U.S. patent number 3,853,192 [Application Number 05/404,411] was granted by the patent office on 1974-12-10 for power driven ski.
This patent grant is currently assigned to Saroy Engineering. Invention is credited to Royce Hill Husted.
United States Patent |
3,853,192 |
Husted |
December 10, 1974 |
POWER DRIVEN SKI
Abstract
A power driven ski is divided by an aperture into anterior and
posterior ski portions, which are held one to the other by a bridge
so that their combined undersurfaces form a longitudinally smooth
skiing undersurface throughout the length of the ski. A motor
driven endless tread is circulateably supported around the
posterior ski portion for thrusting against the snow over which the
posterior ski portion slides.
Inventors: |
Husted; Royce Hill (Wheaton,
IL) |
Assignee: |
Saroy Engineering (Wheaton,
IL)
|
Family
ID: |
23599496 |
Appl.
No.: |
05/404,411 |
Filed: |
October 9, 1973 |
Current U.S.
Class: |
180/181 |
Current CPC
Class: |
A63C
5/085 (20130101); B62M 27/00 (20130101); B62M
2027/022 (20130101) |
Current International
Class: |
A63C
5/00 (20060101); A63C 5/08 (20060101); B62M
27/00 (20060101); B62m 027/00 () |
Field of
Search: |
;180/5R ;280/11.11E |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Goodman; Philip
Attorney, Agent or Firm: Shiber; Samuel
Claims
I claim:
1. In a power driven ski for attachment to a skier's foot and for
slidingly negotiating snow as with a conventional ski, said power
driven ski having in combination;
a. a ski with an aperture dividing it into an anterior ski portion
having a longitudinally smooth anterior undersurface and a
posterior ski portion,
b. a bridge holding said ski portions to each other,
c. means for attaching said ski to a skier's foot,
d. an endless tread circulateably supported around said posterior
ski portion having at least one tension carrying member and a
plurality of cleats attached to said tension carrying member for
thrusting against the snow,
e. means for circulateably supporting said tread around said
posterior ski portion, and
f. motor means coupled to said tread for circulating said tread
around said posterior ski portion,
the improvement wherein the posterior ski portion has a
longitudinally smooth, snow contacting stationary undersurface and
said bridge holds said ski portions in position one relative to the
other so that said undersurfaces jointly form a longitudinally
smooth skiing undersurface substantially throughout the length of
said ski.
2. A power driven ski as in claim 1 including a one way clutch
coupling said motor means to said tread.
3. A power driven ski as in claim 1 wherein the engagement of one
of said blades with snow near the front of said posterior
undersurface is sequenced out of phase with the disengagement of
another one of said blades from snow near the rear of said
posterior undersurface.
4. A power driven ski as in claim 1 wherein said tread blades are
outwardly protruding, and the tread circulates from above to below
said posterior ski portion through said aperture, over a front
sprocket having a first pitch-line radius and thereafter over an
arched ramp having a substantially larger pitch-line radius, said
arched ramp being adapted to guide said cleats downwardly on an arc
into gradual engagement with snow.
5. A power driven ski as in claim 1 wherein said posterior
undersurface is stepped downwards relative to said anterior
undersurface.
6. A power driven ski as in claim 1 wherein said blades are
outwardly protruding and are adapted to erect into the snow on a
bearing formed at their rear tip while engaging the snow and
thereby cause said tension carrying member to assume a zig-zag
configuration as viewed on a plane which is parallel to the chain
and perpendicular to said posterior undersurface, said zig-zag
configuration causing tension forces carried by said tension
carrying member to negate bending moments imposed on it by said
blades which are attached to it.
7. A power driven ski as in claim 6 wherein said tension carrying
member is circulatebly supported on a drive sprocket which is
coupled to said motor means, and on a rear sprocket which is
mounted on said posterior ski portion by resilient means which
permit said tension carrying member to assume said zig-zag
configuration without becoming stretched.
8. A power driven ski as in claim 6 wherein said tension carrying
member comprises a chain of links hinged one to the next to permit
said links to pivot one relative to the next as viewed on a plane
which is parallel to said chain and is perpendicular to said
posterior undersurface, but resist such pivoting as viewed on a
plane which is parallel to said posterior undersurface.
9. A power driven ski as in claim 8 wherein the part of said
tension carrying member which is under said ski is longitudinally
guided in a channel in said posterior undersurface to thereby
shelter said tension carrying member from lateral movement between
the ski and snow as well as for supporting the tread in its
resistance to assume a zig-zag configuration on a plane that is
parallel to said posterior undersurface due to asymetrical loading
of the blades.
Description
BACKGROUND OF DISCLOSURE
This invention relates to skis, and specifically to a ski having
power driven means for propelling a skier.
Presently there is a polarization between outdoor winter sport
enthusiasts. The purists adhere to skis propelled by gravity, while
the modernists enjoy the control of motor power together with the
winter outdoors environment by mounting a snowmobile.
A power driven ski, as explained in Richard F. Thompson U.S. Pat.
Nos. 3,645,348 and 3,710,881 (of which I am an assignee) which are
herein incorporated by a reference, provides the skier on the one
hand with some of the challenges of downhill skiing such as holding
balance, steering and braking by body manipulation, etc., without
being limited to a "one-way" skiing on an often-crowded hill
equipped with a ski lift. On the other hand, a power driven ski is
much less cumbersome to use, transport and store than a snowmobile,
less expensive to produce and maintain, and provides a more
exciting form of sport since it requires the skier's body
participation and skill to a degree not experienced while driving a
snowmobile or other motorized vehicle.
Thus, a power driven ski opens to the skier the entire snow covered
outdoors, and specifically the flat northern regions of the United
States such as the Midwest region, to scout and enjoy in a new and
exciting way.
SUMMARY OF DISCLOSURE
Briefly, a power driven ski is produced by combining an anterior
ski portion with a traction unit comprising a posterior ski portion
and a power driven endless tread circulateably supported thereon.
It is important to combine the anterior ski portion with a traction
unit having certain features (which will be discussed herein
shortly) so that the resulting power driven ski as a whole will
achieve the object of the present invention which is:
To provide the skier with a unit that is worn on the foot and
functions on the snow as a conventional ski, having a
longitudinally smooth undersurface substantially throughout its
length as a conventional ski, for enabling the experienced skier to
execute the full range of skiing maneuvers from straight line
skiing, snow plowing and edging to christie and stem turns) while
giving the skier, at the same time, the freedom to ski on flat and
hilly terrain (uphill or downhill) at a speed and direction of his
choice.
The features which are required of the traction unit, in addition
to its ability to propell the skis and skier in order for the ski
as a whole to achieve the above object, are as follows:
To have a longitudinally smooth snow contacting, stationary
undersurface throughout its length,
To generate a minimal lateral reaction from the snow with the tread
even when sliding laterally,
To laterally support and shelter the tread so it is both functional
and undisturbed by such lateral movement of the ski relative to the
snow, (such lateral movement occurs extensively during turning and
braking maneuvers),
to offer minimal resistance to powerless coasting or downhill
skiing, and to be light and compact.
These and other features of the invention will be further discussed
and illustrated with reference to the FIGURES in the following
paragraphs.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a general side-view of a preferred embodiment of a power
driven ski in its free position,
FIG. 2 is a sectional side-view of a posterior portion of the power
driven ski shown in FIG. 1,
FIG. 3 is a sectional view of the power driven ski taken along the
line 3--3 marked on FIG. 2, with the tread removed,
FIG. 4 is a sectional view of the power driven ski taken along the
line 4--4 marked on FIG. 2,
FIG. 5 is a sectional view of the power driven ski taken along the
line 5--5 marked on FIG. 2, with the tread removed,
FIG. 6 is a sectional view of a modified embodiment of a power
driven ski taken on a plane which is orientated relative to the
modified embodiment as the plane of FIG. 4 is orientated relative
to the preferred embodiment, and
FIG. 7 is a general side view of a power driven ski in use.
DETAILED DESCRIPTION OF THE FIGURES
A preferred embodiment of a power driven ski 10 (shown in FIGS. 1
to 5) comprises:
A ski 11 having an aperture 12 which divides it to anterior and
posterior ski portions 13 and 14, respectively, which are held (and
positioned) one to the other by a bridge 15, so that the
longitudinally smooth anterior and posterior undersurfaces 16 and
17, respectively, unite to jointly form a longitudinally smooth
snow contacting, stationary (relative to the ski, as in a
conventional ski) skiing undersurface substantially (that is,
neglecting the relatively small gap in the area of the aperture)
throughout the length of the ski.
Conventional binding means which are located at the rear part of
the anterior ski portion having; a front anchor 46, rear anchors 49
(one shown), a lever 47 and a cable 48 are provided for attaching
the ski 11 to a skier's foot through a boot 45.
An endless tread 18 having at least one tension carrying member 19
in the form of a roller chain containing attachment links to which
outwardly protruding cleats 20 are attached for thrusting against
snow pre-packed by the anterior undersurface 16 and on which the
posterior undersurface 17 slidingly bears and thereby maintains
packed, circulateably supported around the posterior ski portion
14.
Means for circulateably supporting the tread 18 consisting of; a
drive sprocket 26 coupled to a shaft 24 which is in turn being
rotateably supported by the bridge 15 through ball-bearings 50,
which are affixed to the shaft with a snap ring 51, and an idler
assembly 33 having a sprocket 35 which is rotateably supported
through a needle-bearing 37 and a shaft 36 on a piston 34 which is
slideably disposed in a bore at the rearend of the posterior ski
portion 14.
Motor means 21 which incorporate a centrifugal clutch and which is
adapted to be carried by the skier on his back or hip area is
coupled to the tread 18 through a flexible shaft 22 and a right
angle gear box 23 for circulating the tread 18. Optionally the
motor 21 can be mounted directly on the bridge 15 in which case a
chain and sprockets drive may replace the flexible shaft 22 and the
gear box 23.
A one-way clutch 25 formed in the hub of the sprocket 26 couples it
to the shaft 24 and permits the free circulation of the tread 18
during powerless coasting or downhill skiing. Further, the one-way
clutch 25 prevents the motor 21 from braking the tread and throwing
the skier off balance forwardly when the motor 21 suddenly slows
down due to some malfunction or due to a sudden release of the
motor's throttle which is normally controlled through an assembly
comprising a trigger mechanism 61 attached to one of the ski poles
62 which is connected to the motor 21 through a flexible cable 60
by the skier's hand (note FIG. 7).
The engagement of the one cleat 20 with snow near the front of the
posterior undersurface 17 is sequenced out of phase with the
disengagement of another one of the blades 20 near the rear of the
posterior undersurface 17 to prevent the torque peaks that the
engagement and disengagement imposes on the motor 21 through the
shaft 22 from accumulating at one point in time.
The tread 18 circulates from above to below the posterior ski
portion through the aperture 12, over the front sprocket 26 which
has a first pitch-line radius, and thereafter over an arched ramp
43 having a substantially larger pitch-line radius 44 (although not
necessarily a constant radius) for guiding the cleats in a
downwardly direction on an arc into a gradual engagement with the
snow. The reason for the arched ramp feature can be best understood
by looking at the process by which the cleat engages the snow.
The snow which is exposed to the cleat through the aperture has
been pre-packed by the passage of the anterior undersurface 17 over
it, and often, due to common weather processes, it is covered by an
icy crust. As the tread 18 circulates over the sprocket 26, its
various portions assume a speed which is proportional to the radius
along which they swing. For example, if a tip 41 of the cleat 20
swings on a radius which equals twice the pitch-line radius of the
sprocket 26, its speed will double relative to the speed of the
chain 19 (which is also the speed that the cleats 20 and their tip
41 assume as they sweep along the straight part of the posterior
undersurface 17). In addition, as simple geometrical considerations
would indicate, if the cleat will become engaged with the snow
while it is still passing over the sprocket 26, then its generous
frontal area 42 will be forced into the snow rather than its sharp
tip 41. Such a process of engaging the cleat 20 with the snow by
forcing its frontal area 42 into it while the cleat 20 moves
momentarily at an increased speed (i.e., reduced leverage) imposes
a torque peak on the motor 21. This torque peak represents a power
loss and gives start-ups from standing still an erratic
"stick-slip" characteristic.
One remedy to correct the above mentioned problem would be to
substantially increase the front sprocket's diameter, but this
would have several obvious drawbacks such as making the power
driven ski much more cumbersome and heavy, especially in cases
where the engine is mounted directly on the bridge 15 above the
sprocket 26 (as one may optionally mount the engine). Further, a
power driven ski with a large drive sprocket would tend to
translate flexing of the posterior ski portion 14 into a
substantial change in the length of the chain 19 on one hand, and
cause artificial flexing of the posterior ski portion 14 on the
other hand. Thus, substantial enlargement of the sprocket 26 would
negatively change the characteristics of the power driven ski.
In order to obtain the improvement that a large sprocket would
offer to the engagement process while avoiding its above discussed
structural penalties, a combination of a small sprocket 26 followed
by an arched ramp 43 is employed. With this arrangement, the cleat
20 accomplishes the majority of the turnover on the front sprocket,
but as the cleat 20 starts to effectively engage the snow it
becomes guided along the arched contour of the ramp 43 over which
the cleats' turning process becomes slower. Thus, during the
critical cleat 20-snow engagement stage, the cleat 20 moves as if
it were turning over a larger sprocket than the sprocket 26
actually is (It should be noted that the arched ramp 43 structure
is used in this invention to smoothen out the engagement process of
the protruding cleats 20, and not for obstacle negotiating. To
negotiate obstacles, the power driven ski employs a curved portion
at its very front section, as in regular skis and other tracked and
gliding vehicles).
To further refine the graduality of the cleats' engagement with the
snow, their tip can be shaped to avoid a line contact with the snow
surface, but to replace it with a point or points contact by
shaping the cleats' tip to form a line which is not parallel to the
posterior undersurface 17, as shown in FIG. 4, where the Cleat's
tip 411 has a flat v shape and the next cleat behind it has a tip
412 with an inverted v shape.
It should be pointed out that during the disengagement process,
similar geometrical considerations that were discussed above would
make a large rear sprocket, or a combination of a second arched
ramp ahead of the rear sprocket 35, useful. However, disengaging
from the snow is a process which offers less resistance than the
engagement process during which further packing of packed snow
downwards occurs. Also, the chain 19 carries maximum tension forces
as it passes over the rear sprocket 35, while it carries minimal
tension forces when passing over the arched ramp 43. Thus, the
frictional forces between the rear arched ramp would be several
times higher than they are over the front arched ramp 43.
Therefore, while its a designer's option to incorporate a rear
arched ramp, it is pointed out that the ratio between improvement
in performance to the structural and power loss penalties that a
rear ramp structure represents is less favorable in the case of the
rear arched ramp versus a front one.
As explained in Thompson's U.S. Pat. No. 3,710,881 (which was
previously incorporated by reference) it is important to
effectively energize the posterior ski portion against the snow in
order to prevent the snow from being blown away and to obtain
forward thrust from the snow. For this purpose, a dihedral angle of
less than 180.degree. between the anterior and posterior ski
portions is called for by Thompson. In the present invention, as
shown in FIG. 1, the posterior ski portion undersurface 17 can be
stepped (lowered) downwards relative to the anterior ski portion
undersurface 16, forming a step which is indicated by numeral 55,
to improve the above mentioned energization of the undersurface 17
against the snow. This optional modification can be used together
with, or without, Thompson's dihedral angle of less than
180.degree..
As the cleats 20 engage the snow they erect into it on their rear
tip which is bent to form a sliding bearing 52 throughout the width
of the cleat thereby causing the chain to assume a zig-zag
configuration as viewed on a plane which is parallel to the chain
19 and perpendicular to the posterior undersurface 17 (note FIG.
2). This zig-zag configuration causes tension forces which are
carried by the chain 19 to negate bending moments imposed on it by
the cleats 20 through connecting links 27 by offering the tension
forces a lever arm 28 (which is slightly smaller than the vertical
distance between the axes of chain hinge pins 29 and 30) to act
on.
At the rear-end of the posterior ski portions, the idler assembly
33 is resiliently floating on a helical compression spring 38 and
thereby permits the chain 19 to assume the above discussed zig-zag
configuration without becoming stretched.
The chain 19 comrpises a series of links (standard links 31,
attachment links 27, and a lock link 32) hinged one to the next by
hinge pins 29 and 30 which permit the pivoting of the chain as
viewed on a plane which is parallel to the chain 19 and
perpendicular to the posterior undersurface 17 enabling the chain
to pass over the sprockets 26 and 35 and over the arched ramp 43,
but this hinging arrangement does resist pivoting of a link
relative to the next as viewed on a plane parallel to the posterior
undersurface 17 which prevents twisting of the cleats (around an
axis passing through the attachment link 27 and perpendicular to
the posterior undersurface 17) due to asymetrical loading of the
cleat.
The chain 19 is longitudinally guided by a channel 39 while passing
under the posterior ski portion 14. The channel 39 is formed in the
posterior undersurface 17 for guiding the chain 19 between the
sprockets 29 and 35, for sheltering the chain from lateral movement
between the ski 11 and the snow which occurs extensively during
turning and braking maneuvers, and for supporting the chain
(slightly ahead and slightly behind the attachment link 27 on
alternating sides) when the chain resists the previously discussed
tendency of the cleats to twist due to asymetrical loading and
tries to cause the chain to assume a zig-zag configuration as
viewed on a plane which is parallel to the posterior undersurface
17.
A general view of a power driven ski 10 is shown in FIG. 7. It
should be noted that in order to maximize traction capability a
skier may wear a pair of power driven skis, however, a combination
of a power driven ski on one foot and a conventional ski on the
other foot provides adequate traction for negotiating a wide range
of topographical and snow conditions, and since this combination is
substantially simpler in terms of hardware, it is deemed a
preferred arrangement at least for leisure type usage of the power
driven ski. Further, by favoring the foot wearing the power driven
ski in distributing his body's weight, the skier can overcome spots
where increased traction is required, such as when starting from
stand still on a steep hill, etc.. It may be further noted that as
soon as the skier gathers speed the skis glide on the snow with
minimal resistance.
A modified embodiment of the present invention (shown in FIG. 6)
where an endless tread 118 has two tension carrying members in the
form of chains 119 which contain attachment links 127. The chains
move adjacent to and obtain longitudinal guidance and sheltering
from the sides of the posterior ski portion 114. The tread 118
tends to be heavier and more expensive to fabricate than the tread
18 of the preferred embodiment, however, it negates twisting of the
cleats 120 around a vertical axis effectively with its tension
carrying capacity. Therefore, the modified embodiment should be
given consideration for certain applications in which the cleats'
frontal area 142 is being repeatedly subjected to asymetrical
loading. It should be noted that the traction unit of the modified
embodiment has a longitudinally smooth undersurface 117 (which is
an essential prerequisite of any traction unit that is to be used
in a power driven ski according to the present invention).
It is obvious that modifications and substitutions can be made in
the power driven ski wthout departing from the spirit and the scope
of my invention.
* * * * *