METHOD FOR OPERATING A CLEANING SYSTEM, CLEANING SYSTEM

Description

[0001] The invention relates in a first aspect to a method for operating a cleaning system according to the preamble of claim 1. The invention relates in a second aspect to a cleaning system according to claim 18. The invention relates in a third aspect to a vehicle according to claim 22.

[0002] Cleaning systems and methods for cleaning sensor surfaces and similar surfaces, especially in the field of vehicles, are generally known.

[0003] DE 10 2017 010 254 A1 describes a cleaning device for selectively applying a medium sequence to a surface consisting of at least one first medium, in particular gaseous, and a second medium, in particular liquid, comprising: a nozzle designed for applying the second medium to the surface, a cleaning valve with a holding port, a pressure port, a plunger and a pressure outlet.

[0004] Besides this fundamentally advantageous approach, the use of a liquid cleaning medium leads to the problem that a sufficiently large storage tank must be provided for regular use of the cleaning device. This creates a conflict of objectives due to the installation space and weight restrictions that prevail, especially in vehicles.

[0005] Cleaning with a liquid medium also typically impairs the sensor's measurement signal, especially a camera image, for a short period of time.

[0006] German patent DE 10 2012 218 583 A1 describes a camera washing device comprising an air pump, a wash water tank for storing wash water, a spray nozzle with a spray section, a merging connector having a high-pressure air passage and a wash water passage, and an electromagnetic valve. The air pump generates and supplies high-pressure air to the high-pressure air passage. When the control unit instructs the electromagnetic valve to open, the wash water and the high-pressure air are mixed in the merging connector, generating water particles. These water particles are then fed to the spray nozzle.

[0007] EP 2 873 572 A1 discloses a cleaning device for a vehicle-mounted camera, which cleans a lens surface mounted on a vehicle, the cleaning device comprising: a nozzle having a dispensing opening from which a cleaning fluid and compressed air are dispensed, and which is positioned so that it faces the lens surface, and a cleaning fluid path which leads the cleaning fluid to the dispensing opening, and having an air passage which is configured to lead the compressed air to the dispensing opening, in which a distant end section of the cleaning fluid path and a distant end section of the air passage are positioned such that they are adjacent to each other or that they are joined together; a cleaning fluid supply section which supplies the cleaning fluid to the nozzle through a cleaning fluid line;wherein the control section performs a cleaning with a continuous water supply mode in which the cleaning fluid supply section is driven, and the compressed air supply section is driven intermittently for a plurality of time points to expel the cleaning fluid and the compressed air jet from the discharge opening, causing the cleaning fluid to drip onto the light disk surface.

[0008] In the aforementioned approaches, the problem of water-saving cleaning is already generally recognized and is taken into account in DE 10 2012 218 583 A1 by mixing air into a water jet and in EP 2 873 572 A1 by generating a water mist.

[0009] EP 3168094 A1 further describes a system for cleaning an external, vehicle-mounted sensor surface, comprising: an air nozzle designed to discharge air onto a sensor surface; an air pump comprising a fluid inlet, an air outlet, an air-fluid interface, and a variable volume compression chamber communicating with the air outlet; further comprising: an air flow control device communicating with the air nozzle and the air outlet to control the air flow therethrough; and a liquid pump communicating with the fluid inlet to supply a flow of pressurized liquid such that the volume of the compression chamber changes to generate a volume of compressed air at an absolute pressure below 10 bar.

[0010] The approach described in EP 3168094 A1 also addresses fluid consumption and generally describes the possibility of different cleaning cycles. WO-A-2019 / 238764 also discloses a similar method for operating a cleaning system.

[0011] However, achieving effective cleaning with minimal fluid consumption remains problematic. It would be desirable to specify a cleaning method that improves at least one of the disadvantages present in the current state of the art.

[0012] This is where the invention comes in, the object of which is to provide an improved method, and in particular to enable effective cleaning of a sensor surface with the lowest possible liquid consumption.

[0013] The problem concerning the method is solved by a method according to claim 1.

[0014] The invention relates to a method for operating a cleaning system for cleaning a sensor surface of a sensor of a vehicle, in particular an optical sensor, comprising the step: Applying a quantity of compressed air to the sensor surface in one air cleaning step.

[0015] According to the invention, the method includes checking an air purification result in one test step, wherein, in the event of a negative air purification result, a hybrid purification step is carried out, comprising: Applying a quantity of cleaning fluid to the sensor surface in a fluid, in particular liquid, cleaning step and applying a quantity of compressed air to the sensor surface in a further air cleaning step.

[0016] The invention is based on the consideration that saving fluid, especially cleaning fluid, is generally advantageous, particularly in vehicles. The invention incorporates the finding that cleaning with air, especially compressed air, is generally preferable to liquid cleaning because no cleaning fluid is consumed in an air cleaning step, and the impairment of the sensor signal, especially a camera image, during cleaning is less than in a fluid, especially liquid, cleaning step. The invention recognizes, however, that cleaning with air alone may not be sufficient for heavier soiling. A cleaning fluid is, in particular, a cleaning liquid, but can also be, for example, a gas-water mixture in the form of a spray mist. A cleaning fluid can, in particular, contain antifreeze.

[0017] The invention has recognized that it is advantageous to control the cleaning process depending on a cleaning result, i.e., depending on a test step, in order to use a cleaning fluid - which is available in limited quantities on board a vehicle - sparingly, in particular only when cleaning with compressed air is unsuccessful.

[0018] By checking the air cleaning result after applying a compressed air pulse to the sensor surface, and only in the event of a negative air cleaning result, a hybrid cleaning step is advantageously performed. Only if the air cleaning result is negative, meaning that applying a compressed air pulse alone has not resulted in sufficient cleaning, is further cleaning carried out in a hybrid cleaning step, which includes applying a cleaning fluid and / or a compressed air pulse to the sensor surface.

[0019] In this way, the limited amount of cleaning fluid is used economically while simultaneously ensuring effective cleaning of the sensor surface.

[0020] Checking a cleaning result, in particular the air cleaning result, in a test step can be done in particular by receiving a cleaning signal which indicates whether cleaning is necessary due to existing contamination of the sensor.

[0021] The fluid cleaning step does not necessarily have to involve applying only liquid, but in further training it can include the cleaning fluid being a cleaning mixture, in particular a spray mist, which comprises a cleaning fluid and air, which is mixed, especially before the cleaning mixture is directed onto the sensor surface.

[0022] In a second aspect, the invention relates to a cleaning system for cleaning a sensor surface of a sensor, in particular an optical sensor, in a vehicle, comprising a cleaning device and a control unit configured to carry out a method according to the first aspect of the invention. In particular, the cleaning system is connected to a vehicle bus and / or other communication line of the vehicle in a signal-carrying manner in order to receive and / or transmit information regarding the cleaning method.

[0023] In a third aspect, the invention leads to a vehicle with a cleaning system according to the second aspect of the invention.

[0024] Advantageous further developments of the invention can be found in the dependent claims and specify in detail advantageous possibilities for realizing the concept explained above within the scope of the task and with regard to further advantages.

[0025] In particular, it is intended that the application of compressed air to the sensor surface in the subsequent air cleaning step takes place after the fluid, especially liquid, cleaning step. In such a sequence, the sensor surface can be effectively cleaned in the hybrid cleaning step, in particular by first softening contaminants with a cleaning fluid and then removing the softened contaminant residues with the compressed air.

[0026] According to the invention, it is provided that the fluid, in particular liquid, cleaning steps carried out are recorded. The system records the number of cycles of fluid, and especially liquid, cleaning steps performed, which is incremented after each cleaning step. Recording the number of cycles advantageously enables the control of the process, in particular the determination of a remaining number of cycles and / or a total number of cycles for determining the remaining operating time.

[0027] According to the invention, it is provided that The amount of cleaning fluid depends on the number of cycles such that a higher number of cycles leads to a larger amount of cleaning fluid, in particular increasing the amount of cleaning fluid up to a maximum cleaning fluid amount.

[0028] Recording the number of cycles within a single execution of the process allows for adjusting the cleaning fluid quantity based on the fluid, and in particular liquid, cleaning steps already performed. According to the invention, such adjustment of the cleaning fluid quantity allows for an initial attempt to clean the sensor surface with the lowest possible amount of cleaning fluid. Only if this proves unsuccessful can the cleaning fluid quantity be increased to improve the cleaning effect, particularly incrementally up to a maximum cleaning fluid quantity. The increase can be linear, i.e., by a constant amount with each cycle, or non-linear, for example, by doubling the quantity with each cycle. An increase, particularly a linear increase, of the cleaning fluid quantity can, for example, be made in steps between 2 ml and 20 ml.The maximum cleaning fluid quantity can be, for example, between 25 ml and 100 ml, preferably 40 ml. The starting cleaning fluid quantity can be, in particular, between 2 ml and 20 ml, preferably between 3 ml and 8 ml. When selecting the cleaning fluid quantities, the size of the area to be cleaned can be taken into account, such that a larger area requires a larger cleaning fluid quantity.

[0029] By recording the number of cycles, a total number of cycles can be determined to record the number of all fluid, especially liquid, cleaning steps since the last filling of the fluid tank, which advantageously allows the consumption of the cleaning fluid and, in particular, any residual fluid still present in the fluid tank to be recorded.

[0030] Alternatively or additionally, a remaining cycle count can be determined based on the residual fluid quantity in the fluid tank and the required cleaning fluid quantity, which is either estimated or averaged over several process runs. Based on the predicted remaining cycle count, it can be determined how many process runs can still be carried out with the remaining fluid quantity. The fluid tank can be equipped with a level sensor to determine the fill level.

[0031] According to the invention, the compressed air quantity is dependent on the number of cycles, such that a higher number of cycles results in a larger compressed air quantity, with the compressed air quantity being increased up to a maximum compressed air quantity. Analogous to the further development of the method in which the cleaning fluid quantity depends on the number of cycles, this further development offers the advantage that an attempt is first made to clean the sensor surface with a relatively small amount of compressed air, namely a starting compressed air quantity. Only if this is unsuccessful is the compressed air quantity increased up to the maximum compressed air quantity. When increasing the compressed air quantity, a residual compressed air quantity plays a subordinate role, since compressed air is generally generated by a compressor on board the vehicle and can be provided as needed, and / or can be stored in a compressed air reservoir.Therefore, the compressed air volume, in particular the starting and / or maximum compressed air volume, can be freely selected, and specifically solely based on the criteria of maximum cleaning performance. In particular, the compressed air volume can be greater than the cleaning fluid volume.

[0032] In a further advantageous development, both previous developments can be combined such that the cleaning fluid quantity and the compressed air quantity are increased together depending on the number of cycles. By thus jointly increasing the cleaning fluid quantity and the compressed air quantity depending on the number of cycles, the overall cleaning performance per cleaning cycle can advantageously be increased. Such a further development of the method can advantageously be implemented with a piston unit in which the compressed air quantity in an air chamber, due to the displacing movement of a pressure piston, also corresponds to a cleaning fluid quantity in a fluid chamber.

[0033] In particular, the starting compressed air quantity can be identical to the starting cleaning fluid quantity and / or the maximum compressed air quantity can be identical to the maximum cleaning fluid quantity and / or any increase in the compressed air quantity depending on the number of cycles can be identical to the corresponding increase in the cleaning fluid quantity.

[0034] It is advantageous that The sequence of steps following the hybrid cleaning step includes the following step: checking the hybrid cleaning result in a further test step, whereby the sequence of steps is repeated until a termination condition is reached.

[0035] In such a further development of the process, it is advantageous to terminate the process by means of a termination condition, thus avoiding an endless repetition of the cleaning steps.

[0036] The invention is further developed by the fact that the termination condition is reached when, as a first termination condition, the hybrid cleaning result is positive, or, as a second termination condition, when the number of cycles has reached a maximum value. In such a further development, the process is terminated by the first termination condition if the sensor surface is successfully cleaned. If cleaning is unsuccessful, the process is terminated by a second termination condition after a maximum value of the number of cycles has been reached, in order to advantageously save cleaning fluid. The second termination condition is therefore particularly useful if contamination is so stubborn that it cannot be removed by the cleaning system. In this case, a warning signal can be issued indicating that the sensor cleaning was unsuccessful.

[0037] In particular, it is intended that the test step for checking the air purification result and / or the further test step for checking the hybrid purification result is carried out via the sensor, especially the optical sensor, and / or its evaluation unit. By checking the purification result via the sensor to be cleaned itself, the need for additional sensors can be advantageously eliminated.

[0038] It is advantageously provided that the test step or the further test step is carried out during the air purification step or the further air purification step or This occurs within a waiting period after the air cleaning step or the subsequent air cleaning step. In a training course where the test step takes place during the cleaning step, an immediate assessment of the cleaning can be advantageously performed. In this case, it is particularly possible to adjust the compressed air volume depending on the cleaning result during the application. Thus, for example, in the case of light soiling, the application of compressed air can be stopped prematurely if the cleaning result is already positive.

[0039] It is advantageous that the waiting time is 500 ms. A waiting time of 500 ms represents a suitable compromise, as after this time a significant portion of the contaminants will have detached and removed themselves from the sensor surface after exposure, while at the same time achieving the fastest possible assessment of the cleaning result.

[0040] The invention is further developed by performing the method in the event of a negative initial cleaning result from an initial test step. In such a further development of the method, an initial test step can be carried out at predetermined time intervals and / or after a predetermined mileage of the vehicle in a starting step of the method to assess the necessity of cleaning the sensor surface.

[0041] In particular, the procedure is designed to be executed when a rain sensor detects a positive rain signal. This advanced feature can be implemented as an initial step, especially in addition to a cyclical execution of the initial test step. It advantageously utilizes the fact that, in the presence of rain, the sensor surface is more likely to be damp, meaning that contaminants may have already softened and / or loosened without the use of cleaning fluid. This allows for cleaning the sensor surface in a fluid-saving manner. A rain sensor already integrated into the vehicle's windshield wiper system can be used as the rain sensor.

[0042] In particular, the procedure is designed to be executed depending on an environmental variable. An environmental variable can, in particular, describe the probability of bad weather, i.e., especially the presence of rain, hail, or snow. For this purpose, the control unit of the cleaning system can be connected to control modules or sensors of the vehicle that serve another primary purpose, for example, a thermometer (especially an outside thermometer), a windshield wiper control unit, a windshield heating control unit, a rear window heating control unit, an anti-lock braking system (ABS) control unit, and / or an electronic stability control (ESP) control unit.Depending on the environmental variable, the frequency of the procedure can be adjusted, such that cleaning is carried out more frequently in bad weather to ensure the function of the sensor and / or to take advantage of the presence of moisture to perform a cleaning with compressed air only, thus saving cleaning fluid.

[0043] Advantageously, the system allows for the determination of a residual fluid quantity and / or remaining operating time of the cleaning system, particularly based on the number of remaining cycles or the total number of cycles. The residual fluid quantity in the fluid tank can be determined directly by measuring a level sensor. Alternatively, the residual fluid quantity can be approximated based on the actual amount of cleaning fluid consumed and the tank volume.

[0044] The remaining number of cycles can be determined, in particular, based on the residual fluid volume and a defined constant or estimated expected, especially averaged, cleaning fluid volume per fluid cleaning step. The remaining operating time can be determined based on the residual fluid volume and assuming an average time interval between two cleaning cycles, as well as an expected cleaning fluid volume per cycle, where the expected cleaning fluid volume per cycle is based on the expected number of cycles per cycle and a defined constant or estimated expected, especially averaged, cleaning fluid volume per fluid cleaning step.

[0045] In such a further development of the method, the remaining fluid quantity can advantageously be incorporated into the vehicle's route planning. In particular, it can prevent situations where the cleaning fluid suddenly runs out and the cleaning system fails. This effectively avoids vehicle downtime and interruptions due to a dirty sensor. If the remaining fluid quantity and / or operating time is insufficient to reach a refilling point for the cleaning tank, a driver or operator can be prompted to take control of the vehicle in a timely manner, especially in an autonomous or semi-autonomous vehicle during autonomous driving functions, if it is foreseeable that the cleaning system will no longer be able to function after the remaining operating time.Alternatively, if the cleaning system can no longer guarantee a cleaning function, a vehicle, especially an autonomous vehicle, can be brought to a safe holding state, i.e., stopped.

[0046] The invention is further developed in that, after checking the air purification result in the test step, if the air purification result is negative, an additional air purification process is carried out, which includes the following steps: Applying an additional quantity of compressed air to the sensor surface in an additional air cleaning step, and checking the air cleaning result in an additional test step. In such a further development – ​​based on the concept of the invention to save as much liquid as possible during cleaning – an attempt is first made to clean the sensor surface with one or more further additional air cleaning steps before a quantity of cleaning fluid is used in a hybrid cleaning step.

[0047] In particular, it is provided that the additional air cleaning process is repeated until the air cleaning result is positive or an additional termination condition is met. In such a further development, the additional air cleaning process can be repeated until the air cleaning result is positive, and thus the cleaning of the sensor surface was successful, or – if the air cleaning result is negative over one or more runs – it can be terminated after a defined number of attempts by reaching an additional termination condition.

[0048] In particular, it is stipulated that the additional termination condition is reached when the number of additional cycles reaches a maximum value. By recording the number of additional cycles in an additional counting step, the number of executions of the additional air purification process can be recorded, and, in particular, the additional air purification process can be terminated when a maximum value is reached in order to transition to the hybrid purification step. The maximum value can be, for example, 1, 3, 5, or 10.

[0049] In particular, it is provided that the additional compressed air quantity depends on the number of additional cycles, such that a higher number of additional cycles leads to a larger additional compressed air quantity.

[0050] The invention is further developed in that the cleaning signal and / or the cleaning result is generated based on a target-actual comparison, in particular based on a brightness deviation and / or a contrast deviation. Specifically, the target-actual comparison comprises a comparison of the sensor signal SI or a feature of the sensor signal SI as the actual value with a comparison or reference sensor signal as the target value. Specifically, a cleaning signal is output when a deviation between the target and actual values ​​is exceeded. Specifically, a negative cleaning result is output when a deviation between the target and actual values ​​is exceeded.

[0051] The invention is further developed in that the actual signal is generated by the sensor signal, and the target signal is generated by a comparison sensor signal, which is provided in particular by at least one further sensor, and / or by a reference sensor signal, which is provided in particular by a reference memory. By comparing the actual signal with a comparison or reference sensor signal, a sensor signal can be better validated and / or its plausibility improved, thus advantageously generating a more reliable cleaning signal and / or cleaning result.

[0052] In particular, to determine a cleaning signal and / or a cleaning result, an average brightness value of the image of the camera signal can be determined and compared with one or more brightness deviations, especially those occurring at specific points.

[0053] In particular, to determine a cleaning signal and / or a cleaning result, an average brightness value can be compared with an average reference brightness value, wherein the average reference brightness value is provided by one or more additional sensors, in particular one or more additional cameras.

[0054] In particular, to determine a cleaning signal and / or a cleaning result and / or a rain signal, a contrast or a contrast mean value in the form of a gray value gradient or a color value gradient can be formed, whereby to determine a contrast deviation the gray value gradient can be compared with a reference gray value gradient, or the color value gradient can be compared with a reference color value gradient.

[0055] As part of a preferred further development of the cleaning system, a sensor evaluation device is provided, wherein the sensor evaluation device in particular comprises a target-actual comparison module and / or a brightness comparison module and / or a camera image comparison module and / or a contrast comparison module.

[0056] As part of a preferred further development of the cleaning system, a communication interface is provided that is configured for communication with a vehicle bus and / or a wireless communication device. Such a communication interface advantageously enables bidirectional communication for external control of the cleaning process, in particular for the external generation of a cleaning signal. In further developments, the communication interface can also be configured for communication with a wired communication device.

[0057] In a preferred embodiment of the cleaning system, it includes a trigger switch. In a further preferred embodiment, the cleaning system is configured to communicate with a trigger switch and / or a communication device, in particular wired or wirelessly, especially for transmitting a cleaning signal to the cleaning system.

[0058] In a particularly preferred embodiment of the cleaning system, a common nozzle is provided for applying a quantity of compressed air and a quantity of cleaning fluid to the sensor surface. The use of a common nozzle advantageously results in a compact design of the cleaning device, particularly of an application module, at the sensor surface. Furthermore, the risk of the nozzle freezing is advantageously reduced because the nozzle can be blown clear with compressed air after each use, thereby removing any remaining cleaning fluid.

[0059] As part of a particularly advantageous further development of the cleaning system, a common medium line is provided. A common medium line advantageously achieves a space-saving design. It also advantageously prevents the risk of the cleaning fluid freezing in the medium line, since the medium line can always be blown clear after each use, thus removing the cleaning fluid.

[0060] In a particularly preferred embodiment of the cleaning system, the cleaning system comprises a piston unit with a fluid chamber and an air chamber, wherein the fluid chamber and the air chamber are sealed from each other by an axially movable pressure piston. In particular, the piston unit has a return spring that connects the pressure piston to the housing of the piston unit in order to generate a return force acting axially on the pressure piston, in particular to move the pressure piston to a rest position after it has been pressurized with compressed air.

[0061] In a further development of the vehicle, the vehicle is an autonomous vehicle. In this further development, the vehicle has a vehicle bus, in particular a CAN bus, and the cleaning system has a communication device that can be connected to and / or is connected to the vehicle bus via a signal transmission system.

[0062] Embodiments of the invention are now described below with reference to the drawing. The drawing is not necessarily intended to represent the embodiments to scale; rather, where this is helpful for clarification, it is presented in a schematic and / or slightly distorted form. With regard to additions to the teachings directly apparent from the drawing, reference is made to the relevant prior art. It should be noted that numerous modifications and changes concerning the form and details of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, the drawing, and the claims can be essential for the further development of the invention, both individually and in any combination.Furthermore, the invention encompasses all combinations of at least two of the features disclosed in the description, the drawing, and / or the claims. The general idea of ​​the invention is not limited to the exact shape or detail of the preferred embodiments shown and described below, nor is it limited to an object that would be restricted compared to the object claimed in the claims. Where specified dimensioning ranges are given, values ​​lying within the stated limits are also disclosed as limit values ​​and may be used and claimed as desired. For the sake of simplicity, identical or similar parts, or parts with identical or similar functions, are used below as reference numerals.

[0063] Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiments and from the drawing; this shows in: Fig. 1A a cleaning system configured to carry out the method according to the first aspect of the invention, Fig. 1B, 1C a sensor evaluation device and a diagram demonstrating its operation, Fig. 2A a further development of a method according to the first aspect of the invention, Fig. 2B a section of a further development of the method with an additional air cleaning process, Fig. 3 a first further development of a cleaning device for a cleaning system according to the second aspect of the invention, Fig. 4A, 4B each a second further development of a cleaning device for a cleaning system according to the second aspect of the invention, Fig. 5 a vehicle with a cleaning system according to the second aspect of the invention, Fig. 6 a schematic diagram of exemplary residual fluid quantities and cycle numbers.

[0064] Fig. 1A Figure 1 shows a cleaning system 100 for cleaning a sensor surface 300 of a sensor 301 designed as an optical sensor 302 of a vehicle 1000 (not shown in detail here). The optical sensor 302 is designed in this case as a camera 304 for environmental sensing. The cleaning system 100 also includes a control unit 900, which has a program memory 910 in which a procedure 400 for execution can be stored.

[0065] Sensor 301 is connected to control unit 900 via sensor line 902 for the transmission of a sensor signal SI. Optionally, sensor 301, particularly if connected in sensor line 902, can include a sensor evaluation unit 348 or a similar signal processing unit in which the sensor signal SI is processed. In this case, sensor 301 is connected to the sensor evaluation unit 348 via sensor line 902, and the sensor evaluation unit 348 is connected to control unit 900 via an evaluation line 903. In a sensor evaluation unit 348 or a similar evaluation unit of sensor 301 and / or vehicle 1000, the sensor signal SI can be evaluated, in particular, to determine whether cleaning is required.Depending on this test, and in particular on sensor contamination and the associated deterioration of the sensor signal SI's signal quality, a cleaning signal SC can be output. Similarly, the sensor evaluation unit 348 can provide a cleaning result RE, in particular an initial cleaning result, an air cleaning result LRE, or a hybrid cleaning result. The cleaning signal SC can be binary and / or Boolean and take the value "1" or "TRUE" when cleaning is required and the value "0" or "FALSE" when no cleaning is required. Alternatively or additionally, the cleaning signal SC can be a voltage, with a voltage of, for example, 5 volts when cleaning is required and no voltage, i.e., a voltage of 0 volts, when no cleaning is required.The cleaning signal can also be transmitted via the vehicle CAN bus or a subordinate vehicle bus.

[0066] An air cleaning result LRE, a hybrid cleaning result HRE and / or an initial cleaning result IRE can be transmitted to the control unit 900 via the sensor line 902.

[0067] The cleaning signal SC can be generated by a variety of methods or a combination of different methods by the sensor evaluation unit 348, in particular by different modules 349, 349.1, 349.2, 349.3 of the sensor evaluation unit 348. It is clear to those skilled in the art that there may be preferred methods for determining the signal quality and for determining a cleaning signal SC for each type of sensor. In general, other sensor systems such as radar, lidar, infrared, or ultrasonic sensors, which can be used as sensor 301, are less susceptible to slight contamination than cameras. Nevertheless, they may need to be cleaned of contaminants on their surfaces. For the generation of the cleaning signal SC, a target-actual comparison 350 can preferably be performed in the sensor evaluation unit 348, in particular in a target-actual comparison module 349.In a target-actual comparison module 349, a sensor signal SI, in particular a camera signal SIK, can be compared as the actual signal SSI with a reference sensor signal SIR as the target signal SSS. A reference sensor signal SIR can be stored and made available in a reference memory 940. Alternatively or additionally, the target-actual comparison module 349 can compare a sensor signal SI, in particular a camera signal SIK, with a comparison sensor signal SIV as the target signal SSS, in particular with a comparison camera signal SIKV, in order to, for example, infer contamination 310 of the sensor surface 300 and, in particular, to exclude other influences such as darkness by comparison with a current comparison signal. The comparison sensor signal SIV can be provided by another sensor 930, in particular from the same vehicle 1000.If the target / actual comparison module 349 detects that the sensor signal SI or a feature of the sensor signal SI exceeds a limit value, in particular a reference sensor signal SIR and / or a comparison sensor signal SIV, or exceeds it by a certain tolerable amount, a cleaning signal SC is output by the sensor evaluation unit 348. Such a comparison can refer to the entire contaminated sensor surface 300 and / or to a partial area TB of the contaminated sensor surface 300. However, a comparison with a limit value can also refer to noise or a variation in the sensor signal SI, in particular the camera signal SIK, which arises from contamination 310 of the sensor surface 300.

[0068] The deterioration of signal quality can be detected in the sensor evaluation unit 348 by various methods, which may be implemented in modules 349.1, 349.2, 349.3 of the sensor evaluation unit 348, see Fig. 1B Modules 349.1, 349.2, and 349.3 represent, in particular, further developments of the target-actual comparison module 349. The sensor evaluation unit 348 can include a brightness comparison module 349.1. If, for example, a cleaning signal SC and / or a cleaning result RE is to be determined as a function of a sensor signal SI configured as a camera signal SIK, an average brightness value HWD of the image of the camera signal SIK can be determined in a brightness comparison module 349.1 and compared with, in particular, spot-occurring brightness deviations HWA (see...). Fig. 1C The average brightness value HWD is calculated, in particular, by averaging individual brightness values ​​HW of a number, especially the entirety, of sub-areas TB or pixels PX of the image of the camera signal SIK. A contamination 310 on the sensor surface 300, in particular a spot on the camera lens of a camera 304 caused by dirt, produces, especially at a localized point in a sub-area TB or a pixel PX, a lower brightness value HW than is the case in the rest of the image of the camera signal SIK, in particular lower than the average brightness value HWD, so that contamination 310 can be inferred and a cleaning signal SC can be output accordingly.

[0069] The sensor evaluation unit 348 can include a camera image comparison module 349.2. In particular, if the entire sensor surface 300 of the camera 304, or a predominant part thereof, is covered by contamination 310, the entire image exhibits an unexpected brightness value, especially an unexpectedly low average brightness value HWD. To validate the brightness, especially an unexpectedly low average brightness value HWD, the camera image comparison module 349.2 can take into account images from one or more additional sensors 930, especially additional cameras 932, and / or the time UZ. The time UZ can be provided, in particular, by the control unit 900. The at least one additional camera 932 can provide a comparison camera image SIKV with an average comparison brightness value HWDV.Alternatively or additionally, the average reference brightness value HWDV can be provided by another suitable sensor 930. By comparing this value with the reference brightness value HWDV, it becomes possible to determine whether there is contamination 310 or whether the environment is simply dark. The same applies to the influence factor of the time of day UZ, which can be used to account for the time-of-day-dependent lighting conditions and is intended, in particular, to represent the difference between day and night.

[0070] The sensor evaluation unit 348 can further include a contrast comparison module 349.3. Image evaluation in the contrast comparison module 349.3 is performed by comparing a contrast KK, in particular a sub-area TB of the camera signal SIK, and / or by comparing it to a contrast mean value KKD calculated over the entire image of the camera signal SIK. A contrast KK and / or a contrast mean value KKD can be determined, in particular, via a grayscale gradient GGW or a chromatic gradient GFW. A blurred image, and thus in particular the occurrence of rain, can be detected by recognizing that an unclear edge image is present – ​​as in Fig. 1C This is shown as an example for another sub-area TB2. This means, in particular, that the grayscale gradient GGW or the chromatic gradient GFW is no longer plausible and / or can no longer be plausibly determined. The grayscale gradient GGW and / or the chromatic gradient GFW can be determined for a sub-area TB2 or for the entire image of the camera signal SIK. The grayscale gradient GGW can be compared with a reference grayscale gradient GGWR to determine whether a contrast deviation KA is present. The chromatic gradient GFW can be compared with a reference chromatic gradient GFWR to determine whether a contrast deviation KA is present. Based on a contrast deviation KA, a rain signal SR and / or a cleaning signal SC can be provided by the contrast comparison module 349.3. In particular, the contrast comparison module 349.3 can provide the rain signal SR as an alternative or in addition to a rain sensor 330.Furthermore, the contrast comparison module 349.3 can determine a dirty sensor surface 300, in particular a damp dirty surface 300, via a differing gray value gradient GGW or color value gradient GFW based on the contrast deviation KA.

[0071] Alternatively or additionally, the cleaning signal SC can also be generated manually.

[0072] If the driver detects, for example on a display, that the camera signal SIK and / or the sensor signal SI is malfunctioning, they can also manually generate the cleaning signal SC, in particular by actuating a trigger switch 950 and / or other actuating device for generating the cleaning signal SC in order to execute procedure 400. The trigger switch 950 can be designed as a physical switch or button, or as a programmatic implementation of a control panel in a graphical user interface, for example in a touch-sensitive display. This makes it possible to react to situations in which the sensor evaluation unit 348 cannot provide valid values ​​and / or has failed, or in which the cleaning result RE is insufficient for the driver. It should be noted that this is independent of where the display is located, whether inside or outside the vehicle.

[0073] The cleaning system 100 can have a communication interface 952 configured for communication with a vehicle bus 954 and / or a wireless communication device 956. For example, a cleaning system can be retrofitted as a retrofit solution into a vehicle with such a vehicle bus 954, in particular a CAN bus, via such a communication interface 952. The communication interface 952 can be configured for wired and / or wireless communication.

[0074] In particular, the communication interface 952 can be configured for wireless communication with a wireless communication device 956. A wireless communication device 956 can be, in particular, a computer, handheld device, smartphone, or similar mobile terminal. The connection between the communication interface 952 and the wireless communication device 956 can be established via a suitable radio protocol, such as WLAN, Bluetooth, GSM, UMTS, or the like. Communication between the communication interface 952 and the wireless communication device 956 can be direct or indirect, via servers, radio masts, and / or similar infrastructure components.

[0075] Alternatively or additionally, the cleaning signal SC can also be generated by an operator who is not in the vehicle and monitors the camera image and / or other sensor results via an external display. This is particularly relevant for remotely controlled vehicles. Here, the cleaning signal SC is generated by the driver / operator via a wireless communication device 956, which could be, for example, a mobile device or a computer. This is particularly advantageous when a driver / operator has to monitor several vehicles that operate autonomously. The cleaning signal SC can also be sent to the vehicle via a wireless transmission device. The vehicle receives the cleaning signal SC, which was sent by a wireless communication device 956, via the communication interface 952 and transmits it to the cleaning system 100.The transmission can alternatively or additionally take place via a vehicle bus 954 and / or another data connection within the vehicle 1000. The cleaning signal SC can also be transmitted wirelessly directly to the cleaning system 100.

[0076] Analogous to the methods described here for generating the cleaning signal, a cleaning result can also be determined.

[0077] The cleaning system 100 further comprises a cleaning device 318, which is connected to the control unit 900 via a control line 904. The cleaning device 318 has a nozzle 320, which is designed and arranged to direct both a quantity of compressed air M1 and a quantity of cleaning fluid M2 onto the sensor surface 300. The cleaning system 100 has a compressed air source 314, or is pneumatically connected to such a compressed air source 314, to provide a quantity of compressed air M1. In particular, the compressed air source 314 can be designed as a compressed air reservoir or as a compressor. Furthermore, the cleaning device 318 has a cleaning fluid source 315 for providing the quantity of cleaning fluid M2. The cleaning fluid source 315 can have a fluid tank 316, wherein the quantity of cleaning fluid M2 can be directed under pressure through the nozzle 320 via the compressed air source 314, in particular by means of a piston unit.In further training, the cleaning fluid source 315 can also include a pump for conveying the cleaning fluid quantity M2 through the nozzle 320. The cleaning fluid source 316 or the fluid tank 316 can include a level sensor 346 for determining a residual fluid quantity MR and / or a remaining number of cycles ZR.

[0078] The control unit 901 can transmit a compressed air control signal SM1 to the cleaning device 318 via control line 904 to apply a quantity of compressed air M1 to the sensor surface 300. The control unit 901 can also transmit a cleaning fluid control signal SM2 to the cleaning device 318 via control line 904 to apply a quantity of cleaning fluid M2 to the sensor surface 300. This process cleans the sensor surface 300, i.e., removes dirt 310.

[0079] The cleaning device 318 can include electromagnetic actuating means, in particular electromagnetic valves, for selectively controlling the compressed air quantity M1 and / or the cleaning fluid quantity M2.

[0080] The control unit 900 can optionally include an environment determination unit 912, which can be connected via a system line 906 to at least one of the following systems for determining an environment variable VU based on at least one environment signal SU: rain sensor 330, thermometer 360, in particular outside thermometer 361, a windshield wiper control unit 362, a windshield heating control unit 364, a rear window heating control unit 366, an anti-lock braking system (ABS) control unit 368, and / or a control unit for an electronic stability control (ESP) 370.

[0081] Fig. 2A shows a further development of a method 400 according to the concept of the invention.

[0082] At the start step 402, it is first checked whether the execution of procedure 400 should begin. For this purpose, the start step 402 can in particular include an initial check step 410, in which an initial cleaning result IRE is queried from the sensor 301 (not shown here).

[0083] Alternatively or additionally, the procedure 400 can be executed depending on a rain signal SR and / or other environmental signals SI. This means that in the case of a positive rain signal SR, the presence of rain moisture can be advantageously used for cleaning the sensor surface 300, in particular without consuming cleaning fluid. Alternatively or additionally, an environmental variable VU can be determined based on one or more environmental signals SI, depending on which the procedure 400 is executed or not.

[0084] In the first branch V1, it is checked whether the initial cleaning result (IRE) is negative. A cleaning result (RE), and in particular an initial cleaning result (IRE), is negative if a certain degree of contamination has been exceeded, which can be determined, for example, by the decreasing light transmittance with increasing contamination. Specifically, this can be detected when the brightness of sensor 301 falls below a certain threshold. In a camera using an optical sensor, the cleaning result (RE) can be determined by comparison with a reference image, whereby the differences from the reference image increase with increasing contamination.

[0085] If the initial cleaning result IRE is negative, an air cleaning step 412 is performed, in which the sensor surface 300 is exposed to a quantity of compressed air M1. Simultaneously or subsequently, in a test step 413, the air cleaning step 412 is checked by querying the sensor 301 for an air cleaning result LRE. In further developments of the method, the checking of a cleaning step, in particular the air cleaning step 412, can be carried out by receiving a cleaning signal SC, which indicates the necessity of cleaning and thus, in particular, the success of a previous cleaning step. The determination of the air cleaning result LRE is analogous to the cleaning result RE described above. In a second branch V2, it is checked whether the air cleaning result LRE is negative.

[0086] If the air purification result LRE is positive, air purification step 412 was successful, and the process returns to the starting step 402. After returning to the starting step 402, the process 400 is executed again, optionally after a defined time interval and / or depending on the rain signal SR and / or other starting conditions.

[0087] In the event that the air cleaning result LRE is negative, a hybrid cleaning step 430 is performed, which in turn includes a fluid, in particular liquid, cleaning step 414 and a further air cleaning step 416.

[0088] In fluid, and in particular liquid, cleaning step 414, the sensor surface 300 is first treated with a quantity of cleaning fluid M2, followed immediately or after an adjustable waiting period in a further air cleaning step 416 by treatment with a quantity of compressed air M1. The quantity of compressed air M1 can correspond to the quantity of compressed air M1 from the air cleaning step 413, or it can differ from it, i.e., be more or less.

[0089] Following hybrid cleaning step 430, a further test step 417 is performed to verify the effectiveness of hybrid cleaning step 430. In this further test step 417, analogous to the cleaning result RE described above, a hybrid cleaning result HRE is queried from sensor 301.

[0090] In a third branch V3, it is checked whether the hybrid cleaning result HRE is positive or negative. If the hybrid cleaning result HRE is positive, a first termination condition AB1 is met and the process, as in the case of the second branch V2, returns to the start step 402.

[0091] If the hybrid cleaning result HRE is negative, the number of cycles ZZ is increased by 1 in counting step 418. A cycle specifically describes one execution of the following steps: fluid cleaning step 414, further air cleaning step 416, and further test step 417.

[0092] Across multiple runs of the process, a total number of cycles ZG can be determined, which captures the total number of fluid, in particular liquid, cleaning cycles, especially since the last filling of the fluid tank.

[0093] In particular, the total number of cycles ZG is also increased for a fluid cleaning cycle with a positive cleaning result, so that all fluid cleaning cycles are recorded, which is advantageous for the accurate calculation of a residual fluid quantity. In other further developments, a total number of cycles ZG can also be calculated in a different way, for example, by increasing the total number of cycles ZG with each execution of the process, for example, after the air cleaning step 412.

[0094] Optionally, a residual fluid quantity MR still available in fluid tank 316 can be determined based on the number of cycles ZZ and the respective amount of cleaning fluid M2 used. In further training courses where a level sensor 346 is present in fluid tank 316, the residual fluid quantity MR can alternatively or additionally be determined by sensor.

[0095] Based on the residual fluid quantity MR, a remaining operating time TR can be predicted. Assuming an average time interval TD between two cleaning cycles, the remaining operating time TR indicates how long the cleaning system 100 can continue to operate with the existing residual fluid quantity MR. The average time interval TD can be determined, in particular, based on a current environmental variable VU, or as the mean of a set of past environmental variables, for example, environmental variables determined over the last 100 km, to obtain a time-averaged value as the average time interval TD.Based on the remaining operating time TR, a corresponding vehicle stop for refilling the fluid tank 316 can be taken into account in route planning, especially in the case of an autonomous vehicle 1001, and / or – especially in the case of a conventional, non-autonomous or semi-autonomous vehicle – a corresponding message can be generated for the driver due to the fact that cleaning can no longer be guaranteed, which in particular calls for taking control of the vehicle.

[0096] In a subsequent fourth branch V4, it is checked whether the number of cycles ZZ has exceeded a maximum value ZM. If this is not the case, the process returns to the hybrid cleaning step 430, meaning that the fluid cleaning step 414 and the subsequent air cleaning step 416 are repeated. In particular, the amount of cleaning fluid M2 is increased depending on the number of cycles ZZ.

[0097] This means that the more often hybrid cleaning step 430 is performed, the greater the amount of cleaning fluid M2. This relationship is based on the idea that if the hybrid cleaning result HRE is negative, the amount of cleaning fluid M2 in the subsequent hybrid cleaning step 430 can be successively increased to enhance the cleaning effect up to a maximum cleaning fluid amount M2M, until a positive hybrid cleaning result HRE is achieved and, in the third branch V3, a return to the starting step 402 occurs.

[0098] If, despite repeated execution of hybrid cleaning step 430, a positive hybrid cleaning result (HRE) is not achieved, a second termination condition (AB2) is triggered in the fourth branch (V4) when the maximum value (ZM) of the number of cycles (ZZ) is reached. This triggers an error message in error step 420. The error message can be transmitted, in particular, from control unit 900 to a vehicle control unit 1010 of vehicle 1000 (not shown here) and from there to a driver or an operator responsible for an autonomous vehicle 1001. Following error step 420, a fifth branch (V5) checks whether sensor 301 is a safety-relevant sensor.If this is the case, in an emergency running step 422, an emergency running mode of the vehicle 1000 is initiated, or a signal to initiate such an emergency running mode is transmitted, in particular to the vehicle control unit 1010, in order to minimize the risk of hazards to the vehicle 1000 and / or the area surrounding the vehicle 1000 due to the impaired functionality of the sensor 301. In an emergency running mode, the speed may be reduced, or manual intervention by an operator or further safety measures may be required. If the sensor 301 is not a safety-relevant sensor, the procedure 400 is aborted in a termination step 424. In this case, a message is generated, in particular to request further cleaning, especially manual cleaning, of the sensor surface 300.

[0099] Fig. 2B shows - with reference to Fig. 2A - An excerpt of an optional further development of the procedure with an additional air cleaning sequence 442, which can be carried out in step 440 after checking the air cleaning result LRE in test step 413, specifically in the case of a negative air cleaning result LRE. After the negative air cleaning result LRE has been determined in the second branch V2, the sensor surface (300) is again subjected to an additional compressed air quantity M1Z in an additional air cleaning step 444. The additional compressed air quantity M1Z can correspond to the compressed air quantity M1. The additional compressed air quantity M1Z can also be determined as a function of an additional number of cycles ZZZ, analogous to determining the compressed air quantity M1 as a function of the number of cycles ZZ.

[0100] Following the additional air cleaning step 444, the air cleaning result LRE is checked again in an additional test step 446. In a sixth branch V6, it is checked whether the air cleaning result LRE is positive or negative. In the case of a positive air cleaning result LRE, the process returns to the start step 402, since in this case the cleaning of the sensor surface was successful only by means of air or additional air cleaning steps. In the case of a negative air cleaning result LRE, an additional counting step 448 increments the additional cycle count ZZZ, which records the number of executions of the additional air cleaning process 442 within one execution of the step sequence 440. In a seventh branch V7, it is checked whether the additional cycle count ZZZ has reached an additional maximum value ZZM.If this is not yet the case, the process returns to the additional air cleaning step 444 for a repeat execution of the additional air cleaning sequence 442. If the number of additional cycles ZZZ has reached the maximum additional value ZZM, an additional termination condition AB3 is reached, and the hybrid cleaning step 430, and in particular the fluid, especially liquid, cleaning step 414, is executed. Consequently, the process 400, in particular as described in , is carried out. Fig. 2A shown, continued.

[0101] Fig. 3 Figure 318 shows a cleaning device 318 for a cleaning system 100 according to the concept of the invention. For cleaning a sensor surface 300 of a sensor 301 (not shown), a nozzle 320 is arranged in an application module 326. The nozzle 320 is fluid-carrying connected to a combination unit 328 via a common medium line 312. The cleaning fluid M2 is supplied to the combination unit 328 via a fluid line 332 and is controllable via a fluid valve 324. The combination unit 328 has a piston unit 322. When a quantity of cleaning fluid M2 is supplied to the combination unit 328, it collects in the piston unit 322. By applying pressure to a pressure port 336 of the piston unit 322, the quantity of cleaning fluid M2 located in the piston unit 322 can be directed under pressure via the common medium line 312 and the nozzle 320 to the sensor surface 300.For this purpose, the pressure port 336 is connected via a piston unit line 344 to a compressed air source 314 (not shown). A compressed air valve 338, arranged in the piston unit line 344 and preferably designed as an electromagnetic valve, allows for selective pressurization of the pressure port 336. The compressed air valve 338 can be controlled, preferably via a control unit 900 (not shown). The fluid valve 324 can also be controlled, preferably via a control unit 900 (not shown). By controlling the compressed air valve 338 and the fluid valve 334, a method according to the concept of the invention for cleaning the sensor surface 300 can be carried out automatically via a control unit 900. The fluid line 332 is connected to a fluid tank 316 (not shown).If no cleaning fluid M2 has been directed into the piston unit 322 by closing the fluid valve 324, a quantity of compressed air M1 is directed onto the sensor surface 300 via the nozzle 320 instead of the cleaning fluid M2 when the pressure port 336 is pressurized, particularly for carrying out an air cleaning step.

[0102] In preferred embodiments, the combination unit 328 and / or the piston unit 322 can be configured as a Venturi unit 323, in which the cleaning fluid quantity M2 is mixed with the compressed air quantity M1 or another compressed air quantity to form a cleaning mixture MG and is then directed as such via the common medium line 312 to the sensor surface 300. For this purpose, the fluid valve 324 and the compressed air valve 338 are opened simultaneously. Conversely, when the fluid valve 324 is closed and the compressed air valve 338 is open, only compressed air, in particular a compressed air quantity M1, is directed through the Venturi unit 323 and the common medium line 312 to the sensor surface 300.

[0103] Fig. 4A shows a further development of a cleaning device 318' for a cleaning system 100 according to the concept of the invention. In contrast to the one in Fig. 3 In the further development shown, the cleaning device 318' has, instead of a common medium line 312, a first medium line 312.1 for a compressed air quantity M1 and a second medium line 312.2 for a cleaning fluid quantity M2. The application module 326' accordingly has a first nozzle 320.1, which is fluid-carrying connected to the first medium line 312.1, and a second nozzle 320.2, which is fluid-carrying connected to the second medium line 312.2. The cleaning device 318' has, analogous to the one shown in Fig. 3 The further development shown comprises a piston unit 322'. The piston unit 322' has a fluid chamber 322A and an air chamber 322B, which are separated from each other by an axially movable pressure piston 327. The pressure piston 327 is further connected to the housing of the piston unit 322' via a return spring 325 located in the fluid chamber 322A. The second medium line 312.2 is connected to the fluid chamber 322A of the piston unit 322' via a fluid connection 337. The air chamber 322B can be pressurized with air via a pressure connection 336, whereby the volume of the air chamber 322B changes under axial movement of the pressure piston 327 in order to direct a quantity of cleaning fluid M2 located in the fluid chamber 322A under pressure and against the return spring 325 via the second nozzle 320.2 onto the sensor surface 300. The cleaning device 318' has a compressed air valve 338'. The second medium line 312.2 can have a fluid check valve 386 that opens in the flow direction from the piston unit 322' to the application module 326' and closes in the opposite direction.

[0104] When the compressed air supply via pressure port 336 is interrupted, the pressure piston 327 is pushed back into its initial position by the return spring 325, causing the piston unit 322' to draw in new cleaning fluid M2. The piston unit 322' can be filled via a fluid line 332. The compressed air valve 338' is controllable via a control unit 900 (not shown here) and serves two purposes: firstly, to supply the compressed air quantity M1 to the first nozzle 320.1 via the first medium line 312.1, and secondly, to supply the pressure port 336 of the piston unit 322' via a piston unit line 344, in order to direct the cleaning fluid quantity M2 via the second nozzle 320.2 onto the sensor surface 300. The compressed air valve 338' can in particular be designed as a 3 / 2-way solenoid valve, which optionally in a first position directs a quantity of compressed air M1 applied to a first compressed air valve connection 338.1 via a second compressed air valve connection 338.2 can be directed to the pressure port 336 of the piston unit 322', or in a second position, the second compressed air valve port 338.2 can be pneumatically connected to a third compressed air valve port 338.3 in order to direct the compressed air quantity M1, which is forced from the piston unit 322' by the return spring 325, via the first medium line 312.1 and the first nozzle 320.1 to the sensor surface. Due to the operation of the piston unit 322', a further development of the method can advantageously be implemented in which an identical quantity of compressed air quantity M1 and cleaning fluid quantity M2 is delivered per cleaning cycle, since the volume of cleaning fluid M2 displaced by the pressure piston 327 corresponds to the volume of compressed air M1 displaced by the return spring 325 during the reset process.In particular, in a further development with a piston unit 322', the compressed air quantity M1 and the cleaning fluid quantity M2 can be jointly determined via the compressed air quantity M1, in particular via a switching duration of the compressed air valve 338', in particular such that not both quantities M1, M2 correspond to the full volume of the piston unit 322', by switching the compressed air valve 338' before the cleaning fluid has been completely forced out of the piston unit 322'.

[0105] In the further development shown here, a fluid valve is not necessary, since selective pressurization of the pressure port 336 via the compressed air valve 338' is possible, and the medium lines 312.1, 312.2 are routed separately. The compressed air valve 338' is connected to a compressed air source 314 (not shown) to supply the cleaning device 318'. The fluid line 332 can, in particular, include a check valve 380, which opens in the direction of flow of the cleaning fluid M2 from a fluid tank 316 to the cleaning device 318' and closes in the opposite direction. Furthermore, the fluid line 332, in particular between the check valve 380 and the fluid tank 316, can have a 3 / 2-way valve by means of which, in a further valve position, air can optionally be directed through a vent line 384 through the fluid line 332 to the piston unit 322', in particular when an air cleaning step, i.e.This should take place without the application of the cleaning fluid M2. The piston unit 322' then delivers air in both directions.

[0106] In Fig. 4B is the in Fig. 4A The further development shown is schematically represented as a pneumatic circuit diagram; therefore, the above statements apply accordingly.

[0107] Fig. 5 Figure 1 shows a schematic representation of a vehicle 1000 – in this case in the form of an autonomous or semi-autonomous vehicle 1001 – having a cleaning system 100 for a sensor 301 designed as an optical sensor 302, namely as a camera 304. However, the cleaning system 100 can also be used in other vehicles, in particular conventional cars, trucks, trains, or motorcycles.

[0108] The cleaning system 100 includes a control unit 900, which is connected to a vehicle control unit 1010 via a vehicle control line 1020. The control unit 900 is connected to a cleaning device 318 via a control line 904, specifically for transmitting a compressed air control signal SM1 and a cleaning fluid control signal SM2. A compressed air source 314 and a fluid tank 316 are also connected to the cleaning device 318 via a medium line 312. Alternatively or additionally, the control unit 900 can also be directly connected to the compressed air source 314 via a further control line 340 for transmitting the compressed air control signal SM1. Alternatively or additionally, the control unit 900 can also be directly connected to the fluid tank 316 via a further control line 342 for transmitting the cleaning fluid control signal SM2.

[0109] The cleaning device 318 has a nozzle 320 to apply a quantity of compressed air M1 and / or a quantity of cleaning fluid M2 to a sensor surface 300 of the sensor 301 for cleaning purposes.

[0110] The fluid tank 316 can be used for other vehicle functions, for example to supply a windscreen cleaning system 920 or similar, or another cleaning system 220.

[0111] In optional advanced training courses, the control unit 900 can be connected to a rain sensor 330 via a signal transmission system.

[0112] The sensor 301 is connected to the control unit 900 via a sensor line 902, in particular for transmitting an air cleaning result LRE and / or a hybrid cleaning result HRE and / or an initial cleaning result IRE.

[0113] Fig. 6 Figure 1 shows a schematic progression of exemplary residual fluid quantities MR1, MR2 and cycle numbers ZZ, ZG over various time points T0 to T8 for two exemplary further developments of a process sequence. At an initial time point T0, a fluid tank 316 (not shown here) is completely full, resulting in a first residual fluid quantity MR1 at its maximum in the first further development of the process sequence. A first fluid cleaning step 414 then takes place, specifically within a step sequence 440, in which a first cleaning fluid quantity M2.1 is consumed, thereby reducing the first residual fluid quantity MR1 by the corresponding amount. In the first further development shown, the cleaning fluid quantity M2 is a constant cleaning fluid quantity M2K, meaning it remains constant regardless of the cycle number ZZ.During a cleaning process 400, which is not shown in detail here, a further fluid cleaning step 414 is performed at a first time point T1 and at a second time point T2, specifically due to a negative hybrid cleaning result HRE. In each step, a further constant quantity of cleaning fluid M2K is consumed, and the initial residual fluid quantity MR1 decreases accordingly. Simultaneously, the number of cycles ZZ is increased by 1 with each fluid cleaning step within a single execution of the process. At a third time point T3, the execution of the process is terminated, specifically due to a positive hybrid cleaning result HRE. As a result, the initial residual fluid quantity MR1 initially remains constant, and the number of cycles ZZ is reset to zero. The total number of cycles ZG, however, remains constant at the value 3.

[0114] After a time interval TI between two executions of the cleaning process, which in this example also corresponds to an average time interval TD between two executions of the cleaning process, the cleaning process is carried out again at a fourth time point T4. In this renewed execution of the cleaning process, the initial residual fluid quantity MR1 is reduced by the constant cleaning fluid quantity M2K in four fluid cleaning steps 414, and the number of cycles ZZ is again increased from 0 by 1 in each fluid cleaning step 414. At an eighth time point T8, the process is terminated because a maximum value ZM for the number of cycles ZZ has been reached. In this case, the maximum value ZM is 4. The total number of cycles ZG is then further increased by 4 to the value 7, starting from the value 3 reached in the previous execution.

[0115] In a second refinement of the process shown here, the profile of a second residual fluid quantity MR2 is depicted. Unlike the first refinement shown with the first residual fluid quantity MR1, in the second, alternative refinement of the process, the cleaning fluid quantity M2 is not constant, but depends on the number of cycles ZZ. At the initial time T0, a first cleaning fluid quantity M2.1 corresponds to a starting cleaning fluid quantity M2S, which in this case also corresponds to the constant cleaning fluid quantity M2K, although it can also deviate from it.

[0116] During the second execution of fluid cleaning step 414 at the first time point T1, the cycle count ZZ is already 1, which increases the cleaning fluid quantity to a second cleaning fluid quantity M 2.2. In this case, the second cleaning fluid quantity M2.2 is increased by the amount of the first cleaning fluid quantity 2.1, thus doubling it, which correspondingly reduces the second residual fluid quantity MR2 by twice the amount. Similarly, during a third execution of fluid cleaning step 414 at a second time point T2 – at which time the cycle count ZZ has again been increased by 1 to 2 – the cleaning fluid quantity M2 is increased – again by the amount of the first cleaning fluid quantity 2.1 – to a third cleaning fluid quantity M2.3. The second residual fluid quantity MR2 is correspondingly reduced by the amount of the third cleaning fluid quantity M2.3.

[0117] At the fourth time point T4, the process is repeated by increasing the cleaning fluid quantity M2 in four successive fluid cleaning steps 414, from an initial quantity M2.1 to a fourth quantity M2.4, depending on the number of cycles ZZ. Upon reaching the fourth quantity M2.4, a maximum cleaning fluid quantity M2M is reached, meaning that no further increase in the cleaning fluid quantity M2 occurs within this particular iteration of the process. This means that if further fluid cleaning steps 414 were to be performed after this fourth step 414, they would also be carried out with the fourth quantity M2.4. However, in this case, the maximum value ZM of the number of cycles ZZ has also been reached simultaneously, thus triggering a termination condition and ending the process.

[0118] Furthermore, in Fig. 6The graph shows, as an example, the profiles of two total compressed air volumes, namely a first total compressed air volume MDL1 and a second total compressed air volume MDL2, represented by dashed lines. The first profile, MDL1, represents a further development of the process with a constant compressed air volume M1K. Starting from the initial time T0, a first compressed air volume M1.1 is delivered as a constant compressed air volume M1K in each of three cleaning cycles. Specifically, the respective compressed air volume M1.1 is delivered to the sensor surface in each cleaning cycle after a corresponding cleaning fluid volume M2 has been applied. At the third time T3, no further compressed air is supplied, either due to a positive hybrid cleaning result HRE or because a maximum value ZM of the number of cycles ZZ has been reached.Subsequently, the initial total compressed air quantity MDL1, which corresponds in particular to the quantity of compressed air in a piston unit or in a compressed air reservoir of the compressed air source, is increased back to an initial level, in particular by filling the piston unit and / or operating a compressor of the compressed air source. In particular, unlike a residual fluid quantity MR1, MR2, the compressed air supply can be replenished during operation of the vehicle.

[0119] As a second example of increasing the compressed air volume depending on the number of cycles ZZ, the curve of the second total compressed air volume MDL2 is shown. In this curve – analogous to the curve of the residual fluid volume MR2 – the compressed air volume increases from a first compressed air volume M1.1 as the starting compressed air volume M1S at the initial time T0, via a second compressed air volume M1.2 at the first time T1, to a third compressed air volume M1.3 at the second time T2. At the third time T3, no further compressed air is supplied, and the total compressed air volume MDL2 is increased again to an initial level, in particular by filling the piston unit and / or operating a compressor. Reference symbol list (part of the description)

[0120] 100 Cleaning system 220 Further cleaning system 300 Sensor surface 301 Sensor 302 Optical sensor 304 Camera 310 Dirt, contamination 312 Medium line 312.1, 312.2 First, second medium line 314 Compressed air source 315 Cleaning fluid source 316 Fluid tank 318, 318' Cleaning device 320 Nozzle 320.1, 320.2 First, second nozzle 322, 322' Piston unit 323 Venturi unit 324 Fluid valve 325 Return spring 326 Application module 327 Pressure plunger 328 Combination unit 330 Rain sensor 332 Fluid line 334 Fluid valve 336 Pressure connection 337 Fluid connection 338, 338' Compressed air valve 338.1 to 338.3 First to third compressed air valve connection 340 Additional control line 342 Further control line 344, 344' Piston unit line 346 Level sensor 348 Sensor evaluation unit 349 Setpoint-actual comparison module 349.1 Brightness comparison module 349.2 Camera image comparison module 349.3 Contrast comparison module 350 Setpoint-actual comparison 360 Thermometer 361 External thermometer 362 Windscreen wiper control unit 364 Windscreen heater control unit 366 Rear window heater control unit 368 Anti-lock braking system (ABS) control unit 370 Electronic stability program (ESP) control unit 380 Check valve 382 3 / 2-way valve 384 Vent line 386 Fluid check valve 400 Procedure 402 Start step 410 Initial test step 412 Air cleaning step 413 Test step 414 Fluid, especially liquid,Cleaning step 416 further air cleaning step 417 further test step 418 counting step 420 fault step 422 emergency run step 424 abort step 430 hybrid cleaning step 440 step sequence 442 additional air cleaning sequence 444 additional air cleaning step 446 additional test step 448 additional counting step 900 control unit 902 sensor line 903 evaluation line 904 control line 906 system line 910 program memory 912 environment detection unit 920 windshield cleaning system 930 additional sensor 932 additional camera 940 reference memory 950 trigger switch 952 communication interface 954 vehicle bus 956 wireless communication device 1000 vehicle 1001 autonomous vehicle 1010 vehicle control 1020Vehicle control line , AB Termination condition AB1 First termination condition AB2 Second termination condition AB3 Additional termination condition I Initial cleaning result L Air cleaning result HR Hybrid cleaning result H Brightness value HW Brightness deviation HWD Average brightness value HWDV Average comparative brightness value M1 Compressed air quantity M1.1 to M1.3 First to fourth compressed air quantity M1K Constant compressed air quantity M1M Maximum compressed air quantity M1S Start compressed air quantity M1Z Additional compressed air quantity M2 Cleaning fluid quantity M2.1 to M2.4 First to fourth cleaning fluid quantity M2K Constant cleaning fluid quantity M2M Maximum cleaning fluid quantity M2S Start cleaning fluid quantity MDL Total compressed air quantity MDL1, MDL2 First, second total compressed air quantity MG Cleaning mixture MR residual fluid quantity MR1, MR2 first, second residual fluid quantity PX pixel RE cleaning result SC cleaning signal SI sensor signal SIK camera signal, camera image SIR reference sensor signal SIV comparison sensor signal SIKV comparison camera signalComparison camera image SM1 Compressed air control signal SM2 Cleaning fluid control signal SR Rain signal SSII Actual signal SSS Target signal SU Ambient signal T0 Initial time T1 to T8 First to eighth time TB Sub-area TB2 Further sub-area TD Average time interval between two executions of the cleaning process TI Time interval between two executions of the cleaning process TR Remaining operating time TW Waiting time UZ Time V1 to V7 First to seventh branch VTT Tank volume ZM Maximum value of the number of cycles ZG Total number of cycles ZZZ Number of cycles ZZM Additional maximum value ZZZ Additional number of cycles

Claims

1. Method (400) for operating a cleaning system (100) for cleaning a sensor surface (300) of a sensor (301) of a vehicle (1000), in particular an optical sensor (302), comprising the step of: - applying a compressed air quantity (M1) to the sensor surface (300) in an air cleaning step (412), - checking an air cleaning result (LRE) in a checking step (413), - in the case of a negative air cleaning result (LRE), performing a hybrid cleaning step (430) comprising: - applying a cleaning fluid quantity (M2) to the sensor surface (300) in a fluid cleaning step (414) and - applying a compressed air quantity (M1) to the sensor surface (300) in a further air cleaning step (416), - performed fluid cleaning steps (414) being recorded, and - a number (ZZ) of cycles of performed fluid cleaning steps (414) being recorded, which is increased after each fluid cleaning step (414), characterized in that the cleaning fluid quantity (M2) depends on the number (ZZ) of cycles such that a higher number (ZZ) of cycles results in a larger cleaning fluid quantity (M2), and the compressed air quantity (M1) depends on the number (ZZ) of cycles such that a higher number (ZZ) of cycles results in a larger compressed air quantity (M1).

2. Method (400) according to claim 1, characterized in that - a compressed air quantity (M1) is applied to the sensor surface (300) in the further air cleaning step (416) following the fluid cleaning step (414).

3. Method (400) according to claim 1, characterized in that - the cleaning fluid quantity (M2) is increased up to a maximum cleaning fluid quantity (M2M).

4. Method (400) according to any of claims 1 to 3, characterized in that the fluid cleaning step (414) is a liquid cleaning step (414).

5. Method (400) according to any of claims 1 to 4, characterized in that - the compressed air quantity (M1) is increased up to a maximum compressed air quantity (M1M).

6. Method (400) according to any of the preceding claims, characterized in that - a step sequence (440) comprising the hybrid cleaning step (430) further comprises, after the hybrid cleaning step (430), the step of: checking the hybrid cleaning result (HRE) in a further checking step (417), - the step sequence (440) being repeated until a termination condition (AB) is met.

7. Method (400) according to claim 6, characterized in that the termination condition (AB) is met if, as the first termination condition (AB1), the hybrid cleaning result (HRE) is positive or, as the second termination condition (AB2), the number (ZZ) of cycles has reached a maximum value (ZM).

8. Method (400) according to any of the preceding claims, characterized in that the checking step (413) for checking the air cleaning result (LRE) and / or the further checking step (417) for checking the hybrid cleaning result (HRE) is carried out via the sensor (301) and / or the evaluation device (348) thereof.

9. Method (400) according to any of the preceding claims, characterized in that - the checking step (413) or the further checking step (417) is carried out during the air cleaning step (412) or the further air cleaning step (416) or - within a waiting period (TW) after the air cleaning step (412) or the further air cleaning step (416).

10. Method (400) according to claim 9, characterized in that the waiting period (TW) is 500 ms.

11. Method (400) according to any of the preceding claims, characterized in that the method (400) is carried out in the case of a negative initial cleaning result (IRE) from an initial checking step (410).

12. Method (400) according to any of the preceding claims, characterized in that the method (400) is carried out in the case of a positive rain signal (SR) from a rain sensor (330).

13. Method (400) according to any of the preceding claims, characterized in that a remaining fluid quantity (MR) and / or a remaining operating time (TR) of the cleaning system (100) is determined, in particular being determined on the basis of a remaining number (ZR) of cycles or a total number (ZG) of cycles.

14. Method according to any of the preceding claims, characterized in that after checking the air cleaning result (LRE) in the checking step (413), in the case of a negative air cleaning result (LRE) before the hybrid cleaning step (430), an additional air cleaning process (442) is carried out and comprises the steps of: - applying an additional compressed air quantity (M1Z) to the sensor surface (300) in an additional air cleaning step (444), and - checking the air cleaning result (LRE) in an additional checking step (446).

15. Method (400) according to claim 14, characterized in that - the additional air cleaning process (442) is repeated until the air cleaning result (LRE) is positive or an additional termination condition (AB3) is met.

16. Method according to any of the preceding claims, characterized in that - the cleaning signal (SC) and / or the cleaning result (RE, LRE, HRE, IRE) is formed on the basis of a target-actual comparison (350) between an actual signal (SSI) and a target signal (SSS), in particular on the basis of a brightness deviation (HWA) and / or a contrast deviation (KA).

17. Method (400) according to claim 16, characterized in that - the actual signal (SSI) is formed by the sensor signal (SI), and - the target signal (SSS) is formed by a comparison sensor signal (SIV) provided by at least one further sensor (930), and / or by a reference sensor signal (SIR) provided by a reference memory (940).

18. Cleaning system (100) for cleaning a sensor surface (300) of a sensor (301), in particular an optical sensor (302), in a vehicle (1000), comprising a cleaning apparatus (318) and a control unit (900) designed to carry out a method (400) according to any of the preceding claims.

19. Cleaning system (100) according to claim 18, characterized by a common nozzle (320) for applying a compressed air quantity (M1) and a cleaning fluid quantity (M2) to the sensor surface (300).

20. Cleaning system (100) according to claim 18 or 19, characterized by a communication interface (952) designed to communicate with a vehicle bus (954) and / or a wireless communication device (956).

21. Cleaning system (100) according to any of claims 18 to 20, characterized by a sensor evaluation device (348), the sensor evaluation device (348) having a target-actual comparison module (349) and / or a brightness comparison module (349.1) and / or a camera image comparison module (349.2) and / or a contrast comparison module (349.3).

22. Vehicle (1000) comprising a cleaning system (100) according to any of claims 18 to 21.