Smoking device and method for aerosol generation

Abstract

To provide a smoking device and method for aerosol generation.SOLUTION: The smoking device for aerosol generation of a liquid aerosol-forming substrate comprises a device housing 10 comprising a liquid reservoir 16 for the liquid aerosol-forming substrate. The device also comprises a surface acoustic wave atomizer (SAW-atomizer 15) comprising an atomization region 40, at least one transducer 20 for generating and propagating surface acoustic waves along a surface of the SAW-atomizer, a second transducer, and a supply element 30 arranged for bringing liquid aerosol-forming substrate from the liquid storage portion 16 to the atomization region on the SAW-atomizer. The device further comprises a control system 14 configured to operate the SAW-atomizer for atomizing the liquid aerosol-forming substrate in the atomization region to generate an aerosol. A cartridge for such a smoking device and a method for generating an aerosol in a smoking system are also provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to smoking devices, methods, and smoking systems for aerosol generation of liquid aerosol-forming substrates, and cartridges for such smoking devices. The smoking devices and aerosol-generating systems are electrically operated devices and systems. [Background technology]

[0002] In electrically operated smoking systems, for example, a liquid aerosol-forming substrate is atomized to form an aerosol. Typically, an atomizer comprises a coil of heated wire wrapped around an elongated wick immersed in the liquid aerosol-forming substrate. Other types of atomizers use ultrasonic vibrations rather than heat to atomize the liquid substrate. In these, vibrations are used to push or pull the liquid through a mesh, resulting in atomization. A problem with most atomizers that use ultrasonic vibrations is that they are unable to atomize the highly viscous liquids typically used in electrically operated smoking systems. Furthermore, many atomizers require high power to achieve a desired atomization rate. Summary of the Invention [Problem to be solved by the invention]

[0003] There is a need for a smoking device for aerosol generation of a liquid aerosol-forming substrate that ameliorates these problems.There is a need for a smoking device for aerosol generation of a liquid aerosol-forming substrate that requires less power to achieve efficient atomization. [Means for solving the problem]

[0004] According to a first aspect of the present invention, a smoking device for aerosol generation from a liquid aerosol-forming substrate is provided. The smoking device includes a device housing having a liquid storage portion with a housing for holding the liquid aerosol-forming substrate. The device housing may include a recess for receiving, for example, a cartridge, the cartridge including the liquid aerosol-forming substrate. The smoking device further includes a surface acoustic wave atomizer (SAW atomizer) including an atomization region, at least one transducer for generating surface acoustic waves that propagate along a surface of the SAW atomizer including the atomization region, and at least a second transducer. A supply element is arranged to supply the liquid aerosol-forming substrate from the liquid storage portion to the atomization region on the SAW atomizer. The supply element may fluidly connect the liquid storage portion, e.g., a cartridge, to the SAW atomizer, particularly the atomization region on the SAW atomizer. A control system is configured to operate the SAW atomizer to atomize the liquid aerosol-forming substrate in the atomization region to generate an aerosol. The control system may include, for example, a power source and control electronics connected to the SAW atomizer. The control system is adapted to provide, for example, an RF signal to the at least one transducer, and the generated aerosol may then be transported within the device housing to a downstream end of the smoking device and delivered to a user of the smoking device.

[0005] In use, a user may activate the device by operating a switch or by sucking on the device's mouthpiece. Power may be provided to the SAW atomizer, which may activate at least one transducer to generate surface acoustic waves (Rayleigh waves) that propagate along the surface of the SAW atomizer. The energy of these surface acoustic waves is transferred to a liquid aerosol-forming substrate that is provided to the atomization region. The energy provided to the liquid causes aerosol droplets to form on the liquid aerosol-forming substrate, thereby atomizing the liquid aerosol-forming substrate from the atomization region. The surface acoustic waves transferred to the liquid essentially destabilize the liquid droplets on the surface of the SAW atomizer, causing the droplets' surfaces to rupture and form a mist of aerosol droplets.

[0006] This method of generating aerosol has been proven to provide a reliable and consistent amount of aerosol from a liquid aerosol-forming substrate for a convenient smoking experience. Furthermore, aerosol generation requires less power than that generated using known vibrating elements (e.g., elements that use heat).

[0007] SAW atomizers may use commonly known SAW sensor chips. These typically include at least an interdigital (or interdigitated) transducer, which comprises (metal) electrodes disposed on a piezoelectric substrate (e.g., printed on the substrate). An AC voltage applied to the individual "fingers" of the transducer electrodes generates a mechanical deformation in the piezoelectric substrate due to alternating regions of tensile and compressive strain in the piezoelectric substrate between the fingers. Fingers on the same side of the transducer are in the same level of compression or tension, and the spacing between them (known as the pitch) corresponds to the wavelength of the mechanical wave.

[0008] The waves so generated typically have nanometer-sized amplitudes and propagate along the surface of the piezoelectric substrate at MHz frequencies.

[0009] At least one transducer of a SAW atomizer used in a smoking device according to the present invention is preferably an interdigital transducer comprising electrodes disposed on a piezoelectric substrate.

[0010] The transducer may include a reflector to favor the directionality of the generated surface acoustic waves in one direction, which may increase the power efficiency of the system.

[0011] The transducer may be configured to generate parallel waves, for example by an array of straight electrodes arranged in parallel.

[0012] The transducer may be configured to have a focusing effect on the generated waves, for example the transducer may be provided with parallel but curved electrodes, such as to concentrate the generated waves into a small zone.

[0013] The transducer preferably comprises a reflector and has a focusing effect.

[0014] The control system of the smoking device is configured to operate the SAW atomizer to generate surface acoustic waves at a predetermined frequency, which may be about 20 MHz or greater, such as between 20 MHz and about 100 MHz, or between about 20 MHz and about 80 MHz, to provide a desired aerosol output rate and droplet size for a good user experience.

[0015] The control system may include an electrical circuit connected to the SAW atomizer and a power source.

[0016] The electrical circuitry may include a microprocessor, which may be a programmable microprocessor. The electrical circuitry may include additional electronic components. The electrical circuitry may be configured to regulate power supply to the SAW atomizer. Power may be supplied to the SAW atomizer continuously after activation of the device, or may be supplied intermittently (e.g., between puffs).

[0017] The SAW atomizer can be of any suitable shape. The SAW atomizer can be substantially circular or elliptical. The SAW atomizer can be substantially triangular, or square, or any regular or irregular shape. The SAW atomizer is preferably substantially flat. The SAW atomizer can be curved. The SAW atomizer can be dome-shaped. The SAW atomizer can be a substantially square plate. The SAW atomizer can be a substantially circular or elliptical disk.

[0018] The SAW atomizer may be reusable. The SAW atomizer may be disposable. The SAW atomizer may be a separate element or part of a cartridge, as described below.

[0019] SAW atomizers are generally small and lightweight. Moreover, SAW atomizers, particularly those sized for use in electrically operated smoking devices, use less power than known vibrating elements (e.g., elements that use heat to generate aerosols). Furthermore, SAW atomizers generally have the ability to generate aerosols with small droplet sizes. These advantages of SAW atomizers improve the smoking device of the present invention and enable the provision of an efficient and economical smoking device.

[0020] A smoking device according to the present invention may further comprise a heater arranged to heat the liquid aerosol-forming substrate, preferably the liquid aerosol-forming substrate in the atomization region. The heater may be arranged to heat at least a portion of the SAW atomizer, and thereby heat the aerosol-forming substrate on the SAW atomizer. Preferably, the heater is arranged to heat at least the atomization region of the SAW atomizer, and thereby heat the aerosol-forming substrate in the atomization region.

[0021] The heater may heat the liquid aerosol-forming substrate and reduce the viscosity and surface tension of the liquid. By heating the liquid preferably not only before atomization but also during atomization, the heater may increase the rate of atomization. Heating the aerosol-forming substrate and reducing the viscosity of the liquid aerosol-forming substrate may increase the reliability of the device or smoking system, respectively.

[0022] The heater may heat the liquid aerosol-forming substrate to a consistent, predetermined temperature for atomization, which may allow for atomization of the liquid aerosol-forming substrate at a constant viscosity and may allow the device to produce aerosols at a constant atomization rate, improving the user experience.

[0023] The viscosity of the liquid aerosol-forming substrate can have an effect on the rate of atomization and droplet size of the aerosol produced by the device or system. Thus, heating the liquid aerosol-forming substrate to a consistent, predetermined temperature prior to atomization may facilitate the production of an aerosol with a consistent droplet size distribution.

[0024] Heating the liquid aerosol substrate to a temperature above ambient temperature prior to atomization may also reduce the sensitivity of the system to variations in ambient temperature, providing the user with a consistent aerosol with each use.

[0025] As used herein, the term "droplet size" is used to mean the aerodynamic droplet size, which is the size of a spherical unit density droplet that has the same velocity as the droplet in question. Several measurements are used in the art to describe the droplet size of aerosols. These include mass median diameter (MMD) and mass median aerodynamic diameter (MMAD). As used herein, the term "mass median diameter (MMD)" refers to the diameter of a droplet such that half the mass of the aerosol is contained in a small diameter droplet and half in a large diameter droplet. As used herein, the term "mass median aerodynamic diameter (MMAD)" refers to the diameter of a sphere of unit density that has the same aerodynamic properties as the median mass of droplets of the aerosol.

[0026] The mass median aerodynamic diameter (MMAD) of droplets generated by the smoking devices and systems of the present invention may be from about 1 μm to about 10 μm, or the MMAD may be from about 1 μm to about 5 μm. The MMAD of the droplets may be 3 μm or less. The desired droplet size of droplets generated by the smoking devices of the present invention may be any of the MMADs described above. The desired droplet size (MMAD) may be 3 μm or less.

[0027] The control system of the smoking device may be configured to operate the heater to heat the liquid aerosol-forming substrate to a predetermined temperature, preferably by heating at least a portion of the SAW atomizer to a predetermined temperature. The predetermined temperature may be higher than ambient temperature. The predetermined temperature may be higher than room temperature. This may reduce the viscosity of the aerosol-forming substrate compared to the viscosity of an unheated aerosol-forming substrate, as well as reduce surface tension. This may increase the rate of atomization and facilitate the generation of aerosols with a desired droplet size. This may reduce the sensitivity of the system to fluctuations in ambient temperature. The predetermined temperature may be below the vaporization temperature or below the boiling point of the liquid aerosol-forming substrate. The predetermined temperature may be between 18°C ​​and 80°C, or between 30°C and 60°C, or between 35°C and 45°C. The predetermined temperature may be between 20° C. and 30° C., between 30° C. and 40° C., between 40° C. and 50° C., between 50° C. and 60° C., between 60° C. and 70° C., or between 70° C. and 80° C. Preferably, the predetermined temperature of the heated portion of the SAW atomizer corresponds to the predetermined temperature of the liquid aerosol-forming substrate in the atomization region.

[0028] As used herein, the term "ambient temperature" refers to the air temperature of the environment in which the aerosol generating device or aerosol generating system is used. Ambient temperature typically corresponds to a temperature of about 10 degrees Celsius to 35 degrees Celsius. As used herein, the term "room temperature" refers to standard ambient temperature and pressure, typically a temperature of about 25 degrees Celsius and an absolute pressure of about 100 kPa (1 atm).

[0029] A control system configured to operate the heater may be integral with or separate from the control system of the smoking device.

[0030] The control system may include an electrical circuit connected to the heater and the power source. The electrical circuit may be configured to monitor the electrical resistance of the heater and control the supply of power to the heater in response to the electrical resistance of the heater. The electrical circuit may include a microprocessor, which may be a programmable microprocessor. The electrical circuit may include further electronic components. The electrical circuit may be configured to regulate the supply of power to the heater. Power may be supplied to the heater continuously after activation of the device, or intermittently (e.g., between puffs). Power may be supplied to the heater in the form of current pulses.

[0031] The heater may be located on the surface of the SAW atomizer, preferably next to the atomization region or on the opposite side of the atomization region. For example, the heater may be located on the same surface of the SAW atomizer as the atomization region. Such an arrangement allows direct physical contact or intimate contact between the heater and the heated liquid aerosol-forming substrate, particularly near the atomization region. The heater may surround or partially surround the aerosol-forming substrate, for example, within the atomization region.

[0032] In an arrangement in which the heater is located on the surface of the SAW atomizer opposite the atomization region, the supply of aerosol-forming substrate to the atomization region is not altered by the presence of the heater. Furthermore, the heater may be located at the atomization region, but may also be located on the opposite side of the SAW atomizer substrate. The size of the heater may correspond to the size of the SAW atomizer. The size of the heater may be limited to the size of the atomization region. The size of the heater may at least correspond to the size of the atomization region. The position of the heater may be shifted toward the supply element. This allows the liquid to be heated before it enters the atomization region. Preferably, the heat of the heater is transferred by thermal conduction through the SAW atomizer substrate.

[0033] As explained, the heater location may improve heat transfer between the heater on the SAW atomizer and the liquid aerosol-forming substrate.

[0034] The heater may be attached to the SAW atomizer or may be a separate heater located next to or near the SAW atomizer.

[0035] The heater may be integral with the SAW atomizer, which may reduce the number of component parts of the device and facilitate simple manufacturing.

[0036] The heater is preferably in a thermally conductive relationship with the SAW atomizer.

[0037] The heater may be located on or within the housing of the liquid reservoir, after which the liquid aerosol-forming substrate becomes hot when delivered from the liquid reservoir to the SAW atomizer.

[0038] The heater may be any suitable heater capable of heating the liquid aerosol-forming substrate. The heater may be an electrically operated heater. The heater may be a resistive heater. The heater may include an induction heating means. The heater may be substantially flat to allow for simple manufacturing. As used herein, the term "substantially flat" means formed in a single plane and not wrapped around or adapted to conform to a curved or other non-planar shape. A flat heater may be easier to handle during manufacturing and provides a sturdy structure.

[0039] The heater may comprise one or more conductive tracks on an electrically insulating substrate. The electrically insulating substrate may comprise any suitable material and may be a material that can withstand high temperatures (greater than 150 degrees Celsius) and rapid temperature changes. One example of a suitable material is a polyimide film such as Kapton®.

[0040] A control system configured to operate the heater or the SAW atomizer, or both, may include an ambient temperature sensor to detect ambient temperature. The control system may include a temperature sensor on the SAW atomizer to detect the temperature of the liquid aerosol-forming substrate in the atomization region. The one or more temperature sensors may interface with the control electronics of the aerosol-generating device to enable the control electronics to maintain the temperature of the liquid aerosol-forming substrate at a predetermined temperature. The one or more temperature sensors may be thermocouples or resistance temperature sensors. The heater may be used to provide information regarding temperature. The temperature-dependent resistance characteristics of heaters are well known and may be used to determine the temperature of at least one heater in a manner known to those skilled in the art.

[0041] In a smoking device according to the present invention, a portion of the supply element may be positioned adjacent to the atomization region of the SAW atomizer, while another portion of the supply element may be fluidly connectable to the liquid storage portion. The portion of the supply element positioned adjacent to the atomization region may extend into the atomization region. When the smoking device is ready for use, the supply element may allow the transfer of a liquid aerosol-forming substrate from a liquid storage portion, such as a cartridge, to the atomization region. This allows the other portion of the supply element to be directly connected to the liquid storage portion (e.g., inserted into the contents of the liquid storage portion) or positioned adjacent thereto. However, the aerosol-forming substrate may also be transferred outside the liquid storage portion, for example, within a liquid passageway, and may be fluidly connected to another portion of the supply element further downstream in the liquid transfer from the storage portion to the SAW atomizer. Separation of the liquid transfer may enhance variability and optimization of the liquid transfer means from the liquid storage portion to the SAW atomizer. In particular, the supply elements for supplying the liquid aerosol-forming substrate to the SAW atomizer may be optimized for supplying and distributing the liquid to and across the atomization region, while the liquid transport outside the liquid reservoir may be optimized.

[0042] The delivery element may be, for example, but is not limited to, a wick or strip of paper, a capillary element such as a capillary tube or piercing element for piercing a cartridge containing the liquid aerosol-forming substrate.

[0043] The supply element is preferably a capillary element that has capillary action on the liquid aerosol-forming substrate. A supply element in the form of a capillary element preferably allows the liquid aerosol-forming substrate to be supplied to the atomization region of the SAW atomizer. The capillary element is made of or includes a material through which the liquid aerosol-forming substrate is transported by capillary action. A capillary material is a material that actively transports liquid from one end of the material to the other. Advantageously, the capillary material is oriented within the device to transport the liquid aerosol-forming substrate to the atomization region on the surface of the SAW atomizer. The capillary material may have a fibrous or spongy structure. The capillary material may include a capillary tube, multiple fibers, multiple bundles of threads, or fine tubes. The capillary material may include a combination of fibers, threads, and fine tubes. The fibers, threads, and fine tubes may generally be aligned to transport the liquid to the SAW atomizer. The capillary material may comprise a sponge-like material or may comprise a foam-like material. The structure of the capillary material may form a plurality of small holes or tubes through which liquid can be transported by capillary action.

[0044] The capillary material may comprise any suitable material or combination of materials. Examples of suitable materials include sponge or foam materials, ceramic-based, paper-based, or graphite-based materials in the form of fibers or sintered powders, expanded metal or plastic materials, and sheet materials, such as fibrous materials made of spun or extruded fibers (such as cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene, or polypropylene fibers, nylon fibers, or ceramics). The capillary material may be paper-based. The capillary material may have any suitable capillary action and porosity to be used with different liquid physical properties.

[0045] The liquid aerosol-forming substrate has physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, and boiling point, that allow the liquid to be transported by capillary action through the capillary material of the capillary element. The capillary element may be configured to transport the liquid aerosol-forming substrate to the atomization region of the SAW atomizer. The capillary element may be in the form of a sheet. Some capillary materials (e.g., paper-based wick materials, etc.) may further have the ability to filter contaminants from the liquid, thus supporting the atomization of pure liquid aerosol-forming substrates.

[0046] The delivery element may be a separate element or may be part of the SAW atomizer. Preferably, the delivery element is part of (e.g., integral with) the SAW atomizer.

[0047] The feed element may be a wick element, as is well known in the art, that uses the capillary effect to transport the liquid. The feed element may also use, for example, the Venturi effect to transport the liquid to the atomization region. The feed element may be, for example, a microchannel integrated into the substrate of the SAW atomizer, or any combination of the feed elements described above.

[0048] The SAW atomizer may include at least one piezoelectric transducer. The SAW atomizer may include at least one interdigital transducer. The piezoelectric transducer preferably includes a single crystal material, but may also include a polycrystalline material. The piezoelectric transducer may include quartz, ceramic, barium titanate (BaTiO3), or lithium niobate (LiNbO3). The ceramic may include lead zirconate titanate (PZT). The ceramic may include a doping material such as Ni, Bi, La, Nd, or Nb ions. The piezoelectric transducer may be poled. The piezoelectric transducer may be unpoled. The piezoelectric transducer may include both poled and unpoled piezoelectric materials.

[0049] A SAW atomizer may include one transducer for generating surface acoustic waves. A SAW atomizer may include two or more transducers for generating surface acoustic waves. The transducer that generates the surface acoustic waves is called the input transducer. The input transducer receives an electrical signal and generates surface acoustic waves in accordance with the input signal. Two or more input transducers may generate surface acoustic waves that interfere with each other, preferably with beneficial interference to enhance the energy input to the atomization region. Additional input transducers may be used to collect the liquid within the atomization region, or generally to collect the liquid within a small zone.

[0050] If the SAW atomizer includes two or more transducers, at least one of the two or more transducers may be used to generate the electrical signal.

[0051] The transducer that generates the electrical signal is called the output transducer. The output transducer converts the surface acoustic waves into an output signal. The surface acoustic waves received by the output transducer are generated by at least one input transducer and propagate along the atomization region of the SAW atomizer to the output transducer. The output signal may contain information about the physical process in the atomization region (e.g., the amount of liquid present in the atomization region). Therefore, the SAW atomizer may be used as a SAW sensor to obtain information about the atomization process. This information may be used to control the atomization process. The sensor information may be used in a control system that, for example, controls the operation of the SAW atomizer or, for example, controls a heater. Control of the atomization process may be achieved, for example, through adjustment of the power supplied to the SAW atomizer.

[0052] The SAW atomizer includes at least a second transducer, which may be used to generate an electrical signal representing physical information about the atomization region. Alternatively, the at least second transducer may be used to generate additional surface acoustic waves.

[0053] When two transducers are present, the two transducers are preferably positioned opposite each other with an atomization region disposed between the two transducers. The first of the two transducers is an input transducer. The second of the two transducers may be either an input transducer or an output transducer.

[0054] In the smoking device according to the present invention, the liquid reservoir, SAW atomizer, and supply element may form part of a cartridge. The cartridge, with or without the SAW atomizer and supply element, may be pre-manufactured. The cartridge may be removable, replaceable, reusable, or disposable. The cartridge may be refillable with the liquid aerosol-forming substrate. With a refillable liquid reservoir, or particularly with a replaceable cartridge, the smoking device becomes reusable. Preferably, the cartridge is not refillable or replaced after each use.

[0055] The device housing may include a recess for receiving the cartridge.

[0056] The cartridge may be removably coupled to the aerosol-generating device. The cartridge may be removed from the aerosol-generating device when the aerosol-forming substrate is consumed. As used herein, the term "removably coupled" is used to mean that the cartridge and device can be coupled and separated from each other without significant damage to either the device or the cartridge.

[0057] The cartridge may be manufactured in a low-cost, reliable and reproducible manner. The cartridge may have a simple design. The cartridge may have a housing in which the aerosol-forming substrate is held.

[0058] The cartridge may comprise a liquid-retaining material that holds the aerosol-forming liquid. The cartridge may be a liquid-filled tank system.

[0059] The cartridge housing may be a rigid housing. As used herein, "rigid housing" means a free-standing housing. The housing may comprise a material that is impermeable to liquids.

[0060] The cartridge may have a lid, which may be peelable before coupling the cartridge to the aerosol generating device, and which may be pierceable, for example, by a dispensing element.

[0061] A cartridge comprising a delivery element and a SAW atomizer allows for a completely "fresh" atomization process whenever the cartridge is replaced. Any deposits or residue in the delivery element or on the SAW atomizer can be removed when the cartridge is replaced. The SAW atomizer, including the delivery element, may be a reusable and preferably fixedly attached element in the smoking device. This may reduce waste and material costs.

[0062] According to another aspect of the present invention, there is provided a method for generating an aerosol in a smoking system. The method includes providing a surface acoustic wave atomizer (SAW atomizer) having an atomization region, at least one transducer, and at least a second transducer. The method further includes providing a liquid aerosol-forming substrate to the atomization region of the SAW atomizer and operating the SAW atomizer to generate surface acoustic waves using the at least one transducer, the surface acoustic waves propagating along the surface of the SAW atomizer to the atomization region and to the liquid aerosol-forming substrate in the atomization region, thereby atomizing the liquid aerosol-forming substrate and generating an aerosol. The method may be implemented using a smoking device, smoking system, and cartridge according to other aspects of the present invention.

[0063] The method may have all the advantages described in relation to other aspects of the invention, and the characteristics of the SAW atomizer (e.g., mode of operation, etc.), the characteristics of the supply element (e.g., its arrangement and structure, etc.), and the characteristics of the heater (e.g., predetermined temperature) may be the same as those described in relation to other aspects of the invention.

[0064] The method may include fluidly connecting a liquid reservoir (eg, a cartridge containing a liquid aerosol-forming substrate) with an atomization region of a SAW atomizer.

[0065] The method may include providing a radio frequency signal to at least one transducer.

[0066] The method may further comprise the step of supplying a quantity of liquid aerosol-forming substrate to the SAW atomizer, the quantity of liquid corresponding to one puff.

[0067] The method may include the step of heating the liquid aerosol-forming substrate in the atomization region, preferably to a temperature above room temperature prior to atomization. Heating may be carried out so that the temperature of the liquid to be atomized is above 50 degrees Celsius, for example between 50 and 80 degrees Celsius.

[0068] The method according to the present invention may further comprise the step of providing a SAW atomizer with at least a second transducer.

[0069] The method may then include outputting a signal using at least one second transducer. The output signal is representative of a physical process within the atomization region. The output signal may be used to control operation of the SAW atomizer. For example, the output signal may be used as an input signal to a control system for controlling the SAW atomizer or heater.

[0070] Alternatively, the method may include generating additional surface acoustic waves using at least a second transducer and propagating the additional surface acoustic waves along the surface of the SAW atomizer to the atomization region and to a liquid aerosol-forming substrate within the atomization region.

[0071] According to another aspect of the present invention, there is provided an aerosol-generating smoking system comprising a smoking device as described herein. The system may comprise a liquid aerosol-forming substrate. The supply element fluidly connects the liquid aerosol-forming substrate provided within a housing of a liquid storage portion of the smoking device with an atomization region on a surface acoustic wave atomizer (SAW atomizer).

[0072] The liquid aerosol-forming substrate comprises at least one aerosol former and a liquid additive. The aerosol former may be, for example, propylene glycol or glycerol.

[0073] The liquid aerosol-forming substrate may comprise water.

[0074] The liquid additive may be any one or any combination of liquid flavors or liquid stimulants. The liquid flavors may include, for example, tobacco flavors, tobacco extracts, fruit flavors, or coffee flavors. The liquid additive may be, for example, a sweet liquid (e.g., vanilla, caramel, cocoa, etc.), an herbal liquid, a spicy liquid, or a stimulant liquid (e.g., a liquid containing caffeine, taurine, nicotine, or other stimulants well known in the food industry).

[0075] According to yet another aspect of the present invention, there is provided a cartridge for a smoking device for generating aerosols. The cartridge includes a liquid storage portion having a housing for holding a liquid aerosol-forming substrate. The cartridge further includes a surface acoustic wave atomizer (SAW atomizer) including an atomization region, at least one transducer for generating surface acoustic waves that propagate along a surface of the SAW atomizer including the atomization region, and at least a second transducer. A supply element is provided and arranged to supply the liquid aerosol-forming substrate from the liquid storage portion housing to the atomization region on the SAW atomizer.

[0076] As described herein, the liquid reservoir, SAW atomizer, delivery element, or heater may have any of the features or be arranged in any of the configurations described above for the liquid reservoir, SAW atomizer, delivery element, and heater of the aerosol generating device. The advantages and features of the cartridge have been described in relation to the smoking device and will not be repeated.

[0077] According to a further aspect, a smoking device for aerosol generation from a liquid aerosol-forming substrate is provided. The smoking device includes a device housing having a liquid storage portion with a housing for holding the liquid aerosol-forming substrate. The device housing may include a recess for receiving, for example, a cartridge, the cartridge including the liquid aerosol-forming substrate. The smoking device further includes a surface acoustic wave atomizer (SAW atomizer) including an atomization region and at least one transducer for generating surface acoustic waves that propagate along a surface of the SAW atomizer including the atomization region. A supply element is arranged to supply the liquid aerosol-forming substrate from the liquid storage portion to the atomization region on the SAW atomizer. The supply element may fluidly connect the liquid storage portion, e.g., a cartridge, to the SAW atomizer, particularly the atomization region on the SAW atomizer. A control system is configured to operate the SAW atomizer to atomize the liquid aerosol-forming substrate in the atomization region to generate an aerosol. The control system may include, for example, a power source and control electronics connected to the SAW atomizer. The control system is adapted to provide, for example, an RF signal to the at least one transducer, and the generated aerosol may then be transported within the device housing to a downstream end of the smoking device and delivered to a user of the smoking device.

[0078] The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0079] [Figure 1] FIG. 1 illustrates schematically an aerosol generating device having a pierceable cartridge and a SAW atomizer with a focusing transducer. [Figure 2] FIG. 2 illustrates a schematic diagram of an aerosol generating device having a SAW atomizer with two focusing transducers. [Figure 3] FIG. 3 illustrates schematically an aerosol generator having a pierceable cartridge and a pointed SAW atomizer with a focusing transducer. [Figure 4] FIG. 4 shows a SAW atomizer with a straight transducer. [Figure 5] FIG. 5 shows the SAW atomizer of FIG. 4 with a reflector. [Figure 6] FIG. 6 shows a SAW atomizer with a straight transducer having a different reflector and an additional heating element. [Figure 7] FIG. 7 shows a SAW atomizer with a focusing transducer. [Figure 8] FIG. 8 shows a top view of a SAW atomizer with a focusing transducer, a heating element, and a capillary element. [Figure 9] FIG. 9 shows a cross section (along center line A--A) of the SAW atomizer of FIG. [Figure 10] FIG. 10 shows a cross section along the centerline of a further embodiment of a SAW atomizer with a heating element. [Figure 11] FIG. 11 shows a cross section along the centerline of a further embodiment of a SAW atomizer with a heating element. [Figure 12] FIG. 12 shows a top view of a SAW atomizer with two focusing transducers. [Figure 13] FIG. 13 shows a cross section (along center line B-B) through the SAW atomizer of FIG. [Figure 14] FIG. 14 shows a top view of a SAW atomizer having a feed element with microchannels. [Figure 15] FIG. 15 shows a cross section (along center line C-C) through the SAW atomizer of FIG. [Figure 16] FIG. 16 shows a top view of a SAW atomizer with a countersunk delivery element. [Figure 17] FIG. 17 shows a cross section (along center line D--D) through the SAW atomizer of FIG. [Figure 18] FIG. 18 shows the surface treatment of the SAW atomizer. DETAILED DESCRIPTION OF THE INVENTION

[0080] 1 shows an electronic aerosol generating device comprising a housing 10 and a mouthpiece 11. The housing comprises a cartridge 16 containing an aerosol-forming liquid, a surface acoustic wave atomizer (SAW atomizer) tip 15, electronics 14 for operating and controlling the SAW atomizer, and a battery 13 for providing power to the electronics 14 and the SAW atomizer 15. The SAW atomizer tip 15 is a rectangular tip comprising a focusing interdigital transducer 20 including a reflector, which is described in more detail below.

[0081] The cylindrical cartridge 16 is closed at its distal end facing the SAW atomizer tip with a sealing element (e.g., a pierceable or puncturable foil 160). The sealing element is pierced by a supply element in the form of a sharp capillary element 30 (e.g., a needle or a piece of paper). The other, distal end of the capillary element 30 reaches the focusing zone of the transducer 20 on the tip, which corresponds to the atomization region 40 or vaporization region on the tip 15.

[0082] Figure 2 shows another embodiment of an electronic aerosol generating device, in which the same reference numerals are used for the same or similar elements. In Figure 2, a SAW atomizer 15 includes two focused interdigital transducers 20 positioned opposite each other. An atomization region 40 is located between the two transducers 20.

[0083] Both transducers may be operated to generate surface acoustic waves, which may enhance atomization within the atomization region 40 or may require less power to achieve the same vaporization rate. Alternatively, one of the two transducers may be operated to provide a signal representative of an effect or condition within the atomization region (e.g., vaporization rate or the presence or absence of liquid). The signal may be used within the electronics 14 to control, and possibly adapt, the atomization process.

[0084] 2, the distal end of cartridge 16 is closed by a layer of porous material 161. The porous material is in contact with wick 31 (e.g., a strip or strand of fiber or paper) that extends from porous material 161 to atomization region 40 on tip 15. Due to the arrangement of the two transducers 20 with a wave propagation direction substantially perpendicular to the longitudinal axis of the device, wick 31 is between the two transducers.

[0085] Figure 3 shows yet another embodiment of an electronic aerosol generating device similar to that shown in Figure 1, with the same reference numerals used for the same or similar elements. In Figure 3, the SAW atomizer tip 15 includes a pointed tip portion 150 that supports piercing the pierceable membrane 160 of the cartridge. A capillary tube 32 is positioned to extend between the interior of the cartridge 16 and the atomization region 40 of the tip 15. The capillary tube 32 may be, for example, a microchannel.

[0086] Optional heaters may be placed on each side of the capillary, on top of the capillary, or on the backside of the chip.

[0087] 4-17 show different examples of embodiments of the SAW atomizer tip 15 and the arrangement and embodiment of the transducer, capillary element, and heating element.

[0088] In FIG. 4, a single interdigital transducer 21 is disposed on a lateral surface of a piezoelectric substrate. The transducer 21 comprises a series of parallel, straight, interdigitated electrodes 210 (straight transducer). The atomization region 40 is indicated by a dashed line and is disposed near the transducer but on the opposite lateral surface of the piezoelectric substrate. In FIG. 5, the same transducer 21 is provided with a reflector electrode 215. The straight reflector electrode 215 is disposed parallel to the electrodes 210 of the transducer 21 and adjacent to the side of the transducer opposite the side facing the atomization region 40. The reflector electrode may reflect the surface acoustic waves back toward the intended propagation direction (to the right in the figure). The transducer 21 may have, for example, 20 electrode pairs and 32 reflector electrodes 215 disposed on a LiNbO3 substrate. The electrode material may be gold.

[0089] 6 includes a reflector electrode 216 disposed between the transducer electrodes 210. A heating element, e.g., a resistive heater 50 in the form of a printed circuit trace, is disposed on the substrate opposite the atomization region 40.

[0090] 7 shows an example of a focusing interdigital transducer 20 having curved, tapered electrodes 211 that focus the generated waves onto a small focusing zone 200 on the surface of the substrate. Between the transducer electrodes 211, curved reflector electrodes 214 are positioned parallel to the transducer electrodes.

[0091] FIG. 8 shows the SAW chip 15 of FIG. 7 having an embedded heater 50 on the surface of the chip and a capillary element 31 (e.g., a wick or capillary) in the form of a strip disposed over the heater 50 substantially along the direction of propagation of the wave generated by the transducer 21.

[0092] Figure 9 is a cross-section of the chip of Figure 8. The transducer 20 and heater 50 are disposed on the same surface (top surface) of a piezoelectric substrate 151, e.g., a lithium niobate substrate. A wick 31 is disposed partially over and in intimate contact with the heater to support heating of liquid transported through the wick 31 from a cartridge (not shown) to an atomization region disposed between the transducer 20 and heater 50.

[0093] 10 and 11 show cross sections of further embodiments of the SAW chip 15. In FIG. 10, the heater 50 is positioned on the opposite side (backside) of the substrate 151. The heater "extends" into the atomization region and "overlaps" the wick 31, with the substrate 151 between them. The thickness of the piezoelectric substrate may be reduced to reduce the path the heat must travel through the substrate to reach the liquid in the wick 31 or in the atomization region. In FIG. 11, the transducer 20 and wick 31 are positioned on the surface of a piezoelectric layer 152, such as LiNbO, ZnO, AlN, or other piezoelectric material suitable for SAW atomizer applications. The heater 50 is positioned on the backside of the layer 152 in the same position as described and shown in FIG. 10.

[0094] The layer 152 is arranged on a support 153 (for example a substrate made of glass, ceramic, silicon or metal). For manufacturing reasons, the heater may be applied to the substrate 153, which is then provided with the piezoelectric layer 152.

[0095] While the heater has been shown as being located on the chip, the heater may also be located along the capillary material or channel, for example, between the chip and the cartridge containing the aerosol-forming liquid.

[0096] 12 and 13, two focusing transducers 20 provided with reflector electrodes are arranged opposite each other on a piezoelectric substrate 151. The two transducers 20 have a common focusing zone 200 between them. In the focusing zone 200, the substrate 151 is provided with through-holes 155 through which aerosol-forming liquid may be supplied to the upper surface of the substrate 151. A capillary element 33 is arranged below the substrate 151 for supplying liquid to the lower part of the through-holes 155. Optionally, the through-holes 155 may be filled with a capillary material. In this embodiment, the atomization zone 41 is collected at the edge of the through-holes 155 on the surface of the substrate 151. The sharp edges support the formation of a very thin aerosol-forming liquid layer, which promotes its evaporation.

[0097] 14 and 15, aerosol-forming liquid is supplied to the chip via a capillary element in the form of a sheet of wick material 34. The sheet 34 extends over the surface of a substrate 151 and partially covers a series of parallel microchannels 35 provided in the substrate surface. The microchannels extend to the atomization region of a straight transducer 21, which is also disposed on the substrate surface. However, the atomization area 41 is concentrated above the edge of the microchannel.

[0098] 16 and 17, a similar result may be achieved with a countersunk capillary element 36 when the atomization region 41 is collected on the substrate edge 156. A portion of the substrate surface is removed, for example by etching. A capillary element (e.g., a piece of paper) is placed on this lower level surface portion, flush with the edge 156 of the lower portion, so that the liquid can be transported to the edge 156.

[0099] Surface treatment of the substrate 151 may also support the formation of a thin aerosol-forming liquid layer. The surface treatment may also support the localization of such a layer. For example, and as shown in Figure 18, the atomization region 40 (indicated by the dashed line) may be treated to form a hydrophilic area, while the area outside the indented atomization region may be a hydrophobic area 158.

[0100] An exemplary power range for operating a SAW chip with one or two transducers in an aerosol generating device according to the present invention is 5 Watts to 15 Watts, preferably less than 20 Watts. Typical transducer electrode distances are in the range of about 100 micrometers (straight transducers), while reflector distances may be in the range of about 50 micrometers.

[0101] The size of the rectangular SAW chip with two transducers is about 50 mm x 20 mm to 55 mm x 25 mm.

[0102] An exemplary aerosol-forming liquid composition was 40 to 80 percent propylene glycol, 20 percent water, and 0 to 40 percent glycerol. The aerosol-generating liquid was heated to approximately 65° C. A volume of approximately 5 microliters of such liquid was atomized or vaporized in less than 20 seconds, achieving a vaporization rate of approximately 0.2 to 0.3 microliters per second or greater.

[0103] 1. A smoking device for aerosol generation of a liquid aerosol-forming substrate, comprising: a device housing having a liquid storage portion with a housing for holding a liquid aerosol-forming substrate; a surface acoustic wave atomizer (SAW atomizer) having an atomization region, at least one transducer for generating surface acoustic waves that propagate along a surface of the SAW atomizer including the atomization region, and at least a second transducer; a supply element arranged to supply liquid aerosol-forming substrate from the liquid storage portion to the atomization region on the SAW atomizer; and a control system configured to operate the SAW atomizer to atomize the liquid aerosol-forming substrate in the atomization region to generate an aerosol. 2. A smoking device as described in 1, wherein the at least one transducer is an interdigital transducer having electrodes arranged on a piezoelectric substrate. 3. A smoking device according to any one of claims 1 to 2, further comprising a heater arranged to heat the liquid aerosol-forming substrate. 4. A smoking device as described in 3, wherein the control system is configured to operate the heater to heat the liquid aerosol-forming substrate to a predetermined temperature. 5. A smoking device described in any one of claims 3 or 4, wherein the heater is positioned on the surface of the SAW atomizer, next to the atomization region, or on the surface of the SAW atomizer opposite the atomization region. 6. A smoking device described in any one of claims 1 to 5, wherein a portion of the supply element is positioned adjacent to the atomization region of the SAW atomizer, and another portion of the supply element is fluidly connectable to the liquid storage portion. 7. A smoking device as described in any one of claims 1 to 6, wherein the supply element is a capillary element having capillary action on the liquid aerosol-forming substrate supplied to the atomization region of the SAW atomizer. 8. A smoking device described in any one of claims 1 to 7, wherein the at least second transducer is for generating an electrical signal representing physical information of the atomization area or for generating additional surface acoustic waves. 9. A smoking device described in any one of claims 1 to 8, wherein the liquid storage portion, the SAW atomizer, and the supply element form part of a cartridge, and the device housing has a recess for receiving the cartridge. 10. A method for generating an aerosol in a smoking system, the method comprising: providing a surface acoustic wave atomizer (SAW atomizer) having an atomization region and at least one transducer; providing a liquid aerosol-forming substrate in the atomization region of the SAW atomizer; and operating the SAW atomizer to generate surface acoustic waves using the at least one transducer, the surface acoustic waves propagating along a surface of the SAW atomizer to the atomization region and to the liquid aerosol-forming substrate in the atomization region, thereby atomizing the liquid aerosol-forming substrate and generating the aerosol. 11. The method of claim 10, further comprising the step of heating the liquid aerosol-forming substrate in the atomization region to a temperature above room temperature. 12. The method of any one of claims 10 to 11, further comprising the steps of providing the SAW atomizer with at least a second transducer, and using the at least one second transducer to output a signal, the output signal representing a physical process within the atomization region, and using the output signal to control operation of the SAW atomizer; or generating additional surface acoustic waves using the at least second transducer, and propagating the additional surface acoustic waves along the surface of the SAW atomizer to the atomization region and to the liquid aerosol-forming substrate within the atomization region. 13. An aerosol-generating smoking system comprising a smoking device described in any one of claims 1 to 9 and a liquid aerosol-forming substrate, wherein a supply element is fluidly connected to the liquid aerosol-forming substrate provided within a housing of a liquid storage portion of the smoking device and is fluidly connected to an atomization region on a surface acoustic wave atomizer (SAW atomizer). 14. The aerosol generating system of claim 13, wherein the liquid aerosol-forming substrate comprises at least one aerosol former and a liquid additive. 15. A cartridge for a smoking device for generating aerosols, comprising: a liquid storage portion having a housing for holding a liquid aerosol-forming substrate; a surface acoustic wave atomizer (SAW atomizer) having an atomization region, at least one transducer for generating surface acoustic waves that propagate along a surface of the SAW atomizer including the atomization region, and at least a second transducer; and a supply element arranged to supply the liquid aerosol-forming substrate from the housing of the liquid storage portion to the atomization region on the SAW atomizer.

Claims

1. An aerosol generating device, the aerosol generating device comprising: a liquid reservoir for holding a liquid aerosol-forming substrate; a surface acoustic wave atomizer for atomizing the liquid aerosol-forming substrate to generate an aerosol; The surface acoustic wave atomizer comprises: an atomization region; at least one transducer configured to generate surface acoustic waves that propagate along a surface of the surface acoustic wave atomizer, including the atomization region; The aerosol generating device comprises: a heater arranged to heat the liquid aerosol-forming substrate, said heater being arranged on the same surface as the atomization region and at least one transducer of the surface acoustic wave atomizer; a supply element arranged to supply a liquid aerosol-forming substrate from the liquid storage portion to the atomization region, the supply element at least partially covering the heater; and a control system configured to control operation of the surface acoustic wave atomizer. Aerosol generator.

2. 2. The aerosol generating device of claim 1, wherein the control system is configured to operate the heater to heat the liquid aerosol-forming substrate to a predetermined temperature.

3. 3. The aerosol generating device according to claim 1, wherein the at least one transducer is an interdigital transducer having electrodes arranged on a piezoelectric substrate.

4. An aerosol generating device as described in any one of claims 1 to 3, wherein the at least one transducer is a focusing transducer having curved electrodes that focus the generated surface acoustic waves into a focusing zone located in the atomization region.

5. The aerosol generating device according to claim 1 , wherein the atomizing region further comprises a hydrophilic area.

6. 6. The aerosol generating device of claim 1, wherein at least one region of the surface acoustic wave atomizer outside the atomization region is hydrophobic.

7. 7. The aerosol generating device according to claim 1, wherein the atomizing region is recessed.

8. 8. The aerosol generating device according to claim 1, wherein the atomization region extends to the edge of the surface acoustic wave atomizer.

9. 9. The aerosol generating device of claim 1, wherein a portion of the supply element is positioned adjacent to the atomization region of the surface acoustic wave atomizer, and another portion of the supply element is fluidly connectable to the liquid storage portion.

10. 10. The aerosol generating device according to claim 1, wherein the supply element is a capillary element having capillary action for supplying a liquid aerosol-forming substrate to the atomization region of the surface acoustic wave atomizer.

11. An aerosol generating device described in any one of claims 1 to 10, wherein the surface acoustic wave atomizer further comprises a second transducer, the second transducer being configured to generate an electrical signal representing physical information of the atomization region or to generate further surface acoustic waves.

12. 12. The aerosol generating device of claim 11, configured to control operation of the surface acoustic wave atomizer in accordance with the electrical signal.

13. 13. The aerosol generating device of claim 1, wherein the liquid storage portion, the surface acoustic wave atomizer, and the supply element form part of a cartridge, and the aerosol generating device further comprises a housing having a recess for receiving the cartridge.

14. 1. A cartridge for an aerosol generation system, said cartridge comprising: a liquid reservoir for holding a liquid aerosol-forming substrate; a surface acoustic wave atomizer for atomizing the liquid aerosol-forming substrate to generate an aerosol; The surface acoustic wave atomizer comprises: an atomization region; at least one transducer configured to generate surface acoustic waves that propagate along a surface of the surface acoustic wave atomizer, including the atomization region; The cartridge comprises: a heater arranged to heat the liquid aerosol-forming substrate, said heater being arranged on the same surface as the atomization region and at least one transducer of the surface acoustic wave atomizer; a supply element arranged to supply a liquid aerosol-forming substrate from the liquid storage portion to the atomization region, the supply element at least partially covering the heater. cartridge.

15. 15. An aerosol generating system comprising the cartridge of claim 14, wherein the aerosol generating device comprises: a housing having a recess for receiving the cartridge; a control system configured to control operation of the surface acoustic wave atomizer; An aerosol generating system comprising:

16. 16. The aerosol generation system of claim 15, wherein the cartridge is removably connectable to the aerosol generation device.

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