Note: Descriptions are shown in the official language in which they were submitted.
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LENGTH ADJUSTMENT MECHANISM FOR A STRAP
Field of the invention
The invention relates to a length adjustment mechanism for a strap.
Background of the invention
U.S. Patent 3,214,809 issued to Edwards on December 20, 1963 discloses a
length
adjustment mechanism for a strap having overlapping portions. U.S. Patent
5,950,245
issued to Binduga on September 14, 1999 discloses an adjustable headband
comprising
a ratchet mechanism having different resistances.
Although these prior art adjustable mechanisms allow adjusting the length of a
strap
when desired by the user while normally preventing undesirable movement of the
strap,
such movement is nevertheless possible when the force applied to the strap
exceeds a
certain level.
Against this background, there is a need in the industry for a mechanism that
allows the
length of the strap to be easily adjusted by the user while preventing or at
least reducing
the possibility of unwanted loosening or tightening of the strap.
Summary of the Invention
As embodied and broadly described herein, the invention seeks to provide a
length
adjustment mechanism for a strap having a row of teeth. The mechanism
comprises a
pinion for meshing with the row of teeth and a finger operable actuator
pivotable in a first
direction and in a second direction. The mechanism also comprises a pivoting
link
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coupled to the pinion, the pivoting link being pivotable about a first pivot
axis to impart a pivotal
movement to the pinion and a rotating element coupled with the finger operable
actuator. The
rotating element is pivotable about a second pivot axis and engages the
pivoting link in a driving
relationship such that movement imparted to the finger operable actuator is
communicated to the
pinion via the rotating element and the pivoting link to displace the row of
teeth. When a force is
applied to the pinion tending to pivot the pivoting link, the pivoting link
and the rotating element
interlock for resisting pivotal movement of the pivoting link
Brief descrigtion of the drawings
A detailed description of the preferred embodiments of the present invention
is provided herein
below, by way of example only, with reference to the accompanying drawings, in
which:
Figure 1 is a perspective view of a strap having a length adjustment mechanism
constructed in
accordance with a first embodiment of the invention;
Figure 2 is a perspective exploded view of the mechanism of Figure 1;
Figure 3 is an elevational exploded view of the mechanism of Figure 2;
Figure 4 is a perspective enlarged view of the mechanism, the finger operable
actuator of the
mechanism being omitted;
Figure 5 is a plan view of the mechanism of Figure 4, arrows showing
directions in which
components pivot;
Figure 6 is a plan view of the mechanism of Figure 4, arrows showing forces
acting between the
pivoting link and pinions;
Figure 7 is a perspective view of a ski boot having straps with a length
adjustment mechanism
constructed in accordance with a second embodiment;
Figure 8 is a perspective exploded view of the mechanism of Figure 7;
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Figure 9 is an elevational exploded view of the mechanism of Figure 8; and
Figure 10 is a perspective view of a helmet having a headband with a length
adjustment
mechanism constructed in accordance with the first embodiment.
In the drawings, embodiments of the invention are illustrated by way of
examples. It is to be
expressly understood that the description and drawings are only for the
purpose of illustration and
are an aid for understanding. They are not intended to be a definition of the
limits of the invention.
Detailed description of embodiments
Figures 1 to 6 show a length adjustment mechanism 1 constructed in accordance
with a first
embodiment of the invention, mechanism I being mounted on a strap 10 for
adjusting the length
of the strap 10.
Strap 10 comprises first and second overlapping portions 12 and 14.
Overlapping portions 12 and
14 have respective first and second elongated slots 16 and 18 with opposite
first and second rows
of teeth 20 and 22. Elongated slots 16 and 18 are in general alignment.
Mechanism 1 comprises a pinion 24 having teeth meshing with first and second
rows of teeth 20
and 22. Pinion 24 is coupled to a pivoting link 26. A disc 28 is provided
between pinion 24 and
pivoting link 26. Preferably, pinion 24, pivoting link 26 and disc 28 are
integrally formed. Thus,
pinion 24, pivoting link 26 and disc 28 are pivotable about a first pivot axis
Al and pivoting link
26 imparts a pivotal movement to pinion 24 (and disc 28).
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It is understood that it is not essential that disc 28 pivots and be
integrally formed with
pinion 24 and/or pivoting link 26. While pinion 24 is coupled to pivoting link
26 and
pivots about first pivot axis Al, it is also understood that this pinion may
pivot about
another pivot axis or may be coupled to pivoting link 26 via another driving
component
which pivots about first pivot axis Al.
Pivoting link 26 comprises first and second surfaces 30, 32 that define
therebetween an
angle less than 180 , and third and fourth surfaces 34, 36 that also define
therebetween
an angle less than 180 .
Mechanism 1 further comprises a finger operable actuator 38 having a gripping
portion
40 for allowing a user to turn the finger operable actuator 38 in a first
direction Dl or in
a second direction D2 that is opposite to direction Dl. Finger operable
actuator 38 also
comprises first and second lugs 42, 44 projecting downwardly and engaging
respective
second and third satellite rotating elements 46, 48 in order to communicate
movement
of finger operable actuator 38 to rotating elements 46, 48. In the illustrated
embodiments,
rotating elements 46, 48 are formed of pinions but it is understood that other
types of
rotating elements can be used without departing of the scope of the present
invention.
Second rotating element 46 is pivotable about a second pivot axis A2 and third
rotating
element 48 is pivotable about a third pivot axis A3. Second rotating element
46
comprises a first circular section 46T having teeth anci a second circular
section 46S
being free of teeth. Similarly, third rotating element 48 comprises a first
circular section
48T having teeth and a second circular section 48S being free of teeth.
Mechanism 1 further includes a casing 50 having an elongated aperture 52 for
receiving
overlapping portions 12, 14. Casing 50 has a ring gear 54 with an annular
peripheral
projection 56 having an internal surface 58 from which originate the teeth of
the ring
gear. As shown on Figures 2 and 5, the diameter of disc 28 is substantially
identical to
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the diameter of ring gear 54 and fits in the peripheral projection 56 in order
to properly
support rotating elements 46, 48 that are located above disc 28.
Referring now more specifically to Figures 4 to 6, teeth of first circular
sections 46T, 48T
of second and third rotating elements 46, 48 mesh with ring gear 52, while the
second
circular section 46S of the second rotating element 46 contacts the first and
second
surfaces 30, 32 of pivoting link 26. Similarly, the second circular section
48S of third
rotating element 48 contacts the third and fourth surfaces 34, 36 of pivoting
link 26.
Second and third rotating elements 46, 48 are therefore frictionally engage
with pivoting
io link 26 in a driving relationship such that pivotal movement of finger
operable actuator
38 is communicated to pinion 24 via rotating elements 46, 48 and pivoting link
26,
causing first and second overlapping portions 12, 14 to be displaced in
opposite
directions to either loosen or tighten the strap 10.
More specifically, when the finger operable actuator 38 is turned by hand, the
motion
imparts opposite pivotal movement to second and third satellite rotating
elements 46, 48
about the second and third pivot axes A2, A3, respectively. Since the teeth of
first
circular sections 46T, 48T mesh with ring gear 54, satellite rotating elements
46, 48 also
pivot in an orbital fashion about first pivot axis Al in the same direction as
finger
operable actuator 38.
Furthermore, since a portion of second circular section 46S contacts a portion
of first and
second surfaces 30, 32 of pivoting link 26 and a portion of second circular
section 48S
contacts a portion of first and second surfaces 34, 36 of pivoting link 26,
the orbital
pivotal movement of rotating elements 46, 48 imparts a pivotal movement to
pivoting
link 26 about the first pivot axis Al.
As pivoting link 26 is coupled to pinion 24, the pivotal movement of the
pivoting link 26
imparts pivotal movement of pinion 24 in order to displace first and second
overlapping
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portions 12, 14 in opposite directions. Thus, pivotal movement of finger
operable
actuator 38 in one direction tightens the strap 10 by moving the overlapping
portions 12,
14 toward one another. Conversely, the pivotal movement of the finger operable
actuator
38 in the opposite direction loosens the strap 10 by moving the overlapping
portions 12,
14 away from one another.
When a force is applied on the strap 10 for loosening or tightening it, such
as when the
overlapping portions 12, 14 are pulled away or pushed toward one another, the
teeth 20,
22 tend to impart a turning movement to pinion 24 and to pivoting link 26.
However, the
driving relationship between the satellite rotating elements 46, 48 and
pivoting link 26
is unidirectional such that the satellite rotating elements 46, 48 and the
pivoting link 26
interlock, thus preventing the any one of the rotary components (finger
operable actuator
38, satellite rotating elements 46, 48, pivoting link 26 and pinion 24) from
turning.
In other words, relative movement between the overlapping portions 12, 14 of
strap 10
is precluded when a force is applied to pinion 24 tending to drive pivoting
link 26. A
turning force imparted on pivoting link 26 by the pivot 24 is transmitted to
satellite
rotating elements 46, 48. The forces acting on the satellite rotating elements
46, 48 are
shown at F 1 and F2 in Figure 6. The geometry of the various parts is such
that forces Fl
and F2 intersect the respective pivot axes of the satellite rotating elements
48, 48, thus
interlocking the mechanism.
Figure 8 shows a length adjustment mechanism 100 constructed in accordance
with a
second embodiment of the invention, mechanism 100 being mounted on a strap
110.
Mechanism 100 for adjusting strap 110 is identical to that of mechanism 1, and
the only
difference resides in the construction of the strap 110 that has a single part
112 including
a row of teeth 114 that can be moved forward or backward such as to tighten or
loosen
the strap 110.
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It will become apparent to a person skilled in the art that the mechanism of
the present invention
may be used for adjusting the length of a strap in a wide variety of
applications, such as the strap
forming the headband on a helmet. In fact, the headband may comprise an
adjustable strap having
the length adjustment mechanism 1. For example, as illustrated in Figure 1 and
10, strap 10 may
be part of a headband. Moreover, as illustrated in Figure 10, a helmet may
comprise the headband.
The mechanism of the present invention may also be used for adjusting the
length of a strap for
fastening footwear as illustrated in Figure 7.
The above description of preferred embodiments should not be interpreted in a
limiting manner
since other variations, modifications and refinements are possible within the
spirit and scope of
the present invention. For example, friction drive rollers may replace the
various pinions of the
mechanism. Also, instead of using a pair of satellite pinions 46, 48, a single
satellite pinion can
be used. The scope of the invention is defined in the appended claims and
their equivalents.
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