GB2323408A

GB2323408A - Safety system for canopy doors

Info

Publication number: GB2323408A
Application number: GB9705761A
Authority: GB
Inventors: George William Marren
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-03-20
Filing date: 1997-03-20
Publication date: 1998-09-23
Anticipated expiration: 2017-03-20
Also published as: GB9705761D0; GB2323408B

Abstract

A system for power operated canopy doors is connected to a boom 1 of the door's drive unit. Drive bar 3 is pivotally mounted on a moveable trolley 2 and on a casing 7 which runs by means of guide rollers 18, 19, 10 and 21 on a bow arm 14 which is fixed to the top of the door. A cam track 13 is attached to bow arm 14. Coil springs 8 and 9 and microswitches 10, 11 and 12 are mounted on casing 7. Microswitch 12 runs on cam track 13 and is moved to the closed (ON) position at the half-way stage of the door closing cycle. If the door meets an obstruction on the second half of the door closing cycle, drive bar 3 is cranked at pivot point 5 and causes microswitch 10 to move to the closed (ON) position thus cutting out the door's own electrical system and door movement is stopped. Coil spring 8 returns drive bar 3 to its central position. The reverse action takes place on the first half of the door opening cycle utilising coil spring 9 and microswitch 11.

Description

SAFETY SYSTEM FOR CANOPY DOORS This invention relates to a safety system for canopy doors.

More particularly, but not exclusively, this invention relates to a safety system for power operated canopy doors for car garages.

Canopy doors are the most popular type of doors for car garages because they provide the widest possible opening. When the door is fully open and retracted in the horizontal position, part of the door projects in front of the garage creating a canopy effect. Canopy doors rely upon various types of tension springs combined with side channels in the door frame to provide for easy lifting and lowering movement of the door by roller action.

Power operated canopy doors which operate on the boom principle require a bow arm of some sort fitted centrally to the top inside of the door to enable the door to be opened and closed. The function of the bow arm is to redirect the horizontal opening and closing forces generated by the electric motor and the boom. The curve of the bow arm serves to redirect these horizontal forces in the upwards and downwards direction required respectively for the opening and closing of the door.

All canopy doors need a high torque in the first half of the closing cycle because of the door design. As a consequence of the design, more energy is required in the first half of the closing cycle than is required in the second half of the closing cycle. In other words, the further the door descends down the side frames, the less the energy required to close the door.

The large amount of energy required for the first half of the closing cycle continues to act on the door during the second half of the closing cycle where it is not required. This excess energy accumulates and cannot be reduced as the door descends.

This presents a serious safety hazard if the door meets an obstruction towards the end of the second half of the closing cycle and in consequence some means is required to absorb the unwanted excess energy. Door manufacturers attempt to achieve this by incorporating a sensitivity system into the door system By sensitivity, is meant the ability of a power operated canopy door to stop or reverse if it contacts an obstruction in the second half of the closing cycle.

Sensitivity can be achieved electrically by measuring the current increase as the motor load increases due to door contact with an obstruction and is controlled by a potentiometer, adjustable for varying sizes and weights of door. Sensitivity can also be achieved mechanically by use of microswitches connected to a pinion or sprocket driven by the boom action and which move under load when an obstruction is encountered.

However, no matter what type of sensitivity mechanism is incorporated in the door system, most designs of power operated canopy doors suffer from serious loss of sensitivity in the second half of the closing cycle due to the aforementioned accumulation of excess energy which has been created for the first half of the closing cycle.

Similar considerations apply in reverse with regard to the opening cycle of power operated canopy doors.

One aspect of the present invention, is to provide an additional safety system which overcomes the above mentioned problems of reduced or loss of sensitivity experienced with the opening and closing cycles of many designs of power operated canopy doors.

Another aspect of the present invention, is to provide an additional safety system which gives fine control of speed and torque in the opening and closing cycles of power operated canopy doors.

The safety system of the invention can be: (a) provided for manually operated canopy doors which are being converted to power operation; (b) incorporated in already installed power operated canopy doors; and (c) incorporated in power operated canopy doors at the time of manufacture.

The safety system of the invention enables even the most basic power operated canopy doors to comply with the safety regulations of many countries.

According to the present invention there is provided a safety system for a power operated canopy door unit comprising a pair of switches capable of forming an electric circuit with the stop/start connections of the door unit's motor, the first switch being activated by the door's movement at the half-way stage of the door closing cycle and being deactivated by the door's movement at the end of the door closing cycle and the second switch being activated by the force generated when the door meets an obstruction during the second half of the door closing cycle, the arrangement being such that as soon as the second switch is activated both the first and second switches are in electrical connection with the motor's stop connection and movement of the door automatically ceases.

Preferably, the safety system of the present invention has a third switch capable of forming an electric circuit with the stop/start connections of the door unit's motor, the first switch being activated by the door's movement at the start of the door opening cycle and being deactivated by the door's movement at the half-way stage of the door opening cycle and the third switch being activated by the force generated when the door meets an obstruction during the first half of the door opening cycle, the arrangement being such that as soon as the third switch is activated both the first and third switches are in electrical connection with the motor's stop connection and movement of the door automatically ceases.

Suitably, the electrical connection of the second and third switches with the motor's stop connection can only be made when the first switch is activated.

Further preferably, the first switch is activated and deactivated by the action of a cam associated with the door's movement.

Suitably, the cam is attached to a bow arm of the door unit.

In a preferred embodiment, the safety system of the invention has a pivotally mounted drive bar connected at its top end to a boom trolley of the door unit and is adapted at its bottom end to run on the bow arm of the door unit.

Also in such a preferred embodiment, the first switch is mounted on the drive bar so as to move along the cam attached to the bow arm of the door unit.

An embodiment of the invention will now be described, simply by way of example, with reference to the accompanying drawings in which: Figure 1 is a detailed drawing of the safety system of the invention; Figure 2 is a schematic diagram of the safety system of the invention incorporated into a power operated canopy door system; Figure 3 is a schematic diagram showing the safety system of the invention at various positions during the closing cycle of a power operated canopy door, Figure 4 is a schematic diagram showing the position of a control microswitch on a cam track component of the safety system of the invention at various stages of the closing cycle of a power operated canopy door; and Figure 5 is a circuit diagram showing three microswitches of the safety system of the invention connected up to the standard stop/start connections of a power operated canopy door system.

Referring to Figure 1, a horizontally mounted boom 1 of a power operated canopy door system is connectable at one end to an electric motor (not shown).

A trolley 2 is mounted for travel along boom 1 and can be driven in either direction depending on whether the door is being opened or closed. The driving action of boom 1 can be achieved by various means such as screw, chain, toothed belt or cable drive.

The length of boom 1 is selected so that it is the correct length for opening and closing a door of a particular size. The boom 1 is usually supplied for use with a standard size of door and is altered for length depending on which type of drive is used.

An elongated drive bar 3 is pivotally attached near its top end to trolley 2 by pivot bolt 4. Drive bar 3 is also pivotally attached some way down its length by pivot bolt 5 to a wall 6 of a protective casing 7 which serves as an extension of drive bar 3. Two coil springs 8 and 9 are attached to opposite sides of drive bar 3. The coil springs 8 and 9 serve to return the drive bar 3 to its central position when it oscillates during the door opening and closing cycle.

Two microswitches 10 and 11 are located at the bottom of drive bar 3 with microswitch 10 being positioned directly above microswitch 11. A third control microswitch 12 is located at the bottom end of casing 7. As is later described, a cam track 13 serves as an activator for control microswitch 12. Cam track 13 is attached to a curved bow arm 14 and conforms to the curve of bow arm 14. Curved bow arm 14 is attached to a bow mounting plate 15 by means of bolts 16 and 17. Bow arm mounting plate 15 is attached in vertical position to the top centre of the garage door. Four rollers 18, 19, 20 and 21 are mounted on casing 7 by pivot bolts 22, 23, 24 and 25 and serve as guides for casing 7 as it runs backwards and forwards along bow arm 14 during opening and closing of the door.

In addition to the above mentioned component parts, the safety device of the invention includes a wiring loom to connect microswitches 10, 11 and 12, transfer cables electrically connecting the safety device to the stop/start connections of the motor unit and various other fixings.

Referring now to Figure 2 of the drawings, the safety device of the invention is shown connected up to a canopy door 26 and to an electric motor 27 via trolley 2 and boom 1. A distance is set for correct travel of door 26. Distance 28 is the operational distance of control microswitch 12 when switch 12 is in the closed (ON) position and distances 29 and 30 are the operational distances of microswitch 12 when switch 12 is in the open (OFF) position.

Referring now to Figure 3 of the drawings, it can be seen that as the canopy door 26 closes, utilising rollers 31, the control switch 12 runs along bow arm 14 from top to bottom thereof as the bow arm 14 moves with the door 26 from the horizontal (door open) position to the vertical (door closed) position. Furthermore, whilst the door 26 is closing, the drive bar 3 moves along boom 1 from a position approaching horizontal to a position approaching vertical. The reverse action takes place when the door 26 is opening.

As the drive bar 3 reaches the half-way stage of the door closing cycle, the excess energy generated to start the door closing action and to move the door downwards to the half-way stage accumulates at pivot point 5. If the door 26 meets an obstruction in the second half of the closing cycle, the accumulated energy causes drive bar 3 to crank on pivot point 5 which triggers microswitch 10 to move to the closed (ON) position thus cutting out the door's conventional electrical system with the result that the downward movement of the door 26 is stopped or reversed. The more vertical the drive bar 3, the less is the torque needed to cause drive bar 3 to hinge and actuate rnicroswitch 10. The reverse action takes place on the first half of the door opening cycle and microswitch 11 is moved to the closed (ON) position.

Referring now to Figure 4 of the drawings, it can be seen that when the door 26 is in the fully open position, control microswitch 12 is at the top of cam track 13 in the open (OFF) position thus preventing microswitch 10 from moving to the closed (ON) position. When the door 26 is half closed, microswitch 12 is in a position half-way down cam track 13 and a break 32 in the profile of cam track 13 causes control microswitch 12 to move to the closed (ON) position thus making it possible for switch 10 also to become closed (ON) if the door makes contact with an obstruction 33 during the second half of the closing cycle. Movement of switch 10 to the closed (ON) position will stop or reverse the door's downward movement by virtue of the electrical connection with the door's starting connection 34. When the door 26 approaches the fully closed position, the drive bar 3 has been driven up to the door 26. Before the fully closed position is reached, control microswitch 12 becomes open (OFF) again by a further change in profile of cam track 13 and so prevents an electrical circuit with microswitch 10. At the fully closed position, control microswitch 12 is at the bottom of cam track 13. Again the reverse action takes place on the door opening cycle with microswitch 11 being actuated.

The configuration of cam track 13 is such that when control microswitch 12 is in the open (OFF) position, there is no sensitivity in the safety device of the invention and microswitches 10 and 11 cannot be actuated until switch 12 is closed.

The above description of one embodiment of the invention concentrates on the door closing cycle. The reverse action applies, however, to the door opening cycle. Microswitches 10 and 11 fulfill the same purpose but for different directions of force. Microswitch 10 is for the door closing cycle and microswitch 11 is for the door opening cycle.

Microswitch 12 may be replaced by a tilt switch or a mercury switch but microswitches 10 and 11 are purely mechanical switches.

When the door movement is stopped or reversed due to the activation of microswitch 10 or 11, restoration of the door movement can be achieved by removal of the obstruction 33 and thus release of pressure on the door followed by activation of the motor's starting connection 35 either directly or by remote control.

Claims

1. A safety system for a power operated canopy door unit comprising a pair of switches capable of forming an electric circuit with the stop/start connections of the door unit's motor, the first switch being activated by the door's movement at the halfway stage of the door closing cycle and being deactivated by the door's movement at the end of the door closing cycle and the second switch being activated by the force generated when the door meets an obstruction during the second half of the door closing cycle, the arrangement being such that as soon as the second switch is activated both the first and second switches are in electrical connection with the motor's stop connection and movement of the door automatically ceases.

2. A safety system as claimed in claim 1 having a third switch capable of forming an electric circuit with the stop/start connections of the door unit's motor, the first switch being activated by the door's movement at the start of the door opening cycle and being deactivated by the door's movement at the half-way stage of the door opening cycle and the third switch being activated by the force generated when the door meets an obstruction during the first half of the door opening cycle, the arrangement being such that as soon as the third switch is activated both the first and third switches are in electrical connection with the motor' s stop connection and movement of the door automatically ceases.

3. A safety system as claimed in claim 2 wherein the electrical connection of the second and third switches with the motor's stop connection can only be made when the first switch is activated.

4. A safety system as claimed in any one of the preceding claims wherein the first switch is activated and deactivated by the action of a cam associated with the door's movement.

5. A safety system as claimed in claim 4 wherein the cam is attached to a bow arm of the door unit.

6. A safety system as claimed in claim 5 having a pivotally mounted drive bar connected at its top end to a boom trolley of the door unit and adapted at its bottom end to run on the bow arm of the door unit.

7. A safety system as claimed in claim 6 wherein the first switch is mounted on the drive bar so as to move along the cam attached to the bow arm of the door unit.

8. A safety system for a power operated canopy door unit substantially as described herein with reference to Figures 1 to 5 of the accomapnying drawings.