Method for detecting wear of a compressed air supply device of a motor vehicle

Abstract

The invention relates to a method for detecting wear of a compressed air supply device of a motor vehicle, wherein, as part of a first wear phase (S1), a first group of operating parameters (P1) is monitored, and, after a threshold value (T1) of a predefined operating parameter of the first group (P1) is exceeded for the first time, as part of a second wear phase (S2), a second group of operating parameters (P2) is monitored, and the first group of operating parameters (P1) is further monitored.

Description

[0001] 202405867

[0002] 1

[0003] Method for detecting wear in a compressed air supply system of a motor vehicle

[0004] The invention relates to a method for detecting wear in a compressed air supply system of a motor vehicle according to the preamble of claim 1.

[0005] Compressed air systems in motor vehicles, such as air suspension systems, use a compressed air supply unit to generate compressed air. These systems are typically designed to last the entire lifespan of the vehicle based on a defined usage profile. The wear limits of the components are designed according to this usage profile, and replacement of components due to premature wear is not intended. Therefore, load or wear counters are usually used to analyze actual usage during vehicle operation.

[0006] However, compressed air systems and supply units are being used more frequently than previously anticipated, resulting in increased utilization. The consequent increased need for control of special functions or high-frequency use of the compressed air system leads to premature wear of system components. In particular, the electric motor and compressor of the compressed air supply unit, as well as electromagnetic switching valves, are affected by this premature wear.

[0007] Due to the highly variable usage patterns of a vehicle with an air suspension system, accurately predicting the service life and implementing a corresponding schedule for component replacement is difficult and hardly practical. Simply looking at the wear and load counters provides only a rough picture of the actual condition. The vehicle operator cannot detect when the wear limit is reached. This creates the risk of an unplanned system failure or, conversely, of prematurely replacing components, which is uneconomical. 202405867

[0008] 2

[0009] To determine the wear of a compressor in a compressed air system, a method is known from DE 10 2019 214 858 A1, whereby an operating temperature of the compressor is determined, which is used as a criterion for operating the compressor until a cut-off temperature is reached, whereby a duty cycle until the cut-off temperature is reached is determined and the determined duty cycle is calculated with a parameter that depends on the cut-off temperature reached.

[0010] This method is based on the principle that, under high operating parameters, a higher shutdown temperature than the compressor's nominal shutdown temperature must be selected to ensure sufficient compression runtime for the desired control process. This results in higher compressor availability. However, during extended operation, the compressor enters a critical temperature range where its components can be damaged or begin to wear out. Conversely, under favorable or low operating parameters, a lower shutdown temperature than the nominal shutdown temperature can be selected while still maintaining acceptable compressor availability. On the other hand, this approach does not effectively utilize the maximum possible component load capacity.This is achieved by recording the duty cycle duration of the compression run and calculating it using a parameter that depends on the reached shutdown temperature. This parameter represents a degree of wear that occurs on the compressor components when they are operated up to the respective shutdown temperature. Thus, a weighted duty cycle is obtained for each compression run, which can be used for service life monitoring. This weighted duty cycle allows for a good estimation of compressor wear. This method increases the availability and reliability of the compressor. However, this method only considers the compressor's operating temperature. The compressed air supply unit comprises a multitude of electronic and mechanical components that can wear out, making a more holistic approach advisable. 202405867.

[0011] 3

[0012] The object of the invention is to provide a method for detecting wear of a compressed air supply system of a motor vehicle, which enables the most realistic possible detection and diagnosis of the wear condition of the compressed air supply system.

[0013] The problem is solved using the features of an independent patent claim.

[0014] According to the invention, a method for detecting wear of a compressed air supply system of a motor vehicle is provided, wherein, in a first wear phase, a first group of operating parameters is monitored, and after a first exceedance of a threshold value of a predefined operating parameter of the first group, in a second wear phase, a second group of operating parameters is monitored, and further monitoring of the first group of operating parameters is carried out.

[0015] This method allows for a more precise detection and diagnosis of the actual wear of the compressed air supply system, ensuring its operation even under excessive usage and preventing premature replacement. By selecting specific operating parameters, the wear of components such as the electric motor, compressor pistons and piston seals, or solenoid valves can be determined, as these are crucial for the optimal operation of the compressed air supply system. The at least two-stage wear monitoring provides a quantitative assessment of the compressed air supply system's wear.

[0016] An electronic control unit totals and stores the operating parameters as wear counters during the operation of the compressed air supply system. A comparison of the actual wear counter readings with predefined target wear limits (thresholds) is performed. This involves comparing the absolute values ​​of the actual wear with the target wear limits. In this way, the relative change in the wear counter readings over the operating time is determined.

[0017] 4. Compare with corresponding reference values ​​from a certain point in time. These reference values ​​can be predefined values ​​and / or reference values ​​determined during operation.

[0018] The exemplary multi-stage wear monitoring system is based on direct and indirect wear counters. Operating parameters of the first group, or direct wear counters, include, among others, the operating times and start-up times of the compressor in the compressed air supply system, the switching cycles of the electromagnetically actuated switching valves, and the operating time of the electronic control unit.

[0019] Operating parameters of the second group, or indirect wear counters, include, for example, the compressor's delivery rate or filling time. The corresponding limit or limit is the compressor's delivery rate or the resulting filling time for filling a component of the air suspension system whose filling volume is known, e.g., the filling time of the pressure accumulator. In the further course of the wear procedure, from a defined operating time point, a relative comparison of the delivery rate or filling time is made with a predefined and / or additionally determined reference value.

[0020] Another indirect wear indicator is the current draw. The current draw of the compressor motor is measured and compared to a maximum current draw limit. From a certain point in the wear measurement process, the current draw is compared relative to a predefined and / or additionally determined reference value obtained during operation.

[0021] The variation in maximum current consumption and the current integral, as well as the product of current consumption and running time of the compressor motor, also serve as indirect wear counters.

[0022] Another indirect indicator of wear is the operating pressure range and the operating temperature range. 202405867

[0023] 5

[0024] The exemplary wear process is therefore divided into several stages or phases. In the first wear phase, the break-in phase, the absolute wear counters are monitored, i.e., the running or switching times of the compressor, the switching cycles and current consumption of the compressor's subcomponents, such as switching valves and electric motor, as well as the switching on of the electronic control unit and ignition change.

[0025] In the second wear phase, passive wear monitoring, after exceeding a first threshold value of an absolute wear counter of the break-in phase, monitoring of the absolute wear counters of the break-in phase and additionally monitoring of indirect wear counters, such as the monitoring of the compressor performance (delivery rate or filling time) under defined vehicle and environmental boundary conditions during normal system activity, e.g. during storage pressure filling from the environment in a defined temperature, supply voltage, and pressure range.

[0026] Furthermore, reference values ​​for the indirect wear counters are determined and set. The relative comparison of the indirect wear counters is activated to monitor changes during further operation, based on predefined values ​​and / or the set reference values ​​determined during operation.

[0027] The third active wear phase occurs after a further threshold value of the direct or passive wear counters is exceeded. In this stage, a wear warning is issued. Additionally, diagnostic services are activated, which can be accessed automatically or manually by the operator via a defined functional test under defined vehicle and environmental conditions within a defined temperature and supply voltage range. The results of these additional functional tests can determine the wear state more precisely and validate the results obtained during operation. The remaining operating time of the compressed air supply system is also displayed. 202405867

[0028] 6

[0029] Once a wear counter exceeds a third threshold, the process enters the fourth active wear stage. An extended diagnostic check is performed, and a warning is issued indicating the need to replace the compressed air supply unit or its components, taking into account a predefined minimum remaining service life. The remaining service life is also displayed.

[0030] Further preferred embodiments are shown in the dependent claims and in the following description of an exemplary embodiment with reference to the figure.

[0031] Figure 1 shows a diagram of an example of wear detection for a motor vehicle's compressed air supply system with multiple phases S1, S2, S3, and S4. The first wear phase, S1, is present at the beginning of the process (and thus also at the beginning of the compressed air supply system's operation). This first wear phase, S1, can also be referred to as the break-in phase. While the process or the compressed air supply system is in the first wear phase, S1, a first group of operating parameters, P1, is monitored by the system. This non-exhaustive first group of operating parameters, P1, includes the operating time, the usage profile, the switching cycles of actuators, the switching cycles of the electronic control unit, and the absolute switching time. Corresponding threshold values, T1, or limit values ​​are assigned to the first operating parameters, and the system monitors whether these threshold values ​​are exceeded.The system checks whether thresholds have been exceeded, a time period has elapsed, or switching cycles have been reached. If the threshold of a predefined operating parameter in the first group is exceeded, the first wear phase S1 ends, and the process transitions to a second wear phase S2. This wear phase S2 represents passive wear detection. It includes a second group of non-exhaustive operating parameters P2, and additionally, the continued monitoring of the operating parameters of the first group P1. The second group of operating parameters P2 includes the compressor's delivery rate, which is shown in the 202405867.

[0032] 7

[0033] Compressor performance and a comparison to the compressor's reference values. The second group of operating parameters P2 also has corresponding threshold values ​​T2, exceeding which terminates the second wear phase S2. This checks whether limits have been violated, whether the compressor performance has decreased, and whether an acceptable tolerance to the reference values ​​has been exceeded. The procedure then transitions to active wear detection with a third wear phase S3. Here, the criteria of the second wear phase S2 continue to be monitored, and a cyclical diagnostic check D1 of the compressor performance is additionally performed. The system continues to check whether critical threshold values ​​T2 of the second group of operating parameters P2, which indicate insufficient compressor performance, are exceeded. Furthermore, it observes whether acceptable tolerance values ​​have been significantly exceeded compared to reference values.Furthermore, a critical wear warning W1 is issued. If a threshold value T1 or T2 of a predefined operating parameter of the first or second group P1 or P2 is exceeded a third time, the third wear phase S3 ends and the procedure transitions to the fourth wear phase S4. This essentially corresponds to an active wear warning to the vehicle operator. A warning message W2 is issued to replace the compressed air supply system. During this phase, extended diagnostics are performed and the remaining service life is determined. If further monitoring of the operating parameters of the first and / or second group P1 or P2 reveals another exceedance of a predefined threshold value, the operation of the compressed air supply system is actively stopped.

[0034] 202405867

[0035] 8

[0036] Reference symbol list

[0037] D1 diagnosis

[0038] D2 extended diagnosis

[0039] P1 first group of operating parameters

[0040] P2 second group of operating parameters

[0041] 51 first wear phase

[0042] 52 second wear phase

[0043] 53 third wear phase

[0044] 54 fourth wear phase

[0045] T1 Threshold values ​​of the first group of operating parameters

[0046] T2 Thresholds of the second group of operating parameters

[0047] W1 Wear Warning

[0048] W2 replacement warning

Claims

202405867 9 Patent claims 1. Method for detecting wear of a compressed air supply system of a motor vehicle, characterized in that, during a first wear phase (S1), a first group of operating parameters (P1) is monitored, and after a first exceedance of a threshold value (T1) of a predefined operating parameter of the first group (P1) during a second wear phase (S2), a second group of operating parameters (P2) is monitored, and further monitoring of the first group of operating parameters (P1) is carried out.

2. Method according to claim 1, characterized in that after a second exceedance of a threshold value (T1 ; T2) of another predefined operating parameter of the first or the second group (P1 ; P2) within a third wear phase (S3), a diagnosis (D1 ) of the operating parameters of the first and / or the second group (P1 ; P2) is carried out automatically, cyclically or manually, to determine wear.

3. Method according to claim 2, characterized in that further monitoring of the second group of operating parameters (P2) takes place during the third wear phase (S3).

4. Method according to claim 2 or 3, characterized in that a warning (W1) indicating a critical wear condition is issued during the third wear phase (S3).

5. Method according to one of claims 2 to 4, characterized in that, within the third wear phase (S3), a remaining service life determined on the basis of the monitored operating parameters of the first and / or the second group (P1 ; P2) is output. 202405867 10 6. Method according to one of claims 1 to 5, characterized in that after a third exceedance of a threshold value (T1 ; T2) of another predefined operating parameter of the first or second group (P1 ; P2) within a fourth wear phase (S4) a warning (W2) is issued requesting the replacement of the compressed air supply device.

7. Method according to claim 6, characterized in that further monitoring of the second group of operating parameters (P2) takes place during the fourth wear phase (S4).

8. Method according to claim 6 or 7, characterized in that, within the fourth wear phase (S4), a remaining service life determined on the basis of the monitored operating parameters of the first and / or the second group (P1 ; P2) is output.

9. Method according to one of claims 6 to 8, characterized in that, within the fourth wear phase (S4), an extended diagnosis (D2) of the operating parameters of the first and / or the second group (P1 ; P2) is carried out automatically, cyclically or manually to determine wear.

10. Method according to one of claims 6 to 9, characterized in that after a fourth exceedance of a threshold value (T1 ; T2) of a predefined operating parameter of the first or second group (P1 ; P2) operation of the compressed air supply device is prohibited.

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