SUCTION DEVICE

Abstract: A device in casings (1) for sucking air containing impurities away from a region, under and near the casing, comprises a casing downwardly open, at least a suction opening (6) arranged inside the casing and connected to a suction member for generating an air flow from below, into the casing and out through the suction opening for conducting air away from the device, means (10-18, 28) for conducting a part of the air sucked from the interior of the casing back to the region of a lower edge of a side wall of the casing and members (23, 32', 34) for directing this air as a stream from a side edge towards the interior of the casing, so that secondary air flows into the casing are induced at its edge region. Said means comprises at least a second suction opening (10) separately arranged with respect to the first suction opening (6) for sucking in the air for said stream, all air sucked through the first suction opening being conducted away from the device. The second suction opening (10) is arranged closer to that side wall (4) of the casing which at the bottom is terminated by said edge than the first suction opening (6). The second suction opening (10) is arranged at a substantial height inside the casing, at least in the upper half of the casing.

Description: Suction device TECHNICAL FIELD OF THE INVENTION AND PRIOR ART The present invention relates to a device in casings fo sucking air containing impurities away from a region, such as working place, for example at a kitchen grate, under or nea the casing, said device comprising a casing downwardly open, a least a suction opening connected to a suction member fo generating an air flow from below, into the casing and ou through the suction opening for conducting air away from th device, means for conducting a part of the air sucked from th interior of the casing back to the region of a lower edge of side wall of the casing and members for directing this air as stream from said edge towards the interior of the casing, s that secondary air flows into the casing are induced at it edge region. In the following such devices will be discussed in connectio with cooking, i.e. so called kitchen grate casings, but it i emphasized that such devices as well as the device according t the invention are useful at every type of working place and th like, where the air contains particles which are unhealthy o irritating to inhale. The object of devices of this kind is to remove as great a par of the impurities as possible in sucking such a small total ai quantity as possible away from the region under the device. I particular, it is desired to suck air containing impurities away from the region beside the casing and in the edge regions of the casing without utilizing any enormous suction powers, which give rise to disagreeable draught, noise or removing of a great amount of clean and heated air, which would be very expensive. Through the Swedish patent application 8601636-7 a kitchen grate casing is already known, in which outdoor air is con¬ ducted to the region of the lower edge of one of the side walls of the casing and is blown in a stream upwardly/inwardly in the casing towards a main suction opening, through which conta¬ minated air is sucked into the casing and removed through an exhaust air system. The air stream draws through the so called ejector effect air containing impurities into the casing in the edge regions of the casing, by which no high suction power is required for sucking such air into the casing. However, the cold air in said air stream may give rise to so called cold fall phenomena inside the casing, and the total amount of air which has to be sucked away gets larger than if it were possible to recirculate a part of the air sucked and use this to form the air stream for the ejector effect. Devices being successful in this respect are known through US patent 4 050 367 and GB 2 169 697 A. The efficiency of these known devices is good, but could be further improved. SUMMARY OF THE INVENTION The object of the present invention is to improve a device of the type mentioned in the introduction, so that the quotient amount of impurities divided by the total amount of air sucked away will be even higher than in the devices of the kind already known. According to the invention this object is obtained by a devic which is provided with the characteristics defined in th characterizing part of the appended claim 1. Thanks to the separate suction opening for producing the ai stream at the lower edge of the side wall and the high positio of this opening closer to the side wall than to the first mai suction opening, it it possible to raise the air flows insid the casing, by which additional air may be drawn into th casing. Additional advantages and characteristics appear from th detailed description of the embodiments of the invention a well as the appended claims, in which claim 5 defines a parti cularly advantageous embodiment, which realize the productio of rotating secondary air flows inside the casing, whic effectively retain contamination particles within the casing. BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a spe cific description of three preferred embodiments according t the invention cited as examples. In the drawings: Fig 1 is a schematic cross section view of a first embodimen of the device according to the invention. Fig 2 is a view corresponding to Fig 1 of a second embodimen of the invention. Fig 3 is a perspective view of an insert used in the devic according to Fig 2, in which some portions are broken away fo illustrating the construction of the insert, and Fig 4 is a view corresponding to the views according to Figs and 2 of a third preferred embodiment of the device accordin to the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION The device according to the invention shown in the figures wil here be called kitchen grate casing, which is not to be under¬ stood as limitative. The parts common to the different embodi ments have been provided with the same reference numerals. The kitchen grate casing shown in Fig 1 comprises a substan¬ tially box-shaped casing 1 downwardly open. The kitchen grate casing has mirror image symmetry with a vertical mirror image symmetry plane extending in the longitudinal direction of the casing 1, i.e. perpendicularly to the drawing plane. A V-shaped filter house 2 projects downwardly from the upper limitation of the casing and towards the casing opening 3 in the middle of the casing. The filter house 2 is elongated and extends paral¬ lel to the side walls 4 of the casing over substantially the entire length of the casing. The filter house 2 is provided with first suction openings 6 covered by filters 5 absorbing smell and other impurities. The filters 5 are disc-like and constituted by conventional filter elements adapted for the particular task. At the top the filter house is terminated by an evacuating opening 8 covered by a filter 7 to an exhaust air conduit 9 connected to a suction member, for example the main fan of the main ventilation system of the premises or the building in question. A second suction opening 10 is arranged in the upper limitation wall of the casing on each side of the V-shaped filter house 2. This suction opening is also covered by a filter 11 of the type similar to the type of the filters 5 and 7 and it is directed substantially vertically downwardly towards the opening of the casing. The second suction opening 10 is connected to a second suction member in the form of a fan 12 through an intake 13 The outlet 14 of the fan emerges into a distributing chamber 1 extending over substantially the entire length of the side wal 4. The distribution chamber has three elongated limitatio walls, two of which are the side wall 4 of the casing and th upper limitation wall thereof and these are interconnected b means of an inclined wall 16. The inclined wall 16 is provide with a succession of openings 17 extending over substantiall the whole length of the wall, a section according to Fig being carried out through such an opening. A directing plate 1 is arranged on the inclined wall 16 outside the distributio chamber so as to divert and direct air coming out of th openings 17, so that it gives rise to air flows substantiall being a tangent to the outside of the inclined wall 16. The function of the kitchen grate casing just described is th following: a negative pressure will be created in the filte house 2 by the suction member connected to the exhaust ai conduit 9 and a primary air flow from below and into the casin towards the first suction openings 6 will be produced. This ai flow is indicated by several arrows 19. By means of the suckin action of each fan 12 a part of the air flowing towards th suction opening 9 will divert towards the second suctio opening 10 (see arrow 20). The main part of this air passe through the filter 11, in which the greatest part of it impurities is caught, whereupon this air is recirculated to th casing through the distribution chamber 15. Thanks to the widt of the distribution chamber the comparatively concentrated ai flow emanating from the fan 12 will be distributed substan tially uniformly over the entire length of the chamber an flowing out of the openings 17 in the direction indicated b the arrow 21. Thus, in practice an air stream with the sam width as the length of the side wall 4 is formed, but it has comparatively small dimension in the direction perpendicula thereto. Owing to the fact that air flowing along a wall has tendency to be attracted by the wall and follow this, an ai stream along the side wall 4 downwards towards the lower edge of the casing is created. At the lower edge of the casing a directing plate 23 extending over substantially the entirety of this edge is so arranged that it diverts said air stream substantially in the direction towards the first suction opening 6 (arrows 24). The air stream from the lower edge 22 of the side wall 4 in the direction upwardly/inwardly towards the interior of the casing obtained through this arrangement will induce secondary air flows from the outside of the casing in the edge regions thereof and into the casing towards a first suction opening 6. The fact that an air stream draws surroun¬ ding air into secondary air flows is usually called the ejector effect. The arrows 25 indicates air flows into the casing produced by said ejector effect. Thanks to this it will be possible to suck air containing impurities and located in these regions into the casing without the necessity of creating a disproportionately low negative pressure in the filter house 2, with removing of enormous amounts of clean air. Another advantage of this kitchen grate casing consists in that a part of the air diverted towards the suction opening 10 through the ejector effect of the air flowing out of the openings 17 will be additionally diverted (arrow 26) and drawn into and follow the air stream downwardly towards the edge 22. In this way additional air quantities will be joining the air stream (for example arrow 27) and a rotating air movement will be produced in the room of the casing between the edge 22, the opening 10 and the walls 16 and 4. These rotating air flows or streams are very advantageous, since they retain particles contained in the air inside the casing and also raise the air flows inside the casing in an effective way. Furthermore, they prevent effectively parts of the air stream flowing downwardly towards the edge 22 from disappearing out through the opening 3 of the casing. A second advantageous embodiment of the device according t the invention is shown in Fig 2. In this embodiment the part 10-18 of the kitchen grate casing according to Fig 1 have bee replaced by an insert 28 manufactured in advance, which i shown more in detail in Fig 3. The insert is designed to b introduced into kitchen grate casings already existing and b retained by means of suitable retaining members, in order to b easily removed when this is desired, for example for cleanin purposes. Such an insert may be arranged in either the positio according to Fig 2 or the one according to Fig 4. The inser has a second suction opening 10 covered by a flat filter 11 This suction opening is connected to a fan 12, which blows ou air sucked in through the opening 9 into a distribution chambe 29. The distribution chamber 29 is divided into two halves by finely perforated plate 30, through which the air from the fa 12 has to pass in order to reach the openings 31 in one end o the chamber towards the interior of the casing. The perforate plate 30 contributes additionally to a uniform distribution o the air stream reaching the openings 31 over all of the ope nings. It appears from Fig 3 what the openings look like an how they are arranged, said filter 11 being omitted in thi figure. In the device according to Fig 2 an elongated directin plate 32 is so arranged in the proximity of the openings 31 that the air stream coming out of the insert is directe downwardly along the side wall of the casing and an air strea as well as rotating air movements similar to the ones in th device according to Fig 1 are created. The directing plate 3 is advantageously adjustable for adjustment of the direction o the air stream. A further advantage of the rotating air flows and the ai stream moving along the side wall 4 consists in the fact that if the side wall is made of a material with a high therma conductivity, a great part of the heat content of the air ma be led away to the room outside the casing, so that the ai carried away through the exhaust air conduit 9 has a slightly lower temperature than the rest of the air of the room. It is shown in Fig 4 how an insert according to Fig 3 manu¬ factured in advance has been arranged in a kitchen grate casing with the suction opening 10 substantially horizontally directed and the openings 31 located in the vicinity of the lower edge 22 of the side wall 4. This insert is provided with a directing plate 32 ' according to Fig 3, which is adjustable (the screw 33) and so directed that it together with a directing member 34 replacing the directing plate 23 directs the air stream from the openings upwardly/inwardly substantially towards the first suction opening 6. The insert 28 in Fig 4 is preferably kept in place by resting on a lower edge portion 35 of the casing and upper guiding members not shown projects downwardly from the top of the casing and retain the insert in lateral direc¬ tion, so that the latter after removing a short wall of the casing may be pushed into the same along the side wall 4 or through the opening 3. In the device according to Fig 4 the air flows inside the casing are directed more upwardly thanks to the high location of the second suction opening 10. The invention is of course not restricted to the preferred embodiments described above, but a plurality of possibilities to modify it should be apparent to a man skilled in the art, without departing from the basic idea of the invention. The -embodiments described above relate to casings intended to be located in a room with both side walls 4 out in the room, but in the case that the casing is to be placed close to or against a wall the device only consists of a half of the devices shown. It will then be cut off in the mirror image symmetry plane, where a wall for application on the room wall in question is arranged. Preferably, this wall will then limit the filter house from which the exhaust air conduit emanates. The first suction member may be constituted by the main fan o the ventilation system of the building, but a separate fan ma just as well be arranged for this task. In the case that the casing would have an important longitu dinal extension several second suction openings may be arrange one after the other along the extension of the casing an through separate fans lead air to a common distribution cham ber. The openings 17 and 31, respectively, could be one singl continuous elongated slit, even though a plurality of hole would be advisable from the stability point of view. The filters being a part of the device are of course adapted t their purposes, so they could for example have surfaces actin as catalyzers in a reaction in which a toxic compound of th air is converted to a harmless compound. The casing 1 could also be circular, so that the opening 3 wil be circular, but all other shapes of the casing desired are o course possible.

Claims: Claims 1. A device in casings (1) for sucking air containing impuri¬ ties away from a region, such as a working place, for example at a kitchen grate, under and near the casing, said device comprising a casing downwardly open, at least a suction opening (6) arranged inside the casing and connected to a suction member for generating an air flow from below, into the casing and out through the suction opening for conducting air away from the device, means (10-18, 28) for conducting a part of the air sucked from the interior of the casing back to the region of a lower edge of a side wall of the casing and members (23, 32', 34) for directing this air as a stream from said edge towards the interior of the casing, so that secondary air flows into the casing are induced at its edge region, c h a r a c t e r i z e d in that said means comprises at least a second suction opening (10) separately arranged with respect to the first suction opening (6) for sucking in the air for said stream, all air sucked through the first suction opening being conducted away from the device, that the second suction opening (10) is arranged closer to that side wall (4) of the casing which at the bottom is terminated by said edge than the first suction opening (6) , and that the second suction opening is arranged at a substantial height inside the casing, at least in the upper half of the casing. 2. A device according to claim 1, c h a r a c t e r i z e d in that a second suction member (12) is connected to the second suction opening (10), and that the compression side of this suction member is connected to a member (13-15, 29) conducting the air to and emerging in the interior of the casing in the immediate vicinity of that side wall (4) of the casing, from the lower edge (22) of which said air stream emanates. 3. A device according to claim 1 or 2, c h a r a c t e ¬ r i z e d in that an element (2) extending substantially parallel to the longitudinal direction of the side wall (4) projects downwardly from the upper limitation of the casing a a distance from said side wall, that this element has a surfac being inclined with respect to the vertical line and the middl normal of which is directed substantially towards the lowe edge (22) of the side wall, and that the first suction openin (6) extends on said surface over substantially the whole lengt of the element. 4. A device according to claim 2 or claim 2 and 3, c h a r a c t e r i z e d in that a chamber (15, 29) extendin along the long side of said side wall, i.e. in the horizonta direction, inside the casing between the second suction membe (12) and the discharging of the conducting member is arrange to distribute the air from the suction member (12) substan tially uniformly on one or several openings (17, 31) toward the interior of the casing extending together over substan tially the whole extension of the chamber, and that sai directing member comprises directing members (23, 32*', 34) extending along said lower edge of the side wall, which ar designed to direct the air arriving from the chamber in wardly-upwardly in the casing, preferably in the directio towards the first suction opening (6), so that an air stream i produced, which is substantially uniformly distributed alon said side wall edge (22). 5. A device according to claim 4, c h a r a c t e r i z e d i that the chamber (15, 29) is located in the upper half of th casing, and that the openings (17, 31) are directed so as t produce an air stream, which is substantially continuous in th horizontal direction along the side wall (4), said air strea being directed from the upper portion of the wall and down wardly along the wall towards said lower edge (22). 6. A device according to claim 5, c h a r a c t e r i z e d i that the openings (17) are arranged at a distance from the sid wall (4) and directed outwardly-downwardly towards the wall. 7. A device according to claim 6, c h a r a c t e r i z e d in that the second suction opening (10) is located at the upper limitation of the casing and directed substantially vertically downwardly in the casing. 8. A device according to claim 4, c h a r a c t e r i z e d in that the second suction opening (10) is directed substantially horizontally and substantially perpendicularly to the longi¬ tudinal direction of said side wall, that the chamber (29) in the vertical direction extends downwardly to the vicinity of the lower edge of the side wall, and that the openings (39) are located close to this lower edge and directed inwardly-upwardly towards the interior of the casing, preferably towards the first suction opening (6). 9. A device according to claim 4 and possibly any of the claims 5 to 8, c h a r a c t e r i z e d in that at least the second suction opening (10), the second suction member (12) and the distribution chamber are parts of an elongated insert (28), manufactured in advance, which may be inserted into the casing (1) and removed therefrom without moving the casing from said working place, and that the device has retaining means for retaining the insert along the upper limitation wall of the casing or alternatively the side wall thereof. 10. A device according to any of the preceding claims, c h a r a c t e r i z e d in that the casing (1) has two side walls (4), the longitudinal directions of which are substan¬ tially parallel to each other and both are located in a room over and in the proximity of a working place, that the device has a mirror image symmetry with a symmetry plane which is vertical and parallel to the longitudinal directions of the side walls, and that the symmetry plane traverses a room (2) located behind the two first suction openings (6) , is common to these and connected to one single first suction member, while he other parts of the device occur in double sets.

Inventors: AESTROEM TONNY, AESTROEM, TONNY
Applicants: HEDESUNDA PLAST & METALL, PLAST OCH METALL I HEDESUNDA AB
Application year: 1989
Main classification: B08B15
IPC codes: A47J36, B08B15, F24C15