The invention relates to an aerosol-generating system for generating an inhalable aerosol. The system comprises an electric heater for vaporizing an aerosol-generating substance and a battery for powering the electric heater.

In conventional aerosol-generating systems such as e-cigarettes, an aerosol-generating substance such as an e-liquid is vaporized by means of an electric heater. The electric heater is powered by a battery. The battery can be charged for example by means of a USB cable and a corresponding USB port in the system. However, batteries cause potential problems, since a battery may be burned or cause a sudden increase of internal pressure. This may occur due to a high battery temperature. A high battery temperature may break the internal cells of the battery leading to a short circuit. The temperature of the battery may increase during charging of the battery, because of the heat generated by the electric power transferred into the battery, but also sometimes because of external elements close to the battery like electronic components. In a high temperature condition, more and more heat can be generated by the battery in a "thermal runaway" condition. A high temperature can also occur due to overcharging of the battery, i.e. when more charging current is provided to the battery than the battery is designed for. Overvoltage, overcharge current, overdischarge current, overdischarge voltage, recharging a battery completely depleted, or charging or discharging a battery at too high or too low ambient temperatures may also lead to high temperatures of the battery with a possibility of internal damage of the battery.

An internally damaged battery that is close to the face of a user, who is puffing, may put the user in an adverse situation. The object of the present invention therefore is to prevent an adverse situation of a user using an aerosol-generating system.

This problem is solved by the subject-matter of the independent claims. In this regard, the invention proposes an aerosol-generating system for generating an inhalable aerosol. The system comprises an electric heater for vaporizing an aerosol-forming substance and a battery for powering the electric heater. The system further comprises a control unit, wherein the control unit is configured to detect if the electric heater is operated and if the battery is on charge. The control unit is further configured to prevent charging of the battery, when the electric heater is operated, and to prevent the electric heater from operating, when the battery is on charge.

Providing a control unit which only allows charging the battery or operating the heater ensures that the user cannot puff during charging of the battery. Also, the user cannot charge the battery during puffing. As described above, the possibility of the battery being internally damaged is highest during charging of the battery due to an increased temperature during the time of charging the battery. Also, using the system, i.e. puffing, may additionally increase the temperature of the battery due to a power transfer from the battery towards the heater and also due to the heater temperature. This additional heat generation during operating of the heater is prevented by the invention during charging. Thus, the possibility of the battery being internally damaged is reduced. Furthermore, if the battery is internally damaged, an uncomfortable situation on the user can be prevented, since the user is not puffing during charging.

According to an aspect of the invention, the control unit may detect a charging of the battery when a USB cable is connected to a USB port of the system. The detection of a connection of a USB cable to a USB port of the system for charging the battery may be facilitated by any conventional means.

Any suitable charging of the battery may be detected by the control unit. For example, a USB type connector may be employed for charging the battery such as a Micro USB or USB type C connector. A customized connector or cable may be employed that interface a USB connector. In this case, a USB cable may be plugged onto the customized connector or cable. The other side of the customized connector or cable may connect the aerosol-generating system. A customized charger may also be employed that is directly connected on one side onto a USB port of for example an AC adaptor or a PC and on the other side onto the aerosol- generating system with or without cable between charger and system. A customized AC adaptor may also be employed. In this case, a customized AC adaptor with or without a customized cable is employed. The aerosol-generating system may be plugged to the AC adaptor or to the cable connected to the AC adaptor. Any proprietary charging system may be employed. Also, wireless charging such as inductive charging of the battery may be employed and detected by the control unit. For detecting the charging of the battery, a conventional sensor may be employed.

The control unit may detect that a USB cable is connected to the USB port of the system or that the battery is on charge by other means, and, in this instance, prevent the heater from operating. The control unit prevents the heater from heating even if the puff of a user is detected for as long as the battery is on charge. In this regard, the system may comprise a puff sensor such as an airflow sensor which measures the airflow rate or an on-off button. Also, the puff sensor may be configured as a pressure sensor measuring the pressure of the air inside the system which is drawn through an airflow path of the system by the user during a puff. Normally, the control unit activates the heater upon detection of a puff of a user by this sensor. However, if the control unit has detected that the battery is on charge, the control unit prevents the activation of the heater.

The control unit may be configured to detect if a replaceable cartridge for receiving aerosol-forming substance is connected. The control unit may further be configured to prevent charging of the battery, when the control unit detects that such a cartridge is present. The cartridge may be adapted for storing the aerosol-forming substrate to be supplied to the electric heater. The cartridge may be configured as a container or a reservoir for storing liquid aerosol-forming substrate. The cartridge may be capable of being coupled by a respective coupling hermetically sealed against surrounding atmosphere such as a self-healing pierceable membrane. The cartridge may be configured as a replaceable cartridge such as a tank or container. The electric heater may be comprised in the cartridge. In this case, the control unit and the battery are enclosed in a device portion and the replaceable cartridge may be configured connectable to the device portion. The electric heater may also be encompassed in a housing together with the battery and the control unit such that the replaceable cartridge is connectable to the housing and only comprises the aerosol-forming substrate.

The coupling of such a cartridge may indicate that the user wants to puff and thus activate the heater. Consequently, the control unit may prevent charging of the battery upon detection that the cartridge is coupled to the device portion or housing.

The control unit may further be configured to detect the initiation of the electric heater and prevents the charging of the battery when an initiation of the electric heater is detected.

As described above, a puff may be detected by means of a sensor. The sensor thus detects the initiation of the electric heater. The sensor may be provided as an on-off button, an airflow sensor or a pressure sensor. The electric heater may be initiated by pressing an on-off button for the duration of the user's puff. Also, the sensor may be provided as an airflow sensor measuring the airflow rate, which is a parameter characterizing the amount of air that is drawn through an airflow path of the system for a time. Depending upon the detected airflow rate, a puff may be detected. In this regard, a puff may be detected, when the airflow exceeds a predetermined threshold. In case the sensor is provided as a pressure sensor, a pressure difference or a pressure drop between the pressure of ambient air outside of the system and of the air which is drawn through the system by the user may be measured by the sensor. The pressure of the air may be detected at an air inlet of the system, preferably a semi-open inlet, a mouth end of the system, an aerosol formation chamber or any other passage or chamber within the system, through which the air flows. When the user draws on the system, a negative pressure or vacuum is created inside the system, wherein the negative pressure may be detected by the pressure sensor.

The control unit may be connected to the sensor to receive the sensor input. When an initiation of the heater is detected by the sensor, the control unit detects whether the battery is at this moment on charge or not. If the battery is on charge, the control unit prevents the operation of the heater. If, however, the control unit detects that the battery is not on charge, the control unit allows an activation of the heater and, at the same time, prevents the charging of the system. For example, if a USB-cable is plugged into a USB-port of the system during a puff of a user, a charging of the battery is prevented as long as the puff of the user lasts. Only after the puff of the user has ended, a charging of the battery is allowed by the control unit. In this case, a further puff of the user will not result in an activation of the electric heater, since charging of the system is now detected by the control unit and, thus, a subsequent operation of the heater is prevented by the control unit for as long as the battery is on charge.

Alternatively or additionally to a puff sensor as described above, the system may comprise a temperature sensor for detecting the initiation of the electric heater. Also, a current sensor may be employed for detecting the initiation of the electric heater. These sensors may be used to detect that the user wants to activate the heater. The control unit may only allow the activation of the heater if no charging is detected. If the heater detects that the battery is on charge, an activation of the electric heater is prevented.

A charging sensor may be employed for detecting the charging of the battery. This sensor is connected with the control unit so that the control unit may prevent the electric heater from being activated during charging. Generally, charging is detected by detecting the presence of a voltage on one pin of the aerosol-generating system. To this end, electric components such as a microcontroller or a charger IC may be employed. A BQ24250 2A Single Input l2C/Standalone Switch-Mode Li-Ion Battery Charger from Texas Instruments may be used for this purpose.

All of the above-mentioned sensors may be connected to the control unit so that the output of these sensors may be collected and processed by the control unit. Also, the sensor may be an integral part of the control unit.

The control unit may be part of electric circuitry and may comprise a microprocessor, which may be a programmable microprocessor. The electric circuitry may comprise further electric components. The control unit may be configured to regulate a supply of electric power to the electric heater. Electric power may be supplied to the electric heater continuously following activation of the electric heater or may only be supplied at times, such as on a puff-by-puff basis. The power may be supplied to the electric heater in the form of pulses of electrical current. The control unit may be configured to monitor the electrical resistance of the electric heater, and preferably control the supply of electric power to the electric heater dependent on the electrical resistance of the electric heater.

The battery may have a capacity that allows for the storage of enough energy for one or more puffs of the user. For example, the battery may have sufficient capacity to allow for a continuous generation of aerosol for a period of around 6 minutes or for a period that is a multiple of 6 minutes. In another example, the battery may have sufficient capacity to allow for a predetermined number of puffs or discrete activations of the electric heater. The battery as well as the control unit and also the electric heater may be arranged in a housing of the aerosol-generating system. For allowing ambient air to enter the system, a wall of the housing, preferably a wall opposite the electric heater such as a bottom wall, may be provided with at least one semi-open inlet. The semi-open inlet preferably allows air to enter the system, but no air or liquid to leave the system through the semi-open inlet. A semi-open inlet may for example be a semi-permeable membrane, permeable in one direction only for air, but being air- and liquid-tight in the opposite direction. A semi-open inlet may for example also be a one-way valve. Preferably, the semi-open inlet allows air to pass through the inlet only if specific conditions are met, for example a minimum depression in the system or a volume of air passing through the valve or membrane.

The aerosol-forming substrate for generating an aerosol is a substrate capable of releasing volatile compounds that can form an aerosol. As described above, an aerosol-forming substrate may be contained in a cartridge, which is preferably provided as a replaceable cartridge. The aerosol-forming substrate may also be arranged within the housing of the system in a tank. The tank may be a refillable tank. The volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may comprise plant-based material. The aerosol- forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds, which are released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may alternatively comprise a non-tobacco-containing material. The aerosol-forming substrate may comprise homogenised plant-based material.

The aerosol-forming substrate may comprise at least one aerosol-former. An aerosol- former is any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and that is substantially resistant to thermal degradation at the temperature of operation of the system. The liquid aerosol-forming substrate may comprise other additives and ingredients, such as flavourants. The liquid aerosol-forming substrate may comprise water, solvents, ethanol, plant extracts and natural or artificial flavours. The liquid aerosol-forming substrate may comprise nicotine.

The heater may exemplarily be a heated coil, a heated capillary, a heated mesh or a heated metal plate. The heater may exemplarily be a resistive heater which receives electrical power and transforms at least part of the received electrical power into heat energy. The heater may comprise only a single heating element or a plurality of heating elements. The temperature of the heating element or elements is preferably controlled by the control unit.

In any of the embodiments described above, the heater preferably comprises an electrically resistive material. The invention also proposes a method for controlling an aerosol-generating system. The method comprises the step of providing an aerosol-generating system comprising an electric heater for vaporizing an aerosol-generating substance, a battery for powering the electric heater, and a control unit. The method further comprises the step of detecting, by the control unit, if the electric heater is operated and if the battery is on charge. The method further comprises the step of preventing, by the control unit, charging of the battery, when the electric heater is operated and preventing, by the control unit, the electric heater from operating, when the battery is on charge.

The terms "on charge" and "operated" each define a state of the battery respectively the electric heater. From the initiation of the charging of the battery to the end of the charging of the battery, the battery is in a charging state, i.e. "on charge". From the initiation of a heating of the electric heater to the end of the active heating of the electric heater, the electric heater is in an operation state, i.e. "operated".

The invention will be described in the following in more detail referring to the attached figures.

Figure 1 shows an illustrative sectional view of the aerosol-generating system with a charging cable.

Figure 2 shows an illustrative sectional view of an aerosol-generating system with a cartridge.

In Figure 1 , an aerosol-generating system is depicted. The components of the system are arranged within a housing 1 of the system. These components are a control unit 2, a battery 3, and an electric heater 4. The aerosol-generating system may comprise further components, which are not depicted in Figure 1 .

The battery 3 stores electric power, which may be supplied to the electric heater 4 to heat the electric heater. The supply of the electric power from the battery 3 to the electric heater 4 is controlled by the control unit 2. Thus, the control unit 2 is provided to activate the electric heater 4, in which case the electric heater 4 is heated by means of electric power from the battery 3.

If a user draws on a mouth end 5 of the system, a sensor such as an airflow sensor (not shown) detects the puff of the user and the electric heater 4 is activated by means of the control unit 2. However, the control unit 2 only allows the activation of the electric heater 4, when the battery 3 is not on charge.

Figure 1 shows the system in a state, in which a charging cable 6 is connected to the system for charging the battery 3. The charging cable 6 is a USB cable connected to a respective USB port of the system. Upon detection that a charging cable 6 is connected to the system for charging the battery 3, the control unit 2 prevents an activation of the electric heater 4, even if a user draws on the mouth piece 5.

However, if a user tries to activate the electric heater 4 by drawing on the mouth end 5 before the charging cable 6 is connected to the system, the subsequent charging of the battery 3 is prevented by the control unit 2 if the charging cable 6 is connected to the USB-port after the activation of the electric heater 4 during a puff of the user.

Figure 2 shows a further embodiment, in which a cartridge 7 is connected to the system for supplying an aerosol-forming substrate by conventional means to the system for generating an aerosol. The cartridge 7 comprises a tank 8 for storing the aerosol-forming substrate. The cartridge 7 may be removably connected to the system by coupling means 9. The coupling means 9 may comprise a pierceable membrane. The electric heater 4 may, in a further embodiment, be part of the cartridge 7. In this embodiment, the housing 1 defines a device portion comprising the control unit 2 and the battery 3.

The control unit 2 is configured to detect, if a cartridge 7 is coupled to the system. If a cartridge 7 is coupled to the system, the control unit 2 prevents a charging of the battery 3. A charging of the battery 3 is only enabled by the control unit 2, if the cartridge 7 is not coupled to the system. It is to be noted that Figures 1 and 2 show the cartridge 7 and the charging cable 6 both to be connected to the housing 1 of the system at a rearward end. This is only illustrative. The housing 1 may be configured such that the cartridge 7 as well as the charging cable 6 may be attached anywhere at the housing 1 other than at the mouthpiece 5.

The above described features are to be understood illustrative. The skilled person understands that these features can be combined within the scope of the invention.