevational view of a ski
assembly showing unstressed spring element 250, having
forward and rearward ends 251 and 252 and unstressed spring
element 253 having forward and rearward ends 254 and 255,
wherein the central downward unstressed camber of lower
spring element 253 exceeds the central downward unstressed
camber of spring element 250, and wherein the combined
spring element bending rigidity equals that of spring
element 200 shown in figure 6.
Separately shown is ski runner 204 having forward and
rearward mounting means 205 and 206, a central area disposed
between the forward and rearward mounting means, having a
central upward unstressed camber, a tip area 208, a tail
area 209, a top surface 207, a bottom surface 210 and a
core, wherein the longitudinal bending rigidity of the
central area approximates the combined longitudinal bending
rigidity of spring elements 250 and 253 and wherein the
unstressed camber of the central area approximates the
combined unstressed camber of spring elements 250 and 253.
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2,409,954 ` CA 02409954 2007-11-01
Figure 11 is side elevational view of the ski assembly,
showing the spring elements and the ski runner assembled
into a ski, wherein the forward and rearward ends of the
05 spring elements are secured to the ski runner via the
forward and rearward mounting means 205 and 206 and of which
at least one mounting means is longitudinal slidable and
wherein the ski assembly is not subjected to any external
forces, providing a maximum initial ski bending rigidity.
Figure 12 is a side elevational view of the ski
assembly, showing the position of spring elements 250,and
253, relative to ski runner 204, wherein the ski is
moderately flexed and wherein upper spring element 250 is
disengaged from lower spring element 253, which remains
engaged with the ski runner, providing a central ski bending
rigidity, which is less than the central ski bending
rigidity shown in figure 11.
Figure 13 is a side elevational view of the ski
assembly showing the position of spring elements 250 and
253, relative to ski runner central surface, wherein the ski
is maximally flexed.
As shown, the spring element surfaces are disengaged from
the ski runner, providing a minimum ski bending rigidity.
The ski assembly shown in figures 11, 12 and 13 shows three
different ski flexing related bending rigidities, which each
may be optimized for a different terrain depression.
In the ski assembly, shown in figures 8, 9, 12 and 13, force
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2,409,9r'J4 CA 02409954 2007-11-01
F is applied directly to a longitudinally central area of
the ski runner.
To secure a binding to a longitudinal central portion of the
05 ski runner without impeding the separation between the
spring element and the ski runner requires the binding to be
permanently raised above the ski runner, resulting in an
awkward, undesirable structure.
In a preferred embodiment of this invention, the binding is
secured to the ski runner via a binding supporting
structure.
,
Figure 14 is a diagrammatic side elevational view of a
ski assembly of the character shown in figures 6 through 9,
showing an embodiment wherein force F exerts a vertical
force onto ski runner 204 via a binding supporting structure
300, having forward and rearward binding support mounting
means 301 and 302, which secure the binding supporting
structure onto ski runner 204 at two longitudinally separate
areas which are disposed forwardly and rearwardly of the
forward and rearward mounting means 205 and 206 and wherein
at least one of the binding support mounting means is
longitudinal slidable.
Figure 15 is a diagrammatic side elevational view of
the ski assembly of the character shown in figures 6 through
9 showing another embodiment wherein the binding support 300
is vertical hingedly secured to the ski runner 204 via the
forward binding support mounting means 301, wherein the
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2,409,954 CA 02409954 2007-11-01
binding support is vertical hingedly secured to the ski
runner via the rearward binding support mounting means 302
and the rearward mounting means 206 and wherein at least one
05 of the binding support mounting means is longitudinal
slidable.
Figure 16 is a diagrammatic side elevational view of
the ski assembly of the character shown in figures 6 through
9 showing another embodiment wherein binding support 300 is
vertical hingedly secured to ski runner 204 via the forward
and rearward binding support mounting means 301, 302 and the
forward and rearward mounting means 205, 206 and wherein at
least one of the binding support mounting means is
longitudinal slidable.
In the embodiments shown in figures 14 through 16, the point
of transition is entirely determined by the unstressed
spring camber and the flexing of the ski runner central
area.
Figure 17 is a diagrammatic side elevational view of
the ski assembly of the character shown in figures 6 through
9 showing another embodiment wherein the binding support 300
is vertical hingedly secured to spring element 200 via the
forward binding support mounting means 301, wherein the
binding support is vertical hingedly secured to the ski
runner 204 via the binding support rearward mounting means
302 and wherein at least one of the binding support mounting
means is longitudinal slidable.
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2,409,954 CA 02409954 2007-11-01
Figure 18 is a diagrammatic side elevational view of
the ski assembly of the character shown in figures 6 through
9 showing an embodiment wherein binding support 300 is
05 vertical hingedly secured to the spring element 200 via the
binding support forward mounting means 301 and wherein the
binding support is vertical hingedly secured to the ski
runner 204 via the rearward binding support mounting means
302 and the rearward mounting means 206 and wherein at least
one binding support mounting means is longitudinal slidable.
Figure 19 is a diagrammatic side elevational view of
the ski assembly of the character shown in figures 6 through
9 showing an embodiment wherein,binding support 300 is
vertical hingedly secured to the spring element 200 via the
binding support forward and rearward mounting means 301, 302
and wherein at least one of the binding support mounting
means is longitudinal slidable.
in the embodiments shown in figures 17 through 19, the point
of transition is determined by a combination of skier
exerted downward force onto spring element 200, the spring
element bending rigidity, the unstressed spring element
camber and the flexing of the intermediate ski area and may
actively be controlled by the actions of the skier.
The binding support may simultaneously impart desirable
torsional characteristics to the ski.
when elongated spring element 200 is disposed between the
binding support mounting means 301 and 302, or wherein at
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` 2,409,954 CA 02409954 2007-11-01
least one spring element mounting means corresponds with one
of the binding support mounting means, as shown in figures
14 through 16, spring element 200 may be replaced by one or
05 more compression coil springs or equivalent spring elements,
such as air springs, resilient materials or air inflated
rubber pouches, which exert a pressure onto the ski runner
top surface, relative to the binding support lower surface,
equivalent to that exerted by the elongated spring element
relative to the elongated spring element mounting means.
The spring element unstressed camber and longitudinal,
bending rigidity may be any value, as long as the spring
element increases the bending rigidity of the central ski
portion during initial ski flexing and does not contribute
to the bending rigidity of the intermediate ski portion
during final -moderate- ski flexing.
The spring element contributes to the bending rigidity of
the central ski area when the spring element is firmly
engaged with the central area of the ski runner.
spring elements may be vertically spaced, side by side or
any combination of vertical and side by side spacing.
In the ski according to this invention, the length of the
spring element may vary and some or all of the spring
elements may be tubular.
The areas between the ski and the spring elements may be
filled with a resilient material such as foam rubber to
prevent or reduce snow intrusion during disengagement.
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02409954 2007-11-01
2,409,954 CA
The spring surfaces may be coated and shaped to deter snow
adhesion and snow intrusion.
spring elements may be added that are more valued for their
ability to expel snow than for their ability to contribute
05
to the bending rigidity of a ski.
The terrain undulations shown are rather severe, outside the
range of normally anticipated terrain encounters, and are
intended to facilitate an understanding of the modus
operandi.
The principles shown to optimize a ski for multiple terrain
depressions that are outside the range normally encountered,
are similarly applicable to advantageously optimize a ski
for terrain depressions within the normal range of
anticipated terrain depressions.
In the embodiments shown and described, the variable bending
rigidity area is limited to a central area of the ski.
In another embodiment, the variable bending rigidity area is
similar to that of the central area disposed between forward
and rearward mounting means 205, 206 as shown in figure 7,
but the spring element and associated mounting means are
disposed towards the forward or rearward area of the ski.
.~-
Thus is disclosed the first embodiment of a ski assembly,
comprising one or more spring elements, in which the
variable bending rigidity is optimized to provide a more
equalized longitudinal weight distribution for at least two
different terrain depressions and wherein the bending
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= 2,409,954 CA 02409954 2007-11-01
rigidity decreases with an increase in ski flexing.
A second embodiment provides a variable bending rigidity
area which may extend along all or most of the length of the
05 ski, wherein a variable bending rigidity control layer,
further referred to as "control layer", takes advantage of
the difference between the compressive and tensile
elasticity of rope-like elements such as fibres, straps,
thin sheets or the like.
The fibres of this control layer are pre-tensioned by the
longitudinal bending rigidity and camber of a lower ski
portion, in combination with an upper core.
within the range of normal ski flexing, the top area of a
ski can only be compressed, while the bottom area can only
be tensioned.
In order to take advantage of the difference between the
compressive and tensile elasticity of the control layer, the
tension within the fibres has to reach zero within the
expected range of ski flexing.
This "off-set" is implemented through pre-tensioning of the
rope like elements.
* In this second embodiment, the ski is fully integrated with
functionally similar equivalents of the pre-stressed spring
element and the pre-stressed ski runner, described in the
first embodiment, providing a ski having the advantages of
the previous embodiment shown and disclosed without the
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2,409,954 CA 02409954 2007-11-01
disadvantages associated with the disengagement between ski
runner and spring element surfaces, providing manufacturing
and maintenance advantages, alleviating problems associated
05 with snow intrusion and wherein the ski is indistinguishable
in appearance from a conventional prior art ski.
Figure 20 is a top plan view of a ski 400 having a tip
401, a tail 402, a control layer 403, and side margins,
wherein the ski is not subjected to any external forces.
Figure 21 is a section taken along the plane of line
21-21 of figure 20, showing a ski having a longitudinally
pre-tensioned bottom reinforcing sheet 404, a lower core
405, a longitudinally pre-compressed top reinforcing sheet
406, an upper core 407 and a rope-like pre-tensioned control
layer 403, wherein the variable bending rigidity
characteristics reside in the control layer.
Figure 22 is a section taken along the plane of line
22-22 of figure 20 showing a more detailed view of
longitudinally pre-tensioned bottom reinforcing sheet 404,
which is adhesively bonded onto a lower core 405,
longitudinally pre-compressed top reinforcing sheet 406,
which is adhesively bonded onto lower core 405 and onto
upper core 407 and longitudinally pre-tensioned rope like
control layer 403, which is adhesively bonded onto upper
core 407, wherein the control layer tension is indicative of
the control layer contribution to the longitudinal
bending rigidity of the ski.
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2,409,954 CA 02409954 2007-11-01
Figure 23 is a top plan view of ski 450, having a tip
451, a tail 452, side margins and a control layer 453,
wherein the ski is centrally flexed downwardly to or beyond
05 the transition point.
Figure 24 is a section taken along the plane of line
24-24 of figure 23, showing a ski having a longitudinally
tensioned bottom reinforcing sheet 454, a lower core 455, a
longitudinally compressed top reinforcing sheet 456, an
upper core 457 and a control layer 453, wherein the variable
bending rigidity characteristics reside in the control layer
,
and wherein the control layer tension is zero, indicating
that the control layer is not contributing to the
longitudinal bending rigidity of the ski.
Figure 25 is a section taken along the plane of line
25-25 of figure 23, showing a more detailed view of the
longitudinally tensioned bottom reinforcing sheet 454, a
lower core 455, longitudinally compressed top reinforcing
sheet 456, upper core 457 and control layer 453, wherein the
control layer tension is zero.
zn the embodiments shown in figures 20 through 25, the
compression of top reinforcing sheets 406 and 456 and the
tension of bottom reinforcing sheets 404 and 454 will never
reach zero within the range of normal ski flexing.
only the tension of control layers 403 and 453 will reach
zero at or beyond the point of transition and will remain
zero beyond the point of transition.
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2~409~95~ CA 02409954 2007-11-01
The need for pre-tensioning becomes evident when
one considers that without pre-tension, the control layer
will never be tensioned during normal use of the ski, making
05 it impossible to distinguish between the tensile and
compressive elasticity.
In this second embodiment, the control layer may comprise
fibres which are embedded in a tension and compression
neutral plastic layer.
The control layer is separated from the top reinforcing
sheet by an upper core and is tensioned by the camber and
bending rigidity of a lower ski portion.
The initial longitudinal bendin,g rigidity, when the ski is
relaxed as shown in figure 21 and wherein the control layer
fibres are pre-tensioned, is determined by the tensile
elasticity of the bottom reinforcing sheet, the lower core
thickness, the compressive elasticity of the top reinforcing
sheet, the upper core thickness and the tensile elasticity
of the pre-tensioned fibres, and wherein the longitudinal
elasticity of the upper core areas adjacent to the top
reinforcing sheet and the control layer fibres equals or
exceeds the longitudinal elasticity of the top reinforcing
sheet and that of the control layer fibres and wherein the
upper core transmits the shear forces between the top
reinforcing sheet and the control layer fibres, and further,
wherein the longitudinal elasticity of the lower core areas
adjacent to the bottom reinforcing sheet and the
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CA 02409954 2007-11-01
2,409,954
top reinforcing sheet equals or exceeds the longitudinal
elasticity of the bottom reinforcing sheet and the top
reinforcing sheet, and wherein the lower core transmits
shear forces between the bottom reinforcing sheet and the
05
top reinforcing sheet.
when a longitudinal central area of the ski shown in figure
21 is progressively flexed downwardly, to the curvature
shown in figure 24, the tension in the control layer fibres
decreases progressively to zero.
The point at which the tension in the fibres reaches,zero
corresponds to the point of transition described with
reference to the first embodiment.
The final longitudinal bending rigidity, is determined by
the tensile elasticity of the bottom reinforcing sheet, the
lower core thickness, and the compressive elasticity of the
top reinforcing sheet, without a substantial contribution of
the control layer fibres and the upper core longitudinal
elasticity.
Thus is disclosed a second ski embodiment wherein bending
rigidity decreases with an increase in ski flexing..
The fibres are pre-conditioned to facilitate buckling,
reducing resistance to compression. The upper core top
surface, in addition to providing spacing between the top
reinforcing sheet and the control layer, provides support
for the bindings or binding supporting structures.
In addition to the upper core top surface, the lower core
-24-
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2,409,954 CA 02409954 2007-11-01
top surface may provide support for bindings or binding
supporting structures.
The upper core, while having an equal or higher elasticity
05 than the adjacent control layer and top reinforcing sheet,
may comprise areas of reduced elasticity, providing support
for bindings or other mounted devices.
In still another related embodiment, the upper and lower
cores are fused into one single core by replacing top
reinforcing sheet 406 of figure 22 and sheet 456 of figure
25 by a virtual top reinforcing sheet.
In this embodiment, the longitudinal elasticity of the
single core varies along the core thickness, the minimum
elasticity being in the zone formerly occupied by top
reinforcing sheets 406, 456, and wherein the longitudinal
elasticity of this zone approximates the longitudinal
elasticity of former top reinforcing sheet 406, 456.
In another related embodiment, the single fused core is
converted into a vertically stacked aggregation of cores,
each one having a different longitudinal elasticity.
The core, as described in the previous embodiments, may
comprise relatively homogeneous materials having a
vertically and/or longitudinally varying modulus of
elasticity, which occupy the entire area between the various
reinforcing sheets and the control layer.
In a related embodiment, the core may solely comprise side
walls, longitudinal ribs, transverse ribs, angular ribs or
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2,409,954 ~ CA 02409954 2007-11-01
any combination of both.
A single rib in this context is a narrow member, sandwiched
between an upper and lower layer, of which the length
05 exceeds the height and wherein the vertical portion is
perpendicular to the upper and lower layers.
A core comprising longitudinally oriented ribs, which may
include side walls, provides a minimum longitudinal core
elasticity, while a core comprising transversely oriented
ribs provides maximum longitudinal core elasticity.
Angularly oriented ribs provide any required amount of
longitudinal core elasticity, depending on the angular
orientation, relative to the longitudinal axis.
The lower core may comprise one structure while the upper
core may comprise another structure and vice versa.
The pre-compression and pre-tension of the reinforcing
sheets and the control layer, shown in figures 20, 21 and 22
may be accomplished in the following steps:
unstressed reinforcing sheets 404 and 406 are adhesively
bonded to lower core 405 and upper core 407, providing a ski
portion of which the bending rigidity corresponds to the
desired final bending rigidity and of which the camber
exceeds the desired final camber, after which the ski is
centrally flexed downwardly to the curvature of transition,
at which curvature the unstressed control layer is
adhesively bonded to the upper surface of the upper core
407, after which the ski is relaxed.
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2,409,954 CA 02409954 2007-ii-0i
A third embodiment provides a variable bending rigidity
area which like the second embodiment may extend over all or
most of the length of the ski, wherein a variable bending
05 rigidity control layer takes advantage of difference between
the compressive and tensile elasticity exhibited by various
composite materials, more particularly fibres embedded
within a plastic layer or fibres laminated onto a plastic
sheet. The longitudinal tensile elasticity of the control
layer being substantially that of the fibres and the
longitudinal compressive elasticity of the control l4yer
being substantially that of the plastic.
within the range of normal ski.flexing, the top area of a
ski can only be compressed, while the bottom area can only
be tensioned.
In order to take advantage of the difference between the
compressive and tensile elasticity, the tension within the
control layer, has to change to compression and vice versa,
without external forces exerted onto the control layer
having to change from compression to tension or vice versa.
This "off-set" is implemented through pre-compression of the
plastic layer and pre-tensioning of the fibres.
Figure 26 is a top plan view of ski 500 having a tip
501, a tail 502, a control layer 503 and side margins,
wherein the ski is not subjected to any external forces.
Figure 27 is a section taken along the plane of line
27-27 of figure 26, showing a ski having a longitudinally
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2,409,954 CA 02409954 2007-11-01
pre-tensioned bottom reinforcing sheet 504, which is
adhesively bonded onto a core 505 and a control layer 503,
which is adhesively bonded onto core 505, wherein the
05 variable bending rigidity characteristics reside in the
control layer.
Figure 28 is a section taken along the plane of line
28-28 of figure 26, showing a more detailed view of relaxed
bottom reinforcing sheet 504, core 505 and control layer 503
comprising longitudinally oriented pre-tensioned fibres 506,
embedded within a longitudinally pre-compressed plastic
layer.
Figure 29 is a top plan view of ski 550, having a tip
551, a tail 552, side margins and control layer 553 wherein
the ski is centrally flexed downwardly to or beyond the
transition point.
Figure 30 is a section taken along the plane of line
30-30 of figure 29, showing a ski having a longitudinally
tensioned bottom reinforcing sheet 554, a core 555 and a
control layer 553, wherein the variable bending rigidity
characteristics reside in the control layer and wherein the
plastic layer is longitudinally compressed while the
tension in the fibres has reached zero.
Figure 31 is a section taken along the plane of line
31-31 of figure 29, showing a more detailed view of the
longitudinally tensioned bottom reinforcing sheet 554, core
555 and control layer 553 having longitudinally oriented
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2,409,954 ~ CA 02409954 2007-11-01
fibres 556, embedded within a plastic layer which is
longitudinally compressed by shear forces transmitted from
the bottom reinforcing sheet 554 by the core 555 and wherein
05 the fibre tension is zero.
The initial longitudinal bending rigidity, when the ski is
not flexed, as shown in figure 27, wherein the fibres are
pre-tensioned within a pre-compressed plastic layer, is
determined by the tensile elasticity of the bottom
reinforcing sheet, the thickness of the core, the
compressive elasticity of the plastic layer and the tensile
elasticity of the fibres, and wherein the longitudinal
elasticity of the core areas adjacent to the bottom
reinforcing sheet and the control layer equals or exceeds
the longitudinal elasticity of the bottom reinforcing sheet
and the control layer, and wherein the core transmits shear
forces between the bottom reinforcing sheet and the control
layer.
when a longitudinally central area of the ski shown in
figure 27 is progressively flexed downwardly, the
longitudinal compression of the plastic layer increases
progressively while the tension in the fibres decreases
progressively towards zero.
The point at which the tension in the fibres reaches zero,
after which the fibres cease to contribute to the
longitudinal bending rigidity of the ski, corresponds to the
point of transition described with reference to the first
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2,409,954 CA 02409954 2007-11-01
.
embodiment.
The final longitudinal bending rigidity, when the ski is
centrally flexed as shown in figure 30, and wherein the
05 control layer fibres are not tensioned, is determined by the
tensile elasticity of the bottom reinforcing sheet, the
thickness of the core and the compressive elasticity of the
plastic layer.
The fibres are pre-conditioned to assume a coiled, zigzag or
other similar configuration when not tensioned, facilitating
fibre compression within the plastic layer. ,
Although the control layer is never subjected to tension by
external forces, within the control layer, the direction of'
forces exerted onto the fibres will change from tension to
zero tension at the point of transition and will remain at
zero beyond the point of transition.
In the embodiments, shown in figures 26 through 31, the
fibre orientation is parallel to the longitudinal ski axis.
In other embodiments, the fibres are oriented at a 45 degree
angle relative to the longitudinal ski axis,
providing a longitudinal and transverse rigidity both of
which are dependant on the amount of ski flexing.
The 45 degree angle is cited as an example and may vary
along the length of the ski, depending on the desired ratio
between the longitudinal and transverse bending rigidity as
a function of ski flexing.
In one embodiment the ski comprises multiple full width
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2,409,954 CA 02409954 2007-11-01
=
=
vertically adjacent control layers, each layer having a
different initial internal stress, reaching zero tension at
different amounts of ski flexing, providing multiple
05 transition points, resulting in a more gradual decrease in
ski bending rigidity upon ski flexing.
zn another embodiment, the ski comprises multiple full width
vertically adjacent control layers, each layer having
identical initial internal stress, being vertically spaced
from each other, taking advantage of geometric positions
relative to one another, providing a gradual decrease in ski
bending rigidity upon ski flexing.
In one embodiment, the control layer comprises transverse
adjacent longitudinally oriented portions.
In another embodiment, the control layer comprises
longitudinally spaced portions which impart different
amounts of flex related bending rigidity to longitudinally
spaced areas of the ski, providing longitudinal area
specific control over ski flexing.
The embodiments described may be combined with anyone of the
.previous embodiments shown or parts of embodiments shown and
described.
Figures 32 through 36 show a method for imparting a
graduated pre-tension to longitudinally oriented fibres and
for imparting a graduated pre-compression to a plastic layer
of the character described with reference to the control
layer 503, shown in figure 28, wherein the fibres are
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29409,954 CA 02409954 2007-11-01
=
embedded within or laminated onto a plastic layer.
Figure 32 is a side elevational view of a mandrel 600
having a circumference 601, onto which is deposited one full
05 ski length variable bending rigidity control layer 602.
Figure 33 is a section taken along the plane of line
33-33 of figure 32, showing mandrel 600, mandrel
circumference 601, fibre reinforced plastic layer 602 having
an intermediate circumference 603 and a maximum
circumference 604, wherein the fibres are wrapped around the
mandrel, forming a reinforcement layer 605 which extends
from circumference 601 to circumference 603.
The reinforcement layer is embedded in or laminated onto a
plastic layer 606 which extends onto circumference 604.
Figure 34 shows two identical circularly curved
juxtaposed reinforced plastic layers, after removal from
mandrel 600, having convex outer surfaces 604A and 604B
facing each other.
Figure 35 shows outer surfaces 604A and 604B bonded
together, forming a flat layer.
The conversion from two circularly curved layers
to one flat layer causes the fibres disposed between
circumference 601A and 603A and between 601B and 603B to
become tensioned and causes the plastic layer 606A and 606B,
disposed between circumference 603A and 603B to become
compressed.
Figure 36 is a section taken along the plane of line
-32-
* 2,409,954 ~ CA 02409954 2007-11-01
36-36 of figure 35, showing longitudinally compressed
plastic layer 606A and 606B, which is sandwiched between
longitudinally oriented and longitudinally tensioned fibres
05 605A and 605B.
The required ratio between the minimum layer length,
corresponding to the mandrel circumference 601, which
provides maximum tension to the fibres and the maximum layer
length corresponding to the maximum circumference 604, which
provides maximum compression to the plastic layer, is
generally less that 2%.
For clarity, the ratio between the minimum and maximum layer
length as shown in figure 33, by far exceeds the required
range of ratios. The ratio can be reduced by decreasing the
layer thickness relative to the mandrel diameter.
In the embodiments disclosed, the elements providing the
variable bending rigidity are described as residing in a
ski.
In other embodiments, these elements are incorporated into
or may be part of an attachment or a binding for mounting
onto a ski, wherein these attachments or bindings impart the
variable bending rigidity to a ski.
Throughout this disclosure, reference is made to a ski,
which is understood to include a pair of skis, snow boards
skate boards and more generally a foot attached article of
sports equipment for negotiating undulating terrain.
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2,409,954 ~ CA 02409954 2007-11-01
The embodiments shown may be combined with anyone of the
disclosed embodiments or portions of the disclosed
embodiments by anyone skilled in the art, without departing
05 from the spirit of this invention.
Therefore, the scope of this invention is not limited to the
exact embodiments shown, but only as indicated by the
appended claims.
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