GB2286012A

GB2286012A - Door closing device

Info

Publication number: GB2286012A
Application number: GB9500920A
Authority: GB
Inventors: Frank John Thompson Hancock
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-01-20
Filing date: 1995-01-18
Publication date: 1995-08-02
Also published as: GB9500920D0; GB9401025D0

Abstract

A door closing device 11 comprises a drive unit 12 with a door engaging arm 13 operable to close the door but adapted to offer no resistance to the door being opened. A timer 15 causes the drive unit 12 to operate to close the door after a delay period following opening of the door. The timer being reset after the door is closed. The drive unit 12 may comprise an electric motor 16, reduction gearing 17 and an electronic clutch 18. The drive unit 12 is deactivated when the door is closed or upon the door encountering resistance during closing. An ammeter 22 monitoring the current supplied to the motor 16 may be used to detect resistance to the door closing. <IMAGE>

Description

DOOR CLOSING DEVICES This invention relates to door closing devices.

Conventional door closing devices are springoperated, energy required for closing the door being stored in a spring by the action of opening the door and released in controlled fashion, controlled by a dashpot, once the door is released. A disadvantage of such devices is that the spring force has to be overcome to open the door. The devices also required adjustment to close in properly controlled fashion and this is not always achieved, some doors closing too fast and too hard and being thus annoying and sometimes dangerous, others closing so slowly that they do not have enough power to latch.

Proposals have been made for electrically operated door openers and/or closers, but those are expensive and often complicated to install. An electrically operated door opening and closing device is disclosed in GB-1,327,780 which involves an electric motor and clutch arrangement which operates in conjunction with a spring which is extended by the motor as the motor closes the door to provide stored energy for opening the door when a person approaches and triggers a detector such as a mat switch. By its design, the device uses a smaller, less powerful and therefore less expensive, motor than previous such proposals, but the motor must be powerful enough, nevertheless, to both open the door and stress the spring to provide opening power.

The present invention provides a door closing device which is inexpensive, compact and easy to install.

The invention comprises a door closing device comprising a drive unit with a door-engaging member operable to close the open door but adapted to offer no resistance to the door opening, a timer adapted to cause the drive unit to operate to close the door after a delay period after opening of the door and to be reset after the door is closed, the drive unit being stopped when the door is closed or while the door is closing upon encountering resistance to further closing movement.

The drive unit may comprise an electric motor driving the door-engaging member through a gear box.

The unit may comprise a clutch which engages the drive between the motor and the door-engaging member only when the motor is energized. The clutch may be a mechanical clutch such, for example, as one that operates centrifugally, or it may be electrically operated, as by electromagnetic or electrorheological operation.

In this way, the door can be opened without any resistance from the device, the door pushing the doorengaging member against no or minimal resistance from the drive unit.

In another arrangement, the drive unit can reverse to retract the door-engaging member to a position corresponding to an open door when the door is closed or upon encountering resistance to further closing movement.

In any event, the signal that the door is closed, and that the motor must stop and the clutch disengage, or the motor must reverse, could be an increased resistance to closure as would be encountered when the door is, in fact, closed or when, during closing, someone pushes on the door to open it, or at least prevent it closing further. Such increased resistance can be detected by monitoring motor current, which will increase above its normal operating level, or in any other convenient way. Such signal can also be used to reset the timer.

The timer can be operated to count down the delay period by the door-contacting member being out of the closed position when the timer is set to zero - this is appropriate where the clutch is used, but where the door-engaging member is normally retracted away from the door, a limit switch could be fitted to detect whether the door is open or closed.

Embodiments of door opening devices according to the invention will now be described with reference to the accompanying drawings, in which Figure 1 is a diagrammatic elevation of a door with a closing device, and a control system; Figure 2 is a diagrammatic plan view of the door and device of Figure 1; Figure 3 is a diagrammatic elevation of a door with another embodiment of closing device, and a control system; and Figure 4 is a diagrammatic plan view of the door and device of Figure 3.

The drawings illustrate door closing devices 11 such as might beused in the home for example to keep, say, a bathroom door closed or for fire doors or though probably as original equipment rather than as equipment fitted to existing doors - refrigerator and freezer doors, or indeed anywhere where a door is desirably kept closed.

The devices 11 comprise drive units 12 with doorengaging members 13 operable to close the open door 14.

Such a member 13 could simply be an arm which is rotatable by the drive unit 12 and which has a softsurfaced roller 13a at its extremity that simply pushes the door to - nothing need be fitted or attached to the door 14.

The members 13 are arranged, however, to offer no resistance to the door 14 opening. The doors 14 can thus be opened normally exactly like doors which have no associated mechanism. Ways in which this is achieved will be explained presently.

The devices 11 include a timer 15 adapted to cause the drive unit 12 to operate to close the doors 14 after a delay period after opening of the doors 14, and to be reset after the door is closed.

The drive units 12 are stopped when the door is closed or when closure is interrupted - when the door, during closing, encounters resistance to further closing movement.

In each case the drive unit 12 comprises an electric motor 16 which drives the door-engaging member 13 through a reduction gearbox 17.

In the embodiment illustrated in Figures 1 and 2, the device comprises a clutch 18 which engages between the motor 16 and the door-engaging member 13 when the motor 16 is energised. As this means that the clutch 18 is disengaged when the motor 16 is not energised, the door-engaging member 13 is freely movable then and presents no resistance to door opening.

The clutch 18 could be a mechanical clutch operating, e.g. by centrifugal action, but then would be better situated between motor 16 and gearbox 17 because the higher rotational speed of the motor, as compared to the gearbox output shaft, would enhance the centrifugal effect. This might, however, result in some resistance to door opening because of having to drive the gearbox.

However, an electrically operated clutch can be situated between gearbox 17 and door-closing member 13.

An electromagnetic clutch, after the fashion, perhaps, of the one illustrated in GB-1,327,780 could be used, or an electrorheological device in which a fluid is rigidified by anapplied electric or magnetic field.

The control arrangement includes the timer 15 which, when set to count, times a delay period (which may be user-selectable) after which the drive unit 12 i set to operate to close the door. The timer 15 is started on the countdown to door closure operation by a signal from a transducer 21 between the unit 12 and the member 13.

When the door closes, the motor 16 is still running but now experiences a resistance to motion that causes the operating current to rise. The current is measured in an ammeter 22, which resets the timer 15 when the current exceeds a predetermined amount, and this cuts off the power supply to the motor 16, and the clutch 18, by a switch 19, which, however, resets when the current falls.

The premature halting of a closing door has exactly the same effect as if the door was closed against its lintel - the ammeter 22 causes the timer 15 to reset, and the door stops closing and can even be pushed open further.

The timer 15 is always, once reset, started on its countdown unless the signal from a transducer 22 mounted between clutch 18 and door-engaging member 13 indicates that the door is closed.

Thus, any time the door is open, the timer 15 will, after a predetermined time interval, set in motion the motor 16 to close the door.

Figures 3 and 4 illustrate a second embodiment of door closing device 11 in which, when the door 14 is closed, the door-engaging member 13 is retracted clear of the door 14. The drive unit 12 reverses to retract the door-engaging member 13 to a position (broken line, Figure 4) corresponding to an open door 14 when the door 14 is closed or upon encountering resistance to further closing movement.

This embodiment is in all other respects essentially the same as the embodiment of Figures 1 and 2. It avoids the need for an electrically or otherwise operated clutch by substituting a motor reversal switch 23 operated by the ammeter 15 and may be less expensive and consume less power in operation.

Operating power may be derived from a battery 24 which may be rechargeable - a kit of parts may come complete with charger and two batteries, one to operate, the other to charge. Or, of course, the device may be connected to the mains supply directly or through a transformer.

Claims

1. A door closing device comprising a drive unit with a door-engaging member operable to close the open door but adapted to offer no resistance to the door opening, a timer adapted to cause the drive unit to operate to close the door after a delay period after opening of the door and to be reset after the door is closed, the drive unit being stopped when the door is closed or while the door is closing upon encountering resistance to further closing movement.

2. A device according to claim 1, in which the drive unit comprises an electric motor.

3. A device according to claim 2, in which the motor drives the door-engaging member through a gear box.

4. A device according to claim 2 or claim 3, comprising a clutch which engages drive between the motor and the doorengaging member only when the motor is energised.

5. A device according to claim 4, in which the clutch is a mechanical clutch.

6. A device according to claim 5, in which the clutch operates centrifugally.

7. A device according to claim 4, in which the clutch is electrically operated.

8. A device according to claim 7, in which the clutch is electromagnetically operated.

9. A device according to claim 7, in which the clutch operates electrorheologically.

10. A device according to any one of claims 1 to 9, in which, when the door is closed, the door-engaging member is retracted clear of the door.

11. A device according to claim 10, in which the drive unit reverses to retract the door-engaging member to a position corresponding to an open door when the door is closed or upon encountering resistance to further closing movement.

12. A device according to any one of claims 1 to 11, powered by a battery.

13. A device according to claim 12, powered by a rechargeable battery.