Method for cleaning a surface with the aid of an atmospheric plasma jet and use of a device comprising a plasma source for cleaning a surface

Abstract

The invention relates to a method (200, 600, 700) for cleaning a surface (204, 602, 702) with the aid of an atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709), the surface (204, 602, 702) being contaminated with at least one at least partly organic substance (202), wherein the method is characterized in that water (216, 336, 540) is introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709), and in that the surface (204, 602, 702) is simultaneously subjected to the water (216, 336, 540) introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709) and to the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709). The invention also relates to a use of a device comprising a plasma source configured to generate an atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) and comprising a supply line element (10, 212, 330, 436, 528) configured to introduce water (216, 336, 540) into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709), for cleaning a surface (204, 602, 702), in particular a surface (204, 602, 702) of a battery cell (604), the surface (204, 602, 702) being contaminated with at least one at least partly organic substance (202).

Description

[0001] Method for cleaning a surface using an atmospheric plasma jet and use of a device with a plasma source for cleaning a surface

[0002] The present invention relates to a method for cleaning a surface using an atmospheric plasma jet, wherein the surface is contaminated with at least one at least partially organic substance. The present invention further relates to the use of a device comprising a plasma source configured to generate an atmospheric plasma jet and a supply element configured to introduce water into the atmospheric plasma jet.

[0003] As part of a manufacturing process, for example in the metalworking industry or during battery production, or before carrying out a certain surface treatment, it may be necessary or at least desirable to clean a surface. In particular, in the case of surfaces that are coated with oil or an at least partially organic substance, for example as a result of a previous process step, it may be desirable to remove the oil or organic substance. For example, in the case of battery cells intended for arrangement in a battery pack, the surface of the individual battery cells should be freed of organic substances before assembly as a battery pack. At the same time, high temperatures and voltage transfer to the battery cell should be avoided.

[0004] For example, attempts have already been made in the past using mechanical removal by abrasion or chemical cleaning with solvents. The use of solvents has the disadvantage that it is often harmful to the environment. Furthermore, both known methods can potentially damage the treated surface. Against this background, the present invention seeks to provide an improved method for cleaning a surface contaminated with an organic substance.

[0005] The above-mentioned object is achieved according to the invention by a method for cleaning a surface using an atmospheric plasma jet, wherein the surface is contaminated with at least one at least partially organic substance, in that water is introduced into the atmospheric plasma jet and that the surface is simultaneously exposed to the water introduced into the atmospheric plasma jet and to the atmospheric plasma jet.

[0006] In addition, the above-mentioned object is further achieved according to the invention by using a device with a plasma source configured to generate an atmospheric plasma jet and with a supply element configured to introduce water into the atmospheric plasma jet, for cleaning a surface, in particular a surface of a battery cell, wherein the surface is contaminated with at least one at least partially organic substance.

[0007] It has been shown that by simultaneously exposing the surface to an atmospheric plasma jet and water, organic contaminants can be removed more effectively than by exposing the surface without water. In particular, tests have shown that exposing a surface contaminated with an organic substance to an atmospheric plasma jet without water partially removed the contamination, but caused the remaining contamination to harden. When exposing a comparable surface with a comparable level of contamination to an atmospheric plasma jet and water simultaneously, an improved cleaning result was observed without hardening.

[0008] The method or use according to the present disclosure can be carried out under normal atmospheric conditions, thus eliminating the need for a special gas atmosphere. Furthermore, the use of hazardous solvents can be avoided, allowing the method to be implemented simply and safely.

[0009] In addition, the water cools the surface to be cleaned, which is advantageous, for example, when cleaning the surface of a battery cell. This allows a surface temperature of 60°C or less to be maintained, thus preventing the risk of damage or fire.

[0010] Furthermore, a device, in particular a plasma nozzle, can be used to carry out the method or during use, which allows a transfer of less than 1 V to the surface to be cleaned. Thus, the method is particularly suitable for cleaning battery cell surfaces.

[0011] The method and / or use can be used to clean surfaces or to free them of organic substances which will be provided with an adhesive, for example, in a later treatment process. This makes it possible to remove, for example, oil which would hinder the adhesion of the adhesive to the surface. Likewise, a surface can be treated with the present method and / or use before or after it is subjected to a welding process in order to prevent defects in a weld seam or to clean a weld seam. Another example of an application for the present method and / or use is surface cleaning before a painting process in order to improve the painting result. The term substance which is at least partially organic can be understood to mean a substance in liquid or solid form which contains at least one chemical compound having an organic portion.Examples of such substances include oils, greases, silicones, lubricants, release agents for plastics or metal processing, rolling oils, and coolants, although this list is not exhaustive. Depending on the surface tension, the substance can be distributed over the entire surface or in specific areas. Thus, the substance can be present as a coating distributed essentially homogeneously across the surface or distributed in specific areas, for example, as patches.

[0012] The water introduced into the atmospheric plasma jet may in particular be demineralized water or a gas or liquid mixture containing water molecules.

[0013] According to the invention, water is introduced into the atmospheric plasma jet. For this purpose, the water can be introduced into the already generated plasma jet. Alternatively or additionally, water can be used to generate the plasma jet, so that the plasma jet itself contains water.

[0014] The supply element is preferably designed to conduct water in gaseous or liquid form. The water can be in the form of mist, water vapor, liquid, a portion of a solution, or a gas mixture, although this list is not exhaustive. The supply element can be fluidically connected to a plasma source, for example to a nozzle chamber or to a swirl device of a plasma source. Alternatively or additionally, the supply element can be designed separately from a plasma nozzle, for example as a spray or drip device. Various embodiments of the method and use are described below, wherein the individual embodiments each apply independently of one another to the method and use. Furthermore, the individual embodiments can be combined with one another as desired.

[0015] In one embodiment of the method, the water is introduced into the atmospheric plasma jet in a liquid state together with a carrier gas.

[0016] This ensures simultaneous exposure of the surface to be cleaned to water and the atmospheric plasma jet. The water and carrier gas can be introduced into the atmospheric plasma jet at a predetermined concentration or mixing ratio, ensuring that the surface to be cleaned is exposed to a controlled amount of water.

[0017] Air, especially compressed air, can be used as a carrier gas, although other gases such as nitrogen or argon are also conceivable.

[0018] In addition, the atmospheric plasma jet can be generated with nitrogen (N2), argon, air, forming gas (nitrogen-hydrogen mixture) or an argon-hydrogen mixture.

[0019] In one embodiment of the method, the water introduced into the atmospheric plasma jet interacts at least partially with the atmospheric plasma jet, causing the water to at least partially evaporate. Upon contact with the surface, the water introduced into the atmospheric plasma jet is applied to the surface partly in a gaseous state and partly in a liquid state. Thus, the surface to be cleaned can be exposed to water that has reacted with the plasma jet as well as water in droplet form. Tests have shown an enhanced cleaning effect on organic substances for such a method.

[0020] In one embodiment of the method, it is provided that the water is introduced into the atmospheric plasma jet at a flow rate in the range of equal to or more than 0.1 grams per minute, in particular in the range of equal to or more than 2 grams per minute, preferably in particular in the range of equal to or more than 5 grams per minute, particularly preferably in the range of equal to or more than 10 grams per minute, more preferably in the range of 0.1 to 100 grams per minute.

[0021] It has been shown that using such water volumes can achieve improved cleaning results even with increased amounts of organic substances. Thus, with the specified water volumes, one to several grams of organic matter per square meter of a surface to be cleaned can be removed. In particular, it has been observed that higher flow rates and higher water volumes can remove larger amounts of organic matter.

[0022] In one embodiment of the method, the water is introduced into the atmospheric plasma jet before the atmospheric plasma jet emerges from a plasma nozzle used to generate the atmospheric plasma jet.

[0023] This allows for a compact design, which can prove advantageous, for example, when retrofitting an existing production or treatment line. It also makes it easy to coordinate the simultaneous exposure of the surface to water and the atmospheric plasma jet. In one embodiment of the process, the water is introduced into the atmospheric plasma jet after the atmospheric plasma jet emerges from a plasma nozzle used to generate the atmospheric plasma jet.

[0024] This allows a simple plasma source or plasma nozzle to be used together with a separate feed element. For example, an existing plasma nozzle can be retrofitted to generate an atmospheric plasma jet by adding a separate feed element. Furthermore, a commercially available feed element, such as a spray device, can be used to introduce water after the plasma jet exits the plasma source. Overall, this makes the process simple and cost-effective.

[0025] In one embodiment of the method, it is provided that, in order to introduce water into the atmospheric plasma jet, the water is introduced as a working gas into a plasma nozzle used for generating the atmospheric plasma jet, and that, in order to apply pressure to the surface, the surface is exposed to the atmospheric plasma jet generated on the basis of water as a working gas simultaneously with the water introduced into the atmospheric plasma jet and with the atmospheric plasma jet.

[0026] This ensures that the surface to be cleaned is exposed to the water and the atmospheric plasma jet at the same time.

[0027] In this embodiment, the atmospheric plasma jet is generated at least partially based on the water introduced into the plasma nozzle. The water introduced as the working gas can react chemically or physically at least partially due to an arc-like electrical discharge caused to generate the plasma jet. In particular, the water can be introduced into the plasma nozzle as the working gas and emerge from the plasma nozzle partly in gaseous form and partly in liquid form. This can occur by precipitation of the water or the working gas on an inner wall of the plasma nozzle. Emergence of water from the plasma nozzle in liquid form can be caused by introducing the water into the plasma nozzle in increased quantities.

[0028] The water, as steam or mist, can be introduced into the plasma nozzle together with a carrier gas, which can be air, argon, or nitrogen, for example. Thus, the working gas provided for generating the plasma jet can contain water and at least one carrier gas.

[0029] In one embodiment of the method, the water is introduced as mist or water vapor into the plasma nozzle used to generate the atmospheric plasma jet.

[0030] This allows simple, familiar means to be used to introduce water as a carrier gas into the plasma nozzle. For example, a standard steam cleaner can be used to generate steam.

[0031] The term "water vapor" refers specifically to the gaseous form of water. In contrast, the term "fog" refers to water as fine liquid droplets.

[0032] In one embodiment of the method, the plasma jet is moved relative to the surface when the surface is exposed, and / or the surface is moved relative to the plasma jet when the surface is exposed. This allows a surface to be treated extensively with the water and the plasma jet, thus allowing the entire outer surface of an object to be cleaned.

[0033] For example, an axially symmetrical surface of a battery cell can rotate relative to a plasma nozzle and at the same time the plasma nozzle can be moved back and forth along the axis of symmetry of the battery cell.

[0034] In one embodiment of the method, it is provided that the at least one at least partially organic substance reacts at least partially with the atmospheric plasma jet and mixes with the water or dissolves therein.

[0035] By applying the atmospheric plasma jet, the at least partially organic substance is modified. For example, if the substance contains an oil, it can acquire polar components under the influence of the atmospheric plasma jet. Chemical functional groups are introduced into the oil, which improve its solubility in water, allowing the modified substance to mix, blend, or even dissolve in the water applied to the surface.

[0036] In one embodiment of the method, it is provided that the surface is contaminated with at least one further substance, wherein the at least one further substance contains at least one element of the list: protein, water-soluble salt and / or oil, and that the at least one further substance mixes with the water or dissolves therein.

[0037] By exposing the surface to water, both organic and water-soluble contaminants can be removed.

[0038] In particular, water-soluble contaminants can mix with or dissolve in the water on the surface, resulting in an overall improved cleaning result. For example, this process can remove both grease and fingerprints from a surface.

[0039] Examples of water-soluble salts are: sodium chloride, potassium chloride, nitrates, generally salts containing acetate, perchlorate or nitrate as anion and salts containing potassium or sodium as cation.

[0040] In one embodiment of the method, it is provided that after the application, the surface is freed from the water and the at least partially organic substance and, if appropriate, from at least one further substance.

[0041] When the surface to be cleaned is exposed to water in liquid form, the surface becomes wet. A solution containing water and the organic substance accumulates on the exposed surface. Removing this solution ensures that the cleaned surface is dry, allowing it to be stored or further surface treatment can be carried out.

[0042] In order to free the surface of the water and the at least partially organic substance and possibly of the other substance, for example, a strong air stream can be directed onto the surface, an elevated temperature can be applied, the water and the substance can be vacuumed off, an absorbent material, in particular fleece or fabric, can be used, although this list is not exhaustive.

[0043] In one embodiment of the method, it is provided that the surface has been subjected to at least one treatment process before the application, and / or that the applied surface is subjected to at least one treatment process after the application. Accordingly, the method can be used before, during, or after a treatment process in a production or assembly line.

[0044] Examples of processing operations include mechanical or chemical processes, painting, applying an adhesive, coating, milling, casting, welding, forming, although this list is not exhaustive.

[0045] In one embodiment of the method, it is provided that the surface has a surface with a metal, in particular a surface with a metal alloy, preferably a surface with a metal alloy having a nickel content other than zero, more preferably a surface with a steel alloy having a nickel content other than zero.

[0046] This makes it particularly suitable for cleaning battery cell surfaces. An example of a surface made with a steel alloy with a non-zero nickel content is stainless steel. Another example of a surface made with a steel alloy with a non-zero nickel content is Hilumin.

[0047] In one embodiment of the method, it is provided that the surface is a surface of a battery cell.

[0048] The process allows the surface of a battery cell to be cleaned while meeting both the requirement of a surface temperature equal to or lower than 60°C and the requirement of transferring an electrical potential below 1 V. Thus, the surface of the battery cell can be cleaned and the risk of overheating and / or spontaneous combustion can be avoided.

[0049] In one embodiment of the use it is provided that the plasma source has a plasma nozzle and the supply element is set up to introduce water as a liquid or gas, in particular in the form of mist or water vapor as a working gas into the plasma nozzle, or that the plasma source has a plasma nozzle and the supply element is set up to introduce water into a plasma jet emerging from the plasma nozzle, or that the device has a plasma nozzle with a nozzle chamber and the supply element is set up to introduce water into the nozzle chamber.

[0050] This allows simultaneous exposure of a surface to be cleaned to the plasma jet and water. If the plasma source has a feed element for introducing water as the working gas into the plasma nozzle, the plasma jet is generated based on the water introduced through the feed element, so that the plasma jet exiting the plasma nozzle contains water. If the feed element is configured to introduce water into the plasma jet exiting the plasma nozzle, and if the feed element is configured to introduce water into the nozzle chamber, the water is introduced into the generated plasma jet.

[0051] In one embodiment of the use, it is provided that the substance (202) is at least partially separated from the surface and removed from the surface together with the water introduced into the plasma jet and then accumulating on the surface.

[0052] This makes it easier to remove the organic substance from the surface and thus achieves an improved cleaning result.

[0053] In one embodiment of the use, it is provided that the surface is contaminated with at least one further substance, wherein the at least one further substance contains at least one element from the list: protein, water-soluble salt, oil, that the at least one further substance mixes with the water or dissolves therein, and that after exposure, the surface is freed from the water, from the at least partially organic substance, and from the at least one further substance. Further features and advantages of the method and the use emerge from the following description of exemplary embodiments, with reference to the attached drawing.

[0054] In the drawing show

[0055] Fig. 1 shows a first embodiment of a plasma source for generating an atmospheric plasma jet in a schematic sectional view;

[0056] Fig. 2 shows an embodiment of a method for cleaning a surface with the plasma source from Fig. 1;

[0057] Fig. 3 shows a second embodiment of a plasma source for generating an atmospheric plasma jet in a schematic sectional view;

[0058] Fig. 4 shows a third embodiment of a plasma source for generating an atmospheric plasma jet in a schematic sectional view;

[0059] Fig. 5 shows a fourth embodiment of a plasma source for generating an atmospheric plasma jet in a schematic sectional view;

[0060] Fig. 6 shows a first embodiment of a method for cleaning a surface with the plasma source from Fig. 4,

[0061] Fig. 7 shows a second embodiment of a method for cleaning a surface with the plasma source from Fig. 4 and

[0062] Fig. 8 shows a third embodiment of a method for cleaning a surface with the plasma source from Fig. 4. Fig. 1 shows a schematic sectional view of a plasma source 2 in the form of a plasma nozzle 3 for generating a reactive gas stream 26 in the form of an atmospheric plasma jet by means of an arc-like discharge,

[0063] The plasma nozzle 3 has a metal nozzle tube 4 that tapers conically to a nozzle opening 6. At the end opposite the nozzle opening 6, the nozzle tube 4 has a swirl device 8 with an inlet 10 for a gas stream 23, in particular a working gas, for example, air or nitrogen.

[0064] An intermediate wall 12 of the swirl device 8 has a ring of circumferentially inclined bores 14 through which the gas flow is guided. The downstream, conically tapered portion of the nozzle tube is therefore flowed through by the gas flow in the form of a vortex 16, the core of which runs along the longitudinal axis of the nozzle tube. An internal electrode 18 is arranged centrally on the underside of the intermediate wall 12 and projects coaxially into the nozzle tube in the direction of the tapered section. The internal electrode 18 is electrically connected to the intermediate wall 12 and the remaining parts of the swirl device 8. The swirl device 8 is electrically insulated from the nozzle tube 4 by a ceramic or quartz glass tube 20. A high-frequency high voltage, generated by a transformer 22, is applied to the internal electrode 18 via the swirl device 8. The inlet 10 is supplied with a gas stream 23 via a line not shown. The nozzle tube 4 is grounded.The applied voltage generates a high-frequency discharge in the form of an arc 24 between the inner electrode 18 and the nozzle tube 4.

[0065] The plasma nozzle 3 further comprises a grid structure (not shown) in the region of the nozzle opening 6. The grid structure is provided to spatially confine the arc 24 within the nozzle tube 4 in order to reduce, preferably prevent, potential transfer to a surface treated with the plasma jet. During operation, a high-frequency high voltage, generated by a transformer 22, is applied between the inner electrode 18 and the nozzle tube 4, which acts as a counter electrode. The high-frequency high voltage can have a voltage in the range of 1-100 kV, preferably 1-50 kV, more preferably 1-10 kV, and a frequency of 1-300 kHz, in particular 1-100 kHz, preferably 10-100 kHz, more preferably 10-50 kHz. The high-frequency high voltage can be a high-frequency alternating voltage, but also a pulsed direct voltage, or a superposition of both voltage forms.The high-frequency high voltage generates a high-frequency discharge in the form of an arc 24 between the inner electrode 18 and the nozzle tube 4.

[0066] Throughout this disclosure, the terms "arc," "arc discharge," or "arc-like discharge" are used as a phenomenological description of the discharge, since the discharge occurs in the form of an arc. The term "arc" is also used elsewhere as a discharge form for DC discharges with essentially constant voltage values. In the present case, however, it is a high-frequency discharge in the form of an arc, i.e., a high-frequency, arc-like discharge.

[0067] The gas stream 23 contains at least one working gas. However, due to the swirling flow of the working gas, this arc is channeled in the vortex core along the axis of the nozzle tube 4, so that it only branches off to the wall of the nozzle tube 4 in the region of the nozzle opening 6. The working gas, which rotates at a high flow velocity in the region of the vortex core and thus in the immediate vicinity of the arc 24, comes into intimate contact with the arc 24 and is thereby partially converted into the plasma state, so that an atmospheric plasma jet 26 exits the plasma nozzle 3 through the nozzle opening 6. When the plasma nozzle 3 is used in a method according to the present disclosure, water, for example as water vapor as a gas stream 23 or in liquid form, for example as an aerosol or mist, can be introduced into the plasma nozzle 3 through the inlet 10. The water introduced in the form of water vapor is thus used as the working gas.The water vapor comes into intimate contact with the arc 24 and is at least partially converted into the plasma state. Thus, the atmospheric plasma jet 26 exiting the plasma nozzle 3 through the nozzle opening 6 contains water. Water is introduced into the atmospheric plasma jet 26 by the fact that the working gas introduced into the plasma nozzle to generate the plasma jet 26 contains water vapor.

[0068] A surface to be cleaned is then simultaneously exposed to the water introduced into the atmospheric plasma jet and to the atmospheric plasma jet, in which the plasma jet itself contains water. When using the plasma nozzle 3 in this way, the inlet 10 is a supply element designed to introduce water in the form of steam as the working gas into the plasma nozzle 3.

[0069] Furthermore, depending on the temperature difference between the water vapor and the inner wall of the nozzle tube 4 or the ceramic or quartz glass tube 20, and depending on the flow rate of the gas stream 23, the water vapor can condense and exit the plasma nozzle 3 through the nozzle opening 6 alongside the atmospheric plasma jet 26. In this case, the surface to be cleaned is simultaneously exposed to the water introduced into the atmospheric plasma jet 26 and the atmospheric plasma jet 26, on the one hand because the plasma jet 26 itself contains water, and on the other hand because the plasma jet 26 and the condensed water impinge on the surface in droplet form.

[0070] Fig. 2 shows an embodiment of a method 200 for cleaning a surface 204 contaminated with a substance 202 using the plasma nozzle 3 from Fig. 1. In the method 200, a workpiece 206 with a surface 204 to be cleaned is arranged such that the surface 204 of the workpiece 206 is accessible. The surface 204 is at least partially covered with a substance 202 having an inorganic component, for example, lubricating grease.

[0071] Furthermore, in method 200, the plasma source 2 is supplied with air or nitrogen as a working gas in a gas stream. The atmospheric plasma jet 208 generated on the basis of this working gas exits the plasma nozzle 3 and is directed toward the surface 204 to be cleaned, so that the surface 204 to be cleaned is exposed to the plasma jet 208 in a treatment area.

[0072] Next to the plasma nozzle 3, a supply element 212 in the form of a spray device 214 is arranged and directed onto the treatment area on the surface 204. During exposure to the atmospheric plasma jet 208, the surface 204 in the treatment area is subjected to, in particular sprayed, water 216 by means of the spray device 214. Thus, after the atmospheric plasma jet 208 emerges from the plasma nozzle 3, the water 216 is introduced into the atmospheric plasma jet 208. The water 216 is sprayed in liquid form using a carrier gas 218, for example, air. The flow rate at which water 216 emerges from the spray device 214 can be set in the range of 0.1 to 50 grams per minute, with a flow rate in the range of 0.1 to 10 liters per minute for the carrier gas 218.

[0073] The water 216 introduced into the atmospheric plasma jet 208 can at least partially interact with the atmospheric plasma jet 208 by at least partially evaporating the water 216. Thus, the water 216 introduced into the plasma jet 208 by the spray device 214 can be applied to the surface 204 to be cleaned partially in a gaseous state and partially in a liquid state.

[0074] By subjecting the surface 204 to the plasma jet 208 from the plasma nozzle 3 and to the water 216 from the spray device 214, the oil coating in the treatment area 210 is separated from the surface 204 and dispersed in the form of droplets in the water 216 accumulating on the surface 204.

[0075] The plasma nozzle 3 and the surface 204 can be moved relative to each other to subject the surface 204 or the workpiece 206 to a cleaning treatment in predetermined sections or completely. If the plasma nozzle 3 is moved, the spray device 214 is preferably moved along with it and / or the orientation of the spray device 214 is adjusted such that the treatment area 210 continues to be exposed to the water 216.

[0076] In a further embodiment not shown, the method 200 can also be carried out using a plurality of plasma nozzles and / or a plurality of spray devices 214.

[0077] Fig. 3 shows a second embodiment of a plasma source 300 for generating an atmospheric plasma jet in a schematic sectional view. The plasma source 300 of Fig. 3 is designed as a plasma nozzle 302 for generating a reactive gas stream in the form of an atmospheric plasma jet by means of an arc-like discharge.

[0078] The plasma nozzle 302 from Fig. 3 has a metal nozzle tube 304 that tapers conically to a nozzle opening 306, a swirl device 308 with an inlet 310 for a gas stream 312, an intermediate wall 314, a ring of circumferentially inclined bores 316, an internal electrode 318, and a ceramic or quartz glass tube 320. A high-frequency high voltage generated by a transformer 322 can be applied to the internal electrode 318 via the swirl device 308. The inlet 310 is connected to a line (not shown) for supplying a gas stream 312. The nozzle tube 304 is grounded. By applying the voltage from the transformer 322, a high-frequency discharge in the form of an arc 324 can be generated between the inner electrode 318 and the nozzle tube 304.

[0079] In contrast to the plasma source of Fig. 1, the plasma source 300 of Fig. 3 has an outlet nozzle 328 and a supply element 330 configured to introduce water into the plasma jet 326 emerging from the plasma nozzle 302. The outlet nozzle 328 is designed as an extension of the nozzle opening 306. The supply element 330 is designed as a nozzle 332 fluidly connected to the outlet nozzle 328.

[0080] When using the plasma nozzle 302 in a method according to the present disclosure, a gas stream 312 is introduced into the swirl device 308 via the inlet 310, wherein the gas stream 312 contains a working gas, for example, air, argon, or nitrogen. The working gas comes into intimate contact with the arc 324 generated by the high-frequency discharge and is converted into the plasma state, then exiting the plasma nozzle 302 as an atmospheric plasma jet through the outlet nozzle 328.

[0081] A mixture 334 of a carrier gas, for example, air, and water 336, for example, demineralized water, is fed into the outlet nozzle 328 via the supply element 330. Thus, the water 336 is introduced into the atmospheric plasma jet before the atmospheric plasma jet 326 exits the plasma nozzle 302.

[0082] The flow rate of the carrier gas and the water 336 can be selected such that the water 336 enters the outlet nozzle 328 as fine droplets or mist. Alternatively or additionally, the flow rate of the carrier gas and the water 336 can be selected such that the water 336 exits the outlet nozzle 328 at least partially as droplets 338.

[0083] The feeding of water 336 via the supply element 330 is preferably synchronized with the transfer of the working gas into the plasma state such that a surface to be cleaned can be or is simultaneously exposed to the plasma jet 326 emerging from the outlet nozzle 328 and to the water 336 emerging from the outlet nozzle 328.

[0084] In an alternative embodiment of the plasma nozzle 302, the supply element 330 is arranged in the region of the nozzle tube 304, where the working gas comes into contact with the electrical arc-like discharge, creating the plasma jet. This arrangement of the supply element is shown in dashed lines in Fig. 3 and designated by reference numeral 340.

[0085] Fig. 4 shows a third embodiment of a plasma source 400 for generating an atmospheric plasma jet in a schematic sectional view. The plasma source 400 of Fig. 4 is also designed as a plasma nozzle 402 for generating a reactive gas stream in the form of an atmospheric plasma jet by means of an arc-like discharge.

[0086] The plasma nozzle 402 from Fig. 4 has a metal nozzle tube 404 that tapers conically to a nozzle opening 406, a swirl device 408 with an inlet 410 for a gas stream 412, an intermediate wall 414, a ring of circumferentially inclined bores 416, an internal electrode 418, and a ceramic or quartz glass tube 420. A high-frequency high voltage generated by a transformer 422 can be applied to the internal electrode 418 via the swirl device 408. The inlet 410 is connected to a line (not shown) for supplying a gas stream 412. The nozzle tube 404 is grounded. By applying the voltage from the transformer 422, a high-frequency discharge in the form of an arc 424 can be generated between the inner electrode 418 and the nozzle tube 404.

[0087] In addition, the plasma source 400 has a mouthpiece 428, which, together with the inner wall 430 of the nozzle tube 404, forms an annular chamber 432 in the region of the nozzle opening 406, and a nozzle 434. The mouthpiece 428 and the nozzle 434 together form a supply element 436, which is configured to introduce water into the plasma jet 426 emerging from the plasma nozzle 402.

[0088] The mouthpiece 428 has an outlet 438, an annular recess 440, and channels 442 arranged in a ring around the annular recess 440. The channels 442 are connected to the nozzle nozzle 434. The mouthpiece 428 is received in the region of the nozzle opening 406 of the nozzle tube 404 by the nozzle tube 404 such that the annular recess 440, together with the inner wall 430 of the nozzle tube 404, forms an annular chamber 432, and that the outlet 438, the annular chamber 432, and the channels 442 are fluidly connected to the nozzle nozzle 434 attached to the nozzle tube 404.

[0089] When using the plasma source 400 from Fig. 4 in a method according to the present disclosure, the swirl device 408 is supplied with a gas stream 412 via the inlet 410, wherein the gas stream 412 contains a working gas, for example air, argon or nitrogen. Furthermore, water in the form of mist is introduced via the nozzle 434 together with a carrier gas, for example air. The mixture of water and carrier gas is fed via the nozzle 434 into the annular chamber 432 on the outer circumference of the mouthpiece 428 and from there passes radially via the channels 442 into the nozzle outlet 438. The water is thus at the downstream end of the excitation zone 444, in which the plasma jet 426 is generated and which is formed by the nozzle channel 446 through which the arc 424 passes.The plasma nozzle 400 further comprises a grid structure (not shown) which is designed to spatially confine the arc 424 within the nozzle tube 404, in particular to the excitation zone 444, in order to reduce, preferably prevent, a potential transfer to a surface treated with the plasma jet.

[0090] The feeding of water via the supply element 436 is preferably synchronized with the transfer of the working gas into the plasma state in such a way that a surface to be cleaned can be or will be exposed simultaneously to the plasma jet 426 exiting from the outlet 438 and to the water exiting from the outlet 438.

[0091] Fig. 5 shows a fourth embodiment of a plasma source 500 for generating an atmospheric plasma jet in a schematic sectional view. The plasma source 500 is designed as a plasma nozzle 502 for generating a reactive gas stream in the form of an atmospheric plasma jet by means of an arc-like discharge.

[0092] The plasma nozzle 502 has a metal nozzle tube 504 that tapers conically to a nozzle opening 506, a swirl device 508 with an inlet 510 for a gas stream 512, an intermediate wall 514, a ring of circumferentially inclined bores 516, an internal electrode 518, and a ceramic or quartz glass tube 520. A high-frequency high voltage generated by a transformer 522 can be applied to the internal electrode 518 via the swirl device 508. The inlet 510 is connected to a line (not shown) for supplying a gas stream 512. The nozzle tube 504 is grounded. By applying the voltage from the transformer 522, a high-frequency discharge in the form of an arc 524 can be generated between the internal electrode 518 and the nozzle tube 504. The plasma nozzle 502 further comprises a supply element 528 with a nozzle 530 and a mouth insert 532.The mouth insert 532 has an interior space 534 with an orifice 536. Furthermore, the shape or the interior space 534 of the mouth insert 532 is adapted to the shape of the nozzle tube 504 in the region of the nozzle orifice 506 such that, in an assembled state, the orifice 536 of the mouth insert 532 surrounds the nozzle orifice 506 of the nozzle tube 504. In an assembled state of the plasma nozzle 502 with the supply element 528 or with the nozzle 530 and the mouth insert 532, the interior space 534 of the mouth insert 532, together with the outer wall of the nozzle tube 504, forms an annular chamber 538 that is fluidically connected to the nozzle 530.

[0093] When using the plasma source 500 of Fig. 5 in a method according to the present disclosure, a mixture with water 540 in the form of a mist and with a carrier gas, for example, air, argon, or nitrogen, is fed through the nozzle 530 into the annular chamber 538. The mixture with water 540 then exits the mouth opening 536 into the atmospheric plasma jet 526, which exits the nozzle opening 506. Due to the design of the mouth insert 532 and the arrangement of the mouth insert 532 opposite the nozzle opening 506, the mixture or water 540 is introduced concentrically into the plasma jet. Thus, the water 540 is introduced into the atmospheric plasma jet 526 after the atmospheric plasma jet 526 exits the plasma nozzle 502.

[0094] Fig. 6 shows a first embodiment of a method 600 for cleaning a surface contaminated with an organic substance using the plasma source of Fig. 4.

[0095] In method 600, a rotationally symmetrical battery cell 604 with a surface 602 to be cleaned is mounted on a support element 606 and arranged such that the surface 602 of the workpiece is accessible. The surface 602 of the battery cell 604 comprises a steel alloy, for example, Hilumin. The surface 602 to be cleaned is contaminated by an organic substance in the form of an oil film.

[0096] The support element 606 causes a rotational movement 610 of the battery cell 604 and thus also of the surface 602, whereby the battery cell 604 is rotated about its axis of symmetry.

[0097] A plasma source as shown in Fig.4 is arranged in the immediate vicinity of the surface 602, for example with a distance of about 5 millimeters between the nozzle opening and the surface 602 of the battery cell 604, and with the nozzle opening directed towards the surface 602 of the battery cell 604.

[0098] The plasma nozzle is supplied with a gas stream containing a working gas, such as air, argon, or nitrogen, via the inlet of the swirl device and with a mixture of air and water mist via the supply element. By applying an arc-like discharge, an arc is ignited, and contact between the working gas and the arc converts the working gas into the plasma state. The water mist is introduced into the thus generated atmospheric plasma jet 612. The plasma jet 612 and the water introduced into the plasma jet 612 exit the nozzle opening.

[0099] The plasma nozzle is moved with a translational movement 608 along the symmetry axis of the battery cell 604. The rotational movement 610 of the battery cell 604 and the translational movement 608 of the plasma nozzle are adapted to one another in such a way that the treatment area formed by the impact of the atmospheric plasma jet 612 and the water on the surface 602 of the battery cell 604 migrates across the surface 602.

[0100] In the treatment area, the organic substance or oil is separated from the oil film on the surface 602 of the battery cell 604 and removed as a suspension of oil droplets in the water that was introduced into the plasma jet 612 and then accumulates on the surface 602 after reaching the surface 602.

[0101] When performing method 600, the surface 602 of the battery cell 604 has a contaminated surface portion 614 and a cleaned surface portion 616, wherein the cleaned surface portion 616 corresponds to the portion of the surface 602 of the battery cell 604 over which the treatment region has migrated. The cleaned surface portion 616 has a mixture of water and oil droplets suspended in the water.

[0102] When the cleaned surface portion 616 corresponds to the portion of the surface 602 to be cleaned, the mixture with water and oil droplets suspended in the water can be removed from the surface 602 of the battery cell 604, for example by means of compressed air.

[0103] Fig. 7 shows a second embodiment of a method 700 for cleaning a surface with the plasma source from Fig. 4.

[0104] In method 700, a workpiece 704 having a substantially flat surface 702 is mounted on a support member 706 and positioned such that the surface 702 of the workpiece 704 is accessible. The surface 702 comprises an aluminum alloy. The surface 702 to be cleaned is contaminated by an organic substance in the form of a silicone release agent.

[0105] The holding element 706 moves the workpiece 704 and thus also its surface 702 with a translational movement 708 along a first movement axis.

[0106] A plasma source as shown in Fig.4 is arranged in the immediate vicinity of the surface 702, for example with a distance of about 7 millimeters between the nozzle opening and the surface 702 of the workpiece 704, and with the nozzle opening directed towards the surface 702 of the workpiece 704.

[0107] The plasma nozzle is supplied with a gas stream containing a working gas, such as air, argon, or nitrogen, via the inlet of the swirl device and with a mixture of air and water mist via the supply element. Applying an arc-like discharge creates an arc, and contact between the working gas and the arc converts the working gas into the plasma state. The water mist is introduced into the thus generated atmospheric plasma jet. The plasma jet 709 and the water introduced into the plasma jet 709 exit the nozzle opening.

[0108] The plasma nozzle is moved with a translational movement 710 along a second direction, wherein the second movement axis is arranged substantially perpendicular to the first movement axis.

[0109] The movement of the support element 706 and the movement of the plasma nozzle can be adapted to one another in such a way that the treatment area formed by the arrival of the atmospheric plasma jet 709 and the water on the surface 702 of the workpiece 704 migrates over the surface 702.

[0110] In the treatment area, the organic substance or the release agent is separated from the surface 702 of the workpiece 704 with silicone and mixed and removed with the water that was introduced into the plasma jet 709 and then accumulates on the surface 702 after arriving at the surface 702.

[0111] When performing method 700, the surface 702 of the workpiece 704 has a contaminated surface portion 712 and a cleaned surface portion 714, wherein the cleaned surface portion 714 corresponds to the portion of the surface 702 of the workpiece 704 over which the treatment region has migrated. The cleaned surface portion 714 comprises a mixture of water and release agent.

[0112] Fig. 8 shows a third embodiment of a method 800 for cleaning a surface using the plasma source 802 from Fig. 4. A gas supply element 804 with a gas slot nozzle 806 connected to a gas source (not shown) is provided next to the plasma source 802. The gas slot nozzle 806 has a slot opening 808 and is arranged next to the plasma source 802 such that the slot opening 808 is directed toward a treatment area of ​​a surface being treated by the plasma source 802.

[0113] In method 800, the plasma source 802 is supplied with a gas stream containing a working gas, for example, air, argon, or nitrogen, via the inlet of the swirl device and with a mixture of air and water mist via the supply element. By applying an arc-like discharge, an arc is generated, and contact between the working gas and the arc converts the working gas into the plasma state. The water mist is introduced into the thus generated atmospheric plasma jet 810. The atmospheric plasma jet 810 and the water introduced into the plasma jet exit the nozzle opening.

[0114] The plasma source 802 is moved along a direction 812 that is substantially parallel to the main extension direction of the slot opening 808. The gas-filled slot nozzle 806 is fed, for example, with compressed air, which then exits through the slot opening 808 and frees the treatment area toward which it is directed of liquids, in particular water and contaminants.

[0115] Thus, contaminants are separated from the treated surface by the plasma jet 810 and the water, and then the contaminants and the water are removed from the surface together by the compressed air.

Claims

Patent claims 1. A method (200, 600, 700) for cleaning a surface (204, 602, 702) using an atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709), wherein the surface (204, 602, 702) is contaminated with at least one at least partially organic substance (202), characterized in that water (216, 336, 540) is introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709), and that the surface (204, 602, 702) is simultaneously cleaned with the water (216, 336, 540) introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709) and is subjected to the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709).

2. Method according to claim 1, characterized in that the water (216, 336, 540) is introduced in a liquid state together with a carrier gas into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709).

3. Method according to one of the preceding claims, characterized in that the water (216, 336, 540) introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) interacts at least partially with the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) in that the water (216, 336, 540) at least partially evaporates, and that when the surface (204, 602, 702) is acted upon, the water introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) Water (216, 336, 540) is applied to the surface (204, 602, 702) partly in a gaseous state and partly in a liquid state.

4. Method according to one of the preceding claims, characterized in that the water (216, 336, 540) is introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) at a flow rate in the range of equal to or more than 0.1 grams per minute, in particular in the range of equal to or more than 2 grams per minute, preferably in the range of equal to or more than 5 grams per minute, in particular preferably in the range of equal to or more than 10 grams per minute, more preferably in the range of 0.1 to 100 grams per minute.

5. Method according to one of the preceding claims, characterized in that the water (216, 336, 540) is introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) before the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) emerges from a plasma nozzle (3, 302, 402, 502) used to generate the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709).

6. Method according to one of claims 1 to 4, characterized in that the water (216, 336, 540) is introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) after the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) has emerged from a plasma nozzle (3, 302, 402, 502) used to generate the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709).

7. Method according to claim 1, characterized in that for introducing water (216, 336, 540) into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709), the water (216, 336, 540) is introduced as a working gas into a plasma nozzle (3, 302, 402, 502) used to generate the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709), and that for applying the surface (204, 602, 702) simultaneously with the water introduced into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) (216, 336, 540) and with the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) the surface (204, 602, 702) is exposed to the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) generated on the basis of water (216, 336, 540) as working gas.

8. Method according to claim 7, characterized in that the water (216, 336, 540) is introduced as mist or as water vapor into the plasma nozzle (3, 302, 402, 502) used to generate the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709).

9. Method according to one of the preceding claims, characterized in that when the surface (204, 602, 702) is acted upon, the plasma jet (26, 208, 326, 426, 526, 612, 709) is moved relative to the surface (204, 602, 702), and / or that when the surface (204, 602, 702) is acted upon, the surface (204, 602, 702) is moved relative to the plasma jet (26, 208, 326, 426, 526, 612, 709).

10. Method according to one of the preceding claims, characterized in that the at least one at least partially organic substance (202) reacts at least partially with the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709, 709) and mixes with the water (216, 336, 540) or dissolves therein.

11. Method according to one of the preceding claims, characterized in that the surface is contaminated with at least one further substance, wherein the at least one further substance contains at least one element of the list: protein, water-soluble salt, oil, and that the at least one further substance mixes with or dissolves in the water (216, 336, 540).

12. Method according to one of the preceding claims, characterized in that after the application, the surface (204, 602, 702) is freed from the water (216, 336, 540) and the at least partially organic substance (202) and optionally from the at least one further substance.

13. Method according to one of the preceding claims, characterized in that before the application, the surface (204, 602, 702) has been subjected to at least one processing process, and / or that after the application, the applied surface (616, 714) is subjected to at least one processing process.

14. Method according to one of the preceding claims, characterized in that the surface (204, 602, 702) has a surface (204, 602, 702) with a metal, in particular a surface (204, 602, 702) with a metal alloy, preferably a surface (204, 602, 702) with a metal alloy having a nickel content other than zero, more preferably a surface (204, 602, 702) with a steel alloy having a nickel content other than zero.

15. Method according to one of the preceding claims, characterized in that the surface (204, 602, 702) is a surface (204, 602, 702) of a battery cell (604).

16. Use of a device with a plasma source configured to generate an atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709) and with a feed element (10, 212, 330, 436, 528) configured to introduce water (216, 336, 540) into the atmospheric plasma jet (26, 208, 326, 426, 526, 612, 709), for cleaning a surface (204, 602, 702), in particular a surface (204, 602, 702) of a battery cell (604), wherein the surface (204, 602, 702) is contaminated with at least one at least partially organic substance (202).

17. Use according to claim 16, characterized in that the plasma source has a plasma nozzle (3, 302, 402, 502) and the supply element (10) is designed to introduce water (216, 336, 540) in the form of mist or water vapor as a working gas into the plasma nozzle (3, 302, 402, 502), or that the plasma source has a plasma nozzle (3, 302, 402, 502) and the feed element (212, 330, 436, 528) is designed to introduce water (216, 336, 540) into a plasma jet (26, 208, 326, 426, 526, 612, 709) emerging from the plasma nozzle (3, 302, 402, 502), or that the device has a plasma nozzle (3, 302, 402, 502) with a nozzle chamber and the feed element (330, 436) is designed to introduce water (216, 336, 540) into the nozzle chamber.

18. Use according to claim 16 or 17, characterized in that the substance (202) is at least partially separated from the surface (204, 602, 702) and removed from the surface (204, 602, 702) together with the water introduced into the plasma jet (26, 208, 326, 426, 526, 612, 709) and then accumulating on the surface (204, 602, 702).

19. Use according to one of claims 16 to 18, characterized in that the surface is contaminated with at least one further substance, wherein the at least one further substance contains at least one element from the list: protein, water-soluble salt, oil, that the at least one further substance mixes with the water (216, 336, 540) or dissolves therein, and that after exposure, the surface (204, 602, 702) is freed from the water (216, 336, 540), from the at least partially organic substance (202) and from the at least one further substance.

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