Patent Application
20240374096
The invention relates to a vacuum cleaner filter bag comprising a bag wall and a retaining plate which is connected to the bag wall, the bag wall comprising a film region in which a plastic film is arranged.
Vacuum cleaner filter bags of this kind are known, for example, from EP 3 066 968. Often, the plastic film is a transparent film. The film region is therefore transparent and makes it possible to visually determine how full the vacuum cleaner filter bag is. It is also known to arrange viewing windows in the form of transparent films in other regions of the bag wall, for example from DE 20 2005 007 503 and DE 102 24 561. However, in many vacuum cleaner models, viewing windows in the region of the retaining plate have the advantage that they are particularly easy to see through.
Aside from forming transparent regions, films are also used, for example, to prevent the build-up of a filter cake or to reduce the abrasion of the filter material in particularly stressed regions inside the bag. Films in the region of the bag wall are also known from EP 2 025 278 and DE 20 2008 004 025.
EP 3 066 968 also describes non-transparent films in the region of the retaining plate for facilitating the insertion of the retaining plate into the corresponding receptacle in the vacuum cleaner housing. The plastic film therefore forms the outermost layer of the bag wall in this region.
In the latter case and in the case of a transparent film in the region of the retaining plate for forming a viewing window, the retaining plate is connected to the plastic film.
However, it has proven problematic to weld a retaining plate to a film. The highest achievable tensile force is usually insufficient, and therefore the retaining plate too easily becomes detached from the bag wall, in particular the film. Holes or weak points that tear further under loading often appear in the film on account of the joint welding.
In order to improve the connection between the retaining plate and the film, it is known from WO 2017/098035 to arrange a textile material between the retaining plate and the film. However, this solution has the disadvantage that several elements have to be mutually aligned.
The object of the present invention is therefore to provide a vacuum cleaner filter bag which is more efficient to produce and a method which makes possible this more efficient production of a vacuum cleaner filter bag.
This object is achieved by means of a vacuum cleaner filter bag according to claim 1 and by means of a method according to claim 6. Advantageous developments of the invention are given in the dependent claims.
According to the invention, the retaining plate is not only connected to the plastic film, but also to a nonwoven fabric element that overlaps with the plastic film in part. The nonwoven fabric element has at least one part which is connected, in particular directly, to the part of the bag wall that surrounds the film region. As a result, the positioning of the nonwoven fabric element in relation to the plastic film and the retaining plate can be improved. In particular, it is not necessary to align the nonwoven fabric element as a separate component relative to the film and the retaining plate. This enables an increased production efficiency of the vacuum cleaner filter bag.
In the context of the present invention, “region” refers to a three-dimensional part of an element that is characterized by one or more specific properties. For example, the film region of the bag wall is the three-dimensional bag wall part in which the plastic film is arranged.
The plastic film may be designed to be transparent or non-transparent. The plastic film may in particular be referred to as transparent or see-through if the proportion of visible light that can pass through the plastic film is at least 25%, in particular at least 50%. In particular, this proportion may pass through the plastic film such that imaging of an object located behind it is possible. In other words, the light passing through is not diffuse light.
In the case of a transparent plastic film, the first sub-region of the film region thus forms a transparent region of the bag wall that makes it possible to look into the interior of the vacuum cleaner filter bag. The transparent region therefore forms a sort of viewing window in the bag wall. In this case, in particular, the bag wall in the first sub-region may be formed solely by the plastic film. If necessary, a net or a further transparent element may be connected to the bag wall and overlap with the first sub-region, wherein, however the net or other transparent element is designed such that it does not prevent visual inspection of the interior of the vacuum cleaner filter bag through the transparent region.
The first sub-region of the film region does not have to be designed to be contiguous. For example, the first sub-region may comprise at least two parts that are separated from one another by the second sub-region of the film region.
In the context of the present invention, the bag wall part surrounding the film region refers to the bag wall part that adjoins, in particular directly, the region in which the plastic film is arranged.
It may be possible to attach the retaining plate to a retaining means in a vacuum cleaner housing. As a result, it may be possible to arrange, in particular to secure, the retaining plate in a predetermined position in the vacuum cleaner housing. Alternatively, it may be possible to slide the vacuum cleaner filter bag over a connection nozzle on the vacuum cleaner with the aid of the retaining plate.
In particular in the case of a non-transparent plastic film, the bag wall may form the outermost layer of the bag wall in the first sub-region. This makes it possible to facilitate insertion of the retaining plate into the corresponding receptacle in the vacuum cleaner housing. A transparent plastic film may also form the outermost layer of the bag wall. If said transparent plastic film does not overlap with non-transparent parts of the bag wall, it can be used as a viewing window and for easier insertion of the bag into the holder of the vacuum cleaner.
The plastic film may in particular be referred to as non-transparent or opaque if the proportion of visible light that can pass through the plastic film is less than 25%, in particular less than 10%. The plastic film may also be referred to as non-transparent or opaque if the proportion of visible light that can pass through the plastic film is greater than 25%, but this proportion passes through the plastic film such that imaging of an object behind it is not possible. In other words, the light passing through is diffuse light in that case.
The nonwoven fabric element may in particular be manufactured from the same material as the bag wall surrounding the film region. The nonwoven fabric element may in particular be integrally formed with the bag wall surrounding the film region. In other words, according to a preferred embodiment of the invention, the nonwoven fabric element is not a separate element connected to the bag wall surrounding the film region, but rather an integral part. This can be achieved by the bag wall part surrounding the film region comprising one or more layers of nonwoven fabric and the nonwoven fabric element being formed as a residual part of said nonwoven fabric layers in one or between multiple cut-outs.
The nonwoven fabric element may comprise a through-hole which is arranged concentrically with respect to a through-hole in the plastic film and a through-hole in the retaining plate. As a result, an inflow opening through which the dust-laden air can enter the bag interior can be formed. In particular, a nozzle of a vacuum cleaner can be introduced at least in part in the vacuum cleaner filter bag via the through-hole in the retaining plate and the through-holes in the plastic film and nonwoven fabric element.
The nonwoven fabric element may comprise an annular region that surrounds the through-hole and that is connected to the bag wall part surrounding the film region via at least one connection piece, and wherein the retaining plate is connected to the nonwoven fabric element in the annular region. The annular region may be dimensioned such that it is completely connected, in particular welded, to the retaining plate. As a result, the annular region looks no different to the direct connection of the retaining plate to the transparent plastic film, as is known, for example, from EP 3 066 968.
Compared to a direct connection to the film, in this example i the at least one connection piece, by means of which the annular region is connected to the bag wall part surrounding the film region, remains as a significant optical difference. However, the connection piece may have much smaller dimensions than the first sub-region. In a plan view of the bag wall part in which the film region and retaining plate are arranged, the surface area of the region of the connection piece that overlaps with the plastic film is thus smaller than the surface area of the first sub-region.
Two or more connection pieces may also be provided in order to connect the annular region to the bag wall part surrounding the film region, in particular two, three or four connection pieces. In the case of two connection pieces, they may connect the annular region in particular to opposing sides of the bag wall part surrounding the film region. This enables a particularly advantageous stabilisation and localisation of the nonwoven fabric of the bag wall and of the nonwoven fabric element during production. In the case of four connection pieces, the connection pieces may connect the annular region to the bag wall part surrounding the film region in pairs on opposing sides of the film region.
It should be noted that, in the context of the present invention, the term “annular” is not limited to the shape of a circular ring. The actual shape of the annular region may be adapted to the shape of the region of the retaining plate provided for connection to the bag wall. As a general rule, the annular region may be a closed region that surrounds the through-hole in the plastic film and nonwoven fabric element. The annular region may extend between a closed inner and a closed outer boundary line. The boundary lines may be circular, elliptical or shaped in any other desired manner. The boundary lines may cross the at least one connection piece. The splitting into an “annular region” and “connection piece” merely serves to describe the geometry of the nonwoven fabric element. The annular region and at least one connection piece are in fact integral components of the nonwoven fabric element described here and are merged.
The outer boundary of the film region may be rectangular or square. In other words, the plastic film may be rectangular or square. However, the plastic film may also have other shapes, for example it may be round or oval. The outer boundary may be formed by a weld seam that connects the plastic film to the nonwoven fabric of the bag wall. Said weld seam may simultaneously be part of or correspond to the bag wall part surrounding or delimiting the film region.
Within the context of the present invention, “connection piece” should be understood to mean an element that proceeds from one edge of the outer boundary and connects said edge to another element of the nonwoven fabric element, for example to the annular region. In its simplest form, the connection piece is rectangular or square in a plan view of the bag wall part comprising the film region. However, other geometries are also conceivable.
As mentioned above, two connection pieces may connect two opposing sides or edges of the outer boundary to the annular region.
The retaining plate and the plastic film may be arranged such that the nonwoven fabric element is located between the retaining plate and the plastic film.
Alternatively, the retaining plate and the plastic film may be arranged such that the plastic film is located between the retaining plate and the nonwoven fabric element.
The bag wall of the vacuum cleaner filter bag, in particular the bag wall part surrounding the film region and also the nonwoven fabric element, may comprise one or more filter material layers, in particular one or more nonwoven fabric layers. Vacuum cleaner filter bags comprising several filter material layers are known, for example, from EP 2 011 556 and EP 0 960 645. A wide variety of plastics may be used for the nonwoven fabric layers, for example polypropylene and/or polyester. The bag wall of the vacuum cleaner filter bag may also comprise recycled plastic. For example, the bag wall may be designed in the manner described in EP 3 219 376 A1.
The term nonwoven (German “Vliesstoff”) is used according to the definition in ISO Standard ISO9092: 1988 or CEM Standard EN29092. In particular, the terms fibrous web or web and nonwoven fabric are defined in the field of the manufacture of nonwoven fabrics and also to be understood in the context of the present invention as follows. For the manufacture of a nonwoven, fibers and/or filaments are used. The loose or loose and still unbound fibers and/or filaments are referred to as web or fibrous web. Via a so-called web bonding step, a nonwoven fabric is finally formed from such a fibrous web, which has sufficient strength to be, e.g., wound up into rolls. In other words, a nonwoven fabric is made self-supporting by bonding. (Details of the use of the definitions and/or processes described herein can also be found in the standard work “Nonwovens”, W. Albrecht, H. Fuchs, W. Kittelmann, Wiley-VCH, 2000).
The plastic film may be directly connected, in particular welded, to one or more nonwoven fabric layers of the bag wall. In addition, the plastic film may be directly connected, in particular welded, to the at least one connection piece of the nonwoven fabric element. As a result, the at least one connection piece for connecting the retaining plate to the bag wall can be used, which further increases the stability of the connection between the retaining plate and the bag wall.
When reference is made herein to “welding”, this should be understood to mean connection by means of ultrasonic welding.
The plastic film may be a blown film or a cast film. The term “film” refers to an element of which the thickness is substantially lower than the extent thereof (length and width) perpendicular to the thickness. For example, a film may have an, in particular constant, thickness of less than 300 μm, for example 100 μm. The plastic film may be manufactured from polypropylene, PP, polyethylene, PE, polyethylene terephthalate, PET, polyamide, PA, or polycarbonate, PC.
In claim 6, the invention provides a method for producing a vacuum cleaner filter bag, in particular a vacuum cleaner filter bag as described above. According to this method, at least one through-opening is punched into a sheet of nonwoven fabric such that a region free of nonwoven fabric is formed in the sheet of nonwoven fabric. The region free of nonwoven fabric is formed such that, after punching, a nonwoven fabric element is left which is arranged between two opposing edge portions of the region free of nonwoven fabric and which is spaced apart from the opposing edge portions in each case by means of a sub-region of the region free of nonwoven fabric.
According to the prior art, a rectangular or square through-opening would have been punched and a plastic film would have been arranged herein afterwards. In order to connect the retaining plate to the film, a separate textile element would have to be produced and aligned relative to the film together with the retaining plate. According to the invention, the nonwoven fabric element remains part of the sheet of nonwoven fabric after the at least one through-opening is punched, which greatly simplifies production and alignment.
If one through-opening is punched, the through-opening forms the region free of nonwoven fabric. If more than one through-opening is punched, the region free of nonwoven fabric is formed by a combination of the punched through-openings. The region free of nonwoven fabric may comprise a plurality of non-contiguous sub-regions and/or a plurality of contiguous sub-regions. The sub-regions may each be formed by one of the through-openings.
The nonwoven fabric element is arranged between two opposing edge portions. In other words, there are two edge portions on the edge of the region free of nonwoven fabric which are opposite one another and between which the nonwoven fabric element is arranged. There also may be a plurality of pairs of opposing edge portions on the edge of the region free of nonwoven fabric between which the nonwoven fabric element is arranged.
The nonwoven fabric element may be arranged fully or partially between two opposing edge portions. Further edge portions may also be arranged between the opposing edge portions.
The edge of the region free of nonwoven fabric is formed by a combination of the edges of the through-openings. The edge of the region free of nonwoven fabric may therefore also comprise a plurality of non-contiguous edge portions. For example, the region free of nonwoven fabric may be formed by two separate, i.e. non-contiguous, through-openings. In this case, the edge of the region free of nonwoven fabric is composed of the non-contiguous edges of both through-openings.
The formation of the through-hole in the plastic film may take place at the same time as the formation of the through-hole in the nonwoven fabric element. However, it is also conceivable for the through-hole to be formed in the nonwoven fabric element before the through-hole is formed in the plastic film.
After the retaining plate is welded to the plastic film and nonwoven fabric element, the sheet of nonwoven fabric may be cut to the appropriate size and the vacuum cleaner filter bag may be assembled. In particular, the vacuum cleaner filter bag may be produced as a flat bag. In this case, an upper layer may be circumferentially welded to a lower layer, the film region being arranged together with the retaining plate in the upper layer, for example.
In particular, two through-openings may be punched which are formed symmetrically with respect to an axis of symmetry that extends in the machine direction, in particular wherein the through-openings are punched such that the nonwoven fabric element remains between the through-openings.
It is also conceivable to punch more than two through-openings, for example three or four. In this case, too, symmetry with respect to an axis of symmetry that extends in the machine direction is advantageous and possible. The nonwoven fabric element may be arranged partially between two or more than two through-openings in each case. The region of the sheet of nonwoven fabric in which the region free of nonwoven fabric and the nonwoven fabric element are arranged may have a rectangular, in particular square, boundary.
The nonwoven fabric element may comprise, before the through-hole is formed, a region in the shape of a disc and at least one connection piece, which connects the region in the shape of a disc to the rest of the sheet of nonwoven fabric.
The region in the shape of a disc forms a sort of extension of the nonwoven fabric element that extends transversely to the machine direction. This is where the through-hole is to be formed and the retaining plate to be attached later. The region in the shape of a disc may be punched so as to be annular, the retaining plate being connected, in particular welded, to the annular region of the nonwoven fabric element.
A single connection piece is less stable than a plurality thereof. In particular, if the sheet of nonwoven fabric is pulled, the at least one punched through-opening can be deformed and the sheet of nonwoven fabric can warp and/or wave in the region of the through-opening. By means of at least two connection pieces, the sheet of nonwoven fabric can be stabilized such that the undesired effects do not occur or occur less. Accordingly, the sheet speed between cycles and thus the production speed can be increased.
The connection pieces may in particular be arranged on sides of the region in the shape of a disc that oppose one another in the machine direction. Additional connection pieces may also be arranged on two sides of the region in the shape of a disc that oppose one another transversely to the machine direction. It is also conceivable for one or more connection pieces to extend at an angle of 20° to 60°, in particular 45°, relative to the machine direction.
The retaining plate may comprise guides which are arranged in a region of the retaining plate surrounding a through-hole of the retaining plate, the radial extension of which region corresponds to that of the annular region of the nonwoven fabric element. In other words, the annular region may be adapted to the region of the retaining plate in which the guides are arranged, and is therefore provided for connecting the retaining plate to the nonwoven fabric element and plastic film.
The retaining plate and the plastic film may be arranged such that the nonwoven fabric element is located between the retaining plate and the plastic film after connection of the retaining plate.
Alternatively, the retaining plate and the plastic film may be arranged such that the plastic film is located between the retaining plate and the nonwoven fabric element after connection of the retaining plate.
These two alternatives can be achieved by welding the plastic film to the sheet of nonwoven fabric either from above or from below, when viewing the sheet of nonwoven fabric in plan view.
The region of the sheet of nonwoven fabric in which the at least one through-opening is to be formed may be at least partially thermally compacted prior to punching of the at least one through-opening. As a result, the through-openings can be punched out more precisely. For example, the corresponding regions of the sheet of nonwoven fabric may be compacted by means of ultrasound or pre-embossed using a calender.
The plastic film may be connected to the sheet of nonwoven fabric and to the nonwoven fabric element. In particular, the plastic film may be connected, in particular welded, to a region of the sheet of nonwoven fabric surrounding the region free of nonwoven fabric, to the annular region and to the at least one connection piece of the nonwoven fabric element.
In addition, the retaining plate may be connected, in particular welded, to the at least one connection piece of the nonwoven fabric element. As a result, the connection between the retaining plate and bag wall can be made even more stable.
The sheet of nonwoven fabric may comprise one or more filter material layers, in particular one or more nonwoven fabric layers. Filter material layers of this kind are known, for example, from EP 2 011 556 and EP 0 960 645. A wide variety of plastics may be used for the nonwoven fabric layers, for example polypropylene and/or polyester. The bag wall of the vacuum cleaner filter bag may also comprise recycled plastic. For example, the bag wall may be designed in the manner described in EP 3 219 376 A1.
The plastic film may comprise one or more of the above-mentioned features.
The vacuum cleaner filter bag produced in this manner may comprise one or more of the above-mentioned features.
Additional features and advantages of the invention will be explained below with reference to the exemplary figures, in which:
When the sheet of nonwoven fabric is moved along further after the through-openings 1, 2 have been punched, it is drawn in the machine direction. In the prior art, in which the nonwoven fabric element 3 was not provided, this being drawn in the machine direction resulted in a deformation of the single through-opening provided, which led to disadvantages during further processing. Therefore, in the prior art, the sheet of nonwoven fabric had to be moved slowly and carefully. However, by virtue of the nonwoven fabric element 3, the region of the through-openings 1, 2 is stabilized during a tug in the machine direction, such that higher processing speeds are possible.
As can also be seen in
In this case, the nonwoven fabric element 3 comprises a central region in the shape of a disc and two connection pieces that oppose one another in the machine direction and that connect the region in the shape of a disc to parts of the above-mentioned boundary.
The sheet of nonwoven fabric is merely shown schematically in the present case, in particular the borders 5, 6 thereof extending transversely to the machine direction.
In another method step illustrated in
In the finished form of the vacuum cleaner filter bag, the regions of the plastic film that are not overlapped by the nonwoven fabric element 3 form a first sub-region of a film region that, in the case of a transparent film, serves as a sort of viewing window such that it is possible to visually determine how full the vacuum cleaner filter bag is and, in the case of a non-transparent film, contributes to easier insertion of the vacuum cleaner filter bag into a corresponding receptacle in the vacuum cleaner.
By punching the through-hole 9, the previously disc-shaped central part of the nonwoven fabric element 3 is formed into an annular region 10 that is connected via two connection pieces 11, 12 to the rest of the sheet of nonwoven fabric, in particular to the weld seam 7.
The shape and radial extent of the annular region 10 is adapted to the region of the retaining plate which is provided for connection to the bag wall. This region of the retaining plate typically comprises guides in order to improve welding of the retaining plate to the bag wall.
Finally,
As known per se, the retaining plate 13 comprises a sealing lip 14 and a closure cap (closure cap not shown in
As can be seen in
Finally, a vacuum cleaner filter bag can be assembled by cutting the sheet of nonwoven fabric to the appropriate size and for example interconnecting two nonwoven fabric layers by means of a circumferential weld seam. One of the two nonwoven fabric layers comprises the film region and the retaining plate.
Instead of connecting the plastic film from underneath the sheet of nonwoven fabric, as shown in
Furthermore, it is possible to partially or fully thermally compact, for example by means of ultrasound or pre-embossing, the regions of the sheet of nonwoven fabric in which the through-openings 1, 2 are to be punched (cf.
The geometry of the nonwoven fabric element 3 is shown merely by way of example in
In
In
However, it is also possible to connect the disc-shaped region to the rest of the sheet of nonwoven fabric via only one connection piece, as shown in
It should be understood that features mentioned in relation to the above-described exemplary embodiments are not limited to specific combinations and, as such, any other desired combinations are also possible. In particular, it should be understood that geometries shown in the figures, for example those of the retaining plate, are merely exemplary and, as such, any other desired configurations are also possible.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18169777.2 | Apr 2018 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/057052 | 3/21/2019 | WO |
