Atomizing electronic cigarette

Abstract

The invention relates to an electronic cigarette configured to atomize, through a vibrating membrane (20), a liquid contained in a reservoir (18). The electronic cigarette comprises a chamber (42) arranged 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 kept in contact with the membrane (20).

Description

DESCRIPTION Title of the invention: Nebulizing electronic cigarette

[0001] The invention relates to an electronic cigarette capable of simulating a conventional cigarette in which tobacco is consumed.

[0002] Most current e-cigarettes vaporize a liquid contained in a cartridge to generate vapor that is inhaled by a user, allowing them to simulate smoking. Vaporization is achieved by heating the liquid using an electrical resistor immersed in the liquid. Through the Joule effect, the resistor dissipates heat into the liquid, which vaporizes. The resulting vapor can be inhaled by the user.

[0003] Resistance heating has several disadvantages. 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 e-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. Their chemical composition can be altered, which can lead to a change in the taste experienced by the user.

[0004] Furthermore, achieving vaporization requires significant energy consumption to raise the liquid temperature and provide it with the latent heat needed to transform it from a liquid to a gaseous state. Electronic cigarettes are equipped with a battery that powers the heating element that vaporizes the liquid. The battery must be sufficiently sized to provide acceptable battery life for the user. The significant energy expenditure of the element requires a large size and mass for the battery.

[0005] To avoid vaporizing the liquid inhaled by the user, the inventor developed a first model of electronic cigarette, a description of which was published in document WO 2021 / 094602 A1. In this document, it is specified that liquid present in a reservoir is placed in contact with a porous membrane that can vibrate to nebulize the liquid. By avoiding vaporization, the energy consumption of the electronic cigarette is reduced since it is not necessary to heat the liquid to change it from its liquid phase to its gaseous phase. In this document, the presence of a capillary element is described to drain the liquid contained in the tank towards the membrane. This capillary element occupies part of the volume of the tank, which reduces the useful volume of the tank.

[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 kept in contact with the membrane without using 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 form of a film having two opposite faces spaced apart by the thickness of the membrane, the liquid present in the reservoir coming into contact with a first of the two faces to pass through the membrane in its thickness, - an actuator configured to vibrate the membrane so 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 therein, 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, the chamber being in communication with the reservoir by means of an orifice located opposite a central zone of the membrane.

[0008] A vertical orientation of the electronic cigarette is defined relative to a user in a standing position inhaling nebulized liquid through the membrane and, advantageously, in the vertical orientation: - the chamber and the membrane extend substantially vertically, - the chamber is in communication with the tank by means of an orifice opening onto a lower part of the tank.

[0009] Advantageously, the chamber has a washer shape extending around the orifice.

[0010] Advantageously, the chamber has a circular outline and the orifice has a circular section concentric with the circular outline of the chamber.

[0011] Advantageously, the actuator is fixed to the membrane and the actuator is drilled to the same dimensions as those of a section of the orifice.

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

[0013] [Fig.1] Figure 1 represents in section and in perspective an example of an electronic cigarette according to the invention;

[0014] [Fig.2] Figure 2 represents in section and in perspective a partial view of the cigarette of Figure 1 at the level of a liquid reservoir;

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

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

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

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

[0019] The cigarette 10 comprises a reservoir 18 containing a product in liquid form intended to be nebulized to be inhaled by a user through the mouthpiece 16. The reservoir 18 is closed by a removable cap 19 allowing the reservoir 18 to be filled. The cigarette 10 also comprises a membrane 20 and an actuator 22 configured to vibrate the membrane 20. The membrane 20 is porous in order to allow the liquid to pass in the form of a mist. The liquid remains in the liquid phase when it passes through the membrane 20. At the outlet of the membrane 20, the liquid is in the form of liquid droplets whose characteristic dimension is of the order of 1 to 10 μm. The membrane 20 is perforated with orifices having a section of the dimension of the droplets. More precisely, the membrane 20 has the form of a flat film having two opposite faces 20a and 20b spaced apart by the thickness of the membrane 20.In the example shown, the membrane 20 extends mainly parallel to the axis 12. It is possible to arrange the membrane in other orientations, in particular perpendicular to the axis 12. The liquid present in the reservoir 18 comes into contact with the face 20a to pass through the membrane 20 in its thickness. The vibration of the membrane 20 operated by the actuator 22 causes the liquid to pass through the membrane 20. The vibration of the membrane 20 causes it to deform, mainly perpendicular to its thickness. In the example shown, the membrane 20 has a circular contour. Other membrane shapes are possible within the scope of the invention. For a membrane 20 of the order of 20mm in diameter, vibration at an ultrasonic frequency makes it possible to obtain the desired nebulization. Internal tests have shown that a frequency of 30kHz makes it possible to nebulize the liquid correctly.For the liquid, passing through the membrane 20 in its thickness makes it possible to limit the energy required for nebulization. The small thickness of the membrane offers little resistance to the liquid passing through. Once the membrane 20 has passed through, the nebulized liquid disperses inside the tip 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, so that the user can use the cigarette 10 independently, 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 pierced in its center to allow the membrane 20 to vibrate freely. Other types of actuators for vibrating the membrane can be used within the scope of the invention.

[0021] The power supply of the actuator 22 by the battery 26 can be controlled by means of a switch 32 operated by the user when he wishes to use the cigarette 10. Alternatively or in addition to the switch 32, the power supply of the actuator 22 can be controlled when the user sucks on the cigarette 10. Such suction can be detected by means of a pressure sensor 34 configured to detect the suction of the user. More precisely, the pressure sensor 34 is arranged in a chamber 36 of the cigarette 10 whose pressure drops when the user sucks on the cigarette 10 through the mouthpiece 16. In addition to the pressure sensor 34, the cigarette 10 comprises an electronic circuit 37 receiving information from the pressure sensor 24 and controlling the actuator 22 as a function of the information received from the pressure sensor 34.The electronic circuit 37 may comprise a comparator connected to the pressure sensor 34 at one of its inputs and to a reference voltage at the other of its inputs. The reference voltage is representative of the pressure below which the actuator 22 must be operated. The output of the comparator delivers a binary signal depending on the sign of the difference between the signal received from the pressure sensor 34 and the reference voltage. Alternatively, the electronic circuit 37 may comprise a processor, for example included in a microcontroller, and performing the comparison operation described by means of the comparator. The advantage of implementing 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... The electronic circuit 37 can be produced on a printed circuit. The pressure sensor 34 can be soldered onto the printed circuit.

[0022] The cigarette 10 may comprise a connector 38, for example fixed to the electronic circuit 37, and enabling the battery 26 to be recharged and communication with the electronic circuit 37.

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

[0024] Figure 2 shows a partial and enlarged view of the electronic cigarette 10 at the level of the reservoir 18, the membrane 20 and the mouthpiece 16.

[0025] Between the reservoir 18 and the membrane 20, the cigarette 10 comprises a chamber 42 in communication with the reservoir 18. The chamber 42 is sized to keep the liquid present in the reservoir 18 in contact with the membrane 20 without the need for 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. The face 20a of the membrane 20 forms one of the walls of the chamber 42. The other wall of the chamber 42, parallel to the face 20a, bears the reference 44 and is for example made in a body 43 of the cigarette 10, a part of which separates the chamber 42 from the reservoir 18. The liquid as well as the walls 20a and 44 are defined so 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 placed on a horizontal surface formed by the wall in question has a contact angle of 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 relative to the face 20a. The thickness E is therefore the distance separating the face 20a and the wall 44.The thickness E is defined so that the liquid diffuses into the chamber by. capillarity. The chamber 42 has an essentially flat 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 may, for example, be aqueous-based and contain additives, including nicotine and perfumes. Internal tests have shown that an aqueous-based liquid gives good nebulization results with a membrane 20 pierced with orifices having a cross-section of the order of a few μm. Other liquid bases are also possible, for example glycerin-based. The cross-section of the orifices of 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-based liquid correctly wets a stainless steel wall 20a.

[0028] In the example shown, the other wall 44 of the chamber 42 is made in the body 43 of the cigarette 10. The body 43 can be made of a plastic material. Several materials have been successfully tested for their correct wettability in contact with an aqueous-based liquid, in particular acrylonitrile butadiene styrene known by its acronym ABS, polyethylene (PE), polyoxymethylene (POM), etc. Metallic materials, in particular aluminum-based alloys, can also be used. In practice, it is possible to make the body 43 of the cigarette 10 in a material that makes it easier to make and to cover it with a coating that ensures good wettability with the retained liquid. In addition, among the additives added to the liquid base, it is possible to choose some that make it possible to improve the wettability of the liquid relative to the walls 20a and 44.For example, for a water-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 part of the electronic cigarette shown in Figure 2 in section in a plane perpendicular to the plane in which the membrane 20 extends. The chamber 42 is in communication with the reservoir 18 by means of an orifice 46 for example located opposite a central zone 20c of the membrane 20. Thus, in this central zone 20c, the membrane 20 is not hindered in its oscillation movements when the actuator 22 vibrates the membrane 20. In other words, the central zone 20c cannot touch the walls of the chamber 42 during the oscillation of the membrane. The chamber 42 has for example a circular outer contour 48 here formed by a seal arranged between the membrane 20 and the body 43 of the cigarette 50. Other shapes of outer contours are possible for the chamber 46. The outer contour 48 extends in the plane 45. The orifice 46 then has a section parallel to the plane 45 which is also circular and concentric with the contour 48 of the chamber 42. The chamber 42 extends in the form of a washer between the walls 20a and 44 around the central zone 20c. The orifice 46 can have other section shapes, in particular polygonal, oval, etc.The orifice 46 advantageously has a tubular shape whose axis 49 is perpendicular to the plane 46. The section of the orifice 46 along the axis 49 is then constant.

[0030] The inner contour of the chamber 42 is formed by the orifice 46. Thus, the chamber extends around the periphery of the orifice 46. The thickness E of the chamber 42 remains stable, in other words substantially constant, in order to limit the disturbance of the circulation of the liquid by capillarity in the chamber 42 when the membrane 20 oscillates.

[0031] Furthermore, in the example shown, the bore of the actuator 22 has the same radial dimensions around the axis 49 as those of the orifice 46. More precisely, it is possible to choose an actuator 22 having a circular bore and an orifice 46 of circular section and both of the same diameter D defined parallel to the plane 45. The actuator 22 can be fixed to the membrane 20 and stiffen the membrane 20 around its central zone 20c. Thus the presence and the dimensions of the actuator 22 make it possible to further improve the stability of the thickness E of the chamber 42 during oscillations of the membrane 20.

[0032] 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 nebulized liquid through the mouthpiece 16, the longitudinal axis 12 is in a position substantially vertical. Subsequently, this orientation of the cigarette 10 is called vertical. In this position, due to gravity, the liquid 50 is in the low position in the reservoir 18 and communicates with the chamber 42 in its part located below the level 52 of the liquid 50. By capillarity, the liquid diffuses throughout the chamber 42 and in particular by rising against gravity all around the central zone 20c of the membrane 20.

[0033] Figure 3b shows the chamber 42 in the plane 45 parallel to the walls 20a and 44. There we can see the orifice 46 in the center and the level 52 of the liquid above the lowest level of the orifice 46 in the vertical orientation of the cigarette 10 shown in Figure 3a. Arrows 54 represent the rise of the liquid in the chamber 42 against gravity by capillarity.

[0034] In Figures 3a and 3b, the level 52 of the liquid 50 has been 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 capillarity. Movements of the user causing the cigarette 10 to oscillate around its vertical orientation shown in Figures 3a and 3b, allow liquid 50 to move in the reservoir 18 and periodically enter the orifice 46 bringing the liquid 50 into contact with the chamber 42. This contact, even temporary, allows the liquid to diffuse into the chamber 42. Capillarity 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.

[0035] Figures 4a and 4b represent the cigarette 10 in a so-called horizontal orientation as opposed to the vertical orientation of the cigarette 10 shown in Figures 3a and 3b. In the horizontal orientation, the axis 12 and the plane 45 are horizontal. The level 52 of the liquid 50 is parallel to the plane 45 due to gravity. The horizontal orientation of the cigarette 10 does not allow the liquid 50 contained in the reservoir 18 to reach the chamber 42 through the orifice 46. However, even in this orientation, liquid 50 remains inside the chamber 42.

[0036] During vibrations of the membrane 20 implemented to nebulize the liquid 50, the central zone 20c of the membrane 20 is supplied with liquid by liquid present in the entire chamber 42, that is to say by the entire periphery of the membrane 20. This supply of the membrane 20 with liquid 50 is homogeneous and ensures nebulization by the entire central zone 20c. This radial supply of the membrane 20 from the chamber 42 to the central zone 20c is represented by arrows 56 in Figures 3b and 4b. Thus, whatever the level of liquid 50 in the reservoir 18 and especially whatever the orientation of the cigarette 10, the membrane 20 is supplied with liquid in a homogeneous manner. This reduces the variations in the quantity of nebulized liquid as the reservoir 18 empties.

[0037] 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 lowest part of the reservoir 18 to fill the chamber 42. It is then 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 not very full, communication of the liquid 50 with the chamber 42 is ensured.

[0038] 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 zone 20c of the membrane 20. It has been observed that on average a user's suction lasts of the order of a few seconds, typically 3 seconds. The chamber 42 is sized, in particular its outer diameter, to contain a volume equivalent to 30 to 50 seconds of suction, which represents more than ten suctions. During the period during which a user will carry out these ten suctions, the probability that he will modify the orientation of the cigarette 10 is very high and in particular that he will orient the cigarette 10 in a position where the level 52 of the liquid reaches the chamber 42 at least for the time necessary to fill the chamber 42.The orientations of the cigarette 10 shown in Figures 3a and 4a are only examples allowing to understand how the chamber 42 can be filled or not filled by means of the liquid 50 contained in the reservoir 18. In practice, during use. of the cigarette 10, the user regularly changes the orientation of the cigarette 10 in any intermediate orientation between those shown. Generally, it should be understood that the filling of the chamber 42 can be done when the level 52 of the liquid 50 reaches the chamber 42 and stops when the level 52 does not reach it.

[0039] During nebulization, it has been observed that some air bubbles tend to form on the face 20a of the membrane 20 at the central zone 20c in the film of liquid present on the membrane 20 on the side of the reservoir 18, that is to say on the face 20a of the membrane 20. It has been observed that the air bubbles do not form in the chamber 42, that is to say on the peripheral part of the membrane 20 but only at the central zone 20c. If these air bubbles remain in contact with the membrane 20, the nebulization is degraded. The presence of the orifice 46 facing the central zone 20c allows the evacuation of these air bubbles towards the reservoir 18 above the liquid level 52. The fact that the air bubbles can be evacuated through the orifice 46 makes it possible not to hinder the 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.It is not necessary to provide an additional orifice opening into chamber 42 and allowing the evacuation of any air bubbles.

Claims

CLAIMS Electronic cigarette (10; 100) comprising: - a reservoir (18) containing a liquid (50) capable of being nebulized, - 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) spaced apart 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) arranged 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), a 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 zone (20c) of the membrane (20).The electronic cigarette of claim 1, wherein a vertical orientation (12) of the electronic cigarette (10) is defined relative to a user in a standing position inhaling liquid nebulized through 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 lowest part of the reservoir (18). Electronic cigarette according to one of the preceding claims, in which the chamber (42) has a washer shape extending around the orifice (46). Electronic cigarette according to one of the preceding claims in which the chamber (42) has a circular outer contour (48) and in which the orifice (46) has a circular section concentric with the circular contour (48) of the chamber (42). Electronic cigarette according to one of the preceding claims in which the actuator (22) is fixed to the membrane (20) and in which the actuator (22) is pierced to the same dimensions as those of a section of the orifice (46).

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