Control method, control unit, compressed air supply unit, air suspension system and vehicle

Abstract

The invention relates to a method (100) for controlling an electric drive (30) of a compressor (20) for generating compressed air (11) for a compressed air consumer (12) of a vehicle (10), in which method a sound indicator (40) representing a vehicle sound (41) of the vehicle (10) is monitored (110) and a target speed (31) of the electric drive (30) is determined (120) as a function of the monitored sound indicator (40), wherein when a predefined threshold value (42) of the sound indicator (40) is exceeded (130), the target speed (31) of the electric drive (30) is increased (140).The invention further relates to a control unit (80) for controlling an electric drive (30) of a compressor (20) for generating compressed air (11) for a compressed air consumer (12) of a vehicle (10), a compressed air supply unit (13) with a compressor (20) for generating compressed air (11) for a compressed air consumer (12) of a vehicle (10), an air suspension system (14) for a vehicle (10) and a vehicle (10) with a control unit (80), a compressed air supply unit (13) and / or an air suspension system (14).

Description

The invention relates to a method for controlling an electric drive of a compressor for generating compressed air for a compressed air consumer of a vehicle. The invention further relates to a control unit for controlling an electric drive of a compressor for generating compressed air for a compressed air consumer of a vehicle, to a compressed air supply unit having a compressor for generating compressed air for a compressed air consumer of a vehicle, to an air suspension system for a vehicle and to a vehicle having a compressed air supply unit.DE 10 2014 012 608 A1 describes a compressed air supply system for operating a pneumatic system and a vehicle having a compressed air supply system which has a pneumatic system and a compressed air supply system. To improve acoustics, it is proposed, inter alia, that a venting valve of the compressed air supply system has a venting rear space with a venting connection to which a venting line for venting the venting rear space when a relay piston of the venting valve is actuated is connected.DE 11 2017 003 866 T5 discloses a system for determining whether lowering of the ride height of a vehicle should be prevented if the vehicle speed exceeds a speed threshold. The system has a processor which is configured to calculate a driving attribute parameter in dependence on received driving attribute data. The processor may also determine whether the vehicle is driving on a smooth surface or an uneven surface. Lowering of the ride height can thus be prevented when it is determined that the vehicle is traveling on an uneven surface. The driving attribute data may also be provided by an on-board acoustic sensor, for example.According to the features of independent claim 1, a method for controlling an electric drive of a compressor for generating compressed air for a compressed air consumer of a vehicle is proposed, in which a sound indicator representing a vehicle sound of the vehicle is monitored and a setpoint rotational speed of the electric drive is determined as a function of the monitored sound indicator, wherein the setpoint rotational speed of the electric drive is increased if a predefined threshold value of the sound indicator is exceeded.The proposed method enables an adaptive compressor drive control which is dependent on the driving situation and by means of which the compressor power for the compressed air consumer can be increased depending on the situation without impairing the comfort of vehicle occupants. An increase in the compressor power by increasing the rotational speed of the electric drive can generally involve an increased compressor sound which can be perceived as annoying by vehicle occupants. However, the increased vehicle sound associated with exceeding a predefined threshold value of the sound indicator may be suitable for masking the increased compressor sound or at least for diverting the acoustic perception of vehicle occupants from the compressor sound. A proactive and targeted compressor drive control is thus made possible, which not only acts as required, but also as a function of comfort and uses driving situations suitable for increasing the efficiency to increase the compressor output. Furthermore, the proposed control method is designed as a dynamic control method by determining the setpoint rotational speed of the electric drive as a function of the monitored sound indicator and is therefore adaptable efficiently to a present driving situation at any time. In addition, the sound indicator proposed as a monitoring variable is a representative value for the vehicle sound, which can be derived, for example, not only on the basis of acoustic variables but also from other variables correlating with the vehicle sound. This allows greater flexibility and control reliability for the proposed control method, in which, for example, a plurality of variables correlating with the vehicle sound can also be used for plausibility checking, for redundancy purposes or for defining precise conditions for determining the setpoint rotational speed.The compressor, also referred to as compressor, is configured to generate compressed air and can be designed, for example, as a reciprocating piston compressor or a scroll compressor. The compressor can be driven by means of an electric drive for generating compressed air, wherein the electric drive can be designed, for example, as an electrically commutated direct current motor, in particular as a brushless direct current motor. Such drives have advantages with regard to a fast response time and start-up time and a continuously and precisely adjustable rotational speed. The compressor operation can be started and stopped by means of the electric drive as required or depending on the situation. By increasing the rotational speed of the drive, the compressor power can be increased, so that a higher amount of compressed air can be provided to a compressed air consumer of the vehicle. A compressed air consumer of the vehicle can be, for example, an air suspension system, in particular an electronically controlled air suspension system, or a compressed air brake system of the vehicle. A rotational speed of the drive is predefined with a setpoint rotational speed with control technology, wherein a present actual rotational speed can be monitored, for example, by means of a control circuit and compared with the predefined setpoint rotational speed. The setpoint rotational speed can be determined and predefined by control technology already before starting the compressor operation, so that the electric drive can rapidly accelerate to the predefined setpoint rotational speed when starting the compressor. It is also possible to change the setpoint rotational speed during the ongoing operation of the compressor, so that a dynamic, for example situation-dependent, adaptation of the compressor power is possible by changing the rotational speed of the electric drive.For this purpose, it is proposed to monitor a sound indicator representing vehicle sound of the vehicle. The sound indicator can be a dynamic variable, for example an acoustic variable such as a sound pressure or a sound frequency of the vehicle sound occurring, or a non-acoustic variable correlating with the vehicle sound. Accordingly, the sound indicator can represent a representative value with which, depending on the quantity used, it is possible to draw a conclusion directly or indirectly, for example, as to an intensity or frequency of the present vehicle sound. The sound indicator is not limited to a sound load detectable in the vehicle interior, but can also include a detection on other vehicle areas, for example on an exterior area of the vehicle, as a representative value. The term vehicle sound can refer to a structure-borne sound and / or airborne sound of the vehicle. The term "vehicle sound" can be understood in particular to mean a vehicle sound occurring in interaction with the surroundings of the vehicle, for example as a result of rolling noises, wind noises or precipitation noises. The monitoring of the sound indicator can be effected, for example, by ascertaining the sound indicator and comparing the ascertained sound indicator with one or more threshold values. For this purpose, instantaneous values or a dynamic profile of the sound indicator can be detected, for example, by sensor technology. In particular, when evaluating a dynamic profile of the sound indicator, a plurality of monitoring criteria can be analyzed or further sound indicators can be derived from the profile, for example a uniformity of a represented vehicle sound over time. The sound indicator can be determined in principle by measuring a variable or, for example, also by determination on the basis of predefined characteristic curves, so that indirect detection by correlating variables is possible. The measured variable or an indicator value determined on the basis of characteristic curves can also be converted, for example, into a characteristic value as a sound indicator, for example if a non-acoustic variable is used via an indirect relationship, for example a specific course pattern, for assessing the vehicle sound. In this way, threshold value monitoring on the basis of the derived characteristic value can be facilitated. For monitoring the sound indicator, the sound indicator is compared with a threshold value, which may represent a predefined minimum intensity of the vehicle sound or a lower limit of a natural frequency range of the vehicle sound, for example. It is conceivable to use further threshold values for monitoring, for example to define a plurality of thresholds for further increasing the setpoint rotational speed of the electric drive or to define a plurality of setpoint rotational speed ranges. In addition, a plurality of sound indicators can be monitored, for example two or more sound indicators different from one another can be monitored and, depending on the embodiment, a setpoint rotational speed can be increased when a threshold value of one of the sound indicators is exceeded or when threshold values of a plurality of or all monitored sound indicators are exceeded. Examples of different sound indicators are presented in the following explanation of advantageous embodiments.The electric drive of the compressor can be controlled, for example, by means of a control unit, in particular an electronic control unit. The control unit can be configured to actuate the drive according to the determined setpoint rotational speed. The determination of the setpoint rotational speed can be carried out, for example, on the basis of determination specifications electronically stored in the control unit as a function of the monitored sound indicator, for example on the basis of a predefined algorithm or using characteristic curves, tables or calculation rules.According to one embodiment, after an increase in the setpoint rotational speed as a result of the predefined threshold value of the sound indicator being exceeded, the setpoint rotational speed can be reduced if the predefined threshold value of the sound indicator is undershot again. This can ensure that, in the case of a falling or reduced vehicle sound, after a driving situation associated with an increased vehicle sound, the compressor sound does not come to the foreground, but rather is reduced again in order to increase the occupant comfort. The demand- and comfort-dependent compressor drive control is thus further improved and driving situation-dependent control of the compressor is further developed. The proposed control method can advantageously be operated continuously, such that the setpoint rotational speed can be increased again continuously, for example, if the acoustic indicator is exceeded again, and can be reduced again after the threshold value has been undershot again. Optionally, at least one timer can be incorporated into the control sequence in order to define a predefined delay time after an increase and / or after a reduction of the setpoint rotational speed of the electric drive. As a result, hysteresis behavior can be achieved and a dog of the setpoint rotational speed in the sense of a frequent rotational speed jump can be avoided if the ascertained sound indicator moves close to the threshold value and repeatedly exceeds and falls below it at short time intervals.According to one specific embodiment, the sound indicator may be monitored by means of an acoustic sensor of the vehicle, in particular by means of an acoustic external sensor of the vehicle. Acoustic sensors serve for the detection of sound waves and convert these into an electrical signal. An acoustic sensor can be used to record the vehicle sound simply and directly, so that the sound indicator can directly represent the vehicle sound. The acoustic sensor can be, for example, a microphone or an acceleration sensor. The variable detected with the acoustic sensor can be, for example, a sound intensity or a sound frequency. The acoustic sensor can be arranged, for example, in a vehicle interior in order to be able to detect the sound load perceptible by vehicle occupants as precisely as possible. However, it can also be advantageous to use an acoustic external sensor which is arranged, for example, on an outer side of the vehicle shell. As a result, in comparison with sound recording in the vehicle interior, for example, more precise analysis and classification of the occurring vehicle sound can take place, for example, whether the vehicle sound is caused by a specific driving surface such as a headstone pavement or by an environmental influence such as, for example, a weather condition such as precipitation, so that differentiated assessment and derivation of a sound indicator are possible. In addition, it is basically conceivable to specifically evaluate an external vehicle sound by means of the sound indicator and to use it for determining the setpoint rotational speed in order to reduce a sound load due to the compressor sound for persons outside the vehicle, for example passengers, depending on the situation. In this way, not only can occupant comfort be taken into account, but also a situation-dependent influence on external noise emissions of the vehicle can be effected. In this case, an acoustic external sensor can advantageously be used to determine the sound indicator. The acoustic sensor, in particular the acoustic external sensor, can be additionally assigned, for example, to an acoustic driver assistance system of the vehicle, with which driving situations and environmental influences can be determined and evaluated acoustically. As a result, already existing acoustic sensors can advantageously be additionally evaluated for the compressor drive control.According to one specific embodiment, the sound indicator may be ascertained by means of a driving-dynamic sensor of the vehicle. This advantageously allows an assessment of the vehicle sound to be carried out by means of sensors which may already be present on the vehicle. In addition, driving dynamics sensors can be more robust with respect to comparatively sensitive microphones, for example. By means of the vehicle dynamic sensor, a differentiated and precise analysis of the vehicle situation can also be carried out. The vehicle dynamic sensor can be designed, on the one hand, for the direct or indirect detection of acoustic vehicle sound and, on the other hand, for the detection of mechanical forces and accelerations. The driving dynamics sensor can be used alternatively or additionally to an acoustic sensor for ascertaining a sound indicator. A sound indicator determined by means of a driving dynamic sensor can also be used, for example, for plausibility checking a sound indicator determined by means of an acoustic sensor and vice versa, or the sound indicators of both sensor types can be evaluated together, for example with a two-factor dependence or a multi-factor dependence. The vehicle dynamics of the vehicle may correlate with vehicle sound of the vehicle. The driving dynamics of the vehicle thus offer an indirect possibility of assessing and at least indirectly monitoring a vehicle sound that occurs. The driving dynamics can result, for example, from specific vehicle properties or vehicle states, but also from environmental influences that can also influence the vehicle sound. A driving-dynamics sensor can be designed, for example, as a chassis sensor or as an NVH measurement device (NVH: noise, vibration, roughness).According to one specific embodiment, the acoustic sensor and / or the vehicle dynamic sensor may be designed as one of the following sensors:- acceleration sensor;shock absorber sensor;steering angle sensor;- wheel speed sensor.For example, the acoustic sensor can be designed as an acceleration sensor. If a plurality of acoustic sensors are used for ascertaining one or more acoustic indicators, at least one acoustic sensor can be designed as an acceleration sensor. For example, the vehicle dynamics sensor can be designed as an acceleration sensor, shock absorber sensor, steering angle sensor or wheel speed sensor. If a plurality of driving dynamics sensors are used to determine one or more sound indicators, at least one of the driving dynamics sensors can be designed as an acceleration sensor, shock absorber sensor, steering angle sensor or wheel speed sensor, or different ones of the aforementioned sensors can be evaluated as driving dynamics sensors for determining sound indicators.An acceleration sensor can be used, for example, advantageously as a vibration sensor in order to be able to ascertain an amplitude or frequency of a vehicle sound and to derive a sound indicator. In addition, vehicle vibrations and certain vehicle accelerations or vehicle acceleration patterns can correlate with the vehicle sound, so that suitable sound indicators can be determined therewith. For example, crosswinds that lead to a specific driving-dynamic vehicle behavior can be detected by an acceleration sensor and can be used to infer an increased vehicle sound. To monitor the sound indicator, such vehicle behavior patterns can be initially converted, for example, by means of the control unit into a characteristic value, on the basis of which a comparison of the sound indicator with a threshold value is possible.A shock absorber sensor can be used, for example, to detect a shock absorber activity of the vehicle. An increased shock absorber activity can indicate, for example, an uneven driving surface such as headstone plaster or striking holes. Uneven driving backgrounds can be associated with increased vehicle sound, so that a suitable sound indicator can be derived using a shock absorber sensor, for example via an intensity of the shock absorber activity or by converting specific shock absorber activity patterns into a characteristic value, on the basis of which a comparison of the sound indicator with a threshold value is possible. The shock absorber sensor can be designed, for example, as an acceleration sensor or as a position sensor.A steering angle sensor can be used, for example, to detect a steering angle or steering angle of a steering device of the vehicle. For example, constant steering angles over a longer period of time, repeated relatively strong steering movements or a discrepancy between the steering angle and a direction of travel of the vehicle can indicate specific driving situations, for example increased crosswinds or an uneven driving surface. Driving situations of this type can correlate with increased vehicle sound, so that a suitable sound indicator can be derived using a steering angle sensor. For monitoring the sound indicator, steering angle profiles can be initially converted, for example by means of the control unit, into a characteristic value, on the basis of which a comparison of the sound indicator with a threshold value is possible. The steering angle sensor can be designed, for example, as an electromagnetic sensor.For example, vehicle speeds can be derived using a wheel speed sensor on the basis of the ascertained wheel speed. For example, a trip at high vehicle speed can indicate an increased vehicle sound, so that a suitable sound indicator can be derived using a wheel speed sensor, for example via the vehicle speed or by converting specific speed patterns into a characteristic value, on the basis of which a comparison of the sound indicator with a threshold value is possible. The wheel speed sensor can be designed, for example, as an electromagnetic sensor.According to one specific embodiment, the sound indicator may be ascertained by means of an environment sensor, in particular by means of an optical environment sensor of the vehicle. Ambient sensors are used for detecting ambient conditions or driving situations and can be additionally assigned to a driver assistance system of the vehicle, for example, so that vehicle sensors that are already present can advantageously be used to ascertain sound indicators. The environment sensor can be configured as an external sensor of the vehicle in order to be able to detect an external environment or an external vehicle region of the vehicle. According to one example, the environment sensor can be designed, for example, as a rain sensor. The rain sensor can be designed, for example, as an optical rain sensor which can detect water drops on a windshield of the vehicle, for example, by measuring the light intensity. A precipitation detected by means of the rain sensor can indicate an increased vehicle sound, so that a suitable sound indicator can be derived by means of a rain sensor, for example by means of a measured precipitation intensity or quantity. According to a further example, the in particular optical environment sensor can be designed as a camera. The field of view of the camera can be directed, for example, to a surrounding area of the vehicle or to an outer vehicle area. Image data captured by the camera can be analyzed and evaluated, for example, by means of a digital image processing device, for example, using image recognition methods. Thus, for example, a speed of the vehicle, a driving background or a weather condition such as precipitation can be determined on the basis of the camera data, which can indicate a specific vehicle sound. A suitable sound indicator can thus be derived with a camera, wherein analysis results of the image processing can be transferred, for example, into a characteristic value suitable for monitoring. The environment sensor can be used alternatively or additionally to an acoustic sensor or alternatively or additionally to a driving dynamic sensor for determining a sound indicator. A sound indicator determined by means of an acoustic or driving dynamic sensor can also be used, for example, for plausibility checking a sound indicator determined by means of an environmental sensor and vice versa, or the sound indicators of two or more of the aforementioned sensor types can be evaluated together, for example with a two-factor dependency or multi-factor dependency.According to one embodiment, the electric drive of the compressor can be operable in a normal operation and in a power operation, wherein a predefined setpoint rotational speed range of the power operation is higher than a predefined setpoint rotational speed range of the normal operation, and wherein the electric drive of the compressor is operated in the power operation if the sound indicator exceeds the predefined threshold value. This allows simple and defined control of the electric drive according to predefined setpoint rotational speed ranges. Suitable or permitted setpoint rotational speed ranges can be predefined in this case as a function of the operating mode and stored, for example, in a memory of a control unit of the vehicle. In addition, it is conceivable to provide, in addition to normal operation and power operation, a float operation with a further setpoint rotational speed range, wherein the further setpoint rotational speed range is below the setpoint rotational speed range of the normal operation of the drive and is thus associated with reduced compressor noise. The drive can be operated, for example, in the float mode when the sound indicator falls below a second predefined threshold value. Such an undershoot may occur, for example, when the vehicle is at a standstill, in particular when no sound-generating or sound-intensifying environmental influences such as precipitation, for example, occur. Accordingly, the drive can be controlled on the basis of a detected sound indicatorin normal operation with a corresponding setpoint rotational speed range, if a sound indicator is set between the predefined threshold value and the second predefined threshold value,in a power mode with a corresponding setpoint rotational speed range, if the sound indicator exceeds the predefined threshold value, andin a float mode with a corresponding setpoint rotational speed range, if the sound indicator falls below the second predefined threshold value.The setpoint rotational speed range of normal operation can comprise, for example, a value range of approximately 2,600 to 2,900 1 / min, in particular approximately 2,700 to 2,850 1 / min. The setpoint rotational speed range of the power operation can comprise, for example, a value range of approximately 3,000 to 3,300 1 / min, in particular approximately 3,100 to 3,250 1 / min. The setpoint rotational speed range of the float operation can comprise, for example, a value range of approximately 2,000 to 2,300 1 / min, in particular approximately 2,100 to 2,150 1 / min, or a value range of approximately 2,500 to 2,750 1 / min, in particular approximately 2,610 to 2,700 1 / min.The invention also relates to a control unit for controlling an electric drive of a compressor for generating compressed air for a compressed air consumer of a vehicle, wherein the control unit is configured to monitor a sound indicator representing a vehicle sound of the vehicle and to determine a setpoint rotational speed of the electric drive as a function of the monitored sound indicator, and wherein the control unit is configured to increase the setpoint rotational speed of the electric drive when a predefined threshold value of the sound indicator is exceeded. The control unit can be configured in particular for carrying out the method described above according to one of the features described in connection with the method.The proposed control unit also achieves the advantages described above of a proactive, adaptive, driving situation-dependent and dynamic compressor drive control which acts not only as required but also as a function of comfort and uses driving situations suitable for increasing the efficiency for increasing the compressor output. The control unit can have a signal input for receiving a sound indicator or a signal from which a sound indicator can be derived, and a circuit for determining and / or evaluating the sound indicator. The circuit can be configured in particular for comparing the sound indicator with a threshold value and for determining a setpoint rotational speed of the drive on the basis of the evaluation result. The control unit can have a signal output for providing the determined setpoint rotational speed at the electric drive of the compressor. The control unit can have a memory in which, for example, a threshold value of the sound indicator, a predefined algorithm for determining the setpoint rotational speed, characteristic curves, tables, calculation rules or also predefined setpoint rotational speed ranges for different operating modes, for example for a normal operation, a power operation or a float operation, can be stored.The control unit can furthermore be configured to reduce the setpoint rotational speed after an increase in the setpoint rotational speed as a result of the predefined threshold value of the sound indicator being exceeded, if the predefined threshold value of the sound indicator is undershot again. This can ensure that, in the case of a falling or reduced vehicle sound, after a driving situation associated with an increased vehicle sound, the compressor sound does not come to the foreground, but rather is reduced again in order to increase the occupant comfort.According to one specific embodiment, the control unit may be configured to ascertain the sound indicator by means of an acoustic sensor, by means of a driving-dynamic sensor, and / or by means of an environmental sensor. The acoustic sensor, the driving dynamics sensor and / or the environment sensor can be designed according to the sensor types and sensor properties explained in connection with the method described above. By means of the sensors mentioned, a representative value for the vehicle sound can be determined, which can be derived, for example, not only on the basis of acoustic variables but also from non-acoustic variables correlating with the vehicle sound. This allows greater flexibility and control reliability. The control unit can be connected by signal technology to the acoustic sensor, the driving dynamics sensor and / or the environment sensor, for example by a wired or wireless signal connection. The control unit can be assigned, for example, to a compressed air supply unit of the vehicle, so that the compressed air supply unit has a control unit separate from further vehicle control units according to a decentralized control approach. In this way, the control unit can be set up for independent control of the compressor of the compressed air supply unit on the basis of parameters made available, for example, via a bus system, for example, on the basis of a vehicle speed, a driver's wish for changing the vehicle level or on the basis of energy supply data. According to a predominantly central control approach, the control unit can be a collection control unit for a plurality of or all chassis components of the vehicle, to which the aforementioned parameters are made available in a collected manner and which is configured for the central control of chassis components, in particular of the compressed air supply unit.The invention also relates to a compressed air supply unit having a compressor for generating compressed air for a compressed air consumer of a vehicle, wherein the compressor has an electric drive which can be controlled by means of a control unit according to one of the features described above. According to one specific embodiment, the compressed air supply unit may have, according to a decentralized control approach, a control unit according to one of the features described above. According to one embodiment, the electric drive can be controllable according to the method described above. The advantages described above can also be achieved with the proposed compressed air supply unit.The invention also relates to an air suspension system for a vehicle having a vehicle air suspension and a compressed air supply unit according to one of the features described above. According to one embodiment, the air suspension system, in particular the compressed air supply unit, can have a control unit according to one of the features described above. The advantages described above can also be achieved with the proposed air suspension system.The invention also relates to a vehicle having a control unit according to one of the features described above, having a compressed air supply unit according to one of the features described above and / or having an air suspension system according to one of the features described above. The control unit can be, for example, a collective control unit of the vehicle or a separate control unit of the compressed air supply unit. The advantages described above can also be achieved with the proposed vehicle. The vehicle can be designed, for example, as a commercial vehicle or as a passenger vehicle. In particular for commercial vehicles, the advantages which can be achieved explained can have an increased effect, since commercial vehicles can develop increased vehicle sound due to their usual design and their dimensioning, and efficient compressor operation is desirable on account of their possibly higher compressed air requirement compared to passenger vehicles.The invention permits various embodiments and is explained in more detail below on the basis of exemplary embodiments with the accompanying drawings. They show in schematic form: FIG. 1 shows a vehicle having an air suspension system and a control unit according to an exemplary embodiment; FIG. 2 shows a schematic diagram of a control unit for controlling an electric drive of a compressor according to an exemplary embodiment; FIG. 3 shows a flow chart of a method for controlling an electric drive according to an exemplary embodiment; and FIG. 4 shows an exemplary profile of a compressor sound as a function of the rotational speed of an electric drive of the compressor.FIG. 1 shows, in simplified and schematic form, a vehicle 10 which, according to the exemplary embodiment shown, is designed as a utility vehicle having a towing vehicle 17 and a trailer vehicle 16. The vehicle 10 has an air suspension system 14 with a vehicle air suspension 15 and a compressed air supply unit 13. The air suspension system 14 forms a compressed air receiver 12 of the vehicle 10. According to other exemplary embodiments, alternative or supplementary systems of the vehicle 10 can form compressed air receivers 12, for example a compressed air brake system of the vehicle 10, not shown in more detail. The compressed air receiver 12 has a compressed air line 18 to a compressor 20 of the vehicle 10 for supplying the compressed air supply unit 13 with compressed air 11, which compressor is arranged in the towing vehicle 17 according to the exemplary embodiment shown. The compressor 20 is driven by means of an electric drive 30. For controlling the electric drive 30, the electric drive 30 is connected to a control unit 80 of the vehicle 10 via a signal line 19.The vehicle 10 further comprises an acoustic sensor 50 which, according to the exemplary embodiment shown, is arranged in a vehicle cabin 43 of the vehicle 10. In addition, an acoustic external sensor 50 ais provided on the vehicle 10 and is arranged, for example, on an outer side of the vehicle shell. The acoustic sensor 50 and / or the acoustic external sensor 50 acan be embodied, for example, as microphones or acceleration sensors. The vehicle 10 furthermore has a plurality of driving dynamics sensors 60. According to the illustrated embodiment, an acceleration sensor 60 a, a shock absorber sensor 60 b, a steering angle sensor 60 c, and a wheel speed sensor 60 dare provided as the dynamic driving sensors 60. The vehicle 10 furthermore has an environment sensor 70, which can be designed, for example, as a rain sensor, and an optical environment sensor 70 a, which can be designed, for example, as a camera and is configured for optically detecting a vehicle environment. On the basis of sensor signals of acoustic sensors 50, 50 a, vehicle dynamics sensors 60 and surroundings sensors 70, 70 a, it is possible to ascertain a sound indicator 40, which is schematically shown in FIG. 2, for example, and represents a vehicle sound 41 of vehicle 10. The sound indicator 40 can advantageously be used to dynamically actuate the electric drive 30 of the compressor 20, as will be explained in more detail below with reference to FIGS. 2 to 4. It is proposed here that the sound indicator 40 be monitored and a setpoint rotational speed 31 of the electric drive 30 be determined as a function of the monitored sound indicator 40, wherein the setpoint rotational speed 31 of the electric drive 30 is increased if a predefined threshold value 42 of the sound indicator 40 is exceeded. This achieves a proactive, adaptive, driving situation-dependent and dynamic compressor drive control which acts not only as required but also as comfort-dependent and uses driving situations suitable for increasing the efficiency to increase the compressor power. In this case, the sound indicator 40 can represent a representative value for the vehicle sound 41, which can be determined not only on the basis of acoustic variables but also on the basis of non-acoustic variables correlating with the vehicle sound 41.The sound indicator 40 can be used, for example, to infer an intensity or frequency of the vehicle sound 41 directly or indirectly.FIG. 2 shows a schematic diagram of an exemplary embodiment of the control unit 80 for controlling the electric drive 30 of the compressor 20. According to one specific embodiment, data processing unit 81 may have an image processing function, with which images of optical surroundings sensor 70 acan be electronically processed and evaluated. The control unit 80 further includes a storage unit 82 connected to the data processing unit 81. For example, one or more threshold values 42 for sound indicators 40 can be stored in the memory unit 82. For example, setpoint rotational speed ranges for operating modes which will be explained in more detail below, for example a setpoint rotational speed range 32 of a power mode LB, a setpoint rotational speed range 33 of a normal mode NB and / or a setpoint rotational speed range 34 of a float mode 34 of the electric drive 30 of the compressor 20, can be stored in the memory unit 82. According to the exemplary embodiment shown, the control unit 80 is configured to receive a signal S 50 of an acoustic sensor 50, a signal S 60 of a driving dynamic sensor 60 and a signal S 70 of an environmental sensor 70. On the basis of the signals S 50, S 60 and S 70 the data processing unit 81 can determine a sound indicator 40 and monitor it continuously or periodically, for example, for example by comparing the determined sound indicator 40 with the threshold value 42. The control unit 80 is designed to output a corresponding control signal S A according to the determined setpoint rotational speed 31 and to provide it to the electric drive 30. Furthermore, the control unit 80 is configured to increase the setpoint rotational speed 31 of the electric drive 30 when the threshold value 42 of the sound indicator 40 is exceeded. The control unit 80 can furthermore be configured to reduce the setpoint rotational speed 31 after an increase in the setpoint rotational speed 31 as a result of the threshold value 42 of the sound indicator 40 being exceeded, if the threshold value 42 is undershot again. This can ensure that, in the case of reduced vehicle sound 41, the compressor sound does not come to the foreground after a driving situation associated with increased vehicle sound 41.FIG. 3 schematically depicts a flow diagram of a method 100 for controlling the electric drive 30 according to an exemplary embodiment. The method 100 can be carried out, for example, with the above-described control unit 80. Starting from a start 101 of the method 100, the sound indicator 40 is ascertained 105 continuously, for example on the basis of the sensor signals S 50, S 60 and S 70. described above. Furthermore, the ascertained sound indicator 40 is monitored 110 and a setpoint rotational speed 31 of the electric drive 30 is determined 120 as a function of the monitored sound indicator 40. At the beginning 101 of the method 100, which can start, for example, with a start of travel of the vehicle 10, the sound indicator 40 can be below the predefined threshold value 42, for example, and a setpoint rotational speed 31 of the electric drive 30 can be determined according to a first rotational speed value or first rotational speed range. When the threshold value 42 is exceeded 130, the setpoint rotational speed 31 of the electric drive 30 is increased 140 to a second rotational speed value, which can correspond to a rotational speed value of a second rotational speed range. Subsequently, by continuously determining 105 the sound indicator 40 according to the exemplary embodiment shown, it can be monitored whether the determined sound indicator 40 falls below the predefined threshold value 42 again. If the predefined threshold value 42 is undershot 150, the setpoint rotational speed 31 is reduced 160, for example to the first rotational speed value or a rotational speed value of the first rotational speed range before the increase 140 of the setpoint rotational speed 31 as a result of the threshold value 42 being exceeded 130. Optionally, as illustrated, at least one timer 170 can be incorporated into the control sequence in order to define a predefined delay time after an increase 140 and / or after a reduction 160 of the setpoint rotational speed 31 of the electric drive 30. As a result, hysteresis behavior can be achieved and a dog of the setpoint rotational speed 31 in the sense of a frequent rotational speed jump can be avoided if the ascertained sound indicator 40 moves close to the threshold value 42 and repeatedly exceeds and falls below it at short time intervals. The first rotational speed range can correspond, for example, as explained below, to a predefined setpoint rotational speed range 33 of a normal operation NB or to a predefined setpoint rotational speed range 34 of a float operation FB. The second rotational speed range can correspond, for example, to a predefined setpoint rotational speed range 32 of a power mode LB or to a predefined setpoint rotational speed range 33 of a normal mode NB. According to one variant, further rotational speed ranges for determining the setpoint rotational speed 31 can be established with at least one further threshold value with which the sound indicator 40 is compared in addition to the threshold value 42.FIG. 4 shows an exemplary course of a compressor sound as a function of the rotational speed of the electric drive 30 of the compressor 20. On the basis of the sound intensities, different operating modes of the electric drive 30 of the compressor 20 can be defined. Thus, the electric drive 30 of the compressor 20 can be operable in a normal operation NB and in a power operation LB, wherein a predefined setpoint rotational speed range 32 of the power operation LB can be higher than a predefined setpoint rotational speed range 33 of the normal operation NB, wherein the electric drive 30 can be operated in the power operation LB if the sound indicator 40 exceeds the predefined threshold value 42. For example, a float mode FB of the electric drive 30 can be activated with a setpoint rotational speed range 34 of approximately 2,000 to 2,300 1 / min or approximately 2,500 to 2,750 1 / min, which is connected to a particularly low compressor sound. With a setpoint rotational speed range 33 of approximately 2,600 to 2,900 1 / min, a normal operation NB of the electric drive 30 can be actuated. With a rotational speed range of approximately 2,500 to 2,750 1 / min, a power mode LB of the electric drive 30 can be activated, which although it may be associated with increased compressor sound, may be covered by the vehicle sound 41 depending on a present driving situation, as explained above.List of Reference Numerals (part of the description)10 Vehicle 11 Compressed air 12 Compressed air consumer 13 Compressed air supply unit 14 Air suspension system 15 Vehicle air suspension 16 Trailer vehicle 17 Towing vehicle 18 Compressed air line 19 Signal line 20 Compressor 30 Electric drive 31 Setpoint rotational speed 32 Setpoint rotational speed range of the power operation 33 Setpoint rotational speed range of the normal operation 34 Setpoint rotational speed range of the float operation 40 Sound indicator 41 Vehicle sound 42 Threshold value 43 Vehicle cabin 50 Acoustic sensor 50 a Acoustic external sensor 60 Dynamic sensor 60 aAccelerometric sensor 60 b Stoßdämpfer sensor 60 c Steering angle sensor 60 d Wheel rotational speed sensor 70 Ambient sensor 70 a Optical ambient sensor 80 Control unit 81 Data processing unit 82 Storage unit 100 Method 101 Start of the method 105 Ascertainment of a sound indicator 110 Monitoring of the sound indicator 120 Determination of a setpoint rotational speed of the electric drive 130 Exceeding a predefined threshold value 140 Increasing of the torque delivered by the vehicle. Speed of the electric drive 150 falls below the predefined threshold value 160 Reduction of the speed of the electric drive 170 Timer FB Float mode LB Power mode NB Normal mode S A Control signal S 50 Signal of the acoustic sensor S 60 Signal of the vehicle dynamic sensor S 70 Signal of the environment sensorReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2014 012 608 A1

[0002] DE 11 2017 003 866 T5

[0003]

Claims

Method (100) for controlling an electric drive (30) of a compressor (20) for generating compressed air (11) for a compressed air consumer (12) of a vehicle (10), in which a sound indicator (40) representing a vehicle sound (41) of the vehicle (10) is monitored (110) and a setpoint rotational speed (31) of the electric drive (30) is determined (120) as a function of the monitored sound indicator (40), characterized in that the setpoint rotational speed (31) of the electric drive (30) is increased (140) if a predefined threshold value (42) of the sound indicator (40) is exceeded (130).Method (100) according to Claim 1, characterized in that, after an increase (140) in the setpoint rotational speed (31) as a result of the predefined threshold value (42) of the sound indicator (40) being exceeded (130), the setpoint rotational speed (31) is reduced (160) if the predefined threshold value (42) of the sound indicator (40) is undershot (150) again.Method (100) according to Claim 1 or 2, characterized in that the sound indicator (40) is determined (105) by means of an acoustic sensor (50) of the vehicle (10), in particular by means of an acoustic external sensor (50a) of the vehicle (10).Method (100) according to one of the preceding claims, characterized in that the sound indicator (40) is determined (105) by means of a driving dynamic sensor (60) of the vehicle (10).Method (100) according to Claim 3 or 4, characterized in that the acoustic sensor (50) and / or the dynamic-driving sensor (60) of the vehicle (10) is designed as one of the following sensors (50, 60): - acceleration sensor (60a); - shock absorber sensor (60b); - steering angle sensor (60c); - wheel rotational speed sensor (60d).Method (100) according to one of the preceding claims, characterized in that the sound indicator (40) is determined by means of an environmental sensor (70), in particular by means of an optical environmental sensor (70a) of the vehicle (10).Method (100) according to one of the preceding claims, characterized in that the electric drive (30) of the compressor (20) is operable in a normal operation (NB) and in a power operation (LB), wherein a predefined setpoint rotational speed range (32) of the power operation (LB) is higher than a predefined setpoint rotational speed range (33) of the normal operation (NB), and wherein the electric drive (30) of the compressor (20) is operated in the power operation (LB) if the sound indicator (40) exceeds (130) the predefined threshold value (42).Control unit (80) for controlling an electric drive (30) of a compressor (20) for generating compressed air (11) for a compressed air consumer (12) of a vehicle (10), wherein the control unit (80) is configured to monitor (110) a sound indicator (40) representing a vehicle sound (41) of the vehicle (10) and to determine (120) a setpoint rotational speed (31) of the electric drive (30) as a function of the monitored sound indicator (40), characterized in that the control unit (80) is configured to increase (140) the setpoint rotational speed (31) of the electric drive (30) if a predefined threshold value (42) of the sound indicator (40) is exceeded (130).Control unit (80) according to Claim 8, characterized in that the control unit (80) is configured to ascertain (105) the sound indicator (40) by means of an acoustic sensor (50), by means of a driving-dynamic sensor (60) and / or by means of an environmental sensor (70).Compressed air supply unit (13) having a compressor (20) for generating compressed air (11) for a compressed air consumer (12) of a vehicle (10), wherein the compressor (20) has an electric drive (30) which can be controlled by means of a control unit (80) according to either of Claims 8 and 9.Air suspension system (14) for a vehicle (10) having a vehicle air suspension (15) and a compressed air supply unit (13) according to Claim 10.Vehicle (10) having a control unit (80) according to either of Claims 8 and 9, a compressed-air supply unit (13) according to Claim 10 and / or an air suspension system (14) according to Claim 11.

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