AIR SUSPENSION CONTROL SYSTEM AND AIR SUSPENSION SYSTEM AS WELL AS VEHICLE THEREOF AND METHOD THEREFOR

Description

[0001] The invention relates to the field of air suspension systems for commercial vehicles or passenger cars. Air suspension systems for vehicles are known that improve ride comfort and safety through the use of air springs. This is achieved, for example, by the air springs protecting the vehicle's body and passengers from impacts caused by uneven road surfaces during travel. Furthermore, vibrations caused by uneven road surfaces during travel can be dampened or even prevented.

[0002] A further distinction must be made between adjustable and non-adjustable air suspension systems. Adjustable air suspension systems typically have a variable gas mass, preferably air mass, of the air springs, whereas the gas mass of the air springs in non-adjustable air suspension systems is fixed. Non-adjustable air springs are primarily used for the purposes mentioned above, while adjustable air springs enable extended functions. One such extended function of an adjustable air suspension system is, for example, level control, in which the adjustment of a vehicle's ground clearance, for example, depending on the vehicle load, is kept constant.

[0003] Adjustable or variable air suspension systems feature an air suspension control system to implement additional functions, for example, which varies the gas mass in a spring element depending on sensors. Manual intervention with control signals is also known, as is the case with an automatic lowering system in a bus to facilitate passenger boarding and disembarkation.

[0004] In this case, an adjustable air spring system is to be considered in which a variable gas mass is used in air springs, in particular for the suspension of a vehicle.

[0005] As already mentioned above, such air spring systems typically have an air spring control system connected to a multitude of sensors and actuators for controlling the gas mass of the air springs. An air spring control system, which is usually part of a control unit with additional functions, is thus fed a multitude of measured values. Furthermore, the control unit must send a multitude of commands to control the actuators. Furthermore, the control unit must have a fast response time to generate appropriate control signals from the multitude of measured values.

[0006] A control unit that includes the air suspension control system is therefore subject to highly complex development effort and requires very high computing power. In particular, if the control unit fails, the entire air suspension system is rendered inoperative.

[0007] DE 11 2015 000259 T5 discloses an air suspension control system for controlling air suspension modules for springing a driver's cab of a vehicle. The air suspension control system comprises electrical air suspension control units, each air suspension control unit configured to control an air suspension module. A control module applies an air suspension control algorithm to define a desired air suspension performance. The air suspension control units and the control module are connected to a communication bus. A PID controller is configured to determine specific control parameters for application by the air suspension control units to the air suspension modules.

[0008] DE 102 45 815 A1 discloses an air suspension system for a vehicle. A compressed air control device is assigned to a front axle of the vehicle. The compressed air control device has an electronic control unit that is functionally connected to a 3 / 2-way valve and controls the 3 / 2-way valve. The electronic control unit is functionally connected to an operating unit via a powerline communication connection. The operating unit also serves as an interface between the powerline communication connection and a CAN bus of the vehicle.

[0009] DE 10 2014 101 084 A1 discloses a vehicle control system with a first electronic control unit that controls level sensors arranged on the axles of a vehicle such that a target value for a vehicle level is set by means of the level sensors. The target value of the level or a target value for an air pressure in an air spring bellows, which is controlled by the first electronic control unit, is specified to the first electronic control unit by a second electronic control unit in which routines of a brake pressure control system (EBS) and / or a brake slip control system (ABS) and / or a traction control system (ASR) and / or a vehicle dynamics control system (ESP) and / or a driver assistance system (ACC) are implemented.

[0010] EP 2 765 325 A1 discloses an air spring arrangement with a pneumatic valve driven by a stepper motor.

[0011] The object of the present invention is therefore to find an air spring system or air spring control system that is less complex and, for example, can be easily adapted to different vehicles or vehicle types. In any case, an air spring system or air spring control system that is advantageous compared to the prior art is to be found.

[0012] The invention relates to an air suspension control system for a commercial vehicle or a passenger car. The air suspension control system can also be called Electronic Controlled Air Suspension (ECAS). A commercial vehicle is, for example, a bus or a truck, but also includes a tractor-trailer combination.

[0013] The air spring control system according to the invention has a main control unit for operating the air spring control system. Furthermore, the air spring control system comprises at least two secondary control units. The secondary control units are each connected to the main control unit via a data connection. The data connection is either a shared or a separate data connection. This means that, with a shared data connection, the main control unit and both secondary control units are connected to a common data line, for example, consisting of two or more electrical conductors. If the data connection is configured as a separate data connection, this means that a separate data line is provided between the main control unit and each of the at least two secondary control units.

[0014] Each of the secondary control units has at least one output. The output serves to control at least one actuator that can be connected to the output. An actuator is, for example, an adjustment drive for a valve. Preferably, the actuator is an electrical solenoid valve component, which is, for example, a pneumatic or hydraulic valve component. The valve is particularly preferably a solenoid valve.

[0015] The secondary control units each contain at least one function for generating control signals at the output.

[0016] This means that the secondary control unit is preferably configured to control an output depending on a stored function stored in the secondary control unit.

[0017] The main control unit has means for calling and / or parameterizing the stored function. This is done by sending commands via the data connection from the main control unit to the secondary control unit whose function is to be called and / or parameterized.

[0018] Calling is to be understood here in particular as meaning that by calling a function, the secondary control unit is put into operation with this function and control signals are then generated at the output of the secondary control unit depending on the called function.

[0019] The term "function" here is not limited to a mathematical function in the sense of mapping a relationship between two sets. Rather, the term "function" should also be understood in the sense of its use in computer science. Accordingly, a function is a program construct that generates output values ​​without input values, or preferably with input values, for example, including input data and / or sensor data and / or parameterization.

[0020] Compared to conventional air spring control systems, which only have a single control unit that controls all actuators via their outputs, the control unit according to the invention has a modular design. The main control unit of the present invention essentially serves only to call up and / or parameterize the functions stored in the secondary control units.

[0021] A stored function could, for example, be a leveling function. Accordingly, the leveling function is called from the main control unit in the secondary control units as needed. For example, the main control unit can specify a desired ground clearance to be maintained constant as a parameter for the secondary control units. When the leveling function is called, valves in the secondary control units are then controlled in such a way that gas masses are directed into or out of the air springs in such a way as to maintain the specified ground clearance essentially constant.

[0022] If – to continue with the above example of the level control function – all secondary control units are to perform level control of one or more air springs, the main control unit can, for example, call the corresponding function or level control function in a single broadcast to all secondary control units. The main control unit does not need to interact further after calling the level control function.

[0023] This allows for a modular design of the air suspension control system, so that, for example, the same main control unit can always be used in the vehicle, regardless of the number of required secondary control units. Furthermore, data traffic on the data connection(s) can be significantly reduced or even completely eliminated after a function is called. The bandwidth of a data connection can thus be used for other transmissions.

[0024] In addition, the main control unit requires less computing power, as the functions are shifted to the secondary control units. A main control unit can thus perform other functions with the same computing power and, with regard to air suspension, can essentially be limited to higher-level control functions of the air suspension without having to perform time-critical control of the air suspension.

[0025] The secondary control units each have at least one input for acquiring sensor data. At least one sensor can be connected to the input. Furthermore, the secondary control units are each configured to generate control signals at the output depending on the sensor signals. Preferably, the secondary control unit is configured to generate control signals at the output, thus depending on the sensor signals and a function, in particular a stored, called function. Accordingly, values ​​of sensor data or values ​​derived therefrom are particularly preferably linked to a function executed in the secondary control unit in such a way that specific control signals are generated at the output.

[0026] In the example of the above-mentioned level control function, the current state of the prevailing ground clearance is fed to the auxiliary control unit as sensor data, so that an actuator can be controlled at the output to change or maintain the ground clearance. Complete control of a single, closed-loop system is thus possible with a auxiliary control unit if, for example, sensor data is considered as an actual value, the function has setpoint values, and control is performed via the output by controlling one or more actuators.

[0027] Individual, self-contained control systems comprising a secondary control unit can therefore independently and autonomously perform control functions separately from the main control unit after being activated by calling a function from the main control unit. The parameterization of the function mentioned above can, for example, represent a setpoint value for the function.

[0028] According to a further embodiment, the secondary control unit is configured to detect signals from at least one sensor, which includes a distance, height, and / or pressure sensor, with its input. In particular, for adjusting an actuator to vary or maintain a constant ground clearance with a secondary control unit, complete controllability by the secondary control unit is possible without further specifications from a main control unit by detecting distances, for example, between axles and wheel installation or between the distance of the vehicle's underbody and the ground, and / or by recording pressure measurements with a pressure sensor to evaluate a loading situation.

[0029] The secondary control unit is also configured to transmit sensor signals to the main control unit via the data connection. According to the invention, this is the case when a command is sent from the main control unit via the data connection and this command is received by the secondary control unit, for example, to read a sensor signal. In this way, the main control unit is used as a monitoring authority for correct functioning, even if control using sensors and actuators is actually carried out within the secondary control unit.

[0030] The main control unit is designed in such a way that it checks the correct and / or error-free function of the secondary control unit at intervals or triggered by a query from a higher-level instance based on sensor signals or other data from a secondary control unit.

[0031] According to the invention, the secondary control units are each configured to receive and interpret at least one predefined set of commands from the main control unit. Accordingly, the main control unit is configured with a fixed set of commands, with the interpretation of a command depending on the configuration of a function stored in the secondary control unit.

[0032] Individual adaptation of the air suspension control system can therefore be achieved simply by adapting the auxiliary control units. This means that, regardless of the individual vehicle design or the requirements of the vehicle in which an air suspension control system is to be used, the main control unit can always be identical. The same main control unit can therefore be used for a variety of different individual vehicles, for example, allowing for a more cost-effective implementation of the main control unit due to the large volumes required.

[0033] According to a further embodiment, the data connection is a bus connection. In particular, the bus connection is a CAN bus connection. A data connection designed as a bus connection, in particular as a CAN bus connection, is particularly advantageous for connecting the main control unit to the secondary control units, since this is already planned or present in today's vehicles. Thus, a main control unit can, for example, be arranged in the area of ​​the vehicle in which other higher-level control units are present, while the secondary control units can, for example, be arranged in the area near one or more actuators to be controlled. An already existing bus connection can then be used to implement communication between the secondary control units and the main control unit without the need to provide additional cable connections.

[0034] The invention also relates to an air suspension system comprising an air suspension control system according to one of the aforementioned embodiments. The air suspension system comprises an actuator for connection to an air suspension control system. The actuator is a valve drive and is configured to continuously adjust the flow rate of the valve passage of a valve connected to the valve drive for actuation or in more than three stages. This allows, for example, the speed of the variation of ground clearance to be adjusted. For example, the ground clearance can thus be changed at a lower speed while driving than when stationary, for example, in order to avoid an abrupt influence on the driving dynamics while driving.

[0035] Particularly in buses, this offers the advantage of allowing particularly quick adjustment of the ground clearance when the bus is stationary, allowing passengers to board and disembark. This is preferably achieved using the same valve that supports level control while the bus is moving, eliminating the need for multiple valves connected in parallel.

[0036] According to one embodiment, the valve drive comprises a stepper motor. A stepper motor can be easily adjusted to a variety of stages, allowing a variety of valve actuation stages depending on the step size of the stepper motor used. According to one embodiment, the actuator of the air spring system is designed to be connected to an output of a secondary control unit.

[0037] Furthermore, the invention relates to a vehicle, which is in particular a commercial vehicle or a passenger car and comprises an air spring control system according to one of the aforementioned embodiments and / or an air spring system according to one of the aforementioned embodiments.

[0038] According to one embodiment, the vehicle has multiple axles, wherein the air suspension control system comprises a secondary control unit per axle.

[0039] This enables an individual design of the air suspension control system depending on the number of axles.

[0040] Furthermore, the invention relates to a method for operating a vehicle with an air spring control system according to one of the aforementioned embodiments and / or an air spring system according to one of the aforementioned embodiments.

[0041] According to one embodiment of the method, control signals are generated at the output of at least one secondary control unit for operation as a function of functions stored in the secondary control unit and as a function of commands sent from a main control unit to the secondary control unit. Preferably, the control signals are additionally generated as a function of sensor signals from at least one sensor connected to the secondary control unit.

[0042] Further embodiments are shown in the figures, which show Fig. 1 : an air suspension control system and Fig. 2 : an air spring system according to an embodiment.

[0043] Fig. 1 shows an air spring control system 10 according to one of the aforementioned embodiments. The air spring control system 10 comprises a main control unit 12 and two secondary control units 14. The secondary control units 14 are each connected to the main control unit 12 via a data connection 16. Accordingly, the data connection 16 serves to transmit data from the main control unit 12 to the secondary control units 14 and from the secondary control units 14 to the main control unit 12.

[0044] In Fig. 1 the data connection 16 is represented by two individual strands, each of which comprises, for example, several electrical or optical lines.

[0045] According to another embodiment of the invention, not shown here, these two strands are not separated and there is a common data connection between the main control unit 12 and both secondary control units 14. This common data connection is preferably a bus system.

[0046] Each of the secondary control units 14 has two outputs 18, to each of which an actuator 20 is electrically connected. Furthermore, each of the secondary control units comprises two inputs 22, to each of which a sensor 24 is connected.

[0047] The air suspension control system is designed in such a way that functions in the secondary control units 18 are first called up and parameterized via the main control unit 12 using the data connection 16. Based on these functions, output signals are then generated at the outputs 18 for the actuators 20 depending on the function and sensor data, which are provided to the inputs 22 of the secondary control units 14 via the sensors 24. Functions include, for example, raising or lowering a vehicle with the air suspension control system, tilting the vehicle, or leveling during or after loading a vehicle.

[0048] Fig. 2shows an air suspension system 26 that can be controlled by the air suspension control system 10. The air suspension system includes an actuator 20 configured as a valve drive 28. The valve drive 28 is connected to an output 18 of the secondary control unit 14. The valve drive 28 is part of a valve 30 and includes a stepper motor 32 for actuating a valve passage 34 of the valve 30 continuously or in more than three steps.

[0049] The valve 30 is thus controlled by the secondary control unit 14 in such a way that a desired valve passage 34 level is provided for the valve drive 28. The valve drive 28 then adjusts the valve passage 34 according to the desired level with the aid of the stepper motor 32. This varies the flow rate through the valve 30 in such a way that, for example, a slow or rapid lifting of a vehicle is possible by filling a cylinder with gas, in particular air, depending on the flow rate. List of reference symbols (part of the description)

[0050] 10Air suspension control system 12Main control unit 14Sub-control unit 16Data connection 18Output for connecting an actuator 20Actuator 22Input for collecting sensor data 24Sensor 26Air suspension system 28Valve actuator 30Valve 32Stepper motor 34Valve passage

Claims

1. Air suspension control system (10) for a commercial vehicle, such as a truck, or for a passenger car, the air suspension control system (10) comprising a main control unit (12) for operating the air suspension control system (10) and at least two secondary control units (14), which are each connected to the main control unit (12) via a separate or shared data connection (16), the secondary control units (14) each having at least one output (18) for controlling at least one actuator (20) which can be connected to the output (18), at least one function for generating control signals at the output (18) being stored in each of the secondary control units (14), and the main control unit (12) having means for retrieving and / or parameterizing the stored functions by sending commands via the data connection (16), the secondary control units (14) each having at least one input (22) for acquiring sensor data from at least one sensor (24) which can be connected to the input (22), and the secondary control units (14) each having means for generating control signals at the output (18) according to the sensor signals at the input, characterized in that - the secondary control units (14) are each designed to receive and interpret at least one predefined fixed set of commands from the main control unit (12) and the secondary control units (14) have means for each storing therein a predefined fixed set of functions, one of the commands being interpreted according to the design of a function stored in the secondary control unit, and the secondary control units (14) each have means for transmitting sensor signals to the main control unit (12), the secondary control units (14) each having means for transmitting the sensor signals to the main control unit (12) after receiving a command sent by the main control unit (12) and received via the data connection (16), the main control unit (12) having means for checking, at intervals or triggered by a query from a higher-level instance and on the basis of the sensor signals or other data of one of the secondary control units (14), the correct and / or error-free functioning of this secondary control unit, and - even if control using sensors (24) and actuators (20) can be carried out within the secondary control unit (14), the main control unit (12) can be used as a control instance for the correct and / or error-free functioning of this secondary control unit (14).

2. Air suspension control system (10) according to claim 1, wherein the secondary control units (14) each have means for acquiring, by the input (22), signals from at least one sensor (24), which includes a distance, height and / or pressure sensor.

3. Air suspension control system (10) according to claim 1 or 2, wherein - the main control unit (12) is substantially only designed to retrieve and / or parameterize the functions stored in the secondary control units.

4. Air suspension control system (10) according to any of the preceding claims, wherein - complete control of a single closed system is possible with one of the secondary control units (14).

5. Air suspension control system (10) according to any of the preceding claims, wherein the actuator (20) which can be connected to the output (18) is an adjustment drive (28) for a valve (30), the valve (30) being in particular an electrical magnetic valve component, in particular a pneumatic or hydraulic valve component, such as a solenoid valve.

6. Air suspension control system (10) according to any of the preceding claims, wherein the data connection (16) is a bus connection, in particular a CAN bus connection.

7. Air suspension device comprising an air suspension control system (10) according to any of the preceding claims and comprising an air suspension system (26) which can be controlled by means of the air suspension control system (10), wherein the air suspension system has an actuator (20) for connection to the air suspension control system (10), which actuator is connected to the air suspension control system (1), and the actuator (20) is a valve drive (28), wherein the valve drive (28) is designed to actuate, continuously or in more than three stages, the volumetric flow through the valve opening (34) of a valve (30) connected to the valve drive for actuation.

8. Air suspension device according to claim 7, wherein the valve drive (28) comprises a stepper motor (32).

9. Air suspension device according to claim 7 or 8, wherein the actuator (20) is designed to be connected to at least one output (18) of one of the secondary control units (14) and is connected to the output (18).

10. Vehicle, in particular a commercial vehicle, such as a truck, or a passenger car, comprising an air suspension control system (10) according to any of claims 1 to 6 and / or an air suspension device according to any of claims 7 to 9.

11. Vehicle according to claim 10, wherein the vehicle has a plurality of axles and the air suspension system (10) comprises one secondary control unit (14) per axle.

12. Method for operating a vehicle according to claim 10 or 11 or a vehicle comprising an air suspension device according to any of claims 7 to 9 or an air suspension control system (10) according to any of claims 1 to 6.

13. Method according to claim 12, wherein, for operation, control signals are generated at the output (18) of at least one secondary control unit (14) according to functions stored in the secondary control unit (14) and according to commands sent from a main control unit (12) to the secondary control unit (12).