WO2024017796A1

WO2024017796A1 - Aerosol generating device, aerosol generating system, and method

Info

Publication number: WO2024017796A1
Application number: PCT/EP2023/069684
Authority: WO
Inventors: Hajime Fujita; Pier Paolo MONTICONE; Layth Sliman BOUCHUIGUIR
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2022-07-18
Filing date: 2023-07-14
Publication date: 2024-01-25
Anticipated expiration: 2025-01-18
Also published as: EP4557988A1; JP2025522694A

Abstract

There is provided an aerosol generating device for receiving an aerosol substrate and heating the aerosol substrate, the aerosol generating device comprising: a housing; and a heating circuit comprising: a heater assembly configured to heat the aerosol substrate when the aerosol substrate is received by the aerosol generating device, the heater assembly comprising at least one heater; and a fuse assembly provided in thermal communication with the heater assembly and electrically connected with the heater assembly, the fuse assembly comprising at least one resettable fuse, the fuse assembly being housed in the housing. There is also provided an aerosol generating system, and a method of operating an aerosol generating device or aerosol generating system.

Description

Aerosol generating device, aerosol generating system, and method

The present disclosure relates to an aerosol generating device, an aerosol generating system, and a method of operating an aerosol generating device or aerosol generating system.

Background

An aerosol generating device heats an aerosol substrate to generate aerosol for inhalation.

Referring to Figure 1 , a schematic configuration of a heating circuit of an aerosol generating device according to the prior art is shown. The heating circuit 1 comprises a power source 2, a control unit 4, a heater assembly 6 comprising a driver s and a heater 10, and a temperature sensor 12.

A closed loop control is provided, whereby the output of the temperature sensor 12 is provided as an input to the control unit 4 for controlling the temperature of the heater 10. In the event of failure or malfunction of the control unit 4 and/or temperature sensor 12, it may no longer be possible for the control unit 4 to control the heater assembly 6 in a safe and accurate manner. For example, failure or malfunction of the control unit 4 and/or temperature sensor 12 may lead to an uncontrollable rise in temperature of the heater 10.

In an example, failure or malfunction of the control unit 4 may result in the power source 2 continuing to provide power to the heater assembly 6, despite the heater 10 being above a target temperature or safe temperature. In another example, failure or malfunction of the temperature sensor 12 may result in the control unit 4 being provided with an inaccurate input, or no input. The control unit 4 may continue to cause operation of the heater assembly 6, despite the heater 10 being above a target temperature or safe temperature. This may lead to unexpected behaviour of the aerosol generating device. In further another example, failure or malfunction of the temperature sensor 12 and/or the control unit 4 may result in an over-discharged state of the power source 2.

Furthermore, the closed loop control requires hardware components, such as a temperature sensor 12, to function. As a result, the complexity, cost, and fragility of the aerosol generating device is sub-optimal. Power from the power source 2 is also required for function of the closed loop control. Thus, the power source 2 (which is also used by the heater assembly 6 to heat an aerosol substrate to generate aerosol) is depleted by the closed loop control.

In a further, separate, example of the prior art, an aerosol generating system is provided comprising an aerosol generating device and a consumable to be received by the aerosol generating device. A circuit diagram relating to this prior art example is illustrated in Figure 7. The consumable comprises an aerosol substrate. A resettable fuse is incorporated in the consumable. Once the consumable is consumed, the consumable, and thus the resettable fuse incorporated therein, is disposed of. The resettable fuse is thus wasted, despite potentially being still fully functional. Furthermore, the incorporation of the resettable fuse in the consumable increases the complexity and cost of consumables. Moreover, resettable fuses may be fragile components, which ultimately reduces the robustness of operation of the aerosol generating system and/or the consumable.

It is the object of the invention to overcome at least some of the above referenced problems.

Summary

According to a first aspect, there is provided an aerosol generating device for receiving an aerosol substrate and heating the aerosol substrate, the aerosol generating device comprising: a housing; and a heating circuit comprising: a heater assembly configured to heat the aerosol substrate when the aerosol substrate is received by the aerosol generating device, the heater assembly comprising at least one heater; and a fuse assembly provided in thermal communication with the heater assembly and electrically connected with the heater assembly, the fuse assembly comprising at least one resettable fuse, the fuse assembly being housed in the housing.

Such a construction is highly advantageous. In contrast to prior art configurations, wherein a closed loop control is provided by temperature sensor feedback to a control unit, the present construction does not require closed loop control for safe operation. For example, when the resettable fuse is heated above a cut-off temperature value, the provision of electrical power to the heater assembly may be terminated, without the need for feedback or correct operation of other control componentry (such as a control unit). That is, above a cut-off temperature, the resettable fuse behaves as an open circuit, thus terminating the provision of electrical power to the heater assembly. As a result, the components of the aerosol generating device are protected from overheating, and also the safety of the user is improved. Additionally, the power source is not depleted by the open loop control. It should be noted that such the resettable fuse can be combined with the closed loop control to further improve safety.

Furthermore, in contrast to prior art configurations wherein a resettable fuse is incorporated in a consumable, in the present construction the aerosol generating device itself comprises at least one resettable fuse. That is, the at least one resettable fuse is provided “device-side” (i.e., the aerosol generating device comprising at least one resettable fuse). In this way, waste is reduced as the resettable fuse is not disposed of once the aerosol substrate is consumed. Moreover, the present construction facilitates the use of more accurate and reliable (and thus more costly) resettable fuses, as the resettable fuse will not be disposed of once the aerosol substrate is consumed. The complexity and cost of consumables is thereby reduced.

Additionally, by the present construction, robustness of operation of an aerosol generating system comprising an aerosol generating device and aerosol substrate is improved. Successful operation of the system is not dependent on a correct connection of the aerosol generating device and aerosol substrate (or consumable comprising aerosol substrate), wherein the substrate or consumable comprises a resettable fuse. The likelihood of safe and successful operation of the aerosol generating system is improved by providing at least one resettable fuse at the device-side.

In one example, the aerosol generating device comprises a power source housed in the housing. In one example, the heater assembly is energized by the power source. In one example, the at least one heater is energized by the power source. In one example, the fuse assembly is electrically connected with the power source. In one example, the power source is a battery.

In this way, a power source can provide electrical power to the device components. In one example, the at least one resettable fuse has a cut-off temperature value which corresponds with a target temperature of the heater assembly during operation of the aerosol generating device.

In this way, once the target temperature of the heater assembly is reached, the resettable fuse will form an open circuit so that provision of electrical power to the heater assembly will be terminated. When the temperature of the heater assembly falls below the target temperature, the resettable fuse will form a closed circuit so that provision of electrical power to the heater assembly will be resumed. This allows the temperature of the heater assembly to be maintained at a target temperature or around the target temperature. In an example, the heater assembly has a plurality of target temperatures, and the at least one resettable fuse may have a cut-off temperature value corresponding with one of the target temperatures, so that that one of the target temperatures can be maintained for a period. As above, by such a construction, closed loop control (incorporating temperature sensors) is not required, and therefore safety, robustness, and accuracy of heating is improved.

In one example, the heater assembly comprises a plurality of heaters, each heater being provided with a resettable fuse in thermal communication with the respective heater.

In this way, each heater may be regulated independently. Individual temperature sensors for each heater are not required, and thus the present construction is simpler to manufacture and has reduced chance of failure compared with aerosol generating device of the prior art. By omitting individual temperature sensors, number of input terminals of a controller can be reduced. Thus, a small and inexpensive controller can be used.

In one example, each resettable fuse is electrically connected with each heater of the heater assembly. In one example, each resettable fuse is electrically connected with the power source. In one example, each resettable fuse is electrically connected with the power source and each heater.

In this way, a single heating circuit may be provided. The power source is able to provide electrical power to the heating circuit via each resettable fuse. In one example, each resettable fuse has a cut-off temperature value corresponding with a target temperature of the respective heater during operation of the aerosol generating device.

In this way, each heater may be regulated independently. Individual temperature sensors for each heater are not required, and thus the present construction is simpler to manufacture and has reduced chance of failure compared with aerosol generating device of the prior art. Furthermore, a heater may be required to provide heating to a specific target temperature, which may be different to the target temperature of one or more of the other heaters. By providing each resettable fuse having corresponding cutoff temperature values, the open loop control can control heating to a plurality of different target temperatures. By maintaining temperature of the respective heater to each target temperature, more advanced aerosol generation control can be realized. Such advanced aerosol generation control may lead to generation of a stable aerosol amount during operation.

In one example, at least one of the at least one resettable fuse is connected with a gate terminal of a field-effect transistor.

Continuous ON state of the transistor may cause short circuit of the transistor. In this way, when the at least one of the at least one resettable fuse reaches the cut-off temperature value, the field-effect transistor is also opened. This leads to an improvement in safety and efficiency of use of the power source. Instead of a field-effect transistor, other switching parts (e.g., a bipolar transistor or an insulated gate bipolar transistor) can be utilized. In case of a bipolar transistor, the at least one of resettable fuse is connected with a basis terminal of a bipolar transistor. In case of an insulated gate bipolar transistor (IGBT), the at least one of resettable fuse is connected with a gate terminal of an IGBT as well as a field-effect transistor.

In one example, the fuse assembly comprises a plurality of resettable fuses, and wherein the heating circuit further comprises: a multiplexer; and a control unit configured to control the multiplexer to selectively direct electrical power to one of the plurality of resettable fuses.

Advantageously, by providing a multiplexer, regulation of the temperature of the heater assembly is facilitated where the target temperature does not remain constant over the whole of operation. For example, the multiplexer can direct electrical power to the resettable fuse having a cut-off temperature value corresponding with a target temperature for a particular time period.

In one example, the control unit is configured to control the multiplexer to selectively direct electrical power to the heater assembly through one of the plurality of resettable fuses.

In this way, the electrical power is provided through the resettable fuse, which leads to improvements in safety and responsiveness of the open loop control.

If the resettable fuse, which is provided the electrical power by the multiplexer, is connected with a gate terminal of a field-effect transistor, the electrical power is provided to a field-effect transistor connected with the resettable fuse.

In one example, the control unit is configured to control the multiplexer to selectively direct electrical power to one of the plurality of resettable fuses which has a cut-off temperature value corresponding to a target temperature of the heater assembly for a period of operation of the aerosol generating device.

Advantageously, multiple target temperatures of the heater assembly can be safely maintained. The target temperature may be achieved or obtained by a single heater, or by a plurality of heaters. The period of operation could be a current or future period of operation, thus ensuring that the target temperature is always appropriate for operation of the aerosol generating device.

In one example, the control unit is configured to control the multiplexer to selectively direct electrical power to the heater assembly through one of the plurality of resettable fuses which has a cut-off temperature value corresponding to a target temperature of the heater assembly for a period of operation of the aerosol generating device.

In one example, the heater assembly has a plurality of target temperatures, and the control unit is configured to control the multiplexer to selectively direct electrical power to one of the plurality of resettable fuses corresponding to the target temperature of the heater assembly for a period of operation of the aerosol generating device.

In this way, the plurality of target temperatures can each be maintained by directing electrical power to the appropriate resettable fuse using the multiplexer. Safety across all operating temperatures of the heater assembly is thus improved. It will be appreciated that the plurality of target temperatures may be provided by a single heater controlled so as to provide a plurality of target temperatures, or a plurality of heaters each configured to have a target temperature (e.g., a preferred operating temperature, or a maximum safe operating temperature).

In one example, the heater assembly has a plurality of target temperatures, and the control unit is configured to control the multiplexer to selectively direct electrical power to the heating assembly through one of the plurality of resettable fuses corresponding to the target temperature of the heater assembly for a period of operation of the aerosol generating device.

In one example, the heater assembly comprises a plurality of heaters, each heater being provided with a resettable fuse in thermal communication with the respective heater, wherein the control unit is configured to control the multiplexer to selectively direct electrical power to one of the plurality of resettable fuses corresponding to the respective heater which is operational to achieve the target temperature of the heater assembly for a period of operation of the aerosol generating device. In this way, the appropriate resettable fuse which corresponds with the operational heater will provide the open loop control. Multiple target temperatures can thus be achieved and safely maintained during operation of the aerosol generating device.

In one example, the fuse assembly further comprises a non-resettable fuse.

Highly advantageously, the non-resettable fuse in the fuse assembly provides an additional degree of safety of the aerosol generating device. If the cut-off temperature value of the non-resettable fuse is reached, the non-resettable fuse will form an open circuit and will permanently prevent further provision of electrical power to the heating circuit. Unlike the resettable fuse, the non-resettable fuse will not reset if or when the temperature of the heater assembly falls below the cut-off temperature value. This is highly advantageous where the non-resettable fuse cut off temperature value is selected to be a temperature at which the aerosol generating device and components therein can no longer be considered safe. The aerosol generating device will cease to function when the cut-off temperature value of the non-resettable fuse is reached.

In one example, the non-resettable fuse has a cut-off temperature value that is higher than the cut-off temperature value of at least one of the at least one resettable fuse.

In this way, it is possible for the temperature to rise to the cut-off temperature value of the resettable fuse, such that the target temperature can be maintained, but exceeding this temperature (e.g., by an amount considered unsafe) can be prevented by the nonresettable fuse.

In one example, the non-resettable fuse has a cut-off temperature value that is higher than a highest target temperature of the heater assembly.

In this way, heating beyond (e.g., by an amount considered unsafe) a highest target temperature of the heater assembly can be prevented by the non-resettable fuse. That is, in this example, the non-resettable fuse will not form an open circuit until after the resettable fuse has formed an open circuit, but the non-resettable fuse will form an open circuit in the event that the non-resettable fuse does not prevent further increase in temperature of the heater assembly due to any unexpected failure.

In one example, the non-resettable fuse has a cut-off temperature value that is higher than the cut-off temperature value of each resettable fuse.

In this way, the non-resettable fuse forms an open circuit in the event of overheating of the aerosol generating device. Thus, the provision of further electrical power to the heating assembly may be prevented.

In one example, the fuse assembly is located inside or outside of the heater assembly.

By locating the fuse assembly inside the heater assembly, calibration of the fuse assembly to the temperatures within the heater assembly need not be required. That is, due to the close or direct contact of the fuse assembly with the heaters, the temperature at the heater directly corresponds with the temperature at the fuse assembly, and thus accurate and rapid activation at target temperatures can be facilitated.

Alternatively, by locating the fuse assembly outside of the heater assembly, space within the heater assembly is freed-up, and manufacture of the heater assembly and fuse assembly may be simplified. Nevertheless, accurate and rapid activation at target temperatures may still be provided by calibration (e.g., appropriate selection of cut-of temperatures) of the fuse assembly to correspond with the target temperature within the heater assembly.

According to a second aspect, there is provided an aerosol generating system comprising: an aerosol generating device according to the first aspect; and an aerosol substrate.

Highly advantageously, an aerosol generating system is provided wherein the fuse assembly comprising at least one resettable fuse is provided at the aerosol generating device (e.g., device-side), thus improving safety, and reducing cost and complexity. According to a third aspect, there is provided a method of operating an aerosol generating device comprising: receiving an aerosol substrate at the aerosol generating device; heating the aerosol substrate using a heating circuit comprising: a heater assembly configured to heat the aerosol substrate received by the aerosol generating device, the heater assembly comprising at least one heater; and a fuse assembly provided in thermal communication with the heater assembly and electrically connected with the heater assembly, the fuse assembly comprising at least one resettable fuse, the fuse assembly being housed in a housing of the aerosol generating device.

Such a construction is highly advantageous, in particular for the reasons provided above in relation to the first aspect.

Brief Description of the Drawings

Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a heating circuit of an aerosol generating device according to the prior art;

Figure 2 shows a cross-sectional view of an aerosol generating device;

Figure 3 shows a first schematic configuration of a heating circuit;

Figure 4 shows a second schematic configuration of a heating circuit;

Figure 5 shows a third schematic configuration of a heating circuit;

Figure 6 shows a fourth schematic configuration of a heating circuit;

Figure 7 shows a circuit diagram according to the prior art;

Figure 8 shows a circuit diagram corresponding with the first configuration as shown in Figure 3;

Figure 9 shows a circuit diagram corresponding with the second configuration as shown in Figure 4;

Figure 10 shows a circuit diagram corresponding with the third configuration as shown in Figure 5;

Figure 11 shows a circuit diagram corresponding with the fourth configuration as shown in Figure 6;

Figure 12 shows a circuit diagram;

Figure 13 shows a schematic aerosol generating system; and Figure 14 shows general methodology principles.

Detailed Description

Referring to Figure 2, a schematic cross-sectional view of an aerosol generating device 100 is shown. The aerosol generating device 100 is suitable for receiving an aerosol substrate 102. The aerosol generating device 100 is suitable for heating the aerosol substrate 102. For example, the aerosol generating device 100 may include a chamber 104 in which the aerosol substrate 102 is received.

The aerosol substrate 102 may form part of, or be, a consumable. The consumable may comprise the aerosol substrate 102. The consumable may comprise a body which houses the aerosol substrate 102.

The invention is not limited to the specific aerosol generating device 100 or aerosol substrate 102 described herein, provided the aerosol generating device 100 or aerosol substrate 102 are in accordance with the appended claims. That is, the description of the aerosol generating device 100 and aerosol substrate 102 is provided for illustrative purposes only. The skilled person will appreciate that alternative constructions of aerosol generating devices and consumables will be compatible with the present invention.

As used herein, the term aerosol substrate is a label used to mean a medium that generates an aerosol or vapour when heated. It may be synonymous with smokable material and aerosol generating medium. Aerosol substrate includes liquid or solid materials that provide volatilized components upon heating, typically in the form of vapor or an aerosol. Aerosol substrate may be a non-tobacco-containing material or a tobacco-containing material. Aerosol substrate may, for example, include one or more of tobacco per se, tobacco derivatives, expanded tobacco, reconstituted tobacco, tobacco extract, homogenized tobacco or tobacco substitutes. Aerosol substrate also may include other, non-tobacco, products, which, depending on the product, may or may not contain nicotine. Aerosol substrate may comprise one or more humectants, such as glycerol or propylene glycol. The aerosol generating device 100 comprises a housing 106. The housing 106 may be an outer casing or other structure for housing the components of the aerosol generating device 100.

The aerosol generating device 100 comprises a heating circuit 108. In an example, the heating circuit 108 is for heating the aerosol substrate 102.

The heating circuit 108 comprises a heater assembly 110. The heater assembly 110 is configured to heat the aerosol substrate 102 when the aerosol substrate 102 is received by the aerosol generating device 100.

The heater assembly 110 comprises at least one heater 112. In an example, the heater assembly 110 comprises a single heater 112. In a further example, the heater assembly 110 comprises a plurality of heaters 112.

In one example, the aerosol substrate 102 is a liquid and the at least one heater 112 comprises a heating element, such as a coil, a ceramic heater, a flat resistive heater, a mesh heater, a MEMS heater, induction heater or the like, configured to aerosolise the liquid for inhalation. A liquid delivery element or mechanism, such as a porous material, a capillary system, and/or valve, may transfer the liquid to the heating element, in use. In some examples, the aerosolised liquid may pass through a solid substrate within the aerosol generating device 100. In other examples, the aerosol substrate 102 may comprise a solid aerosol substrate.

In one example, the aerosol generating device 100 comprises a nebulizing engine, such as a vibrating mesh, to generate an aerosol from a liquid with heating thereof.

The heater assembly 110 may comprise a chamber or volume. The chamber may be suitable for receiving the aerosol substrate 102 therein. That is, the chamber of the heater assembly 110 may be the chamber 104 of the aerosol generating device 100. The chamber may provide, or define, an oven. The at least one heater 112 may be provided inside of (i.e. , within) the chamber, or outside of the chamber. That is, the at least one heater 112 may be provided inside of the oven, or outside of the oven.

The heating circuit 108 comprises a fuse assembly 114. The fuse assembly 114 may be located inside of or outside of the heater assembly 110. In an example, where the heater assembly 110 comprises a chamber suitable for receiving the aerosol substrate 102 therein, the fuse assembly 114 may be located inside of or outside of the chamber.

The fuse assembly 114 is provided in thermal communication with the heater assembly 110. In other words, the fuse assembly 114 is arranged to be acted upon by the heat from the heater assembly 110. That is, heat from the heater assembly 110 may cause changes in a property or state of the fuse assembly 114. Thermal communication need not require direct contact with the heater assembly 110. That is, in an example, the fuse assembly 114 may be proximal to, in the vicinity of, or located such that it is acted upon by the heat from, the heater assembly 110. The fuse assembly 114 may be calibrated in the location in which it is provided, such that direct contact is not necessary. Thermal communication by direct contact of the fuse assembly 114 with the heater assembly 110 may be advantageous in improving response time of the fuse assembly 114 and/or accuracy. That is, in an example, the fuse assembly 114 may be in direct contact with the heater assembly 110.

The fuse assembly 114 may be electrically connected with the heater assembly 110. In an example, the fuse assembly 114 is provided as a fuse assembly for the heater assembly 110. The fuse assembly 114 may dictate if electrical power may be provided to the heater assembly 110, or to a heater of the heater assembly 110.

The fuse assembly 114 comprises at least one resettable fuse 116. A resettable fuse may be referred to as a “resettable thermal fuse”. In general, any resettable fuse as described herein may be a polymeric positive temperature coefficient (PPTC) device. PPTC devices are well known in the art. PPTC devices may also be known as a multifuse or a polyfuse or a polyswitch. Below a cut-off temperature value, the resettable fuse 116 is in a conductive state, whereas at or above a cut-off temperature value the resettable fuse 116 is in a high resistance state. That is, below the cut-off temperature value the resettable fuse 116 behaves as a closed circuit, whereas at or above the cutoff temperature value the resettable fuse 116 behaves as an open circuit. The resettable fuse may transition from closed circuit to open circuit at the cut-off temperature value of the particular resettable fuse. The cut-off temperature value is a property specific to each resettable fuse. Selection of an appropriate resettable fuse for a particular application will be well understood by the skilled person. It will be appreciated that the resettable fuse may reset automatically, if or when the temperature falls below the cutoff temperature value.

The fuse assembly 114 is housed in the housing 106. In other words, the fuse assembly 114 comprising the resettable fuse 116 is provided at or in the aerosol generating device 100.

The aerosol generating device 100 may comprise a mouthpiece 118 through which a user draws on the aerosol generating device 100 to inhale generated aerosol. The mouthpiece 118 includes a vent or channel 120 that is connected to a region close to the aerosol substrate 102 for passage of any generated aerosol from the aerosol substrate 102, during use. For example, the channel 120 may extend between an opening in the mouthpiece 118 and the chamber 104 in which the aerosol substrate 102 is receivable. The mouthpiece 118 is arranged such it may be received in a user’s mouth in use. In other examples, a mouthpiece 118 is not required and a portion of the consumable (e.g., the body which houses the aerosol substrate 102) may protrude from the aerosol generating device 100.

The aerosol generating device 100 may comprise a control unit 122 (or control circuitry). The control unit 122 may be for electronic management of the aerosol generating device 100. The control unit 122 may include a PCB or the like (not shown). The control unit 122 may include a memory for storing instructions and/or data therein. The control unit 122 may be configured to control the heating circuit 108. In an example, the heating circuit 108 comprises the control unit 122. The control unit 122 may form part of the heating circuit 108. The control unit 122 may be connected to the heating circuit 108 in use.

The aerosol generating device 100 may comprise an activation input sensor 124. The activation input sensor 124 may be a button, a touchpad, or the like for sensing a user’s input, such as a tap or swipe. In other examples, the activation input sensor 124 comprises an aerosol substrate sensor configured to detect if an aerosol substrate 102 has been inserted into the aerosol generating device 100. Additionally, or alternatively, the user input may also comprise an inhalation action by a user.

The aerosol generating device 100 may comprise a puff sensor 126 (otherwise known as an inhalation sensor). The puff sensor 126 is configured to detect an inhalation action (or puff) by a user on the aerosol generating device 100. In one example, the puff sensor 126 comprises a microphone, a flow rate sensor or a mass flow sensor configured to an airflow within the chamber 104 and/or an airflow channel extending from the chamber 104 through the mouthpiece 118 to an inhalation outlet thereof, the airflow being associated with a user’s inhalation action. In other examples, the puff sensor 126 is configured to detect a change in pressure indicative of a beginning of an inhalation action on the aerosol generating device by the user. In this case, the puff sensor 126 may be located anywhere on the aerosol device 100 in which there would be a change in pressure due to an inhalation action of the user. In one example, the puff sensor 126 is located in the channel 120 between the chamber 104 and the mouthpiece 118 of the aerosol generating device 100. The puff sensor 126 may also detect the end of an inhalation action by the user. For example, the puff sensor 126 may be configured to detect a further change in pressure due to the end of an inhalation action of a user.

The control unit 122 may comprise a processor (e.g., a microcontroller unit (MCU) or a micro processing unit (MPU)). The control unit 122 may be configured to receive data relating to various sensors/inputs (such as the activation input sensor 124 and/or puff sensor 126) of the aerosol generating device 100.

The aerosol generating device 100 may include a power source 128. The power source may be a battery. The power source may supply the aerosol generating device 100 with electrical power providing a voltage in the range of 1 V and 4 V. In a preferred embodiment the voltage source is a lithium-ion secondary battery delivering a value of 3.7 V. Such a voltage source is particularly advantageous for a modern aerosol generating device in view of rechargeability.

The power source 128 may be housed in the housing 106. The power source 128 may be permanently located in the housing 106, or could be replaceable with another power source (for example, by use of a replacement batter or similar). The power source 128 may supply the heating circuit 108 with electrical power. The heater assembly 110 may be energized by the power source 128. The at least one heater 112 may be energized by the power source 128. The fuse assembly 114 may be electrically connected with the power source 128. The power source 128 may also be arranged to provide electrical power to any other electrical component of the aerosol generating device 100. In an example, the heating circuit 108 comprises the power source 128. In use, the power source 128 may supply the heating circuit 108 with electrical power. In an example, the power source 128 may already be provided in the aerosol generating device 100, and the heating circuit 108 connected to the power source 128 when the heating circuit 108 is in use.

Referring to Figure 3, a first configuration of the heating circuit 108 is schematically shown. The heating circuit 108 comprises the heater assembly 110 having a first heater 112, and the fuse assembly 114 having a first resettable fuse 116.

The heating circuit 108 further may comprise a driver 140. The driver 140 may be configured to drive the heater 112. The driver 140 may direct electrical power to the heater 112 through the first resettable fuse 116.

The heating circuit 108 further comprises the power source 128 and the control unit 122.

The first resettable fuse 116 has a cut-off temperature value which corresponds with a target temperature of the heater assembly 110 during operation of the aerosol generating device 100. In use, the control unit 122 controls the driver 140 to provide electrical power from the power source 128 to the heater 112. The electrical power is provided through the first resettable fuse 116. The heater 112 is controlled to provide heating to a target temperature of the heater assembly 110. Once the target temperature is reached, the first resettable fuse 116 cuts off further provision of electrical power to the heater assembly 110 by forming an open circuit. The heater assembly 110 is thus prevented from heating to a temperature above the target temperature.

Referring to Figure 4, a second configuration of the heating circuit 108 is schematically shown. The second configuration of the heating circuit 108 is identical to the first configuration described above in relation to Figure 3, apart from the following differences. In the second configuration of the heating circuit 108, the fuse assembly 114 comprises a resettable fuse 116 and a non-resettable fuse 150. Connection order of the resettable fuse 116 and the non-resettable fuse 150 can be inverted.

A non-resettable fuse is a single-use circuit protection device. A non-resettable fuse may be known as a “thermal fuse” or a “non-resettable thermal fuse”. In contrast to a resettable fuse, if the temperature of a non-resettable fuse exceeds a cut-off temperature value, an open circuit is permanently formed. The non-resettable fuse will not reform a closed circuit (e.g., return to a low resistance state) if or when the temperature falls below the cut-off temperature.

In use, the control unit 122 controls the driver 140 to provide electrical power from the power source 128 to the heater 112. The electrical power is provided through the resettable fuse 116 and the non-resettable use 150. The heater 112 is controlled to provide heating to a target temperature of the heater assembly 110. In the event that the resettable fuse 116 fails to prevent further provision of electrical power to the heater assembly 110, such that the temperature of the heater assembly 110 continues to rise beyond the target temperature, the non-resettable fuse 150 will form an open circuit such that the provision of electrical power to the heater assembly 110 is permanently terminated. It may then be necessary to replace the aerosol generating device 100. As an example, this is highly advantageous in protecting the safety of the user in the event of damage to insulation of the heater assembly 110.

The non-resettable fuse 150 may have a cut-off temperature value that is higher than the cut-off temperature value of at least one of the at least one resettable fuse 116. That is, the resettable fuse 116 will reach its cut-off temperature value before the nonresettable fuse 150. In the event that the heater assembly 110 continues to heat beyond the target temperature, the non-resettable fuse 150 will form an open circuit as its cutoff temperature value is higher than that of the resettable fuse 150.

Referring to Figure 5, a third configuration of the heating circuit 108 is schematically shown. The third configuration is identical to the second configuration described above in relation to Figure 3, apart from the following differences. In the third configuration of the heating circuit 108, the fuse assembly 114 comprises a plurality of resettable fuses 116a, 116b, and the heater assembly 110 comprises a plurality of heaters 112a, 112b. The resettable fuses 116a, 116b may be referred to as a first resettable fuse 116a and a second resettable fuse 116b. The plurality of heaters 112a, 112b may be referred to as a first heater 112a and a second heater 112b.

Each heater 112a, 112b may be provided with a resettable fuse 116a, 116b in thermal communication with the respective heater 112a, 112b. That is, in this example, a resettable fuse is associated with each heater. The first resettable fuse 116a is associated with the first heater 112a, and the second resettable fuse 116b is associated with the second heater 112b. In this way, each heater 112, 112b can be regulated independently, and operated at different target temperatures.

Each resettable fuse 116a, 116b has a cut-off temperature value corresponding with a target temperature of the respective heater 112a, 112b during operation of the aerosol generating device. In an example, the first heater 112a may be provided with electrical power to heat to a first target temperature, at which the first resettable fuse 116a forms an open circuit. The second heater 112b may then be provided with electrical power to heat from the first target temperature to a second target temperature, at which the second resettable fuse 116b forms an open circuit.

A time period of providing of electrical power to the first heater 112a (e.g. a time period in which the heater is provided with electrical power, which may be an “ON” condition of the heater) may differ with a time period of providing of electrical power to the second heater 112b. In other example, a time period of providing of electrical power to the first heater 112a may be partially or wholly overlapped with a time period of providing of electrical power to the second heater 112b. In further other example, each electrical power to the first heater 112a and the second heater 112b are intermittently supplied so that both time periods do not overlap. By preventing of providing electrical power to the first heater 112a and the second heater 112b at same time, high rate discharging of the power source 128 can be moderated.

The fuse assembly 114 of the third configuration may comprise one or more nonresettable fuses 150. In an example, the fuse assembly 114 may comprise a single nonresettable fuse 150. The non-resettable fuse 150 may have a cut-off temperature value that is higher than a highest target temperature (e.g., both the first target temperature and second target temperature) of the heater assembly 110. That is, the non-resettable fuse 150 may be located such that it is exposed to the highest target temperature in the aerosol generating device 100, whereby in the event that the heater assembly 110 continues to heat beyond the highest target temperature, the non-resettable fuse 150 will form an open circuit. In this example, the non-resettable fuse 150 is connected at upstream of each resettable fuse 116a, 116b. Alternatively, the non-resettable fuse 150 is connected at downstream of the first resettable fuse 116a and/or the second resettable fuse 116b. If the non-resettable fuse 150 is connected at downstream of each resettable fuse 116a, 116b, multiple the non-resettable fuse 150 are provided. Referring to Figure 6, a fourth configuration of the heating circuit 108 is schematically shown. The fourth configuration is identical to the third configuration described above in relation to Figure 5, apart from the following differences. In the fourth configuration of the heating circuit 108, the heater assembly 110 comprises a single heater 112 operable at a plurality of target temperatures. The plurality of target temperatures may be suitable for different periods of operation, or stages, in an aerosol generating process. The heating circuit 108 further comprises a multiplexer 160. The multiplexer may otherwise be referred to as a power multiplexer. The multiplexer 160 operates as a switch, controlled by the control unit 122, to direct electrical power to a selected resettable fuse 116a, 116b. The control unit 122 is configured to control the multiplexer 160 to selectively direct electrical power to one of the plurality of resettable fuses 116a, 116.

In use, the control unit 122 is configured to control the multiplexer 160 to selectively direct electrical power to one of the plurality of resettable fuses 116a, 116b which has a cut-off temperature value corresponding to a target temperature of the heater assembly 110 for a period of operation of the aerosol generating device 100.

For example, the target temperature of the heater assembly 110 for a first period of operation may be a first target temperature, and the control unit 122 is configured to control the multiplexer 160 to selectively direct electrical power to the first resettable fuse 116a which has a cut-off temperature value corresponding to the first target temperature. Once the first target temperature is reached, the first resettable fuse 116a forms an open circuit, such that no electrical power is further provided to the heater 112.

Subsequently, the target temperature of the heater assembly 110 for a second period of operation may be a second target temperature (which may be higher or lower than the first target temperature), and the control unit 122 is configured to control the multiplexer 160 to selectively direct electrical power to the second resettable fuse 116b which has a cut-off temperature value corresponding the second target temperature. Once the second target temperature is reached, the second resettable fuse 116b forms an open circuit, such that no electrical power is further provided to the heater 112.

In general, the control unit 122 controls the multiplexer 160 to direct electrical power to the resettable fuse 116a, 116b corresponding to the target temperature for a particular period of operation of the aerosol generating device 100. Instead of the multiplexer, single-pole-multi-throw (SPMT) switch (e.g., single-pole- double-throw (SPDT) switch) can be utilised.

Whilst not illustrated in Figure 6, the heater assembly 110 may comprise a plurality of heaters 112a, 112b, each heater being provided with a resettable fuse 116a, 116b in thermal communication with the respective heater 112a, 112b. The resettable fuses 116a, 116b may be referred to as a first resettable fuse 116a and a second resettable fuse 116b. The plurality of heaters 112a, 112b may be referred to as a first heater 112a and a second heater 112b. The control unit 122 is configured to control the multiplexer 160 to selectively direct electrical power to one of the plurality of resettable fuses 116a, 116b corresponding to the respective heater which is operational to achieve the target temperature of the heater assembly 110 for a period of operation of the aerosol generating device 100.

For example, the target temperature of the heater assembly 110 for a first period of operation may be a first target temperature to be provided by the first heater 112a. That is, the first heater 112a is to be operated to provide the first target temperature. The control unit 122 is configured to control the multiplexer 160 to selectively direct electrical power to the first resettable fuse 116a corresponding to the first heater 112a which is operated to achieve the first target temperature for the first period of operation of the aerosol generating device 100.

Subsequently, the target temperature of the heater assembly 110 for a second period of operation may be a second target temperature to be provided by the second heater 112b. That is, the second heater 112b is to be operated to provide the second target temperature. The control unit 122 is configured to control the multiplexer 160 to selectively direct electrical power to the second resettable fuse 116b corresponding to the second heater 112b which is operated to achieve the second target temperature for the second period of operation of the aerosol generating device 100.

Exemplary circuit diagrams are illustrated and described in relation to Figures 7 to 12.

Referring to Figure 7, a prior art circuit diagram of a heating circuit 708 is shown. A consumable, or cartmizer (cartridge and atomizer), is indicated schematically at 700. The consumable 700 comprises a heater 712 and a resettable fuse 716. That is, the consumable 700 comprises the resettable fuse 716. The consumable 700 is connected to an aerosol generating device to form a heating circuit 708.

Referring to Figure 8, a circuit diagram of a heating circuit 108 according to the present invention and corresponding to the first configuration described above in relation to Figure 3 is shown. The heating circuit 108 comprises a heater assembly 110 comprising a heater 112. The heating circuit 108 comprises a resettable fuse 116. In contrast to the prior art heating circuit, the resettable fuse 116 is provided at the aerosol generating device 100, and is not part of a consumable. From Figure 8 to 12, MCU is illustrated as an example of the control unit 122, a combination of Gate Driver and p-channel MOSFET is illustrated as an example of the driver 140. LDO (Low Drop-out regulator) receives output of the power supply 128, and outputs converted electrical power to the MCU and the Gate Driver. Alternatively, the Gate Driver can be omitted. In this alternative embodiment, p-channel MOSFET behaves as the driver 140, and MCU is configured to directly control p-channel MOSFET. Alternatively or additionally, n- channel MOSFET can be provided between a negative pole of the heater assembly 110 and GND, as component of the driver 140.

Referring to Figure 9, a circuit diagram of a heating circuit 108 according to the present invention and corresponding to the second configuration described above in relation to Figure 4 is shown. The heating circuit 108 comprises a heater assembly 110 comprising a heater 112. The heating circuit 108 comprises a resettable fuse 116. The heating circuit 108 may also comprise a non-resettable fuse 150. Again, in contrast to the prior art heating circuit, the resettable fuse 116 is provided at the aerosol generating device 100, and is not part of a consumable. Connection order of the resettable fuse 116 and the non-resettable fuse 150 can be inverted.

Referring to Figure 10, a circuit diagram of a heating circuit 108 according to the present invention and corresponding to the third configuration described above in relation to Figure 5 is shown. The heating circuit 108 comprises a plurality of resettable fuses 116a, 116b. The heating circuit 108 comprises a heater assembly 110 comprising a plurality of heaters 112a, 112b. The heating circuit may also comprise a non-resettable fuse 150. Again, in contrast to the prior art heating circuit, the resettable fuses 116 are provided at the aerosol generating device 100 and are not part of a consumable. Referring to Figure 11 , a circuit diagram of a heating circuit 108 according to the present invention and corresponding to the fourth configuration described above in relation to Figure 6 is shown. The heating circuit 108 comprises a plurality of resettable fuses, in this example, four resettable fuses 116a, 116b, 116c, 116d. The heating circuit 108 comprises a heater assembly 110 comprising a single heater 112. However, in other examples the heating circuit 108 may comprise a plurality of heaters. The heating circuit 108 comprises a multiplexer 160. The heating circuit may also comprise a nonresettable fuse 150. Again, in contrast to the prior art heating circuit, the resettable fuses 116 are provided at the aerosol generating device 100 and are not part of a consumable. It should be noted that number of the resettable fuses 160 in Figure 6 and 11 is just example. The skilled person will appreciate that alternative number of the resettable fuses 160 by using a multiplexer or a single-pole-multi-throw switch which has appropriate the number of output pins.

Referring to Figure 12, a circuit diagram of a heating circuit 108 according to the present invention is shown. The heating circuit 108 comprises a heater assembly 110 comprising a single heater 112. However, in other examples the heating circuit 108 may comprise a plurality of heaters. The heating circuit 108 comprises a resettable fuse 116. Again, in contrast to the prior art heating circuit, the resettable fuse 116 is provided at the aerosol generating device 100 and is not part of a consumable. The resettable fuse is connected with a gate terminal of a field-effect transistor (e.g., MOSFET), indicated generally at 170. Once the resettable fuse 116 forms open circuit, electrical potential of a gate terminal of a field-effect transistor is maintained high level by a pull-up resistor. Thus, a voltage across a source terminal and a gate terminal of a field-effect transistor falls below threshold value, and a field-effect transistor is opened.

Alternatively or additionally, n-channel MOSFET connected between a negative pole of the heater assembly 110 and GND can be provided, such the n-channel MOSFET has the resettable fuse 116 connected between the Gate Driver and a gate terminal of the n-channel MOSFET. A gate terminal of the n-channel MOSFET is preferably connected with GND via pull-down resistor.

A heating circuit 108 shown in Figure 12 can be combined with from the first configuration to the fourth configuration. When a heating circuit 108 shown in Figure 12 is combined with the fourth configuration, each the resettable fuses 116 is connected to a gate terminal of each MOSFETs, and the multiplexer 160 directs electrical power to any one of a source terminal of MOSFETs.

Referring to Figure 13, a schematic of an aerosol generating system 800 is shown. The aerosol generating system 800 comprises an aerosol generating device 100 and an aerosol substrate 102. The aerosol generating device 100 is in accordance with any of the examples described above, and may comprise any of the features thereof. The aerosol generating device 100 is for receiving the aerosol substrate 102 and heating the aerosol substrate 102. The aerosol substrate may be received by the aerosol generating device 100.

Referring to Figure 14, a method of operating an aerosol generating device 100 or aerosol generating system 800 is shown. Step 910 comprises receiving an aerosol substrate 102 at the aerosol generating device 100. Step 920 comprises heating the aerosol substrate 102 using a heating circuit 108 comprising: a heater assembly 110 configured to heat the aerosol substrate 102 received by the aerosol generating device 100, the heater assembly 110 comprising at least one heater 112; and a fuse assembly 114 provided in thermal communication with the heater assembly 110 and electrically connected with the heater assembly 110, the fuse assembly 114 comprising at least one resettable fuse 116, the fuse assembly 114 being housed in a housing 106 of the aerosol generating device 100. The method may comprise any of the features or functionality of the aerosol generating device 100 or aerosol generating system 800 described above.

Although preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

Claims

CLAIMS An aerosol generating device (100) for receiving an aerosol substrate (102) and heating the aerosol substrate (102), the aerosol generating device (100) comprising: a housing (106); and a heating circuit (108) comprising: a heater assembly (110) configured to heat the aerosol substrate (102) when the aerosol substrate (102) is received by the aerosol generating device (100), the heater assembly comprising at least one heater (112); and a fuse assembly (114) provided in thermal communication with the heater assembly (110) and electrically connected with the heater assembly (110), the fuse assembly (114) comprising at least one resettable fuse (116), the fuse assembly (114) being housed in the housing (106). The aerosol generating device (100) as claimed in claim 1 , wherein the at least one resettable fuse (116) has a cut-off temperature value which corresponds with a target temperature of the heater assembly (110) during operation of the aerosol generating device (100). The aerosol generating device (100) as claimed in claim 1 or claim 2, wherein the heater assembly (110) comprises a plurality of heaters (112a, 112b), each heater being provided with a resettable fuse (116a, 116b) in thermal communication with the respective heater. The aerosol generating device (100) as claimed in claim 3, wherein each resettable fuse (116a, 116b) has a cut-off temperature value corresponding with a target temperature of the respective heater (112a, 112b) during operation of the aerosol generating device (100). The aerosol generating device (100) as claimed in any one of claims 1 to 4, wherein at least one of the at least one resettable fuse (116) is connected with a gate terminal of a field-effect transistor (170). The aerosol generating device (100) as claimed in any one of the preceding claims, wherein the fuse assembly (114) comprises a plurality of resettable fuses (116a, 116b), and wherein the heating circuit further comprises: a multiplexer (160); and a control unit (122) configured to control the multiplexer to selectively direct electrical power to one of the plurality of resettable fuses (116a, 116b). The aerosol generating device (100) as claimed in claim 6, wherein the control unit (122) is configured to control the multiplexer (160) to selectively direct electrical power to one of the plurality of resettable fuses (116a, 116b) which has a cut-off temperature value corresponding to a target temperature of the heater assembly (110) for a period of operation of the aerosol generating device (100). The aerosol generating device (100) as claimed in either of claim 6 or claim 7, wherein the heater assembly (110) has a plurality of target temperatures, and the control unit is configured to control the multiplexer (160) to selectively direct electrical power to one of the plurality of resettable fuses (116a, 116b) corresponding to the target temperature of the heater assembly (110) for a period of operation of the aerosol generating device (100). The aerosol generating device (100) as claimed in any one of claims 6 to 8, when dependent directly or indirectly on claim 3, wherein the control unit (122) is configured to control the multiplexer (160) to selectively direct electrical power to one of the plurality of resettable fuses (116a, 116b) corresponding to the respective heater (112a, 112b) which is operational to achieve the target temperature of the heater assembly (110) for a period of operation of the aerosol generating device (100). The aerosol generating device (100) as claimed in any one of the preceding claims, wherein the fuse assembly (114) further comprises a non-resettable fuse (150). The aerosol generating device (100) as claimed in claim 10, wherein the nonresettable fuse (150) has a cut-off temperature value that is higher than the cutoff temperature value of at least one of the at least one resettable fuse (116a, 116b). 12. The aerosol generating device (100) as claimed in any either of claim 10 or claim 11 , wherein the non-resettable fuse (150) has a cut-off temperature value that is higher than a highest target temperature of the heater assembly (110).

13. The aerosol generating device (100) as claimed in any one of the preceding claims, wherein the fuse assembly (114) is located inside or outside of the heater assembly (110).

14. An aerosol generating system (800) comprising: the aerosol generating device (100) according to any one of the preceding claims; and an aerosol substrate (102).

15. A method of operating an aerosol generating device (100) or aerosol generating system comprising: receiving an aerosol substrate (102) at the aerosol generating device (100); heating the aerosol substrate (102) using a heating circuit (108) comprising: a heater assembly (110) configured to heat the aerosol substrate (102) received by the aerosol generating device (100), the heater assembly (110) comprising at least one heater (112); and a fuse assembly (114) provided in thermal communication with the heater assembly (110) and electrically connected with the heater assembly (110), the fuse assembly (114) comprising at least one resettable fuse (116), the fuse assembly (114) being housed in a housing (106) of the aerosol generating device (100).