GB2323528A - Remote control resetting device; fire damper - Google Patents

Abstract

A remote controlled re-setting device for a rotatable member (10) is provided with a mechanical drive means which, in use, is connected to the member to rotate the member through a predetermined angle from an operated position to a reset position. The drive means includes a disengageable drive link (15) comprising a first drive element (16) and a second driven element (17) which are normally disengaged but which on movement of the first element become engaged in driving relation and rotate said member into its reset position thereby effecting the resetting operation, and which on subsequent movement of the first element become disengaged. A particular use for the device is for re-setting a fire damper (10) in a heating and/or ventilation system.

Description

Remote controlled resetting device This invention relates to a remote controlled resetting device which is preferably manually operated.

More particularly but not exclusively, the invention relates to a device for re-setting a fire damper after it has been tripped.

Fire dampers are provided in ducts of heating and ventilation systems as means for controlling the heating and ventilation supply or extract following detection of a fire within a building. On detection of a fire, the fire damper opens or closes the duct, as required, in order to control the effects of the fire.

The damper is an essential element of the heating and ventilation system and is installed in many factories, office buildings, power stations, oil recovery installations and similar places. The damper may be operated at intervals either to test its operation or as a result of a fault in the system. After the damper has been operated, it is necessary to re-set the damper.

Fire dampers are conventionally spring-loaded and require to be rotated through 900 to be reset. It is known to provide flats or another suitable engagement feature on the main damper actuation shaft to enable the damper to be re-set using a spanner or similar tool. The disadvantage of this arrangement is that most heating and ventilation ductwork and their dampers are positioned at elevated positions and thus re-setting them using a spanner or similar tool involves mobile platforms, ladders or scaffolding. Of course, in the event of an actual in-ductwork fire, the damper would require a partial strip down to replace components rather than a simple re-setting procedure.

An object of this invention is to provide a remote controlled means for re-setting the damper. The damper may be re-set quickly from a convenient floor level or walkway. This would eliminate Health and Safety aspects of working at elevated positions and minimise the down time of the heating and ventilation system. Manual operation eliminates the requirement for an external power source. The re-setting means may also be used in different applications, for example, for re-setting a valve mechanism or an automatically movable door or flap, in which a rotatable member requires to be re-set at intervals.

According to the invention there is provided a remote controlled re-setting device for a rotatable member comprising a mechanical drive means which, in use, is connected to the member to rotate the member through a predetermined angle from an operated position to a reset position, wherein the drive means includes a disengageable drive link comprising a first drive element and a second driven element which are normally disengaged but which on movement of the first element become engaged in driving relation and rotate said member into its reset position thereby effecting the resetting operation, and which on subsequent movement of the first element become disengaged.

Preferably the first and second elements of the disengageable link comprise intermeshing gears, the driven gear being a geared segment having a peripheral length of gear teeth which is proportional to the predetermined angle through which said member is to be rotated, and the drive gear being a geared segment having the same peripheral length of gear teeth. By changing the peripheral length of the gear teeth of both geared segments, the angle through which said member is rotated, may be changed.

In one embodiment of the invention the predetermined angle is 90 .

In the preferred embodiment of the invention, the rotatable member to be reset is a fire damper in a duct of a heating and/or ventilation system.

Preferably the fire damper is mounted for rotation on a shaft, and the drive means comprises said disengageable link having the second element adapted for drive connection with the shaft, and the first element connected in driving relation with manually operable means for moving the first element to effect the resetting operation.

The manually operable means is preferably a handwheel connected in driving relation with the first element of the disengageable link via a flexible drive cable.

Indicator means may be provided to give visual indication to the operator that the rotatable member has been reset.

The invention also provides a fire damper in a heating and/or ventilation system provided with a remote controlled resetting device as defined above.

Preferably the remote controlled resetting device is manually operated.

By way of example, a specific embodiment in accordance with the invention will be described with reference to the accompanying drawings in which: Figure 1 illustrates a fire damper in a heating and/or ventilation system provided with a remote controlled resetting device, the damper being in its open rest position; Figure 2 is a front elevation of the resetting device shown in Figure 1, with the cover removed and showing the disengageable link with the drive member in its standby position and the damper closed; Figure 3 is a side elevation of the resetting device as shown in Figure 2; Figure 4 is an underside elevation of the resetting device as shown in Figure 2; Figure 5 is an underside view of the cover of the resetting device showing the end flag aligned with the "tripped" aperture; Figures 6 to 8 illustrate diagrammatically the drive and driven gears in successive stages of the resetting operation; and Figure 9 shows the drive gear over-driven into non-driving relation with the driven gear.

Referring to the drawings, a fire damper 10 is located within a duct 11 of a heating and/or ventilation system. The damper 10 is mounted on a shaft 12 for rotation about a horizontal axis between an open rest position as illustrated in Figure 1, and, in the event of a fire, a closed position in which the damper is vertical and closes the duct 11 in order to reduce or control the effects of the fire.

Alternatively, the damper may be mounted for operation to open the duct in the event of a fire, in which case the damper's closed position is its normal rest position. In each case, the damper 10 is spring urged into its rest position.

At intervals, it is required to test the operation of the damper 10, by tripping the damper to close the duct, in this embodiment. Afterwards, the damper is re-set to its open rest position.

For re-setting the damper, there is provided a remote controlled re-setting device whereby the damper 10 can be easily re-set from floor level 14 or a convenient walkway. In this embodiment, the re-setting device is manually operated.

The re-setting device is a mechanical drive for rotating the damper shaft 12 through 900, in this embodiment. Essentially, the drive includes a disengageable link 15. The link comprises two geared members 16, 17, of which the driven member 17 is a geared segment, substantially a quadrant, having a peripheral length of gear teeth 13 which is proportional to the predetermined angle through which the damper is to be rotated. The other drive member 16 is a geared segment having the same peripheral length, i.e. number and size, of gear teeth as the driven segment 17. The driven segment 17 is connected to the damper shaft 12 by a spring loaded arm 18 and adaptor 19 which engages the conventional spanner flats 20 or, if desired, another suitable engagement feature on the shaft 12. In this embodiment, 780 of gear teeth results in more than 900 rotation of the driven segment 17 to provide an overdrive feature whereby the excess rotation is absorbed by the spring loaded arm 18 and ensures that the damper shaft is moved through its full 900 into its reset position.

The drive segment 16 is driven by a worm 21 and wheel 22 arrangement through a central shaft 23. The worm 21 is driven, via a clutch 28, by a flexible drive cable 24 at the other end of which a handwheel 25 is located within reach of an operator at floor level 14 or on a convenient walkway. As viewed in Figure 2, the drive segment 16 is rotated clockwise by the worm 21. An anti-backwind device is fitted to the worm drive to prevent the drive segment 16 being turned in the wrong direction, i.e. anti-clockwise as viewed. Thereby, the drive segment 16 can only be rotated in one direction and, when not being rotated, is held in an angular position by the worm 21 and wheel 22. The mechanism of the re-setting device is located in a steel box 36 for protection against the ingress of dirt, accidental damage and obstruction of actuation. The box 36, which comprises a cover 37 and a base plate 38, ensures that there are no exposed moving parts which could lead to personal injury.

When the damper 10 is in its tripped, closed position (not shown), the damper may be re-set by the operator turning the handwheel 25 to rotate the drive segment 16 into driving relation (Figures 7 and 8) with the driven segment 17. Rotation of the driven segment 17 turns the damper 10 through 900 intro its open re-set position. At the point of re-set, the spring 27 of the spring-loaded arm 18 allows the drive segment 16 to overdrive the driven segment by compressing the spring 27 until the drive segment disengages from the driven segment 17. This ensures that the damper 10 moves fully into its reset position, as mentioned above. The drive segment 16 is then freely rotated into its predetermined standby position (Figures 2 and 6), which state is shown to the operator by visual indicator means 40. The handwheel 25 is then locked in position.

The visual indicator means 40 are operated via the link 15, in this embodiment, to show to the operator whether the damper is re-set or tripped. The actual indication, which may be the words "RE-SET" and "TRIPPED" or similar indication in wording or varying colour scheme, is displayed on two peripherally spaced panels 46, 47 on a tube 41. The tube 41 is freely mounted for rotation on shaft 42 and connected to the driven segment 17 by a spring 43. The tube 41 also has a radially projecting peg 44 for engagement with a cam plate 45 mounted for rotation with the drive segment 16. In this embodiment, part of the peripheral surface of the tube 41 is exposed through a slot 54 in the cover 37 of the box 36 so that the respective panel 46, 47 showing whether the damper 10 is tripped or reset can be seen by the operator externally of the cover 37. In this embodiment, the tube 41 has an additional end indicator comprising a flag 48 which is mounted on the shaft 42 for rotation with the tube 41 and is visible through apertures 49 in the underside of the cover 37 (Figure 5). The apertures 49 are marked "TRIPPED" and "RE-SET" respectively. For improved visibility by the operator, the flag 48 is brightly coloured.

During the re-setting operation (Figures 7 and 8), the tube 41 and the flag 48 are maintained substantially stationary in their respective tripped positions, thereby indicating to the operator that the damper 10 is still tripped, until the damper is reset. This is achieved by the peg 44 rotating only into engagement with the cam plate 45 on interengagement of the drive and driven segments 16, 17, and the spring 43 stretching during the last part of the re-setting movement of the driven segment 17. When the segments 16, 17 have disengaged and the damper has been re-set, the peg 44 will move off the cam plate 45 and the tube 41 and the flag 48 will be rotated by the spring 43 contracting so that the RE-SET panel 47 on the tube is visible to the operator externally of the cover 37 and the flag becomes aligned with the RE-SET aperture 49.

The operator thereby knows that the damper has been re-set by seeing the RE-SET panel 47 and/or the brightly coloured flag 48 through the RE-SET aperture 49.

Over-winding the drive segment 16 beyond its standby position and into physical contact with the driven segment 17 is possible, but an outwardly protruding peripheral ridge 50 on the trailing end of the driven segment 17 prevents intermeshing engagement of the respective teeth of the two segments 16,17 (Figure 9). At the same time, the ridge 50 is shaped so that it does not prevent the driven segment 17 rotating clockwise to over-ride the drive segment 16 when the damper 10 is tripped. This is necessary because, in this embodiment, the drive segment cannot back rotate.

The re-setting device may be fitted to a fire damper during installation of the heating and/or ventilation system, or to an existing damper arrangement. For installation of the device, a mounting bracket 51 is supplied and fitted to the conventional equipment of the heating and/or ventilation system adjacent to shaft 12 on which the damper 10 is mounted. The bracket 51 has slots 52 for the base plate 38 of the box 36 to be bolted thereto.

For initial installation of the mechanism, there is provided a locating pin 53 for holding the driven segment 17 in its position shown in Figures 2 and 4.

In this position of the driven segment 17, the pin engages a hole 55 in the segment 17 and, in this embodiment, a blind hole 56 in the base plate 38. The adaptor 19 is thereby located for mounting on the damper shaft 12. Alternatively, other means may be provided for clamping the driven segment 17 and the drive adaptor components ready for assembly of the mechanism on the damper drive shaft 12. Then, with the damper 10 in its tripped closed position, the adaptor 19 is engaged with the flats 20 or other engagement feature on the damper drive shaft 12 and the base plate 38 is bolted to the bracket 51, the slots 52 allowing for alignment of the mechanism with the shaft 12. The handwheel 25 is mounted in its desired location within reach of the operator, and the drive cable is attached as required. The locating pin 53 is then removed, and the damper 10 re-set using the handwheel 25.

The invention is not limited to the specific details of the embodiment described above. For example, although the re-setting device is designed to be free of an electrical power supply, limit switches may be fitted, if desired, for indication of the state of the damper, i.e. whether it is "tripped" or 'reset". These limit switches can be in addition to or instead of the visual indicator. Also, the handwheel 25 may be replaced by an electric motor drive for the cable 24, which can be operated from a control panel.

Furthermore, the re-setting device described above may be used in other applications in which a similar rotatable member is operated to rotate through a predetermined angle, and is required to be re-set prior to the next operation. Such a rotatable member may be a valve member, or an automatically movable door or flap.

Claims (12)

1. A remote controlled re-setting device for a rotatable member comprising a mechanical drive means which, in use, is connected to the member to rotate the member through a predetermined angle from an operated position to a reset position, wherein the drive means includes a disengageable drive link comprising a first drive element and a second driven element which are normally disengaged but which on movement of the first element become engaged in driving relation and rotate said member into its reset position thereby effecting the resetting operation, and which on subsequent movement of the first element become disengaged.

2. A device as claimed in Claim 1, wherein the first and second elements of the disengageable link comprise intermeshing gears, the driven gear being a geared segment having a peripheral length of gear teeth which is proportional to the predetermined angle through which said member is to be rotated, and the drive gear being a geared segment having the same peripheral length of gear teeth.

3. A device as claimed in Claim 1 or Claim 2, wherein the predetermined angle is 900.

4. A device as claimed in any one of the preceding claims, wherein stop means are provided which maintain the first and second elements of the link disengaged until the member has been operated and moved to its operated position.

5. A device as claimed in any one of the preceding claims, wherein the rotatable member to be reset is a fire damper in a duct of a heating and/or ventilation system.

6. A device as claimed in Claim 5, wherein the fire damper is mounted for rotation on a shaft, and the drive means comprises said disengageable link having the second element adapted for drive connection with the shaft, and the first element connected in driving relation with manually operable means for moving the first element to effect the resetting operation.

7. A device as claimed in Claim 6, wherein said manually operable means is a handwheel connected in driving relation with the first element of the disengageable link via a flexible drive cable.

8. A device as claimed in any one of the preceding claims, wherein indicator means are provided to give visual indication to the operator that the rotatable member has been reset.

9. A fire damper in a heating and/or ventilation system provided with a remote controlled resetting device as claimed in Claim 1.

10. A fire damper as claimed in Claim 9, wherein the remote controlled resetting device is manually operated.

11. A remote controlled re-setting device for a rotatable member substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

12. A fire damper substantially as hereinbefore described with reference to and as shown in the accompanying drawings.