BÄCK, Per-Olov (Askims Sörgårdsväg 92, Askim, S-436 44, SE)
AVT INDUSTRITEKNIK AB. (Box 20, Alingsås, S-441 21, SE)
LARSSON GUSTING, Anders (Bergdahlsgatan 5, Borås, S-504 58, SE)
BÄCK, Per-Olov (Askims Sörgårdsväg 92, Askim, S-436 44, SE)
| CLAIMS Frame arrangement for fastening a plurality of filter units (5) arranged adjacent to each other within a rectangular outer frame (2) which defines an air- inlet opening (21), said filtering units (5) having substantially symmetrical pocket sides (50) and at least one opening (51) arranged to face the air- inlet opening (21), wherein neighboring filter units (5) within the outer frame (2) are joined along their respective outer adjacent edges characterized in that each pocket side (50) comprises at least one portion for gripping engagement (52) adjacent to the filter unit opening (51) and arranged to meet a gripping member (72). Frame arrangement according to claim 1 wherein the portion for gripping engagement (52) is a portion which is gas impermeable. Frame arrangement according to claim 1 wherein the portion for gripping engagement (52) is a portion which comprises hook-and-loop fasteners. Frame arrangement according to claim 1 wherein the portion for gripping engagement (52) is a portion which comprises an adhesive layer. Frame arrangement according to claim 2 wherein the gripping member (72) arranged to meet said portion for gripping engagement (52) is a vacuum suction member. Frame arrangement according to claim 1 or 3 wherein the gripping member (72) arranged to meet said portion for gripping engagement (52) comprises hook-and- loop fasteners. Frame arrangement according to claim 1 or 4 wherein the gripping member (72) arranged to meet said portion for gripping engagement (52) comprises an adhesive layer. Frame arrangement according to any of claims 1-7 wherein neighboring filter units are joined along their respective outer adjacent edges by means of a clamping element (3) characterized in that two respective end portions (32) of each clamping element (3) are positionally fixed to the outer frame (2). 9. Frame arrangement according to claim 8 wherein the clamping elements (3) are positionally fixed to the outer frame (2) by means of welding, preferably ultrasonic welding. 10. Frame arrangement according to claim 8 wherein the clamping elements (3) are positionally fixed to the outer frame (2) by means of mechanical fastening. 11. Frame arrangement according to any of claims 8-10 wherein the outer frame (2) comprises four side profiles (6) having identical cross sections, said side profiles (6) arranged to be connected to each other to form a rectangular outer frame (2), where each side profile (6) further comprises a vertical side wall (61) presenting flat surface arranged to meet a portion of said clamping elements (3). 12. Frame arrangement according to any of claims 8-11 wherein said side profiles (6) are substantially hollow and comprise two outer vertical side walls (60, 61), and at least one interior supporting wall (6) which extends between the vertical side walls (60, 61) of the profile (6) and defines at least two interior channels (63, 63') extending longitudinally through the profile (6). 13. Frame arrangement according to claim 12 wherein the interior supporting wall (62) is positioned so that said at least two interior channels (63, 63') are symmetrical. 14. Frame arrangement according to any of claims 8-13 wherein said clamping element (3) is a clamping strip (3) arranged to withhold the edges of said filter units (5). 15. Frame arrangement according to claim 14 wherein each clamping strip (3) has two ends where each respective end (31) comprises projecting flap members (32) forming a pair of shoulders arranged to meet the inner vertical side (61) of the side profiles (6) of the outer frame (2). 16. Frame arrangement according to claim 15 wherein the shoulders (32) of a clamping strip (3) are arranged to be positionally fixed to the inner vertical side (61) of the side profiles (6), preferably by means of welding, even more preferably by ultrasonic welding. 17. Frame arrangement according to any of claims 11-16 wherein the vertical side wall (61) of the respective side profiles (6) which is arranged to face the air- inlet opening (21) comprises a horizontally protruding longitudinal upper flange (64) intended to at least partly cover the end portion (31) of the clamping elements (3). 18. Frame arrangement according to any of claims 11-17 wherein said side profiles (6) are extruded. 19. Frame arrangement according to any of claims 11-18 wherein the side profiles (6) are connected to each other via corner elements (4) comprising two tongues (40) at an angle in relation to each other, arranged to be inserted into the interior channels (63, 63') of the side profiles (6) and be positionally fixed thereto, preferably by means of welding. 20. Frame arrangement according to claim 19 wherein said tongues (40) are projecting at an angle of 90° in relation to each other. 21. Frame arrangement according to claim 19 or 20 wherein each tongue (40) is bifurcated by a slot (41) which is dimensioned to match with the interior supporting wall (62) of the side profiles (6) so that upon introducing a tongue (40) into a meeting profile (6) the supporting wall (62) is introduced into the slot (41) and enclosed by the tongue (40). 22. Frame arrangement according to any of claims 11-21 wherein said side profiles (6), said corner elements (4) and said clamping elements (3) are made of plastic material. 23. Frame arrangement according to any of claims 11-22 wherein said side profiles (6) comprise a height (h) in the range between 15-35 mm, a width (w) in the range between 15-35 mm. 24. Frame arrangement according to any of claims 11-23 wherein said outer frame which side comprises a length (L) in the range between 0.1-1 m. 25. Method for assembling a frame arrangement comprising the following steps: a. providing a plurality of filter units (5) each unit comprising an opening (51), b. arranging the plurality of filter units (5) so that the filter unit openings (51) are positioned with the opening edges adjacent to each other, c. joining neighboring filter units (5) by attaching two adjacent opening edges by means of a clamping element (3), d. providing a rectangular outer frame (2) which encloses the plurality of filter units (5), and e. permanently fastening the respective end portions (32) of each clamping element (3) to the inner side (61) of the outer frame (2) in such a way that each clamping element (3) is positionally fixed thereto. 26. A method according to claim 25, wherein the filter units are filter pockets (5) according to anyone of claims 1-4, where said method comprises an additional step in between steps (a) and (b), wherein for each filter pocket (5) the two opposite pocket sides (50) are urged into opposite directions by means of a gripping member (72) thus opening the filter pocket prior to that it is positioned as described in step (b). 27. A method according to claim 26, wherein the filter units are filter pockets (5) according to claim 2, wherein opening of a filter pocket is automatic and the pocket sides are parted by means of applying a vacuum suction onto each of the respective sides thus opening the filter pocket. 28. A method according to anyone of claims 25-27, wherein in step (b) said filter units (5) are positioned by means of said gripping member (72). |
TECHNICAL FIELD
The present invention relates to a frame arrangement for fastening a plurality of filter units arranged adjacent to each other within a rectangular outer frame which defines an air-inlet opening.
BACKGROUND ART
Filter arrangements are well known air purification products and generally consist out of a plurality of filter units (e.g. filter pockets) conventionally containing media and media support assembled adjacent to each other inside a suitable media support, typically in the form of a rectangular rigid frame. The frame is mounted, e.g. within a vent hole or an air drum, with the bag openings facing the flow direction of the air so that dust and particles are captured by the walls of the filter media units and the air is thus purified.
A widely used type of filter arrangement comprises an outer metal frame enclosing a number of filter bags which in their turn are held by smaller inner metal frames supported by the outer frame. Today manufacturing of metal filter frames is a highly automatic production process, however the mounting of filter bags still requires manual handling, meaning to date no producer of metal frames has managed to fully automate manufacturing. The fact that the inner and outer metal frames are not integrated further leads to that it is meaningless to reinforce the outer frame, since when the filter bags accumulate dirt they will eventually sag regardless of the properties of the outer frame. On the other hand, connecting the inner and outer frames (e.g. by stapling, riveting) cannot be done without causing holes in the outer frame, inevitably resulting in air leakage.
Another drawback related to metal filter frame arrangements is that production of metal frames requires huge amounts of energy, and furthermore the optimal waste
management is different for metal compared to the filter media, for instance the metal must be disposed in a landfill which demands special transportation, whereas the filter media is suitable for combustion. This often leads to that instead of being properly taken care of, used filter arrangements are thrown away as a whole, which is of course disadvantageous from an recyclable point of view since separation of the metal frame from the filter media would be more desirable. In general there are several drawbacks in connection to manufacture of filter frame arrangements. Assembling the filter units, for example, is an uneconomical process since joining of several pockets by means of sewing, welding or pressing the outer edges of adjacent filter units/pockets is laborious and expensive, and since air-filter pockets are merely a throw-away article. The material which constitutes the filter media is also hard to handle and control due to its supple and pliant quality, and therefore needs to be manually positioned in order to avoid the risk of rupturing the filter pockets during assembly which would lead to air-leakage.
Because of the difficulties related to managing the filter media, today production of filter arrangements requires an undesired element of manual handling. Regarding metal frame filter arrangements, corresponding to the main product regarding volume, both transferring and opening the separate filter media pockets as well as rightfully position an inner metal frame inside a filter bag opening prior to assembly inside a support frame must be done by hand, which is of course time consuming and evidently demands an excess of personnel. Manual handling of filter bags thus constitutes a bottle-neck regarding manufacturing speed and prevents efficient balance of production capacity.
Moreover, the material for making the filter arrangements must be kept on hand by the manufacturer meaning that a great inventory of framing material is required. For instance, if producing metal frame arrangements space demanding casings for different frame sizes as well as various sizes of filter bags must be kept in stock, or if buying metal on a coil the corresponding costly metal handling equipment for manufacturing the frames is needed in- house. During the last decade manufacturers have developed frame arrangements of plastic material, which means worn out units are readily combustible as a whole.
There have been attempts to automate production of plastic filter frames in order to reduce production time, minimise stock and enable scale-up/down of production w/o up/downsized workforce, however due to the properties of plastic material it is not possible to use small inner frames or the like as in metal arrangements. Plastic is simply not resilient enough to hold the filter units open while mounting inside the outer frame the way metal can. Plastics manufacturers merely copying the metal solution is hereby inefficient. Therefore other types of frame arrangement designs have been developed; however it has proven difficult to automate manufacturing without ending up with a substandard product, i.e. with insufficient rigidity. Further, it is quite expensive to keep a flexible production line, which in some cases has lead to that frame suppliers have abandoned less common frame sizes. There have been attempts to make rigid outer frames of plastic, for instance by producing hollow plastic outer frame parts, but it has proven difficult to attach transversal holding structures holding the filter bags onto the outer frame since mechanical fastening as well as welding requires a support, which impossible to introduce into the hollow outer frame. Thus, the hollow outer frames have merely been used as holders for corner parts, connecting sides into a rectangular frame.
Evidently, the problems which relate to handling the filter units also relate to the production of plastic filter arrangements, e.g. juxtaposing the filter media units within the plastic frame needs to be done manually.
To our knowledge, so far no producer of filter frame arrangements (metal or plastic) including filter media has been able to present a fully automatic production line and at the same time keep up the required quality standard regarding the product. In fact current attempts to improve the production has either resulted in inefficient solutions leading to worse aerodynamic characteristics with lost quality standard, or even both inefficient assembly and reduced frame quality. For example, metal holding strips for holding the filter bags has been made by metal sheet bending in order to achieve stability, however this has lead to an impaired airflow. For the same reason the plastic frames has been injection molded with thick transversal support bars, which of course also disturbs passing air.
Hereinafter will be described two plastic frame arrangements pertaining to prior art.
In W09837945 is shown a plastic frame arrangement for fastening adjacent filter bags, where adjacent filter bags are coupled to each other by means of clamping strips which are inserted into an outer frame by means of sliding or snapping clamping strips onto the outer frame.
In such an arrangement clamping strips are attached e.g. with a snap-in device located at a predetermined position in the outer frame leading to that the tension of the clamping strips will differ from time to time depending on the thickness of the interposed filter media or choice of sliding resistance/snap-in force. In case of insufficient or different tension there is a risk of differently formed parallel clamping strips and thereby to air- leakage and concave/convex clamping strips if not reinforced by an extra gap-covering profile. A further obvious disadvantage related to said solution, as well as to numerous other filter frames, is that upon assembly of a filter arrangement a certain portion of the filter media will inevitably become covered by the edges of the outer frame, which diminishes the filtering area and thereby reduces the filtering efficiency.
The drawbacks of the snap-in principle in combination with risk for mistakes during manual handling of the filter units have lead to that many manufacturers add a layer of foam or adhesive along the outer frame in an attempt to avoid air-leakage, whereby is added another time consuming step to production. Another problem with plastic frames has been insufficient frame stability, and that plastic filter arrangements become weak and have insufficient torsional rigidity compared to metal frame arrangements. Also, regarding the particular design in
W09837945 there is a risk that the clamping strips are deformed and become concave/convex which results in different air pressure in different filter pockets which could lead to air pressure fall due to unbalanced pressure. This problem also comes with those frame arrangements which are making use of a snap-in mechanism for attaching the filter pocket holders, since snap-in solutions inevitably leads to insufficiently tightened holders and thereby risk of concave/convex filter pocket edges.
In an attempt to avoid distorted filter pocket cross sections the clamping elements in W09837945 have been given a sturdy and thick design. However, the thick clamping elements will disturb the passing stream of air, interfering with the flow direction and thus reduce the filtering capacity.
Another plastic frame arrangement is seen in US6451079, where an outer frame encloses a plurality of inner frames each arranged inside a free border of a filter pocket. This arrangement shortens assembly turnaround-time but leads to the same type of disadvantage as the one disclosed in W09837945, namely that the structures which belong to said inner frames will disturb the air flow through the filter pockets and result in an unfavourable air resistance.
Due to the foregoing it is obvious that there is a need for a more efficient manufacturing method as well as an improved frame arrangement, which would solve or minimise at least some of the above mentioned problems and disadvantages. DISCLOSURE OF THE INVENTION
It is a first object of the present invention to overcome or at least minimise the drawbacks and disadvantages of known processes for manufacturing filter frame arrangements, and providing the possibility of a fully automated production process for the making of filter frame arrangements.
The aforementioned objects of the invention are achieved according to one aspect by a frame arrangement for fastening a plurality of filter units arranged adjacent to each other within a rectangular outer frame which defines an air- inlet opening, each of said filtering units having opposite substantially symmetrical pocket sides and at least one opening arranged to face the air-inlet opening, wherein each pocket side comprises at least one portion for gripping engagement adjacent to, or a least close to, the edge which defines said opening of the filter pocket, said portion for gripping engagement being arranged to meet a gripping member.
It is understood that by "filter units" means filter bags/pockets which are made out of any type of conventional filter media as known per se, where each filter bag comprises substantially parallel and symmetrical pocket sides.
Thanks to the above mentioned frame arrangement according to the invention an automatic external gripping member may temporarily engage with said portion for gripping engagement on a filter unit and urge the two sides of the unit into different directions (preferably opposite directions) thereby parting the two sides of the filter unit thus exposing the opening of the corresponding filter unit. Said filter unit outline comprising a portion for gripping engagement is extremely advantageous when it comes to manufacturing procedure: thanks to the portion for gripping engagement a filter unit may be opened in an automatic manner by means of said gripping means. The pocket sides may thus be parted by applying the gripping member onto each of the respective sides and subsequently urging two opposite pocket sides into opposite directions thus opening the filter pocket prior to positioning for further assembly into a filter frame arrangement.
Evidently the filter pockets may also be held and transported/transferred by the same gripping member from a pile, sewing machine or pocket welding machine to a desired position for further assembly into a filter frame arrangement. Hereby is achieved a very effective way of improving the production of filtering units since previously manual opening of the filter pockets as well as transportation and positioning thereof may be replaced by a fully automated process. This saves both time and money since no need of personnel is required for assembly of filter frame arrangements. Thanks to the new inventive manufacturing procedure the time of production per unit may be reduced by 75-95%. According to one aspect of the invention the portion for gripping engagement is a portion which is gas impermeable, and said gripping member comprises vacuum suction. Said portion which is gas impermeable may comprise a gas impermeable layer such as plastic film, aluminium foil or any other gas impermeable material suitable for applying onto the surface of a filter unit. Preferably said gas impermeable layer is applied onto the surface of the filter unit which is arranged to meet said gripping member. The portion for gripping engagement may be attached to the pocket sides as part of manufacturing of filter bags in any conventional way, for instance a plastic film may be sewn, welded or riveted onto the surface of the filter units so that, once the filter unit is supposed to be assembled in a frame arrangement, it already comprises said portion for gripping engagement.
According to one aspect of the invention the portion for gripping engagement is a portion which is supplied with a hot-melt adhesive, for instance however not restricted to INSTAWELD 9609.
According to one aspect of the invention the portion for gripping engagement is a portion which comprises hook-and-loop fasteners, for instance Velcro®. Preferably the external gripping member comprises a meeting surface arranged to engage with hook- and-loop fasteners.
According to one aspect of the invention the portion for gripping engagement is a portion which comprises an adhesive layer such as for instance, but not limited to, a tape strip or glue.
According to one aspect of the invention the gripping member comprises needle members arranged to engage with the surface of a filter unit. As is also mentioned above, hereby is achieved a filter unit which may be readily handled in an automatic manner, no need of manual interception, which leads to substantial cost reduction as well as time savings and quality assurance. Thanks to the present invention a fully automatic manufacturing process is achieved which leads to that a fully assembled filter arrangement can be produced at substantially reduced turn- around time, at lower costs and with improving efficiency. Obviously said automatic opening of filter bags may be applied onto any present production process, metal or plastic. For instance, the to-date step of by hand inserting a metal inner frame into a manually opened filter bag may easily be replaced by the above described automatic opening of said filter bag followed by insertion of an inner frame, every form of manual interference being eliminated. It is another object of the present invention to provide an improved frame arrangement with the advantages of:
-having excellent robustness as well as torsional and flexural rigidity;
-providing minimised risk of air-leakage yet without usage of extra sealing and/or reinforcements; and
-providing a high quality air-purification with essentially even air-pressure fall over the filter bags.
These objects are achieved by a frame arrangement for fastening a plurality of filter units arranged adjacent to each other within a rectangular outer frame which outer frame defines an air- inlet opening, wherein neighboring filter units are joined along their respective outer adjacent edges by means of clamping elements wherein two respective end portions of each clamping element are positionally fixed to the outer frame.
Accordingly each clamping element is positioned transversally within the outer frame. It is understood that by "positionally fixed" means that the end portions of each transversely positioned clamping element are fastened onto the outer frame in such a way that they do not move/change coordinates in a longitudinal direction along the frame wall onto which the clamping elements are fixed.
The cooperation of the various embodiments incorporated into one filter frame arrangement will enable for a fully automatic production process of a surprisingly rigid and strong frame.
According to one aspect of the invention, upon attachment to the outer frame each filter unit will have a rectangular cross section at the air-inlet opening. During fastening of the clamping elements (where said clamping elements are withholding neighboring filter units) onto the outer supporting frame a certain tension may be applied onto the clamping elements so that they are arranged within the frame with a tightness, which is possible thanks to the rigidity of the outer frame, as will be later described in more detail. This leads to that the frame arrangement gets a great inherent stability where the risk of slack filter units is eliminated, and to that a relatively thin clamping element still may provide a firm holding function so that additional strengthening plastic components may be omitted and consequently disturbance of passing air is minimised. The clamping elements may be tailored to fit any type of outer frame since they are easily cut just-in-time in situ (i.e. in immediate connection to the production line). The fastening of the clamping elements onto the frame further leads to that a very precise positioning of the filter openings relative to the outer frame is possible meaning eliminated risk of concave/convex filter pockets.
A frame arrangement according to one or more of the aspects according to the invention will be flexurally and torsionally strong in three coordinate axes, the flexural strength resulting from the structures of the components constituting the frame as well as the connection of said components (as will be later described in more detail), with no risk that the clamping elements get out of position and result in air-leakage.
The outer frame according to the invention will have an extremely high bending stiffness resulting in that it is virtually indeflectable, and therefore the clamping elements will be immobile meaning concave/convex filter pockets is completely avoided.
According to one embodiment the frame arrangement is made of plastic based material, also including bio/organic plastics and the like, however a person skilled in the art will realize that any material is possible to use such as metal, wood, any suitable composite or for that matter a combination thereof. Thanks to the geometry and design (e.g. the permanent fixation of the clamping elements) of the frame arrangement according to the present invention it is possible to use other types of materials, such as for instance wood plastic composite (WPC). A plastic frame provides the advantage in that it can be disposed of and combusted as a whole.
According to one aspect of the invention the clamping elements are permanently and positionally fixed to the outer frame by means of welding, preferably ultrasonic welding into a hollow profile without external support. They may also be fixed to the outer frame by means of punch-and-tuck closure, also referred to as plunging, or with mechanical fasteners such as rivets or screws. All of said welding, plunging and mechanical fasteners will result in that the clamping elements are positionally fastened onto the frame in such a way that they cannot move sideways along the frame during normal use. According to another aspect of the invention the outer frame comprises four side profiles having identical cross sections, said side profiles arranged to be connected to each other to form a rectangular/square-shaped outer frame, the outside for instance measuring 592 x 592 mm. Each side profile is substantially hollow and presents a closed cross section with two vertical side walls, whereof the one vertical wall which upon assembly of a frame is arranged to face inwards against the air-inlet opening is also intended to meet an end portion of said clamping elements.
Further, each side profile preferably comprises at least one interior supporting wall extending horizontally between the vertical side walls of the profile and divides the inside of a profile into two interior longitudinal channels extending longitudinally through the profile. In one embodiment of the invention the interior wall is horizontally positioned in the middle of a side profile so that said two interior channels are symmetrical. This leads to advantages related to production due to that symmetric (plastic) profiles are easier to make than asymmetrical since asymmetrical parts may stiffen in an uneven way and the parts then have to be reheated in order to eliminate any arisen tensions in the material. Obviously, however, the interior wall may be positioned in any suitable way other than in the middle inside the side profiles without departing from the scope of the invention. The closed cross section of each profile together with the interior wall promote an extraordinary torsional stability and stiffness of the side profiles and therefore also of the final frame arrangement. Therefore deformation of the outer frame arrangement is avoided, risk of air leakage minimised as well as concave/convex clamping elements. A further great advantage is that the interior wall constitutes an integrated welding support leading to that welding through a clamping element as well as the filter media is enabled without any external support.
According to yet another aspect of the invention said clamping element is a foldable clamping strip arranged to withhold the edges of neighboring filter units by means of being folded over and enclosing two adjacent filter unit edges. Preferably each clamping strip is fixated onto said adjacent filter units, for instance by means of welding or stapling the clamping strip onto the filter unit edges which it encloses whereby is ensured an air-tight closure in between neighboring filter bags. This allows for a quick, and possibly automated, connection of a plurality of separate filter units into one pack, and eliminates the need of a prepared, pre-sewn or pre-welded accordion pack meaning savings both in terms of time and money. Also the described design will lead to that relatively thin clamping strips will still provide sufficient support and air may thus pass virtually without disturbance and air-pressure fall is minimised. The present invention leads to an assembly with extremely low pressure fall, surprisingly enough as much as 15-20% less pressure fall than the most common plastic frame construction (w/o media). The end-portions of each clamping strip is further fixated onto the outer frame resulting in a complete filter frame arrangement. Thanks to being mounted with a tension the clamping strips can be kept very thin which allows for a larger number of filter units per frame arrangement since they require less space compared to known clamping strips. Preferably the plurality of filter units in one frame corresponds to a number of at least 10, preferably at least 12 for a frame measuring 592 x 592 mm. The larger the number of filter units per frame, given the same outer measurement, the better the air purification capacity becomes.
According to yet another aspect of the invention each end portion of a clamping strip comprises projecting flap members forming a pair of shoulders arranged to meet a vertical side of the side profiles of the outer frame. Said shoulders of a clamping strip are arranged to be positionally fixed to the inner vertical side of the side profiles, for instance by means of welding, preferably ultrasonic welding. Thanks to the
aforementioned interior supporting walls a welding support is provided within each side profile of the frame so that welding of the clamping strips onto the vertical wall of the outer frame can be done easily and without any external support. The design of the clamping elements also results in substantially rectangular cross section of the filter bag openings, where virtually all filter media is exposed to passing air and used for air purification.
According to yet another aspect of the invention the vertical side wall of each of the respective side profiles arranged to face the air- inlet opening of the frame comprises a horizontally protruding longitudinal upper flange. The flange is intended to, upon assembly of a frame arrangement, at least partly cover the end portion of the clamping elements (in particular cover the projecting members which are fixed to the side profile) in order to shield off disturbance of/from air flow. The flange is also intended to vertically fix the clamping elements.
In one embodiment of the invention the upper flange protrudes a certain distance which distance corresponds at least to the thickness of a clamping strip. This means when the clamping strips are attached onto the outer frame the upper flange is arranged to protrude above the projecting members as they meet and get fixed onto the vertical side of a side profile. Such arrangement is advantageous since it leads to a firm seal between the filtering units and the outer frame and at the same time interference with the passing stream of air to be purified is minimised. Further the upper flange contributes to protect the connection between the clamping strip and the outer frame, for instance minimizing the risk of relaxation phenomena and/or loosening of the welding.
According to yet another aspect of the invention the side profiles are extruded or injection molded.
According to yet another aspect of the invention the side profiles are produced by means of metal sheet bending. According to yet another aspect of the invention the side profiles are connected to each other via corner elements. A corner element comprises two tongues, preferably but not necessarily at an angle of 90° in relation to each other, arranged to be inserted into the open ends of a side profile in such a way introduced into facing interior channels and be fixed thereto, preferably by means of welding, without need of external support. Thanks to the new design of corner elements a significantly improved torsional rigidity is achieved for the assembled frame arrangement. Being permanently fixed (for instance by welding) to the side profiles the corner elements provide the assembled frame with a great rigidity and stability. According to yet another aspect of the invention each tongue of the corner elements is bifurcated by a slot which is dimensioned to match with the interior supporting wall of the side profiles so that upon introducing a corner element into an open interior channel of a side profile, the interior wall is introduced into the slot and enclosed by the tongue. This particular design of the corner elements and their co-operation with the adjacent side profiles allows for a very easy connection to quickly form a completely integrated and very rigid outer frame. Once a corner element is introduced into a side profile it may be fastened thereto by welding or gluing, or by means of any mechanical fastening such as riveting, pop riveting, screwing or stapling. According to yet another aspect of the invention said side profiles, said corner elements and said clamping elements are made of plastic material.
According to yet another aspect of the invention said side profiles, said corner elements and said clamping elements are made of plastic, of metal, or of a composite material, or of a combination of said materials. According to yet another aspect of the invention said side profiles comprise a height in the range between approximately 20-25 mm, a width in the range between 20 - 25 mm and a length/depth in the range between 0.1-1 m. BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in more detail with reference to the enclosed figures, in which:
Fig. 1 A is a perspective view showing a filter arrangement according to an
example of the invention,
Fig. IB is a detail view according to encircled IB in fig. 1A,
Fig. 2A is a perspective view showing a detail of the frame arrangement according to an example of the invention,
Fig. 2B is a side view showing the detail of the frame arrangement according to
Fig. 2 A viewed from the inside out,
Fig. 2C is a detailed view according to encircled IIC in fig. 2A,
Fig. 3A-B show exploded views of a corner element and portions of the frame
profiles,
Fig. 4A is a perspective view illustrating a processing station for manufacture of a filter arrangement according to the invention, and
Fig. 4B is a detail view according to IVB in fig. 4A.
DETAILED DESCRIPTION OF THE INVENTION
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings. Further, the description, and the examples contained therein, are provided for the purpose of describing and illustrating certain embodiments of the invention only and are not intended to limit the scope of the invention in any way.
In figure 1 A is seen a perspective view, partly cut off, of a frame arrangement 1 according to an example of the invention comprising a plurality of filter units 5 arranged adjacent to each other within a rectangular outer frame 2 which defines an air- inlet opening 21, said filtering units 5 each having substantially symmetrical pocket sides 50 and an opening 51 arranged to face the air- inlet opening 21, wherein neighboring filter units 5 are joined along their respective outer adjacent edges. Each pocket side 50 comprises at least one portion for gripping engagement 52 substantially adjacent to the mouth of the filter unit opening 51.
Said portion gripping engagement 52 is shown in fig. 1 as a band located adjacent to the mouth of the opening 51 , however the portion 52 may be any other type of restricted or unrestricted area arranged for gripping engagement 52.
It is understood that by "gripping engagement" means any type of interaction with a pocket side 50 which results in a temporarily and reversible attachment, for instance picking a pocket 5 by vacuum lifting.
Herein each filter bag 5 is arranged with a plurality of integrated inner pockets 53 according to prior art, however it is obvious that any conventional type of filter bag/unit 5 may be used.
Neighboring filter units 5 are joined along their respective adjacent edges by means of a clamping element 3, preferably in the form of a clamping strip 3 having been folded over two adjacent filter unit 5 edges and fixated thereto so as to pinch together said filter units 5 resulting in a seal tight connection. Preferably, but not necessarily, a clamping strip 3 may be arranged to be fixated around two filter units 5 by means of welding, however other fastening methods are also possible such as mechanical fastening (stapling, riveting, screwing), pressing or gluing.
The side of the outer frame 2 preferably comprises a length L in the range between 0.1- 1 m.
Now referring to the zoomed detail view of fig. IB, the respective end portions 31 of each clamping element 3 are arranged to meet the outer frame 2 and be positionally fastened to the outer frame 2 via flap members 32. As will also be later described in more detail each clamping strip 3 is folded over the edges of two adjacent filter bags 5 withholding the same inside the frame 6. Each end portion 31 of each strip 3 comprises a slit dividing the strip 3 into a pair of flap members 32 which are folded in order to spread out the filter bag 5 and also to be fixated onto the outer frame 6.
As a result thereof also the filter units 5 which are held by the corresponding clamping element 3 are attached to the outer frame 2. This is achieved thanks to that said flap members 32 of respective clamping element 3 are arranged to press an upper portion of a corresponding filter unit 5 against the outer frame 2, meaning fastening of the clamping element 3 leads to fixation of the filter unit 5. Once the clamping elements 3 are fastened onto the outer frame 2 a very rigid filter frame arrangement 1 is achieved with air-tight assembly of filter units 5 and where each filter unit 5 is tightly stretched transversally within the outer frame 2, held by said corresponding clamping strips 3.
The clamping elements 3 may be fastened onto the outer frame 2 by means of welding or any mechanical fastening such as riveting, stapling or screwing that is: any fastening which leads to positional and permanent fastening of a clamping strip 3 onto the outer frame 2 so that no longitudinal moving of the clamping element 3 out of position is possible. This means the filter units 5 will not risk becoming concave/convex but will keep its original shape. Also, the clamping elements may be delivered on a coil and be cut to lengths just-in-time allowing for adapting the length to the specific frame arrangement 1. For instance if the filter units 5 are made out of a thick media shorter clamping elements 3 are needed since the filter units will require more space between the clamping element 3 and the outer frame 2.
The filter frame arrangement 1 seen in figs. 1 A-B may be made of plastic material, metal or a combination thereof. It is also possible to manufacture the frame parts from composite material.
The design of the outer frame 2 according to a preferred embodiment of the invention is now to be described, referring mainly to figures 2 - 3.
Figure 2A is a perspective view showing a partly cut off portion of an outer frame 2 and a plurality of clamping members 3, and Figure 2B is a side view of the portion shown in fig. 2A. Figure 2C is a close-up view of the encircled area IIC in figure 2A. For illustrating purposes no filter units 5 are shown in these figures.
An outer frame 2 according to the invention comprises four side profiles 6 like the ones at least partly shown in fig. 2A, said side profiles 6 having identical, closed cross sections, and arranged to be connected to each other to form a rectangular outer frame 2, where each side profile 6 further comprises a vertical side wall 61 presenting flat surface arranged to meet a portion 32 of a clamping element 3. In one embodiment of the arrangement 1 the clamping element 3 is said foldable clamping strip arranged to withhold the edges of neighboring filter units 5 by means of enclosing two adjacent filter unit edges. In Figures 2A-C are shown a preferred principle of how clamping strips 3 are arranged in relation to the side profiles 6 of the outer frame 2. Each end portion of each clamping strip 3 comprises projecting flap members 32 forming a pair of shoulders arranged to meet the inner vertical side 61 of the side profiles 6 of the outer frame 2. Said shoulders 32 are achieved by means of cutting a slit in each of the two respective end portions of each clamping strip 3. Said shoulders 32 are arranged to be positionally fixed to the inner vertical side 61 of the side profiles 6, preferably by means of welding, even more preferably by ultrasonic welding, however other alternative fastening methods are equally conceivable as has been previously mentioned.
Figure 2B is a side view of the portion shown in fig. 2A, and illustrates a plurality of clamping strips 3 being fastened to the outer frame 2 via their respective projecting flap members 32 which are arranged to abut the vertical side wall 61 thereby also fixating the filter unit 5 by pressing the same against the side profile 6. As is illustrated in 2A-C the outermost clamping strips 3' are withholding one filter unit 5 edge only, and furthermore, the entire length of the clamping strip 3 ' is arranged to be fastened onto the corresponding side profile 6 and sealed thereto. Unlike the clamping strips 3 located in the middle of the frame which are attached onto the outer frame 2 at their respective end portions only, the outermost ones 3 ' are attached both along their outer length and at the end portions 31 ' .
Figures 3A-B are exploded views of a detail of the outer frame 2, namely a corner element 4 according to one embodiment and end portions of two meeting side profiles 6 of the outer frame 2. The side profiles 6 are substantially hollow and comprise two outer vertical side walls 60, 61 and at least one interior horizontal supporting wall 62 which extends between the vertical side walls 60, 61 of the profile 6 and defines at least two interior channels 63, 63' extending longitudinally through the profile. According to a preferred embodiment the interior supporting wall 62 is positioned so that said at least two interior channels 63, 63' are symmetrical, however it is also possible to position the interior wall 62 in another way without departing from the scope of the claims. The interior supporting wall 62 provides excellent flexural and torsional rigidity to the side profiles 6 leading to a great inherent stability of the final assembled frame arrangement 1. Further, in the case of welding together the clamping elements 3 and the outer profile 6, the interior wall 62 provides a welding support.
In an assembled frame arrangement 1 two side profiles 6 are connected to each other via one of said corner elements 4. This is illustrated for instance in fig. 1 A and 2A.
A corner element 4 comprises two tongues 40 at an angle in relation to each other, preferably but not exclusively projecting at an angle of 90° in relation to each other. Said tongues 40 are arranged to be inserted into the interior channels 63, 63' of meeting side profiles 6. Each tongue 40 is bifurcated by a slot 41 which is dimensioned to match with the interior supporting wall 62 of the side profiles 6 so that upon introducing said tongue 40 into a meeting interior channel 63, 63' the supporting wall 62 is introduced into and enclosed by the slot 41. Once two side profiles 6 have been connected by a corner element 4 they are positionally fixed thereto, preferably by means of welding but possibly by means of any other suitable fastening method, e.g. screwing, riveting, pop riveting, gluing or stapling. In case of welding, preferably ultrasonic welding, the shape of the corner element 4 according to a preferred embodiment will constitute a welding support in addition to provide a great rigidity to the final product. Hence no external welding support is needed. Welding may be performed onto the side profiles 6 from the upper 65 and lower 66 horizontal walls thus fixating the respective corner element 4. A corner element 4 as illustrated in fig. 3A-B may be used together with corresponding side profiles 6 independent of how the rest of the filter arrangement 1 is designed. Obviously the corner elements 4 may be used for assembling any type of frame as long as the outer frame parts are substantially compatible with the corner elements 4, e.g. being hollow and having matching dimensions.
Said side profiles comprise a height h in the range between 15-35 mm, more preferred between 20-25 mm, and a width w in the range between 15-35 mm, more preferred between 20-25 mm.
The vertical side 61 of the respective side profiles 6 which is arranged to face the air- inlet opening 21 of the frame arrangement 1 comprises a horizontally protruding longitudinal upper flange 64 intended to cover the end portion 31 of the clamping elements 3 when assembled in a frame arrangement 1. Such a design will lead to a reliable sealed frame arrangement 1 with minimised low risk of air-leakage.
The filter frame arrangement 1 according to the present invention provides many manufacturing advantages compared to prior art. For instance the side profiles may be delivered in extruded lengths, meaning they may be easily stored until production, whereupon they may be cut just-in-time according to desired dimensions of the frame. Thanks to the corner elements 4 an easy and quick assembly of an outer frame 2 of any size is possible. The clamping elements 3 are also very easily handled and stored; since comprising merely a strip the material may be delivered on a coil and cut to lengths in close connection to assembly of the filter arrangement 1, which further contributes to efficient production. An example of how to assemble a filter frame arrangement 1 according to the invention is now to be described, referring mainly to figures 4A - B which show a part of a processing station 7 for fully automatic manufacture of a filter arrangement 1 according to the invention.
In figs. 4A - B are shown a part of two parallel production lines 71, 71 '.
A plurality of filter units 5 is provided, typically in a pile 54, each unit comprising substantially symmetrical sides 50 and an opening 51. Each pocket side 50 comprises at least one portion for gripping engagement 52 adjacent to the mouth of the filter unit opening 51 , said portion for gripping engagement 52 being arranged to meet a gripping member 72 (see fig. 4B).
By means of said gripping member 72 engaging said portion for gripping engagement 52 the two opposite sides 50 of a filter unit 5 may be urged into opposite directions and opening of a filter unit 5 may thereby be done automatically. The portion for gripping engagement 52 may be a portion which is gas impermeable, or it may be a portion which comprises hook-and-loop fasteners (e.g. Velcro ®), hot melt or an adhesive layer or by means of needles.
In the exemplary embodiment where said portion 52 is gas impermeable, the corresponding outer area of the pocket side 50 may be covered with an impermeable sheet material such as plastic foil/film, aluminum foil or a glue such as hotmelt enabling for vacuum lifting.
The gripping member 72 may be a vacuum suction member or it may equally comprise hook-and-loop fasteners, or comprise an adhesive layer arranged to meet said pocket side 50. Common for all embodiments is that said gripping member 72 is arranged to detachably and temporarily engage with a portion 52 of the filter unit/bag 5 for automatic opening and transporting the unit 5 in order to rightfully position the same for further production steps. Once a filter unit is opened and/or rightfully positioned said gripping member 72 is preferably arranged to detach from the portion for gripping engagement 52, for instance vacuum suction is stopped or the gripping member 72 is pulled away from the pocket side 50 so that any of said temporary interaction (e.g. by hook-and-loop fasteners or adhesive) is interrupted.
A plurality of filter units 5 are thus arranged so that the filter unit openings are positioned with the opening edges adjacent to each other 55. The production steps up to the adjacently positioned filter units 5 are illustrated in figures 4A-B. After having become adjacently positioned, neighboring filter units 5 are joined by attaching two adjacent opening edges to each other with a clamping strip 3, which clamping strip 3 has previously been described. A clamping strip 3 is folded over two adjacent edges, and is subsequently sealed, for instance by welding. In a subsequent step an assembled outer frame 2 according to the invention is provided and positioned to enclose the plurality of juxtaposed filter units 5. The respective end portions 31 of each clamping element 3 are permanently fixated to the side profiles 6 of the outer frame 2 in such a way that each clamping element 3 is positionally fastened thereto whereby is achieved an assembled filter frame arrangement 1.
The skilled person realizes that a large variety of modifications may be performed without the use of inventive skill, departing from the description above, e.g. the use of adhesive layer or Velcro® on either or both of the portion for gripping engagement 52 and the gripping member 72 respectively, or adjusting the angle between the two tongues 40 of the corner element 4.
Furthermore it is within the scope of the present invention to have a different design of the tongues 40 compared to the one shown in the figures, however using the same principle. It is also understood that the principle for assembling an outer frame 2 using corner elements 4 according to the invention may be very useful in various contexts apart from filter frames, for instance mounting of a window frame or picture frame.
It should be further noted that the above described embodiments, e.g. said filter units 5 and corresponding method for handling/opening/transporting the same, as well as said side profiles 6, corner elements 4 and clamping elements 3 each may be the subject for its own protection. Hence, it foreseen that these aspects of the invention may require a protection by its/their own, e.g. since each thereof may be applicable per se also in other concepts than that defined by the independent claim/s in this application. It is understood, however, that the cooperation of the various embodiments incorporated into one filter frame arrangement 1 will enable for a fully automatic production process of a surprisingly rigid and strong frame.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated figures.
Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
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