Filtered Cigarettes

Abstract

A filtered cigarette in which the inner end of the filter is tapered so that there is a variable drawing resistance along different longitudinal planes of the filter and in which the space between the tobacco and the inner end of the filter provides a chamber in which the tobacco smoke may be cooled; additionally, there is a relatively even draw resistance throughout the entire smoking cycle.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to filtered cigarettes and filters therefor and, particularly, to filters allowing air mixing in such filtered cigarettes.

2. Description of the Prior Art

The increasing death rate resulting from vascular disorders, lung cancer and cancer of the upper respiratory tract is known to both the medical profession and the general public. While to some extent, it is unquestionable that this increase is due in part to the overall environmental conditions caused by a highly advanced technological society, the results of recent scientific investigation together with statistical evidence have shown that there is a connection between smoking and vascular disorders and lung cancer. It is widely recognized that the cancer-causing agents or carcinogens are present in the tobacco tar and nicotine from burning tobacco and that these carcinogens are carried to the smoker's respiratory tract in the tobacco smoke.

Many previous attempts have been made to protect smokers against the health hazards of smoking, including a variety of mechanical and chemical means for incorporation into cigarettes, cigarette and cigar holders, tobacco pipes and the like with a view to extracting from the tobacco smoke at least a proportion of the harmful substances.

However, most of the previous attempts have failed to take into account two important factors, namely, firstly that tobacco smoke is at a high temperature by virtue of the combusion temperature (viz. 800.degree.C. or more) of the tobacco, and any enveloping material, e.g., cigarette paper (often impregnated with chemical products to sustain burning) and, secondly that the tobacco smoke is low in oxygen, most of the oxygen of the air used in the combustion having been converted to carbon monoxide and carbon dioxide. It is apparent that the high temperature and the low oxygen content of the tobacco smoke entering the mouth, respiratory tract and lungs of a smoker enhance the dangers of or indeed cause the observed deleterious effect of tobacco smoke. Even those prior art filtering devices which did combine cooling of the tobacco smoke by air mixing with filtration did not provide the ease of manufacture and economy of the filtering device of the present invention.

In the machines presently used in the production of filtered cigarettes 1,200 to 2,000 cigarettes are produced each minute, and the expectation is that this rate can be increased to 4,000 cigarettes per minute. The filter material fed into the machine is of a length calculated to provide four or six cigarettes in one operation; the older machines making four and the newer six. In either case, whether four or six cigarettes are produced in each operation, the process of production is the same.

To maintain the speed of production it is impossible to incorporate additional elements, such as the elastic tape in U.S. Pat. No. 3,547,132 to Beam or U.S. Pat. No. 3,526,230 to Rosen or the insert member in U.S. Pat. No. 3,602,232 to Grauvogel, et. al.

Furthermore, it would not be possible to use high speed production with the filter material cut as shown in figure 1 of the Beam patent because the elastic tape would alternately point in different directions.

SUMMARY OF THE INVENTION

The filtering device of the present invention overcomes the above objections and difficulities by providing a filtering device having a flow restricting orifice which gives a relatively even mixture of air and smoke throughout the entire smoking cycle, without requiring any manipulation of the filtering device or of the cigarette by the smoker. In fact, it is a distinct advantage of the filtering device of the present invention that a cigarette may be produced using conventional cigarette manufacturing equipment without any significant modifications and at no additional cost to that of a regular filter cigarette, and without affecting the rate of production.

According to one aspect of the present invention, there is provided a cigarette having a tobacco section having an upstream end (to be ignited during the smoking cycle) and a downstream end; and a tobacco smoke filter in flow communication with the tobacco section. The tobacco smoke filter has an inner end which abuts the downstream end of the tobacco section and a mouthpiece end. The inner end is tapered or slanted on one or more surfaces to present one or more surfaces having a cross-sectional area which is gradually reduced from the point where the tapering or slant begins to a minimum surface area at the inner end. A wrapper connects the tobacco smoke filter and the tobacco section and defines a mixing chamber disposed between the tobacco section and the tobacco smoke filter. The tapered surface or surfaces provides a variable drawing resistance along different longitudinal planes of the filter so that smoke is constrained to flow first through the plane or planes of least drawing resistance (the plane or planes of shortest length from the mouthpiece end to the inner end) and then, as the shortest plane(s) become saturated with tar and nicotine, progressively through planes of increasing draw resistance, i.e., planes of increasing longitudinal length.

Viewed from another aspect, the invention provides a cigarette incorporating one or more air ducts in the cigarette wrapper so disposed and formed that, when the smoking means are being used, suction by the smoker in the usual way causes supplementary air, that is, air that has not passed through the burning portion of the tobacco being smoked to be drawn through the duct or ducts into an air mixing chamber where the supplemental air mixes with tobacco smoke and through a tobacco smoke filter into the mouth of the smoker simulataneously with the tobacco smoke, such supplementary air serving both to lower the temperature of the tobacco smoke and to enrich it with oxygen, such tobacco smoke filter providing a variable drawing resistance. Alternatively, an air permeable wrapper might be used, supplementary air being drawn into the air mixing chamber through the pores of the wrapper.

Conveniently, the variable drawing resistance is provided by having a filter of substantially uniform density, but having an inner end portion, that is, the end furthest from the smoker's mouth and closest to the tobacco end, of reduced cross-section, as compared to the rest of the filter. The inner end portion of the filter may carry a stepped surface or surfaces or a curved surface or surfaces but preferably it carries a planar slanted surface(s) which tapers from a point or loci of points intermediate the ends of the tobacco smoke filter.

In the production of the filtered cigarettes of the present invention an elongated filter is cut into two or three sections with one or two knives respectively; the knife or knives are slanted with respect to the longitudinal axes of the elongated filter. Each of these cut filter sections are inserted into the cigarette wrapping machine between tobacco sections and is then further cut to produce either four or six cigarettes in each cycle of production.

It is therefore an object of the present invention to provide a filtered cigarette which will serve to reduce or minimize the dangers arising from smoking tobacco and other combustible materials and which does not necessitate to any noticeable extent a change in the appearance and size of conventional cigarettes, the filtered cigarette being satisfactory from an operative and economical aspect.

It is a further object of the present invention to provide in a filtered cigarette, for the purpose of reducing or minimizing the dangers inherent in smoking, an air mixing chamber for lowering the temperature of the tobacco smoke and to enrich it with oxygen and a flow restrictive filter which does not require any effort on the part of the smoker to achieve the flow restricting properties of the filter and which will ensure a relatively even mixture of tobacco smoke and supplemental air throughout the smoking cycle.

It is still a further object of the present invention to provide smoking means incorporating in a cigarette having an air mixing chamber in which smoke from the burning portion of the tobacco is mixed with supplemental air drawn into the air mixing chamber through one or more ducts, a flow restrictive filter carrying near its inner end, that is, the end furthest from the smoker's mouth and closest to the tobacco section, a surface or surfaces, each of such surfaces being tapered or slanted with respect to the path of flow of the tobacco smoke both before and after the tobacco smoke is mixed with the supplemental air in the air mixing chamber.

It is a still further object of the present invention to provide in a cigarette a conventional cylindrical tobacco smoke filter of uniform density carrying near its inner end one or more slanted or tapered surfaces with respect to the longitudinal axis of the filter, such tapered surface of the filter defining, along with the tobacco portion and the connecting wrapper of the cigarette, an air mixing chamber in which tobacco smoke and supplemental air are mixed prior to impinging on each tapered or slanted surface or surfaces of the inner end of the filter, the supplemental air being drawn into such air mixing chamber through one or more ducts provided in the connecting wrapper each duct being in flow communication between the air mixing chamber and outside atmosphere or alternatively through an air permeable connecting wrapper.

Still other objectives of the present invention will become apparent in connection with the following descriptions and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view of the filtered cigarette of this invention using the filter shown in FIG. 3.

FIG. 2 shows a sectional view of a different embodiment of the filtered cigarette of this invention using the filter shown in FIG. 4.

FIG. 3 shows a sectional view of one embodiment of a cigarette smoke filter which can be used in the filtered cigarette of this invention.

FIG. 4 shows a sectional view of a second embodiment of a cigarette smoke filter which can be used in the filtered cigarette of this invention.

FIG. 5 shows a sectional view of a different embodiment of the filtered cigarette of FIG. 1.

FIGS. 6, 7 and 8 each show sectional views of other embodiments of a tobacco smoke filter which can be used in the filtered cigarette of this invention.

FIG. 9 shows the prior art method of cutting cigarette filters.

FIG. 10 shows a method of cutting the cigarette filters of the present invention.

FIG. 11 shows an assembly of the filtered cigarettes of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The cigarette of the present invention contains in flow communication a tobacco section having an upstream end and a downstream end and a filter element having an inner end abutting the downstream end of the tobacco section, wherein the tobacco smoke filter carries a surface or surfaces near its inner end, each of such surfaces being slanted with respect to the path of flow of tobacco smoke within the cigarette (the path of the tobacco smoke generally following the longitudinal axis of the cigarette); a space between the tobacco and the slanted surfacels) defining an air mixing chamber; a wrapper containing the tobacco and filter and further defining the air mixing chamber; and a duct or ducts each in the form of a hole or aperture leading from the outside of the wrapper into the chamber so that when the cigarette is in use, air is drawn through each vent and mixes with smoke from the burning tobacco before passing through the filter and finally reaching the smoker's mouth.

According to a further feature of the invention, an additional filter element is located adjacent to and at the downstream end of the tobacco section thereby providing a preliminary filtering action of the tobacco smoke prior to the mixing of the tobacco smoke and supplementary air drawn through vents in the wrapper into the air mixing chamber which is disposed between the additional filter element and the downstream filter element.

The cigarette 5 shown in FIG. 1 has a wrapper 16 containing tobacco T and filter F, the filter carrying an inclined surface S near the inner end 11 which abuts the downstream end 9 of the tobacco section T, forming air mixing chamber C disposed between tobacco T and filter F. Air vents 8 in the form of radial holes are so located as to place the air mixing chamber C in flow communication with the outside atmosphere, the air vents being provided, for example, by piercing the wrapper 16, either before or after assembly of cigarette 5. Instead of, or in addition to, providing air vents in the cigarette wrapper it is also possible to use an air permeable cigarette paper through which supplemental air may be drawn into the air mixing chamber. The cigarette is ignited at its upstream end 2 containing tobacco T and the smoker inhales at the mouthpiece end 3 through tobacco smoke filter F.

During the process of smoking the cigarette thus described, as the smoker draws on the cigarette, smoke is drawn from the point of combustion at the upstream end 2 along the tobacco T into the passage or air mixing chamber C while simultaneously supplementary air is drawn through one or all of the air vents or perforations 8 into air mixing chamber C where the smoke and supplementary or fresh air are mixed prior to impinging on inclined or tapered surface S of filter F.

The suction required to draw air through the tobacco from the point of combustion at 2 to the downstream end of the tobacco 9 depends on the resistance provided by the tobacco which, in turn, for a given cross-sectional area and tobacco density, depends on the length of tobacco through which the air is to be drawn. Similarly, the drawing resistance of the tobacco smoke filter F is also dependent on the length of the filter and consequently, the force of suction will be strongest (i.e., least draw resistance) at the shortest longitudinal plane 12-12' of the filter F. Therefore, during the process of smoking the smoke and air from air mixing chamber C will initially be constrained to flow towards the narrow end 12 of the tobacco smoke filter F. This narrow end acts as a flow restricting orifice, bringing about the perfect mixture of smoke with air, highly intensified filtering and a relatively constant ratio of smoke to air. As the smoking process continues, the narrow end 12 becomes congested with tars and the flow of air and smoke will proceed, step by step, along the tapered surface S toward the longest longitudinal plane 11-11'. The increased draw resistance through the filter results in less supplemental air being drawn through the vents into the mixing chamber; this effect is compensated for since the length of tobacco will have decreased, thereby decreasing its draw resistance. It should be noted however, that the drawing resistance of the tobacco section T decreases relatively rapidly and therefore, to maintain a proper balance of smoke and supplemental air during the smoking cycle the flow of supplemental air through the filter F must not decrease as rapidly. This will, to some extent, result naturally, since the congested filter will present a greater barrier to the smoke, which is loaded with tars and nicotine, than to the supplemental air which is much thinner. It is thus readily apparent that by proper selection of the angle or surface area of the tapered surface S of the tobacco smoke filter F the increased draw resistance through the tobacco smoke filter will be compensated for by the decreased draw resistance of the tobacco section, thereby ensuring that the mixture of smoke and fresh air will remain relatively constant throughout the smoking cycle.

FIG. 3 shows the tobacco smoke filter F of the cigarette 5 of FIG. 1. The filter is constructed using conventional cigarette filter material 25 and has a relatively uniform density throughout its length. The filter can be cut from cylindrical stock and may be provided with a wrapper 26. The inner face of the filter, denoted generally at S, is tapered from the point 12 located on the outer surface of the filter intermediate the mouthpiece end 3 and the inner end at 11, such tapering extending to the point 11 on the inner end. This tapered surface can be conveniently formed by slicing or cutting a cylindrical filter element at an angle to the longitudinal axis 28 of the filter element. The cross-sectional area of the tobacco smoke filter, looking in the direction of the longitudinal axis 28, is seen to gradually decrease along planes perpendicular to the longitudinal axis from the point 12 to the inner end at 11.

Referring now to FIGS. 10 and 11 the steps for producing the filtered cigarettes of the present invention (using a six cigarette per cycle cigarette wrapping machine) are shown. FIG. 9 shows conventional cylindrical filters formed from cigarette filter material 25 having a relatively uniform density throughout its length cut into three sections. FIG. 10 shows the method of formation of the preferred embodiment of the filters of the present invention, forming three sections of filter material F1, F2, F3, using tilted cutting edges K. Each of the sections F1,F2, F3, services two cigarettes as shown in FIG. 11.

FIG. 11 shows the filter sections F1, F2 and F3 of FIG. 10 disposed between tobacco sections T ready to be cut into six cigarettes each having a mixing chamber C. It is thus readily apparent that (according to the present invention) the production of filtered cigarettes having a tobacco section T, an air mixing chamber C and a tobacco smoke filter F having a slanted inner surface S can be accomplished without making any changes of equipment and without impairing the speed of production of cigarette wrapping machines.

FIG. 2 shows a filtered cigarette as in FIG. 1 with the difference that the filter F' shown in FIG. 4 is used instead of the filter F shown in FIG. 3.

The filter F' of FIG. 4 is tapered at its inner face 30 on the two diverging surfaces 31 and 32 which intersect each other in a common edge 33-33' at or near the longitudinal axis 28 of the filter. The tapering of each of the diverging inner surfaces 31 and 32 thus begins at the loci of points 33-33' on or near a plane containing the longitudinal axis and continues to the points 34 and 35 respectively on the inner end of the filter.

The operation of the filtered cigarette in FIG. 2 is substantially identical to the filtered cigarette in FIG. 1 except that the mixture of supplemental air and tobacco smoke first impinges the filter at the shortest longitudinal plane through 33-33' and as the narrow end at 33-33' of the surfaces of the inner end becomes congested with tars and nicotine, the flow of air and smoke will proceed, step by step, along the tapered surfaces 31 and 32 toward the points 34 and 35 respectively on the inner end 30.

Fig. 5 shows a cigarette as in FIG. 1 with the addition of a second filter 18 to provide additional filtering action. The insertion of a second filter as at 18 does not, of course, change the manner of operation or the arrangement as shown in FIG. 1. Of course, an additional filter element can also be similarly placed in the filtered cigarette shown in FIG. 2. FIGS. 6 - 8 show alternative embodiments of the basic filter F, each of which may be used in the filtered cigarettes shown in FIGS. 1, 2 or 5. FIG. 6 shows a filter 20 carrying tapered surfaces 21 and 22 near its inner end whereby the shortest longitudinal planes are on the outside surface of the filter and the longest longitudinal plane intermediate the two shortest planes. FIG. 7 shows a filter 23 carrying at its inner end a conical surface 36, with the summit ending in a point 37. FIG. 8 shows a filter 24 similar to filter 23 except that the pointed end is cut off to provide additional initial surface area 38. Each of filters 20, 23 and 24 can be used in place of filter F as shown in FIGS. 1 or 5 without modifying the basic concept of the present invention.

In addition to the aforementioned advantages, the filters shown in FIGS. 3 and 4 will strengthen the walls 19 of the air mixing chamber 10.

The foregoing description is considered as illustrative only of the principles of this invention. Other modifications and changes will be apparent to those skilled in the art and is therefore not desired to limit the invention to the exact construction and operation as shown and described and, accordingly, many modifications and equivalents are commensurate with the scope of this invention as claimed.

Claims

What is claimed is:

1. A filtered cigarette comprising

a. a tobacco section of cylindrical configuration having an upstream end and a downstream end;

b. a tobacco smoke filter of substantially uniform density having an upstream end and a mouthpiece end which is perpendicular to the flow of tabacco smoke through the filter;

c. a wrapper encircling said tobacco section and said filter, said wrapper having apertures immediately adjacent said downstream end of said tobacco section and circumferentially arranged about said wrapper through 360.degree.; the upstream end of said filter being disposed along a single inclined plane, the forwardmost portion of which is immediately adjacent the apertures of said circumferential ring, and rearmost portion of which is significantly displaced from said circumferential row of apertures at a point 180.degree. from one of said apertures, the inclined upstream end of said filter forming with said downstream end of said tobacco section and said wrapper an air mixing chamber whereby air can be drawn into said air mixing chamber to mix with the tobacco smoke and tars and nicotine will deposit on said inclined plane progressively from said rearmost portion to said forwardmost portion.

2. A filtered cigarette comprising

a. a tobacco section of cylindrical configuration having an upstream end and a downstream end;

b. a tobacco smoke filter substantially uniform density having an upstream end and a mouthpiece end which is perpendicular to the flow of tobacco smoke through the filter;

c. an additional cylindrical filter element disposed between said downstream end of said tobacco section and said upstream end of said tobacco smoke filter; and

d. a wrapper encircling said tobacco section and said filter, said wrapper having apertures disposed between said additional cylindrical filter element and said upstream end of said tobacco smoke filter and circumferentially arranged about said wrapper through 360.degree.;

said upstream end of said filter being disposed along a single inclined plane,

the forwardmost portion of which is adjacent the additional cylindrical filter element and rearmost portion of which is significantly displaced from said forwardmost portion at a point approximately 180.degree. from said forwardmost portion;

said downstream end, said inclined plane, and said wrapper forming an air mixing chamber;

said apertures being substantially completely in flow communication between said air mixing chamber and said outside atmosphere,

whereby air can be drawn into said air mixing chamber to mix with the tobacco smoke, and tars and nicotine will deposit on said inclined plane progressively from said rearmost portion to said forwardmost portion.