AEROSOL-GENERATING SYSTEM

The present invention relates to an atomizing assembly of an aerosol-generating system, such as a handheld electrically operated aerosol-generating system. The invention relates also to an aerosol-generating system comprising such atomizing assembly and a method of generating an aerosol in an aerosol-generating system.

One type of an aerosol-generating system is an electrically operated aerosol- generating system. Handheld electrically operated aerosol-generating systems are known that consist of a device portion comprising a battery and control electronics, a cartridge portion comprising a supply of aerosol-forming substrate held in a liquid storage portion, and an electrically operated vaporiser, and a mouthpiece, from which the user inhales aerosol The vaporiser typically comprises a coil of heater wire wound around an elongate wick soaked in the liquid aerosol-forming substrate held in the liquid storage portion.

EP 0 957 959 B1 discloses an electrically operated aerosol generator for receiving liquid material from a source, the aerosol generator comprising a pump for pumping the liquid material in metered amounts from the source through a tube with an open end. A heating element is provided which surrounds the tube. The liquid material within the tube is volatilized upon activation of the heater. Upon volatilization the liquid material expands and exits the open end of the tube in gaseous form.

Residues are created upon heating. In capillary tubes, the residues can cause clogging. This effect can alter liquid transport properties. Furthermore, the liquid material is heated indirectly: First the tube or a capillary wick is heated which in turn heats the liquid material. Heat can therefore be lost during the energy transfer process.

Moreover, volatilization in the above described system is rather slow, as a substantial amount of liquid is to be volatilized in the confined volume within the tube.

It would be desirable to provide an improved aerosol-generating system with a low- maintenance liquid transport system and with an improved atomization effect.

According to a first aspect of the present invention there is provided an atomizing assembly for an aerosol-generating system, comprising a tubing section for conveying a liquid aerosol-forming substrate with an inlet end and an outlet end. The inlet end of the tubing section is configured to be connected to a liquid storage portion, and the outlet end of the tubing section is connected to an atomizing nozzle. The tubing section is configured for delivering a flow of liquid aerosol-forming substrate through the atomizing nozzle. The atomizing nozzle comprises an air channel for establishing an air flow through the atomizing nozzle, the air flow being mixed with the flow of liquid aerosol-forming substrate to enhance atomization of the flow of liquid aerosol-forming substrate delivered through the atomizing nozzle.

In examples of the present invention the liquid aerosol-forming substrate is finely distributed into a spray jet of small droplets. By mixing the spray jet with the air stream atomization of the liquid aerosol-forming substrate can be enhanced. The average size of the droplets may for example be reduced. The liquid may be more homogeneously distributed and may be fully, i.e. without residues, and quickly volatilized by a downstream heater element. In this way a reproducible aerosol generation can be achieved.

The tubing section may comprise a pumping unit for controllably delivering a predefined amount of liquid aerosol-forming substrate through the atomizing nozzle. The pumping unit may be any commercially available pumping system, such as an electrically driven pump, a motorized pump, a micro pump or a manually operated pump. The pumping unit is configured to transport the liquid aerosol-forming substrate from the liquid storage portion to the atomizing nozzle. The pumping unit is further configured to deliver the liquid aerosol-forming substrate with a slight over pressure to the atomizing nozzle such that the liquid aerosol-forming substrate is transformed into a spray jet.

Alternatively to using a pumping unit for conveying the liquid aerosol-forming substrate from the liquid storage portion to the atomizing nozzle, it is also possible use a liquid storage portion comprising pressurized liquid aerosol-forming substrate. The tubing section may then comprise a controllable one-way valve which may be configured to deliver a metered amount of liquid aerosol-forming substrate to the atomizing nozzle upon activation. The liquid aerosol-forming substrate may be pressurized in the liquid storage portion by mechanical means or by adding suitable propellants to the liquid aerosol-forming substrate. Mechanical means may include elastic collapsible containers or pumping systems.

The inlet portion of the tubing section is configured for connection to a liquid storage portion. The connection between the tubing section and the liquid storage portion may be a permanent connection or a releasable connection. In some embodiments the liquid storage portion may be refillable. In some embodiments the liquid storage portion may be replaceable and may be exchanged when it is empty or when the user would like to use a different type of liquid substrate for aerosol-generation. The releasable connection between the tubing section and the liquid storage portion may be established by any suitable connection means, including a Luer taper connection (either the locking or fitting type).

The tubing section may further comprise at least one one-way valve for controlling fluid flow through the tubing section. Any commercially available one-way valves with adequate size and liquid flows may be used, including mini and micro flutter valves, duckbill valves, check valves. The valves may be made of any suitable material for example materials, which may be used for food industry or medical applications.

The liquid aerosol-forming substrates used with the present invention are characterized by a relatively high viscosity as compared to water. The viscosity of a liquid aerosol-forming substrate may be in the range from about 10 to 500 millipascal seconds, preferably in the range from about 17 to 86 millipascal seconds. The liquid aerosol-forming substrate is a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds may be released by heating the liquid aerosol-forming substrate. The liquid aerosol-forming substrate may comprise plant-based material. The liquid aerosol-forming substrate may comprise tobacco. The liquid aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavor compounds, which are released from the liquid aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may alternatively comprise a non-tobacco-containing material. The liquid aerosol-forming substrate may comprise homogenized plant-based material. The liquid aerosol-forming substrate may comprise homogenized tobacco material. The liquid aerosol-forming substrate may comprise at least one aerosol-former. The liquid aerosol-forming substrate may comprise other additives and ingredients, such as flavourants.

According to a second aspect of the invention there is provided an aerosol-generating system, comprising the above disclosed atomizing assembly and further comprising a housing with an air inlet and a mouthpiece, establishing an air flow path from the air inlet to the mouthpiece.

When a user inhales through the mouthpiece, an air flow is generated in the air flow path between the air inlet and the mouthpiece wherein at least a portion of this airflow is guided through the air channel of the atomizing nozzle. The air flow is mixed with the flow of liquid aerosol-forming substrate thereby enhancing atomization effect of the spray nozzle.

The airflow through the atomizing nozzle may be mixed with the flow of liquid aerosol- forming substrate within the atomizing nozzle and the mixed flow may be delivered through a common outlet end of the atomizing nozzle.

Alternatively, the air flow through the atomizing nozzle and the flow of liquid aerosol- forming substrate are delivered through separate outlets provided in the atomizing nozzle. In some embodiments the atomizing nozzle may have a central outlet opening for the liquid aerosol-forming substrate which creates a spray jet of small droplets of liquid aerosol-forming substrate. A ringshaped outlet opening arranged radially outwardly from and concentrically with the central opening may be provided as air stream outlet opening. The air stream mixes with the spray jet downstream from the outlet openings.

The atomizing nozzle may comprise plural outlet openings for each of the air flow and the flow of liquid aerosol-forming substrate.

Commercially available atomizing nozzles usually use specific caps that induce an airflow management in the outlet of the nozzle that create a defined geometry of the spray jet. The cap of the atomizing nozzle may be designed or selected from existing models in the market, to create a geometry and size of the spray to match the geometry and size of the hot surface of the heating element.

The aerosol-generating system may be configured to define further secondary airflow paths in addition to the primary air flow path through the atomizing nozzle. The additional air flows may recombine before or after aerosol generation in order to achieve a desired air flow composition.

If secondary air inlets are provided, only a portion of the total air stream generated by the user upon inhalation is guided through the air channel of the atomizing nozzle. Preferably, about 30 to 90 percent, more preferably about 50 to 70 percent of the total air flow is guided through the air channel of the atomizing nozzle.

The spray jet generated by the atomization nozzle may be directed on a heater assembly. The heater assembly may comprise any type of known heating elements suitable for evaporating the liquid aerosol-forming substrate. The heater assembly may be substantially flat and may have any desired shape. The heater assembly may have a rectangular, polygonal, circular or oval shape with width and length dimensions of between 3 to 10 millimeters.

The heating element may comprise a thin, preferably substantially flat, electrically conductive material, such as a mesh of fibers, a conductive film, or an array of heating strips, suitable for receiving and heating an aerosol-forming substrate for use in an aerosol generating system.

The heating element may comprise a plurality of openings. For example, the heating element may comprise a mesh of fibers with interstices between them. The heating element may comprise a thin film or plate, optionally perforated with small holes. The heating element may comprise an array of narrow heating strips connected in series.

The heater assembly may comprise a heat resistive substrate and a heating element provided in the heat resistive substrate or on a surface of the heat resistive substrate. The heat resistive substrate of the heater assembly may be made from glass, heat resistive glass, ceramics, silicon, semiconductors, metals or metal alloys.

The heat resistive substrate may be substantially flat and may have any desired shape. The heat resistive substrate may have a rectangular, polygonal, circular or oval shape with for example width and length dimensions of between 3 to 10 millimeters. The thickness of the heat resistive substrate may range between 0.2 and 2.5 millimeters. In some embodiments the heat resistive substrate may be have a rectangular shape with a size of about 7 x 6 millimeters or 5 x 5 millimeters (L x W).

The heating element may be provided as a thin film coating provided to the surface of the heat resistive substrate. The heating element can be impregnated, deposited or printed the surface of the heat resistive substrate. The material of the thin film heating element can be any suitable material which has convenient electrical properties and a sufficiently high adherence to the heat resistive substrate.

The heating element may be provided within the volume of the heat resistive substrate, may be sandwiched between two elements of the heat resistive substrate or may be covered with a protective layer of heat resistive material.

In some embodiments the liquid aerosol-forming substrate may be delivered to a front side of the heat resistive substrate and the heating element may be provided on a backside of the heat resistive substrate.

The heater assembly may be spaced apart from the dispensing assembly. By providing the heater assembly spaced apart from the delivery assembly, the amount of liquid aerosol-forming substrate delivered to the heater assembly can be better controlled compared to a vaporizer having a tubing segment for carrying flow of the liquid aerosol-forming substrate from the delivery assembly to the heater assembly. Undesired capillary actions due to such tubing segment can be avoided. When passing the air gap, the delivered amount of the liquid aerosol-forming substrate will be transformed into a jet of droplets before hitting the surface of the heater assembly. Thus, a uniform distribution of the delivered amount of the liquid aerosol- forming substrate on the heater assembly can be enhanced in some examples, leading to better controllability and repeatability of generating an aerosol with a predetermined amount of vaporized aerosol-forming substrate per inhalation cycle.

The operating temperature of the heater assembly may be between 120 to 210 degrees Celsius, preferably between 150 to 180 degrees Celsius. The operation temperature of the device may be varied in some examples.

The flow rate of the liquid aerosol-forming substrate delivered through the atomizing nozzle is within 0.5 to 2 microliters per second. In embodiments comprising a micropump, the micropump may allow on-demand delivery of liquid aerosol-forming substrate at a flow rate of for example approximately 0.7 to 4.0 microliters per second for intervals of variable or constant duration. A pumped volume of one activation cycle may be around 0.5 microliters in micropumps working within a pumping frequency from 8 to 15 hertz. Preferably, the pump volume in each activation cycle, as a dose of liquid aerosol-forming substrate per puff, may be of around 0.4 to 0.5 microliters.

The aerosol-generating system may comprise a user operation detection unit for detecting an operation of a user to initiate aerosol generation. The user operation detection unit may be configured by a puff detection system, e.g. a puff sensor. Alternately or optionally, the user operation detection unit may be configured by an on-off button, e.g. an electrical switch.

The aerosol-generating system further comprises a control unit for controlling delivery of the liquid aerosol-forming substrate and for activating the heater assembly. Delivery of the liquid aerosol-forming substrate may be time delayed after activation of the heater assembly in response to a detected user operation. Upon activation by the user, such as using an on-off button or the puff sensor, the control unit may activate the heater assembly first, and then, after delay of around 0.3 to 1 seconds, preferably from 0.5 to 0.8 seconds, may activate the delivery device. The duration of activation may be fixed or may correspond to a user action like pressing the on-off button or puffing as e.g. detected by the user operation detection unit. Alternatively, the control unit may be adapted to activate the heater assembly and the liquid delivery simultaneously, depending on how fast the heater will react to achieve the desired temperature to produce the aerosol. Alternatively the heater may be activated at the start of the user experience and kept powered during the use of the device for any given time span.

Preferably, the aerosol-generating may comprise a device portion and a replaceable liquid storage portion. The device portion may comprise a power supply and the control unit. The power supply may be any type of electric power supply, typically a battery. The power supply for the delivery device may be different from the power supply of the mesh heating element or may be the same.

The power supply may be a form of charge storage device such as a capacitor, a super- capacitor or hyper-capacitor. The power supply may require recharging and may have a capacity that allows for the storage of enough energy for one or more user experiences; for example, the power supply may have sufficient capacity to allow for the continuous generation of aerosol for a period of around six minutes or for a period that is a multiple of six minutes. In another example, the power supply may have sufficient capacity to allow for a predetermined number of puffs or discrete activations of the vaporizer.

The aerosol-generating system may be an electrically operated system. Preferably, the aerosol-generating system is portable. The aerosol-generating system may have a size comparable to a conventional cigar or cigarette. The aerosol-generating system may have a total length between approximately 45 millimeters and approximately 160 millimeters. The aerosol-generating system may have an external diameter between approximately 7 millimeters and approximately 25 millimeters.

According to a third aspect of the present invention, there is provided a method for generating an aerosol, comprising the steps of providing a tubing section having an inlet end and an outlet end, the inlet end of the tubing section being configured to be connected to a liquid storage portion, providing an atomizing nozzle to the outlet end of the tubing section, and delivering a flow of liquid aerosol-forming substrate through the atomizing nozzle, wherein the atomizing nozzle comprises an air channel for establishing an air flow through the nozzle. The method further comprises the step of mixing the air flow with the flow of liquid aerosol- forming substrate to enhance atomization of the flow of liquid aerosol-forming substrate delivered through the atomizing nozzle.

The air flow through the atomizing nozzle is preferably generated by the user, when a puff is drawn at the mouthpiece of the aerosol-generating system, wherein at least a portion of the air flow between the air inlet and the mouthpiece is guided through the air channel of the atomizing nozzle.

By simultaneously utilising the inhaling action of the user for generation of an air stream through the atomizing nozzle, atomization of the liquid aerosol-forming substrate is substantially enhanced, requiring at the same time only very limited modification to existing aerosol-generating systems.

Features described in relation to one aspect may equally be applied to other aspects of the invention.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a side view of an embodiment of an aerosol-generating system including the atomizer of the present invention;

Fig. 2 shows an enlarged and detailed view of the the aerosol-generating system of Fig. 1 comprising the atomizer of the present invention.

Fig. 1 shows the components of an aerosol-generating system comprising the atomizing assembly of the present invention. The aerosol-generating system 10 comprises a housing 12, a power source 14, a control unit 16, a liquid storage portion 18, a tubing section 20, a micro pump 22, an atomizing nozzle 24 and a heater assembly 26. The housing comprises an air inlet 28 and a mouthpiece 30 at its proximal end.

The aerosol-generating system 10 may be activated by the user by manual operation of a power switch, or may automatically be activated by corresponding detection means when a user draws a puff. Upon detection of a puff, control unit 16 activates the micropump 22 and the heater assembly 26. Micro pump 22 delivers a predefined amount of liquid aerosol-forming substrate via atomizing nozzle 24 onto the heater assembly 26 where the liquid aerosol- forming substrate is vaporized and is delivered in the form of an aerosol to the user.

Atomizing nozzle 24 transforms the liquid aerosol-forming substrate into a spray jet 32 of small droplets. This atomization effect is supported by an air stream 34 established in an air flow channel 36 of atomizing nozzle 24. Fig. 2 is an enlarged view of the aerosol-generating system of Fig. 1 , depicting the air flow channel 36 and the fluid flow path 38 through the atomizing assembly in more detail. The liquid aerosol-forming substrate is conveyed in tubing 20 towards atomizing nozzle 24 provided at the outlet end 20a of the tubing section 20. Atomizing nozzle 24 has a central outlet 40 opening for creating a spray jet of small droplets of liquid aerosol-forming substrate. Atomizing nozzle 24 further comprises an air flow channel 36 that is in fluid communication with air inlet 28 and which terminates in a ringshaped outlet opening 42 arranged radially outwardly from and symmetrically with the central opening 40. The air stream 34 exiting the ringshaped outlet opening 42 mixes with the spray jet and enhances atomization of the small droplets of liquid aerosol-forming substrate.

Spray jet 32 is delivered onto heater assembly 26 where the aerosol-forming substrate is volatilized to form an aerosol. In the depicted embodiment, the complete air flow is guided through the air flow channel 36 of the atomizing nozzle 24. Alternatively, additional secondary air inlets may be provided in the housing of the aerosol-generating system. The side air flow entering the secondary air inlets may be mixed with the primary flow before or after volatilization by the heater assembly.

The exemplary embodiment described above illustrates but is not limiting. In view of the above discussed exemplary embodiment, other embodiments consistent with the above exemplary embodiment will now be apparent to one of ordinary skill in the art.