Patent Publication Number: US-2022234411-A1

Title: Air suspension system for a vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of international patent application PCT/EP2020/077912, filed Oct. 6, 2020 designating the United States and claiming priority from German application 10 2019 129 014.7, filed Oct. 28, 2019, and the entire content of both applications is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to an air suspension system for vehicles, in particular utility vehicles or passenger cars. In particular, the disclosure relates here to a module or a plurality of modules, and to a control device for the air suspension system, to an air suspension system, to a vehicle with an air suspension system of this type, to a vehicle trailer, and to a method for operating the air suspension system. 
     BACKGROUND 
     Vehicles which have air suspension systems are known from the prior art. Although air suspension systems are more complicated than the likewise known spring systems which are realized with combinations of a coil or leaf spring with a shock absorber, they increase the driving comfort and the safety. In the case of air suspension systems, the coil or leaf springs are replaced by air springs which include bellows which are filled or can be filled with gas such as, for example, air, in order thus to provide the suspension action. Air suspension systems thus generally make it possible to protect occupants, body and a load of a vehicle against shocks which are caused, for example, by way of ground unevenness while driving. 
     Furthermore, air suspension systems can be divided fundamentally into two different systems, namely those, in the case of which the gas pressure or the gas mass of the air spring, namely in the bellows, can be adjusted, and those, in the case of which the gas mass cannot be adjusted. The gas mass of the air springs in the case of non-adjustable air suspension systems is accordingly fixedly specified. Here, non-adjustable air suspension systems are comparable functionally with conventional spring systems, in the case of which a combination of a leaf or spiral spring with a shock absorber is used. These air suspension systems which are not adjustable are therefore not the subject matter of the disclosure and thus will not be considered in the further text. 
     In contrast, adjustable air suspension systems have variable gas pressures or variable gas masses, preferably air masses, of the air springs, namely of the bellows. Accordingly, additional functions are made possible by way of air suspension systems which are adjustable, which additional functions include, for example, a ride height regulation, in the case of which a ground clearance of the vehicle can be adapted by way of adaptation of the gas masses. An adaptation of the gas masses takes place, for example, in a manner which is dependent on a terrain which is to be driven over or a vehicle load, that is, an overall vehicle mass. 
     Since the behavior of air springs of air suspension systems has a direct influence on the driving behavior of a vehicle with the air suspension system, adjustable air suspension systems are governed by complex regulating mechanisms, in order to make the best possible comfort and the best possible safety possible. Here, for example, constant monitoring takes place of the spacing between the vehicle frame, the body or body parts, such as a wheel arch, and a wheel suspension system. The gas pressures of the individual air springs are also monitored. A multiplicity of valves for wheel-specific filling or emptying of the air springs then has to be actuated in a manner which is dependent on the monitoring. 
     Therefore, air suspension systems which are adapted precisely to a vehicle, in which they are to be used, are known from the prior art. In the case of these air suspension systems, all the valves which are to be provided for the air springs and a control device for controlling the valves are frequently arranged within one housing. Compressed air hoses of the air springs of the individual wheels are then connected to the housing, and the housing is connected to a compressed air source, in order to realize the air suspension system in a vehicle. 
     Integrated air suspension systems of this type afford the advantage in comparison with individual equipping of each single wheel with a valve that an air suspension system can be integrated into a vehicle substantially more rapidly. It is disadvantageous here, however, that a system of this type is adapted specifically to a vehicle type. For example, vehicles which have a different number of axles cannot be equipped with the same integrated air suspension system, since the number of valves changes depending on the wheels to be suspended. A system which was configured, for example, for two axles would not have sufficient valves, in order to actuate the air springs of a vehicle with three axles individually. Secondly, a system which was configured for three axles, would be over dimensioned for a vehicle with two axles, since some valves would remain unused and the use of a system of this type would therefore be uneconomical. 
     SUMMARY 
     It is an object of the disclosure to provide an adjustable air suspension system which addresses at least one of the problems of the prior art. In particular, an air suspension system is to be found which firstly can be integrated into a vehicle in a simple way, but secondly can be adapted to different vehicles or vehicle types. At any rate, an air suspension system which is alternative to the prior art is to be found. 
     To this end, the disclosure relates to a module for an air suspension system. The module for the air suspension system is a module for an air suspension system of a vehicle which is, in particular, a utility vehicle or a passenger car. The module has a sensor interface for connecting to a sensor. The sensor interface is configured to receive sensor values from the sensor. Here, in particular, the sensor interface is configured to be connected to a displacement sensor, in order to receive displacement sensor values of the displacement sensor as sensor values. Furthermore, the module has a valve, the valve being, in particular, an electropneumatic valve. Moreover, the module has a data interface which is preferably a bus interface, in particular a CAN bus interface. The data interface is configured to output sensor values received by way of the sensor interface to a control device, and to receive control commands for controlling the valve from the control device. 
     The module thus consolidates, in particular in one housing, one or more valves, one or more connection options for one or more sensors, and provides a data interface which outputs the sensor values and at the same time accepts control values for the valve. A module of this type can then be used in interaction with a corresponding control device, in order to form the air suspension system overall. A control device can be realized, for example, by any desired control unit and a computing unit, by way of which a regulating method can be carried out. Thus, for example, a control unit which is already present in the vehicle, such as, for example, a brake control unit, an engine control unit, a transmission control unit or the like, can be used as control device, and any desired number of modules can be connected to the control device in a vehicle-specific manner. 
     For example, the module can be configured for one wheel or one axle, with the result that, in the case of a vehicle with two axles, four modules can be used if the module is configured for one wheel, or two modules can be used if the module is configured for one axle. In the case of a vehicle with three axles, six modules can then be used if the module is configured for one wheel, or three modules can be used if the module is configured for one axle. Accordingly, the modules are connected to the control device, the air springs and a sensor as part of an air suspension system depending on arrangement, for example on the vehicle frame. In this way, the modules can in each case be arranged close to a wheel or an axle, since each module is used exclusively for the actuation of the air springs of an axle which is assigned to it or the air spring of a wheel which is assigned to it. Pressure hoses for connecting the air springs therefore have to be laid only over a short distance. The connecting complexity is therefore likewise reduced. 
     Moreover, a rapid installation of the air suspension system which is formed by way of modules is thus possible, a vehicle-specific adaptation of the air suspension system also being possible without great complexity. Merely the control device has to be preprogrammed, for example, for different vehicles or vehicle types with different regulating algorithms in a manner which is dependent on the number of modules used. An adaptation of the modules per se is not necessary. 
     In accordance with a first embodiment, the module additionally includes a pressure sensor for detecting at least one pressure sensor value of a compressed air line which is connected to the valve. Furthermore, the module is configured to output the pressure sensor value via the data interface to the control device. 
     In this way, a pressure sensor is therefore also already provided for monitoring the air spring pressure, which pressure sensor can be connected to the valve, and the connection to an external pressure sensor, for example in the air spring or in the region of the air spring, can be dispensed with. Additional cabling complexity or the additional arrangement of a pressure sensor is therefore dispensed with, with the result that an even more rapid installation of an air suspension system on a vehicle is possible. 
     In accordance with a further embodiment, the module includes precisely three valves. An input of the first valve of the three valves can be connected to a pressure source, in particular a compressed air source, and an output of the first valve is connected to the inputs of the second valve and the third valve. Outputs of the second valve and the third valve can be connected in each case to an air spring of an air suspension system. 
     In accordance with this embodiment, in particular, the module also includes a sensor interface which is configured to be connected to two sensors which are preferably displacement sensors. A sensor interface is used, furthermore, in the singular here, even if it serves to connect more than one sensor, it also being possible for a sensor interface to have two or more plug-in connectors which are connected in each case to a sensor. Accordingly, one or more plug-in connectors for connecting to in each case one sensor are named and combined overall as a sensor interface. 
     As a result of the arrangement of the three valves, the module is prepared in such a way that it can be assigned to precisely one axle with two wheels, the wheels being assigned in each case one air spring, with the result that the module can correspondingly be assigned to the air springs which are assigned in each case to the wheels. The assignment of one module to precisely one axle is advantageous, since merely the number of axles is dependent on the configuration of the vehicle. In contrast, the number of air springs per axle is identical regardless of an embodiment of the vehicle. As a result of the abovementioned embodiment, the module is therefore configured in such a way that firstly the installation complexity is reduced to one module per axle, since the two air springs of an axle can be actuated at the same time by way of one module, and that secondly an economic adaptation to different vehicle types with a different number of axles is possible. 
     In accordance with a further embodiment, the module includes two pressure sensors which are arranged in each case in the region of the outputs of the second valve and the third valve. The second valve therefore has a further pressure sensor in the region of its output, and the third valve has a pressure sensor in the region of its output. Here, the region of the output is not restricted to the direct output of the respective valve itself, but rather also includes the flowing region of a pressure hose which is connected to the output of the second or third valve, or of a pressure line which is connected to the output of the second or third valve, through which a fluid, in particular air, flows. In particular, the sensor is also arranged in the region of the output of the corresponding valve in such a way that the pressure of an air spring which is connected via a pressure hose or a pressure line to the valve can be measured, even if the respective valve is closed. In accordance with this embodiment, furthermore, the module is configured to output the pressure sensor values of the pressure sensors via the data interface. 
     In this way, a continuous measurement of the air pressure of the air springs is possible, even if the valves for feeding in or discharging fluid, in particular air, to and from the valve are closed. 
     In accordance with a further embodiment, the first valve is a 3/2-way valve. The second valve and the third valve are in each case a 2/2-way valve. As a result of this configuration of the valves, it is possible for a pressure for the air springs which can be connected to the second and the third valve to be provided in a first valve position via the first valve, namely in particular the input of the first valve which can be connected to the pressure source, in particular a compressed air source. In the case of a second valve position, in contrast, a gas pressure can be discharged from the air springs via the first valve. Furthermore, as a result of the configuration of the second valve and third valve in each case as a 2/2-way valve, the air springs of the wheels of one axle can be actuated individually. A realization of the valves for providing the full functionality is therefore possible with low complexity of the configuration of the valves. 
     In accordance with a further embodiment, the first valve has a first passage cross section, the second valve has a second passage cross section, and the third valve has a third passage cross section. The second and the third passage cross section are preferably substantially identical. Substantially identical means that the second passage cross section is identical to the third passage cross section, or the second passage cross section differs from the third passage cross section by less than 10%, less than 5% or less than 1%. In accordance with this embodiment, the first passage cross section corresponds at least to the sum of the second and third passage cross section. 
     The valves can thus particularly preferably firstly be configured in such a way that the second and third valve are minimized in terms of their overall size in comparison with the first valve, and secondly at the same time pressurizing as rapidly as possible of the air springs or venting of the air springs is possible. 
     In accordance with a further embodiment, the module is configured to actuate the first valve in a manner which is dependent on the control command in such a way that the throughflow quantity can be controlled in a variable manner, in particular in multiple steps or in an infinitely variable manner. The throughflow quantity through the first valve can therefore be set in a manner which is dependent on the actuation. 
     In order, in particular, to vent the air springs at a standstill or at night, the air can thus be brought about with a comparatively low throughflow quantity through the first valve, in order thus to reduce the development of noise during venting. During venting while moving, in the case of which a development of noise is not important, for example, the throughflow quantity can be comparatively high, in order to make a rapid variation of the air spring pressure possible. Secondly, for example, the throughflow quantity can also particularly preferably be varied in a manner which is dependent on a speed of the vehicle, in order, for example, to make a higher throughflow quantity at a lower speed possible and to make a lower throughflow quantity at a higher speed possible. The driving comfort can thus be increased, by low change rates for the height adjustment, for example, at high speeds leading to oscillations being reduced or avoided. 
     In accordance with a further embodiment, the module has a PWM signal generator. A PWM signal generator is a generator which generates a pulse width modulated signal (PWM signal). The PWM signal generator serves to actuate at least the first valve by way of the PWM signal. The throughflow quantity of the valve is thus controlled in a manner which is dependent on the pulse width of the PWM signal, it being possible for the throughflow quantity to be varied from a minimum value, in the case of which the first valve is constantly closed, as far as a maximum value, in the case of which the first valve is constantly open. 
     An actuation of the first valve which is configured to vary the throughflow quantity in multiple steps or in an infinitely variable manner is particularly simply possible by way of a PWM signal, since a valve of this type which is configured as an electropneumatic valve and can fundamentally switch only between a completely open and a completely closed state can be used for the variation, in particular for the infinitely variable variation, of the throughflow quantity. Therefore, a specifically adapted valve which, for example, has more than two switching states for the variation of the throughflow quantity can be dispensed with. 
     In accordance with a further embodiment, the module has a fault diagnosis device, in order to carry out a fault diagnosis of the module. The fault diagnosis preferably includes detecting of a fault of the data connection to a control device and/or detecting of a fault of a data connection to the sensor or sensors connected via the sensor interface. As an alternative or in addition, the fault diagnosis includes testing of a valve functionality and/or a function of connected sensors. In the case of a fault which is diagnosed by way of the fault diagnosis, the valve or all the valves of the module is/are moved into a predefined state. It is also possible that the valve or all the valves of the module remains/remain in the position it/they had before the detected fault. In particular, in the case of a detected fault, all the valves of the module therefore remain in the position which the respective valve had before the detected fault. Furthermore, it is possible that, in the case of a detected fault, the valve of the module is closed or all the valves of the module are closed. 
     An operational readiness of the module can therefore be indicated after conclusion of a fault diagnosis, in the case of which no fault has been detected, it preferably being possible for this result to be transmitted via the data interface to a control device. In the case that a fault is detected by way of the fault diagnosis, a defined state of the valves can at least be assumed. 
     This can also be the last state of the valves before the fault. 
     Furthermore, the disclosure relates to a control device for receiving pressure sensor values of pressure sensors via a bus from a module for an air suspension system in accordance with one of the abovementioned embodiments. In particular, the control device is also configured to receive sensor values, in particular displacement sensor values of a displacement sensor, via the bus from the module for an air suspension system in accordance with one of the abovementioned embodiments. The bus is preferably a CAN bus. Furthermore, the control device serves to generate and output control commands for a valve of a module in accordance with one of the abovementioned embodiments. 
     Moreover, the disclosure relates to an air suspension system with one or more modules in accordance with one of the abovementioned embodiments, and preferably with a control device in accordance with one of the abovementioned embodiments. Furthermore, the air suspension system includes a displacement sensor which is connected via the sensor interfaces to the module or one of the modules, and an air spring which is connected to a valve of the module. The module is connected via a data interface and a bus, in particular a CAN bus, to the control device. 
     In addition, the disclosure relates to a vehicle with the air suspension system in accordance with one of the abovementioned embodiments, the control device being a control unit of the vehicle, in particular a brake control unit of the vehicle. In particular, the vehicle has one of the modules per axle. The vehicle can have two displacement sensors and two air springs per axle, which are connected in each case to the module which is assigned to the axle. 
     Furthermore, the disclosure relates to a vehicle trailer which has an air suspension system in accordance with one of the abovementioned embodiments. The vehicle trailer has a plurality of axles, each axle preferably being assigned one module, and the vehicle trailer having a control unit. Here, the control unit implements the control device in accordance with the abovementioned embodiments. The control unit is preferably a trailer brake control unit. As an alternative to the configuration of the control device by way of the control unit, the vehicle trailer has an interface, in order to be connected to a towing vehicle which has a control unit which is configured as a control device in accordance with one of the abovementioned embodiments. 
     Furthermore, the disclosure relates to a method for operating an air suspension system in accordance with one of the abovementioned embodiments. In accordance with the method, displacement sensor values from a displacement sensor which is connected via a sensor interface to a module are first of all received by the module via a control device. Furthermore, pressure sensor values from a pressure sensor of the module are received by way of the control device. Control commands for a valve of the module are then generated and output to the module by way of the control device. 
     In addition, the disclosure relates to a computer program product which includes instructions which, when they are run on a control unit of a vehicle or a trailer vehicle, configure the control unit as control device and cause the control unit to carry out the steps of the method according to the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the drawings wherein: 
         FIG. 1  shows a diagrammatic illustration of a module for an air suspension system; 
         FIG. 2  shows a diagrammatic illustration of an air suspension system; 
         FIG. 3  shows a diagrammatic illustration of a vehicle with an air suspension system; 
         FIG. 4  shows a diagrammatic illustration of a towing vehicle/trailer combination with an air suspension system; 
         FIG. 5  shows a diagrammatic illustration of a further towing vehicle/trailer combination with an air suspension system; and, 
         FIG. 6  shows a flow chart of steps of a method for operating an air suspension system. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a diagrammatic illustration of a module  10  for an air suspension system in accordance with one embodiment. The module  10  includes a data interface  12  which can be connected to a bus, in particular a CAN bus. The data interface  12  is connected to a processing unit  14  which is likewise connected to further components of the module  10 . 
     In accordance with this embodiment, the processing unit  14  is connected to two sensor interfaces  16 , to which displacement sensors can be connected. A displacement sensor which is connected via the sensor interface  16  supplies, in particular, sensor values  17  which preferably correspond to displacement sensor values  15  and which include a spacing, for example between a wheel suspension system and a chassis of a vehicle. The sensor interfaces  16  thus serve to receive sensor values by way of the processing unit  14 , it then being possible for the processing unit  14  to transmit these sensor values in a bus protocol, in order to output these sensor values as a data packet or the like via the interface  12 . 
     Furthermore, the processing unit is connected to three valves  18 ,  20 ,  22 . The processing unit  14  serves to actuate the valves  18 ,  20 ,  22  when a data packet which requests an actuation of one or more valves  18 ,  20 ,  22  is received via the data interface  12 . The three valves  18 ,  20 ,  22  are configured as electropneumatic valves  19 ,  21 ,  23 . 
     One of the valves  18 ,  20 ,  22  which is called first valve  18  in the further text is configured as a 3/2-way valve. Here, the first valve  18  has an input  24 , to which a pressure source, in particular a compressed air source, can be connected. To this end, the input  24  is guided via a compressed air line  26  to an outer side  27  of the housing  28  of the module  10 , and forms a compressed air connector  30  here. Furthermore, an output  32  is provided on the first valve  18 , which output  32  is likewise guided via a compressed air line  34  to the outer side  27  of the housing  28 . A silencer  36  is arranged at the end of the compressed air line  34  on the outer side  27  of the housing  28 . 
     In the position which is shown, that is, the state or switching state which is shown, of the first valve  18 , air can thus be guided with a throughflow quantity  35  via a pressure source which is connected to the compressed air connector  30 , through the first valve  18  to the valves  20 ,  22 . To this end, the first valve  18  has a passage cross section  37  in the position which is shown, namely the passage position  33 . 
     The valves  20 ,  22  are closed in the position which is shown, namely the closed position  39 . The valve  20  is called second valve  20  in the further text, and the valve  22  is called third valve  22  in the further text. If the valves  20 ,  22  are switched over by actuation by way of the processing unit  14 , the compressed air which is provided via the first valve  18  can flow through a compressed air line  38 , which is guided from an output  40  of the first valve  18  to inputs  42 ,  44  of the second valve  20  and the third valve  22 , through the second valve  20  and the third valve  22 , and can flow out at outputs  45 ,  46  of the module  10 . To this end, the second valve  20  has a second passage cross section  41 , and the third valve  22  has a third passage cross section  43 . An air spring of an air suspension system can be connected in each case at the outputs  45 ,  46 . 
     Furthermore, in a passage position of the second valve  20  and the third valve  22  which is not shown in each case here, compressed air can also be discharged from the air springs through the first valve and through the compressed air line  34  by way of switching over of the first valve  18  into a discharge position (not shown) of the first valve  18 . To this end, the silencer  36  is provided, in order to reduce the development of noise during venting of the air springs. In the closed position  39  which is shown of the second valve  20  and the third valve  22 , an air pressure in the air springs which can be connected to the outputs  45 ,  46  can be measured via pressure sensors  48 ,  50  which are integrated into the module  10 . 
     A pressure sensor value  54  which is detected by way of these pressure sensors  48 ,  50  can be converted into a data protocol of a bus system by the processing unit  14 , just like the abovementioned displacement sensor values  15 , in order to output the pressure sensor values  54  via the data interface  12 . 
     Furthermore, the module  10  includes a fault diagnosis device  51 . If a fault of the module  10  is determined by way of the fault diagnosis device  51 , the valves  18 ,  20 ,  22  are switched into a predefined position  52 ,  53 . The predefined position  52 ,  53  preferably corresponds to the open state which is shown, that is, the passage position  33 , of the first valve  18  and the closed state which is shown, that is, the closed position  39 , of the second valve  20  and the third valve  22 . 
     Furthermore, the processing unit  14  includes a generator  53  for generating a pulse width modulated signal  55 , by way of which the first valve  18  is actuated. The throughflow quantity  35  of an air flow through the first valve  18  can thus be varied. In particular in the case of discharging of air, a development of noise can thus be reduced further by way of a small throughflow quantity  35 . In accordance with a further embodiment which is not shown here, the silencer  36  can thus also be dispensed with. 
       FIG. 2  shows a diagrammatic illustration of an air suspension system  60  with the module  10  which is shown in  FIG. 1 . Two sensors  61  which are displacement sensors  62  are connected via the sensor interfaces  16  to the module  10 . Furthermore, a compressed air source  63  is connected to the compressed air connector  30  of the module  10 . The outputs  45 ,  46  are connected in each case via a compressed air line  67  to an air spring  66 . Sensor values  17  which are received from the displacement sensors  62  by way of the sensor interface  16  can thus be transmitted via a bus  56  to the control device  58 . To this end, the data interface  12  is connected to the bus  56  which is a CAN bus  57 . Furthermore, pressure sensor values  54  which are recorded by way of the pressure sensors  48 ,  50  which are not shown here are also transmitted to the control device  58 . The control device  58  transmits control commands  64  via the bus  56  to the module  10 , by way of which control commands the valves  18 ,  20 ,  22  are actuated. 
       FIG. 3  shows a diagrammatic illustration of a vehicle  70  with a control device  58  and two modules  10 . Each of the modules  10  is assigned to one of the axles  72  of the vehicle. The two modules  10  have the data interface  12  and are connected by way of it via a bus  56  to the control device  58 . Furthermore, the modules  10  are connected in each case to two air springs  66  and two displacement sensors  62 . Each of the displacement sensors  62  and each of the air springs  66  are assigned to a wheel  74  of the vehicle  70 . 
       FIG. 4  shows a diagrammatic illustration of a towing vehicle/trailer combination  80  which has a vehicle  70 , for example the vehicle  70  from  FIG. 3 . Here, the vehicle  70  corresponds to a towing vehicle  81 , to which a vehicle trailer  82  is coupled. The vehicle  70  has a brake control unit  84  which serves here as control device  58 . The control device  58  is connected to four modules  10 , each of the modules  10  being assigned to one of the axles  72  of the vehicle  70  and of the vehicle trailer  82 . The bus  56  for connecting the control device  58  to the modules  10  is guided to this end further via a cable connection  86  between the vehicle  70  and the vehicle trailer  82  to the vehicle trailer  82 . In accordance with an embodiment of the disclosure which is not shown here, a radio connection is provided instead of the cable connection  86 . 
       FIG. 5  shows an alternative embodiment to the embodiment of  FIG. 4 .  FIG. 5  once again shows a diagrammatic illustration of a vehicle  70  which is configured as a towing vehicle  81 , and a diagrammatic illustration of a vehicle trailer  82 , which can together be called a towing vehicle/trailer combination  80 . Here, however, in addition to the control device  58  of the towing vehicle  81 , a further control device  58  is provided in the vehicle trailer  82 , which further control device  58  controls the modules  10  of the vehicle trailer  82  and receives sensor values  17  and pressure sensor values  54  from them. The control device  58  in the vehicle trailer  82  is a trailer brake control unit  88  in accordance with this embodiment. 
       FIG. 6  shows a flow chart of the steps of one embodiment of a method  89  for operating an air suspension system. In a step  90 , sensor values  17  from at least one displacement sensor  62  and pressure sensor values  54  from a pressure sensor  48 ,  50  are received by a module  10  by way of a control device  58 . In step  92 , control commands for a valve  18 ,  20 ,  22  are generated in the control device  58 . In step  94 , the control commands are then output to the module  10 . 
     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 DESIGNATIONS (CONSTITUENT PART OF THE DESCRIPTION) 
     
         
           10  Module 
           12  Data interface 
           14  Processing unit 
           15  Displacement sensor values 
           16  Sensor interfaces 
           17  Sensor values 
           18  Valve 
           19  Electropneumatic valve 
           20  Valve 
           21  Electropneumatic valve 
           22  Valve 
           23  Electropneumatic valve 
           24  Input 
           26  Compressed air line 
           27  Outer side 
           28  Housing 
           30  Compressed air connector 
           32  Output 
           33  Passage position 
           34  Compressed air line 
           35  Throughflow quantity 
           36  Silencer 
           37  First passage cross section 
           38  Compressed air line 
           39  Closed position 
           40  Output 
           41  Second passage cross section 
           42  Input 
           43  Third passage cross section 
           44  Input 
           45  Output 
           46  Output 
           48  Pressure sensor 
           50  Pressure sensor 
           51  Fault diagnosis device 
           52  Predefined position 
           53  Predefined position 
           54  Pressure sensor value 
           55  Pulse width modulated signal 
           56  Bus 
           57  CAN bus 
           58  Control device 
           60  Air suspension system 
           61  Sensor 
           62  Displacement sensor 
           63  Compressed air source 
           64  Control commands 
           66  Air springs 
           67  Compressed air line 
           70  Vehicle 
           72  Axles 
           74  Wheel 
           80  Towing vehicle/trailer combination 
           81  Towing vehicle 
           82  Vehicle trailer 
           84  Brake control unit 
           86  Cable connection 
           88  Trailer brake control unit 
           89  Method 
           90  Step 
           92  Step 
           94  Step