METHOD AND APPARATUS FOR MAKING A FILTER ELEMENT

Abstract

There is disclosed a method for making a filter element comprising the steps of: advancing two or more sheets of filtering material in a longitudinal direction; separating the two or more sheets of longitudinally advancing filtering material; gathering the separated sheets of longitudinally advancing filtering material to form a partially gathered rod of filtering material having a longitudinally extending recess; inserting an additive release vessel into the longitudinally extending recess; gathering the filtering material around the additive release vessel to close the recess and thereby form a rod comprising a longitudinally extending core of filtering material and one or more additive release vessels.

Claims

1-33. (canceled)

34. A method for making a filter element comprising the steps of: advancing two or more sheets of filtering material in a longitudinal direction; separating the two or more sheets of longitudinally advancing filtering material; gathering the separated sheets of longitudinally advancing filtering material to form a partially gathered rod of filtering material having a longitudinally extending recess; inserting an additive release vessel into the longitudinally extending recess; gathering the filtering material around the additive release vessel to close the recess and thereby form a rod comprising a longitudinally extending core of filtering material and one or more additive release vessels.

35. The method according to claim 34, wherein the two or more sheets of longitudinally advancing filtering material are separated by a separator; and/or wherein the gathering of the separated two or more sheets of longitudinally advancing filtering material comprises drawing the separated two or more sheets of longitudinally advancing filtering material into a gathering chamber.

36. The method according to claim 35, wherein the separator is coupled to the gathering chamber such that the two or more sheets of longitudinally advancing filtering material are separated before entering the gathering chamber, and the separator prevents complete gathering of the two or more sheets of longitudinally advancing filtering material to thereby form a longitudinally extending recess in the partially gathered filtering material.

37. The method according to claim 35, wherein the gathering chamber comprises an inlet for receiving the separated sheets of filtering material and an outlet for the partially gathered filtering material to exit, and wherein the gathering chamber is tapered longitudinally away from the inlet; and/or wherein the separator is longitudinally tapered and/or extends into and along at least part of the length of the gathering chamber; and/or wherein the separator is tapered in the same direction as the gathering chamber.

38. The method according to claim 36, wherein the separated two or more longitudinally advancing sheets of filtering material are drawn into a preliminary chamber before entering the gathering chamber; for example wherein the preliminary chamber comprises an inlet and an outlet, wherein the outlet of the preliminary chamber is joined to the inlet of the gathering chamber, and wherein the separator extends into and along at least part of the length of the preliminary chamber.

39. The method according to claim 34, wherein the additive release vessel is inserted into the longitudinally extending recess by an additive release vessel inserter; for example wherein the additive release vessel inserter comprises a rotating drum or wheel.

40. The method according to claim 34, wherein the two or more sheets of filtering material are embossed; and/or wherein the filtering material comprises a non-woven material; and/or wherein the filtering material comprises paper; and/or wherein the two or more sheets of longitudinally advancing filtering material comprise 2, 3 or 4 sheets of longitudinally advancing filtering material.

41. The method according to claim 34, comprising a step of cutting the rod to form a filter element comprising a longitudinally extending core of filtering material and one or more additive release vessels.

42. A filter element comprising a longitudinally extending core of filtering material and an additive release vessel enclosed within the longitudinally extending core of filtering material; wherein the longitudinally extending core of filtering material is formed from two or more sheets of filtering material.

43. The filter element according to claim 42, wherein the filtering material comprises paper or a non-woven material; and/or wherein the additive release vessel is a capsule.

44. An apparatus for making a filter element comprising: a separator for separating two or more longitudinally advancing sheets of filtering material; a gathering chamber configured to gather the separated longitudinally advancing sheets of filtering material and form a rod of partially gathered filtering material; wherein the separator is coupled to the gathering chamber such that the separator and the gathering chamber are configured to form a longitudinally extending recess in the rod of partially gathered filtering material; and an inserter configured to insert one or more additive release vessels into the longitudinally extending recess.

45. The apparatus according to claim 44, wherein the gathering chamber comprises an inlet for receiving the separated sheets of filtering material and an outlet for the partially gathered filtering material to exit, and wherein the gathering chamber tapers longitudinally away from the inlet; and/or wherein the separator is longitudinally tapered and extends into and along at least part of the length of the gathering chamber; for example wherein the separator is tapered in the same direction as the gathering chamber.

46. The apparatus according to claim 44 comprising: a preliminary chamber comprising: an inlet and an outlet; wherein the outlet of the preliminary chamber is joined to the inlet of the gathering chamber; and wherein the separator extends into and along part of the length of the preliminary chamber; for example wherein the preliminary chamber tapers longitudinally away from the inlet.

47. The apparatus according to claim 44, wherein the gathering chamber comprises a longitudinally extending aperture for receiving the inserter; and/or wherein the gathering chamber is configured to gather the filtering material around the additive release vessel to close the recess and thereby form a continuous rod comprising a longitudinally extending core of filtering material and one or more additive release vessels; and/or wherein the apparatus comprises a rod cutter configured to cut a rod comprising a longitudinally extending core of filtering material and one or more additive release vessels to form a filter element; and or wherein the inserter comprises a rotating drum or wheel configured to insert the or each additive release vessel into the longitudinally extending recess.

48. An apparatus for separating and gathering two or more sheets of filtering material, the apparatus comprising: a gathering chamber comprising an inlet and an outlet, wherein the inlet has a larger diameter than the outlet such that the gathering chamber is longitudinally tapered; a separator extending at least part of the way into the gathering chamber and protruding from the inlet of the gathering chamber; wherein the separator and the gathering chamber are configured to separate and partially gather two or more sheets of filtering material to thereby form a partially gathered longitudinally extending rod of filtering material comprising a longitudinally extending recess.

Description

[0085] Preferred embodiments of the invention will now be described by reference to the accompanying drawings in which:

[0086] FIG. 1 is a schematic overview of the method of the present invention;

[0087] FIG. 2 is a perspective view of part of the apparatus according to the present invention;

[0088] FIG. 3 is a side view of part of the apparatus according to the present invention in use;

[0089] FIG. 4 is a rear view of part of the apparatus according to the present invention in use;

[0090] FIG. 5 is a side view of the separator according to the present invention;

[0091] FIG. 6 is a perspective view of a filter element according to the present invention

[0092] FIG. 7 is a sectional view of a filter element according to the present invention.

[0093] FIG. 8 is a perspective view of an apparatus for separating and gathering two or more sheets of filtering material.

[0094] FIG. 1 shows a schematic overview of the process of the present invention.

[0095] Filtering material 104 is unwound from a reel 102 and advanced in a longitudinal direction L. The filtering material is a pre-cut sheet of paper filtering material comprising two individual sheets of paper filtering material wound onto the same reel 102. Each sheet has a width of 110 mm, a thickness of 85 m and a basis weight of 36 g/m.sup.2. The two sheets 104 advance together longitudinally in parallel. The longitudinal edge of one sheet abuts the longitudinal edge of the other sheet. It will be appreciated that more than two sheets of filtering material could be used, for example 3 or 4 or more sheets of longitudinally advancing filtering material. It will be appreciated that the two or more sheets of filtering material may be formed as part of the method of the invention. For example, a single sheet of filtering material could be advanced longitudinally and cut longitudinally into multiple sheets. It will be appreciated that a non-woven sheet material could also be used.

[0096] The advancing sheets of filtering material 104 are embossed by an embosser 106. The embosser 106 comprises a rotating roller comprising spikes which protrude from the outer surface of the roller. The advancing sheets of filtering material are drawn between the roller and a flat surface or between the roller and a second smooth roller (as shown in FIG. 1) and the embossing roller embosses the sheets of filtering material. The applicant has found that embossing the sheets of filtering material leads to a desired pressure drop and leads to a dense or compact visual end appearance.

[0097] The embossed sheets of filtering material are then advanced and flattened by a wire 108. The flattened sheets of filtering material are then separated by a separator in the form of a separator cone 110. The separated sheets of filtering material pass into a preliminary chamber 116, and the sheets remain separated as the two sheets are gathered together such that a recess is formed in the partially gathered rod of filtering material. The partially gathered rod of filtering material then passes into the gathering chamber 122 and one or more capsules are inserted into the recess in the partially gathered rod of filtering material by means of a capsule inserter 130 comprising a rotating wheel. The rod is then further gathered and condensed by the gathering chamber 122 to thereby close the recess and form a rod comprising a longitudinally extending core of filtering material and one or more additive release vessel within the core of filtering material.

[0098] The rod is advanced in the longitudinal direction and is wrapped with an outer wrapper, such as a plug wrap to form a wrapped rod. The rod is wrapped with an outer wrapper using techniques known in the art. Finally the wrapped rod is cut by a rod cutter 140 to form a filter element comprising a longitudinally extending core of filtering material comprising one or more additive release vessels located within the core of filtering material. The rod cutter is a standard rod cutter known in the art.

[0099] The gathering and capsule insertion steps and apparatus will now be described in more detail with reference to FIGS. 2 to 4 and 8.

[0100] The flattened tow 104 is advanced and before it enters the preliminary chamber 116 the two sheets are separated by the cone 110. The cone 110 comprises a first end 112 and a second end 114. The first end has a wider diameter than the second end such that the cone tapers longitudinally from the first end to the second end. The cone is formed from a metal.

[0101] As shown in FIGS. 3 and 4, the cone 110 separates the two sheets of filtering material as these enter the preliminary chamber 116.

[0102] The preliminary chamber 116 comprises an inlet 118 and an outlet 120. The inlet 118 has a larger diameter than the outlet 120 such that the preliminary chamber 116 tapers longitudinally from the inlet 118 to the outlet 120. The cone 110 is positioned partially within the preliminary chamber 116 such that part of the cone 110 protrudes out of and away from the inlet 118 of the preliminary chamber 116. The preliminary chamber 116 is formed from a metal.

[0103] The cone 110 is fixed within the preliminary chamber 116 by a mechanical support. Before the sheets of filtering material are drawn into the preliminary chamber 116, the sheets are separated by the cone 110. As the sheets of filtering material are drawn into the preliminary chamber 116, the sheets remain separated by the cone 110, but as the filtering material advances longitudinally, the gap between the sheets reduces as the diameter of the cone 110 reduces. At the same time, the filtering material is partially gathered by the inner surfaces of the preliminary chamber 116. As the diameter of the preliminary chamber 116 decreases, the filtering material is gathered and condensed to form a partially gathered rod of filtering material. The cone 110 prevents complete gathering of the filtering material and leads to the formation of a recess in the partially gathered rod off filtering material. The applicant has found that the cone 110 keeps the folds of the sheet material apart such that the capsule can be placed into the centre of the partially gathered filtering material, so leading to improved capsule positioning.

[0104] The partially gathered rod of filtering material is drawn into the gathering chamber in the form of gathering shoe 122. Gathering shoe 122 comprises an inlet 124 and an outlet (not shown. The inlet of the gathering shoe has a larger diameter than the outlet of the gathering shoe. The cross sectional diameter of the gathering shoe initially remains constant in a first section 126. In a second section 127 of the gathering shoe, the cross sectional diameter decreases such that the second section 127 is longitudinally tapered. A third section 128 has a constant cross sectional diameter. It will be appreciated that the gathering shoe may not include a third section 128. Positioned in a top surface of the gathering shoe is a longitudinally extending aperture which extends partially along the first section 126 and second section 127 of the gathering shoe. The aperture is configured to receive the capsule inserter wheel 130.

[0105] The capsule inserter wheel 130 is fed by a hopper (not shown).

[0106] The capsule inserter wheel is one known in the art. The capsule inserter wheel utilises a vacuum and air jet system to collect and insert the capsules into the longitudinally extending recess. In such a system, a first wheel (not shown) comprises a plurality of grooves spaced equidistantly around its cylindrical surface. A hopper, which contains the capsules, releases the capsules and the capsules are collected by the grooves in the first wheel. A vacuum pump applies suction to the grooves such that each groove collects a single capsule.

[0107] A second smaller wheel 130 is positioned beneath the first wheel. The second wheel 130 comprises a plurality of grooves spaced equidistantly around its cylindrical surface. The capsules collected by the first wheel are transferred to the second wheel 130. At the bottom of the travel path of a given groove on the first wheel, the suction applied to that groove stops, and the capsule is transferred by gravity to a corresponding groove on the second wheel. The capsules are retained in the grooves of the second wheel 130 by suction applied by a vacuum pump. The bottom part of the second wheel 130 is positioned within the aperture of the gathering shoe 122. At the bottom of the travel path of a given groove, the suction applied to that particular groove is stopped and is replaced by a jet of air directed at the capsule to thereby release the capsule into the longitudinally extending recess.

[0108] Alternative capsule inserter wheels could also be used and an alternative capsule inserter wheel configuration will now be described. The capsule inserter wheel has radially extending cylindrical recesses spaced equidistantly around its cylindrical surface. The base of each recess is formed by the free end of a plunger or piston. Each piston is resiliently biased by a spring radially towards the centre of the wheel, but is movable radially outwards against this spring bias to sweep through the recess and so positively eject its contents. Sequential operation of the pistons or plungers as the wheel rotates clockwise is effected by means of stationary cam surface which engages with the radially inner end of the pistons or plungers over a portion of their travel path.

[0109] As the inserter wheel rotates, each recess is filled with an individual frangible capsule from a hopper as the recesses pass around the top of their travel path. The pistons or plungers are operated by a cam surface to empty the capsules from the inserter wheel recesses, into the longitudinally extending recess of the advancing rod of partially gathered filtering material, at the bottom of the travel path of the recesses.

[0110] The aperture in the gathering shoe 122 enables the capsule inserter wheel to extend into the gathering shoe 122 and thereby insert one or more capsule into the recess within the rod of partially gathered filtering material. The rotational speed of the capsule inserter 130 and the longitudinal speed of the advancing rod of partially gathered filtering material is constant so the capsules are inserted into the rod of partially gathered filtering material at regular intervals and so are positioned at regular intervals within the core of filtering material. The presence of a recess in the partially gathered rod of filtering material aids the placement of the one of more capsules and improves the capsule positioning within the finished filter element.

[0111] Following capsule insertion, the partially gathered rod continues to advance longitudinally and is further gathered by the walls of the gathering shoe. As the internal diameter of the gathering shoe decreases, the partially gathered rod is further gathered and condensed such that the recess is closed and a longitudinally advancing rod comprising a longitudinally extending core of filtering material and one or more capsules is provided.

[0112] Further processing steps are carried out on the rod as described above with reference to FIG. 1.

[0113] FIG. 8 shows an apparatus for separating and gathering two or more sheets of filtering material. The apparatus includes the same structure and components as described above with reference to FIGS. 2 to 4, but the apparatus does not include a capsule inserter.

[0114] FIG. 5 shows a side view of the cone 110. As shown in FIG. 5, the cone has a first end 112 which has a larger diameter than the second end 114. A first section of the cone extending from the first end 112 of the cone has a constant diameter. A second section of the cone extends from the first section and has a diameter that decreases from the first end of the second section to the second end of the second section, such that the second section is tapered. A final third section extends from the second end of the second section and includes a narrower and constant diameter.

[0115] FIG. 6 is a perspective view of a filter element according to the invention.

[0116] The filter element 200 shown in FIG. 6 comprises a longitudinally extending core of filtering material 202 formed from two sheets of paper filtering material having a basis weight of 36 g/m.sup.2, a thickness of 85 m and each sheet having a width of 110 mm. The core 202 comprises a capsule 204 positioned centrally within the core. The capsule is a frangible capsule containing 2.5 g of menthol in an oil carrier. The capsule has a diameter 3.35 mm. The filter element 200 also includes a paper plug wrap 206 which surrounds the core and is secured by a lapped and stuck seam as is known in the art. The filter element has a circumference of 24 mm and a length of 27 mm.

[0117] FIG. 6 shows a perspective sectional view of the filter element 200 shown in FIG. 5. FIG. 6 illustrates the structure of the capsule 204 which includes a capsule shell 208 comprising gelatine, and a liquid menthol flavourant solution 210 within the capsule shell. It will be appreciated that other flavourants may be contained in the capsule 204.

[0118] The filter element shown in FIGS. 5 and 6 may be made according to the method described above with reference to FIGS. 1 to 4.

[0119] The filter element 200 shown in FIGS. 5 and 6 may be joined to a wrapped tobacco rod (not shown) to form a filtered smoking article, such as a filtered cigarette. The filter element 200 may be joined to the wrapped tobacco rod by ring tipping paper, in which the tipping paper engages around only the adjacent ends of the filter element and wrapped tobacco rod to thereby leave some of the plug wrap 206 exposed. Alternatively, the filter may joined by a full tipping overwrap which engages around the entire length of the filter element and the adjacent end of the wrapped tobacco rod.