Photoelectric smoke sensor tube

Abstract

A smoke detector for an air duct includes a photoelectric detection system and an air flow path in fluid communication with the air duct. The air flow path includes an inlet, an optical tube, and an outlet. The photoelectric detection system includes a circuit board having at least one light emitter and at least one light receiver mounted thereon. The optical tube passes through the circuit board and between the at least one light emitter and the at least one light receiver.

Description

Technical Field

[0001] Embodiments disclosed herein relate to smoke detectors, and more particularly to photoelectric smoke detectors for air ducts. Background Art

[0002] A smoke detector is a device that detects smoke and sounds an alarm. A photoelectric smoke detector operates based on the principle of light reflection and generally consists of a light emitter, a light receiver, and an optical chamber. When smoke is absent from the optical chamber and the chamber is empty or nearly empty, the light receiver typically receives a small amount of light reflected from the chamber surfaces. On the other hand, when smoke is present in the optical chamber, the light receiver receives more light due to light reflected from smoke particles. When the amount of received light exceeds a threshold level, an alarm is triggered.

[0003] Detectors for sensing one or more conditions within the ductwork of a heating, ventilation, and air conditioning system are typically mounted to a flange or other member and / or the outside of the air duct and include a sampling tube extending laterally from the outside into the ductwork. Air within the ductwork flows into an inlet formed in the sampling tube and into a smoke sensor located in a housing outside the ductwork. The air then returns to the interior of the ductwork via an outlet flow tube.

[0004] Dust and debris can accumulate within smoke detectors, leading to false alarms and frequent maintenance.A need exists for improved methods of detecting smoke in air ducts. Summary of the Invention

[0005] According to one embodiment, a smoke detector for an air duct includes a photoelectric detection system and an air flow path in fluid communication with the air duct. The air flow path includes an inlet, an optical tube, and an outlet. The photoelectric detection system includes a circuit board having at least one light emitter and at least one light receiver mounted thereon. The optical tube passes through the circuit board and between the at least one light emitter and the at least one light receiver.

[0006] Additionally or alternatively to one or more of the above features, in a further embodiment, at least one light emitter comprises a light emitting diode.

[0007] In addition to or alternatively to one or more of the above features, in a further embodiment, the optical tube absorbs infrared light.

[0008] In addition to or alternatively to one or more of the above features, in a further embodiment, the smoke detector further includes a cleaning port.

[0009] In addition to or alternatively to one or more of the above features, in a further embodiment, at least one optical receiver comprises a photodiode.

[0010] In addition to or alternatively to one or more of the above features, in a further embodiment, at least one light receiver receives light at different angles.

[0011] In addition to or as an alternative to one or more of the above features, in a further embodiment, the optical tube comprises an optical window.The optical tube may have antistatic or hydrophobic properties.

[0012] In addition to or alternatively to one or more of the above features, in further embodiments, the optical tube is removable.

[0013] In addition to or as an alternative to one or more of the above features, in a further embodiment the photodetection system further comprises at least one reflector.

[0014] According to another embodiment, a method for detecting smoke in an air duct includes: emitting light into an optical tube; receiving light from the optical tube at multiple angles; and comparing the emitted light to the received light, wherein the optical tube includes an optical window and is located in an air flow path in fluid communication with the air duct, and wherein the photoelectric detection system includes a circuit board having at least one light emitter and at least one light receiver mounted thereon, and further wherein the optical tube passes through the circuit board between the at least one emitter and the at least one light receiver.

[0015] In addition to or as an alternative to one or more of the above features, in a further embodiment the photodetection system comprises at least one reflector.

[0016] In addition to or alternatively to one or more of the above features, in further embodiments, the photoelectric detection system detects scattered light from multiple angles and compares the emitted light to the received light to distinguish smoke from other types of predetermined conditions.

[0017] According to another embodiment, a method of maintaining a smoke detector for an air duct includes removing an optical tube from an air flow path and cleaning or replacing the optical tube, wherein the air flow path is in fluid communication with the air duct and the smoke detector includes a photoelectric detection system including a circuit board having at least one light emitter and at least one light receiver mounted thereon, and further wherein the optical tube passes through the circuit board between the at least one emitter and the at least one light receiver. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following description should not be considered limiting in any way. Referring to the accompanying drawings, like elements are numbered alike:

[0019] Figure 1 is a side view of a smoke detector system;

[0020] Figure 2 is the cross section of the smoke detector system; and

[0021] Figure 3 is a top view of a smoke detector system. DETAILED DESCRIPTION

[0022] A smoke detector for an air duct includes an air flow path in fluid communication with the air duct and a photoelectric detection system. The air flow path includes an inlet, an optical tube, and an outlet. The photoelectric detection system includes a circuit board having at least one light emitter and at least one light receiver mounted thereon. The optical tube passes through the circuit board and between the at least one light emitter and the at least one light receiver. By locating the optical components out of the air flow, dust accumulation is reduced.

[0023] The optical tube includes an optical window located adjacent to at least one light emitter and at least one light receiver. The optical tube is removable for cleaning or replacement.

[0024] A detailed description of one or more embodiments of the disclosed apparatus and method is given herein by way of example and not limitation with reference to the accompanying figures.

[0025] Figure 1 A smoke detector 10 is shown having an air flow path 20. The air flow path 20 includes an inlet 30, an outlet 40, and an optical tube 50. The photoelectric detection system 70 includes a circuit board 60 and an optical mount 65. The optical tube 50 passes through an opening in the circuit board 60 and is located between at least one light emitter 90 and at least one light receiver 100 (at Figure 2 The air flow path is in fluid communication with an air duct (not shown). As air moves through the air duct, a portion of the air enters inlet 30 and moves through the air flow path, passing through optical tube 50, and continues through path 20, ultimately exiting outlet 40 and rejoining the air passing through the duct. Photoelectric detection system 70 can use multi-wavelength, multi-angle detection technology to distinguish between smoke and non-smoke (such as water vapor).

[0026] The air flow path 20 may have a receiving end (not shown) that facilitates removal and replacement of the optical tube. The optical tube 50, the receiving end, or both may include a seal or gasket to secure the optical tube 50 to the air flow path 20 and prevent air from escaping the optical tube 50 and the air flow path 20 before exiting the outlet 40. There may be an optional cleaning port 110 ( Figure 3 ) to help clean the optical tube. For example, compressed air can be used to force dust or accumulated material through the optical tube 50. Dust and accumulated material may cause the light in the optical tube 50 to be obscured.

[0027] Optical tube 50 absorbs infrared light and may be made of an infrared-absorbing material or coated with an infrared-absorbing coating. Optical tube 50 includes an optical window 55 to enable detection and, optionally, measurement of smoke and other materials. Optical window 55 transmits greater than or equal to 90% of the light transmitted by the detection system for effective detection and / or measurement and may be made of a polymer, glass, or other suitable transparent material. The optical window may exhibit antistatic and / or superhydrophobic properties in the form of a coating that facilitates cleaning of the optical window. Antistatic and / or superhydrophobic properties may also reduce the likelihood of particles becoming lodged on the optical window and interfering with detection, measurement, or both. Optical tube 50 may have any shape that does not interfere with the detection system (note that certain angles may result in excessive reflectivity of light from the tube surface, which can increase light scattering or noise and, therefore, interfere with detection accuracy). Exemplary cross-sectional shapes include circular, square, rectangular, and hexagonal.

[0028] The photodetection system 70 includes a circuit board 60 having at least one light emitter 90 and at least one light receiver 100 mounted thereon. An optical tube extends through an opening in the circuit board. The at least one light emitter 90 is positioned to emit light into the optical tube, and the light receiver 100 is positioned to receive light from the at least one emitter 90 at a desired angle. In other words, the optical tube 50 is located between the at least one light emitter 90 and the at least one light receiver 100. In some embodiments, the photodetection system further includes at least one reflector (not shown). The reflector can be used to generate light at multiple angles from a single emitter.

[0029] Photoelectric detection system 70 uses light to assess the amount of air (in this example, the amount of air within optical tube 50) present in relation to a condition, such as a fire or other hazard. Photoelectric detection systems can also be used to monitor conditions such as air quality. Throughout this specification, the term "light" refers to coherent or incoherent radiation at any frequency or combination of frequencies in the electromagnetic spectrum. In this example, photoelectric system 70 uses light scattering to determine the presence of particles in the surrounding atmosphere, indicating the presence of a threshold condition or event. Throughout this specification, the term "scattered light" can encompass any change in the amplitude / intensity or direction of incident light, including reflection, refraction, diffraction, absorption, and scattering in any / all directions. In this example, light is emitted through an optical window into a designated area within optical tube 50. When the light encounters an object (e.g., a smoke particle or gas molecule), it is scattered and / or absorbed due to the different refractive index of the object compared to the surrounding medium (air). Depending on the object, the light can be scattered in all different directions. Detecting the light scattered by the object can provide information about the designated area within optical tube 50, including determining the presence of a threshold condition or event.

[0030] Light scattering is due to the physics of how light interacts with the atoms or surfaces of a material. For light emitted from a source, the angle of redirection depends on the material composition and geometry. The redirection of light can be isotropic, where each angle receives the same amount of radiation. Alternatively, the redirection of light can be anisotropic, where a certain amount of light is redirected inconsistently with respect to angle. The amount of anisotropy depends on the optical, electronic, and magnetic properties combined with the geometric properties of the material. Anisotropy is also frequency-dependent. In practice, this principle can be used to distinguish one material from another; one group of materials from another; or combinations of materials and groups of materials.

[0031] In its most basic form, the photodetection system 70 includes at least one light emitter 90 and at least one light receiver 100. The at least one emitter 90 is capable of emitting multiple wavelengths. The receiver 100 is capable of detecting (receiving) multiple wavelengths. Exemplary light emitters include light emitting diodes (LEDs). The ability to emit and detect multiple wavelengths facilitates distinguishing between different types of materials in a sample volume. Exemplary light receivers include photodiodes. The photodetection system may further include at least one reflector.

[0032] Light from emitter 90 is transmitted through optical tube 50. The light interacts with any particles present in optical tube 50 and is reflected or transmitted to receiver 100. Comparison of changes in the light provided by emitter 90 and / or the light received by receiver 100 will indicate whether there is an atmospheric change in optical tube 50 that causes light scattering. Scattered light, as described herein, is intended to include reflected light, transmitted light, and absorbed light. Although the detection system is described as using light scattering to determine a condition or event, embodiments that use light obscuration, absorption, and fluorescence in addition to or in lieu of light scattering are also within the scope of this disclosure.

[0033] The detection system 70 can be used to distinguish smoke from other types of hazardous conditions or nuisances. Each emitter is associated with one or more receivers for collecting / receiving scattered light from the sampling space 50. Each of the multiple receivers is oriented at a different angle relative to the emitter. For example, a first angle is formed between the emitter and the first receiver, and a second angle is formed between the emitter and the second receiver. The first angle and the second angle are known and different. In some embodiments, the different angles can be achieved by physically orienting / positioning the receivers differently. In other embodiments, the different angles can be achieved by using multiple emitters. In some embodiments, reflectors can be used to generate the angles.

[0034] A control system (not shown) can be used to manage the operation of the detection system 70 and can include component control, data acquisition, data processing, and data analysis. The control system can be located on the circuit board 60. The control system includes a processor and memory. Exemplary processors include microprocessors, system-on-chips (SOCs), field programmable gate arrays (FPGAs), and the like. At least one receiver can be configured to convert the received scattered light into a corresponding signal that can be received by the processor. The signal output can be compared by the processor to the signal from the emitted light to determine whether a threshold condition exists.

[0035] Signals received by or output from the multiple receivers may be amplified and / or filtered, such as by a comparator, to reduce or eliminate irrelevant information within the signals before being transmitted to a remotely located control unit. In such embodiments, amplification and filtering of the signals may occur directly within the multiple receivers, or alternatively, may occur via one or more components disposed between the receivers and the control unit. The control unit may control data acquisition by the receivers, such as by adjusting amplifier gain, filter bandwidth, sampling rate, timing, and data buffering.

[0036] In addition to being operably coupled to at least one transmitter and a plurality of receivers, the control unit may also be associated with one or more input / output devices. In embodiments, the input / output devices may include alarms or other signals, or fire suppression systems that are triggered upon detection of a predefined event or condition. It should be understood that the term "alarm," as used herein, may refer to any of the possible outcomes of a detection.

[0037] The term "about" is intended to include the degree of error associated with the measurement of the particular quantity based on the equipment available at the time the application is filed.

[0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, indicate the presence of the specified features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039] Although the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the basic scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed as the best mode for carrying out the concepts of the present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A smoke detector for an air duct, comprising a photoelectric detection system and an air flow path in fluid communication with the air duct, wherein the air flow path includes an inlet, an optical tube, and an outlet, and the photoelectric detection system includes a circuit board having at least one light emitter and at least one light receiver mounted thereon, and further wherein the optical tube passes through the circuit board between the at least one light emitter and the at least one light receiver.

2. The smoke detector according to claim 1, wherein: The at least one light emitter comprises a light emitting diode.

3. The smoke detector according to claim 1 or claim 2, characterized in that: The optical tube absorbs infrared light.

4. The smoke detector according to claim 1 or claim 2, characterized in that: The smoke detector further includes a cleaning port.

5. The smoke detector according to claim 1 or claim 2, characterized in that: The at least one light receiver includes a photodiode.

6. The smoke detector according to claim 1 or claim 2, characterized in that: The at least one light receiver receives light at different angles.

7. The smoke detector according to claim 1 or claim 2, characterized in that: The optical tube includes an optical window.

8. The smoke detector according to claim 7, wherein: The optical window has antistatic or hydrophobic properties.

9. The smoke detector according to claim 1 or claim 2, characterized in that: The optical tube is removable.

10. The smoke detector according to claim 1 or claim 2, characterized in that: The photoelectric detection system further includes at least one reflector.

11. A method for detecting smoke in an air duct using the smoke detector according to any one of claims 1 to 10, comprising: emitting light into the optical tube; receiving light from the optical tube at a plurality of angles; as well as The emitted light is compared to the received light.

12. The method according to claim 11, characterized in that The photoelectric detection system detects scattered light from multiple angles and compares the emitted light to the received light to distinguish smoke from other types of conditions.

13. A method of maintaining a smoke detector for an air duct, comprising: and removing the optical tube from an air flow path, and cleaning or replacing the optical tube, wherein the air flow path is in fluid communication with the air duct, and the smoke detector includes a photoelectric detection system, the photoelectric detection system including a circuit board having at least one light emitter and at least one light receiver mounted thereon, and further wherein the optical tube passes through the circuit board between the at least one light emitter and the at least one light receiver.

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