WO2025021619A1

WO2025021619A1 - Consumable article with a heating arrangement for an aerosol-generating system

Info

Publication number: WO2025021619A1
Application number: PCT/EP2024/070268
Authority: WO
Inventors: Alec WRIGHT
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2023-07-25
Filing date: 2024-07-17
Publication date: 2025-01-30
Anticipated expiration: 2026-01-25

Abstract

Heating arrangement for aerosol-generating systems A consumable article (10) for an aerosol-generating system (1) for producing an inhalable aerosol comprises a heating arrangement (300) disposed in a vaporization chamber (200) and a liquid reservoir (100) storing a liquid aerosol-forming material (101). The heating arrangement (300) comprises a wicking member (310) having a first end region (311) arranged in fluid connection with an outlet (104) of the liquid reservoir (100) and a second end region (312) located between the first end region and another end of the wicking member (310) away from the first end region. The heating arrangement (300) further comprises a resistive heating element (320) configured to heat the wicking member (310) having a first end (321) disposed at the first end region (311) of the wicking member (310) and a second end (322) disposed at the second end region (312) of the wicking member (310), wherein an electrical resistance of the heating element (320) per unit length increases along a direction from the first end (321) to the second end (322) of the heating element (320) when an electrical current is passed through the heating element (320). The vaporization chamber (200) comprises a vaporization chamber inlet (201) and a vaporization chamber outlet (202) which arranged relative to the heating arrangement (300) in the vaporization chamber (200) to establish at least one airflow over the heating arrangement (300) in a direction substantially parallel to the longitudinal axis of the heating arrangement (300) from the second end region (312) of the wicking member (310) to the first end region (311) of the wicking member (310) when air is drawn from a vapor outlet (12) of the consumable article (10).

Description

CONSUMABLE ARTICLE WITH A HEATING ARRANGEMENT FOR AN AEROSOL-GENERATING SYSTEM

Technical field

The present invention relates to an electronic aerosol-generating system for producing an inhalable aerosol, such as an electronic cigarette or e-cigarette. In particular, the invention relates to a vaporizer assembly for use in an aerosol-generating system comprising an aerosol-forming material containing at least two constituents having different boiling points.

Description of related art

Personal aerosol-generating systems such as electronic cigarettes or e-cigarettes are more and more popular as an alternative to conventional tobacco articles such as cigarettes, cigars, and pipes.

A personal aerosol-generating system usually comprises a vaporizer unit, typically a heating element, a power supply unit and an electronic control unit. Vaporization occurs upon heating of an aerosol-forming material up to or above a vaporizing temperature of the aerosol-forming material in the vaporizer unit. One common example of a conventional aerosol-generating system is an electronic cigarette, which vaporizes a liquid stored in a liquid reservoir.

The liquid aerosol-forming material used in the aerosol-generating system may comprise at least an active agent such as nicotine, and one or more aerosol formers such as polypropylene glycol and glycerine as well as at least one flavorant. Each of these compounds has a different boiling point. Accordingly, heating the liquid aerosol-forming material to a given vaporization temperature may cause overheating of one or more of the compounds having lower boiling points. On the other hand, when the heating temperature is reduced to around the boiling points of the one or more of the compounds having lower boiling points, the heating temperature may not be high enough to achieve a sufficiently high rate of vaporization of compounds having higher boiling points. The low heating temperature may also form large droplets unsuitable for inhalation. In this way, differences in the rate of vaporization among different compounds having different boiling points may also cause complication in controlling a composition and consistency of aerosol formed from the liquid aerosol-forming material during consumption. One approach to improve the control of vaporization of each compound in the liquid aerosolforming material may be to produce a temperature gradient when aerosol forming material is vaporized. For example, as disclosed in US10674865, such a temperature gradient may be achieved by employing a wick having a tapered end and a heating element comprising a heating coil configured to fit around the tapered end of the wick. In that configuration, the energy from the heating element is focused on a tip of the tapered wick, thereby a temperature gradient where the highest temperature is achieved at the tip of the wick is formed. However, the assembly of the tapered wick and the heating coil is complicated to manufacture compared with conventional wickcoil assemblies found in most e-cigarettes. Moreover, achieving a target temperature gradient using such configuration brings challenges in dimensioning the wick and the heating element. Indeed, the temperature of each part of the wick is determined by a local volume of the wick per unit length of the heating element. This limits the flexibility of the design of the aerosol generating system, especially for miniaturization of the system.

There is therefore a need for a simpler vaporizer unit design for aerosol generating systems, which could allow for provision of temperature gradients to better control vaporization of individual components in an aerosol forming composition.

Summary of invention

According to a first aspect of the invention there is provided a heating arrangement for an aerosolgenerating system. The heating arrangement comprises a wicking member comprising: a first end region located on one end of the wicking member; and a second end region located away from the first end region along a length of the wicking member. The heating arrangement further comprises a resistive heating element disposed adjacent to the wicking member. The resistive heating element comprises: a first end of the heating element disposed at the first end region of the wicking member; and a second end of the heating element disposed at the second end region of the wicking member, whereby the heating element extends between the first and second ends thereof along a determined length. First and second electrical contacts are electrically connected respectively to the first end of the heating element and the second end of the heating element for connecting the heating element to an electrical power supply. The heating element is configured such that an electrical resistance of the heating element per unit length increases along a direction from the first end to the second end of the heating element so that a positive temperature gradient is achieved from the first end to the second end of the heating element when an electrical current is passed through the heating element.

The resistive heating element of the heating arrangement is configured to heat the wicking member for vaporizing the aerosol-forming material retained therein.

The resistive heating element has a determined length between the first end to the second end.

Preferably, the heating element may be disposed to surround at least a part of the wicking member. The heating element having the determined length may cover at least a portion of the wicking member along a longitudinal direction of the wicking member so that a length of the portion of the wicking member covered by the heating element corresponds to the determined length of the heating element.

The heating arrangement further comprises first and second electrical contacts electrically connected respectively to the first end of the heating element and the second end of the heating element that are connected to an electrical power supply for supplying electrical current through the heating element.

The first and second electrical contacts may be formed as a part of the heating element. Alternatively, first and second electrical contacts may be separate elements attached to the heating element e.g., by soldering.

In some embodiments, the heating arrangement is used in an aerosol-generating system comprising the electrical power supply. The aerosol-generating system may comprise two electrical connections configured to establish an electrical circuit including the heating element and the electrical power supply via first and second electrical contacts of the heating arrangement.

In some embodiments, the heating arrangement is used in a consumable article (or a pod) for the aerosol-generating system and the aerosol-generating system comprises an aerosol-generating device having the electrical power supply and configured to be detachably coupled to the consumable article. In this case, the first and second electrical contacts may be further connected to respective electrical contacts placed on an outer surface of the consumable article to establish an electrical connection to a power source in the aerosol-generating system. The respective electrical contacts on the consumable article are arranged such that each of the respective electrical contacts physically contact electrical contacts of the aerosol-generating device to establish an electrical circuit for supplying a controlled power to the heating element of the consumable article from the power source in the aerosol-generating device.

The heating element of the consumable article is configured such that an electrical resistance of the heating element per unit length increases along a longitudinal axis of the heating element from the first end to the second end. In this way, when an electrical current is passed through the heating element, the resistive heating element generates a variable heat energy per unit length across the resistive heating element which increases along a direction from the first end to the second end. Consequently, the wicking member may receive a higher heating energy at the second end region of the wicking member than at the first end region of the wicking member. This non-uniform distribution of heat energy may result in a positive temperature gradient formed across the wicking member in a direction from the first end region to the second end region.

The wicking member may comprise a cylindrical rod, and the first end region of the wicking member may be disposed at or adjacent to one end of the cylindrical rod and the second end region of the wicking member may be disposed at or adjacent to another end of the cylindrical rod.

Alternatively, the shape of the wicking member may be any elongated shape with a constant cross-sectional area along the length of the wicking member such as a plate, and a prism.

In some embodiments, the wicking member may be in the form of a cone, or a truncated pyramid.

Preferred shapes of the wicking member may be shapes with a constant cross-sectional area along the length of the wicking member such as a cylindrical rod, a plate and a prism. A wicking member with one of these shapes may be manufactured and assembled with the heating element in a relatively simple manner compared with a wicking member in the form of a cone, or a truncated pyramid.

The wicking member may comprise a monolithic material having a capillary structure. The wicking member may comprise a porous material comprising a plurality of pores configured to absorb, retain and deliver the liquid aerosol-forming material by capillary action occurring in the pores.

Advantageously the wicking member may comprise a thermally resistant material which is physically and chemically stable at the temperatures of vaporization of the liquid aerosol-forming material, for example up to 350°C. The wicking member may have a certain hardness so that the dimension of the wicking member substantially does not deform, neither during manufacturing nor during use. The rigidity of the wicking member may facilitate handling of the wicking member during assembly of the wicking member and the heating element. The rigid wicking member is also preferred during use because the contact between the wicking member and the heating element should not significantly change regardless of the heating temperature and the amount of the liquid aerosol-forming material retained in the wicking member.

The wicking member may preferably comprise a porous ceramic material or a porous glass. A suitable porous ceramic material may be selected from the group consisting of aluminum oxide, zirconia, or silicon nitride or combinations thereof.

The heating element may be wound about a circumference of the cylindrical rod of the wicking member.

Preferably, the heating element is an electrically conductive strip, wire or track. Alternatively, the heating element may be at least partially formed of an electrically conductive strip, wire or track.

In some embodiments where the heating element comprises the electrically conductive strip, wire or track that is employed to form the heating element, a cross-sectional area of the heating element along a direction perpendicular to its longitudinal direction decreases along the length of the heating element from the first end to the second end thereof. The cross-sectional area of the heating element corresponds to the cross-sectional area measured along a direction of a longitudinal axis of the electrically conductive strip, wire or track in an extended state. The electrically conductive strip, wire or track is dimensioned to have the cross-sectional area which decreases from the first end to the second end. In this way, there is a progressive increase in the electrical resistance of the heating element from the first end to the second end of the heating element.

In some embodiments, the strip, wire or track may be designed such that a width of the strip, wire or track progressively decreases along the direction of the longitudinal axis thereof from the first end to the second end.

When the heating element is formed of the strip, wire or track with the variable cross-sectional area and the wicking member comprises the cylindrical rod, the strip, wire or track may be wound about the circumference of the cylindrical rod from the first end region to the second end region with a constant pitch, where the pitch is defined as a distance between two adjacent wound lines measured from and to their central positions in a width direction. Alternatively, the heating element may be wound with a variable pitch so that the temperature profile across the heating element can be more precisely configured.

The strip, wire or track may be helically wound around the circumference of the cylindrical rod of the wicking member to form the heating arrangement. In another embodiment, the heating element may be a printed helical track formed of an electrically conductive film disposed on a surface of the circumference of the cylindrical rod.

In some embodiments, the cross-sectional area of the electrically conductive strip, wire or track may be constant along a direction of a longitudinal axis thereof from the first end to the second end, and the electrically conductive strip, wire or track may be wound about the circumference of the cylindrical rod from the first end region to the second end region with a variable pitch so that the resulting heating element has an electrical resistance of the heating element per unit length that increases along a longitudinal axis of the heating element from the first end to the second end.

In some embodiments, the heating element may be an electrically conductive mesh, a plurality of heat track lines or any other forms of electrically conductive materials suitable for resistive heating of the wicking member arranged adjacent to the wicking member such that the heating element generates a heating power profile which progressively increases along the longitudinal axis of the heating element from the first end of the heating element to the second end of the heating element when a current is passed through the heating element. The variable heating power across the length of the heating element may cause the positive temperature gradient from the first end region of the wicking member to the second end region of the wicking member.

According to a second aspect of the invention, there is provided a consumable article comprising: a heating arrangement according to any one of the preceding embodiments which is disposed in a vaporization chamber; a liquid reservoir storing a liquid aerosol-forming material. The liquid aerosol-forming material comprises a first chemical compound having a first boiling point and a second chemical compound having a second boiling point which is higher than the first boiling point. The first region of the wicking member of the heating arrangement is arranged in fluid connection with an outlet of the liquid reservoir. The consumable article may further comprise an air inlet and a vapor outlet. The vaporization chamber of the consumable article may be in fluid communication with the air inlet and the vapor outlet.

The liquid aerosol-forming material may be stored in a reservoir cavity defined by a reservoir housing of the liquid reservoir.

The liquid reservoir may further comprise a reservoir outlet configured to supply the liquid aerosolforming material from the reservoir cavity to the wicking member. The reservoir outlet may be formed on the reservoir housing in the form of an opening through which an extremity of the first end region of the wicking member may be inserted until at least a part of the inserted portion is immersed in the liquid aerosol-forming material.

In this way, the liquid aerosol-forming material is delivered from the liquid reservoir through the part of the first end region which is in contact with the outlet of the liquid reservoir. The liquid aerosol-forming material received in the first end region of the wicking member is then further delivered through the wicking member essentially in a direction toward the second end region. As described earlier, the wicking member may comprise a capillary material and therefore delivery and retention of the liquid aerosol-forming material is driven by capillary action. The liquid delivery continues until the liquid aerosol-forming material is distributed in an entire volume of the wicking member. In use, the liquid aerosol-forming material is supplied by capillary action to a part where the liquid aerosol-forming material has been depleted.

In some embodiments where the wicking member is a cylindrical rod, the end of the wicking member on the side of the first end region may be inserted in the outlet of the liquid reservoir and a body of the wicking member projects from the outlet of the liquid reservoir substantially perpendicular to the outlet. The outlet may be dimensioned such that the outlet fits closely on the circumference of the cylindrical rod to stabilize the position of the wicking member relative to the reservoir.

When the heating element may be wound about a circumference of the cylindrical rod of the wicking member, the first end of the heating element may be disposed in the first end region of the wicking member but preferably arranged outside of the reservoir because the direct contact of the heating element with the liquid aerosol-forming material in the reservoir may cause corrosion of the heating element which may affect not only the heating element but also contaminate the liquid aerosol-forming material stored in the liquid reservoir.

The liquid aerosol-forming material may comprise a first chemical compound having a first boiling point and a second chemical compound having a second boiling point which is higher than the first boiling point.

The boiling point (b.p.) is a temperature at which a vapour pressure of a liquid is equal to the external pressure, e.g., 1 atm, as generally defined. For example, a conventional aerosol-forming material comprises nicotine (b.p. 247°C) or a nicotine compound, an aerosol former comprising glycerin (b.p. 290°C) and/or propylene glycol (b.p. 188°C) and a flavourant such as menthol (b.p. 212°C). When the liquid aerosol-forming material is heated, each of these compounds evaporates at a different rate to the others essentially according to its boiling point, i.e. , the compound having a lower boiling point evaporates faster than the compound having a higher boiling point.

When the liquid aerosol-forming material is heated to a temperature to evaporate a compound with a high boiling point, one or more of the compounds having lower boiling points may be overheated, resulting in undesirable production of carbonyls from the one or more of the compounds having lower boiling points. On the other hand, when the heating temperature is reduced to around the boiling points of the one or more of the compounds having lower boiling points, the heating temperature may not be high enough to achieve a sufficiently high rate of vaporization of compounds having higher boiling points.

The heating arrangement configured to generate the positive gradient of the temperature of the wicking member from the first end region to the second end region may overcome this problem.

In the case where the liquid aerosol-forming material comprises the first chemical compound with the first boiling point and the second chemical compound with the second boiling point which is higher than the first boiling point, the heating arrangement may be configured to provide the positive gradient of the temperature of the wicking member generated by the heating element to cover a temperature range including the first boiling point and the second boiling point. This may allow to selectively evaporate both the first chemical compound and the second chemical compound at different longitudinal positions of the wicking member.

In addition to the first and second chemical compounds, the liquid aerosol-forming material may include one or more further chemical compounds. In such a case, the positive gradient of the temperature of the wicking member generated by the heating element may cover a temperature range including boiling points of all of these chemical compounds contained in the liquid aerosolforming material. In this way, each of the chemical compounds in the liquid aerosol-forming material may be selectively vaporized at a specific longitudinal position of the heating arrangement.

It is also preferred that a temperature of the hottest point of the wicking member does not significantly exceed a boiling point of the chemical compound having the highest boiling point among the chemical compounds in the liquid aerosol-forming material. In this way, each of the chemical compounds may be selectively evaporated at a specific position of the wicking member dependent on its boiling point, while ensuring that the risk of overheating of the compounds is minimized. Advantageously, a temperature of the hottest point of the wicking member may be at a temperature substantially equal to a boiling point of the chemical compound having the highest boiling point.

In some embodiments, the wicking member further comprises a longitudinal bore defining an airflow path extending through wicking member in a direction substantially parallel to the longitudinal axis of the wicking member. When the wicking member comprises the cylindrical rod, the bore extends through the cylindrical rod in a direction substantially parallel to the longitudinal axis of the cylindrical rod.

In this configuration, the air inlet and the vapor outlet of the consumable article may be in fluid communication with the bore of the wicking member.

In some embodiments, the cylindrical rod of the wicking member having the bore comprises an inner tubular region permeable to fluid, wherein an inner wall of the tubular porous region defines the longitudinal bore, and an outer tubular region which is not fluid permeable and disposed concentrically around the inner tubular region with an inner surface of the outer tubular region in contact with the circumference of the tubular porous region.

Preferably, the inner tubular region comprises a porous material formed of ceramic or glass and the outer tubular region comprises a non-porous material formed of ceramic or glass.

The inner tubular region serves for conducting and evaporating the liquid aerosol-forming material, while the outer tubular region serves for transferring heat from the heating element to the inner tubular region. Because the outer tubular region is not permeable to air, the liquid aerosol-forming material is not delivered through the outer tubular region. Consequently, the delivery of the liquid aerosol-forming material is limited only to the inner tubular region.

Upon activation of the heating element, the outer tubular region of the wicking member is heated. The heat is subsequently conducted in a radial direction toward the inner tubular region of the wicking member and evaporates the liquid aerosol-forming material within the inner tubular region. The evaporated aerosol-forming material may be released only from a surface of the inner tubular region defining the longitudinal bore forming the airflow path. Aerosol or vapor formed from the evaporated liquid aerosol-forming material is then delivered through the longitudinal bore to the vapor outlet of the consumable article to be inhaled by a user. Because the delivery of the liquid aerosol-forming material is limited only in the inner tubular region, where variations in the temperature in a radial direction may be small, the selectivity of evaporation of different chemical compounds across the length of the wicking member may be improved. In addition, heat from the heating element may be more uniformly distributed to the inner tubular region by employing the outer tubular region as a heat transfer element.

The heating arrangement of the consumable article may generate vapor with a high temperature especially from the second end region of the wicking member. For example, when the temperature of the second end region is set at the boiling point of glycerin, which is about 290°C, the vapor may be too hot for inhalation. Therefore, it may be desirable to provide a sufficiently long airflow path to cool a vapor to a suitable temperature to be inhaled. Particularly, it may be desirable to provide a longest air flow path for the vapor generated at the second end region of the wicking member, wherein the wicking member is heated to the highest temperature across the length of the wicking member. It is also desired that the airflow path is formed without significantly increasing a volume of the consumable article.

In some embodiments, the vaporization chamber of the consumable article according to any one of precedent embodiments further comprises a vaporization chamber inlet in fluid communication with the air inlet of the consumable article, and a vaporization chamber outlet in fluid communication with the vapor outlet of the consumable. The vaporization chamber inlet and the vaporization chamber outlet are arranged relative to the heating arrangement in the vaporization chamber to establish at least one airflow over the heating arrangement in a direction substantially parallel to the longitudinal axis of the heating arrangement from the second end region of the wicking member to the first end region of the wicking member when air is drawn from the vapor outlet of the consumable article. Therefore, vapor generated at the second end region of the wicking member travels a longer distance to the vaporization chamber outlet than vapor generated at the first end region. This airflow structure may avoid the hot vapor from exiting the vapor outlet and may also contribute to compensate for variations in temperature of vapor generated from different longitudinal positions of the wicking member, thereby providing vapor at an optimal temperature to the user.

In some embodiments, the consumable article includes the liquid reservoir within the housing arranged in a distal end (a bottom side) of the consumable article and the vaporization chamber arranged between the vapor outlet provided on a proximal end (a top side) and the liquid reservoir. The reservoir outlet may be arranged to face towards the vaporization chamber, and the heating arrangement may project vertically from the reservoir outlet in the vaporization chamber in a direction toward the proximal end. Therefore, the wicking member is arranged with the side of the wicking member away from the reservoir outlet facing up.

The vaporization chamber may comprise a vaporization chamber inlet in fluid communication with the air inlet. The vaporization chamber inlet may be located above the heating arrangement. The vaporization chamber may further comprise a vaporization chamber outlet in fluid communication with the vapor outlet of the consumable and configured to receive the air entraining aerosol generated in the vaporization chamber. The vaporization chamber outlet may be disposed downstream of the heating arrangement, for example, below the heating arrangement in the vaporization chamber.

In some embodiments, the heating arrangement includes the cylindrical wicking member comprising the longitudinal bore according one of preceding embodiments. In this case, the longitudinal bore may define at least a part of an airflow path. When an inhalation by the user takes place, at least a part of the air entering through the air inlet may be directed to a primary airflow which passes from the vaporization chamber inlet through the bore of the wicking member to the vaporization chamber outlet. At the same time, some part of air may flow over outside surfaces of the heating arrangement, in particular the air may flow through a space between the circumferential surface of the heating arrangement and a side wall of the vaporization chamber. The secondary air flow is subsequently merged with the primary air flow, for example at the vapor chamber outlet. In some embodiments, the cylindrical wicking member with the longitudinal bore may comprise the inner tubular region permeable to fluid and the outer tubular region impermeable to fluid, according to one of the preceding embodiments. Therefore, the heating arrangement generates vapor only from the surface of the longitudinal bore. In order to deliver the vapor from the surface of the longitudinal bore, the heating arrangement is disposed in the vaporization chamber such that the end of the wicking member away from the reservoir outlet of the liquid reservoir abuts an inner top wall of the vaporization chamber. The longitudinal bore of the wicking member is arranged such that the bore is in fluid communication with the vaporization chamber inlet and the vaporization chamber outlet. On the other hand, air does not enter into the space between the circumferential surface of the heating arrangement and a side wall of the vaporization chamber because the space is isolated by the end of the wicking member which abuts the inner top wall of the vaporization chamber to close the passage for air. Consequently, air can flow only through the bore, which may offer more precise control of vapor generation and aerosol delivery.

The consumable article may further comprise one or more side channels extending between the vaporization chamber outlet and the vapor outlet to deliver the vapor from the vaporization chamber outlet to the vapor outlet. Preferably, the one or more side channels may be formed within at least one of the outer walls of the housing of the consumable article. The one or more side channels provide a longer flow path which may further cool down the vapor to be inhaled to an optimal temperature. In this way, the airflow structure comprising the one or more side channels further extends a total airflow path length for achieving an effective cooling within a limited volume of the consumable article.

Additionally, an insulating member may be disposed inside the vaporization chamber between the walls of the housing and the heating arrangement to minimize the heat transfer from the heating element to at least a part of the outer walls of the housing where the user touches during use.

In one embodiment, the insulating member may comprise a tube formed of a thermal insulator. The tube may be disposed in the vaporization chamber and surrounding at least a part of side surfaces of the heating element. Alternatively, the insulating member may be provided on inner surfaces of the vaporization chamber. In some embodiments, there is provided an aerosol-generating system comprising the heating arrangement according to any one of preceding embodiments or the consumable article according to any one of preceding embodiments.

The aerosol-generating system may further comprise: a power supply connectable to the resistive heating element through the first and second electrical contacts; and a controller for controlling delivery of electrical power from the power supply to the heating element to generate the temperature gradient in the wicking member in use.

In some embodiments, the aerosol-generating device and the consumable article are configured to be detachably coupled to each other to form the aerosol-generating system. The aerosolgenerating device may further comprise electrical contacts arranged to make electrical contact with the electrical contacts formed on the exterior surface of the consumable article when the aerosol-generating system is assembled.

According to a third aspect of the invention, there is provided a consumable article for an aerosolgenerating system for producing an inhalable aerosol, the consumable article comprising: a heating arrangement disposed in a vaporization chamber; and a liquid reservoir storing a liquid aerosol-forming material comprising a first chemical compound having a first boiling point and a second chemical compound having a second boiling point which is higher than the first boiling point; wherein the heating arrangement comprises: a wicking member comprising: a first end region arranged in fluid connection with an outlet of the liquid reservoir; and a second end region located away from the first end region along a length of the wicking member; a resistive heating element disposed adjacent to the wicking member and comprising: a first end disposed at the first end region of the wicking member; and a second end disposed at the second end region of the wicking member, the heating element extending between the first and second ends thereof along a determined length; and first and second electrical contacts at the first end of the heating element and the second end of the heating element for connecting the heating element to an electrical power supply; wherein an electrical resistance of the heating element per unit length increases along the length of the heating element from the first end to the second end of the heating element such that a positive temperature gradient is achieved from the first end to the second end of the heating element when an electrical current is passed through the heating element; wherein the vaporization chamber comprises: a vaporization chamber inlet in fluid communication with an air inlet of the consumable article; and a vaporization chamber outlet in fluid communication with a vapor outlet of the consumable article, and wherein the vaporization chamber inlet and the vaporization chamber outlet are arranged relative to the heating arrangement in the vaporization chamber to establish at least one airflow over the heating arrangement in a direction substantially parallel to the longitudinal axis of the heating arrangement from the second end region of the wicking member to the first end region of the wicking member when air is drawn from the vapor outlet of the consumable article.

Brief description of drawings

Embodiments of the invention are now described, by way of example with reference to the drawings, in which;

Figures 1a shows a schematic illustration of a consumable article in an embodiment of the invention;

Figure 1 b shows a cross-sectional view of the consumable article along the line A-A in Figure 1a; Figure 2a shows a schematic illustration of a heating arrangement and a liquid reservoir of the consumable article of Figure 1 ;

Figure 2b shows a schematic illustration of the heating arrangement and the liquid reservoir of Figure 2a in an assembled state;

Figure 2c shows a schematic illustration of a temperature profile generated in the heating arrangement of Figures 2a and 2b;

Figure 3a shows a schematic illustration of a wicking member of the heating arrangement of one embodiment of the invention;

Figure 3b shows a cross-sectional view of the wicking member along the line A-A in Figure 3a.

Figure 4a shows a schematic illustration of a heating element comprising a strip according to an embodiment of the invention;

Figure 4b shows the strip of Figure 4a in an extended state; Figure 5a shows a schematic illustration of a wicking member of the heating arrangement of another embodiment of the invention;

Figure 5b shows a cross-sectional view of the wicking member along the line A-A in Figure 5a;

Figure 6a shows a schematic illustration of a wicking member of the heating arrangement of another embodiment of the invention;

Figure 6b shows a cross-sectional view of the wicking member along the line A-A in Figure 6a;

Figure 7a shows a schematic illustration of a top view of the consumable article of another embodiment of the invention;

Figure 7b shows a cross-sectional view of the consumable article along the line A-A in Figure 7a; Figure 7c shows a cross-sectional view of the consumable article along the line B-B in Figure 7a; Figure 8a shows a schematic illustration of a top view of the consumable article of another embodiment of the invention;

Figure 8b shows a cross-sectional view of the consumable article along the line A-A in Figure 8a; Figure 8c shows a cross-sectional view of the consumable article along the line B-B in Figure 8a; and

Figure 9 shows a schematic illustration of an aerosol-generating system of an embodiment of the invention.

Detailed description with reference to drawings

Figures 1a and 1 b schematically represent an example of a consumable article 10 for use in an aerosol-generating system 1. The consumable article 10 comprising: a liquid reservoir 100 for storing a liquid aerosol-forming material 101 ; a vaporization chamber 200 in fluid communication with an air inlet 11 of the consumable article 10 and a vapor outlet 12 of the consumable article 10; and a heating arrangement 300 disposed in the vaporization chamber 200.

In this embodiment, both the liquid reservoir 100 and the vaporization chamber 200 are defined by a housing 13 of the consumable article 10. The housing 13 also defines the air inlet 11 and the vapor outlet 12. The air inlet 11 may comprise one or more openings in the housing 13 extending between an outer surface of the housing 13 and an inner surface 13a of the housing 13 facing towards the vaporization chamber 200. The vapor outlet 12 may comprise an opening at a proximal end (a mouthpiece end) of the housing 13.

Figures 2a and 2b show the heating arrangement 300 and the liquid reservoir 100 in one embodiment of the invention. The heating arrangement 300 comprises a wicking member 310 and a resistive heating element 320 configured to heat the wicking member 310 for vaporizing the aerosol-forming material 101.

The liquid reservoir 100 comprises a reservoir housing 102 defining a reservoir cavity 103 for storing the liquid aerosol-forming material 101 and a reservoir outlet 104. The reservoir housing 102 may be a part of the housing 13 of the consumable article. The reservoir outlet 104 may be an opening in the reservoir housing 102. The reservoir outlet 104 is configured to supply the liquid aerosol-forming material 101 from the reservoir cavity 103 to the wicking member 310.

The liquid aerosol-forming material 101 may comprise a first chemical compound having a first boiling point and a second chemical compound having a second boiling point which is higher than the first boiling point temperature.

For example, the first and second chemical compounds may be respectively selected from one of nicotine, a nicotine-containing compound (for instance a nicotine salt formulation), glycerin, propylene glycol and a flavourant such as menthol.

Figure 3a shows a first example of the wicking member 310 of the heating arrangement 300. Figure 3b shows a cross-sectional view of the wicking member 310 along the line A-A of Figure 3a. The wicking member 310 comprises a first end region 311 located on one end of the wicking member 310. The wicking member 310 further comprises a second end region 312 located between the first end region 311 and another end of the wicking member away from the first end region 311.

The wicking member 310 may comprise a cylindrical rod 316. In this example, the wicking member 310 comprises a porous ceramic material or a porous glass. A part including one end 313 of the cylindrical rod forms the first end region 311 while a part including the other end 314 of the cylindrical rod forms the second end region 312. In such a configuration, the end 313 of the wicking member forming a part 31 T of the first end region 311 is inserted in the reservoir outlet 104 of the liquid reservoir 100 and a body 315 of the wicking member 310 projects vertically from the reservoir outlet 104, as shown in Figure 2b. The reservoir outlet 104 may be dimensioned such that the outlet opening fits closely on the circumference of the cylindrical rod 316 to stabilize the position of the wicking member relative to the reservoir.

In use, the heating arrangement 300 and the liquid reservoir 100 are assembled as shown in Figure 2b. The part 31 T of the first end region 311 , e.g., an extremity of the wicking member 310 on the side of the first end region 311 , is inserted into the reservoir cavity 103 through the reservoir outlet 104 so that the wicking member is in contact with the liquid aerosol-forming material 101 stored in the reservoir cavity 103. Once the heating arrangement 300 and the reservoir 100 are assembled, the liquid aerosol-forming material 101 is received in the first end region 311 of the wicking member 310 through the part immersed in the liquid aerosol-forming material 101. The liquid aerosol-forming material 101 is then further delivered through the wicking member 310 essentially in a direction toward the second end region 312. As described later, the wicking member 310 typically comprises a capillary material. The delivery and retention of the liquid aerosol-forming material is therefore driven by capillary action. The liquid delivery continues until an entire volume of the wicking member 310 is soaked. During aerosol generation, the liquid aerosol-forming material 101 is supplied by capillary action to a part where the liquid aerosolforming material 101 has been depleted due to evaporation.

Referring to Figures 2a and 2b, the resistive heating element 320 may be in the form of a helix disposed to surround the circumference of the cylindrical wicking member 310. The heating element 320 has an inner diameter substantially equal to the diameter of the wicking member 310. The heating element 320 comprises a first end 321 and a second end 322 opposite to the first end 321. The heating element 320 is arranged relative to the wicking member 310 such that the first end 321 of the heating element 320 is disposed at the first end region 311 of the wicking member 310 and the second end 322 of the heating element 320 is disposed at the second end region 312 of the wicking member 310, thereby the heating element 320 extends between the first end region 311 and the second end region 312 of the wicking member.

Figures 4a illustrates an example of the heating element 320 in some embodiments. The heating element 320 comprises an electrically conductive strip 323 formed into the helical coil having a longitudinal axis L. The heating element 320 may be formed by winding the strip 323 around the circumference of the cylindrical rod 316 of the wicking member 310 (cf. Figure 2a). The first end 321 of heating element 320 is disposed relative to the wicking member 310 such that a part of the first end region 311 of the wicking member 310 to be inserted in the liquid reservoir 100 is not surrounded by the heating element 320. In this way, the heating element 320 is arranged outside of the liquid reservoir 100 when the heating arrangement 300 and the liquid reservoir 100 are assembled. This configuration avoids a direct contact of the heating element with the bulk of the liquid aerosol-forming material which may cause corrosion of the heating element. Figure 4b shows a top view of the strip 323 forming the heating element 320 of Figure 4a in an extended state. The strip comprises a constant thickness. The strip however comprises a variable width which progressively decreases along the length of the strip 323 from the first end 321 to the second end 322. Because the thickness of the strip is uniform across the strip, the strip comprises a variable cross-sectional area which decreases along a length of the strip from the first end 321 to the second end 322 which in turn results in a progressive increase in an electrical resistance of the strip per unit length from the first end 321 to the second end 322 when electrical current is passed through the heating element 320.

Accordingly, when the strip 323 of Figure 4b is formed into the heating element 320 in the form of a helix, an electrical resistance of the heating element 320 per unit length increases along a longitudinal axis of the heating element 320 from the first end 321 to the second end 322. Consequently, when an electrical current is passed through the heating element 320, the generation of a heat energy per unit length of the heating element 320 increases along a direction of the longitudinal axis L of the heating element 320 from the first end 321 to the second end 322. This non-uniform distribution of heat energy having a positive gradient from the first end 321 to the second end 322 of the heating element 320 may result in a positive temperature gradient formed across the wicking member 310 in a direction from the first end region 311 to the second end region 312.

In some embodiments, the strip 323 of the heating element 320 has a constant pitch p, where the pitch is a distance between two adjacent wound lines measured from and to their central positions in a width direction. Alternatively, the heating element 320 may be wound with a variable pitch p so that the temperature profile across the heating element 320 can be more precisely configured.

Although the heating element 320 shown in Figures 2a, 2b, 4a and 4b comprises the strip 323, the heating element 320 may alternatively comprise other materials such as a wire, a printed film or layer.

The heating arrangement 300 further comprises first and second electrical contacts 330a, 330b electrically connected respectively to the first end 321 of the heating element 320 and the second end 322 of the heating element 320 for supplying electrical current through the heating element 320. The first and second electrical contacts 330a, 330b may be formed as a part of the heating element 320. Alternatively, the first and second electrical contacts 330a, 330b may be separate elements attached to the heating element.

The first and second electrical contacts 330a, 330b may be further connected to respective electrical contacts (not shown) placed on an outer surface of the consumable article 10 to establish an electrical connection to the power source in an aerosol-generating system, e.g., in an aerosol-generating device configured to be detachably coupled to the consumable article 10. The respective electrical contacts on the consumable article 10 are configured to establish an electrical circuit for supplying power to the resistive heating element 320 of the consumable article 10 from the power source disposed in the aerosol-generating device.

In some embodiments, the liquid aerosol-forming material 101 comprises the first chemical compound with the first boiling point and the second chemical compound with the second boiling point which is higher than the first boiling point. In this case, the heating arrangement 300 may be configured to provide the positive gradient of the temperature which covers a temperature range including the first boiling point and the second boiling point. This may allow to selectively evaporate both the first chemical compound and the second chemical compound at different longitudinal positions of the wicking member 310.

Figure 2c is an illustration of a graph displaying one example of a temperature profile of the wicking member 310 when the heating element 320 is activated. In this example, the temperature continuously increases from a position Po, corresponding to the position of the first end 321 of the heating element 320, to a position Pi, corresponding to the position of the second end 322 of the heating element 320. The wicking member 310 of Figure 2c further comprises a position P2 and a position P3 located between the position Po and the position Pi. The position P2 is located closer to the position Po than the position P₃. In this example, the position P2 is heated to a temperature T1 which is substantially equal to the first boiling point of the first chemical compound, and the position P₃ is heated to a temperature T2 which is substantially equal to the second boiling point of the second chemical compound.

During operation of the aerosol-generating system, the first chemical compound and the second chemical compound of the liquid aerosol-forming material 101 from the liquid reservoir 100 are delivered through the reservoir outlet 104 toward the second end region 312 of the wicking member 310. At the position P₂, where the temperature Ti is the boiling point of the first chemical compound, the first chemical compound may start to be predominantly evaporated. The evaporation of the first chemical compound at the first position P₂ depletes the first chemical composition in the liquid aerosol-forming material 101. Consequently, the liquid aerosol-forming material 101 delivered further from the first position P₂ toward the second end region 312 of the wicking member 310 may become substantially free from the first chemical compound. On the other hand, the second chemical compound of the liquid aerosol-forming material 101 may not be consumed at the first position P₂ because the temperature is lower than the second boiling point of the second chemical compound. Hence, substantially all of the second chemical compound originally in the liquid aerosol-forming material 101 may remain and may be delivered further toward the second end region 312 of the wicking member 310.

Once the second chemical compound has reached the second position P₃of the wicking member 310 where the temperature is substantially equal to the boiling point of the second chemical compound, the second chemical compound may start to be evaporated significantly. Consequently, the second chemical compound in the liquid aerosol-forming material 101 is depleted at the second position P₃, and the liquid aerosol-forming material 101 delivered further from the second position P₃ toward the second end region of the wicking member may become substantially free from the second chemical compound.

The liquid aerosol-forming material 101 indeed typically includes more than two chemical compounds. For any number of chemical compounds, the heating arrangement 300 may be configured to generate an appropriate positive temperature gradient for selectively vaporizing a plurality of compounds at different longitudinal positions of the wicking member 310 that are specific to their boiling points. In this way, each of the chemical compounds may be selectively vaporized at a specific longitudinal position of the heating arrangement.

Preferably, the positive gradient of the temperature of the wicking member 310 generated by the heating element 320 covers a temperature range including boiling points of all chemical compounds contained in the liquid aerosol-forming material 101.

It is also preferred that a temperature of the hottest point of the wicking member 310 does not significantly exceed a boiling point of the chemical compound having the highest boiling points among the chemical compounds in the liquid aerosol-forming material 101. In this way, each of the chemical compounds may be selectively evaporated at a specific position of the wicking member 310 dependent on its boiling point, while ensuring that the risk of overheating of the compounds is minimized.

Figures 5a and 5b show a second example of the wicking member 310. The wicking member 310 comprises the cylindrical rod 316, like the wicking member 310 of Figures 3a and 3b. The wicking member 310 of this embodiment differs from the wicking member 310 of Figures 3a and 3b in that the cylindrical rod of the wicking member 310 further comprises a longitudinal bore 317 defining an airflow path 203 extending through the cylindrical rod in a direction substantially parallel to the longitudinal axis of the cylindrical rod. The air inlet 11 may be in fluid communication with a first opening 317a of the bore 317 which is on the side of the first end region 311 , and the vapor outlet 12 may be in fluid communication with a second opening 317b of the opposite end of the bore 317 which is on the side of the second end region 312. In this way the air from the air inlet 11 flows into the first opening 317a through the bore 317 to the second opening 317b and then further to the vapor outlet 12.

Figures 6a and 6b show a third example of the wicking member 310. Similar to the wicking member 310 of Figures 5a and 5b, the wicking member 310 of this embodiment comprises the cylindrical rod 316 having the longitudinal bore 317 extending through the wicking member 310. The wicking member 310 further comprises an inner tubular region 318 permeable to fluid and an outer tubular region 319 impermeable to fluid and disposed concentrically around the inner tubular region 318 with an inner surface of the outer tubular region 319 in contact with the circumference of the tubular porous region. The inner wall of the inner tubular region 318 defines the longitudinal bore 317. In this configuration, the liquid aerosol-forming material 101 is transferred only through the inner tubular region 318. The outer tubular region 319 which is not fluid permeable serves to transfer heat from the heating element 300 to the inner tubular region 318 and the liquid aerosolforming material 101 therein.

The inner tubular region 318 may comprise a porous material formed of ceramic or glass and the outer tubular region 319 may comprise a non-porous material formed of ceramic or glass.

Upon activation of the heating element 300, the heat is conducted in the outer tubular region 319 in a radial direction inwardly towards the inner tubular region 318. The heat evaporates the liquid aerosol-forming material 101 within the inner tubular region 318. Because the outer tubular region 319 is not permeable to air, the evaporated aerosol-forming material 101 is released substantially only from a surface 318a of the inner tubular region 318 defining the longitudinal bore 317 (i.e., the airflow path 203). Vapor formed from the evaporated liquid aerosol-forming material is then delivered through the longitudinal bore 317 to the vapor outlet 12 of the consumable article to be inhaled by a user.

Because the delivery and evaporation of the liquid aerosol-forming material 101 is limited only in the inner tubular region 318, where variations in temperature in a radial direction may be small, the selectivity of evaporation of different chemical compounds across the length of the wicking member 310 may be improved. The wicking member 310 also allows to direct the vapor to be formed only in the longitudinal bore 317 which may be advantageous for better control of properties of the aerosol or vapor.

The heating arrangement 300 may generate vapor with a high temperature especially from the second end region 312 of wicking member 310. For example, when the temperature of the second end region 312 is set at the boiling point of glycerin, which is about 290°C, the vapor as generated may be too hot for inhalation. Therefore, it may be desirable to provide a sufficiently long airflow path for the vapor to be cooled to a suitable temperature for inhalation before the vapor exits the vapor outlet 12. Particularly, it may be desirable to design the airflow structure of the consumable article such that the vapor generated at the second end region 312 of the wicking member 310 travels a longer distance before exiting from the vapor outlet than the vapor generated at the first end region 311 , so that the vapor with a higher temperature can be cooled down more than a vapor with a lower temperature. It is also desired that the long airflow path is formed without significantly increasing a volume of the consumable article.

Figures 7a, 7b and 7c show an example of the consumable article 10 comprising the heating arrangement 300 of the consumable article 10 according to any one of preceding embodiments. The consumable article 10 comprises the vaporization chamber 200 which comprises a vaporization chamber cavity 209, a vaporization chamber inlet 201 in fluid communication with the air inlet 11 of the consumable article 10, and a vaporization chamber outlet 202 in fluid communication with the vapor outlet 12 of the consumable article 10. The vaporization chamber inlet 201 and the vaporization chamber outlet 202 are arranged relative to the heating arrangement 300 in the vaporization chamber 200 to establish at least one airflow over the heating arrangement 300 in a direction substantially parallel to the longitudinal axis of the heating arrangement 300 from the second end region 312 of the wicking member to the first end region 311 of the wicking member 310 when air is drawn from the vapor outlet of the consumable article 10. In this way, when the user inhales from the vapor outlet 12, the air passes over the heating arrangement 300 from the hottest region to the coolest region. A flow path to the vapor chamber outlet for vapor generated at the second end region 312 of the wicking member 310 is therefore longer than the flow path for vapor generated at the first end region 311. Therefore, vapor generated at the second end region 312 of the wicking member 310 travels a longer distance to the vaporization chamber outlet 202 than vapor generated at the first end region 311. This airflow structure may avoid the hot vapor exiting the vapor outlet 12 and may also contribute to compensate for variations in temperature of vapor generated from different longitudinal positions the wicking member 310, thereby providing vapor at an optimal temperature to the user.

The consumable article 10 has the liquid reservoir 100 within the housing 13 arranged in a distal end 15 (a bottom side) of the consumable article 10 and the vaporization chamber 200 arranged between the vapor outlet 12 provided on a proximal end 14 (a top side) of the consumable article 10 and the liquid reservoir 100.

Figure 7b shows a cross-sectional view of the consumable article 10 along the line A-A of Figure 7a. The vaporization chamber 200 comprises a vaporization chamber inlet 201 in fluid communication with the air inlet 11. The vaporization chamber inlet 201 may be arranged above the heating arrangement 300. The vaporization chamber 200 further comprises a vapor chamber outlet 202 configured to receive the air entraining aerosol generated in the vaporization chamber 200. The vaporization chamber outlet 202 is in fluid communication with the vapor outlet 12.

For the configuration where the wicking member 310 comprises the longitudinal bore 317 as shown in Figure 7b, the liquid reservoir housing 102 comprises a reservoir air channel 105 extending vertically through the liquid reservoir 100. The reservoir air channel 105 fluidically connects the bore 317 of the wicking member 310 and the vaporization chamber outlet 202. In this way, the air flowing through the bore 317 of the wicking member 310 is delivered to the vaporization chamber outlet 202.

Preferably the vaporization chamber inlet 201 , the bore 317, the reservoir air channel 105 and the vaporization chamber outlet 202 are aligned along the longitudinal axis of the consumable article 10 to form the straight air flow path 203 extending through the length of the vaporization chamber 200. When an inhalation by the user takes place, air entering the consumable article through the one or more air inlets 11 flows to the vaporization chamber inlet 201. In the vaporization chamber 200, at least a part of the air flows downward through the airflow path 203 to the vaporization chamber outlet 202 to form a primary airflow 205. At the same time, some part of the air may flow downwardly through a space between the circumferential surface of the heating arrangement 300 and a side wall 204 of the vaporization chamber 200 to form a secondary air flow 206. The secondary air flow 206 is subsequently merged with the primary air flow 205, for example at the vapor chamber outlet 202. For establishing the secondary airflow 206, one or more air channels (not shown) in fluid communication with the vaporization chamber outlet 202 and a downstream end (i.e., the distal end) of the space between the circumferential surface of the heating arrangement 300 and a side wall 204 of the vaporization chamber 200 may be provided.

Figure 7c shows a cross-sectional view of the consumable article 10 along the line B-B of Figure 7a. The consumable article 10 may further comprise one or more side channels 207 extending between the vaporization chamber outlet 202 and the vapor outlet 12 to deliver the vapor from the vaporization chamber outlet 202 to the vapor outlet 12. Preferably, the one or more side channels 207 may be formed within at least one of the outer walls of the housing 13 of the consumable article 10. The one or more side channels 207 provide a longer flow path which may further cool down the vapor to be inhaled to an optimal temperature.

Each of the one or more side channels 207 may comprise a first section 207a which extends from the vaporization chamber outlet 202 in a radial direction toward a side wall of the housing 13 and to a first joint portion 207b. As shown in Figure 7c, the first section 207a of the side channel 207 may be formed within a bottom wall of the housing 13 and may run substantially parallel to the bottom surface of the consumable article 10. The side channel 207 further comprises a second section 207c formed in a side wall of the housing 13. The second section 207c extends from the first joint portion 207b and runs vertically up to a second joint portion 207d located at a portion of the side wall of the housing 13 close to the proximal end 14 of the consumable article 10. The side channel 207 further comprises a third section 207e extending between the second joint portion 207d and the vapor outlet 12.

In this consumable article 10, air exiting the vaporization chamber outlet 202 is taken to the first section 207a of the one or more side channels 207. At the first joint portion 207b, the airflow bends 90° and continues to the second section 207c upwardly along the side wall of the housing 13 to the second joint portion 207d. At the second joint portion 207d, the airflow continues through the third section 207e of the side channel 207 which finally flows into the vapor outlet 12 of the consumable article 10. When there is more than one side channel 207, a downstream end of each channel 207 may intersect at a portion 207f upstream of the vapor outlet 12. The airflow structure comprising the one or more side channels 207 further extends a total airflow path length for achieving an effective cooling within a limited volume of the consumable article 10.

Figures 8a-8c show the consumable article 10 in another embodiment. Figure 8b shows a cross- sectional view of the consumable article 10 along the line A- A of Figure 8a. The consumable article 10 comprises the tubular wicking member 310 having the inner tubular region 318 and the outer tubular region 319 similar to the wicking member of Figures 6a and 6b. Therefore, in this embodiment, vapor generates only from the surface of the longitudinal bore 317. In the consumable article 10, the end of the wicking member 310 away from the reservoir outlet 104 of the liquid reservoir 100 abuts an inner top wall 208 of the vaporization chamber 200. The longitudinal bore 317 of the wicking member 310 is arranged such that the bore 317 is in fluid communication with the vaporization chamber inlet 201 and the vaporization chamber outlet 202. On the other hand, air does not flow into the space between the circumferential surface of the heating arrangement 300 and a side wall 204 of the vaporization chamber 200 because there is no space between the wicking member 100 and the inner top wall 208 of the vaporization chamber 200. Consequently, air can flow only through the bore 317, which may offer more precise control of vapor generation and aerosol delivery.

Figure 8c shows a cross-sectional view of the consumable article 10 along the line B-B of Figure 8a. The consumable article 10 may further comprise one or more side channels 207 extending between the vaporization chamber outlet 202 and the vapor outlet 12 to deliver the vapor from the vaporization chamber outlet 202 to the vapor outlet 12. The side channel 207 in this embodiment is same as the side channel 207 shown in Figure 7c.

Figure 9 shows an aerosol-generating system 1 according to one embodiment of the invention. The aerosol-generating system 1 comprises the consumable article 10 according to any of the embodiments described above and an aerosol-generating device 20. The aerosol-generating device 20 comprises a power supply 21 connectable to the resistive heating element 320 of the consumable article 10, through the first and second electrical contacts 330a, 330b; and a controller 22 for controlling delivery of electrical power from the power supply to the heating element 320 to generate the temperature gradient in the wicking member 310 in use. The aerosolgenerating device 20 and the consumable article 10 may be configured to be detachably coupled to each other to form the aerosol-generating system 1. The aerosol-generating device 20 may further comprise electrical contacts (not shown) arranged to make an electrical connection to each of the electrical contacts formed on the exterior surface of the consumable article 10 when the aerosol-generating device 20 and the consumable article 10 are coupled.

Alternatively, the aerosol-generating device 20 and the consumable article 10 may be configured as an integrated part of the aerosol-generating system 1. In such a case, the aerosol-generating system 1 comprises the heating arrangement 300 according to any of the preceding embodiments.

The vaporization chamber 200 and the liquid reservoir 100 are formed as a part of the aerosolgenerating system 1. In this embodiment, the entire aerosol generating system 1 may be reusable. The aerosol-generating system 1 is configured such that a user can refill the liquid reservoir 100 with the aerosol-forming material 101 once the aerosol-forming material 101 is depleted.

Claims

1. A consumable article (10) for an aerosol-generating system (1) for producing an inhalable aerosol, the consumable article (10) comprising: a heating arrangement (300) disposed in a vaporization chamber (200); and a liquid reservoir (100) storing a liquid aerosol-forming material (101) comprising a first chemical compound having a first boiling point and a second chemical compound having a second boiling point which is higher than the first boiling point; wherein the heating arrangement (300) comprises: a wicking member (310) comprising: a first end region (311) arranged in fluid connection with an outlet (104) of the liquid reservoir (100); and a second end region (312) located away from the first end region (311) along a length of the wicking member (310); a resistive heating element (320) disposed adjacent to the wicking member (310) and comprising: a first end (321) disposed at the first end region (311) of the wicking member (310); and a second end (322) disposed at the second end region (312) of the wicking member (320), the heating element (320) extending between the first and second ends (321 , 322) thereof along a determined length; and first and second electrical contacts (330a, 330b) at the first end (321) of the heating element (320) and the second end (322) of the heating element (320) for connecting the heating element (320) to an electrical power supply; wherein an electrical resistance of the heating element (320) per unit length increases along the length of the heating element from the first end (321) to the second end (322) of the heating element such that a positive temperature gradient is achieved from the first end (321) to the second end (322) of the heating element (320) when an electrical current is passed through the heating element (320); wherein the vaporization chamber (200) comprises: a vaporization chamber inlet (201) in fluid communication with an air inlet (11) of the consumable article (10); and a vaporization chamber outlet (202) in fluid communication with a vapor outlet (12) of the consumable article (10), and wherein the vaporization chamber inlet (201) and the vaporization chamber outlet (202) are arranged relative to the heating arrangement (300) in the vaporization chamber (200) to establish at least one airflow over the heating arrangement (300) in a direction substantially parallel to the longitudinal axis of the heating arrangement (300) from the second end region (312) of the wicking member (310) to the first end region (311) of the wicking member (310) when air is drawn from the vapor outlet (12) of the consumable article (10).

2. A consumable article (10) according to claim 1 , wherein the wicking member (310) comprises a cylindrical rod (316) of a porous ceramic or a porous glass.

3. A consumable article (10) according to claim 1 or 2, wherein the heating element (320) is wound about a circumference of the wicking member.

4. A consumable article (10) according to any one of the preceding claims, wherein the heating element (320) is an electrically conductive strip (323), wire or track.

5. A consumable article (10) according to claim 4, wherein a cross-sectional area of the heating element (320) along a direction perpendicular to its longitudinal direction decreases along the length of the heating element (320) from the first end (321) to the second end (322) thereof.

6. A consumable article (10) according to any one of the preceding claims, wherein the positive gradient of the temperature of the wicking member (310) generated by the heating element (320) covers a temperature range including the first boiling point and the second boiling point.

7. A consumable article (10) according to any one of the preceding claims, wherein the wicking member (310) further comprises a longitudinal bore (317) defining an airflow path (203) extending through the wicking member (310) in a direction substantially parallel to the longitudinal axis of the wicking member (310).

8. A consumable article (10) according to claim 7, wherein the air inlet (11) and the vapor outlet (12) are in fluid communication with the bore (317) of the wicking member (310).

9. A consumable article (10) according to claim 7 or 8, wherein the wicking member (310) comprises a cylindrical rod (316) and the cylindrical rod (316) comprises: an inner tubular region (318) permeable to fluid, wherein an inner wall of the inner tubular region (318) defines the bore (317); and an outer tubular region (319) which is not fluid permeable and disposed concentrically around the inner tubular region (318) with an inner surface of the outer tubular region (319) in contact with the circumference of the inner tubular region (318).

10. An aerosol-generating system (1) comprising a consumable article (10) according to any one of the preceding claims.

11. An aerosol-generating system according to claim 10, wherein the aerosol-generating system (1) further comprises: a power supply (21) connectable to the resistive heating element (320) of the heating arrangement, through the first and second electrical contacts (330a, 330b); and a controller (22) for controlling delivery of electrical power from the power supply (21) to the heating element (320) to generate the temperature gradient in the wicking member in use.