Note: Descriptions are shown in the official language in which they were submitted.
CA 02278876 1999-07-26
Title: LOCK MECHANISM FOR FOLDING LEG
FIELD OF THE INVENTION
This invention relates to the field of folding support legs.
BACKGROUND OF THE INVENTION
Some prior art folding table legs comprise an articulated cross-
support mechanism which spans between the leg and the underside of the
tabletop. Often, the cross-support mechanism has a hinge in its middle
which permits it to fold back upon itself when the leg is collapsed against
the tabletop, but which is designed to prevent the cross-support from
pivoting much past 180 at its full extension, when the leg is erected.
These cross-supports maintain their spanning strength through the use of
gravity or some form of friction lock which works to keep the cross-
support extended. Such support legs tend to be flimsy and easily collapsed
by accident once erected.
Alternatively, some cross-support mechanisms are locked in their
extended position through the use of a locking pin. While such
mechanisms tend to be more secure in maintaining the leg in its erect
position, the locking pins are frequently difficult to use. If the pin is
lost,
the table leg is rendered unusable until a replacement is found.
Frequently, the locking pins are attached to the table through the use of a
lengthy chain, which can become tangled when the table leg is collapsed.
Other devices have been developed to improve the stability of the
collapsible legs, and to lock them in the erect position. However, such
designs tend to be complex, both from the manufacturing standpoint, and
from the user's perspective.
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Additionally, many collapsible table leg designs fail to provide a
retention device for maintaining the table leg in its collapsed position. In
order to keep the legs from extending and becoming obstructive, it is
typically necessary to ensure that the table is transported and stored in an
upside-down position.
Accordingly, it has been recognized that there is a need for a
collapsible table support mechanism, which is sturdy, simple to use, and
which is capable of locking the support in both its collapsed and extended
positions.
SUMMARY OF THE INVENTION
The present invention is directed towards a collapsible support
mechanism, which has common, but by no means exclusive application to
folding table legs.
The lock system of the present invention is for releasably locking a
first component, pivotally coupled along a pivot axis to a second
component, in a plurality of positions fixed relative to the second
component. The system has a first engaging mechanism fixed to the first
component and aligned with the pivot axis such that it rotates in a
rotation plane substantially perpendicular to the pivot axis when the first
component is pivoted relative to the second component. The system also
has a second engaging mechanism pivotally mounted to the second
component and movable between an engaged position in which the
second engaging mechanism fixedly engages with the first engaging
mechanism, preventing the first component from pivoting relative to the
second component, and a disengaged position removed from the first
engaging mechanism wherein the first component is free to pivot relative
to the second component.
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BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described, by way of example
only, with reference to the following drawings, in which like reference
numerals refer to like parts and in which:
Figure 1 is a bottom plan view of a locking mechanism
manufactured in accordance with the subject invention, in which the
support is locked in a collapsed position;
Figure 1A is a side sectional view of a hinge knuckle of the locking
mechanism in Figure 1;
Figure 1B is an overhead view of the engaging bar and spring in
Figure 1, with portions of the hinge mechanism removed;
Figure 2 is a side, close-up view of the locking mechanism of Figure
1, in which the support is locked in a collapsed position;
Figure 3 is a bottom perspective, close-up view of the locking
mechanism of Figure 1, in which the lock mechanism is disengaged, and
the support is in the collapsed position of Figure 2;
Figure 4 is a side, close-up view of the locking mechanism of Figure
1, in which the support is locked in an erect position;
Figure 5 is a bottom perspective, close-up view of the locking
mechanism of Figure 1, in which the lock mechanism is disengaged, and
the support has been moved between the collapsed position of Figure 2
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and the erect position of Figure 4;
Figure 6 is a side, close-up view of an alternate locking mechanism
of the subject invention, in which the plate of the first engaging
mechanism is substantially pentagonal in shape;
Figure 7 is a side, close-up view of an alternate locking mechanism
of the subject invention, in which the plate of the first engaging
mechanism is substantially hexagonal in shape;
Figure 8A is a side view of a table comprising collapsible legs
utilizing the locking mechanism of Figure 1, in which the legs are locked
in an erect position;
Figure 8B is a bottom perspective view of the table of Figure 8A, in
which the legs are locked in a collapsed position;
Figure 9 is a side view of a collapsible table wing comprising a
locking mechanisms manufactured in accordance with the subject
invention, in which the table wing is locked in an extended, in use
position; and
Figure 10 is a side view of a drafting table comprising collapsible legs
utilizing the locking mechanism of Figure 7, in which the tabletop is
locked in a position between the horizontal and vertical.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring simultaneously to Figures 1 and 2, illustrated therein is a
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lock system, shown generally at 10 and made in accordance with a
preferred embodiment of the subject invention. Lock system 10 comprises
a first component 12, pivotally coupled to a second component 14 through
the use of a hinge mechanism 16, and a locking mechanism 17. The first
component 12 is shown locked in its collapsed position.
Typically, the first component 12 is a support member, such as a
table leg, and correspondingly, typically the second component 14 is a
tabletop. Preferably, the first component 12 comprises a main stem 18 (eg.
a tube) having a base stabilizing member 20, which provides lateral
stability when in contact with the floor when the leg is in its erect
position.
Base member 20 may also comprise adjustable feet 22, which may be
screwed in and out for height adjustment with respect to the base member
20, for optimal contact with the floor, as will be understood by one skilled
in the art. In the example shown, main stem 18 is of tubular metal
construction, typically cylindrical in shape, through which the base
member 20, also typically of tubular metal construction, has been passed.
The hinge mechanism 16 comprises a support plate 24 which is
mounted to the underside of the tabletop 14, typically through the use of
mounting screws 26. Hinge knuckles 28 are typically welded to the support
plate 24, and comprise a U-shaped portion 30, within which tube segment
32 has been mounted (Figure 1A). Tube segment 32 is sized to slidably
receive hinge pin 34 (which also may be tubular). Hinge pin 34 is fixedly
mounted through the main stem 18, typically through welding the two
components together. Hinge pin 34 is aligned to pivot about a pivot axis
36, shown by the dotted line. The periphery of hinge pin 34 is spaced by
distance D (Figure 1A) from the adjacent surface of plate 24, for a purpose
which will become apparent.
The locking mechanism 17 comprises a first engaging mechanism
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38, typically a substantially square metal locking plate, which is fixed (eg.
by
welding) to one end of the hinge pin 34. The locking plate 38 is centrally
aligned to substantially rotate about the pivot axis 36, in a rotation plane
40, represented by a dotted line, which is substantially perpendicular to the
pivot axis 36 and to the paper on which Figure 1 is printed. The locking
mechanism is shown in Figures 1 and 2 in its engaged or locked position.
The locking mechanism 17 also comprises a second engaging
mechanism 42, typically a substantially rectangular bar, which is pivotally
mounted to the support plate 24 through the use of a screw 44 extending
through a hole in the bar 42. The hole in the bar 42 is sized to permit the
bar 42 to freely pivot about the screw 44, while pivotally fixing the bar 42
to
the support plate 24. Preferably, the locking mechanism 17 also includes a
U-shaped biasing spring element 46, mounted to the nearest hinge
knuckle 28. A reinforcing pin 47 (see also Figure 1B) may also be provided,
mounted to the support plate 24 and positioned on the interior of the
spring 46, with the spring 46 passing between the pin 47 and the nearest
knuckle 28 and then bent at 49 against the inside of U-shaped member 30.
The spring 46 is sized to fit around the pivoting end of the bar 42, and has a
free, flexing arm 48, which maintains biasing force against the bar, urging
it towards the nearest knuckle 28.
The bar 42 is positioned in the gap 43 (Figure 2) between the locking
plate 38 and the support plate 24. Gap 43 is part of the distance D shown in
Figure 1A. In this engaged position, the bar 42 prevents the locking plate
38 from rotating to any substantial degree, and thereby locks the table leg 12
in its collapsed position.
Referring now to Figure 3, the table leg 12 is shown in the collapsed
position of Figure 2. A user has exerted and maintained counter force
against the biasing force of the flexing arm 48 of the spring 46 and flexed it
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outward, by pivoting the free end of the bar 42 outward in the direction of
the arrow, away from the nearest hinge knuckle 28, and out of the gap 43.
As a result, the locking mechanism 17 is disengaged or unlocked, and the
table leg 12 is freed to rotate towards a vertical, erect position.
In Figure 4, the table leg 12 has been rotated approximately 90 to its
erect position. As a result, the locking plate 38 has correspondingly been
rotated approximately 90 . In the same fashion as was illustrated in Figure
2, the bar 42 is positioned between the locking plate 38 and the support
plate 24, and in this engaged position, the bar 42 again prevents the locking
plate 38 from rotating to any substantial degree. As a result, the table leg
12
is locked in its erect position.
Referring now to Figure 5, the table leg 12 is shown part way
between the collapsed position of Figures 2 and 3 and the erect position of
Figure 4. When in the disengaged position of Figure 5, the table leg 12 has
been rotated toward the vertical. In this position, the bottom corner of the
locking plate 38 has been rotated and projects into the space which had
previously formed the gap 43 in Figure 2. As a result, when the bar 42 has
been released by the user, the spring 46 urges the bar 42 into contact with
the outer surface of the locking plate 38. As shown in Figure 5, the lock
system 10 may also include a peg 50 for preventing over extension of the
spring 46 when the bar 42 is flexed outward by the user.
Once the table leg 12 has been rotated completely into the erect
position of Figure 4, a new gap 43' is formed between the bottom side of
the locking plate 38 and the support plate 24, and the spring 46 urges the
bar 42 to snap into the newly formed gap 43', thereby preventing further
rotation of the table leg 12.
Reference is next made to Figure 6, which shows an alternate
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locking mechanism shown generally as 100. As indicated through the use
of similar reference numbers used in Figures 1 to 5, the various
components of the alternate mechanism 100 are largely identical to those
of the lock system 10. However, the locking plate 38 has been replaced
with metal plate 110 which is substantially pentagonal in shape. As shown
in dotted outline, this configuration permits the first component 12 to be
locked into three different positions with respect to the second component
14, each varying by approximately 72 from the next immediate position.
Referring now to Figure 7, illustrated therein is an alternate locking
mechanism shown generally as 200. As indicated through the use of
similar reference numbers used in Figures 1 to 5, the various components
of the alternate mechanism 200 are largely identical to those of the lock
system 10. However, the locking plate 38 has been replaced with metal
plate 210 which is substantially hexagonal in shape. As shown in dotted
outline, this configuration permits the first component 12 to be locked into
three different positions with respect to the second component 14, each
varying by approximately 60 from the previous position.
While the collapsed position of the first component 12 is illustrated
in Figures 6 and 7 as being essentially parallel to the second component 14,
it should be understood that for certain uses, it may be preferable for the
collapsed position to have the first component 12 at some positive angle
with respect to the second component 14. As will be understood,
providing for different angles in this manner involves fixing the locking
plate 110 or 210 to the hinge pin 34 (not shown in Figures 6 and 7), and
hence to the first component 12 at a different angle than illustrated.
Furthermore, it should be understood that the locking plates 38, 110, 210
may be replaced with locking plates that comprise more than 6 sides.
Additionally, it should be understood the locking plates do not need to be
regular polygons. In general, any appropriately sized and shaped locking
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plate having at least two flat sides at its periphery may be used. Typically,
the larger the number of sides on the locking plate, the greater the number
of adjustable positions available, with smaller angular increments between
consecutive positions.
Referring now to Figure 8A, illustrated therein is a table, referred to
generally as 300 comprising a pair of collapsible legs 310, 312 each utilizing
the locking mechanism of the subject invention. The legs 310, 312 are
shown locked in an erect position. In Figure 8B, the table 300 is shown
with the legs 310, 312 in the collapsed position.
Referring now to Figure 9, illustrated therein is a locking system,
referred to generally as 400, in which a table wing 410 is mounted to the
edge of a tabletop 412 utilizing a mounting mechanism 414 which
comprises components substantially similar to the hinge mechanism 16
and the locking mechanism 17 illustrated in Figures 1 and 2. Instead of the
table leg 12 of Figures 1 and 2, the first component comprises an extension
support 416 which is mounted to the table wing 410 by a U-shaped
mounting bracket 418 which is welded to both the extension support 416
and a mounting plate 420 which, in turn, is screwed or bolted to the
underside of the table wing 410. When not in use, the table wing 410 can
be lowered approximately 90 and locked in a vertical position beneath the
tabletop 412, or if the underside of the tabletop is free from obstruction,
may be swung approximately 180 and locked in a position beneath and
essentially parallel to the tabletop 412. As will be understood, the table
support for the tabletop 412 may comprise fixed table legs, collapsible table
legs (such as the table leg 12 of Figures 1 and 2), or the tabletop may simply
be mounted to and extend from a wall.
Referring now to Figure 10 is the support mounting system 200 of
Figure 7, used on a drafting table, referred to generally as 500. For
stability
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purposes, the table 500 utilizes two, laterally spaced mounting systems 200,
each comprising a support leg 510 fixedly, pivotally mounted to the
underside of the drafting tabletop 512. As will be understood, the tabletop
512 may be locked in several different positions with respect to the support
legs 510, depending on the user's preferences. It should also be understood
that the locking plate 210 can be replaced with any suitably sized and
shaped locking plate, as mentioned previously.
While the various locking mechanisms have been illustrated and
described in conjunction with tables, and generally in conjunction with
table legs, it should be understood that the locking mechanism of the
subject invention may be used for many different purposes in which it is
desirable to pivotally mount one component to a second component, and
be able to releasably lock the first component in position with respect to
the second component.
Thus, while what is shown and described herein constitute
preferred embodiments of the subject invention, it should be understood
that various changes can be made without departing from the subject
invention, the scope of which is defined in the appended claims.
