Aerosol-generating device with narrowed RTD passage

Abstract

The invention relates to an aerosol-generating device comprising a cavity for receiving a cartridge comprising aerosol-forming substrate. The aerosol-generating device further comprises an airflow channel fluidly connecting the cavity with an ambient environment. The aerosol-generating device further comprises a constriction element. The constriction element comprises a constricted airflow passage. The constriction element is configured with a predetermined resistance to draw (RTD). The constricted airflow passage is arranged in fluid communication with the airflow channel. The RTD of the constriction element is higher than the RTD of the rest of the airflow channel. An inner diameter of the constricted airflow passage is smaller than an inner diameter of the rest of the airflow channel. The invention further relates to an aerosol-generating system comprising the aerosol-generating device and a constriction element. The invention further relates to a kit comprising the aerosol-generating device, a first constriction element and a second constriction element.

Description

[0001] AEROSOL-GENERATING DEVICE WITH NARROWED RTD PASSAGE

[0002] The present invention relates to an aerosol-generating device. The invention further relates to an aerosol-generating system comprising the aerosol-generating device and a constriction element. The invention further relates to a kit comprising the aerosol-generating device, a first constriction element and a second constriction element.

[0003] It is known to provide an aerosol-generating device for generating an inhalable vapor. Such devices may heat aerosol-forming substrate to a temperature at which one or more components of the aerosol-forming substrate are volatilised without burning the aerosolforming substrate. Aerosol-forming substrate may be provided as part of the cartridge. The cartridge may be received in a cavity, such as a heating chamber, of the aerosol-generating device. A heating element may be arranged in or around the heating chamber for heating the aerosol-forming substrate once the cartridge is inserted into the heating chamber of the aerosol-generating device. The aerosol-generating device should have a well-defined resistance to draw (RTD) or a pleasant user experience.

[0004] It would be desirable to have an aerosol-generating device with a well-defined RTD. It would be desirable to have an aerosol-generating device with improved RTD accuracy. It would be desirable to have an aerosol-generating device with adjustable RTD.

[0005] According to an embodiment of the invention there may be provided an aerosolgenerating device comprising a cavity for receiving a cartridge comprising aerosol-forming substrate. The aerosol-generating device may further comprise an airflow channel fluidly connecting the cavity with an ambient environment. The aerosol-generating device may further comprise a constriction element. The constriction element may comprise a constricted airflow passage. The constriction element may be configured with a predetermined resistance to draw (RTD). The constricted airflow passage may be arranged in fluid communication with the airflow channel. The RTD of the constriction element may be higher than the RTD of the rest of the airflow channel. An inner diameter of the constricted airflow passage may be smaller than an inner diameter of the rest of the airflow channel.

[0006] According to an embodiment of the invention there is provided an aerosol-generating device comprising a cavity for receiving a cartridge comprising aerosol-forming substrate. The aerosol-generating device further comprises an airflow channel fluidly connecting the cavity with an ambient environment. The aerosol-generating device further comprises a constriction element. The constriction element comprises a constricted airflow passage. The constriction element is configured with a predetermined resistance to draw (RTD). The constricted airflow passage is arranged in fluid communication with the airflow channel. The RTD of the constriction element is higher than the RTD of the rest of the airflow channel. An inner diameter of the constricted airflow passage is smaller than an inner diameter of the rest of the airflow channel.

[0007] Preferably, the constriction element, particularly the constricted airflow passage of the constriction element, defines the overall resistance to draw of the aerosol-generating device. This may be particularly beneficial in order to provide a reliable resistance to draw of the aerosol-generating device. If no defined portion for defining the resistance to draw is provided, manufacturing tolerances may lead to a variance in the resistance to draw of the final aerosolgenerating device.

[0008] However, providing a constricted airflow passage having a defined resistance to draw enables manufacturing of this specific portion with high manufacturing tolerances so as to reliably define the overall resistance to draw of the aerosol-generating device. Preferably, the resistance to draw of the constricted airflow passage is significantly higher than the resistance to draw of the further components of the aerosol-generating device through which air is drawn. Hence, the other components of the aerosol-generating device through which air is drawn are insignificant with respect to contributing to the overall resistance to draw of the aerosolgenerating device in comparison to the resistance to draw of the constricted airflow passage. In this way, it is possible to define the overall resistance to draw of the aerosol-generating device by defining the resistance to draw of the constricted airflow passage of the constriction element.

[0009] As used herein, the term “resistance to draw” (RTD), is used to describe the resistance for air to be drawn through a material. As used herein, resistance to draw is expressed with the units of pressure "millimetres of water gauge" and is measured in accordance with ISO 6565:2015.

[0010] The constricted airflow passage may have an inner diameter of between 0.8 mm and 1.2 mm, preferably of between 0.9 mm and 1.1 mm, more preferably of 1 mm.

[0011] The constricted airflow passage may have a length of between 11 mm and 19 mm, preferably of between 13 mm and 17 mm, more preferably of 15 mm.

[0012] The constriction element may have an RTD of between 40 mmWC and 80 mmWC, preferably of between 50 mmWC and 70 mmWC, more preferably of 60 mmWC.

[0013] The constriction element may have an RTD of at least 40 mmWC, preferably of at least 50 mmWC, more preferably of at least 60 mmWC.

[0014] The airflow channel, apart from the constricted airflow passage, may have an RTD of between 5 mmWC and 30 mmWC, preferably of between 7 mmWC and 20 mmWC, more preferably of 10 mmWC. The airflow channel, apart from the constricted airflow passage, may have an inner diameter of between 1.3 mm and 4 mm, preferably of between 1.4 millimeter and 3.5 millimeter, more preferably of between 1 .5 millimeter and 3 mm.

[0015] The airflow channel, apart from the constricted airflow passage, may have an inner diameter of at least 1 .3 mm, preferably of at least 1.4 mm, more preferably of at least 1.5 mm.

[0016] The constricted airflow passage of the constriction element may be part of the airflow channel.

[0017] The aerosol-generating device may further comprise an air inlet allowing ambient air to be drawn into the aerosol-generating device, wherein the air inlet may be fluidly connected with the airflow channel, and wherein the constricted airflow passage of the constriction element may be arranged downstream of the air inlet.

[0018] The constriction element may be integrally formed with the aerosol-generating device.

[0019] As an alternative to providing the constriction element integrally formed with the aerosol-generating device, the constriction element may be configured removably attachable to the aerosol-generating device.

[0020] The constriction element may be configured removably attachable to an upstream end of the aerosol-generating device.

[0021] The aerosol-generating device may comprise an upstream slot into which the constriction element can be removably attached, wherein the upstream slot may be fluidly connected with the airflow channel.

[0022] The constriction element may comprise a protective grill with multiple fluid permeable holes.

[0023] The protective grill may be configured to prevent inadvertent blockage of ambient air being drawn into the aerosol-generating device.

[0024] The invention further relates to an aerosol-generating system comprising the aerosolgenerating device as described herein and a constriction element. The constriction element may be configured removably attachable to the upstream end of the aerosol-generating device.

[0025] The invention further relates to a kit comprising the aerosol-generating device as described herein, a first constriction element and a second constriction element. The first and second constriction elements may be configured removably attachable to the upstream end of the aerosol-generating device. The RTD of the first constriction element may be different from the RTD of the second constriction element.

[0026] The invention further relates to a kit comprising the aerosol-generating device as described herein, a first constriction element and a second constriction element. The first and second constriction elements are configured removably attachable to the upstream end of the aerosol-generating device. The RTD of the first constriction element is different from the RTD of the second constriction element.

[0027] The cartridge may have a length. The length may be measured along the longitudinal central axis of the cartridge. The length may be made from a proximal end of the cartridge to a distal end of the cartridge.

[0028] The cartridge may have a width. The width of the cartridge may be measured perpendicular to the length of the cartridge.

[0029] The cartridge may have a thickness. The thickness of the cartridge may be measured perpendicular to the length of the cartridge and perpendicular to the width of the cartridge.

[0030] The width of the cartridge may be larger than the thickness of the cartridge.

[0031] The cartridge may be configured as a replaceable cartridge. In other words, the cartridge may be provided as external to the aerosol-generating device so that the cartridge can be received by the aerosol-generating device, more particularly by the cavity of the aerosol-generating device. After the cartridge is spent, the spent cartridge can be removed from the cavity of the aerosol-generating device and a fresh cartridge can be inserted into the cavity of the aerosol-generating device.

[0032] The cartridge may comprise a substrate storage portion. The substrate storage portion may be fluidly connected with the cartridge outlet.

[0033] The heating element may be arranged in the cartridge. The heating element may be arranged in the cartridge in order to heat the aerosol-forming substrate also arranged in the cartridge.

[0034] The electrical contacts of the cartridge may electrically contact the heating element. The electrical contacts may be arranged on the housing of the cartridge. When the cartridge is received in the cavity of the aerosol-generating device, the electrical contacts of the cartridge may electrically contact corresponding electrical contacts of the aerosol-generating device, preferably of a main body of the aerosol-generating device. The electrical contacts of the aerosol-generating device may be electrically contacted with the power supply of the aerosolgenerating device. In this way, when the cartridge is received in the cavity, the power supply of the aerosol-generating device can power the heating element of the cartridge.

[0035] The heating element may be configured as a resistive heating element. The heating element may comprise heating tracks. The heating tracks may be arranged in a wound, coiled, zigzag or spiral pattern.

[0036] Alternatively, the heating element may be configured as an inductive heating element. In case of being an inductive heating element, the heating element may comprise an induction coil. Potentially, the heating element may further comprise a susceptor element which may be heated by eddy currents induced by an alternating current running through the induction coil. The susceptor element in this case may be arranged inside of the induction coil. The susceptor element may be provided in the cartridge while the induction coil may be provided in the aerosol-generating device, particularly the main body of the aerosol-generating device. Alternatively, both the susceptor element as well as the induction coil may be provided in the cartridge.

[0037] The aerosol-generating device may comprise the main body and a mouthpiece.

[0038] The main body of the aerosol-generating device may comprise a power supply, preferably a battery, for powering a heating element of the aerosol-generating system.

[0039] The main body of the aerosol-generating device may comprise electric circuitry, preferably comprising a controller, for controlling the supply of electrical energy from the power supply to the heating element.

[0040] The cavity of the aerosol-generating device may be arranged at a proximal end of the main body. The cavity may have a hollow cylindrical shape. The cavity may have a circular cross-section. Alternatively, the cavity may have a rectangular or oval cross-section.

[0041] The main body may comprise an air inlet. The air inlet may be fluidly connected with the base of the cavity. When a user draws on the mouthpiece, ambient air may be drawn into an airflow channel of the aerosol-generating device through the air inlet. From the airflow channel running through the main body, the air may be drawn into the cavity at one or more apertures at the base of the cavity. This section of the cavity may be referred to as the main body outlet. When the cartridge is received in the cavity, the air may then be drawn into the cartridge through a cartridge inlet. The cartridge inlet may be arranged at a distal end of the cartridge. The air may then be drawn through the cartridge, particularly through the substrate storage of the cartridge and subsequently out of the cartridge through the cartridge outlet. The air then enters the mouthpiece, particularly through a mouthpiece inlet. The airflow channel may continue through the mouthpiece towards a mouthpiece outlet. The user may put his or her lips at the mouthpiece outlet to inhale the generated aerosol.

[0042] The mouthpiece of the aerosol-generating device may be arranged such that the mouthpiece may close the cavity. Closing the cavity may be performed after insertion of the cartridge into the cavity. In other words, the cartridge may be sandwiched between the main body of the aerosol-generating device and the closed mouthpiece of the aerosol-generating device after insertion of the cartridge into the cavity.

[0043] The mouthpiece may be connected to the main body. The mouthpiece may be hingedly connected to the main body. The mouthpiece may be opened in order to allow insertion of the cartridge into the cavity. The mouthpiece may be closed to lock the cartridge in place. The cartridge may comprise a cartridge inlet and the main body may comprise a main body outlet. The cartridge inlet may be fluidly connected with the main body outlet. The cartridge inlet may be formed by one or both of the proximal air openings and the distal air openings.

[0044] The cartridge may comprise a cartridge outlet and the mouthpiece may comprise a mouthpiece inlet. The cartridge outlet may be fluidly connected with the mouthpiece inlet. The cartridge outlet may be formed by one or both of the proximal air openings and the distal air openings.

[0045] The main body may comprise an air inlet. The air inlet may be fluidly connected with the base of the cavity. When a user draws on the mouthpiece, ambient air may be drawn into an airflow channel of the aerosol-generating device through the air inlet. From the airflow channel running through the main body, the air may be drawn into the cavity at one or more apertures at the base of the cavity. This section of the cavity may be referred to as the main body outlet. When the cartridge is received in the cavity, the air may then be drawn into the cartridge through the cartridge inlet. The cartridge inlet may be arranged at a distal end of the cartridge. The air may then be drawn through the cartridge, particularly through the substrate storage of the cartridge and subsequently out of the cartridge through the cartridge outlet. The air then enters the mouthpiece, particularly through the mouthpiece inlet. The airflow channel may continue through the mouthpiece towards a mouthpiece outlet. The user may put his or her lips at the mouthpiece outlet to inhale the generated aerosol.

[0046] The cartridge may be configured as described in one of WO2022154863, WO2022154869 and WO2021262266, which are incorporated herein by reference. Specifically, cartridge dimensions and internal volumes as described in one of WO2022154863, WO2022154869 and WO2021262266, which are incorporated herein by reference.

[0047] The cartridge may be configured as a replaceable cartridge. The cartridge may comprise a substrate storage for holding the aerosol-forming substrate.

[0048] The aerosol-forming substrate may be as described in one of WO2022154863, WO2022154869 and WO2021262266, which are incorporated herein by reference.

[0049] The aerosol-forming substrate may be solid. The aerosol-forming substrate may comprise tobacco, preferably consist of tobacco. The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may contain an aerosol former, preferably glycerin.

[0050] Alternatively, the aerosol-forming substrate may be liquid or gel-like. Also in this case, the aerosol-forming substrate may comprise one or more of tobacco, nicotine and an aerosol former, preferably glycerin. The aerosol-forming substrate may be held in a matrix. The matrix may be arranged within the substrate storage. The matrix may comprise, preferably consists of, a capillary material.

[0051] As used herein, the terms ‘proximal’, ‘distal’, ‘downstream’ and ‘upstream’ are used to describe the relative positions of components, or portions of components, of the aerosolgenerating device in relation to the direction in which a user draws on the aerosol-generating device during use thereof.

[0052] The aerosol-generating device may comprise a mouth end through which in use an aerosol exits the aerosol-generating device and is delivered to a user. The mouth end may also be referred to as the proximal end. In use, a user draws on the proximal or mouth end of the aerosol-generating device in order to inhale an aerosol generated by the aerosolgenerating device. The mouth end may be part of the mouthpiece. The aerosol-generating device comprises a distal end opposed to the proximal or mouth end. The proximal or mouth end of the aerosol-generating device may also be referred to as the downstream end and the distal end of the aerosol-generating device may also be referred to as the upstream end. Components, or portions of components, of the aerosol-generating device may be described as being upstream or downstream of one another based on their relative positions between the proximal, downstream or mouth end and the distal or upstream end of the aerosolgenerating device.

[0053] As used herein, an ‘aerosol-generating device’ relates to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-forming substrate may be part of a cartridge. An aerosol-generating device may be a smoking device that interacts with an aerosol-forming substrate of a cartridge to generate an aerosol that is directly inhalable into a user’s lungs thorough the user's mouth. An aerosol-generating device may be a holder. The device may be an electrically heated smoking device. The aerosol-generating device may comprise a housing, electric circuitry, a power supply and a heating chamber.

[0054] As used herein with reference to the present invention, the term ‘smoking’ with reference to a device, article, system, substrate, or otherwise does not refer to conventional smoking in which an aerosol-forming substrate is fully or at least partially combusted. The aerosol-generating device of the present invention is arranged to heat the aerosol-forming substrate to a temperature below a combustion temperature of the aerosol-forming substrate, but at or above a temperature at which one or more volatile compounds of the aerosol-forming substrate are released to form an inhalable aerosol.

[0055] The aerosol-generating device may comprise electric circuitry. The electric circuitry may comprise a microprocessor, which may be a programmable microprocessor. The microprocessor may be part of a controller. The electric circuitry may comprise further electronic components. The electric circuitry may be configured to regulate a supply of power to the heating element. The heating element may be part of the cartridge. Power may be supplied to the heating element continuously following activation of the aerosol-generating device or may be supplied intermittently, such as on a puff-by-puff basis. The power may be supplied to the heating element in the form of pulses of electrical current. The electric circuitry may be configured to monitor the electrical resistance of the heating element, and preferably to control the supply of power to the heating element dependent on the electrical resistance of the heating element.

[0056] The aerosol-generating device may comprise a power supply, typically a battery, within a main body of the aerosol-generating device. In one embodiment, the power supply is a Lithium-ion battery. Alternatively, the power supply may be a Nickel-metal hydride battery, a Nickel cadmium battery, or a Lithium based battery, for example a Lithium-Cobalt, a Lithium- Iron-Phosphate, Lithium Titanate or a Lithium-Polymer battery. As an alternative, the power supply may be another form of charge storage device such as a capacitor. The power supply may require recharging and may have a capacity that enables to store enough energy for one or more usage experiences; for example, the power supply may have sufficient capacity to continuously generate aerosol for a period of around six minutes or for a period of a multiple of six minutes. In another example, the power supply may have sufficient capacity to provide a predetermined number of puffs or discrete activations of the heating element.

[0057] The cavity of the aerosol-generating device may have an open end into which the cartridge is inserted. The open end may be a proximal end. The cavity may have a closed end opposite the open end. The closed end may be the base of the cavity. The closed end may be closed except for the provision of air apertures arranged in the base. The base of the cavity may be flat. The base of the cavity may be circular. The base of the cavity may be arranged upstream of the cavity. The open end may be arranged downstream of the cavity. The cavity may have an elongate extension. The cavity may have a longitudinal central axis. A longitudinal direction may be the direction extending between the open and closed ends along the longitudinal central axis. The longitudinal central axis of the cavity may be parallel to the longitudinal axis of the aerosol-generating device.

[0058] The cavity may be configured as a heating chamber. The cavity may have a cylindrical shape. The cavity may have a hollow cylindrical shape. The cavity may have a shape corresponding to the shape of the aerosol-generating article to be received in the cavity. The cavity may have a circular cross-section. The cavity may have an elliptical or rectangular crosssection. The cavity may have an inner diameter corresponding to the outer diameter of the aerosol-generating article. An airflow channel may run through the cavity. Ambient air may be drawn into the aerosol-generating device, into the cavity and towards the user through the airflow channel. Downstream of the cavity, the mouthpiece may be arranged. The airflow channel may extend through the mouthpiece.

[0059] In any of the aspects of the disclosure, the heating element may comprise an electrically resistive material. Suitable electrically resistive materials include but are not limited to: semiconductors such as doped ceramics, electrically "conductive" ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum platinum, gold and silver. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetai® and iron-manganese-aluminium based alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required.

[0060] As described, in any of the aspects of the disclosure, the heating element may be part of a cartridge. The cartridge may comprise an internal heating element or an external heating element, or both internal and external heating elements, where "internal" and "external" refer to the aerosol-forming substrate. An internal heating element may take any suitable form. For example, an internal heating element may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different electro-conductive portions, or an electrically resistive metallic tube. Alternatively, the internal heating element may be one or more heating needles or rods that run through the center of the aerosol-forming substrate. Other alternatives include a heating wire or filament, for example a Ni-Cr (Nickel-Chromium), platinum, tungsten or alloy wire or a heating plate. Optionally, the internal heating element may be deposited in or on a rigid carrier material. In one such embodiment, the electrically resistive heating element may be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track on a suitable insulating material, such as ceramic material, and then sandwiched in another insulating material, such as a glass. Heaters formed in this manner may be used to both heat and monitor the temperature of the heating elements during operation. An external heating element, which is particularly preferred, may take any suitable form. For example, an external heating element may take the form of one or more flexible heating foils or tracks on a dielectric substrate, such as polyimide. The flexible heating foils or tracks can be shaped to conform to the perimeter of the substrate receiving cavity. Alternatively, an external heating element may take the form of a metallic grid or grids, a flexible printed circuit board, a molded interconnect device (MID), ceramic heater, flexible carbon fibre heater or may be formed using a coating technique, such as plasma vapour deposition, on a suitable shaped substrate. An external heating element may also be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track between two layers of suitable insulating materials. An external heating element formed in this manner may be used to both heat and monitor the temperature of the external heating element during operation.

[0061] As an alternative to an electrically resistive heating element, the heating element may be configured as an induction heating element. The induction heating element may comprise an induction coil and a susceptor. In general, a susceptor is a material that is capable of generating heat, when penetrated by an alternating magnetic field. When located in an alternating magnetic field. If the susceptor is conductive, then typically eddy currents are induced by the alternating magnetic field. If the susceptor is magnetic, then typically another effect that contributes to the heating is commonly referred to hysteresis losses. Hysteresis losses occur mainly due to the movement of the magnetic domain blocks within the susceptor, because the magnetic orientation of these will align with the magnetic induction field, which alternates. Another effect contributing to the hysteresis loss is when the magnetic domains will grow or shrink within the susceptor. Commonly all these changes in the susceptor that happen on a nano-scale or below are referred to as “hysteresis losses”, because they produce heat in the susceptor. Hence, if the susceptor is both magnetic and electrically conductive, both hysteresis losses and the generation of eddy currents will contribute to the heating of the susceptor. If the susceptor is magnetic, but not conductive, then hysteresis losses will be the only means by which the susceptor will heat, when penetrated by an alternating magnetic field. According to the invention, the susceptor may be electrically conductive or magnetic or both electrically conductive and magnetic. An alternating magnetic field generated by one or several induction coils heat the susceptor, which then transfers the heat to the aerosol-forming substrate, such that an aerosol is formed. The heat transfer may be mainly by conduction of heat. Such a transfer of heat is best, if the susceptor is in close thermal contact with the aerosol-forming substrate.

[0062] As used herein, the term ‘cartridge’ refers to an element comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. For example, a cartridge may be a smoking cartridge that generates an aerosol that is directly inhalable into a user’s lungs through the user's mouth. A cartridge may be disposable.

[0063] As used herein, the term ‘aerosol-forming substrate’ relates to a substrate capable of releasing one or more volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. An aerosol-forming substrate may conveniently be part of an aerosol-generating article or smoking article.

[0064] The aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosolforming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise an aerosol former that facilitates the formation of a dense and stable aerosol. Examples of suitable aerosol formers are glycerine and propylene glycol.

[0065] The aerosol-generating substrate preferably comprises homogenised tobacco material, an aerosol-former and water. Providing homogenised tobacco material may improve aerosol generation, the nicotine content and the flavour profile of the aerosol generated during heating of the aerosol-generating article. Specifically, the process of making homogenised tobacco involves grinding tobacco leaf, which more effectively enables the release of nicotine and flavours upon heating.

[0066] Below, there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0067] Example 1. An aerosol-generating device comprising: a cavity for receiving a cartridge comprising aerosol-forming substrate, an airflow channel fluidly connecting the cavity with an ambient environment, and a constriction element, wherein the constriction element comprises a constricted airflow passage, wherein the constriction element is configured with a predetermined resistance to draw (RTD), wherein the constricted airflow passage is arranged in fluid communication with the airflow channel, wherein the RTD of the constriction element is higher than the RTD of the rest of the airflow channel, and wherein an inner diameter of the constricted airflow passage is smaller than an inner diameter of the rest of the airflow channel.

[0068] Example 2. The aerosol-generating device according to example 1 , wherein the constricted airflow passage has an inner diameter of between 0.8 mm and 1.2 mm, preferably of between 0.9 mm and 1.1 mm, more preferably of 1 mm. Example 3. The aerosol-generating device according to any of the preceding examples, wherein the constricted airflow passage has a length of between 11 mm and 19 mm, preferably of between 13 mm and 17 mm, more preferably of 15 mm.

[0069] Example 4. The aerosol-generating device according to any of the preceding examples, wherein the constriction element has an RTD of between 40 mmWC and 80 mmWC, preferably of between 50 mmWC and 70 mmWC, more preferably of 60 mmWC.

[0070] Example 5. The aerosol-generating device according to any of the preceding examples, wherein the constriction element has an RTD of at least 40 mmWC, preferably of at least 50 mmWC, more preferably of at least 60 mmWC.

[0071] Example 6. The aerosol-generating device according to any of the preceding examples, wherein the airflow channel, apart from the constricted airflow passage, has an RTD of between 5 mmWC and 30 mmWC, preferably of between 7 mmWC and 20 mmWC, more preferably of 10 mmWC.

[0072] Example 7. The aerosol-generating device according to any of the preceding examples, wherein the airflow channel, apart from the constricted airflow passage, has an inner diameter of between 1.3 mm and 4 mm, preferably of between 1.4 millimeter and 3.5 millimeter, more preferably of between 1.5 millimeter and 3 mm.

[0073] Example 8. The aerosol-generating device according to any of the preceding examples, wherein the airflow channel, apart from the constricted airflow passage, has an inner diameter of at least 1.3 mm, preferably of at least 1 .4 mm, more preferably of at least 1.5 mm.

[0074] Example 9. The aerosol-generating device according to any of the preceding examples, wherein the constricted airflow passage of the constriction element is part of the airflow channel.

[0075] Example 10. The aerosol-generating device according to example 9, wherein the aerosol-generating device further comprises an air inlet allowing ambient air to be drawn into the aerosol-generating device, wherein the air inlet is fluidly connected with the airflow channel, and wherein the constricted airflow passage of the constriction element is arranged downstream of the air inlet.

[0076] Example 11. The aerosol-generating device according to example 9 or 10, wherein the constriction element is integrally formed with the aerosol-generating device.

[0077] Example 12. The aerosol-generating device according to any of examples 1 to 8, wherein the constriction element is configured removably attachable to the aerosol-generating device. Example 13. The aerosol-generating device according to example 12, wherein the constriction element is configured removably attachable to an upstream end of the aerosolgenerating device.

[0078] Example 14. The aerosol-generating device according to example 12 or 13, wherein the aerosol-generating device comprises an upstream slot into which the constriction element can be removably attached, wherein the upstream slot is fluidly connected with the airflow channel.

[0079] Example 15. The aerosol-generating device according to any of examples 12 to 14, wherein the constriction element comprises a protective grill with multiple fluid permeable holes.

[0080] Example 16. The aerosol-generating device according to example 15, wherein the protective grill is configured to prevent inadvertent blockage of ambient air being drawn into the aerosol-generating device.

[0081] Example 17. An aerosol-generating system comprising the aerosol-generating device of any of examples 1 to 8 and 12 to 16 and a constriction element, wherein the constriction element is configured removably attachable to the upstream end of the aerosolgenerating device.

[0082] Example 18. A kit comprising the aerosol-generating device of any of examples 1 to 8 and 12 to 16, a first constriction element and a second constriction element, wherein the first and second constriction elements are configured removably attachable to the upstream end of the aerosol-generating device, and wherein the RTD of the first constriction element is different from the RTD of the second constriction element.

[0083] Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

[0084] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0085] Fig. 1 shows an aerosol-generating system comprising an aerosol-generating device and a replaceable cartridge;

[0086] Fig. 2 shows a constriction element of the aerosol-generating device having a constricted airflow passage;

[0087] Fig. 3 shows an alternative placement of the constricted airflow passage; and

[0088] Fig. 4 shows the constriction element as a replaceable element.

[0089] Figure 1 shows an aerosol-generating system 10 comprising an aerosol-generating device and a replaceable cartridge 12. The aerosol-generating device comprises a main body 14 and a mouthpiece 16. The mouthpiece 16 is hingedly connected with the main body 14 and can be opened such that the cartridge 12 can be inserted into a cavity 18 of the aerosolgenerating device. After insertion of the cartridge 12 into the cavity 18 of the aerosol-generating device, the mouthpiece 16 can be closed. After closing of the mouthpiece 16, the cartridge 12 is held between the mouthpiece 16 and the main body 14 of the aerosol-generating device.

[0090] At the base 20 of the cavity 18, a main body outlet 22 is provided. Ambient air can be drawn through the aerosol-generating device, particularly the main body 14 of the aerosolgenerating device, and into the cavity 18 via the main body outlet 22. When the cartridge 12 is received in the cavity 18, the air can be drawn into the cartridge 12 via a cartridge inlet 24. After being drawn through the cartridge 12, the air can exit the cartridge 12 through a cartridge outlet 26.

[0091] While traveling through the cartridge 12, vaporized aerosol-forming substrate contained in the cartridge 12 is entrained in the airflow. The aerosol-forming substrate is vaporized by means of heating the aerosol-forming substrate. In order to heat the aerosol-forming substrate, a heating element (not shown) is provided within the cartridge 12. The aerosol-forming substrate may be contained in a substrate storage (not shown) of the cartridge 12.

[0092] After exiting the cartridge 12, the airflow containing the vaporized aerosol-forming substrate enters the mouthpiece 16 for aerosol formation. The generated aerosol exits the mouthpiece 16 via a mouthpiece outlet 28 can then be inhaled by a user.

[0093] For supplying electrical energy to the heating element of the cartridge 12, the main body 14 of the aerosol-generating device comprises a power supply 30 in the form of a battery. The cartridge 12 comprises electrical contacts (not shown). In the cavity 18 of the main body 14 of the aerosol-generating device, corresponding contacts (not shown) are provided. When the cartridge 12 is inserted into the cavity 18 of the aerosol-generating device, the contacts of the cartridge 12 come into contact with the contacts of the cavity 18 so as to establish electrical connection between the cartridge 12 and the main body 14 of the aerosol generating device. In this way, electrical energy can be provided from the power supply 30 of the aerosolgenerating device to the heating element of the cartridge 12. In order to control the supply of electrical energy from the power supply 30 to the heating element, the main body 14 of the aerosol-generating device comprises a controller 32.

[0094] Further, figure 1 shows an airflow channel 34 through the aerosol-generating device, particularly through the main body 14 of the aerosol-generating device. The airflow channel 34 is fluidly connected with the main body outlet 22 at the base 20 of the cavity 18. The aerosolgenerating device may further comprise an air inlet 36 configured to allow ambient air to be drawn into the airflow channel 34. Between the air inlet 36 and the airflow channel 34, an intermediate channel 38 may be provided. The air inlet 36 is fluidly connected with the intermediate channel 38. The intermediate channel 38 is fluidly connected with the airflow channel 34. The airflow channel 34 is fluidly connected with the main body outlet 22.

[0095] Figure 2 shows a further element in comparison to the design of Figure 1. In more detail, a constricted airflow passage 40 is provided as part of a constriction element in figure 2. The constricted airflow passage 40 has an inner diameter that is significantly smaller than the inner diameter of the rest of the elements of the aerosol-generating device through which air is drawn from the air inlet 36 into the cavity 18. In other words, the constricted airflow passage 40 has an inner diameter that is smaller than an inner diameter of the air inlet 36, of the intermediate channel 38, of the airflow channel 34 and of the main body outlet 22. As a result of the smaller inner diameter of the constricted airflow passage 40, the constricted airflow passage 40 has a significantly higher resistance to draw in comparison to the other elements of the aerosol-generating device through which air is drawn from the air inlet 36 to the main body outlet 22. The constricted airflow passage 40 has a predefined resistance to draw which is chosen so as to define the overall resistance to draw of the aerosol-generating device.

[0096] Figure 3 shows a variation of the arrangement of the constricted airflow passage 40. The constricted airflow passage 40 shown in figure 3 is arranged more downstream in comparison to the arrangement of the constricted airflow passage 40 shown in figure 2. The constricted airflow passage 40 can adopt various geometries, including a bent structure resembling a joint coupler, and does not necessarily need to be straight.

[0097] Figure 4 shows a configuration of the constricted airflow passage 40, in which the constricted airflow passage 40 as well as the constriction element 42 are configured removably insertable within an upstream slot 44 into which the constriction element can be removably attached the upstream slot 44 is fluidly connected with the airflow channel 34. The upstream slot 44 is arranged at the upstream end of the aerosol-generating device. The upstream end of the aerosol-generating device may be at the distal end of the aerosol-generating device. The upstream slot 44 may replace the air inlet 36.

[0098] Providing the constriction element 42 as a removably insertable element may enable different constriction elements 42 to be used together with a single aerosol-generating device. For example, a first constriction element 42 with a first constricted airflow passage 40 may be used, wherein the first constricted airflow passage 40 has a first resistance to draw. A second constriction element 42 with a second constricted airflow passage 40 may be used, wherein the second constricted airflow passage 40 has a second resistance to draw. The first resistance to draw may be different from the second resistance to draw. In this way, user can exchange the constriction elements 42 when a different resistance to draw of the aerosolgenerating device is desired. The constriction element comprises a protective grill 46 with multiple fluid permeable holes. The protective grill 46 prevent unwanted clogging of the constriction element 42, for example by a user placing a finger over the constriction element 42.

Claims

CLAIMS1. An aerosol-generating device comprising: a cavity for receiving a cartridge comprising aerosol-forming substrate, an airflow channel fluidly connecting the cavity with an ambient environment, and a constriction element, wherein the constriction element comprises a constricted airflow passage, wherein the constriction element is configured with a predetermined resistance to draw (RTD), wherein the constricted airflow passage is arranged in fluid communication with the airflow channel, wherein the RTD of the constriction element is higher than the RTD of the rest of the airflow channel, wherein an inner diameter of the constricted airflow passage is smaller than an inner diameter of the rest of the airflow channel, and wherein the constriction element comprises a protective grill with multiple fluid permeable holes.

2. The aerosol-generating device according to claim 1 , wherein the constricted airflow passage has an inner diameter of between 0.8 mm and 1 .2 mm, preferably of between 0.9 mm and 1.1 mm, more preferably of 1 mm.

3. The aerosol-generating device according to any of the preceding claims, wherein the constricted airflow passage has a length of between 11 mm and 19 mm, preferably of between 13 mm and 17 mm, more preferably of 15 mm.

4. The aerosol-generating device according to any of the preceding claims, wherein the constriction element has an RTD of between 40 mmWC and 80 mmWC, preferably of between 50 mmWC and 70 mmWC, more preferably of 60 mmWC.

5. The aerosol-generating device according to any of the preceding claims, wherein the airflow channel, apart from the constricted airflow passage, has an RTD of between 5 mmWC and 30 mmWC, preferably of between 7 mmWC and 20 mmWC, more preferably of 10 mmWC.

6. The aerosol-generating device according to any of the preceding claims, wherein the airflow channel, apart from the constricted airflow passage, has an inner diameter of between 1.3 mm and 4 mm, preferably of between 1.4 millimeter and 3.5 millimeter, more preferably of between 1 .5 millimeter and 3 mm.

7. The aerosol-generating device according to any of the preceding claims, wherein the constricted airflow passage of the constriction element is part of the airflow channel.

8. The aerosol-generating device according to claim 7, wherein the aerosolgenerating device further comprises an air inlet allowing ambient air to be drawn into the aerosol-generating device, wherein the air inlet is fluidly connected with the airflow channel, and wherein the constricted airflow passage of the constriction element is arranged downstream of the air inlet.

9. The aerosol-generating device according to claim 7 or 8, wherein the constriction element is integrally formed with the aerosol-generating device.

10. The aerosol-generating device according to any of claims 1 to 7, wherein the constriction element is configured removably attachable to the aerosol-generating device.

11. The aerosol-generating device according to claim 10, wherein the constriction element is configured removably attachable to an upstream end of the aerosol-generating device.

12. The aerosol-generating device according to claim 10 or 11 , wherein the aerosolgenerating device comprises an upstream slot into which the constriction element can be removably attached, wherein the upstream slot is fluidly connected with the airflow channel.

13. An aerosol-generating system comprising an aerosol-generating device comprising a cavity for receiving a cartridge comprising aerosol-forming substrate, and an airflow channel fluidly connecting the cavity with an ambient environment; and a constriction element, wherein the constriction element comprises a constricted airflow passage, wherein the constriction element is configured with a predetermined resistance to draw (RTD), wherein the constricted airflow passage is arranged in fluid communication with the airflow channel when the constriction element is removably attached to an upstream end of the aerosol-generating device, wherein the RTD of the constriction element is higher than the RTD of the rest of the airflow channel, wherein an inner diameter of the constricted airflow passage is smaller than an inner diameter of the rest of the airflow channel, wherein the constriction element comprisesa protective grill with multiple fluid permeable holes, and wherein the constriction element is configured removably attachable to the upstream end of the aerosol-generating device.

14. A kit comprising an aerosol-generating device comprising a cavity for receiving a cartridge comprising aerosol-forming substrate, and an airflow channel fluidly connecting the cavity with an ambient environment; a first constriction element, wherein the first constriction element comprises a constricted airflow passage, wherein the first constriction element is configured with a predetermined resistance to draw (RTD), wherein the constricted airflow passage is arranged in fluid communication with the airflow channel when the first constriction element is removably attached to an upstream end of the aerosol-generating device, wherein the RTD of the first constriction element is higher than the RTD of the rest of the airflow channel, wherein an inner diameter of the constricted airflow passage is smaller than an inner diameter of the rest of the airflow channel, and wherein the first constriction element comprises a protective grill with multiple fluid permeable holes; and a second constriction element, wherein the second constriction element comprises a constricted airflow passage, wherein the second constriction element is configured with a predetermined resistance to draw (RTD), wherein the constricted airflow passage is arranged in fluid communication with the airflow channel when the second constriction element is removably attached to the upstream end of the aerosol-generating device, wherein the RTD of the second constriction element is higher than the RTD of the rest of the airflow channel, wherein an inner diameter of the constricted airflow passage is smaller than an inner diameter of the rest of the airflow channel, and wherein the second constriction element comprises a protective grill with multiple fluid permeable holes, wherein the first and second constriction elements are configured removably attachable to the upstream end of the aerosol-generating device, and wherein the RTD of the first constriction element is different from the RTD of the second constriction element.

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