DE102020121369B4 - Evaporator device for an electric cigarette - Google Patents

Abstract

Evaporator unit (1) for an electric cigarette (17) having a tank (2), the tank (2) being designed such that a liquid can be accommodated in the tank (2), an evaporator head (3) with a receptacle for an electric operable heating resistor (10) and a delivery device for delivering the liquid from the tank (2) into the evaporator head (3), characterized in that the delivery device has a riser channel (4), at least one inlet opening (5) and at least one transition opening (6), the inlet opening (5) forming a fluid connection for the liquid from the tank (2) into the riser channel (4), the evaporator unit (1) having at least one inlet channel (13), the inlet channel (13) forming a fluid connection for the liquid from the inlet opening (5) into the riser channel (4), the inlet channel (13) being designed and arranged in such a way that the liquid in the inlet channel (13) is influenced by a capillary force from the inlet opening (5) into the riser channel (4) is conveyed, with the inlet channel (13) being designed as a disc-shaped gap surrounding the longitudinal axis (16), with the transition opening (6) forming a fluid connection for the liquid from the riser channel (4) into the evaporator head (3). andwherein the riser channel (4) has at least two opposing inner wall surfaces (7, 8), the inner wall surfaces (7, 8) being arranged and designed in such a way that the riser channel (4) has a defined gap dimension (9) and the liquid in the Rising channel (4) is promoted by a capillary force from the inlet opening (5) to the transition opening (6).

Description

The present invention relates to an evaporator unit for an electric cigarette having a tank, the tank being designed in such a way that a liquid can be held in the tank, an evaporator head with a receptacle for an electrically operable heating resistor, and a delivery device for delivering the liquid from the tank in the evaporator head.

With an electronic cigarette, the user inhales vapor that is produced when a liquid, the so-called liquid, is vaporized in an evaporator unit. On the one hand, the atomizer unit comprises a tank that is filled or can be filled with the liquid, on the other hand an evaporator head and a delivery device for the liquid.

The vaporizer head is designed in such a way that it can accommodate an electrically operable heating resistor, in particular a heating coil, which is connected to a power source. As soon as current flows through the heating resistor, it heats up and the liquid, which was pumped from the tank into the evaporator head by the conveyor, is vaporized by the heating of the heating resistor.

If the user draws in air at a mouthpiece of the electronic cigarette, air is guided along the heating resistor through an air flow channel. The air that the user breathes in therefore contains the vapor that is created by the evaporation of the liquid on the heating resistor.

Vaporizer units for electronic cigarettes are known from the prior art, in which the conveying device is formed by a liquid carrier in the form of a wick. The wick conveys the liquid from the tank into the evaporator head. There are different configurations for the wick. With regard to the material of the wick, cotton wool or stainless steel are used, for example; the possible geometries for the wick range from loose wadding, a strand of wadding, a stainless steel cable to a fine mesh made of stainless steel. With all designs of the wick, the liquid is conveyed from the tank into the evaporator head due to adhesion and capillary forces.

However, the use of a wick to promote the liquid has a disadvantageous effect on the practical use of an electronic cigarette. The loose wicks that are installed in conventional electronic cigarettes have to be changed or cleaned after a certain period of time. This is associated with additional effort for the user.

Furthermore, depending on the arrangement of the wick by the user, problems may arise during operation of the electronic cigarette. If, for example, a wick made of cotton wool is arranged too densely, the liquid flow can be interrupted. As a result, the heating resistor runs dry and a so-called dry hit occurs. This dry hit burns the wick. In addition to a severely clouded taste experience, the user is also exposed to a not inconsiderable amount of pollutants that are produced during combustion.

From the DE 698 04 385 T2 an aroma-generating device for enjoying a flavor inhalation or for enjoying simulated smoke is therefore known, the device having at least one liquid channel which has a first end section which is in fluid communication with the liquid and a second end section which is in fluid communication with a gas channel , wherein the liquid can be conveyed from a liquid container to the second end section by means of capillary force, wherein a heating device for heating and gasifying the liquid transported from the liquid container is attached to the second end section of the liquid channel.

A similar arrangement is also known from US 2016/0 360 786 A1, which relates to a two-stage atomizer with a primary heating element and a secondary heating element.

Next will be in the DE 20 2018 004 630 U1 an aerosol inhalation unit is described, with the outer supply lines of the liquid to be evaporated to the nozzle having the smallest possible cross-sections.
The present invention is therefore at least based on the object of providing an evaporator unit for an electric cigarette which offers easier use in practice.

Furthermore, the object of the present invention is to achieve greater application reliability of the evaporator unit.

At least one of the aforementioned objects is achieved according to the invention by an evaporator unit for an electric cigarette, the evaporator unit having a tank, the tank being designed in such a way that a liquid can be held in the tank, an evaporator head with a receptacle for an electrically operable heating resistor and has a conveying device for conveying the liquid from the tank into the evaporator head, the conveying device having a riser channel, has at least one inlet opening and at least one transition opening, with the inlet opening forming a fluid connection for the liquid from the tank into the riser channel, with the evaporator unit having at least one inlet channel, with the inlet channel forming a fluid connection for the liquid from the inlet opening into the riser channel, with the inlet channel is designed and arranged in such a way that the liquid in the inlet channel is conveyed by capillary force from the inlet opening into the riser channel, with the inlet channel being designed as a disc-shaped gap surrounding the longitudinal axis, with the transition opening providing a fluid connection for the liquid from the riser channel forms in the evaporator head and wherein the riser channel has at least two opposite inner wall surfaces, the inner wall surfaces being arranged and designed in such a way that the riser channel has a defined gap dimension and the liquid in the riser channel of a cap larkraft is promoted from the inlet opening to the transition opening.

According to the invention, the evaporator unit comprises a conveying device with a riser channel, which conveys the liquid decisively by capillary force from an inlet opening to a transition opening.

The riser channel is designed in such a way that it has at least two opposing inner wall surfaces, which result in the riser channel having a defined gap dimension. That is, in contrast to a wick, the distance between the two opposing inner wall surfaces is known exactly. With a wick made of stainless steel, for example, the gap size of the capillary channels is statistically distributed and usually unknown.

In contrast to a conveying device that has a wick as a riser channel, the riser channel according to the invention offers the advantage that the assembled vaporizer unit alone creates a cavity in which corresponding capillary forces act, which convey the liquid from the tank into the vaporizer head. There is no need to change or clean an additionally built-in wick and the use is therefore more convenient in comparison to an evaporator unit of an electric cigarette known from the prior art.

The riser channel according to the invention becomes soiled less quickly than a wick, since the liquid flows through evenly due to the defined gap size. Wicks, on the other hand, also have capillary channels with a gap dimension that tends to be almost zero. Blockages occur more quickly in such channels. In addition, the wicks can become clogged when the cotton wool is placed on the wick or the cotton wool is replaced several times and the cotton wool is pressed onto the wick as a result. The riser channel according to the invention, on the other hand, only very rarely needs to be cleaned, since there are no narrow capillary channels and there are no wire fiber ends of a wick on which the wadding can get caught. The cleaning of the riser channel according to the invention is easy to carry out due to the geometry.

In addition, since the evaporator unit according to the invention does not use a wick, there is less waste.

The configuration of the evaporator unit according to the invention allows the liquid flow to be adjusted precisely by previously defined dimensions of the riser channel and the inlet and transition openings, so that the risk of a dry hit is minimized.

In one embodiment of the evaporator unit, the gap dimension of the riser channel is at least 0.15 mm, preferably at least 0.25 mm, which is a further difference from a conveying device implemented as a wick. As explained above, wicks made of stainless steel or cotton wool, for example, have significantly smaller gap dimensions, which lead to faster contamination of the conveying device.

In a further embodiment of the evaporator unit, the riser channel has a constant gap dimension, in contrast to a wick.

In a further embodiment of the evaporator unit, the riser channel has a gap dimension which is 0.45 mm or smaller, preferably 0.35 mm or smaller.

The inlet opening forms a fluid connection for the liquid from the tank into the riser channel and the transition opening forms a fluid connection from the riser channel into the evaporator head. In one embodiment of the evaporator unit according to the invention, the width of the inlet opening is between 0.3 mm and 0.5 mm, the width being selected such that a sufficient quantity of liquid can be conveyed and a dry hit is prevented.

The transition opening makes the liquid conveyed through the riser channel available in the atomizer head, so that it can be vaporized on an electrically operable heating resistor.

In a further embodiment, the inner wall surfaces of the riser channel on an inner inner wall surface and an outer inner wall surface, wherein the inner inner wall surface and the outer inner wall surface are arranged concentrically around a longitudinal axis of the evaporator unit that the riser channel is designed as a circumferential gap.

This has the advantage that the evaporator unit has only one riser channel, which, however, offers the maximum possible volume while at the same time maintaining the capillary force, so that the largest possible amount of liquid can be conveyed to the evaporator head. In this way, the electrically operable heating resistor is supplied with sufficient liquid at all times.

The gap can, for example, have the form of an annular gap, in particular an annular gap.

In a further embodiment of the present invention, the riser channel has, at an end of the riser channel at a minimum distance from the evaporator head, a region with a distance from the longitudinal axis of the evaporator unit that increases in the direction of the evaporator head.

On the one hand, this offers the technical advantage that the delivery device can be connected more easily to the evaporator head, i.e. there is sufficient space in the transition area of the delivery device and the evaporator head to accommodate a heating resistor and the associated electrical supply lines.

On the other hand, in a further embodiment, one or more transition openings are arranged in the region of the riser channel which is at a minimum distance from the evaporator head and whose distance from the longitudinal axis of the evaporator unit increases in the direction of the evaporator head. If the transition opening is projected parallel to the longitudinal axis onto this area of the riser channel which is inclined to the longitudinal axis, a maximum area for the transition opening is achieved.

This in turn means that a larger amount of liquid can be provided at the transition to the evaporator head at the same time.

In one embodiment of the evaporator unit according to the invention, the width of the transition opening is between 0.8 mm and 1.2 mm.

If, on the other hand, a riser channel does not have such a sloping area, then the area of the transition opening, which is also arranged at the end of the riser channel at a minimum distance from the evaporator head, corresponds only to the cross section of the riser channel. As a result, only a smaller amount of liquid can be made available at the transition opening. The risk of a dry hit increases.

In addition, it would be conceivable to arrange the transition opening on an inner wall surface of the riser channel. However, the larger the transition opening is selected in this case, the lower the capillary capacity of the riser channel. In addition, the connection from the transition opening to the evaporator head is more difficult, so that this is not a preferred arrangement of the transition openings.

In a further embodiment, the evaporator unit has at least one wadding receptacle for accommodating a wadding that adjoins the transition openings of the delivery device and the wadding receptacle forms a fluid connection for the liquid from the transition opening into the evaporator head. Due to the large-area configurations of the transition openings described in the previous embodiment, the wadding holder can also be made correspondingly large.

In one embodiment, the wadding receptacle has a curved, slot-like recess which preferably extends at least 90° around a longitudinal axis of the evaporator unit and in which a wadding can be arranged. In this way, the largest possible contact surface for the wadding is made possible, so that as much liquid as possible, which is made available at the transition opening, is transported to the heating resistor at the same time.

The wadding receptacle can be filled with wadding, in particular a strand of wadding, with the wadding conveying the amount of liquid provided at the transition opening to the electrically operable heating resistor due to adhesive forces. For this purpose, in one embodiment, the wad is arranged such that it extends in the wad receptacle and out of the wad receptacle to the heating resistor.

According to the invention, the wadding is not part of the conveying device, as for example in various evaporator units that are known from the prior art, but merely a liquid carrier for transporting the liquid from the transition opening to the heating resistor.

In one embodiment, the wadding receptacle and an end of the tank facing the wadding receptacle are designed in such a way that tank venting is ensured. As a result, a pressure equalization can take place, so that on the one hand there is an overpressure when filling the tank with liquid and on the other hand there is a negative pressure when the tank is emptied by sucking in the liquid via the riser channel is balanced. Likewise, air bubbles, which can form in the tank as it is emptied, can escape and thus do not impede the flow of liquid.

According to the invention, the evaporator unit has at least one inlet channel, with the inlet channel forming a fluid connection for the liquid from the inlet opening into the riser channel. In other words, the liquid does not run directly from the tank into the riser channel, but first into the inlet channel located in between.

In a further embodiment of the evaporator unit, the inlet opening is arranged in such a way that it is located in an inner wall surface of the tank which is at a maximum distance from the evaporator head, preferably in a bottom of the tank. Accordingly, the inlet channel is likewise at a maximum distance from the evaporator head, preferably arranged below the bottom of the tank.

In this embodiment, the inlet channel runs essentially perpendicularly to the longitudinal axis of the evaporator unit and essentially parallel to the bottom of the tank. The gap dimension of the inlet channel also extends essentially parallel to the longitudinal axis of the evaporator unit. This arrangement of the inlet opening and the inlet channel offers the advantage that the tank of the vaporizer unit can be completely emptied before the liquid has to be refilled. In addition, the promotion of the liquid in the riser channel is supported by the hydrostatic pressure of the liquid in the tank.

According to the invention, the inlet channel is designed in such a way that it is designed as a disk-shaped gap surrounding the longitudinal axis, which is located at a maximum distance from the evaporator head below the base. The gap dimension of the inlet channel extends essentially parallel to the longitudinal axis of the evaporator unit. Similar to the embodiment of the riser channel as a circumferential gap, this offers the advantage that the largest possible volume of the inlet channel can be achieved, so that a sufficient quantity of the liquid is conveyed during operation of the electric cigarette.

According to the invention, the gap size of the inlet channel is chosen such that the liquid is conveyed due to capillary forces. When choosing the gap between 0.15 mm and 0.45 mm, preferably between 0.25 mm and 0.35 mm, so that capillary forces act, there is the advantage that the liquid is independent of the orientation of the electric cigarette in space can be pumped from the tank into the riser channel.

In a further embodiment, the inlet channel has a gap which increases towards the longitudinal axis of the evaporator unit. In other words, the inlet channel is funnel-shaped, which supports the capillary forces that pull the liquid into the riser channel.

In a further embodiment of the invention, the inlet channel is designed in such a way that it is connected to the rising channel via at least one opening in the outer inner wall surface of the rising channel if the rising channel is designed as a circumferential gap.

In a further embodiment, the opening between the inlet duct and the riser duct is designed in such a way that it is a slot in the outer inner wall surface of the riser duct, which annularly surrounds the longitudinal axis. As with the design of the transition openings between the riser channel and the evaporator head, here too there is the advantage of a maximum possible passage area of the opening, which ensures a uniform and sufficient flow of liquid.

In a further embodiment of the present invention, the diameter of the inlet opening and/or the transition opening is selected such that it is larger than the gap dimension of the riser channel and/or the inlet channel. This embodiment also takes into account the fact that the largest possible amount of liquid should be pumped, but at the same time the capillary forces of the riser and/or the inlet channel must be sufficiently large to be able to pump a sufficient amount of liquid from the tank into the evaporator head.

In a further embodiment, a surface of the riser channel, formed from the total number of all inner wall surfaces of the riser channel, is structurally and materially constituted in such a way that, if no capillary force is acting, a macroscopic contact angle occurs when the liquid comes into contact with a flat, extensive surface of the riser channel forms between the liquid and the surface of the riser channel, in particular a macroscopic contact angle of 40° or more.

This feature distinguishes the gap according to the invention from a conveyor in the form of a wick. If you look at the wick as a whole, it has a porous surface structure. This applies to cotton wool, a stainless steel cable and a stainless steel screen mesh. In the case of a porous surface, no macroscopic contact angle forms between the liquid and the extensive surface structure of the wick. On the contrary they are In this case, adhesive forces are so strong that complete wetting develops.

In the present invention, on the other hand, the riser channel is designed in such a way that, if no capillary force is acting, complete wetting does not form when the liquid comes into contact with a macroscopic surface of the material of the riser channel.

For this reason, the inner wall surfaces of the riser channel have an average peak-to-valley height R _z of at most 4.5 μm.

Furthermore, in one embodiment, the tank is arranged in a ring around the riser channel. In addition, the tank can be refilled, which also reduces waste.

In addition, the evaporator head according to the invention has a receptacle for an electrically operable heating resistor. This recording offers the possibility of mechanically fastening the heating resistor in the evaporator head, for example by means of a clamping device. At the same time, the mount provides an interface for the electrical supply of the heating resistor.

In one embodiment, a heating resistor is connected to the receptacle. This heating resistor can be designed in the form of a spiral. Corresponding metals such as stainless steel or metal alloys such as chromium-nickel compounds are used as the material for the heating resistor, which have a high specific resistance and efficiently convert the electrical current into heat.

In a further embodiment, the evaporator head according to the invention is connected to a power source, with the power source being located at a maximum distance from the evaporator head. The power source is in an electrically conductive connection with the holder for the heating resistor in the evaporator head.

• 1 ist eine schematische Schnittansicht eines Teils einer elektrischen Zigarette mit einer erfindungsgemäßen Ausführungsform der Verdampfereinheit parallel zu der Längsachse der Verdampfereinheit.
• 2 ist eine schematische Schnittansicht eines Teils einer elektrischen Zigarette mit einer erfindungsgemäßen Ausführungsform der Verdampfereinheit senkrecht zu der Längsachse der Verdampfereinheit in der Mitte der Fördereinrichtung.
• 3 ist eine schematische Schnittansicht eines Teils einer elektrischen Zigarette mit einer erfindungsgemäßen Ausführungsform der Verdampfereinheit senkrecht zu der Längsachse der Verdampfereinheit im Bereich der Watteaufnahme.
• 4 ist eine schematische, dreidimensionale Explosionsansicht eines Teils einer elektrischen Zigarette mit einer erfindungsgemäßen Ausführungsform der Verdampfereinheit.
• 5 ist eine schematische Skizze einer elektrischen Zigarette.

Further advantages, features and application possibilities of the present invention become clear from the following description of an embodiment and the associated figures. In the figures, the same elements are denoted by the same reference symbols.

• 1 12 is a schematic sectional view of part of an electronic cigarette with an embodiment of the vaporizer unit according to the invention, parallel to the longitudinal axis of the vaporizer unit.
• 2 12 is a schematic sectional view of part of an electronic cigarette with an embodiment of the vaporizer unit according to the invention, perpendicular to the longitudinal axis of the vaporizer unit in the center of the conveyor.
• 3 is a schematic sectional view of a part of an electric cigarette with an embodiment of the vaporizer unit according to the invention, perpendicular to the longitudinal axis of the vaporizer unit in the area of the wadding receptacle.
• 4 Fig. 12 is a schematic, three-dimensional, exploded view of part of an electronic cigarette with an embodiment of the vaporizer unit according to the invention.
• 5 is a schematic sketch of an electronic cigarette.

According to the 1 until 3 the evaporator unit 1 has a tank 2 which is arranged concentrically around the longitudinal axis 16 and in which the liquid can be accommodated. On the bottom 14 of the tank 2 there is an inlet opening 5 which forms a fluid connection for the liquid from the tank 2 into the inlet channel 13 . The inlet channel 13 running perpendicularly to the longitudinal axis 16 is connected to the riser channel 4 through an opening 15 so that the liquid flows from the inlet channel 13 into the riser channel 4 .

The tank 2 has a tank ventilation 20 at an end remote from the inlet channel 13 . As a result, a pressure equalization can take place, so that on the one hand an overpressure when filling the tank with liquid and on the other hand a negative pressure when emptying the tank by sucking in the liquid via the riser channel is compensated. Likewise, air pockets can escape from the tank 2 via a cotton receptacle 11 via the tank vent 20 .

The inlet channel 13 is designed as a disc-shaped gap surrounding the longitudinal axis 16 below the bottom 14 of the tank 2 and runs essentially parallel to the bottom 14 of the tank 2. The gap dimension of the inlet channel 13 is defined by the distance between the inner wall surfaces of the inlet channel 13 and runs essentially parallel to the longitudinal axis 16 of the evaporator unit 1. In addition, the gap dimension of the inlet channel 13 increases towards the longitudinal axis 16.

The inlet channel 13 is connected to the riser channel 4 via an opening in the outer inner wall surface 8 of the riser channel 4 . The opening between the inlet channel 13 and the riser channel 4 is designed in such a way that it forms a ring around the longitudinal axis 16 surrounding slot in the outer inner wall surface 8 of the riser channel 4 is.

The riser channel 4 has two opposing inner wall surfaces 7 and 8, with an inner inner wall surface 7 and an outer inner wall surface 8 being arranged concentrically around the longitudinal axis 16 of the evaporator unit 1 in such a way that the riser channel 4 is designed as a circumferential, annular gap. The riser channel 4 also has a defined and constant gap size 9 . The gap size 9 is defined as the distance between the inner inner wall surface 7 and the outer inner wall surface 8. The gap size 9 is essentially constant over the entire length of the riser channel 4.

In addition, the distance between the riser channel 4 and the longitudinal axis 16 increases in a direction toward the evaporator head 3 , with the transition openings 6 being located in this region 12 of the riser channel 4 that is inclined relative to the longitudinal axis 16 .

A cotton-wool receptacle 11 is connected to these transition openings 6 so that the liquid that has risen in the riser channel 4 can be conveyed into the evaporator head 3 through the transition opening 6 and a cotton wool that can be introduced into the cotton-wool receptacle 11 .

In the evaporator head 3 there is a heating coil 10 in the vicinity of which the cotton is arranged, which is guided from the transition opening 6 through the cotton holder 11 to the heating coil 10 . The wadding absorbs the liquid provided at the transition opening 6 and conveys it to the heating coil 10.

4 shows an exploded view of an embodiment of the evaporator head 3 according to the invention. Before the electric cigarette 17 is put into operation, cotton wool is placed in the cotton-wool holder 11, which rests on a flower-shaped structure that forms the recesses for the tank ventilation 20 and extends from the cotton-wool holder 11 to the heating coil 10 and thus the liquid from the transition opening 6 transported to the heating coil 10, where the liquid is vaporized.

5 shows a schematic sketch of an electric cigarette 17 with an evaporator unit 1 according to the invention, a power supply 19, an air flow channel and a mouthpiece 18. The power supply 19 is connected to the heating coil 10 via an electrical connection, so that the heating coil 10 can be heated when a current flows . Air is guided along the heated heating coil 10 through an air flow channel and the user draws it on through a mouthpiece 18 .

Since the liquid provided by the conveying device according to the invention is vaporized at the heating coil 10 at the same time, the user inhales a corresponding vapor of the liquid when he draws on the mouthpiece 18 .

For the purposes of the original disclosure, it is pointed out that all the features that are apparent to a person skilled in the art from the present description, the drawings and the claims, even if they were specifically described only in connection with certain other features, both individually and in any configuration can be combined with other features or groups of features disclosed here, unless this has been expressly excluded or technical circumstances make such combinations impossible or pointless. On the other hand, the comprehensive, explicit presentation of all conceivable combinations of features is omitted here only for the sake of brevity and legibility of the description.

While the invention has been shown and described in detail in the drawings and the foregoing description, this illustration and description is by way of example only and is not intended to limit the scope as defined by the claims. The invention is not limited to the disclosed embodiments.

Modifications to the disclosed embodiments will become apparent to those skilled in the art from the drawings, the specification, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plural. The mere fact that certain features are claimed in different claims does not preclude their combination. Reference signs in the claims are not intended to limit the scope.

Reference List

1

evaporator unit

2

tank

3

atomizer head

4

riser channel

5

inlet opening

6

transition opening

7

inner interior wall surface

8th

outer inner wall surface

9

gap size

10

heating coil

11

cotton intake

12

Area with increasing distance to the longitudinal axis

13

inlet channel

14

bottom of the tank

15

opening

16

longitudinal axis

17

Electric cigarette

18

mouthpiece

19

power supply

20

tank ventilation

Claims (12)

Evaporator unit (1) for an electric cigarette (17) having a tank (2), the tank (2) being designed such that a liquid can be accommodated in the tank (2), an evaporator head (3) with a receptacle for one electrically operable heating resistor (10) and a delivery device for delivering the liquid from the tank (2) into the evaporator head (3), characterized in that the delivery device has a riser channel (4), at least one inlet opening (5) and at least one transition opening (6 ), wherein the inlet opening (5) forms a fluid connection for the liquid from the tank (2) into the riser channel (4), the evaporator unit (1) having at least one inlet channel (13), the inlet channel (13) having a fluid connection for the liquid from the inlet opening (5) into the riser channel (4), the inlet channel (13) being designed and arranged in such a way that the liquid in the inlet channel (13) is influenced by a capillary force from the inlet opening (5) is conveyed into the riser channel (4), with the inlet channel (13) being designed as a disc-shaped gap surrounding the longitudinal axis (16), with the transition opening (6) providing a fluid connection for the liquid from the riser channel (4) into the evaporator head (3 ) and wherein the riser channel (4) has at least two opposite inner wall surfaces (7, 8), the inner wall surfaces (7, 8) being arranged and designed in such a way that the riser channel (4) has a defined gap dimension (9) and that Liquid is conveyed in the riser channel (4) by a capillary force from the inlet opening (5) to the transition opening (6). evaporator unit claim 1 , wherein the gap dimension (9) of the riser channel (4) is at least 0.15 mm, preferably at least 0.25 mm. Evaporator unit (1) according to one of the preceding claims, wherein the inner wall surfaces (7, 8) of the riser channel (4) have an inner inner wall surface (7) and an outer inner wall surface (8), the one inner inner wall surface (7) and one outer inner wall surface (8) are arranged concentrically around a longitudinal axis (16) of the evaporator unit (1) in such a way that the riser channel (4) is designed as a circumferential gap. Evaporator unit (1) according to one of the preceding claims, wherein the riser channel (4) at an end of the riser channel (4) at a minimum distance from the evaporator head (3) has an area with a distance from the longitudinal axis (16 ) of the evaporator unit (1). Evaporator unit (1) after claim 4 , wherein the at least one transition opening (6) is arranged in the region of the riser channel (4) at a distance from the longitudinal axis (16) that increases in the direction of the evaporator head (3). Evaporator unit (1) according to one of the preceding claims, wherein the evaporator unit (1) further has at least one wadding receptacle (11) for accommodating a wadding, the wadding receptacle (11) providing a fluid connection for the liquid from the transition opening (6) into the evaporator head ( 3) forms. Evaporator unit (1) according to one of the preceding claims, wherein the at least one inlet opening (5) is arranged in an inner wall surface of the tank (2) at a maximum distance from the evaporator head (3), preferably in a bottom of the tank (14). Evaporator unit (1) according to any one of the preceding claims as far as from claim 3 dependent, the inlet channel (13) being connected to the riser channel (4) via at least one opening (15) in the outer inner wall surface (8) of the riser channel (4). Evaporator unit (1) after claim 8 , wherein the opening (15) is a longitudinal axis (16) annularly surrounding slot in the outer inner wall surface of the riser channel (4). Evaporator unit (1) according to one of the preceding claims, wherein the diameter of the at least one inlet opening (5) and/or the at least one transition opening (6) is larger than the gap dimension (9) of the riser channel (4) and/or of the inlet channel (13 ). Evaporator unit (1) according to one of the preceding claims, wherein the gap dimension (9) of the riser channel (4) is 0.45 mm or smaller, preferably 0.35 mm or smaller. Evaporator unit (1) according to any one of the preceding claims, wherein a surface of the riser channel (4), formed by the total number of all inner wall surfaces (7, 8) of the riser channel (4), is structured and material such that when no capillary force acts When the liquid comes into contact with a flat, extensive surface of the riser channel (4), a macroscopic contact angle forms between the liquid and the surface of the riser channel (4), in particular a macroscopic contact angle of 40° or greater.

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