Compressed air supply system comprising a compressed air control unit and a compressor, and method for operating the compressed air supply system

Abstract

The invention relates to a compressed air supply system (30) comprising compressed air consumers (34), compressed air lines, valves (44, 46, 48, 50, 52, 54), a compressed air control unit (56) for controlling the valves, a compressor or compactor (12) having an electric motor (14) as the drive, and a pressure accumulator (36). The compressed air consumers (34) are pneumatically connected or connectable to the compressor or compactor (12) and / or the pressure accumulator (36) in such a way that the compressed air supply system (30) can be operated either in an open operating mode or in a closed operating mode. The compressed air control unit (56) is designed, in response to a request signal, to predict an output pressure at the output of the compressor or compactor (12) at the time T when a corresponding state of the pressure consumer is reached. Depending on the predicted output pressure, the compressed air control unit (56) either activates the open or closed operating mode, or provides a predefined target speed for controlling the rotational speed of the electric motor, or, when activated, provides an operating mode.

Description

[0001] Compressed air supply system with a compressed air control system and a compressor, method for operating the compressed air supply system

[0002] The invention relates to a compressed air supply system for a vehicle. The invention also relates to a method for operating such a compressed air supply system.

[0003] In motor vehicles, compressed air supply systems can, for example, supply compressed air to an air suspension system as a compressed air consumer and / or a pneumatic braking system as a compressed air consumer. In order to provide compressed air at a sufficiently high pressure for such compressed air consumers, compressors are required to generate compressed air. Such compressors are typically driven by electric motors that consume a motor current during operation. Compressors and compressors are used synonymously in this description and refer to units that compress air.

[0004] In addition to the compressed air consumer(s), the compressor and its drive, key components of a compressed air supply system are electrically controllable valves that can be controlled by a compressed air controller – i.e., opened or closed. In this way, compressed air can be supplied to or released from the individual compressed air consumers in a compressed air supply system in a targeted manner. Depending on which compressed air consumers need to be supplied with compressed air in a given operating situation, the compression work to be performed by the compressor can vary greatly. As explained in more detail below, the torque delivered by the drive of the compressor depends on the compressed air pressure required for the respective operating situation.If the compressor or condenser is driven by an electric motor, its current consumption depends on the torque to be delivered (i.e. the operating load of the drive) at the supply voltage typically provided by the vehicle's electrical system.

[0005] Preferably, the compressor and the associated drive, in particular the associated electric motor, are combined into a single structural unit—hereinafter referred to as the compressor module. Compressor modules are used, for example, for compressed air supply systems in motor vehicles.

[0006] Brushless DC motors (BLDC motors: Brushless Direct Current motors) are preferably used as electric motors for driving compressors or condensers. A brushless DC motor, as a so-called internal rotor, typically has a stator equipped with electromagnetic coils, a rotor equipped with permanent magnets, and motor electronics. The motor electronics are configured as an electronic commutator in such a way that the motor electronics controls the power supply to the stator coils (hereinafter also referred to as stator coils) via power switches in such a way that the stator coils are periodically supplied with power in turn, creating a rotating magnetic field that, via magnetic forces, causes the synchronous rotation of the rotor equipped with permanent magnets.Such brushless DC motors with rotors fitted with permanent magnets are therefore also referred to as PMSM motors, where PMSM stands for permanent magnet synchronous motor. The abbreviation PMSM is typically used for sinusoidally commutated brushless electric motors, while the abbreviation BLDC (brushless direct current) is usually used for block-commutated brushless electric motors. With block commutation, the current supply to the (e.g. three or n times three) stator coils is digitally switched, i.e. either no current or the full current is supplied to the windings of the respective stator coil or stator coils of a phase. With sinusoidal commutation, each stator coil of the motor is supplied with a sine wave offset by 120°, resulting in a continuously rotating stator magnetic field of constant strength.For the conventional speed control of a brushless electric motor, the motor is equipped with rotor angle detection devices, which include electronic sensors such as Hall sensors for detecting the rotor position. This also allows the phase angle between the applied rotating field and the mechanical rotation of the rotor to be detected, and the phase angle of the rotating field can be adjusted accordingly. BLDC motors thus behave similarly to mechanically commutated DC motors. However, brushless DC motors are more efficient, subject to less wear, and can be better controlled in terms of speed than electric motors with a brush commutator.

[0007] In compressor modules for compressed air generation in a compressed air supply system, for example, for motor vehicles, the compressor generating the compressed air and its electric motor serving as its drive form a single structural unit. For both efficient and environmentally friendly operation, the design and operation of the electric motor – i.e., the brushless DC motor – pose a particular challenge. This includes, among other things, the compressor module's ability to provide sufficient compressed air to the respective compressed air supply system at all times, in all possible operating scenarios – even the rare ones. This means that a compressor module must provide sufficient compressed air for the compressed air supply system even under unfavorable conditions, which only occur rarely (first-case operating scenario).For this purpose, the drive, for example, the preferably brushless DC motor, must also be designed accordingly. For a given supply voltage of the DC motor, a higher mechanical load—i.e., a higher mechanical output power—inevitably leads to a higher current consumption of the DC motor. However, to protect a motor vehicle's electrical system, the maximum current consumption of a DC motor must be limited. WO 2020 / 225024 A1 discloses operating a BLDC motor for driving a compressor at a constant speed and reducing this speed depending on the load conditions (operating voltage and load (torque)) to avoid oversizing the motor.

[0008] The invention is based on the object of ensuring reliable and environmentally friendly operation of a compressor module in the simplest possible way.

[0009] To achieve this object, the invention provides a compressed air supply system according to claim 1. The compressed air supply system, in particular for a motor vehicle, has at least the following components: one or more compressed air consumers,

[0010] Compressed air lines, electrically controllable valves, a compressed air control system for controlling the electrically controllable valves, a compressor or condenser with an electric motor as drive, and preferably a pressure accumulator.

[0011] In a design variant with compressed air storage, the compressed air consumer(s) are or can be pneumatically connected to the compressor(s) and / or the pressure accumulator via the compressed air lines and the electrically controllable valves in such a way that the compressed air supply system can be operated either in an open operating mode or in a closed operating mode.

[0012] In closed operating mode, compressed air is supplied to the compressed air consumer(s) from the pressure accumulator, or compressed air from the compressed air consumer to the pressure accumulator. For this purpose, the electrically controlled valves are controlled by the compressed air control system according to the closed operating mode. In open operating mode, compressed air is supplied to the compressed air consumer(s) or the pressure accumulator from the ambient air via the compressor. For this purpose, the electrically controlled valves are controlled by the compressed air control system according to the open operating mode.

[0013] According to the invention, the compressed air control has signal inputs for at least: a request signal representing a request to the compressed air supply system, preferably a pressure accumulator pressure signal representing the value of the pressure in the pressure accumulator and a pressure sensor pressure signal representing the value of the pressure in the pressure sensor.

[0014] The compressed air control is designed to evaluate a current pressure sensor pressure signal (actual pressure signal PAbn from the pressure sensor) and preferably - if a pressure accumulator is present - a current pressure accumulator pressure signal (actual pressure signal PR) in relation to a desired state of the pressure sensor corresponding to the request signal SAnf, in response to a request signal, and to determine the desired state of the pressure sensor as a function of the desired state defined by the request signal SAnf and the desired state defined by the current pressure sensor pressure signal PAbn and, if applicable,to determine operating specifications for a target speed of the electric motor and / or for an operating mode (open or closed) of the compressed air supply system based on the current pressure accumulator pressure signal PR in such a way that a maximum motor current - i.e. a maximum current consumption of the electric motor - is not exceeded until the target state of the pressure sensor is reached and control signals corresponding to the specific operating specifications (e.g. the following n. S oii, S1, S2, ... Sn). For this purpose, the compressed air control can be designed to predict an output pressure at the outlet of the compressor or condenser and / or a motor current (IB) to be absorbed by the electric motor driving the compressor or condenser for the time T at which a state of the pressure sensor corresponding to the request signal is reached.

[0015] The control signals to be output by the compressed air control system can be, for example, a target speed for a speed controller of the electric motor or control signals for activating or deactivating valves of the compressed air supply system according to an open or closed operating mode.

[0016] Instead of first predicting an output pressure at the outlet of the compressor or condenser and / or a motor current (IB) ZU to be absorbed by the electric motor driving the compressor or condenser, the compressed air control can also be designed to derive the operating specifications and the corresponding control signals to be output directly from the input signals, for example by means of a corresponding characteristic map or a trained neural network.

[0017] The invention enables the prediction of the electric motor's power consumption for the operating state based on the input signals. The compressed air controller can select any one of a number of fixed speeds to ensure that the current consumption at the end of the operating cycle – i.e., until the target state is reached – is below the specified maximum value. The selection is made before the compressor starts, so that no speed change is required during the entire operating cycle until the target state defined by the request signal is reached. This has the major advantage that the speed is not changed during a operating cycle – i.e., from the compressor starting up until the target state is reached – which leads to a significantly better cycle and better acoustic behavior.Advantageous further developments of the invention, in particular of the power circuit arrangement, can be found in the subclaims and specify in detail advantageous possibilities for realizing the concept explained above within the scope of the task and with regard to further advantages.

[0018] The compressed air control system for determining the control signals n S oii, S1, S2, ... Sn by evaluating the input signals SAnf, PAbn, PR etc. can also be implemented as a self-learning variant that adjusts the specific power consumption (e.g. by measuring the current deviation during a run compared to the calculated value) during the lifetime of the compressor in order to ensure maximum performance while maintaining maximum permissible power consumption.

[0019] In a first embodiment, the compressed air control is connected to a target speed data memory in which several predetermined target speed values ​​are stored. In this embodiment, the compressed air control is designed, in response to a request signal, to predict an output pressure at the outlet of the compressor or condenser for time T at which a state of the pressure sensor corresponding to the request signal is reached, and, depending on the predicted output pressure, to select one of the predetermined target speed values ​​as the target speed value for the electric motor driving the compressor or condenser and to specify it for speed control of the DC motor such that the motor current to be absorbed by the electric motor driving the compressor or condenser does not exceed a maximum motor current at time T at which a state of the pressure sensor corresponding to the request signal is reached.

[0020] According to a second embodiment, the compressed air control is designed, depending on the predicted output pressure, either to control the electrically controllable valves according to the open operating mode of the compressed air supply system if the predicted output pressure is greater than or equal to a predetermined maximum value for the output pressure or the predicted motor current is greater than or equal to a predetermined maximum value for the motor current, or to control the electrically controllable valves according to the closed operating mode of the compressed air supply system if the predicted output pressure is less than the predetermined maximum value for the output pressure or the predicted motor current is less than the predetermined maximum value for the motor current.

[0021] What both design variants have in common is that the compressed air control determines operating specifications and corresponding control signals on the basis of the input signals describing the actual state and the target state defined by the request signal in such a way that exceeding a predetermined maximum motor current is avoided until the target state is reached, without a predetermined target speed for the electric motor having to be changed after the motor has been started.

[0022] To do this, the compressed air control system can first predict a maximum load that must be overcome to achieve the target state defined by the demand signal. The maximum load can, for example, be the maximum torque output by the electric motor driving the compressor or the maximum motor current absorbed by the electric motor driving the compressor.

[0023] The invention allows the electric motor to be designed for a constant speed as standard. According to the invention, exceeding the permissible current consumption (usually 35 A) of the compressor or condenser is prevented by predictively limiting its power consumption. This is done by either specifying a suitable speed that does not lead to the permissible current consumption being exceeded until a required state of the compressed air supply system is reached, or by activating the open operating mode from the outset if the prediction shows that the closed operating mode at the specified speed would lead to the permissible current consumption being exceeded. For this purpose, the current current consumption of the electric motor driving the compressor or condenser is determined. If the defined limit is exceeded, the closed operation of the compressed air supply system is terminated and the control in the open operating mode is completed.

[0024] Preferably, the compressed air control has a current signal input which is connected to a current sensor which is designed to detect a motor current IB ZU received by the electric motor driving the compressor or condenser and to output a signal representing this current to the compressed air control.

[0025] In a preferred embodiment, the compressed air collector is an air suspension system of a vehicle which has one or more bellows.

[0026] Preferably, the compressor or compressor are combined with the electric motor in the form of a compressor module to form a structural unit and are thus optimally coordinated with each other on the one hand and easy to integrate as a unit into a compressed air supply system on the other.

[0027] The electric motor is preferably a speed-controlled BLDC motor, which is given at least one target speed during operation.

[0028] Particularly with regard to releasing air from the compressed air collector, for example when lowering a vehicle with an air suspension system, it is advantageous if the compressed air control is designed to predictively determine a motor current to be absorbed by the electric motor based on an air pressure in the compressed air supply system and a request - in particular a "lowering" request - to the compressed air collector and to activate the open operating mode from the outset (i.e., to control the valves of the compressed air supply system accordingly) when the predictively determined motor current reaches or exceeds the predetermined maximum value for the motor current. This is because an otherwise necessary switch from closed to open operation during lowering would require the activation of several valves. This can be avoided with the predictive control according to the invention.

[0029] Preferably, the compressed air supply system comprises a pressure sensor arranged and configured to detect the air pressure prevailing in the compressed air supply system during operation and output a pressure signal representing this pressure to the compressed air control system. Based on the pressure signal and a demand signal, the compressed air control system can predictively determine the required motor current and compare it with the specified maximum motor current Imax to select a suitable operating mode.

[0030] Preferably, the compressed air supply system comprises a reservoir valve which is pneumatically arranged between the pressure accumulator and a pneumatic main pressure line.

[0031] It is also advantageous if the compressed air supply system has a boost valve that is pneumatically arranged between the pressure accumulator and a boost and return line.

[0032] A further aspect relates to a method of claim 12. The method serves to operate a compressed air supply system, in particular for a motor vehicle, with: one or more compressed air consumers,

[0033] Compressed air lines, electrically controllable valves, a compressed air control system for controlling the electrically controllable valves, a compressor or condenser with an electric motor as drive, and preferably a pressure accumulator.

[0034] According to the method, preferably a pressure accumulator pressure signal PR, which represents the pressure value in the pressure accumulator, and a pressure sensor pressure signal PAbn, which represents the pressure value in the pressure sensor, are recorded and evaluated. In response to a request signal, a current pressure sensor pressure signal and preferably a current pressure accumulator pressure signal are recorded and evaluated with respect to a desired state of the pressure sensor corresponding to the request signal. Depending on the desired state of the pressure sensor defined by the request signal, as well as the desired state defined by the current pressure sensor pressure signal and, if applicable,Based on the actual state of the compressed air supply system, characterized by the current accumulator pressure signal, operating specifications for a target speed of the electric motor and / or for an operating mode (open or closed) of the compressed air supply system are determined in such a way that a maximum motor current is not exceeded until the target state of the pressure sensor is reached. Control signals corresponding to the determined operating specifications are then output, and the compressed air supply system is controlled accordingly.

[0035] According to a first preferred method variant for operating a compressed air supply system by means of a compressed air control system which is connected to a target speed data memory in which a plurality of predetermined target speed values ​​are stored, in response to a request signal SAnf, an output pressure at the output of the compressor or condenser is predicted for the time T at which a state of the pressure sensor corresponding to the request signal is reached, and depending on the predicted output pressure, one of the predetermined target speed values ​​is selected as the target speed value for the electric motor driving the compressor or condenser and specified for a speed control of the electric motor in such a way that the motor current (IB) to be absorbed by the electric motor driving the compressor or condenser does not exceed a maximum motor current (temax) at the time T at which a state of the pressure sensor corresponding to the request signal is reached.

[0036] The predefined, fixed number of speeds is advantageous for improving acoustic performance. These speeds can be set to operating points that offer good acoustic and / or pneumatic performance. Predictive selection of a suitable target speed can also be used for compressed air supply systems that cannot operate in closed-loop mode because they lack a pressure accumulator.

[0037] According to a second preferred method variant for operating a compressed air supply system, in which the compressed air consumer(s) are or can be connected pneumatically to the compressor or condenser and / or the pressure accumulator via the compressed air lines and the electrically controllable valves in such a way that the compressed air supply system can be operated either in an open operating mode or in a closed operating mode, in response to a request signal, an output pressure at the output of the compressor or condenser and / or a motor current (IB) to be absorbed by the electric motor driving the compressor or condenser is predicted for the time T at which a state of the pressure consumer corresponding to the request signal is reached.

[0038] Depending on the predicted output pressure, either the electrically controllable valves are controlled according to the open operating mode of the compressed air supply system if the predicted output pressure is greater than or equal to a specified maximum value for the output pressure or the predicted motor current is greater than or equal to a specified maximum value for the motor current, or the electrically controllable valves are controlled according to the closed operating mode of the compressed air supply system if the predicted output pressure is less than the specified maximum value for the output pressure or the predicted motor current is less than the specified maximum value for the motor current.

[0039] The predictive selection of an operating mode can be combined with the predictive selection of a target speed.

[0040] Preferably, during operation, a voltage signal representing the value of the available supply voltage and / or an ambient pressure signal representing the air pressure in the environment and / or an air temperature signal representing the air temperature in the environment are additionally recorded and evaluated, and the output pressure at the output of the compressor or condenser and / or the motor current to be absorbed by the electric motor driving the compressor or condenser is predicted for the time T at which a state of the pressure sensor corresponding to the request signal is reached, depending on the voltage signal and / or the ambient pressure signal and / or the air temperature signal.

[0041] A method is preferred for operating a compressed air supply system which has a pressure sensor on the compressed air reservoir and a discharge valve, a return flow valve and a reservoir valve which is pneumatically connected to the pressure reservoir, in which the compressed air control, in the event that compressed air is to be discharged from the pressure sensor, activates the closed operating mode if the current reservoir pressure in the pressure reservoir is less than a reservoir pressure limit value, or activates the open operating mode if the current reservoir pressure in the pressure reservoir is greater than a reservoir pressure limit value.

[0042] A method is preferred for operating a compressed air supply system which has a pressure sensor on the compressed air reservoir and a discharge valve, a backflow valve and a reservoir valve which is pneumatically connected to the pressure reservoir, in which method the compressed air control, in the event that compressed air is to be discharged from the pressure consumer, calculates or estimates the expected reservoir pressure in advance on the basis of the available information about the reservoir pressure in the pressure reservoir and the volume of the pressure reservoir, the pressure in the compressed air consumer or one or more of its components and their volumes and height, and in the event that the calculated or estimated reservoir pressure exceeds a predetermined reservoir pressure limit value, the open operating mode is activated by switching off the compressor, closing (deactivating) the backflow valve and the reservoir valve and opening (activating) the discharge valve.

[0043] Also preferred is a method in which the compressed air control adaptively sets the storage pressure limit from a correlation of back pressure and current consumption learned during operation of the compressor module.

[0044] Preferably, the open operating mode is activated from a closed operating mode by deactivating the boost valve when compressed air is supplied to the pressure sensor. For this purpose, the compressed air supply system has a boost valve that is pneumatically connected to the pressure accumulator.

[0045] Preferably, the open operating mode is activated from a closed operating mode when compressed air is discharged from the pressure sensor by shutting off the compressor, closing (deactivating) the non-return valve and the reservoir valve, and opening (activating) the drain valve. For this purpose, the compressed air supply system comprises a drain valve, a non-return valve, and a reservoir valve that is pneumatically connected to the pressure accumulator.

[0046] Since the motor current is proportional to the drive torque required by the compressor (torque requirement), the selection of the open or closed operating mode and / or a suitable target speed can be achieved by predictive control solely based on the influencing variables that affect the compressor's torque requirement at a given speed and their foreseeable temporal development - for example, the backpressure that increases as the pressure accumulator fills. This - the selection of a suitable target speed and / or the predictive selection of the open or closed operating mode and the corresponding control of the compressed air supply system - is done in such a way that a selected operating specification ensures that a specified maximum motor current is not exceeded to achieve the target state of the pressure consumer.

[0047] According to a first advantageous variant, if compressed air is to be discharged from the pressure sensor, the compressed air control activates the closed operating mode if the pressure in the pressure accumulator is lower than a predefined or learned accumulator pressure limit, or the open operating mode if the pressure in the pressure accumulator is higher than a predefined or learned accumulator pressure limit. For this purpose, the compressed air supply system has a pressure sensor on the compressed air accumulator, as well as a drain valve, a backflow valve, and a reservoir valve pneumatically connected to the pressure accumulator.

[0048] According to a second advantageous variant, the compressed air control activates the open operating mode in the event that compressed air is to be discharged from the pressure sensor. The compressed air control calculates or estimates the expected accumulator pressure in advance based on the available information about the accumulator pressure and the volume of the accumulator, the pressure in the compressed air sensor or one or more of its components and their volumes and heights. The control activates the open operating mode if the calculated or estimated accumulator pressure exceeds a predetermined accumulator pressure limit. The compressor is then shut down, the reflux valve and the reservoir valve are closed (deactivated), and the discharge valve is opened (activated).

[0049] Preferably, the compressed air control adaptively sets the storage pressure limit from a correlation of back pressure and current consumption learned during operation of the compressor module.

[0050] Embodiments of the invention are now described below with reference to the drawing. These are not necessarily intended to represent the embodiments to scale; rather, where useful for explanation, the drawing is schematic and / or slightly distorted. With regard to additions to the teachings immediately apparent from the drawing, reference is made to the relevant prior art. It should be noted that numerous modifications and changes to the form and detail of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, in the drawing and in the claims can be essential for the further development of the invention, both individually and in any combination.Furthermore, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of ​​the invention is not limited to the exact form or detail of the preferred embodiment shown and described below, or limited to an object that would be limited compared to the object claimed in the claims. For specified dimensioning ranges, values ​​lying within the stated limits are also intended to be disclosed as limit values ​​and can be used and claimed as desired. Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiments and from the drawings, which show:

[0051] Fig. 1 is a circuit diagram of an example of a compressed air supply system including compressed air receiver in the form of air springs of a vehicle;

[0052] Fig. 2 Symbols for the valves shown in Fig. 1 to explain their operation;

[0053] Fig. 3 is a schematic block diagram of an electronic compressed air control system;

[0054] Fig. 4 a compressor module with compressor, electric motor and motor electronics;

[0055] Fig. 5 is a sketch illustrating the operation of a brushless electric motor;

[0056] Fig. 6 Diagrams illustrating the increase in current consumption of an electric motor with increasing back pressure

[0057] Fig. 7 is a symbolic representation of a compressor and a brushless electric motor with motor electronics driving it; and

[0058] Fig. 8 Diagrams illustrating the effect of the inventive predictive activation of the closed operating mode (Fig. 8a) or the open operating mode (Fig. 8b) on the current consumption of the electric motor driving the compressor.

[0059] The compressed air supply system 30 shown in Fig. 1 serves, for example, to supply compressed air to an air suspension system 32 comprising a plurality of air springs 34 of a vehicle. Instead of an air suspension system, other compressed air consumers, such as an air brake system, can also be pneumatically connected to the compressed air supply system 30.

[0060] The term "compressed air pickup" is used herein both for an entire air suspension system 32 or compressed air brake system and for individual bellows 34 of an air suspension system 32 or compressed air brakes of an air brake system, i.e. for any form of compressed air pickup.

[0061] Essential components of the compressed air supply system 30, in addition to the compressed air consumers 34, are a compressor or compressor 12 and its drive 14, as well as electrically controllable valves 44, 46, 48, 50, 52, and 54, which can be controlled—for example, opened or closed—by a compressed air control 56. In this way, compressed air can be specifically supplied to, or discharged from, the individual compressed air consumers 34. Depending on which of the compressed air consumers 34 needs to be supplied with compressed air in a given operating situation, the compression work to be performed by the compressor 12 can vary greatly. The compressed air control 56 is an electronic control system that outputs electrical control signals S1, S2, Sn to activate the individual electrically controllable valves, thus controlling the compressed air supply system 30.

[0062] To increase efficiency and ensure consistent availability, so-called "closed air spring systems" are used in car air spring systems. These are air spring systems that can be operated, for example, with a compressed air supply system 30, as shown in Figure 1, because the compressed air supply system 30 has components such as a pressure accumulator 36, which enables both an open operating mode and a closed operating mode. In contrast to "open systems" or an open operating mode, in the closed operating mode the air mass in the air springs is not reduced by venting the excess air into the environment; rather, this air is pumped into the pressure accumulator 36 using the compressor 12. The compressor 12 required for this is preferably designed for two-stage compression and is driven by an electric motor, preferably a BLDC motor 14.The closed operating mode by pumping occurs via the second stage 12.2, in the open operating mode the compressor 12 operates in two stages by pre-compression by means of the first stage 12.1 and final compression by means of the second stage 12.2.

[0063] In order to enable a closed operating mode, the compressed air supply system 30 in the illustrated embodiment has, in addition to the pressure accumulator 36, also a return valve 48, a reservoir valve 52, a separation valve 44 and a boost valve 54.

[0064] The return flow valve 48 is pneumatically arranged between the compressed air consumer 34 and the compressor 12 such that, when the return flow valve 48 is activated - i.e., open - compressed air can flow from the compressed air consumer 34 into a boost and return flow line 76 which leads to the compressor 12.

[0065] The reservoir valve 52 is pneumatically arranged between the pressure accumulator and a pneumatic main pressure line 40 such that, when the reservoir valve 52 is activated - i.e., open - compressed air can flow from the pressure accumulator 36 into the pneumatic main pressure line 40.

[0066] The boost valve 54 is pneumatically arranged between the pressure accumulator 36 and a boost and return line 76 such that, when the boost valve 54 is activated—i.e., open—compressed air can flow from the pressure accumulator 36 into the boost and return line 76, which leads to the compressor 12. This allows the compressor 12 to recompress the compressed air extracted from the pressure accumulator 36 during closed operation before it is supplied to the compressed air consumer 34.

[0067] The separation valve 44 is pneumatically arranged between the main pressure line 40 and the air suspension system 32 in such a way that, when the separation valve 32 is activated - i.e., open - compressed air can flow from the main pressure line 40 into the air suspension system 32.

[0068] Due to the required compressor power or the delivery capacity derived therefrom, the torques required to drive the compressor 12 in the closed operating mode differ significantly from the torque required for the open operating mode.

[0069] As already indicated, the compressed air supply system 30 shown in Fig. 1 can be operated in an open operating mode or in a closed operating mode. In the open operating mode, outside air is drawn in from the environment and compressed (see the dashed arrow in Fig. 1), and in the closed operating mode, air is drawn from a pressure vessel 36—also referred to here as a reservoir—and compressed (see the dotted arrow in Fig. 1).

[0070] While the current consumption of the compressor drive—that is, the current consumption of electric motor 14—(which is proportional to the required torque) is below approximately 25A in open mode, it can rise to 50A and more in closed mode. The closed mode is therefore the mode with the highest torque and current requirements. Both modes must be available in a vehicle.

[0071] The electronic compressed air control

[0072] The compressed air control 56 outputs the control signals S1, S2, ... Sn to activate the electrically controllable valves - and thus to activate the open or closed operating mode - and a control signal Ss for the target speed n S oii of the electric motor 14.

[0073] In addition, the compressed air control 56 receives input signals representing the pressure value in the pressure accumulator 36 as the accumulator pressure signal PR and the pressure sensor pressure signal PAbn representing the pressure value in the compressed air sensor 34, as well as a request signal (SAnf) defining a desired state of the compressed air sensor 32—e.g., raised or lowered—or of the compressed air supply system. Other possible input signals of the compressed air control 56 are a voltage signal representing the value of the available supply voltage Uv, an ambient pressure signal representing the ambient air pressure, and / or an air temperature signal representing the ambient air temperature.

[0074] The pressure sensor pressure signal PAbn can represent the pressure in the entire pressure sensor 32, e.g. the air spring system 32, or in the form of a vector with several components also the pressures in the individual bellows 34 of the air spring system 32.

[0075] The compressed air control 56 is connected to a target speed data memory 56.1, in which several predetermined target speed values ​​are stored. Furthermore, the compressed air control 56 has an evaluation unit 56.3, which processes the input signals SAnf, PR, PAbn, etc., and generates and outputs control signals n. S oii, S1, S2 etc. is designed for the compressed air supply system 30. In particular, the evaluation unit 56.3 forms the control signals after receiving a request signal SAnf such that the desired state of the compressed air consumer 32 or the compressed air supply system 30 defined by the request signal SAnf while maintaining an initially set desired speed nS0 n can be achieved without exceeding a predetermined maximum motor current Iß max. This is achieved by a predictive control, which can, for example, predict a motor current Iß pra or a pressure at the outlet of the compressor 12, or the control signals n required to achieve the target state Soii, S1, S2, etc., based on a characteristic map or a trained neural network 56.2 from the input signals SAnf, PR, PAbn, etc. For this purpose, the initial or actual state, which is represented by the input signals PR, PAbn, etc., is taken into account.In particular, the compressed air control 56 can be designed to predict, in response to a request signal SAnf, an output pressure at the output of the compressor or condenser 12 for the time T at which a state of the compressed air consumer corresponding to the request signal SAnf is reached, and to select one of the predetermined target speed values ​​as the target speed value for the electric motor 14 driving the compressor or condenser 12 as a function of the predicted output pressure and to output a corresponding control signal for a speed control of the electric motor 14 such that the motor current Ißpra to be absorbed by the electric motor 14 at the time T at which a state of the compressed air consumer corresponding to the request signal SAnf is reached, does not exceed a maximum motor current IB max.

[0076] Additionally or alternatively, the compressed air controller 56 can be configured to predict, in response to a request signal SAnf, an output pressure at the output of the compressor or condenser 12 and / or a motor current Ißpra to be absorbed by the electric motor 14 for the time T at which a state of the compressed air consumer corresponding to the request signal SAnf is reached, and depending on the predicted output pressure or the predicted motor current Ißpra, either to control the electrically controllable valves according to the open operating mode of the compressed air supply system 30 if the predicted output pressure is greater than or equal to a predetermined maximum value for the output pressure or the predicted motor current IB pra is greater than or equal to a predetermined maximum value for the motor current IB max, or to control the electrically controllable valves according to the closed operating mode of the compressed air supply system 30,if the predicted output pressure is less than the specified maximum value for the output pressure or the predicted motor current Iß pra is less than the specified maximum value for the motor current Ißmax. The following describes how compressed air can be supplied to the compressed air pickup 34, e.g., the air suspension system of a vehicle, in open or closed operating mode. This is necessary, for example, if the vehicle is to be lifted on one side or all sides. For this lifting, compressed air must be supplied to the bellows 34. Open operating mode,

[0077] Both raising and lowering of an air suspension system can take place in closed operating mode.

[0078] In the first open operating mode, e.g., for raising the air suspension system 12, compressed air is supplied from the compressor 12 via a pneumatic main pressure line 40 to the compressed air receiver 34—i.e., the air suspension system 32—to supply compressed air to the compressed air receiver 32. Within the air suspension system, the compressed air is distributed by means of individual pressure receiver valves 46—which, in the illustrated embodiment, are bellows valves 46 of spring bellows 34 of the air suspension system 32.

[0079] In the illustrated embodiment, the compressor 12 is designed as a two-stage unit, comprising a first compressor stage 12.1 and a second compressor stage 12.2. In open operating mode, the outside air is thus pre-compressed in two stages, first by the first compressor stage 12.1 and then post-compressed by the second compressor stage 12.2.

[0080] The compressed air provided by the compressor 12 in the open operating mode can also be fed to a pressure accumulator 36 instead of a compressed air consumer 34 in order to create the prerequisite for a closed operating mode.

[0081] For the compressed air supply in the open operating mode, a compressor such as compressor 12 and a pneumatic main pressure line 40 are required, which supplies the compressed air provided by compressor 12 to the compressed air receiver 34. Additional components such as an air dryer 38 or a separating or isolating valve 44 are optional.

[0082] In the second open operating mode, e.g., when lowering the air suspension system 12, the drain valve is opened. This opening of the drain valve 50 causes the pneumatically controlled 3 / 2-way valve 70 to move into the working position, where venting occurs. After the drain valve 50 opens, the pressure of the air to be vented acts as a control pressure, which acts on a control piston 74 of the pneumatically controlled 3 / 2-way valve 70 and moves the 3 / 2-way valve 70 into the working position against the force of its return spring 72. Throttle valves 80.1 and 80.2 as well as two check or one-way valves 42.1 and 42.2 effectively limit the control pressure for actuating the pneumatically controlled 3 / 2-way valve 70. Closed operating mode

[0083] Both raising and lowering can occur in an air spring system in the closed operating mode. In general, this means that a compressed air receiver 34 can be supplied with compressed air in a first closed operating mode and can discharge air in a second closed operating mode—also referred to as reflow mode.

[0084] For the closed operating mode, a pressure accumulator 36, designed as a compressed air tank, for example, a reservoir valve 52, an optional boost valve 54, a likewise optional separation valve 44, and a likewise optional check valve 48, as well as corresponding compressed air lines, are also provided. The components not required for the open operating mode for the closed operating mode - namely the pressure accumulator 36, the reservoir valve 52, the optional boost valve 54, and the check valve 48 - are shown in Fig. 1 within the dashed border 82. In the first closed operating mode, e.g. for raising an air suspension system, air is pumped from the pressure accumulator 36 to the compressed air receiver 34 and into its bellows 34 by means of the compressor 12 and its second compressor stage 12.2. For this purpose, the compressor 12, the boost valve 54, and the separation valve 44 are activated, and the bellows valves 46 are opened.In this way, a vehicle can be lifted by means of the air suspension system 32 in the closed operating mode of the compressed air supply system 30 ("boost"). Since the air in the pressure vessel 36 already has a higher static pressure than the ambient air, the air is recompressed in the closed operating mode only by means of the second stage 12.2 of the compressor 12, and the first stage 12.1 of the compressor 12 is pneumatically ineffective in this case.

[0085] Just as in the open operating mode, in the closed operating mode the compressed air is fed via the air dryer 38 to the pneumatic main pressure line 40 and through the one-way or check valve 42.2 and is thus made available for delivery to a compressed air consumer 34.

[0086] In the second closed operating mode, for example, when lowering an air suspension system, air is pumped from the bellows 34 into the pressure accumulator 36. In this case, the compressor 12 is activated, and both the check valve 48 and the reservoir valve 52 are open, i.e., activated. Air is then pumped from the bellows 36 through the check valve 48 by means of the second stage 12.2 of the compressor 12, and through the reservoir valve 52 into the pressure accumulator 36.

[0087] Distribution of compressed air within the compressed air receiver

[0088] The compressed air is delivered to the compressed air consumer(s) 34 or the pressure accumulator 36 and distributed within the compressed air consumer 32—in the example, between the air springs 34 of the air suspension system 32—by means of electrically controlled 2 / 2-way valves 46, one of which is also shown in Fig. 2a as 2 / 2-way valve 60. In their first (rest) position, which is effected by a return spring 62, the 2 / 2-way valves 46 act as one-way or check valves. In the controlled second (activated or working) position, the 2 / 2-way valves 46 are open. The electrically controlled 2 / 2-way valves 46 are connected to an electronic compressed air control unit 56, which can be identical to an electronic control unit for controlling the compressor module 10 and can control control magnets 64 of the 2 / 2-way valves 46.The 2 / 2-way valves 46 of the compressed air collector 32 – in the example case, the air spring system 32 – correspond to the 2 / 2-way valve 60 shown in Figure 2a.

[0089] Ventilation

[0090] Regardless of whether the compressed air supply system 30 is operated in open or closed mode, venting one or more components—such as the bellows 34—of the compressed air receiver 32 may be necessary. In the case of a vehicle with an air suspension system, one or more bellows 36 of the air suspension system must be vented if the vehicle is to be lowered on one side or all sides.

[0091] The venting of the compressed air collector 32 – e.g., when lowering the vehicle with an air suspension system – can also occur in open or closed operating mode. These variants for venting the compressed air collector 32 are explained in more detail below. In both cases, the venting of the compressed air collector 32 is involved – not the venting of the compressed air supply system 30 as a whole. Venting of the compressed air supply system 30 necessarily occurs in open operation, in which air from the compressed air supply system 30 is released into the environment. Venting in open operation

[0092] For venting in open operating mode, the compressed air supply system 30 in the example shown is designed as an indirectly venting compressed air supply system.

[0093] For this purpose, a drain valve 50, a pneumatically controlled 3 / 2-way valve 66, throttles 80.1 and 80.2 as well as a further check or one-way valve 42.1 are provided - see the corresponding border 84 around the components for indirect venting in Figure 1 .

[0094] Venting of the compressed air supply system 30 and one or more compressed air consumers 34 can be effected in the open operating mode by opening the drain valve 50, which is also designed as an electrically controlled 2 / 2-way valve. Opening the drain valve 50 causes the pneumatically controlled 3 / 2-way valve 66, as also shown in Fig. 2b (reference number 70 there), to be moved into the working position. The working position is the position in which venting occurs. After opening the drain valve 50, the pressure of the air to be vented acts as a control pressure, acting on a control piston 74, which moves the 3 / 2-way valve 66 into the working position against the force of its return spring 72. Restrictors 80.1 and 80.2 as well as two check or one-way valves 42.1 and 42.2 ensure a sensible limitation of the control pressure for controlling the pneumatically controlled 3 / 2-way valve 66.

[0095] Ventilation in closed operation

[0096] In the closed operating mode, the components of the compressed air collector 32 are vented into the pressure vessel 36.

[0097] During venting in closed operating mode, the air is pumped from the bellows 34 into the pressure accumulator 36 by means of the compressor 12 and its second compressor stage 12.2. For this purpose, the compressor 12 is activated, and the check valve 48 and the reservoir valve 52 are opened. This allows, for example, the air suspension system 32 to be lowered in closed operating mode. The first stage 12.1 of the compressor 12 is pneumatically ineffective in this case.

[0098] Summary of open / closed operating mode

[0099] An open operating mode occurs when the compressor 12 delivers air directly from the environment to the compressed air receiver 34, for example, the bellows of the air suspension; then the compressor 12 is activated, the separation valve 44 is activated, the bellows valves 46 are activated => "Lift" request, the compressor 12 fills the compressed air reservoir 36 from the environment; then the compressor 12 is activated, the reservoir valve 52 is activated => "Fill reservoir" request, the air from the compressed air receiver 34 (in the example: the bellows of the air suspension) is vented into the atmosphere (bellows valves activated, separation valve activated, drain valve activated) => "Lower" request to atmosphere

[0100] A closed operating mode exists when

[0101] The air is pumped from the bellows 34 into the pressure accumulator 36; then the compressor 12 is activated, the return valve 48 is activated, and the reservoir valve 52 is activated => "lower" request in closed operating mode ("reflow"). The first stage 12.1 of the compressor 12 is pneumatically ineffective in this case.

[0102] The air is pumped from the pressure accumulator 36 into the bellows 34; then the compressor 12 is activated, the boost valve 54 is activated, the separation valve 44 is activated, and the bellows valves 46 are activated => "lift" request in closed operating mode ("boost"). The first stage 12.1 of the compressor 12 is pneumatically ineffective in this case.

[0103] The compressor module

[0104] The compressor module 10 shown in Fig. 4 is intended for use in the compressed air supply system 30, as shown by way of example in Fig. 1 using a circuit diagram. The compressor module 10 is designed as a structural unit comprising the compressor 12, the electric motor 14, and the motor electronics (16, see Fig. 7; not shown in Fig. 4; typically flanged directly to the electric motor 14), as well as other components such as the air dryer 18 and the air distributor 20, etc.

[0105] Fig. 5 shows a sketch of the stator and rotor of a brushless DC motor. The sketched brushless DC motor 14, as a so-called internal rotor, typically has a stator 14.1 equipped with electromagnetic coils, a rotor 14.2 equipped with permanent magnets, and motor electronics 16 (see Fig. 6). The motor electronics 16 are configured as an electronic commutator such that the motor electronics 16 controls the current supply to the stator coils 14.3 of the stator 14.1 via power switches and terminals A, B, and C such that the stator coils 14.3 are periodically supplied with current in turn such that a rotating magnetic field is produced, which, via magnetic forces, causes a synchronous rotation of the rotor 14.2 equipped with permanent magnets.

[0106] For the known speed control of the brushless electric motor 14, the motor comprises means for detecting the rotor angle, e.g., a Hall sensor 14.4 for detecting the rotor position. This also allows a phase angle between the applied rotating field and the mechanical rotation of the rotor 14.2 to be detected, and the phase angle of the rotating field can be adjusted accordingly. Thus, the BLDC motor 14 behaves similarly to a mechanically commutated DC motor. However, as a brushless DC motor, it is more efficient, subject to less wear, and can be better speed-controlled than electric motors with a brush commutator.

[0107] To generate the rotating field by periodically energizing the stator coils 14.3 via terminals A, B, and C, the motor electronics 16 is provided, which functions as an electronic commutator; see Fig. 7.

[0108] The speed of the electric motor 14 is also controlled in a conventional manner via the motor electronics 16. For this purpose, a target speed is specified to the motor electronics 16. An electronic control unit 100 is provided to specify the target speed. It receives a value for the average motor current from the motor control unit 16 or is connected to a current sensor 58, 102 that detects the respective motor current consumed by the electric motor 14 during operation.

[0109] The current consumption of the electric motor 12 can be calculated by the motor controller 16 from the measured phase currents or measured directly using the current sensor 58 or 102. In the first case, three current sensors 102 are required, which are necessary anyway for operational reliability. In the second case, an additional current sensor 58 is required in the supply branch (see Figure 1). The variant without a separate current sensor 58 is therefore preferred.

[0110] Compared to an unregulated DC motor, regulated, brushless DC motors offer the advantage that their speed can be continuously adjusted without additional design effort. The commutation of a brushless DC motor is electronic, whereas a DC motor with a brush-commutator system is mechanically commutated. For acoustic reasons, air spring systems require a constant speed across the entire specified load range (voltage, back pressure and boost pressure, temperature, geodetic altitude), which favors the use of a regulated DC motor.

[0111] The disadvantage of the speed specification is that the requirement of n=const results in a motor current that increases with the torque, which in individual cases can even exceed the defined maximum limit of, for example, 35 A. To comply with the maximum permissible current consumption, the compressor would have to be designed such that the current consumption is never exceeded under worst-case operating conditions within the specified application cases. One such scenario could be a loaded vehicle, twisted over terrain.

[0112] It is proposed to design the motor for a constant speed as standard, and to reduce the required drive power of the compressor if the permissible current consumption (usually 35 A) is at risk of being exceeded. To this end, a compressor current consumption is predicted that is required to achieve a target state of the compressed air consumer. If the defined limit is at risk of being exceeded, a target speed and / or an operating mode (open or closed) is specified in advance, at which the maximum motor current is not exceeded until the target state of the compressed air consumer defined by the request signal SAnf is reached.

[0113] Typically, the pneumatic performance of a compressor for an air suspension system is designed for the most common operating point. For example, a flow rate of 130 l / min at 11 bar boost pressure and 11 bar back pressure is required. The maximum current consumption of 35 A, however, applies across all operating ranges (operating and ambient pressures, voltages).

[0114] To avoid over-engineering the compressor, it is designed for a current consumption of approximately 30 A at the specified operating point (taking into account device variations, service life influences, and slightly higher operating loads). Particularly in supercharged operation, a sharp increase in the required drive power or current beyond 35 A (current ~ torque) is evident with increasing backpressure.

[0115] In the example shown in Fig. 6, the current increases by more than 2 A per bar of back pressure. A remedy would be to design the compressor module 10 in such a way that no current is exceeded in the defined, rather rare worst-case operating points. However, this has the disadvantage that the compressor module 10 exhibits a correspondingly reduced, non-specified performance in the frequently encountered operating ranges. A required flow rate of, for example, 130 l / min at 11 bar of inlet pressure and 11 bar of back pressure cannot be achieved in this case. The problem is exacerbated by device variation and service life influences. To avoid the high currents, the speed of the BLDC motor can be reduced. However, due to the proportionality of speed and current, this may result in an excessive, necessary speed reduction. For example, if the current consumption is to be reduced from 60 A to 35 A, the speed would have to be reduced to 58% of the original, from, for example, 2850 rpm.1 to under 1700min' 1 This significant reduction in speed can lead to undesirable effects on airborne and structure-borne noise.

[0116] By selecting the closed or open operating mode according to the invention, it is possible to prevent the specified maximum motor current from being exceeded. As can be seen from Figure 8a, the closed operating mode in the example shown can lead to the specified maximum motor current of 35 A being exceeded. However, if the open operating mode is activated from the outset, the specified maximum motor current is not exceeded; see Figure 8b.

[0117] One approach is to operate the BLDC motor at a constant speed and, to avoid oversizing the DC motor, reduce this speed under certain load conditions (operating voltage and load). With correct design and correct consideration of all nominal conditions, the maximum current of, for example, 35 A will not be exceeded. However, this requires that all current-influencing factors, such as component tolerances and operating temperatures, are considered in the form of worst-case assumptions, and that the resulting early switch to a lower speed (including the resulting performance reduction) is acceptable.

[0118] The aim was therefore not to design the compressor module for the rare worst-case conditions, but instead to provide a design according to the most common operating conditions in combination with a current limitation to ensure the specified current limits in conjunction with situationally maximum compressor performance.

[0119] The requirement for constant compressor speed leads to an increasing current consumption with increasing compressor drive torque (which is proportional to the required motor torque):

[0120] Formula: M x 2n xn = ix U x I with:

[0121] M = Compressor drive torque (is constant at constant pressure) n = Compressor speed (is determined according to conventional control strategy at

[0122] BLDC kept constant)

[0123] T = efficiency

[0124] U = supply voltage (specified, between 9 V and 16 V as required)

[0125] / = Motor current (usually limited to 35 A)

[0126] Measurements have shown that the motor current consumption of a supercharged compressor for use in car air suspension systems can increase by more than 2 A / bar of back pressure. Thus, when designed for the nominal point of 11 bar boost pressure and 11 bar back pressure at I = 30 A, a back pressure of only 13.5 bar would be permissible (which would then no longer cover the entire required operating range up to 18 bar, for example). Further reductions may result from: manufacturing-related device variations

[0127] Run-in effects

[0128] wear and tear

[0129] Ambient conditions Self-heating

[0130] The compressor module is advantageously designed so that it can perform the majority of the usage conditions at a single one of the specified target speeds.

[0131] Furthermore, the basic design of the compressor 12 and the associated electric motor 14 - i.e. the compressor module 10 - when using the invention should not be based on worst case tolerance levels, etc., but should also be analogous to the nominal values.

[0132] Advantages also arise in the event that the nominal diameters on the compressor pressure side are temporarily too small (e.g. when conveying into only one bellows 34) and an excessive back pressure builds up due to the high delivery volume flow, which in turn would lead to an excessively high motor current.

[0133] The application of the predictive control according to the invention is not limited to compressors driven by a BLDC DC motor (although the latter are preferred), but can also be extended to compressors with other DC motors.

[0134] In the example, the closed or open operating mode is activated as described below. For the predictive control to select a specified target speed and / or an open or closed operating mode, not (only) the motor current is measured, but also the pressure P on the pressure side of the compressor 12 or in the pressure accumulator 36. For this purpose, at least one PU converter is provided as a pressure sensor 78. This can be provided, for example, on the main pressure line 40 or the pressure accumulator 36, or at both locations, and also at other locations, depending on which pressure is to be detected, for example, for predictive control.

[0135] The accuracy of the prediction of the motor current IB, pra and thus the decision whether, for example, a sink occurs in the open or closed operating mode, can be improved over the following cases 1 to 3 by increasing the prediction complexity.

[0136] Since the motor current is proportional to the drive torque required by the compressor (torque requirement), the selection of the open operating mode or the closed operating mode and / or a suitable target speed can be achieved by predictive control solely based on the influencing variables that affect the compressor's torque requirement at a given speed and their foreseeable temporal development - for example, the backpressure that increases as the pressure accumulator fills. This - the selection of a suitable target speed and / or the predictive selection of the open or closed operating mode and the corresponding control of the compressed air supply system - is done in such a way that a selected operating specification ensures that a specified maximum motor current is not exceeded to achieve the target state of the compressed air consumer.

[0137] In the simplest case 1, the compressed air control is designed to activate either the closed operating mode or the open operating mode in response to a "lowering" request, depending solely on the current accumulator pressure (i.e., the air pressure in the accumulator). If the current accumulator pressure is too close to a maximum permissible accumulator pressure limit, so that not enough additional air mass can be stored in the accumulator to release sufficient air from the air receiver (e.g., to lower the vehicle far enough), then open operation is selected from the start to avoid switching the operating mode during lowering. For this purpose, the compressed air control is designed, among other things, as a pressure estimator.

[0138] In the second case (2), the compressed air control system is designed to calculate the resulting (i.e., expected) accumulator pressure in advance (air mass manager) based on the available information about accumulator pressure and volume, bellows pressure, bellows geometry, and height, as well as the requested control (e.g., raising or lowering), or to estimate it if the data is incomplete (air mass estimator). If the calculated or estimated accumulator pressure exceeds a specified or learned accumulator pressure limit, the lowering process is carried out from the outset by venting the bellows to atmosphere, i.e., in open operating mode. No switching occurs during the lowering process.

[0139] In a third, advantageous embodiment (Case 3), the compressed air control system is designed to adaptively determine a pressure limit from Case 2, but also from Case 1, based on a correlation between backpressure and current consumption learned during operation of the compressor module 10. Here, the unavoidable device tolerances are compensated for by performing the switchover on a compressor-specific basis in the form of self-calibration.

[0140] For this purpose, the compressed air control system may comprise a neural network 56.2 trained with training data sets containing input signals, control signals, and motor currents for various load conditions and demand signals. Reference symbol (part of the description)

[0141] 10 Compressor module

[0142] 12 Compressor

[0143] 12.1 first compressor stage

[0144] 12.2 second compressor stage

[0145] 14 Electric motor

[0146] 14.1 Stator

[0147] 14.2. Rotor

[0148] 14.3 Stator coil

[0149] 14.4. Hall sensor

[0150] 16 Engine electronics

[0151] 18 air dryers

[0152] 20 air distributors

[0153] 30 Compressed air supply system

[0154] 32 air suspension system

[0155] 34 compressed air receivers (e.g. bellows of the air springs)

[0156] 36 pressure accumulators

[0157] 38 air dryers

[0158] 40 Main pressure line

[0159] 42 One-way valve / check valve

[0160] 44 Separation valve (electrically controlled)

[0161] 46 Pressure sensor valve (bellows valve, electrically controlled)

[0162] 48 Check valve (electrically controlled)

[0163] 50 Drain valve (exhaust valve, electrically controlled)

[0164] 52 Reservoir valve (electrically controlled)

[0165] 54 Boost valve (electrically controlled)

[0166] 56 Compressed air control

[0167] 56.1 Target speed data memory for predefined target speeds

[0168] 56.2 neural network

[0169] 56.3 Evaluation unit

[0170] 58 Current sensor

[0171] 60 2 / 2-way valve 62 Return spring

[0172] 64 Control magnet

[0173] 66 3 / 2-way valve (pneumatically controlled) for venting

[0174] 70 3 / 2-way valve (electrically controlled)

[0175] 72 return spring

[0176] 74 control pistons

[0177] 76 Boost and return line

[0178] 78 Pressure sensor; PU converter

[0179] 80 Throttle

[0180] 82 components for closed operation

[0181] 84 components for indirect ventilation

[0182] 86 Compressor output

[0183] 90 Signal input for request signal

[0184] 92 Current signal input

[0185] 94 Pressure signal input for a signal representing the pressure in the pressure accumulator 36

[0186] 96 Pressure signal input for a signal representing the pressure of the compressed air in the main pressure line of the compressed air supply system

[0187] 98 Pressure signal input for a signal representing the pressure of the compressed air at the compressed air receiver

[0188] 100 electronic control unit n S oii Target speed

[0189] IB (average) motor current

[0190] Ißpra predicted motor current

[0191] SAnf request signal

[0192] SS control signal

[0193] PR accumulator pressure signal

[0194] PAbn pressure sensor pressure signal

[0195] PAUS pressure at the outlet of the compressor

[0196] PAUS pra predicted outlet pressure at the compressor

[0197] PAUS max predefined maximum outlet pressure on the compressor

[0198] Uv supply voltage

[0199] Suv signal representing the supply voltage Tu temperature of the ambient air

[0200] STU air temperature signal

[0201] Pu ambient air pressure

[0202] SPU ambient pressure signal

[0203] V Volume of a compressed air collector, especially an air spring h Height of a compressed air collector, especially an air spring

[0204] T Time at which a state of the pressure sensor corresponding to the request signal is reached

Claims

Patent claims 1 . Compressed air supply system (30), in particular for a motor vehicle, comprising: one or more compressed air consumers (34), compressed air lines (40), electrically controllable valves (44, 46, 48, 50, 52, 54), a compressed air control (56) for controlling the electrically controllable valves (44, 46, 48, 50, 52, 54), a compressor (12) with an electric motor (14) as a drive, and preferably a pressure accumulator (36), characterized in that the compressed air control (56) has signal inputs for at least: one request signal (SAnf), which represents a request to the compressed air supply system (30), preferably a pressure accumulator pressure signal (PR), which represents the value of the pressure in the pressure accumulator (36), and a compressed air consumer pressure signal (PAbn), which represents the value of the pressure in the compressed air consumer (32, 34), and is designed,in response to a request signal (SAnf), to evaluate a current pressure consumer pressure signal (PAbn) and preferably a current pressure accumulator pressure signal (PR) in relation to a target state of the compressed air consumer (32, 34) corresponding to the request signal (SAnf), depending on the target state of the compressed air consumer (32, 34) defined by the request signal (SAnf) and the actual state of the compressed air supply system (30) characterized by the current pressure consumer pressure signal (PAbn) and possibly the current pressure accumulator pressure signal (PR), operating specifications for a target speed (n, S oii) of the electric motor (14) and / or for an open operating mode or closed operating mode of the compressed air supply system (30) in such a way that up to to achieve the desired state of the compressed air consumer (32, 34), a predetermined maximum motor current (temax) is not exceeded and the operating specifications for a desired speed (n Soii) of the electric motor (14) and / or for an open operating mode or closed operating mode of the compressed air supply system (30) to output corresponding control signals (Ss).

2. Compressed air supply system (30) according to claim 1, the compressed air control (56) of which is connected to a target speed data memory (56.1) in which several predetermined target speed values ​​(n S oii) are stored, and which is designed, in response to a request signal (SAnf), to predict an output pressure (PAUS) at the output (86) of the compressor (12) for the time (T) at which a state of the pressure sensor (PAbn) corresponding to the request signal (SAnf) is reached, and, depending on the predicted output pressure (PAUS), to use one of the predetermined target speed values ​​(56.1) as the target speed value (n Soii) to select the electric motor (14) driving the compressor (12) and to specify it for a speed control of the electric motor (14) in such a way that the motor current (IB) to be absorbed by the electric motor (14) driving the compressor (12) does not exceed a maximum motor current (te max) at the time (T) at which a state of the pressure sensor (PAbn) corresponding to the request signal (SAnf) is reached.

3. Compressed air supply system (30) according to claim 1 or 2, in which the compressed air consumer (34) is / are pneumatically connected to the compressor (12) and / or the pressure accumulator (36) via the compressed air lines (40) and the electrically controllable valves (44, 46, 48, 50, 52, 54) in such a way that which are connected or connectable such that the compressed air supply system (30) can be operated either in an open operating mode or in a closed operating mode, characterized in that the compressed air control (56) is designed, in response to a request signal (SAnf), to predict an output pressure (PAus pra) at the output (86) of the compressor (12) and / or a motor current (Iß pra) to be received by the electric motor (14) driving the compressor (12) for the time (T) at which a state of the pressure sensor (32, 34) corresponding to the request signal (SAnf) is reached, and to control either the electrically controllable valves (44, 46, 48, 50, 52, 54) in accordance with the open operating mode of the compressed air supply system (30),if the predicted output pressure (PAUS) is greater than or equal to a predetermined maximum value for the output pressure (PAUS max) or the predicted motor current (Iß pra) is greater than or equal to a predetermined maximum value for the motor current (IB max), or to control the electrically controllable valves (44, 46, 48, 50, 52, 54) according to the closed operating mode of the compressed air supply system (30) if the predicted output pressure (PAUS) is less than the predetermined maximum value for the output pressure (PAUS) or the predicted motor current (Iß pra) is less than the predetermined maximum value for the motor current (IB max).

4. Compressed air supply system (30) according to at least one of claims 1 to 3, characterized in that the compressed air control (56) has further signal inputs for: a voltage signal (Suv) representing the value of the available supply voltage (Uv) and / or an ambient pressure signal (SPU) representing the air pressure in the environment (Pu) and / or an air temperature signal (STU) representing the air temperature in the environment (Tu), and is designed to predict the output pressure at the output (86) of the compressor (12) and / or the motor current (IB) to be absorbed by the electric motor (14) driving the compressor (12) for the time (T) at which a state of the pressure sensor (34) corresponding to the request signal (SAnf) is reached, depending on the voltage signal (Suv) and / or the ambient pressure signal (SPU) and / or the air temperature signal (STU).

5. Compressed air supply system (30) according to at least one of claims 1 to 4, characterized in that the compressed air consumer is an air spring system (32) with one or more air spring bellows (34).

6. Compressed air supply system (30) according to at least one of claims 1 to 5, characterized in that the compressor (12) is combined with the electric motor (14) in the form of a compressor module (10) to form a structural unit.

7. Compressed air supply system (30) according to at least one of claims 1 to 6, characterized in that the electric motor (14) is a speed-controlled BLDC motor and at least one target speed (n S oii) is specified.

8. Compressed air supply system (30) according to at least one of claims 1 to 7, characterized in that the compressed air supply system (30) has a pressure sensor (78) which is arranged and designed such that it detects an air pressure (PAni) prevailing in the compressed air supply system (30) during operation and outputs a pressure signal (SP A ) representing this to the compressed air control (56).

9. Compressed air supply system (30) according to at least one of claims 1 to 8, characterized in that the compressed air supply system (30) has a reservoir valve (52) which is arranged pneumatically between the pressure accumulator (36) and a pneumatic main pressure line (40).

10. Compressed air supply system (30) according to at least one of claims 1 to 9, characterized in that the compressed air supply system (30) has a boost valve (54) which is pneumatically arranged between the pressure accumulator (36) and a boost and return line (76).

11. Compressed air supply system (30) according to at least one of claims 1 to 10, characterized in that the compressed air control (56) is designed to be self-learning and preferably has a trained or trainable neural network (56.2).

12. Method for operating a compressed air supply system (30), in particular for a motor vehicle, with: one or more compressed air consumers (34), compressed air lines (40, 76), electrically controllable valves (44, 46, 48, 50, 52, 54), a compressed air control (56) for controlling the electrically controllable valves (44, 46, 48, 50, 52, 54), a compressor (12) with an electric motor (14) as a drive, and preferably a pressure accumulator (36), characterized in that during operation, a request signal (SAnf), which represents a request to the compressed air supply system (30), preferably a pressure accumulator pressure signal (SPR), which represents the value of the pressure (PR) in the pressure accumulator (36) and a pressure sensor pressure signal (SpAbn), which represents the value of the pressure (PAbn) in the compressed air sensor (34), is detected and evaluated, and in response to a request signal (SAnf), a current pressure sensor pressure signal (SpAbn) and preferably a current pressure accumulator pressure signal (SPR) are detected and evaluated in relation to a desired state of the pressure sensor (32, 34) corresponding to the request signal (SAnf), and depending on the desired state of the pressure sensor (32, 34) defined by the request signal (SAnf) and the actual state of the compressed air supply system (30) characterized by the current pressure sensor pressure signal (SpAbn) and possibly the current pressure accumulator pressure signal (SPR), operating specifications for a desired speed (n Soii) of the electric motor (14) and / or for an open operating mode or a closed operating mode of the compressed air supply system (30) is determined in such a way that a maximum motor current (IB) is not exceeded until the desired state of the pressure sensor (32, 34) is reached and control signals (Ss) corresponding to the determined operating specifications are output and the compressed air supply system (30) is controlled accordingly.

13. Method according to claim 12 for operating a compressed air supply system (30) by means of a compressed air control (56) which is connected to a target speed data memory (56.1) in which a plurality of predetermined target speed values ​​(n S oii) are stored, characterized in that several target speed values ​​(n S oii) are specified and are triggered by a request signal (SAnf) an output pressure (PAUS) at the output (86) of the compressor (12) is predicted for the time (T) at which a state of the pressure sensor (32, 34) predetermined by the request signal (SAnf) is reached, and depending on the predicted output pressure (PAUS pre) one of the predetermined target speed values ​​(n S oii) as target speed value (n S oii) is selected for the electric motor (14) driving the compressor (12) and is specified for a speed control of the electric motor (14) in such a way that the motor current (IB) to be absorbed by the electric motor (14) driving the compressor (12) does not exceed a maximum motor current (te max) at the time (T) at which a state of the pressure sensor (32, 34) corresponding to the request signal (SAnf) is reached.

14. Method according to claim 12 or 13 for operating a compressed air supply system (30), in which the compressed air consumer (34) is or can be pneumatically connected to the compressor (12) and / or the pressure accumulator (36) via the compressed air lines (40, 76) and the electrically controllable valves (44, 46, 48, 50, 52, 54) in such a way that the compressed air supply system (30) can be operated either in an open operating mode or in a closed operating mode, characterized in that in response to a request signal (SAnf), an output pressure (PAUS) at the output (86) of the compressor (12) and / or a motor current (IB) to be absorbed by the electric motor (14) driving the compressor (12) is predicted for the time (T) at which a state of the pressure consumer (32, 34) is reached, and depending on the predicted output pressure (PAus pra) either the electrically controllable valves (44, 46, 48, 50, 52,54) are controlled according to the open operating mode of the compressed air supply system (30) when the predicted, Output pressure (PAUS pre) is greater than or equal to a predetermined maximum value (PAUS max) for the output pressure (PAUS) or the predicted motor current (IB) is greater than or equal to a predetermined maximum value for the motor current (te max), or the electrically controllable valves (44, 46, 48, 50, 52, 54) are controlled in accordance with the closed operating mode of the compressed air supply system (30) when the predicted output pressure (PAUS pre) is less than the predetermined maximum value for the output pressure (PAUS max) or the predicted motor current (IB) is less than the predetermined maximum value for the motor current (IB max).

15. Method according to at least one of claims 12 to 14, characterized in that during operation, a voltage signal (Suv) representing the value of the available supply voltage (Uv) and / or an ambient pressure signal (SPU) representing the air pressure in the environment (Pu) and / or an air temperature signal (STU) representing the air temperature in the environment (Tu) are additionally detected and evaluated, and the output pressure (PAUS) at the output (86) of the compressor (12) and / or the motor current (IB) to be absorbed by the electric motor (14) driving the compressor (12) for the time (T) at which a state of the pressure sensor (32, 24) corresponding to the request signal (SAnf) is reached is predicted as a function of the voltage signal (Suv) and / or the ambient pressure signal (SPU) and / or the air temperature signal (STU).

16. Method according to at least one of claims 12 to 15 for operating a compressed air supply system (30) which has a pressure sensor (78) on the compressed air reservoir (36) and a drain valve (50), a return valve (48) and a reservoir valve (52) which is pneumatically connected to the pressure reservoir (36), wherein the compressed air control (56) in the event that compressed air is to be discharged from the compressed air consumer (34), the closed operating mode is activated if the current accumulator pressure (PR) in the pressure accumulator (36) is less than a storage pressure limit value (P R limit), or activates the open operating mode when the current accumulator pressure (PR) in the pressure accumulator (36) is equal to or greater than an accumulator pressure limit value (P R gr ence).

17. Method according to at least one of claims 12 to 16 for operating a compressed air supply system (30) which has a pressure sensor (78) on the compressed air reservoir (36) as well as a discharge valve (50), a return valve (48) and a reservoir valve (52) which is pneumatically connected to the pressure reservoir (36), wherein the compressed air control (56), in the event that compressed air is to be discharged from the compressed air consumer (34), is designed to calculate or estimate in advance the expected reservoir pressure (PR) on the basis of the available information about the reservoir pressure (PR) in the pressure reservoir (36) and the volume of the pressure reservoir (36), the pressure in the compressed air consumer (34) or one or more of its components (36) and their volumes (V) and height (h), and in the event that the calculated or estimated reservoir pressure (PR) exceeds a predetermined reservoir pressure limit value (P Rlimit), activate the open operating mode by switching off the compressor (12), closing (deactivating) the reflux valve (48) and the reservoir valve (52) and opening (activating) the drain valve (50).

18. Method according to one of claims 12 to 17, wherein the compressed air control (56) determines the accumulator pressure limit value (P R gre nz) from a correlation of back pressure (PAUS) and current consumption (IB) learned during operation of the compressor module (10).

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