Aerosol-Generating Article with Non-Circular Perforations in a Ventilation Zone

This application is a continuation of and claims benefit under 35 U.S.C. § 120 to U.S. patent application Ser. No. 18/684,785, filed Feb. 19, 2024, which is a U.S. national stage application of PCT/EP2022/073906, filed Aug. 29, 2022, and claims the benefit of priority under 35 U.S.C. § 119 from EP 21194080.4, EP 21194082.0, and EP 21194088.7, each filed Aug. 31, 2021, the entire contents of each of which are incorporated herein by reference.

The present invention relates to an aerosol-generating article. The aerosol-generating article may comprise an aerosol-generating substrate and may be adapted to produce an inhalable aerosol upon heating. The invention further relates to an aerosol-generating system comprising an aerosol-generating device having a cavity for receiving an aerosol-generating article. The invention further relates to a method for manufacturing an aerosol-generating article.

Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than combusted, are known in the art. Typically, in such heated smoking articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol-generating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosol-generating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosol-generating substrate. As an alternative, inductively heatable aerosol-generating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosol-generating substrate have been proposed. Alternatively, the susceptor arrangement may be arranged in the aerosol-generating device such as at least partly surrounding a cavity for receiving the aerosol-generating article.

Aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted present a number of challenges that were not encountered with conventional smoking articles. First of all, tobacco-containing substrates are typically heated to significantly lower temperatures compared with the temperatures reached by the combustion front in a conventional cigarette. This may have an impact on nicotine release from the tobacco-containing substrate and nicotine delivery to the consumer. At the same time, if the heating temperature is increased in an attempt to boost nicotine delivery, then the aerosol generated typically needs to be cooled to a greater extent and more rapidly before it reaches the consumer. However, technical solutions that were commonly used for cooling the mainstream smoke in conventional smoking articles, such as the provision of a high filtration efficiency segment at the mouth end of a cigarette, may have undesirable effects in an aerosol-generating article wherein a tobacco-containing substrate is heated rather than combusted, as they may reduce nicotine delivery. Secondly, a need is generally felt for aerosol-generating articles that are easy to use and have improved practicality.

It would be desirable to provide an aerosol-generating article that can be manufactured efficiently and at high speed, preferably with a satisfactory RTD and low RTD variability from one article to another. It would be desirable to provide an aerosol-generating article that provides efficient cooling. It would be desirable to provide an aerosol-generating article that provides efficient cooling of the aerosol. It would be desirable to provide an aerosol-generating article that provides efficient cooling of the vaporized aerosol-forming substrate. It would be desirable to provide an aerosol-generating article that provides efficient mixing of ambient air with the vaporized aerosol-forming substrate.

It would be desirable to provide a new and improved aerosol-generating article adapted to achieve at least one of the desirable results described above.

According to an embodiment of the invention there is provided an aerosol-generating article that may comprise a rod of aerosol-generating substrate. The aerosol-generating article may further comprise a ventilation zone arranged downstream the rod of aerosol-generating substrate. The ventilation zone may comprise perforations. One or more of the perforations may have a non-circular cross-section having an ovality, the ovality being the ratio of a large diameter of a perforation divided by a small diameter of the perforation, of at least 1.5. A thickness of the peripheral wall of the ventilation zone may be between 0.1 millimeter and 2.5 millimeter.

According to an embodiment of the invention there is provided an aerosol-generating article comprising a rod of aerosol-generating substrate. The aerosol-generating article further comprises a ventilation zone arranged downstream the rod of aerosol-generating substrate. The ventilation zone comprises perforations. One or more of the perforations have a non-circular cross-section having an ovality, the ovality being the ratio of a large diameter of a perforation divided by a small diameter of the perforation, of at least 1.5. A thickness of the peripheral wall of the ventilation zone is between 0.1 millimeter and 2.5 millimeter.

Having a non-circular cross-section may improve the mixing of ambient air being drawn into the ventilation zone via the perforations with the air being drawn into the ventilation zone via the rod of aerosol-forming substrate. The flow of the ambient air being drawn into the ventilation zone may be influenced by the shape of the perforations. A more turbulent airflow may be created by non-circular perforations thereby leading to an improved mixing of the ambient air with the air drawn through the rod or aerosol-forming substrate.

The cross-sectional shape of the perforations may be seen in a plane parallel to a central axis of the ventilation zone. The central axis of the ventilation zone is preferably identical to the central axis of the whole aerosol-generating article. The cross-sectional shape of the perforations may be seen at the outermost or peripheral opening area of the perforation.

One or more of the perforations may have an oval cross-section.

One or more of the perforations may be slit-shaped.

For one or more of the perforations, the length of the perforations may be larger than the width of the perforations. Preferably, the length is 1.5 times larger than the width, more preferably 2.5 times larger than the width, more preferably 4 times larger than the width, most preferably 5 times larger than the width for one or more of the perforations.

For one or more of the perforations, a longitudinal axis of the perforation may be parallel to a longitudinal axis of the aerosol-generating article.

One or more perforations may have a width of between 0.05 millimeter and 0.2 millimeter, preferably between 0.1 millimeter and 0.15 millimeter, most preferably between 0.11 millimeter and 0.13 millimeter.

One or more perforations may have a length of between 0.25 millimeter and 1.0 millimeter, preferably between 0.4 millimeter and 0.8 millimeter, most preferably between 0.5 millimeter and 0.6 millimeter.

The ovality of the perforations may be at least 2, preferably at least 3, more preferably at least 4, most preferably at least 5.

Between 5 and 15 perforations may be provided in the ventilation zone. Preferably, between 7 and 14 perforations may be provided in the ventilation zone. Preferably, between 9 and 13 perforations may be provided in the ventilation zone. Preferably, between 10 and 12 perforations may be provided in the ventilation zone. Preferably, the number of perforations is 11.

Having a ventilation zone with perforations may enable that ambient air is drawn into the ventilation zone. This ambient air may mix with air drawn through the rod of aerosol-forming substrate. The rod of aerosol-forming substrate may be heated by an aerosol-generating device so that the aerosol-forming substrate is volatilized. The volatilized aerosol-forming substrate may be entrained in the air flowing through the rod of aerosol-forming substrate. This airflow mixes with the ambient air downstream of the rod of aerosol-forming substrate in the ventilation zone. The mix of ambient air with the air drawn through the rod of aerosol-forming substrate cools down to form an aerosol. Having 10 to 12 perforations improve the mixing of ambient air drawn through the perforations into the ventilation zone with the air drawn into the ventilation zone through the rod of aerosol-forming substrate. This improved mixing may result in an improved aerosol generation. Without being bound to any theory, a number of 10 to 12 perforations have been found to lead to the best mixture of ambient air and air carrying volatilized aerosol-forming substrate. The reason may be that this relatively small number of perforations necessitate relatively large perforations to enable a sufficient amount of ambient air being drawn into the ventilation zone. Relatively large perforation may lead to relatively strong turbulences between the two airflows and thus to an improved mixing of the two airflows.

Each perforation may have a central axis. The aerosol-generating article may have a central axis. A smallest distance between the central axis of each perforation and the central axis of the aerosol-generating article may be between 3% and 15% of the outer diameter of the aerosol-generating article, preferably between 4% and 13% of the outer diameter of the aerosol-generating article, more preferably between 5% and 10% of the outer diameter of the aerosol-generating article, most preferably 6% of the outer diameter of the aerosol-generating article.

Each central axis of each perforation may be angled with respect to a radial direction of the aerosol-generating article by an angle of between 3° and 20°, preferably by an angle of between 4° and 15°, more preferably by an angle of between 5° and 10°, most preferably by an angle of 7°.

This tilt of the perforations may lead to a turbulent flow of the ambient air being drawn into the ventilation zone via the perforations. This may improve the mixing of the ambient air with the air being drawn through the rod of aerosol-forming substrate.

An inner diameter of the hollow tubular ventilation zone may be between 2.5 millimeter and 7.5 millimeter, preferably between 3.5 millimeter and 6.5 millimeter, more preferably between 4.0 millimeter and 6.0 millimeter, more preferably between 4.5 millimeter and 5.5 millimeter, most preferably 5.0 millimeter.

The ventilation zone may be arranged in a second hollow tubular segment of an aerosol-cooling element. The second hollow tubular segment may have an inner volume of between 130 mmand 200 mm, preferably between 155 mmand 185 mm, more preferably of 170 mm.

The perforations may be arranged in a peripheral wall of the ventilation zone. The perforations may be non-symmetrically arranged in the peripheral wall. The arrangement may be non-symmetrical in that it may not be point symmetric with respect to any point on a central longitudinal axis of the aerosol-generating article. In addition or alternatively, the arrangement may be non-symmetrical in that it further does not have a line symmetry.

The perforations may be arranged in a peripheral wall of the ventilation zone with a non-constant pitch. The pitch of the perforations is the distance between the perforations. The non-constant pitch arrangement of the perforations may be an arrangement with a coefficient of variation of the pitch of above 5%, preferably above 10%, more preferably above 15%. The coefficient of variation is the ratio of the standard deviation to the mean. The non-constant pitch arrangement of the perforations may be an arrangement with a coefficient of variation of the pitch of below 40%, preferably below 35%, more preferably below 30%.

In other words, a first pair of adjacent perforations may have a first distance between each other measured along the arc length of the peripheral wall, a second pair of adjacent perforations, different from the first pair, may have a second distance between each other measured along the arc length of the peripheral wall and a third pair of adjacent perforations, different from the first pair and the second pair, may have a third distance between each other measured along the arc length of the peripheral wall. The first distance, the second distance and the third distance may all be different.

In one embodiment, more than half of the perforations may be arranged in one half of the peripheral wall of the ventilation zone and less than half of the perforations may be arranged in the other half of the peripheral wall of the ventilation zone. In a preferred embodiment, more than two thirds of the perforations may be arranged in one half of the peripheral wall of the ventilation zone and less than one third of the perforations may be arranged in the other half of the peripheral wall of the ventilation zone.

Having a non-symmetrically arrangement of the perforations may achieve the same quality of mixing of ambient air with air drawn through the rod of aerosol-forming substrate. However, a non-symmetrical arrangement of the perforations may be easier to manufacture or may facilitate higher manufacturing speeds. In more detail, it is difficult to increase the manufacturing speed while maintaining a symmetrical arrangement of the perforations with high quality. It has been found that having perforations with a non-symmetrical arrangement as described herein does not lead to a decrease in quality of the mixing of air or a decrease in quality of aerosol generation.

The perforations may perforate the peripheral wall. The perforations may penetrate through the peripheral wall.

The peripheral wall may at least partially surround the ventilation zone. The peripheral wall may fully surround the ventilation zone. The hollow tubular shape of the ventilation zone may be facilitated by the peripheral wall of the ventilation zone. The peripheral wall may abut the ambient environment surrounding the aerosol-generating article. The peripheral wall may abut the hollow interior of the ventilation zone.

A thickness of the peripheral wall of the ventilation zone may be between 0.8 millimeter and 2.2 millimeter, more preferably between 1.2 millimeter and 1.8 millimeter, most preferably around 1.5 millimeter.

The peripheral wall may be configured to provide the ventilation zone with dimensional stability. Due to the perforations being arranged in the peripheral wall and due to the perforations being tilted, the length of the perforations may be between 0.1 millimeter and 2.7 millimeter, preferably between 0.8 millimeter and 2.4 millimeter, more preferably between 1.2 millimeter and 2.0 millimeter, most preferably around 1.7 millimeter.

The length of a perforation may result in the perforation influencing the airflow through the perforation. The airflow can be directed by the shape of the perforation. A tilting of the perforation as described herein may lead to a turbulent airflow when the air exits the perforation.

In one embodiment, all perforations are tilted in the same direction. All perforations may be tilted with the same angle with respect to the radial direction. This may create a spiral turbulent airflow enhancing mixing of ambient air with the air drawn through the rod of aerosol-forming substrate.

The cross-sectional shape of one or more perforations may be unchanged along the central axis of the perforations. One or more perforations may have a cylindrical shape. One or more perforations may have a hollow cylindrical shape. One or more perforations may have a hollow tubular shape.

The perforations may be arranged in a row. The perforations may be arranged like pearls on a string. The row of perforations may be a ring-shaped arrangement. The row of perforations may be a ring-shaped arrangement with the center being the central axis of the ventilation zone.

A distance between the perforations of the ventilation zone and a downstream end of the rod of aerosol-generating substrate may be between 1 millimeter and 6 millimeter, preferably between 2 millimeter and 5 millimeter, more preferably between 3 millimeter and 4 millimeter.

The arrangement of the perforations in this area of the ventilation zone may improve the aerosol generation. The aerosol generation may be improved by placing the perforations such that an optimized mixing is achieved between the ambient air being drawn in to the ventilation zone through the perforations and the air being drawn into the perforations through the rod of aerosol-forming substrate.

A distance between the perforations of the ventilation zone and a downstream end of the aerosol-generating article may be between 10 millimeter and 26 millimeter, preferably between 12 millimeter and 24 millimeter, more preferably between 14 millimeter and 22 millimeter, most preferably between 16 millimeter and 20 millimeter.

The arrangement of the perforations in this area of the ventilation zone may improve the aerosol generation. The aerosol generation may be improved by having an optimized distance downstream of the perforations to enable cooling of the mix of ambient air and air carrying the volatilized aerosol-forming substrate to enable cooling of the mix and subsequent aerosol formation.

The perforations may be configured to allow ambient air to be drawn into the ventilation zone.

A ratio of ambient air drawn into the ventilation zone through the perforations and air drawn into the ventilation zone through the rod of aerosol-forming substrate may be between 5 percent and 75 percent, preferably between 20 percent and 65 percent, more preferably between 30 percent and 60 percent, more preferably between 40 percent and 55 percent, most preferably 50 percent.

This ration may improve the aerosol formation by achieving a thorough mix of ambient air and air being drawn through the rod of aerosol-forming substrate. This ration may improve the aerosol formation by achieving an optimized cooling of the air being drawn through the rod of aerosol-forming substrate due to mixing this air with ambient air.

The aerosol-generating article may further comprise a filter plug downstream of the ventilation zone. The resistance to draw (RTD) of the filter plug may be between 5 millimetres HO and 80 millimetres HO, preferably between 10 millimetres HO and 65 millimetres HO, more preferably between 15 millimetres HO and 50 millimetres HO, more preferably between 20 millimetres HO and 40 millimetres HO, most preferably 30 millimetres HO. Generally, the RTD may be measured with one of ISO 6565:2002 and coresta recommended method Nr. 41.

The overall resistance to draw of the aerosol-generating article may be essentially determined by the resistance to draw of the filter plug. The resistance to draw of the further components of the aerosol-generating article, particularly of the ventilation zone, may be negligible in comparison with the resistance to draw of the filter plug.

The invention further relates to an aerosol-generating system comprising an aerosol-generating device having a cavity for receiving an aerosol-generating article as described herein.

The invention further relates to a method for manufacturing an aerosol-generating article, wherein the method may comprise the steps of:

The invention further relates to a method for manufacturing an aerosol-generating article, wherein the method comprises the steps of: