Abstract:
A particle detection unit including a detection chamber and a duct detector is disclosed. The duct detector is disposed within the detection chamber. The duct detector has a rod with a first and a second end where the first end is distal the second end. A reflector may be attached to the rod adjacent the first end. A sensor and emitter device may be attached to the rod and spaced apart from the reflector.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present disclosure relate to the field of duct or chamber systems. More particularly, the present disclosure relates to a system and method for detecting unwanted foreign particles within a duct or air handling system. 
     2. Discussion of Related Art 
     In air handling or ventilation systems (HVAC), fans draw fresh outside air into a building, and exhaust stale interior air to the outside. These air handling systems use venting or ducts (i.e. ductwork) to provide an air flow path throughout the building, including to and from heaters and/or air conditioners. To assist in adjusting the volume of air flow, volume control dampers and fans may be used. These dampers and fans can be fitted within the ducts themselves and may be manually or automatically activated. 
     On occasion, unwanted foreign particles may enter the ductwork of such air handling systems. For example, in the case of a fire, smoke may enter the ductwork. To control the spread of smoke throughout the duct system and subsequently other rooms of the building, smoke dampers may be used which may be automated with the use of a mechanical motor, often referred to as an actuator. For example once smoke is detected by a sensor within the duct, the sensor sends a signal to the actuator to close the smoke damper. A signal may also be sent from the sensor to shut down the fans thereby limiting the spread of smoke through the ducts which would otherwise travel to other rooms or parts of the building. Thus, detectors/sensors may be located throughout the ductwork of a building to detect the presence of smoke which triggers the control of fans and dampers to prevent smoke from traveling or spreading to unwanted areas therein. 
       FIG. 1  is a functional depiction of a conventional duct sensor  100  used to detect smoke within a duct. The duct sensor  100  includes a sampling tube  110 , a smoke sensor  120 , and exhaust tube  130 . The sampling tube  110  is used to collect the smoke and then to guide the air through the smoke sensor  120 . After passing through the smoke sensor  120 , the air is then released through the exhaust tube  130 . If smoke is detected by the smoke sensor  120 , display  140  indicates the detection of smoke by the duct sensor  100 . Those of ordinary skill in the art will recognize that the depicted system is highly-simplified for ease of explanation. 
       FIG. 2  illustrates a cross-sectional view of conventional duct sensor  200  attached to duct  240 , the walls of which define duct chamber  240   a . Smoke sensor  220  is attached to housing  260  and is located outside of duct  240 . Housing  260  is connected to exhaust tube  230  and sampling tube  210 . To attach housing  260  to duct  240 , two holes  215 A and  215 B must be formed in a wall of the duct to allow sampling tube  210  and exhaust tube  230  to project into duct chamber  240   a  respectively. As such, this requires two holes for every duct sensor that is attached to a portion of the ductwork. To prevent room particles from entering the duct system or duct particles from entering the room, gaskets or other means (not shown) must be used to seal the two holes. Thus, there exists a need for a new and improved duct sensor/detector to reduce the number of holes that need to be created in a duct system. 
     Sampling tube  210  also includes access holes  250  for capturing air that flows through duct  240 . To prevent sampling tube  210  from recapturing exhausted smoke from exhaust tube  230 , sampling tube  210  must be located upstream of exhaust tube  230 . This means that exhaust tube  230  must be positioned downstream of sampling tube  210  when attaching the duct sensor  200  to the duct system. Thus, conventional duct sensor  200  must be properly oriented to allow the duct to funnel air in through sampling tube  210 , across sensor  220  via housing  260 , and out through exhaust tube  230 . Hence, there exists a need for a new and improved duct sensor to eliminate possible orientation errors when installing a duct sensor/detector. 
     Furthermore, air must be flowing through the duct to allow conventional sensor  220  to sample the air in the duct. Therefore, before a conventional duct sensor  200  can be properly tested to make sure the smoke sensor  220  is operating properly, it must be verified that air is flowing within the duct. Thus, in an effort to properly test the smoke sensor  220  and to make sure air is flowing within the duct, a device may be required to be placed within the duct before testing. This device measures the airflow or differential pressure of the duct to indicate whether or not airflow is present around the sensor  220 . Without these additional devices, it may be impossible to know whether the smoke supplied for testing has reached the sensor  220  or if the smoke has traversed through the device that measures differential pressure which may compromise testing. Thus, there exists a need for a new and improved duct sensor/detector to eliminate the need for air flow testing. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the present disclosure are directed to a particle detection unit including a detection chamber; a duct detector disposed within the detection chamber, comprising a rod having a first and a second end, the first end distal the second end, a reflector attached to the rod adjacent the first end, and a sensor/emitter device attached to the rod and spaced apart from the reflector at the second end wherein particles disposed between the first and second ends are detected. 
     In another exemplary embodiment, a particle detection unit includes a detection chamber; a duct detector disposed at least partially within the detection chamber, and having a sensor attached to an inner wall of the detection chamber. An emitter is attached to the inner wall of the detection chamber opposite the sensor. In another exemplary embodiment, a particle detection unit includes a detection chamber and a duct detector, disposed within the chamber which is defined by a rod having a first and a second end. The first end is distal the second end. An emitter is attached to the rod adjacent the first end, and a sensor is attached to the rod and spaced apart from the reflector. 
     In an exemplary method, a duct detector is installed within a detection chamber defined by a wall having an inner surface. The duct detector is attached to the inner surface of the duct and smoke is detected within the chamber. The duct detector comprises a rod having a first and a second end. The first end is distal the second end and a reflector is attached to the rod adjacent the first end. A sensor and emitter device is attached to the rod and spaced apart from the reflector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a functional diagram of a conventional duct sensor. 
         FIG. 2  is a cross sectional view of a conventional duct sensor attached to a duct. 
         FIG. 3  is a cross sectional view of a duct detector in accordance with the present disclosure. 
         FIG. 4  is a side view depiction of a duct detector in accordance with the present disclosure. 
         FIG. 5  is a side view depiction of a duct detector including a telescoping rod in accordance with the present disclosure. 
         FIG. 6  is a side view depiction of a duct detector without a rod in accordance with the present disclosure. 
         FIG. 7   a  is a side view depiction of a cover in accordance with the present disclosure. 
         FIG. 7   b  is a front view depiction of a cover in accordance with the present disclosure. 
         FIG. 8  is a side view depiction of a duct detector within a tubular rod in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings like numbers refer to like elements throughout. 
       FIG. 3  shows a cross-sectional view of an exemplary duct detector  300  consistent with one embodiment of the present disclosure. Those of ordinary skill in the art will recognize that the depicted system is highly-simplified for ease of explanation. In this exemplary embodiment, the duct detector  300  is inserted and attached to an air duct  310 . The shape of the duct is defined by the duct walls. Generally, an improved duct detector is inserted or attached to any chamber or other confined space such as, for exemplary purposes only, ductwork, plenums, air handlers, silos, etc. 
     Duct detector  300  includes a rod  320  which has a reflector  330  coupled to the distal end of the rod  320 . A sensor and emitter (sensor/emitter) device  340  is spaced apart from the reflector  320  and is also coupled to the rod  320 . The sensor and emitter device  340  may contain both a light sensor and emitter. As depicted, the rod  320  including the reflector  330 , and sensor and emitter device  340 , is inserted into the chamber of duct  310 . To insert duct detector  300  into the duct  310 , a single penetration hole (not shown to scale) may be made in the duct  310  the size of which is dependent on the size of the sensor and emitter device  340 , rod  320 , and reflector  330 . The rod may be hollow to accommodate wiring to and from the sensor and emitter device  340  and reflector  330 . The rod  320  may then be attached, for example, to the duct  310  by any means known in the art. Thus, with this embodiment only a single penetration hole may be created in the duct  310  housing to accommodate rod  320 , reflector  330 , and sensor and emitter device  340 . This embodiment advantageously reduces the number of holes needed in the duct housing as compared to using a conventional duct detector  200  where two holes must be created to allow for sampling tube  210  and exhaust tube  230  to penetrate into the duct as shown in  FIG. 2 . 
     With this embodiment, the sensor/emitter device  340  and the reflector  330  are used to detect particles (i.e., smoke) within the duct. The reflector  330  along with the sensor/emitter device  340  use technology that is similar to a beam detector for detecting particles (i.e., smoke) in the air. In particular, light from the emitter portion of emitter/sensor  340  is transmitted within the duct  310  toward reflector  330  which reflects the light back toward sensor portion of emitter/sensor  340 . When particles are present within the air within duct  310 , the sensor portion of emitter/sensor  340  will not receive the same amount of light emitted by the emitter portion of emitter/sensor  340 . More specifically, it is the difference between the amount of light produced by the emitter and the amount of light received by the sensor via the reflector  330 , as well as the distance between the sensor  340  and reflector  330  which is used to calculate the percentage of obstructed light. This percentage of light obstruction is used to determine the presence of unwanted particles (i.e., smoke) between the emitter and the sensor. Generally, percent obscuration is reported per foot. Thus, if the distance between the emitter and sensor is, for example, 12 inches then the percent obscuration is the real value. However, if the distance between the emitter and sensor is 6 inches, then the percent obscuration is reported as two times the value since the light is only going half the distance. Thus, when the percentage of obstructed light exceeds a predetermined threshold an alarm is triggered. The duct detector  300  communicates with alarm indicating devices via control modules and/or control panels through wired or wireless connections  350  which may be, for example, bells, alarms, LED indicators, displays, etc. 
     By inserting the sensor and emitter device  340  into the duct  310 , the duct detector  300  uses the duct itself as a chamber for detecting particles (i.e., smoke). Thus, rather than placing the sensor and emitter device  340  outside of the duct and guiding the air across the sensor as in duct sensor  200  described above, the sensor and emitter device  340  are placed within the duct  310 , thereby eliminating the need to test whether or not air is flowing prior to testing the sensors. In this manner, the need to use airflow and differential pressure devices to detect airflow within the duct  310  prior to the testing is advantageously eliminated. 
     Likewise, because the duct  310  may now be used as the sensing chamber, the duct detector  300  eliminates the orientation problems described above with respect to conventional smoke detector  200 . More specifically, upstream and downstream orientation concerns regarding sampling tube  210  and exhaust tube  230  are eliminated. The airflow is no longer depended on to guide the smoke out of the duct to the sensor  220 . The sensor and emitter device  340  are now located within the duct itself. In addition, the spacing between the sensor/emitter and thus the distance the light travels from the sensor portion of emitter/sensor  340  to reflector  330  and back to the sensor portion of emitter/sensor  340  may be much closer as compared to convention beam detectors. 
     Groups of duct detectors may be installed within an air handling systems and wired together along a pair of bidirectional communication lines. A group of such devices on a pair of lines is often referred to as a “line of devices.” Many lines of devices can connect back to a control panel that controls the operation of an alarm system. A line of devices is usually associated with a certain zone of the building and/or a certain type of device. For example, one floor of a multi-story building may have duct detectors wired together on a line that connects back to the control panel. Also, each duct detector on a line may be individually addressed from the control panel. Addressing individual devices allows a single duct detector to indicate an alarm condition at a specific location on a line, provides selective operation of specific duct detectors, and can also be useful for fault diagnosis and/or individual duct detector testing. 
     To perform fault diagnosis and/or individual duct detector testing, a self test mode may be used to eliminate the need to perform a smoke test. Smoke tests are undesirable because actual smoke is introduced into the duct and forced by the sensor. Rather than triggering an alarm indicating device by obstructing the light between the sensor and emitter or sensor/emitter device and reflector with smoke, the emitter&#39;s light output may be decreased or obstructed by other means to trigger an alarm indicating device. 
     One exemplary way to implement a self test mode to test a sensor may be to decrease the light that is emitted by the emitter or reflected by the reflector. Reducing the amount of light received by the sensor simulates the light reduction caused by smoke. Reducing the light received by the sensor may be caused by decreasing the light output of the emitter&#39;s LED or by decreasing the reflection characteristics of the reflector. Once, the light output is decreased the sensor may measure the reduction in light and trigger an alarm indicating device as discussed above. 
     Another exemplary embodiment used to test a sensor may be to implement a lens or filter to decrease the light that is detected by the sensor. The lens or filter may be placed within the light path between the emitter/sensor. By placing the lens or filter within the light path, the light received by the sensor is reduced thereby simulating the obstruction of light caused by smoke. Additionally, the lens or filter may be electro-mechanically inserted into the light path by any means known in the art, such as a relatively small motor. Generally, self test mode devices such as, the lens, filter, and LED for the light reduction or output of the emitter, may all be controlled remotely from a control panel as described above. 
       FIG. 4  shows a cross-sectional view of a duct detector  400  consistent with one embodiment of the present invention. Those of ordinary skill in the art will recognize that the depicted system is highly-simplified for ease of explanation. The duct detector  400  is inserted and attached to an air duct  410 . The duct detector  400  includes a rod  420  and a sensor  430  which is attached to a distal end of the rod as illustrated in  FIG. 4 . Opposite the sensor  430 , an emitter  440  may be attached to the rod  420 . Conversely, the position of the emitter  440  may be interchanged with the position of the sensor  430 . 
     To insert the duct detector  400  into the air duct  410 , a single penetration hole may be made in the wall of duct  410 . The size of the penetration hole may be dependent on the size of the sensor  430 , the emitter  440 , and the rod  420 . With this embodiment, it is the sensor  430  and emitter device  440  that are used to detect particles (i.e., smoke) within the duct. For example, the sensor  430  and emitter  440  may use technology that is similar to a beam detector for detecting particles (i.e., smoke) in air. However, the spacing between the sensor  430  and the emitter  440  may be used at much closer distances as compared to a beam detector. More specifically, it is the difference between the amount of light produced by the emitter  440  and the amount of light that is received by the sensor  430 , as well as the distance between the two that is used to calculate the percent obscuration of the light. This percent of obscuration may be used to determine the presence of particles (i.e., smoke) between the emitter  440  and the sensor  430 . Thus, as described above with reference to duct detector  300 , when the percentage of obscuration passes a predetermined threshold, an alarm is triggered by duct detector  400 . Again, to trigger an alarm or implement a self test mode, duct detector  400  may be in communication with alarm indicating devices or central control panels through wired or wireless connections  450 . Additionally, to trigger an alarm, duct detector  400  may be also be equipped with self test mode devices, as described above with reference to  FIG. 3 . This eliminates the need for a smoke test when testing the sensor of duct detector  400 . 
       FIG. 5  shows a cross-sectional view of a duct detector  500  consistent with one embodiment of the present invention. Those of ordinary skill in the art will recognize that the depicted system is highly-simplified for ease of explanation. The duct detector  500  is inserted and attached to an air duct  510 . However, as depicted in  FIG. 5 , rods  320  and  420  of  FIGS. 3 and 4 , respectively, are substituted by a telescoping rod  520 . The use of a telescoping rod  520  may be used to more easily adjust how far rod  520  penetrates the chamber of the duct  510 . Here again, duct detector  500  may implement a sensor and emitter device  540  along with a reflector  530  as described with relation to  FIG. 3 . Duct detector  500  may also implement a sensor and emitter configuration as described with relation to  FIG. 4 . With either configuration a single penetration hole may be made in the duct  510  prior to inserting duct detector  500  into air duct  510 . The size of the penetration hole may be dependent on the size of the duct detector  500 . The telescoping rod  520  may then be substantially attached, for example, to the wall of the duct  510  by any means known in the art. 
     As described above with reference to duct detector  300 , when the percentage of obscuration passes a predetermined threshold, an alarm indicating such may be triggered by duct detector  500 . Again, to trigger an alarm or implement a self test mode, duct detector  500  may be in communication with alarm indicating devices or central control panels through wired or wireless connections  550 . Additionally, to trigger an alarm, duct detector  500  may also be equipped with self test mode devices, as described above with reference to  FIG. 3 . This eliminates the need for a smoke test when testing the sensor of duct detector  500 . 
       FIG. 6  illustrates a cross-sectional view of a duct detector consistent with one embodiment of the present invention. Those of ordinary skill in the art will recognize that the depicted system is highly-simplified for ease of explanation. The duct detector  600  is substantially inserted and attached to opposing walls of air duct  610 . However, as depicted in  FIG. 6 , rods  320  and  420  of  FIGS. 3 and 4 , respectively, are removed. Here again, duct detector  600  may implement a sensor and emitter device  640  along with a reflector  630  as described with relation to  FIG. 3 . However, sensor and emitter device  640  is attached to a wall of the duct  610  substantially opposite reflector  630 . Duct detector  600  may also attach a sensor to the wall of the duct  610  substantially opposite an emitter. Any means known in the art may be used to attach the sensor and emitter device  640 , reflector  630 , emitter, or sensor to the wall of the duct and may be dependent on the size of the sensor and emitter device  640 , reflector  630 , emitter, or sensor used for the duct detector  600 . 
     As described above with reference to duct detector  300 , when the percentage of obstruction passes a predetermined threshold an alarm indicating such may be triggered by duct detector  600 . Again, to trigger an alarm or implement a self test mode, duct detector  600  may be in communication with alarm indicating devices or central control panels through wired or wireless connections  650 . Additionally, to trigger an alarm, duct detector  600  may be also be equipped with self test mode devices, as described above with reference to  FIG. 3 . This eliminating the need for a smoke test when testing the sensor of duct detector  600 . 
       FIGS. 7   a  and  7   b  illustrate one exemplary embodiment of a cover  700 .  FIG. 7   a  depicts a side view of the cover  700  and  FIG. 7   b  depicts a front view of cover  700 . The cover  700  may be coupled to a rod, telescoping rod, duct wall, sensor/emitter device, sensor, emitter, or reflector. The cover may be used to substantially prevent particles (i.e., dust) from accumulating on a sensor and emitter device, reflector, sensor, and emitter. Whatever shape used, the cover  700  substantially prevents dust accumulation while still allowing the emitter, sensor, and reflector to emit, sense, and reflect light  710 , respectively. By covering the above mentioned structures, particles such as dust may be substantially prevented from overwhelming the structures. This may in turn prolong the accuracy of the duct detector in detecting particles (i.e., smoke) within a duct. By substantially preventing particles from overwhelming the sensor, emitter, and reflector structures the duct detector may substantially maintain its accuracy for detecting smoke for longer periods of time. 
       FIG. 8  shows a side view of a duct detector  800  consistent with one embodiment of the present invention. Those of ordinary skill in the art will recognize that the depicted system is highly-simplified for ease of explanation. The duct detector  800  is substantially inserted and attached to an air duct  810 . However, as depicted in  FIG. 8 , rods  320  and  420  of  FIGS. 3 and 4 , respectively, are substituted by a substantially tubular rod  820 . The use of a tubular rod  820  may be used to protect the sensor and emitter device, sensor, emitter, or reflector while allowing smoke or other particles to travel through ventilation structures  830 . By implementing a sensor and emitter device within the tubular rod  820 , and on one side of the ventilation structures  830 , and a reflector within the tubular rod  820 , and on the other side of the ventilation structure  830 , the particles (i.e., smoke) may pass through the tubular rod  820  and in between the sensor and emitter device and reflector. Likewise, the duct detector  800  may also implement a sensor and emitter within the tubular rod  820 . The sensor located within the tubular rod  820  across from the emitter which may also be located substantially within the tubular rod  820 . Between the sensor and emitter, ventilation structures  830  may be used to allow particles (i.e., smoke) to pass through the tubular rod  820  and enter the line of site between the emitter and sensor. With either configuration a single penetration hole may be made in the duct  810  prior to inserting duct detector  800  into air duct  810 . The size of the penetration hole may be dependent on the size of the duct detector  800 . The tubular rod  820  may then be substantially attached, for example, to the wall of the duct  810  by any means known in the art. 
     As described above with reference to duct detector  300 , when the percentage of obstruction passes a predetermined threshold, an alarm indicating such may be triggered by duct detector  800 . Again, to trigger an alarm or implement a self test mode, duct detector  800  may be in communication with alarm indicating devices or central control panels through wired or wireless connections  850 . Additionally, to trigger an alarm, duct detector  800  may be also be equipped with self test mode devices, as described above with reference to  FIG. 3 . This eliminates the need for a smoke test when testing the sensor of duct detector  800 . 
     The improved duct detector disclosed herein advantageously reduces the number of holes required to install a duct detector within a duct system. In fact, only one installation hole may be created within the duct per at least one duct detector that is to be installed within a duct. 
     The improved duct detector disclosed herein advantageously uses the duct itself as a chamber for detecting particles (i.e., smoke) which obviates the need to use airflow and differential pressure devices. Thus, there is no longer a need to confirm the presence of airflow before testing the operability of the duct detectors. Likewise, upstream and downstream orientation concerns regarding exhaust tubes and sampling tubes are eliminated by implementing the improved duct detector. Furthermore, the improved duct detector allows for self testing with a self test mode. Consequently, the improved duct detector reduces the labor costs and hazards associated with manufacturing, installing, and testing duct detectors. 
     While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.