CLEANING DEVICE AND CLEANING PROCEDURE

Description

TECHNICAL FIELD

[0001] The present invention relates to a cleaning device and a cleaning method for cleaning a narrow, curved channel. STATE OF THE ART

[0002] EP 3446787 discloses a device and method that generate a discontinuous liquid jet using a nozzle. The liquid jet is used for cleaning, surface treatment, and cutting, with reduced fluid consumption and an improved abrasion effect.

[0003] EP 2716208 discloses a cleaning device for narrow-lumen channels, pipes, and lines, in particular for cannulas, catheters, and endoscopes. This known cleaning device comprises a housing with a rinsing chamber that accommodates a distribution chamber. The distribution chamber has a medium inlet connected to a cleaning fluid supply, as well as a medium outlet having several connecting ports. The cannulas, catheters, and endoscopes to be cleaned are interchangeably arranged at the connecting ports. The housing also provides a collecting container in which the cleaning fluid collects after use. A pump pumps the collected cleaning fluid through a cleaning supply line and through several filters in one direction at 0.5 bar. Furthermore, the cleaning device has a compressed air supply line that opens into the cleaning supply line.The compressed air supply line is connected to a compressed air source. At a predefined time, an inlet valve is opened, causing compressed air at 5 bar to flow through the compressed air supply line into the cleaning fluid supply line, causing a pressure surge within the cleaning fluid. This creates a two-phase cleaning medium consisting of cleaning fluid on the one hand and compressed air on the other. Due to its phase boundaries, this medium acts mechanically on the contaminants to be removed from the inner surface of cannulas, catheters, and endoscopes.

[0004] EP 2815816 discloses a method for the optimized cleaning of lines or systems through which liquid flows. The known method comprises applying a gas or gas mixture to a line that is at least partially filled with liquid in pulses with a specific number of pulses, with a specific pulse interval between each pulse.

[0005] DE 67368 discloses a process for removing solid sludge deposits from water pipelines by injecting carbon dioxide into the water pipeline while simultaneously flushing it with water, either continuously or intermittently. A mixture of water, gas bubbles, and optionally sparingly soluble salts swirls through the pipeline and abrades the sludge deposits.

[0006] GB 2 289 512 A describes a method and device for cleaning tubular elements in medical cannulas, endoscopes, and also in the field of mechanical engineering. The device comprises a compressor that can add air intermittently to a fluid flow as bubbles via a valve. Furthermore, the device comprises a pulsed fluid pump that generates the fluid flow. Furthermore, an impeller is proposed that better distributes the bubbles in the fluid flow.

[0007] US 2003 / 051746 A1 describes a water hammer cleaning machine with a pump for conveying a cleaning fluid and a compressor for conveying air. The water hammer cleaning machine further includes a regulator for maintaining a constant air pressure and a valve for adjusting the flow of air into the cleaning fluid. TASK

[0008] Therefore, the object of the invention is to provide an improved cleaning device and an improved cleaning method for cleaning a narrow, curved channel. DISCLOSURE OF THE INVENTION

[0009] According to the invention, a cleaning device for cleaning a narrow, curved channel is provided, according to claim 1, which comprises a liquid pump for conveying a cleaning liquid. The liquid pump can be controlled such that it conveys the cleaning liquid at varying pressure. Furthermore, the cleaning device comprises a gas bubble generating device with an air compressor for generating gas bubbles, wherein the air compressor comprises a compressor with controllable compression and wherein the air compressor can be controlled such that it generates gas bubbles of variable size and mixes them with the cleaning liquid to form a gas bubble-cleaning liquid mixture in order to clean the narrow, curved channel with the gas bubble-cleaning liquid mixture.

[0010] The term "liquid pump" particularly encompasses a working machine for conveying a liquid or an incompressible fluid, e.g., a centrifugal pump. The liquid pump can be driven by an electric motor, the speed of which can be adjusted by an electric speed controller or speed regulator. The pressure of the conveyed cleaning fluid preferably depends on the speed of the electric motor of the liquid pump.

[0011] The cleaning liquid comprises in particular water, acid, hydrochloric acid, alkali and / or mixtures thereof. The gas bubbles are in particular air bubbles. The gas bubbles have, for example, a diameter or a size in a range of 0.5 to 8 mm. The expression gas bubbles of variable size means that the cleaning device generates gas bubbles with essentially the same first size at a first point in time or for a first period of time, while the cleaning device generates gas bubbles with essentially the same second size at a second point in time or for a second period of time, wherein the first size is different from the second size, i.e. the size is varied. Alternatively, the cleaning device can generate gas bubbles of varying size, i.e. gas bubbles of different sizes simultaneously at one point in time or for one period of time.The varying size of the gas bubbles is generated by a compressor with controllable compression and / or by the varying pressure of the cleaning liquid (the latter feature not falling within the scope of the independent claims).

[0012] The gas bubble cleaning fluid mixture may comprise a gas bubble cleaning fluid foam, a gas bubble cleaning fluid mist and / or a gas bubble cleaning fluid vapor.

[0013] The term channel preferably encompasses a tube, a pipe, an opening, and in particular a cooling channel of an injection molding tool, wherein the channel has a first end or a first opening and another end or a second opening. The term narrow means in particular that the length of the narrow channel is greater than its cross-sectional area or its diameter. For example, the diameter of a narrow channel is in a range from 6.35 to 25.4 mm, while its length can typically be over 100 mm or even over 500 mm. The term curved preferably means a channel that does not run in a straight line, but has at least one bend, curvature, angle, or the like.

[0014] Injection molding tools, such as those used in plastic parts production, can have one or more cooling channels, for example to achieve faster cooling of the injection molding tool or an injection-molded plastic part. Short cooling times are usually preferred in order to achieve faster overall cycle times or production cycles in plastic parts production. Due to limescale deposits, corrosion or contamination (hereinafter generally referred to as contamination), the diameter of the cooling channels can decrease over time, whereby a coolant pumped through the cooling channels can dissipate less heat from the injection molding tool or the plastic part and / or a lower flow rate, i.e. volume flow, is achieved.

[0015] The use of 3D-printed injection molds has recently made it possible, among other things, to produce injection molds with complexly shaped, curved, or angled cooling channels. Typical drilling of a contaminated, curved cooling channel with a conventional drill to remove the contamination is insufficient due to the curvature. Manual cleaning is possible but is usually time-consuming, expensive, and does not produce repeatable and / or measurable cleaning results. Manual cleaning can also be harmful to the environment and health.

[0016] The varying pressure of the cleaning fluid can cause turbulence in the cleaning fluid, which, compared to a laminar flow of the cleaning fluid caused by constant pressure, achieves better detachment of contaminants from an inner wall of the narrow, curved channel. The gas bubbles in the gas bubble-cleaning fluid mixture essentially cause phase transitions between liquid and gas and, in particular, cause contaminants to be brushed off by means of the swirling cleaning fluid. Gas bubbles with a diameter or size in the range of 0.5 to 2 mm are referred to below as small, while those in the range of 5 to 8 mm are referred to as large. Large gas bubbles cause contaminants to be brushed off gently or more gently; small gas bubbles cause contaminants to be brushed off hard or more powerfully.

[0017] Conventional cleaning devices and processes generally do not provide for gas bubbles of variable size and, in particular, do not mix such size-varying gas bubbles with a pressure-varying cleaning fluid.

[0018] According to a further preferred embodiment, the gas bubble generating device can comprise a compressed air connection, a compressed air tank, and / or the compressed air compressor. In plastic parts production, a compressed air connection is often available, to which the cleaning device according to the invention can be connected with its compressed air connection in order to generate gas bubbles. The compressed air tank can buffer compressed air or compensate for pressure fluctuations. The compressed air compressor can advantageously make the cleaning device independent of a compressed air connection. The compressed air compressor, in particular, comprises a compressor with controllable compression. The compressor can, in particular, be controlled such that it generates the gas bubbles of varying size.

[0019] Furthermore, it is preferred that the gas bubble generating device comprises, in particular, a gas bubble injection device that injects the gas bubbles into the cleaning fluid and can thereby generate the gas bubble-cleaning fluid mixture. The gas bubble injection device comprises, for example, a hollow body with a plurality of bores, wherein the bores have different diameters in a range of 0.1 to 0.5 mm. The hollow body can comprise a sphere that is hollow inside. The hollow body preferably comprises the compressed air connection and / or can be connected to the compressed air reservoir and / or to the compressed air compressor. Compressed air supplied into the hollow body can escape through the bores.The hollow body is immersed in the cleaning fluid, which is pumped under varying pressure, allowing the escaping compressed air to emerge from the hollow body in the form of gas bubbles and mix with the passing cleaning fluid. The different diameters of the holes generally allow for the formation of gas bubbles of varying sizes.

[0020] According to a further embodiment, the cleaning device according to the invention can have a flow rate measuring device, i.e. a volume flow measuring device, downstream of the liquid pump, which measures a flow rate, i.e. a volume flow, of the cleaning liquid or of the gas bubble-cleaning liquid mixture. If the flow rate measuring device is arranged downstream of the gas bubble injection device, it measures in particular the flow rate of the gas bubble-cleaning liquid mixture; if it is arranged upstream of the gas bubble injection device, it measures in particular the flow rate of the cleaning liquid. The more cleanly a narrow, curved channel has been cleaned, the higher the flow rate of the cleaning liquid or of the gas bubble-cleaning liquid mixture is generally.The flow rate meter can be used to advantageously determine the cleaning progress and / or degree of cleaning of the narrow, curved channel. The flow rate is preferably in a range between 1 l / min and 75 l / min.

[0021] The cleaning device according to the invention generally comprises a pressure gauge downstream of the liquid pump, wherein the pressure gauge measures a pressure of the cleaning liquid. The pressure gauge and the liquid pump can form a pressure control circuit, in particular to be able to generate a predetermined pressure of the cleaning liquid. The pressure of the cleaning liquid is preferably in a range between 1.5 and 4.5 bar. In particular, the liquid pump varies the pressure in a range between 1.5 and 4.5 bar continuously or oscillatingly. The pressure variation, measured over time, can be, for example, sinusoidal, sawtooth-shaped, or triangular.

[0022] In a further embodiment, the cleaning device according to the invention may comprise a container downstream of the narrow, curved channel, wherein the container serves in particular to collect and decompress the gas bubble-cleaning liquid mixture and / or contamination from the narrow, curved channel.

[0023] According to a further embodiment, the liquid pump, the pressure sensor, the gas bubble generating device, the flow rate measuring device, a first connection for connecting to a first opening of the narrow, curved channel, a second connection for connecting to a second opening of the narrow, curved channel, and the container can form a fluid circuit, particularly in the order mentioned. The cleaning device can further comprise a flow direction change unit for changing the flow direction of the cleaning liquid or the gas bubble-cleaning liquid mixture. The flow direction change unit can enable cleaning of the narrow, curved channel in two directions, or in a forward and a reverse direction. Cleaning in a forward and a reverse direction generally improves the cleaning result, reduces clogging of the narrow, curved channel, and / or shortens the cleaning time.According to a preferred embodiment, the flow direction change unit can continuously change direction at a specific rhythm during a cleaning process. In a further embodiment, the cleaning device according to the invention can have at least two fluid circuits for cleaning at least two narrow, curved channels. The cleaning machine according to the invention with multiple fluid circuits can thus clean, for example, multiple cooling channels of an injection mold more quickly. Even more preferably, the cleaning device comprises four fluid circuits.

[0024] According to a further embodiment, the container can have a filter. The filter can serve for ventilation and as a cleaning fluid splash guard. Furthermore, the filter can reduce or prevent the escape of odors and / or gases from the cleaning fluid. The container is preferably open at the lid in order to collect and decompress gas bubble / cleaning fluid mixture escaping from the narrow, curved channel. Contamination released from the narrow, curved channel can settle to a container base by gravity. After the contamination has settled and the gas bubbles have outgassed, cleaning fluid is essentially present again, which the fluid pump can return to the fluid circuit, i.e., in particular, reuse. At the same time, the gas bubbles can outgas from the gas bubble / cleaning fluid mixture. The container can further comprise a heating device for heating the cleaning fluid.If acid is heated, its chemical reactivity and thus its cleaning performance can be increased. The heating device comprises, in particular, an electrically operated heating resistor whose heating power can be controlled. Furthermore, the container can comprise a temperature sensor for measuring a temperature of the cleaning fluid. The temperature sensor and the heating device can form a temperature control circuit in order to achieve a predeterminable temperature of the cleaning fluid. According to a further embodiment, the container can comprise a pH sensor for measuring a pH value of the cleaning fluid. If the cleaning fluid is reused after being used in a narrow, curved channel containing contaminants, the pH value of the cleaning fluid can change.If the pH sensor detects that a predetermined threshold has been reached, the cleaning device can indicate this; pause a cleaning process; indicate the need for complete or partial replacement of the cleaning fluid; and / or add concentrated or new cleaning fluid or replace it with used cleaning fluid. After a cleaning process, the cleaning fluid can be neutralized for disposal, with the pH sensor monitoring the neutralization process.

[0025] The cleaning method according to the invention for cleaning a narrow, curved channel comprises the following steps: Pumping a cleaning fluid at varying pressure using a controllable fluid pump; generating gas bubbles using a gas bubble generating device; varying the size of the gas bubbles using an air compressor comprising a compressor with controllable compression; mixing the gas bubbles and the cleaning fluid to form a gas bubble-cleaning fluid mixture; and cleaning the narrow, curved channel using the gas bubble-cleaning fluid mixture. According to a further development of the cleaning method, the gas bubble size can be adjusted depending on the cross-sectional area of ​​the narrow, curved channel.

[0026] Advantageous further developments of the invention are specified in the subclaims and described in the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments of the invention are explained in more detail with reference to the drawings and the following description. They show: Figure 1 an embodiment of a cleaning device according to the invention, Figure 2 another embodiment of a cleaning device according to the invention and Figure 3 an embodiment of a cleaning method according to the invention. EMBODIMENTS OF THE INVENTION

[0028] In the Figure 1A cleaning device 100 for cleaning a cooling channel 102 of an injection molding tool 104 is shown according to an embodiment of the invention. The cleaning device 100 comprises a fluid circuit 106, indicated by arrows. The tips of the arrows of the fluid circuit 106 point in a flow direction, i.e., downstream; the ends of the arrows point in a counterflow direction, i.e., upstream. The cleaning device 100 further comprises a centrifugal pump 108 with electronic speed control for controllably conveying a cleaning solution 109 along a pipeline 107; a pressure sensor 110, which is arranged downstream of the centrifugal pump 108;a hollow plastic body 112 with a plurality of bores 114 having different diameters in a range between 0.1 and 0.5 mm and arranged in the first pipeline, wherein the hollow plastic body 112 is connected to a compressed air connection 116 or alternatively to a compressed air reservoir 118 or an air compressor 120; a volume flow meter 122 to which the pipeline 107 is connected; a pipeline 124 connected to the volume flow meter 122; a directional control valve 125 with four connections, wherein the pipeline 124 is connected to a first connection of the directional control valve 125; a second connection 126 which can be connected to a first opening of the cooling channel 102 via a hose line 127; a third connection 128 of the directional control valve 125 which can be connected to a second opening of the cooling channel 102 via a hose line 129;a pipeline 130 connected to a fourth port of the directional control valve 125, and a container 132 to which the pipeline 130 is connected. The container 132 includes a filter 134 on its cover. Furthermore, the container 132 includes a temperature sensor T, a pH sensor pH, and an electrically operated heating coil 138. The centrifugal pump 108 and the container 132 are connected by a pipeline 140.

[0029] The injection molding tool 104 and the cooling channel 102 are manufactured using an additive manufacturing process. The cooling channel 102 has a diameter of 5 mm, meaning it is narrow, and has several bends in which contamination builds up due to storage, coolant, and / or corrosion. The cleaning device 100 is capable of loosening and removing this contamination. For this purpose, the cleaning device 100 is first connected to the cooling channels. The centrifugal pump 108 delivers the cleaning solution 109 at a pressure oscillating between 1.5 and 4.5 bar. The centrifugal pump 108 is equipped with a 3-phase, fan-cooled permanent magnet synchronous motor. For speed control, the centrifugal pump 108 has a frequency converter and PI controller, which are arranged in a terminal box of the centrifugal pump 108.The pressure sensor 110, together with the centrifugal pump 108, forms a pressure control circuit in order to be able to generate the oscillating pressure in a controllable manner.

[0030] The centrifugal pump 108 conveys the cleaning solution 109 through the pipeline 107 to the hollow plastic body 112 arranged in the pipeline, which is also referred to as the injection point and from whose bores compressed air flows in the form of gas bubbles. The hollow plastic body is spherical with a diameter of 10 mm and is made of acid-resistant PVC. The cleaning solution 109 mixes with the gas bubbles to form a cleaning solution-gas bubble mixture. Depending on the instantaneous pressure and / or average pressure of the cleaning solution 109, the diameter of the gas bubbles can be varied from 0.5 to 8 mm. Gas bubbles with a diameter or size in the range of 0.5 to 2 mm are referred to below as small, while those in the range of 5 to 8 mm are referred to as large. The pressure conveys the cleaning solution-gas bubble mixture through the volume flow meter 122, which determines a volume flow of the cleaning solution-gas bubble mixture.If the volume flow is below an adjustable threshold, the cooling channel 102 is still considered dirty and cleaning is continued.

[0031] The pressure then conveys the cleaning solution-gas bubble mixture further through the pipe 124 to the first port of the directional control valve 125. In a first state, the directional control valve 125 is set to connect the first port to the second port 126, so that the pressure conveys the cleaning solution-gas bubble mixture further through the hose line 127 to the first opening of the cooling channel 102. The cleaning solution-gas bubble mixture arriving in the cooling channel 102, due to the combination of the cleaning solution, the oscillating pressure, and the gas bubbles, causes the contaminants in the narrow, curved cooling channel 102 to be removed more effectively than conventional cleaning devices and methods.

[0032] The pressure conveys the cleaning solution-gas bubble mixture together with the detached contaminants from the second opening of the cooling channel 102 and through the hose line 129 to the third port 128 of the directional control valve 125. In the first state, the directional control valve 125 is set such that it connects the third port 128 to the fourth port, so that the cleaning solution-gas bubble mixture together with the detached contaminants is conveyed through the pipe 130 and finally into the container 132. Since the container 132 is not hermetically sealed, but has the filter 134 on the lid, the cleaning solution-gas bubble mixture decompresses in the container 132, ie the gas bubbles escape through the filter 134 and the cleaning solution 109 is formed again. Settling components of the contamination can be sedimented at the bottom of the container 132 as contamination sediment 136.Contaminant components that have bonded, in particular chemically, with the cleaning solution 109 reduce the cleaning performance or dilute the cleaning solution 109. The pH sensor pH therefore determines the pH value of the cleaning solution 109. The chemical reactivity of the cleaning solution 109 depends on the temperature of the cleaning solution 109. In order to increase the chemical reactivity of the cleaning solution 109 and thus the cleaning speed, the heating coil 138 heats the cleaning solution 109 to a predeterminable temperature. The temperature sensor T forms a temperature control circuit with the heating coil 138 in order to be able to set the predeterminable temperature. The centrifugal pump 108 draws the cleaning solution 109 from the container 132 via the pipe 140 and feeds it back to the fluid circuit 106.If the volume flow reaches an adjustable minimum volume flow or a predetermined cleaning time is reached, the contamination in the cooling channel 102 is considered removed and the cleaning process is terminated. Not in . Figure 1 Shown, however, the cleaning device 100 also includes a fresh water connection, a wastewater drain tap, and a power connection. In a second state, the directional control valve can be set so that the first connection is connected to the third connection 128 and the fourth connection to the second connection 126, i.e., the cooling channel 102 is cleaned in a different flow direction. During a cleaning process, the flow direction is continuously changed at a specific rhythm. This prevents clogging of the cooling channel and / or the cleaning device. Furthermore, a continuous change in the flow direction causes the cleaning fluid 109 to be thoroughly mixed.

[0033] In the Figure 2A cleaning device 200 for cleaning multiple channels according to a further embodiment of the invention is shown. The cleaning device 200 comprises eight connections 202 to 216 for connecting to the channels via hose lines. The eight connections 202 to 216 can be connected to one or more fluid circuits 106 via a directional control valve. The cleaning device 200 also comprises a programmable logic controller with a touchscreen 218. The programmable logic controller has multiple sensor inputs and control outputs, an operating system, and an interface via which a user program can be loaded. The user program determines how the control outputs are switched depending on the sensor inputs. The sensor inputs are connected in particular to the pressure sensor 110, the volume flow meter 122, the temperature sensor T, and the pH value sensor pH, see Fig. 1, electrically connected. The control outputs are electrically connected, in particular, to the frequency converter of the centrifugal pump 108, the directional control valve 125, and the heating coil 138.

[0034] According to one embodiment of the invention, the cleaning device 200 can be mounted on a flat pallet 220. The cleaning device 200 has a maximum width of 800 mm and a maximum length of 1200 mm. Alternatively, the cleaning device 200 can have integrated recesses for receiving forks. These configurations enable easy transport by means of an industrial truck with forks to an injection molding tool for a cleaning process, as well as easy storage of the cleaning device 200 when not in use, for example, in a pallet storage space in a high-bay warehouse.

[0035] In the Figure 3A cleaning method 300 according to an embodiment of the invention is shown. In a step 302, cleaning fluid is conveyed at varying pressure by means of a controllable fluid pump. In a further step 304, gas bubbles are generated by a gas bubble generating device. In a further step 306, the size of the gas bubbles is varied by means of the varying pressure of the cleaning fluid. In a further step 308, the gas bubbles and the cleaning fluid are mixed to form a gas bubble-cleaning fluid mixture. In a further step 310, the narrow, curved channel is cleaned by means of the gas bubble-cleaning fluid mixture. In a further step, not in Fig. 3As shown, the gas bubble size is adjusted depending on the cross-sectional area of ​​the narrow, curved channel. In a further step, the cleaning fluid is neutralized with a neutralizing agent after use and then disposed of. Before step 302, the fluid pump can pump fresh water to measure the volume flow rate using the volume flow meter 122, see Fig. 1 to be able to perform a leak test on the cleaning device. In a further step, after completion of a cleaning operation, the programmable logic controller can save a cleaning report for a cleaned injection molding tool. The report includes the volume flows of the injection molding tool cooling channels achieved during the cleaning and an injection molding tool identifier.

[0036] According to a further embodiment, all elements of the cleaning device 100 that carry the cleaning liquid and the cleaning solution-gas bubble mixture are made of stainless steel. LIST OF REFERENCE SYMBOLS

[0037] 100 Cleaning device 102 Cooling channel 104 Injection molding tool 106 Fluid circuit 107 Pipeline 108 Centrifugal pump 109 Cleaning solution 110 Pressure sensor 112 Plastic hollow body 114 Bores 116 Compressed air connection 118 Compressed air reservoir 120 Air compressor 122 Flow meter 124 Pipeline 125 Directional control valve 126 Second connection 127 Hose line 128 Third connection 129 Hose line 130 Pipeline 132 Container 134 Filter 136 Contamination sediment 138 Heating coil 140 Pipeline pH pH value sensor Temperature sensor 200 Cleaning device 202 - 216 Connections 218 Touchscreen 220 Flat pallet 300Cleaning procedures 302 - 310Steps

Claims

1. Cleaning apparatus (100; 200) for cleaning a narrow, curved channel (102), comprising a liquid pump (108) for pumping a cleaning liquid (109), it being possible for the liquid pump (108) to be controlled such that it pumps the cleaning liquid (109) at varying pressure, and a gas bubble-generating device (112) having a compressed air compressor (120) for generating gas bubbles characterized in that the compressed air compressor (120) comprises a compressor with controllable compression, it being possible for the compressed air compressor (120) to be controlled such that it generates gas bubbles of variable size and mixes them with the cleaning liquid (109) to form a gas bubble-cleaning liquid mixture in order to clean the narrow, curved channel (102) with the gas bubble-cleaning liquid mixture.

2. Cleaning apparatus (100; 200) according to claim 1 characterized in that the gas bubble-generating device (112) has a gas bubble-injection apparatus (112) which injects the gas bubbles into the cleaning liquid and thereby generates the gas bubble-cleaning liquid mixture.

3. Cleaning apparatus (100; 200) according to claim 2 characterized in that the gas bubble-injection apparatus (112) has a hollow body comprising a plurality of bores (114), the bores having different diameters in a range of 0.1 to 0.5 mm.

4. Cleaning apparatus (100; 200) according to any of the preceding claims characterized in that the cleaning apparatus (100; 200) has a flow rate measuring instrument (122) downstream of the liquid pump (108) which measures a flow rate of the cleaning liquid (109) and the gas bubble-cleaning liquid mixture.

5. Cleaning apparatus (100; 200) according to any of the preceding claims characterized in that the cleaning apparatus (100; 200) has a pressure gauge (110) downstream of the liquid pump (108), which measures a pressure of the cleaning liquid (109).

6. Cleaning apparatus (100; 200) according to any of the preceding claims characterized in that the cleaning apparatus (100; 200) comprises a container (132) downstream of the narrow, curved channel (102) for collecting the gas bubble-cleaning liquid mixture and contamination from the narrow, curved channel (102).

7. Cleaning apparatus (100; 200) according to claim 6 characterized in that the liquid pump (108), the pressure sensor (110), the gas bubble-generating device (112), the flow rate measuring instrument (122), a first connection (128; 202 - 216) for connection to a first opening of the narrow, curved channel (102), a second connection (128; 202 - 216) for connection to a second opening of the narrow, curved channel (102) and the container (132), in particular in the order mentioned, form a fluid circuit (106).

8. Cleaning apparatus (100; 200) according to claim 7 characterized in that the cleaning apparatus (100; 200) has a flow direction changing unit (125) for changing a flow direction of the cleaning liquid (109) and the gas bubble-cleaning liquid mixture.

9. Cleaning apparatus (100; 200) according to claim 8 characterized in that the cleaning apparatus (100; 200) comprises at least two fluid circuits (106) for cleaning at least two narrow, curved channels (102).

10. Cleaning apparatus (100; 200) according to any of claims 6 to 9 characterized in that the container (132) comprises a filter (134).

11. Cleaning apparatus (100; 200) according to any of claims 6 to 10 characterized in that the container (132) comprises a heating apparatus (138) for heating the cleaning liquid (109).

12. Cleaning apparatus (100; 200) according to any of claims 6 to 11 characterized in that the container (132) comprises a temperature sensor (T) for measuring a temperature of the cleaning liquid (109).

13. Cleaning apparatus (100; 200) according to any of the preceding claims characterized in that the cleaning liquid (109) comprises an acid.

14. Cleaning apparatus (100; 200) according to any of claims 6 to 13 characterized in that the container (132) comprises a pH value sensor (pH) for measuring a pH value of the cleaning liquid (109).

15. Cleaning method (300) for cleaning a narrow, curved channel comprising the following steps: pumping a cleaning liquid at varying pressure by means of a controllable liquid pump (302); generating gas bubbles using a gas bubble-generating device (304); varying the size of the gas bubbles by means of a compressed air compressor, which comprises a compressor with controllable compression; mixing the gas bubbles and the cleaning liquid to form a gas bubble-cleaning liquid mixture (308) and cleaning the narrow, curved channel by means of the gas bubble-cleaning liquid mixture (310).

16. Cleaning method (300) according to claim 15, wherein the gas bubble size is adjusted depending on the cross-sectional area of the narrow, curved channel.