U.S. patent number 3,756,585 [Application Number 05/179,234] was granted by the patent office on 1973-09-04 for spiral spring counterbalance unit.
Invention is credited to Arthur Mihalcheon.
United States Patent |
3,756,585 |
Mihalcheon |
September 4, 1973 |
SPIRAL SPRING COUNTERBALANCE UNIT
Abstract
A counterbalance unit, for lifting an overhead door, is
provided. The unit includes a flat plate which can be mounted on
the wall adjacent the door. A rigid, fixed, horizontal shaft
extends forwardly from the plate. A pair of united cable drums is
rotatably mounted on the shaft. A spiral spring is also mounted
arund the shaft; the spring's inner end is connected to the drums
and its outer end is connected to a housing. The spring functions
to rotate the drums. The housing can be rotated around the shaft to
tension the spring; however, usually it is locked in a fixed
position. A cable is attached at its inner end to each drum; the
cables extend over pulleys and are attached at their lower ends to
the overhead door. In operation, the spring expands to rotate the
drums, thereby winding up the cables and lifting the door.
Inventors: |
Mihalcheon; Arthur (Edmonton,
Alberta, CA) |
Family
ID: |
22655764 |
Appl.
No.: |
05/179,234 |
Filed: |
September 9, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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870273 |
Nov 5, 1969 |
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Current U.S.
Class: |
267/156; 160/193;
16/78 |
Current CPC
Class: |
E05D
13/1284 (20130101); F16J 1/10 (20130101); Y10T
16/568 (20150115); E05Y 2900/106 (20130101) |
Current International
Class: |
F16J
1/10 (20060101); F16f 001/10 () |
Field of
Search: |
;267/156
;160/193,191,192 ;191/12.2 ;16/78 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Marbert; James B.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation - in - part of my application
for U.S. Pat. Ser. No. 870,273, filed Nov. 5, 1969, now abandoned.
Claims
What is claimed is:
1. A counterbalance unit for an overhead door which closes an
opening in a wall which comprises:
a base, adapted to be mounted on the wall, including a horizontal
shaft adapted to extend forwardly from the wall;
a pair of interconnected drums mounted on the shaft for
simultaneous rotation therearound;
spring-end fixing means associated with the base and adapted to be
rotated around the shaft independent of the movement of the
drums;
means, associated with the base and operatively connected with the
spring-end fixing means, for disengagably locking the spring-end
fixing means to prevent rotational movement thereof; and
a spiral spring, disposed around the shaft; having one end secured
to the normally stationary spring-end fixing means and the other
end operatively connected to the drums for rotation thereof.
2. A counterbalance unit as set forth in claim 1 wherein:
the spring has an outer diameter substantially greater than the
effective diameter of the drums.
3. A counterbalance unit for an overhead door which closes an
opening in a wall which comprises:
a base comprising a vertical, flat plate to be mounted on the wall
and a horizontal shaft extending forwardly from the plate;
a hub mounted rotatably and coaxially on the shaft;
a pair of drums rigidly secured to the hub whereby the drums may be
rotated simultaneously around the shaft;
spring-end fixing means associated with the base and adapted to be
rotated around the shaft independent of the movement of the
hub;
means, associated with the base and operatively connected with the
spring-end fixing means to prevent rotational movement thereof;
and
a spiral spring, disposed around the shaft having its outer end
secured to the normally stationary spring-end fixing means and its
inner end secured to the hub for rotation thereof, said spring
having an outer diameter substantially greater than the effective
diameter of the drums.
4. The counterbalance unit as set forth in claim 3 wherein:
the spring-end fixing means comprises a sleeve, rotatably mounted
on the shaft beneath the hub, and a back member connected with the
sleeve and extending radially therefrom, said back member having a
forwardly extending rim at its outer end, the spring having its
outer end secured to the rim.
5. The counterbalance unit as set forth in claim 4 wherein:
the locking means comprises a lug on the rim and a spring-actuated
member carried by the plate, said spring-actuated member being
adapted to contact the lug to prevent further movement of the
spring-end fixing means in at least one direction.
Description
BACKGROUND OF THE INVENTION
This invention relates to a spiral spring counterbalance unit for
raising an overhead door, such as a sectionalized garage door or
the like.
At the present time, it is usual to counterbalance a sectionalized
door with either an extension spring arrangement or a torsion
spring arrangement.
If the door is light, the extension spring mechanism is used. This
mechanism includes a pair of springs, one extending down beside
each side edge of the door. Each spring is attached at its lower
end to the bottom edge of the door and at its upper end to the
garage wall. When the door is in the latched-down position, the
springs are fully extended. When the door is unlatched, the springs
contract to roll the door up along a pair of tracks.
In the case where the door is heavy, a torsion spring mechanism is
normally used. This mechanism includes a long shaft which is
rotatably mounted along the upper edge of the door. A pair of drums
are mounted on the shaft, one at each end thereof. A torsion spring
is threaded onto the shaft between the drums. One end of the spring
is secured to a wall bracket and the other end is twisted, to
tension the spring, and then secured to the shaft. The spring tends
to unwind with consequent rotation of the shaft and drums. The
drums are each connected to the upper end of a cable which is
attached at its lower end to the bottom edge of the door. When the
door is unlatched, the spring unwinds, thereby winding the cables
onto the drums and lifting the door.
Both the extension spring and torsion spring arrangements have
shortcomings. For example, in the case of the former, the extension
springs must be balanced to pull on both sides of the door with the
same force; otherwise the door will bind in its tracks. With use,
the extension springs become unbalanced. In the case of the torsion
spring mechanism, expensive, wide, grooved drums must be used. In
addition, the torsion spring equipment is heavy and awkward to
handle, thereby making it difficult to install and adjust.
SUMMARY OF THE INVENTION
With the foregoing remarks in mind, it is an object of this
invention to provide a light, simple counterbalance unit having a
pair of interconnected cable drums which are actuated
simultaneously by a single spiral spring element whereby the drum
cables apply equal lifting forces at each side of the door to be
lifted.
It is another object to provide a unit of this type having means
which permit of easy adjustment of the tension of the spring.
It is another object to provide a unit of this type which is
capable of lifting the door through an extended distance, e.g. 7
feet.
Among other objects of the invention are that the unit should be
adapted for use with either light or heavy doors, that the spring
element should be easily replacable, and that the unit should be
mechanically simple and easy to install.
In accordance with the invention, a number of known parts are
combined in a novel arrangement to provide a single power mechanism
adapted to raise a door through an extended travel. More
particularly, the unit comprises a base having a flat plate, which
is mounted on the garage wall, and a horizontal shaft which extends
forwardly from the plate. A pair of interconnected cable drums are
mounted on the shaft for simultaneous rotation about the shaft
axis. A spiral spring is also mounted around the shaft. The inner
end of the spring is attached to the drums and its outer end is
secured to a normally stationary housing. In operation, the spring
is in a tensioned condition when the door is in the closed
position. When the door is unlatched, the spring expands and
rotates the drums. As the drums rotate, they wind in their
respective cables, which pass over pulleys and are connected to the
bottom edge of the door; the door is therefore lifted with an even
pull on both sides. In one feature of the device, the spiral spring
has a diameter greater than the effective diameters of the drums;
this ensures that sufficient mechanical advantage is available to
enable the spring to raise the door throughout its vertical travel.
In another feature of the device, the housing is rotatable about
the shaft but can be locked in place for normal operations. As a
result, the housing can be rotated to adjust the tension of the
spiral spring and then locked when the desirable degree of tension
has been obtained.
The unit is characterized by a flat structure which can be mounted
over the wall opening and does not interfere with the movement of
the door. It is powered by a single spring which, through a cable
and pulley arrangement, applies equal lifting forces at each side
of the door. The spring's tension can be varied so that the unit
can be used with doors of different weights. The unit is simple,
light, and easy to install and adjust.
Broadly stated, the unit comprises: a base, adapted to be mounted
on the wall, including a horizontal shaft adapted to extend
forwardly from the wall; a pair of interconnected drums mounted on
the shaft for simultaneous rotation therearound; spring-end fixing
means associated with the base and adapted to be rotated around the
shaft independent of the movement of the drums; means, associated
with the base and operatively connected with the spring-end fixing
means, for disengagably locking the spring-end fixing means to
prevent rotational movement thereof; and a spiral spring, disposed
around the shaft, having one end secured to the normally stationary
spring-end fixing means and the other end operatively connected to
the drums for rotation thereof, said spring having an outer
diameter substantially greater than the effective diameter of the
drums.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the unit;
FIG. 2 is a side section view of the unit;
FIG. 3 is a front plan view of the unit;
FIG. 4 is a perspective view of the unit in combination with
pulleys, as it would appear in use;
FIG. 5 shows another version of the assembly shown in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference now to FIGS. 1 - 3, the unit includes a base
comprising a vertical, flat plate 1 and a horizontal shaft 3. The
plate 1 is secured to the garage wall adjacent the door 20 (see
FIGS. 4-5). The shaft 3 is rigidly fixed to the plate 1 and extends
forwardly from it.
A spring housing 5 is rotatably mounted on the shaft 3. The housing
5 consists of a central, cylindrical sleeve 5c, which slidably fits
on the shaft 3, a radially extending back member 5a, and a
forwardly extending rim 5b. The parts 5a, 5b, 5c are integrally
joined together to form a single assembly.
A locking mechanism 6 is associated with the base and operatively
connected with the housing 5. This mechanism 6 functions to
normally lock the housing 5 so that it cannot rotate about the
shaft 3; it can be disengaged, when required, to permit the housing
5 to be rotated. In greater detail, the mechanism 6 includes the
spaced lugs 6a which are attached to the exterior surface of the
rim 5b. A catch element 7 is pivotally attached to the plate 1 and
is urged toward the rim 5b by spring 8. When biased by the spring
8, the catch element 7 engages the lug 6a and prevents
counter-clockwise rotation of the housing 5. To disengage the catch
element 7, one pivots it to the left so that the lug 6a can pass
beneath it.
A cable drum structure 9 is rotatably mounted on the shaft 3. The
structure 9 comprises rotatable drum-supporting means, such as the
hub 10, and a pair of cable drums 11 associated with the said
means. The hub 10 includes a pair of bearing races 10a, which are
mounted on the sleeve 5c, and a web 10c which is carried by the
races 10a and is held in place by the race shoulders 10b. It will
be noted that the hub 10 is adapted to rotate freely about the
shaft 3 and that the hub 10 and housing 5 rotate independently of
one another. Turning now to the cable drums 11, they are integral
with the web 10c for simultaneous rotation about the axis of the
shaft 3. The drums 11 are thin, whereby their cables 12a, 12b are
wound thereon in a single width coil. The races 10a are held in
place by the washer 15. The bolt 14, threaded into the bore 4 of
shaft 3, holds the washer 15 in place.
A spiral spring 17 is provided within the housing 5. The outer end
of the spring 17 is secured to the housing 5. As shown, this may be
done by providing a slot 18 in the rim 5b; a short piece of the
spring 17 is bent backwards to catch on the edge wall of the slot
18. The inner end of the spring 17 is attached to the cable drum
structure 9. This may conveniently be done by cutting a slot in the
hub web 10c and bending the end of the spring 17 back over its
edge.
From the foregoing, it is seen that the housing 5 provides a
normally stationary, spring-end fixing means which is associated
with the base. When the hub 10 is stationary -- as in the case
where the door 20 is in the latched position -- the housing locking
mechanism 6 can be disengaged and the housing 5 rotated around the
shaft 3 to tension the spring 17.
Since the outer end of the spring 17 is normally fixed, expansion
of the coil spring results in rotation of the hubs 10; the drums 11
correspondingly turn and wind in the cables 12a, 12b, thereby
lifting the door 20. It will be noted that the spring 17 has an
outside diameter which is substantially greater than the effective
diameter of the drums 11 (by "effective diameter" is meant the
outer diameter of the cable coils when fully wound on the drums).
The use of a spring having such a large diameter ensures that
sufficient leverage is provided to lift the door through its full
travel.
The unit is mounted on the wall adjacent the door. One of the
advantages of the mechanism is that it can be mounted at any
position on the wall; its cables 12a, 12b can be lead through an
arrangement of pulleys to bring them to the pulleys 19 located
adjacent the upper corners of the door 20.
To counterbalance the unit, the door 20 is locked in the down
position. At this point, the cable drums 11 are locked so that they
cannot rotate. The locking mechanism 6 is then unlatched. Housing 5
is free to rotate, and a wrench can be used to turn sleeve 5c.
Housing 5 is rotated with the result that spring 17 is tensioned.
When it is felt that the proper tension has been reached, the
locking mechanism 6 is actuated to lock housing 5. The door 20 is
then unlatched. If the tension is properly set, the door 20 will
just begin to move and will slowly slide upwardly.
Those skilled in the art will comprehend equivalents to the housing
5 and locking mechanism 6. For example, a framework of
interconnecting rods could be used in place of the solid housing.
The spring end could be welded to a forwardly projecting lug
extending from the framework. The function of the housing 5 is to
provide means for fixing one end of the spiral spring 17, when
required. The means can be rotated when needed to wind up the
spring. In place of the locking mechanism 6 which is described, one
could, for example, secure a tab to the rim 5b. The tab would have
a central opening adapted to line up with one of a group of spaced,
threaded holes formed in plate 1. A threaded screw could be
inserted through the tab and into one of the holes to lock the
housing 5 to the plate 1. It will be understood that minor changes
in the size, form and construction of the various parts of the
improved counterbalance unit may be made and substituted for those
herein shown and described, without departing from the spirit of
the invention, the scope of which is set forth in the appended
claims.
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