GB2450991A

GB2450991A - Closure retention and release mechanism with controller and power source

Info

Publication number: GB2450991A
Application number: GB0812581A
Authority: GB
Inventors: Nicholas Roger Charles Goddard
Original assignee: Stephenson Gobin Ltd
Current assignee: Stephenson Gobin Ltd
Priority date: 2007-07-09
Filing date: 2008-07-09
Publication date: 2009-01-14
Anticipated expiration: 2028-07-09
Also published as: GB0713293D0; GB2450991B; GB0812581D0

Abstract

A system (10) comprises a controller, a closure retention and release mechanism (10) and an electrical conduit (74). The closure retention and release mechanism may comprise an engagement plate (12) mountable to a closure and a magnetic retention and release device (14) mountable at a position remote from the closure. The magnetic retention and release device (14) may comprise a body (22) having spaced apart first and second portions (28,30) of ferrous material, a magnet (24) mounted between said portions (28,30) and an actuator powered by a power source and operable to move the magnet (24) relative to said portions. The magnet (24) is movable between a first position where each pole (40,42) of the magnet (24) is located in a respective portion of the body (22) and a second position where each pole (40,42) is not located in a respective portion of the body (22). The door may be released in the second position, for example in response to a fire.

Description

I

P7I7WG-I Improvements in or Relating to Closure Retention and Release Mechanisms The present invention relates to an improved system for the control and operation of a closure retention and release mechanism and in particular, though not exclusively, to a door holder for a tire door.

Fire doors are installed in buildings to prevent the spread of smoke and fire through the building in the event of a fire. In order to serve their purpose the doors must be closed, however this may be inconvenient during periods when the building is occupied, for example an office building, or times when there is significant movement of people within the building, for example hospital, nursing home or hotel building during periods when the occupants are awake. A common solution involves the use door holder devices which are operable to maintain the fire doors in an open state but are arranged to release the doors in the event of a fire alarm being raised. The doors thus released are able to close under the influence of a separate or integrated closing mechanisms. In such a system the door holders are typically required to be hard wired to the fire alarm system.

Numerous forms of door holder mechanisms presently exist. The most common system includes an electromagnet mounted on the floor, ceiling, or wall adjacent a fire door, and a ferrous plate mounted on the door. The plate, and hence the door, will remain held by the magnet for as long as it is energised. The door is released when the power supply to the electromagnet is cut. A similar system incorporates the combination of a permanent magnet and an electromagnet. The door is retained by the permanent magnet until the electromagnet is energised. The electromagnet is arranged to oppose the filed of the permanent magnet and thereby cause the door to be released.

Known door closing mechanisms may include a spring and a hydraulic damper, the hydraulic damper being arranged to control the closing speed of the door. In such an instance a door holder mechanism may be incorporated into the hydraulic damper to block the flow of fluid iherethrough and thereby maintain the door in an opened state.

According to the first aspect of the present invention there is provided a system for the operation of a closure retention and release mechanism, the system comprising a controller, a closure retention and release mechanism and an electrical conduit connecting the controller to the closure retention and release mechanism, the closure retention and release mechanism comprising an engagement plate mountable to a closure and a magnetic retention and release device mountable at a position remote from the closure, the mechanism being operable to either retain the closure in an open position wherein the plate is attracted to and contacts the device or to no longer attract the plate so as to permit the closure to close, wherein the magnetic retention and release device comprises a body having spaced apart first and second portions of ferrous material, a magnet having north and south poles mounted between said portions and actuation means operable to move the magnet relative to said portions, wherein the magnet is movable between a first position where each pole of the magnet is located fully in a respective portion of the body and a second position where each pole is not located fully in a respective portion of the body and the plate is thus no longer attracted to the device, wherein further the closure retention and release mechanism is provided with a power source for the actuation means.

The power source may comprise an energy storage means such as a battery or a capacitor.

The battery may, for example, comprise a replaceable battery or a rechargeable battery. In the case of a rechargeable battery, the power source may be connected to the electrical conduit so that the battery may be recharged by power supplied via the electrical conduit.

Where a capacitor is provided, this too may be connected to the electrical conduit so that the capacitor may be charged by power supplied via the electrical conduit.

The system preferably also includes a detector operable to detect the presence of a fire. For example, the detector may be a smoke detector. Alternatively, the detector may be configured so as to detect other characteristics of a fire such as heat and/or flames. The system may also be provided with a sounder to alert persons as to the presence of a fire.

In the first position of the magnet relative to the body portions the magnet is able to act through the body portions to attract and retain an engagement plate of a closure, such as a door. In the second position of the magnet relative to the body portions the magnet is unable to act through the body portions, either as a result of its orientation relative to and/or spacing from the body portions, and hence is unable to attract and retain an engagement plate.

The body portions may be spaced from one another by the provision of a non-ferrous spacer positioned therebetween. In an alternative embodiment an air space may be provided between the body portions. In such an embodiment the body portions may be supported in a holder or frame work which maintains the spacing between the blocks. Preferably the body is provided with an engagement face which, in use, is adapted to interface with a portion of a closure. The engagement face may be provided in an extension of one of the body portions. Preferably both body portions may include an extension, with the engagement face being provided partially upon each extension.

Preferably the magnet is located in a recess defined between the body portions. The recess may preferably be a through hole of the body. In such an embodiment the magnet may be substantially cylindrical and mounted for rotation in the through hole. Rotation of the magnet may preferably be effected by the provision of a motor arranged to drive a rotation mechanism. The rotation mechanism may comprise a gear train arranged between an output of the motor and the magnet. The gear train may comprise a worm gear connected to an output shaft of the motor, an drive gear connected to the magnet and a reduction gear provided intermediate the worm and drive gears. The gear train may include one or more additional gears.

The motor may be reversible so as to permit the magnet to be rotated both clockwise and anticlockwise. Alternatively the motor may operate in a unidirectional manner so as to rotate the magnet in a unidirectional manner. In both embodiment the motor includes a control system operable to ascertain the position of the magnet relative to the body and to cease the operation of the motor when the magnet reaches a desired position. The control system may include one or more limit switches.

In an alternative embodiment the magnet may be movable in a linear manner relative to the body. In such an embodiment the mechanism includes a motor and a reciprocating motion mechanism arranged to move the magnet between the first and second positions.

According to a second aspect of the present invention there is provided a method of controlling a closure retention and release mechanism the method comprising the steps of: providing a controller; providing a closure retention and release mechanism having a power supply and which switchable between closure retention and release states, the mechanism being connected to the controller by an electrical conduit; transmitting a switch signal from controller to the mechanism via the conduit to switch the device from the closure retention state to the closure release state.

In a preferred embodiment, the mechanism is configured to send an acknowledgement signal to the controller via the conduit upon receipt of the switch signal.

The method preferably includes the additional step of recharging the power supply from the electrical conduit. The mechanism is preferably configured so as to monitor the state of the electrical conduit. In the event that the mechanism detects an interruption in the electrical conduit, then the mechanism will switch to the closure release state as a matter of precaution.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a side view of a closure holding mechanism of a known type; Figure 2 is a further side view of the mechanism; Figure 3 is an other side view of the mechanism; and Figure 4 shows a schematic representation of a mechanism incorporated into an analogue addressable control system.

Referring firstly to figures 1 to 3 there is shown a closure holding mechanism generally designated 10. The device comprises a plate 12 and a magnetic retention/release device 14.

The plate 12 is attachable to a door by any appropriate means such as, for example screws or like fasteners. The plate 12 comprises a base 16, an engagement face portion 18 and a flexible neck 20 connecting the base 16 to the face portion 18. The flexibility of the neck ensures that minor misalignment between the plate 12 and mechanism 14 can be accommodated. The face portion 16 of the plate 12 at least is comprised of a ferrous metal such as steel. The ferrous metal may be provided in an insert mounted to the face portion 16. Alternatively the plate 12 in its entirety may be comprised of a ferrous metal.

The device 14 comprises body 22, a permanent magnet 24 and an actuation mechanism 26.

The body 22 is comprised of two blocks 28,30 of ferrous metal such as, for example, steel.

The blocks 28,30 sandwich, and hence are separated by, a member 32 comprised of a non-magnetic material such as, for example, aluminium alloy. In an alternative embodiment the blocks 28,30 may be mounted relative to one another such that an air gap instead of the non-magnetic material is provided therebetween. In such an embodiment the blocks 28,30 may be mounted in a non-magnetic holder The blocks 28,30 include an engagement face 34. In the embodiment shown the engagement face 34 is provided on a projection 36 of each block 28 either side of the non-magnetic member 32.

The device 14, in use, is mounted to a surface adjacent the door which is remote from both the door and the door frame but is contactable by the door when it is opened to a desired extent. For example, the device 14 can be mounted on a wall. Alternatively, the device 14 can be mounted on the floor in a similar manner to a door stop. Where the device 14 is used in conjunction with other types of closures, such as windows, the device may be similarly sited with respect to the window and window frame.

The permanent magnet 24 is positioned in a through hole 38 provided in the blocks 28,30 and non-magnetic member 32. The through hole 38 is positioned such that equal portions thereof are provided in each block 28,30. The magnet 24 has both north and south poles 40,42 and is rotatable in the through hole between a first position where the poles 40,42 are aligned with the non-magnetic member 32 (figure 1) and a second position where the poles 40,42 are aligned transverse to the 32 such that each pole 40,42 is positioned in a respective block 28,30 (figure 3).

The release/retention device 14 comprises a motor 44 having a drive shaft 46 and a gear arrangement 48. The gear arrangement 48 comprises a worm gear 50 mounted on the drive shaft 46, a reduction gear 52 and a drive gear 54. The reduction gear 52 comprises a large diameter portion 56 and a concentric smaller diameter portion 58. The periphery of each portion 56,58 is toothed such that the portions 56,58 mate respectively with the worm gear and drive gear 54. The drive gear 54 is connected to the permanent magnet 24 via a spindle 60. It will thus be understood that operation of the motor 44 causes the drive shaft 46 and worm gear 50 to rotate. Rotation of the worm gear 50 causes the reduction gear 52 to rotate which in turn causes the drive gear 54 to rotate. Rotation of the drive gear results in rotation of the magnet 24 within the through hole 38. The arrangement of the gears 50,52,54 is such that the rotational speed of the drive gear 54 is less than that of the drive shaft/worm gear 46,50, while the torque applied to the permanent magnet 24 is greater than that applied to the drive shaft 46 by the motor 26. The embodiment shown in figures 1 to 3 the gear arrangement includes a single reduction gear 52. It will be appreciated that one or more additional gears may be incorporated in the gear train between the drive shaft 46 and drive gear 54 to achieve the desired rotation characteristics for the magnet 24.

The motor 26 may be reversible so as to permit the magnet 24 to rotated both clockwise and counter-clockwise. Alternatively the motor 26 may rotate in a unidirectional manner. In such an embodiment the motor 26 will include appropriately configured limit switches to halt the rotation of the magnet 24 substantially every 90 degrees.

Operation of the mechanism 10 will now be described. During normal operation the magnet 24 is aligned with the blocks 28,30 as shown in figure 3. The position of the magnet 24 in figure 3 may be referred to as the retention position. As described above the poles 40,42 of the magnet 24 are each positioned in a respective block 28,30. As such, each block 28,30 effectively becomes an extension of the respective pole 40,42 with the result that magnetic lines of force, indicated by broken lines 62, extend from the north pole 40 to the south pole 42. The magnet 24 and block 28,30 arrangement is thus able to attach ferrous metal, such as the plate 12 thereto. As described above the plate 12 is connected to a closure such as a door, while the release mechanism 14 is mounted to a wall behind the closure. The strength of the magnet 24 is such that the plate 12 and closure is held securely thereto. The strength of the magnet 24 is selected such that the attractive force experienced by the plate 12 is greater than any force applied to the door by a spring biased or hydraulic closing mechanism.

Typically the strength of the magnet 24 may be chosen such that attractive force applied to the plate is greater than any externally applied forces, such as for example wind loading, which may reasonably be expected to experienced by the closure. As a safety precaution however, the strength of the magnet 24 may be such that the attractive force experienced by the plate 12 may be overcome in the event of an emergency by a person applying sufficient force to the closure In the event that it is desired to separate the plate 12 from the mechanism 14 in a controlled manner the motor 26 can be operated to rotate the magnet 24 through substantially 90 degrees to the position shown in figure 1. The position of the magnet 24 in figure 1 may be referred to as the release position. With the magnet 24 in this position both of the poles 40,42 provided partially in each block 28,30 and as such the magnetic lines of force are fully contained within the blocks 28 30. The magnet 24 is therefore unable to attract ferrous metal at or near the external faces of the blocks 28,30. The device 14 is thus unable to retain the plate 12 and closure to which the plate 12 is attached. The closure is thus able to be closed either manually or more preferably under the influence of a closing mechanism associated with the closure. When it is desired to reactivate the device 14, the motor 26 may be operated to rotate the magnet to the position shown in figure 3. This may be achieved either by reversing the motor 26 or continuing the rotation of the motor 26 in the same direction as before.

The device 14 is preferably integrated into a control system which controls the operation of the motor 26. For example the control system may be configured to move the magnet 24 at predetermined time intervals. Such a system may be particularly useful in a building which is substantially unoccupied during the night. In such a circumstance the control system may be configured to move the magnet 24 to the release position at a predetermined time of the evening to enable a closure to close. At a predetermined time of the morning the magnet 24 may be moved to the retention position ready to retain the closure when it is opened for the first time. The control system is preferably also able to move the magnet 24 to the release position in the event of an emergency such as a fire alarm being raised.

Figure 4 shows a schematic view of a control system, generally designated 70, which incorporates a mechanism 10 of the type described above. The control system 70 is of the analogue addressable type and comprises a control panel 72 from which extends a closed loop wire conduit 74 to which are connected a sounder 76, a smoke detector 78 and the device 14 of the closure holding mechanism 10. For the sake of simplicity the loop 74 is illustrated as having a single sounder 76, detector 78 and closure holding mechanism 10. It will be appreciated that in use the ioop 74 may include multiple sounders 76, detectors 78 and mechanisms 10, and that the control panel 72 may be provided with multiple loops 74.

The wire conduit forming the loop 74 is used to supply both electrical power and control signals from the control panel 72 to each item on the loop 74. Additionally, each item on the loop 74 is able to send signals through the ioop 74 to the control panel 72. Each item on the loop 74 is able to provide a status report to the control panel 72 and thus report any faults which may arise with the item. Each item on the loop 74 is provided with a unique address which enables the control panel 72 to send control signals to a specified item or group of items, and permits each item to identify itself to the control panel 72 when reporting a fault. The mechanism 10 is provided with an appropriate control interface which is able to receive and interpret signals sent through the loop 74 by the control panel 72 and to operate the mechanism 10 in response to the receipt of appropriate signals.

A typical analogue addressabLe fire control system operates at a voltage of between 18 to 50 Volts DC. The maximum current draw for an item on the loop 74 of such a system is typically no greater than 5 mA, and the current draw of a device will limit the number of such devices that can be incorporated into a loop 74. Known electromagnetic door holders typically draw a Continuous current of 20 to 50 mA at 24V, and hence are not suitable for incorporation into a low current loop 74 of the type described. This necessitates the provision within a building of a separate high current loop for the door holders which increases both complexity and Cost of the building fire control system.

As described above, the closure holding mechanism 10 does not operate on an electromagnetic principal, and instead utilises the movement of a permanent magnet 24 within a ferrous body 22 by a motor 44. The power requirement of the motor 44 is less than that of an electromagnetic door holder, and the motor 44 is not required to be powered continuously. The power requirement of the motor 44, while less than that of an electromagnetic door holder, is typically greater than that which can be supplied by the control system 70. The closure holding mechanism 10 is thus provided with a dedicated power source 80. The power source may comprise, for example, a replaceable battery, a rechargeable battery or a capacitor. In the case of a replaceable battery, the mechanism I 0 is preferably configured so as to be able to monitor the condition of the battery and alert the control panel 72 when it is determined that the battery requires changing. The mechanism may further be configured to move the device to a safe state whereby the closure is released if it is determined that condition of the battery is critical. In the case of a rechargeable battery or capacitor, the power source 80 is provided with a connection 82 to the loop 74 which enables current to be supplied from the system 70 to recharge the battery or charge the capacitor as appropriate.

With reference to the control of the mechanism 10 by the control panel 72, the following protocols may be employed. In a first embodiment, the mechanism 10 may be configured to move between operative states in response to a dedicated switch signal being sent by the control panel 72. The mechanism 10 may be configured so as to send an acknowledgement signal to the control panel 72 in response thereto. The mechanism 10 may further be configured so as to monitor the voltage present in the loop 74. In the event of the voltage in the loop 74 being interrupted, for example as a result of damage to the loop wiring or power supply, the mechanism 10 may switch to the closure release state as a precautionary step, thereby allowing the closure to close.

In an alternative embodiment, the control panel 72 may emit a periodic control signal which is intended to be received by the mechanism 10 via the loop 74. The control signal may comprises a plurality of equally spaced pulses. Upon initial start up of the system 70, or the addition of a new mechanism 10 to the system 70, the mechanism 10 "listens" for a predetermined number of repetitions of the control signal. In doing so the mechanism 10 is able to determine the average time t between each pulse. Once the period t has been determined, the mechanism 10 enters a hibernation mode whereupon it alternates between an active state whereupon it is awake and able to receive the control signal and an inactive state whereupon it is not able to receive the control signal. The switching of the mechanism from the inactive to the active state is synchronised with the period t of the control signal. Thus the device enters the active state shortly before it expects to receive a pulse of the control signal. Upon receiving the control signal the device re- enters the inactive state.

During this normal mode of operation wherein the mechanism 10 cycles between the active and inactive states, the mechanism 10 remains in its original operational state holding a closure open.

in the event that the mechanism 10 does not receive a pulse of the control signal as expected, then the mechanism 10 enters an alert state whereupon it remains active and awaits the next scheduled pulse of the control signal. If the next scheduled pulse is received then the mechanism 10 reverts to cycling between the active and inactive states as described above. In the event that a predefined number of pulses are not received by the mechanism 10, then the mechanism 10 acts to change its operative state and thereby release the closure, In an alternative embodiment the mechanism 10 may be arranged such that it acts to change its operative state if a single pulse of the control signal is not received. It will be understood that in such an embodiment the mechanism 10 would not enter the alert state described above.

In the event of a fire alarm being raised, the control panel 72 instruct the release of the closure retained in an open state by the mechanism 10. In such a circumstance the control panel 72 ceases the transmission of the control signal thereby promoting the mechanism 10 to change its operative state. Ii will be appreciated that the control signal may be stopped in alternative circumstances. For example, the control signal may be stopped in the event of a power failure at the control panel 72 In such an event the closure is permitted to close as a precaution. In yet an alternative embodiment the control signal may be stopped at a predetermined time of the day, for example after working hours, to permit closure of the closure.

Claims

Claims I. A system for the operation of a closure retention and release

mechanism, the system comprising a controller, a closure retention and release mechanism and an electrical conduit connecting the controller to the closure retention and release mechanism, the closure retention and release mechanism comprising an engagement plate mountable to a closure and a magnetic retention and release device mountable at a position remote from the closure, the mechanism being operable to either retain the closure in an open position wherein the plate is attracted to and contacts the device or to no longer attract the plate so as to permit the closure to close, wherein the magnetic retention and release device comprises a body having spaced apart first and second portions of ferrous material, a magnet having north and south poles mounted between said portions and actuation means operable to move the magnet relative to said portions, wherein the magnet is movable between a first position where each pole of the magnet is located fully in a respective portion of the body and a second position where each pole is not located fully in a respective portion of the body and the plate is thus no longer attracted to the device, wherein further the closure retention and release mechanism is provided with a power source for the actuation means.
2. A system as claimed in claim 1, wherein the power source is a battery.
3. A system as claimed in claim 2, wherein the battery is rechargeable by power supplied via the electrical conduit.
4. A system as claimed in claim 1, wherein the power source is a capacitor.
5. A system as claimed in claim 4, wherein the capacitor is chargeable by power supplied via the electrical conduit.
6. A system as claimed in any preceding claim and including a detector operable to detect a fire.
7. A system as claimed in any preceding claim and including a sounder.
8. A mechanism as claimed in any preceding claim wherein the second position of the magnet corresponds to a position where each pole of the magnet is located partially in both portions of the body.
9. A mechanism as claimed in any preceding claim wherein the second position of the magnet corresponds to a position where each pole of the magnet is located equally in both portions of the body.
10. A mechanism as claimed in any of claims I to 7 wherein the second position of the magnet corresponds to a position whereupon the magnet is moved away and is spaced from the body.
11. A mechanism as claimed in any preceding claim wherein the body portions are spaced from one another by the provision of a non-ferrous spacer positioned therebetween.
12. A mechanism as claimed in any of claims I to 10 wherein the body portions are spaced from one another by the provision an air space between the body portions.
13. A mechanism as claimed in any preceding claim wherein the body portions are supported in a holder or frame which maintains the spacing between the body portions.
14. A mechanism as claimed in any preceding claim wherein the body is provided with an engagement face which, in use, is adapted to interface with the plate.
15. A mechanism as claimed in claim 8 wherein the engagement face is defined by an extension of one of the body portions.
16. A mechanism as claimed in claim 9 wherein both body portions include an extension, the engagement face being provided partially upon each extension.
17. A mechanism as claimed in any preceding claim wherein the magnet is located in a recess defined between the body portions.
18. A mechanism as claimed in claim 17 wherein the recess is defined by a through hole of the body.
19. A mechanism as claimed in claim 18 wherein the magnet is substantially cylindrical.
20. A mechanism as claimed in claim 18 or claim 19 wherein the magnet is mounted for rotation in the through hole.
21. A mechanism as claimed in claim 20 wherein the magnet is rotatable by the provision of a motor arranged to drive a rotation mechanism.
22. A mechanism as claimed in claim 21 wherein the rotation mechanism includes a gear train arranged between an output of the motor and the magnet.
23. A mechanism as claimed in claim 22 wherein the gear train includes a worm gear connected to an output shaft of the motor, a drive gear connected to the magnet and a reduction gear provided intermediate the worm and drive gears.
24. A mechanism as claimed an any of claims 21 to 23 wherein the motor is reversible so as to permit the magnet to be rotated both clockwise and anticlockwise.
25. A mechanism as claimed in any of claims 21 to 23 wherein the motor is operable in a unidirectional manner so as to rotate the magnet in a unidirectional manner.
26. A mechanism as claimed in any of claims 21 to 25 wherein the motor includes a control system operable to ascertain the position of the magnet relative to the body and to cease the operation of the motor when the magnet reaches a desired position.
27. A mechanism as claimed in claim 26 wherein the control system includes one or more limit switches.
28. A mechanism as claimed in any of claims I to 19 wherein the magnet (24) is movable in a linear manner relative to the through hole of the body.
29. A method of controlling a closure retention and release mechanism the method comprising the steps of: providing a controller; providing a closure retention and release mechanism having a power source and which is switchable between closure retention and release states, the mechanism being connected to the controller by an electrical conduit; transmitting a switch signal from controller to the mechanism via the conduit to switch the device from the closure retention state to the closure release state.
30. A method as claimed in claim 29 wherein the closure retention and release mechanism sends an acknowledgement signal to the controller via the conduit upon receipt of the switch signal.
31. A method as claimed in claim 29 or claim 30 wherein the method includes the additional step of recharging the power supply from the electrical conduit.
32. A method as claimed in any of claims 29 to 31 wherein the mechanism is configured so as to monitor the state of the electrical conduit and in the event that an interruption in the electrical conduit is detected, then the closure retention and release mechanism switches to the closure release state as a matter of precaution.