Gas separation – Flexible or collapsible bag type – Seaming – reinforcing or bag structure
Reexamination Certificate
1994-10-06
2001-06-26
Thornton, Krisanne (Department: 1744)
Gas separation
Flexible or collapsible bag type
Seaming, reinforcing or bag structure
C055S524000, C055SDIG002, C055SDIG003, C055SDIG005, C156S199000, C156S200000, C156S201000, C156S202000, C156S203000, C264S145000, C264S159000, C264S160000, C264S171100, C264SDIG004
Reexamination Certificate
active
06251154
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a dust bag, as well as to a method of producing a dust bag.
1. Background Art
In recent years, the suction performance of vacuum cleaners has increased constantly. As a result, the air flow sucked into the dust bag through the inlet opening thereof is so strong that the particles taken along in the air flow to be cleaned may damage the dust bag when impinging on the inner surface thereof. This risk of damage to the bag of the vacuum cleaner is particularly high at the inner surface of the dust bag opposite the inlet opening. Further, such dust bags are particularly prone to damages, in which the inflowing air impinges obliquely onto the inner surface of the dust bag opposite the inlet opening; in such dust bags, the inner surface portion opposite the inlet opening is blown clean by the inflowing air so that no dust or particles can gather there which could protect the inner surface from damage.
From European Patent 0 161 760 A2, a dust bag is known having a filter bag consisting of a three-layered fiber material composite. An inner layer of polypropylene micro fiber is disposed between two outer supporting layers of high strength. The two outer layers consist of a nonwoven web of nylon fibers that are welded together. These outer layers are of a relatively high strength both in the machining direction and transversally thereto. However, since this known dust bag has two fiber layers of high strength, seen over its entire wall, it is comparatively expensive to produce.
It is an object of the present invention to provide a dust bag that is protected from damage by sucked particles and may be produced at low cost.
2. Description of the Invention
The object is solved by the dust bag of the present invention having a filter bag provided with an air-permeable filter material and having two wall portions that are connected or closed at their respective opposite edges so as to form the filter bag. The inlet opening for allowing the inflow of the air to be cleaned into the filter bag is arranged in one of the two wall portions. On the inner surface of the wall portion opposite the inflow opening, a protective layer is provided that is made from an air-permeable material resistant to mechanical stresses caused by particles in the air flow and protecting the filter material of the filter bag. This protective layer extends at least over the surface portion of the other wall portion opposite the inlet opening and between at least two interconnected edges of the two wall portions, the protective layer being held between the interconnected edges over at least a part of their length. The protective layer may lie on the inner surface of the wall portion opposite the inlet opening.
The protective layer of the dust bag of the present invention is an insert positioned in the filter bag prior to the completion thereof. This insert is held on the filter bag by at least two interconnected end edges. Preferably, the insert is held at the filter bag at those of the insert's ends that are disposed between the interconnected edge portions of the wall portions of the filter bag. Each wall portion may be integral or may consist of a plurality of parts that are interconnected to constitute the respective wall portion. Advantageously, the protective layer of the present dust bag is in the form of a strip-shaped web that does not extend over the entire surface of the wall portion opposite the inlet opening, but is arranged only in the surface portion opposite the inlet opening and extends through the filter bag. The protective layer consists of air-permeable material. Preferably, the permeability to air of this material is considerably higher (for example, at least by the factor 10) than the permeability to air of the actual filter material so that the pressure drop of the dust bag is not or only insignificantly reduced.
Advantageously, the protective layer consists of a non-woven of rigidly connected (e.g. heat bonded) synthetic polymeric fibers and has a comparatively high strength, though being light of weight. Preferably, the strength of the protective layer is greater than that of the filter material by at least the factor 2 to 3.
In a first variant of a method of production according to the present invention, the dust bag described above is made by forming a first web of air-permeable filter material. While being supplied, this first web of air-permeable filter material is shaped such that both longitudinal edges thereof are made to overlap. Together with the first web, a separate second web is supplied as a protective layer for the first web, the second web being narrower than the first one. The second web is about centered with respect to the first web. By shaping the first web, the same encloses the second web so that after connecting the overlapping longitudinal edges of the first web, a tube of filter material is obtained. In this tube, the second web is arranged as an insert, consisting of an air-permeable material resistant to mechanical stresses caused by particles in the air flow and protecting the filter material of the first web. The first web is provided with an opening which forms the (future) inlet opening which forms the (future) inlet opening of the finished dust bag for the inflow of air to be filtered into the filter bag. The inlet opening is provided opposite the second web. After the overlapping longitudinal edges have been connected, a section of the first web thus formed is severed with the second web disposed therein. The cut off section is then sealedly closed at both open end edges, which may be done, for example, by folding and heat bonding or glueing the ends. In doing so, both longitudinal ends of the second web are held at the two closed ends of the cut off section. The insert of the invention provided for the protection of the dust bag in the area opposite the inlet opening can thus readily be integrated into the production process as a second web supplied in addition to the first web. The second web is automatically fastened to the filter material web when closing the ends of the cut off hose section of filter material containing the second material web therein. There is no need for a large surface fastening of the second web to the first filter material web, since the inflowing air presses the second web onto the inner surface of the filter bag.
Whereas, according to the above method, dust bags of in particular paper filter material are generally produced, a second variant of the method of the present invention preferably provides for the production of dust bags using a fiber layer composite as the filter material. Onto a first layer of such an air-permeable composite filter material, comprising one or more layers and synthetic, thermoplastic fibers, a second layer of a material is applied that is resistant to mechanical stresses caused by particles in the air flow to be filtered and is permeable to air. Onto this second layer, a third layer that is of the same material as the first layer is applied such that at least the edges of the first and the third layer overlap and at least two (opposing) edges of the second layer overlap opposing edges of the first and the third layer. The overlying layers are then welded together along the overlapping edges. Prior to welding and superposing the layers, an opening will be formed in the first or the third layer, the opening being opposite the second layer. By welding the described sequence of layers in order to produce the dust bag, the second layer is held between the two layers of filter material at its ends and/or its edge portions. Preferably, the second layer is narrower than the first or the third layer and extends through the dust bag only over the surface portion opposite the inlet opening.
In both methods of production, the inlet opening can also be provided in the filter bag after the same has been closed.
In its edge portions secured between the welded edges of the two filter material layers, the resistant second (intermediate) layer contributes to the strengthening
3M Innovative Properties Company
Bond William J.
Griswold Gary L.
Sprague Robert W.
Thornton Krisanne
LandOfFree
Dust bag and method of production does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dust bag and method of production, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dust bag and method of production will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2447180