GB2463944A

GB2463944A - A retaining device comprising a suction cup and valve operable in response to an electrical control signal

Info

Publication number: GB2463944A
Application number: GB0818188A
Authority: GB
Inventors: Manhar Amlani
Original assignee: RED DOT TECHNOLOGIES Ltd
Current assignee: RED DOT TECHNOLOGIES Ltd
Priority date: 2008-10-04
Filing date: 2008-10-04
Publication date: 2010-04-07
Also published as: GB0818188D0

Abstract

A device 12 for holding a first member such as a door 10 in a fixed position relative to a second member 13 such as a wall comprises a suction cup 15 for sealing against a surface 11 which may be a plate on the door 10. The device comprises a valve 17 to allow air into the suction chamber in response to an electrical control signal in order to release the door. The valve is preferably a solenoid valve; the valve may be located within the suction cup or within the surface to which the suction cup seals. The suction cup may be located on the door and seal against a wall or vice versa. The door preferably includes a door closing means to automatically return the door to the closed position upon release of the suction cup. The suction cup device may be used on a fire door and the solenoid valve 17 may be connected to the circuit of a fire alarm system.

Description

DOOR HOLDING DEVICE

This invention relates to a door holding device and more particularly to a door holding device for a fire door.

Fire doors are widely used in buildings to inhibit the spread of fire, for example along corridors. A disadvantage of this is that fire doors can be obstructive and can make it difficult for persons to move from one area to another without opening numerous doors.

Accordingly, it is well known to fit fire doors with devices which normally hold the doors open against an applied bias until a fire is detected. Known door holders comprise a large mains-powered electro-mag net, which is secured to the door or wall and a perro-magnetic plate secured to the door. The electro-mag net is normally energised to engage the plate. When a fire is detected, the electro-magnet is de-energised and the place is released to allow the door to close under the applied bias.

A disadvantage of the above-mentioned devices is that it can be costly and difficult to route mains power to each door. Furthermore, such devices are bulky, costly to purchase, costly to install and consume a significant amount of electrical power.

Typically, such devices are controlled by a fire alarm system which de-energises the devices to close the fire doors when heat or smoke is detected. In order to achieve this, these devices require a control circuit which can control the mains supply to the electro-magnet in response to a low voltage signal generated by the control panel of the alarm system. Such control circuits can be expensive, especially because a degree of electrical isolation is needed between the low voltage control signal and mains. Furthermore, a mains switching device is required.

We have now devised a holder device for a door or other member which alleviates the above-mentioned problems.

In accordance with the present invention, there is provided a device for holding a first member such as a door in a fixed position relative to a second member, the device comprising a suction cup adapted for fitting to one member and for sealing to surface on the second member, the suction cup defining a suction chamber, the device further comprising valve means operable to allow air into the suction chamber in response to an electrical control signal applied to an input thereof.

The holding force between the members is provided by suction and not by an electro magnet and hence less power is consumed. The valve means can be a simple solenoid, which consumes very little power and can be powered by a low voltage supply, for example which can be taken directly from the circuit of a fire alarm system.

The valve means may be arranged to maintain the suction within the suction chamber when electrical power is supplied thereto, such that the door or other member is released in the event of a power failure. However, the valve means consumes such little power that it may continue to hold the door or other member by drawing power from a backup battery, perhaps provided in an alarm system to which the device may be connected.

Preferably the valve means is operable in response to a coded control signal, so that specific doors or members can be released by applying an appropriately-coded control signal thereto.

Preferably the device comprises a plate or other member having a substantially smooth surface against which the suction cup can seal.

The valve means is preferably arranged to control the flow of air through a duct which extends between the suction chamber and atmosphere, the duct extending through either the suction cup or the plate or other member to which the suction cup seals.

Also in accordance with the present invention, there is provided an assembly comprising a door and a holding device as hereinbefore defined arranged to hold the door in an open condition.

Preferably means are provided for biasing the door into a closed position.

Also in accordance with the present invention, there is provided an alarm system comprising a device as hereinbefore defined.

An embodiment of the present invention will now be described by way of an example only and with reference to the accompanying drawings, in which: Figure 1 is a sectional view through a door holding device in accordance with the present invention when fitted adjacent a door; and Figure 2 is a block diagram of a fire alarm system incorporating the device of Figure 1.

Referring to Figure 1 of the drawings, there is shown a door 10 which is biased to its normally closed position by a door closer (not shown). The door 10 is arranged to open forwardly and a plate 11 of steel or other ferro magnetic material is fitted to the front fase of the door adjacent an outer edge thereof.

A door holder unit 12 is fixed to a wall 13 or other structure via a bracket 14. The unit 12 comprises a suction cup 15 of an elastomeric material which faces outwardly and is arranged to engage the plate 11 on the door 10 when the door is opened. The suction cup and plate 11 together define a suction chamber 18. A duct 16 extends through the wall of the suction cup 15 from the suction chamber 18 to a solenoid valve 17. The solenoid valve 17 is connected via a control circuit 19 to a low-voltage control cable 20 which extends from a fire alarm circuit.

Referring to Figure 2 of the drawings, the control circuit 19 is connected, via the cable 20, across a pair of wires 23,24 which extend from a control panel 25 of the fire alarm system. A plurality of heat/smoke detectors 21 and sounders 22 are also connected and parallel across the wires 23,24. The wires 23,24 carry a low voltage which normally energises the solenoid 17 to close the duct 16. In the event that smoke or heat is detected by one of the detectors 21, the control panel 25 sends a coded signal to energise the sounders 22 and to actuate the control circuit 19 to disconnect the supply from the solenoid 17, such that air is admitted into the suction chamber 18: this allows the door 10 to then move away from the suction cup 15 under the applied bias.

Only the doors which are situated adjacent the fire or in other strategic locations can be closed by sending appropriately coded signals to the respective door holder units 12.

S A door holding device in accordance with the present invention is simple and inexpensive in construction, yet is able to reliably hold a door in its open position for extended periods without drawing excessive power and without the need to route mains power to each door.

Claims

CLAIMS1. A device for holding a first member such as a door in a fixed position relative to a second member, the device comprising a suction cup adapted for fitting to the first member and for sealing to surface on the second member, the suction cup defining a suction chamber, the device further comprising valve means operable to allow air into the suction chamber in response to an electrical control signal applied to an input thereof.
2. A device as claimed in claim 1, in which the valve means is comprises solenoid
3. A device as claimed in claim I or claim 2, in which the valve means is arranged to maintain the suction within the suction chamber when electrical power is supplied thereto.
4. A device as claimed in any preceding claim, in which the valve means is operable in response to a coded control signal.
5. A device as claimed in any preceding claim, in which the surface is provided by a plate or other member for fixing to said second member, the plate or other member having a substantially smooth surface against which the suction cup can seal.
6. A device as claimed in any preceding claim, in which the valve means is arranged to control the flow of air through a duct which extends between the suction chamber and atmosphere, the duct extending through the suction cup. * *S*-----*SS*7. A device as claimed in claim 5, in which the valve means is arranged to control the flow of air through a duct which extends between the suction chamber and atmosphere, the duct extending through the plate or other * ** member to which the suction cup seals. * * * *.S*8. A device substantially as herein described with reference to the accompanying drawings.9. An assembly comprising a door and a device as claimed in any preceding claim, in which the door forms said first member, the device being arranged to hold the door in an open condition.10. An assembly as claimed in claim 9, in which means are provided for biasing the door into a closed position.11. An assembly substantially as herein described with reference to Figure 1 of the accompanying drawings.12. An alarm system comprising a device as claimed in any preceding claim. **** S * * ** * *5S*S ----------------------------------------------------------*5S5 * * * *5S * ** * * *S **SS* * S