AEROSOL-GENERATING DEVICE WITH COLD PLASMA CLEANING

Abstract

An aerosol-generating device is provided, including: a heating element to heat an aerosol-generating article to generate an aerosol; and a cleaning apparatus arranged to cooperate with the heating element and to clean a surface of the heating element, in which the cleaning unit includes at least one piezoelectric element, and in which the piezoelectric element is configured to generate cold plasma to clean the surface of the heating element. A method for cleaning a heating element of an aerosol-generating device, and a method for manufacturing an aerosol-generating device, are also provided.

Claims

1.-15. (canceled)

16. An aerosol-generating device, comprising: a heating element configured to heat an aerosol-generating article to generate an aerosol; and a cleaning unit arranged to cooperate with the heating element and being configured to clean a surface of the heating element, wherein the cleaning unit comprises at least one piezoelectric element, and wherein the piezoelectric element is configured to generate cold plasma to clean the surface of the heating element.

17. The aerosol-generating device according to claim 16, wherein the piezoelectric element is further configured to generate the cold plasma at atmospheric pressure.

18. The aerosol-generating device according to claim 16, wherein the piezoelectric element is further configured to generate the cold plasma at a temperature in a range of 17 degrees Celsius to 75 degrees Celsius.

19. The aerosol-generating device according to claim 16, wherein the piezoelectric element has a first end, wherein the cleaning unit further comprises at least two electrodes, and wherein the first end of the piezoelectric element is arranged between the at least two electrodes.

20. The aerosol-generating device according to claim 16, wherein the piezoelectric element has a first end, and wherein the piezoelectric element has a second end with a protrusion to generate the cold plasma as a point ionic wind jet in a substantially orthogonal plane relative to the protrusion.

21. The aerosol-generating device according to claim 16, wherein the piezoelectric element has a first end, and wherein the piezoelectric element has a second end with a rectangular shape with at least two corners at the second end to generate the cold plasma as direct discharge ionic wind jets in an orthogonal plane relative to a front line connecting the at least two corners.

22. The aerosol-generating device according to claim 16, further comprising a charging unit configured to receive charging power for a power unit of the aerosol-generating device, wherein the charging unit has a top end with an opening configured for insertion of the aerosol-generating article and a bottom end opposite to the top end, and wherein the cleaning unit is arranged inside the charging unit and at a bottom end of the charging unit.

23. The aerosol-generating device according to claim 16, further comprising a holding unit configured to receive the aerosol-generating article, wherein the piezoelectric element is arranged inside the holding unit.

24. The aerosol-generating device according to claim 16, wherein the cleaning unit further comprises a plurality of piezoelectric elements and a plurality of electrodes, and wherein respective ends of the plurality of piezoelectric elements are arranged between adjacent electrodes in a layered stack arrangement.

25. The aerosol-generating device according to claim 16, further comprising a power unit configured to supply power to the heating element and to the cleaning unit, wherein the power unit is the only power supply of the aerosol-generating device.

26. A method for cleaning a heating element of an aerosol-generating device, the method comprising the step of: generating cold plasma by means of a piezoelectric element, wherein the cold plasma cleans a surface of the heating element.

27. The method according to the claim 26, wherein the step of generating the cold plasma comprises the steps of: applying electric voltage to the piezoelectric element, and thereby forming the cold plasma for cleaning the surface of the heating element.

28. The method according to claim 27, wherein the electric voltage has a peak-to-peak AC voltage in a range of 5 Vpp to 15 Vpp.

29. The method according to claim 27, wherein the electric voltage causes a mechanical oscillation of the piezoelectric element with a frequency in a range of 10 kHz and 500 kHz.

30. A method for manufacturing an aerosol-generating device, the method comprising the steps of: providing a heating element for heating an aerosol-generating article to generate an aerosol, and a cleaning unit comprising at least one piezoelectric element, the piezoelectric element being configured to generate cold plasma for cleaning a surface of the heating element; and arranging the cleaning unit to allow a cooperation with the heating element for cleaning the surface of the heating element.

Description

[0113] Examples will now be further described with reference to the figures in which:

[0114] FIG. 1 shows schematically and exemplarily an embodiment of an aerosol-generating device according to the disclosure;

[0115] FIGS. 2a to 2e show schematically and exemplarily an embodiment of a piezoelectric element according to the disclosure;

[0116] FIGS. 3a to 3c shows schematically and exemplarily an embodiment of an aerosol-generating device according to the disclosure;

[0117] FIGS. 4a to 4c shows schematically and exemplarily another embodiment of an aerosol-generating device according to the disclosure;

[0118] FIGS. 5a to 5d shows schematically and exemplarily an embodiment of a retraction cleaning arrangement according to the disclosure;

[0119] FIG. 6 shows schematically and exemplarily a method for cleaning a heating element of an aerosol-generating device according to the disclosure; and

[0120] FIG. 7 shows schematically and exemplarily a method for manufacturing an aerosol-generating device with a heating element to heat an aerosol-generating substrate and a cleaning unit to clean a surface of the heating element according to the disclosure.

[0121] FIG. 1 shows an aerosol-generating device 100 according to the disclosure, which interacts with an aerosol-forming substrate 20 to generate an aerosol. The aerosol-generating device 100 comprises a heating element 250. The heating element 250 heats an aerosol-generating article to generate an aerosol. The heating element 250 is here substantially blade-shaped. The heating element 250 has a length that in use extends along a longitudinal axis of the aerosol-forming substrate 20 engaged with the heating element 250, a width and a thickness. The width is greater than the thickness. The heating element 250 terminates in a point or spike for penetrating the aerosol-forming substrate 20. The heating element 250 comprises an electrically insulating substrate, which defines the shape of the heating element 250. The electrically insulating material may be, for example, alumina (Al.sub.2O.sub.3), stabilized zirconia (ZrO.sub.2).

[0122] The aerosol-generating device 100 comprises the heating element 250 and a cleaning unit 400 (shown in FIGS. 2). The heating element 250 and the cleaning unit 400 are arranged within and integrated into the aerosol-generating device 100. The cleaning unit 400 is arranged close or next to the heating element 250 to cooperate with the heating element 250 for cleaning a surface of the heating element 250.

[0123] As shown in FIG. 2a, the cleaning unit 400 is a plasma cleaner for cleaning the heating element 250. The cleaning unit 400 comprises one or more piezoelectric element(s) 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 with respect to the longitudinal direction of the cuboid.

[0124] The piezoelectric element 410 generates cold plasma in a vicinity of the surface of the heating element 250. The cold plasma interacts with the surface of the heating element 250 for cleaning the surface to remove or reduce accumulated organic residues on the heating element 250.

[0125] In more detail: The piezoelectric element 410 is subjected at its first end 412 to an electric voltage, preferably with an input voltage of e.g. 5 to 15 Vpp. The piezoelectric element 410 reacts by generating mechanical oscillation. The mechanical oscillation preferably has a frequency in a range of 10 kHz and 500 kHz. The mechanical oscillation propagates to the second end 413 of the piezoelectric element 410. There, the mechanical oscillation creates an electric field. The electric field has a higher output power compared to the input power at the first end 412. Preferably, the electric field has an electric potential from e.g. 3 kVpp to 20 kVpp. The electric field leads to ionized gas in the spatial vicinity of the piezoelectric element 410.

[0126] The ionized gas forms cold plasma in the vicinity or proximity of the piezoelectric element 410 and thereby also in the vicinity of the surface of the heating element 250. In a vicinity means that the generated cold plasma touches the surface of the heating element 250. Cold plasma comprises ions and neutrally charged particles (molecule and atoms) at a low temperature (17 to 75 degree Celsius) and hotter electrons. The piezoelectric element 410 generates the cold plasma at atmospheric pressure, in ambient air and at an overall temperature in a range of 17 to 75 degree Celsius.

[0127] The cold plasma interacts with unwanted residues on the surface of the heating element 250 for cleaning them from the heating element 250. The unwanted residues were generated by the heating of the aerosol-forming substrate 20. They might be non-volatile organic residues and in particular carbon species that remain and accumulate on the heating element surface.

[0128] The cold plasma can break down heavy organic molecule residuals to light residuals. The light residuals may be volatilizable organic molecules. Also the heavy organic molecules may be volatilizable. The volatilizable organic molecules evaporate from the heating element surface leaving it in a cleaner state. The light organic residual chemical species on the heating element 250 can oxidize to form oxides and water vapour. As a result, the cold plasma cleans the heating element 250 by reducing, removing, liberating and/or eliminating the unwanted species on the surface of the heating element 250.

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

[0130] As shown in FIG. 2b, the cleaning unit 400 comprises two electrodes 411 and the first end 412 of the piezoelectric element 410 is arranged between these electrodes 411.

[0131] As shown in FIG. 2c, the cleaning unit 400 comprises a plurality of piezoelectric elements 410 and a plurality of electrodes 411. The plurality of electrodes 411 can be multiple co-fired electrodes 411. Respective first ends 412 of the plurality of piezoelectric elements 410 are arranged between adjacent electrodes 411 in a layered stack arrangement.

[0132] The cold plasma is formed when a predetermined electrical field strength on the surface of the piezoelectric element 410 is reached. Piezoelectric direct discharge from corners and edges of the piezoelectric element 410 occur as cold plasma in form of ionic wind jets. As shown in the following, the form of the ionic wind jets can be controlled using the different shapes of the piezoelectric element 410.

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

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

[0135] As shown in FIG. 3a, the aerosol-generating device 100 comprises 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 to the cleaning unit 400. The power unit may be or comprise a (rechargeable) battery.

[0136] The charging unit 101 has a stick holder charging compartment 110 with a top end comprising an opening for inserting a stick or aerosol-generating article. The charging unit 101 has a bottom end opposite to the top end. In the embodiment shown in FIGS. 3a to 3c, the cleaning unit 400 is arranged inside the charging unit 101 and in particular at the bottom end of the charging unit 101.

[0137] The cleaning unit 400 is arranged at the bottom inside the stick holder charging compartment 110. The piezoelectric element 410 is arranged at the bottom of a stick holder cavity 111 in the charging unit 101. The stick holder cavity 111 accepts the stick or aerosol-forming substrate in a way such that the piezoelectric element 410 passes through a cap opening 220 of a stick holder 200. The piezoelectric element 410 is shown in FIG. 3b in a top view and in a side view.

[0138] As shown in FIG. 3c, the piezoelectric element 410 is close to the heating element 250. The piezoelectric element 410 gets charged to generate cold plasma 450 directly in incidence to the heating element 250. The generated cold plasma 450 allows volatilizing and oxidizing organic residues on the heating element 250.

[0139] The cleaning procedure requires the user to insert the stick holder 200 for holding the stick or aerosol-generating article inside the aerosol-generating device 100. The aerosol-generating device 100 receives the stick holder 200 in the stick holder charging compartment 110 of the charging unit 101 in a manner that the piezoelectric element 410 on the cleaning unit 400 enters into the stick holder 200 through the cap opening 220.

[0140] Once the stick holder 200 is in its position, a cavity door 112 of the aerosol-generating device 100 is closed by moving a hinge opening toward the charging compartment. On closing the cavity door 112, the user presses a cleaning activation button 180, which activates the cleaning of the heating element 250. On completion of the cleaning, the stick holder 200 can be removed from the aerosol-generating device 100 and would be ready for the next experience.

[0141] In the embodiment shown in FIGS. 4a to 4c, indication A-A′ and B-B′ are markers for top and dissection view of a stick holder 200. A cleaning unit 400 and a piezoelectric element 410 are arranged inside the stick holder 200. The piezoelectric element 410 is here in an arc shape. The piezoelectric element 410 is retractable using a retracting cleaning arrangement 420.

[0142] The operation is as follows: To initiate the cleaning, the user may press a retraction button 430, which activates the cleaning. The cleaning function starts with the movement of the retraction cleaning arrangement 420 vertically upward toward a heating element 250. Once the position of the piezoelectric element 410 is in-line with the heating element 250, the cleaning process starts. On completion of the cleaning process, the retraction mechanism 420 automatically moves downward and makes space available to receive new aerosol-generating articles into the stick holder 200.

[0143] FIGS. 4a to 4c and FIGS. 5a to 5d explain the retraction cleaning arrangement 420 in more detail. For activating the cleaning process, in FIG. 4a, the retraction button 430 is pressed, which activates a micro-motor 310. As shown in FIGS. 4b to 4d, the micro-motor 310 spins a threaded spindle 429 to move the piezoelectric element 410 upwards from a lower part 205 so to bring the piezoelectric element 410 closer to the heating element 250. Once the piezoelectric element 410 and the heating element 250 are aligned as desired, the cold plasma generation may be activated. The cold plasma generated, namely in the form of ionic wind jets, comes directly in contact with organic residues on the heating element 250. This interaction results in oxidization and evaporation of organic residues on the heating element 250 at room temperature.

[0144] When the cleaning process is complete, the micro-motor 310 lowers the retracting cleaning arrangement 420 below a separator 245 and a top cladding 428 on the piezoelectric element 410 comes in line with the separator 245 and seals the retracting cleaning arrangement 420. The micro-motor 310 progresses and stops the retraction mechanism automatically.

[0145] As shown in FIGS. 4a to 4c, the stick holder 200 comprises a removable cap 210 with a cap opening 220 on top, a stick holder housing 230, a cap housing 240, and a cap releasing button 215. The cap housing 240 comprises side openings 260, a rechargeable battery 391, electronics 282, a heating element assembly support 255. The cap 210 and the cap releasing button 215 is optional. The cap releasing button 215 can also be provided on the stick holder housing 230.

[0146] FIG. 6 shows a method for cleaning a heating element 250 of an aerosol-generating device 100. The method for cleaning a heating element 250 of an aerosol-generating device 100 comprises the step S1 of generating cold plasma by means of a piezoelectric element 410, wherein the cold plasma cleans a surface of the heating element 250.

[0147] The step S1 of generating cold plasma comprises the sub step S11 of applying electric voltage to a first region of the piezoelectric element 410 and the sub step S12 of thereby forming cold plasma in a vicinity of the surface of the heating element 250. The electric voltage causes a mechanical oscillation of the piezoelectric element 410. The mechanical oscillation propagates along the piezoelectric element 410, for example from the first region to the opposite, second region. At the second region, the mechanical oscillation creates an electric field. The electric field results in ionization gas. The ionization gas forms the cold plasma for cleaning the heating element 250. The cold plasma is generated at atmospheric pressure and at a temperature in a range of 17 to 75 degree Celsius.

[0148] The cold plasma breaks down organic molecules of organic residues on the surface of the heating element 250 into lighter and/or volatilizable organic molecules. The lighter organic residuals can oxidize to form oxides and water vapour. The oxides, the water vapour and/or the volatilizable organic molecules can evaporate at room temperature from the heating element 250.

[0149] FIG. 7 shows a method for manufacturing an aerosol-generating device 100 with a heating element 250 to heat an aerosol-generating substrate and a cleaning unit 400 to clean a surface of the heating element 250. The method for manufacturing an aerosol-generating device 100 comprises the following steps, not necessarily in this order: [0150] S1. providing the heating element 250 for heating an aerosol-generating article to generate an aerosol and providing the cleaning unit 400 comprising at least one piezoelectric element 410, the piezoelectric element 410 being configured to generate cold plasma for cleaning the surface of the heating element 250, and [0151] S2. arranging the cleaning unit 400 to allow a cooperation with the heating element 250 for cleaning the surface of the heating element 250.

[0152] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term “about”. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A±20% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed disclosure. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

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

[0154] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The term “comprising” does not exclude the presence of elements or steps other than those listed in a claim. The word “a” or “an” preceding an elements does not exclude the presence of a plurality of such elements. The disclosure can be implemented by means of hardware comprising several distinct elements. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measured are recited in mutually different dependent claims does not indicate that a combination of these measure cannot be used to advantage.