Compressor module, compressed air supply system, and method for operating compressed air supply system having compressor module

Abstract

The invention relates to a compressor module (10), in particular for a compressed air supply system (20) of a vehicle. The compressor module (10) has a compressor (12) and a speed-regulated brushless electric motor (14) for driving the compressor (12). A motor current (IB) occurs during operation of the electric motor (14). The electric motor (14) is associated with motor electronics having an electronic commutator and a rotational speed regulator. The compressor module is connected to or has an electronic control unit (100), the electronic control unit (100) being designed to specify one of at least two different target rotational speeds for the electric motor (14) as a function of the average motor current (IB), the average motor current (IB) is at least one predefined motor current limit value (Imax, red), i.e. At least one predefined first target speed (n1, soll) and a predefined second target speed (n2, soll) which is lower than the predefined first target speed (n1, soll), and switching from the predefined first target speed (n1, soll) to the predefined second target speed (n2, soll) when the average motor current (IB) reaches or exceeds the predefined motor current limit value (Imax, red).

Description

Technical Field

[0001] This invention relates to a compressor module, and more particularly to a compressor module for a compressed air supply system for a vehicle. The invention also relates to a compressed air supply system for a motor vehicle having a compressor module, and a method for operating a compressed air supply system having a compressor module and a speed-regulated electric motor for driving the compressor. Background Technology

[0002] Compressor modules are used, for example, in compressed air supply systems for motor vehicles. In motor vehicles, the compressed air supply system may, for example, supply compressed air to an air spring system with air springs that serves as a compressed air consuming mechanism and / or to a pneumatic braking system with compressed air brakes that also serves as a compressed air consuming mechanism. In order to provide sufficiently high-pressure compressed air to such compressed air consuming mechanisms, a compressor or compressor is required to generate compressed air. Such compressors or compressors are typically driven by electric motors. In this specification, compressor or compressor is used synonymously to refer to a unit that compresses air (i.e., pressurized air).

[0003] Brushless direct current (BLDC) motors are preferred for use as electric motors driving compressors. A brushless DC motor, acting as an internal actuator, typically has a stator equipped with electromagnetic coils (i.e., a coiled stator), a rotor equipped with permanent magnets, and motor electronics. The motor electronics are configured with an electronic commutator, allowing them to be fed to the stator coils (hereinafter also referred to as stator coils) via a power switch. This periodic feeding of the stator coils generates a rotating magnetic field, thereby causing the rotor equipped with permanent magnets to rotate synchronously via magnetic force. Therefore, such a brushless DC motor with a rotor equipped with permanent magnets is also called a PMSM motor, where PMSM stands for Permanent Magnet Synchronous Motor. Sinusoidal commutation brushless electric motors are commonly abbreviated as PMSM, while square wave commutation brushless electric motors are commonly abbreviated as BLDC (Brushless Direct Current). In square wave commutation, the stator coil feed (e.g., three-phase or n×3-phase) is switched digitally, meaning that the individual stator coil or a particular phase stator coil winding has no current or is fully current. In sinusoidal commutation, each stator coil of the motor is fed with a sinusoidal waveform staggered by 120°, thereby obtaining a continuously rotating stator magnetic field with a constant amplitude.

[0004] For known speed regulation of brushless electric motors, these motors have a rotor angle detection mechanism with electronic sensors, such as Hall effect sensors, for detecting the rotor position. This also allows for the detection of the phase angle between the applied rotating magnetic field and the mechanical rotation of the rotor, and the adjustment of the rotating magnetic field's phase angle accordingly. In this way, the behavior of a BLDC motor is similar to that of a mechanically commutated DC motor. However, brushless DC motors are more efficient, experience less wear, and offer better speed regulation than electric motors with brushed commutators.

[0005] In a compressor module used in a compressed air supply system (such as a compressed air supply system for a motor vehicle), the compressor that generates compressed air and the electric motor that serves as the drive form a structural unit. To achieve both efficient and environmentally friendly operation, the design and operation of the electric motor (i.e., a brushless DC electric motor) face unique challenges, primarily including the requirement that the compressor module must provide sufficient compressed air even under rare adverse conditions (the so-called "worst-case" operating conditions). Therefore, the drive (i.e., the brushless DC motor) must be designed accordingly. With the supplied voltage of the brushless DC motor, increased mechanical load, i.e., increased mechanical output power, inevitably leads to increased current consumption of the brushless DC motor. However, to protect the vehicle's onboard electrical system, the maximum current consumption of the brushless DC motor must be limited.

[0006] Referring to document WO2020 / 225024A1, a BLDC motor is known to drive a compressor at a constant speed, and the speed is reduced according to the operating voltage and load (torque) conditions to avoid the motor size being too large. Summary of the Invention

[0007] The objective of this invention is to ensure that the compressor module can operate reliably and environmentally in the simplest possible way.

[0008] This task is solved by proposing a compressor module, specifically for a compressed air supply system for vehicles, as described in claim 1. The compressor module includes a compressor and a speed-regulated brushless electric motor for driving the compressor, wherein a motor current I occurs during operation of the speed-regulated brushless electric motor. B The speed-regulated brushless electric motor is equipped with motor electronics having an electronic commutator and a speed regulator. According to the invention, the compressor module is connected to or has an electronic control unit, wherein the electronic control unit is configured as follows:

[0009] - Depends on average motor current I B Preset one of at least two different target speeds for the electric motor, i.e., at least one predefined first target speed n. 1,solland below the predetermined first target rotational speed n 1,soll The predefined second target rotational speed n 2,soll ,and

[0010] - When the average motor current I B Reaching or exceeding, especially the preset first motor current boundary value I max At that time, from the preset first target speed n 1,soll Switch to the preset second target velocity n 2,soll .

[0011] As a criterion for reducing speed, it is preferable not to consider the instantaneous value of the motor current, but to consider the average motor current that represents the short-time average value of the motor current, so that the speed reduction is not triggered by the short-term current peak or periodic fluctuation of the instantaneous value of the motor current.

[0012] This invention proposes that the motor is designed not only in standard mode to operate at at least two constant speeds depending on the operating voltage and torque requirements (which correspond to the air pressure to be generated), but also preferably with the addition of a functional target current preset or target current limit as an advantageous adjustment parameter. Here, appropriate voltage-dependent current limits (which can also be preset by the vehicle) can protect the vehicle's electrical system and induce condition-dependent overload protection. The result is a superimposed, current-dependent target speed preset, taking into account the respective applicable current boundaries.

[0013] By setting a predetermined lower second target speed when the average motor current reaches or exceeds a preset motor current boundary value (e.g., a first motor current boundary value), the output power can be effectively reduced, and consequently, the average motor current consumed by the brushless electric motor can also be effectively reduced. This effectively avoids overload of the brushless electric motor and / or the vehicle's electrical grid in a simple way. This is because the solution utilizes the motor electronics already present in the brushless electric motor, which includes an electronic commutator and speed regulator. Furthermore, it requires minimal control effort and can be easily achieved in a simple manner. At the predetermined lower second target speed, the compressor module's brushless electric motor can output the required higher torque under special load conditions without exceeding the preset motor current boundary value.

[0014] The advantage of the solution proposed in this invention lies in the fact that the measurement parameter that triggers the preset, pre-defined lower second target speed, i.e., the preset motor current boundary value, is easily detected. This allows the electronic control unit to be designed simply and robustly to control the compressor module. The measures taken when the current boundary value is reached (i.e., the preset, pre-defined lower second target speed) are equally simple and can be easily implemented without additional work, because the brushless electric motor already contains motor electronics for this purpose.

[0015] Another positive effect is that it avoids frequent speed changes in brushless electric motors, thus enabling the compressor module to achieve acoustic optimization within several speed ranges.

[0016] The present invention recognizes that a disadvantage of requiring a constant target speed n (n = constant) is that as the load torque increases, the motor current rises, and in some cases may even exceed the limited motor current I consumed. B The maximum limit, for example, 35A. The advantage of presetting the target speed for speed regulation based on the average motor current is that it eliminates the need to consider worst-case assumptions regarding assembly-specific tolerances, different temperatures, and other factors affecting motor current values. Instead, it allows for independent detection of specific assemblies, thereby minimizing variations in the preset speed to the bare minimum.

[0017] The solution proposed in this invention is simpler than known solutions, in which the electric motor, in standard mode, should be designed with at least two constant speeds based on operating voltage and torque requirements (torque requirements depend on the pressure level to be generated by the compressor). Building upon known solutions, as an alternative and advantageous load-dependent control, at least one preset current boundary value for the average motor current can be set as a criterion for transitioning from a predefined higher first target speed to a predefined lower second target speed.

[0018] Advantageous improvements of the invention are described in the dependent claims, which specifically point out advantageous and feasible solutions that achieve the above-described concept within the scope of the invention's objectives and for other advantages.

[0019] Preferably, two or more target speeds are preset, and the control unit is preferably configured such that when the average motor current (I) B The motor current reaches or exceeds the motor current boundary value or the corresponding preset motor current boundary value (I). max ;I max,red When the target rotational speed n is preset to a higher limit, the rotational speed n is increased. x,soll Accordingly, switch to a preset, lower target speed (n). x+1,sollThe advantage of this variant is that it allows for smaller increments in reducing the target speed and thus the power output of the compressor module, preventing excessively large changes in speed and power. According to one implementation variant, a preset motor current boundary value is established. When this motor current boundary value is first reached under load, the target speed is reduced from a preset first target speed to a preset lower second target speed. If, during operation at the preset lower second target speed, the load further increases and the output torque further increases, causing the preset (first and only) motor current boundary value to be reached again, the target speed can be further reduced from the preset second target speed to a preset lower third target speed. Multiple preset target speeds can be established based on the respective reduction amounts.

[0020] Preferably, the compressor module is designed to be powered by different supply voltages, wherein the control unit is configured to apply different preset motor current boundary values ​​(IC) for different supply voltages. max ;I max,red A particularly advantageous aspect here is that the control unit is configured such that, for its respective voltage value below the boundary voltage value U... v grenz The supply voltage Uv is applied below the preset maximum motor current boundary value I. max Motor current boundary value I max,red For example, the compressor module can be designed to be powered by at least two different supply voltages. The control unit is then configured to preset motor current boundary values ​​for each of the at least two different supply voltages, such that these preset motor current boundary values ​​are different from each other.

[0021] Preferably, the maximum motor current boundary value can be adjusted to one of at least two different maximum motor current boundary values.

[0022] Preferably, the electric motor has:

[0023] - A stator capable of electrical commutation;

[0024] - A permanent magnet rotor; and

[0025] - Motor electronics, preferably forming a speed-regulating electronic commutator, which adjusts the rotational speed according to a preset target rotational speed n. soll To generate a rotating electric field for an electric motor.

[0026] Preferably, the compressor module has a motor current I for detecting the motor current consumed by the electric motor. B A current sensor and a method for converting the output value provided by the current sensor into an average motor current I representing the electric motor's consumption.B An analog-to-digital converter for digital signals. Current sensors, typically provided for each phase in motor electronics, can be used as current sensors. The average motor current can be generated by motor electronics at the compressor module or by the compressed air control unit. For example, the motor electronics can determine the average motor current based on the measured three-phase currents. Alternatively, additional current sensors can be provided.

[0027] The average motor current is the average motor current over a period of several seconds and / or a low-pass filtered value of the motor current. By generating a short-term average motor current or a low-pass filtered value, it is possible to avoid speed drops caused by short-duration motor current peaks. To transmit the motor current value, the compressor module has an interface through which a digital signal representing the motor current consumed by the electric motor can be retrieved during operation. The average motor current can be generated within the compressor module.

[0028] Another advantage is that the electric motor is designed to deliver maximum expected torque even with a supply voltage as low as 11.5V, without exceeding the preset motor current limit. This avoids unnecessary and frequent switching to lower target speeds.

[0029] Another aspect of the present invention relates to a compressed air supply system according to claim 9. The compressed air supply system for a motor vehicle comprises:

[0030] - Compressor module;

[0031] - At least one compressed air consuming mechanism, especially an air spring system or a braking system;

[0032] - Compressed air storage tank;

[0033] - Controllable valves; and

[0034] - Compressed air control unit used to control valves.

[0035] Preferably, the compressed air supply system is configured to switch between open and closed operation.

[0036] Another aspect of the present invention relates to a method according to claim 11. A method for operating a compressed air supply system having a compressor and a speed-regulated electric motor for driving the compressor, comprising the steps of:

[0037] - Preset, limited first target rotational speed;

[0038] - Periodically or continuously compare each current value of the average motor current with a predefined maximum motor current boundary value; and

[0039] - Once each current value of the average motor current is greater than or equal to the preset maximum motor current boundary value, a preset second target speed lower than the preset first target speed is set.

[0040] The concept of this invention is not limited to compressed air supply systems or compressed air consuming mechanisms in vehicles, such as compressed air brakes in air spring or braking systems that have an air spring system for generating compressed air and an air spring system using a regulated brushless electric motor. Specifically, the method based on this invention can serve as a general approach for operating a regulated brushless electric motor at a constant speed within different load ranges.

[0041] Embodiments of the invention will now be described in conjunction with the accompanying drawings. These drawings are not necessarily to scale; rather, they are shown schematically and / or with slight modifications for illustrative purposes. Reference is made to the relevant prior art in light of the teachings readily apparent from the drawings. It should be understood here that various modifications and alterations to the form and detail of the embodiments can be made without departing from the overall concept of the invention. The features disclosed in the specification, drawings, and claims can be modified substantially both individually and in any combination. Furthermore, all combinations of at least two features disclosed in the specification, drawings, and / or claims fall within the scope of the invention. The overall concept of the invention is not limited to the exact form or details of the preferred embodiments shown and described below, nor to any subject matter limited compared to the subject matter claimed in the claims. Values ​​within the limits set forth in the invention should also be considered boundary values ​​of this disclosure and can be applied arbitrarily and claimed. Attached Figure Description

[0042] Other advantages, features, and details of the invention will be illustrated by the following description of preferred embodiments and with reference to the accompanying drawings; in the drawings:

[0043] Figure 1 A compressor module with a compressor, an electric motor, and motor electronics is shown.

[0044] Figure 2 A wiring diagram of an example of a vehicle's compressed air supply system and a compressed air consumption mechanism in the form of an air spring is shown.

[0045] Figure 3 It shows the use of Figure 2 The symbols for the valves shown are used to illustrate their functions;

[0046] Figure 4 A simplified diagram illustrating the function of a brushless electric motor is shown.

[0047] Figure 5Symbol diagrams of a compressor, a brushless electric motor driving the compressor, and its motor electronics are shown.

[0048] Figure 6 A diagram is shown to illustrate how, in the prior art, switching from a preset higher target speed to a predetermined lower target speed depends on operating voltage and load.

[0049] Figure 7 a diagram illustrates how, according to the present invention, a switch from a preset higher target speed to a predetermined lower target speed is made when a preset motor current boundary value is reached.

[0050] Figure 7 b shows a variation of the present invention, which switches from a preset higher target speed to a predetermined lower target speed when a preset motor current boundary value is reached.

[0051] Figure 8 A diagram is shown illustrating another variation of the present invention, which switches from a preset higher target speed to a predetermined lower target speed when a preset motor current boundary value is reached.

[0052] Figure 9 A diagram is shown illustrating another variation of the present invention, which switches from a preset higher target speed to a predetermined lower target speed when a preset motor current boundary value is reached.

[0053] Figure 10 A diagram is shown illustrating another variation of the present invention, which switches from a preset higher target speed to a predetermined lower target speed when a preset motor current boundary value is reached. Detailed Implementation

[0054] See Figure 1 The compressor module 10 can be configured to consist of a compressor 12, an electric motor 14, and motor electronics 16 (see [link]). Figure 5 ; Figure 1 The structure unit, which is typically directly connected via a flange to an electric motor 14, and other components such as an air dryer 18 and an air distributor 20, is not shown in the diagram.

[0055] Compressor module 10 is configured for use in compressed air supply system 30, such as Figure 2 Refer to the wiring diagram. The compressed air supply system 30 is used, for example, to supply compressed air to an air spring system 32 of a vehicle having multiple air springs 34. In addition to the air spring system, other compressed air consuming mechanisms (such as the compressed air brakes of a compressed air braking system) may also be pneumatically connected to the compressed air supply system 30.

[0056] Figure 2 The compressed air supply system 30 shown can operate in either open or closed operation. In open operation, it draws in ambient air and compresses it (see...). Figure 2 (dashed arrow in the text); In closed-loop operation, air is drawn from pressure vessel 36 (also referred to herein as the storage tank) and compressed (see...). Figure 2 (The dotted arrow in the text). In open operation, the outside air is compressed in two stages: first, it is pre-compressed by compressor 12.1, and then it is re-compressed by compressor 12.2. Since the air in pressure vessel 36 already has a higher static pressure than the outside air in the environment, in closed operation, the air is re-compressed only by compressor 14.2.

[0057] In both cases, compressed air is ultimately delivered to the pneumatic main pressure line 40 via the air dryer 38, and guided through the check valve or check valve 42.2 and thus supplied to the air spring system 34 or delivered to the pressure vessel 36 for output.

[0058] The supply of compressed air to the air spring system 32 or the compressed air container 36, as well as the distribution of compressed air within the air spring system 32 (in the example case, the distribution of compressed air between the air springs 34 of the air spring system 32), are both achieved by means of an electrically controlled two-position two-way valve 50 (see also...). Figure 3 a) In its first (resting) position, actuated by the return spring 42, the two-position two-way valve 50 functions as a check valve or a one-way valve. In its second (operating) driven position, the two-position two-way valve 50 opens. The electrically driven two-position two-way valve 50 is connected to an electronic control unit (not shown), which may be the same as the electronic control unit used to control the compressor module 10 and can drive the control magnet 54 of the two-position two-way valve 50.

[0059] The compressed air supply system 30 and spring system 32 can be vented by opening the exhaust valve 56, which is also an electrically driven two-position two-way valve. Opening the exhaust valve 56 actuates the pneumatically controlled two-position three-way valve 60 (e.g., Figure 3 (b) The valve moves to the working position. The working position is the position for venting. Here, the pressure of the air to be vented is used as the control pressure, which acts on the control piston 54, causing the two-position three-way valve 60 to move to the working position against the force of its return spring 52. Throttling elements 70.1 and 70.2, as well as an additional check valve or one-way valve 42.2, facilitate the reasonable limitation of the control pressure used to drive the pneumatic control of the two-position three-way valve 60.

[0060] Figure 4The stator and rotor of a brushless DC motor are briefly described. The brushless DC motor 14 shown, as a so-called internal mover, typically has a stator 14.1 equipped with electromagnetic coils (i.e., coiled), a rotor 14.2 equipped with permanent magnets, and motor electronics 16 (see [link to motor electronics]). Figure 5 The motor electronics 16 is configured as an electronic commutator so that the motor electronics 16 controls the current supply to the stator coil 143 of the stator 14.1 via power switches and terminals A, B, C, thereby periodically supplying current to the stator coil 14.3 to generate a rotating magnetic field, thereby causing the rotor 14.2 equipped with permanent magnets to rotate synchronously via magnetic force.

[0061] For known speed regulation of the brushless electric motor 14, the motor has a mechanism for rotor angle detection, such as a Hall sensor 14.4 for detecting rotor position. Therefore, the phase angle between the applied rotational field and the mechanical rotation of the rotor 14.2 can also be detected, and the phase angle of the rotational field can be adjusted accordingly. In this way, the BLDC motor 14 behaves similarly to a mechanically commutated DC motor, but as a brushless DC motor, it is more efficient, experiences less wear, and can be better regulated in speed than an electric motor with a brushed commutator.

[0062] To generate a rotating field by periodically energizing the stator coils 14.3 via terminals A, B, and C, motor electronics 16 are configured as an electronic commutator; see also Figure 5 .

[0063] The motor electronics 16 also regulates the speed of the electric motor 14 in a known manner. For this purpose, a target speed is preset for the motor electronics 16. To preset the target speed, an electronic control unit 100 is provided, to which the motor electronics 16 supplies an average value of the motor current, or the electronic control unit is connected to a current sensor 102, which detects the motor current consumed by the electric motor 12 during operation.

[0064] The current consumption of the electric motor 12 can be calculated by the motor electronics 16 based on the measured phase current, or it can be directly measured using a current sensor. In the first case, three current sensors are required for the motor electronics, which is essential for operational safety. Therefore, a variant without a separate current sensor is preferred.

[0065] The electronic control unit 100 is configured to depend on the average motor current I B Knowing and / or presetting one of at least two different target speeds for the electric motor 14, i.e., at least one predefined first target speed n 1,soll and below the predetermined first target rotational speed n 1,soll The predefined second target rotational speed n 2,sollAnd when the average motor current I B The motor current reaches or exceeds the preset current boundary value I. max Or I max,red At that time, from the preset first target rotational speed n 1,soll Switch to the preset second target rotational speed n 2,soll .

[0066] The compressor module 10 has a motor current I for detecting the motor current consumed by the electric motor 14. B At least one current sensor 102 and for converting the output value provided by the current sensor 104 into a motor current I representing the electric motor 14 consumed by the electric motor 14. B An analog-to-digital converter 104 is used to convert digital signals. An interface 106 allows the use of a digital signal representing the motor current consumed by the electric motor during operation. Preferably, the motor current I represented by the digital signal is... B The motor current is already averaged over time or filtered by a low-pass filter.

[0067] Figure 6 This indicates that when the supply voltage U is lower than the preset higher target speed n, the speed will decrease. nominal Switch to the predetermined lower target speed n red,stat See reference WO2020 / 225024A1.

[0068] In existing technologies, depending on the efficiency of each electric motor, the motor switches to a lower target speed before reaching the maximum permissible motor current. For example, when the switching occurs at a 12V supply voltage, the least efficient electric motor has already reached its maximum permissible motor current, while the more efficient electric motor consumes significantly less motor current at the same supply voltage and load.

[0069] Specifically, Figure 6 This explains that the "lowest efficiency compressor (WoCo)" exhibits maximum permissible current consumption when the supply voltage is ≤12V, therefore the speed needs to be reduced at 12V. The "medium efficiency compressor (MeCo)" exhibits maximum permissible current consumption when the supply voltage is ≤11V, therefore the speed needs to be reduced at 11V. The "highest efficiency compressor (MoCo)" exhibits maximum permissible current consumption when the supply voltage is ≤10.5V, therefore the speed needs to be reduced at 10.5V.

[0070] The solution proposed in document WO 2020 / 225024 A1 requires switching to a lower speed based on the load and supply voltage so that the "least efficient compressor" does not exceed the maximum motor current. As a result, all the "better" compressors switch to a lower second speed earlier than needed, inevitably leading to a decrease in compressor performance throughout the vehicle.

[0071] If the nominal conditions are temporarily exceeded or the customer reduces the maximum current according to the operating conditions, the method proposed in document WO2020 / 225024 A1 is insufficient to meet the requirements.

[0072] Generally speaking, as the compressor supply voltage U decreases or the mechanical load (compressor drive torque M) increases, while the compressor speed is still required to remain constant, the compressor current will increase. This is because the mechanical power of the compressor module and the electrical power consumed satisfy the following relationship:

[0073] M×2π×n = η×U×I

[0074] in:

[0075] M = Compressor driving torque (constant under constant pressure)

[0076] n = Compressor speed (constant preset and adjustable)

[0077] η = Motor efficiency

[0078] U = Supply voltage (which can vary between 9V and 16V as needed)

[0079] I = Motor current

[0080] The power supply voltage is the voltage of the vehicle's electrical grid and is typically between 9V and 16V. For example, according to regulations, the maximum permissible motor current is limited to 35A.

[0081] Figure 7 The image above ( Figure 7 a) The current I increases as the voltage U decreases. In this example, the current I reaches the boundary I at a voltage of 11V. max (Point (1)), the compressor speed n is always equal to the first target speed n nominal , corresponding to n 1,soll Referring to document WO2020 / 225024 A1, the known solution proposes that, under an 11V supply voltage (point 1), the compressor speed drops to a reduced second speed n. 2,soll (also known as n) red,stat If the operating voltage U drops further, the current consumption of the electric motor (which initially decreases due to the reduced speed) will rise again, reaching I again at 9V. max (Point 1a).

[0082] In this prior art, a voltage boundary for reducing the speed is determined via parameterized static determination, which is 11V in this case. This also applies to all operating conditions and compressors.

[0083] When switching is based on a preset motor current boundary value according to the present invention, the operating voltage when switching to a lower target speed is variable.

[0084] Figure 7 a and Figure 7 b explains how to reasonably preset the motor current boundary value and how it affects the motor's operating behavior.

[0085] Figure 7 a explains the current value I that may occur due to factors such as discrete or rare operating conditions. max The first case is when the value exceeds the user-preset boundary value. In this case, I... max I represents the current generated by the compressor currently in use under the current operating conditions. max,red This is the maximum static current allowed by the user. The shaded area indicates an operating condition that violates the current consumption allowed according to the user specifications.

[0086] Figure 7 a indicates that the user requires a lower boundary value I based on operating conditions or for a specific vehicle. max,red The first case where dynamic presets can also be performed.

[0087] Here, compliance with the defined current boundaries is ensured by implementing an additional target rotational speed, in the following example where these speeds are n. red,stat_1 and n red,stat_2 .according to Figure 7 The embodiment shown in b defines three speed ranges, thereby obtaining two switching voltages.

[0088] However, because the switching is based on the average motor current rather than a preset voltage (switching voltage), the electric motor can operate more efficiently. For example, if the compressor's power consumption decreases due to operation at an altitude of 3000 meters (and consequently the required motor current decreases), this method allows the maintenance of the first target speed n. nominal Until a significantly lower operating voltage is reached. Figure 8 In the example, the solid line represents the current consumption when operating at an altitude of 3000 meters. When applying the current boundary I... max,red In this case, reducing the speed once at 9.8V is sufficient to not exceed the maximum current.

[0089] Figure 8 It also uses zigzag dashed lines to illustrate how to preset corresponding target speeds and related speed abrupt changes to reduce adaptive speed selection. For example, the first target speed n nominal (n) 1,soll The second target speed n can be 3000 rpm. red,stat_1 (n) 2,sollThe third target speed n can be further reduced to 2800 rpm. red,stat_2 (n) 3,soll The target speed can be 2600 rpm, with a further reduction to the fourth target speed n. red,stat_3 (n) 4,soll The speed can be 2400 rpm.

[0090] Figure 9 a, Figure 9 b and Figure 10 An example of a further advantageous implementation of the variant is shown.

[0091] To protect the vehicle's electrical grid, the maximum allowable reduction in compressor current, i.e., the reduction in motor current boundary value I, can be set based on the vehicle's electrical grid voltage. max,red A function limited to the operating voltage provided by the vehicle's electrical grid:

[0092] I max,red = f(supply voltage U).

[0093] This reduction in motor current boundary value can be requested by the vehicle's central controller or implemented independently by the compressor controller. Figure 9 a and Figure 9 b exemplarily illustrates the voltage-dependent allowable current I max For example, the motor current boundary value I decreases linearly from the supply voltage U=12.2V to the supply voltage U=9V. max,red By applying these motor current boundary values, switching voltages such as 11.8V, 10V, and 9.2V can be obtained; see [link to relevant documentation]. Figure 9 b.

[0094] Figure 10 Another alternative implementation variation is described: by pre-setting an appropriate combination of motor current boundary values ​​and target speed, no sudden changes in speed occur when operating within the most common voltage range in vehicles (e.g., 12V to 13.5V). Accordingly, the electric motor is designed to deliver maximum expected torque even at supply voltages as low as 11.5V without exceeding the motor current boundary values.

[0095] Furthermore, for acoustic reasons, when the operating voltage is higher than, for example, 13.5V, it is preferable not to approach the maximum current boundary and proceed without correspondingly increasing the speed; instead, a constant speed strategy is adopted here.

[0096] Figure 10Different operating ranges are described. Within the range 5a to 5, compressor module 10 operates according to a "constant speed" strategy. The target speed is the same as the speed in the preferred voltage range 5 to 5b. Within the range 5 to 5d, compressor module 10 operates according to a "target current limiting" strategy. Parameterizing the target speed avoids sudden speed changes that occur in the most common voltage ranges (5b to 5).

[0097] Reference numerals (part of the instruction manual)

[0098] 10 compressor modules

[0099] 12 compressors

[0100] 14 electric motors

[0101] 14.1 Stator

[0102] 14.2 Rotor

[0103] 14.3 Stator Coils

[0104] 14.4 Hall sensor

[0105] 16 Motor Electronics

[0106] 18 Air Dryer

[0107] 20 air distributors

[0108] 30 Compressed Air Supply System

[0109] 32 air spring system

[0110] 34 air springs

[0111] 36 Compressed Air Storage Tank

[0112] 38 Air Dryer

[0113] 40 main pressure line

[0114] 42.2 Check valve / one-way valve

[0115] 50 Two-way valve

[0116] 42 (Reset spring of 2-position 2-way valve 50)

[0117] 44 (Control magnet of 2-position 2-way valve 50)

[0118] 56 exhaust valve

[0119] 60 Two-position Three-way Valve

[0120] 52 (reset spring for 60 two-position three-way valve)

[0121] 54 (2-position 3-way valve 60) control piston

[0122] 70.1 and 70.2 throttling components

[0123] 100 control unit

[0124] 102 Current Sensor

[0125] 104 Analog-to-Digital Converter

[0126] 106 interface

Claims

1. A compressor module (10) for a compressed air supply system (20) particularly for vehicles. in, The compressor module (10) has: - Compressor (12); and - A speed-regulated electric motor (14) for driving the compressor (12), preferably a brushless electric motor, wherein a motor current (I0) occurs during operation of the electric motor. B The electric motor is equipped with motor electronics (16) having an electronic commutator and a speed regulator. Its features are, The compressor module (10) is connected to or has an electronic control unit (100), wherein the electronic control unit (100) is configured to: - Depends on average motor current (I B The electric motor (14) is preset with at least two different target speeds, namely at least one predefined first target speed (n). 1,soll and below the predetermined first target rotational speed (n) 1,soll The predefined second target rotational speed (n) 2,soll ),and - When the average motor current (I B The current reaches or exceeds the preset motor current boundary value (I). max ;I max,red When, from the preset first target rotational speed (n) 1,soll Switch to the preset second target rotational speed (n) 2,soll ).

2. The compressor module (10) according to claim 1, wherein two or more target speeds are preset for the compressor module, wherein, The control unit (100) is configured such that when the average motor current (I) B The current reaches or exceeds the preset motor current boundary value (I). max ;I max,red When starting from a preset, higher target rotational speed (n), x,soll Switch to a preset, lower target speed (n) x+1,soll ).

3. The compressor module (10) according to claim 1 or 2, wherein the compressor module is capable of being powered by at least two different supply voltages (Uv), wherein, The control unit (100) is configured to preset predetermined motor current boundary values ​​(I0) for at least two different supply voltages (Uv). max ;I max,red ), wherein, for the at least two different supply voltages (Uv), the predefined motor current boundary value (I) max ;I max,red They are different from each other.

4. The compressor module (10) according to claim 3, wherein, The control unit (100) is configured to, for each voltage value below a boundary voltage value (U v grenz The supply voltage (Uv) is applied below the preset maximum motor current boundary value (I). max The reduced motor current boundary value (I) max,red ).

5. The compressor module (10) according to at least one of claims 1 to 4, wherein, The maximum motor current boundary value (I) max It can be adjusted to at least two different, preset maximum motor current boundary values ​​(I). max I max,red )one.

6. The compressor module (10) according to at least one of claims 1 to 5, wherein, The electric motor (14) has - Stator with electric commutation (14.1). - Permanent magnet rotor (14.2), and - The motor electronics (16), the motor electronics at least form a speed-adjustable electronic commutator, the electronic commutator according to a preset target speed (n soll ) generates a rotating electric field for the electric motor (14).

7. The compressor module (10) according to at least one of claims 1 to 6, the compressor module comprising: at least one current sensor (102) for detecting the current (I0) consumed by the electric motor (14). B ); Analog-to-digital converter (104), the analog-to-digital converter being used to convert the current (I) provided by the current sensor (102) representing the current consumed by the electric motor (14) into digital signals (I0). B The output value of ) is converted into the current (I) consumed by the electric motor (14). B The digital signal of the electric motor (14); and an interface (106) via which a digital signal representing the current consumed by the electric motor (14) can be invoked during operation.

8. The compressor module (10) according to at least one of claims 1 to 6, wherein, The electric motor (14) is designed such that it can provide maximum expected torque even at supply voltages as low as 11.5V without exceeding the motor current boundary value (I0). max I max,red ).

9. A compressed air supply system (30) for a motor vehicle, said compressed air supply system having: - Compressor module (10) according to any one of claims 1 to 8; - At least one compressed air consuming mechanism (34), especially an air spring system (32) or a braking system; - A controllable valve (50); and - Compressed air control unit (36) for controlling the valve (50).

10. The compressed air supply system (30) according to claim 9, wherein the compressed air supply system has a compressed air storage tank (36) and is capable of switching between open and closed operation.

11. A method for operating a compressed air supply system (30) having a compressor (12) and a speed-regulated electric motor (12) for driving said compressor (12), wherein, The method includes the following steps: - Preset first target rotational speed (n) 1,soll ); - Periodically or continuously measure the average motor current (I) consumed by the electric motor (14) during operation. B The current values ​​of each of the following are compared with the predefined maximum motor current boundary value (I). max ;I max,red ) for comparison; - Once the average motor current (I) B Each of the current values ​​of ) is greater than or equal to the preset maximum motor current boundary value (I) max If the preset rotational speed is lower than the predefined first target rotational speed (n), then the rotational speed will be lower than the predefined first target rotational speed (n). 1,soll The predefined second target rotational speed (n) 2,soll ).

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