Method for diagnosing a crankcase system, crankcase system, vehicle and computer program product

Abstract

A method (100) for diagnosing a crankcase system (200), comprising: - determining (110) a signal curve of an intake pressure (10) in an intake region (220) of an internal combustion engine, - determining (120) a signal curve of a second pressure (20) in a region (230) located downstream of the intake region (220), - calculating (130) a similarity between the signal curve of the intake pressure (10) and the signal curve of the second pressure (20), and - comparing (140) the similarity with a similarity target value range, wherein a deviation of the similarity from the similarity target value range indicates an improper condition of the crankcase system (200), characterized in that the calculation (130) comprises at least calculating a correlation or calculating a covariance between the signal curve of the intake pressure (10) and the signal curve of the second pressure (20), and / or that the calculation (130) comprises at least calculating a linear function whose curve substantially corresponds to the signal curve of the intake pressure (10) and the signal curve of the second pressure (20) or comprises carrying out a regression analysis.

Description

[0001] The invention relates to a method for diagnosing a crankcase system, a crankcase system, a vehicle and a computer program product.

[0002] A crankcase is a device that essentially serves as a bearing for the crankshaft in internal combustion engines. Depending on the definition, the crankcase may also include the cylinders, cooling jacket, and engine casing of an internal combustion engine.

[0003] When the combustion engine is running, certain pressure fluctuations always occur in a crankcase.

[0004] Gases that flow past the cylinder during combustion are fed back into the intake tract of the combustion engine in so-called closed crankcase ventilation systems or Positive Crankcase Ventilation (PCV) systems.

[0005] For the operation of the engine, it is particularly important that the crankcase system is intact, otherwise the service life of the internal combustion engine or its components can be significantly reduced.

[0006] Various diagnostic systems for crankcases are known from the state of the art, for example from DE 10 2015 116 483 A1, DE 10 2021 124 041 A1, US 2014 / 0081548 A1, JP 2020-186703 A, US 2005 / 0022795 A1, DE 10 2019 002 486 A1 and US 2022 / 0112822 A1.

[0007] However, there is still a need to provide particularly reliable, accurate and cost-effective crankcase diagnostics.

[0008] It is an object of the present invention to at least partially remedy the above-mentioned disadvantages known from the prior art. In particular, it is an object of the present invention to provide a method for diagnosing a crankcase system, a crankcase system, a vehicle, and a computer program product that enable reliable, accurate, and cost-effective diagnostics of the crankcase.

[0009] The above object is achieved by a method having the features of claim 1, a crankcase system having the features of claim 5, a vehicle having the features of claim 6, and a computer program product having the features of claim 7. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the crankcase system according to the invention, the vehicle according to the invention, and / or the computer program product according to the invention, and vice versa, so that reciprocal reference is or can always be made to the individual aspects of the invention with regard to the disclosure.

[0010] According to a first aspect of the invention, a method for diagnosing a crankcase system is provided, comprising: - Determining a signal curve of an intake pressure in an intake area of an internal combustion engine, in particular by an intake pressure sensor, - determining a signal curve of a second pressure in a region located downstream of the intake region, in particular by a second pressure sensor, - Calculating a similarity between the signal curve of the intake pressure and the signal curve of the second pressure, in particular by a processor, and - comparing the similarity with a similarity setpoint range, in particular by the processor, wherein a deviation of the similarity from the similarity setpoint range indicates an improper condition of the crankcase system.

[0011] The method may in particular be a computer-implemented method.

[0012] The method steps can be performed at least partially simultaneously and / or sequentially, whereby the sequence of the method steps is not limited by the specified order, so that individual steps can be performed in different orders. Furthermore, individual or all steps can be performed repeatedly.

[0013] A crankcase, also called engine housing or engine block, can be understood as an assembly comprising at least one cylinder, a cylinder cooling jacket, a crankshaft, a crankshaft bearing or an oil pan.

[0014] In other words, a method for determining a condition of a crankcase system can be provided, wherein at least two pressures are recorded in different regions of the crankcase system and their measured value curves are compared to determine whether they exhibit similar changes. At least one pressure is recorded in a region of the crankcase that is designed to supply a fluid, in particular air and / or air mixture, to the crankcase, in particular a combustion chamber of the internal combustion engine. A fluid can in particular comprise fuel and / or incompletely combusted products of the combustion process of the internal combustion engine. A further pressure is recorded in a region of the internal combustion engine that is located downstream of the first region.If the two pressures show significantly different curves, this may indicate that the crankcase system is at least in an improper condition, particularly a leak or blockage. In a proper condition, the pressure conditions in the crankcase remain within a specified range relative to the surrounding atmosphere, and blow-by gases generated in the engine are collected and discharged in an environmentally friendly manner as intended by the design. In other words, any condition deviating from the proper condition may constitute an improper condition.

[0015] In the context of the invention, a diagnosis can be understood as a process for assessing the condition of a system. The diagnosis can, in particular, comprise a determination of whether or not a defect is present. Furthermore, the diagnosis can also comprise a graded statement about the status of the system. It can be provided that the diagnosis includes an indication of the tightness, in particular as a percentage, with 100% preferably corresponding to a system that is tight as intended and 0% to a defective system. Comprehensive diagnoses offer the advantage that they can be used when servicing the crankcase, thus simplifying maintenance and saving costs.

[0016] Determining a signal profile can be understood as recording at least two, in particular a plurality of, measured values. Determining the signal profile can be understood as measuring at least one variable that changes over time.

[0017] Intake pressure can be understood as the pressure prevailing at a position in the intake area. The intake fluid can be provided to an internal combustion engine for combustion in one or more combustion chambers.

[0018] The features described in connection with the method according to the invention, which relate to a crankcase system to be diagnosed, also relate to a crankcase system according to the invention, which is described in more detail later.

[0019] The intake region can be understood as an assembly designed to supply a fluid, in particular air and / or an air mixture, to the crankcase, in particular the crankcase block. The intake region can comprise at least one intake manifold. At least one throttle valve can be arranged in the intake manifold.

[0020] The crankcase may comprise a crankcase block in which cylinders and a crankshaft can be arranged. Furthermore, the crankcase may comprise an oil pan. Furthermore, the internal combustion engine comprises both the intake region and the region located downstream of the intake region, which may, in particular, be designed as a ventilation region.

[0021] The second pressure is measured in a region that differs in position from the intake region. The second pressure is intended to be measured downstream of the intake region. Downstream refers to the direction of fluid movement within the crankcase system. Depending on the operating mode, the fluid can be routed along different flow paths.

[0022] It can be provided that the second pressure is configured as a venting pressure. The venting pressure can be understood as the pressure prevailing at a position in a venting area of the crankcase.

[0023] The ventilation area can be understood as an assembly designed to remove a fluid, in particular air and / or an air mixture, from the crankcase, in particular from the crankcase block. It can be provided that the ventilation area guides a fluid, in particular air and / or an air mixture, away from the crankcase toward the intake area, in particular to one or more combustion chambers.

[0024] Alternatively or additionally, the second pressure can be implemented as pressure in a crankcase ventilation line and / or pressure in the crankcase block.

[0025] The crankcase system can be designed as a closed crankcase system. In other words, it can be provided that air and / or an air mixture from the ventilation area is fed back into the intake area.

[0026] Similarity can be understood as a measure, particularly a mathematical one, of the similarity of two signal profiles. Similarity can be defined as a measure of the change in the signal profile as a function of time. Similarity would be high if both signal profiles change on a similar time scale. The similarity of the signal profiles may be high if they change by a similarly high value, particularly in absolute terms, over time.

[0027] Calculating the similarity with a similarity target range can be understood as a method suitable for determining a quantitative value for the similarity of the signal waveforms. Variants of this method are described in connection with the subclaims.

[0028] A similarity setpoint range can be a value range that is specific to the condition of the crankcase system. The similarity setpoint range can also be implemented as a threshold value. It can further be provided that at least two similarity setpoint ranges are provided, wherein a first similarity setpoint range corresponds to a crankcase system that is sealed as intended, and a second similarity setpoint range corresponds to an operational crankcase system with a measurable fault.

[0029] It can further be provided that a measure is triggered if the similarity deviates from the similarity target value range. A measure can be implemented as a signal, in particular at least acoustically or visually. Furthermore, the signal can be received by a central control unit of a vehicle that includes the crankcase system. It can also be provided that the measure comprises at least entering or incrementing a counter reading in an error memory. This can, for example, switch off the engine in the event of a fault or prompt a vehicle user to immediately park the vehicle or visit a workshop. This can improve the service life of the crankcase system. Furthermore, it can be provided that if the similarity deviates from the similarity target value range, charging by the turbocharger is prevented.This can prevent exhaust gases from being released into the environment in the event of a line defect. It can also be provided that the measure includes at least a reduction in the vehicle's speed, torque, engine power, remaining travel time, or a transmission of the detected improper condition to a recording center, in particular at least the vehicle manufacturer or a workshop.

[0030] Overall, the method according to the invention for diagnosing a crankcase system achieves the advantage of enabling reliable, precise, and cost-effective diagnostics of the crankcase system. Determining the signal curves of the intake pressure and the ventilation pressure provides information about two areas of the crankcase that can be detected independently of one another and thus even offer a certain level of information redundancy in themselves. In principle, with a properly sealed crankcase system, it can be assumed that the signal curves of the intake pressure and the ventilation pressure react similarly to changes in the system. If this similarity deviates, which is determined according to the invention and compared with a similarity target value, it is possible that the crankcase system is in a condition deviating from the proper state, in particular a leak or a blockage.The comparison therefore allows for a reliable and easy detection of a malfunction, which can also extend the service life of the crankcase system.

[0031] Furthermore, the method according to the invention can be provided for the calculation to include at least calculating a correlation or a covariance between the signal curve of the intake pressure and the signal curve of the second pressure. Both correlation and covariance can be determined relatively easily, in particular almost in real time. This provides a particularly fast, reliable measure of the similarity of the signal curves.

[0032] Furthermore, the method according to the invention can be provided for the calculation to comprise at least a calculation of a linear function whose profile essentially corresponds to the signal profile of the intake pressure and the signal profile of the second pressure, or to comprise carrying out a regression analysis. The determination of a linear function offers the advantage that a similarity of the signal profiles can be determined easily and quickly from the linear function. In a regression analysis, a variety of statistical methods can be selected to determine the similarity. The regression analysis therefore has the advantage of being able to select a statistical method tailored to the specific application, which can be selected to achieve the best compromise between speed of execution and accuracy of the analysis.

[0033] Within the scope of the invention, it is further conceivable that the determination of the signal curve of the intake pressure in the intake region is carried out as a determination of the signal curve of the intake pressure at least in an intake manifold downstream of a throttle valve or upstream of the throttle valve. When determining the intake pressure in the intake manifold downstream of a throttle valve, the advantage can be achieved that a pressure reduced compared to the ambient pressure can be measured. When measuring upstream of the throttle valve, either an ambient pressure or a pressure which is increased by an exhaust gas turbocharger compared to the pressure downstream of the throttle valve is present. It can also be provided that the intake pressure is implemented as the average value of measurements downstream of the throttle valve and upstream of the throttle valve. This can mitigate measurement errors of an individual sensor.It may also be provided that a plausibility analysis is performed based on pressure measurements downstream and upstream of the throttle valve. This has the advantage of allowing a defective sensor to be identified.

[0034] Within the scope of the invention, it is further conceivable that determining the signal profile of the second pressure in the region downstream of the intake region is carried out as determining the signal profile of the second pressure at least in a crankcase ventilation line, in a crankcase block, or in a crankcase ventilation line. Measuring the second pressure can be advantageous depending on the operating mode of the internal combustion engine. Furthermore, the combination of multiple measurements can be used to perform a plausibility analysis to check the functionality of the pressure sensors. Furthermore, average values can be calculated to reduce the impact of individual outliers on the calculation of similarity.

[0035] Preferably, a method according to the invention can provide for at least the calculation of the similarity to take place when a calculation condition is met at least for the intake pressure or the second pressure, or the signal curve of at least the intake pressure or the second pressure only comprises values for which a recording condition is met when detected. In other words, the calculation and / or recording of the values can only take place when predetermined prerequisites are met, in particular during a boost pressure build-up, a boost pressure maintenance, or a boost pressure reduction. The calculation condition and / or the recording condition can include, for example, that the internal combustion engine is in operation and / or that the intake pressure, in particular the boost pressure, is within a predetermined value range, in particular between 1100 hPa and 1500 hPa.Furthermore, it can be provided that the calculation condition and / or the recording condition are implemented as a time delay, particularly after a boost pressure buildup. Providing calculation conditions and / or recording conditions has the advantage of making the diagnosis particularly reliable, since outliers are pre-filtered and no measurements or evaluations take place at a time when a diagnosis is not possible or not appropriate.

[0036] According to a further aspect of the invention, a crankcase system is provided, comprising: - an intake pressure sensor designed to determine a signal curve of an intake pressure in an intake area of an internal combustion engine, - a second pressure sensor designed to determine a signal curve of a second pressure in a region located downstream of the intake region, - a processor configured to calculate a similarity between the intake pressure signal waveform and the second pressure signal waveform and to compare the similarity with a similarity setpoint range, wherein a deviation of the similarity from the similarity setpoint range indicates an improper condition of the crankcase system.

[0037] Furthermore, in a crankcase system according to the invention, it is provided that the crankcase system is designed to carry out a method according to the invention.

[0038] Thus, a crankcase system according to the invention brings with it the same advantages as have already been described in detail with reference to a method according to the invention.

[0039] According to a further aspect of the invention, a vehicle is provided comprising at least one crankcase system according to the invention.

[0040] Thus, a vehicle according to the invention brings with it the same advantages as have already been described in detail with reference to a method according to the invention and / or a crankcase system according to the invention.

[0041] According to a further aspect of the invention, a computer program product is provided, comprising instructions which, when the program is executed by a computer, in particular a processor of a crankcase system according to the invention, cause the computer to carry out a method according to the invention.

[0042] Thus, a computer program product according to the invention brings with it the same advantages as have already been described in detail with reference to a method according to the invention, a crankcase system according to the invention and / or a vehicle according to the invention.

[0043] Further advantages, features, and details of the invention will become apparent from the following description, which describes exemplary embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. They show schematically: Fig. 1: a method according to the invention, Fig. 2: exemplary measured values, and Fig. 3: an exemplary determination of correlation and covariance for different situations in the crankcase system, and Fig. 4: a crankcase system according to the invention.

[0044] In the following description of some embodiments of the invention, the same reference numerals are used for the same technical features even in different embodiments.

[0045] Fig. 1 schematically shows a method 100 according to the invention for diagnosing a crankcase system 200. The method 100 comprises determining 110 a signal profile of an intake pressure 10 in an intake region 220 of an internal combustion engine. Furthermore, the method 100 comprises determining 120 a signal profile of a second pressure 20 in a region 230 of the internal combustion engine located downstream of the intake region. The method 100 likewise comprises calculating 130 a similarity between the signal profile of the intake pressure 10 and the signal profile of the second pressure 20. Part of the method 100 is also comparing 140 the similarity with a similarity target value range. A deviation of the similarity from the similarity target value range indicates an improper condition of the crankcase system 200.

[0046] Overall, the method 100 according to the invention for diagnosing a crankcase system 200 achieves the advantage of enabling reliable, accurate, and cost-effective diagnostics of the crankcase system 200. Determining the signal curves of the intake pressure 10 and the second pressure 20 provides information about two areas of the crankcase 210 that can be detected independently of one another and thus even offer a certain level of information redundancy. In principle, with a properly sealed crankcase system 200, it can be assumed that the signal curves of the intake pressure 10 and the second pressure 20 react similarly to changes in the system. If this similarity, which is determined according to the invention and compared with a similarity target value, deviates, it is possible that the crankcase system 200 is malfunctioning.The comparison allows for a reliable and easy detection of a malfunction. This can also extend the service life of the 200 crankcase system.

[0047] Furthermore, in a method 100 according to the invention, it can advantageously be provided that the calculation 130 comprises at least a calculation 130 of a correlation or the calculation 130 of a covariance between the signal curve of the intake pressure 10 and the signal curve of the second pressure 20. Both the correlation and the covariance can be determined in a relatively simple manner, in particular almost in real time. This provides a particularly fast, reliable measure of the similarity of the signal curves.

[0048] Fig. 2 shows, by way of example, a representation of measured values for a second pressure 20 (top) and an intake pressure 10 (bottom) for various states of the crankcase system 200 as a function of time. In other words, the signal curves of the second pressure 20 and the intake pressure 10 are shown. Both graphs 10, 20 share a common time axis. The second pressure 20 is shown inverted. In the correct state, the signal curves of the second pressure 20 and the intake pressure 10 are similar, in particular proportional or antiproportional. In particular, they rise and fall at similar times by similar values relative to the respective signal. This case corresponds to the uppermost signal curve of the second pressure 20.

[0049] However, if leaks occur in a region 230 of the combustion engine located downstream of the intake region, the two lower signal curves for the second pressure 20 result (upper signal curve for a leak of 6 mm, lower signal curve for a leak of 12 mm). The signal curve for the intake pressure 10 remains essentially the same. This leads to a decrease in the similarity of the signal curves for the intake pressure 10 and the second pressure 20 in the event of a leak.

[0050] Furthermore, in a method 100 according to the invention, it is conceivable that the calculation 130 comprises at least a calculation 130 of a linear function, the course of which essentially corresponds to the signal course of the intake pressure 10 and the signal course of the second pressure 20 or comprises carrying out a regression analysis. A linear function is in the Fig. 2 shows, by way of example, the signal curves 10, 20 at the point where the pressure increases. Determining a linear function offers the advantage that a similarity of the signal curves can be determined easily and quickly from the linear function, in particular via a correlation. In a regression analysis, a variety of statistical methods 100 can be selected to determine the similarity. Regression analysis therefore offers the advantage of being able to select a statistical method tailored to the specific application, which can be selected to achieve the best compromise between speed of execution and accuracy of the analysis.

[0051] In the Fig. 3 shows three graphs for the different states of the crankcase system 200, which represent the correlation coefficient between the signal curve of the intake pressure 10 and the signal curve of the second pressure 20 as a function of time. When recording the values, a Worldwide Harmonized Light Vehicles Test Procedure (WLTP for short) was measured. In the left of the three graphs of the Fig. 3, the correlation coefficient is almost -1, which corresponds to the proper condition. For a leak of 6 mm (middle graph of the Fig. 3) the correlation coefficient deviates from -1. For an even larger leak of 12 mm (right graph of the Fig. 3) the correlation coefficient fluctuates around 0. In other words, the correlation coefficient of the signal curves of the suction pressure 10 and the second pressure 20 decreases in the event of a leak.

[0052] Fig.4 finally shows a crankcase system 200 according to the invention. As shown, the crankcase system 200 has an intake pressure sensor 240, which is designed to determine 110 a signal curve of an intake pressure 10 in an intake region 220 of an internal combustion engine. Furthermore, the crankcase system 200 has a second pressure sensor 250, which is designed to determine 120 a signal curve of a second pressure 20 in a region 230 of the internal combustion engine located downstream of the intake region. The crankcase system 200 also has a processor 260, which is designed to calculate 130 a similarity between the signal curve of the intake pressure 10 and the signal curve of the second pressure 20 and to compare the similarity with a similarity target value range 140. The processor 260 can be signal-connected to at least the intake pressure sensor 240 and / or the second pressure sensor 250 in order to receive the measured values (not shown here).A deviation of the similarity from the similarity target range indicates an improper condition of the crankcase system 200.

[0053] Within the scope of the invention, it is further conceivable that the determination 110 of the signal curve of the intake pressure 10 in the intake region 220 is carried out as a determination 110 of the signal curve of the intake pressure 10 at least in an intake manifold 221 downstream of a throttle valve 222 or upstream of the throttle valve 222. When determining the intake pressure 10 in the intake manifold 221 downstream of a throttle valve 222, the advantage can be achieved that a pressure slightly reduced compared to the ambient pressure can be measured. When measuring upstream of the throttle valve 222, either an ambient pressure or a pressure is present which is slightly increased by an exhaust gas turbocharger compared to the pressure downstream of the throttle valve 222. It can also be provided that the intake pressure 10 is implemented as the average value of measurements downstream of the throttle valve 222 and upstream of the throttle valve 222.This can mitigate measurement errors of a single sensor.

[0054] It may further be provided that a plausibility analysis is performed based on pressure measurements downstream of the throttle valve 222 and upstream of the throttle valve 222. This provides the advantage of detecting a defective pressure sensor.

[0055] Within the scope of the invention, it is further conceivable that the determination 120 of the signal profile of the second pressure 20 in the region 230 located downstream of the intake region is carried out as the determination 120 of the signal profile of the second pressure 20 at least in a vent line 231 of the crankcase 210, in a crankcase block 211, or in a ventilation line 232 of the crankcase 210. The measurement of the second pressure 20 can be advantageous depending on the operating mode of the internal combustion engine. Furthermore, the combination of several measurements can be used to perform a plausibility analysis in order to check the functionality of the pressure sensors. Furthermore, average values can be calculated to reduce the effects of individual outliers on the calculation of the similarity. List of reference symbols 10 Intake pressure 20 second print 100 procedures 110 Determining a signal curve of an intake pressure 120 Determining a signal curve of a second pressure 130 Calculate 140 Compare 200 crankcase system 210 crankcase 211 crankcase block 220 intake area 221 intake manifold 222 throttle valve 230 area downstream of the intake area 231 vent line 232 ventilation line 240 Intake pressure sensor 250 second pressure sensor 260 processor

Claims

[1] A method (100) for diagnosing a crankcase system (200), comprising: - determining (110) a signal curve of an intake pressure (10) in an intake region (220) of an internal combustion engine, - determining (120) a signal curve of a second pressure (20) in a region (230) located downstream of the intake region (220), - calculating (130) a similarity between the signal curve of the intake pressure (10) and the signal curve of the second pressure (20), and - comparing (140) the similarity with a similarity setpoint range, wherein a deviation of the similarity from the similarity setpoint range indicates an improper condition of the crankcase system (200), characterized bythat the calculation (130) comprises at least a calculation of a correlation or the calculation of a covariance between the signal curve of the intake pressure (10) and the signal curve of the second pressure (20), and / or that the calculation (130) comprises at least a calculation of a linear function, the curve of which substantially corresponds to the signal curve of the intake pressure (10) and the signal curve of the second pressure (20) or comprises carrying out a regression analysis. [2] Method (100) according to one of the preceding claims, characterized by that the determination (110) of the signal curve of the intake pressure (10) in the intake region (220) is carried out as a determination (110) of the signal curve of the intake pressure (10) at least in an intake manifold (221) downstream of a throttle valve (222) or upstream of the throttle valve (222). [3] Method (100) according to one of the preceding claims, characterized bythat the determination (120) of the signal curve of the second pressure (20) in the region (230) located downstream of the intake region (220) is carried out as determination (120) of the signal curve of the second pressure (20) at least in a vent line (231) of the crankcase (210), in a crankcase block (211) of the crankcase (210) or in a ventilation line (232) of the crankcase (210). [4] Method (100) according to one of the preceding claims, characterized by that at least the calculation (130) of the similarity takes place when a calculation condition is fulfilled at least for the intake pressure (10) or the second pressure (20), or the signal curve of at least the intake pressure (10) or the second pressure (20) only comprises values for which a recording condition is fulfilled when detected. [5] Crankcase system (200), comprising: - an intake pressure sensor (240) designed to determine (110) a signal curve of an intake pressure (10) in an intake region (220) of an internal combustion engine, - a second pressure sensor (250) designed to determine (120) a signal curve of a second pressure (20) in a region (230) located downstream of the intake region (220), - a processor (260) designed to calculate (130) a similarity between the signal curve of the intake pressure (10) and the signal curve of the second pressure (20) and to compare (140) the similarity with a similarity setpoint range, wherein a deviation of the similarity from the similarity setpoint range indicates an improper condition of the crankcase system (200), characterized by , - points out, characterized by that the crankcase system (200) is designed to carry out a method (100) according to one of claims 1 to 4. [6] A vehicle comprising at least one crankcase system (200) according to claim 5. [7] Computer program product, comprising instructions which, when the program is executed by a computer, in particular a processor (260) of a crankcase system (200) according to claim 5, cause the computer to carry out a method (100) according to one of claims 1 to 4.

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