Heating unit with intumescent material insulation for aerosol-generating device

Abstract

To provide a heating unit with an intumescent material insulation for an aerosol-generating device.SOLUTION: The present invention relates to a heating unit for an aerosol-generating article. The heating unit comprising a heating oven configured to heat an aerosol-forming substrate of an aerosol generating article when the aerosol-forming substance is received in the heating oven. The heating oven is thermally insulated by a layer of an intumescent material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heating unit for an aerosol generating device. The heating unit comprises a furnace configured to heat an aerosol product article to generate an aerosol that is inhaled by a user. In particular, the present invention relates to such a furnace that is thermally insulated by a layer of intumescent material. The present invention further relates to a method for manufacturing such a heating unit, to such a heating unit and to the use of the layer of intumescent material as insulation for aerosol generating devices and systems. [Background technology]

[0002] Aerosol-generating devices, in particular electronic nicotine delivery systems (known as ENDS), have become popular worldwide over the past few decades. These devices are an alternative to traditional combustible tobacco products such as cigarettes.

[0003] Different types of aerosol-generating devices based on various aerosolization technologies and aerosol-generating substrates are currently available on the market. A particular subset of aerosol-generating devices are heated tobacco products, also known as "heat-not-burn" products and / or systems (HNB). These HNB systems can generate inhalable aerosols from heating a tobacco-containing substrate, usually in solid or powdered form. Such HNB systems require an electronic device containing a heating unit to heat the tobacco-containing substrate instead of burning tobacco as is done in conventional cigarettes.

[0004] The heating units described above are typically provided with a heating cavity or furnace into which an aerosol producing product (or consumable) containing tobacco can be inserted. The tobacco in the consumable is then heated until an aerosol is formed. The furnace generates high temperatures of about 250-400°C, which contribute to the rapid formation of an aerosol that can be inhaled by a user.

[0005] Furnaces require extensive insulation to protect the surroundings of the heating unit and / or the aerosol generating device from heating and to protect the user from potential injury when holding an aerosol generating device including such a furnace during use. Furthermore, the space between the furnace and its surroundings is typically limited, which makes the manufacturing and assembly of the heating unit and its insulation means, and / or the aerosol generating device difficult.

[0006] Conventional implementations of furnaces of HNB devices fail to address these challenges, or at least fail to address them adequately. As an example, foam insulation is conventionally applied, which requires tape to precisely fix and / or position the foam insulation to insulate the furnace. Such conventional implementations can easily lead to loss of insulation of the furnace during normal use. In addition, it is difficult to insulate the entire outer surface of the furnace. Thus, thermal insulation cannot be reliably guaranteed, which also makes the heating of the aerosol product less efficient. Another consequence may be unintended heating of the heating unit. Furthermore, the manufacturing and assembly process of such conventional furnaces is subject to space limitations, which often represent a bottleneck when it comes to precise positioning and attachment of wires around the furnace. Thus, the manufacturing and assembly process of conventional furnaces is hindered and cannot be easily automated. Rather, skilled labor is required, and as a result, the process is time-consuming and costly.

[0007] There is therefore a significant need for improvements in such heating units and in aerosol generating devices including these heating units.

[0008] Against this background, the object of the present invention is to address one or more or all of the above-mentioned problems. In particular, the object of the present invention is to provide an improved heating unit with a furnace for aerosol product products. The resulting furnace has enhanced thermal insulation, especially at its periphery. Accordingly, it is an object to prevent heat radiation or heat loss to the furnace's surroundings. In addition, it is an object to overcome the space limitations associated with conventional heating units. Thus, a heating unit is provided that can be manufactured and assembled in a simpler manner. Furthermore, the manufacturing and assembly can be more easily automated than existing methods. Accordingly, it is also an object to facilitate an improved, cost-effective and fast process of manufacturing and assembly of such heating units.

[0009] These and other objects that will become apparent from the following description are solved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims. Summary of the Invention [Means for solving the problem]

[0010] General aspects A first embodiment of the present invention is directed to a heating unit for an aerosol product article, the heating unit including a furnace configured to heat an aerosol-forming substrate of the aerosol product article upon receipt therein, the furnace being thermally insulated by a layer of expansive material.

[0011] The heating unit may be used in an aerosol generating device that is held by a user. The aerosol generating device may therefore be a portable and / or handheld aerosol generating device that can be comfortably held by a user. For example, the aerosol generating device may be held between the fingers and / or in the palm of one hand.

[0012] The heating unit may be configured to generate an aerosol for inhalation by a user while the consumable, i.e., aerosol-producing, item is received (at least partially) within the furnace.

[0013] An "aerosol product" may also be referred to as a consumable product or a consumable item. Such an aerosol product may include an aerosol-forming substrate, which may be heated to generate an aerosol and / or vapor that can be inhaled by a user.

[0014] The term "aerosol-forming substrate" is used to describe a substrate capable of releasing a volatile compound that can form an aerosol upon heating. The aerosol generated from a consumable aerosol-forming substrate may or may not be visible and may include vapor, e.g., fine particles of a substance in a gaseous state. The generated aerosol may also include droplets of gas and condensed vapor. The aerosol-forming substrate may be provided in a solid, gel, foam, or liquid form. In one example, the aerosol-forming substrate may be provided as a combination of the forms described herein. For example, the aerosol-forming substrate may include tobacco in leaf or some other solid form, such as reconstituted cast and / or pressed tobacco sheet. The tobacco may also be ground tobacco in a fine powder form or in a foam or paste form.

[0015] The "expansive material" as used herein may also be referred to as a reactive material. The behavior of such materials may be based on the principle of expansion. In this sense, the expansion of a material may be understood as expanding when the material is exposed to elevated or high temperature conditions, i.e., exposed to heat. Such expansion under high temperature conditions may be greater than simply as a result of the thermal expansion coefficient of the material. As an example, when a certain temperature (trigger temperature) is reached, the expansive material may expand and therefore swell significantly. This may be caused by a chemical process initiated by heat. It is also possible that the expansion occurs rapidly. Under chemical reactions, char may be produced. Thus, the expansive material may also be referred to as a "char-swelling" material. Thus, the expansive material may form an insulating material, such as an insulating foam, when exposed to heat and / or high temperature conditions. Thus, the expansive material may provide improved thermal insulation. Another advantage of the expansive material is that it offers a safe chemical profile with respect to handling and the environment (e.g., halogen-free protection), which is highly valued by users. As used herein, an expansion material may refer to a material that remains in a substantially expanded shape or state (although small variations may still occur) even when no longer exposed to heat. The expansion of an expansion material may also be understood as the thickness and / or volume of the material increasing and / or the density of the material decreasing.

[0016] The leavening material may include any suitable material capable of expanding as described above. Such heat may be generated by a heating oven during normal use. By way of example, the leavening material includes an organic compound. This may be starch or one or more pentaerythritols (or other types of polyalcohols). The leavening material may also include an acid such as ammonium polyphosphate. The leavening material may also include a foaming agent such as melamine. Optionally, the leavening material may include a binder such as soy lecithin. By way of example, a material including toluene, melamine, and N-butyl acetate (e.g. "char 22" or "char 22 pittura" by iris coatings srl) may be used as the leavening material.

[0017] With such materials, the mechanism of the expanding material upon heating can be understood as follows: the acidic source of the expanding material can enhance the carbon source to carbonize upon heating, and then the gas that can be released from the blowing agent can promote such carbonization to increase the thickness and / or volume of the material.

[0018] It may also be possible to add chemicals to enhance the formation of the insulating foam, such as chlorinated paraffin. In another example, a mixture of sodium silicate and graphite may be included with the expanding material. In such an example, a hard carbonized foam may be produced when the material is exposed to high temperature conditions.

[0019] Such high temperature conditions may occur during use of the heating unit and / or furnace or prior to their first use, typically during manufacture of an aerosol generating device that includes such a heating unit.

[0020] A "layer" of intumescent material may be understood as a covering, film, wrapping, or coating.

[0021] The furnace is "thermally insulated," which means that less heat is transferred towards the surroundings of the heating unit (and / or furnace) than inside the furnace.

[0022] The above configuration of the first embodiment has the advantage that the thermal insulation of the furnace is improved. The layer of expansive material facilitates and simplifies the thermal insulation of the furnace compared to conventional thermal insulation means. The expansive material allows such thermal insulation in a more reliable, predictable and reproducible manner. Thereby, the overall heating efficiency of the heating unit is improved. This saves costs and power consumption during the life cycle of the heating unit. In addition, such a configuration may improve battery life. Furthermore, the complexity of the heating unit may be reduced compared to conventional insulation means.

[0023] Another advantage is that the manufacture of such heating units can be significantly improved. Providing a layer of expansive material to thermally insulate the furnace can be easily automated. Thus, the manufacture can be speeded up and errors or defects during manufacture can be eliminated. In particular, conventional insulation means such as conventional foam insulation require additional tape to fix and / or position the foam insulation accurately. The inventor has found a way to make the burden of managing such separate elements (foam and additional tape) unnecessary. The layer of expansive material therefore offers a simplified solution for thermal insulation. In particular, there is no longer any need to deal with different material expansions due to different thermal expansion coefficients of conventional materials. The proposed configuration therefore paves the way for a cost-effective and fast manufacture of heating units.

[0024] In addition, the heating unit may provide an improvement in the overall assembly of its parts. The expansion material may expand after reaching the high temperature state, for example increasing its thickness. This increases the installation space for assembly before reaching the high temperature state. This enhances the assembly of different parts, such as wires and / or cables, near the furnace. In addition, the core material volume (VMC) of the heating unit may be reduced (for example, it may be sufficient to provide a thin layer before reaching the high temperature state by expanding), thereby reducing the cost of the heating unit parts.

[0025] Function / expansion of the layer of expanding material According to a second embodiment, in the preceding embodiment, the layer of intumescent material is configured to be triggered once heated to a trigger temperature.

[0026] The layer of intumescent material being triggered may be understood as the intumescent material being activated. In this manner, a chemical reaction may occur which leads to the expansion of the intumescent material and a decrease in its density. This may provide a lightweight heating unit.

[0027] Heating "once" to a trigger temperature may be understood such that triggering of the intumescent material occurs when the trigger temperature is first reached. Once the trigger temperature is reached for a substantial period of time, the volume of the layer of intumescent material may remain substantially constant over time, regardless of further temperature changes of the intumescent material and its surroundings, such as furnace temperature.

[0028] This arrangement has the advantage that triggering, eg activation, can be performed in a plannable, reliable, predictable and reproducible manner.

[0029] According to a third embodiment, in any one of the preceding embodiments, the trigger temperature is at least about 200° C.

[0030] The trigger temperature may also be greater than 200° C. depending on the intumescent material being applied. For example, it may be possible for the trigger temperature to be at least 210° C., 220° C., 230° C., or higher. One of ordinary skill in the art will appreciate that the trigger temperature is dependent on the intumescent material being placed on the furnace.

[0031] According to a fourth embodiment, in any one of the second or third embodiments, when the layer of expansive material is triggered, the thermal resistance of the layer of expansive material increases.

[0032] An increase in thermal resistance may be understood as an increased ability of the layer of expansive material to reduce the temperature across the thickness of the layer of expansive material. From a physics perspective, thermal resistance is a quantification of the difficulty with which heat is transferred through a material from a first point to a second point that is distinct from and distant from the first point. In practice, the effect of the thermal resistance of a material is to attenuate the transfer of heat in the material from a first point to a second point, such that the temperature T2 at the second point is lower than the temperature T1 at the first point, i.e. T1>T2. In the context of the present invention, the thermal resistance of the layer of expansive material may increase due to the increased thickness upon triggering the layer of expansive material. It may also be possible that the thermal conductivity of the material decreases due to a chemical reaction upon triggering. This additionally improves the thermal insulation.

[0033] According to a fifth embodiment, in any one of the second to fourth embodiments, the layer of expansion material has a thickness of at least 5 micrometers (μm), preferably at least 10 μm, more preferably at least 20 μm, most preferably at least 30 μm, and / or a thickness of at most 60 μm, preferably at most 50 μm, more preferably at most 30 μm, most preferably at most 30 μm, before being triggered.

[0034] The above arrangement has the advantage that a layer of intumescent material of a relatively small thickness is applied to the furnace initially, i.e. during its manufacture, which facilitates the assembly of the heating unit in the aerosol generating device and / or improves the compactness of such aerosol generating device.

[0035] Before the layer is triggered, its thickness should not be too small so that sufficient thermal insulation is not expected after triggering. The inventors have found that an optimal balance of these conflicting requirements can be ensured according to the fifth embodiment. In particular, it has been found that the thickness of such a layer is sufficient to allow and participate in the progression of the expansion upon triggering to be reached and improved, e.g. increased, thermal insulation.

[0036] According to the sixth embodiment, in any one of the second to fifth embodiments, when the layer of expansion material is triggered, the thickness of the layer of expansion material increases by at least 10 times, preferably at least 20 times, more preferably at least 40 times, even more preferably at least 60 times, even more preferably at least 80 times, most preferably at least 100 times, and / or at most 200 times, preferably at most 180 times, more preferably at most 160 times, even more preferably at most 140 times, even more preferably at most 120 times, most preferably at most 100 times.

[0037] The thickness increase of the layer of expansion material according to the above embodiment may be measured under conditions where there is substantially no physical prevention and / or restriction of the thickness increase. A person skilled in the art will understand that in the presence of physical impediments, obstacles, and / or obstructions, the thickness increase may be smaller, e.g., the degree of expansion may be limited. This may be the case when another part is in contact with and / or pressing against the layer of expansion material. Generally, this should not be the case according to the present invention.

[0038] As an example, a 100-fold increase means that if the thickness before triggering is 0.03 mm, the thickness after triggering can be about 3 mm (3 mm / 0.03 mm=100). The above-mentioned thickness increase factors significantly improve the thermal insulation of the furnace. Thus, the overall heating efficiency of the heating unit is enhanced. An optimal balance should be struck between sufficient thermal insulation (a high factor is desired) and acceptable expansion for ease of positioning after triggering (a low factor is desired).

[0039] As an example, the layer of expansive material may be disposed around a furnace, where the furnace has a generally cylindrical shape. In such a case, the thickness of the layer of expansive material may be measured along a radial direction. Thus, the layer of expansive material may expand radially upon triggering by a factor as specified in the sixth embodiment.

[0040] According to the seventh embodiment, in the preceding embodiments, the layer of expandable material substantially maintains its increased thickness even after the temperature of the expandable material is reduced to between 25°C and 50°C, preferably between 25°C and 30°C, and most preferably to 25°C.

[0041] "Maintaining" the increased thickness may be understood such that the thickness does not substantially fluctuate, change, alter or deviate. It should be understood that the thickness increase usually occurs when the trigger temperature is reached (for the first time). Typically, a short period of time may be necessary and sufficient for the layer of intumescent material to reach a certain thickness increase. By way of example, the short period of time may be on the order of about one second or multiple seconds. In one example, the short period of time may be comparable to the heating time of an oven (e.g., an oven to reach a targeted temperature to provide an aerosol for a user). After such triggering or activation, the temperature to which the layer of intumescent material is exposed has a substantially insignificant effect on the thickness of the layer of intumescent material.

[0042] Preferably, after such triggering or activation, there is no effect on the thickness of the layer of intumescent material, for example if the temperature is significantly reduced. For example, when the heating unit is taken out of service, the temperature of the layer of intumescent material may be cooled to about ambient temperature, for example about 20° C. to 25° C. This may have no substantial effect on the thickness of the layer. Furthermore, raising the temperature of the layer of intumescent material again to the triggering temperature or above may have no effect on its thickness.

[0043] The configuration of the seventh embodiment improves the manufacture and assembly of the heating unit. By maintaining an increased thickness of the layer of expansive material, the advantage is provided that the spaces, areas and / or dimensions within the heating unit can be determined more accurately before assembly. Such spaces, areas and / or dimensions can thereby be predicted in a more reliable and reproducible manner. By way of example, by knowing the filled space after and before triggering the layer of expansive material, it is possible to avoid unused spaces within the heating device. This provides a more compact heating unit while ensuring good thermal insulation.

[0044] Expansive material layer arrangement / shape According to an eighth embodiment, in any one of the preceding embodiments, the layer of expansive material is disposed on an outer surface of the furnace.

[0045] The outer surface of the furnace may be understood as the surface opposite to the surface facing the consumable when the consumable is received in the furnace. In other words, the outer surface faces substantially towards the outside or periphery of the furnace. Thus, the outer surface of the furnace faces the heating unit and other parts of the aerosol generating device including such heating unit / furnace. Such other parts should not be heated as they may be damaged, which also negatively affects the heating efficiency of the heating unit. Moreover, the outside of the heating unit and / or the outside of the aerosol generating device including such heating unit should not be heated as this would make normal use by the user uncomfortable and impair it.

[0046] Placing a layer of intumescent material on the outer surface of the furnace means that at least a portion of the outer surface is covered by the layer. This thermally insulates the furnace, thereby substantially preventing heat transfer to the remainder of the heating unit and / or outside the heating unit. This promotes thermal efficiency and comfort for the user. By way of example, "placing" a layer of intumescent material on the outer surface of the furnace can be understood as the layer being painted, sprayed, dipped, coated or deposited on the furnace. Preferably, it is fixed on the furnace.

[0047] According to a ninth embodiment, in any one of the preceding embodiments, the cross section of the furnace is U-shaped, and the layer of expansive material is disposed on the outer surface and the outer bottom surface of the furnace.

[0048] A cross section of the furnace may be viewed, for example, with respect to the longitudinal axis of the furnace. Typically, the longitudinal axis may be disposed generally parallel to the direction of insertion of the consumables into the furnace. A layer of intumescent material may be disposed on the exterior and bottom surfaces of the furnace to improve thermal insulation. In this manner, substantially the entire exterior of the furnace may be thermally insulated. If the furnace has a cylindrical shape, the exterior surface may be referred to as the shell surface. Additionally, the bottom surface may be referred to as the front surface of the cylinder.

[0049] In such a configuration, the outer bottom surface of the furnace can also be easily insulated. Typically, the bottom surface is difficult to access during assembly of the heating unit and can be a weak point in terms of thermal insulation. Conventional insulation means such as (thick) foam insulation lack consideration of the outer bottom surface, which is a challenge. The inventors have found a way to successfully overcome and confront this problem. Providing a layer of expansive material on the outer bottom surface of the furnace may not require more effort than providing a layer of expansive material on the outer surface. For example, the manufacturing steps of the layer of expansive material on the outer bottom surface may be performed simultaneously with those on the outer surface. The heating unit is therefore suitable for simplified and cost-effective manufacturing.

[0050] In addition, the overall thickness of the layer of expansive material can be easily controlled and determined at the same time. This promotes uniform thermal insulation of the heating unit. However, it may also be possible to provide a part of the outer surface of the furnace with a relatively thick layer of expansive material compared to other parts of the outer surface. In one example, it may be possible to arrange an additional layer of expansive material on a part of the furnace, for example on one side of the furnace. This may be beneficial if said part (for example one side) is closer to a surrounding part (for example the case or a thermally vulnerable or already warm component, thus requiring better insulation). This enhances the control and predefinition of the thermal insulation according to local thermal deviations of the furnace. This may be important if some parts of the outer surface of the furnace become hotter than other parts during normal use of the heating unit.

[0051] Further layers According to a tenth embodiment, in any one of the preceding embodiments, a primer layer, preferably comprising an epoxy or silicone, is disposed between the outer surface of the furnace and the layer of expansive material.

[0052] The primer layer may be understood as a layer that may at least partially interact with the layer of expansive material. The primer layer serves to improve the adhesion of the layer of expansive material to the furnace. The primer layer may be capable of chemically reacting with the layer of expansive material to further improve adhesion. In addition, the outer surface of the furnace may be treated, for example, by sandblasting, cleaning, laser scratching, or plasma surface treatment. This may further enhance the adhesion of the layer of expansive material to the furnace. By way of example, the primer layer may be understood as being applied, sprayed, dipped, painted, or attached onto the furnace. Preferably, it is fixed onto the furnace.

[0053] When the primer layer is disposed as described in the tenth embodiment, the layer of intumescent material may not be in direct contact with the outer surface of the furnace. Rather, the layer of intumescent material may be in direct contact with the primer layer. Regardless of the above, the layer of intumescent material is disposed "on" the outer surface of the furnace. This is because the layer of intumescent material is disposed close to the surface and thermally insulates the furnace, for example, at the outer face and bottom surface of the furnace.

[0054] According to an eleventh embodiment, in any one of the preceding embodiments, a top layer is disposed on top of the layer of expansion material.

[0055] The top layer may be understood as the layer that is exposed to the exterior and / or surroundings of the furnace. It is therefore not located inside the furnace where consumables may be received. The top layer may be referred to as the outermost layer of the furnace. By way of example, the top layer may be applied, sprayed, dipped, painted or attached onto the layer of intumescent material. Preferably, it is fixed to the layer of intumescent material.

[0056] The top layer may help to protect the layer of intumescent material. For example, the heating unit may be exposed to or influenced by environmental influences such as moisture, dust, and / or dirt. This may be the case when the heating unit is not in use for a longer period of time. As an example, condensation of moisture in the air may occur, resulting in the formation of water droplets. Such droplets may adversely affect the action of the layer of intumescent material. This may be true before triggering, but also after triggering. Thus, the top layer may beneficially counter any deterioration of the layer of intumescent material.

[0057] tube According to a twelfth embodiment, in any one of the preceding embodiments, the heating unit further includes a tube housing the furnace and the layer of expansive material.

[0058] The tube is a substantially hollow elongated piece. The tube contains, for example, contains or encloses the furnace and the layer of intumescent material. Those skilled in the art will understand that it may also contain a primer layer and / or a top layer, if these are applied. The tube may act as a container and / or reflector of infrared radiation. Thus, heat reaching the tube may be substantially reflected. This helps to keep the outside of the heating unit cooler compared to its inside, and in particular compared to the furnace. Furthermore, this improves thermal efficiency. The tube may serve the purpose of holding the rest of the heating unit together. Typically, the tube should not be heated. This may be achieved by the layer of intumescent material.

[0059] By way of example, the tube may be generally cylindrical in shape. This allows for easy assembly of the heating unit. For example, the furnace may be easily placed at least partially within the tube. Assembly is even more advanced if the furnace is shaped to match the shape of the tube. For example, the furnace may also be generally cylindrical in shape.

[0060] According to a thirteenth embodiment, in the preceding embodiment, a gap is provided between the outer surface of the furnace and the tube.

[0061] The gap may be understood as a substantial void. This improves assembly of the heating unit since it may be easier to connect the furnace to other parts. For example, electrical connection to a power source is strengthened since more space is available for proper placement of wires and / or cables. Such an approach may also be amenable to automation, which reduces manufacturing costs. In addition, such a gap eliminates errors during manufacturing. Overall, a more reliable heating unit may be provided.

[0062] The gap may be measured between the outer surface of the furnace and the tube, and therefore the thickness of the primer layer, the thickness of the layer of intumescent material, and the thickness of the top layer may not be critical when measuring such gap.

[0063] According to the fourteenth embodiment, in the preceding embodiments, the gap is at least 0.5 mm, preferably at least 1.0 mm, more preferably at least 1.5 mm, even more preferably at least 2.0 mm, most preferably at least 3.0 mm, and / or at most 5 mm, preferably at most 4.5 mm, more preferably at most 4.0 mm, even more preferably at most 3.5 mm, most preferably at most 3.0 mm.

[0064] The size of the gap may depend on the desired installation space, the size of the consumable to be heated, the expected increase in thickness of the layer of the triggered expansion material, and / or the expected thermal insulation (which may be competing goals). The gap should not be too large, otherwise there may be a void left after triggering, which leads to a less compact heating unit. The gap should not be too small, allowing for sufficient installation space. Thus, an optimal balance should be struck.

[0065] By way of example, if the tube and furnace have a generally cylindrical shape, the gap may be measured radially. Further, the gap may be constant along the circumference. In other cases, the tube may not be constant along the circumference, e.g., the gap may not be symmetrical or substantially asymmetrical along the circumference.

[0066] According to the 15th embodiment, in either the second embodiment and the 13th or 14th embodiment, before the layer of expansion material is triggered, the gap is filled with the layer of expansion material by at most 10%, preferably at most 6%, more preferably at most 4%, even more preferably at most 2%, most preferably at most 1%, and / or at least 0.1%, preferably at least 0.2%, more preferably at least 0.4%, even more preferably at least 0.6%, most preferably at least 1%.

[0067] The gap is filled with a layer of intumescent material by a certain amount, meaning that the layer occupies a certain portion of the gap. Before triggering, such occupied space may be small. This improves assembly. The occupied space may depend on one or more of the conflicting goals mentioned above, for example the expected increase in thickness of the layer of intumescent material (on reaching the trigger temperature) once triggered. An optimal balance is found to take these conflicting goals into account.

[0068] Preferably, the gap filling is constant along the circumferential direction, however, it is possible that the gap is not filled constantly along the circumferential direction.

[0069] According to the 16th embodiment, in any one of the second embodiment and the 13th to 15th embodiments, after the layer of expansion material is triggered, the gap is filled with the layer of expansion material by at least 60%, preferably at least 80%, more preferably at least 90%, even more preferably at least 94%, and most preferably at least 96%.

[0070] Upon triggering, the thickness of the layer of the expansion material has increased. Thereby, the gaps are largely filled. This allows for a compact design of the heating unit. In addition, the installation space before triggering is beneficially reduced or completely occupied after triggering. This is beneficial, since after assembly, access to the outer surface of the furnace may not be necessary. Instead, thermal insulation becomes important, which is also ensured by the increased thickness. Such filling of the gaps also increases the structural integrity of the heating unit. In this way, structural advantages are provided in case of external forces acting on the heating unit, for example when a device with a heating unit falls on the floor.

[0071] The gap may be filled to nearly 100%. The extent to which the gap is filled may depend on the presence of primer and top layers and their respective thicknesses. Typically, their thicknesses may be small. The extent to which the gap is filled may also depend on other components that may be located in the gap. For example, one or more cables and / or wires may be located in the gap to provide an electrical connection to a power source. The cables and / or wires may be shifted radially towards the tube by triggering. This may enhance the durability, life and service life of these components as they are shifted away from the furnace.

[0072] Manufacturing method A seventeenth embodiment of the present invention is a method for manufacturing a heating unit for an aerosol product, the method comprising: a) applying a layer of an expandable material onto an exterior surface of an oven configured to heat an aerosol-forming substrate of an aerosol product article upon receipt in the oven; b) heating the layer of intumescent material to a temperature of at least about 200° C. to increase the thickness of the layer of intumescent material by at least 10 times, preferably at least 20 times, and most preferably at most 100 times.

[0073] The features and advantages described above with respect to the heating unit according to any one of the first to sixteenth embodiments are mutually applicable to the method of manufacturing such a heating unit for an aerosol product. It should therefore be understood that the features described with respect to the heating unit may also be used to describe the method. Similarly, a person skilled in the art will recognize that the features and advantages described with respect to the method of manufacture are also applicable to the heating unit.

[0074] Step a) of the method may include an oven configured to heat an aerosol-forming substrate of the aerosol product article upon receipt within the oven to generate an aerosol for inhalation by a user while the aerosol product article is received within the oven. By way of example, the heating unit may be used within an aerosol generating device held by a user.

[0075] Step b) of the method may comprise increasing the thickness of the layer of the expansion material by a factor of at least 40, preferably at least 60, even more preferably at least 80, most preferably at least 100, and / or at most 200, preferably at most 180, more preferably at most 160, even more preferably at most 140, and even more preferably at most 120.

[0076] It may be appreciated that step b) of the method may occur during normal use of the heating unit and / or furnace, e.g. during first use. However, it may also be possible to provide such high temperature conditions before normal use by a user. In this case, the high temperature conditions may be applied before a final product, such as an aerosol generating device including the heating unit, is delivered to a user.

[0077] According to an 18th embodiment, in the method of the preceding embodiment, step a) comprises immersing and / or spinning the furnace in a solution comprising the expansion material, or spraying the solution comprising the expansion material onto the furnace.

[0078] Such application of the expanding material on the furnace makes the manufacturing method more cost-effective. This may be especially when compared to conventional insulation means that are cumbersome to implement, such as conventional foam insulation with additional tape for proper fixing and / or positioning. Step a) may also include applying, painting, brushing, taping or attaching the expanding material on the furnace. Preferably, dipping and spinning are performed. Thus, proper fixing and control of the thickness can be achieved.

[0079] The application of the intumescent material onto the furnace can be carried out in a single rapid manufacturing step that can be easily automated, thereby making it advantageous from a mass production standpoint.

[0080] Use of intumescent materials as insulation A nineteenth embodiment of the present invention is directed to the use of a layer of an expanding material as insulation for a heating unit of an aerosol generating device.

[0081] Intumescent materials are used in the technical field of fire protection to increase the safety of critical components in the heavy industrial sector, to protect the structural steel of buildings, etc. Such applications have proven successful in increasing the integrity of steel in the event of an external fire.

[0082] In a pioneering way, the inventors have discovered how to make such technology possible in the field of aerosol generating devices.

[0083] Aerosol generating devices and systems A twentieth embodiment of the present invention is directed to an aerosol generating device comprising a heating unit according to any one of the first to sixteenth embodiments and a power source configured to provide an electric current to the heating unit for generating an aerosol to be inhaled by a user. Advantageously, the heating unit may be of the resistive heating type, for example comprising a heating element arranged in contact with the wall of the furnace and transferring heat thereto by conduction. The heating unit may also be of the inductive type, for example comprising at least one induction coil arranged in a circumferential direction around the furnace and configured for inductive heating of a susceptor element in contact with or formed by the wall of said furnace or of a susceptor element arranged on a consumable item inserted in the furnace. The heating unit may also be a microwave heating unit, comprising the furnace as a consumable receiving cavity, a microwave radiation source, in particular a solid-state transistor-based microwave source, and an impedance matching unit for achieving an impedance matching between a consumable item inserted in the furnace and a microwave field generated by the microwave source.

[0084] The power source may be any suitable power source, for example a DC voltage source, such as a battery, for example a lithium iron phosphate battery. Alternatively, the power source may be a nickel cadmium battery, a nickel metal hydride battery, or a lithium-based battery, for example a lithium cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery. The power source may be located within a part of the aerosol generating device, or it may be another form of charge storage device, such as a capacitor. The power source may be capable of being recharged and may have a capacitor that allows it to store sufficient energy for one or more, preferably many, normal use cycles of the aerosol generating device.

[0085] A twenty-first embodiment of the present invention is directed to an aerosol generation system comprising an aerosol generation device according to the twentieth embodiment and an aerosol product comprising an aerosol-forming substrate. [Brief description of the drawings]

[0086] Preferred embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0087] [Figure 1] 1 shows a side cross-sectional view of a heating unit for an aerosol product according to a first embodiment of the present invention, prior to triggering of the layer of expansion material. [Diagram 2] 2 shows a side cross-sectional view of a heating unit for an aerosol product according to a first embodiment of the present invention after triggering of the layer of expansion material; FIG. [Diagram 3] FIG. 4 shows a side cross-sectional view of part of a layer of a furnace and heating unit according to a second embodiment of the present invention. [Figure 4] 1 shows a side cross-sectional view of a heating unit for an aerosol product according to a third embodiment of the present invention, prior to triggering of the layer of expansion material. [Diagram 5] 13 shows a side cross-sectional view of a heating unit for an aerosol product according to a third embodiment of the present invention after triggering of the layer of expansion material. FIG. [Figure 6] 1 is a flow chart of a method for manufacturing a heating unit for an aerosol product according to an embodiment of the present invention. [Figure 7] 1 illustrates an aerosol generation device and an aerosol generation system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0088] In the following, the invention will be described in more detail with reference to the attached drawings. However, the invention can also be used in other embodiments not explicitly disclosed below. As detailed below, the embodiments are mutually compatible and individual features of one embodiment can also be applied to another embodiment.

[0089] Throughout the following drawings and specification, the same reference numbers refer to the same elements unless otherwise specified. The drawings may not be drawn to scale, and the relative sizes, proportions, and depictions of elements in the drawings may be exaggerated for purposes of clarity, illustration, and convenience. The drawings are not intended to limit the scope of the claims, but are merely intended to aid in understanding the invention.

[0090] 1 shows a heating unit 10 for an aerosol product article 1, the heating unit 10 including a furnace 20 configured to heat an aerosol-forming substrate of the aerosol product article 1 when the aerosol product article 1 is received therein. The furnace 20 is typically formed by a generally tubular cup of a metallic material such as aluminum or stainless steel. The furnace 20 is thermally insulated by a layer 30 of an expanding material. Although shown in this figure, the aerosol product article 1 is generally not part of the heating unit 10. Thus, the heating unit 10 may be provided as a separate, individual component from the aerosol product article 1.

[0091] The intumescent material is a reactive material. Based on the principle of expansion, the material expands when exposed to an elevated temperature or high temperature condition (trigger temperature). Typically, such expansion occurs at high temperatures of at least about 200°C. It may be recognized that the material expansion is greater than the mere material expansion due to its thermal expansion coefficient. This may be discernible when inspecting and / or examining the heating unit, for example, when comparing the layer 30 of intumescent material at different temperatures, including the trigger temperature. The intumescent material may include a carbon source such as starch or one or more pentaerythritol (or other types of polyalcohols), an acid source such as ammonium polyphosphate, and a blowing agent such as melamine. Such substances may result in an increase in the thickness of the layer 30 of intumescent material when triggered. When triggered, the acid source of the layer 30 of intumescent material may enhance the carbonization of the carbon source. The gas released from the blowing agent may then increase such carbonization to increase the thickness and / or volume of the layer 30 of intumescent material. Beneficially, this reduces the density of the intumescent material.

[0092] The layer of expanding material 30 is disposed on the outer surface 21 of the furnace 20, which is the opposite surface to the surface facing the aerosol product 1 when the aerosol product 1 is received in the furnace 20. In this way, the outer surface 21 faces substantially towards the outside or periphery of the furnace 20. Thus, the outer surface 21 of the furnace 20 may face other parts of the heating unit 10, such as other parts that should not be heated. When triggered, the layer of expanding material 30 may provide improved thermal insulation around the furnace 20. This entails several advantages. For example, this allows for more efficient heating of the aerosol product 1, reduces power consumption, and thus increases battery life. Furthermore, it prevents the surroundings and the outside of the heating unit 10 from becoming unintentionally hot, which may be undesirable since a user may come into contact with these parts.

[0093] In the embodiment of this drawing, the furnace 20 can be provided with a layer 30 of expansive material by dipping and spinning. Thereby, the thickness 31 (not shown in this drawing) of the layer 30 of expansive material can be controlled in a simplified manner. Such a process can also be easily automated, which reduces manufacturing time and costs. The layer 30 of expansive material has a thickness of at least about 5 μm (0.005 mm) to at most about 60 μm (0.06 mm) before being triggered. Preferably, the thickness is about 30 μm. This has the advantage that a relatively thin layer of expansive material is provided, thereby saving material costs. Another benefit due to this thin thickness is that it aids in the assembly of the heating unit 10. For example, the placement and positioning of wires and / or cables can be significantly simplified due to the increased installation space.

[0094] The embodiment of this figure may have a furnace 20 with a U-shaped cross section. The cross section of the furnace 20 is shown in this figure as a cross section along the longitudinal axis of the furnace 20. Such longitudinal axis (shown in this figure as dashed line L) is oriented generally parallel to the direction of insertion of the aerosol product article 1 into the furnace 20.

[0095] The layer 30 of expanding material is arranged on the outer surface 21 and the outer bottom surface 22 of the furnace 20. The outer surface 21 and the outer bottom surface 22 of the furnace 20 may be referred to as the (overall) outer surface 21 of the furnace 20. Such a configuration may improve the thermal insulation, in particular of the entire outer surface 21 and the outer periphery of the furnace 20. As shown in this drawing, the furnace 20 may have a cylindrical shape. The outer surface 21 may therefore be referred to as the shell surface of the cylinder, and the outer bottom surface 22 may be referred to as the front surface of the cylinder. Many different shapes of the furnace 20 are also possible and are envisaged in the context of the present invention. In particular, the furnace may present a non-circular transverse cross section perpendicular to the longitudinal direction L. It may in particular include at least two flat surfaces joined by an arcuate portion, the flat surfaces providing a compression surface for improving the heat transfer to the aerosol-generating consumable 1 when inserted into the furnace 20.

[0096] FIG. 2 shows a side cross-sectional view of a heating unit 10 for an aerosol product article 1 according to a first embodiment of the present invention after triggering of the layer 30 of expanding material. This embodiment corresponds to the embodiment shown in the previous figures. By way of the illustrated example, it can be seen that the thickness 31 of the layer 30 of expanding material increases compared to the previous figures (indicated by a thick black straight line or a thick black U-shape). Such an increase in thickness 31 may range from at least 10 times to at most 200 times compared to the thickness 31 before triggering. By way of example, the thickness 31 before triggering may be about 30 μm (0.03 mm) and the thickness 31 after triggering may be about 3 mm. Thus, the thickness 31 has increased by a factor of 100.

[0097] It should also be specifically appreciated that a layer 30 of intumescent material of increased thickness 31 is provided on the exterior bottom surface 22. Such exterior bottom surface 22 is typically difficult to access and thermally insulate using conventional means for thermal insulation. Thus, the illustrated embodiment significantly improves overall thermal insulation.

[0098] It should be understood that once the layer of expansion material 30 is triggered, there is substantially no change thereafter to the thickness 31 of the layer of expansion material 30. Thus, the thickness 31 is maintained or remains the same. This may be the case even if the temperature of the expansion material subsequently changes. However, in some cases, the thickness 31 may subsequently change slightly, which may be due to the thermal expansion coefficient of the material. However, such expansion may be small.

[0099] 3 shows a side cross-sectional view of a furnace 20 and part of the layers 30, 40, 50 (not shown completely in this drawing) of a heating unit 10 according to a second embodiment of the invention. This second embodiment is compatible with the previous embodiment and simply shows the arrangement of the layers 30, 40, 50. Compared to the previous drawing, this drawing shows a part of the furnace 20 rotated by about 90°.

[0100] The primer layer 40 is disposed between the exterior surface 21 of the furnace 20 and the layer of intumescent material 30. The primer layer 40 may comprise an epoxy or silicone and may (chemically) interact with the layer of intumescent material 30 to improve adhesion of the layer of intumescent material 30 on the furnace 20. The primer layer 40 may be applied using a similar process as described with respect to the layer of intumescent material 30.

[0101] Moreover, a top layer 50 is disposed on top of the layer of intumescent material 30. The top layer 50 is exposed to the exterior and / or surroundings of the furnace 20, i.e. it faces away from the inner portion of the furnace 20. A dashed line is drawn in this drawing to illustrate this, which may represent the central axis of the furnace 20. The top layer 50 may be applied using a process similar to that described for the layer of intumescent material 30. The top layer 50 serves the purpose of protecting the layer of intumescent material 30 from environmental influences. Such protection is applied and evaluated reciprocally before and after triggering the layer of intumescent material 30. In particular, the top layer 50 may beneficially counter any deterioration of the layer of intumescent material 30. This improves the life and integrity of the heating unit 10.

[0102] Although all three layers are shown in this drawing, namely, primer layer 40, layer of intumescent material 30, and top layer 50, it should be understood that not all three layers are required. Rather, it is sufficient that layer of intumescent material 30 is present, e.g., disposed on exterior surface 21 of furnace 20. However, the additional placement of primer layer 40 and top layer 50 may help to reach the beneficial effects of layer of intumescent material 30 and its maximum potential of thermal insulation upon triggering.

[0103] 4 shows a side cross-sectional view of a heating unit 10 for an aerosol product article 1 according to a third embodiment of the invention, prior to triggering of the layer of expansion material 30. This embodiment corresponds to the embodiment shown in FIG.

[0104] In addition to the examples mentioned above, the heating unit 10 in this figure includes a tube 60, which houses the furnace 20 and the layer of intumescent material 30. The tube 60 is a generally hollow elongated part for enclosing the furnace 20 and the layer of intumescent material 30. It should be understood that it also houses the primer layer 40 and / or the top layer 50 if these layers are placed on the furnace 20 (as shown in the previous figure). The tube 60 acts as a container and / or a reflector of infrared radiation. Thus, heat reaching the tube 60 can be reflected to keep the outside of the heating unit 10 cooler than its inside, in particular the furnace 20. This additionally improves thermal efficiency and enhances user convenience.

[0105] As an example, a gap 61 may be provided between the outer surface 21 of the furnace 20 and the tube 60. Such a gap 61 is useful for assembling the heating unit 10, since it may be easier to connect the furnace to other parts and since space for installation is created. The gap 61 may be at least 0.5 mm and at most 5 mm. Preferably, the gap is about 3.0 mm. In this drawing, the gap 61 may be constant along the circumferential direction. However, the gap 61 may vary (in its width) along the circumferential direction. Before the layer 30 of expansion material is triggered, the gap 61 is filled with the layer 30 of expansion material by at most 10% and / or at least 0.1%, preferably by about 1%. This significantly improves the assembly, since it is less prone to errors.

[0106] 5 shows a side cross-sectional view of a heating unit 10 for an aerosol product article 1 according to a third embodiment of the invention after triggering of the layer of expansion material 30. This embodiment corresponds to the embodiment shown in the previous figures.

[0107] Similar to Figure 2 compared to Figure 1, this figure also shows that the thickness 31 of the layer of intumescent material 30 is increased compared to the previous figure. Such increase in thickness 31 may be of a similar magnitude to that previously discussed.

[0108] After the layer 30 of expansive material is triggered, the gap 61 is filled with the layer 30 of expansive material by at least 60%, preferably at least 80%, more preferably at least 90%, even more preferably at least 94%, and most preferably at least 96%. Due to the schematic nature of this drawing, the exact amount of filling cannot be visually indicated, but it should be at least 60%. Such filling facilitates a compact design of the heating unit 10, reducing the installation space that is present before triggering and that may no longer be needed after triggering (because assembly has already been performed). In addition, the thermal insulation is increased due to the increased thickness 31 of the layer 30 of expansive material.

[0109] FIG. 6 shows a flow chart of a method 300 for manufacturing a heating unit for an aerosol product according to an embodiment of the present invention.

[0110] The method 300 includes the steps of: a) applying a layer of an expandable material onto an exterior surface of an oven configured to heat an aerosol-forming substrate of an aerosol product article upon receipt therein (310); b) heating the layer of intumescent material to a temperature of at least about 200° C. to increase the thickness of the layer of intumescent material by a factor of at least 10, preferably at least 20, and preferably at most 100 (320).

[0111] 7 shows an aerosol generation device 100 and an aerosol generation system 200 according to an embodiment of the present invention. The system 200 includes the aerosol generation device 100 and an aerosol product 1 that includes an aerosol-forming substrate.

[0112] The aerosol generating device 100 comprises a heating unit 10 according to any one of the previously described embodiments. Furthermore, the aerosol generating device 100 comprises a power source 101 configured to provide an electric current to the heating unit 10, preferably to the furnace 20, in order to generate an aerosol to be inhaled by a user. The power source 101 may be any suitable power source 101, for example a DC voltage source.

[0113] In all of the above described embodiments, the heating unit 10 is a portable or handheld heating unit 10. The same applies to the aerosol generating device 100, the aerosol generating system 200 and the aerosol product 1. It is to be understood that these components can be comfortably held by a user between the fingers, for example between the fingers of one hand.

[0114] The scope of protection is determined by the claims and is not limited by the embodiments disclosed in the above drawings. [Explanation of symbols]

[0115] 1. Aerosol products 10 Heating unit 20 Furnace 21 Outer surface of heating furnace 22 Outer bottom surface of heating furnace 30 Layer of Expandable Material 31 Thickness of layer of intumescent material 40 Primer layer 50 upper layer 60 tubes 61 Gap 100 Aerosol generating device 101 Power supply 200 Aerosol Generation System 300 ways 310 Method Step: Applying 320 Method Step: Heating L Longitudinal axis of the furnace

Claims

**Claim 1** A heating unit (10) for an aerosol generating article (1), comprising the heating furnace (20) configured to receive and heat an aerosol forming substrate of the aerosol generating article (1) within the heating furnace (20), wherein the heating furnace (20) is thermally insulated by a layer (30) of an expandable material, the heating unit (10). **Claim 2** The heating unit (10) according to claim 1, wherein the layer (30) of expandable material is configured to be triggered once heated to a trigger temperature. **Claim 3** The heating unit (10) according to claim 2, wherein the trigger temperature is at least about 200°C. **Claim 4** The heating unit (10) according to claim 2, wherein the layer (30) of expandable material has a thickness (31) of at least 5 micrometers (μm), preferably at least 10 μm, more preferably at least 20 μm, most preferably at least 30 μm, and / or at most 60 μm, preferably at most 50 μm, more preferably at most 30 μm, most preferably at most 30 μm before being triggered. **Claim 5** The heating unit (10) according to claim 2, wherein when the layer (30) of expandable material is triggered, the thickness (31) of the layer (30) of expandable material increases by at least 10 times, preferably at least 20 times, more preferably at least 40 times, even more preferably at least 60 times, still more preferably at least 80 times, most preferably at least 100 times, and / or at most 200 times, preferably at most 180 times, more preferably at most 160 times, even more preferably at most 140 times, still more preferably at most 120 times, most preferably at most 100 times. **Claim 6** The heating unit (10) according to any one of claims 1 to 5, wherein the layer (30) of expandable material is disposed on the outer surface (21) of the heating furnace (20). **Claim 7** The heating unit (10) according to any one of claims 1 to 5, wherein the cross-section of the heating furnace (20) is U-shaped, and the layer (30) of expandable material is disposed on the outer side surface and the outer bottom surface (22) of the heating furnace (20). **Claim 8** The heating unit (10) according to any one of claims 1 to 5, wherein a primer layer (40) preferably containing epoxy or silicone is disposed between the outer surface (21) of the heating furnace (20) and the layer (30) of expandable material. **Claim 9** The heating unit (10) according to any one of claims 1 to 5, further comprising the heating furnace (20) and a tube (60) for accommodating the layer (30) of the expansion material.

10. The heating unit (10) according to claim 9, wherein a gap (61) is provided between the outer surface (21) of the heating furnace (20) and the tube (60).

11. The gap (61) is at least 0.5 mm, preferably at least 1.0 mm, more preferably at least 1.5 mm, even more preferably at least 2.0 mm, most preferably at least 3.0 mm, and / or at most 5 mm, preferably at most 4.5 mm, more preferably at most 4.0 mm, even more preferably at most 3.5 mm, most preferably at most 3.0 mm. The heating unit (10) according to claim 10.

12. The layer (30) of the expansion material is configured to be triggered once heated to a trigger temperature. Before the layer (30) of the expansion material is triggered, the gap (61) is filled with the layer (30) of the expansion material by at most 10%, preferably at most 6%, more preferably at most 4%, even more preferably at most 2%, most preferably at most 1%, and / or at least 0.1%, preferably at least 0.2%, more preferably at least 0.4%, even more preferably at least 0.6%, most preferably at least 1%. The heating unit (10) according to claim 10.

13. The layer (30) of the expansion material is configured to be triggered once heated to a trigger temperature. After the layer (30) of the expansion material is triggered, the gap (61) is filled with the layer (30) of the expansion material by at least 60%, preferably at least 80%, more preferably at least 90%, even more preferably at least 94%, most preferably at least 96%. The heating unit (10) according to claim 10.

14. A method (300) for manufacturing a heating unit (10) for an aerosol generating article (1), a) A step (310) of applying a layer (30) of an expansion material onto the outer surface of the heating furnace (20) configured to receive and heat an aerosol-forming substrate of the aerosol generating article (1) within the heating furnace (20). b) heating the layer (30) of the expansion material to a temperature of at least about 200°C to increase the thickness (31) of the layer (30) of the expansion material by at least 10 times, preferably at least 20 times, and most preferably at most 100 times (step 320); A method comprising the steps of: **Claim 15** Use of a layer (30) of an expansion material as thermal insulation for a heating unit (10) of an aerosol generating device (100).

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