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WO2008109933A1 - Particle detection apparatus - Google Patents

Particle detection apparatus Download PDF

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Publication number
WO2008109933A1
WO2008109933A1 PCT/AU2008/000316 AU2008000316W WO2008109933A1 WO 2008109933 A1 WO2008109933 A1 WO 2008109933A1 AU 2008000316 W AU2008000316 W AU 2008000316W WO 2008109933 A1 WO2008109933 A1 WO 2008109933A1
Authority
WO
WIPO (PCT)
Prior art keywords
detection chamber
air
detecting particles
air sample
detector
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AU2008/000316
Other languages
French (fr)
Inventor
Nitin Vayeda
Mark Brian Dockrill
Adrian Charles Ian Scott-Murphy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xtralis Technologies Ltd Bahamas
Original Assignee
Xtralis Technologies Ltd Bahamas
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2007901284A external-priority patent/AU2007901284A0/en
Application filed by Xtralis Technologies Ltd Bahamas filed Critical Xtralis Technologies Ltd Bahamas
Publication of WO2008109933A1 publication Critical patent/WO2008109933A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
    • G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
    • G08B17/113—Constructional details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G01N15/075—Investigating concentration of particle suspensions by optical means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/10—Investigating individual particles
    • G01N15/14—Optical investigation techniques, e.g. flow cytometry
    • G01N15/1434—Optical arrangements
    • G01N2015/1438—Using two lasers in succession

Definitions

  • the present invention relates to particle detection. It is convenient to describe the preferred embodiments in relation to an apparatus specifically adapted for detecting smoke particles. However, the present invention should not be considered as being limited to that exemplary application.
  • Fire protection and suppressant systems which operate by detecting the presence of smoke and other airborne pollutants are well known. Upon a threshold level of smoke being detected, an alarm may be activated and operation of a fire suppressant system may be initiated. While the fire itself will cause damage, considerable damage can also be caused by operation of the fire suppression system, and subsequent removal of the suppressant can be quite hazardous.
  • a detection system that with sufficient sensitivity to detect an abnormal level of particles in the air is advantageous as it enable action to be taken at a very early stage before the onset of an actual fire.
  • One such method of providing an early warning of a fire is based on the use of a particle detector which detects airborne particles on the basis of the amount of light scattered from a beam of radiation such as the smoke detectors sold under the trade mark VESDA by Xtralis Pty Ltd, provide a highly sensitive way of detecting particles.
  • smoke detectors operate by transmitting a beam of light, typically from a laser, or flash tube, through a stream of air in which particles may be present.
  • a photo-detector such as a photodiode or other light sensitive element is placed at a predetermined position with respect to illuminated volume and the amount of scattered light received by the photo-detector is used to determine the level of particulate matter in the airflow.
  • Such smoke detection systems draw air samples through a pipe network consisting of one or more sampling pipes with sampling holes installed at positions where smoke or particles can be collected. Air is drawn in through the sampling holes and along the pipe by means of a fan and is directed through a detector at a remote location.
  • the present invention provides an apparatus for detecting particles, including: at least one detection chamber having means to detect particles in at least one region of interest within the chamber; at least one inlet port for introducing an air sample into a respective detection chamber; and at least one outlet from the detection chamber; wherein the detection chamber is configured such that the air sample enters the inlet port in a first direction and after traversing the region of interest flows towards the outlet at least partially in a direction other than the first direction.
  • the apparatus further includes a flow detector located between an air inlet to the apparatus and the detection chamber with the air sampling flowing through the flow detector in the first direction.
  • an apparatus for detecting particles including: at least one airflow path including, at least one inlet port for introducing an air sample into a respective detection chamber; and means to exhaust the air sample(s) from the detection chamber(s) such that the air sample flows through the detection chamber; at least one light source configured to illuminate a volume of the detection chamber; at least one photo-detector able to view at least part of the illuminated volume of the detection chamber and an optical surface of the detection chamber, to detect particle in the detection chamber; wherein the airflow path is formed in at least two parts such that a portion is removable, whereby the removable portion includes an optical surface of the detection chamber viewable by the photo-detector.
  • the apparatus is provided with two light sources, preferably two laser beams or LEDs, and respective photo-detectors.
  • the optical surfaces viewed by the separate photo- detectors are preferably spaced apart.
  • the removable portion of the detection chamber forms a removable cartridge including the detection means.
  • the inlet port and the outlet to the exhaust means are located on a same side of the detection chamber.
  • the removable cartridge is therefore able to be inserted in a single action.
  • the cartridge is able to be engaged with the housing by a single downward or sliding movement. Due to this arrangement the two parts of the detection chamber are only required to seal in a single direction.
  • the housing and the chamber cartridge are shaped in a complementary manner such that the detection chamber cartridge cannot be attached to the housing when misaligned or incorrectly orientated.
  • the apparatus preferably includes multiple inlet ports and respective detection chambers.
  • the detector can include a common exhaust manifold into which air from each of the detection chambers is output from the detection chamber.
  • the removable portion of the detection chamber can forms a removable cartridge including one or more of, a photo detector and light source corresponding to an optical surface.
  • the airflow passes into the inlet port and out of the outlet to the exhaust means in different directions.
  • the present invention provides an apparatus for detecting particles, including:
  • a fan and/or filter cartridge removable from the housing
  • the interconnection between the cartridges provides a fluid communication path between the cartridges.
  • the interconnection between the cartridges may be an electrical and or data connection between the cartridges.
  • the present invention provides a smoke detector having multiple detection chambers, including: multiple air inlet ports for introducing air samples into respective multiple detection chambers;
  • apertures are configured to minimise leakage of air samples through the apertures between adjacent detection chambers.
  • the smoke detector includes an ultrasonic flow detector that is preferably located upstream from the adjacent detection chambers.
  • the smoke detector also preferably includes a fan, which is located downstream of the detection chambers and also preferably downstream of the common manifold.
  • the detection chambers may include a plurality of light sources, e.g. lasers. It can also include two apertures between the detection chambers.
  • the inlet ports and the manifold are both connected to the detection chamber from a same side of the detection chamber, such that the air sample flows in a first direction from the inlet port into the detection chamber and after traversing the detection chamber flows to the exhaust means in a direction opposite to the first direction.
  • the inlet ports preferably lie parallel to the manifold. Such an arrangement allows the detection chamber to create a loop between the inlet ports and the manifold.
  • the present invention provides an apparatus for detecting particles in an air sample, including:
  • a housing including an air sample inlet and an air sample outlet and means to define an airflow path between the inlet and outlet, air sample inlet being configured to introduce an air sample into the apparatus in a first direction;
  • At least one particle detector interacting with the air sample between the inlet and outlet to detect particles in the air sample; wherein the means to define the airflow path include means to direct the airflow in a direction other than the first direction, to minimise the width of the housing along the first direction.
  • the means to define the airflow path defines at least two portions of the airflow path through which the airflow moves in opposite directions. Most preferably the two portions are aligned along the first direction.
  • the means to define the airflow path preferably defines at least one substantially u-shaped bend in the airflow path.
  • the housing includes a plurality of housing components that cooperate to define the airflow path.
  • the housing includes a chassis defining part of the airflow path and one or more removable housing components removably mounted to the chassis that define part of the airflow path.
  • the at least one particle detector is incorporated in a removable housing components.
  • the flow path through the housing component including the at least one particle detector includes one or more bends that changes the direction of airflow.
  • the net change of direction of the airflow between the input and output of the housing component including the at least one particle detector is 180 degrees.
  • a removable housing component can be removed and/or coupled with the chassis without the disconnection and/or connection of additional components, such as additional wiring, hoses or the like between them.
  • the removable housing component can be engaged and/or disengaged with the chassis by movement along or about a single axis.
  • the movement along or about a single axis may be preceded by a step of aligning the removable housing component with the chassis.
  • the apparatus preferably includes a flow sensor for determining a flow rate in the airflow in the airflow path.
  • the apparatus includes a plurality of air sample inlets and at least one air sample outlet, and means to define a plurality of airflow path between a respective one of the air sample inlets and an outlet.
  • a particle detector that which interacts with each airflow is incorporated in a common removable component.
  • the particle detector corresponding to each airflow shares one or more components with a particle detector for another airflow.
  • the particle detectors for the plurality of airflows operates by detecting scattered light and share a common light source.
  • the present invention provides an apparatus for detecting particles in an air sample, including, a plurality of air sample inlets and air sample outlets in communication with a common air volume, and means to define a plurality of airflow path between a respective one of the air sample inlets and the common volume, at least one particle detector interacting with each air sample between its inlet and outlet to the particle detector being configured to detect particles in each air sample, the particle detector including, a shared light source for illuminating a volume in two or more of the air samples, and at least one light detector for each air sample that is configured to detect the level of light scattered from at least part of the illuminated volume in each air sample; the means to define a plurality of airflow paths including apertures between adjacent airflow paths through which a shared light source illuminates a volume in two or more of the air samples, wherein the apertures between adjacent airflow paths is positioned such that, in the event that a different air pressure exists in each airflow their respective air sample inlets, the pressure difference between the adjacent airflow paths is minimised at the position
  • each airflow path includes a respective flow detector.
  • the apertures between adjacent airflow paths are located adjacent to the sample outlets to the common volume.
  • the invention provides an apparatus for detecting particles, including: at least one detection chamber having means to detect particles in the chamber; at least one inlet port for introducing an air sample into a respective detection chamber; and means to exhaust the air sample(s) from the detection chamber(s); wherein the detection chamber is configured such that the air sample flows in a first direction from the inlet port into the detection chamber and after traversing the detection chamber flows to the exhaust means in a direction opposite to the first direction.
  • the particle detection apparatus may include a flow detector located between the inlet port and the detection chamber with the air sampling flowing through the flow detector in the first direction.
  • a portion of the detection chamber is formed by a cartridge removable from a housing of the apparatus.
  • the removable portion is able to be located by a single action.
  • the housing and the detection chamber cartridge are shaped in a complementary manner such that the detection chamber cartridge cannot be fitted to the housing when misaligned.
  • multiple inlet ports and respective detection chambers are provided.
  • the detection chamber to includes a loop between its inlet port and out outlet to cause the external length of the flow path to be minimised.
  • detector preferably includes a common exhaust manifold into which air from each of the detection chambers is output from the detection chamber.
  • a fan and filter arrangement is preferably provided and is located on the opposite side of the manifold to the inlet ports.
  • Figure 1 is a perspective view of a smoke detector according to the present invention
  • Figure 2 is a perspective view of a smoke detector showing a cross-section through line 2-2 in Figure 1;
  • Figure 3 is a cross-sectional view of a detection chamber, with a representation of the viewing area reached by the photo-detectors;
  • Figure 4 is a perspective view of the smoke detector of Figure 1 , with the detection chamber and fan and filter cartridge removed;
  • Figure 5 is a perspective view of the top side of the detection chamber
  • Figure 6 is a perspective exploded view of the detection chamber of Figure 5;
  • Figure 7 is a top view of the smoke detector, with partial cross-section through the detection chamber and fan and filter cartridge;
  • Figure 8 is a perspective exploded view from above of the fan and filter cartridge;
  • Figure 9 is a perspective exploded view from below of the fan and filter cartridge of Figure 8.
  • FIG. 1 shows a perspective view of a particle detection apparatus in the form of a smoke detector according to a preferred embodiment.
  • the detector 100 includes three main components, namely a chassis 102, a detection chamber cartridge 104 and a fan and filter cartridge 106.
  • the detection chamber cartridge 104 and fan and filter cartridge 106 are removable from the chassis 102.
  • the illustrative embodiment depicted is able to independently analyse six air samples as it has six inlets 108 for introducing air samples into six detection chambers 103 in the detection chamber cartridge 104.
  • the air samples are all vented from the smoke detector via a common exhaust port 110.
  • Figure 2 shows a perspective view of the smoke detector with a cross-section through one of the detection chambers 103 at line 2-2 as shown in Figure 1.
  • Those skilled in the art will appreciate that a similar cross section could be taken through any one of the six detection chambers of the smoke detector.
  • the air samples enter the inlet 108 in the direction of arrow 114.
  • the air samples initially flow through a flow detector 116, which is configured to determine the flow rate of the air flowing through the detector 116.
  • the flow detector 116 is preferably an ultrasonic flow sensor of the type described in International patent publication WO 2004/102499 entitled “Improved sensing apparatus and method", in the name of Xtralis Pty Ltd and has been used in such products as the range of air sampling smoke detectors sold under the trade mark "VESDA LaserFocus" by Xtralis Pty Ltd.
  • the air sample traverses the region of interest 118 of the detection chamber 103 in which smoke detection readings are performed.
  • the illustrative embodiment described herein uses the principles of detecting the forward light scattering from a laser beam to detect the presence of particles in the air flow although a backscatter geometry may also be used.
  • two laser beams 120 project through each of the six detection chambers 103, best shown in Figure 7.
  • Photo-detectors 516 are able to detect light scattered from the laser beams 120 as the air sample moves through the region of interest 118.
  • Figure 3 shows a representation of the viewing area 119 of the photo-detectors 516. Details of the smoke detection function and the light sources are described in co-pending patent application filed on the same day as the present application entitled "Method and system for particle detection".
  • the flow detector 116 is located close to the inlet 108, with the inlets 108 being connected to separate inlet pipes from an air sampling network (not shown) which collect air samples possibly from different rooms or areas of a building.
  • an air sampling network not shown
  • the independent air samples from separate locations can each be analysed, which, when detecting smoke, allows the location of the smoke to be easily identified.
  • the path of travel of the air samples through the area of interest 118 requires the air to flow around a tortuous path or loop and flow back toward the side of the chassis 102 that it entered. This is achieved by both the inlets 108 and the exhaust means (described below) being connected to the detection chamber 103 on the same side, thus the path loops back on top of itself and the air sample flows in a direction opposite to the direction of flow of arrow 114. This confines the length of the components and allows the smoke detector to be of a relatively compact size.
  • One advantage of this arrangement is that the detection chamber cartridge 104 can be located at the edge of the chassis 102, and still be between the ultrasonic flow detector 116 and a manifold 122 in the flow path.
  • the air sample passes into a common exhaust manifold 122.
  • the exhaust manifold 122 is common to each of the individual detection chambers 103.
  • the air is then drawn into the fan and filter cartridge 106 via aperture 124.
  • the majority of the air drawn into the aperture 124 is vented through an exhaust port 110 (not shown in Figure 2) and a portion is filtered through clean air filter 126.
  • the air filtered by clean air filter 126 is fed into the detection chamber 103 and is used to provide clean air for cleaning the optical surfaces of the detection chamber cartridge 104 in a manner which will be described in more detail below.
  • the air entering one inlet 108 may have a pressure that is different to the air entering another inlet 108.
  • any pressure differential between the six separate air flows is equalised.
  • apertures 524 are provided between the detection chambers 103 for the laser beams 120 to pass through. Whilst it may be possible to use transparent windows between the adjacent chambers for the beam to pass through, such windows will tend to become contaminated by particle build up relatively quickly, thus requiring maintenance.
  • the problems associated with open apertures between the inlets 108 is that if a pressure differential exists between the different air flows, air in one port that has a higher pressure will migrate into the port with air at a lower pressure through the apertures.
  • any pressure differential between the air flows at the laser beam apertures 524 can be minimised by locating the laser beam apertures 524 and related detection chambers 103 in close proximity to the common manifold, as at this location the pressure differential is relatively equalised.
  • the ultrasonic flow detector 116 upstream of the detection chambers 103, an accurate reading of the flow in each of the separate inlets 108 is able to be made.
  • FIG. 4 shows the chassis 102 of the smoke detector 100 with the detection chamber cartridge 104 and the fan and filter cartridge 106 removed.
  • part of the air flow channel through the smoke detector is formed by the chassis 102 and part is formed by the removable cartridges 104 and 106.
  • the chassis 102 On its lower side, the chassis 102 is formed having a series of six cavities 302 which are adapted to receive inlet ports 526 (described below) of the smoke detection chamber cartridge 104. Each of these cavities 302 is further adapted to receive an insect screen in slot 304, which prevents insects and large particulate matter from entering the region of interest 118 of the detection chamber 103.
  • the chassis 102 is provided with a single receiving aperture 306 on the common exhaust manifold (122 of Figure 2) side which is adapted to receive the outlet ports 528 portion (described below) of the detection chamber cartridge 104.
  • the detection chamber cartridge 104 engages with the chassis 102 above the cavities 302, also shown in Figure 3.
  • Surrounding the apertures 306 and cavities 302 is a continuous surface 305 adapted to receive a gasket (514 shown in Figure 6) to form a seal between the removable detection chamber 104 and chassis 102.
  • a surface 300 adjacent surface 305 is adapted to receive the removable fan and filter cartridge 106 and includes aperture 124 through which the exhausted air is drawn into the fan and filter cartridge 106.
  • Second aperture 308 is the entry into the common exhaust port 110 from the fan and filter cartridge 104.
  • Surface 300 is flat and is adapted to receive a gasket (not shown) to provide a seal between the fan and filter cartridge 104 and the chassis 102.
  • the chassis 102 also includes a pair of electrical connectors 310 and 312 which are configured to make electrical and data connections with the detection chamber cartridge 104 and fan and filter cartridge 106 respectively. These are placed so as to engage when the detection chamber cartridge 104 and fan and filter cartridge 106 are brought into engagement with the chassis 102.
  • the detection chamber cartridge 104 and fan and filter cartridge 106 are held in place on the chassis 102 using pairs of cam levers 314 and 316 respectively (shown in Figure 1).
  • the area noted generally with reference numeral 112 is adapted to receive the wiring and electronics of the device (not shown) and holes 320 and 322 are provided to reach the region 112 for wiring.
  • Figure 5 shows a perspective view of the top of the detection chamber cartridge 104 of the preferred embodiment of the present invention
  • Figure 6 shows an exploded view of the detection chamber cartridge 104.
  • the assembly of the detection chamber cartridge 104 includes the following main components: housing 500, printed circuit board 502, a pair of lasers 504 and 506, an internal gasket 508, an upper housing 510 and a lower housing 512, and the interface gasket 514.
  • the detection chambers of particle detectors 103 and their optical components, such as reflective and viewed surfaces and windows are susceptible to contamination from the build up of particles. This is particularly the case in dirty environments. Overtime the additional uncontrolled reflectiveness of dirty surfaces can cause a change in the levels of background light (which is effectively noise) that is received by the detectors. If left uncorrected, either by maintenance or through software controls this increasing background level can cause an increase in false alarms.
  • a chamber cartridge can be provided that defines part of the detection chamber walls (or other surface) which includes the optical surface viewable by the photo-detector, but not other components.
  • the housing 500 is configured to receive each of the other components, and in the preferred embodiment is made from aluminium to provide both rigidity and electro-magnetic shielding for the electronics contain therein. As it would be appreciated by those skilled in the art, other materials may be used to form such a housing, which would have the desired rigidity and shielding characteristics.
  • the printed circuit board 502 carries photo-detectors 516 (shown in Figure 3) arranged in pairs for each detection chamber 103.
  • Printed circuit board 502 also has a connector 518 for electrically connecting the detection chamber cartridge 104 to the chassis 102 of the smoke detector in which it is installed.
  • the pair of lasers 504 and 506 are also mounted at one end of the housing 500 and configured to project parallel beams of light 120 along the length of the detection housing 500, through all of the six detection chambers 103.
  • the housing 500 is adapted to receive a flow of clean air into an aperture 520 (shown in Figure 5) which is used to ensure that the optical surfaces of the detection chambers 103 are maintained free from dust and other contamination.
  • the printed circuit board 502 is formed with holes 503 to allow the clean air that enters the chamber housing 500 to pass through it into the detection chambers 103.
  • an internal gasket 508 Over the printed circuit board 502 there is placed an internal gasket 508 which is adapted to provide a controlled flow of the clean air through the inside of the detection chamber cartridge 104.
  • Light dump 520 is formed by two angled faces 525 which act to direct the laser beam away from a direct return path into the detection chambers 103.
  • Each detection chamber 103 formed by the upper housing 510 has a pair of apertures 515 through which their respective photo-detector 516 may view a portion of the laser beam 120 shining through the detection chamber 103. These apertures are kept clean in use by the clean air introduced into the housing through aperture 521.
  • the photo-detectors 516 also view through holes 503 in the printed circuit board 502.
  • the upper housing 510 includes wall portions 522 which have apertures 524 formed therein.
  • the walls 522 provide a division between individual chambers 103 whilst the apertures 524 are provided through the wall portions 522 allowing an uninterrupted path through the plurality of chambers 103 for the beams 120 of lasers 504 and 506. This is best shown in Figure 7.
  • the lower housing 512 includes a plurality of detection chamber inlet ports 526 aligned in a row on one side thereof and a corresponding plurality of detection chamber outlets 528 formed on the opposite side of the lower housing 512.
  • Sample air enters the inlet ports 526 and passes through the detection chamber 103, defined in the detection chamber cartridge 104 before exiting the detection chamber 103 via respective exhaust ports 528.
  • Between the inlet ports 526 and respective exhaust ports 528 are located short wall portions 529 which co-operate with the partial wall 522 of the upper housing 510 to define the detection chamber wall. It can be seen in Figure 3 that the detection chambers 103 are formed in part from the inlet ports 526, the outlet ports 528 and wall portions 522 and 529 of the detection chamber cartridge 104.
  • the inlet ports 526 and the output ports 528 form the majority of the optical surfaces within the viewing area 119 of the photo-detectors 516. As these surfaces are part of the removable detection chamber cartridge 104, they are replaced when the chamber cartridge 104 is replaced.
  • a recess 530 is provided to enable an electrical connection to be made through the housing to the connector 518 sitting on the printed circuit board 502.
  • the outer surface of the lower housing 512 has a relatively flat portion 532 which is adapted to receive the gasket 514.
  • the gasket is provided to form a seal between the detection chambers 103 and chassis 102 when the detection chamber cartridge 104 is mounted to the chassis 102.
  • FIGS 8 and 9 show exploded views of the fan and filter cartridge 106 of the illustrative embodiment from different view points. Because the performance of the fan 604 and the filter 606 may deteriorate with age and contamination, it is therefore advantageous to provide a removable and replaceable cartridge that contain those elements of the smoke detector.
  • the fan and filter cartridge 106 includes a housing 600, which is generally box-like, and in which an electrical circuit board 602, a fan 604 and a filter 606 are mounted.
  • the electrical circuit board 602 and fan 604 are mounted to a surface of the housing 600 via respective gaskets 608 and 610 which provide a seal between the components and the housing 600.
  • the housing 600 is also provided with a lid 612.
  • the housing 600 is provided with three apertures 614, 616, 618 on its bottom side for interfacing with the chassis 102 of the smoke detector.
  • the first of these apertures 614 is an air inlet port that aligns with aperture 124 on the chassis 102 and through which air is drawn from the common manifold 122 of the chassis 102.
  • the second aperture in the bottom side of the housing 600 is an exhaust port 616 through which the exhaust air passes out of the housing 600.
  • the third aperture in the housing 618 provides external access to the electrical connection on the circuit board 602 which is used to electrically connect the fan and filter cartridge 106 to the electronics of the smoke detector 100.
  • the housing 600 also provides a clean air hole 620 through which filtered air passes into the clean air input port 521 on the detector chamber cartridge 104.
  • Each of the apertures 614, 616 and 620 which are used for the transport of air, are provided with a respective gasket (not shown) so that a seal is formed with the surface that they make contact with in use.
  • the aperture 618 does not need a gasket as no air passes through it.
  • the fan 604 has an air inlet 628 on its underside that corresponds to the inlet 614 of the housing 600.
  • the fan 604 has an outlet 630.
  • the filter 606 is retained within the housing 600 above the fan 604 and retained between the housing 600 and the lid 612.
  • An air path between the filter 606 and lid 612 is not compromised as a textured surface 632 on the underside of the lid 612 is provided. Air passes in the channels through the textured surface 632 of the lid into a recess 634 (shown in Figure 9) before passing out of the clean air outlet 620 in the underside of the housing 600.
  • the fan and filter cartridge 106 can be mounted to a smoke detector 100 by aligning it with the appropriate apertures and pressing it downwardly such that the fan and filter cartridge 106 come into contact with the appropriate portion of the chassis 102. In this single downward movement towards the chassis the seal between the fan and filter cartridge 106 and the chassis 102 as well as the seal between the clean air outlet 120 and the detection chamber cartridge 104 is made. Furthermore, an electrical connection between the fan and filter cartridge 106 and the electronics of the chassis 102 are also made. In use, fan and filter cartridge 106 is retained in contact with the chassis 102 with the levers 316 which are shown more clearly in Figure 1. A portion of the fan and filter cartridge 106 overlies a portion of the detection chamber cartridge 104. this overlying portion connects the clean air feed to the detection chamber cartridge 104 without the need to manually connect hoses.
  • both the detection chamber cartridge 104 and the fan and filter cartridge 106 contain onboard electronics that include a memory chip logs various data about the component that can minimise or remove the need for a technician to enter data into the detection apparatus to re-commission it after servicing.
  • the chamber cartridge 104 memory can store date including, but not limited to, calibration values, serial numbers, a dust count, contamination rate, data relating to fault or alarm conditions etc.
  • the fan and filter cartridge 106 memory can store data including, but not limited to, calibration values, serial numbers, a dust and contamination rates, flow rates and fan bearing life.
  • the detector can be configured to interrogate each component as they are installed into the detector (or upon start up), and if certain conditions are not met the detector may issue a fault warning either locally to the technician or to a remote monitoring device such as a central controller, or go into a non-operational mode, such as a stand-by mode until appropriate action is taken.
  • the light sources described have been laser light sources. However the light sources could equally be one or more LEDs or other light sources. If an LED or other source of non-collimated light is used it may be necessary to use one or more optical devices (e.g. a lens) to focus or collimate the beam of light emitted by the light source.
  • optical devices e.g. a lens

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  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

An apparatus for detecting particles (100) is disclosed, including: at least one detection chamber (103) having means to detect particles in at least one region of interest (118) within the chamber; at least one inlet port (526) for introducing an air sample into a respective detection chamber; and at least one outlet (528) from the detection chamber; wherein the detection chamber (118) is configured such that the air sample enters the inlet port in a first direction and after traversing the region of interest flows towards the outlet at least partially in a direction other than the first direction.

Description

Particle detection apparatus
Field of the invention
The present invention relates to particle detection. It is convenient to describe the preferred embodiments in relation to an apparatus specifically adapted for detecting smoke particles. However, the present invention should not be considered as being limited to that exemplary application.
Background of the invention
Fire protection and suppressant systems which operate by detecting the presence of smoke and other airborne pollutants are well known. Upon a threshold level of smoke being detected, an alarm may be activated and operation of a fire suppressant system may be initiated. While the fire itself will cause damage, considerable damage can also be caused by operation of the fire suppression system, and subsequent removal of the suppressant can be quite hazardous. A detection system that with sufficient sensitivity to detect an abnormal level of particles in the air is advantageous as it enable action to be taken at a very early stage before the onset of an actual fire.
One such method of providing an early warning of a fire is based on the use of a particle detector which detects airborne particles on the basis of the amount of light scattered from a beam of radiation such as the smoke detectors sold under the trade mark VESDA by Xtralis Pty Ltd, provide a highly sensitive way of detecting particles. These smoke detectors operate by transmitting a beam of light, typically from a laser, or flash tube, through a stream of air in which particles may be present. A photo-detector, such as a photodiode or other light sensitive element is placed at a predetermined position with respect to illuminated volume and the amount of scattered light received by the photo-detector is used to determine the level of particulate matter in the airflow.
Such smoke detection systems draw air samples through a pipe network consisting of one or more sampling pipes with sampling holes installed at positions where smoke or particles can be collected. Air is drawn in through the sampling holes and along the pipe by means of a fan and is directed through a detector at a remote location. Summary of the invention
In a first aspect the present invention provides an apparatus for detecting particles, including: at least one detection chamber having means to detect particles in at least one region of interest within the chamber; at least one inlet port for introducing an air sample into a respective detection chamber; and at least one outlet from the detection chamber; wherein the detection chamber is configured such that the air sample enters the inlet port in a first direction and after traversing the region of interest flows towards the outlet at least partially in a direction other than the first direction.
Preferably the apparatus further includes a flow detector located between an air inlet to the apparatus and the detection chamber with the air sampling flowing through the flow detector in the first direction.
In a second aspect, an apparatus for detecting particles, including: at least one airflow path including, at least one inlet port for introducing an air sample into a respective detection chamber; and means to exhaust the air sample(s) from the detection chamber(s) such that the air sample flows through the detection chamber; at least one light source configured to illuminate a volume of the detection chamber; at least one photo-detector able to view at least part of the illuminated volume of the detection chamber and an optical surface of the detection chamber, to detect particle in the detection chamber; wherein the airflow path is formed in at least two parts such that a portion is removable, whereby the removable portion includes an optical surface of the detection chamber viewable by the photo-detector.
Advantageously, the apparatus is provided with two light sources, preferably two laser beams or LEDs, and respective photo-detectors. The optical surfaces viewed by the separate photo- detectors are preferably spaced apart.
Preferably, the removable portion of the detection chamber forms a removable cartridge including the detection means. Advantageously, the inlet port and the outlet to the exhaust means are located on a same side of the detection chamber. The removable cartridge is therefore able to be inserted in a single action. In one form the cartridge is able to be engaged with the housing by a single downward or sliding movement. Due to this arrangement the two parts of the detection chamber are only required to seal in a single direction. There are preferably multiple detection chambers, with each having optical surfaces. The surfaces of the detection chamber(s) are preferably curved, thus minimising any disturbances to the flow of the air sample and also reducing corners or crevasses where particles can build up.
Preferably the housing and the chamber cartridge are shaped in a complementary manner such that the detection chamber cartridge cannot be attached to the housing when misaligned or incorrectly orientated.
The apparatus preferably includes multiple inlet ports and respective detection chambers. The detector can include a common exhaust manifold into which air from each of the detection chambers is output from the detection chamber.
The removable portion of the detection chamber can forms a removable cartridge including one or more of, a photo detector and light source corresponding to an optical surface.
In one embodiment the airflow passes into the inlet port and out of the outlet to the exhaust means in different directions.
In a third aspect, the present invention provides an apparatus for detecting particles, including:
a base housing;
a detection chamber cartridge removable from the housing; and
a fan and/or filter cartridge removable from the housing;
wherein a portion of one of the cartridges overlies a portion of the other cartridge, to enable interconnection between the cartridges.
Preferably the interconnection between the cartridges provides a fluid communication path between the cartridges. The interconnection between the cartridges may be an electrical and or data connection between the cartridges.
In a fourth aspect, the present invention provides a smoke detector having multiple detection chambers, including: multiple air inlet ports for introducing air samples into respective multiple detection chambers;
apertures provided between the multiple detection chambers such that a light source can project light through a plurality of the detection chambers;
a manifold common to the multiple detection chambers;
wherein the apertures are configured to minimise leakage of air samples through the apertures between adjacent detection chambers.
Advantageously, the smoke detector includes an ultrasonic flow detector that is preferably located upstream from the adjacent detection chambers. The smoke detector also preferably includes a fan, which is located downstream of the detection chambers and also preferably downstream of the common manifold.
The detection chambers may include a plurality of light sources, e.g. lasers. It can also include two apertures between the detection chambers.
In one embodiment, the inlet ports and the manifold are both connected to the detection chamber from a same side of the detection chamber, such that the air sample flows in a first direction from the inlet port into the detection chamber and after traversing the detection chamber flows to the exhaust means in a direction opposite to the first direction. The inlet ports preferably lie parallel to the manifold. Such an arrangement allows the detection chamber to create a loop between the inlet ports and the manifold.
In a further aspect the present invention provides an apparatus for detecting particles in an air sample, including:
a housing including an air sample inlet and an air sample outlet and means to define an airflow path between the inlet and outlet, air sample inlet being configured to introduce an air sample into the apparatus in a first direction;
at least one particle detector interacting with the air sample between the inlet and outlet to detect particles in the air sample; wherein the means to define the airflow path include means to direct the airflow in a direction other than the first direction, to minimise the width of the housing along the first direction.
Preferably the means to define the airflow path defines at least two portions of the airflow path through which the airflow moves in opposite directions. Most preferably the two portions are aligned along the first direction.
The means to define the airflow path preferably defines at least one substantially u-shaped bend in the airflow path.
In a preferred form the housing includes a plurality of housing components that cooperate to define the airflow path. Preferably the housing includes a chassis defining part of the airflow path and one or more removable housing components removably mounted to the chassis that define part of the airflow path.
In a preferred form the at least one particle detector is incorporated in a removable housing components.
Preferably air enters and exits the removable housing component in substantially different directions. Most preferably the flow path through the housing component including the at least one particle detector includes one or more bends that changes the direction of airflow. Preferably the net change of direction of the airflow between the input and output of the housing component including the at least one particle detector is 180 degrees.
Preferably a removable housing component can be removed and/or coupled with the chassis without the disconnection and/or connection of additional components, such as additional wiring, hoses or the like between them.
Preferably the removable housing component can be engaged and/or disengaged with the chassis by movement along or about a single axis. The movement along or about a single axis may be preceded by a step of aligning the removable housing component with the chassis.
The apparatus preferably includes a flow sensor for determining a flow rate in the airflow in the airflow path. In a preferred embodiment the apparatus includes a plurality of air sample inlets and at least one air sample outlet, and means to define a plurality of airflow path between a respective one of the air sample inlets and an outlet.
In this embodiment it is preferable that a particle detector that which interacts with each airflow is incorporated in a common removable component. Preferably the particle detector corresponding to each airflow shares one or more components with a particle detector for another airflow. Preferably the particle detectors for the plurality of airflows operates by detecting scattered light and share a common light source.
In another aspect the present invention provides an apparatus for detecting particles in an air sample, including, a plurality of air sample inlets and air sample outlets in communication with a common air volume, and means to define a plurality of airflow path between a respective one of the air sample inlets and the common volume, at least one particle detector interacting with each air sample between its inlet and outlet to the particle detector being configured to detect particles in each air sample, the particle detector including, a shared light source for illuminating a volume in two or more of the air samples, and at least one light detector for each air sample that is configured to detect the level of light scattered from at least part of the illuminated volume in each air sample; the means to define a plurality of airflow paths including apertures between adjacent airflow paths through which a shared light source illuminates a volume in two or more of the air samples, wherein the apertures between adjacent airflow paths is positioned such that, in the event that a different air pressure exists in each airflow their respective air sample inlets, the pressure difference between the adjacent airflow paths is minimised at the position of the apertures between them.
Preferably each airflow path includes a respective flow detector.
Preferably the apertures between adjacent airflow paths are located adjacent to the sample outlets to the common volume.
In another aspect the invention provides an apparatus for detecting particles, including: at least one detection chamber having means to detect particles in the chamber; at least one inlet port for introducing an air sample into a respective detection chamber; and means to exhaust the air sample(s) from the detection chamber(s); wherein the detection chamber is configured such that the air sample flows in a first direction from the inlet port into the detection chamber and after traversing the detection chamber flows to the exhaust means in a direction opposite to the first direction. The particle detection apparatus may include a flow detector located between the inlet port and the detection chamber with the air sampling flowing through the flow detector in the first direction. Preferably, a portion of the detection chamber is formed by a cartridge removable from a housing of the apparatus. By locating the inlet port and the exhaust means on a same side of the detection chamber, the removable portion is able to be located by a single action. Preferably the housing and the detection chamber cartridge are shaped in a complementary manner such that the detection chamber cartridge cannot be fitted to the housing when misaligned. Advantageously, multiple inlet ports and respective detection chambers are provided. Advantageously, the detection chamber to includes a loop between its inlet port and out outlet to cause the external length of the flow path to be minimised. Additionally, detector preferably includes a common exhaust manifold into which air from each of the detection chambers is output from the detection chamber. A fan and filter arrangement is preferably provided and is located on the opposite side of the manifold to the inlet ports.
Brief description of the drawings
The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a perspective view of a smoke detector according to the present invention;
Figure 2 is a perspective view of a smoke detector showing a cross-section through line 2-2 in Figure 1;
Figure 3 is a cross-sectional view of a detection chamber, with a representation of the viewing area reached by the photo-detectors;
Figure 4 is a perspective view of the smoke detector of Figure 1 , with the detection chamber and fan and filter cartridge removed;
Figure 5 is a perspective view of the top side of the detection chamber;
Figure 6 is a perspective exploded view of the detection chamber of Figure 5;
Figure 7 is a top view of the smoke detector, with partial cross-section through the detection chamber and fan and filter cartridge; Figure 8 is a perspective exploded view from above of the fan and filter cartridge; and
Figure 9 is a perspective exploded view from below of the fan and filter cartridge of Figure 8.
Detailed description of the embodiments
The preferred embodiment of the present invention will now described in connection with a smoke detector which is able to receive and simultaneously analyse a plurality of air samples in separate detection chambers.
The principles and advantageous aspects of the present invention could be practised in a smoke detector with any number of detection chambers, and a person skilled in the art would readily understand how to adapt the various aspects of the present invention to detectors with a different number of chambers.
Figure 1 shows a perspective view of a particle detection apparatus in the form of a smoke detector according to a preferred embodiment. The detector 100 includes three main components, namely a chassis 102, a detection chamber cartridge 104 and a fan and filter cartridge 106. The detection chamber cartridge 104 and fan and filter cartridge 106 are removable from the chassis 102.
The illustrative embodiment depicted is able to independently analyse six air samples as it has six inlets 108 for introducing air samples into six detection chambers 103 in the detection chamber cartridge 104. The air samples are all vented from the smoke detector via a common exhaust port 110.
Figure 2 shows a perspective view of the smoke detector with a cross-section through one of the detection chambers 103 at line 2-2 as shown in Figure 1. Those skilled in the art will appreciate that a similar cross section could be taken through any one of the six detection chambers of the smoke detector.
In overview, the air samples enter the inlet 108 in the direction of arrow 114. The air samples initially flow through a flow detector 116, which is configured to determine the flow rate of the air flowing through the detector 116. The flow detector 116 is preferably an ultrasonic flow sensor of the type described in International patent publication WO 2004/102499 entitled "Improved sensing apparatus and method", in the name of Xtralis Pty Ltd and has been used in such products as the range of air sampling smoke detectors sold under the trade mark "VESDA LaserFocus" by Xtralis Pty Ltd.
After passing through the flow detector 116 the air sample traverses the region of interest 118 of the detection chamber 103 in which smoke detection readings are performed. The illustrative embodiment described herein uses the principles of detecting the forward light scattering from a laser beam to detect the presence of particles in the air flow although a backscatter geometry may also be used. In this example, two laser beams 120 project through each of the six detection chambers 103, best shown in Figure 7. Photo-detectors 516 are able to detect light scattered from the laser beams 120 as the air sample moves through the region of interest 118. Figure 3 shows a representation of the viewing area 119 of the photo-detectors 516. Details of the smoke detection function and the light sources are described in co-pending patent application filed on the same day as the present application entitled "Method and system for particle detection".
As can be seen best in Figure 2, the flow detector 116 is located close to the inlet 108, with the inlets 108 being connected to separate inlet pipes from an air sampling network (not shown) which collect air samples possibly from different rooms or areas of a building. By providing six separate flow detectors 116 and detections chambers 103, the independent air samples from separate locations can each be analysed, which, when detecting smoke, allows the location of the smoke to be easily identified.
The path of travel of the air samples through the area of interest 118 requires the air to flow around a tortuous path or loop and flow back toward the side of the chassis 102 that it entered. This is achieved by both the inlets 108 and the exhaust means (described below) being connected to the detection chamber 103 on the same side, thus the path loops back on top of itself and the air sample flows in a direction opposite to the direction of flow of arrow 114. This confines the length of the components and allows the smoke detector to be of a relatively compact size. One advantage of this arrangement is that the detection chamber cartridge 104 can be located at the edge of the chassis 102, and still be between the ultrasonic flow detector 116 and a manifold 122 in the flow path. By arranging the detection chamber cartridge 104 at the edge of the chassis 102, a better seal can be made between the components, as the cartridge 104 is only required to be inserted in the downward direction and does not need to lock into sealing engagement between two components. Referring back to Figure 2, after traversing the region of interest 118 of the detection chamber 103, the air sample passes into a common exhaust manifold 122. The exhaust manifold 122 is common to each of the individual detection chambers 103. The air is then drawn into the fan and filter cartridge 106 via aperture 124. The majority of the air drawn into the aperture 124 is vented through an exhaust port 110 (not shown in Figure 2) and a portion is filtered through clean air filter 126. The air filtered by clean air filter 126 is fed into the detection chamber 103 and is used to provide clean air for cleaning the optical surfaces of the detection chamber cartridge 104 in a manner which will be described in more detail below.
The air entering one inlet 108 may have a pressure that is different to the air entering another inlet 108. When the air from each of the airflows enters at the common manifold 122 any pressure differential between the six separate air flows is equalised. As explained above, apertures 524 are provided between the detection chambers 103 for the laser beams 120 to pass through. Whilst it may be possible to use transparent windows between the adjacent chambers for the beam to pass through, such windows will tend to become contaminated by particle build up relatively quickly, thus requiring maintenance. The problems associated with open apertures between the inlets 108 is that if a pressure differential exists between the different air flows, air in one port that has a higher pressure will migrate into the port with air at a lower pressure through the apertures. It has been discovered that any pressure differential between the air flows at the laser beam apertures 524 can be minimised by locating the laser beam apertures 524 and related detection chambers 103 in close proximity to the common manifold, as at this location the pressure differential is relatively equalised. By positioning the ultrasonic flow detector 116 upstream of the detection chambers 103, an accurate reading of the flow in each of the separate inlets 108 is able to be made.
Figure 4 shows the chassis 102 of the smoke detector 100 with the detection chamber cartridge 104 and the fan and filter cartridge 106 removed. As will be appreciated, part of the air flow channel through the smoke detector is formed by the chassis 102 and part is formed by the removable cartridges 104 and 106. On its lower side, the chassis 102 is formed having a series of six cavities 302 which are adapted to receive inlet ports 526 (described below) of the smoke detection chamber cartridge 104. Each of these cavities 302 is further adapted to receive an insect screen in slot 304, which prevents insects and large particulate matter from entering the region of interest 118 of the detection chamber 103.
The chassis 102 is provided with a single receiving aperture 306 on the common exhaust manifold (122 of Figure 2) side which is adapted to receive the outlet ports 528 portion (described below) of the detection chamber cartridge 104. The detection chamber cartridge 104 engages with the chassis 102 above the cavities 302, also shown in Figure 3. Surrounding the apertures 306 and cavities 302 is a continuous surface 305 adapted to receive a gasket (514 shown in Figure 6) to form a seal between the removable detection chamber 104 and chassis 102. A surface 300 adjacent surface 305 is adapted to receive the removable fan and filter cartridge 106 and includes aperture 124 through which the exhausted air is drawn into the fan and filter cartridge 106. Second aperture 308 is the entry into the common exhaust port 110 from the fan and filter cartridge 104. Surface 300 is flat and is adapted to receive a gasket (not shown) to provide a seal between the fan and filter cartridge 104 and the chassis 102.
The chassis 102 also includes a pair of electrical connectors 310 and 312 which are configured to make electrical and data connections with the detection chamber cartridge 104 and fan and filter cartridge 106 respectively. These are placed so as to engage when the detection chamber cartridge 104 and fan and filter cartridge 106 are brought into engagement with the chassis 102. The detection chamber cartridge 104 and fan and filter cartridge 106 are held in place on the chassis 102 using pairs of cam levers 314 and 316 respectively (shown in Figure 1). The area noted generally with reference numeral 112 is adapted to receive the wiring and electronics of the device (not shown) and holes 320 and 322 are provided to reach the region 112 for wiring.
Figure 5 shows a perspective view of the top of the detection chamber cartridge 104 of the preferred embodiment of the present invention, and Figure 6 shows an exploded view of the detection chamber cartridge 104. The assembly of the detection chamber cartridge 104 includes the following main components: housing 500, printed circuit board 502, a pair of lasers 504 and 506, an internal gasket 508, an upper housing 510 and a lower housing 512, and the interface gasket 514.
Over time the detection chambers of particle detectors 103 and their optical components, such as reflective and viewed surfaces and windows are susceptible to contamination from the build up of particles. This is particularly the case in dirty environments. Overtime the additional uncontrolled reflectiveness of dirty surfaces can cause a change in the levels of background light (which is effectively noise) that is received by the detectors. If left uncorrected, either by maintenance or through software controls this increasing background level can cause an increase in false alarms.
Since it is difficult for components to be serviced or cleaned in a controllable and reliable fashion in the field, it would be advantageous if they could be replaced. However, to do this requires tools, time and a fair degree of skill. By providing a removable detection chamber cartridge 104, the components susceptible to contamination can be removed and analysed and if necessary replaced by swapping a new cartridge for the old one, preferably without tools and with as little skill as possible.
In one implementation (not illustrated) a chamber cartridge can be provided that defines part of the detection chamber walls (or other surface) which includes the optical surface viewable by the photo-detector, but not other components.
In the preferred embodiment illustrated the housing 500 is configured to receive each of the other components, and in the preferred embodiment is made from aluminium to provide both rigidity and electro-magnetic shielding for the electronics contain therein. As it would be appreciated by those skilled in the art, other materials may be used to form such a housing, which would have the desired rigidity and shielding characteristics. The printed circuit board 502 carries photo-detectors 516 (shown in Figure 3) arranged in pairs for each detection chamber 103. Printed circuit board 502 also has a connector 518 for electrically connecting the detection chamber cartridge 104 to the chassis 102 of the smoke detector in which it is installed. The pair of lasers 504 and 506 are also mounted at one end of the housing 500 and configured to project parallel beams of light 120 along the length of the detection housing 500, through all of the six detection chambers 103.
The housing 500 is adapted to receive a flow of clean air into an aperture 520 (shown in Figure 5) which is used to ensure that the optical surfaces of the detection chambers 103 are maintained free from dust and other contamination. The printed circuit board 502 is formed with holes 503 to allow the clean air that enters the chamber housing 500 to pass through it into the detection chambers 103. Over the printed circuit board 502 there is placed an internal gasket 508 which is adapted to provide a controlled flow of the clean air through the inside of the detection chamber cartridge 104. Above is the upper housing 510, which defines the upper surfaces of the six detection chambers 103 (best seen in Figure 3) and the structure of a light dump 520 (best seen in Figure 7). Light dump 520 is formed by two angled faces 525 which act to direct the laser beam away from a direct return path into the detection chambers 103. Each detection chamber 103 formed by the upper housing 510 has a pair of apertures 515 through which their respective photo-detector 516 may view a portion of the laser beam 120 shining through the detection chamber 103. These apertures are kept clean in use by the clean air introduced into the housing through aperture 521. The photo-detectors 516 also view through holes 503 in the printed circuit board 502. The upper housing 510 includes wall portions 522 which have apertures 524 formed therein. The walls 522 provide a division between individual chambers 103 whilst the apertures 524 are provided through the wall portions 522 allowing an uninterrupted path through the plurality of chambers 103 for the beams 120 of lasers 504 and 506. This is best shown in Figure 7.
The lower housing 512 includes a plurality of detection chamber inlet ports 526 aligned in a row on one side thereof and a corresponding plurality of detection chamber outlets 528 formed on the opposite side of the lower housing 512. Sample air enters the inlet ports 526 and passes through the detection chamber 103, defined in the detection chamber cartridge 104 before exiting the detection chamber 103 via respective exhaust ports 528. Between the inlet ports 526 and respective exhaust ports 528 are located short wall portions 529 which co-operate with the partial wall 522 of the upper housing 510 to define the detection chamber wall. It can be seen in Figure 3 that the detection chambers 103 are formed in part from the inlet ports 526, the outlet ports 528 and wall portions 522 and 529 of the detection chamber cartridge 104.
As can best be seen in Figure 2, the inlet ports 526 and the output ports 528 form the majority of the optical surfaces within the viewing area 119 of the photo-detectors 516. As these surfaces are part of the removable detection chamber cartridge 104, they are replaced when the chamber cartridge 104 is replaced.
At one end of the lower housing 512 a recess 530 is provided to enable an electrical connection to be made through the housing to the connector 518 sitting on the printed circuit board 502. Around the inlet ports 526 and output ports 528 the outer surface of the lower housing 512 has a relatively flat portion 532 which is adapted to receive the gasket 514. The gasket is provided to form a seal between the detection chambers 103 and chassis 102 when the detection chamber cartridge 104 is mounted to the chassis 102.
Figures 8 and 9 show exploded views of the fan and filter cartridge 106 of the illustrative embodiment from different view points. Because the performance of the fan 604 and the filter 606 may deteriorate with age and contamination, it is therefore advantageous to provide a removable and replaceable cartridge that contain those elements of the smoke detector.
Turning firstly to Figure 8, it can be seen that the fan and filter cartridge 106 includes a housing 600, which is generally box-like, and in which an electrical circuit board 602, a fan 604 and a filter 606 are mounted. The electrical circuit board 602 and fan 604 are mounted to a surface of the housing 600 via respective gaskets 608 and 610 which provide a seal between the components and the housing 600. The housing 600 is also provided with a lid 612.
The housing 600 is provided with three apertures 614, 616, 618 on its bottom side for interfacing with the chassis 102 of the smoke detector. The first of these apertures 614 is an air inlet port that aligns with aperture 124 on the chassis 102 and through which air is drawn from the common manifold 122 of the chassis 102. The second aperture in the bottom side of the housing 600 is an exhaust port 616 through which the exhaust air passes out of the housing 600. The third aperture in the housing 618 provides external access to the electrical connection on the circuit board 602 which is used to electrically connect the fan and filter cartridge 106 to the electronics of the smoke detector 100. The housing 600 also provides a clean air hole 620 through which filtered air passes into the clean air input port 521 on the detector chamber cartridge 104. Each of the apertures 614, 616 and 620 which are used for the transport of air, are provided with a respective gasket (not shown) so that a seal is formed with the surface that they make contact with in use. As will be appreciated, the aperture 618 does not need a gasket as no air passes through it.
The fan 604 has an air inlet 628 on its underside that corresponds to the inlet 614 of the housing 600. The fan 604 has an outlet 630. When the fan 604 is mounted within the housing 600 its outlet 630 generally aligns with the outlet 616 of the housing 600. However, there is not a seal between these two openings so a portion of the air drawn into the fan 604 is passed into the void within the housing 600. This portion of air is passed upwardly through the housing 600 and through the clean air filter 606, and out of the housing via the clean air outlet 620 into the detection chamber cartridge 104 via aperture 521. The filter 606 is retained within the housing 600 above the fan 604 and retained between the housing 600 and the lid 612. An air path between the filter 606 and lid 612 is not compromised as a textured surface 632 on the underside of the lid 612 is provided. Air passes in the channels through the textured surface 632 of the lid into a recess 634 (shown in Figure 9) before passing out of the clean air outlet 620 in the underside of the housing 600.
In use, the fan and filter cartridge 106 can be mounted to a smoke detector 100 by aligning it with the appropriate apertures and pressing it downwardly such that the fan and filter cartridge 106 come into contact with the appropriate portion of the chassis 102. In this single downward movement towards the chassis the seal between the fan and filter cartridge 106 and the chassis 102 as well as the seal between the clean air outlet 120 and the detection chamber cartridge 104 is made. Furthermore, an electrical connection between the fan and filter cartridge 106 and the electronics of the chassis 102 are also made. In use, fan and filter cartridge 106 is retained in contact with the chassis 102 with the levers 316 which are shown more clearly in Figure 1. A portion of the fan and filter cartridge 106 overlies a portion of the detection chamber cartridge 104. this overlying portion connects the clean air feed to the detection chamber cartridge 104 without the need to manually connect hoses.
In a preferred form both the detection chamber cartridge 104 and the fan and filter cartridge 106 contain onboard electronics that include a memory chip logs various data about the component that can minimise or remove the need for a technician to enter data into the detection apparatus to re-commission it after servicing.
For example the chamber cartridge 104 memory can store date including, but not limited to, calibration values, serial numbers, a dust count, contamination rate, data relating to fault or alarm conditions etc. Similarly the fan and filter cartridge 106 memory can store data including, but not limited to, calibration values, serial numbers, a dust and contamination rates, flow rates and fan bearing life.
In a preferred form the detector can be configured to interrogate each component as they are installed into the detector (or upon start up), and if certain conditions are not met the detector may issue a fault warning either locally to the technician or to a remote monitoring device such as a central controller, or go into a non-operational mode, such as a stand-by mode until appropriate action is taken.
Where such detectors are used as smoke detectors it is imperative that a high level of confidence can be placed the devices. By having pre-programmed calibration values stored on the replaceable components the level of confidence that the device is programmed correctly may be enhanced. Additionally, by checking the on-board data before enabling re- commissioning of the device after a component is replaced the risks associated with or using old, damaged, non-standards compliant, or other components that may not be within required specifications, such as incorrect operation or premature failure etc. can be monitored and possibly prevented.
In the preferred embodiments described herein the light sources described have been laser light sources. However the light sources could equally be one or more LEDs or other light sources. If an LED or other source of non-collimated light is used it may be necessary to use one or more optical devices (e.g. a lens) to focus or collimate the beam of light emitted by the light source. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

The claims defining the invention are as follows:
1. An apparatus for detecting particles, including:
at least one detection chamber having means to detect particles in at least one region of interest within the chamber;
at least one inlet port for introducing an air sample into a respective detection chamber; and
at least one outlet from the detection chamber;
wherein the detection chamber is configured such that the air sample enters the the inlet port in a first direction and after traversing the region of interest flows towards the outlet at least partially in a direction other than the first direction.
2. An apparatus for detecting particles as claimed in claim 1 where it further includes a flow detector located between an air inlet to the apparatus and the detection chamber with the air sample flowing through the flow detector in the first direction.
3. An apparatus for detecting particles, including:
at least one airflow path including, at least one inlet port for introducing an air sample into a respective detection chamber; and means to exhaust the air sample(s) from the detection chamber(s) such that the air sample flows through the detection chamber;
at least one light source configured to illuminate a volume of the detection chamber; at least one photo-detector able to view at least part of the illuminated volume of the detection chamber and an optical surface of the detection chamber, to detect particle in the detection chamber;
wherein the airflow path is formed in at least two parts such that a portion is removable, whereby the removable portion includes an optical surface of the detection chamber viewable by the photo-detector.
4. An apparatus for detecting particles as claimed in claim 3 wherein the apparatus can be provided with a plurality of light sources configured to illuminate respective volumes of a detection chamber and at least one photo-detector corresponding to each illuminated volume.
5. An apparatus for detecting particles as claimed in either of the preceding claims wherein at least a portion of at least one detection chamber is formed by a cartridge that is removable from a housing of the apparatus.
6. An apparatus for detecting particles as claimed in claim 5 wherein, the cartridge is able to be removed and/or attached to the housing with a single action.
7. An apparatus for detecting particles as claimed in any one of claims 5 or 6 wherein the housing and the detection chamber cartridge are shaped in a complementary manner such that the detection chamber cartridge cannot be attached to the housing when misaligned or incorrectly orientated.
8. An apparatus for detecting particles as claimed in any one of the preceding claims including multiple inlet ports and respective detection chambers are provided.
9. An apparatus for detecting particles as claimed in any one of the preceding claims wherein the, detector preferably includes a common exhaust manifold into which air from each of the detection chambers is output from the detection chamber.
10. An apparatus for detecting particles as claimed in any one of claims 3 to 9 wherein the removable portion of the airflow path forms a removable cartridge including one or more of, a photo detector and light source corresponding to an optical surface.
11. An apparatus for detecting particles as claimed in any one of claims 3 to 10 wherein the airflow passes into the inlet port and out of the outlet to the exhaust means in different directions.
12. An apparatus for detecting particles, including:
a base housing;
a detection chamber cartridge removable from the housing; and a fan and/or filter cartridge removable from the housing;
wherein a portion of one of the cartridges overlies a portion of the other cartridge, to enable interconnection between the cartridges.
13. An apparatus for detecting particles as claimed in claim 12 wherein the interconnection between the cartridges allows at least one of the following forms of communication between cartridges:
fluid communication;
electrical communication;
data communication.
14. A smoke detector having multiple detection chambers, including:
multiple air inlet ports for introducing air samples into respective multiple detection chambers;
apertures provided between the multiple detection chambers such that a light source can project light through a plurality of the detection chambers;
a manifold common to the multiple detection chambers;
wherein the apertures are configured to minimise leakage of air samples through the apertures between adjacent detection chambers.
15. A smoke detector as claimed in either of claims 14 wherein the smoke detector includes a fan, which is located downstream of the detection chambers and also preferably downstream of the common manifold.
16. A smoke detector as claimed in any one of claims 14 or 15 wherein the detection chambers include a plurality of light sources..
17. A smoke detector as claimed in claim 15, wherein, the smoke detector includes an ultrasonic flow detector that is preferably located upstream from the adjacent detection chambers.
18. An apparatus for detecting particles in an air sample, including:
a housing including an air sample inlet and an air sample outlet and means to define an airflow path between the inlet and outlet, air sample inlet being configured to introduce an air sample into the apparatus in a first direction;
at least one particle detector interacting with the air sample between the inlet and outlet to detect particles in the air sample;
wherein the means to define the airflow path include means to direct the airflow in a direction other than the first direction, to minimise the width of the housing along the first direction.
19. An apparatus for detecting particles as claimed in claim 18 wherein the means to define the airflow path defines at least two portions of the airflow path through which the airflow moves in opposite directions.
20. An apparatus for detecting particles as claimed in claim 18 wherein the two portions are aligned along the first direction.
21. An apparatus for detecting particles as claimed in any one of claims 18 to 20 wherein the means to define the airflow path preferably defines at least one substantially u-shaped bend in the airflow path.
22. An apparatus for detecting particles as claimed in any one of claims 18 to 21 wherein the housing includes a chassis defining part of the airflow path and one or more removable housing components mounted to the chassis that define part of the airflow path.
23. An apparatus for detecting particles as claimed in any one of claims 18 to 22 wherein a removable housing component is adapted to be removed from and/or coupled with the chassis without separate disconnection and/or connection of additional components between them.
24. An apparatus for detecting particles as claimed in any one of claims 18 to 23 wherein the removable housing component can be engaged and/or disengaged with the chassis by movement along or about a single axis.
25. An apparatus for detecting particles as claimed in any one of claims 18 to 24 wherein the apparatus includes a plurality of air sample inlets and at least one air sample outlet, and means to define a plurality of airflow paths between a respective one of the air sample inlets and an outlet.
26. An apparatus for detecting particles as claimed in any one of claims 18 to 24 wherein at least one particle detector is incorporated into a removable housing component.
27. An apparatus for detecting particles as claimed in claim 26 wherein a particle detector that which interacts with each airflow is incorporated in a common removable component.
28. An apparatus for detecting particles as claimed in either of claims 26 or 27 wherein the particle detector corresponding to each airflow shares one or more components with a particle detector for another airflow.
29. An apparatus for detecting particles as claimed in claim 28 wherein the particle detectors for the plurality of airflows operates by detecting scattered light and share a common light source.
30. An apparatus for detecting particles in an air sample, including:
a plurality of air sample inlets and an air sample outlets in communication with a common air volume, and means to define a plurality of airflow paths between a respective one of the air sample inlets and the common volume;
at least one particle detector interacting with each air sample between its inlet and outlet to the particle detector being configured to detect particles in each air sample, and including, a shared light source for illuminating a volume in two or more of the air samples, and at least one light detector for each air sample that is configured to detect the level of light scattered from at least part of the illuminated volume in each air sample; the means to define a plurality of airflow paths including apertures between adjacent airflow paths through which a shared light source illuminates a volume in two or more of the air samples, wherein the apertures between adjacent airflow paths is positioned such that, in the event that a different air pressure exists in each airflow their respective air sample inlets, the pressure difference between the adjacent airflow paths is minimised at the position of the apertures between them.
31. An apparatus for detecting particles as claimed in claim 30 wherein airflow path includes a respective flow detector.
32. An apparatus for detecting particles as claimed in claim either of claims 30 or 31 wherein the apertures between adjacent airflow paths are located adjacent to the sample outlets to the common volume.
33. An apparatus for detecting particles as claimed in any one of claims 1 to 13 or 18 to 32 which is a smoke detector.
PCT/AU2008/000316 2007-03-09 2008-03-07 Particle detection apparatus Ceased WO2008109933A1 (en)

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AU2007901284A AU2007901284A0 (en) 2007-03-09 Particle detection apparatus
AU2007901284 2007-03-09

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