Safety device for a movable barrier

A safety device is provided for an upward acting door supported by a support cable, the door being movable along a pair of parallel tracks between an open position and a closed position. The safety device includes a brake pad mechanism disposed within at least one of the parallel tracks and coupleable to the door, the brake pad mechanism operable between a released position, to enable movement of the door as the door is positioned between the open and closed positions, and a braking position, to resist movement of the door. The support cable is coupled to the release mechanism such that in the event of a loss of tension of the support cable, the release mechanism actuates from the released position to the braking position to resist movement of the door.

BACKGROUND

Barrier operator systems of the type including a barrier operator and associated drive assembly for opening and closing sectional garage doors typically also use a counterbalance assembly to provide additional force to assist in the raising of the door and to effect control over the lowering of the door. This assembly conventionally includes a large compression spring for providing the necessary force and a pair of spaced support cables that are attached at one end to the counterbalance spring shaft and at the other end at the bottom of the door. After extended periods of use and/or in instances where the garage door is operated without any preventative maintenance, different portions of the counterbalance assembly can be susceptible to wearing out or breaking, and in some circumstances potentially create unintended movement of the door unless this potential is adequately addressed. For example, this could potentially occur if one or the other of the two support cables snap while the door is closing, due to the then uncounterbalanced weight of the door. In such event, a method of resisting unintended movement of the door can provide additional safety for people and property in the vicinity of the opening.

Many solutions have heretofore been developed to attempt to address this problem. Many of the devices designed to prevent door movement are bulky, difficult to install, costly, not easily retrofitted onto an existing door, or otherwise not satisfactory in their operation for many conditions of service. A need therefore has existed for a new and improved safety device to protect against unintended movement of the door in the event of the breaking of, or damage to, the counterbalance assembly or significant portions thereof.

SUMMARY

Accordingly, the embodiments of the safety device disclosed herein provide a method, in accordance with the principles of the present invention, for substantially compensating for, if not entirely eliminating, the adverse effects of a break in one or both of the support cables affixed to the garage door. The safety device of the present invention preferably includes a main body member adapted for disposition within the confines of one of the parallel door tracks along which the garage door is driven, and coupled to the door so as to travel with it as the door is moved between its open and closed positions. The safety device further includes a brake pad mechanism coupled to a support cable and operable to move one or more brake pads between a retracted position out of engagement with the door track, during normal door operation, and a braking position, in which the brake pads are in frictional engagement with the track, in response to the support cable breaking or otherwise becoming slack. The safety device, through this frictional engagement, thus aids in preventing, or significantly slowing, any unintended movement of the door. If desired, a safety device of the aforestated construction and positioning may be respectively disposed in each of the opposed door tracks.

DETAILED DESCRIPTION

In the description which follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale and certain features may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness.

Referring initially toFIG. 1, a safety device10is illustrated such that, for example, in the event of a breaking or a loss of tension of a support cable12, safety device10will reduce or substantially eliminate the possibility of unintended movement of the garage door. In particular, safety device10is disposed substantially within a parallel track member14and contains a brake pad mechanism16, which is moved in response to loss of tension in support cable12to position one or more brake pads to frictionally engage track14to prevent the door from falling or, at least significantly slow the door's descent downward.

Referring toFIGS. 1-3B, brake pad mechanism16includes a main body member18having a front plate20and a rear plate22forming a support frame or slot24to slideably receive a pair of brake pad supports26and28therein. As seen specifically inFIGS. 3A and 3B, supports26and28each include generally planar surfaces30,32and34and are angled so as to be generally parallel to inner surfaces36,38and40, respectively, of track14. Planar surfaces30,32and34are sufficiently sized to support brake pads42,44and46thereon such that when brake pad mechanism16is triggered, supports26and28are pushed outward to a braking position so that brake pads42,44and46frictionally engage surfaces36,38and40(FIG. 4B) to stop or slow further downward movement of the door. Alternatively, planar surfaces30,32and34can be formed of a material to directly frictionally engage surfaces36,38and40such that brake pads42,44and46are not necessary.

In operation, brake pad mechanism16is moved from a retracted position (i.e., when brake pads42,44and46are spaced apart from inner surfaces36,38and40) to the braking position in response to movement of a tensioning arm50, which is rotatably mounted to front plate20. In particular, a biasing mechanism54biases tensioning arm50to rotate in the direction of arrow56(FIG. 2) to facilitate the disengagement of a reset link52from tensioning arm50. This disengagement between tensioning arm50and link52enables link52to rotate upward in the direction of arrow88to, as explained in further detail below, cause movement of brake pad supports26and28, and thus, brake pads42,44and46, to the braking position.

Referring specifically toFIG. 1, tensioning arm50is interfaced with support cable12via a cable follower58, which is positioned to receive support cable12through an opening60formed on cable follower58. After inserting support cable12through opening60and applying tension to support cable12, tensioning arm50rotates in the direction of arrow57until arm50, and in particular, arm extension50a, is generally in the vertical position (i.e., generally parallel to track14). When positioned as such, tensioning arm50holds or otherwise prevents the release of reset link52from within a curvilinear slot84, which is disposed on a base section50bof tensioning arm50.

As illustrated inFIGS. 1 and 2, reset link52includes a first end80pivotably coupled to front plate20and a second end82having a cam follower86movable within curvilinear slot84(FIG. 2). In operation, if tension in support cable12is lost, biasing mechanism54releases its stored energy to rotate tensioning arm50in the direction of arrow56, which in turn releases or otherwise allows the disengagement of second end82of reset link52from curvilinear slot84. Once disengaged, reset link52is biased to rotate in the direction of arrow88(FIG. 2), which in turn rotates a cam90(FIGS. 4A and 4B). As cam90, which is fixedly secured to reset link52, rotates, brake pad supports26and28are outwardly positioned to enable brake pads42,44and46to frictionally engage track inner surfaces36,38and40.

InFIGS. 4A and 4B, cam90is disposed between brake pad supports26and28and is preferably oval shaped having a major axis92, the cam90movable between a vertically oriented position (FIG. 4A, where major axis92is vertically oriented) to a generally horizontally oriented position (FIG. 4B, where major axis92is horizontally oriented). Movement of cam90from the vertically oriented position to the horizontally oriented position causes brake pad supports26and28and thus, brake pads42,44and46, to contact inner surfaces36,38and40, respectively, of track14. A biasing mechanism94biases cam90toward the horizontally oriented position to configure and/or otherwise exert an outward force on surfaces96and98of supports26and28. Thus, as reset link52is released from curvilinear slot84(as a result of tension loss of support cable12), biasing mechanism94releases its stored energy to rotate cam90(and thus reset link52) to the horizontal oriented position thereby moving supports26and28and thus, brake pads42,44and46, to the braking position.

Brake pad mechanism16is easily positionable to the retracted position after, for example, actuation of brake pad mechanism16, without the use of tools or requiring that any component of track12and/or release mechanism16be replaced. For example, when configuring brake pad mechanism16from the braking position to the retracted position, reset link52is manually moved in the direction of arrow89(FIG. 2), thereby causing rotation of cam90in the direction of arrow100(FIG. 4A) and storage of potential energy in biasing mechanism94. This movement continues until reset link52and cam90are both generally vertically oriented. During this movement and as particularly illustrated inFIGS. 4A and 4B, a pair of tensioned return springs102and104retract supports26and28inward in the direction of arrows106and108to maintain contact with the outer surface of cam90. As reset link52reaches its vertical orientation, tensioning arm50is manually rotated/oriented such that curvilinear slot84will be configured to receive cam follower86therein (FIG. 2). Tension is applied to support cable12so as to resist substantial movement of tensioning arm50, which prevents the release of reset link52from curvilinear slot84and maintains brake pad mechanism16in the retracted position.

Referring toFIGS. 5 and 6, safety device10optionally includes an external brake pad support200having a brake pad202to frictionally engage an outer surface204of track14in response to actuation and movement of brake pad mechanism16to the braking position. Preferably, brake pad support member200is used with heavier garage doors to provide additional frictional contact between brake pad202and track14and thus, additional braking support for the garage door to prevent the door from falling, or at least slow its descent in the event of a break in support cable12, resulting in a loss of tension of support cable10.

InFIGS. 5 and 6, a guide arm206extends from brake pad support200and is aligned with, supported on, and otherwise movable with respect to a stationary guide208. A coupler210extends between guide arm206and reset link52such that as reset link52is released from tensioning arm50and rotates in the direction of arrow88, brake pad supports26and28frictionally engage internal surfaces36,38and40, and brake pad support200(and thus brake pad202) is pulled toward outer surface204to enable brake pad202frictionally engages surface204(FIG. 6). In the embodiment illustrated inFIGS. 5 and 6, coupler210comprises right and left hand threads for engagement with threaded rods212and214, which are used to connect coupler210to guide arm206and reset link52and also to facilitate the adjustment of the position of brake pad202relative to surface204when brake pad mechanism16is in the retracted position.

Preferably, safety device10is substantially disposed within at least one of the parallel track members14; however, it should be understood that a safety device10could be disposed within each of the parallel track members14. Referring back toFIGS. 1 and 2, safety device is mounted on a roller shaft110adjacent to a bottommost garage door panel (not illustrated). Front plate20contains a slot or recessed portion112to receive roller shaft110, which supports a door roller on the garage door. Roller shaft110is inserted within recess112and locked therein via a locking plate114, which is coupled to and disposed along the bottom portion of front plate20. It should be understood that other methods of coupling roller shaft110to safety device can be used, such as, for example, frictionally engaging roller shaft110within recess112. Safety device10is further supported and/or otherwise balanced within track14by a pair of roller guides116and118. In the embodiment illustrated inFIGS. 1 and 2, roller guide116is mounted on front plate20on an end opposite recessed portion112and roller guide118is disposed intermediate roller guide116and roller shaft110. Roller guides116and118and the garage door roller mounted on roller shaft110all function to stabilize safety device10within track14.

Embodiments disclosed herein provide for a safety device10that can potentially be installed onto many existing or previously installed garage doors. For example, instead of attaching system10directly to a garage door at the factory, safety device10can be aligned within track14and coupled to roller shaft110during installation of the garage door in the field and/or retrofitted to an already existing garage door. In addition, safety device10can be easily removed from track14without damage thereto and/or damage to the garage door.

Embodiments disclosed herein also provide a brake pad mechanism16designed to be operable even after engaging track14without necessitating the replacement any of the components of brake pad mechanism16and/or track14. Thus, brake pad mechanism16is easily resettable for repeated use. For example, brake pads42,44,46and202can be formed of a material and desired thickness to withstand multiple engagements with track14. If, after repeated use, it becomes necessary to replace worn or unusable brake pads42,44,46and/or202, the brake pads are removed from brake pad supports26and28and replaced with new brake pads42,44and46so that brake release mechanism16remains operable.

Safety device10is operable to prevent accidental actuations that could occur as the garage door moves to the fully open position. In particular, sometimes slack in support cable12can potentially develop as the garage door and thus, safety device10, travels along the curved portion of track14(i.e., the portion that connects the horizontal and vertical track sections). In order to accommodate for such periods of slack and thus prevent false actuations of brake pad mechanism16, tensioning arm50rotates or otherwise adjusts in response to small variations of tension in support cable10. In particular, the curvature of curvilinear slot84enables cam follower86to move within slot84to accommodate slight angular displacements of tensioning arm50resulting from tension variations without releasing reset link52from slot84. However, if the slack in support cable12rises above a predetermined threshold (i.e., more than what typically occurs during movement of the door or when the door approaches the raised position), tensioning arm50will continue to rotate until reset link52exits slot84, thereby actuating brake pad mechanism16.

Although embodiments of cable failure device10have been described in detail, those skilled in the art will also recognize that various substitutions and modifications may be made without departing from the scope and spirit of the appended claims.