AEROSOL GENERATING ARTICLE WITH DIRECTING ELEMENT

Abstract

An aerosol-generating article is provided, including: a heat source; an aerosol-forming substrate downstream of the heat source; an airflow-directing element downstream of the substrate, the airflow-directing element including an air-permeable segment defining a cavity; at least one air inlet to allow air to be drawn into the article; and first and second airflow pathways, in which the first airflow pathway extends from the air inlet, through the substrate, and into a distal end of the cavity, in which the second airflow pathway extends from the air inlet, through the air-permeable segment, and into the cavity at a point downstream of the distal end of the cavity, in which the air inlet is located downstream of the distal end of the airflow-directing element, and in which a longitudinal cross-sectional area of the cavity is at least 30 percent of a total longitudinal cross-sectional area of the article.

Claims

1.-12. (canceled)

13. An aerosol-generating article, comprising: a heat source; an aerosol-forming substrate downstream of the heat source; an airflow-directing element downstream of the aerosol-forming substrate, the airflow-directing element comprising an air-permeable segment, the air-permeable segment defining a cavity; at least one air inlet configured to allow air to be drawn into the aerosol-generating article; a first airflow pathway; and a second airflow pathway, wherein the first airflow pathway extends from the at least one air inlet, through the aerosol-forming substrate, and into a distal end of the cavity, wherein the second airflow pathway extends from the at least one air inlet, through the air-permeable segment, and into the cavity at a point downstream of the distal end of the cavity, wherein the at least one air inlet is located downstream of the distal end of the airflow-directing element, and wherein a longitudinal cross-sectional area of the cavity is at least 30 percent of a total longitudinal cross-sectional area of the aerosol-generating article.

14. The aerosol-generating article according to claim 13, wherein the air-permeable segment comprises a material having a density of at least 0.05 milligrams per cubic millimetre.

15. The aerosol-generating article according to claim 13, wherein the at least one air inlet is located no more than 3 millimetres downstream of the distal end of the airflow-directing element.

16. The aerosol-generating article according to claim 13, wherein the first airflow pathway extends from the at least one air inlet, through the air-permeable segment, through the aerosol-forming substrate, and into the distal end of the cavity.

17. The aerosol-generating article according to claim 13, wherein the second airflow pathway extends from the at least one air inlet, through the air-permeable segment, and directly into the cavity at a point downstream of the distal end of the cavity.

18. The aerosol-generating article according to claim 13, wherein the at least one air inlet is located no more than 5 millimetres downstream of the distal end of the airflow-directing element.

19. The aerosol-generating article according to claim 13, wherein a downstream end of the aerosol-forming substrate abuts an upstream end of the airflow-directing element.

20. The aerosol-generating article according to claim 13, wherein the air-permeable segment is a cylindrical air-permeable segment and the cavity is a cylindrical cavity.

21. The aerosol-generating article according to claim 13, wherein the cavity has a circle shaped cross-section, or a square shaped cross-section, or a cloverleaf shaped cross-section.

22. The aerosol-generating article according to claim 13, wherein a longitudinal cross-sectional area of the cavity is less than or equal to 40 percent of a total longitudinal cross-sectional area of the aerosol-generating article.

Description

[0135] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0136] FIG. 1 shows a schematic longitudinal cross sectional view of an aerosol generating article according to the present invention where the at least one air inlet is located downstream of the distal end of the airflow directing element;

[0137] FIG. 2 shows a schematic longitudinal cross sectional view of an alternative aerosol generating article according to the present invention where the at least one air inlet is located downstream of the distal end of the airflow directing element.

[0138] FIG. 3 shows a schematic longitudinal cross sectional view of an aerosol generating article according to the present invention where the at least one air inlet is located upstream of the distal end of the airflow directing element.

[0139] FIG. 4 shows the results of a test to determine how the mass of glycerine remaining in the aerosol-forming substrate after use of an aerosol generating article varied as a function of the cross sectional area of the cavity.

[0140] FIG. 5 shows the results of a test to determine how the mass of glycerine adsorbed by the air-permeable portion of the airflow directing element after use of an aerosol generating article varied as a function of the cross sectional area of the cavity.

[0141] The aerosol generating article 100 according to the first embodiment of the invention shown in FIG. 1 comprises a blind combustible carbonaceous heat source 102, an aerosol-forming substrate 104, an airflow directing element 106, and a mouthpiece 110 in abutting coaxial alignment. The combustible carbonaceous heat source 102, aerosol-forming substrate 104, airflow directing element 106, and mouthpiece 110 are overwrapped in an outer wrapper 112 of cigarette paper of low air permeability.

[0142] The aerosol-forming substrate 104 is located immediately downstream of the combustible carbonaceous heat source 102 and comprises a cylindrical plug 114 of tobacco material comprising glycerine as aerosol former and circumscribed by plug wrap (not shown). A non-combustible, substantially air impermeable barrier is provided between the downstream end of the combustible heat source 102 and the upstream end of the aerosol-forming substrate 104. As shown in FIG. 1, the non-combustible, substantially air impermeable barrier consists of a non-combustible, substantially air impermeable, barrier coating 118, which is provided on the entire rear face of the combustible carbonaceous heat source 102.

[0143] A heat-conducting element 120 consisting of a tubular layer of aluminium foil surrounds and is in direct contact with a rear portion 122 of the combustible carbonaceous heat source 102 and an abutting front portion 124 of the aerosol-forming substrate 104. As shown in FIG. 1, a rear portion of the aerosol-forming substrate 104 is not surrounded by the heat-conducting element 120.

[0144] The airflow directing element 106 is located downstream of the aerosol-forming substrate 104 and comprises an air-permeable segment 128 defining a cavity 129. The air-permeable segment 128 comprises substantially uniformly distributed cellulose acetate tow. The cavity 129 is provided along the central longitudinal axis of the air-permeable segment 128. The longitudinal cross sectional area of the cavity 129 is 20 percent of the total cross sectional area of the aerosol generating article 100. Both the distal end and the proximal end of the cavity 129 are open such that air may pass into the distal end of the cavity 129, pass along the length of the cavity 129, and pass out of the cavity 129 through the proximal end of the cavity.

[0145] As shown in FIG. 1, the air-permeable segment 128 is circumscribed by an inner wrapper 130.

[0146] As also shown in FIG. 1, at least one air inlet 132 is provided in the outer wrapper 112 and the inner wrapper 130. The at least one air inlet 132 comprises a plurality of air inlets in a circumferential arrangement around the aerosol generating article. In the aerosol generating article 100 shown in FIG. 1, the at least one air inlet 132 is located 3 millimetres downstream of the distal end of the airflow directing element 106.

[0147] The mouthpiece 110 of the aerosol generating article 100 is located downstream of the airflow directing element 106 and comprises a cylindrical plug 136 of cellulose acetate tow of very low filtration efficiency circumscribed by filter plug wrap 138. The mouthpiece 110 may be circumscribed by tipping paper (not shown).

[0148] In use, once the combustible carbonaceous heat source 102 is ignited, the aerosol-forming substrate 104 is heated by conduction through the abutting rear portion 122 of the combustible carbonaceous heat source 102 and the heat-conducting element 120. The heating of the aerosol-forming substrate 104 releases volatile compounds including glycerine and nicotine from the plug 114 of tobacco material.

[0149] The non-combustible, substantially air impermeable, barrier coating 118 provided on the rear face of the combustible carbonaceous heat source 102 isolates the combustible carbonaceous heat source 102 from the airflow pathway through the aerosol generating article 100 such that, in use, air drawn through the aerosol generating article 100 along the first portion and the second portion of the airflow pathway does not directly contact the combustible carbonaceous heat source 102.

[0150] Air is drawn into the aerosol generating article 100 through the at least one air inlet 132. This air first enters the air-permeable segment 128 of the airflow directing element 106.

[0151] A first portion of this air follows a first airflow pathway and passes from the air-permeable segment 128, through the distal end of the airflow directing element 106 and into the aerosol-forming substrate 104. While passing through the aerosol-forming substrate 104, the air following the first airflow pathway entrains the volatile compounds from the aerosol-forming substrate 104 to form an aerosol. The air following the first airflow pathway then passes into the distal end of the cavity 129. The aerosol cools and condenses as it passes along the cavity 129.

[0152] A second portion of the air entering the aerosol generating article 100 through that at least one air inlet 132 follows a second airflow pathway. This air passes directly from the air-permeable portion 128 of the airflow directing element 106 and into the cavity 129 at a point downstream of the distal end of the cavity 129. This air does not entrain volatile compounds directly from the aerosol-forming substrate 104 and so may act to dilute the aerosol entrained in the air following the first airflow pathway.

[0153] Air following both the first and second airflow pathways pass through the proximal end of the cavity 129, through the mouthpiece 110, and out of the aerosol generating article 100.

[0154] The first and second airflow pathways are identified by dashed lines and arrows in FIG. 1.

[0155] FIG. 2 shows an alternative aerosol generating article 100 according to the present invention. The aerosol generating article 100 shown in FIG. 2 is of largely identical construction to the aerosol generating article 100 shown in FIG. 1 and like reference numerals are used to identify common features. However, the aerosol generating article 100 shown in FIG. 2 further comprises an expansion chamber 108 located downstream of the airflow directing element 106 and upstream of the mouthpiece 110. The expansion chamber 108 comprises an open-ended hollow tube 134 made of, for example, cardboard, which is of substantially the same diameter as the aerosol-forming substrate 104. To maintain the overall length of the aerosol generating article 100, both the airflow directing element 106 and the mouthpiece 110 are shorter than the corresponding features in the aerosol generating article shown in FIG. 1.

[0156] FIG. 3 shown an alternative aerosol generating article 100 according to the present invention. The aerosol generating article 100 shown in FIG. 3 is of largely identical construction to the aerosol generating article 100 shown in FIG. 1 and like reference numerals are used to identify common features. However, the at least one air inlet 132 is located 3 millimeters upstream of the distal end of the airflow directing element 106.

[0157] In the aerosol generating article shown in FIG. 3, air is drawn into the aerosol generating article 100 through the at least one air inlet 132. This air first enters the aerosol-forming substrate 104 where it becomes entrained with volatile compounds from the aerosol-forming substrate 104.

[0158] A first portion of the air then follows a first airflow pathway and passes into the distal end of the cavity 129. The aerosol cools and condenses as it passes along the cavity 129. A second portion of the air then follows a second airflow pathway and passes through the distal end of the air-permeable segment 128. The air following the second airflow pathway then passes into the cavity 129 at a point downstream of the distal end of the cavity 129.

[0159] Air following both the first and second airflow pathways pass through the proximal end of the cavity 129, through the mouthpiece 110, and out of the aerosol generating article 100. The first and second airflow pathways are identified by dashed lines and arrows in FIG. 3.

[0160] FIGS. 4 and 5 show the results of tests to determine the optimum cross sectional area for the cavity.

[0161] Four aerosol generating articles according to the present invention were manufactured. Each aerosol generating article had an airflow directing element with a cavity having a different cross sectional area. Each aerosol generating article was held at 22 degrees Celsius, at 40 percent relative humidity for 48 hours, and then kept in a sealed aluminum bag prior to assessment.

[0162] The downstream ends of each aerosol generating article was connected to a smoking machine, the combustible heat sources were ignited and each of the aerosol generating articles was subjected to the same puff cycle. Following the puff cycle, the aerosol-forming substrate and the air-permeable portion of the airflow directing elements were removed and the mass of glycerine, acting as an aerosol former, in each was measured.

[0163] FIG. 4 is a graph showing the mass of glycerine obtained from the aerosol-forming substrate as a function of the cross sectional area of the cavity. The mass of glycerine per aerosol-forming substrate is shown in milligrams on the vertical axis 210, and the cross sectional area of the cavity in millimeters squared is shown on the horizontal axis 215. As shown in the graph, the mass of glycerine obtained from the aerosol-forming substrate after use of the aerosol generating article increases as the diameter of the cavity increases.

[0164] As set out above, the provision of a cavity having a larger cross sectional area may lead to a greater proportion of the air following the second airflow pathway. Where the at least one air inlet is located downstream of the distal end of the airflow directing element, this may mean that a greater proportion of the air does not pass through the aerosol-forming substrate at all, meaning that the air following the second airflow pathway would not entrain glycerine from the aerosol-forming substrate. This may lead to the increase in the mass of glycerine remaining in the aerosol-forming substrate as the cross sectional area of the cavity increases.

[0165] FIG. 5 is a graph showing the mass of glycerine obtained from the air-permeable portion of the airflow directing element as a function of the cross sectional area of the cavity. The mass of glycerine per aerosol-forming substrate is shown in milligrams on the vertical axis 220, and the cross sectional area of the cavity in millimeters squared is shown on the horizontal axis 215. As shown in the graph, the mass of glycerine obtained from the air-permeable portion of the airflow directing element after use of the aerosol generating article decreases as the diameter of the cavity increases.

[0166] As set out above, the provision of a cavity having a smaller cross sectional area may lead to a greater proportion of the glycerine entrained by the airflow through the cavity being removed from the aerosol and adsorbed by the air-permeable portion of the air flow directing element. This may lead to an increase in the mass of glycerine remaining in the air-permeable portion of the air flow directing element as the cross sectional area of the cavity decreases.

[0167] Accordingly, the inventors have identified that to optimise the delivery of volatile constituents such as nicotine and glycerine, a balance needs to be struck between these two effects. In other words, the cross sectional area of the cavity must be selected to maximise the release of volatile constituents such as nicotine and glycerine from the aerosol-forming substrate while also minimizing the adsorption of nicotine by the air-permeable portion of the airflow directing element.

[0168] Furthermore, as can be seen from FIG. 5, once the cross sectional area of the cavity gets to about 12 millimeters squared, the mass of glycerine observed in the air-permeable portion of the airflow directing element increases substantially. Accordingly, the inventors have identified that one way to optimise the delivery of volatile constituents such as nicotine and glycerine may be to provide a cavity having a cross sectional area of about 12 millimeters squared. This corresponds to a diameter of about 4 millimeters.

[0169] The specific embodiments and examples described above illustrate but do not limit the invention. It is to be understood that other embodiments of the invention may be made and the specific embodiments and examples described herein are not exhaustive.

[0170] For the purpose of the present description and claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term “about”. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.