Patent Application
20150022363
The application pertains to smoke detectors. More particularly, the application pertains to aspirated smoke detectors which receive smoke samples from a plurality of locations.
Some commercial installations for aspirated smoke detectors require a larger area of coverage than single channel products are capable of meeting. In order to cover a larger area, a multichannel smoke detector is needed. For cost purposes, it is desirable to only use one smoke sensing chamber. But, if air is being sampled from multiple pipes to the one chamber, the user still needs to know which pipe (channel) the smoke came from. This can be done mechanically via valves and actuators, but this is complex, slow, and expensive.
While disclosed embodiments can take many different forms, specific embodiments hereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles hereof, as well as the best mode of practicing same, and is not intended to limit the claims hereof to the specific embodiment illustrated.
In accordance herewith, electronic gas or smoke sensing, on a per channel basis, can be combined with a common smoke chamber which receives smoke from multiple, different locations. Multiple ambient condition sensors, such as gas or smoke sensors, can be coupled to a manifold that combines multiple ambient air inflow channels to a single out flow that enters the smoke sensing chamber.
The ambient condition sensors can be activated after smoke is detected by the sensing chamber in order to determine, electrically, which input is the source of the detected smoke. By way of example only, and not limitation, a metal oxide semiconductor gas sensor can be coupled to each of the inflow channels. Those of skill will understand that other types of gas or smoke sensors come within in the spirit and scope hereof. For example, electro-chemical gas sensors, photoelectric smoke sensors or the like, all without limitation, could also be used.
Metal oxide gas sensors are cross sensitive to a variety of gases that are produced by a range of fire types and are not subject to false alarm due to dust. They can be activated after the smoke chamber detects smoke. As a result, less signal processing is needed and power consumption is reduced.
Metal oxide gas sensors are typically available in TO-type packaging that can be fitted into a hole in the sampling tube or manifold. For example, a four channel device would use one smoke sensing chamber and four MOS gas sensors fitted to a four-to-one manifold.
Each of the conduits or pipes Ci is coupled to a respective inflow port 10a, b, c . . . n of the detector 10. Each of the inflow ports 10i is coupled to a respective Stage 1 ambient condition sensor, such as a gas or smoke sensor Si. The particular details of the sensors Si are not a limitation hereof. Sensor Si can be continuously or intermittently energized without limitation. Each of the sensors Si is coupled by a respective pipe or conduit to a manifold 12.
Manifold 12 combines each of the n inflow conduits, such as 12a, 12b . . . 12n to a single output flow conduit, or pipe 14 which is in turn coupled to an inflow port 16a of main sensing chamber 16. Ambient air, which might be carrying smoke or gas of interest, flows from manifold 12, via conduit 14 into chamber 16, where a gas or smoke sensing process can be carried. That air exits chamber 16, via outflow port 16b and an aspirator 18.
Control circuits 20, of the detector 10, are coupled to each of the Stage 1 sensors Si via cables 16-1, as well as to the main sensing chamber 16 by cables 16-2. Control circuits 20 can implement gas and/or smoke processing as in exemplary method 100 discussed subsequently. Control circuits 20 could be implemented, at least in part, via a programmable processor 20a and local control software 20b.
Control circuits 20 can communicate via a wired or wireless medium 22 with a displaced monitoring system control unit 24. It will be understood that details of the control unit 24 are not limitations hereof.
Control circuits 20 can determine which of the sensors Si are detecting gas or smoke, as at 110. The conduit or pipe, Ci through which the gas or smoke is flowing can then be identified. This in turn specifies the Protected Space i from which the gas, or smoke is being drawn. Circuits 20 can then emit an appropriate alarm indictor to the control unit 24.
From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.
Further, logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Other steps may be provided, or steps may be eliminated, from the described flows, and other components may be add to, or removed from the described embodiments.
