Draught-enhancing device, in particular for chimneys, fireplaces and the like

Abstract: A draught-enhancing device, in particular for chimneys, comprises a plurality of channel-shaped bodies (7) divided into groups so as to define a plurality of stratiform sectors (8a, 8b, 8c) disposed side by side between the rear wall (5) and front wall (6) of a hood (2), the channel-shaped bodies (7) of each sector (8a, 8b, 8c) having lengthwise sizes greater than those of the corresponding bodies of an adjacent sector closer to the rear wall (5).

Description: The present invention relates to a draught-enhancing device, in particular for chimneys, fireplaces and the like, comprising the features set forth in the preamble of claim 1. While described with particular reference to chimneys and fireplaces, the innovatory concepts proposed by the present invention can be validly used also in connection with kitchen hoods for example, and under any situation in which one wishes to improve the natural draught effect. It is known that draught, that is the natural capacity of conveying and drawing fumes into a chimney flue, is not always sufficient, above all if a great distance exists between the hearth and the hood, to prevent fumes from flowing back towards the room where chimneys are located, mainly when foods tending to produce smoke in excess are being barbecued. Sometimes an unsatisfactory draught in a fireplace is to be ascribed to an imperfect planning and/or construction of the latter. Draught can be also inappropriate under some situations such as those due to particular weather conditions or operating temperatures not corresponding to the foreseen temperatures, which often occurs at the initial lighting step, when the flue has not yet been sufficiently heated. In order to overcome the above drawbacks, a fume-exhausting apparatus has been disclosed by the same Applicant in a European Patent Application EP-A-0620405. Said apparatus comprises a plurality of fume-conveying channels having lower openings directed downwardly close to the lower inlet mouth of the hood and upper openings directed upwardly and communicating with the lower end of the flue. This apparatus enables the natural draught of a chimney or the like to be increased to an important degree without resorting to the use of fans or similar power-driven devices, so that under any circumstances any smoke emissions into the room where the chimney or fireplace is located can be avoided. The technical task underlying the present invention is to provide a draught-enhancing device that, as compared with the above described known apparatus, is capable of further improving fume-exhaust in chimneys and fireplaces, even during the lighting step and in the presence of unfavourable weather conditions or when a great amount of smoke is being produced. The above technical task is substantially achieved by a draught-enhancing device in particular for chimneys and fireplaces, characterized in that it comprises the features set forth in the characterizing part of claim 1. The description of a preferred embodiment of a draught-enhancing device is now given by way of non-limiting example, with reference to the accompanying drawings, in which: Fig. 1 is an elevational front view of the device of the invention; Fig. 2 is a side view of the device; fig. 3 is a plan view of the device, with a sectional view of the hood taken along line III-III in Fig. 1. Referring to the drawings, the draught-enhancing device according to the invention is generally identified by reference numeral 1. It is to be applied to the inside of a hood 2 of a chimney or fireplace located between a hearth 3 and a flue 4. More particularly, the device 1 occupies the space included between a rear hood wall 5 and a front hood wall 6 and is comprised of a plurality of channel-shaped bodies 7, that is provided with tubular cavities having lower openings 7a directed downwardly close to the lower inlet mouth of the hood 2 and upper openings 7b directed upwardly and communicating with the flue 4. In an original manner, the channel-shaped bodies 7 are divided into groups and such arranged as to define a plurality of stratiform sectors 8a, 8b, 8c adapted altogether to form the device 1 itself. Sectors 8a, 8b, 8c of the draught-enhancing device 1 have surfaces of mutual separation which are substantially parallel to the rear wall 5, and extend one after the other in side by side relation between the rear wall and the front wall 6. Practically the stratiform sectors 8a, 8b, 8c divide the hood volume into elongate regions extending longitudinally between the hearth 3 and flue 4 and substantially flattened parallelly to the rear wall 5. By way of example, in the accompanying drawings provision is made for three sectors identified as first sector 8a, second sector 8b and third sector 8c respectively, moving away from the rear wall 5. Sectors 8a, 8b and 8c each comprise one central channel-shaped body, denoted by 9a, 9b and 9c respectively and defining a conveying channel adapted to transfer fumes from the hearth 3 to the flue 4 and two side channel-shaped bodies, denoted by 10a, 10b and 10c respectively and defining air-recovery pipes disposed in pairs at the outside of the corresponding conveying channel 9a, 9b, 9c. Each pair of air-recovery pipes 10a, 10b, 10c is adapted to transfer cold air, or in any case air at a lower temperature than that present over the hearth 3, from the flue 4 to the lower inlet mouth of the hood 2. The channel-shaped bodies 7 of the different sectors 8a, 8b, 8c have differentiated lengths, that is they extend differently in a substantially vertical direction, and more particularly they are increasingly longer as they move away from the rear wall 5. In this manner, each pair of air-recovery pipes 10a, 10b, 10c has its upper openings located at a higher position than the adjacent pair closer to the rear wall 5. Likewise, each upper opening of the conveying channels 9a, 9b, 9c in the different sectors 8a, 8b, 8c opens at a higher position than the opening of the adjacent conveying channel closer to the rear wall 5. In addition, in each sector 8a, 8b, 8c the air-recovery pipes 10a, 10b, 10c have the respective upper openings 7b located at a higher position than the upper opening 7b of the conveying channel 9a, 9b, 9c included therebetween. Practically, the upper opening 7b of the first conveying channel 9a is disposed at a lower position than the upper opening 7b of the second conveying channel 9b and the last-mentioned opening, in turn, is located at a lower position than the opening 7b of the third conveying channel 9c. In the same manner, the upper openings 7b of the first pair of air-recovery pipes 10a are disposed at a lower position than those of the second pair of air-recovery pipes 10b which, in turn, are located below the openings of the third pair 10c. Preferably, also the lower openings 7a of the channel-shaped bodies 7 of the different sectors 8a, 8b, 8c are slightly offset in an upward direction, moving away from the rear wall 5. In other words, the openings 7a that are closer to the front wall 6 are spaced apart a greater distance from the hearth 3. The conveying channels 9a, 9b, 9c each have a shape practically defining a flattened hollow space substantially parallel to the rear wall 5, and the air-recovery pipes 10a, 10b, 10c in each sector 8a, 8b, 8c have transverse sizes in section that substantially correspond to the thickness of the respective hollow space. The plan extension (that is in a horizontal plane) of the third conveying channel 9c, that is the channel which is the closest to the front wall 6, is smaller, at least in a direction parallel to the rear wall 5, than the extension of the corresponding conveying channels in the sectors that are closer to said rear wall. Since the third air-recovery pipes 10c are located immediately at the outside of the third conveying channel 9c, hence it follows that said third pipes 10c have a distance from each other which is smaller than that of the recovery pipes in the other sectors. Due to the fact that, as well known, temperature in the hood increases on moving from the front wall 6 to the rear wall 5, in order to restrain the heat flow from the sectors that are closer to the rear wall 5 towards the sectors closer to the front wall 6, the surfaces of mutual separation between the sectors 8a, 8b, 8c are provided to be defined by shields 11 made of highly heat-insulating material. In this manner, the air streams from the flue 4 substantially maintain their temperature in the outermost recovery pipes 10b, 10c, in the same manner as the fumes in the conveying channels closer to the rear wall 5 transfer heat to a reduced amount to the fumes in the conveying channels closer to the front wall 6. Preferably, at least one of the conveying channels 9a, 9b, 9c has at least one partition 12 adapted to divide the channel itself into conveying portions disposed side by side and adapted to avoid the occurence of swirling motions in the fumes. Finally, below the lower openings 7a of the channel-shaped bodies 7 a grid 13 is provided which consists of a series of horizontal strip-like elements 14, extending parallely to the rear wall 5 and having each an inclined orientation ascending towards the front wall 6. These strip-like elements 14 can be pivoted at the end on a perimetric bearing framework 15, and interconnected by at least one adjustment rod 16 to be operated manually or by powered means in order to adjust the inclination of said strip-like elements and therefore modify the width of the clearance defined between said elements and enabling passage of the fumes, from a maximum value substantially corresponding to the plan extension of the lower inlet mouth of the hood 2, to a zero value at which the strip-like elements fit together following each other along the respective side edges. By this solution the conventional flue-closing shutter usually provided in traditional chimneys is eliminated. Operation of a draught-enhancing device described above mainly as regards structure is as follows. Practically a double circulation is created between the inlet mouth of the hood 2 and the flue 4, that is an ascending circulation or flow of hot fumes in the central portion through the conveying channels 9a, 9b, 9c and a descending circulation or flow of cold or relatively cold air in the side regions through the air-recovery pipes 10a, 10b, 10c. This double circulation also takes place during the initial lighting step of the chimney because, contrary to the operating principles of traditional chimneys in which the maximum draught is achieved when the flue has reached the provided operative temperature, the device according to the invention obtains an excellent efficiency exactly by utilizing the cold (or at all events cooler) air present in the outermost band of the flue itself. The differentiated heights, in the different sectors 8a, 8b, 8c, of the upper openings 7b and lower openings 7a both of the fume-conveying channels 9a, 9b, 9c and air-recovery pipes 10a, 10b, 10c are useful not only for the purpose of not hindering the respective fume and air flows but also for promoting them. The heat-insulating shields 11 enable the colder air present in the front portion of the hood 2 not to be heated by the higher temperatures of the fumes and air in the regions closer to the rear wall 5. The different stratiform sectors 8a, 8b, 8c of the device therefore allow the creation of an equal number of fume and air flows disposed side by side and maintained as much as possible to their different temperatures. Due to the lower position of the inferior openings 7a closer to the rear wall 5 and the greater sizes of the corresponding air-recovery pipes 10a, 10b, a greater amount of oxygen is allowed to flow exactly to the regions where it is more needed. Positioning of the third air-recovery pipes 10c (that is the pipes closer to the front wall 6) slightly spaced apart from the flue walls has also proved to promote a greater flow of cool air downwardly. Practically, the air-recovery pipes 10a, 10b, 10c enable cold air flows to be drawn from the flue 4 and to be sent to the hearth 3 at a flow rate sufficient to make the air intakes usually present at the lower part of the hearth unnecessary: the effect achieved by said pipes corresponds to a downward flue extension for carrying air and therefore oxygen to the place where it is necessary for combustion. The adjustable grid 13 is useful to improve the central draught and also to avoid the escape of fumes by creating an obstacle to possible refluxes of same. In addition when the chimney is unlighted said grid can be used as an end closure for the flue so as to stop the cold air that may come down therefrom.

Claims: A draught-enhancing device, in particular for chimneys, fireplaces and the like, comprising a hood (2) disposed above a hearth (3) and below a flue (4) and having a rear wall (5) and a front wall (6) as well as a plurality of channel-shaped bodies (7) provided with lower openings (7a) directed downwardly close to the lower inlet mouth of said hood (2) and upper openings (7b) directed upwardly and communicating with said flue (4), characterized in that said channel-shaped bodies (7) are divided into groups and such arranged as to define a plurality of stratiform sectors (8a, 8b, 8c), said sectors having surfaces of mutual separation which are susbstantially parallel to said rear wall (5) and extend one after the other in side by side relation between said rear wall (5) and front wall (6) of the hood (2), and in that the channel-shaped bodies (7) of each of said sectors (8a, 8b, 8c) have sizes in the lengthwise direction between the respective lower (7a) and upper (7b) openings greater than the lengthwise sizes of the corresponding channel-shaped bodies (7) of the adjacent sector (8a, 8b, 8c) closer to said rear wall (5). A device according to claim 1, characterized in that each of said sectors (8a, 8b, 8c) comprises at least one central channel-shaped body defining a conveying channel (9a, 9b, 9c) adapted to transfer the fumes from the hearth (3) to the flue (4) and at least two side channel-shaped bodies (10a, 10b, 10c) defining air-recovery pipes located at the outside of said central channel-shaped body and adapted to transfer cold air from said flue (4) to said lower inlet mouth of the hood (2). A device according to claim 1, characterized in that in each of said sectors (8a, 8b, 8c) the respective air-recovery pipes (10a, 10b, 10c) have said upper openings (7b) located at a higher position that the upper opening (7b) of the respective conveying channel (9a, 9b, 9c). A device according to claim 2, characterized in that said conveying channel (9a, 9b, 9c) has a shape defining a flattened hollow space substantially parallel to said rear wall (5) and in that said air-recovery pipes (10a, 10b, 10c) have transverse sizes substantially corresponding in section to the thickness of said hollow space. A device according to claim 1, characterized in that said surfaces separating said sectors are embodied by shields (11) made of a highly heat-insulating material. A device according to claim 1, characterized in that said lower openings (7a) of the channel-shaped bodies (7) of each said sector (8a, 8b, 8c) are disposed at a higher location than the corresponding lower openings (7b) of the adjacent sector (8a, 8b, 8c) closer to said rear wall (5). A device according to claim 2, characterized in that the conveying channel (9c) of the sector (8c) closer to said front wall (6) has an extension in a horizontal plane and at least parallelly to said rear wall (5), lower than the corresponding extension of the conveying channels (9a, 9b) of the other sectors (8a, 8b) and in that the respective air-recovery pipes (10c) of said sector (8c) closer to the front wall (6) have a mutual distance lower than that of the air-recovery pipes (10a, 10b) of the other sectors (8a, 8b). A device according to claim 2, characterized in that inside at least one of said conveying channels (9a, 9b) provision is made for at least one partition (12) adapted to divide the channel into conveying portions disposed in side by side relation. A device according to claim 1, characterized in that a grid (13) is provided below the lower openings (7a) of said channel-shaped bodies (7), which grid comprises strip-like elements (14) extending horizontally and parallelly to said rear wall (5), arranged consecutively in side by side relation away from said rear wall and each having an inclined orientation ascending towards the front wall (6). A device according to claim 9, characterized in that said strip-like elements (14) are pivoted at their end on a perimetric framework (15) and interconnected by at least one adjustment rod (16) to be operated for modifying the orientation of said strip-like elements (14).

Inventors: DELLA ROCCA GIANFRANCO, DELLA ROCCA GIANLUCA, DELLA ROCCA, GIANFRANCO, DELLA ROCCA, GIANLUCA
Applicants: DELLA ROCCA GIANFRANCO, DELLA ROCCA GIANLUCA, DELLA ROCCA, GIANFRANCO, DELLA ROCCA, GIANLUCA
Application year: 1995
Main classification: F24B1
IPC codes: F24B1