EP3838012A1

EP3838012A1 - Heating apparatus

Info

Publication number: EP3838012A1
Application number: EP19218308.5A
Authority: EP
Inventors: Claude Zominy
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2021-06-23

Abstract

A heating apparatus for an aerosol generating device, comprising a first and second heating element supported by a housing, wherein the first and second heating elements each comprise a sheet of heating material and are arranged adjacent to each other, extending in the same direction along the length of the housing, a liquid supply configured to supply liquid to the first and second heating elements, an air flow path arranged to transport air over the first and second heating elements.

Description

The present invention relates to a heating apparatus for an aerosol generating device, such as an electronic cigarette.
Aerosol generating devices, such as electronic cigarettes, typically comprise a heating element arranged within a housing, wherein the heating element is configured to heat a vaporisable liquid to produce a vapour for inhalation by a user. Some existing devices are known to utilise a heating element comprised of a sheet of heating material, thereby providing a large surface area for heating. However, the provision of a sheet of heating material produces a bulky device which is undesirable particularly in terms of the portability of the aerosol generating device.
An object of the present invention is to address this issue.
According to an aspect of the present invention there is provided a heating apparatus for an aerosol generating device, comprising a first and second heating element supported by a housing, wherein the first and second heating elements each comprise a sheet of heating material and are arranged adjacent to each other, extending in the same direction along the length of the housing, a liquid supply configured to supply liquid to the first and second heating elements, an air flow path arranged to transport air over the first and second heating elements.
In this way, the size of the heating apparatus can be reduced without impairing the aerosol generating properties of the aerosol generating device. Specifically, by disposing two sheets of heating material adjacent to each other, the length of the housing can be shortened whilst providing the same surface area of heating. Alternatively, if the length of housing remains unchanged, the provision of two adjacent sheets will provide an increased surface area of heating, and thus improved vapour generating properties.
The sheets of heating material are preferably arranged with the sides of larger surface area adjacent to each other, i.e. the major sides of the first sheet are aligned parallel with the major sides of the second sheet.
Preferably, the sheets of heating element may comprise one or more slots extending inwardly from at least one edge of each sheet. In one example, each sheet of heating element may be formed such that it follows a serpentine path. In this way, a meandering current path may be provided along the heating element, resulting in different concentrations of current along the length of the heating element. In use, areas of relatively high current density will become hotter than areas of relatively low current density, thus establishing a temperature gradient across the heating element.
It should be understood that, in use, the liquid will flow from the sides, or edges, of the heating element in direct communication with an e-liquid (aerosol generating liquid) in the liquid store and be wicked toward the centre of the heating element by capillary action. A temperature gradient is provided in the heating element to improve the wicking process and optimise aerosol generation. The temperature gradient occurs when there are zones or areas in the heating element with reduced material densities. The reduced material densities can be obtained by having, for example, a flat electrical conductive element with hole/slots distributed in the element, wherein the distance between two holes/slots is reduced compared to the remaining part of the element. Therefore a higher material density zone is provided at the sides or edges of the heating element and a lower material density zone is provided toward or at the central region of the heating element. This means that the edges of the heating element will be cooler than the central reduced material density zone of the heating element. A heating element may be shaped, patterned or otherwise designed in a way to provide these different material density zones in order for a temperature gradient to form during use.
It should also be understood that components in the e-liquid with a lower temperature of evaporation will heat first at the edges of the heating element, followed by components in the e-liquid with higher evaporation temperatures which will be vaporised when they reach central areas or zones in the heating element which exhibit higher temperatures. In this way the temperature operation of the device can be lowered, which improves the heat distribution and optimises the vaporization, meaning that finer droplets particles are generated.
Preferably, the liquid supply at least partially surrounds the housing and is configured to directly interface with the first and second heating element along the length of the housing. In this way, a compact device is provided which delivers a reliable supply of liquid to the heating element along the length of the housing. This ensures a consistent vapour is generated and delivered to the user. Moreover, direct interfacing of the heating element with the liquid supply removes the requirement for an additional wick component, thereby reducing the cost and complexity of the heating apparatus.
The liquid supply may be a liquid store, i.e. a container arranged to hold an aerosol generating liquid, which is arranged such that the heating element is in contact with the liquid in use. In this way, liquid form the liquid store is drawn directly through the heating element as liquid is vaporised.
Preferably, the sheets of heating material each comprise a wicking structure for transporting liquid from the liquid supply by capillary action. A sheet can be formed by a combination of a plate and a mesh or by a mesh only. The sheets of heating material may each comprise a mesh of conductive fibres, for example steel fibres. In this way, the heating element also acts as a wick, thereby removing the requirement for an additional discrete wick element, and reducing the total number of components. This reduces the cost of manufacture and also leads to an improved efficiency of the heating operation.
In one example, the mesh may be a sintered mesh with a random arrangement of fibres. In another example, the mesh of fibres may comprise a regular woven pattern of fibres.
Preferably, the housing comprises a first portion and a second portion that cooperatively engage along the length of the housing, and wherein the first and second heating elements are supported between the housing portions. In this way, the heating elements are securely supported within the housing, whilst also enabling the supply of liquid to the heating elements along the entire length of the housing.
The housing may comprise a third portion arranged between the first and second portion, wherein the housing portions cooperatively engage along the length of the housing, wherein the first heating element is supported between the first and second portions, and wherein the second heating element is supported between the second and third portions. In this way, additional structural support is provided to the heating elements, and two or more separate vaporisation chambers may be formed between the respective housing portions. Furthermore, the air flow path may pass over both sides of each sheet of heating material, i.e. a greater surface area of each heating element is exposed to the air flow path. In this way, a greater volume of vapour may be extracted into the air flow path.
Preferably, the sheets of heating material are substantially parallel. In this way, the packing efficiency of the heating apparatus is increased.
Preferably, the first and second heating elements are arranged to define a gap between the sheets of heating material.
In one example, the gap may comprise a conducting material. In another example, the gap may comprise a wicking material. In this way, utilisation of space within the heating apparatus is maximised whilst also providing additional functionality or improved efficiency of the aerosol generating device.
In another example, the gap may comprise an air gap comprising a portion of the air flow path. In this way, the air flow path may be arranged such that air is passed directly between the planar surfaces of both sheets and the vaporised liquid may be collected in the air flow path, thereby providing an optimal heating operation.
At least one of the sheets of heating material may be folded about a fold line, wherein the fold line lies parallel to the length of the housing. In this way, the design freedom is improved with regards to the shape and structure of the housing. Moreover, the spatial efficiency of the heating apparatus may be enhanced.
The heating apparatus may comprise a support structure extending adjacent to the fold line. In this way, a more robust structure is provided which is less prone to damage by a user.
The support structure may be configured to conduct electricity to the adjacent sheet of heating material. In this way, a more consistent heating operation is ensured along the length of the heating element. Current may be supplied to the heating element along its entire length, such that defects within the heating element will not impede the overall flow of current. Furthermore, current may be supplied preferentially to specific regions of the sheet of heating material, thereby preferentially heating these areas and creating temperature gradients which improve the wicking function of the heating element.
In one example, each sheet of heating material is folded about a respective fold line lying parallel to the length of the housing, each having a support structure extending adjacent to the fold line, and wherein the housing comprises four portions which cooperatively engage at four interfaces along the length of the housing, wherein the edges of the sheets of heating material extending along the length of the housing are supported between the interfaces respectively. In this way, the area available for liquid ingress is increased, thereby providing a greater rate of liquid transport to the heating element and improving overall aerosol generating properties.
In one arrangement, the heating element may comprise a resistive heating element. In another arrangement, the heating element may comprise an inductive heater. Alternatively, the heating element may comprise an induction heated device, which includes a generator for generating an alternating electromagnetic field and one or more susceptors which generate heat used to vaporize the substrate (the e-liquid) when energized by the generated alternating electromagnetic field) or light heated devices (in which a light source such as a laser or high power LED directs light to an absorber element which is heated by the light absorbed from the light source in order to vaporize the liquid.
According to another aspect of the invention there is provided an aerosol generating device comprising a heating apparatus as set out above.
According to another aspect of the invention there is provided a consumable for an aerosol generating device, the consumable comprising a heating apparatus as set out above.
Embodiments of the invention are now described, by way of example, with reference to the drawings, in which:

Figure 1 is a schematic view of a heating apparatus comprising three housing portions for an aerosol generating device in an embodiment of the invention;
Figure 2 is a schematic view of a heating apparatus comprising two housing portions for an aerosol generating device in an embodiment of the invention; and
Figure 3 is a cross-sectional view of a heating apparatus with four housing portions and two folded heating elements in an embodiment of the invention.
Figure 4A is a schematic top view of a heating element in an embodiment of the invention.
Figure 4B is a schematic top view of a heating element in an alternative embodiment of the invention

Figure 1 shows a heating apparatus 2 in an embodiment of the invention that comprises a first heating element 4, a second heating element 6, a liquid store 8, and a housing 10. The heating apparatus is configured to be set in an aerosol generating device comprising a battery and a mouthpiece. In some examples, the heating apparatus 2 may be or may be comprised in a replaceable cartridge or consumable.
In use, the first and second heating elements 4 and 6 are arranged to receive electrical energy from the battery in order to generate an aerosol by heating an aerosol generating liquid. The aerosol generating liquid is drawn onto the first and second heating elements 4 and 6 from the liquid store 8 via capillary action. Airflow channels 18a, 18b, 18c are provided in the housing 10, and configured to, on user inhalation, direct air from outside the heating apparatus 2 through the airflow channels 18 and toward the mouthpiece of the aerosol generation device. This means that aerosol that has been generated by heating aerosol generating liquid on the first and second heating elements 4 and 6 will be carried along the airflow channels 18 to exit the device.
The first and second heating elements 4 and 6 each comprise a sheet of electrically conductive fibres. The term "sheet" refers to a planar shape with a thickness many times smaller than its length or breadth. The sheet is a piece of material with an extensive surface area, which in some embodiments may be flat, but in other embodiments may be folded or warped. However, the skilled person will appreciate a non-planar arrangement of electrically conductive fibres may also be used as a heating element. The fibres form a porous network of fibres, thereby providing each heating element 4 and 6 with wicking properties. Hence, the provision of an additional wicking element to transport vaporisable liquid from the liquid store 8 is not required within the heating apparatus 2.
The fibres of the first and second heating elements 4 and 6 may be made of a metal, such as stainless steel, non-stainless steel, iron, copper, tungsten, aluminium, brass, Nichrome, Kanthal, Cupronickel and other alloys, or any other metal (element, compound or alloy). Alternatively, the fibres may be made of a non-metal material such as molybdenum disilicide, silicon carbide and other ceramics or semiconductors, or any other non-metal.
In one example, the first and second heating elements 4 and 6 may each comprise a sintered mesh with a random arrangement of fibres. In another example, the first and second heating elements 4 and 6 may each comprise a regular woven pattern of fibres.
The sheets of first and second heating elements 4 and 6 are arranged to lie parallel to one another and are mounted in the housing 10. The housing 10 includes a first housing portion 12 placed above the top major side of the first heating element 4 and a second housing portion 14 placed below the lower major side of the second heating element 6. A third housing portion 16 is positioned between the first and second heating elements 4 and 6 such that each heating element 4 and 6 is respectively held or clamped between two housing portions. The housing 10 acts as a vaporisation chamber which is configured to collect generated aerosol within the airflow channels 18a, 18b and 18c.
Each of the first and second heating elements 4 and 6 are exposed to the liquid store 8 which surrounds the housing 10. The edge portions of the first and third housing portions 12 and 16, when constructed, form a gap in which the first heating element 4 is held, thereby exposing the edges of the first heating element 4 to the liquid store 8 along the length of the housing 10. Similarly, the edge portions of the second and third housing portions 14 and 16, when constructed, form a gap in which the second heating element 6 is held, thereby exposing the edges of the second heating element 6 to the liquid store 8 along the length of the housing 10. This configuration allows aerosol generating liquid from the liquid store 8 to be uniformly and reliably supplied to the first and second heating elements 4 and 6 along their length, and to be further drawn across the heating elements 4 and 6 via capillary action.
In one example, the edges of the first and second heating elements 4 and 6 may extend beyond the outer limits of the housing 10. In an alternative example, the edges of the first and second heating elements 4 and 6 may be level or retracted from the outer limits of the housing 10, and aerosol generating liquid from the liquid store 8 configured to penetrate within the gaps between housing portions 12, 14 and 16. In either case, the edges of the sheets of first and second heating elements 4 and 6 are in direct fluid communication with the liquid store 8, such that an additional wicking element is not required to transport vaporisable liquid from the liquid store 8 to the heating elements 4 and 6. In one example, the thickness of the each heating element 4 and 6 may be slightly smaller than the gap between housing portions in order to provide an additional capillary channel for supplying liquid from the liquid store 8 to each heating element 4 and 6.
The provision of two parallel sheet of heating elements 4 and 6 allows for a reduction in the size of the heating apparatus 2 in comparison to a heating apparatus containing only one heating element, whilst maintaining or increasing the surface area for heating. Moreover, the arrangement of multiple airflow paths 18a, 18b, 18c within the heating apparatus 2, provides an additional level of control over the vapour generating properties of the device, which can be tailored according to operational requirements.
In this example, the heating elements 4 and 6 each comprise a uniform sheet of heating material. In alternative examples, the heating elements 4 and 6 may each comprise a non-uniform sheet of heating material, for example the heating element sheets may be formed such that they follow a serpentine path. In this way, a meandering current path may be provided along each heating element, resulting in different concentrations of current along the path, and the establishment of temperature gradients across the heating elements.
Within the housing 10, the space between the first and second heating elements 4 and 6 comprises empty space, thereby forming airflow path 18b. Alternatively, a piece of conducting material may be disposed between the first and second heating elements 4 and 6. Alternatively, a piece of wicking material may be disposed between the first and second heating elements 4 and 6. These alternative configurations provide compact arrangements of functional components, such that the efficiency or vapour generating properties of the heating apparatus 2 may be improved.
The heating apparatus 2 is substantially cylindrical. However, it will be appreciated that the heating apparatus 2 may be formed in various different shapes according to operational and design requirements.
Figure 2 shows a schematic view of a heating apparatus 20 in an alternative embodiment of the invention, wherein the housing 10 comprises only two housing portions 12 and 14.
The top major side of the first sheet of heating element 4 is held by the first housing portion 4 and the lower major side of the second sheet of heating element 6 is held by the second housing portion 6. However, unlike in Figure 1, a third housing portion is not disposed between the first and second heating elements 4 and 6. Instead, a connecting article 22 is sandwiched between the first and second sheets of heating element 4 and 6.
In one example, the connecting article 22 may be a piece of wicking material. Therefore, as the connecting article 22 interfaces with the liquid store 8 along the length of the housing 10, the piece of wicking material may enhance the ingress of vaporisable liquid to the first and second heating elements 4 and 6 via capillary action. In another example, the connecting article 22 may be a conducting material. In an alternative example, the connecting article 22 may be absent entirely.
Figure 3 shows an end-on cross-sectional view of a heating apparatus 24 in an embodiment of the invention. The heating apparatus 24 comprises four housing portions 26, 28, 30, 32, a first heating element 34, a second heating element 36, a first support structure 38, and a second support structure 40.
The four housing portions 26, 28, 30, 32, when constructed, form a generally cylindrical housing with four interfaces running along the length of the housing. Two rod- like support structures 38 and 40 are disposed within the housing and arranged such that they extend along the length of the housing.
The first and second heating elements 34 and 36 each comprise a sheet of heating material folded about the first and second support structures 38 and 40 respectively. Hence, the fold line or maximum point of curvature of the first and second heating element 34 respectively coincides with the first and second support structures 38 and 40. The support structures 38 and 40 provide structural support to each sheet of heating material and may be used to deliver electrical current to the heating elements along their length. In alternative embodiments, the support structures 38 and 40 may be absent.
As a result of the folding of the sheets of heating material, a more compact heating apparatus may be provided which is operable to receive vaporisable liquid at multiple locations around the edge of the housing. Hence, an increased rate of liquid transport to the heating elements 34 and 36 may be provided. Moreover, folded sheets of heating material provide more design freedom, allowing the shape and structure of the heating apparatus and aerosol generating device to be tailored according to operational requirements. Although the housing portions 26, 28, 30, 32 form a housing that is generally cylindrical in shape, the skilled person will appreciate that the housing may be formed in various different shapes.
Moreover, the skilled person will appreciate that the number of heating elements in the heating apparatus 24, or heating apparatus 2, may be further increased to improve device compactness and efficiency.
Each heating element in the heating apparatus 24 or 2 may possess the same physical characteristics (e.g. thickness, density, material etc.). Alternatively, the heating elements may possess different physical characteristics (e.g. thickness, density, material etc.), thereby allowing the vapour properties or droplet size to be tailored through the choice and/or combination of physical characteristics of each heating element. For example, heating elements 34 and 36 in Figure 3 may be comprised of different materials.
Figures 4A and 4B show different configurations of a heating element where patterns are used to provide different zones of material densities in order to create temperature gradients across the heating elements according to the present invention.
Figure 4A shows a schematic top view of a heating element 41 in an embodiment of the invention. The heating element 41 has two contact ends 42 which may be connected to a power source (not shown). In use, an electric current passes through the heating element 41 between the contact ends 42, thereby causing the heating element 41 to generate heat. The heating element 41 also includes a plurality of slots 44, which are arranged to cause an electric current to follow a serpentine path as it flows between the two contact ends 42. This results in different concentrations of current along the path, and the establishment of temperature gradients across the heating element. In alternative arrangements, the heating element 41 may comprise a simple shape, such as a rectangle, and different current concentrations may be established across the heating element 41 by alternative means.
Figure 4B shows a schematic top view of a heating element 45 in an alternative embodiment of the invention. The heating element 45 has a plurality of slots 46 arranged as pairs of slots, where the slots in a pair are oppositely arranged along the length of the heating element 45. The heating element 45 also comprises a plurality of holes 48 positioned within the central portion of the heating element 45. The holes 48 and the slots 46 are provided in an alternating pattern along the length of the heating element 45 to control the flow path of an applied electric current. The flowing current will follow a meandering or square-wave path as it travels across the heating element 45 and flows around the one or more holes 48 and slots 54.

Claims

A heating apparatus for an aerosol generating device, comprising;
a first and second heating element supported by a housing,
wherein the first and second heating elements each comprise a sheet of heating material and are arranged adjacent to each other, extending in the same direction along the length of the housing;
a liquid supply configured to supply liquid to the first and second heating elements;
an air flow path arranged to transport air over the first and second heating elements.
The heating apparatus of claim 1, wherein the liquid supply at least partially surrounds the housing and is configured to directly interface with the first and second heating element along the length of the housing.
The heating apparatus of claim 1 or claim 2, wherein the sheets of heating material each comprise a wicking structure for transporting liquid from the liquid supply by capillary action.
The heating apparatus of any preceding claim, wherein the sheets of heating material each comprise a mesh of conductive fibres.
The heating element of claim 4, wherein the mesh is a sintered mesh with a random arrangement of fibres.
The heating apparatus of any preceding claim, wherein the housing comprises a first portion and a second portion that cooperatively engage along the length of the housing, and wherein the first and second heating elements are supported between the housing portions.
The heating apparatus of claim 6, wherein the housing comprises a third portion arranged between the first and second portion, wherein the housing portions cooperatively engage along the length of the housing, wherein the first heating element is supported between the first and second portions, and wherein the second heating element is supported between the second and third portions.
The heating apparatus of any preceding claim, wherein the sheets of heating material are substantially parallel.
The heating apparatus of any preceding claim, wherein the first and second heating elements are arranged to define a gap between the sheets of heating material.
The heating apparatus of claim 9, wherein the gap comprises a conducting material and/or a wicking material.
The heating apparatus of claim 9, wherein the gap comprises an air gap comprising a portion of the air flow path.
The heating apparatus of any preceding claim, wherein the sheets of heating element each comprise one or more slots extending inwardly from at least one edge of each sheet.
The heating apparatus of any preceding claim, wherein at least one of the sheets of heating material is folded about a fold line, wherein the fold line lies parallel to the length of the housing.
The heating apparatus of claim 13, further comprising a support structure extending adjacent to the fold line.
The heating apparatus of claim 14, wherein the support structure is configured to conduct electricity to the adjacent sheet of heating material.