Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Sash balances – Spring
Reexamination Certificate
1999-01-21
2001-07-24
Mah, Chuck Y. (Department: 3626)
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Sash balances
Spring
C016S197000, C160S191000
Reexamination Certificate
active
06263541
ABSTRACT:
FIELD OF THE PRESENT INVENTION
The present invention relates to a winding cone for a torsion spring and, in particular, to a winding cone used in a torsion spring assembly of an overhead door counterbalancing mechanism.
BACKGROUND OF THE PRESENT INVENTION
A conventional winding cone includes both a frusto-conical surface for receiving and retaining an end of a torsion spring and a base having an opening therein for receiving a set screw whereby the end of the spring is fixed to a torsion rod extending axially through the winding cone. With this type of winding cone, the force of the spring does not have to be overcome prior to releasing the set screw. The set screw can simply be released without regard to the torque of the torsion spring on the winding cone. Consequently, an inexperienced person often will release the set screw without sufficiently bracing against the torque of the torsion spring thereby leading to unexpected and rapid unwinding of the torsion spring and possible injury. A need therefore exists for a failsafe whereby the torque of the torsion spring must first be overcome before the securement of the torsion spring to the torsion rod by the set screw can be released.
Balk U.S. Pat. No. 5,671,500 is illustrative of a conventional torsion spring assembly used in a counterbalancing mechanism for an overhead door. The torsion spring
3
is axially disposed about torsion rod
20
. One end of the spring is retained by cone
16
that is mounted to the rod
20
by adjustable mounting
18
, and the other end of the spring is retained by cone and bracket
12
which are rotationally fixed relative to rod
20
. Rotation of rod
20
causes rotation of mounting
18
, cone
16
, and torsion spring
3
leading to a change in the tension of the torsion spring
3
. The tension range is adjusted by: first releasing a set screw which fixes mounting
18
to rod
20
; next rotating mounting
18
, cone
16
, and spring
3
relative to the rod
20
in the desired direction; and then re-engaging the set screw with the rod
20
through the mounting
18
. No failsafe is provided to insure that the tension in torsion spring
3
will be maintained when the set screw is released from torsion rod
20
.
With more particular detail to the conventional structure of a winding cone itself, Martin U.S. Pat. No. 4,817,927 discloses in
FIG. 4
a winding cone
60
and, in
FIG. 3
, an anchor cone
10
. A tool (not shown) is inserted into apertures
68
or
69
for selectively adjusting the tension in the torsion spring
50
and set screws are provided through aperture
64
in base
62
for mounting the winding cone to the torsion rod
34
. Martin provides markings on the winding cones to indicate which direction each cone should be rotated to wind the torsion spring
50
. Similarly, Kalister U.S. Pat. No. 3,779,537 discloses a winding cone and winding base that includes both left-hand and right-hand threads for receiving either a left-hand or right-hand wound spring. Similar to Martin, the winding cone is secured to the torsion rod by set screws. The winding cones of both of these references fail to provide a failsafe for insuring that the torque of the torsion spring is adequately braced against when the winding cone is released from the torsion rod for winding of the torsion spring.
Apart from the structure of a torsion spring assembly or a winding cone, Way U.S. Pat. No. 5,605,079 actually relates to a device for rotating the winding cone and winding the torsion spring for increasing winding tension. In particular, Way discloses a housing that is mountable to a winding cone to which ratchet arms are attachable for increasing the tension in the torsion spring. In using the device, a ratchet arm must be braced to counteract the force of the torsion spring that is released when the set screw is removed. In Way no failsafe is provided whereby the spring force must first be overcome before disengagement of the set screw. In fact, the opening
66
by which the set screw is accessible is continuously aligned with the set screw
34
and the housing
36
in which the opening is formed is fixed to the winding cone. Thus, the set screw is continuously accessible in the device of Way.
The prior art also includes devices for adjusting the operating tension range in a torsion spring assembly which does not involve the rotation of the winding cone relative to the torsion rod and, thus, does not include the dismounting of the winding cone from the torsion rod to which the failsafe of the present invention relates. Such devices are disclosed, for example, by Davis U.S. Pat. No. 4,882,806; Carper et al. U.S. Pat. Nos. 5,636,678 and 5,632,063; and Husselton U.S. Pat. No. 5,239,777. None of these mechanisms relate to the winding of the torsion spring by rotation of the winding cone relative to the torsion shaft, nor do they provide a safeguard against an inadequate force bracing against the release of the torsion spring tension.
Looking beyond overhead doors to the art of spring hinges, a few references relate to the adjustment of the tension in torsion springs thereof. In Rapp U.S. Pat. No. 4,817,242, a spring hinge for a toilet seat is disclosed wherein the tension in the torsion spring is adjustable. Specifically, Rapp discloses, with relevance to the present invention, a torsion spring
2
axially disposed about a rod
1
within a hinge. A first end of the torsion spring
2
is secured to end cap
9
and a second end of the torsion spring is secured to a first coupling member
6
that is mounted to the rod
1
and that has teeth which interlock with a second coupling member
5
. End cap
9
is mounted to the toilet and second coupling member
5
is mounted to the seat. The first coupling member
6
, and the second coupling member
5
, when interlocked therewith, are rotational with the rod
1
relative to end cap
9
, which rotation increases and decreases the tension in torsion spring
2
within a certain range. This range of tension is adjusted by: first axially moving the first coupling member
6
away from the second coupling member
5
into an unlocked position by axially displacing rod
1
against the spring force via knob
8
thereby compressing the spring; then rotating the first coupling member
6
and the spring
2
attached thereto relative to the second coupling member
5
by rotating rod
1
via knob
8
; and then moving the first coupling member
6
back into interlocking relation with the second coupling member
5
by releasing the knob
8
.
Curry et al. U.S. Pat. No. 4,073,038 discloses a spring hinge in which the torsion spring
23
biasing the hinge has a selectable tension range. In particular, torsion spring
23
is retained between cone
22
fixed to hinge
12
via set screw
35
, and cone
24
coupled to plug
20
which, in turn, is fixed to hinge
11
via set screw
32
. The coupling between cone
24
and plug
20
is accomplished through mating engagement surfaces
26
,
27
. When the tension range is to be adjusted, a wrench
29
is inserted through an opening in the plug
20
into an opening
28
in cone
24
. Due to the contoured engagement surfaces
26
,
27
, rotation of the wrench about the axis of the torsion spring
23
in a first direction will cause the cone
24
and plug
20
to rotate relative to one another in segmented increments. However, the contoured engagement surfaces
26
,
27
prevent the rotation of the cone
24
and plug
20
in the segmented steps in the opposite direction unless the cone
24
and plug
20
are separated by an axial force applied directly to the cone
24
via the wrench
29
.
Hwang U.S. Pat. No. 5,048,155 discloses a spring hinge in which the torsion spring biasing the hinge has an adjustable tension range. In particular, torsion spring
30
is retained between end cap
50
, secured to a first hinge by set screw
90
, and end cap
40
secured to a second hinge by set screw
70
. A number of openings are formed in the second hinge member
10
and, in particular, in knuckle
12
in which the end cap
40
is disposed, through which set screw
70
can e
Kennedy Covington Lobdell & Hickman LLP
Mah Chuck Y.
Windsor Door, Inc.
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