Aerosol-Generating Device and Heater Assembly

The present disclosure relates to an aerosol-generating device for coupling to a cartridge; a heater assembly for an aerosol-generating device; a cartridge; and an aerosol-generating system.

Aerosol-generating systems configured to generate inhalable aerosol from an aerosol-forming substrate are known in the art. Many prior aerosol-generating systems comprise an aerosol generating-device that is couplable to a cartridge. A typical cartridge for use with an aerosol-generating device comprises an aerosol-forming substrate and a heater assembly, where the heater assembly comprises a heating element. The cartridge may further comprise a wicking material adjacent to or in contact with the aerosol-forming substrate and the heating element. The wicking material is configured to transport aerosol-forming substrate to the heating element. In use, the heating element is configured to vaporise the aerosol-forming substrate. An airflow is provided past the heating element to entrain the generated vapour. In the airflow the vapour is condensed and an aerosol is formed. The aerosol may then be inhaled by a user. The cartridge is removably couplable to the aerosol-generating device. The aerosol-generating device typically comprises a power supply that is configured to supply power to the heating element, via electrical connectors.

In aerosol-generating systems of this type, it is desirable to minimise the amount of power required to heat the aerosol-forming substrate. This is particularly desirable in portable aerosol-generating systems where the system comprises a portable power supply such as a battery. To minimise power usage and efficiently heat the aerosol-forming substrate the heating element may be in direct contact with the wicking material and therefore the aerosol-forming substrate.

Repeated use of the aerosol-generating system, over many heating cycles, requires repeated heating of the wicking material. This may lead to degradation of the wicking material over a period of time. Degradation can be caused by heating of the wicking material. Degradation can also be caused by chemical interactions between the aerosol-forming substrate and the wicking material, mechanical stress on the wicking material and particle accumulations on the surface of the wicking element. The degradation of the wicking material may lead undesirable effects such as less efficient heat transfer between the heating element and the wicking material, less efficient transfer of aerosol-forming substrate from the wicking material to the heating element, or the generation of aerosols comprising unfavourable components. In addition, during use of an aerosol-generating system, hotspots may occur in the heating element. Hotspots are regions of the heating element that have a temperature higher than the average temperature of the heating element, during operation. These hotspots may lead to degradation of the wicking material.

As a result of degradation, the wicking material limits the lifetime of any cartridge.

It would be desirable to provide an aerosol-generating system, and an aerosol-generating device for such a system, which requires less frequent disposal of the heater assembly.

According to a first aspect of the present disclosure, there is provided an aerosol-generating device for coupling to a cartridge. The aerosol-generating device may comprise a cartridge coupling portion for engaging a cartridge containing an aerosol-forming substrate. The aerosol-generating device may comprise an air flow passage defined between an air inlet and an air outlet. The aerosol-generating device may further comprise a heater assembly, the heater assembly comprising a fluid permeable heating element configured to heat an aerosol-forming substrate from the cartridge, wherein the heater assembly comprises a first side and a second side, the first side opposing a second side, wherein the first side forms at least part of a surface of a wall of the air flow passage and wherein the second side forms part of the cartridge coupling portion and is configured to contact the cartridge to receive the aerosol-forming substrate.

The heater assembly may be arranged within the device to couple with a cartridge. The aerosol-generating device may be reusable. The cartridge may be disposable. Advantageously, when the cartridge needs to be disposed of, the cartridge may be uncoupled from the device, disposed of, and replaced. The heater assembly may be retained in the device, instead of being removed and disposed of. Therefore, the heater assembly may be reused. The heater assembly may be more costly to manufacture in comparison to elements of a cartridge, so it is advantageous to prevent unnecessary disposal of the heater assembly.

The air inlet may be defined in a side wall of the device. The air outlet may be defined in an end wall of the device. The side wall of the device may extend perpendicular to the end wall of the device. The configuration of the air inlet and air outlet may allow air to flow past the heater assembly and therefore entrain vapourised aerosol-forming substrate. The air outlet may be configured to align with an opening in the cartridge. Entrained vapourised aerosol-forming substrate may aerosolise in the in the air flow and pass through the air outlet into the cartridge.

The second side of the heater assembly may be situated outside of the airflow passage. The second side of the heater assembly may be configured so that at least a portion of the second side is contact with a wicking material of the cartridge.

The heating assembly may be a planar heater assembly. The heating element may be a planar heating element. The heating element may be perpendicular to a longitudinal axis of device.

The heating element may comprise at least one filament. The heating element may comprise a plurality of electrically conductive filaments. The term “filament” as used herein refers to an electrical path arranged between two electrical contacts. The at least one filament may have a round, square, flat or any other form of cross-section. The heating element may be an array of filaments, for example arranged parallel to each other. Preferably, the filaments may form a mesh.

The heating element may be a mesh heating element. The heating element may comprise a mesh. The heating element may allow vapour to flow from the second side of the heater assembly to the first side of the heater assembly. The heating element may not allow liquid to flow from the second side of the heating element to the first side of the heating element.

The electrically conductive filaments may define interstices between the filaments and the interstices may have a width of between 10 micrometres and 100 micrometres. Preferably, the filaments give rise to capillary action in the interstices, so that in use, liquid to be vaporized is drawn into the interstices, increasing the contact area between the heating element and the aerosol-forming substrate.

The electrically conductive filaments may form a mesh of size between 60 and 240 filaments per centimetre (+/−10 percent). Preferably, the mesh density is between 100 and 140 filaments per centimetres (+/10 percent). More preferably, the mesh density is approximately 115 filaments per centimetre. The width of the interstices may be between 100 micrometres and 25 micrometres, preferably between 80 micrometres and 70 micrometres, more preferably approximately 74 micrometres. The percentage of open area of the mesh, which is the ratio of the area of the interstices to the total area of the mesh may be between 40 percent and 90 percent, preferably between 85 percent and 80 percent, more preferably approximately 82 percent. The electrically conductive filaments may have a diameter of between 8 micrometres and 100 micrometres, preferably between 10 micrometres and 50 micrometres, more preferably between 12 micrometres and 25 micrometres, and most preferably approximately 16 micrometres.

The area of the mesh of electrically conductive filaments may be small, for example less than or equal to 50 square millimetres, preferably less than or equal to 25 square millimetres, more preferably approximately 15 square millimetres. The size is chosen such to incorporate the heating element into a handheld system. Sizing of the mesh, array or fabric of electrically conductive filaments less or equal than 50 square millimetres reduces the amount of total power required to heat the mesh of electrically conductive filaments while still ensuring sufficient contact of the mesh of electrically conductive filaments to the aerosol-forming substrate. The mesh of electrically conductive filaments may, for example, be rectangular and have a length between 2 millimetres to 10 millimetres and a width between 2 millimetres and 10 millimetres. Preferably, the mesh has dimensions of approximately 5 millimetres by 3 millimetres.

The heating element may comprise a porous material. Advantageously, a mesh heating element, a heating element comprising a mesh, or a heating element comprising a porous material may provide a large surface area in contact with the liquid aerosol-forming substrate. This large surface area may provide efficient vaporisation of the liquid aerosol-forming substrate.

Preferably, the heating element comprises a single filament. A heating element comprising a single filament may also be referred to as a heating wire. The single filament may have a diameter of 0.1 millimetres to 0.5 millimetres. The single filament may have a diameter of 0.02 millimetres to 0.2 millimetres.

The heating element, or portions thereof, may comprise an electrically resistive material. The heating element may be configured to be resistively heated. In other words, the heating element may be configured to generate heat when an electrical current is passed though the heating element. The heating element, or portions thereof, may comprise or be formed from any material with suitable electrical and mechanical properties, for example a suitable, electrically resistive material. Suitable materials may include but are not limited to: semiconductors such as doped ceramics, electrically “conductive” ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum and metals from the platinum group. Examples of suitable metal alloys include Constantan, nickel-, cobalt-, chromium-, aluminium-, titanium-, zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, Timetal®, iron-aluminium based alloys and iron manganese-aluminium based alloys. Timetal® is a registered trade mark of Titanium Metals Corporation, 1999 Broadway Suite 4300, Denver Colorado. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required. The heating element, or portions thereof, may comprise a metallic etched foil insulated between two layers of an inert material. In that case, the inert material may comprise Kapton®, all-polyimide or mica foil. Kapton® is a registered trade mark of E. I. du Pont de Nemours and Company, 1007 Market Street, Wilmington, Delaware 19898, United States of America.

Preferably, the heating element comprises stainless steel. Stainless steel may provide a heating element with desirable mechanical properties, corrosion resistance and high electrical resistance.

The heating element may comprise a ferrimagnetic material. The heating element may comprise a ferromagnetic material. The heating element may be formed of a ferrimagnetic or ferromagnetic material. At least a portion of the heating element may be formed of a ferrimagnetic or ferromagnetic material. The electrical resistance of the heating element may increase as the frequency of an alternating current applied to the heating element is increased. The use of a heating element comprising ferrimagnetic or ferromagnetic material may advantageously increase the electrical resistance of the heating element, and therefore locally generating more heat, without the need to reduce the diameter of the heating element. Reducing the diameter may compromise the mechanical strength of the heating element.

The electrical resistance of the heating element may be between 0.1 Ohms and 5 Ohms. Preferably the electrical resistance of the heating element may be between 0.4 Ohms to 2 Ohms.

The heating element may be coated with a corrosion resistant material. A corrosion resistant coating may increase the life span of the heating element. The heating element may be coated with a ceramic material.

The heater assembly may be configured to contact a wicking portion of the cartridge. The heating element may be configured to contact a wicking portion of the cartridge.

The heater assembly may comprise a support element. The support element may provide mechanical support to the heating element. The support element may laterally support the heating element. The support element may comprise a thermal conduction material in thermal contact with the heating element. The support element may be configured to absorb heat produced by the heating element. Advantageously, the presence of a support element comprising a thermal conduction material may reduce the temperature of the heating element in regions where the heating element is not in contact with a wicking material or aerosol-forming substrate. This may reduce overheating of the heating element, preferably prolonging the life of the heating element. In addition, this may reduce or slow down degradation of a wicking material in contact with the heating element.

The support element may comprise at least one of aluminium, copper, brass, gold, silver or thermally conductive ceramic. Advantageously these materials are highly thermally conductive.

The thermal conductivity of the support element may be at least 10 W/mK. The thermal conductivity of the support element may be at least 50 W/mK. The thermal conductivity of the support element may be at least 200 W/mK.

The support element may comprise at least one supporting pin. The support element may comprise at least 4, at least 6, at least 8, at least 10 or at least 12 supporting pins. The heating element may be engaged with the at least one supporting pin. The heating element may be figured to be wound or wrapped around the at least one supporting pin. The heating element may be a heating wire wherein the heating wire passes around each of the supporting pins.

The at least one supporting pin may be cylindrical. The cross-section of the at least one supporting pin may have a diameter of 0.5 millimetres to 5 millimetres, preferably 1 millimetres to 2 millimetres.

The heater assembly may further comprise a heater holder. The heater holder may provide mechanical support to the support element. The heater holder may comprise an upper plate and a lower plate. The heating element may be situated between the upper plate and the lower plate. Advantageously, a heater holder comprising an upper plate and a lower plate with a heating element situated therebetween may be straightforward to manufacture.

The heater holder may have an aperture defined therethrough. The aperture may be defined through the upper plate and the lower plate. The heating element may span at least part of the aperture. The aperture may be configured to allow aerosol-forming substrate to flow between the second side of the heater assembly and the first side of the heater assembly. The aperture may be configured to allow gases, such as air and vapour generated from the aerosol-forming substrate, to flow between the second side of the heater assembly and the first side of the heater assembly.

The aerosol-generating device may further comprise a first electrical connector and a second electrical connector. The first and second electrical connectors may be configured to supply power to the heating element. The electrical connectors may be situated in electrical contact with the heating element. The first electrical connector may comprise a first contact pad and the second electrical connector may comprise a second electrical contact pad, wherein the first and second electrical contact pads are configured to be in electrical contact with the heating element. The electrical connectors may extend outside of the heater assembly to allow for the provision of electrical energy to the electrical connectors and thus the heating element, from a power supply. In operation, the heating element may be heated as a result of electrical current passing through the heating element. The first electrical connector and the second electrical connect may be positioned on opposite sides of the heating element. An electrical current passing from the first electrical connector to the second electrical connector may pass through the heating element.

The support element may be situated adjacent to the aperture. The support element may be situated as close as possible to the aperture. The distance between the support element and the aperture may be less than 2 mm, preferably less than 1 mm. Advantageously, this may minimise the total length of the heating element. The length of the heating element that is not spanning the aperture may also be reduced. The percentage of the heating element that is spanning the aperture may be increased. Increasing the percentage of the heating element that is spanning the aperture may increase the percentage of the second side of the heating element that is configured to contact the cartridge to receive the aerosol-forming substrate. Advantageously, less material may be needed to manufacture the heating element while not reducing performance of the heating element. The electrical connectors may be in electrical contact with the heating element at distance further from the aperture than the distance of the support element from the aperture. The first electrical connector may be in electrical contact with a first end of the heating element. The second electrical connector may be in contact with a second end of the heating element. The electrical connectors may be connected with the heating element in series. Preferably, the heating element may have a diameter of 0.1 millimetres to 0.5 millimetres.

The first and second electrical connectors may be situated adjacent to the aperture. The support element may be in contact with the heating element at a distance further from the aperture than the distance of the first and second electrical connectors from the aperture. The first and second electrical connectors may be situated as close as possible to the aperture. The distance between first electrical connector and the aperture may be less than 2 millimetres, preferably less than 1 millimetre. The distance between second electrical connector and the aperture may be less than 2 millimetres, preferably less than 1 millimetres. In this configuration, the length of the heating element between the first electrical connector and the second electrical connector is shorter than in the previous configuration. As a result, a small diameter of the heating element is selected. The first and second electrical connectors, preferably the first and second electrical contact pads, may be configured to absorb some of the heat produced by the heating element in operation. Advantageously, this may reduce the temperature of a portion of the heating element that is not in contact with, or configured to be in contact with, aerosol-forming substrate. The first and second electrical connectors, preferably the first and second electrical contact pads, may be in contact with the heating element at more than two positions on the heating element. The first and second electrical connectors, preferably the first and second electrical contact pads, may be connected with the heating element in parallel. Preferably, the heating element may have a diameter of 0.02 millimetres to 0.2 millimetres.

The cross-sectional area of the aperture may be from 4 square millimetres to 1000 square millimetres. Preferably, the cross-sectional area of the aperture may be from 9 square millimetres to 400 square millimetres. Most preferably, the cross-sectional area of the aperture may be from 16 square millimetres to 100 square millimetres. Any shape may be selected for the cross-section of the aperture. Preferably, the cross-section of the aperture may be circular, square, or rectangular. Advantageously, these cross-sectional shapes for the aperture may be simple to manufacture.

The heater holder may be electrically insulating. The heater holder may have a thermal conductivity of 1 W/mk or less. The heater holder may comprise a heat resistant polymer. The heater holder may comprise polyether ether ketone (PEEK). The heater holder may comprise liquid crystal polymer (LCP). The heater holder may comprise a ceramic. The heater holder may comprise alumina. The heater holder may comprise zirconia. Advantageously, these materials are able to withstand high temperatures.

The heating element may be, or may comprise, a susceptor material. The susceptor material may be configured to be inductively heated. In operation, the susceptor material may be heated by eddy currents induced in the susceptor material. Hysteresis losses may also contribute to the inductive heating.

The device may comprise no wicking element. After repeated heating of an aerosol-forming substrate in an aerosol-generating system, wicking elements may degrade more quickly compared to other components such as the heating element. The degraded wicking material may need replacing before other components of the system such as the heater assembly. Therefore, the device not having a wicking element may increase the lifetime of the device.

The heater assembly may comprise a compressible element. The compressible element may be configured to be compressed by the cartridge when the cartridge is received by the aerosol-generating device.

The compressible element may be a spring. The spring may be situated adjacent to or in contact with the lower plate of the heater holder. The compressible element may allow the heater assembly to move along a longitudinal axis of the device. In use, when a cartridge is attached to the device, the cartridge may provide a force to the heater assembly which moves the heater assembly. When the cartridge is coupled to the device, the spring may compress. When the cartridge is uncoupled from the device, the spring may expand. The spring may be positioned to act against the force provided by insertion of the cartridge. Advantageously, a close fit between the cartridge and the heater assembly may be achieved, reducing the likelihood of leakage of aerosol-forming substrate. A close fit may provide more efficient heating of the aerosol-forming substrate.

The aerosol-generating device may further comprise a power supply. The power supply may be a DC power supply. The power supply may be a battery. The battery may be a Lithium based battery, for example a Lithium-Cobalt, a Lithium-Iron-Phosphate, a Lithium Titanate or a Lithium-Polymer battery. The battery may be a Nickel metal hydride battery or a Nickel cadmium battery. The power supply may be another form of charge storage device such as a capacitor. The power supply may be configured to supply power to the heating element. This may heat the heating element.

The power supply may be configured to supply an alternating current. The power supply may comprise a direct current to alternating current (DC/AC) inverter for converting a DC current supplied by the DC power supply to an alternating current.

The power supply may be configured to supply power to the heating element to resistively heat the heating element. The power supply may be configured to supply power to the heating element to inductively heat the heating element.

The power supply may be electrically connected to the first and second electrical connectors. The power supply may be configured to supply power to the heating element via the electrical connectors. The power supply may be configured to supply power to the heating element by passing an electrical current through the heating element.

The aerosol-generating device may further comprise a control circuitry. The control circuitry may comprise a controller. The controller may be a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic control circuitry. The controller may be configured to control supply of power from the power supply. The controller may be configured to regulate the supply of power from the power supply to the heater assembly. Thus, the controller may control heating of the heating element.

The heating element may be airflow actuated. The heating element may be puff actuated. The aerosol-generating device may comprise a puff detector. The puff detector may be in communication with the control circuitry. The puff detector may be configured to detect when there is an airflow through the air flow passage. The control circuitry may be configured to activate the heating element when an airflow is detected.

The aerosol-generating device may be a handheld aerosol-generating device.

It would be desirable to provide a heater assembly where the likelihood of hotspots occurring is reduced in comparison to prior art systems.

According to a second aspect of the present disclosure, there is provided a heater assembly for an aerosol-generating device, the heater assembly may comprise a heater holder comprising an aperture, a heating element spanning at least part of the aperture, first and second electrical connectors in electrical contact with the heating element, and a support element comprising a thermal conduction material in thermal contact with the heating element. The heater assembly of the second aspect may comprise any of the features of the heater assembly described in relation to the first aspect of the disclosure. In addition, any of the features of the heater assembly of the second aspect may be equally applied to the heater assembly of the first aspect.

Advantageously, a support element comprising a thermal conduction material will conduct heat away from hotspots of the heating element. Thus, leading to a more uniform temperature along the heating element. This may reduce degradation of a wicking material that is adjacent to or in contact with the heating element during use of the heater assembly.