Heater assembly with perforated transport material

Abstract

The invention relates to a heater assembly with perforated transport material. In particular, a heater assembly for an aerosol-generating system is provided, comprising: a fluid permeable heating element configured to vaporize a liquid aerosol-forming substrate; a transport material configured to transport the liquid aerosol-forming substrate to the fluid permeable heating element, the transport material having a thickness defined between a first surface of the transport material and an opposing second surface of the transport material, where the first surface is arranged in fluid communication with the fluid permeable heating element, and the second surface is arranged in fluid communication with the fluid permeable heating element. And the second surface is arranged to receive a liquid aerosol-forming substrate; wherein the second surface of the transport material is provided with at least one aperture extending into the transport material at a depth corresponding to at least a portion of the thickness of the transport material to define a shaped fluid channel for the liquid aerosol-forming substrate.

Description

[0001] This application is a divisional application of the Chinese patent application with international application number PCT / EP2019 / 064114, Chinese application number 201980030656.9, application date May 29, 2019, and name “Heater assembly with perforated transmission material”. Technical Field

[0002] The present invention relates to a heater assembly for an aerosol generating system and a method of manufacturing a heater assembly for an aerosol generating system. In particular, the present invention relates to a handheld aerosol generating system that vaporizes a liquid aerosol-forming substrate by heating to generate an aerosol for inhalation by a user. Background Art

[0003] A handheld electrically operated aerosol generating system consisting of a device portion including a battery and control electronics, a cartridge including a supply of an aerosol-forming substrate held in a liquid storage portion, and an electrically operated heater assembly acting as a vaporizer. A cartridge including both a supply of an aerosol-forming substrate held in a liquid storage portion and a vaporizer is sometimes referred to as a "cartomizer". A vaporizer typically includes a heater coil wrapped around an elongated core soaked in a liquid aerosol-forming substrate. A capillary material soaked in an aerosol-forming substrate supplies liquid to the core. The cartridge portion typically includes not only a supply of a liquid aerosol-forming substrate and an electrically operated heater assembly, but also a mouthpiece through which a user can inhale an aerosol into their mouth.

[0004] It is generally desirable to ensure that a minimum amount of liquid aerosol-forming substrate is present in the capillary material to avoid a "dry heating" situation, i.e. a situation where the fluid permeable heating element is heated when insufficient liquid aerosol-forming substrate is present. This situation is also known as "dry puff" and may result in overheating of the liquid aerosol-forming substrate and possible thermal decomposition, which may produce undesirable by-products such as formaldehyde. Summary of the invention

[0005] According to a first aspect of the present application, a heater assembly for an aerosol generating system is provided, the heater assembly comprising: a fluid permeable heating element, the fluid permeable heating element being configured to vaporize a liquid aerosol-forming substrate; a transmission material, the transmission material being configured to transmit the liquid aerosol-forming substrate to the fluid permeable heating element, the transmission material having a thickness defined between a first surface of the transmission material and an opposite second surface of the transmission material, wherein the first surface is arranged to be fluidically connected to the fluid permeable heating element, and the second surface is arranged to receive the liquid aerosol-forming substrate, wherein the second surface of the transmission material is provided with at least one hole, the at least one hole extending into the transmission material to a depth corresponding to at least a portion of the thickness of the transmission material to define a shaped fluid channel for the liquid aerosol-forming substrate.

[0006] During manufacture, the transmission material is placed in fluid communication with the fluid-permeable heating element. The transmission material may be located in a housing or heater bracket that may include a portion of the barrel portion, and typically includes a porous or fluid-permeable material having a pore or microchannel network through which the liquid aerosol-forming substrate is transmitted or infiltrated. The size of the transmission material is generally slightly larger than the internal dimensions of the heater bracket so as to provide a tight fit between the heater bracket and the transmission material, which helps to reduce the possibility of leakage around the edge of the transmission material. Therefore, during insertion, the transmission material is orthogonal to the thickness direction of the transmission material and is compressed toward the center of the transmission material, which may result in closing a portion of the pores or microchannels of the transmission material or at least reducing the size of a portion of the pores or microchannels of the transmission material. Therefore, the transmission of the liquid aerosol-forming substrate through the transmission material may be interrupted or reduced, which may result in insufficient and dry suction of the liquid aerosol-forming substrate at the fluid-permeable heating element.

[0007] In the first aspect of the invention described above, at least one hole is provided in the transmission material, the at least one hole defining a shaped fluid channel for the liquid aerosol-forming substrate. The at least one hole remains open even when the transmission material is inserted into the housing and compressed, so that the liquid aerosol-forming substrate can freely enter the hole. The depth to which the at least one hole extends into the transmission material corresponds to at least a portion of the thickness of the material, so that the thickness of the transmission material and therefore the resistance to fluid flow are reduced in the area of ​​the hole. This helps the liquid aerosol-forming substrate to reach the fluid-permeable heating element and reduces the possibility of dry suction and formaldehyde production. The applicant has found that the claimed arrangement can reduce formaldehyde production by 90% compared to a heater assembly in which no holes are provided in the transmission material.

[0008] As used herein, the term "shaped fluid channel" refers to a fluid channel, i.e., at least one pore, provided in a transport material, and which is distinct from pores or microchannels that are part of the transport material by virtue of its porous or fluid-permeable properties. In other words, the shaped fluid channel is distinct from pores or microchannels that are intrinsic to the transport material. Furthermore, the shaped fluid channel need not extend through the entire thickness of the transport material. The shaped fluid channel need only extend sufficiently so that the liquid aerosol-forming substrate can enter the channel.

[0009] The transfer material may be in contact with the fluid permeable heating element. This facilitates the transfer of the liquid aerosol-forming substrate from the transfer material to the heating element. Alternatively, there may be an intermediate layer between the transfer material and the fluid permeable heating element, wherein the intermediate layer assists in providing fluid communication between the transfer material and the fluid permeable heating element.

[0010] The fluid permeable heating element may be substantially flat and may include a conductive filament. This avoids the need to wrap a heater coil around a capillary wick. The conductive filament may be located in a single plane. A flat heating element may be easy to handle during manufacturing and provide a stable construction. In other embodiments, a substantially flat heating element may be curved along one or more dimensions, for example to form a dome shape or a bridge shape.

[0011] The conductive filaments may define spaces between the filaments, and the spaces may have a width of between 10 μm and 100 μm. The filaments may induce capillary action in the spaces so that, in use, liquid to be evaporated is drawn into the spaces, thereby increasing the contact area between the heating element and the liquid.

[0012] The conductive filaments may form a grid having a size between 160 and 600 mesh US (+ / - 10%) (i.e., between 160 and 600 filaments per inch (+ / - 10%)). The width of the gaps is preferably between 75 μm and 25 μm. The percentage of open area of ​​the grid (which is the ratio of the area of ​​the gaps to the total area of ​​the grid) is preferably between 25% and 56%. The grid may be formed using different types of interlaced or lattice structures. Alternatively, the conductive filaments consist of an array of filaments arranged parallel to each other.

[0013] The diameter of the conductive filaments may be between 10 μm and 100 μm, preferably between 8 μm and 50 μm, and more preferably between 8 μm and 39 μm. The filaments may have a circular cross section or may have a flat cross section. The heater filaments may be formed by etching a sheet of material such as foil. This may be particularly advantageous when the heater assembly comprises an array of parallel filaments. If the heater assembly comprises a mesh or fabric of filaments, the filaments may be formed individually and knitted together.

[0014] The area of ​​the fluid permeable heating element may be smaller, for example, less than or equal to 50 square millimeters, preferably less than or equal to 25 square millimeters, more preferably about 15 square millimeters. Select the size to incorporate the heating element into the handheld system. The size of the heating element is set to be less than or equal to 50 square millimeters to reduce the total power required for heating the heating element, while still ensuring that the heating element and the liquid aerosol form enough contact of the substrate. The heating element can be, for example, rectangular, and has a length between 2 millimeters and 10 millimeters and a width between 2 millimeters and 10 millimeters. Preferably, the grid has a size of about 5 millimeters multiplied by 3 millimeters.

[0015] The filaments of the heating element may be formed of any material having suitable electrical properties. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, electrically "conductive" ceramics (such as molybdenum disilicide), carbon, graphite, metals, metal alloys, and composite materials made of ceramic materials and metallic materials. Such composite materials may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals.

[0016] Examples of suitable metal alloys include stainless steel; Constantan; nickel-containing alloys, cobalt-containing alloys, chromium-containing alloys, aluminum-containing alloys, titanium-containing alloys, zirconium-containing alloys, hafnium-containing alloys, niobium-containing alloys, molybdenum-containing alloys, tantalum-containing alloys, tungsten-containing alloys, tin-containing alloys, gallium-containing alloys, manganese-containing alloys, and iron-containing alloys; and superalloys based on nickel, iron, and cobalt; stainless steel, Alloys based on iron and aluminum, and alloys based on iron, manganese and aluminum. is a registered trademark of Titanium Metal Corporation. The filaments may be coated with one or more insulators. Preferred materials for the conductive filaments are stainless steel and graphite, more preferably 300 series stainless steels such as AISI 304, 316, 304L, 316L, etc. In addition, the conductive heating element may include a combination of the above materials. Combinations of materials can be used to improve control of the resistance of the fluid permeable heating element. For example, a material with a high inherent resistance can be combined with a material with a low inherent resistance. This may be advantageous if one of the materials is more advantageous in other aspects, such as price, processability or other physical and chemical parameters. Advantageously, the substantially flat filament arrangement with increased resistance reduces parasitic losses. Advantageously, the high resistivity heater allows for more efficient use of battery energy.

[0017] Preferably, the filament is made of wire. More preferably, the wire is made of metal, most preferably made of stainless steel.

[0018] The resistance of the grid, array or fabric of the conductive filaments of the heating element can be between 0.3 ohms and 4 ohms. Preferably, the resistance is equal to or greater than 0.5 ohms. More preferably, the resistance of the grid, array or fabric of the conductive filaments is between 0.6 ohms and 0.8 ohms, and most preferably about 0.68 ohms. The resistance of the grid, array or fabric of the conductive filaments is preferably at least one order of magnitude greater than the resistance of the conductive contact area, and more preferably at least two orders of magnitude greater. This ensures that the heat generated by passing the current through the heating element is concentrated to the grid or array of the conductive filaments. If the system is powered by a battery, it is advantageous for the heating element to have a lower total resistance. The low resistance high current system allows high power to be delivered to the heating element. This allows the heating element to quickly heat the conductive filaments to the desired temperature.

[0019] The depth of at least one hole may exceed half the thickness of the transport material. This means that the liquid aerosol-forming substrate must pass through less than half the thickness of the transport material in the region of the at least one hole, which facilitates transport of the liquid aerosol-forming substrate to the fluid permeable heating element in the region of the at least one hole.

[0020] At least one hole may be formed in a central region of the transmission material. Preferably, at least one hole may be formed at the center or centroid of the second surface of the transmission material. When the transmission material is inserted into the housing, compression tends to be greatest toward the center of the transmission material. Therefore, positioning at least one hole in the central region of the transmission material provides the most desired shaped fluid channel and helps to transport the liquid aerosol generating substrate in the central region of the transmission material.

[0021] The entrance diameter of the at least one hole at the second surface of the transmission material may be between 0.5 mm and 2.5 mm, more specifically between 0.8 mm and 2 mm, and even more specifically 1.3 mm. These dimensions of the holes have been found to be suitable for transmitting liquid aerosol-forming substrates that are drawn into the holes by wicking, i.e. capillary action. Furthermore, it has been found that holes of this size remain open, i.e. are not forced closed, when the transmission material is inserted into the housing.

[0022] At least one of the holes may taper towards the first surface of the transport material. It has been found that the rate of absorption of liquid into converging channels by wicking is faster than that of cylindrical channels or diverging channels. In addition, the walls of the tapered holes do not necessarily have to be straight, but can be curved. It has been found that curved walls, especially those that curve inwardly (i.e., the walls are convex), further increase the rate of absorption of liquid because they increase the surface area of ​​the walls of the channel that interacts with the surface tension of the liquid. The degree of curvature will depend on the characteristics of the liquid, especially its surface tension.

[0023] At least one hole may extend through the entire thickness of the transport material to provide a through hole in the transport material.This arrangement provides a shaped fluid passage through the transport material through which the liquid aerosol-forming liquid may be transported.

[0024] The outlet diameter of at least one hole at the first surface of the transfer material may be between 0.2 mm and 0.4 mm, more specifically between 0.28 mm and 0.32 mm, and even more specifically 0.3 mm. These ranges of outlet diameters have been found to be suitable sizes for transferring liquid aerosol-forming substrate to the fluid permeable heating element.

[0025] The first surface of the transmission material may be convex, particularly a convex dome. This shape may be added to the first surface, or may be a byproduct of manufacturing the transmission material with at least one hole, for example by stamping and piercing. As discussed above, the first surface of the transmission material is arranged to be in fluid communication with the fluid permeable heating element so that the convex surface will be oriented towards the heating element. The heating element may have a residual arcuate shape due to certain manufacturing processes, and therefore the convex first surface will better conform to the shape of the heating element. This may improve the transmission of the liquid aerosol generating substrate to the heating element, particularly in arrangements where the transmission material is in contact with the fluid permeable heating element.

[0026] The transmission material may comprise a disc. A disc has been found to be a particularly convenient shape as it is easily manufactured by stamping and fits into the tubular housing. However, it will be appreciated that the transmission material may be formed in other suitable shapes, such as a square, rectangular or oval or another curved or polygonal or irregular shape. The thickness of the transmission material may be less than the length or width or diameter of the transmission material. The aspect ratio of the length or width or diameter of the transmission material to the thickness of the transmission material may be greater than 3:1.

[0027] The transport material may include a capillary material. A capillary material is a material that transports a liquid through the material by capillary action. The transport material may have a fibrous or porous structure. The transport material preferably includes a capillary bundle. For example, the transport material may include a plurality of fibers or threads or other fine-pore tubes. The transport material is configured to transport liquid primarily in a direction orthogonal or perpendicular to the thickness direction of the transport material.

[0028] The capillary material may preferably include elongated fibers so that capillary action occurs in small spaces or microchannels between the fibers. The average direction of the elongated fibers may be in a direction substantially parallel to the first surface and the second surface, and at least one hole may extend in a direction substantially perpendicular to the average direction of the elongated fibers. The arrangement of such elongated fibers means that capillary action occurs primarily substantially parallel to the first surface and the second surface, so that the liquid aerosol-forming matrix diffuses throughout the transmission material and the fluid-permeable heating element. Therefore, the transmission of the liquid aerosol-forming matrix through the thickness of the transmission material is relatively low. However, providing at least one hole so that it extends in a direction substantially perpendicular to the average direction of the elongated fibers means that the shaped fluid channel at least partially extends through the thickness of the transmission material and helps to transport the fluid through the thickness of the transmission material to the fluid-permeable heating element.

[0029] The transmission material may include a heat-resistant material having a thermal decomposition temperature of at least 160 degrees Celsius or higher (such as about 250 degrees Celsius). The transmission material may include fibers or threads of cotton or treated cotton, such as acetylated cotton. Other suitable materials may also be used, such as ceramic or graphite-based fiber materials or materials made of spinning, stretching or extruding fibers, such as glass fibers, cellulose acetate, or any suitable heat-resistant polymers. The thickness of each fiber of the transmission material may be between 10 μm and 40 μm, and more specifically between 15 μm and 30 μm. The transmission material may have any suitable capillarity and porosity so as to be used with different liquid physical properties. The liquid aerosol-forming matrix has these physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point and vapor pressure, which allow the liquid aerosol-forming matrix to be transported through the transmission material by capillary action.

[0030] The transmission material can be provided with a plurality of holes. By providing more than one hole, additional shaped fluid channels are generated, which can increase the transmission of the liquid aerosol generating matrix through the thickness of the transmission material. A plurality of holes can be formed in the second surface and extend from the second surface into the transmission material. Alternatively, a first hole can be formed in the second surface and extend from the second surface into the transmission material, and a second hole can be formed in the first surface and extend from the first surface into the transmission material. The first hole and the second hole can be connected to produce a through hole in the transmission material. Alternatively, the first hole and the second hole can be spaced apart in a direction parallel to the first surface and the second surface so that the holes are not connected. However, the fluid can be transferred between the first hole and the second hole by capillary action.

[0031] The heater assembly can also include a heater bracket for installing a transmission material and a fluid permeable heating element. In addition, the heater assembly can also include a holding material to hold the liquid aerosol to generate a matrix and transport it to the transmission material. The holding material can also include a capillary material with a fiber or porous structure forming a plurality of small holes or microchannels, and the liquid aerosol formation matrix can be transmitted through the plurality of small holes or microchannels by capillary action. The holding material can include a capillary bundle, for example, a plurality of fibers or lines or other fine-pore tubes. The fiber or line can be roughly aligned to form a matrix to transport the liquid aerosol toward the transmission material. Alternatively, the holding material can include a spongy or foamy material. The holding material can include any suitable material or material combination. The example of a suitable material is a spongy or foamy material, a ceramic or graphite-based material in the form of a fiber or sintered powder, a foamed metal or a plastic material, for example, a fibrous material made by spinning or extruding a fiber, such as cellulose acetate, polyester or bonded polyolefin, polyethylene, terylene or polypropylene fiber, nylon fiber or ceramic. The retention material may include high density polyethylene (HDPE) or polyethylene terephthalate (PET). Compared to the transmission material, the retention material may have excellent wicking properties, so that it retains more liquid per unit volume than the transmission material. In addition, the thermal decomposition temperature of the transmission material may be higher than that of the retention material.

[0032] According to a second aspect of the present invention, there is provided a method for manufacturing a heater assembly for an aerosol generating system, the method comprising: providing a fluid permeable heating element; providing a transmission material having a thickness defined between a first surface of the transmission material and a relative second surface of the transmission material; forming at least one hole in the second surface of the transmission material, wherein the at least one hole extends into the transmission material to a depth corresponding to at least a portion of the thickness of the transmission material; and arranging the first surface of the transmission material to be fluidically connected to the fluid permeable heating element.

[0033] The transfer material may be provided by cutting a disc from a section of the transfer material with a punch. Stamping is a suitable manufacturing process which may enable high volume manufacturing techniques. Furthermore, the stamping action may help impart a convex shape to the first surface of the transfer material.

[0034] The cutting end of the punch may include a tapered perforator for forming at least one hole. It has been found that a tapered perforator is a suitable tool for forming the hole, and the conical shape can help to give the hole a tapered shape. However, the skilled person will recognize that perforators of other shapes can be used depending on the desired hole shape. In addition, other techniques can be used to form the hole, such as molding, drilling, stamping and laser drilling. By combining the punch and perforator, the step of forming at least one hole can be performed during the step of cutting the disc of transmission material, thereby improving manufacturing efficiency.

[0035] The diameter of the conical perforator at its widest part may be between 0.5 and 2.5 mm, more specifically between 0.8 and 2 mm, and even more specifically 1.3 mm. This size range has been found to be a suitable diameter for forming at least one hole.

[0036] According to a third aspect of the present invention there is provided a cartridge for an aerosol generating system, the cartridge comprising: a heater assembly according to the first aspect above; and a liquid storage compartment for storing a liquid aerosol-forming substrate.

[0037] The cartridge may further comprise a cap or holder for holding components of the heater assembly and the liquid aerosol-generating substrate.

[0038] According to a fourth aspect of the present invention, there is provided an aerosol generating system comprising a main body portion and a cartridge according to the third aspect above, wherein the cartridge is removably coupled to the main body portion.

[0039] Features described in relation to one aspect may be equally applicable to other aspects of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0041] Figure 1 is a schematic illustration of an aerosol generating system according to an embodiment of the present invention;

[0042] Figure 2 is a schematic illustration of a cross section of a barrel including a mouthpiece according to the present invention;

[0043] Figure 3 Shows Figure 2 Heater bracket.

[0044] Figure 4 yes Figure 2 and Figure 3 A cross-sectional illustration of a transmission material showing a magnified area of ​​its internal structure.

[0045] Figures 5 to 8 is a cross-sectional illustration of a transmission material according to various embodiments of the present invention.

[0046] Fig. 9 is a cross-sectional illustration of a stamping tool for making a transfer material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] Figure 11 is a schematic illustration of an aerosol generating system according to an embodiment of the present invention. The system comprises two main components, a cartridge 100 and a main body portion 200. The connection end 115 of the cartridge 100 is removably connected to a corresponding connection end 205 of the main body portion 200. The main body portion 200 comprises a battery 210, which in this example is a rechargeable lithium-ion battery, and a control circuit 220. The aerosol generating system is portable and has a size equivalent to a conventional cigar or cigarette. A mouthpiece is arranged at the end of the cartridge 100 opposite to the connection end 115.

[0048] The cartridge 100 comprises a housing 105 containing a heater assembly 120 and a liquid storage compartment having a first portion 130 and a second portion 135. The liquid aerosol-forming substrate is retained in the liquid storage compartment. Figure 1 , the first portion 130 of the liquid storage compartment is connected to the second portion 135 of the liquid storage compartment so that liquid in the first portion 130 can be transferred to the second portion 135. The heater assembly 120 receives liquid from the second portion 135 of the liquid storage compartment. In this embodiment, the heater assembly 120 includes a fluid permeable heating element.

[0049] The airflow passages 140 , 145 extend through the cartridge 100 from an air inlet 150 formed in a side of the cartridge 105 , through the heater assembly 120 , and from the heater assembly 120 to a mouthpiece opening 110 formed in the cartridge 105 at the end of the cartridge 100 opposite the connection end 115 .

[0050] The components of the cartridge 100 are arranged such that the first portion 130 of the liquid storage compartment is between the heater assembly 120 and the mouthpiece opening 110, and the second portion 135 of the liquid storage compartment is located on the side of the heater assembly 100 opposite the mouthpiece opening 110. In other words, the heater assembly 120 is located between the two portions 130, 135 of the liquid storage compartment and receives liquid from the second portion 135. The first portion 130 of the liquid storage compartment is closer to the mouthpiece opening 110 than the second portion 135 of the liquid storage compartment. The airflow passages 140, 145 pass through the heater assembly 110 and extend between the first portion 130 and the second portion 135 of the liquid storage compartment.

[0051] The system is configured so that the user can inhale or suck on the mouthpiece opening 110 of the tube to inhale the aerosol into its mouth. In operation, when the user inhales on the mouthpiece opening 110, air is inhaled to the mouthpiece opening 110 from the air inlet 150 through the heater assembly 120 through the airflow passage 140, 145. When the system is activated, the control circuit system 220 controls the power supply of the battery 210 to the tube 100. This in turn controls the amount and nature of the steam generated by the heater assembly 120. The control circuit 220 may include an airflow sensor (not shown), and when the airflow sensor detects that the user inhales on the tube 100, the control circuit 220 may supply electric power to the heater assembly 120. This type of control arrangement has been used for a long time in aerosol generating systems such as inhalers and electronic cigarettes. Therefore, when the user inhales on the mouthpiece opening 110 of the tube 100, the heater assembly 120 is activated and generates steam, which is entrained in the airflow passing through the airflow passage 140. The vapor cools within the air flow in the passageway 145 to form an aerosol, which is then drawn through the mouthpiece opening 110 into the user's mouth.

[0052] In operation, the mouthpiece opening 110 is typically the highest point of the system. The configuration of the cartridge 100, and in particular the arrangement of the heater assembly 120 between the first and second portions 130, 135 of the liquid storage compartment is advantageous because it utilizes gravity to ensure that the liquid substrate is delivered to the heater assembly 120, even when the liquid storage compartment becomes empty, but prevents an oversupply of liquid to the heater assembly 120 which could result in leakage of liquid into the airflow passage 140.

[0053] Figure 2 1 is a schematic cross-section of a cartridge 100 according to an embodiment of the present invention. The cartridge 100 includes an outer housing 105 having a mouthpiece with a mouthpiece opening 110 and a connection end 115 opposite the mouthpiece. Within the housing 105 is a liquid storage compartment that holds a liquid aerosol-forming substrate 131. The liquid storage compartment has a first portion 130 and a second portion 135, and the liquid is contained in the liquid storage compartment by the following three additional components: an upper storage compartment housing 137, a heater bracket 134, and an end cap 138. A heater assembly 120 including a fluid-permeable heating element 122 and a transmission material 124 is held in the heater bracket 134. A retention material 136 is disposed in the second portion 135 of the liquid storage compartment and adjacent to the transmission material 124 of the heater assembly 120. The retention material 136 is arranged to transfer the liquid to the transmission material 124 of the heater assembly 120.

[0054] The first portion 130 of the liquid storage compartment is larger than the second portion 135 of the storage compartment and occupies the space between the heater assembly 120 and the mouthpiece opening 110 of the cartridge 100. Liquid in the first portion 130 of the storage compartment can travel to the second portion 135 of the liquid storage compartment through the liquid channel 133 on either side of the heater assembly 120. In this example, two channels are provided to provide a symmetrical structure, but only one channel is required. The channel is a closed liquid flow path defined between the upper storage compartment housing 137 and the heater bracket 134.

[0055] The fluid permeable heating element 122 is substantially flat and is arranged on a side of the heater assembly 120 facing the first portion 130 of the liquid storage compartment and the mouthpiece opening 110. The transmission material 124 is arranged between the fluid permeable heating element 122 and the retention material 136. A first surface of the transmission material 124 is in contact with the fluid permeable heating element 122, and a second surface of the transmission material is in contact with the retention material 136 and the liquid 131 in the storage compartment. The second surface of the transmission material 124 faces the connection end 115 of the cartridge 100. The heater assembly 120 is closer to the connection end 115 so that the electrical connection of the heater assembly 120 to the power source can be easily and firmly achieved.

[0056] The airflow passage 140 extends between the first and second portions of the storage compartment. The bottom wall of the airflow passage 140 includes the fluid permeable heating element 122. The side walls of the airflow passage 140 include portions of the heater bracket 134, and the top wall of the airflow passage includes a surface of the upper storage compartment housing 137. The airflow passage has a vertical portion (not shown) that extends through the first portion 130 of the liquid storage compartment toward the mouthpiece opening 110.

[0057] It should be understood that Figure 2 The arrangement of is only one example of a cartridge of an aerosol generating system. Other arrangements are possible. For example, the fluid permeable heating element, the transmission material and the retaining material may be arranged at one end of the cartridge housing, and the liquid storage compartment may be arranged at the other end.

[0058] Figure 3 yes Figure 2134, which shows the features of the heater bracket in more detail. The transmission material 124 and a portion of the retention material 136 are located within the tubular recess 132 formed in the heater bracket 134. The fluid permeable heating element 122 extends across the tubular recess 132. The first surface 124a of the transmission material 124 contacts the bottom surface of the fluid permeable heating element 122 to provide fluid communication between the transmission material 124 and the heating element 122 for the liquid aerosol generating substrate. The first portion of the retention material 136 is located within the tubular recess 132 and abuts the second surface 124b of the transmission material 124 so that the transmission material 124 can receive the liquid aerosol generating substrate from the retention material 136. The second portion of the retention material 136 extends outside the tubular recess 132 and is in fluid communication with the liquid channel 133 so that the second portion of the retention material 136 can receive the liquid aerosol generating liquid from the liquid channel 133. A second portion of the retention material 136 abuts an end cap 138 that seals the lower end of the heater bracket 134. The heater bracket 134 is injection molded and formed from an engineering polymer such as polyetheretherketone (PEEK) or liquid crystal polymer (LCP).

[0059] The fluid permeable heating element 122 comprises a planar mesh heating element formed of a plurality of filaments. Details of the construction of such a heating element can be found in published PCT patent application number WO2015 / 117702. The heating element is provided at the entrance and exit of the Figure 2 The heater element 122 extends outside the tubular recess 132 in the direction of the plane of the heater element 122 so that the opposite ends of the heater element 122 are located outside the heater bracket 134. Contact pads are provided at each opposite end of the heater element 122 to supply electrical power to the heater element 122.

[0060] Transmission material 124 and retention material 136 are both formed by the capillary material that keeps and conveys liquid aerosol to form a matrix. As described above, transmission material 124 is in direct contact with heating element 122, and has a higher thermal decomposition temperature (at least 160 degrees Celsius or higher, for example, about 250 degrees Celsius) than retention material 136. Transmission material 124 is effectively used as a spacer that separates heating element 122 from retention material 136, so that retention material 136 will not be exposed to a temperature higher than its thermal decomposition temperature. The thermal gradient of transmission material 124 makes retention material 136 only exposed to a temperature lower than its thermal decomposition temperature. Retention material 136 can be selected to have a wicking performance that is superior to transmission material 124, so that its per unit volume ratio transmission material 124 retains more liquid. In this example, transmission material 124 is a heat-resistant material, such as cotton or treated cotton-containing material, and retention material 136 is a polymer, such as high-density polyethylene (HDPE) or polyethylene terephthalate (PET).

[0061] The transmission material 124 is formed as a disc having a diameter of about 5.8 mm and a thickness of about 2.5 mm. This diameter is slightly larger than the inner diameter of the tubular recess 132 so that when the transmission material 124 is inserted into the tubular recess 132, the transmission material 124 is compressed radially inwardly toward the center of the disc. This is done to provide a seal between the outer circumference of the disc and the inner circumference of the tubular recess 132 to prevent the liquid aerosol-generating substrate from leaking around the outside of the transmission material 124. However, compressing the disc compresses the microchannels of the capillary material that makes up the transmission material 124. This may be problematic because it may inhibit the transmission of the liquid aerosol-forming substrate through the transmission material 124.

[0062] In order to seek to alleviate this problem, the second surface 124b of the transmission material 124 is provided with an aperture 126 that extends through the entire thickness of the transmission material 124, i.e., from the second surface 124b to the first surface 124a. The aperture 126 is provided at the center of the transmission material 124 where compression is greatest, and defines a shaped fluid channel for the liquid aerosol generating substrate. This helps the liquid pass through the central area of ​​the transmission material 124 where compression is greatest. The aperture tapers towards the first surface 124a of the transmission material 124, and may have a variety of different sizes depending on the characteristics of the transmission material 124 and the liquid aerosol generating substrate. In this example, the aperture 126 has an inlet diameter of 1.3 mm at the second surface 124b before it is compressed into the tubular recess 132, and an outlet diameter of 0.3 mm at the first surface 124a. The aperture 126 is provided by piercing the transmission material 124 using a conical piercing tool, which is described below.

[0063] Figure 4 Shows Figure 2 and Figure 3124. The cross-sectional area of ​​the transmission material 124 has been magnified one hundred times to show its internal structure. The transmission material 124 is formed of elongated fibers that are arranged substantially parallel to the first surface 124a and the second surface 124b of the transmission material 124. Liquid is transported through the transmission material 124 by capillary action in the small spaces or microchannels between the elongated fibers 124c. Although some liquid is transported through the thickness of the transmission material 124, the primary direction of liquid transport is along the fibers, i.e., substantially parallel to the first surface 124a and the second surface 124b of the transmission material 124. This arrangement prevents excessive liquid from being transported to the fluid permeable heating element, which could result in leakage of the liquid aerosol-forming substrate and deposition of droplets in the airflow path. In addition, it helps to spread the liquid aerosol-forming substrate over the area of ​​the fluid permeable heating element to help uniformly wet the heating element. However, due to the compression of the transport material 124 described above, the microchannels at the center of the transport material 124 may be constricted, which inhibits the transport of liquid aerosol-generating substrate through the transport material 124, i.e., from the holding material to the fluid-permeable heating element. The holes 126 overcome this problem by providing shaped fluid channels in the central region of the transport material to allow sufficient liquid aerosol-generating substrate to reach the fluid-permeable heating element so as to avoid dry puff conditions. The holes 126 extend in a direction substantially perpendicular to the average direction of the elongated fibers 124c.

[0064] Figure 5 FIG. 2 shows a transmission material 224 according to another embodiment of the present invention. The transmission material 224 is similar to Figure 4 224, except that it has a convex first surface 224a, particularly a convex dome shape. This shape can be caused by the stamping and piercing process used to manufacture the transmission material 224, which is applied to the second surface 224b and tends to cause the first surface 224a to bend outwardly due to the application of stamping and piercing forces. Alternatively, the shape can be added to the transmission material 224, for example by forcing it into a mold. This arrangement helps the transmission material 224 conform to the shape of the curved fluid permeable heating element, which shape can be a byproduct of some manufacturing process used to manufacture the fluid permeable heating element. The tapered hole 226 passes through the entire thickness of the transmission material 224. The transmission material is formed into a disc having a diameter of about 5.8 mm and a thickness of about 2.5 mm at its thickest point.

[0065] Figure 6 FIG. 3 shows a transmission material 324 according to another embodiment of the present invention. The transmission material 324 is similar to Figure 5324, except that the holes 326 extend only partially through the thickness of the transmission material 324. In this example, the holes 326 extend into the transmission material 324 to a depth greater than half the thickness of the transmission material 324. Although this arrangement does not provide through holes in the transmission material 324 for liquid to flow through, it still improves the flow of liquid aerosol generating substrate through the transmission material by reducing the thickness of the transmission material in the area of ​​the holes through which the liquid must flow (in this example, reducing the thickness of the transmission material to less than half the thickness). In other words, liquid flowing into the holes 326 can more easily penetrate through the remainder of the thickness of the transmission material 324 than having to penetrate through the entire thickness.

[0066] Figure 7 A transmission material 424 according to another embodiment of the present invention is shown. Again, the transmission material 424 is formed into a disk having a diameter of about 5.8 mm and a thickness of about 2.5 mm. The transmission material 424 includes a plurality of holes: a first hole 426a disposed in a first surface 424a, and a second hole 426b disposed in a second surface 424b. Each of the first hole 426a and the second hole 426b extends into the transmission material 424 to a depth greater than half the thickness of the transmission material 424. The first hole 426a and the second hole 426b are aligned so that they are connected to form a through hole in the transmission material 424 through which the liquid aerosol generating substrate can pass.

[0067] Figure 8 FIG. 5 shows a transmission material 524 according to another embodiment of the present invention. The transmission material 524 is similar to Figure 7 524, except that the first and second holes 526a, 526b are not aligned, but are spaced apart in a direction parallel to the first and second surfaces 524a, 524b. Each of the first and second holes 526a, 526b extends into the transmission material 524 to a depth greater than half the thickness of the transmission material 524. The liquid aerosol generating substrate flowing into the holes 526b can travel by capillary action along the elongated fibers of the transmission material 524 in a direction parallel to the first and second surfaces 524a, 524b to the holes 526a, where the liquid aerosol generating substrate can be transferred to the fluid permeable heating element.

[0068] A method of manufacturing a heater assembly according to an embodiment of the present invention includes arranging a transmission material in fluid communication with a fluid permeable heating element. One example of achieving fluid communication is arranging the transmission material in contact with the fluid permeable heating element. The transmission material can be provided by stamping a disc from a larger block of transmission material.

[0069] Fig. 9An example of a punch 600 for providing a disc of transmission material is shown. The punch 600 includes a cylindrical post 650 having an internal thread 652 at one end for attaching the punch to a press (not shown). The longitudinal thread 652 extends longitudinally into the cylindrical post 650. The other end of the cylindrical post 650 includes a cutting end 654 of the punch 600, which is configured to cut a disc of transmission material. The diameter of the cutting end is the same as the diameter of the disc of transmission material, i.e., about 5.8 mm. A conical perforator 656 is located at the cutting end, which is configured to pierce the transmission material to form a hole. The diameter of the conical perforator 656 is about 1.3 mm at its widest part and is about 4.3 mm long. By placing the conical perforator 656 at the cutting end of the punch 600, the transmission material can be pierced in the step of cutting the disc of transmission material.

Claims

1. A heater assembly for an aerosol generating system, the heater assembly comprising: a fluid permeable heating element configured to vaporize a liquid aerosol-forming substrate, a transfer material configured to transfer a liquid aerosol-forming substrate to the fluid permeable heating element, the transfer material having a thickness defined between a first surface of the transfer material and an opposing second surface of the transfer material, wherein the first surface is arranged in fluid communication with the fluid permeable heating element and the second surface is arranged to receive the liquid aerosol-forming substrate, wherein the second surface of the transmission material is provided with at least one hole, the at least one hole extending into the transmission material to a depth corresponding to at least a portion of the thickness of the transmission material to define a shaped fluid channel for a liquid aerosol-forming substrate, and The first surface of the transmission material is convex.

2. The heater assembly of claim 1, wherein the depth of the at least one hole exceeds half the thickness of the transmission material.

3. The heater assembly of claim 1 or 2, wherein the at least one hole is formed at the center of the second surface.

4. The heater assembly of claim 1 or 2, wherein the at least one hole has an entrance diameter at the second surface of the transmission material between 0.5 mm and 2.5 mm.

5. The heater assembly of claim 4, wherein the at least one hole has an entrance diameter at the second surface of the transmission material between 0.8 mm and 2 mm.

6. The heater assembly of claim 4, wherein the at least one hole has an entrance diameter of 1.3 mm at the second surface of the transmission material.

7. The heater assembly of claim 1, wherein the at least one hole tapers toward the first surface of the transmission material.

8. The heater assembly of claim 1, wherein the at least one hole extends through the entire thickness of the transmissive material to provide a through hole in the transmissive material.

9. A heater assembly according to claim 7 or 8, wherein the at least one hole has an outlet diameter at the first surface of the transport material of between 0.2 mm and 0.4 mm.

10. The heater assembly of claim 9, wherein the at least one hole has an exit diameter at the first surface of the transport material between 0.28 mm and 0.32 mm.

11. The heater assembly of claim 9, wherein the at least one hole has an exit diameter of 0.3 mm at the first surface of the transmission material.

12. The heater assembly of claim 1 or 2, wherein the transmission material comprises a disk.

13. The heater assembly of claim 1 or 2, wherein the transmission material comprises a capillary material having elongated fibers.

14. The heater assembly of claim 13, wherein the average direction of the elongated fibers is in a direction substantially parallel to the first surface and the second surface, and wherein the at least one hole extends in a direction substantially perpendicular to the average direction of the elongated fibers.

15. The heater assembly of claim 1 or 2, wherein the transmission material is provided with a plurality of holes.

16. A method of manufacturing a heater assembly for an aerosol generating system, the method comprising: providing a fluid permeable heating element; providing a transmission material having a thickness defined between a first surface of the transmission material and an opposing second surface of the transmission material; forming at least one hole in the second surface of the transmission material, wherein the at least one hole extends into the transmission material to a depth corresponding to at least a portion of the thickness of the transmission material, and wherein the first surface of the transmission material is convex; The first surface of the transmission material is disposed in fluid communication with the fluid permeable heating element.

17. A method according to claim 16, wherein the transmission material is provided by cutting discs from sections of transmission material with a punch.

18. The method of claim 17, wherein the cutting end of the punch includes a tapered perforator for forming the at least one hole, such that the step of forming the at least one hole is performed during the step of cutting the disk of transfer material.

19. The method of claim 18, wherein the conical perforator has a diameter at its widest portion of between 0.5 mm and 2.5 mm.

20. The method of claim 19, wherein the conical perforator has a diameter at its widest portion of between 0.8 mm and 2 mm.

21. The method of claim 19, wherein the tapered perforator has a diameter of 1.3 mm at its widest portion.

22. A cartridge for an aerosol generating system, the cartridge comprising: A heater assembly according to any one of claims 1 to 15; as well as A liquid storage portion for storing a liquid aerosol-forming substrate.

23. An aerosol generating system comprising: The main part; as well as The cartridge according to claim 22; Wherein the cartridge is removably coupled to the body portion.

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