GB2489039A

GB2489039A - Recessed smoke or heat detector

Info

Publication number: GB2489039A
Application number: GB1104559.8A
Authority: GB
Inventors: Simon Edward Walters
Original assignee: DDC Ltd
Current assignee: DDC Ltd
Priority date: 2011-03-17
Filing date: 2011-03-17
Publication date: 2012-09-19
Anticipated expiration: 2031-03-17
Also published as: EP2500639A3; GB201104559D0; GB2489039B; EP2500639A2

Abstract

A recessed smoke or heat detector 1 is arranged to be mounted in a ceiling panel 7. The detector 1 comprises a sensor that is mounted within a cylindrical housing 2. The housing 2 is configured to be pushed through a hole 13 cut in a ceiling panel 7 in order to project into a ceiling void above. The housing 2 is open at its lower end 3 to allow smoke or heat from a room below to reach the sensor in use. The detector comprises a reflector (10,fig.4) that extends from the lower end of the housing 3 towards an upper end of the housing 4. The reflector has an internal light-reflecting surface (17,fig.4) that converges from an open lower end (16,fig.4) towards an upper end of the reflector (19,fig.4). The reflector may be conical in shape and may comprise a parabolic reflector. The sensor is positioned within a space defined by the internal surface of the reflector (10,fig.4). A light source (22,fig.5) may be provided within the space defined by the internal surface of the reflector. An audible alarm device may also be positioned within the reflector.

Description

Recessed Smoke or Heat Detector The present invention relates to a recessed smoke or heat detector.

Modern building regulations require smoke and/or heat detectors to be fitted into all new buildings. Usually the smoke orheat detector will be one of the readily available detectors that surface mount to the underside of the ceiling panel. These are cheap, generally work well and do not require any large holes to be made in the ceiling panel, which can be an important consideration for ensuring that a building

meets the minimum fire rating specifications.

To some, these surface mounted detectors will be unsightly, particularly in modern apartments and houses where it is desirable to maintain clean architectural lines.

As a solution, it is known to provide recessed detectors that are mostly hidden in the ceiling void. One example is a flush mounted smoke detector that is available from Clipsal Australia Pty LtdL under a "Fire Tek" registered trade mark. This device, while being considerably less imposing than the surface mounted detectors, still protrudes below the ceiling in order to position the detection sensors at ceiling level.

Other recessed smoke detectors are suggested in US-A-533341 8 and US-A- 2008/210839. These documents recognise the problem with the surface mounted detectors and provide devices that are hidden from view within the ceiling void. A decorative panel with status LEDs may be the only component of the detector that is visible from below. In the arrangement of US-A-2008/210839, the recessed smoke detector has a large surface diameter of 5 to 7 inches (about 125-175 mm).

JP-A-1 019499 describes a recessed light fitting for fluorescent tubes that incorporates a smoke detector in an upper region of the fitting.

GB-A-2446430 suggests a recessed fitting that is the same size as a standard recessed downlighter' light fitting. The fitting is able to accommodate a variety of electrical fixtures from a downlight to a speaker and a smoke detector.

WO-A-2005/1 24710 describes a smoke detector that is arranged in a housing having a lower body portion that is configured to match the profile of a reflector lamp so that it can be fitted in an existing downlighter fitting. The smoke detector device may still include a lamp in the lower body portion in order to match the working appearance of other downlight fillings installed in the ceiling.

It would be desirable to provide an alternative smoke detector or heat detector that offers an attractive solution to the surface mounted detectors, which does not unduly impair the fire barrier properties of the ceiling panel and which further provides improvements on the arrangements taught in the prior art.

According to the present invention there is provided a recessed smoke or heat detector for mounting in a ceiling panel, the detector comprising a detection sensor that is mounted within a housing, the housing being configured to be pushed through a hole cut in a ceiling panel to project into a ceiling void above, the housing being open at its lower end to allow smoke and/or heat from a room below to reach the detection sensor in use, wherein the recessed detector further comprises a reflector that extends from the lower end of the housing towards an upper end, the reflector having an internal, light-reflecting surface that converges from an open, lower end towards a top of the reflector, the internal surface of the reflector defining a spate into which the detection sensor projects in an upper region of the reflector, the recessed detector further including.a light source that is configured to provide emergency lighting, the emergency light source also being mounted to emit light within the reflector at a position where it can generate a concentrated beam of light using the internal, light-reflecting surface of the reflector, to shine into a room below.

A significant benefit of the recessed detector of the present invention is that it has a much more attractive appearance than the traditional surface mounted detectors, and in many respects it offers significant technical improvements over the known recessed smoke detector arrangements in the prior art described above.

Preferably the recessed detector has a separate reflector that is mounted within the housing. Ideally the reflector is an existing component from a downlight fitting. It is preferably a parabolic reflector having a focal point close to its upper end. The -3.-reflecting surface may be a coating or film of reflective metal such as aluminium or a similar shiny metal or alloy. Alternatively the reflector may be made of aluminium or other reflective metal to present a shiny interior surface. It may have a smooth interior surface or it may include facets or other light dispersing features in its reflector surface to help spread light by creating different reflections. As the benefits of the present invention, at least to an extent, can still be achieved using a less sophisticated reflector, for example, a conical or pyramidal reflector, the present invention is not limited just to parabolic reflectors.

It is also envisaged that the reflector itself could provide the housing of the recessed detector, e.g., where it can be made with sufficient strength and fire resistance.

The lower end of the reflector is open to the room below. Preferably there is no additional cover of any form on the lower end of the reflector, as this allows for better detection of fire and for better illumination of the room below by the light source. The shiny light-reflecting internal surface of the reflector also adds to the visual appeal and sophistication of the recessed detector.

However arrangements are envisaged where there is a fine grille or mesh on the lower end where this does not significantly affect the performance of the detector.

In addition the lower end may be provided with a cover that is transparent to heat (in the case of a heat detector) and is transparent to visible light to emit the emergency lighting! As the detector is likely to work better without such covers and these only serve to create extra manufacturing complexity and cost, while such embodiments are envisaged within the present invention, it is preferred for such covers to be absent.

In one arrangement, the recessed detector is a heat detector and includes a heat detection sensor. The heat detector is suitable for use as a domestic heat detector and meets the relevant building regulations that apply. It can of course be used in commercial premises too. In such heat detector arrangements, the reflector acts to focus heat from the room towards the detection sensor, resulting in much earlier detection of fire. Although parabolic heat collectors are known for scientific instruments, no-one has thought to use a reflector, for example from an existing downlight fitting, as a collector for the heat detection sensor of a domestic heat detector. The reflector is open at its lower end and does not contain additional components, such as a light bulb, between the opening and the heat detection sensor that could interfere with the detection. There is a clear path for heat radiation to reach the detection sensor directly or to be reflected off the internal surface of the reflector onto it. This means that the recessed heat detector is able to offer much more sensitive heat detection than the prior art domestic heat detector devices described above.

In another arrangement, the recessed detector is a smoke detector and is provided with a smoke detection sensor. The smoke detector is suitable for use as a domestic smoke detector and meets the relevant building regulations that apply. It can of course be used in commercial premises too. As a smoke detector, since the upper region of the reflector is, in use, higher than the surface of the ceiling, it provides a higher point where smoke, which has a tendency to rise, will collect if there is a fire, again leading to potentially earlier detection. As the lower end of the recessed detector is open, there is nothing to impede the ingress of the smoke into the reflector to reach the smoke detection sensor.

In a further arrangement, the recessed detector is provided with a heat detector and a smoke detector within the reflector.

In all arrangements, an audible alarm device is preferably incorporated into the recessed detector to emit an alarm warning sound in the event that a fire is detected. Preferably the audible alarm device is a wafer sounder that is back fitted to the upper end of the reflector, preferably centrally within the reflector. In this way the reflector also acts to amplify the sound emitted by the sounder to improve the likelihood that the alarm will be heard by an occupant of the building or by a further person that can raise help. A remote switch may be provided to silence or sound the alarm.

Preferably the emergency light source is positioned generally centrally at the upper end of the reflector. In one arrangement, for example, it is arranged to protrude or shine from the surface of the reflector close to the upper end. Ideally the portion emitting the light is roughly coincident with the focal point of the reflector or close enough to it to generate a concentrated beam of light that an occupant can see by.

The actual focal point of the reflector may be devoid of any components altogether, including the emergency light source, in order to improve the appearance and operation of the detection sensor.

By arranging the components in this way, the reflector, which helps to enhance the heat sensitivity and smoke sensitivity of the detection sensor, and also helps to amplify an audible alarm signal, and also assists to direct light to the floor below in a concentrated beam of light so that a trapped occupant can escape.

The emergency light source is preferably a high brightness LED or LEDs of white or a yellow light. LEDs are preferred because these use less power than other light sources, meaning that the detector will last for longer on a backup battery power supply if the mains electricity supply fails. They also offer substantial brightness but generate only a small amount of heat. This is important in the embodiment where the detection sensor is a heat detector, allowing the detector to be reset easily after a test or false detection when the emergency light source would have been illuminated.

The emergency light source is preferably activated by a controller that is triggered by the output from the detection sensor. The light source is arranged to be switched off during normal operation and only switch on during times of emergency when smoke or excessive heat is detected indicating a fire. If a remote silence/sound switch is provided, then the switch may also switch off/switch on the emergendy lighting together with the audible alarm.

Other forms of detector. sensor could also be incorporated into the recessed detector. In one example a carbon dioxide sensor is set into, the surface of the reflector.

The housing of the recessed detector may be entirely standard for existing downlight applications, and indeed is preferably an existing downlight component having established fire-proofing properties and certification. The housing may include intumescent material, for example, as a collar of intumescent material that is positioned on the housing to expand against the cut edge of the ceiling panel.

Additionally or alternatively, intumescent material may be provided in a rim of the housing at the lower end for sealing against the surface of the ceiling. Intumescent collars or discs may further be provided within the housing to close off ventilation holes, where present, in the event of fire. Separate fire-proofing, for example, in the form of a fire-proof hood may be preferred in certain situations.

The housing preferably also includes a pair of spring clips or other retention device or devices to retain the recessed detector securely in the ceiling panel and prevent the detector dropping out of the ceiling panel during a fire. Spring clips are preferred as they facilitate easy removal of the recessed detector for inspection or maintenance.

The housing is preferably circular in cross-sectiOn, similar to existing downlight fittings, as circular holes are straight forward to cut into a ceiling panel. Preferably the housing is between 80 and 120mm in diameter, and in a most preferred embodiment the housing is 100mm in diameter. However the housing could be square or rectangular if desired with an appropriate reflector design.

The recessed detector is preferably connected to a mains power source (240 or 11 0V, 50Hz AC supply) to charge a rechargeable battery pack, which in turn provides a power source for the detection sensor and the emergency light source.

The detector may instead receive a reduced voltage supply, e.g. a 1 2V or 24V DC supply. A green LED may be provided in the reflector to indicate charging and a red LED may be provided to indicate the alarm status (e.g., red light "on" to indicate that the detector is "active").

The electronic components for controlling the operation of the recessed detector may be provided in a remote gear tray located in the ceiling void beyond the housing. The gear tray may be either mechanically joined to the housing or, more preferably, be provided as a separate item that is pushed up into the ceiling void through a hole in the ceiling before the recessed detector is fitted. A connector may be provided on the electrical leads from the recessed detector for easy connection with a corresponding connector on the gear tray.

Preferably a decorative bezel is provided on or is mountable on the lower end of the housing. The bezel hides from view the housing and the edge of the cut hole that the recessed detector fits into, in order to provide a neat finish. Preferably the bezel snap-fits, screws or twist-locks onto the tower end of the housing and is available in a range of finishes, e.g., white, polished chrome, brushed aluminium, etc., that can be specified by the user, for example, to match other ceiling fittings. In the most preferred embodiments, the decorative bezel is the only visible component of the recessed detector that extends below the surface of the ceiling.

Certain preferred embodiments of the present invention will now be described in greater detail, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a recessed detector prior to fitting into a ceiling panel; Figure 2 is a front view of the recessed detector èhown in Figure 1 (underside view when the detector is in use); Figure 3 is a side view showing the recessed detector mounted in a ceiling panel and projecting into a ceiling void; Figure 4 is an exploded view from the side of a recessed detector; and Figure 5 is a photograph showing the underside of the recessed detector when mounted in a ceiling panel.

As shown in Figure 1, the recessed detector 1 comprises a generally cylindrical housing 2, which is open at its lower end 3 and closed off at its upper end 4. The housing 2 also includes a flange 5 at its lower end 3, which is intended to sit flush against a lower surfaqe of a ceiling panel. The housing 2 extends from the flange 5 into a ceiling void 6 immediately above the ceiling panel 7, such that only the flange 5, or more preferably, a decorative bezel 9, is visible from the room below 8 (see the side elevation in Figure 3).

The housing 2 is made of metal and may be die-cast in aluminium or an aluminium alloy: or could be formed from steel sheet or other suitable material. The housing 2 may be provided with a gun metal grey finish. In Figure 1, the recessed detector I is shown with the reflector 10 removed to show the internal claw clamps 11 that are provided internally within the housing 1 in order to clamp the reflector 10 in place.

A second internal claw clamp 11 is provided on the inside surface of the housing 2 opposite the one shown to secure the reflector properly. On the external surface of the housing, tags 12 are provided for attaching external metal dual-wing clamps (one on each side of the housing 2), which are able to expand and contract to secure the housing 2 in a hole 13 provided in the ceiling panel 7.

As shown in Figure 2, which is a view from underneath the recessed detector 1 looking up into the internal space of the housing 2, three recessed notches 14, preferably spaced symmetrically around the flange 5, are provided in the outer edge of the flange 5 for attaching a decorative bezel 9 thereto. More or less than three notches 14 may be provided as desired. The recessed notches 14 allow lugs (not shown) on the decorative bezel to pass through to grip the upper surface of the flange 5 to retain the decorative bezel 9 in place. The installer aligns the lugs with the recessed notches, pushes the decorative bezel 9 onto the flange 5, then rotates it to lock it in place. The recessed detector 1 can be provided with a range of decorative bezels 9, each having a different finish, for the installer to choose as appropriate.

An important consideration of the recessed detector I is that it should not harm the ceiling's fire-proofing properties by either breaching the fire barrier or through providing a more vOlnerable region where fire can penetrate from the room below 8 into the ceiling void 6. Accordingly, a fire-rated intumescent seal is provided either on the side of the housing 2 to seal against the vertical edges of the hole 13 in the ceiling panel 7 or on the upper surface of the decorative bezel 9 or flange 5 to seal against the underside of the ceiling panel 7 (the intumescent seals are not visible in the figures). Further intumescent seals (also not shown) may be provided in the upper end 4 of the housing 2 to seal ventilation holes provided for ventilation or for cables to pass through. The combination of the metal housing 2 and the intumescent seals which expand and seal any holes in the presence of fire, return the fire rating of the ceiling panel 7 back to an appropriate level to meet the fire-proofing regulations.

Figure 4 is an exploded view from the side of a recessed detector 1. The reflector 10 slots into the internal claw clamps 11 provided within the housing 2 and the decorative bezel 9 fits on to the flange 5 as described above. The metal dual-wing clamps 15 are shown in position fitted onto the tags 12. The housing 2 may taper towards its upper end 4 as shown through having cylindrical portions of steadily reducing diameter. This tapering may make it easier to insert the recessed detector 1 into the ceiling void 6.

The reflector 10 is generally cone-shaped, and in the examples shown is a parabolic reflector having an open lower end 16. The internal surface 17 of the reflector 10 is preferably a metal finish in order to provide a light reflecting surface.

This can be seen more clearly in Figure 5 which is a photograph from below the recessed detector 1. The reflector 10 may include a plurality of facets 18 or other surface relief for reflecting Jight in different directions. At the upper, closed end 19 of the reflector 10, a set of components are fitted. A heat detector 20 protrudes from the internal surface 17 of the reflector 10 at the upper end 19 towards an upper central region of the reflector 2. In other embodiments, this heat detector 20 could be replaced with a smoke.detector (or other detector), or alternatively a smoke detector could be used in conjunction with a heat detector 20 within the reflector 10. In the middle of the upper closed end 19 of the reflector 10, there is provided a back-built wafer sounder 21 to provide an audible alarm to any room occupants. Also shown is an emergency light source 22 in the form of a bright LED which can illuminate white, yellowor similar light of sufficient intensity as illumination to help an occupant within the room to escape. Also provided at the upper end 19 of the reflector 10 is an alarm status LED 23, for example a red LED.

A further LED (not shown) may be provided to indicate that a rechargeable power source is charging from a mains electricity supply.

Also shown in Figure 4 is a remote gear tray 24 which is connected to the housing 2 of the recessed detector 1. The remote gear tray 24 contains a rechargeable battery (not visible) to provide a back-up power supply in the event that the mains power supply fails during a fire. It also contains all the components required to run and control the detector, all provided within a housing which will give some fire protection to the components inside. A cable 25 supplies the recessed detector 1 with mains electricity. If desired, the remote gear tray 24 can be provided as a separate component that is connected to the recessed detector 1 by wires. This allows the remote gear tray 24 to be pushed up through the hole 13 in the ceiling panel 7 before fitting the recessed detector 1.

As can be seen from Figure 5, at least in preferred embodiments of the present invention, the recessed detector 1 offers a much more aesthetically pleasing device than the surface mounted detectors that are usually provided in domestic environments. From a distance, the detector 1 will look like a standard recessed downlight which are common within most properties and offices nowadays.

Standing underneath the recessed detector 1, an observer would see the shiny reflective surface of the reflector 10 and the small coloured LED's indicating that the alarm is active and charging, all of which would be pleasing to the eye. In addition, the recessed detector I offers better detection properties when detecting heat and/or smoke, since heat and smoke wilJ tend to rise to a highest point, namely the upper closed end 19 of the reflector 10. In other words the heat and smoke will tend to be most concentrated at the detectors and so will be detectable sooner using standard detector components. Thus the reflector has many functions, namely to collect and concentrate heat andior smoke for the heat/or smoke detector, to concentrate a beam of tight from the emergency light source to provide illumination that can help an occupant escape, and to amplify the sound from an audible alarm device to alert the occupant of the fire. Moreover, by installing an intumescent fire barrier within the metal fitting, it can be assured that fire safety is still met. By providing the control components beyond the housing the components may survive for longer during a fire than a standard surface mounted plastic detector offering the occupant a greater chance that he/she will hear the alarm and escape the building in the event of a fire. -11 -

Claims

Claims 1. A recessed smoke or heat detector for mounting in a ceiling panel, the detector comprising a detection sensor that is mounted within a housing, the housing being configured to be pushed through a hole cut in a ceiling panel to project into a ceiling void above, the housing being open at its lower end to allow smoke and/or heat from a room below to reach the detection sensor in use, wherein the recessed detector further comprises a reflector that extends from the lower end of the housing towards an upper end, the reflector having an internal, light-reflecting surface that converges from an open, lower end towards a top of the reflector, the internal surface of the reflector defining a space into which the detection sensor projects in an upper region of the reflector, the recessed detector further including a light source that is configured to provide emergency lighting, the emergency light source also being mounted to emit light within the reflector at a position where it can generate a concentrated beam of light using the internal, light-reflecting surface of the reflector, to shine into a room below.
2. A recessed detector as claimed in claim 1, wherein the recessed detector is suitable for use as a domestic smoke detector and the detection sensor is a smoke detection sensor.
3. A recessed detector as claimed in claim 1 or 2, wherein the recessed detector is suitable for use as a domestic heat detector and the detection sensor, or a further detection sensor, is a heat detection sensor.
4. A recessed detector as claimed in claim 1, 2 or 3, wherein the. reflector is a different component to the housing and is mounted within the housing.
5. A recessed detector as claimed in claim 1, 2 or 3, wherein the reflector also provides the housing of the recessed detector.
6. A recessed detector as claimed in any preceding claim, wherein the reflector has a generally conical form.
7. A recessed detector as claimed in any preceding claim, wherein the reflector is a parabolic reflector having a focal point close to its upper end.
8. A recessed detector as claimed in any preceding claim, wherein the lower end of the reflector is open to the room below and there is no additional cover of any form on the lower end of the reflector.
9. A recessed detector as claimed in any of claims 1 to 7, wherein the lower end of the reflector is provided with a grille or mesh.
10. A recessed detector as claimed in any preceding claim, further including an audible alarm device for emitting an alarm warning sound in the event that a fire is detected.
11. A recessed detector as claimed in claim 10, wherein the audible alarm device is a wafer sounder that is back fitted to the upper end of the reflector.
12. A recessed detector as claimed in claim 11, wherein a remote switch is provided to silence or sound the audible alarm device.
13. A recessed detector as claimed in any preceding claim, wherein the emergency light source is positioned generally centrally at the upper end of the reflector.
14. A recessed detector as claimed in claim 13, wherein the emergency light source is arranged to protrude or shine from the surface of the reflector close to the upper end.
15. A recessed detector as claimed in any preceding claim, wherein the emergency light source is a light emitting diode.
16. A recessed detector as claimed in any preceding claim, wherein the housing includes intumescent material.
17. A recessed detector as claimed in claim 16, wherein the housing includes a collar of intumescent material that is positioned to expand against a cut edge of the ceiling panel.
18. A recessed detector as claimed in claim 16 or 17, wherein the housing includes a ring of intumescent material that is provided on a rim of the housing and positioned to expand against a surface of the ceiling.
19. A recessed detector as claimed in any preceding claim, wherein the housing is circular in cross-section.
20. A recessed detector as claimed in claim 19, wherein the housing is between and 120mm in diameter.
21. A recessed detector as claimed in any preceding claim, wherein electronic components for controlling the operation of the recessed detector are provided in a remote gear tray for location in the ceiling void beyond the housing.
22. A recessed detector as claimed in any preceding claim, wherein a decorative bezel is provided for mounting on the. lower end of the housing.
23. A recessed smoke or heat detector as substantially hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.