HU188419B - Tobacco smoke filter particularly for cigarettes - Google Patents

Abstract

A filter for a smoking article such as a cigarette, comprising several grooves (2) of varying depth between a shallow inlet end (3) and a deep outlet end (4) thereof, the outlet end face (8) being air permeable to an extent greater than are the floor (7) or the sides of each groove (2). A tipping (5) enwrapping the filter plug (1) has ventilation perforations (6) in the region of the inlet end of each groove. Alternatively, the grooves may have their median axes in a plane which is perpendicular to the axis of the filter plug, whereby the grooves extend circumferentially of the filter plug between the shallow inlet ends and the deep outlet ends. <IMAGE>

Description

The proposed tobacco smoke filter has a rod-shaped filter insert having at least one air-guiding groove along its circumference. The point of the proposal is that this air guide groove (2) is of increasing depth from the inlet (3) to the outlet (4). Further, the groove (2) also has a longitudinal component transverse to the longitudinal axis of the filter cartridge, i.e. preferably of helical configuration or perpendicular to the longitudinal axis of the filter cartridge. The groove (2) has an air-permeable surface (8) at its outlet. (Figures 1 and 2).

Figure 1

Figure 2

188,419

The present invention relates to a tobacco smoke filter which is particularly applicable to cigarettes.

Smoke filter cigarettes are known which are provided with a ventilation unit through which ventilation air can enter the smoke filter. This is to achieve the aim of reducing the proportion of smoke components in the smoke stream, i.e. the main stream. Such a solution is described, for example, in U.S. Patent No. 1,571,114. British Patent No. 620,578; Swiss Patent Specification. The former has helical grooves with a constant cross-section on the peripheral surface of the smoke filter, while the latter has an annular space in the middle section of the smoke filter. With these suggestions, a part of the smoke stream may mix with the ventilation air currents. It has also been observed that when ventilation air is introduced into the filter insert made of fibrous filter material through the surrounding topsheet, the inflow air forces the flow of smoke into a central section of the filter insert. This relatively narrow stream of smoke can pass undisturbed into the smoker's mouth.

No. 4,273,141. The tobacco smoke filter of U.S. Pat. No. 4 is provided with recesses or annular space in its central region which passes through the perforations of the topsheet to the outside air space. However, in these recesses or annular spaces, the smoke stream is in contact with the venting air stream, such that, in some of the proposed embodiments, the smoke stream in the central section of the filter may pass undisturbed into the smoker's mouth.

It is an object of the present invention to provide an improved tobacco smoke filter which allows a wide range of ventilation air to be introduced into the smoke filter so that the smoke stream passing through the filter insert is completely mixed with the air.

In order to accomplish this object, we have started with a smoke filter which is provided with a filter insert having at least one air-conducting groove along its circumference. A further development, i.e. the essence of the invention, is that the air inlet groove is of increasing depth from the inlet to the outlet, the air inlet groove also has a directional component transverse to the longitudinal axis of the tobacco smoke filter and the air inlet groove is air permeable.

Due to the transverse directional component of the air-guiding grooves, the air that is separately guided in and out of the grooves will flow transversely into the smoke filter, so that the longitudinal smoke flow and the transverse air currents intersect, i.e. the smoke flow cannot run parallel to the air flows. As the air guide grooves deepen in the direction of their outlet, the outlet cross-section thereof increases, and consequently the cross-section of the transverse air currents increases. Since the air guide grooves of the invention have an air-permeable surface at the outlet, only the air currents can pass through the smoke filter here. Through the above measures, the smoke stream passing through the smoke filter is fully contacted and effectively mixed with the transverse air currents. This significantly improves the ventilation of the smoke stream inside the smoke filter.

Preferably, the groove is of helical shape and its inlet and outlet are at a different distance from the suction end of the tobacco smoke filter. However, it is also possible according to the invention that the groove inlet and outlet are equidistant from the suction end.

DETAILED DESCRIPTION OF THE INVENTION The invention will now be described in more detail with reference to the drawings, which illustrate two exemplary embodiments of the present invention. In the drawing:

Figure 1 is a side view of a tobacco smoke filter according to the invention with helical air guide grooves;

Figure 2 is a sectional view taken along line II-II in Figure 1;

Figure 3 is a sectional view, partly in section, of a cigarette with the tobacco smoke filter of Figure 1;

Fig. 4 is a sectional view of another exemplary embodiment of a tobacco smoke filter according to the invention;

Figure 5 is a sectional view taken along line V-V in Figure 4.

The tobacco smoke filter 1 of Figure 1 is made of a filter material known per se, such as fibrous cellulose acetate, and is provided with helical grooves 2 along its circumference. The cross-section of the grooves 2 is clearly shown in Figure 2. It can be clearly seen here that the depth of the groove 2 gradually increases from the inlet 3 to the outlet 4.

The tobacco smoke filter 1 is secured to the cigarette paper wrapped tobacco rod by a cover 5 (not shown in Figure 2), which is otherwise connected to the tobacco smoke filter on the right side. The cover 5 is provided with a perforation 6 which is circumferentially located in the groove 3 inlet region. The apertures of the perforation 6 are configured so that at least one of them passes through each groove 2.

The grooves 2 may be formed, for example, by treating the filter rod by a hot melting process, for example as taught in British Patent No. 1,507,765, using a suitable molding device. By selecting the parameters of the hot forming process, the grooves 2 are formed such that its longitudinal bottom surface 7 is air-tight but the end-plate-like surface 8 is air-permeable.

When smoking a cigarette with a tobacco smoke filter according to Figures 1 and 2, ambient air enters the grooves 2 through the perforation 6. As the grooves 2 form helical passages and their depth increases in the direction of flow, the ventilation air enters through the air permeable surfaces 8 into the interior of the tobacco smoke filter 1 with a helical and inward swirling motion. This results in an increased mixing of the ventilation air with the smoke stream passing through the tobacco smoke filter.

3, the tobacco rod 10 is wrapped in cigarette paper 11 and the tobacco smoke filter 12 has a filter insert 13 which is secured to the tobacco rod 10 by a wrap 14. The rod-21

188 419 shaped filter insert 13 is similar to the one shown in Fig. 1, except that in addition to the helical grooves 15 it is provided with longitudinal grooves 16 flowing into the suction end.

Like the grooves 2 in Figures 1 and 2, the longitudinal bottom surface of the grooves 15 is substantially airtight. The same applies to the longitudinal grooves 16. In this embodiment, perforations 17 and 18 are provided which are circumferentially spaced apart in the inlet region of the grooves 15 and 16 and serve as inlets for the venting air.

Optionally, the filter cartridge 13 may consist of two interconnected cylindrical pieces, one of which has grooves 15 and the other of the grooves 16.

When the cigarette of Fig. 3 is sucked in, the first stream of ventilation air enters the filter cartridge 13 through the grooves 15 thereby causing the incoming air to swirl and mix intimately with the tobacco smoke. The other stream of ventilation air through the grooves 16 enters the smoker's mouth substantially separately from the smoke stream.

The tobacco smoke filter shown in Figure 4 has a filter insert 20 having grooves 21 along its circumference. These grooves 21 are configured such that their outlets and inlets are transverse to the longitudinal centerline of the filter cartridge. As shown in Figure 5, the depth of the grooves 21 increases towards the outlet. Again, the end face 22 forming the end wall of the grooves 21 is air-permeable. The other surfaces of the grooves 21, on the other hand, are airtight.

The filter insert 20 is secured to your tobacco (not shown) by a cover 23 provided with a micro-perforation 24 surrounding the filter insert in a circumference of the grooves 21.

When such a cigarette is sucked in, the ventilation air enters the grooves 21 through the micro-perforation 24. From there, the air passes through the face surfaces 22 into the filter cartridge and is mixed in a spiral motion with the tobacco smoke.

In any of the above embodiments, the venting perforations may be formed as microperforated portions of each section of the casing.

The cover may optionally surround the air-permeable topsheet of the filter cartridge. In this case, the casing may be formed as an outer barrier layer in which the perforations are formed. Of course, the cover 5 is longer than the top of the filter cartridge.

It should be noted that the perforations 6, 17 and 18 shown in the drawing are of a relatively larger scale for the purpose of illustration.

Patent claims

Claims (10)

A tobacco smoke filter, in particular for cigarettes, having a rod-like filter insert having at least one air passage groove along its circumference, characterized in that the air passage groove (2; 15; 21) is of increasing depth from the inlet (3) to the outlet (4). 2; 15; 21) also has a directional component transverse to the longitudinal axis of the tobacco smoke filter, and the air passage groove (2; 15; 21) is provided with an air-permeable surface (8 or 22) at its outlet. Tobacco smoke filter according to claim 1, characterized in that the inlet (3) of the groove (2; 15) is further away from the suction end of the tobacco smoke filter (4). Tobacco smoke filter according to Claim 2, characterized in that the air-conducting groove (2; 15) is in the form of a helix. ' Tobacco smoke filter according to claim 1, characterized in that the inlet and outlet of the groove (21) are at a distance from the suction end of the filter cartridge. 5. Tobacco smoke filter according to any one of claims 1 to 3, characterized in that the groove (2) has a lower surface (7) and its side surfaces which are less permeable to air than the outlet surface (8). 6. A tobacco smoke filter according to any one of claims 1 to 3, characterized in that the cover (5; 14; 23) covering the tobacco smoke filter is air-permeable at least in the region of the inlets of the grooves (2; 15; 21). 7. Tobacco smoke filter according to any one of claims 1 to 3, characterized in that it has longitudinal auxiliary air guide grooves (16) which extend to the suction ends of the filter insert and terminate in front of the filter insert part which includes the grooves (15). A tobacco smoke filter according to claim 7, characterized in that the casing (Hja) has a first vent perforation (17) in the inlet region of the grooves (15) and a second vent perforation (18) in the inlet region of the longitudinal grooves (16). A tobacco smoke filter according to claim 8, characterized in that the perforations (17, 18) are formed as micro-perforations of the casing (14). 10. Tobacco smoke filter according to any one of claims 1 to 3, characterized in that the filter insert comprises two interconnected cylindrical sections, one of which is provided with at least one groove (15) and the other with longitudinal air guide grooves (16). 5 pieces of figure Published by the National Office of Inventions Responsible for publishing: Zoltán Hímet, Head of Department, Collected by the Printing Foam Collection (877648/09) 87—1775 Dabasi Printing House, Budapest — Dabas Chief Executive Officer: Csaba Bálint Director