Method for operating a piston compressor and piston compressor

Abstract

The invention relates to a method for operating a piston compressor (10) for a motor vehicle, in particular an air spring piston compressor of an air spring system or a sensor cleaning compressed air system of the motor vehicle, wherein a compressor piston (14) in a compressor cylinder (12) is driven, at least indirectly, by a drive shaft (20) of a drive motor (18) rotatable about an axis of rotation (24) in at least one direction of rotation (26) in order to compress aspirated air. It is provided that a control device (34) of the drive motor (18) changes the direction of rotation (26) of the drive motor (18) when the drive motor (18) is started, in particular reversing it, depending on at least one definable direction of rotation parameter (36). In addition, a piston compressor (10) for a motor vehicle is proposed, with a control device that is set up for the aforementioned operating procedure.

Description

[0001] The invention relates to a method for operating a piston compressor for a motor vehicle, in particular an air spring piston compressor of an air spring system or a sensor cleaning compressed air system of the motor vehicle, wherein a compressor piston in a compressor cylinder is driven, at least indirectly, by a drive shaft of a drive motor rotatable about an axis of rotation in at least one direction of rotation in order to compress aspirated air.

[0002] Furthermore, the invention relates to a piston compressor that can be operated according to this method. STATE OF THE ART

[0003] Piston compressors of the type mentioned above are widely known from the prior art, for example from DE 10 2018 130 887 A1.

[0004] These types of piston compressors are regularly used in the air suspension systems of motor vehicles, where they are used to fill the air spring bellows of the suspension system. This allows the suspension behavior to be adjusted adaptively, even while driving, depending on load, speed, weather conditions, and other parameters.

[0005] Additionally or alternatively, compressed air-based sensor cleaning can be used in the field of vehicle sensors to increase the safety and efficiency of vehicle operation. Sensors responsible for navigation and environmental perception, such as LiDAR, radar, cameras, as well as windshields and headlights, can be affected by various environmental influences, including dust, dirt, and other particles. A compressed air compressor for sensor cleaning can keep the sensors clean and operational, particularly for autonomous vehicle control.

[0006] For this purpose, such a piston compressor has as its essential components a compressor piston that can be moved within a compressor cylinder for drawing in and compressing air. This piston is at least indirectly connected to a drive shaft driven by a drive motor, usually via a connecting rod, and thus can be driven. The compressor cylinder can be designed for either single-stage operation with one compressor cover or for two-stage operation with two compressor covers positioned opposite each other along the piston.

[0007] The design and function of the piston compressor are widely known. Essentially, a drive motor generates a motive force and transmits it to the drive shaft, causing it to rotate. This rotational force is typically converted into a reciprocating force by means of the connecting rod, which is coupled to the drive shaft and the compressor piston, and transmitted to the compressor piston. This causes the compressor piston to move up and down within the compressor housing in a reciprocating motion. The compressor housing has an inlet for drawing in air from the atmosphere and an outlet for the drawn-in air. The inlet and outlet are fluidically connected to a piston chamber in which the compressor piston is movably mounted and are often closable by valves, particularly check valves. The downward movement of the compressor piston compresses air within the compressor housing.A vacuum is created in the piston chamber, drawing in air. The subsequent stroke compresses the previously drawn-in air and directs it through the outlet to its destination, such as an air spring bellows, a compressed air reservoir in a vehicle air suspension system, or a sensor cleaning system.

[0008] In principle, piston compressors can be operated reciprocally with respect to the direction of rotation of the drive shaft, i.e., in both clockwise and counterclockwise directions. However, the direction of rotation of the drive shaft is usually fixed inertially, so that it remains constant throughout the compressor's lifespan. Consequently, the drive systems of known piston compressors are generally designed and operated such that the drive shaft always rotates in one direction, or at least only in one direction during normal operation. However, such methods of operating the piston compressor lead to the problem of uneven stress and wear on the components, and thus, sooner or later, to a loss of functionality and service life due to this uneven wear.In particular, one-sided stresses occur on the cylinder wall, the piston cover, the connecting rod bearings and the crankshaft, and are also particularly pronounced in the sealing between the compressor piston and the surrounding housing or the compressor cylinder.

[0009] To mitigate this problem, it is known to design the components of the piston compressor geometrically and materially to withstand this one-sided load, or to optimize their design accordingly, so that a certain minimum service life is achieved. This leads to the subsequent problem that the design and manufacture of the piston compressor are comparatively complex and therefore expensive.

[0010] The object of the invention is to provide an improved method for operating piston compressors in which the one-sided wear or stress on the components of the piston compressor, which is usual in known methods due to the always same direction of rotation, is at least reduced, and in particular avoided.

[0011] This problem is solved by a method and a piston compressor according to the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims. REVELATION OF THE INVENTION

[0012] The invention relates to a method for operating a piston compressor for a motor vehicle, in particular an air spring piston compressor of an air spring system or a sensor cleaning compressed air system of the motor vehicle, wherein at least one compressor piston in a compressor cylinder is driven, at least indirectly, by a drive shaft of a drive motor rotatable about an axis of rotation in at least one direction of rotation in order to compress aspirated air.

[0013] The compressor piston is driven by the drive shaft, in particular by a connecting rod (indirect driving).

[0014] According to the invention, a control device of the drive motor changes the direction of rotation of the drive motor when the drive motor is started, in particular reversing it, depending on at least one definable direction of rotation parameter.

[0015] In the context of the invention, changing or reversing the direction of rotation primarily means that the direction of rotation is now reversed, for example, from counterclockwise to clockwise. An abrupt change in the direction of rotation is not intended; rather, a direction of rotation should be set for each operation when the drive shaft is started, and this direction can be changed with each restart. A change in the direction of rotation can also be made during operation, but this should be achieved by a continuously decreasing speed in one direction until standstill, followed by a continuously increasing speed in the opposite direction, thus ensuring a smooth transition that minimizes stress on the rotational direction.

[0016] According to the invention, the direction of rotation is adjusted during the start-up of the drive motor, depending on environmental influences characterized by the direction-of-rotation parameter, and is changed repeatedly / continuously with each start-up, such that the one-sided wear or stress on the components of the piston compressor, which is typical in known methods, is avoided. This change in the direction of rotation, as provided for in the invention, results in a targeted and uniform load on the piston compressor. This advantageously maintains the performance of the piston compressor for a longer period, improves its operating efficiency—particularly with regard to performance and energy costs—and increases its service life, thereby eliminating the need for a complex and expensive design or concept of the piston compressor optimized for one-sided wear.In particular, one-sided stress on the seal between piston and cylinder housing is significantly reduced by alternating directions of rotation, as the sealing and guiding elements of the piston are worn evenly and not just on one side.

[0017] In principle, the use of the above-discussed concept of the (demand-dependent) reversal of the direction of rotation of a drive shaft can be possible not only in piston compressors, but also in other mechanical piston-cylinder devices, in particular for motor vehicles and / or aircraft, but also heat pumps etc., with at least one drive shaft operable by means of a cylinder-piston arrangement, in particular internal combustion engines, compressors and motors and other or general compressor devices for the hydraulic and / or pneumatic compression of media.

[0018] It is also conceivable to apply the concept according to the invention to piston systems with multiple cylinder-piston units, such as inline engines / compressors, V-engines / compressors, Wankel engines / compressors, boxer engines / compressors, radial engines / compressors and similar.

[0019] In this respect, the invention preferably also relates to a method for operating an internal combustion engine and / or a compressor device or a compressor, wherein at least one compressor element is driven, at least indirectly, by a drive shaft rotatable about an axis of rotation in at least one direction of rotation in order to compress a medium or to perform drive work, whereby the concept according to the invention is implemented.

[0020] According to a preferred embodiment, the direction of rotation parameter takes into account a usage signal, in particular a number of starts signal, a number of revolutions and / or an operating time, wherein the usage signal characterizes a predetermined usage state, in particular a predetermined number of starts and / or a predetermined number of revolutions and / or a predetermined operating time.

[0021] This training therefore concerns a (preset) regular, preferably automatic, alternation of the direction of rotation. The usage signal is taken into account for this.

[0022] The usage signal characterizes the previous use of the piston compressor. In particular, the usage signal includes a previous number of starts of the piston compressor (start count signal). The usage signal can also include a number of revolutions of the drive shaft, preferably separated by direction of rotation, recording how many revolutions have already occurred in the counterclockwise direction and how many revolutions in the clockwise direction. The usage signal can also include an operating time or duration, which is preferably recorded separately for each direction of rotation, analogous to the number of revolutions.

[0023] Regarding the usage signal, it can be implemented that, in principle, a regular alternation of the direction of rotation is performed depending on the number of previous starts, the number of revolutions in each direction, and / or the operating time in each direction. For example, the direction of rotation is changed to the same direction after a definable number of starts, revolutions, and / or operating time upon reaching a defined threshold. Alternatively, actual usage can be recorded separately for each direction of rotation. For example, the number of times the piston compressor was started in reverse, the number of revolutions performed in reverse, and / or the duration of operation in reverse are recorded. Depending on this, the direction of rotation can be changed so that, to ensure even wear, the piston compressor operates in clockwise direction once a certain threshold for reverse operation is reached.Taking the usage signal into account advantageously leads to a fundamental reduction in wear through even wear.

[0024] According to a preferred embodiment, the direction of rotation parameter takes into account an event signal, in particular a sensor signal, user signal, or error signal. This embodiment relates to a deliberate or targeted reversal of the direction of rotation. The event signal is only generated and sent when the corresponding event occurs, whereupon the direction of rotation is changed. The event signal can be, for example, a user input (button actuation), the detection of uneven wear of the piston compressor components, or an error message (for example, a jamming of the drive shaft in the current direction of rotation). The reversal of the direction of rotation occurs, in particular, irregularly or as needed.The service life, performance, and / or operating efficiency of the piston compressor are advantageously further improved as a result. According to a preferred embodiment, the event signal includes a sensor signal that characterizes a mechanical and / or electrical quantity. The mechanical and / or electrical quantity can, for example, be wear of the piston compressor components or a starting current, i.e., the current required to start the drive motor from standstill, which is detected by a suitably designed sensor. Advantageously, this allows the direction of rotation to be optimized for demand or adapted to the current operating conditions.

[0025] According to a preferred embodiment, the sensor signal characterizes a motor current, in particular a starting current, a connecting rod position at the start time of the drive motor, in particular a drive shaft position, and / or a wear condition, wherein the direction of rotation parameter is determined as a function of at least one predeterminable threshold value of the sensor signal. The drive shaft position is the angle of the drive shaft at start-up, from which the position of the connecting rod, via which the compressor piston is indirectly driven by the drive shaft, can be deduced.A wear condition, such as increased leakage of a seal, particularly between two components like the compressor piston and a housing wall of the compressor cylinder, or increased frictional resistance of the piston movement or a bearing ring, can be detected by a decrease in compressed air generation output, an increase in power consumption, or other secondary variables. This further development provides that if the sensor detects that (particularly due to the connecting rod / drive shaft position and / or wear) the starting current required to start the drive motor is higher in the previous direction of rotation, e.g., counterclockwise, than in the other direction, e.g., clockwise, the drive shaft is now rotated in the direction requiring less current during startup. The connecting rod position can also be used to determine...The drive shaft position is determined to ascertain the direction of rotation in which the drive motor would operate against the pressure present in the piston cylinder and thus require more power. Based on this, the direction of rotation can be selected so that the drive motor operates with, rather than against, the compression pressure during startup, thereby requiring less electrical power. Furthermore, as previously discussed, the detected wear to date (in the current direction of rotation) can be taken into account to determine the future direction of rotation. This advantageously leads to further improvements in the service life, performance, and / or operating efficiency of the piston compressor.

[0026] According to a preferred embodiment, the sensor signal of the connecting rod position, preferably an angle of the drive shaft, determines the direction of rotation parameter in a decompression direction of the compressor cylinder within the compressor piston. The decompression direction is the direction of movement of the compressor piston within the compressor cylinder that leads to the intake of air and thus—in contrast to a compression direction opposite to the decompression direction—does not compress the intake air. In other words, as already indicated, the connecting rod position determines which potential direction of rotation of the drive shaft (clockwise or counterclockwise) corresponds to the decompression direction at the start-up point. Thus, for a start, it is determined whether the drive shaft, rotating counterclockwise or clockwise, would rotate the piston in the decompression direction. Based on this determination, the direction of rotation parameter can be adjusted.The resulting direction of rotation is determined or selected such that the drive shaft moves the compressor piston in the decompression direction. This has the advantage that the required starting current for the drive motor is significantly reduced, since the compressor piston does not have to work against a compression pressure – as would be present in the compression direction.

[0027] According to a preferred embodiment, the motor current sensor signal determines the direction of rotation parameter with respect to a minimized starting current. Thus, as previously discussed, the direction of rotation is selected based on the sensor signal such that the starting current required to start the drive motor is as minimal as possible. Advantageously, this allows the piston compressor to be operated with particularly high energy efficiency.

[0028] According to a preferred embodiment, the sensor signal indicating the wear condition, preferably an output or friction condition, operating pressure condition, or operating current behavior, determines the direction of rotation parameter with respect to a minimized wear condition. A wear sensor can be, for example, an operating current, compressed air, or friction sensor. The direction of rotation is selected by the correspondingly determined direction of rotation parameter such that the drive shaft does not rotate in the direction in which increased wear is already detectable. For example, the existing wear is characterized based on the output or friction condition, operating pressure condition, or operating current behavior in a direction of rotation, such as counterclockwise rotation, and it is thus recognized that the compressor output in this direction of rotation is already decreasing due to wear.However, in the other direction of rotation, for example clockwise rotation, wear is reduced, so that a higher compressor output can be achieved compared to the other direction of rotation.

[0029] Accordingly, the direction of rotation is then selected to optimize performance, so that the performance of the piston compressor is advantageously maintained or extended.

[0030] The invention further relates to a piston compressor for a motor vehicle, in particular an air spring compressor of an air spring system or a sensor cleaning compressed air system of the motor vehicle, with at least one compressor piston movable in a compressor cylinder, which can be driven at least indirectly by a drive shaft of a drive motor rotatable about an axis of rotation in at least one direction of rotation in order to compress intake air, and with at least one control device that controls and operates the drive motor.

[0031] According to the invention, the control unit for carrying out the method according to the invention, as described above, is configured. For this purpose, the drive motor is configured as a reversible motor, for example, as a DC or AC motor, or a three-phase motor. In particular, the motor is configured as a DC motor with permanent magnets with a direction of rotation specified by a DC polarity, or as a multiphase AC motor with variable speed based on a direction of rotation. The advantages already mentioned above result from this configuration.

[0032] According to a preferred embodiment, the control unit includes a usage signal generation unit and / or event signal generation unit, which is configured to provide the direction of rotation parameter for generating a direction-of-rotation control current for the drive motor. This direction-of-rotation control current determines or causes the drive shaft to rotate in the intended direction. The control current can influence the direction of rotation of the motor, whether DC or AC, by current polarity control or by specifying a rotating field, for example, using PWM signals. The rotation is initiated by the direction-of-rotation control current. This results in the advantages already mentioned.

[0033] The term "encompass" in this context merely describes a fundamental (functional) assignment, in this case of the usage signal generation unit and / or event signal generation unit to the control unit, and is therefore not limited to an actual physical integration of the usage signal generation unit and / or event signal generation unit into the control unit. In simpler terms, it is sufficient that the usage signal generation unit and / or event signal generation unit are functionally related to or assigned to the control unit in some way, e.g., communicate via signal technology, without necessarily having to be physically connected.

[0034] However, structural integration can of course also be planned.

[0035] According to a preferred further development, a starting count recording device, a revolution count recording device, and / or an operating time recording device are provided within the usage signal generation unit. This results in the advantages already mentioned in this regard.

[0036] According to a preferred embodiment, a sensor signal processing means included in the event signal generation unit is provided for processing a sensor signal of a starting current, an operating current, a connecting rod position, in particular a drive shaft position, and / or a wear condition. The advantages already mentioned above result from this. DRAWINGS

[0037] Further advantages become apparent from the accompanying drawing description. The drawings illustrate exemplary embodiments of the invention. The drawing, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0038] They show: Fig. 1 A simplified schematic cross-sectional representation of an advantageous piston compressor operable according to an embodiment of the method according to the invention, and Fig. 2 a simplified flowchart to discuss an embodiment of an operating method according to the invention.

[0039] In the figures, similar elements are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0040] Fig. Figure 1 shows a simplified cross-sectional representation of an embodiment of a piston compressor 10 according to the invention.

[0041] The piston compressor 10 is designed to generate compressed air and feed it into a downstream system. In this document, the piston compressor 10 is configured as a single- or two-stage air spring piston compressor for an air spring system of a motor vehicle, which is not shown in detail here for the sake of clarity. In this respect, the present piston compressor 10 can be used, in particular, to fill the air spring bellows of the air spring system with compressed air, with the air spring system being the aforementioned downstream system. Alternatively or additionally, the piston compressor 10 can be used in an unspecified sensor cleaning compressed air system.

[0042] The piston compressor 10 has a compressor cylinder 12 or a housing in which a compressor piston 14 is mounted vertically so as to move in a stroke, as shown in Fig. 1 is represented by an arrow 16. The piston compressor 10 further comprises a drive motor 18 arranged externally on the compressor cylinder 12, which is designed to generate a driving force for the stroke movement of the compressor piston 14.

[0043] To transmit the drive force and convert it into the lifting motion, the drive motor 18 is operatively connected to the compressor piston 14 via a rotatably mounted drive shaft 20 and a connecting rod 22. The drive shaft 20 has an axis of rotation 24 about which the drive shaft 20 can rotate in a direction 26, as shown in Fig. 1 represented by a round arrow.

[0044] The compressor piston 14 is thus indirectly coupled to the drive motor 18 via the drive shaft 20 and the connecting rod 22 in order to convert the drive force generated by the drive motor 18 into a reciprocating motion of the compressor piston 14. The drive force generated by the drive motor 18 is transmitted to the drive shaft 20, causing it to rotate about the axis of rotation 24 in the direction of rotation 26. The connecting rod 22, in turn, is mechanically coupled to the drive shaft 20, or in this case, is part of the drive shaft 20, and is designed to translate the rotary motion of the drive shaft 20 generated by the drive motor 18 into the reciprocating motion of the compressor piston 14.

[0045] The piston compressor 10 further comprises an inlet 28 formed in the compressor cylinder 12 or housing, through which air from the surrounding atmosphere can be drawn into the interior of the compressor cylinder 12. The piston compressor 10 also has an outlet 30 formed in the compressor cylinder 12, by means of which the compressed air generated by the piston compressor 10 can be transferred to the downstream system. The inlet 28 and the outlet 30 are fluidically coupled to a piston chamber 32 formed in the compressor cylinder 12, in which the compressor piston 14 is movably mounted. Preferably, for the sake of clarity, (controllable) valves, in particular check valves, are arranged between the inlet 28, outlet 30, and piston chamber 32 to prevent uncontrolled inflow and outflow of air, especially backflow.

[0046] To generate compressed air, the compressor piston 14 is set into a downward movement by means of the drive motor 18, drive shaft 20, and connecting rod 22. This creates a vacuum in the piston chamber 32, which draws air from the surrounding atmosphere into the piston chamber 32 through the inlet 28. A subsequent upward movement of the compressor piston 14 compresses the air previously drawn in within the piston chamber 32 and forces it out of the outlet 30 into the downstream system. This process is repeated until sufficient compressed air has been generated and fed into the downstream system.

[0047] Piston compressors of the type known from the prior art, and thus analogous in design and function, are typically designed such that the corresponding drive shaft can only rotate in one direction, meaning that the direction of rotation of the respective drive shaft is fixed and cannot be changed. Accordingly, known piston compressors typically exhibit one-sided wear, which in known solutions is at least partially compensated for by a corresponding structural design or configuration of the piston compressor.

[0048] In contrast, the piston compressor 10 discussed above is advantageously designed in such a way that the direction of rotation 26 of the drive shaft 20 can be controlled or deliberately changed depending on definable parameters, in this case reversed.

[0049] For this purpose, the present piston compressor 10 has a feature as described in Fig. Figure 1 shows an example of a control unit 34 coupled to the drive motor 18 via a signal connection, which is designed to generate at least one definable direction of rotation parameter 36. Depending on the direction of rotation parameter 36, the direction of rotation 26 of the drive shaft 20 can be selectively reversed when the drive motor 18 is started.

[0050] The direction of rotation parameter 36 can comprise various types of signals that determine the direction of rotation 26 to be effected. In this case, these signals are, in particular, a usage signal and / or an event signal. The control unit 34 has an event signal generation unit 38 and a usage signal generation unit 40, which can generate the respective signal and incorporate it into the direction of rotation parameter 36. The event signal generation unit 38 and the usage signal generation unit 40 also have, for the sake of clarity, not shown in detail here, acquisition and / or processing means for determining and generating the event signal or usage signal.

[0051] Accordingly, the present one is based on Fig. 1 The piston compressor 10 discussed is advantageously operable according to an advantageous method discussed below, in which the direction of rotation 36 of the drive shaft 20 is advantageously changeable or controllable via the direction of rotation parameter 36 when starting the drive motor 18.

[0052] Fig. Figure 2 shows a flowchart illustrating the process.

[0053] The process begins with a first step S1, in which the drive motor 18 is to be started to generate compressed air.

[0054] In a subsequent second step S2, the direction of rotation parameter 36 is determined, based on which, as previously discussed, the direction of rotation 26 of the drive shaft 20 is determined for the subsequent operation of the drive motor 18 or piston compressor 10.

[0055] To determine the direction of rotation parameter 36 in step S2, the usage signal is determined or generated in a first sub-step S2A. Additionally or alternatively, the event signal can be determined or generated in a second sub-step S2B. Depending on the usage signal and / or generation signal, the direction of rotation parameter 36 is then determined in step S2.

[0056] The usage signal encompasses or characterizes the previous use of the piston compressor 10. In this context, the usage signal can, for example, include a start count signal, which characterizes the number of previous starts of the drive motor 18. The usage signal can also include the number of previous revolutions of the drive shaft 20 and / or the operating time or duration of the piston compressor 10. To record the number of starts, revolutions, and / or previous operating time, the usage signal generation unit 40 of the control device 34 has the corresponding recording means mentioned above.

[0057] Depending on the recorded previous starts, revolutions, and / or operating time, and the associated information about how long or how often the drive shaft 20 has already rotated in one direction 26, the usage signal is generated in sub-step S2A. This usage signal defines whether it is now necessary to reverse the previous direction of rotation 26, or to maintain it, when the drive motor 18 is started, due to the previous usage.

[0058] If the determination of the usage signal in step S2A shows that the drive shaft 20 has now been rotated long enough in the previous direction of rotation 26, the usage signal is now generated such that the direction of rotation parameter 36 contained in the usage signal reverses the direction of rotation 26 when the drive motor 18 is started. However, if the usage signal shows that the drive shaft 20 can continue to be rotated in the same direction of rotation 26 as before, the usage signal is generated such that the drive shaft 20 continues to rotate in the same direction of rotation 26 due to the direction of rotation parameter 36 when the drive motor 18 is started.

[0059] Additionally or alternatively, when determining the direction of rotation parameter 36 in step S2, the event signal can be determined and generated in substep S2B. The event signal relates to a targeted reversal of the direction of rotation 26 depending on an event. The event can be, for example, a user input or user signal, or an error signal.

[0060] In particular, the event signal includes a sensor signal that characterizes a mechanical and / or electrical quantity. This mechanical and / or electrical quantity is, for example, a wear condition of the piston compressor 10, but preferably a starting current of the drive motor 18 and / or a position of the connecting rod 22 at the time of start-up.

[0061] The idea here is that the rotation direction parameter 36 is determined via the sensor signal or event signal in such a way that the drive motor 18 requires a minimized starting current during the intended start-up. For this purpose, the position of the connecting rod 22 at the start-up time is determined in particular. The position of the connecting rod 22 is determined via the angle of the drive shaft 20 at the start-up time, from which the position of the connecting rod 22 can be deduced using simple, known mathematical methods.

[0062] To minimize the starting current, the direction of rotation 26 is selected such that the connecting rod 22 is moved in a decompression direction of the compressor piston 14 when the drive motor 18 is started. This means that the compressor piston 14 does not have to move against a pressure prevailing in the compressor cylinder 12, so less work or energy is required for the initial movement of the compressor piston 14, which in turn results in a minimized starting current for the drive motor 18 moving the compressor piston 14.

[0063] To determine or acquire the aforementioned factors necessary for the event signal, in particular the sensor signal, in sub-step S2B, the event signal generation unit 38 of the control device 34 has corresponding sensor signal processing means. Thus, the event signal or the direction of rotation parameter 36 is determined in step S2 in particular such that the direction of rotation 26 is selected so that the drive motor 18 requires a minimal starting current by moving the drive shaft 20 in the direction of rotation 26 that causes a displacement of the compressor piston 14 in the decompression direction.

[0064] Depending on the preceding determination of the direction of rotation parameter 36 in step S2, or the determination and generation of the usage signal (sub-step S2A) and / or event signal (sub-step S2B) influencing the direction of rotation parameter 36, the direction of rotation parameter 36 is subsequently generated and transmitted to the drive motor 18 in a third step S3 following step S2. As previously discussed in detail, the direction of rotation parameter 36 generated and transmitted in step S3 comprises the control command for the direction of rotation 26 of the drive shaft 20.

[0065] Thus, in a subsequent fourth step S4, the drive motor 18 is started based on the direction of rotation parameter 36 with the direction of rotation 26 defined by the direction of rotation parameter 36 and operated until the end of its intended use. At the end of its intended use, the drive motor 18 is switched off.

[0066] The process then restarts with step 1 as soon as further operation and thus a new start of the drive motor 18 is required. A new start can occur when the vehicle is started or when a lower limit pressure of the air pressure system, the main gallery of the air suspension system, or the sensor cleaning compressed air system is undershot. Reference symbol list 10 piston compressor 12 compressor cylinders 14 compressor pistons 16 Arrow 18 Drive motor 20 Drive shaft 22 connecting rods 24 Rotary axis 26 Direction of rotation 28 Admission 30 outlet 32 Piston chamber 34 Control unit 36 Rotation direction parameters 38 Event signal generation unit 40 Usage signal generation unit QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 130 887 A1

[0003]

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