Patent Publication Number: US-2023150455-A1

Title: Multi-channel cleaning apparatus, multi-channel sensor-cleaning module, and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of international patent application PCT/EP2021/068927, filed Jul. 8, 2021, designating the United States and claiming priority from German application 10 2020 119 476.5, filed Jul. 23, 2020, and the entire content of both applications is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to a multi-channel cleaning apparatus for providing a liquid cleaning pulse and/or a compressed-air cleaning pulse. The disclosure furthermore relates to a sensor cleaning module, to a vehicle, and to a method for operating a cleaning apparatus. 
     BACKGROUND 
     Cleaning apparatuses for vehicles, in particular for providing a liquid cleaning pulse and a compressed-air cleaning pulse, are generally known. 
     For example, EP 3 168 094 B1 describes a system for cleaning an external sensor surface installed on the vehicle, including an air nozzle that is configured to emit air onto a sensor surface; an air pump that has a fluid inlet, an air outlet, an air-fluid interface, and a variable volume compression chamber that communicates with the air outlet; with an air flow control device that communicates with the air nozzle and with the air outlet in order to control the air flow through same; and a liquid pump that communicates with the fluid inlet in order to deliver a flow of pressurized liquid, such that the volume of the compression chamber changes, in order to generate a volume of compressed air with an absolute pressure of lower than 10 bar. 
     Such approaches are however in need of improvement, in particular as regards the provision of a supply to multiple cleaning nozzles, in particular for cleaning multiple sensor surfaces. 
     Cleaning apparatuses are also in need of improvement with regard to the individual controllability of the cleaning pulses, and in particular an application of compressed air to a sensor surface independently of a liquid cleaning pulse. 
     It is therefore desirable to improve the function and the construction of the cleaning apparatus, in particular to make it possible for a supply to be provided to multiple cleaning nozzles with relatively little expenditure on equipment, and to allow improved controllability, in particular controllability of cleaning pulses and/or compressed-air flows. 
     SUMMARY 
     The disclosure addresses this, and it is an object of the disclosure to specify an improved cleaning apparatus, in the case of which, in particular, the provision of a supply to multiple cleaning nozzles, and/or the possibility of controlling individual cleaning pulses, is improved. 
     The object relating to the cleaning apparatus is achieved by the disclosure, in a first aspect, by a multi-channel cleaning apparatus. 
     The disclosure proceeds from a multi-channel cleaning apparatus for a vehicle for providing a liquid cleaning pulse and/or a compressed-air cleaning pulse, for at least two cleaning nozzles, including: 
     a module compressed-air port for admitting compressed air, and a module liquid port for admitting cleaning liquid. 
     According to an embodiment of the disclosure, in the multi-channel cleaning apparatus, at least two nozzle branches are provided, wherein a nozzle branch is configured to provide a supply to at least one cleaning nozzle independently of another nozzle branch, wherein each nozzle branch includes: 
     a pressure cylinder with a cylinder volume, including a movable separating means that divides the cylinder volume in fluid-tight fashion into an air chamber, which accommodates compressed air, and a liquid chamber, which accommodates cleaning liquid, wherein 
     the air chamber has an air chamber port to which compressed air can be applied for the purposes of filling the air chamber, wherein, in the event of filling of the air chamber, movement of the separating means counter to a restoring force and enlargement of the air chamber result in a reduction in size of the liquid chamber, whereby cleaning liquid is provided in the form of the liquid cleaning pulse at a liquid nozzle line via a liquid chamber port of the liquid chamber, and 
     a switching valve that is configured to produce a pneumatic connection between the module compressed-air port and the air chamber port in an air admission position, and 
     a bypass valve that is configured to produce a pneumatic connection between the module pressure port and the compressed-air nozzle line, bypassing the switching valve, in an open position in order to provide a bypass compressed-air flow. 
     The disclosure is based on the consideration that a supply of cleaning media, in particular cleaning liquid and compressed air, to multiple cleaning nozzles is generally advantageous in order to reliably clean a number of sensors that is constantly increasing with the progression of technological development. Here, as central a supply as possible, in particular in a multi-channel cleaning apparatus, is particularly advantageous because—by contrast to a multiplicity of individual cleaning apparatuses—the installation effort, weight, installation space and costs can be advantageously reduced. However, individual controllability of individual cleaning nozzles or individual groups of cleaning nozzles should advantageously be possible here. Via a central multi-channel cleaning apparatus with an in particular small number of defined ports and interfaces, in particular one module compressed-air port, one module liquid port, one module control connection and a number of liquid nozzle ports and compressed-air nozzle ports, an integration of the multi-channel cleaning apparatus can be advantageously simplified and improved. 
     In accordance with the cleaning nozzles to which a supply is to be provided in a mutually independent manner, a corresponding number of nozzle branches may be implemented in the multi-channel cleaning apparatus. Through the use of pressure cylinders for generating both the compressed-air cleaning pulse and the liquid cleaning pulse, it is advantageously possible for both cleaning media, that is, compressed air and cleaning liquid, to be provided in pressurized form, that is, in the form of cleaning pulses, to a cleaning nozzle via only one pressure source, in particular a compressor or a pressure accumulator. It is thus advantageously possible to omit a further pressure source, in particular a liquid pump, whereby the expenditure on equipment is advantageously reduced further. 
     The provision of a bypass valve in a nozzle branch advantageously makes it possible here to generate a bypass compressed-air flow independently of the pressure cylinder, whereby a compressed-air flow for cleaning a sensor surface can be provided. This makes effective cleaning of the sensor surface possible in an advantageously liquid-saving manner, in particular in rainy conditions or in the case of dry cleaning for the purposes of blowing the sensor surface clear of particles. 
     The cleaning liquid may in particular be water or a mixture of water with cleaning agent and/or antifreeze. 
     In particular, the switching valve is configured to produce a pneumatic connection between the air chamber port and a compressed-air nozzle line, for the purposes of providing the compressed-air cleaning pulse by return movement of the separating means under the action of the restoring force, in a venting position. 
     In a preferred embodiment, provision is made for the separating means to be a cylinder plunger which is movable axially along a cylinder axis of the pressure cylinder and which bears sealingly against a cylinder inner wall of the pressure cylinder, wherein the cylinder plunger is of cylindrical form and has a plunger height and is held in the pressure cylinder via a restoring spring, which has a spring constant, for generating the restoring force. 
     Through the selection or the setting of a spring constant of the restoring spring of a pressure cylinder, it is possible to influence the restoring force and thus advantageously a pulse pressure with which, in particular, a compressed-air cleaning pulse of the pressure cylinder is provided. Here, the pulse pressure is determined from a plunger area of the cylinder plunger multiplied by the restoring force. Here, the spring constant of the restoring spring should be selected so as to yield a pulse pressure that is lower than an application pressure applied to the pressure cylinder at the air chamber port, in order that the restoring spring can be compressed. The spring constant should preferably be selected such that an application force—which is determined from the application pressure applied to the air chamber port of the pressure cylinder multiplied by the plunger area of the cylinder plunger—is sufficient to move the cylinder plunger counter to the force of the restoring spring. The application force is thus preferably higher than the restoring force of the spring. Correspondingly, in this case, the pressure of the resulting compressed-air cleaning pulse is lower than the application pressure. The higher the application pressure, and correspondingly the application force, the higher the pressure of the resulting liquid cleaning pulse. The spring constant may advantageously be selected in a manner dependent on the application pressure, for example such that the application force is twice the restoring force. 
     In an embodiment, provision is made for several, in particular all, pressure cylinders of the multi-channel cleaning apparatus to be arranged in one pressure cylinder block, in particular as structurally identical pressure cylinder modules. In particular, the pressure cylinder modules are, in each case at their module side, arranged adjacent to one another, in particular screwed together, to form a pressure cylinder block. In preferred embodiments, a pressure cylinder block with a number of pressure cylinder modules may also be milled from one piece, printed, or cast. Other suitable manufacturing methods are in particular primary forming, deforming, cutting, joining, additive or similar manufacturing methods. In the case of detachable assembly, in particular by screw connection, it is advantageously possible for the number of pressure cylinder modules to be individually adapted to a specific usage situation. 
     In an embodiment, provision is made for a cylinder plunger of the pressure cylinder of one nozzle branch to have a plunger height that differs from a plunger height of a cylinder plunger of the pressure cylinder of another nozzle branch. Through the selection or the setting of a plunger height of a cylinder plunger, it is advantageously possible to adapt an effective delivery volume, in particular in a structurally identical pressure cylinder and/or pressure cylinder module. In this way, it is possible to set an individual effective delivery volume, in particular for individual nozzle branches. For example, for a nozzle branch that provides a supply to a cleaning nozzle for a sensor surface which is relatively large or for which relatively intense fouling is to be expected, a relatively large effective delivery volume can be set by way of a small plunger height. 
     In an embodiment, provision is made for the bypass valve to be configured as a 2/2 directional valve, in particular 2/2 directional solenoid valve and/or cartridge valve. The 2/2 directional valve is preferably configured as a normally-closed 2/2 directional valve. “Normally-closed valve” means that the valve, in particular the 2/2 directional valve, is situated in its closed position when in the non-activated, in particular electrically deenergized state. 
     In an embodiment, provision is made for the bypass valve to be configured as an in particular normally-open 3/2 directional valve, wherein the 3/2 directional valve is configured to produce a pneumatic connection between the module compressed-air port and the compressed-air nozzle line in an open position, and to produce a pneumatic connection between the compressed-air nozzle line and an exhaust port of the 3/2 directional valve in a closed position. Such a refinement with a bypass valve configured as a 3/2 directional valve advantageously allows the connection of a quick exhaust valve, in particular for the purposes of generating compressed-air pulses. 
     In an embodiment, provision is made for the bypass valve to be formed as an arrangement composed of an in particular normally-open 3/2 directional valve and a quick exhaust valve, wherein the 3/2 directional valve is configured to produce a pneumatic connection between the module compressed-air port and the quick exhaust valve in an open position, and to produce a pneumatic connection between the quick exhaust valve and an exhaust port of the 3/2 directional valve in a closed position, the quick exhaust valve is arranged between the bypass valve and the compressed-air nozzle line or in a compressed-air nozzle connection line that pneumatically connects the cleaning nozzle to the compressed-air nozzle line, and the quick exhaust valve is configured to admit the bypass compressed-air flow and to provide a bypass compressed-air cleaning pulse. Via the arrangement composed of a 3/2 directional valve and a quick exhaust valve, a bypass compressed-air cleaning pulse can advantageously be generated in a nozzle branch—independently of the pressure cylinder in the nozzle branch. In relation to a bypass compressed-air flow, it is possible via the quick exhaust valve for a bypass compressed-air cleaning pulse to be generated that has a relatively high pressure and/or a relatively high velocity, for improved cleaning performance. The bypass compressed-air cleaning pulse, in particular the volume thereof, can be set via a corresponding structural configuration of a compressed-air buffer of the quick exhaust valve. 
     In an embodiment in which the bypass valve is formed as an arrangement composed of a 3/2 directional valve and a quick exhaust valve, the 3/2 directional valve is preferably formed as a normally-open valve. “Normally-open valve” means that the valve, in this case the 3/2 directional valve, is situated in its open position when in the non-activated, in particular electrically deenergized state, and is switched into its closed position—which vents the quick exhaust valve at its second port for the purposes of releasing the bypass compressed-air cleaning pulse—only when a bypass compressed-air cleaning pulse is to be provided. In particular, the quick exhaust valve is arranged between the bypass valve and the cleaning nozzle. 
     This has the advantage that the 3/2 directional valve is situated in its open position when in the non-activated state, and is switched into its closed position—which vents the quick exhaust valve at the second port for the purposes of releasing the bypass compressed-air cleaning pulse—only when a bypass compressed-air cleaning pulse is to be provided. 
     In an embodiment, provision is made for the bypass valve to be configured as an in particular normally-closed 3/2 directional valve, wherein the 3/2 directional valve is configured to produce a pneumatic connection between the module compressed-air port and the compressed-air nozzle line in an open position, and to produce a pneumatic connection between the quick exhaust valve and an exhaust port of the 3/2 directional valve in a closed position. In the closed position, the exhaust port may be blocked or open. In such a refinement, a 3/2 directional valve, which is in particular formed as a standard pneumatic component, for example as a cartridge valve, can be effectively utilized with the function of a 2/2 directional valve. By contrast to a refinement in which the bypass valve is formed from an arrangement composed of a 3/2 directional valve and a quick exhaust valve, the 3/2 directional valve in this refinement is preferably formed as a normally-closed valve which is activated, and thus switched into its open position, for the purposes of providing a bypass compressed-air flow. In such refinements, it is possible for an approximately structurally identical switching valve to be used both for embodiments with a quick exhaust valve and for embodiments without a quick exhaust valve, wherein, in the second case, the switching valve merely needs to be adapted by blocking of the exhaust port (and optionally by modification from normally-open to normally-closed). 
     In an embodiment, provision is made for at least two pressure cylinders to be assigned to one nozzle branch in such a way that the air chamber ports of the at least two pressure cylinders are pneumatically connected to a single switching valve. In such a refinement, the effective delivery volume of a nozzle branch can advantageously be enlarged, in particular multiplied, by joint switching of several pressure cylinders of a nozzle branch via a single switching valve. In particular, such a nozzle branch with at least two pressure cylinders may be assigned to one cleaning nozzle, or to a number of cleaning nozzles assigned to one sensor surface. In this way, the expenditure on equipment for providing a supply to one or more cleaning nozzles for cleaning relatively large sensor surfaces, for example a surface of a LIDAR or RADAR sensor, can be advantageously reduced, in particular through the omission of one or more switching valves. 
     In an embodiment, at least four nozzle branches and/or four pressure cylinders are provided. Such a refinement represents a suitable number of nozzle branches and/or pressure cylinders for a vehicle, in particular for a passenger motor vehicle. Nevertheless, different numbers of nozzle branches and/or pressure cylinders, for example two or eight, are possible within the scope of the disclosure. 
     In an embodiment, a module control connection is provided. A module control connection advantageously allows a central connection of all control lines, in particular for the switching valves and/or bypass valves of the multi-channel cleaning apparatus. The module control connection is in particular formed as a standardized plug and/or plug connection. 
     In an embodiment, a module control unit is provided which is configured for communication between the multi-channel cleaning apparatus, in particular the module control connection of the multi-channel cleaning apparatus, and a vehicle control unit of the vehicle, in particular via a vehicle bus. In particular, the module control unit is configured to convert control signals  1022  that are transmitted via the vehicle bus  1026  into switching signals for switching valves and/or bypass valves, and vice versa. 
     In a second aspect, the disclosure specifies a multi-channel sensor cleaning module, including a module housing, in particular a valve cartridge housing, and a multi-channel cleaning apparatus according to the first aspect of the disclosure. The advantages of the multi-channel cleaning apparatus are utilized to corresponding advantage in the multi-channel sensor cleaning module. In particular, the integration of the multi-channel cleaning apparatus in the form of a self-contained multi-channel sensor cleaning module with defined interfaces and/or ports allows improved integration into a vehicle, in particular with relatively little installation effort. Also, a multi-channel sensor cleaning module of the type allows improved retrofitting in existing vehicles. A valve cartridge housing is in particular formed as a block from aluminum or plastic or similar suitable material, into which block a number of valve inserts is introduced by suitable processing methods, with corresponding bores or similar air-conducting and/or fluid-conducting lines between the valve inserts and/or external ports. 
     In a third aspect, the disclosure specifies a vehicle, in particular passenger motor vehicle or utility vehicle or trailer, including at least one multi-channel cleaning apparatus according to the first aspect of the disclosure and/or a sensor cleaning module according to the second aspect of the disclosure. The advantages of the multi-channel cleaning apparatus according to the first aspect of the disclosure and/or a sensor cleaning module according to the second aspect of the disclosure can be advantageously utilized in a vehicle according to the third aspect of the disclosure. In particular, reliable cleaning of sensor surfaces of the sensors of the vehicle via an improved multi-channel cleaning apparatus according to the concept of the disclosure allows more reliable functioning of driver assistance functions, autonomous driving functions and/or partially autonomous driving functions of the vehicle that are based on the sensors. The trailer may in particular be configured as a utility vehicle trailer or passenger motor vehicle trailer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will now be described with reference to the drawings wherein: 
         FIG.  1    is a schematic of a preferred nozzle branch of a multi-channel cleaning apparatus according to the disclosure; 
         FIG.  2    is a schematic of a further preferred nozzle branch of a multi-channel cleaning apparatus according to the disclosure; 
         FIG.  3    shows a preferred embodiment of a multi-channel cleaning apparatus according to the disclosure; 
         FIG.  4 A  shows a single pressure cylinder in the form of a pressure cylinder module in a lateral cross-sectional view; 
         FIG.  4 B  shows a schematic plan view of four pressure cylinder modules for forming a pressure cylinder block; and, 
         FIG.  5    is a schematic of a vehicle, in particular of a passenger motor vehicle or utility vehicle, including a multi-channel cleaning apparatus according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a nozzle branch  520  of a multi-channel cleaning apparatus  100  according to the disclosure. The nozzle branch  520  is configured to provide compressed air DL in the form of a compressed-air cleaning pulse DRI at a nozzle compressed-air port  104  and to provide cleaning liquid F in the form of a liquid cleaning pulse FRI at a nozzle liquid port  102 . The nozzle branch  520  is pneumatically connected to a module compressed-air port  272  of the multi-channel cleaning apparatus  100 , wherein the module compressed-air port  272  is configured to admit compressed air DL from a compressed-air source  600 , in particular a compressor  602  and/or a pressure accumulator  604  of a compressed-air supply system  606 . The module compressed-air port  272  is pneumatically connected via a compressed-air connection line  273  to a first port  2700 . 1  of a switching valve  2700 . The switching valve  2700  is in the present case configured as a 3/2 directional solenoid valve. 
     The nozzle branch  520  is connected in fluid-conducting fashion to a module liquid port  618  of the multi-channel cleaning apparatus  100 . The module liquid port  618  is configured to admit cleaning liquid F from a liquid source  400 . The liquid source  400  may in particular be in the form of a tank that holds cleaning liquid F. 
     The nozzle branch  520  furthermore has a pressure cylinder  220  with a separating means  226  which is configured as a cylinder plunger  227  and which is movable axially along a cylinder axis AZ and which variably divides a cylinder volume VZ of the pressure cylinder  220  into an air chamber  222  and a liquid chamber  224 . The pressure cylinder  220  has, in the region of the air chamber  222 , an air chamber port  223  via which compressed air DL can be applied to the air chamber  222  in order to fill the air chamber  222 . Pressurization of the air chamber port  223  causes an expansion of an air chamber volume VL of the air chamber  222 , with the separating means  226  being moved counter to a restoring force FR, with a liquid chamber volume VF of the liquid chamber  224  simultaneously decreasing in size. In the present case, the separating means  226  in the form of the cylinder plunger  227  is held in the pressure cylinder  220  by a restoring spring  228 , whereby the restoring spring  228  generates the restoring force FR when the cylinder plunger  227  is deflected. The air chamber port  223  is pneumatically connected via an air chamber line  230  to a second outlet  2700 . 2  of the switching valve  2700 . 
     In the region of the liquid chamber  224 , the pressure cylinder  220  has a liquid chamber port  225  via which the liquid chamber  224  is connected in fluid-conducting fashion to the liquid nozzle line  626 . The liquid chamber port  225  is connected in fluid-conducting fashion at a cylinder connection point  619  to the liquid nozzle line  626 . Application of compressed air DL to the air chamber port  223 , and a movement of the separating means  226  counter to the restoring force FR, cause a quantity of cleaning liquid F that is held in the liquid chamber  224  to be provided, via the liquid chamber port  225  and via the cylinder connection point  619  and the liquid nozzle line  626 , in the form of a liquid cleaning pulse FRI at the nozzle liquid port  102  for at least one cleaning nozzle  320 . This occurs by virtue of the liquid chamber volume VF of the liquid chamber  224  being decreased in size as a result of the movement of the separating means  226 , and the cleaning liquid F thus being forced out of the pressure cylinder  220 , in particular in the form of a pulse. 
     The nozzle compressed-air port  104  is pneumatically connected via the compressed-air nozzle line  278  to a third port  2700 . 3  of the switching valve  2700 . 
     An induction pressure check valve  350  is arranged in the liquid nozzle line  626  between the cylinder connection point  619  and the nozzle liquid port  102 . 
     A liquid pulse check valve  352  is arranged in the liquid nozzle line  626  between the cylinder connection point  619  and the module liquid port  618 . The liquid pulse check valve  352  prevents cleaning liquid F from escaping in the direction of the module liquid port  618  during the provision of the liquid cleaning pulse FRI. 
     In an air admission position  2700 A of the switching valve  270 , the first port  2700 . 1  is pneumatically connected to the second port  2700 . 2 , and the third port  2700 . 3  is blocked. In this air admission position  2700 A, an air pressure prevailing at the module compressed-air port  272  is thus transmitted onward to the air chamber port  223 , which results in an expansion of the air chamber  222  and the provision of a liquid cleaning pulse FRI at the nozzle liquid port  102 . The liquid cleaning pulse FRI is consequently applied via the cleaning nozzle  320  to a sensor surface  300 . 
     In a venting position  2700 B of the switching valve  2700 , as illustrated here, the second port  2700 . 2  is pneumatically connected to the third port  2700 . 3 , and the first port  2700 . 1  is blocked. This venting position  2700 B results in venting of the air chamber port  223 , whereby the separating means  226  performs a return movement under the action of the restoring force FR, and the air chamber volume VL of the air chamber  222  decreases in size, and the liquid chamber volume VF of the liquid chamber  224  increases in size. The return movement of the separating means  226  gives rise to a negative pressure at the liquid chamber port  225 . Owing to the induction pressure check valve  350 , the negative pressure acts only at the module liquid port  618  (and not at the nozzle liquid port  102 ), whereby new cleaning liquid F is inducted into the liquid chamber  224  from the liquid source  400 , in particular without a pump or similar delivery device being required. 
     At the same time, the return movement of the separating means  226  gives rise to a positive pressure at the air chamber port  223 , which positive pressure results in a flow of compressed air DL via the second port  2700 . 2  and the third port  2700 . 3  to the nozzle compressed-air port  104 , whereby a compressed-air cleaning pulse DRI is provided at the nozzle compressed-air port  104 . Consequently, the compressed-air cleaning pulse DRI is applied to the sensor surface  300  via the cleaning nozzle  320  for cleaning purposes. The switching valve  270  has, in particular, a relatively large nominal width in order to advantageously transmit the cleaning compressed-air pulse to the compressed-air nozzle line  278  without pressure loss. In particular, the switching valve has a nominal width that is greater than or equal to the diameter of the compressed-air nozzle line  278  and/or of the air chamber line  230 . 
     A cleaning process operation is thus complete, and may be repeated as required by virtue of the switching valve  2700  being switched back into the air admission position  2700 A. 
     The nozzle branch  520  furthermore has a bypass valve  3300  and a compressed-air pulse check valve  354 . The bypass valve  3300  is in the present case in the form of a 2/2 directional valve  3320 , specifically a 2/2 directional solenoid valve  3330 . The 2/2 directional valve  3320  is pneumatically connected via a first port  3320 . 1  to the compressed-air connection line  273  and via a second port  3320 . 2  and a bypass line  623  to a bypass connection point  621  of the compressed-air nozzle line  278 . 
     The compressed-air pulse check valve  354  is arranged in the compressed-air nozzle line  278  between the third port  2700 . 3  of the switching valve  2700  and the bypass connection point  621 . 
     In a closed position  3320 A of the 2/2 directional valve  3320  or of the bypass valve  3300 , the first port  2320 . 1  is pneumatically separated from the second port  2320 . 2 . In this closed position  2320 A, the functioning of the multi-channel cleaning apparatus  100  means of the pressure cylinder  220  is as described above. However, by virtue of the bypass valve  3300  being switched, compressed air DL can be supplied to the nozzle compressed-air port  104  directly from the module compressed-air port  272 , bypassing the switching valve  2700 . In the present case, this occurs by virtue of the bypass valve  3300  in the form of the 2/2 directional valve  3320  being switched into an open position  3320 B, in which the first port  3320 . 1  is pneumatically connected to the second port  3320 . 2 . In this way, the compressed air DL that is present at the module compressed-air port  272  can be transmitted directly via the bypass connection point  621  and the compressed-air nozzle line  278  in order to provide a bypass compressed-air flow BDS at the nozzle compressed-air port  104 . The bypass valve  3300  thus advantageously makes it possible for compressed air DL, in particular a bypass compressed-air flow BDS, to be applied to the sensor surface  300  without the pressure cylinder  220  being actuated. 
     The compressed-air pulse check valve  354  ensures that—when the 2/2 directional valve  3320  is in the open position  3320 B and the switching valve is in the venting position  2700 B— the compressed air DL cannot flow in the direction of the switching valve  2700  and thus into the air chamber  222  of the pressure cylinder  220 . 
     The 2/2 directional valve  3320  may optionally have, at the first port  3320 . 1 , a control line  3320 . 3  for providing a control pressure PST. 
     The multi-channel cleaning apparatus  100  may furthermore have a nozzle connection line  108  that is configured to connect one or more cleaning nozzles  320  in air-conducting and/or fluid-conducting fashion to the multi-channel cleaning apparatus  100 . The nozzle connection line  108  may be configured as a common line that is configured to conduct both compressed air and cleaning liquid simultaneously and/or successively. In other preferred embodiments, the nozzle connection line  108  may have a liquid nozzle connection line  108 . 1  and a compressed-air nozzle connection line  108 . 2  and thus be configured for conducting the media separately to the cleaning nozzle  320 . 
       FIG.  2    shows a further preferred nozzle branch  520 ′ for a multi-channel cleaning apparatus  100 ′ according to the concept of the disclosure, which, by contrast to the nozzle branch  520  shown in  FIG.  1   , has, as a bypass valve  3300 , an arrangement composed of a 3/2 directional valve  3340  and additionally a quick exhaust valve  3400 . The quick exhaust valve  3400  is arranged in the bypass line  623 . Via the quick exhaust valve  3400 , it is advantageously possible for a pulse-like bypass compressed-air cleaning pulse BDRI to be generated and provided at the nozzle compressed-air port  104  on the basis of the bypass compressed-air flow BDS, which in particular takes the form of a continuous flow. 
     The quick exhaust valve  3400  has a first port  3400 . 1  that pneumatically connects the quick exhaust valve  3400  to the second port  334 . 2  of the 3/2 directional valve  3340 . The quick exhaust valve  3400  has a second port  3400 . 2  that pneumatically connects the quick exhaust valve  3400  to the bypass connection point  621 . The quick exhaust valve  3400  furthermore has a third port  3400 . 3 , to which a compressed-air buffer  341  of the quick exhaust valve  3400  is pneumatically connected. The quick exhaust valve  3400  is formed in the manner of a selector valve with a valve element  3400 . 4 , which valve element blocks that one of the first port  3400 . 1  and the second port  3400 . 2  at which the lower air pressure prevails, and which valve element pneumatically connects the respective other port to the third port  3400 . 3 . 
     Furthermore, in the bypass line  623  between the second port  3340 . 2  of the 3/2 directional valve  3340  and the bypass connection point  621 , there is arranged a bypass check valve  356  which opens in a flow direction from the 3/2 directional valve  334  to the bypass connection point  621  and which blocks in the opposite direction. In an open position  3340 B of the 3/2 directional valve  3340 — analogously to the open position  3320 B of the 2/2 directional valve  3320  shown in  FIG.  2   —a first port  3340 . 1 , leading to the compressed-air connection line  273 , of the 3/2 directional valve  3340  is pneumatically connected to the second port  3340 . 2 . This has the result that compressed air DL prevailing at the module compressed-air port  272  is transmitted in the form of the bypass compressed-air flow BDS to the first port  3400 . 1  of the quick exhaust valve  3400 , whereby the valve element  3400 . 4  is forced against the second port  3400 . 2  with blocking action, and the compressed-air buffer  341  is filled with compressed air DL via the third port  3400 . 3 . If the 3/2 directional valve  3340  is now switched into a closed position  3340 A, the second port  3340 . 2  is pneumatically connected to a third exhaust port  3340 . 3 , which particular vents into the surroundings, and the first port  3340 . 1  is blocked. As a result, the air pressure at the first port  3400 . 1  of the quick exhaust valve falls to ambient pressure, and the valve element  3400 . 4  is, in particular through a quick exhaust valve control line  3400 . 5 , forced against the first port  3400 . 1  with blocking action by the pressure of the compressed air DL that is stored in the compressed-air buffer  341 . The second port  3400 . 2  is consequently opened, whereby the compressed air DL that is stored in the compressed-air buffer  341  can be provided in the form of the bypass compressed-air cleaning pulse BDRI, via the second port  3400 . 2  and also the bypass connection point  621  and the compressed-air nozzle line  278 , at the nozzle compressed-air port  104 . Here, the compressed-air pulse check valve  354  prevents a flow of the bypass compressed-air cleaning pulse BDRI in the direction of the switching valve  2700 . 
     By virtue of the 3/2 directional valve  3340  being switched back into the open position  3340 B, the compressed-air buffer  341  can be filled with compressed air DL again, and the process for generating the bypass compressed-air cleaning pulse BDRI can be repeated—as required and in particular as often as desired and independently of the pressure cylinder  220 . 
     Independently of the generation of a bypass compressed-air flow BDS and/or of a bypass compressed-air cleaning pulse BDRI, a compressed-air cleaning pulse DRI and/or a liquid cleaning pulse FRI can be generated in a known manner via the pressure cylinder  220  and the switching valve  2700 — as described in conjunction with  FIG.  1   . 
     In the case of the nozzle branch  520 ′ shown in  FIG.  2   , the bypass check valve  356  prevents a compressed-air cleaning pulse DRI, which is generated by the pressure cylinder  220  and which is conducted via the switching valve  2700  in its venting position  2700 B to the compressed-air nozzle line  278 , from being able to pass to the quick exhaust valve  3400 . 
     The 3/2 directional valve  3340  may optionally have, at the first port  3340 . 1 , a control line  3340 . 4  for providing a control pressure PST. 
     The 3/2 directional valve  3340  is in particular configured as a normally-open valve, that is, the 3/2 directional valve  3340  is situated in the open position  3340 B when in a non-activated, in particular electrically deenergized state, and switches into the closed position  3340 A when in an activated, in particular electrically energized state. In this way, the 3/2 directional valve  3340  only needs to be activated, in particular electrically energized, in order to emit the bypass compressed-air cleaning pulse BDRI. 
     In general, with regard to the least possible pressure losses and thus the strongest possible bypass compressed-air cleaning pulse BDRI, it is advantageous to keep the line length between the quick exhaust valve  340  and the cleaning nozzle  320  as short as possible. In alternative preferred embodiments, instead of the quick exhaust valve  340  shown, it is possible for an alternative further quick exhaust valve  340 ′ (illustrated in highly simplified form here) to be arranged closer to the cleaning nozzle  320 , for example between the compressed-air nozzle port  104  and the cleaning nozzle  320 , in the compressed-air nozzle line  108 . 2 , or alternatively as a yet further quick exhaust valve  340 ″ in the compressed-air nozzle line  278 . The cleaning nozzle  320 , the nozzle connection line  108  and the quick exhaust valve  340  may in this case be formed in particular as part of the multi-channel cleaning apparatus  100 . 
     In embodiments—in particular with an alternative further quick exhaust valve  340 ′ or an alternative yet further quick exhaust valve  340 ″, but also in embodiments without quick exhaust valves—it is advantageously possible for the third port  2700 . 3  of the switching valve  2700  not to be connected to the compressed-air nozzle line  278 , but rather to be configured to vent directly into the surroundings in the venting position  2700 B. In such embodiments, it is thus possible for the compressed-air pulse check valve  354  and/or the bypass check valve  356  and/or the line between the third port  2700 . 3  of the switching valve  2700  and the bypass connection point  621  to be omitted. Thus, in such embodiments, no compressed-air cleaning pulse DRI generated by the pressure cylinder  220  is provided at the compressed-air nozzle line  278 , but a structural simplification of the multi-channel cleaning apparatus  100  is advantageously achieved, in particular through the omission of the check valve  354 ,  356 . The bypass line  623  and the compressed-air nozzle line  278  directly coincide in this embodiment, and are configured to conduct the bypass compressed-air flow BDS and/or a bypass compressed-air cleaning pulse BDRI from the bypass valve  330  to the compressed-air nozzle port  104 . 
       FIG.  3    shows a multi-channel cleaning apparatus  100  according to the concept of the disclosure with four nozzle branches  520 , specifically a first nozzle branch  520 . 1 , a second nozzle branch  520 . 2 , a third nozzle branch  520 . 3  and a fourth nozzle branch  520 . 4 . Here, each nozzle branch  520  has a switching valve  2700 , a pressure cylinder  220  and a bypass valve  3300 , which are each numbered in accordance with their associated nozzle branch. The four pressure cylinders  220 . 1 ,  220 . 2 ,  220 . 3 ,  220 . 4  are each configured as a pressure cylinder module  532 . 1 ,  532 . 2 ,  532 . 3 ,  532 . 4  and are assembled together, in particular screwed to one another, to form a pressure cylinder block  530 . The pressure cylinder module  532  and/or the pressure cylinder block  530  are in particular formed from a suitable material, in particular from a plastic that exhibits adequate strength or from aluminum. 
     In the present case, each pressure cylinder  220 . 1 ,  220 . 2 ,  220 . 3 ,  220 . 4  has, as shown here by way of example only at the first pressure cylinder  220 . 1 , a first part  225 . 1 A, which leads to the module liquid port  618 , of the liquid chamber port  225 . 1 , and a second part  225 . 18 , which leads to the liquid nozzle line  626 . 1 , of the first liquid chamber port  225 . 1 . 
     In all embodiments, it is alternatively possible for a single liquid chamber port  225 . 1 ,  225 . 2 ,  225 . 3 ,  225 . 4  to be provided at each pressure cylinder  220 , which liquid chamber port is—as shown in  FIG.  1    and  FIG.  2   —connected via a cylinder connection point  619 ,  619 . 1 ,  619 . 2 ,  619 . 3 ,  619 . 4  (schematically indicated here) to the liquid nozzle line  626 . Via a cylinder connection point  619 , a pressure cylinder  220  can be connected in a structurally advantageously simplified manner, via only a single fluid-conducting connection, to the respective liquid nozzle line  626 . 
     Each nozzle branch  520  has both a nozzle liquid port  102  and a nozzle compressed-air port  104 , that is, the first nozzle branch  520 . 1  has a first nozzle liquid port  102 . 1  for providing a first compressed-air cleaning pulse DRI 1  and has a first nozzle compressed-air port  104 . 1  for providing a first liquid cleaning pulse FRI 1 , the second nozzle branch  520 . 2  has a second nozzle liquid port  102 . 2  for providing a second liquid cleaning pulse FRI 2  and has a second nozzle compressed-air port  104 . 2  for providing a second compressed-air cleaning pulse DRI 2 , the third nozzle branch  520 . 3  has a third nozzle liquid port  102 . 3  for providing a third liquid cleaning pulse FRI 3  and has a third nozzle compressed-air port  104 . 3  for providing a third compressed-air cleaning pulse DRI 3 , and the fourth nozzle branch  520 . 4  has a fourth nozzle liquid port  102 . 4  for providing a fourth liquid cleaning pulse FRI 4  and has a fourth nozzle compressed-air port  104 . 4  for providing a fourth compressed-air cleaning pulse DRI 4 . One or more cleaning nozzles  320  may be connected in each case to a combination composed of a nozzle liquid port  102  and a nozzle compressed-air port  104  of a nozzle branch  520  for the purposes of a supply of compressed air DL and cleaning liquid F. In the present case, by way of example, one cleaning nozzle  320  is provided per nozzle branch  520 , specifically a first cleaning nozzle  320 . 1  for the first nozzle branch  520 . 1 , a second cleaning nozzle  320 . 2  for the second nozzle branch  520 . 2 , a third cleaning nozzle  320 . 3  for the third nozzle branch  520 . 3  and a fourth cleaning nozzle  320 . 4  for the fourth nozzle branch  520 . 4 . 
     The multi-channel cleaning apparatus  100  has a liquid distributor  560  that connects the module liquid port  618  in fluid-conducting fashion to the individual liquid nozzle lines  626 . 1 ,  626 . 2 ,  626 . 3 ,  626 . 4 . 
     The multi-channel cleaning apparatus  100  has a compressed-air distributor  570  that pneumatically connects the module compressed-air port  272  to the switching valves  2701 ,  2702 ,  2703 ,  2704 , in particular to the first port  2701 . 1 ,  2702 . 1 ,  2703 . 1 ,  2704 . 1  thereof. 
     The multi-channel cleaning apparatus  100  has a compressed-air bypass distributor  580  which—shown in two parts in  FIG.  3   —pneumatically connects the module compressed-air port  272  to the bypass lines  623 . 1 ,  623 . 2 ,  623 . 3 ,  623 . 4 . 
     The multi-channel cleaning apparatus  100  has a module control connection  590  which may be configured as an in particular standardized plug connection for the connection of a suitable plug of a vehicle control line  1024 , in particular for the signal-transmitting connection of the multi-channel cleaning apparatus  100  and/or of the sensor cleaning module  200  to a vehicle control unit  1020  of the vehicle  1000 . Alternatively or in addition, the multi-channel cleaning apparatus  100  may have a module control unit  210  which is configured to be connectable in signal-transmitting fashion to the vehicle control unit  1020  of the vehicle  1000 , in particular via a vehicle control line  1024 , configured as a vehicle bus  1026 . The module control unit  210  serves in particular as an interface between the cleaning apparatus  100  and the vehicle control unit  1020  and allows signal-transmitting communication via the vehicle bus  1026  using a suitable protocol, in particular CAN. The vehicle bus  1026  is configured in particular as a CAN bus. 
     The module control connection  590  may have a bypass control connection  592  for each nozzle branch  520 , in the present case a first bypass control connection  592 . 1 , a second bypass control connection  592 . 2 , a third bypass control connection  592 . 3  and a fourth bypass control connection  592 . 4 , each bypass control connection  592 . 1 ,  592 . 2 ,  592 . 3 ,  592 . 4  being connected in signal-transmitting fashion, in particular for the transmission of a control signal, to the bypass valve  3301 ,  3302 ,  3303 ,  3304  of the respective nozzle branch  520 . 1 ,  520 . 2 ,  520 . 3 ,  520 . 4 . 
     Each nozzle branch  520  has a bypass valve  3300 , which is arranged in the respective bypass line  623 , for providing a bypass compressed-air flow BDS. The first nozzle branch  520 . 1  has, in a first bypass line  623 . 1 , a first bypass valve  3301  for providing a first bypass cornpressed-air flow BDS 1 . The second nozzle branch  520 . 2  has, in a second bypass line  623 . 2 , a second bypass valve  3302  for providing a second bypass compressed-air flow BDS 2 . The third nozzle branch  520 . 3  has, in a third bypass line  623 . 3 , a third bypass valve  3303  for providing a third bypass compressed-air flow BDS 3 . The fourth nozzle branch  520 . 4  has, in a fourth bypass line  623 . 4 , a fourth bypass valve  3304  for providing a fourth bypass compressed-air flow BDS 4 . 
     The module control connection  590  may have a switching valve control connection  594  for each nozzle branch  520 , in the present case a first switching valve control connection  594 . 1 , a second switching valve control connection  594 . 2 , a third switching valve control connection  594 . 3  and a fourth switching valve control connection  594 . 4 , each switching valve control connection  594 . 1 ,  594 . 2 ,  594 . 3 ,  594 . 4  being connected in signal-transmitting fashion, in particular for the transmission of a control signal, to the switching valve  2701 ,  2702 ,  2703 ,  2704  of the respective nozzle branch  520 . 1 ,  520 . 2 ,  520 . 3 ,  520 . 4 . 
     The module control connection  590  may furthermore have a ground connection  596 , in particular a single ground connection  596  for all bypass valves  3301 ,  3302 ,  3303 ,  3304  and switching valves  2701 ,  2702 ,  2703 ,  2704  of the multi-channel cleaning apparatus  100 . 
     The components of each nozzle branch  520  have already been described in  FIG.  1    or  FIG.  2    and are denoted by corresponding numbering in  FIG.  3    (the decimal point indicates the assignment to the respective nozzle branch, with the exception of the four-digit reference designations for the valves, where the fourth digit denotes the assignment to the nozzle branch and the decimal point denotes the respective port). 
     For the sake of clarity, the ports of the switching valve  2700  and of the bypass valve  3300  have been labelled only for the first switching valve  2701  and the first bypass valve  3301 , and are correspondingly apparent for the other switching valves  2702 ,  2703 ,  2704  and bypass valves  3302 ,  3303 ,  3304 . 
     The multi-channel cleaning apparatus  100  shown in  FIG.  3    may optionally, in a manner illustrated in simplified form here, have an arrangement of a bypass valve  3300  with a quick exhaust valve  3400  in particular for each nozzle branch  520 . 1 ,  520 . 2 ,  520 . 3 ,  520 . 4 , wherein, for each nozzle branch  520 . 1 ,  520 . 2 ,  520 . 3 ,  520 . 4 , the quick exhaust valve  3400  is arranged, analogously to  FIG.  2   , in the respective bypass line  623 . 1 ,  623 . 2 ,  623 . 3 ,  623 . 4 , specifically in each case in the sequence of bypass valve  3300 , quick exhaust valve  3400 , bypass check valve  356  and bypass connection point  621 . Thus, in the present case, in each case together with a bypass check valve  356  as shown in  FIG.  2   , a first quick exhaust valve  3401  of the first nozzle branch  520 . 1  for providing a first bypass compressed-air cleaning pulse BDRI 1  is arranged with a first bypass check valve  356 . 1  in a first bypass line  623 . 1 , a second quick exhaust valve  3402  of the second nozzle branch  520 . 2  for providing a second bypass compressed-air cleaning pulse BDRI 2  is arranged with a second bypass check valve  356 . 2  in a second bypass line  623 . 2 , a third quick exhaust valve  3403  of the third nozzle branch  520 . 3  for providing a third bypass compressed-air cleaning pulse BDRI 3  is arranged with a third bypass check valve  356 . 3  in a third bypass line  623 . 3 , and a fourth quick exhaust valve  3404  of the fourth nozzle branch  520 . 4  for providing a fourth bypass compressed-air cleaning pulse BDRI 4  is arranged with a fourth bypass check valve  356 . 4  in a fourth bypass line  623 . 4 . 
     The multi-channel cleaning apparatus  100  shown in  FIG.  3    may be housed in a module housing  290  in order to form a multi-channel sensor cleaning module  200 . The module housing  290  may be formed from a suitable material, in particular from a plastic that exhibits adequate strength or from aluminum. 
       FIG.  4 A  schematically shows a single pressure cylinder  220  in the form of a pressure cylinder module  532  in a lateral cross-sectional view. Multiple, in particular structurally identical, pressure cylinder modules  532  may be assembled together, in particular joined together, in particular by screw connection, in a row and so as to be adjacent to one another in each case at one module side  534 , to form a pressure cylinder block  530 . This is shown by way of example in  FIG.  4 B  in a schematic plan view of four pressure cylinder modules  532 . 1 ,  532 . 2 ,  532 . 3 ,  532 . 4  for forming a pressure cylinder block  530 . For a better arrangement of individual or multiple pressure cylinder modules  532  adjacent to one another, a pressure cylinder module  532  may in particular, as shown in  FIG.  4 B , have an approximately rectangular, in particular approximately square, external cross section. 
       FIG.  4 A  furthermore shows a separating means  226  in the form of a cylinder plunger  227  which is arranged within the cylinder volume VZ of the pressure cylinder  220  so as to be movable axially along the cylinder axis AZ and so as to bear in pressure-tight fashion against an inner wall  536  of the pressure cylinder  220 . The cylinder plunger  227  thus variably divides the cylinder volume VZ into an air chamber  222 , which accommodates compressed air DL and which has an air chamber volume VL, and a liquid chamber  224 , which accommodates cleaning liquid F and which has a liquid chamber volume VF. The air chamber  222  is separated in fluid-tight fashion from the air chamber  224  by virtue of the cylinder plunger  227  bearing—circumferentially around the cylinder plunger  227 —against the inner wall  536  of the pressure cylinder  220 . Via an air chamber port  223 , it is firstly possible for compressed air DL to be applied to the air chamber  222  with an application pressure PB, for the purposes of generating an application force FB that acts on the cylinder plunger  227 , and it is secondly possible, for the purposes of providing a compressed-air cleaning pulse DRI, for the air chamber  222  to emit compressed air DL with a pulse pressure PI by virtue of the separating means  226  performing a return movement under the action of the restoring force. The pulse pressure is determined here in particular from the restoring force multiplied by the plunger area AS of the cylinder plunger  227 . Via a liquid chamber port  225 , the liquid chamber  224  can induct cleaning liquid F and can emit the cleaning liquid with a liquid pressure PF for the purposes of providing a liquid cleaning pulse FRI. The liquid pressure PF is dependent on the application pressure PB, though it is not possible for the entire application pressure PB to be utilized as liquid pressure PF at the liquid chamber port  225  because losses arise in overcoming the restoring force FR. 
     Optionally, for better sealing of the air chamber  222  from the liquid chamber  224 , the cylinder plunger  227  may have a sealing ring  229 , in particular composed of plastic and/or rubber. 
     The cylinder plunger  227  is held in the cylinder volume VZ of the pressure cylinder  220  by a restoring spring  228  such that, in the event of a deflection, in particular as a result of the application pressure PB being applied to the air chamber port  223 , a restoring force FR is generated. 
     Here, the restoring spring  228  may advantageously be configured to move the cylinder plunger  227  with a stroke amplitude AH that extends along the cylinder axis AZ over a cylinder volume height VZH of the cylinder volume VZ minus a plunger height HS of the cylinder plunger  227  and minus a minimum spring height HFMIN of the restoring spring  228  in the compressed state. The restoring spring  228  may in particular have a maximum spring height HFMAX in order to achieve the stroke amplitude AH. 
     The stroke amplitude AH is dependent inter alia on the maximum spring height HF. The stroke amplitude AH is the axial travel that the cylinder plunger  227  must cover in order to move from a bottom dead center UT to a top dead center OT. The stroke amplitude HA thus defines an effective delivery volume VE that determines the maximum volume of cleaning liquid F and/or compressed air DL that can be delivered per stroke. 
     Through the selection of a plunger height HS of a cylinder plunger  227 , it is advantageously possible to influence the quantity of cleaning liquid F and compressed air DL delivered by the pressure cylinder  220 , in particular without changing the shape and size of the pressure cylinder  220 , in particular of the pressure cylinder module  532 . Selecting a relatively large plunger height HS has the effect that a plunger volume VS of the cylinder plunger  227  is enlarged. The effective delivery volume VE is correspondingly decreased in size because a greater proportion of the cylinder volume VZ is already occupied by the plunger volume VS of the cylinder plunger  227 . Correspondingly, in the case of a relatively large plunger height HS, the volume of compressed air DL and cleaning liquid F delivered by the pressure cylinder  220 , that is, the volume of the compressed-air cleaning pulse DRI and of the liquid cleaning pulse FRI, is reduced. 
     The pressure cylinder  220  may have a cylinder volume VZ of between 5 ml and 80 ml, preferably between 10 ml and 40 ml, particularly preferably between 10 and 20 ml. 
     In an embodiment in which the pressure cylinder  220  has a cylinder volume VZ of 20 ml, and a plunger height HS of the cylinder plunger  220  is selected so as to result in a plunger volume VS of 8 ml, and if for simplicity one assumes a dead volume of 2 ml resulting from the minimum spring height HFMIN, then there is a remaining effective delivery volume VE of approximately around 10 ml that is available both for providing the compressed-air cleaning pulse DRI via the air chamber port  223  and providing the liquid cleaning pulse FRI via the liquid chamber port  225 . This means that, in such a configuration, a compressed-air cleaning pulse DRI with a volume of 10 ml compressed air DL and a liquid cleaning pulse FRI with a volume of 10 ml cleaning liquid F can be provided. 
       FIG.  5    is a schematic illustration of a vehicle  1000 , in particular of a passenger motor vehicle  1002  or utility vehicle  1004  or trailer  1006 , in the present case in the form of an autonomous or partially autonomous vehicle, including a multi-channel cleaning apparatus  100  with a number of nozzle branches  520  for a number of at least two cleaning nozzles  320 , in the present case with a first nozzle branch  520 . 1  for a first cleaning nozzle  320 . 1  for cleaning a first sensor surface  300 . 1  of a first sensor  301 . 1 , which is configured as an optical sensor, for example as a camera, and with a second nozzle branch  520 . 2  for a second cleaning nozzle  320 . 2  for cleaning a second sensor surface  300 . 2  of a second sensor  301 . 2 , which is configured as an optical sensor, for example as a camera. 
     The multi-channel cleaning apparatus  100  may nevertheless be used in other vehicles. 
     The multi-channel cleaning apparatus  100  is configured in particular as a sensor cleaning module  200 . The cleaning apparatus  100  has a module control port  590  that is connected in signal-transmitting fashion to a vehicle control unit  1020  via a vehicle control line  1024 . The vehicle control line  1024  is configured in particular as a vehicle bus  1026 , in particular CAN bus. 
     The first sensor  301 . 1  is connected in signal-transmitting fashion via a first sensor line  306 . 1  to the vehicle control unit  1020  for the transmission of first sensor signals  305 . 1 . In particular, a first cleaning check signal  307 . 1  for establishing whether a first liquid cleaning pulse FRI 1  has been emitted can be transmitted via the first sensor line  306 . 1  to the vehicle control unit  1020 . Analogously, the second sensor  301 . 2  is connected in signal-transmitting fashion via a second sensor line  106 . 2  to the vehicle control unit  1020  for the transmission of second sensor signals  305 . 2 , in particular of a second cleaning check signal  307 . 2 . 
     In the case of a sensor  301 . 1 ,  301 . 2  configured as a camera, a cleaning check signal  307 . 1 ,  307 . 2  may be generated in particular using image recognition means, for example through the identification of liquid particles in the camera image. 
     Each cleaning nozzle  320 . 1 ,  320 . 2  is configured to apply a liquid cleaning pulse FRI 1 , FRI 2  and/or a compressed-air cleaning pulse DRI 1 , DRI 2  and/or a bypass compressed-air flow BDS 1 , BDS 2  and/or a bypass compressed-air cleaning pulse BDRI 1 , BDRI 2  to the respective sensor surface  300 . 1 ,  300 . 2 . 
     Each cleaning nozzle  320 . 1 ,  320 . 2  is connected in fluid-conducting fashion, via a respective nozzle liquid port  102 . 1 ,  102 . 2  and nozzle compressed-air port  104 . 1 ,  104 . 2 , to the multi-channel cleaning apparatus  100 . In embodiments in which the cleaning nozzle  320  is not arranged directly at the cleaning apparatus  100  or at the sensor cleaning module  200 , the cleaning nozzle  320  may be connected in fluid-conducting fashion via a nozzle connection line  108 . 1 ,  108 . 2  to the nozzle liquid port  102  and/or to the nozzle compressed-air port  104 . 
     It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims. 
     LIST OF REFERENCE DESIGNATIONS (PART OF THE DESCRIPTION) 
     
         
           100  Multi-channel cleaning apparatus 
           102  Nozzle liquid port 
           102 . 1  First nozzle liquid port 
           102 . 2  Second nozzle liquid port 
           102 . 3  Third nozzle liquid port 
           102 . 4  Fourth nozzle liquid port 
           104  Nozzle compressed-air port 
           104 . 1  First nozzle compressed-air port 
           104 . 2  Second nozzle compressed-air port 
           104 . 3  Third nozzle compressed-air port 
           104 . 4  Fourth nozzle compressed-air port 
           200  Sensor cleaning module 
           220  Pressure cylinder 
           220 . 1  First pressure cylinder 
           220 . 2  Second pressure cylinder 
           220 . 3  Third pressure cylinder 
           220 . 4  Fourth pressure cylinder 
           221  Cylinder inner wall of the pressure cylinder 
           222  Air chamber 
           223  Air chamber port 
           224  Liquid chamber 
           225  Liquid chamber port 
           225 . 1  First liquid chamber port 
           225 . 2  Second liquid chamber port 
           225 . 3  Third liquid chamber port 
           225 . 4  Fourth liquid chamber port 
           225 . 1 A First part of the first liquid chamber port 
           225 . 16  Second part of the first liquid chamber port 
           226  Separating means 
           227  Cylinder plunger 
           228  Restoring spring 
           229  Sealing ring 
           230  Air chamber line 
           270  Switching valve 
           272  Module compressed-air port 
           273  Compressed-air connection line 
           278  Compressed-air nozzle line 
           290  Module housing 
           292  Valve cartridge housing 
           300  Sensor surface 
           300 . 1  First sensor surface 
           300 . 2  Second sensor surface 
           301  Sensor 
           301 . 1  First sensor 
           301 . 2  Second sensor 
           305  Sensor signal 
           306  Sensor line 
           307  Sensor line 
           320  Cleaning nozzle 
           320 . 1  First cleaning nozzle 
           320 . 2  Second cleaning nozzle 
           320 . 3  Third cleaning nozzle 
           320 . 4  Fourth cleaning nozzle 
           341  Compressed-air buffer 
           350  Induction pressure check valve 
           352  Liquid pulse check valve 
           354  Compressed-air pulse check valve 
           356  Bypass check valve 
           356 . 1  First bypass check valve 
           356 . 2  Second bypass check valve 
           356 . 3  Third bypass check valve 
           356 . 4  Fourth bypass check valve 
           400  Liquid source 
           520  Nozzle branch 
           520 . 1  First nozzle branch 
           520 . 2  Second nozzle branch 
           520 . 3  Third nozzle branch 
           520 . 4  Fourth nozzle branch 
           530  Pressure cylinder block 
           532  Pressure cylinder module 
           532 . 1  First pressure cylinder module 
           532 . 2  Second pressure cylinder module 
           532 . 3  Third pressure cylinder module 
           532 . 4  Fourth pressure cylinder module 
           534  Module side 
           536  Inner wall 
           560  Liquid distributor 
           570  Compressed-air distributor 
           580  Compressed-air bypass distributor 
           590  Module control connection 
           592  Control connection 
           592 . 1  First bypass control connection 
           592 . 2  Second bypass control connection 
           592 . 3  Third bypass control connection 
           592 . 4  Fourth bypass control connection 
           594  Switching valve control connection 
           594 . 1  First switching valve control connection 
           594 . 2  Second switching valve control connection 
           594 . 3  Third switching valve control connection 
           594 . 4  Fourth switching valve control connection 
           600  Compressed-air source 
           602  Compressor 
           604  Pressure accumulator 
           606  Compressed-air supply system 
           618  Module liquid port 
           619  Cylinder connection point 
           619 . 1  First cylinder connection point 
           619 . 2  Second cylinder connection point 
           619 . 3  Third cylinder connection point 
           619 . 4  Fourth cylinder connection point 
           621  Bypass connection point 
           621 . 1  First bypass connection point 
           621 . 2  Second bypass connection point 
           621 . 3  Third bypass connection point 
           621 . 4  Fourth bypass connection point 
           623  Bypass line 
           623 . 1  First bypass line 
           623 . 2  Second bypass line 
           623 . 3  Third bypass line 
           623 . 4  Fourth bypass line 
           626  Liquid nozzle line 
           626 . 1  First liquid nozzle line 
           626 . 2  Second liquid nozzle line 
           626 . 3  Third liquid nozzle line 
           626 . 4  Fourth liquid nozzle line 
           1000  Vehicle 
           1002  Passenger motor vehicle 
           1004  Utility vehicle 
           1020  Vehicle control unit 
           1022  Control signal 
           1024  Vehicle control line 
           1026  Vehicle bus 
           2700  Switching valve 
           2701  First switching valve 
           2702  Second switching valve 
           2703  Third switching valve 
           2704  Fourth switching valve 
           2700 A Air admission position 
           2700 B Venting position 
           2700 . 1  First port of the switching valve 
           2700 . 2  Second port of the switching valve 
           2700 . 3  Third port of the switching valve 
           2701 . 1  First port of the first switching valve 
           2702 . 1  First port of the second switching valve 
           2703 . 1  First port of the third switching valve 
           2704 . 1  First port of the fourth switching valve 
           3300  Bypass valve 
           3301  First bypass valve 
           3302  Second bypass valve 
           3303  Third bypass valve 
           3304  Fourth bypass valve 
           3320   2 / 2  directional valve 
           3320 A Closed position of the 2/2 directional valve 
           3320 B Open position of the 2/2 directional valve 
           3320 . 1  First port of the 2/2 directional valve 
           3320 . 2  Second port of the 2/2 directional valve 
           3320 . 3  Control line of the 2/2 directional valve 
           3330   2 / 2  directional solenoid valve 
           3340   3 / 2  directional valve 
           3340 . 1  First port of the 3/2 directional valve 
           3340 . 2  Second port of the 3/2 directional valve 
           3340 . 3  Exhaust port of the 3/2 directional valve 
           3340 A Closed position of the 3/2 directional valve 
           3340 B Open position of the 3/2 directional valve 
           3400  Quick exhaust valve 
           3400 . 1  First port of the quick exhaust valve 
           3400 . 2  Second port of the quick exhaust valve 
           3400 . 3  Third port of the quick exhaust valve 
           3400 . 4  Valve element 
           3400 . 5  Quick exhaust valve control line 
           3401  First quick exhaust valve 
           3402  Second quick exhaust valve 
           3403  Third quick exhaust valve 
           3404  Fourth quick exhaust valve 
         AH Stroke amplitude 
         AS Plunger surface 
         AZ Cylinder axis 
         BDS Bypass compressed-air flow 
         BDS 1  First bypass compressed-air flow 
         BDS 2  Second bypass compressed-air flow 
         BDS 3  Third bypass compressed-air flow 
         BDS 4  Fourth bypass compressed-air flow 
         BDRI Bypass compressed-air cleaning pulse 
         BDRI 1  First bypass compressed-air cleaning pulse 
         BDRI 2  Second bypass compressed-air cleaning pulse 
         BDRI 3  Third bypass compressed-air cleaning pulse 
         BDRI 4  Fourth bypass compressed-air cleaning pulse 
         DL Compressed air 
         DRI Compressed-air cleaning pulse 
         DRI 1  First compressed-air cleaning pulse 
         DRI 2  Second compressed-air cleaning pulse 
         DRI 3  Third compressed-air cleaning pulse 
         DRI 4  Fourth compressed-air cleaning pulse 
         F Cleaning liquid 
         FB Application force 
         FR Restoring force 
         FRI Liquid cleaning pulse 
         FRI 1  First liquid cleaning pulse 
         FRI 2  Second liquid cleaning pulse 
         FRI 3  Third liquid cleaning pulse 
         FRI 4  Fourth liquid cleaning pulse 
         HS Plunger height 
         HFMIN Minimum spring height 
         HFMAX Maximum spring height 
         PB Application pressure 
         PI Pulse pressure 
         PF Liquid pressure 
         PST Control pressure 
         UT Bottom dead center 
         OT Top dead center 
         VE Effective delivery volume 
         VF Liquid chamber volume 
         VL Air chamber volume 
         VS Plunger volume 
         VZ Cylinder volume 
         VZH Cylinder volume height