GB2064978A - Filter bag with removable shaping members - Google Patents

Abstract

A filter structure supporting a series of tubular filter bags 3 for filtering a dust-laden airflow DA. The filter bags 3 are subjected to a momentary reverse flow for purging collected particles from the bag walls. The filter bags 3 are supported against pressure drops across the bag walls by bag shaping members 10 spaced at intervals along each filter bag. Each bag shaping member 10 is retained in an adjustable annular pocket formed by a cuff 11 secured to the bag wall. The cuff 11 is provided with size adjusting means, e.g. a drawstring 14, which permits contraction of the pocket to confine the shaping member therein and also expansion of the cuff 11 to permit convenient removal of the shaping member 10. <IMAGE>

Description

SPECIFICATION Filter bag with removable shaping members The present invention relates to tubular filter bags for filtering a dust-laden airflow by separating out airborne particles during passage of the airflow through a bag wall.

During normal bag operation as well as during bag cleaning by a reverse airflow, the bag is subject to inward and outward distortion. To prevent severe bag distortion, it has become common to mount rigid rings at spaced intervals along the filter bag.

After several months of bag operation it is common practice to remove the bag from the filter structure for transfer to a cleaning facility. During such bag cleaning it is best that the shaping members be removed from the bag to prevent premature bag wear and early failure of the bag.

While the prior art discloses the use of filter bag shaping rings, no bag structure is found providing convenient installation and removal of such rings.

The present invention is embodied within filter bag construction wherein bag shaping members are spaced along the tubular bag wall in a manner permitting their convenient removal and replacement.

Important objectives of the present bag construction include the provision of a filter element or bag having shaping members removably attached there- to; the provision of filter bag construction having removable bag shaping members to permit launder~ ing or cleaning of the bag without subjecting the bag to wear or damage from the rigid bag shaping members; the provision of a filter bag providing a removable bag shaping member supported within a bag attached cuff in a manner preventing abrasion between the shaping member and bag with the cuff having adjustable sizing means readily contractable and expansible for retention of the shaping member or convenient release of the shaping member prior to bag laundering.

In the drawings: Figure 1 is a fragmentary elevational view of an industrial filter of a type utilizing tubular fabric filter bags; Figure2 is an enlarged, side elevational view of a bag segment of a bag made in accordance with the present invention; Figure 3 is a vertical, sectional view taken along line 3-3 of Figure 2 on an enlarged scale; Figure 4 is a view similar to Figure 2 but on a smaller scale showing a modified retainer arrangement for a bag shaping member; Figure 5 is an enlarged fragmentary view of bag construction with still another modified retainer arrangement for securing the bag shaping member in place; Figure 6 is a view similar to Figure 5 showing a further modification; and Figure 7 is an enlarged fragmentary view of a filter bag wall with still another modified retainer arrange- ment.

With reference to the drawings, the reference numeral 1 indicates generally an industrial type filter structure currently in use. Fragments are broken away to disclose an inlet structure 2 for a dust-laden airflow at DA resulting from an industrial operation.

The dust-laden airflow is directed toward an array of tubular filter bags 3 each having a main body wall.

Filtering occurs during air passage through the air permeable bag walls. Operation of the filter structure over a period of time results in the deposit of a layer of particles on the bag interior which particles must be removed at intervals to restore desired permeability of the bag walls for proper filter operation. In the filter structure shown, the bags 3 receive a dust-laden airflow at their lower ends with filtering accomplished during outward passage of the air through the bag walls. The air returns to the atmosphere via annular filter opening 9. The filter bag improvement may be used in other filter bag structures.

For particle removal during a filter operation, a reverse flow of pure air through the bag walls is induced by a rotatable sweep or purge suction duct at 4 in communication at its unseen end with a below atmospheric source of negative pressure such as the intake side of a blower. The purge duct 4 rotates into successive communication with circularly disposed chambers at 5 each in upward communication with a filter bag 3. In Figure 1, a pair of filter bags is shown being subjected to a reverse purge flow by sweep 4.

The foregoing is a brief description of an industrial filter structure disclosed in U.S. Patent 3,871,845 owned in common by the owner of the present invention. It is to be understood thatthe present filter bag invention is in no way limited to use with any specific filter structure.

The tubular shaped filter bags 3 are of porous fabric, the porosity of which will vary to suit various filtering requirements. One commonly used bag material is woven polypropylene. Other bag material may be of felt construction. The bag 3 is open at one end and is secured thereat in place about a collar 6 by a removable band 7. The opposite bag end is shown being secured in place by an angular bracket 8 insertable through a folded and stitched portion of the bag end. Other arrangements may be utilized for securing the bag ends which permit infrequent bag removal for periodic laundering.

The present invention is embodied in bag construction having bag shaping members 10 such as metal rings located at intervals along the bag to maintain the bag in tubular configuration against pressure drops occurring across the bag wall. During filter operation, the bag wall is subjected to inward and outward displacement during filtering and purge modes of filter operation.

Each bag shaping member 10 is supported in place by retainer means, as shown in Figure 2, which includes a bag attached pliable cuff 11 secured in place on the bag by stitching 12. Cuff 11 is of greater diameter than the bag wall with an edge portion stitched at 12 to form a remaining cuff portion forming an annular pocket 13. The pocket is adjustable for the reception and release of shaping member 10. Sizing means are provided at 14 to permit adjustment of the size of the fabric cuff 11, to confine bag shaping member 10 in pocket 13 or, alternative ly, permit removal of shaping member 10 priorto bag laundering at a remote location.

The sizing means at 14 is shown as a drawstring which extends through a folded over cuff portion 15 which is stitched at 16 to define a fabric tube. The drawstring is tied at 17.

In Figure 5, a somewhat modified arrangement is shown wherein a knotted tie at 18 passes through eyelets and serves as sizing means to contract or permit expansion of a cuff portion at 15'. Other cuff components, similar to those described above, are identified by prime reference numerals.

In Figure 4, a further variation of the present invention is disclosed, which relies on the cuff perimeter size alone to retain bag shaping member 10" in place. The cuff 20 is attached to the bag by stitching 21 with the cuff ends joined by stitching 22.

A bag shaping member 10" is insertable into the cuff as shown by progressively forcing said shaping member into place within an annular pocket defined by said cuff and the adjacent bag wall. Stretching of the cuff fabric, though slight, is adequate to permit member acceptance. Said member is retained by the cuff edge at 20A, which has an effective diameter slightly less than the pocket defining portion of the cuff.

In Figure 6, another form of the present invention is shown wherein a bag shaping member 23 is removably confined within retainer means including a a fabric cuff 24 stitched along an edge portion to a tubular bag 3 by stitching 25 leaving spaced apart cuff ends. A folded portion 26 of a remaining cuff portion is stitched at 27 and receives sizing means shown as a chord 28 with ends 28A which are reversed to provide spaced apart looped segments secured by stitching 30 to the cuff. A convenient method of sizing the adjustable remaining edge portion 26 of the cuff is by use of tie means 31 which may be of the plastic type previously used in the tying of insulated electrical cables or wires into bundles and which includes a positive, automatic locking pawl to retain the tie in a loop shape.Tie 31 is inserted through the looped segments 28A of cord 28 and thereafter drawn toward a reduced size to reduce cuff 24 to a size enabling manual removal of shaping member 23 at bag cleaning or laundering intervals.

In Figure 7 a further modified form of the invention is disclosed wherein a bag wall 3 is again shaped by a a ring member 35. Retainer means for ring member 35 includes a fabric cuff 36 which, with other vertically spaced apart cuffs, is stitched at 37 along one of its edges to the bag wall 3. Cuff ends at 36A and 36B terminate in spaced relationship to one another to facilitate sizing of the adjustable remaining cuff portion at 36C. The adjustable remaining cuff portion has a folded and stitched portion with a line of stitching at 40 forming a fabric tube which is separate from the bag wall. Cuff sizing means comprises as flexible member 38 stitched at one of its ends at 41 to folded over cuff portion 36C so as to form a looped segment 38A while the remaining end segment of flexible member 38 is knotted at 42 to form a second looped segment 43.A pull segment 44 of the continuous member is easily grasped by a worker during cuff sizing since it is external of the cuff.

In sizing of a cuffto retain a bag shaping member 35 in place, tie means 45 is inserted through looped segments 38A and 43 with the tie end 45A thereafter being passed through an enlarged portion 45B of the tie which embodies a pawl (not shown) which admits inserted end 45A of the tie and automatically locks the tie end against retraction. The tie is of the same type earlier described. Obviously, other tie means could be utilized.

In the last described form of the invention the shaping member 35 is initially placed within the cuff after which the cuff is folded upwardly to enclose the shaping member. The pull portion 44 of the cord is manually tensioned or pulled to position loop segment 43 close to looped segment 38A and held there during insertion of tie means 45. The diameter of the adjustable cuff portion is thereby reduced to assure retention of the shaping member 35. For purposes of saving time in later removal of member 35, the plastic tie means 45 may be snipped with wire cutters.

Claims (9)

1. A tubular shaped air filter bag for use within an air filter structure, said filter bag comprising, a tubular bag adapted at its ends for attachment to the air filter structure, bag shaping ring members located in a spaced apart manner along the bag, and retainer means associated with each of said members and normally confining one of said bag shaping members in place about the bag body, each of said retainer means including a fabric cuff secured to the bag body and permitting temporary removal of a bag shaping member prior to removal of the filter bag for laundering purposes, said cuff being stitched adjacent one edge thereof to the bag body with a remaining adjustable cuff portion adapted to support a bag shaping member in a removable manner, cuff sizing means carried by and acting on said remaining cuff portion to enable contractive adjustment of same for retention of the bag shaping member and alternatively expansive adjustment of the cuff for removal of said shaping member.

2. The filter bag claimed in claim 1 wherein said remaining adjustable cuff portion of each of said retainer means has a folded and stitched portion, each of said cuff sizing means being carried by said folded and stitched portion.

3. The filter bag claimed in claim 2 wherein each of said cuff sizing means is a drawstring extending interiorly of said folded and stitched portion and with exposed ends for knotting.

4. The filter bag clained in claim 2 wherein each of said cuff sizing means is an elongated member secured at its ends to said cuff so as to form spaced apart looped segments, removable tie means interconnecting said looped segments in a tensioned manner to hold the cuff in a contracted state.

5. The filter bag claimed in claim 4 wherein each of said tie means is of the automatically locking type.

6. The filter bag claimed in claim 2 wherein each of said cuff sizing means is an elongated flexible member secured at one of its ends to said cuff so as to form a looped segment, said flexible member having a looped segment formed therein adjacent its opposite end, removable tie means interconnecting said looped segments in a tensioned manner for contraction of the cuff and retention of the bag shaping member.

7. The filter bag claimed in claim 6 wherein each of said tie means is of the automatically locking type.

8. The filter bag claimed in claim 6 wherein each of said flexible members additionally includes a pull segment at all times at least partially exposed for grasping and tensioning of the flexible member during application of the tie means.

9. An air filter bag constructed and arranged to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.