GB2039595A - Closure structures - Google Patents

Abstract

A closure arrangement for an opening comprises a closure structure (1) slidable sideways relative to the opening, an electric motor drive (7), preferably three-phase, connected by means of an endless chain (8) to the closure structure (1) to effect the sliding and an automatic electric switching device (10) comprising a motor current sensor operable to switch off the motor (7) if the current exceeds a predetermined value. The current sensor may be a relay or resistor in circuit with the motor (7) or isolated therefrom by a transformer. The sensor may operate the on-off manually operable switch (10) for the motor (7) or may operate an auxiliary switch provided with latching and resetting means. The endless chain (8) may run along the top edge of the opening in a channel (3) from which the closure structure (1) is slidably supported, the closure structure (1) comprising sections (2) pivotally connected to adjacent sections (2) along their vertical edges. <IMAGE>

Description

SPECIFICATION Closure structures This invention relates to a closure structure of the kind which is slidable sideways relative to an opening towards and away from a closed position at which it extends across the opening thereby to close same. The invention is more particularly, although not exclusively concerned with such a closure structure of the kind, hereinafter referred to as the kind described, which is formed from a plurality of pivotally interconnected vertical sections which pivot relative to each other to effect folding of the closure structure as such structure slides away from the said closed position thereof.

A closure structure of the kind described may be provided with an electric motor drive to effect sliding ofthe structure between said closed position and an open position at which the structure is retracted in folded condition at or adjacent one side edge of the opening. With this arrangement, it is known to provide limit switches which are automatically operated by interengagement thereof with a part of the closure structure respectively in the said open and closed positions thereof, such limit switches when operated acting to stop the motor drive.It is also known to provide the motor drive with a torque limiter instead of said limit switches, said torque limiter comprising a mechanical device which acts to operate a control switch to stop the motor drive when the torque output of the motor exceeds a predetermined value such as occurs when the closure structure reaches a limit of its travel or becomes jammed or obstructed. With these known arrangements, however, the problem arises that complicated and1or expensive switching arrangements are required in orderto effect the requisite automatic control of the motor drive.

An object of the present invention is to provide a closure arrangement incorporating a closure structure which is operated by a motor drive which can be automatically controlled with a simple and inexpensive switching arrangement.

According to the invention therefore there is provided a closure arrangement comprising a closure structure of the kind which is slidable sideways relative to an opening towards and away from a closed position at which it extends across the opening thereby to close same, an electric motor drive for effecting said sliding, and an automatic electrical switching device for controlling operation of the motor drive, characterised in that the automatic switching device comprises a current sensor operable to sense current flow to the motor drive and to act to cause the motor drive to be switched off when said current exceeds a predetermined value.

With this arrangement, it will be appreciated that the same said current sensor, which may be a simple inexpensive electrical and/or electronic device, can respond to any circumstance giving rise to an increase in current flow, including attainment of a limit to the travel of the closure structure in each direction and also any jamming or obstruction thereof, whereby comprehensive control of the motor drive can be achieved with a simple and inexpensive switching arrangement.

With regard to the closure structure, this may be of any suitable construction and may slide in any suitable manner. Thus, the structure may be an openwork gate structure, or a solid door structure, or a solid or openwork sectioned shutter structure.

Preferably, a folding closure structure of the kind aforementioned described is used.

The motor drive may utilise an electric motor of any suitable kind and this may be connected to the closure structure in any suitable manner. In a preferred embodiment, however, the motor is a three-phase electric motor and this is connected to the closure structure via an endless chain which runs along a top edge of the opening.

The current sensor may take any suitable form and thus may comprise an electromechanical component, such as a relay which operates when the current flowing through same reaches the said predetermined value, or a component such as resistor which under such conditions undergoes a change in a parameter, such as a change in potential across same, which change can control operation of an electronic switching circuit. Any such component may be connected directly in circuit with the motor or may be connected via a transformer or other isolating component or circuit. Alternatively, a sensor may be used which responds directly to a current-influenced change in parameter of the motor itself or of some other auxiliary device which is provided for the purpose of starting or control ling normal running of the motor.

The current sensor may be arranged to actuate a specially provided switch which is connected in circuit with the motor, which switch may be provided with an appropriate latching and resetting arrangement to ensure that the motor is held switched off until it is desired to restart same.

Alternatively, the sensor may be arranged to appropriately actuate a starting and stopping mechanism provided for normal manual control of the motor.

The invention will now be described further by way of example only and with reference to the accompanying drawing which is a diagrammatic representation of one form of a closure arrangement according to the invention.

The closure arrangement is for closing a large opening in industrial or commercial premises such as a vehicle access opening in a factory or warehouse.

The closure arrangement incorporates a closure structure 1 of the kind known as a folding shutter door. Such door 1 comprises a plurality of rigid steel elongate sections 2 which are hinged together in vertical side-by-side disposition. The door 1 is suspended from a track 3 secured along the top periphery of the opening, by means of suspension members 4 which are secured at intervals to the top edge of the door 1 and which extend through a slot in the bottom of the track 3 and are connected to rollers 5 which bear on and are free to run along the track 3. The door 1 is also guided in a slide track (not shown) running along the bottom periphery of the opening. On the inner side of the door the sections 2 may be linked by a mesh 6 of pivotally interconnected struts which can extend and retract in a 'lazy tong' manner.

The door 1 so far described can slide horizontaliy across the opening between a closed position at which the door completely covers the opening, and an open position at which the door is retracted to expose substantially the entire opening. During such horizontal sliding, the door is guided by the upper and lower slide tracks and the sections 2 pivot relative to each other so that they are almost co-planar in the closed position and are folded back against each other in concertina fashion in the open position.

In order to effect such horizontal sliding there is provided a drive system comprising a three-phase electric motor 7 and an endless chain 8. The chain 8 passes around wheels 9 mounted at opposite ends of the upper periphery of the opening and has upper and lower horizontally extending runs 8a, 8b adjacent the upper slide track 3. The lower run 8b of the chain 8 is connected to a leading portion of the door 1, and the motor 7 is drivably connected to the chain.

The motor 7 is connected to three-phase a.c.

mains supply, in accordance with conventional practice, via a starter control 10 having forward and reverse buttons 11, 12so that the door can be drawn by the chain 8 to the open and closed positions by appropriate operation of the buttons.

Contrary to conventional practice, however, the starter control 10 incorporates (within a common housing) a current sensor (not shown) which comprises a relay having the coil thereof in series with the motor 7 and having contacts thereof in a control circuit associated with the starter control mechan ism. The arrangement is such that the relay operates only when the current flowing through the relay coil exceeds a predetermined value. This does not occur during normal running of the motor but only occurs when the door reaches a limit to its travel (in the open or closed position thereof) or becomes jam med or obstructed. When the relay operates, the starter control mechanism trips out and the motor 7 is disconnected from the power supply.

With this arrangement it will be appreciated that the current sensor can perform the function of opening and closing limit switches and also of a safety cut-out switch. Separate such switches are therefore not necessary, and, having regard to the possible simplicity, reliability and low cost of the current sensor, considerable advantages can there fore result from the use of same.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only.

Claims (15)

1. A closure arrangement comprising a closure structure slidable sideways relative to an opening towards and away from a closed position in which it extends across the opening thereby to close the same, an electric motor drive adapted to effect said sliding and an automatic electrical switching device adapted to control operation of said motor drive and comprising a current sensor operable to sense current flow to the motor drive and to cause the motor drive to be switched off when said current exceeds a predetermined value.

2. A closure arrangement according to claim 1 wherein said current sensor comprises a relay operable when said current exceeds a predetermined value.

3. A closure arrangement according to claim 1 wherein said current sensor comprises a resistor across which the potential changes in accordance with said current and an electronic switching circuit operable in response to said potential.

4. A closure arrangement according to any one of claims 1 to 3 wherein said current sensor actuates a manually operable starting and stopping switch means connected to said motor for control thereof.

5. A closure arrangement according to any one of claims 1 to 3 wherein said current sensor actuates an auxiliary switch connected thereto and in circuit with said motor.

6. A closure arrangement according to claim 5 wherein said auxiliary switch is provided with latching and resetting means whereby said motor remains switched off until said resetting means is actuated.

7. A closure arrangement according to any preceding claim wherein said current sensor and said motor are connected in series.

8. A closure arrangement according to any one of claims 1 to 6 wherein isolating means isolate said current sensor from the circuit containing said motor.

9. A closure arrangement according to claim 8 wherein said isolating means comprises a transformer.

10. A closure arrangement according to any preceding claim wherein said motor is a three-phase motor.

11. A closure arrangement according to any preceding claim wherein said motor is connected to said closure structure by means of an endless chain.

12. A closure arrangement according to claim 11 wherein said endless chain runs along a top edge of said opening.

13. A closure arrangement according to any preceding claim wherein said closure structure com prises a plurality of sections with adjacent sections pivotally connected with each other along vertically disposed edges thereof.

14. A closure arrangement according to claim 13 wherein said sections are slidably supported in a channel track secured along a top edge of said opening.

15. A closure arrangement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.