Wick heater unit for an inhaler

Abstract

Wick heater unit (6) for an inhaler, preferably for an electronic cigarette product, wherein the heater (18) consists of at least one doped silicon layer which has through-channels (14) acting capillary on a liquid and is arranged on an outlet side of the liquid-conducting wick (9), characterized in that the wick (9) is made of a porous glass material, and in that the silicon layer is welded to the outlet side of the wick (9) by laser welding in such a way that the liquid conductivity of the through-channels (14) of the silicon layer is not impaired.

Description

The present invention relates to a wick heater unit for an inhaler having the features of the preamble of claim 1 and to a method of manufacturing a wick heater unit for an inhaler having the features of the preamble of claim 5.Conventional inhalers, such as electronic cigarette products, comprise replaceable consumer units having a liquid reservoir and a wick heater unit having a wick and a heater, preferably a resistance heater. A liquid is stored in the liquid reservoir, which is supplied to the heater through the wick from the liquid reservoir. The wick and the heater together form the wick-heater unit, in which the liquid is transported from the liquid reservoir by the capillary forces acting in the wick until it is heated in the heater and thus evaporated. The wick thus serves as a liquid-conducting connection between the liquid reservoir and the heater.A liquid reservoir having the features of the preamble of claim 1 is described, for example, in the applicant's patent application DE 10 2018 206 647.7, which has not yet been disclosed at the time of application.The wick is made of porous and / or capillary material which, due to capillary forces, is capable of passively replenishing liquid vaporized from the heater in sufficient quantity from the liquid reservoir to the heater to prevent the through-holes from idling and resulting problems. A large-scale list of suitable wick materials is known, for example, from the document US 2018 / 0296777 A1.The wick is advantageously made of an electrically non-conductive material in order to avoid undesired heating of liquid in the wick structure by current flow. The wick advantageously has a low thermal conductivity. The storage volume of the wick is in the range between 1 mm 3 and 10 mm 3, more preferably in the range between 2 mm 3 and 8 mm 3, even more preferably in the range between 3 mm 3 and 7 mm 3 and is, for example, 5 mm 3.A particularly easily controllable and thus advantageous simple implementation of the heater is the arrangement of an electrically conductive doped silicon layer on an outlet surface of the wick through which the liquid drawn in passes and in the process evaporates by heating. The electrically conductive silicon layer is itself permeable for the liquid to be evaporated, for example, through through-channels, and forms a planar resistance heater for the liquid to be evaporated when energized. Such an arrangement is shown, for example, in DE 10 2016 120 803 A1.Against this background, the object of the invention is to provide a wick heater unit for an inhaler, preferably an electronic cigarette product, which is intended to be able to be produced cost-effectively in large numbers, taking into account the high requirements for connection and liquid permeability. It is a further object to provide a cost-effective method for producing such a wick-heater unit.According to the invention, to achieve the objects, a wick-heater unit having the features of claim 1 and a method having the features of claim 5 are proposed. Further preferred further developments can be taken from the dependent claims, the figures and the associated description.According to the basic idea of the invention, a wick-heater unit is proposed, in which the wick is made from a porous glass material, and in which the silicon layer is welded to the outlet side of the wick by laser welding in such a way that the liquid conductivity of the through-channels of the silicon layer is not impaired.It has been found that the use of porous glass for the wick structure is particularly advantageous since the porous glass can already be produced in large numbers in the desired size and shape, for example in a sintering process, without the need for further post-processing. Furthermore, laser welding has proven to be a particularly cost-effective connection of the wick heater unit to be produced on a large scale, in that the silicon layer is melted by the laser in a targeted manner at the boundary layer to the wick formed from porous glass, and the cohesive connection to the wick is thus produced. Laser welding can be effected both through the silicon layer and through the wick, wherein the welding through the wick has the advantage that the laser does not penetrate the silicon layer and therefore only preferably fuses in the edge zone adjoining the wick. However, welding through the silicon layer may also be advantageous since the silicon layer is thinner, which is in turn more favorable for the design and the accuracy of the laser welding.It is further proposed that the silicon layer is formed by a polysilicon layer, which has proven to be particularly favorable with regard to the connection to be produced via the laser welding.It is further proposed that a silicon layer of the heater is undoped, and the doped silicon layer is provided between the undoped silicon layer and the wick as an electrically conductive intermediate layer.The advantage of the proposed solution is that the liquid is intentionally heated and evaporated in a layer between the wick and the silicon layer. The undoped silicon layer is no longer actively heated by the energization because of its nondoping, but rather is only indirectly heated by its thermally conductive properties via the electrically conductive intermediate step. The undoped silicon layer then serves for the further evaporation of the liquid or for the removal of the liquid evaporated in the electrically conductive intermediate layer. The evaporation zone is practically laid into the interior of the wick-heater unit. A further advantage of the wick heater unit proposed according to the invention is that the wick, the doped silicon layer and the undoped silicon layer can be connected to one another very easily by laser processing. This is because the laser can pass through the undoped silicon layer and is not attenuated in terms of energy during the pass because of the lack of doping of the silicon layer. The energy of the laser is then only converted into thermal energy in the doped silicon layer. This thermal energy then leads to a melting of the doped silicon layer and thus to a cohesive connection of the doped silicon layer to the wick and / or the undoped silicon layer. Such a connection process is also referred to as bonding. A further advantage which results from this is that the undoped silicon layer is intentionally not actively heated due to its lack of doping by the laser, so that melting of the through channels in the undoped silicon layer can be prevented. By a corresponding adjustment of the energy of the laser, it can furthermore be ensured that the doped silicon layer is only slightly melted without the through channels provided therein being melted.The doped silicon layer provided according to the invention is thus used not only for generating the necessary heat for evaporating the liquid, but additionally also for generating the heat for the bonding process and thus for connecting the doped silicon layer to the undoped silicon layer and / or the wick.Furthermore, the doped silicon layer can be formed by a coating of the wick and / or the undoped silicon layer.The doped silicon layer preferably forms the surface of the wick connected to the undoped silicon layer and / or the surface of the undoped silicon layer connected to the wick, so that the electrically conductive intermediate layer is arranged between the wick and the undoped silicon layer by connecting the undoped silicon layer to the wick.The electrically conductive intermediate layer is preferably liquid-permeable, so that the liquid can pass through the electrically conductive intermediate layer during evaporation.Furthermore, a method for producing a wick heater unit for an inhaler, preferably an electronic cigarette product, is proposed, in which the wick is manufactured according to the invention from a porous glass material, and the silicon layer is welded to the outlet side of the wick by laser welding without the liquid conductivity of the through channels of the silicon layer being impaired. The laser weld connection enables particularly cost-effective production of the wick-heater unit in mass production, wherein the energy introduced by the laser can be adjusted in a targeted manner such that the through-channels in the silicon layer do not melt in the process.It is further proposed that a silicon layer of the heater is undoped, and the doped silicon layer is provided between the undoped silicon layer and the wick, and the doped silicon layer is applied as an additional layer to the surface of the wick to be connected before the laser welding, and / or that the doped silicon layer is applied as an additional layer to the surface of the undoped silicon layer to be connected to the wick before the laser welding. The provision of the undoped silicon layer and the arrangement of the doped silicon layer between the wick and the undoped silicon layer is advantageous in that the laser weld connection is thus produced in a targeted manner in the boundary layer between the silicon layer and the wick.In this case, the doped silicon layer is preferably applied to the free surface of the undoped silicon layer to be connected to the wick before the through channels are introduced into the undoped silicon layer. This solution is advantageous in that the through-channels are not thereby closed by the doped silicon layer or the through-channels in the doped silicon layer can be simultaneously produced during the production of the through-channels in the undoped silicon layer.Furthermore, the wick, the undoped silicon layer and the doped silicon layer can be connected to one another in an oversized manner in a large-area composite structure in a first step, wherein the wick with the undoped silicon layer and the doped silicon layer are separated from the composite structure to the assembly size in at least one further step by a mechanical separating method. The wick-heater units are thus produced cost-effectively first in a large-area composite and only then cut out of the composite in terms of assembly size.In this case, the laser welding is preferably carried out by laser processing with a wavelength of greater than 1100 nm. The proposed wavelength is advantageous in this respect since active heating of the undoped silicon layer when passing through the laser can thereby be avoided. In the opposite direction, this furthermore results in the advantage that the energy loss of the laser during passage through the undoped silicon layer can be kept as low as possible, and the energy of the laser can be used at most for producing the connection via the electrically conductive intermediate layer.The invention is explained below with reference to preferred embodiments with reference to the attached figures. This shows FIG. 1 shows a consumption unit for an inhaler having a wick heater unit according to the invention, and FIG. 2 shows the wick-heater unit according to the invention as a single part.In FIG. 1, a consumption unit 1 can be seen, which is inserted into an inhaler, for example an electronic cigarette, for use. The consumption unit 1 comprises a liquid reservoir 2 for storing a liquid 3, which may be formed, for example, cylindrically with a circular cross section.A chimney 4 and an evaporator housing 5 are provided in the liquid reservoir 2, which supplement one another to form a flow connection of the consumer unit 1 from an air inlet side 16 to an air outlet side 17 through the liquid reservoir 2. The chimney 8 comprises a flow channel and is connected on its outer side in a liquid-tight manner to the front wall of the liquid reservoir 2. The evaporator housing 5 for its part likewise comprises a flow channel, not shown, which is connected in terms of flow to the flow channel of the chimney 4. Furthermore, the flow channel of the evaporator housing 5 is connected fluidically to the environment, so that the air flows from the inlet side 16 into the flow channel of the evaporator housing 5 when a suction force is exerted from the outlet side 17 in the arrow direction and flows further through the flow channel of the chimney 4 as far as the outlet side 17 until it finally flows out again at the outlet side 17 in the arrow direction. The evaporator housing 5 is connected on its outer side in a liquid-tight manner to the wall of the liquid reservoir 2 on the inlet side, so that the liquid reservoir 2 overall forms a container which is liquid-tight toward the environment.On the evaporator housing 5, a wick-heater unit 6 according to the invention is provided, which is shown in enlarged form in FIG. 2. The wick heater unit 6 comprises a wick 9 in the form of a porous glass body, a heater 18 formed by an electrically conductive intermediate layer 11 and an undoped silicon layer 10. The wick 9 is formed from porous glass with a plurality of very small interconnected hollow spaces 15 in which the liquid is drawn in by the capillary forces and temporarily stored. The wick 9 thus forms an intermediate storage means which ensures, on the one hand, that the liquid bears against the wick heater unit 6 independently of the orientation of the consumption unit 1, i.e. for example even when the consumption unit 1 is only partially filled and is arranged in such a way that the wick heater unit 6 is arranged on the upper side. On the other hand, the wick 9 can prevent the wick heater unit 6 from running dry until the last liquid is consumed, i.e. even if the liquid level is lowered to such an extent, when the wick heater unit 6 is arranged at the bottom, that the wick heater unit 6 is no longer completely covered with liquid.The electrical intermediate layer 11 and the undoped silicon layer 10 have a plurality of indicated through-channels 14, which are connected in terms of flow to the hollow spaces 15 of the wick 9 and open into the flow channel of the evaporator housing 5. The through channels 14 may be formed by etching the undoped silicon layer 10 and the electrical interlayer 11, for example.The wick heater unit 6 is connected to an external current source via the electrical intermediate layer 11 and is heated by the electrical resistor in the event of a preferably pulsed current flow. The undoped silicon layer 10 is intentionally not actively heated and only heats up due to its thermal conductivity via the contact with the electrically conductive heated intermediate layer 11.When the wick-heater unit 6 is activated, the electrical intermediate layer 11 is energized and the liquid present in the through-channels 14 evaporates. The vapor formed is transported further in the through channels 14 of the undoped and heated silicon layer 10 and finally introduced into the flow channel of the evaporator housing 5 and discharged into the environment via the flow channel of the chimney 4 or introduced into the mouth of the consumer in the case of an electric cigarette product. The wick 9 made of glass intentionally has no or a considerably lower thermal conductivity, as a result of which the transport direction of the vapor generated in the intermediate layer 11 in the direction of the undoped silicon layer 10 is predefined.Since the liquid in the intermediate layer 11 evaporates and is transported away via the undoped silicon layer 10, free cavities are formed in the intermediate layer 11 again and again here as a result of the preferred pulsing of the current application, through which cavities the liquid is sucked out of the cavities 15 of the wick 9 and finally out of the liquid reservoir 2 into the cavities 15 on account of the capillary forces.Owing to the solution according to the invention, the liquid is deliberately vaporized exclusively in the interior of the evaporator assembly 6, while the transport direction of the discharged vapor is predefined both by the suction force and the flow generated thereby in the flow channels of the chimney 4 and of the evaporator housing 5 and by the thermally conductive properties of the wick 9 and of the undoped silicon layer 10.The electrically conductive intermediate layer 11 can be formed by a metal layer and / or also by a doped silicon layer, preferably by a highly doped polysilicon layer. The term "metal layer" is intended to mean, in the sense of the invention, any electrically conductive layer with metallic portions, i.e. for example also alloys. The electrically conductive intermediate layer 11 can be arranged, attached or formed either on the wick 9 or on the undoped silicon layer 10 before the wick 9 is connected to the undoped silicon layer 10.The connection of the wick 9 to the undoped silicon layer 10 and the electrically conductive intermediate layer 11 provided therebetween can be effected advantageously from a process standpoint by means of laser processing, wherein the laser preferably has a wavelength of greater than 1100 nm and is directed through the undoped silicon layer 10 onto the electrically conductive intermediate layer 11. Since neither the undoped silicon layer 10 nor the wick 9 are electrically conductive, the electrically conductive intermediate layer 11 is heated exclusively or preferably. By the power of the laser, the intermediate layer 11 can be heated to such an extent that it easily fuses without the through channels 14 provided therein being melted in the intermediate layer 11 and in the undoped silicon layer 10. The melted material of the intermediate layer 11 then penetrates into the surface of the wick 9 and / or into the surface of the undoped silicon layer 10 and forms a cohesive connection. This connection process is also referred to as bonding.The connection of the wick 9 to the silicon layer by a laser has been described here in particular for the combination of an undoped silicon layer 10 with an electrically conductive intermediate layer 11, for example in the form of a doped silicon layer. However, it is also possible to provide on the wick 9 only a simple doped silicon layer without an undoped silicon layer 10, and to connect this doped silicon layer to the wick 9 by laser processing. The energy of the laser is adjusted in this case such that the doped silicon layer easily fuses and thereby forms the cohesive connection with the wick 9 (bonding), while the through-channels 14 are intentionally not fused.

Claims

Wick-heater unit (6) for an inhaler, preferably for an electronic cigarette product, wherein the heater (18) consists at least of a doped silicon layer which has through-channels (14) acting capillaryly on a liquid and is arranged on an outlet side of the liquid-conducting wick (9), characterized in that the wick (9) is manufactured from a porous glass material, and in that the silicon layer is welded to the outlet side of the wick (9) by laser welding in such a way that the liquid conductivity of the through-channels (14) of the silicon layer is not impaired.Wick heater unit (6) according to claim 1, characterised in that the silicon layer consists of polysilicon.Wick heater unit (6) according to one of the preceding claims, characterized in that a silicon layer (10) of the heater (18) is undoped, and the doped silicon layer is provided between the undoped silicon layer (10) and the wick (9) as an electrically conductive intermediate layer (11).Wick heater unit (6) according to Claim 3, characterized in that the doped silicon layer is formed by a coating of the wick (9) and / or of the undoped silicon layer (10).Method for producing a wick-heater unit (6) for an inhaler, preferably for an electronic cigarette product, wherein the heater (18) consists at least of a doped silicon layer which has through-channels (14) acting capillaryally on a liquid and is arranged on an outlet side of the liquid-conducting wick (9), characterized in that the wick (9) is produced from a porous glass material, and in that the silicon layer is welded to the outlet side of the wick (9) by laser welding without the liquid conductivity of the through-channels (14) of the silicon layer being impaired.Method according to Claim 5, characterized in that a silicon layer (10) of the heater (18) is undoped, and the doped silicon layer is provided between the undoped silicon layer (10) and the wick (9), and the doped silicon layer is applied as an additional layer to the surface of the wick (9) to be connected before the laser welding, and / or in that the doped silicon layer is applied as an additional layer to the surface of the undoped silicon layer (10) to be connected to the wick (9) before the laser welding.Method according to Claim 6, characterized in that the doped silicon layer is applied to the free surface of the undoped silicon layer (10) to be connected to the wick structure (9) before the through channels (14) are introduced into the undoped silicon layer (10).Method according to one of claims 6 or 7, characterised in that the wick (9), the undoped silicon layer (10) and the doped silicon layer are connected to one another in an oversized manner in a large-area composite structure in a first step, and the wick (9) with the undoped silicon layer (10) and the doped silicon layer are isolated from the composite structure to the assembly size in at least one further step by a mechanical separating method.Method according to one of Claims 5 to 8, characterized in that the laser welding is carried out by laser processing with a wavelength of greater than 1100 nm.

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