Field of the invention

The present invention relates to an aerosol generating device allowing vaporization of a liquid aerosol substrate, often called e-liquid or e-juice. The aerosol generating device according to the invention are also commonly called vaporizers or electronic cigarettes.

Background of the invention

Known aerosol generating devices for vaporizing a liquid aerosol substrate generally comprise a heater and a reservoir filled with a liquid aerosol substrate intended to be aerosolized by the heater. The heater is disposed in a duct open to a mouthpiece for the user to inhale the aerosol. The duct is in fluid communication with the reservoir at the location of the heater so that the heater regularly receives liquid aerosol substrate to transform it into an aerosol.

However, when the device is not in operation and the heater is not operating, i.e. not heating, the liquid aerosol substrate is not transformed to an aerosol and drains into the duct.

There is a need to improve the sealing of aerosol generating devices that allow the vaporization of a liquid aerosol substrate when the devices are not in use.

Summarv of the invention

The invention is intended to provide a simple, convenient and economical aerosol generating device which does not leak liquid when not in use.

The present invention thus relates to an aerosol generating device comprising a reservoir adapted to contain a liquid aerosol substrate to be vaporized by a heater of the aerosol generating device, an air path comprising an air inlet for air admission into the air path, and an air outlet from which an aerosol formed by vaporization of the liquid aerosol substrate exits, the air path having a region of fluid communication with the reservoir allowing the passage of the liquid aerosol substrate, the heater being arranged in the region of fluid communication of the air path, wherein the aerosol generating device comprises an air inlet cover arranged in the air path upstream of the heater, and an aerosol outlet cover arranged in the air path downstream of the heater, the air inlet cover and the aerosol outlet cover being movable between a first position preventing the passage of a liquid into the air path and a second position enabling the passage of a fluid into the air path, the air inlet cover and the aerosol outlet cover being made of shape memory material and moving from the first position to the second position when they reach a predetermined temperature.

In the device according to the invention, the air inlet cover and the air outlet cover prevent the liquid aerosol substrate from leaking into the air path, i.e. , out of the fluid communication region, when their temperatures are below a predetermined temperature. Thus, the air inlet cover and the air outlet cover prevent liquid leakage when the aerosol generating device is not in use and the heater is not activated.

When a user operates the aerosol generating device, the heat generated by the heater or by the hot aerosol leads to the heating of the air inlet cover and the aerosol outlet cover and then to their displacement to the second position in order to allow the flow of said aerosol in the air path. The air inlet cover and the aerosol outlet cover return to the first position as soon as their temperature is below the predetermined temperature.

With the invention, no sensor is required to control the displacement of the air inlet cover and the aerosol outlet cover. The predetermined temperature for the displacement between the first position and the second position can be adjusted according to the type of shape memory material of which the air inlet cover and the aerosol outlet cover are formed.

Preferably, the predetermined temperature is between 30°C and 130°C.

Thus, the air inlet cover and the aerosol outlet cover moves from the first position to the second position when they reach a temperature between 30°C and 130°C.

This temperature range ensures that all, or almost all, of the liquid aerosol substrate in the fluid communication region has been aerosolized and that the aerosol is not overheated. Indeed, drops of liquid aerosol substrate or an overheated aerosol can negatively affect the user's experience.

In an embodiment, the air inlet cover and the aerosol outlet cover are located substantially at a similar distance from the heater.

The air inlet cover and the air outlet cover are thus heated identically. Depending on how close they are to the heater, the air inlet cover and the air outlet cover may be directly subjected to the heat generated by the heater or heated with the heat transferred from the aerosol generated by the vaporization of the liquid aerosol substrate.

The further away they are from the heater, the less the covers will be directly subjected to the heat from the heater. This allows the covers to be displaced to the second position ensuring that all of the liquid aerosol substrate in the fluid communication region has been vaporized.

In addition, the covers delimit a liquid restriction zone which is more or less extended according to their distance from the heater. The smaller the restriction zone, the less likely it is that unvaporized drops of liquid aerosol substrate will be inhaled by the user.

In an alternative embodiment, the aerosol outlet cover is farther from the heater than the air inlet cover.

The air inlet cover can be heated more quickly than the aerosol outlet cover and thus can permit the flow of air into the fluid communication region before the aerosol outlet cover is displaced into the second position. This provides air necessary for vaporization of the liquid aerosol substrate while preventing inhalation by the user until all, or almost all, of the liquid aerosol substrate in the fluid communication region has been aerosolized.

In a complementary embodiment, the heater, the air inlet cover and/or the aerosol outlet cover are connected to an electric power source of the aerosol generating device so that when the heater is supplied with electric current from the electric power source, the electric current passes through the air inlet cover and/or the aerosol outlet cover and causes heating by Joule effect of said air inlet cover and/or the aerosol outlet cover.

Thus, when the aerosol generating device is in use, the electrical energy used to heat the heater is also used to heat, by Joule effect, the air inlet cover and/or the aerosol outlet cover. This accelerates the temperature rise of the air inlet cover and/or the aerosol outlet cover, in addition to the heat transmitted by the heater or by the hot aerosol.

Advantageously, the air inlet cover and/or the aerosol outlet cover comprises a seal adapted to be compressed respectively between the air inlet cover and/or the aerosol outlet cover and a wall of the air path when said air inlet cover and/or the aerosol outlet cover is in the first position.

Such a seal helps to enhance the liquid tightness when the air inlet cover and/or aerosol outlet cover is in the first position. For instance, the seal can compensate for potential misfits, for example, between the air inlet cover and/or the aerosol outlet cover and the air path.

Preferably, air inlet cover and/or the aerosol outlet cover is formed by the assembly of a layer of shape memory material and a layer of elastic material forming the seal, which layer of elastic material, preferably silicone, covers at least partially the layer of shape memory material.

The elastic material, in particular silicone, is particularly well suited for this application since it provides the sealing function and is able to return to its original shape after being deformed.

Advantageously, the air inlet cover and/or aerosol outlet cover comprises a fixed edge attached to a wall of the air path and a free edge that rests against the wall of the air path when the air inlet cover and/or aerosol outlet cover is in the first position and that moves away from the wall of the air path when moving from the first position to the second position, with the air inlet cover and/or aerosol outlet cover deforming.

In this way, no additional mechanism is required to move the cover between the first and second position.

Brief description of the drawings

Other particularities and advantages of the invention will also emerge from the following description.

In the accompanying drawings, given by way of non-limiting examples: Other particularities and advantages of the invention will also emerge from the following description.

In the accompanying drawings, given by way of non-limiting examples:

Figure 1 represents, in a schematic sectional view, an aerosol generating device according to a first embodiment of the invention with an air inlet cover and an aerosol outlet cover in a first position (on the left) and in a second position (on the right);

Figure 2 represents, in the same schematic sectional view as Figure 1 , an aerosol generating device according to a second embodiment of the invention with the air inlet cover and the aerosol outlet cover in a first position (on the left) and in a second position (on the right);

Figure 3 represents, in the same schematic sectional view as Figure 1 , an aerosol generating device according to a third embodiment of the invention with the air inlet cover and the aerosol outlet cover in a first position (on the left) and in a second position (on the right);

Figure 4 represents, in a schematic sectional view, the aerosol generating device of Figure 1 with different covers; and

Figure 5 represents in an isolated way and in a schematic sectional view, the cover adapted for use of Figure 4.

Detailed Description

Figure 1 represents an aerosol generating device 1 according to a first embodiment of the invention.

The aerosol generating device 1 comprises a reservoir 2, a heater 3, an electric power source 4 supplying the heater 3, and an air path 5.

The reservoir 2 defines an inner volume adapted to contain a liquid aerosol substrate. In particular, the liquid aerosol substrate is adapted to be provided in the reservoir 2 in liquid form. The liquid aerosol substrate is adapted to be aerosolized under the influence of heat energy. In other words the vaporization is obtained by heating the liquid aerosol substrate.

To this end, the heater 3 is configured to perform aerosolization of the liquid aerosol substrate. The heater 3 comprises heating means such as a resistive element, such as a resistive wire that is coiled in the represented embodiment. The heater 3 is a so called “vertical heater”, installed vertically in the aerosol generating device 1 i.e. such that the heater 3 extends in a longitudinal direction of the aerosol generating device 1.

To allow the formation of an aerosol, the heater 3 must be provided with an electric current via the electric power source 4, with liquid aerosol substrate from the reservoir 2, and with air.

The heater 3 is connected to electric power source 4 by conducting wires 41 . In particular, a conducting wire links a first end of the coil formed by the heater 3 to a positive terminal of the power supply 4, while another conducting wire links a second end of the coil formed by the heater 3 to a negative terminal of the electric power supply 4.

In the illustrated example, the heater 3 is supplied with electric current by means of a switch 42 connected in series with one of the conducting wires 41 . The switch 42 is connected to a control unit which changes the state of the switch 42 between an open and a closed state. The control unit may comprise a push button, a puff sensor or any other known means adapted to determine when the user wishes the delivery of a puff by the aerosol generating device.

In the illustrated example, the electric power source 4 is represented externally of the aerosol generating device 1 for clarity, but it is understood that the electric power source 4 is integrated in the device.

The heater 3 is arranged in the air path 5 so that the heater 3 is exposed to an air flow under the influence of a user's suction from a mouthpiece 6 of the aerosol generating device 1. This air path 5 is provided for the flow of air to the heater 3 and the flow of aerosol, formed with this air, from the heater 3 to the air outlet 52.

The air path 5 has an air inlet 51 for air admission, and an air outlet 52, which is where the aerosol exits from the aerosol generating device 1 . The air outlet 52, or aerosol outlet, thus opens onto the mouthpiece 6.

In the illustrated example, the air path 5 extends in a straight line and the air inlet 51 opens on a face opposite to the mouthpiece 6. Of course, the straight shape of the air path 5 is given as an example and other shapes can be envisaged. In the same way, the air inlet can open on any other face of the aerosol generating device, including near the mouthpiece.

The air path 5 has a region of fluid communication 53 with the reservoir 2, allowing the passage of the liquid aerosol substrate from the reservoir 2 into the air path 5. The fluid communication region 53 is shown here with a larger crosssection than the rest of the air path 5, but it can also have the same cross-section as the air path 5, or a smaller one.

The supply of liquid aerosol substrate to the heater 3 may be performed via holes, wicks (not represented) or any other means known by the skilled person, allowing fluid communication between the inner volume of the reservoir 2 and the region of fluid communication 53 of the air path 5.

The heater 3 is disposed in the air path 5 in the fluid communication region 53 to heat the liquid aerosol substrate discharging from the reservoir 2. When the heater 3 is at a sufficient temperature, the liquid aerosol substrate is vaporized into an aerosol.

It may happen when the heater 3 is not at a sufficient temperature that the liquid aerosol substrate discharges from the reservoir 2 into the fluid communication region 53 of the air path 5 without being vaporized. To prevent the liquid aerosol substrate from flowing to the air inlet 51 and/or air outlet 52 of the air path 5 and then leaking out of the aerosol generating device 1 , the latter comprises an air inlet cover 7 arranged in the air path 5 upstream of the heater 3, and an aerosol outlet cover 8 arranged in the air path 5 downstream of the heater 3.

The air inlet cover 7 and the aerosol outlet cover 8 are movable between a first position in which it prohibits the passage of a liquid, in particular the liquid aerosol substrate, into the air path 5 and a second position in which it allows the passage of a fluid into the air path 5.

The fluid communication region 53 is located between the air inlet cover 7 and the aerosol outlet cover 8 so that the liquid aerosol substrate cannot leak to the air inlet 51 or the air outlet 52 when the covers 7 and 8 are in the first position.

The air inlet cover 7 and the aerosol outlet cover 8 are configured to be in the first position when the aerosol generating device 1 is not being used by a user, and in the second position when the aerosol generating device 1 is in use, i.e. when a user is vaping.

Specifically, the air inlet cover 7 and aerosol outlet cover 8 comprise respectively a fixed edge 71 and 81 attached to a wall of the air path 5, and a free edge 72 and 82 that rests against the wall of the air path 5 in the first position as shown in Figure 1 , and that is away from the wall of the air path 5 in the second position.

The change in temperature leads to a reversible deformation of the covers 7 and 8. In particular, when the covers 7 and 8 reach or exceed the predetermined temperature discussed in more detail below, the covers 7 and 8 deform by bending so that the free edge 72, 82 moves away from the wall of the air path 5 and permits fluid communication between the fluid communication region 53 and the air inlet 51 as well as between the fluid communication region 53 and the air outlet 52.

In this way, it is possible to avoid leakage of liquid aerosol substrate from the aerosol generating device 1when not used, even if it is stored in a position which makes the flow of liquid aerosol substrate into the air path 5 more susceptible.

Thus, in order to trigger the displacement of the covers 7 et 8 from the first position to the second position, it is preferable that the heater 3 has reached a predetermined temperature at which the liquid aerosol substrate vaporizes. In this way, the fluid communication region 53 only communicates with the rest of the air path 5 when all of the liquid aerosol substrate present in the fluid communication region 53 has been vaporized. This prevents the user from aspirating liquid aerosol substrate that has not been vaporized. The vaporization of the liquid aerosol substrate is generally obtained when the heater 3 reaches a temperature up to 400°C, preferably up to 350°C. However, this temperature can vary depending on the type of substrate used.

The air inlet cover 7 and the aerosol outlet cover 8 are made of shape memory material, for example an alloy of nickel and titanium also known as Nitinol. The air inlet cover 7 and the aerosol outlet cover 8 can be made from different shape memory materials or from the same material.

The air inlet cover 7 and the aerosol outlet cover 8 move from the first position to the second position when they reach or exceeds a predetermined temperature. Conversely, the covers 7 and 8 move from the second position to the first position when their temperature falls below the predetermined temperature.

The predetermined temperature for moving the covers 7 and 8 between the first position and the second position is between 30°C and 130°C. This temperature may vary depending on the type of shape memory material used.

In the first embodiment illustrated in Figure 1 , the air inlet cover 7 and the aerosol outlet cover 8 are arranged substantially at a similar distance from the heater 3. Thus, the covers 7 and 8 are heated in a similar way. The distance between the covers 7 and 8 and the heater 3 can be between 1 and 10 mm. When the covers 7 and 8 are located at less than 5 mm from the heater 3, said covers 7 and 8 are directly heated by the heat generated by heater 3, which simultaneously heats the liquid aerosol substrate and covers 7 and 8. This arrangement allows the covers 7 and 8 to move from the first position to the second position relatively quickly since they are heated as soon as the heater 3 is activated.

Figure 2 shows the aerosol generating device according to a second embodiment in which only the arrangement of the aerosol outlet cover 8 differs from the aerosol generation device visible in Figure 1.

This embodiment is based on the idea that the temperature rise time of the cover can be adjusted by varying the distance between said cover and the heater. Other embodiments not shown are based on the idea that the temperature rise time of the cover can be adjusted by choosing different shape memory materials with different deformation temperatures.

The aerosol outlet cover 8 is further away from the heater 3 than the air inlet cover 7. The aerosol outlet cover 8 is here closer to the air outlet 52 of the air passage 5 than to the heater 3. The fact that the aerosol outlet cover 8 is far enough away from the heater 3 means that it is not heated directly by the heater 3. In this case, the cover 8 is heated mainly by the aerosol generated when the aerosol generating device 1 is in use. This may result in the positioning of the cover 8 at a distance of more than 5 mm from the heater 3.

In this embodiment, the air inlet cover 7 is heated more quickly than the aerosol outlet cover 8 and thus moves more quickly from the first position to the second position. Thus, as the air inlet cover 7 moves to the second position, air flows through the air path 5 into the fluid communication region 53 and allows an aerosol to form with the heater 3 and the liquid aerosol substrate. The aerosol then flows through the air path 5 towards the air outlet 52 and heats the aerosol outlet cover 8 by convection. Once the aerosol outlet cover 8 has reached the predetermined temperature, it moves to the second position and allows the aerosol to flow towards the air outlet 52. In this embodiment, since it is the aerosol that mainly heats the aerosol outlet cover 8, it is possible to ensure that all or nearly all of the liquid aerosol substrate present in the fluid communication region 53 has been vaporized.

Figure 3 shows the aerosol generating device according to a third embodiment in which the air inlet cover and the aerosol outlet cover are connected to the electric power source 4. This embodiment may be combined with any of the previously described embodiments.

In this arrangement, the lead wire 41 connecting the positive pole of the electric current source 4 to the first end of the heater coil 3, is also linked to the covers 7 and 8, and the conducting wire 41 linking the negative terminal of the electric power source 4 to the second end of the coil of the heater 3, is also linked to the covers 7 and 8. When the switch 42 is in closed state, an electric current flows through the heater 3, the air inlet cover 7 and the aerosol outlet cover 8. In the same way as for the heater 3, the flow of electric current in the covers 7 and 8 leads to their heating by Joule effect. This is particularly advantageous as a complement to the heating of the covers 7 and 8 by the heater 3, e.g. to reduce the heating time of the covers 7 and 8.

Figure 4 and 5 shows the aerosol generating device according to a fourth embodiment in which the air inlet cover and the aerosol outlet cover differ from the aerosol generating devices visible in Figures 1 to 3.

To simplify the description, the same numerical references have been used except for the air inlet cover and the aerosol outlet cover for which similar references but with the number 100 added have been used. This embodiment can be combined with any of the previously described embodiments.

As for the previously described embodiments, each of air inlet cover 107 and the aerosol outlet cover 108 comprises a fixed edge 171 , 181 and a free edge 172, 182.

Each of the covers 107 and 108 includes a layer of shape memory material 173, 183 and a seal 174, 184 adapted to be compressed between the layer of shape memory material 173, 183 and a wall of the air path 5 in the first position. This allows for improved sealing to liquids, specifically the liquid aerosol substrate, when the aerosol generating device 1 is not in use.

As shown in more detail in Figure 5, the cover 107, 108 is formed by the assembly of the layer of shape memory material 173, 183 and a layer of elastic material 174, 184 forming the seal. The layer of elastic material 174, 184 is preferably made of silicone, which has particularly advantageous mechanical and thermal properties for this use.

The layer of elastic material 174, 184 at least partially covers the layer of shape memory material 173, 183. In the illustrated example, the layer of elastic material 174, 184 covers one side of the layer of shape memory material 173, 183. Alternatively, the layer of shape memory material may be overmolded with an elastic material so that the layer of shape memory material is completely covered.

This embodiment is particularly advantageous in that it improves liquid tightness and does not interfere with the displacement of the cover 107, 108 between the first and second positions.

With the invention, it is possible to improve the liquid-tightness of aerosol generating devices allowing the vaporization of a liquid aerosol substrate when these devices are not in use. Furthermore, the covers according to the invention can be easily implemented on existing devices since they do not require the addition of any mechanism or sensor to operate. As a consequence of their simplicity of use, these covers are relatively reliable and their service life depends only on the durability of the materials from which they are made.