Electrically Operated Aerosol Generating Device with Means for Detecting Airflow Within the Device - Patent application

Abstract

The present invention relates to an electrically operated aerosol generating device for generating an aerosol. The device includes an air path extending therethrough and configured to support airflow within the device. The device further includes a sound-generating member disposed in fluid communication with the air path and configured to generate sound when the device is in use and a user takes a puff, the sound-generating member generating sound caused by airflow passing through the sound-generating member. The device further includes a puff detector including a vibration sensor. The vibration sensor is fluidly isolated from the air path and configured to detect sound propagating from the sound-generating member to the vibration sensor. The present invention further relates to an aerosol generating system including such a device and an aerosol-generating article including an aerosol-forming substrate.

Description

[Technical field]

[0001] The present invention relates to an electrically operated aerosol generating device for generating an aerosol, in particular by releasing a substance of an aerosol-forming substrate into an air stream, the device comprising means for detecting the air stream within the device.The present invention further relates to an aerosol generating system comprising such a device and an aerosol-generating article comprising an aerosol-forming substrate. [Background technology]

[0002] Electrically operated aerosol generating devices used to generate inhalable aerosols by releasing a substance of an aerosol-forming substrate into an air stream are generally known from the prior art. For example, such devices may comprise an electric heater for heating an aerosol-forming substrate capable of releasing a volatile compound that forms an inhalable aerosol when heated. As another example, such devices may comprise an atomizer for dispersing particles or droplets of the aerosol-forming substrate into an air stream to form an inhalable aerosol.

[0003] In order to keep the user's experience as uniform as possible, the substance emission from the aerosol-forming substrate needs to be maintained at a certain level when the user takes a puff. However, the substance emission may vary during consumption, especially due to the airflow drawn through the system while the user is taking a puff. For this reason, proper puff detection is important for accurate control of the substance emission. Puff detection may be achieved, for example, by measuring the pressure drop of the airflow through the device when the user takes a puff. For this reason, many devices include a pressure sensor in direct fluid communication with the air path through the device to directly detect the airflow that indicates that the user is taking a puff. However, in such an arrangement, the sensor is directly exposed to the conditions in the air path, such as, for example, thermal and water vapor effects resulting from aerosol formation. This may adversely affect proper airflow detection, leading to poor or non-functioning puff detection.

[0004] It would therefore be desirable to provide an electrically operated aerosol generating device with a means for puff detection that utilizes the advantages of prior art solutions while mitigating their limitations. In particular, it would be desirable to have an electrically operated aerosol generating device with improved means for detecting airflow through the device, which is indicative of a user's puff. Summary of the Invention

[0005] According to the present invention, there is provided an electrically operated aerosol generating device for generating an aerosol, in particular an electrically operated aerosol generating device for generating an aerosol by releasing a substance of an aerosol-forming substrate into an air stream. The device comprises an air path extending through the device and configured to support an air flow within the device. The device further comprises a sound generating member disposed in fluid communication with the air path and configured to generate sound caused by the air flow passing through the sound generating member in use of the device when a user takes a puff. Additionally, the device comprises a puff detector including a vibration sensor. At least within the device, the vibration sensor is fluidly separated from the air path and configured to detect sound propagating from the sound generating member to the vibration sensor. Thus, detection of sound propagating from the sound generating member to the vibration sensor may enable detection of air flow through the device indicative of a user taking a puff.

[0006] In accordance with the present invention, it is recognized that airflow, and in particular changes in airflow, indicative of a user taking a puff, can be reliably detected by using the airflow to generate air vibrations (acoustic) or vibrations in at least a portion of the device that can be propagated and remotely detected by a vibration sensor. For remote detectability of the propagated vibrations, the vibration sensor may be disposed fluidly isolated from the air path within the device. Advantageously, the fluidically isolated arrangement of the vibration sensor makes airflow and puff detection less error prone and therefore more reliable. It is further recognized that the use of an acoustic generating member can act as an amplifier of airflow through the air path in that it generates vibrations that are transmitted to the remote vibration sensor.

[0007] The terms "acoustic" or "propagating vibrations" used essentially refer to mechanical acoustic waves propagating through a gas, fluid or solid medium, especially air, or through the structural components (solid material) of the aerosol generating device. The term "acoustic waves" refers to a type of energy propagation by adiabatic compression and decompression of the medium (air or solid material of the device, respectively).

[0008] The term "acoustic waves" or "sound" may relate to acoustic waves or sounds that are perceptible / audible by humans through their hearing perception, in particular hearing. Frequencies that humans can hear are typically in the range of 20 Hertz (Hz) to 20.000 Hertz (Hz). Similarly, the term "acoustic waves" or "sound" may relate to acoustic waves or sounds in a frequency range beyond the human audible frequency spectrum, in particular in a frequency range above 20.000 Hertz (Hz), or in a frequency range below 20 Hertz (Hz). Thus, the term "acoustic waves" or "sound" may also relate to ultrasound or ultrasonic sounds, or infrasonic waves or infrasonic sounds.

[0009] In general, the sound-generating member may be any mechanical member suitable for generating sound by passing an airflow through the vibration-generating member, in which case the sound-generating member may also be denoted as an airflow-driven sound-generating member.

[0010] To generate sound, the sound-generating member may include a sound-generating displacement structure configured to partially displace the airflow as it passes through the sound-generating displacement structure. As in aerophones such as pipes, whistles, and flutes, the airflow passing through the sound-generating displacement structure is divided and modified by the displacement structure such that vibrations in the airflow, i.e., adiabatic compression and decompression of the airflow, occur. Typically, the sound-generating displacement structure may include one or more edges, particularly sharp edges, that the airflow encounters as it passes through the sound-generating displacement structure.

[0011] The sound-generating displacement structure preferably includes at least one of one or more grooves, or one or more ridges, or one or more dimples, or one or more protrusions. When air passes along the one or more grooves, dimples, protrusions, or protrusions, respectively, the laminar airflow in contact with the one or more grooves, dimples, protrusions, or protrusions is converted into a turbulent airflow due to collision with the one or more grooves or protrusions, respectively. Thus, a part of the kinetic energy of the airflow, i.e., the dynamic pressure, is converted into a static pressure. When the sound-generating displacement structure includes multiple grooves or ridges, respectively, the partial displacement of the airflow generates multiple alternating high and low pressure regions in the airflow, which causes vibrations in the airflow, i.e., sounds.

[0012] In general, the frequency and amplitude of the sound depends on the shape, height or depth, and periodicity of each groove, dimple, protrusion, or ridge. Furthermore, the frequency and amplitude of the sound depends on the speed of the airflow passing along the vibration-generating displacement structure. Thus, in the case of multiple grooves, dimples, protrusions, or ridges, the shape, height, or depth of the grooves, dimples, protrusions, or ridges, and the periodicity of the grooves, dimples, protrusions, or ridges can be designed to selectively generate vibrations having a specific frequency (frequency spectrum) and amplitude.

[0013] The one or more grooves, or the one or more ridges, or the one or more grooves and the one or more ridges, may have any kind of shape suitable for partially displacing the airflow. Preferably, the one or more grooves, or the one or more ridges, or the one or more grooves and the one or more ridges may include one of a triangular shape, a curved, particularly sinusoidal, shape, or a rectangular shape. As used, the shape of each of the one or more grooves or ridges refers to the cross-sectional shape of the one or more grooves or ridges as seen in a cross section perpendicular to the length extension of each of the one or more grooves or ridges.

[0014] In general, the plurality of grooves or ridges may be evenly or unevenly distributed along the sound-generating displacement structure. Preferably, the sound-generating displacement structure includes a periodic pattern. That is, the grooves or ridges, or both grooves and ridges, are arranged in a periodic pattern with a constant distance between each pair of adjacent grooves or ridges, respectively. The periodic pattern is advantageous for generating vibrations having a specific, particularly narrowband, frequency spectrum.

[0015] Depending on the frequency of the generated sound, the periodic pattern may have a periodicity in the range of 0.5 ridges or grooves per millimeter to 10 ridges or grooves per millimeter, in particular 1 ridge or groove per millimeter to 5 ridges or grooves per millimeter, preferably 2 ridges or grooves per millimeter to 4 ridges or grooves per millimeter. That is, the periodic pattern may have a periodic length in the range of 0.1 millimeter to 2 millimeters, in particular 0.2 millimeter to 1 millimeter, preferably 0.25 millimeter to 0.5 millimeter. Thus, the generating displacement structure may include a plurality of ridges or grooves, or both a plurality of ridges and grooves, with the distance between each pair of adjacent grooves or ridges in the range of 0.1 millimeter to 2 millimeters, in particular 0.2 millimeter to 1 millimeter, preferably 0.25 millimeter to 0.5 millimeter.

[0016] For example, if the periodic pattern of the sound-generating displacement structure has a period length of 0.25 mm and the airflow speed passing the sound-generating displacement structure is 10 meters / second, sound having a frequency of approximately 40 kilohertz (kHz) may be generated.

[0017] The periodic pattern may be a linear periodic pattern. The periodic pattern may be one-dimensional, such as an array of multiple parallel grooves or ridges. That is, the pattern includes periodicity along only one direction. The periodic pattern may be multidimensional, in particular a two-dimensional pattern. That is, the pattern includes periodicity along more than one direction, in particular along two directions. For example, the pattern may include a first periodicity along a first direction and a second periodicity along a second direction. The first direction and the second direction may be transverse, in particular perpendicular to each other. As an example, the periodic pattern may include a first array of multiple parallel first grooves or first ridges with a first periodicity along a first direction and a second array of multiple parallel second grooves or second ridges with a second periodicity along a second direction. In particular, such a periodic pattern may be a cross pattern or a grid pattern.

[0018] The periodic pattern may be a non-linear periodic pattern. For example, the periodic pattern may include a plurality of curved, particularly ring-shaped grooves or a plurality of curved, particularly ring-shaped ridges. The periodic pattern may include a concentric ring pattern forming a plurality of ring-shaped grooves or a plurality of ring-shaped ridges. The ring pattern or ring shape may be circular, elliptical, oval, rectangular, square, or polygonal. A symmetrical periodic ring pattern is advantageous for the arrangement of the sound-generating displacement structure at the distal end surface of the cylindrical receiving cavity.

[0019] As another example, the periodic pattern may include a spiral pattern formed in spiral shaped grooves or ridges.

[0020] As another example, the periodic pattern may include a honeycomb pattern that includes a plurality of grooves or ridges that define the contours of the honeycomb pattern.

[0021] To enhance sound generation, at least one or more length extensions of the groove or ridges may be transverse, particularly perpendicular to the direction in which air flows past the sound generating member when the device is in use.

[0022] At least one of the height of the ridges or the depth of the grooves may vary constantly along the sound-generating displacement structure in the direction in which airflow passes the sound-generating member when the device is in use. Alternatively, at least one of the height of the ridges or the depth of the grooves may vary, in particular increase, along the sound-generating displacement structure in the direction in which airflow passes the sound-generating member when the device is in use. This may allow the sound generation to be adapted to the geometry and dimensions of the air path, for example to provide a particular resistance to draw (RTD).

[0023] The sound-generating member, and in particular the sound-generating displacement structure, is preferably part of a wall member that defines at least a portion of the air path through the device. Advantageously, this may simplify the manufacture and assembly of the device. In particular, having the sound-generating displacement structure and the wall member of the device integrated together allows for a compact design of the device. For example, the sound-generating displacement structure may include one or more grooves, or one or more ridges, or one or more grooves and one or more ridges, formed in the wall member of the device that defines at least a portion of the air path through the device.

[0024] Similarly, the sound generating member, particularly the sound generating displacement structure, may be a separate member or element separate from, and particularly attached to, a wall member which defines at least a portion of the air path through the device.

[0025] The sound-generating displacement structure is preferably a rigid structure, so that neither the sound-generating displacement structure as a whole nor any of its structural components experiences eccentricity of the center of mass, however, this does not exclude that sound may propagate through the sound-generating displacement structure.

[0026] Alternatively or in addition to the sound-generating displacement structure, the sound-generating member may include at least one airflow-driven vibrating element for periodically interrupting the airflow passing through the vibrating element. As in interrupted aerophones, and in particular in reed aerophones such as the oboe or clarinet, the airflow is directed at a flexible vibrating element, such as a lamella or a pair of lamellae, causing the vibrating element to vibrate. Due to the airflow-driven vibration of the flexible vibrating element, the airflow passing through the vibrating element is periodically interrupted, which moves the air and thereby generates sound.

[0027] Thus, the at least one vibration element may comprise a lamella, or a reed, or a pair of reeds or a pair of lamellae.

[0028] Similarly, at least one vibratory element may include a constrained movable element for periodically interrupting the airflow passing through the vibratory element. To restrict its free movement, the movable element may be disposed within a cage, such as a ball in a pea whistle. Similarly, the movable element may be constrained by coupling it to one end of a spring element, the other end of which is fixedly attached within the device.

[0029] Of course, the sound-generating member may include multiple vibration elements, e.g., multiple lamellae or reeds. Having multiple vibration elements advantageously increases the amplitude of the generated sound, which in turn facilitates sound propagation towards the vibration sensor.

[0030] As mentioned above, the amplitude and frequency / frequency spectrum of the generated sound can be influenced by the dimensions and configuration of the air path and the sound-generating member. In order to make the generated sound imperceptible by the user of the device, and in particular to avoid undesirable noise exposure, the generated sound is preferably outside the range of the human audible frequency spectrum, and even more preferably outside the range of the audible frequency spectrum of many animals, particularly pets such as dogs or cats. Thus, the air path and the sound-generating member can be configured such that the sound generated during use of the device is in a frequency range of more than 15 kilohertz (kHz), preferably more than 20 kilohertz (kHz), more preferably more than 10 ...

[0031] In order to fluidically separate the vibration sensor from the air path through the device, at least within the device, the vibration sensor may be disposed in a compartment of the device that is fluidically separated from the air path through the device. Thus, the vibration sensor is not in direct fluid communication with the air path, and in particular is not in direct contact with the fluid (air, aerosol, aerosol particles) passing through the air path. This does not exclude that the vibration sensor is in indirect fluid communication with the air path through the device, for example, via a direct fluid communication to the ambient air surrounding the device, and then in direct fluid communication with the air path through the device, for example, via an air inlet or an air outlet of the device. In this configuration, the vibration sensor is still sufficiently isolated from any fluid (air, aerosol, aerosol particles) passing through the air path.

[0032] Thus, a compartment of the device that is fluidly isolated from the air path may be in fluid communication with the device environment, in particular the ambient air surrounding the device.

[0033] Alternatively, a compartment of the device that is fluidly isolated from the air path through the device may also be fluid-sealed from the device environment, in particular the ambient air surrounding the device.

[0034] Although the vibration sensor is fluidically isolated from the air path through the device, the sound generated in the sound-generating member can easily propagate from the sound-generating member to the vibration sensor through different media. That is, the sound can propagate through the air in the device, through the ambient air surrounding the device, and through solid materials of the device, such as wall members of the device, for example wall members that define at least a portion of the air path, or wall members that separate the above-mentioned compartments from the air path. Depending on the sound propagation characteristics of the different media and depending on the physical structure and dimensions of the device, the sound can propagate directly from the sound-generating member to the vibration sensor. Alternatively or additionally, the sound may propagate from the sound-generating member to the vibration sensor through the device environment. That is, the sound can at least partially escape from the device and re-enter the device before reaching the vibration sensor.

[0035] The vibration sensor may be arranged in the device such that acoustic transmission to the vibration sensor occurs from air surrounding at least a portion of the vibration sensor. Thus, the vibration sensor may be arranged in the device such that it is at least partially surrounded by a fluid, in particular air.

[0036] Similarly, the vibration sensor may be disposed within the device such that acoustic transmission to the vibration sensor occurs from the solid material of the device component with which the vibration sensor contacts. For example, the vibration sensor may be disposed in a wall member of the device, such as a wall member of the device that fluidly separates the sensor from an air path. In particular, the vibration sensor may be disposed on a side of the wall member that faces a side of the wall member that defines at least a portion of the air path through the device.

[0037] The vibration sensor may include an electroacoustic transducer, which is a device configured to convert acoustic energy into electrical energy. Depending on the nature of the acoustic transmission to the vibration sensor, the vibration sensor may include, for example, a microphone, an accelerometer, a strain gauge, or a piezoelectric or magnetoacoustic transducer.

[0038] A piezoelectric acoustic transducer is a device that detects sound by using the piezoelectric effect to measure changes in pressure, acceleration, strain, or force caused by sound and converting the measured changes into an electrical signal. Similarly, a magneto-acoustic transducer is a device that detects sound by using electromagnetic induction to measure changes in pressure, acceleration, strain, or force caused by sound and converting the measured changes into an electrical signal.

[0039] Similarly, accelerometers or strain gauges can be used to measure the movement and vibration of structures exposed to dynamic loads caused by acoustics coupled to these types of sensors. Strain gauges are sensors whose resistance changes with applied force. They convert force, pressure, tension into measurable changes in electrical resistance. Accelerometers measure the approximate acceleration of a sensing mass, such as a membrane, in response to vibrations in air pressure or vibrations / acoustics in a solid body to which the sensing mass is mechanically coupled.

[0040] The microphone may be an electromagnetic microphone (also known as a dynamic microphone or moving coil microphone) that uses electromagnetic induction to convert acoustic energy into electrical energy. Electromagnetic microphones are robust, relatively inexpensive, and resistant to moisture. Electromagnetic microphones use the same dynamic principle as in loudspeakers, only reversed. A small movable induction coil positioned within the magnetic field of a permanent magnet is attached to a diaphragm. When sound enters the microphone, the acoustic waves move the diaphragm. As the diaphragm vibrates, the coil moves within the magnetic field, creating a varying current in the coil via electromagnetic induction. This type of microphone may also be referred to as a magneto-acoustic transducer, or may be a specific embodiment of a magneto-acoustic transducer.

[0041] The microphone may be an electrostatic microphone, such as a condenser microphone, an electret microphone, or a piezoelectric microphone, the latter also being denoted as a piezoelectric acoustic transducer or being a specific embodiment of a piezoelectric acoustic transducer, the details of which are explained below.

[0042] The microphone may be a fiber optic microphone. Fiber optic microphones convert acoustic waves into electrical signals by sensing changes in the intensity of light passing through the optical fiber. In operation, light from a laser source travels through the optical fiber and illuminates the surface of a reflective diaphragm. Acoustic vibrations of the diaphragm modulate the intensity of the light that reflects off the diaphragm in a particular direction. The modulated light is transmitted through a second optical fiber to a photodetector, which converts the intensity modulated light into an electrical signal. Fiber optic microphones have a high dynamic and frequency range. Advantageously, fiber optic microphones do not interfere with electric, magnetic, or electrostatic fields. Thus, fiber optic microphones are ideal for use in electrically operated aerosol generators, particularly in conjunction with induction heating aerosol generators.

[0043] The device may comprise a device housing including an air passage through the device. The device housing may be configured to receive an aerosol-forming substrate including a substance to be expelled into an airflow through the air passage.

[0044] In general, an aerosol generating device may comprise at least one air inlet through which air may enter an air path through the device. The air inlet may therefore be considered as the starting point of an air path through the device. Similarly, an aerosol generating device may comprise at least one air outlet through which air may exit an air path through the device. The air outlet may therefore be considered as the ending point of an air path through the device. The air outlet may, for example, be provided in a mouthpiece portion of the device.

[0045] The aerosol-generating device may comprise a receiving cavity for removably receiving at least a portion of the aerosol-forming substrate or an aerosol-generating article including a substrate.

[0046] The receiving cavity may include an insertion opening through which the aerosol-forming substrate or aerosol-generating article may be inserted into the receiving cavity. As used herein, the direction in which the aerosol-forming substrate or aerosol-generating article is inserted is indicated as the insertion direction. The insertion direction preferably corresponds to an extension of the length axis, in particular the central axis, of the receiving cavity.

[0047] After insertion into the receiving cavity, at least a portion of the aerosol-generating article may still extend outwardly through the insertion opening. The outwardly extending portion is preferably provided for interaction with a user, in particular for entry into the user's mouth. Thus, during use of the device, the insertion opening may be close to the user's mouth.

[0048] As a result, as used herein, the section that is proximate the insertion opening or proximate the user's mouth when the device is in use is generally designated with the prefix "proximal," respectively. Sections that are disposed further away are generally designated with the prefix "distal."

[0049] With this practice, the receiving cavity may be disposed or located in a proximal portion of the aerosol generating device, and the insertion opening may be disposed or located in a proximal end of the aerosol generating device, in particular in a proximal end of the receiving cavity.

[0050] The air path through the device can extend at least partially through a wall that defines at least a portion of the receiving cavity. Such a configuration is described, for example, in WO2013 / 102609A2.

[0051] Additionally or alternatively, the air path through the device may extend at least partially along the inner surface of the receiving cavity. Thus, the receiving cavity may include a plurality of protrusions extending into the interior of the receiving cavity. The plurality of protrusions are preferably spaced apart from each other such that an air path or at least a portion of an air path through the device is formed between adjacent protrusions, i.e. by a gap (free space) between adjacent protrusions. Additionally, the plurality of protrusions may be configured to contact at least a portion of the aerosol-forming substrate or aerosol-generating article to hold the substrate or article within the receiving cavity. Examples of such configurations are described in WO2018 / 050735A1.

[0052] With this configuration, the air inlet of the device is preferably realized at an insertion opening of the receiving cavity, which is used to insert the substrate or article into the cavity. When the substrate or article is received in the cavity, air may be drawn into the receiving cavity at the edge of the insertion opening and further through a portion of the air path formed between the inner surface of the receiving cavity and the outer periphery of the aerosol-forming substrate or aerosol-generating article.

[0053] Preferably, part of the air path extends through the aerosol-forming substrate or article. From there, the air path may pass directly into the user's mouth. Alternatively, the air path may extend through a mouthpiece portion of the device, with air exiting the device at an air outlet in the mouthpiece portion.

[0054] The aerosol generating device may comprise one or more end stops arranged in the receiving cavity, in particular at the distal end of the receiving cavity. The one or more end stops are preferably configured to limit the insertion depth of the aerosol-forming substrate or aerosol-generating article into the receiving cavity. In particular, the one or more end stops may be configured to prevent the aerosol-forming substrate or aerosol-generating article from abutting against a distal end face of the receiving cavity facing the insertion opening of the receiving cavity at the proximal end of the receiving cavity. The one or more end stops therefore advantageously provide a free space in the distal part of the receiving cavity, allowing free air flow between the distal end of the receiving cavity and the distal end of the aerosol-generating article when the substrate or article is received in the receiving cavity. The one or more end stops may comprise a contact surface against which the aerosol-generating article, in particular the distal end of the aerosol-generating article, may abut when the article is received within the receiving cavity.

[0055] Preferably, the aerosol generating device may comprise a plurality of separate end stops, for example three end stops disposed within the receiving cavity, particularly at the distal end of the receiving cavity.

[0056] The end stops may be arranged symmetrically about a length axis, particularly a central axis, of the receiving cavity. Preferably, the end stops are equally spaced about a length axis, particularly a central axis, of the receiving cavity. As mentioned above, this allows free air flow around the end stops and the articles received within the receiving cavity.

[0057] In general, the receiving cavity may have any suitable shape. In particular, the shape of the receiving cavity may correspond to the shape of the aerosol-forming substrate or aerosol-generating article to be received therein. Preferably, the receiving cavity may have a substantially cylindrical shape or a tapered shape, for example a substantially conical or substantially frustoconical shape.

[0058] Similarly, the receiving cavity may have any suitable cross-section as seen in a plane perpendicular to the length axis of the receiving cavity or perpendicular to the direction of insertion of the article. In particular, the cross-section of the receiving cavity may correspond to the shape of the aerosol-generating article to be received therein. The receiving cavity preferably has a substantially circular cross-section. Alternatively, the receiving cavity may have a substantially elliptical cross-section, or a substantially oval cross-section, or a substantially square cross-section, or a substantially rectangular cross-section, or a substantially triangular cross-section, or a substantially polygonal cross-section. As used herein, the above mentioned shapes and cross-sections preferably refer to the shape or cross-section of the receiving cavity without taking into account any protrusions.

[0059] The receiving cavity may be formed as a receiving cavity module, in particular as a tubular sleeve that may be inserted into the main body of the aerosol generating device. Advantageously, this allows for modular assembly of the aerosol generating device.

[0060] Alternatively, at least a portion of the receiving cavity may be integrally formed with the main body. Providing at least a portion of the receiving cavity as part of the main body may reduce the number of parts required to construct the aerosol generating device.

[0061] The acoustically generating member may be located within a distal end portion of the receiving cavity, in particular on a distal end face of the receiving cavity. The distal end face of the receiving cavity may be formed by a wall member separating the receiving cavity from other parts of the device, in particular a portion of the device comprising the vibration sensor and / or electronic components (electrical circuitry, controller, power supply). The vibration sensor is preferably disposed on a side of such wall member that faces the side of the wall member that defines the distal end face of the receiving cavity.

[0062] In addition to the vibration sensor, the smoke detector may further include an electrical circuit for converting an output signal of the vibration sensor into a signal indicative of sound. The electrical circuit may include at least one of a transimpedance amplifier for current-to-voltage conversion, an inverting signal amplifier, a single-ended to differential converter, an analog-to-digital converter, and a microcontroller.

[0063] The smoke detector or the electrical circuit may further comprise one or more electronic filters for filtering the output signal of the vibration sensor. Advantageously, the filtering may make it possible to reduce different types of noise, in particular parasitic noise, detected by the vibration sensor.

[0064] In general, aerosol generation, and in particular the release of a substance from an aerosol-forming substrate into the airflow through the device, can be achieved in different ways, as further explained above.

[0065] For example, the device may comprise an atomizer for dispersing particles or droplets of the aerosol-forming substrate into an air stream so as to form an inhalable aerosol. The atomizer may be an ultrasonic atomizer.

[0066] Alternatively, the aerosol generating device may comprise an electric heater for heating an aerosol-forming substrate capable of releasing volatile compounds which, when heated, form an inhalable aerosol and are released into the airstream.

[0067] The electric heater of the aerosol generating device may be an induction heater. The induction heater may comprise an induction source including an inductor configured to generate an alternating electromagnetic field, in particular a high frequency alternating electromagnetic field, in the device, in particular in the receiving cavity of the device mentioned above. The alternating electromagnetic field, in particular a high frequency alternating electromagnetic field, may be in the range of 500 kHz (kilohertz) to 30 MHz (megahertz), in particular 5 MHz to 15 MHz, preferably 5 MHz to 10 MHz. The alternating electromagnetic field is used to inductively heat a susceptor that is in thermal contact or in thermal proximity with the aerosol-forming substrate to be heated. The inductor may be arranged to surround at least a portion of the susceptor and the aerosol-forming substrate when the device is in use. The inductor may be an inductor coil, for example a helical coil arranged in a sidewall of the receiving cavity. For example, the inductor may be arranged to surround at least a portion of the receiving cavity.

[0068] Alternatively, the heater may be a resistive heater comprising a resistive heating element configured to heat when an electric current is passed through it due to the inherent ohmic resistance or resistive load of the resistive heating element. For example, the resistive heating element may comprise at least one of a resistive heating wire, a resistive heating track, a resistive heating grid, or a resistive heating mesh. During use of the apparatus, the resistive heating element is in thermal contact or thermal proximity with the aerosol-forming substrate to be heated.

[0069] The aerosol generating device may further comprise a controller operatively coupled to the puff detector for determining a user's puff based on signals provided by the vibration sensor, in particular based on signals provided by the puff detector indicative of airflow through an air path of the device.

[0070] The controller may further be configured to control the overall operation of the aerosol-generating device, in particular the heating process. Based on the signals indicative of the n airflows, the controller may be particularly configured to control the release of substance from the aerosol-forming substrate into the airflow. For example, if the aerosol-generating device comprises an electric heater for heating the aerosol-forming substrate, the controller may be operably coupled to the heater and configured to control the heating process to maintain the heating temperature at a particular level when the user takes a puff.

[0071] The controller and at least a portion of the smoke detector may be integral parts of the overall electrical circuitry of the aerosol generating device.

[0072] The aerosol generating device may include a power source, preferably a battery, such as a lithium iron phosphate battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a capacity that allows for storage of sufficient energy for one or more user experiences. For example, the power source may have a capacity sufficient to allow continuous generation of aerosol for about six minutes, or a multiple of six minutes. In another embodiment, the power supply may have a capacity sufficient to allow a predetermined number of puffs, or discontinuous activation of the heating device.

[0073] The present invention further relates to an aerosol generating system comprising an aerosol generating device according to the invention and as described herein, the system further comprising an aerosol-generating article comprising at least one aerosol-forming substrate heated by the device, at least a part of the article being removably receivable or removably received in the device, in particular in a receiving cavity of the device.

[0074] The aerosol-generating article may be a consumable product, in particular intended for single use. The aerosol-generating article may be a tobacco article. In particular, the article may be a rod-shaped article, preferably a cylindrical rod-shaped article that may resemble a conventional cigarette.

[0075] The article may comprise one or more of the following elements: a filter element, a cooling element, a first support element, a substrate element, and an optional second support element. Preferably, the aerosol-generating article comprises at least a first support element, a second support element, and a substrate element located between the first support element and the second support element.

[0076] All of the aforementioned elements may be disposed sequentially along the length axis of the article in the above-mentioned order, with the first support element being preferably disposed at the distal end of the article, and the filter element being preferably disposed at the proximal end of the article. Each of the aforementioned elements may be substantially cylindrical. In particular, all elements may have the same outer cross-sectional shape. In addition, the elements may be surrounded by an outer wrapper to keep the elements together and to maintain the desired cross-sectional shape of the rod-like article. The wrapper is preferably made of paper.

[0077] In the case of an inductively heated aerosol generating system, the article may further comprise a susceptor. The susceptor is positioned in thermal proximity or thermal contact with the aerosol-forming substrate such that the susceptor can be inductively heated by the inductive heating arrangement in use when the article is received in the cavity of the device. For example, the susceptor may be a susceptor strip, or a susceptor blade, or a susceptor tube, or a susceptor sleeve. The susceptor may be part of a substrate element. The term "susceptor" as used herein refers to an element that has the ability to convert electromagnetic energy into heat when subjected to an alternating magnetic field. This may be the result of hysteresis losses and / or eddy currents induced in the susceptor, depending on the electrical properties and magnetic properties of the susceptor material. Hysteresis losses occur in ferromagnetic or ferrimagnetic susceptors due to magnetic domains in the material that are switched under the influence of an alternating electromagnetic field. Eddy currents may be induced when the susceptor is conductive. In the case of electrically conductive ferromagnetic or ferrimagnetic susceptors, heat can be generated due to both eddy currents and hysteresis losses.

[0078] At least one of the first support element and the second support element may comprise a central air passage. Preferably, at least one of the first support element and the second support element may comprise a hollow cellulose acetate tube. Alternatively, the first support element may be used to cover and protect the distal forward end of the base element.

[0079] The aerosol cooling element is an element having a large surface area and low draw resistance (e.g., 15 mmWG to 20 mmWG). In use, the aerosol formed by the volatile compounds released from the base element is drawn through the aerosol cooling element before being conveyed to the proximal end of the aerosol-generating article, allowing for the formation and cooling of the aerosol.

[0080] The filter element preferably functions as a mouthpiece or as part of a mouthpiece together with an aerosol cooling element. As used herein, the term "mouthpiece" refers to the portion of the article through which the aerosol exits the aerosol-generating article.

[0081] Similarly, the aerosol-generating article may be a capsule containing an aerosol-forming powder (as the aerosol-forming substrate) that is dispersed in an air stream to generate an aerosol.

[0082] Further features and advantages of the aerosol generating system and aerosol generating article according to the invention have already been described above with reference to the aerosol generating device and apply equally.

[0083] The term "aerosol-forming substrate" as used herein relates to a substrate capable of emitting a volatile compound capable of forming an aerosol.

[0084] In particular, the aerosol-forming substrate may be a substrate capable of releasing a volatile compound capable of forming an aerosol when heated. Such an aerosol-forming substrate is intended to be heated, rather than burned, to release the aerosol-forming volatile compound. The aerosol-forming substrate may be a solid aerosol-forming substrate or a liquid aerosol-forming substrate or a gel-like aerosol-forming substrate, or any combination thereof. That is, the aerosol-forming substrate may include, for example, both solid and liquid components. The aerosol-forming substrate may include a tobacco-containing material that contains volatile tobacco flavor compounds that are released from the substrate upon heating. Alternatively, or additionally, the aerosol-forming substrate may include a non-tobacco material. The aerosol-forming substrate may further include an aerosol former. Examples of suitable aerosol formers are glycerin and propylene glycol. The aerosol-forming substrate may also include other additives and ingredients, such as nicotine or flavorings. The aerosol-forming substrate may also be a paste-like material, a sachet of porous material containing the aerosol-forming substrate, or loose tobacco mixed with, for example, a gelling or adhesive agent, which may include a common aerosol former such as glycerin, which is compressed or molded into a plug.

[0085] Similarly, the aerosol-forming substrate may be an aerosol-forming powder. The aerosol-forming powder may include nicotine powder. The term "nicotine" refers to nicotine and nicotine derivatives such as nicotine salts. Thus, the nicotine powder may be a nicotine salt or a nicotine salt hydrate. Suitable nicotine salts or nicotine salt hydrates include, for example, nicotine tartrate, nicotine aspartate, nicotine lactate, nicotine glutamate, nicotine bitartrate, nicotine salicylate, nicotine fumarate, nicotine mono-pyruvate, nicotine hydrochloride, and combinations thereof.

[0086] The nicotine powder may have any suitable particle size distribution for delivery of nicotine to the lungs of a user. In particular, at least about 90 weight percent (wt%) of the nicotine powder may have a particle size of about 10 micrometers or less, preferably about 7 micrometers or less. The nicotine powder preferably has an average diameter ranging from about 0.1 to about 10 micrometers, more preferably from about 1 to about 7 micrometers, and particularly preferably from about 2 to about 6 micrometers.

[0087] Nicotine powder particles can be surface modified, for example, nicotine salt particles can be coated.Preferred coating material is L-leucine.Particularly suitable nicotine powder particles include L-leucine coated nicotine bitartrate, L-leucine coated nicotine glutamate and L-leucine coated aspartate.

[0088] The capsule preferably contains about 5 to about 20 milligrams, especially about 10 milligrams, of nicotine powder. The capsule preferably contains sufficient nicotine powder to deliver about 10 to about 30 puffs to the user.

[0089] The nicotine powders described herein are preferably carrier-free, allowing the nicotine powder to be inhaled and delivered to the user's lungs at an inhalation or airflow rate similar to that of a typical smoking technique. Furthermore, because the nicotine powder is carrier-free, the airflow path of the inhaler can have a simple geometry or configuration.

[0090] Nevertheless, the aerosol-forming powder may further contain carrier particles which serve to increase fluidization of the active particles and improve dose uniformity by acting as a diluent or bulking agent in the formulation.

[0091] Alternatively, or in addition to the nicotine powder, the aerosol-forming powder may also include another active agent or ingredient, such as an active medical material. This active agent or ingredient may be mixed in the same capsule. The second active agent or ingredient may have a similar average diameter size range as the nicotine powder described above. EXAMPLES

[0092] The following provides 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.

[0093] Example 1: 1. An electrically operated aerosol generating device for generating an aerosol by releasing an aerosol-forming substrate material into an air stream, the device comprising: an air passage extending through the device and configured to support airflow within the device; a sound-generating member disposed in fluid communication with the air path and configured to generate sound when a user takes a puff, the sound-generating member being configured to generate sound when the device is in use by airflow passing through the sound-generating member; An electrically operated aerosol generating device comprising: a puff detector including a vibration sensor, the vibration sensor being fluidly separated from the air path and configured to detect sound propagating from the sound generating member to the vibration sensor, thereby enabling detection of airflow through the device indicative of a user's puff.

[0094] Example 2: 2. An aerosol generating device according to embodiment 1, wherein the sound-generating member comprises a sound-generating displacement structure for at least partially displacing the airflow as it passes through the sound-generating displacement structure.

[0095] Example 3: An aerosol generating device according to embodiment 2, wherein the acoustic generating displacement structure comprises at least one of one or more grooves, or one or more ridges, or one or more dimples, or one or more protrusions.

[0096] Example 4: An aerosol generating device according to Example 3, wherein the length extensions of one or more grooves, or the length extensions of one or more ridges, or the length extensions of one or more grooves and one or more ridges, are perpendicular to a transverse direction, in particular to the direction in which airflow passes through the sound-generating member when the device is in use.

[0097] Example 5: An aerosol generating device according to any one of Examples 3 or 4, wherein the one or more grooves, or the one or more ridges, or the one or more grooves and the one or more ridges, comprise one of a triangular shape, a sinusoidal shape, or a rectangular shape.

[0098] Example 6: An aerosol generating device according to any one of Examples 3 to 5, wherein at least one of the height of the ridges or the depth of the grooves varies, in particular increases, along the sound-generating displacement structure in the direction in which airflow passes through the sound-generating member when the device is in use.

[0099] Example 7: An aerosol generating device according to any one of Examples 3 to 6, wherein the plurality of grooves, ridges, dimples, or protrusions are evenly or unevenly distributed along the air passage.

[0100] Example 8: An aerosol generating device according to any one of Examples 1 to 7, wherein the sound-generating member, in particular the sound-generating displacement structure, is part of or integral with a wall member that defines at least a portion of the air path through the device.

[0101] Example 9: The aerosol generating device according to any one of Examples 2 to 8, wherein the acoustic generating displacement structure comprises a periodic pattern.

[0102] Example 10: An aerosol generating apparatus according to embodiment 9, wherein the periodic pattern has a period length in the range of 0.1 mm to 2 mm, in particular 0.2 mm to 1 mm, preferably 0.25 mm to 0.5 mm.

[0103] Example 11: An aerosol generating apparatus according to any one of Examples 8 to 10, wherein the periodic pattern is a linear periodic pattern or a non-linear periodic pattern.

[0104] Example 12: An aerosol generating device according to any one of Examples 8 to 11, wherein the periodic pattern is a one-dimensional periodic pattern, in particular an array of a plurality of parallel grooves or ridges.

[0105] Example 13: An aerosol generating device according to any one of Examples 8 to 11, wherein the periodic pattern includes a first array of multiple parallel first grooves or first ridges having a first periodicity along a first direction, and a second array of multiple parallel second grooves or second ridges having a second periodicity along a second direction.

[0106] Example 14: An aerosol generating device according to embodiment 13, wherein the first direction and the second direction are transverse directions, in particular perpendicular to each other.

[0107] Example 15: An aerosol generating device according to any one of Examples 8 to 10, wherein the periodic pattern comprises at least one of one or more curved, particularly ring-shaped grooves, or one or more curved, particularly ring-shaped ridges.

[0108] Example 16: An aerosol generating device according to any one of Examples 8 to 10, wherein the periodic pattern comprises a concentric ring pattern forming a plurality of ring-shaped grooves or a plurality of ring-shaped protuberances.

[0109] Example 17: An aerosol generating device according to any one of Examples 8 to 10, wherein the periodic pattern comprises a spiral pattern formed in the spiral-shaped grooves or ridges.

[0110] Example 18: The aerosol generating device according to any one of Examples 3 to 10, wherein the periodic pattern may include a honeycomb pattern including a plurality of grooves or ridges that form the contours of the honeycomb pattern.

[0111] Example 19: The aerosol generating device according to any one of Examples 2 to 18, wherein the sound generating displacement structure is a rigid structure.

[0112] Example 20: An aerosol generating device according to any one of the preceding embodiments, wherein the sound-generating member, in particular the sound-generating displacement structure, is a separate member or element separate from, in particular attached to, a wall member defining at least a portion of the air path through the device.

[0113] Example 21: An aerosol generating device according to any one of the previous embodiments, wherein the sound-generating member comprises at least one airflow-driven vibratory element configured to periodically interrupt the airflow passing through the vibratory element.

[0114] Example 22: 22. An aerosol generating device according to embodiment 21, wherein at least one vibration element comprises a reed, or a lamella, or a pair of reeds or a pair of lamellas.

[0115] Example 23: An aerosol generating device according to any one of the preceding embodiments, wherein the air path and the sound generating member are configured such that the sound generated when the device is in use is in a frequency range above 15 kilohertz (kHz), preferably above 20 kilohertz (kHz), and more preferably above 10 kilohertz (kHz).

[0116] Example 24: An aerosol generating device according to any one of the preceding embodiments, wherein the vibration sensor is disposed within a compartment of the device that is fluidly isolated from the air path through the device.

[0117] Example 25: An aerosol generating device according to Example 24, wherein a compartment of the device that is fluidly isolated from the air path is in fluid communication with the device environment.

[0118] Example 26: An aerosol generating device according to Example 24, wherein a compartment of the device that is fluidically separated from the air path is fluidly sealed from the device environment, in particular from the ambient air surrounding the device.

[0119] Example 27: The aerosol generating device according to any one of the preceding embodiments, wherein the vibration sensor comprises a microphone, an accelerometer, a strain gauge, or a piezoelectric transducer, or a magneto-acoustic transducer.

[0120] Example 28: An aerosol generating device according to any one of the preceding embodiments, wherein the vibration sensor is disposed on a side of the wall member opposite a side of the wall member that defines at least a portion of an air path through the device.

[0121] Example 29: An aerosol generating device according to any one of the preceding embodiments, wherein the device comprises a receiving cavity for removably receiving at least a portion of an aerosol-forming substrate or an aerosol-generating article comprising a substrate.

[0122] Example 30: An aerosol-generating device according to example 29, wherein the receiving cavity may include an insertion opening through which the aerosol-forming substrate or aerosol-generating article may be inserted into the receiving cavity.

[0123] Example 31: An aerosol generating device according to any one of Examples 29 or 30, wherein the air path extends at least partially along an inner surface of the receiving cavity and / or through a wall defining at least a portion of the receiving cavity.

[0124] Example 32: An aerosol generating device according to any one of Examples 29 to 31, wherein the acoustic generating member is located within the distal end portion of the receiving cavity, in particular on the distal end surface of the receiving cavity.

[0125] Example 33: An aerosol generating device according to any one of the preceding examples, wherein the smoke detector comprises one or more electronic filters for filtering the output signal of the vibration sensor.

[0126] Example 34: An aerosol generating device according to any one of the preceding embodiments, further comprising an atomizer for dispersing particles or droplets of the aerosol-forming substrate into an airflow so as to form an inhalable aerosol.

[0127] Example 35: An aerosol-generating apparatus according to any one of Examples 1 to 33, further comprising an electric heater for heating the aerosol-forming substrate.

[0128] Example 36: 36. An aerosol generating device according to example 35, comprising an electric heater, including an induction heater or a resistance heater.

[0129] Example 37: An aerosol generating device according to example 35, wherein the induction heater comprises an inductor, in particular an induction coil, for generating an alternating magnetic field within the device, in particular within the receiving cavity of the device.

[0130] Example 38: An aerosol generating system comprising an aerosol generating device according to any one of the embodiments and an aerosol generating article comprising an aerosol-forming substrate, at least a part of the article being removably receivable or removably received within the device, in particular within a receiving cavity of the device.

[0131] The present invention will now be further described with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0132] [Figure 1] FIG. 1 illustrates generally in cross-section a first exemplary embodiment of an aerosol generating device according to the present invention. [Diagram 2] FIG. 2 shows details of the aerosol generating device according to FIG. [Diagram 3] FIG. 3 shows further details of the sound-generating member of the aerosol generating device according to FIG. [Figure 4] FIG. 4 shows a detail of the sound-generating member of the aerosol generating device according to FIG. [Diagram 5] FIG. 5 illustrates, in cross-section, a second exemplary embodiment of an aerosol generating device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0133] 1 illustrates generally a first exemplary embodiment of an aerosol generating system 1 according to the present invention. System 1 comprises two main components: an electrically operated aerosol generating device 100 and an aerosol-generating article 190 for use with device 100. Device 100 is configured to heat an aerosol-forming substrate 191 contained within article 190. Substrate 191 has the ability to form an inhalable aerosol when heated, emitting volatile compounds which are released into an airflow passing through system 1 in use.

[0134] The aerosol generating device 100 has an elongated shape and comprises a distal portion 101 and a proximal portion 102. Within the proximal portion 102, the device 100 comprises a receiving cavity 120 formed in the device housing 110 for receiving at least a portion of an aerosol generating article 190. Within the distal portion 101, the device 100 comprises electronics, in particular a power source 150 and electrical circuitry 151 including a controller 152 for powering and controlling the operation of the aerosol generating device 100.

[0135] The article 190 has a rod shape similar to that of a conventional cigarette. In this embodiment, the article 190 comprises four elements arranged one after the other in a coaxial alignment: a substrate element 192, a support element 193, an aerosol cooling element 194, and a filter element 195. The substrate element 192 is disposed at the distal end of the article 190 and includes an aerosol-forming substrate 191 that is heated. The aerosol-forming substrate 191 may include, for example, a crimped sheet of homogenized tobacco material that includes glycerin as an aerosol former. The support element 193 includes a hollow core that forms a central air passage. The cooling element 194 has a large surface area and low drawing resistance, allowing the aerosol formed by the volatile compounds released from the substrate element 192 to be cooled before being conveyed to the proximal end of the article 190. The filter element 195 functions as a mouthpiece and may include, for example, cellulose acetate fibers for filtering the aerosol. The four elements 192, 193, 194 and 195 are substantially cylindrical in shape and have approximately the same diameter. The elements are surrounded by an outer wrapper 196 made of cigarette paper to form a cylindrical rod. The outer wrapper 196 may be wrapped around the aforementioned elements such that the free ends of the wrapper overlap one another. The wrapper may further include an adhesive that bonds the overlapping free ends of the wrapper to one another.

[0136] To heat the substrate 191 in the article 190, the aerosol generating device 100 according to the invention comprises an induction heating device. The induction heating device comprises an induction coil 140 for generating an alternating magnetic field, in particular a high-frequency magnetic field, in the receiving cavity 120. The high-frequency magnetic field may preferably be in the range of 500 kHz (kilohertz) to 30 MHz (megahertz), in particular 5 MHz (megahertz) to 15 MHz (megahertz), preferably 5 MHz (megahertz) to 10 MHz (megahertz). In this embodiment, the induction coil 140 is a helical coil disposed in the device housing 110. The coil 140 is aligned coaxially with the length axis of the receiving cavity 120 and circumferentially surrounds a portion of the cylindrical cavity 120. The alternating magnetic field is used to inductively heat a susceptor 141 disposed within an aerosol-forming substrate 191 of the article 190 such that the article 190 experiences the magnetic field generated by the induction coil 140 when received within the cavity 120. In this embodiment, the susceptor 140 is a susceptor blade disposed within a substrate element 192 along the length axis of the article 190 such that the susceptor 140 is in direct physical contact with the aerosol-forming substrate 191.

[0137] Thus, when the induction heating device is activated, a high frequency alternating current passes through the induction coil 140 and an alternating magnetic field is generated within the cavity 120. Depending on the magnetic and electrical properties of the susceptor material, the alternating magnetic field induces at least one of eddy currents or hysteresis losses within the susceptor 141. As a result, the susceptor 141 is heated to a temperature sufficient to vaporize the volatile compounds from the aerosol-forming substrate 191. The vaporized compounds are released and entrained in an airflow passing through the article 190 from the substrate element 192 at the distal end of the article 190, through the support element 193 and the cooling element 194, and toward the filter element 195. In this manner, the vaporized material cools to form an inhalable aerosol, which may then escape from the article 190 through the filter element 195 at the proximal end of the article 190.

[0138] According to the present invention, the aerosol-generating device 100 comprises an air passage 180 that provides an airflow through the system 1 into which the material of the aerosol-forming substrate can be released to form an inhalable aerosol. As shown by the curved arrow 180 in FIG. 1, the aerosol-generating article system 1 of this embodiment comprises an air passage that starts at an insertion opening 122 at the proximal end of the receiving cavity 120 that is used to insert the aerosol-generating article 190 into the cavity 120. The insertion opening 122 thus also functions as an air inlet for the device 100. The air passage 180 further extends along the inner surface of the receiving cavity 120 toward the distal end face (bottom) of the receiving cavity 120. The latter part of the air passage is formed between the inner surface of the receiving cavity 120 and the outer periphery of the aerosol-generating article 190 as it is inserted into the cavity 120. As further described above, the latter portion of the air path may be provided, for example, by a gap (free space) between protrusions (not shown) that are part of the inner surface of the receiving cavity 120 and that are used to provide a clamping retention of the article 190 within the cavity 120. At the distal end face (bottom) of the receiving cavity 120, the air path is redirected in a proximal direction, as illustrated by the curved arrow 181 in Figure 1, into the base element 192 of the aerosol-generating article 190. From there, the air path further extends through the various elements 192, 193, 194, and 195 of the article 190, as described above with respect to the aerosol-generating article 190, and finally exits the system 1.

[0139] As a result, when a user takes a puff, i.e., when negative pressure is applied to the filter element 195 of the article 190 received within the cavity 120, air is drawn into the receiving cavity 120 at the edge of the insertion opening 122 and further along the air path into the bottom portion at the distal end of the receiving cavity 120. Here, the airflow enters the aerosol-generating article 190 through the base element 192, further passes through the support element 193, the aerosol cooling element 194, and the filter element 195, and finally exits the article 190. Thus, when the induction heating device is turned on, vaporized material from the aerosol-forming substrate is entrained in the airflow through the base element 192 and is then cooled on its further path through the support element 193, the aerosol cooling element 194, and the filter element 195 to form an aerosol.

[0140] To enable proper redirection of the airflow into the aerosol-generating article 190 at the bottom of the receiving cavity 120, the aerosol generating device 100 may be provided with one or more end stops (not shown) that may be disposed within the distal end portion of the receiving cavity 130 to limit the insertion depth of the article 190 into the cavity 120 and thus prevent the article 190 from abutting the distal end face 123 of the receiving cavity 120.

[0141] As further mentioned above, proper puff detection is important to ensure accurate control of the heating process. To this end, the aerosol generating device 100 according to this embodiment is equipped with a puff detector including a vibration sensor 170 for detecting the sound generated by the airflow through the air paths 180, 181 of the device 100, which then indicates that the user is taking a puff. In this embodiment, the vibration sensor 170 is a microphone, for example a moving coil microphone. As can be seen in FIG. 1, the vibration sensor 170 is disposed outside the receiving cavity 120, fluidically isolated from the air paths 180, 181 passing through the device 100. Due to the isolated arrangement, the vibration sensor 170 is not exposed to conditions within the air paths, such as temperature and moisture. In particular, the vibration sensor 170 is isolated from airborne particles or droplets originating from the aerosol formation, and is therefore protected from any deposition. In this embodiment, as described above, the vibration sensor 170 is disposed in a compartment 125 in the distal portion 101 that also contains electronic circuitry 151, including power source 150 and controller 152. The compartment 125 is fluidly isolated from the receiving cavity 120 in the proximal portion 102 of the device 100.

[0142] To enhance the acoustic effects used to indicate the airflow through the device 100 and identify a user's puff, the aerosol generating device 100 further comprises a sound generating member 160. The sound generating member 160 is disposed in fluid communication with the air paths 180, 181 described above and configured to generate a sound resulting from the airflow passing through the sound generating member 160 when a user takes a puff. In this embodiment, the sound generating member 160 includes a sound generating displacement structure configured to at least partially displace the airflow 181 as it passes through the sound generating displacement structure.

[0143] Figures 2, 3 and 4 show details of the sound-generating displacement structure 161 implemented in the device according to Figure 1. In this embodiment, the sound-generating displacement structure 161 comprises an array of one-dimensional ridges 162 arranged in a periodic pattern at the distal end of the receiving cavity 120 (Figures 2-4 are not to scale). A groove 163 is formed between each two adjacent ridges 106. The cross-sectional shape of the ridges 162 is substantially triangular such that each ridge 162 has a sharp edge at its upper portion.

[0144] Thus, when the airflow 182 passes through the sound-generating displacement structure 161, as shown in FIG. 2, the airflow 182 is partially displaced due to collision with the ridges 162 of the displacement structure 161, causing a portion of the airflow 180 to become turbulent. Thus, a portion of the kinetic energy of the airflow, i.e., the dynamic pressure, is converted into a static pressure resulting in a plurality of alternating high pressure regions 185 and low pressure regions 186, as shown in FIG. 3. The alternating pattern of adiabatic compression and decompression in the airflow 180 causes an acoustic wave, i.e., sound, to propagate through the device 100. Originating from the sound-generating displacement member 161, the acoustic wave propagates, inter alia, through the wall member 111 that fluidly separates the receiving cavity 120 from the compartment 125. The acoustic wave further propagates through the air in the compartment 125 until it reaches the vibration sensor 170. Here, the acoustic wave (sound) is detected, thus indicating the presence of airflow through the device 100, which in turn indicates that the user is taking a puff. Thus, the sound generating displacement structure 161 is part of the wall member, i.e. the wall member 111 , that defines at least a portion of the air path through the device 100 .

[0145] In addition to the vibration sensor 170, the puff detector further comprises an electrical circuit operatively coupled to the vibration sensor 170 and configured to convert the output signal of the vibration sensor 170 into a signal indicative of the presence of airflow in the receiving cavity 120. The electrical circuit may further comprise one or more electronic filters for filtering the output signal of the vibration sensor. Advantageously, the filtering may make it possible to reduce different types of noise, in particular parasitic noise, detected by the vibration sensor 170. The electrical circuit of the puff detector may be an integral part of the electrical circuit 151, which includes the controller 152. Based on the signal indicative of the presence of airflow through the device 100, the controller 152 may adjust the control of the heating process to maintain the heating temperature of the substrate 191 in the article 190 at a certain level when the user puffs.

[0146] 4, the length 164 of the periodic pattern of the sound-generating displacement structure 161 is selected to generate sound within a particular frequency range depending on the speed of the airflow 182. For example, if the speed of the airflow 182 at the sound-generating displacement structure 161 is approximately 10 meters per second and the displacement structure 161 includes ridges 162 that occur every 0.25 millimeters, the sound will have a frequency of approximately 40 kilohertz (kHz). This frequency is outside the range of human hearing, and also outside the range of many animals, particularly pets such as dogs and cats.

[0147] FIG. 5 shows a second embodiment of the aerosol generating device 100 according to the invention. In this embodiment, the vibration sensor 270 is attached to the wall member 211 that fluidically separates the receiving cavity 220 from the compartment 225. That is, the vibration sensor 270 is arranged on a side of the wall member 211 that faces the side of the wall member 211 that defines at least a part of the air path through the device 200 and also forms or at least supports the sound-generating displacement structure 261. As a result, the vibration sensor 270 is coupled to the sound-generating displacement structure 261, i.e. close to the sound source, in particular directly to them. Advantageously, this configuration increases the detectability of the sound propagating through the device 100. Otherwise, the embodiment according to FIG. 5 is identical to the first embodiment shown in FIGS. 1-3. Accordingly, identical or similar features are indicated with the same reference numbers, but incremented by 100.

[0148] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are to be understood in all instances as being modified by the term "about." Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges thereof, which may or may not be specifically recited herein. Thus, in this context, the number A is to be understood as A±5%.

Claims

1. 1. An electrically operated aerosol generating device for generating an aerosol, said device comprising: a receiving cavity for removably receiving at least a portion of an aerosol-forming substrate or an aerosol-generating article comprising an aerosol-forming substrate; an air passage extending through the device and configured to support airflow within the device; a sound-generating member disposed in fluid communication with the air path and configured to generate sound caused by airflow passing through the sound-generating member in use of the device when a user takes a puff, the sound-generating member being located within a distal end portion of the receiving cavity; - a smoke puff detector including a vibration sensor, the vibration sensor being fluidly isolated from the air path and configured to detect the sound propagating from the sound generating member to the vibration sensor.

2. 2. The aerosol generating device of claim 1, wherein the sound generating member comprises a sound generating displacement structure for at least partially displacing the airflow as the airflow passes through the sound generating displacement structure.

3. 3. The aerosol generating device of claim 2, wherein the acoustic generating displacement structure comprises at least one of one or more grooves, or one or more ridges, one or more dimples, or one or more protrusions.

4. 4. The aerosol generating device of claim 3, wherein the length extensions of the one or more grooves, or the length extensions of the one or more ridges, or the length extensions of the one or more grooves and the length extensions of the one or more ridges, are perpendicular to the direction in which the airflow passes through the sound-generating member when the device is in use.

5. 5. The aerosol generating device of claim 3 or 4, wherein the one or more grooves, or the one or more ridges, or the one or more grooves and the one or more ridges, comprise one of a triangular shape, a sinusoidal shape, or a rectangular shape.

6. An aerosol generating device as described in any one of claims 3 to 5, wherein at least one of the height of the ridges or the depth of the grooves varies, in particular increases, along the sound-generating displacement structure in the direction in which the air flow passes through the sound-generating member when the device is in use.

7. An aerosol generating device according to any one of claims 2 to 6, wherein the acoustic generating displacement structure is part of a wall member that defines at least a portion of the air path through the device.

8. 8. An aerosol generating device according to claim 2, wherein the acoustic generating displacement structure comprises a periodic pattern.

9. 9. An aerosol generating device according to claim 8, wherein the periodic pattern has a period length in the range of 0.1 mm to 2 mm, in particular 0.2 mm to 1 mm, preferably 0.25 mm to 0.5 mm.

10. An aerosol generating device as described in any one of claims 1 to 9, wherein the sound generating member includes at least one airflow-driven vibration element configured to periodically interrupt the airflow passing through the vibration element.

11. The aerosol generating device of claim 10 , wherein the at least one vibration element comprises a reed, or a lamella, or a pair of reeds or a pair of lamellas.

12. An aerosol generating device as described in any one of claims 1 to 11, wherein the air pathway and the sound generating member are configured such that the sound generated when the device is in use is in a frequency range above 15 kilohertz, preferably above 20 kilohertz, more preferably above 40 kilohertz.

13. 13. An aerosol generating device according to any one of claims 1 to 12, wherein the vibration sensor comprises a microphone, an accelerometer, a strain gauge, or a piezoelectric transducer, or a magneto-acoustic transducer.

14. An aerosol generating device as described in any one of claims 1 to 13, wherein the vibration sensor is arranged on a side of a wall member opposite a side of the wall member that defines at least a portion of the air path through the device.

15. An aerosol generating device according to any one of claims 1 to 14, wherein the acoustic generating member is located at a distal end surface of the receiving cavity.

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