Patent ID: 12193503

Referring toFIG.1, this shows a schematic illustration of an aerosol-generating system in accordance with an embodiment of the invention. The system comprises two main components, a cartridge100and a main body part200. A connection end115of the cartridge100is removably connected to a corresponding connection end205of the main body part200. The main body part200contains a battery210, which in this example is a rechargeable lithium ion battery, and control circuitry220. The aerosol-generating system is portable and has a size comparable to a conventional cigar or cigarette. A mouthpiece is arranged at the end of the cartridge100opposite the connection end115.

The cartridge100comprises a housing105containing a heater assembly120and a liquid storage compartment having a first portion130and a second portion135. A liquid aerosol-forming substrate is held in the liquid storage compartment. Although not illustrated inFIG.1, the first portion130of the liquid storage compartment is connected to the second portion135of the liquid storage compartment so that liquid in the first portion130can pass to the second portion135. The heater assembly120receives liquid from the second portion135of the liquid storage compartment. The heater assembly120comprises a fluid permeable heater.

An air flow passage140,145extends through the cartridge100from an air inlet150formed in a side of the housing105past the heater assembly120and from the heater assembly120to a mouthpiece opening110formed in the housing105at an end of the cartridge100opposite to the connection end115.

The components of the cartridge100are arranged so that the first portion130of the liquid storage compartment is between the heater assembly120and the mouthpiece opening110, and the second portion135of the liquid storage compartment is positioned on an opposite side of the heater assembly100to the mouthpiece opening110. In other words, the heater assembly120lies between the two portions130,135of the liquid storage compartment and receives liquid from the second portion135. The first portion130of liquid storage compartment is closer to the mouthpiece opening110than the second portion135of the liquid storage compartment. The air flow passage140,145extends past the heater assembly110and between the first130and second135portions of the liquid storage compartment.

The system is configured so that a user can puff or draw on the mouthpiece opening110of the cartridge to draw aerosol into their mouth. In operation, when a user puffs on the mouthpiece opening110, air is drawn through the airflow passage140,145from the air inlet150, past the heater assembly120, to the mouthpiece opening110. The control circuitry220controls the supply of electrical power from the battery210to the cartridge100when the system is activated. This in turn controls the amount and properties of the vapour produced by the heater assembly120. The control circuitry220may include an airflow sensor (not shown) and the control circuitry220may supply electrical power to the heater assembly120when a user's puff is detected by the airflow sensor. This type of control arrangement is well established in aerosol-generating systems such as inhalers and e-cigarettes. So when a user puffs on the mouthpiece opening110of the cartridge100, the heater assembly120is activated and generates a vapour that is entrained in the air flow passing through the air flow passage140. The vapour cools within the airflow in passage145to form an aerosol, which is then drawn into the user's mouth through the mouthpiece opening110.

In operation, the mouthpiece opening110is typically the highest point of the system. The construction of the cartridge100, and in particular the arrangement of the heater assembly120between first and second portions130,135of the liquid storage compartment, is advantageous because it exploits gravity to ensure that the liquid substrate is delivered to the heater assembly120even as the liquid storage compartment is becoming empty, but prevents an oversupply of liquid to the heater assembly120which might lead to leakage of liquid into the air flow passage140.

FIG.2is a schematic cross section of a cartridge100in accordance with an embodiment of the invention. Cartridge100comprises an external housing105having a mouthpiece with a mouthpiece opening110, and a connection end115opposite the mouthpiece. Within the housing105is a liquid storage compartment holding a liquid aerosol-forming substrate131. The liquid storage compartment has a first portion130and a second portion135and liquid is contained in the liquid storage compartment by three further components, an upper storage compartment housing137, a heater mount134and an end cap138. A heater assembly120comprising a fluid permeable heater122and a porous member124is held in the heater mount134. Contact pads (not shown) are provided on opposing sides of the fluid permeable heater122to supply electrical power to the fluid permeable heater122. The heater assembly120is closer to the connection end115so that electrical connection of the heater assembly120to a power supply can be easily and robustly achieved. A retention material136is provided in the second portion135of the liquid storage compartment and abuts the porous member124of the heater assembly120. The retention material136is arranged to transport liquid to the porous member124of the heater assembly120.

The first portion130of the liquid storage compartment is larger than the second portion135of the storage compartment and occupies a space between the heater assembly120and the mouthpiece opening110of the cartridge100. Liquid in the first portion130of the storage compartment can travel to the second portion135of the liquid storage compartment through liquid channels133on either side of the heater assembly120. Two channels are provided in this example to provide a symmetric structure, although only one channel is necessary. The channels are enclosed liquid flow paths defined between the upper storage compartment housing137and the heater mount134.

The fluid permeable heater122is deposited on to a porous outer surface of the porous member124and is arranged on a side of the heater assembly120facing the first portion130of the liquid storage compartment and the mouthpiece opening110. In particular, the fluid permeable heater122is deposited on to a porous first end of the porous member124. A porous second end of the porous member124extends into the second portion135of the liquid storage compartment where it contacts the retention material136such that the porous member124can receive liquid aerosol-forming substrate from the retention material136. The remainder of the second portion135of the liquid storage compartment not occupied by the porous member is occupied by the retention material136which is in fluid communication with the liquid aerosol-forming substrate131delivered via liquid channels133.

An airflow passage140extends between the first and second portions of the storage compartment. A bottom wall of the airflow passage140comprises the fluid permeable heater122. Side walls of the airflow passage140comprise portions of the heater mount134, and a top wall of the airflow passage comprises a surface of the upper storage compartment housing137. The air flow passage has a vertical portion (not shown) that extends through the first portion130of the liquid storage compartment towards the mouthpiece opening110.

It will be appreciated that the arrangement ofFIG.2is only one example of a cartridge for an aerosol-generating system. Other arrangements are possible. For example, the fluid permeable heater, porous member and retention material could be arranged at one end of a cartridge housing, with a liquid storage compartment being arranged at the other.

FIG.3is a schematic illustration of a cross-section of a heater assembly300in accordance with an embodiment of the invention. The drawing is not to scale. The heater assembly300comprises a porous member324and a multi-layer fluid permeable heater322deposited on a porous outer surface of a first end324aof the porous member324. The fluid permeable heater322is formed of first326and second328layers of electrically conductive material. In the present example, the porous member324comprises porous quartz, the first layer326comprises tungsten and the second layer328comprises gold. The thickness of the porous member324is approximately 2.5 mm. The thickness of the first layer326of tungsten is approximately 1200 nm and the thickness of the second layer328of silver is approximately 15 nm. The first layer326has been directly deposited on the porous member324by physical vapour deposition (PVD) and second layer328was then deposited on the first layer326, also by PVD. The aforementioned thickness for the first326and second328layers provide sufficient electrical conductivity for the fluid permeable heater322without filling or blocking the pores of the porous member324such that the porous outer surface upon which the heater is deposited remains porous. The skilled person will appreciate that different combinations of suitable materials and thicknesses can be used, for example, as discussed earlier in this application.

FIG.4is a schematic illustration of a cross-section of a heater assembly400in accordance with a further embodiment of the invention. Again, the drawing is not to scale. The heater assembly is substantially the same as the heater assembly300shown inFIG.3, with the exception that the fluid permeable heater comprises an additional third layer432. In the following description, like reference numerals have been used to designate those parts in common with the heater assembly300shown inFIG.3.

The heater assembly400comprises a porous member424and a multi-layer fluid permeable heater422deposited on a porous outer surface of a first end424aof the porous member424. The fluid permeable heater422is formed of first layer326of tungsten and second layer328of silver. The fluid permeable heater further comprises a third layer432arranged between porous member424and the first layer426. The third layer432is formed of tantalum and is approximately 15 nm thick. A layer of tantalum helps to improve the adhesion of the fluid permeable heater to the porous member424. The thickness of the third layer432is relatively small compared to the overall thickness of the heater and therefore this additional layer can be added without filling or blocking the pores of the porous member324such that the porous outer surface upon which the heater is deposited remains porous. The skilled person will appreciate that different combinations of suitable materials and thicknesses can be used, for example, as discussed earlier in this application.

FIG.5is a schematic illustration of a magnified cross-section of part of a heater assembly500in accordance with an embodiment of the invention. The porous member524comprises a plurality of grains or particles524csintered together. The size of the particles and the degree of sintering may determine the porosity and the size of the pores in the porous member524. For example, if a lower porosity is required, smaller particles with increased sintering can be used and, if a higher porosity is required, larger particles with less sintering can be used. Liquid aerosol-forming substrate531is conveyed through the porous member524by means of capillary action occurring within the pores of the porous member524. The liquid aerosol-forming substrate is conveyed from a second end524bof the porous member524in contact with a store of liquid aerosol-forming substrate to a first end524ahaving a fluid permeable heater522, where it is vaporised, such that vaporised aerosol-forming substrate531ais emitted from the pores in the porous outer surface arranged at the first end524aof the porous member524.

The fluid permeable heater522is deposited on to the porous outer surface by PVD at the first end524aof the porous member524. The fluid permeable heater522comprises multiple layers, although, for simplicity, these are not shown inFIG.5. The multiple layers comprise a first layer of deposited electrically conductive material and a second layer of deposited electrically conductive material having a higher electrical conductivity than the first layer. The second layer is used modify the electrical resistance of the fluid permeable heater522to a required resistance. The fluid permeable heater522may also have a third layer (not shown) such as an adhesion layer arranged between the porous member524and the first layer for improving the adhesion of the first layer to the porous member.

The fluid permeable heater522has partially diffused into the porous outer surface at the first end524of the porous member524, i.e. the fluid permeable heater522partially extends into the pores of the porous outer surface. This assists in improving contact between the fluid permeable heater522and the porous member524and helps increase adhesion between the heater522and the porous member524. The porosity of the porous member524and the thickness of the fluid permeable heater522can be selected to leave the pores in the porous outer surface at the first end524of the porous member524open, i.e. so as to not block the pores.FIG.5shows pores being open such that liquid aerosol-forming substrate which has permeated through the porous member514is vaporised at the fluid permeable heater522and is emitted from the open pores in the fluid permeable heater522as vaporised aerosol-forming substrate531a.

FIG.6is a scanning electron microscope image taken at 150× magnification of part of a heater assembly in accordance with an embodiment of the invention. The heater assembly comprises a quartz porous member having a layer of tungsten deposited as a first layer on the porous member by PVD, which layer having an average thickness of approximately 1200 nm. As can be seen fromFIG.6, the pores in the quartz porous member, i.e. the dark regions between the grains of quartz inFIG.6, remain open and are not blocked by this thickness of first layer.FIG.6shows the heater assembly prior to the deposition of a second layer. However, as discussed above, the thickness of the second layer, i.e. between 10 and 20 nm, is relatively thin compared the thickness of the first layer and therefore its deposition on the first layer is not likely to block the pores.

FIG.7is a scanning electron microscope image taken at 150× magnification of part of a heater assembly in accordance with an embodiment of the invention. The heater assembly comprises a glass fibre porous member having a layer of tungsten deposited as a first layer on the porous member by PVD, which layer having an average thickness of approximately 500 nm. As can be seen fromFIG.7, the pores in the glass fibre porous member, i.e. the dark regions between the glass fibres inFIG.7, remain open and are not blocked by this thickness of first layer.FIG.7shows the heater assembly prior to the deposition of a second layer. However, as discussed above, the thickness of the second layer, i.e. between 10 and 20 nm, is relatively thin compared the thickness of the first layer and therefore its deposition on the first layer is not likely to block the pores.