Nebulizing electronic cigarette

Abstract

The invention relates to an electronic cigarette configured to nebulize a liquid contained in a reservoir (18) through a vibrating membrane (20). The electronic cigarette comprises a chamber (42) disposed between the reservoir (18) and the membrane (20), the chamber (42) extending between two parallel walls (20a, 44), one of which is formed by a face (20a) of the membrane (20), the liquid (50) wetting the two walls (20a, 44) of the chamber (42), a thickness of the chamber (42), forming a distance separating the two walls (20a, 44), being defined such that the liquid diffuses into the chamber (42) by capillary action so that the liquid is maintained in contact with the membrane (20). Figure for the abstract: Fig. 2

Description

Title of the invention: Nebulizing electronic cigarette

[0001] The invention relates to an electronic cigarette that allows the simulation of a conventional cigarette in which tobacco is consumed.

[0002] Most current electronic cigarettes vaporize a liquid contained in a cartridge to generate vapor that is inhaled by the user, thus simulating smoking. Vaporization is achieved by heating the liquid using an electrical resistance element immersed in it. Through the Joule effect, the resistance element dissipates heat into the liquid, causing it to vaporize. The resulting vapor can then be inhaled by the user.

[0003] Resistance heating has several drawbacks. First, vaporization significantly raises the temperature of the liquid to be inhaled by the user. Once vaporized, the liquid can reach temperatures well above 100°C. Some manufacturers offer electronic cigarettes in which the inhaled products reach temperatures of around 350°C. At these temperatures, the additives present in the vaporized liquid can be denatured. In particular, their chemical composition can be altered, which can lead to a change in the taste perceived by the user.

[0004] Furthermore, achieving vaporization requires significant energy consumption to raise the liquid's temperature and provide it with the latent heat of vaporization necessary for its transformation from a liquid to a gaseous state. Electronic cigarettes are equipped with batteries that power the heating element which vaporizes the liquid. The battery must be large enough to provide acceptable battery life for the user. The significant energy consumption of the heating element necessitates a large battery size and weight.

[0005] To avoid vaporizing the liquid inhaled by the user, the inventor developed a first model of an electronic cigarette, a description of which was published in document WO 2021 / 094602 AL. This document specifies that liquid in a reservoir is placed in contact with a vibrating porous membrane to atomize the liquid. By preventing vaporization, the electronic cigarette's energy consumption is reduced since it is not necessary to heat the liquid to change its phase from liquid to gas. The document also describes the presence of a capillary element that drains the liquid from the reservoir to the membrane. This capillary element partially occupies the volume of the reservoir, thus reducing its usable volume.

[0006] The invention aims to overcome all or part of the problems mentioned above by proposing a nebulizing electronic cigarette in which the liquid is maintained in contact with the membrane without the use of a capillary element.

[0007] To this end, the invention relates to an electronic cigarette comprising: - a reservoir containing a liquid suitable for nebulization - a porous membrane configured to nebulize the liquid, the membrane having the shape of a film with two opposite faces separated by the thickness of the membrane, the liquid present in the reservoir coming into contact with one of the two faces to pass through the membrane in its thickness, - an actuator configured to vibrate the membrane in such a way as to nebulize the liquid as it passes through the membrane, - a chamber arranged between the reservoir and the membrane, the chamber being in communication with the reservoir to admit the liquid, the chamber extending between two parallel walls, the first of which is formed by the first face, the liquid wetting the two walls of the chamber, a thickness of the chamber, forming a distance separating the two walls, being defined so that the liquid diffuses into the chamber by capillarity so that the liquid is kept in contact with the membrane.

[0008] Advantageously, the chamber is in communication with the reservoir by means of an orifice located opposite a central area of ​​the membrane.

[0009] A vertical orientation of the electronic cigarette is defined with respect to a user in a standing position inhaling liquid nebulized by the membrane and, advantageously, in the vertical orientation, the chamber is in communication with the reservoir by means of an orifice opening onto a lowest part of the reservoir.

[0010] Advantageously, the chamber has a washer shape extending around the orifice.

[0011] Advantageously, the chamber has a circular contour and the orifice has a circular section concentric with the circular contour of the chamber.

[0012] The invention will be better understood and other advantages will become apparent upon reading the detailed description of an embodiment given by way of example, a description illustrated by the accompanying drawing in which:

[0013] [Fig-1] [Fig.1] shows in cross-section and perspective an example of an e-cigarette tronics according to the invention;

[0014] [Fig.2] [Fig.2] shows in section and perspective a partial view of the cigarette of the [Fig.l] at the level of a liquid reservoir;

[0015] [Fig.3] Figures 3a and 3b represent, in a first orientation, with respect to a vertical direction, the part of the electronic cigarette shown in [Fig.2];

[0016] [Fig. 4] Figures 4a and 4b represent, in a second orientation, with respect to a vertical direction, the part of the electronic cigarette shown in [Fig.2].

[0017] For the sake of clarity, the same elements will bear the same markings in the different different figures.

[0018] Figure 1 represents an example of an elongated electronic cigarette 10 extending mainly along a longitudinal axis 12. The electronic cigarette 10 has, in the example shown, a casing 14 with a substantially rectangular cross-section perpendicular to the longitudinal axis 12 except for a prominent mouthpiece 16 which a user can bring to the mouth to inhale a liquid nebulized by the electronic cigarette 10. Any other shape of casing 14 is, of course, possible within the scope of the invention.

[0019] The cigarette 10 comprises a reservoir 18 containing a liquid product intended to be nebulized for inhalation by a user through the mouthpiece 16. The reservoir 18 is closed by a removable cap 19 allowing the reservoir 18 to be refilled. The cigarette 10 also comprises a membrane 20 and an actuator 22 configured to vibrate the membrane 20. The membrane 20 is porous to allow the liquid to pass through in the form of a mist. The liquid remains in the liquid phase as it passes through the membrane 20. At the outlet of the membrane 20, the liquid is in the form of liquid droplets with a characteristic size on the order of 1 to 10 µm. The membrane 20 is perforated with orifices having a cross-section corresponding to the size of the droplets. More precisely, the membrane 20 is in the form of a flat film having two opposite faces 20a and 20b separated by the thickness of the membrane 20.In the example shown, the membrane 20 extends primarily parallel to the axis 12. It is possible to arrange the membrane in other orientations, notably perpendicular to the axis 12. The liquid in the reservoir 18 comes into contact with face 20a and passes through the membrane 20. The vibration of the membrane 20, driven by the actuator 22, causes the liquid to pass through the membrane. This vibration deforms the membrane, primarily perpendicular to its thickness. In the example shown, the membrane 20 has a circular outline. Other membrane shapes are possible within the scope of the invention. For a membrane 20 with a diameter of approximately 20 mm, vibration at an ultrasonic frequency achieves the desired nebulization. Internal tests have shown that a frequency of 30 kHz provides adequate nebulization of the liquid.For the liquid, passing through the membrane 20 in its thickness limits the energy required for nebulization. The thinness of the membrane offers little resistance to the liquid's passage. Once the membrane 20 has passed through, the nebulized liquid disperses inside the nozzle 16 to be aspirated by the user.

[0020] The actuator 22 can be electrically powered. The power supply can be external to the cigarette 10. However, in order for the user to be able to use the cigarette 10 autonomously, the cigarette 10 is equipped with a battery 26 for powering The actuator 22. Wiring wires 28 and 30 connect the battery 26 and the actuator 22. In the example of [Fig. 1], the actuator 22 is a piezoelectric actuator. This type of actuator is well suited to ultrasonic frequencies. The actuator 22 here has the shape of a washer with a hole in its center to allow the diaphragm 20 to vibrate freely. Other types of actuators for vibrating the diaphragm can be used within the scope of the invention.

[0021] The actuator 22 can be powered by the battery 26 using a switch 32 operated by the user when they wish to use the cigarette 10. Alternatively, or in addition to the switch 32, the actuator 22 can be powered when the user inhales on the cigarette 10. Such inhalation can be detected by means of a pressure sensor 34 configured to detect user inhalation. More specifically, the pressure sensor 34 is located in a chamber 36 of the cigarette 10, the pressure of which decreases when the user inhales on the cigarette 10 through the mouthpiece 16. In addition to the pressure sensor 34, the cigarette 10 includes an electronic circuit 37 that receives information from the pressure sensor 24 and controls the actuator 22 according to the information received from the pressure sensor 34.The electronic circuit 37 may include a comparator connected to the pressure sensor 34 at one of its inputs and to a reference voltage at the other. The reference voltage represents the pressure below which the actuator 22 must operate. The comparator output provides a binary signal that is a function of the sign of the difference between the signal received from the pressure sensor 34 and the reference voltage. Alternatively, the electronic circuit 37 may include a processor, for example, integrated into a microcontroller, which performs the comparison operation described by the comparator. The advantage of using a processor is that it can also perform other tasks, such as monitoring the state of charge of the battery 26, monitoring the liquid level in the tank 18, etc. The electronic circuit 37 may be implemented on a printed circuit board. The pressure sensor 34 may be soldered onto the printed circuit board.

[0022] The cigarette 10 may include a connector 38 for example fixed to the electronic circuit 37 and allowing the battery 26 to be recharged and the electronic circuit 37 to be communicated with.

[0023] The cigarette 10 includes an orifice 40 allowing outside air to reach the chamber 36 where the pressure sensor 34 is located. The functional gap between the connector 38 and the casing 14 can be used as orifice 40. Once inside the casing 14, the air bypasses the electronic circuit 37 and the battery 26 to reach the inside of the mouthpiece 16, forming a chamber in which the air is mixed with the nebulized liquid.

[0024] Figure 2 shows, in partial and enlarged view, the electronic cigarette 10. reservoir level 18, membrane level 20 and nozzle level 16.

[0025] Between the reservoir 18 and the membrane 20, the cigarette 10 includes a chamber 42 in communication with the reservoir 18. The chamber 42 is dimensioned to keep the liquid present in the reservoir 18 in contact with the membrane 20 without a capillary element as described in document WO 2021 / 094602 A1.

[0026] The chamber 42 extends along the membrane 20. The chamber 42 comprises two parallel walls. Face 20a of the membrane 20 forms one of the walls of the chamber 42. The other wall of the chamber 42, parallel to face 20a, is designated 44 and is, for example, formed in a body 43 of the cigarette 10, a portion of which separates the chamber 42 from the reservoir 18. The liquid, as well as the walls 20a and 44, are defined such that the liquid wets the walls. In other words, in the presence of air at atmospheric pressure, the contact angle of a drop of liquid resting on a horizontal surface formed by the wall in question is less than 90°. This contact angle depends on the surface tension of the liquid at the interface with the air and on the nature of the walls 20a and 44. The thickness E of the chamber 42 is defined with respect to face 20a. The thickness E is therefore the distance separating face 20a and wall 44.The thickness E is defined so that the liquid diffuses into the chamber by capillary action. The chamber 42 has an essentially planar shape along a plane 45 passing between the two walls 20a and 44. The thickness E is defined perpendicular to the plane 45.

[0027] The liquid can, for example, be aqueous and contain additives, including nicotine and flavorings. Internal tests have shown that an aqueous liquid gives good nebulization results with a membrane 20 perforated with orifices having a cross-section on the order of a few micrometers. Other liquid bases are also possible, for example, glycerin-based. The cross-section of the orifices in the membrane 20 is then adapted to the liquid to allow its nebulization. It is possible to make a membrane 20 from stainless steel. This type of membrane has a good lifespan. Other materials are possible for making the membrane. An aqueous liquid properly wets a stainless steel wall 20a.

[0028] In the example shown, the other wall 44 of the chamber 42 is formed in the body 43 of the cigarette 10. The body 43 can be made of plastic. Several materials have been successfully tested for their adequate wettability in contact with an aqueous-based liquid, including acrylonitrile butadiene styrene (ABS), polyethylene (PE), polyoxymethylene (POM), etc. Metallic materials, particularly aluminum alloys, can also be used. In practice, the body 43 of the cigarette 10 can be made of a material that facilitates its production and coated with a finish ensuring good wettability with the selected liquid. Furthermore, among the additives added to the liquid base, some can be chosen to improve the wettability of the liquid with respect to walls 20a and 44. For example, for an aqueous-based liquid, it is possible to add a solvent based on organic carbonates, some of which are known to improve the wettability of water.

[0029] Figure 3a shows the portion of the electronic cigarette shown in [Fig. 2] in cross-section in a plane perpendicular to the plane in which the membrane 20 extends. The chamber 42 communicates with the reservoir 18 by means of an orifice 46, for example, located opposite a central area 20c of the membrane 20. The chamber 42 has, for example, a circular contour 48, here formed by a sealing gasket disposed between the membrane 20 and the body 43 of the cigarette 50. The contour 48 extends in the plane 45. The orifice 46 then has a cross-section that is also circular and concentric with the contour 48 of the chamber 42. The chamber 42 extends in the shape of a disc between the walls 20a and 44 around the central area 20c. The user can manipulate the cigarette 10 so that the longitudinal axis 12 is oriented in any direction relative to a vertical direction.When a user in a standing position inhales the nebulized liquid through the mouthpiece 16, the longitudinal axis 12 is in a substantially vertical position. This orientation of the e-cigarette 10 is subsequently referred to as vertical. In this position, due to gravity, the liquid 50 is in a lower position in the reservoir 18 and communicates with the chamber 42 in the part located below the level 52 of the liquid 50. By capillary action, the liquid diffuses throughout the chamber 42 and, in particular, rises against gravity all around the central area 20c of the membrane 20.

[0030] Figure 3b shows chamber 42 in plane 45 parallel to walls 20a and 44. The orifice 46 is shown in the center, and the liquid level 52 is shown above the lowest level of orifice 46 in the vertical orientation of the cigarette 10 shown in Figure 3a. Arrows 54 represent the upward movement of the liquid in chamber 42 against gravity by capillary action.

[0031] In Figures 3a and 3b, the liquid level 52 of the liquid 50 is shown at the bottom of the reservoir 18. In other words, the reservoir 18 is almost empty. Even with this very low level of liquid 50, it is in contact with the chamber 42 and can diffuse throughout the chamber 42 by capillary action. Movements by the user, causing the cigarette 10 to oscillate around its vertical orientation shown in Figures 3a and 3b, allow liquid 50 to move within the reservoir 18 and periodically enter the orifice 46, bringing the liquid 50 into contact with the chamber 42. This contact, even if temporary, allows the liquid to diffuse into the chamber 42. Capillary action allows the liquid 50 to remain in the chamber 42 even when the cigarette 10 is tilted so that the liquid 50 does not bathe the orifice 46.

[0032] Figures 4a and 4b represent the cigarette 10 in a so-called horizontal orientation as opposed to the vertical orientation of the cigarette 10 represented in Figures 3a and 3b. In horizontal orientation, axis 12 and plane 45 are horizontal. The level 52 of liquid 50 is parallel to plane 45 due to gravity. The horizontal orientation of the cigarette 10 prevents the liquid 50 contained in the reservoir 18 from reaching chamber 42 through orifice 46. However, even in this orientation, liquid 50 remains inside chamber 42.

[0033] During vibrations of the membrane 20 used to nebulize the liquid 50, the central zone 20c of the membrane 20 is supplied with liquid from the entire chamber 42, that is, from the entire periphery of the membrane 20. This supply of liquid 50 to the membrane 20 is homogeneous and ensures nebulization by the entire central zone 20c. This radial supply of liquid 50 to the membrane 20 from the chamber 42 to the central zone 20c is represented by arrows 56 in Figures 3b and 4b. Thus, regardless of the level of liquid 50 in the reservoir 18 and especially regardless of the orientation of the cigarette 10, the membrane 20 is supplied with liquid homogeneously. This reduces variations in the quantity of nebulized liquid as the reservoir 18 empties.

[0034] In the vertical orientation of the cigarette 10, the lowest part of the reservoir 18 may be located lower than the lowest point of the orifice 46. However, in this configuration, liquid 50 may remain in the reservoir 18 without the usual movements of the user allowing liquid 50 located at the bottom of the reservoir 18 to fill the chamber 42. It is therefore advantageous for the orifice 46 to open onto the lowest part of the reservoir 18 in the vertical orientation of the cigarette 10. Thus, even when the reservoir 18 is only partially filled, communication of the liquid 50 with the chamber 42 is ensured.

[0035] In practice, the reservoir 18 must periodically supply the chamber 42 so that the latter can, in turn, maintain a liquid film on the central area 20c of the membrane 20. It has been observed that, on average, a user's inhalation lasts on the order of a few seconds, typically 3 seconds. The chamber 42 is sized, particularly its outer diameter, to contain a volume equivalent to 30 to 50 seconds of inhalation, which represents more than ten inhalations. During the period in which a user performs these ten inhalations, the probability that they will change the orientation of the e-cigarette 10 is very high, and in particular that they will orient the e-cigarette 10 in a position where the liquid level 52 reaches the chamber 42 for at least the time necessary to fill the chamber 42.The orientations of the cigarette 10 shown in Figures 3a and 4a are merely examples to illustrate how the chamber 42 can fill or not fill with the liquid 50 contained in the reservoir 18. In practice, when using the cigarette 10, the user regularly changes its orientation to any intermediate position between those shown. In general, it must be understood that the filling of chamber 42 can take place when the level 52 of the liquid 50 reaches chamber 42 and stops when the level 52 does not reach it.

[0036] During nebulization, it was observed that some air bubbles tend to form on face 20a of membrane 20 at the central zone 20c within the liquid film present on membrane 20 on the side of reservoir 18, i.e., on face 20a of membrane 20. It was observed that the air bubbles do not form in chamber 42, i.e., on the peripheral part of membrane 20, but only at the central zone 20c. If these air bubbles remain in contact with membrane 20, nebulization is impaired. The presence of orifice 46 facing the central zone 20c allows these air bubbles to be evacuated to reservoir 18 above the liquid level 52. The fact that the air bubbles can be evacuated through orifice 46 prevents interference with nebulization. Thus, in order to improve nebulization, it is advantageous for the orifice 46 to be located opposite the central zone 20c of the membrane 20.

Claims

Demands

1. Electronic cigarette (10; 100) comprising: - a reservoir (18) containing a liquid (50) suitable for nebulization, - a porous membrane (20) configured to nebulize the liquid (50), the membrane (20) having the form of a film having two opposite faces (20a, 20b) separated by the thickness of the membrane (20), the liquid (50) present in the reservoir (18) coming into contact with a first (20a) of the two faces to pass through the membrane (20) in its thickness, - an actuator (22) configured to vibrate the membrane (20) so as to nebulize the liquid (50) as it passes through the membrane (20), - a chamber (42) disposed between the reservoir (18) and the membrane (20), the chamber (42) being in communication with the reservoir (18) to admit the liquid (50), the chamber (42) extending between two parallel walls (20a, 44), the first of which is formed by the first face (20a), the liquid (50) wetting the two walls (20a,44) of the chamber (42), a thickness (E) of the chamber (42), forming a distance separating the two walls (20a, 44), being defined so that the liquid (50) diffuses into the chamber (42) by capillarity so that the liquid (50) is kept in contact with the membrane (20), the chamber (42) being in communication with the reservoir (18) by means of an orifice (46) located opposite a central area (20c) of the membrane (20).

2. Electronic cigarette according to claim 1, wherein a vertical orientation (12) of the electronic cigarette (10) is defined with respect to a user in a standing position inhaling liquid nebulized by the membrane (18), and in the vertical orientation: - the chamber (42) and the membrane (20) extend substantially vertically, - the chamber (42) is in communication with the reservoir (18) by means of an orifice (46) opening onto a lower part of the reservoir (18).

3. Electronic cigarette according to any one of the preceding claims, wherein the chamber (42) has a washer shape extending around the orifice (46).

4. Electronic cigarette according to any one of the preceding claims in which the chamber (42) has a circular contour (48) and in in which the orifice (46) has a circular section concentric with the circular contour (48) of the chamber (42).

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