Patent Document

TECHNICAL FIELD 
     The present invention relates to a device for an extractor hood. 
     BACKGROUND OF THE INVENTION 
     Extractor hoods have become a common feature in kitchens, due to their undisputed effectiveness in odor extraction. Current technological advances have led these appliances to much better performances than before, by increasing both operational versatility and extraction power. 
     There are typically two types of hoods: extraction hoods and filter hoods. 
     Extraction hoods extract air from the outside environment (e.g. the kitchen) and force it out of the environment from which it was drawn, e.g. out of the apartment or house. 
     On the other hand, filter hoods reintroduce the air they drew into the same environment, after appropriate filtering. 
     In certain countries, such as the United States of America, regulations have been approved (e.g. UL 507/CSA C22.2 no. 113), which impose that the environment from which the extractor hood draws air have a connection with the outside, if the flow of extracted air is higher than a given limit. 
     The simplest way to meet this requirement is to form a hole in the wall of the inside environment to permanently allow communication thereof with the outside environment. 
     Of course, such solution has a number of drawbacks, especially when the temperature of the outside environment is not optimal as compared with that of the inside environment (e.g. in Summer, when the inside environment may be conditioned, or in Winter when the inside environment may be heated). 
     In the light of the above described prior art, the object of the present invention is to provide an arrangement other than the one described above, to increase thermal efficiency in the environment in which the extractor hood is located. 
     Furthermore, the present invention affords advantages in terms of simple fabrication, greater strength, more compact design and/or higher versatility. 
     SUMMARY OF THE INVENTION 
     According to the present invention, the above object is fulfilled by a device for an extractor hood comprising a tubular portion, having a cross section from 5000 to 32000 mm 2 , wherein an air flow detector is arranged in said tubular portion, for detecting the air flow in said tubular portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The characteristics and advantages of the present invention will appear from the following detailed description of one practical embodiment, which is given as a non limiting example with reference to the annexed drawings, in which: 
         FIG. 1  shows a perspective view of an extractor hood comprising a device according to a preferred embodiment of the present invention; 
         FIG. 2  shows a broken-away perspective view of the device of  FIG. 1 ; 
         FIG. 3  shows a perspective view of an outer element designed to cooperate with the hood of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Although this is not expressly shown, the individual features described with reference to each embodiment shall be intended as auxiliary and/or interchangeable with other features, as described with reference to other embodiments. 
     Reference will be simply made herein to a hood installed in a kitchen, such as a domestic kitchen. 
     Of course, the technical concepts as disclosed herein may be equally understood if the hood is installed in an environment other than a domestic kitchen, for instance if it is installed in a kitchen of a restaurant or another indoor environment. 
     The extractor hood, generally referenced  1  in the figures, typically comprises a chassis  11 , an extractor motor (not shown), a control panel  13  connected to the extractor motor to regulate operation thereof, and an exhaust duct  14 , for exhausting fumes and vapors outside the kitchen or into a specially provided chimney flue. 
     Additional components may be filters, one or more lighting elements, possibly controlled by the same control panel  13  or a different control panels, and structural elements for fixation to existing or specially provided fixtures in the kitchen. 
     The present invention relates to a device, referenced  2  in the figures, for the extractor hood  1 . Such device  2  is designed to be mounted in series to the exhaust duct  14 . 
     Therefore, the device  2  comprises a tubular portion  22 , having a preferably circular or substantially rectangular section (although a different section may be also provided), and preferably extending along a predetermined longitudinal, preferably straight axis X-X (curvilinear arrangements, such as elbows, possibly 90° elbows, may be also provided, as the skilled person may appreciate from the present disclosure). 
     An air flow detector (or an anemometer)  21  is placed within the tubular portion  22 . 
     In terms of cross section perpendicular to the axis X-X, the area of the section of the tubular portion  22  ranges from about 5000 mm 2  to about 32000 mm 2 , which correspond, in a device  2  having a circular section, to a diameter ranging from 80 to 200 mm. 
     The air flow detector  21  may be a hot-wire anemometer, a Pitot tube, a cup anemometer or another kind of detector that can detect the air flow with adequate accuracy. 
     In a preferred embodiment, the detector  21  is of mechanical type, e.g. comprising an element  23  disposed transverse to the axis X-X, preferably perpendicular to such axis. 
     Advantageously, the element  23  has a flat surface, e.g. facing towards the side of the device  2  that is designed to face towards the hood side  1 , when installed. 
     According to a preferred embodiment, the element  23  comprises a thin plate; e.g. the element  23  may be substantially a sheet, typically made of metal, such as steel, gold, silver. 
     The element  23  may be joined to the tubular portion  22  by a constraint  24  that allows a limited degree of angular displacement, such as a hinge, or a device that allows a limited linear displacement (not shown). 
     The device  2  may further comprise a counteracting element (not shown), such as an elastic element or a spring (or two springs, located on either side, or more), capable of pressing or urging the element  23  to an equilibrium position, in which it is substantially transverse or in which it is perpendicular to the axis X-X (coinciding with the air flow direction designed during use). 
     Therefore, during operation of the hood  1 , the element  23  is displaced from its equilibrium position by the air flow through the device  2  due to the force exerted by the air flow on the element  23 . 
     The displacement of the element  23  from its equilibrium position obviously depends on a number of factors but, assuming that the device  2  is the same, it will only depend on the air speed through the device. 
     Therefore, the displacement of the element  23  will determine with adequate accuracy the extraction capacity of an extractor hood  1  connected in series therewith, whereby detection of the angular displacement of the element  23  will provide the air flow extracted by the extractor hood  1  from the environment in which the latter is installed, such as a kitchen. 
     Therefore, the device  2  may include a detector  26  for detecting the displacement of the element  23  from its equilibrium position. 
     The sensitivity of the detector  26  may range from a very high sensitivity to a sensitivity that only allows detection of a displacement corresponding to an air flow equal to or higher than a preset limit, e.g. the limit imposed by local standards. 
     For instance, the detector  26  may be able to generate a threshold signal Ss as a predetermined air flow is exceeded, or a first threshold signal Ss 1  as the predetermined air flow is exceeded and a second threshold signal Ss 2  as the air flow in the device  1  returns below the predetermined air flow. 
     Considering the above mentioned US standards, for instance, such limit is 400 cubic feet per minute (about 680 cubic feet per hour). 
     In a preferred embodiment, such detector  26  may be a microswitch  27  located in a position in which it is triggered as a particular displacement threshold is exceeded. 
     For instance, the microswitch  27  may be actuated by a lug  28 , joined or formed of one piece with the element  23 . 
     For instance, the lug  28  may be substantially elongate along an axis transverse to the axis X-X, e.g. along an axis coplanar with the flat surface of the element  23 . 
     The lug  28  may be placed on the side opposite to the constraint  24 , or on the same side as the latter. 
     When the element  23  is in its rest position, it may obstruct a part of the total section of the tubular portion; such part may be more than 5%, advantageously more than 10% or 15%, e.g. more than 20%, and/or less than 70%, than 60% or 50%, e.g. less than 40%. 
     In a preferred embodiment, the device  1  comprises a control element  3  capable of receiving the threshold signal Ss generated by the detector  26  and of transmitting it to an external element  4 , such as a closure element  41  for closing a passage formed between the environment in which the extractor hood  1  is installed and the outside environment. 
     Advantageously, the closure element  41  comprises a frame  42  with a passage  43  and a movable diaphragm  44 , which is adapted to selectively obstruct the passage  43 . 
     The movable diaphragm may include one or more strips, as shown in  FIG. 3 , or be formed in another equivalent manner. 
     The frame  42  and the passage  43  are of such a size as to allow an installation operator to form a passage between the kitchen (or more generally the environment in which the extractor hood  1  is installed) and the outside environment, to meet any relevant standard. 
     The external element  4  may include a control and monitoring device  45  for receiving the threshold signal/s Ss, Ss 1 , Ss 2  generated by the detector  26  and, for instance, causing the movable diaphragm  44  to open and/or close upon receipt of the threshold signal. 
     For example, the movable diaphragm  44  may be controlled to leave the passage open  43  while the threshold signal Ss is being transmitted, or during the time between receipts of the first and second threshold signals Ss 1 , Ss 2 . 
     Those skilled in the art will obviously appreciate that a number of changes and variants may be made to the arrangements as described hereinbefore to meet specific needs, e.g. by changing the way in which the signal for opening and closing the movable diaphragm  44  is transmitted or received, as long as the relevant standard is met. 
     All of these variants and changes fall within scope of the invention, as defined in the following claims.

Technology Category: 3