Aerosol generation device with cold plasma cleaning

Abstract

This disclosure relates to an aerosol generating apparatus having a cleaning unit for a heating element, a method for cleaning the heating element of the aerosol generating apparatus, and a method for manufacturing the aerosol generating apparatus. The aerosol generating apparatus includes a heating element and a cleaning unit. The heating element is configured to heat an aerosol generating article to generate an aerosol. The cleaning unit is arranged to cooperate with the heating element for cleaning the surface of the heating element. The cleaning unit includes at least one piezoelectric element. The piezoelectric element is configured to generate cold plasma for cleaning the surface of the heating element.

Description

Technical Field

[0001] This disclosure relates to an aerosol generating apparatus for consumer smoking articles. The aerosol generating apparatus includes a cleaning unit for a heating element. This disclosure further relates to a method for cleaning the heating element of the aerosol generating apparatus and a method for manufacturing such an aerosol generating apparatus. Background Technology

[0002] Smoking articles in which the aerosol-forming matrix (such as a tobacco-containing matrix) is heated without combustion are known in the art. The purpose of such heated smoking articles is to reduce known harmful smoke components produced by the combustion and thermal degradation of tobacco in conventional cigarettes. Typically, in such heated smoking articles, an aerosol is generated by transferring heat from a heat source to a physically separated aerosol-forming matrix or material, which may be located within, around, or downstream of the heat source. During inhalation, volatile compounds are released from the aerosol-forming matrix via heat transfer from the heat source and are entrained in the air inhaled through the smoking article. When the released compounds cool, they condense to form an aerosol inhaled by the consumer.

[0003] Typically, smoking articles used with aerosol generating devices include an aerosol forming matrix, which is usually assembled with other elements or components in the form of a strip. This strip is typically configured to the shape and size to be inserted into the aerosol generating device, which includes a heating element for heating the aerosol forming matrix.

[0004] In an aerosol generation device, aerosols are generated when an aerosol-forming matrix is ​​exposed to an active heating element. The aerosol-forming matrix is ​​composed of complex organic compounds. When this matrix generates aerosols upon heating, non-volatile organic residues from the matrix remain and accumulate on the surface of the heating element. These accumulated organic residues on the heating element can act as a thermal resistance layer over time. The formation of this thermal resistance layer affects aerosol generation, thus increasing energy requirements and consumption.

[0005] Currently, methods such as pyrolysis or other procedures, such as ultrasonic cleaning or manual cleaning like scrubbing, are used to clean heating elements. For example, pyrolysis is described in EP2797444(A1). This document discloses a method using an aerosol generating apparatus, comprising the steps of: contacting a heating element of the aerosol generating apparatus with an aerosol forming matrix; raising the temperature of the heating element to a first temperature to sufficiently heat the aerosol forming matrix to form an aerosol; removing the contact between the heating element and the aerosol forming matrix; and heating the heating element to a second temperature above the first temperature to thermally release organic material adhering to or deposited on the heating element. One embodiment of the aerosol generating apparatus includes a heating element coupled to a controller for heating the heating element to the first and second temperatures.

[0006] Some existing cleaning methods consume relatively large amounts of electricity, causing batteries in aerosol generators, for example, to deplete more quickly. Additionally, in some cases, if the battery fails, the aerosol generator must be taken to an authorized service center. These methods make the entire cleaning process expensive and time-consuming. Conversely, some users of aerosol generators attempt to clean the heating element themselves using unsuitable brushes or unauthorized chemical reagents. This can damage the heating element, rendering it unusable.

[0007] In summary, effectively removing organic residues from the heating element of an aerosol generator using existing methods requires a relatively large amount of electrical energy and is time-consuming. Summary of the Invention

[0008] Therefore, it may be necessary to provide an alternative aerosol generating device with a cleaning unit for its heating element.

[0009] The purpose of this disclosure is achieved by the subject matter of the independent claims, wherein other embodiments are incorporated in the dependent claims. It should be noted that the aspects of this disclosure described below are applicable to aerosol generating apparatus, methods for cleaning heating elements of an aerosol generating apparatus, and methods for manufacturing an aerosol generating apparatus.

[0010] According to one aspect of this disclosure, an aerosol generating apparatus is provided. The aerosol generating apparatus includes a heating element and a cleaning unit.

[0011] The heating element is configured to heat the aerosol-generating article to generate an aerosol.

[0012] The cleaning unit is arranged to cooperate with the heating element for cleaning the surface of the heating element. The cleaning unit includes at least one piezoelectric element.

[0013] The piezoelectric element is configured to generate cold plasma for cleaning the surface of the heating element.

[0014] The aerosol generating apparatus according to this disclosure can be used as an aerosol generating apparatus with an integrated cleaning device for cleaning organic residues accumulated on heating elements using cold plasma. The heating element and cleaning unit can be arranged within the aerosol generating apparatus. The aerosol generating apparatus can use a piezoelectric cleaning device to remove organic residues using cold plasma. In other words, this disclosure relates to a plasma cleaner for cleaning heating elements used in an aerosol generating apparatus. The piezoelectric element can be used to generate cold plasma for cleaning organic residues from the heating element. During cleaning, there are no consumables or aerosol generating articles in the aerosol generating apparatus.

[0015] Compared to conventional aerosol generating devices with cleaning units, the aerosol generating device of the present invention is easier to handle. Due to the use of piezoelectric elements and cold plasma, cleaning can be performed under ambient conditions. Due to the arrangement of the piezoelectric elements, the heating element can be cleaned inside the aerosol generating device. The device can be designed so that the aerosol generating device does not need to be disassembled, and battery life can be extended. The aerosol generating device, cleaning element, and heating element can be small in size and can be easily integrated into existing devices.

[0016] The lifespan of the heating element and thus the aerosol generating device can be extended and its efficiency improved. The aerosol generating device consumes less energy. Furthermore, cleaning takes less time. And, the aerosol generating device may be less expensive.

[0017] Cleaning of cleaning elements can be improved. This can be even more efficient through the "blast-off" effect and molecular decomposition of the ion wind jet. Cold plasma minimizes any adverse effects on users of heating elements or aerosol generation devices. Compared to conventional arc discharge plasma, piezoelectric elements used in aerosol generation devices do not generate high-frequency radiation, high voltage, or direct charge transfer. They operate at cryogenic temperatures. Therefore, there will be no additional safety considerations regarding their availability or commercial manufacturing.

[0018] The operation of the cleaning unit of the aerosol generation device can be understood as follows: When subjected to voltage, the piezoelectric element of the cleaning unit can react by generating mechanical oscillations, preferably high-frequency mechanical oscillations. The mechanical oscillations of the dielectric material within the piezoelectric element can generate an electric field, resulting in ionized gas or ionized gas in its vicinity. The ionized gas can form cold plasma in the form of an ion wind jet. The cold plasma generated by direct piezoelectric discharge can be maintained at 75 degrees Celsius or lower, preferably 50 degrees Celsius or lower. The generated cold plasma can have a temperature in the range of 17 to 75 degrees Celsius, or preferably 17 to 50 degrees Celsius. The cold plasma can interact with organic residues on the surface of the heating element to remove them from the heating element. The cold plasma can decompose heavy organic molecular residues into light residues and volatile organic molecules. Light organic residual chemicals (such as carbon) on the heating element can be oxidized to form (carbon) oxides and water vapor. Volatile organic molecules can evaporate from the surface of the heating element at room temperature, keeping it clean. In addition, the light organic residual chemicals can be volatile. The same applies to heavy organic molecular residues.

[0019] The term "aerosol generating device" refers to an apparatus that interacts with an aerosol-forming matrix to generate aerosols. The aerosol-forming matrix may be part of an aerosol-generating article, such as a smoking article. An aerosol generating device may include one or more components for supplying energy from a power source to the aerosol-forming matrix to generate aerosols. The aerosol generating device and all its components may be portable and mobile. It may be the size of a typical handheld device.

[0020] Heating elements can be provided in various shapes, sizes, and numbers. For example, heating elements can be shaped as needles, pins, rods, or plates that can be inserted into a smoking article to contact the aerosol-forming matrix. An aerosol-generating apparatus may include more than one heating element, and the term "heating element" as used in the following description means one or more heating elements. The aerosol-generating apparatus may also include electronic circuitry arranged to control the supply of current to the heating element to control its temperature. The aerosol-generating apparatus may also include means for sensing the temperature of the heating element.

[0021] The cleaning unit includes at least one piezoelectric element. The cleaning unit is arranged to cooperate with a heating element for cleaning the surface of the heating element. For example, the piezoelectric element may be mounted within an aerosol generating apparatus. This may be at the charging unit of the power unit for the aerosol generating apparatus, or inside the strip holder (for aerosol-generating articles), or at any other suitable location.

[0022] The piezoelectric element can be a piezoelectric transformer. The piezoelectric element can have different geometries, such as rectangular, semi-circular, and helical. The piezoelectric element is configured to generate cold plasma near the surface of the heating element. The cold plasma is configured to interact with the surface of the heating element to clean the surface. "Nearby" can be understood as the generated cold plasma contacting the surface of the heating element. Specifically, the gaseous flow of ions and free electrons forming the cold plasma contacts the surface of the heating element, and the ions and electrons bombard the surface of the heating element. Therefore, the piezoelectric element can be arranged close to, adjacent to, or near the surface of the heating element. The distance between the piezoelectric element and the surface of the heating element should be as close as possible, for example, 2 mm or less, preferably 1 mm or less, and more preferably 0.5 mm or less.

[0023] Cold plasma can be understood as a gas of ions and free electrons. Cold plasma, or non-thermal plasma, is not in thermal equilibrium and may include ions (and neutrally charged particles) at low temperatures (75 degrees Celsius or lower, preferably 50 degrees Celsius or lower, in the range of 17 to 75 degrees Celsius or 17 to 50 degrees Celsius), while electrons are hotter.

[0024] "Cleaning" can be understood as reducing, removing, releasing, and / or eliminating a certain amount of unwanted substances on the surface of a heating element. Unwanted substances can be residues generated by heating through the formation of an aerosol matrix. These can be non-volatile organic residues, and in particular, carbonaceous substances that remain and accumulate on the surface of the heating element.

[0025] Piezoelectric elements can be configured to generate cold plasma at atmospheric pressure. They can also generate cold plasma in ambient air. Therefore, aerosol generation devices are easy to handle. High-voltage systems and high voltages are not required. Furthermore, there is no need to consider their availability or manufacturing safety.

[0026] The piezoelectric element can be configured to generate cold plasma at temperatures ranging from 75 degrees Celsius or lower, preferably 50 degrees Celsius or lower. The piezoelectric element can also be configured to generate cold plasma at temperatures ranging from 17 to 75 degrees Celsius. In one example, the piezoelectric element is configured to generate cold plasma at room temperature (e.g., 17 to 25 degrees Celsius). Therefore, the aerosol generating device consumes less energy and is easier to handle compared to conventional devices. The absence of the need to supply and handle high temperatures makes it safer to use and manufacture.

[0027] Piezoelectric elements may include piezoelectric crystals. Piezoelectric elements may be made of lead zirconate titanate. Piezoelectric elements may be made of lead zirconate titanate or a mixture of lead zirconate and lead titanate (Pb(ZrxTi1-x)O3(PZT)) and barium titanate (BaTiO3(BTO)). Piezoelectric elements may have a protective ceramic layer. The protective ceramic layer allows the piezoelectric element to have a minimum shelf life of, for example, three years. These materials are very effective and remain in good working order.

[0028] The thickness of the piezoelectric element or piezoelectric crystal can range from 0.5 mm to 0.9 mm. The width of the piezoelectric element or piezoelectric crystal can range from 0.5 mm to 0.9 mm. The length of the piezoelectric element or piezoelectric crystal can range from 0.5 cm to 4 cm. These dimensions allow for a comfortable, small, lightweight, and handheld aerosol generating device.

[0029] A piezoelectric element may have a first end or region and a second end or region opposite the first end. For example, a piezoelectric element may be a cuboid with a longitudinal direction. A piezoelectric element may be a parallelepiped or a trapezoid. Each pair of adjacent faces of the piezoelectric element may meet at a right angle. Adjacent faces of the piezoelectric element may also meet at an angle other than 90 degrees. The first end may be opposite the second end relative to the longitudinal direction of the cuboid.

[0030] The cleaning unit may include at least two electrodes, with a first end of a piezoelectric element disposed between these electrodes. The electrodes may be made of copper, silver, or an alloy, etc. Such an implementation of the piezoelectric element and electrodes is very easy to construct.

[0031] The cleaning unit may include multiple piezoelectric elements and multiple electrodes. The respective first ends of the multiple piezoelectric elements may be stacked in layers and arranged between adjacent electrodes. The electrodes may be made of copper, silver, or alloys, etc. Such an implementation of multiple piezoelectric elements and electrodes can provide a more powerful yet still compact cleaning unit.

[0032] When the electric field strength reaches the surface of a piezoelectric element, cold plasma can form an ion wind jet. Direct piezoelectric discharge from the corners, edges, or tips of a piezoelectric element can occur as cold plasma, i.e., an ion wind jet. The term "ion wind jet" can be understood as ion wind, ionic wind, coronal wind, or electric wind, and is a flow of air caused by the electrostatic force associated with corona discharge generated at corners, edges, or tips subjected to a high voltage relative to the ground. The net charge on a conductor, including the localized charge distribution associated with dipoles, resides entirely on its outer surface and tends to concentrate around corners, edges, or tips rather than on a flat surface. This means that the electric field generated by the charge at corners, edges, or tips is much stronger than the electric field generated by the same charge residing on a large conductive shell. When this electric field strength exceeds the so-called corona discharge initiation voltage gradient, it ionizes the air around the corners, edges, or tips, and a small, faint jet of purple cold plasma can be seen at the conductive corners, edges, or tips in the dark. The ionization of nearby air molecules can lead to the formation of ionized air molecules with the same polarity as the charged corners, edges, or tips. Subsequently, the corners, edges, or tips can repel clouds of ions with similar charges, and the ion clouds immediately expand due to the repulsion between the ions themselves. This repulsion of ions can generate an electric "wind" emanating from the corners, edges, or tips.

[0033] The form of the ion wind jet can be controlled using different shapes of the piezoelectric element. The second end of the piezoelectric element can have a rectangular shape with at least two corners at the end to generate cold plasma as a direct discharge ion wind jet in an orthogonal plane relative to the front lines connecting the two corners of the piezoelectric element. The piezoelectric element can also have a rectangular shape with four corners on its outer edge, such that the direct discharge of the ion wind jet occurs orthogonally relative to the front of the piezoelectric element. This shape of the piezoelectric element and the ion wind jet allows for cleaning a wider area on the heating element.

[0034] The second end of the piezoelectric element may have a protrusion to generate cold plasma as a point ion wind jet in the same direction as the protrusion. The cold plasma can be generated as a point ion wind jet in a substantially orthogonal plane relative to the protrusion of the piezoelectric element. The piezoelectric element may have a sharp end or tip, which can generate multiple ion wind jets at a single point in a direction perpendicular to the tip of the piezoelectric element. This shape of the piezoelectric element and the ion wind jets allows for a very dense, clean focusing spot for the heating element.

[0035] The aerosol generating apparatus may include an electrical unit configured to power a heating element and a cleaning unit. Preferably, this electrical unit is the sole power source for the aerosol generating apparatus. In other words, there are no two separate electrical units used for the heating element and the cleaning unit. For example, the electrical unit may be or include a (rechargeable) battery. This avoids the need for a second power source, which would increase weight, size, and cost.

[0036] There are many ways to initiate cleaning. The aerosol generating device may include a user-operable button for activating the cleaning unit. To initiate cleaning, pressing the button on the aerosol generating device will activate the cleaning function of the cleaning unit. As a result, the user can determine that the heating element needs cleaning and actuate the cleaning process.

[0037] As an alternative to or supplement to the button, the aerosol generating device may include a control unit. The control unit may be a processor.

[0038] The control unit can automatically activate the cleaning unit at predetermined intervals or events. This cleaning function can, for example, activate automatically after each use, ensuring the heating element remains fully efficient and hygienic until the next use. The aerosol generating device may include a means for recording the number of smoking products consumed by the user, and the control unit can then automatically begin cleaning after a predetermined number of smoking products have been consumed. For example, the predetermined number of smoking products consumed could be two, five, or ten. The means for recording the number of smoking products consumed could be a processor that calculates, for example, the number of heating events.

[0039] Aerosol generating apparatus may include means for detecting when a heating element is removed from contact with an aerosol-forming matrix (e.g., when a smoking article is removed from the apparatus). When such an event is detected, a control unit may initiate cleaning. The means for detecting when the aerosol-forming matrix is ​​removed may be, for example, an induction coil, an aerosol-forming matrix sensor, a physical switch that can be pressed by the aerosol-forming matrix, etc.

[0040] The aerosol generating device may include means for detecting when the battery of the aerosol generating device is charging. When such an event is detected, the control unit may initiate cleaning. For example, the means for detecting when the battery of the aerosol generating device is charging may be electronic circuitry.

[0041] The control unit may be combined with one, several, or all of the above-described devices. Those skilled in the art will readily recognize how to implement these devices.

[0042] There are many instances of components that arrange aerosol generating devices.

[0043] In one embodiment, the aerosol generating apparatus may include a charging unit for receiving charging power from a power unit of the aerosol generating apparatus. The charging unit may have a strip-shaped charging compartment having a top or free end, the top or free end including an opening for inserting a strip holder for holding the aerosol-generated article or strip. The charging unit may have a bottom end opposite the top end. The bottom end may be physically connected to the aerosol generating apparatus. A cleaning unit may be arranged inside the charging unit. The cleaning unit may be arranged at the bottom end of the charging unit. This arrangement allows the aerosol generating apparatus to be very small and compact. Once the strip holder is inserted into the strip-shaped charging compartment of the charging unit, the cleaning unit, including a piezoelectric element arranged at the bottom end of the charging unit, comes into contact with the heating unit. When the strip holder is inserted into the strip-shaped charging compartment, the chamber door of the aerosol generating apparatus can be closed by moving a hinged opening toward the charging compartment. When the chamber door is closed, the aerosol generating apparatus may be configured to automatically trigger a control unit to activate the cleaning unit.

[0044] In another configuration of the aerosol generating apparatus components, a cleaning unit including a piezoelectric element may be arranged inside the strip holder holding the aerosol-generated article. Compared to the embodiments described above, a charging unit may be absent. This arrangement allows for very easy and elegant handling of the aerosol generating apparatus.

[0045] The aerosol generating device may include a retractable cleaning device, and the piezoelectric element may be a retractable piezoelectric element. The retractable cleaning device may include a micromotor for moving the retractable piezoelectric element relative to a heating element. The micromotor may move the heating element from a retracted position further away from the heating element to an extended position closer to the heating element. The micromotor may be actuated by a retraction button. The micromotor may move the heating element by means of a spindle. When the cleaning process is complete, the micromotor may lower the retractable cleaning device back to the retracted position.

[0046] According to another aspect of this disclosure, a method for cleaning a heating element of an aerosol generating apparatus is provided. The method for cleaning a heating element of an aerosol generating apparatus includes the following steps:

[0047] - Cold plasma is generated by means of piezoelectric elements, in which the cold plasma cleans the surface of the heating element.

[0048] This method is easier to handle compared to conventional methods for cleaning heating elements of aerosol generating devices. Cleaning of the heating elements can be completed inside the aerosol generating device, avoiding disassembly. The efficiency of this method for cleaning heating elements of aerosol generating devices is improved. This method consumes less energy and takes less time. Furthermore, the cleaning method may be less expensive. The cleaning results may be better.

[0049] Cleaning can be understood as the interaction with debris and the removal of debris from the surface of the heating element.

[0050] An exemplary operation of a method for cleaning a heating element may be as follows: the step of generating cold plasma includes applying a voltage to a first region of the piezoelectric element, thereby forming cold plasma for cleaning the surface of the heating element. The voltage may have an inter-peak AC voltage in the range of 5-15 Vpp. An AC potential may be applied to at least one or more electrodes. This voltage level may be fairly moderate and is therefore safe to use.

[0051] Voltage can induce mechanical oscillations in piezoelectric elements. These oscillations can be understood as, for example, deformation of microscopic dimensions in the submicron range. The mechanical oscillations of a piezoelectric element can have frequencies ranging from 10 kHz to 500 kHz. The mechanical oscillations of a piezoelectric element can depend on its dimensions.

[0052] Mechanical oscillations can propagate along the piezoelectric element, for example, from a first region of the piezoelectric element to a second region opposite the first region. The mechanical oscillations can be generated from the first region or end of the piezoelectric element and can propagate along the longitudinal direction of the piezoelectric element to the opposite second region or end. At the second region, the mechanical oscillations can generate an electric field. The second region of the piezoelectric element can then be subjected to a potential, for example, from 3 kV to 20 kV. The outer edge of the second region of the piezoelectric element can be provided in a metallized form for applications with high potentials.

[0053] An electric field can generate ionized gas. Ionized gas can form cold plasma for cleaning heating elements. In other words, when the electric field strength on the surface of a piezoelectric element exceeds a desired threshold ionization field strength, cold plasma can form as an ion wind jet. This can happen very quickly (e.g., within microseconds) when this threshold field applied to the piezoelectric element is exceeded, and these charges can form piezoelectric direct discharges from the corners and / or edges of the piezoelectric element as cold plasma (i.e., an ion wind jet). The use of ionized gas and cold plasma is safe.

[0054] To clean the surface of the heating element, cold plasma can break down organic molecules of organic residues on the surface of the heating element into lighter and / or volatile organic molecules. The lighter organic residues can be oxidized to form (carbon) oxides and water vapor. The (carbon) oxides, water vapor, and / or volatile organic molecules can evaporate from the heating element at room temperature. This cleaning method can be very effective and efficient.

[0055] Cold plasma can be generated at atmospheric pressure. The ability to generate cold plasma at atmospheric pressure makes aerosol generation devices easy to handle and eliminates any safety concerns regarding their usability or manufacture.

[0056] Cold plasma can be generated at temperatures in the range of 75 degrees Celsius or lower, preferably 50 degrees Celsius or lower. Cold plasma can also be generated at temperatures in the range of 17 to 75 degrees Celsius. Furthermore, cold plasma can be generated at room temperature (e.g., 17 to 25 degrees Celsius). This cryogenic temperature allows for low energy consumption and easy handling without any safety concerns.

[0057] A method for cleaning the heating element of an aerosol generating device may include actuating a user-operable button on the aerosol generating device to initiate a cleaning unit. In this way, the cleaning step can be manually actuated by the user. For example, the user may decide that the heating element needs cleaning and actuate the cleaning. Pressing the button on the aerosol generating device may affect the actuation. Preferably, the cleaning automatically terminates after a predetermined or pre-programmed time period.

[0058] A method for cleaning the heating element of an aerosol generating device may include the step of automatically activating a cleaning unit at predetermined intervals by means of a control unit. The control unit may be a processor. This cleaning function ensures that the heating element remains fully efficient and hygienic.

[0059] According to another aspect of this disclosure, a method for manufacturing an aerosol generating apparatus is provided. The method for manufacturing the aerosol generating apparatus includes the following steps, not necessarily in this order:

[0060] - Provides heating elements for heating aerosol-generating articles to generate aerosols.

[0061] - Provide a cleaning unit, the cleaning unit including at least one piezoelectric element configured to generate cold plasma for cleaning the surface of a heating element, and

[0062] - The cleaning unit is arranged to allow it to cooperate with the heating element for cleaning the surface of the heating element.

[0063] This method for manufacturing aerosol generating devices is easy. Manufacturing can be carried out quickly without much expense and / or is not easily affected by defects.

[0064] This manufacturing method allows for the production of aerosol generating devices with an integrated cleaning unit, which are easier to handle. Cleaning of the heating element can be performed inside the aerosol generating device. Cleaning can be performed under ambient conditions. Disassembly of the aerosol generating device may not be necessary.

[0065] Aerosol generating devices consume less energy. Furthermore, cleaning takes less time. Cleaning components can be cleaned more effectively.

[0066] As used herein, the term "aerosol generating apparatus" refers to a device that interacts with an aerosol forming matrix to generate aerosols. The aerosol forming matrix may be part of an aerosol generating article, such as a smoking article. An aerosol generating apparatus may include one or more components for supplying energy from a power source to the aerosol forming matrix to generate aerosols.

[0067] An aerosol generating apparatus can be described as a heated aerosol generating apparatus, which includes a heater or heating element. The heater is preferably used to heat the aerosol-forming matrix of the aerosol generating article to generate an aerosol.

[0068] Aerosol generating devices can be electrically heated aerosol generating devices, which include a heater that is electrically operated to heat the aerosol-forming matrix of the aerosol generating product to generate aerosols. Aerosol generating devices can also be gas-fired heated aerosol generating devices. Finally, aerosol generating devices can be smoking devices that interact with the aerosol-forming matrix of the aerosol generating product to generate aerosols that can be directly inhaled into the user's lungs through the user's mouth.

[0069] As used herein, the term "aerosol forming matrix" refers to a matrix capable of releasing volatile compounds that can form aerosols. Such volatile compounds can be released by heating the aerosol forming matrix. The aerosol forming matrix can be adsorbed, coated, impregnated, or otherwise loaded onto a carrier or support. The aerosol forming matrix may suitably be part of an aerosol-generating article or a smoking article.

[0070] The aerosol forming matrix can be solid or liquid and may include nicotine. The aerosol forming matrix may include tobacco, for example, a tobacco-containing material containing volatile tobacco flavor compounds that are released from the aerosol forming matrix upon heating. In a preferred embodiment, the aerosol forming matrix may include homogeneous tobacco material, such as cast tobacco leaves.

[0071] As used herein, the terms "aerosol-generating article" and "smoking article" refer to articles comprising an aerosol-forming matrix capable of releasing volatile compounds that can form aerosols. For example, an aerosol-generating article can be a smoking article that generates aerosols that can be inhaled directly into a user's lungs through their mouth. Aerosol-generating articles can be disposable.

[0072] Optionally, the aerosol-generating article is a heated aerosol-generating article, which includes an aerosol-forming matrix intended to be heated rather than burned to release volatile compounds that can form aerosols. The smoke generated by heating the aerosol-forming matrix may contain fewer known harmful components than the known harmful components produced by combustion or thermal degradation of the aerosol-forming matrix. The aerosol-generating article may be or may include tobacco sticks.

[0073] The aerosol forming matrix may be a solid aerosol forming matrix. Alternatively, the aerosol forming matrix may include both solid and liquid components. The aerosol forming matrix may include tobacco-containing materials containing volatile tobacco flavor compounds that are released from the matrix upon heating. Alternatively, the aerosol forming matrix may include non-tobacco materials. The aerosol forming matrix may include aerosol forming agents. Examples of suitable aerosol forming agents are glycerol and propylene glycol.

[0074] If the aerosol forming matrix is ​​a solid aerosol forming matrix, then the solid aerosol forming matrix may include, for example, one or more of the following: powder, granules, pellets, fragments, strips, strips, or sheets containing one or more of herbaceous leaves, tobacco leaves, tobacco ribs, reconstituted tobacco, processed tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco. The solid aerosol forming matrix may be in loose form or may be provided in a suitable container or tube. For example, the aerosol forming material of the matrix may be contained within paper or packaging and may be in strip form. In the case where the aerosol forming matrix is ​​in strip form, the entire strip, including any packaging paper, is considered the aerosol forming matrix.

[0075] Optionally, the solid aerosol forming matrix may contain additional tobacco or non-tobacco volatile flavor compounds that are released upon heating of the matrix. The solid aerosol forming matrix may also contain capsules, which may include, for example, additional tobacco or non-tobacco volatile flavor compounds, and such capsules may melt during heating of the solid aerosol forming matrix.

[0076] Optionally, the solid aerosol forming matrix can be disposed on or embedded in a heat-stabilized carrier. The carrier can be in the form of powder, granules, microspheres, fragments, strips, ribbons, or sheets. The solid aerosol forming matrix can be deposited on the surface of the carrier in the form of, for example, sheets, foams, gels, or slurries. The solid aerosol forming matrix can be deposited on the entire surface of the carrier, or alternatively, it can be deposited in a pattern to provide uneven fragrance delivery during use.

[0077] Optionally, the aerosol-forming matrix is ​​incorporated into a smoking article, such as a cigarette. The smoking article is preferably of a suitable size and shape to engage with an aerosol-generating device so that the aerosol-forming matrix contacts the heating element of the device. For example, the smoking article may have an overall length between about 30 mm and about 100 mm. The smoking article may have an outer diameter between about 5 mm and about 12 mm.

[0078] Those skilled in the art will readily recognize which organic residues may be deposited on the heating element after using at least one of the above-described aerosol forming matrices.

[0079] The following provides a non-exhaustive list of non-limiting examples. Any one or more features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0080] A. An aerosol generating apparatus, comprising:

[0081] - A heating element configured to heat the aerosol-generating article in use to generate an aerosol, and

[0082] - A cleaning unit, arranged to cooperate with the heating element for cleaning the surface of the heating element during use.

[0083] The cleaning unit includes at least one piezoelectric element, and the piezoelectric element is configured to generate cold plasma for cleaning the surface of the heating element.

[0084] B. The aerosol generating apparatus according to Example A, wherein the piezoelectric element is configured to generate cold plasma at atmospheric pressure.

[0085] C. The aerosol generating apparatus according to Example A, wherein the piezoelectric element is configured to generate the cold plasma at a temperature ranging from 17 to 75 degrees Celsius.

[0086] D. The aerosol generating apparatus according to Example A, wherein the piezoelectric element has a first end, wherein the cleaning unit includes at least two electrodes, and wherein the first end of the piezoelectric element is disposed between these electrodes.

[0087] E. An aerosol generating apparatus according to Example A, wherein the piezoelectric element has a second end with a protrusion to generate the cold plasma as a point ion wind jet in a substantially orthogonal plane relative to the protrusion of the piezoelectric element.

[0088] F. An aerosol generating apparatus according to Example A, wherein the piezoelectric element has a second end with a rectangular shape having at least two corners at the end to generate the cold plasma as a direct discharge ion wind jet in an orthogonal plane relative to the front lines connecting the two corners of the piezoelectric element.

[0089] G. The aerosol generating apparatus according to Example A further includes a charging unit for receiving charging power from the power unit of the aerosol generating apparatus during use, wherein the charging unit has a top end with an opening for inserting an aerosol generating article and a bottom end opposite the top end, wherein the cleaning unit is disposed inside the charging unit and at the bottom end of the charging unit.

[0090] H. The aerosol generating apparatus according to Example A further includes a holding unit for receiving the aerosol-generated article, wherein the piezoelectric element is arranged inside the holding unit.

[0091] I. The aerosol generating apparatus according to Example A, wherein the cleaning unit includes a plurality of piezoelectric elements and a plurality of electrodes, wherein the respective ends of the plurality of piezoelectric elements are arranged in a layered stacked arrangement between adjacent electrodes.

[0092] J. The aerosol generating apparatus according to Example A further includes an electrical unit configured to supply power to the heating element and the cleaning unit, wherein the electrical unit is the sole power source for the aerosol generating apparatus.

[0093] K. An aerosol generating apparatus according to Example A, wherein the piezoelectric element is composed of lead zirconate titanate or a mixture of lead zirconate and lead titanate and barium titanate.

[0094] L. An aerosol generating apparatus according to Example A, wherein the piezoelectric element comprises a piezoelectric crystal having a thickness and / or width and / or length ranging from 0.5 mm to 0.9 mm.

[0095] M. A method for cleaning a heating element of an aerosol generating apparatus, the method comprising the following steps:

[0096] - Cold plasma is generated by means of piezoelectric elements, in which the cold plasma cleans the surface of the heating element.

[0097] N. The cleaning method according to Example M, wherein the step of generating cold plasma includes the following steps:

[0098] - Apply voltage to the piezoelectric element, and

[0099] - This generates the cold plasma for cleaning the surface of the heating element.

[0100] O. According to the cleaning method of Example M, the voltage has an inter-peak AC voltage in the range of 5-15Vpp.

[0101] P. According to the cleaning method of Example M, a voltage causes the piezoelectric element to mechanically oscillate at frequencies ranging from 10 kHz to 500 kHz. According to a cleaning method of one of Examples P, the mechanical oscillation propagates along the piezoelectric element and generates an electric field having a potential ranging from 3 kV to 20 kV.

[0102] Q. A cleaning method according to example Q, wherein an electric field causes the gas to ionize.

[0103] R. A method for cleaning according to Example R, wherein the ionized gas forms a cold plasma for cleaning the heating element.

[0104] S. A method for cleaning according to Example M, wherein, in order to clean the surface of the heating element, the cold plasma decomposes organic molecules of organic residues on the surface of the heating element into lighter organic residues and / or volatile organic molecules, wherein the lighter organic residues are oxidized to form carbon oxides and water vapor, and wherein the carbon oxides, the water vapor and / or the volatile organic molecules evaporate from the heating element at room temperature.

[0105] T. The method for cleaning according to Example M, wherein the cold plasma is generated at atmospheric pressure.

[0106] U. According to the cleaning method of Example M, the cold plasma is generated at a temperature in the range of 17 to 75 degrees Celsius.

[0107] V. A method for manufacturing an aerosol generating apparatus, the method comprising the following steps:

[0108] - Provides heating elements for heating aerosol-generating articles to generate aerosols.

[0109] - Provide a cleaning unit, the cleaning unit including at least one piezoelectric element configured to generate cold plasma for cleaning the surface of a heating element, and

[0110] - The cleaning unit is arranged to allow it to cooperate with the heating element for cleaning the surface of the heating element.

[0111] W. The method of manufacturing according to Example W further includes the step of providing a user-operable button on the aerosol generating device, the user-operable button being configured to activate the cleaning unit.

[0112] X. The method for manufacturing according to Example W further includes the step of providing a control unit configured to activate the cleaning unit at predetermined intervals. Attached Figure Description

[0113] Several examples will now be described further with reference to the accompanying drawings, in which:

[0114] Figure 1 An embodiment of the aerosol generating apparatus according to the present disclosure is illustrated schematically and by way of example;

[0115] Figures 2a to 2e Embodiments of piezoelectric elements according to the present disclosure are illustrated schematically and by way of example;

[0116] Figures 3a to 3c An embodiment of the aerosol generating apparatus according to the present disclosure is illustrated schematically and by way of example;

[0117] Figures 4a to 4c Another embodiment of the aerosol generating apparatus according to the present disclosure is illustrated schematically and by way of example;

[0118] Figures 5a to 5d An embodiment of the retractable cleaning device according to the present disclosure is illustrated schematically and by way of example;

[0119] Figure 6 A method for cleaning the heating element of an aerosol generating apparatus according to the present disclosure is illustrated schematically and by example; and

[0120] Figure 7 A method for manufacturing an aerosol generating apparatus according to the present disclosure is illustrated schematically and by way of example, comprising a heating element for heating an aerosol generating matrix and a cleaning unit for cleaning the surface of the heating element. Detailed Implementation

[0121] Figure 1 An aerosol generating apparatus 100 according to the present disclosure is shown, which interacts with an aerosol forming matrix 20 to generate an aerosol. The aerosol generating apparatus 100 includes a heating element 250. The heating element 250 heats the aerosol generating article to generate an aerosol. The heating element 250 is substantially sheet-like. The heating element 250 has a length, width, and thickness, the length of which extends along the longitudinal axis of the aerosol forming matrix 20 to which the heating element 250 is engaged in use. The width is greater than the thickness. The heating element 250 terminates at points or peaks to penetrate the aerosol forming matrix 20. The heating element 250 includes an electrically insulating matrix that defines the shape of the heating element 250. The electrically insulating material may be, for example, alumina (Al₂O₃) or stabilized zirconia (ZrO₂).

[0122] The aerosol generating apparatus 100 includes a heating element 250 and a cleaning unit 400 (shown in FIG. 2). The heating element 250 and the cleaning unit 400 are arranged within and integrated therein. The cleaning unit 400 is arranged close to or near the heating element 250 to cooperate with the heating element 250 for cleaning the surface of the heating element 250.

[0123] like Figure 2a As shown, the cleaning unit 400 is a plasma cleaner for cleaning the heating element 250. The cleaning unit 400 includes one or more piezoelectric elements 410. The piezoelectric element 410 is a cuboid with a longitudinal direction. It has a first end or region 412 and a second end or region 413 opposite to the first end 412 in the longitudinal direction of the cuboid.

[0124] The piezoelectric element 410 generates cold plasma near the surface of the heating element 250. The cold plasma interacts with the surface of the heating element 250 to clean the surface and remove or reduce organic residues accumulated on the heating element 250.

[0125] More specifically: The piezoelectric element 410 is subjected to a voltage at its first end 412, preferably having an input voltage of, for example, 5 to 15 Vpp. The piezoelectric element 410 responds by generating mechanical oscillations. The mechanical oscillations preferably have a frequency in the range of 10 kHz to 500 kHz. The mechanical oscillations propagate to the second end 413 of the piezoelectric element 410. There, the mechanical oscillations generate an electric field. The electric field has an output power higher than the input power at the first end 412. Preferably, the electric field has a potential of, for example, from 3 kVpp to 20 kVpp. The electric field causes ionization of the gas in the vicinity of the piezoelectric element 410.

[0126] The ionized gas forms a cold plasma in or near the piezoelectric element 410, and thus also near the surface of the heating element 250. "In or near" means that the generated cold plasma contacts the surface of the heating element 250. The cold plasma comprises ions and neutrally charged particles (molecules and atoms) and hotter electrons at low temperatures (17 to 75 degrees Celsius). The piezoelectric element 410 generates the cold plasma at atmospheric pressure, in ambient air, and at an overall temperature ranging from 17 to 75 degrees Celsius.

[0127] The cold plasma interacts with unwanted residues on the surface of the heating element 250 to remove them from the heating element 250. The unwanted residues are generated by heating the aerosol-forming matrix 20. They may be non-volatile organic residues, and specifically, carbonaceous material that remains and accumulates on the surface of the heating element.

[0128] Cold plasma can break down heavy organic molecular residues into lighter residues. The lighter residues can be volatile organic molecules. Additionally, the heavy organic molecules can also be volatile. The volatile organic molecules evaporate from the heating element surface, keeping it in a relatively clean state. Light organic residual chemicals on the heating element 250 can be oxidized to form oxides and water vapor. As a result, cold plasma cleans the heating element 250 by reducing, removing, releasing, and / or eliminating unwanted substances on its surface.

[0129] like Figure 2a As shown, the piezoelectric element 410 is a cuboid with a longitudinal direction. It includes a first end or region 412 and a second end or region 413 opposite to the first end 412 in the longitudinal direction of the cuboid.

[0130] like Figure 2b As shown, the cleaning unit 400 includes two electrodes 411, and a first end 412 of the piezoelectric element 410 is disposed between these electrodes 411.

[0131] like Figure 2c As shown, the cleaning unit 400 includes a plurality of piezoelectric elements 410 and a plurality of electrodes 411. The plurality of electrodes 411 may be a plurality of co-fired electrodes 411. The respective first ends 412 of the plurality of piezoelectric elements 410 are arranged in a layered stacked manner between adjacent electrodes 411.

[0132] Cold plasma is formed when a predetermined electric field strength is reached on the surface of the piezoelectric element 410. Direct piezoelectric discharge from the corners and edges of the piezoelectric element 410 generates cold plasma as an ion wind jet. As shown below, the form of the ion wind jet can be controlled using different shapes of the piezoelectric element 410.

[0133] like Figure 2d As shown, the second end 413 of the piezoelectric element 410 has a rectangular shape with four corners in cross-section. At these corners, cold plasma is generated as multiple (four in this case) direct discharge ion wind jets in an orthogonal plane relative to the front of the piezoelectric element 410.

[0134] like Figure 2e As shown, the second end 413 of the piezoelectric element 410 may have a sharp end, protrusion or tip in cross-section, which can generate a single ion wind jet at a single point in an orthogonal plane relative to the tip of the piezoelectric element 410.

[0135] like Figure 3a As shown, the aerosol generating apparatus 100 includes a charging unit 101 for receiving charging power for a power unit (not shown). The power unit supplies power to the heating element 250 and the cleaning unit 400. The power unit may be or include a (rechargeable) battery.

[0136] The charging unit 101 has a strip holder charging compartment 110, the compartment having a top end including an opening for inserting a strip or aerosol-generating article. The charging unit 101 has a bottom end opposite the top end. Figures 3a to 3c In the embodiment shown, the cleaning unit 400 is arranged inside the charging unit 101, and particularly at the bottom end of the charging unit 101.

[0137] A cleaning unit 400 is disposed at the bottom inside the strip holder charging compartment 110. A piezoelectric element 410 is disposed at the bottom of the strip holder cavity 111 in the charging unit 101. The strip holder cavity 111 receives the strip or aerosol forming matrix such that the piezoelectric element 410 passes through the cover opening 220 of the strip holder 200. The piezoelectric element 410 is in Figure 3b It is shown in top view and side view.

[0138] like Figure 3c As shown, the piezoelectric element 410 is close to the heating element 250. The piezoelectric element 410 is charged to generate a cold plasma 450 that is directly incident on the heating element 250. The generated cold plasma 450 allows for the evaporation and oxidation of organic residues on the heating element 250.

[0139] The cleaning procedure requires the user to insert the strip holder 200 to hold the strip or aerosol-generated article inside the aerosol generating device 100. The aerosol generating device 100 receives the strip holder 200 in the strip holder charging compartment 110 of the charging unit 101 such that the piezoelectric element 410 on the cleaning unit 400 enters the strip holder 200 through the cover opening 220.

[0140] Once the strip holder 200 is in its position, the chamber door 112 of the aerosol generating device 100 is closed by moving the hinge opening toward the charging compartment. While the chamber door 112 is closed, the user presses the cleaning start button 180, which initiates cleaning of the heating element 250. Upon completion of cleaning, the strip holder 200 can be removed from the aerosol generating device 100, and the device will be ready for the next experience.

[0141] exist Figures 4a to 4c In the illustrated embodiment, A-A' and B-B' are markings for the top and cross-sectional views of the strip holder 200. The cleaning unit 400 and the piezoelectric element 410 are arranged inside the strip holder 200. The piezoelectric element 410 is arc-shaped here. The piezoelectric element 410 can be retracted using a retractable cleaning device 420.

[0142] The operation is as follows: To begin cleaning, the user can press the retraction button 430, which initiates cleaning. The cleaning function begins with the retractable cleaning device 420 moving vertically upward toward the heating element 250. Once the piezoelectric element 410 is aligned with the heating element 250, the cleaning process begins. Upon completion of the cleaning process, the retraction mechanism 420 automatically moves downward, making space available for receiving new aerosol-generated articles into the strip holder 200.

[0143] Figures 4a to 4c as well as Figures 5a to 5d The retractable cleaning device 420 is explained in more detail. To initiate the cleaning process, in... Figure 4a In the middle, pressing the retraction button 430 activates the micro motor 310. For example... Figure 4b As shown in 4d, the micromotor 310 rotates the threaded spindle 429 to move the piezoelectric element 410 upward from the lower portion 205, bringing the piezoelectric element 410 closer to the heating element 250. Once the piezoelectric element 410 and the heating element 250 are aligned as needed, cold plasma generation can be initiated. The generated cold plasma (i.e., in the form of an ion wind jet) comes into direct contact with organic residues on the heating element 250. This interaction causes the organic residues on the heating element 250 to oxidize and evaporate at room temperature.

[0144] When the cleaning process is complete, the micro motor 310 lowers the retractable cleaning device 420 below the separator 245, and the top cover 428 on the piezoelectric element 410 aligns with the separator 245 and seals the retractable cleaning device 420. The micro motor 310 then operates and automatically stops the retraction mechanism.

[0145] like Figures 4a to 4c As shown, the strip holder 200 includes a removable cover 210 with a cover opening 220 on the top, a strip holder housing 230, a cover housing 240, and a cover release button 215. The cover housing 240 includes a side opening 260, a rechargeable battery 391, electronics 282, and a heating element assembly support 255. The cover 210 and the cover release button 215 are optional. The cover release button 215 may also be located on the strip holder housing 230.

[0146] Figure 6 A method for cleaning the heating element 250 of an aerosol generating apparatus 100 is shown. The method for cleaning the heating element 250 of the aerosol generating apparatus 100 includes a step S1 of generating cold plasma by means of a piezoelectric element 410, wherein the cold plasma cleans the surface of the heating element 250.

[0147] Step S1, which generates cold plasma, includes a sub-step S11 of applying a voltage to a first region of the piezoelectric element 410 and a sub-step S12 of thereby forming cold plasma near the surface of the heating element 250. The voltage causes mechanical oscillations in the piezoelectric element 410. These mechanical oscillations propagate along the piezoelectric element 410, for example, from the first region to an opposing second region. In the second region, the mechanical oscillations generate an electric field. This electric field generates ionized gas. The ionized gas forms cold plasma for cleaning the heating element 250. The cold plasma is generated at atmospheric pressure and at a temperature ranging from 17 to 75 degrees Celsius.

[0148] Cold plasma breaks down organic molecules in organic residues on the surface of heating element 250 into lighter and / or volatile organic molecules. The lighter organic residues can be oxidized to form oxides and water vapor. The oxides, water vapor, and / or volatile organic molecules can evaporate from heating element 250 at room temperature.

[0149] Figure 7 A method is shown for manufacturing an aerosol generating apparatus 100 having a heating element 250 for heating an aerosol generating matrix and a cleaning unit 400 for cleaning the surface of the heating element 250. The method for manufacturing the aerosol generating apparatus 100 includes the following steps, not necessarily in this order:

[0150] S1. A heating element 250 is provided for heating an aerosol-generating article to generate an aerosol, and a cleaning unit 400 is provided including at least one piezoelectric element 410 configured to generate cold plasma for cleaning the surface of the heating element 250.

[0151] S2. The cleaning unit 400 is arranged to allow it to cooperate with the heating element 250 for cleaning the surface of the heating element 250.

[0152] For the purposes of this specification and the appended claims, unless otherwise stated, all figures representing quantities, quantities, percentages, etc., shall be understood to be modified by the term “about” in all cases. Furthermore, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges that may be specifically listed or not listed herein. Thus, in this context, the number A is understood as A ± 20% A. Within this context, the number A can be considered as a value within the general standard error for the measurement of the attribute modified by the number A. In some cases used in the appended claims, the number A may deviate from the percentages listed above, provided that the amount of deviation from A does not materially affect the essential and novel features of the claimed disclosure. Furthermore, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges that may be specifically listed or not listed herein.

[0153] Although illustrative examples of this disclosure have been described above in part with reference to the accompanying drawings, it should be understood that this disclosure is not limited to these examples. Variations on the disclosed examples can be understood and implemented by those skilled in the art from a study of the drawings, description, and appended claims.

[0154] In the claims, any reference marks enclosed in parentheses should not be construed as limiting the scope of the claims. The term "comprising" does not exclude the presence of elements or steps other than those listed in the claims. The words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. This disclosure can be implemented by means of hardware comprising several different elements. In an apparatus claim enumerating several means, several of these means may be embodied by the same item of hardware. The fact that certain means are enumerated in mutually different dependent claims does not imply that a combination of these means cannot be used advantageously.

Claims

1. An aerosol generating apparatus, comprising: - A heating element configured to heat the aerosol-generating article to generate an aerosol, and - A cleaning unit, arranged to cooperate with the heating element for cleaning the surface of the heating element. The cleaning unit includes at least one piezoelectric element, and the piezoelectric element is configured to generate cold plasma for cleaning the surface of the heating element. The piezoelectric element is configured to generate the cold plasma at atmospheric pressure, and The piezoelectric element is configured to generate the cold plasma at a temperature ranging from 17 to 75 degrees Celsius.

2. The aerosol generating apparatus according to claim 1, wherein the piezoelectric element has a first end, wherein the cleaning unit includes at least two electrodes, and wherein the first end of the piezoelectric element is disposed between the at least two electrodes.

3. The aerosol generating apparatus according to claim 1, wherein the piezoelectric element has a second end with a protrusion to generate the cold plasma as a point ion wind jet in an orthogonal plane relative to the protrusion of the piezoelectric element.

4. The aerosol generating apparatus according to claim 1, wherein the piezoelectric element has a second end with a rectangular shape having at least two corners at the second end to generate the cold plasma as a direct discharge ion wind jet in an orthogonal plane relative to the front lines connecting the at least two corners of the piezoelectric element.

5. The aerosol generating apparatus according to claim 1, further comprising a charging unit for receiving charging power from a power unit of the aerosol generating apparatus, wherein the charging unit has a top end with an opening for inserting an aerosol generating article and a bottom end opposite the top end, wherein the cleaning unit is disposed inside the charging unit and at the bottom end of the charging unit.

6. The aerosol generating apparatus according to claim 1, further comprising a holding unit for receiving the aerosol-generated article, wherein the piezoelectric element is disposed inside the holding unit.

7. The aerosol generating apparatus according to claim 1, wherein the cleaning unit comprises a plurality of piezoelectric elements and a plurality of electrodes, wherein the respective ends of the plurality of piezoelectric elements are arranged in a layered stacked manner between adjacent electrodes.

8. The aerosol generating apparatus of claim 1, further comprising a power unit configured to supply power to the heating element and the cleaning unit, wherein the power unit is the sole power source for the aerosol generating apparatus.

9. A method for cleaning a heating element of an aerosol generating apparatus, the method comprising the following steps: - Cold plasma is generated by means of a piezoelectric element, wherein the cold plasma cleans the surface of the heating element. The cold plasma is generated by the piezoelectric element at atmospheric pressure and at a temperature ranging from 17 to 75 degrees Celsius.

10. The method for cleaning the heating element of an aerosol generating apparatus according to claim 9, wherein the step of generating cold plasma comprises the following steps: - Apply voltage to the piezoelectric element, and - This generates the cold plasma for cleaning the surface of the heating element.

11. The method for cleaning the heating element of an aerosol generating apparatus according to claim 10, wherein the voltage has an inter-peak AC voltage in the range of 5-15 Vpp.

12. The method for cleaning the heating element of an aerosol generating apparatus according to claim 10 or claim 11, wherein the voltage causes the piezoelectric element to mechanically oscillate at a frequency in the range of 10 kHz to 500 kHz.

13. A method for manufacturing an aerosol generating apparatus, the method comprising the following steps: - Provides a heating element for heating an aerosol-generating article to generate an aerosol, and a cleaning unit including at least one piezoelectric element configured to generate cold plasma for cleaning the surface of the heating element, the piezoelectric element being configured to generate the cold plasma at atmospheric pressure and at a temperature in the range of 17 to 75 degrees Celsius. - The cleaning unit is arranged to allow it to cooperate with the heating element for cleaning the surface of the heating element.

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