WO2018192993A1 - Internal combustion engine and method for monitoring an internal combustion engine - Google Patents

Abstract

The invention relates to an internal combustion engine having a motor having a number of cylinders and a monitoring device for monitoring an operation of the internal combustion engine, characterized in that, for each cylinder from the number of cylinders, a respective cylinder pressure sensor of the monitoring device is arranged on the respective cylinder of the internal combustion engine and is designed to measure a cylinder pressure of the respective cylinder, to determine cylinder pressure data corresponding to the cylinder pressure and to output a respective cylinder pressure signal indicating the cylinder pressure data. The monitoring device furthermore has an analysis unit which is designed to receive the respective cylinder pressure signal (135) and to determine, individually for each cylinder, from a temporal progression of the cylinder pressure data of the respective cylinder, whether there is an anomaly of cylinder pressure, in particular whether there is an anomaly of cylinder pressure during a compression phase of the respective cylinder during operation of the motor, and to associate the anomaly with the respective cylinder of the motor.

Description

 DESCRIPTION Internal combustion engine and method for monitoring an internal combustion engine

The invention relates to an internal combustion engine, comprising an engine with a number of cylinders and a monitoring device for monitoring an operation of the internal combustion engine. Furthermore, the invention relates to a method for monitoring an operation of an internal combustion engine and software.

It is known to monitor by cylinder pressure sensors, a cylinder pressure in a cylinder of an engine. As a result, in the case of atypical behavior of the cylinder pressure in the cylinder, for example in the case of unusually large or unusually small cylinder pressure, a mechanical defect of the engine can be inferred. Known mechanical defects affecting the behavior of the cylinder pressure in this context are a broken or worn piston ring, a valve break, a clamping of a valve due to deposits in the combustion chamber. In addition to mechanical defects, it also affects the behavior of the cylinder pressure when the valve clearance of the intake or exhaust valve is too large.

Therefore, maintenance work is typically performed on engines on a regular basis to examine the valves and condition of the piston rings.

Furthermore, a control system for internal combustion engines is known, which triggers a signal to a user of the internal combustion engine in the presence of an atypical behavior of the cylinder pressure.

The object of the invention is to provide an improved internal combustion engine, in particular to provide an internal combustion engine which monitors particularly advantageous cylinder pressure data of an internal combustion engine during operation of the internal combustion engine. Here, in particular, an effective monitoring is to be provided by the fast damage is supported in case of damage.

To solve this problem, an internal combustion engine according to claim 1 is proposed. The internal combustion engine according to a first aspect of the invention comprises an engine having a number of cylinders and a monitoring device for monitoring an operation of the internal combustion engine.

According to the invention, it is provided that

- For each cylinder of the number of cylinders a respective Zy cylinder pressure sensor of the monitoring device to the respective cylinder of the internal combustion engine is arranged and adapted to measure a cylinder pressure of the respective cylinder to determine the cylinder pressure corresponding cylinder pressure data and output a cylinder pressure data indicating respective cylinder pressure signal ;

an analysis unit of the monitoring device is designed to receive the respective cylinder pressure signal and to determine from a chronological progression of the cylinder pressure data of the respective cylinder individually for each cylinder, whether there is an anomaly of the cylinder pressure, in particular if an anomaly of the cylinder pressure during a compression phase of the respective cylinder in the Operation of the engine is present, wherein

 the anomaly can be determined as a symptom occurring in the course of time of the cylinder pressure data,

 the symptom is compared with an adequate reference of the cylinder pressure data, and is concluded from a significant proportionate size of the symptom compared to the adequate reference to the presence of the anomaly, in particular extent and nature of the anomaly;

 the analysis unit is further configured to associate the anomaly with the respective cylinder of the engine.

The invention is based on the consideration that a repair of a defective engine can be particularly efficient and fast if a location of a defective cylinder is known. In addition, regular maintenance can be dispensed with if, during operation of the internal combustion engine, a functional capability of corresponding components susceptible to wear can occur. The invention has recognized that monitoring the chronological progression of the cylinder pressure data allows conclusions to be drawn as to the operability of the valves and the piston ring of the cylinders of the engine, so that it is possible to conclude a cylinder-specific evaluation of the cylinder pressure data for a specific damage of a specific cylinder of the engine.

The internal combustion engine according to the invention allows a particularly effective maintenance, since for a detected anomaly already the cylinder on which the anomaly has occurred is known. In particular, a repair time and thus a service life of the internal combustion engine can be shortened.

A maintenance of the cylinder according to fixed maintenance intervals can be advantageously avoided by the internal combustion engine according to the invention. The evaluation of cylinder pressure data is particularly advantageous in view of a simple and robust construction of commercially available cylinder pressure sensors. Here, cylinder pressure data preferably represent the pressure in the cylinder over a crank angle for the present working cycle of the cylinder. The compression phase of a cylinder is formed by that part of a working cycle of a corresponding cylinder, in which the piston is moved to a cylinder head of the cylinder, so that the pressure is increased in the combustion chamber of the cylinder. Here, the compression phase is preferably formed by a left and right flank to a maximum cylinder pressure of a cylinder pressure curve.

The symptom is a characteristic of the time history of the cylinder pressure data which is suitable for allowing conclusions to be drawn about a damage to the corresponding cylinder on which the cylinder pressure data were measured. The presence of an anomaly is in the context of the internal combustion engine according to the invention from the size of the symptom in comparison to an adequate reference closed. This means that the symptom is related to the adequate reference, that is, for example, a cylinder pressure of the cylinder pressure curve measured at an earlier time, a predetermined comparison value to a characteristic of the cylinder pressure curve, or a predetermined target cylinder pressure curve. An anomaly is a malfunction of the engine, in particular the intake and / or exhaust valves or the piston rings in the cylinder. In the presence of a significantly proportionate size of the symptom in view of the adequate reference can be concluded on such a misconduct, so an anomaly. A significantly proportionate size of the symptom is when, compared to usual differences from the adequate reference, a measure is exceeded, which is likely to make a misconduct likely against a random deviation of a random difference. In particular, this can ensure that inaccuracies not caused by structural engineering, such as the piston play, lead to the determination of the presence of an anomaly. From the fault behavior of the engine according to the invention to a mechanical defect on the corresponding cylinder and / or an abnormal valve clearance, so a valve clearance, which differs significantly from a predetermined valve clearance, closed.

A time course of cylinder pressure data indicates the measured cylinder pressure for at least three different crank angles within a compression phase of the respective cylinder, preferably more than 10, more than 50 or more than 100 different crank angles within a compression phase of the respective cylinder.

According to another aspect of the invention, the above object is achieved by a method for monitoring an operation of an internal combustion engine with a number of cylinders, in particular an internal combustion engine according to the first aspect of the invention.

The method according to the invention comprises the following steps:

- Measuring a respective cylinder pressure for all cylinders of the internal combustion engine;

Determining respective cylinder pressure data and outputting a cylinder pressure signal indicative of the cylinder pressure data;

- Receiving the respective cylinder pressure signal and cylinder-individual determination of whether an anomaly of the cylinder pressure is present, based on a time course of the cylinder pressure data, wherein the anomaly can be determined as a symptom occurring in the course of time of the cylinder pressure data,

 the symptom is compared with an adequate reference of the cylinder pressure data, and is concluded from a significant proportionate size of the symptom compared to the adequate reference to the presence of the anomaly, in particular extent and nature of the anomaly;

- Assigning the determined anomaly to a cylinder of the engine. Advantageously, the method enables a cylinder-specific determination of which cylinder has a damage. Furthermore, in view of the symptom, an anomaly reason may be displayed, which may particularly facilitate maintenance of a corresponding internal combustion engine. Furthermore, the method according to the invention can be carried out particularly advantageously automated, in particular be carried out automatically at regular intervals, without individual steps require manual operation of the user.

According to a further aspect of the invention, the above-mentioned object is achieved by a software having program means with a module adapted to control a method according to the invention for monitoring an operation of an internal combustion engine.

The software is preferably executed during operation of the internal combustion engine by a processor connected to the internal combustion engine.

Further advantageous developments of the invention can be found in the subclaims and specify in detail advantageous possibilities to realize the above-described concept within the scope of the problem as well as with regard to further advantages.

Preferably, the analysis unit of the internal combustion engine is designed to check for several symptoms whether these symptoms occur in the course of the cylinder pressure data. This may indicate the presence of an anomaly for various causes of anomaly, ie Various malfunctions of the engine are checked. This makes it possible to detect different components of the engine to be serviced and thus increases the efficiency of maintenance.

In a particularly preferred development of the internal combustion engine according to the first aspect of the invention, the analysis unit is further configured to calculate from discrete values of the determined time characteristic of the cylinder pressure data of the cylinder a current cylinder pressure curve with current cylinder pressure curve coefficients and to determine whether based on the current cylinder pressure curve there is an anomaly of the cylinder pressure. In this development, the internal combustion engine can advantageously reduce a processing outlay of the monitoring device, since the current cylinder pressure curve can already be deduced from a few values for the cylinder pressure of the cylinder, which represent the ascertained time profile of the cylinder pressure data. In this case, a known characteristic curve of cylinder pressure curves is taken into account particularly advantageously. In particular, can be closed by the internal combustion engine according to this development to a maximum cylinder pressure without the measurement of the cylinder pressure must take place in such small time intervals that the maximum cylinder pressure is actually measured.

In a preferred embodiment, the internal combustion engine is further characterized in that

 - The monitoring device comprises a memory unit which is connected to the analysis unit and which is adapted to store predetermined target pressure data, which characterize a desired pressure curve of the engine, wherein

 - The analysis unit is adapted to access the predetermined target pressure data and the predetermined target pressure data is used as an adequate reference for the comparison of the symptom.

In this refinement, it is advantageously possible to determine a difference between a current pressure profile curve resulting from the determined cylinder pressure data and the desired pressure profile curve. In this way, advantageously, for determining whether symptoms have a significant proportionate size, only those symptoms that result from significant deviations from the target pressure curve curve can be examined. In a particularly advantageous variant of this development, the predetermined desired pressure data at an earlier time from the analysis unit of the internal combustion engine Zy cylinder pressure data of the respective cylinder during a fault-free state of the engine determined. This allows the use of a desired pressure curve, which is adapted to the respective engine, in particular to the respective cylinder of the engine. In an embodiment of the internal combustion engine according to the invention, the analysis unit is designed to determine whether an anomaly of the cylinder pressure is present, based on detecting a reduction of a symptomatic maximum cylinder pressure of the cylinder compared to an adequate reference forming earlier measurement of the cylinder pressure. From the reduction in the maximum cylinder pressure of the cylinder can be concluded that a malfunction of the intake valve. A dynamically reducing maximum cylinder pressure can be caused in particular by a leaking valve, for example due to deposits in the combustion chamber.

In a further refinement of the internal combustion engine according to the invention, the analysis unit is designed to determine whether there is an anomaly of the cylinder pressure based on detecting a shift in a symptomatic temporal position of a maximum cylinder pressure relative to a top dead center of the internal combustion engine forming the adequate reference toward a negative one Crank angle of the internal combustion engine. The negative crank angle of the internal combustion engine lies in the region of a left flank, or incoming flank of the Zylmderdruckverlaufskurve resulting in error-free operation of the engine. Consequently, if the maximum cylinder pressure shifts to negative crank angles, this means that before the corresponding piston of the cylinder has reached its top dead center, a maximum pressure is created in the combustion chamber of the cylinder. As a result, a malfunction of the intake valve of the cylinder is detected and determined according to the presence of an anomaly.

In an embodiment of the internal combustion engine according to the invention, the analysis unit is designed to determine whether there is an anomaly of the cylinder pressure, based on detecting a reduction of a symptomatic indexed mean pressure of the cylinder compared to an earlier measurement of the indicated mean pressure forming the adequate reference. The indicated mean pressure is known to result from the ratio of indicated work done by the cylinder and present displacement. Determining a reduced mean indicated pressure as compared to an earlier measurement indicates a malfunction of the intake valve of the corresponding cylinder. Additionally or alternatively, the analysis unit of the internal combustion engine is configured to determine whether an anomaly of the cylinder pressure is present, based on detecting a reduction of a symptomatic minimum cylinder pressure after reaching a top dead center of the internal combustion engine compared to a minimum forming the adequate reference Cylinder pressure before a top dead center of the internal combustion engine. A reduction in minimum cylinder pressure after compression below a level reached prior to this compression indicates incorrect compression within the cylinder. In this case, it can be concluded that there is a defect in a valve on the corresponding cylinder if the reduction has a significant relative size compared to the level before compression, ie there are no component-related fluctuations which would also be present in the case of a functioning cylinder.

In an embodiment of the internal combustion engine according to the invention, the analysis unit is designed to determine whether there is an anomaly of the cylinder pressure, based on detecting a strong increase in a symptomatic curvature of an outgoing edge of a resulting from the time course of the cylinder pressure data cylinder pressure curve after top dead center of the internal combustion engine , Such a large increase in a curvature of an outgoing flank, that is, a right flank, leads to a characteristic bend in a corresponding cylinder pressure curve. Such a kink, that is, a greatly increased curvature, typically results from a reversal of a flow direction due to pressure differences between the combustion chamber and the charge air tube on the cylinder. With increasing malfunction of an intake valve of the cylinder, this kink shifts to smaller crank angles. Already by the kink can be closed on the existence of the corresponding anomaly, ie a malfunction of the intake valve. From a position of the bend can in turn be concluded on a degree of anomaly, so to a degree of malfunction of the valve.

In a preferred refinement of the internal combustion engine according to the invention, the analysis unit is designed to determine from a reduction in a symptomatic degree of symmetry of a cylinder pressure curve resulting from the time profile of the cylinder pressure data with respect to a top dead center of the internal combustion engine, if there is an anomaly of the cylinder pressure. In the case of a correctly set inlet valve, there is typically an axial symmetry in the cylinder pressure curve with respect to top dead center the internal combustion engine recognizable when the engine is either towed or the cylinder deactivation is activated. A low degree of symmetry, that is to say a certain asymmetry, within the cylinder curve resulting from the chronological progression of the cylinder pressure data, indicates a malfunction, in particular an incorrectly adjusted inlet valve. In this case, the adequate reference is formed by a degree of asymmetry in the cylinder pressure curve that is typically present in the case of a faultless engine.

Furthermore, the analysis unit is formed in a development, based on the cylinder pressure data and on a predetermined displacement of the cylinder of the internal combustion engine for at least two different crank angles of the internal combustion engine to determine a symptomatic current polytropic exponent of the cylinder of the internal combustion engine and thereby determine whether an anomaly the cylinder pressure is present. The adequate reference in this development is a predetermined polytropic exponent of the corresponding cylinder, which can be accessed by the analysis unit. The polytropic exponent is the exponent n, for which p ^■ V "= const, where p is the measured cylinder pressure and V is the specific volume of the gas in the cylinder The polytropic exponent n is equal to 1 for an isothermal process 0 for an isobaric process, and very large for an isochoric process From the value of the cylinder pressure at two different interfaces can be directly deduced the present polytropic exponent, preferably as support points 100 ° crank angle before top dead center and 64 ° crank angle before If the polytropic exponent differs from the predetermined polytropic exponent there is a compression error, such a compression error can be caused by malfunction of the valves and / or piston ring of the cylinder.

In an embodiment of the internal combustion engine according to the invention, the analysis unit is designed to determine whether an anomaly of the cylinder pressure is present, based on an analysis of a symptomatic pressure gradient pattern formed by the time profile of the cylinder pressure data at the time of closing an intake and / or exhaust valve. The closing of the intake or exhaust valve can be detected by characteristic high-frequency cylinder pressure oscillations at a respective predetermined crank angle before the top dead center of the internal combustion engine. Lack of such high-frequency cylinder pressure oscillations, or falls significantly lower than is typically the case is, can be closed on a wrongly adjusted inlet valve and / or according to an incorrectly adjusted exhaust valve. In particular, such a false adjustment may be inferred if a steady cylinder pressure curve is obtained from the measured cylinder pressure data that does not indicate characteristic high frequency cylinder pressure oscillations. Such sudden deviations from a constant pressure, as is the case with faultless valves, can be determined particularly well automated, in particular automated by means of a computer. Furthermore, the internal combustion engine according to this development allows a determination as to whether there is a defect in the inlet or outlet valve of the corresponding cylinder. Furthermore, it can be concluded by the position and size of the characteristic high-frequency cylinder pressure oscillations at the corresponding crank angle to a valve clearance of the respective valve of the cylinder. Thus, a reduced valve clearance causes a valve to open earlier and close later, compared to a non-reduced valve clearance. From the location of the characteristic high-frequency cylinder pressure oscillations, it can be determined whether an existing valve clearance of a valve of the cylinder corresponds to a valve clearance predetermined before an operation of the cylinder. Furthermore, in addition to the presence of an anomaly, the analysis unit may additionally or alternatively output a valve clearance for the intake and / or exhaust valve of the cylinder. As a result, maintenance to be performed can be carried out particularly effectively, since information about the present valve clearance already exists. In particular, by determining an anomaly of the valve clearance, that is, for example, a faulty large valve clearance, a preventive maintenance of the corresponding cylinder can be carried out before damage to the engine could occur.

In an embodiment of the internal combustion engine according to the invention, the analysis unit is designed to additionally perform an analysis of a symptomatic pressure gradient pattern formed by the time course of the cylinder pressure data at the time of closing an intake and / or exhaust valve of the cylinder and based on the anomaly to assign an anomaly cause in particular to distinguish whether a defect of a valve or a piston ring is present. If a cylinder anomaly is detected, there is typically a mechanical failure of one of the valves or one of the piston rings of the cylinder. Therefore, if an abnormality has been detected on a cylinder, but also the characteristic high-frequency cylinder pressure oscillations typical for closing the intake or exhaust valve have been established, a high-probability piston ring defect can be inferred become. This development allowed a particularly advantageous distinction between two different causes of error on the cylinder. This makes it possible to detect an abnormality cause without disassembling the engine or manually inspecting the engine.

In a particularly preferred development, there is a combination of at least two of the described developments. The internal combustion engine is preferably designed to be able to examine various characteristics of the chronological progression of the cylinder pressure data, that is to say different symptoms by the analysis unit, so that a defect and / or a malfunction of a component of the cylinder can be concluded on the basis of a plurality of symptoms of significantly proportional size. In particular, the internal combustion engine is designed in a development, only to confirm the presence of an anomaly in the presence of multiple symptoms with a significant proportionate size. As a result, errors of the monitoring device can be avoided particularly reliable.

In an embodiment of the internal combustion engine according to the invention, the analysis unit is designed to trigger an output signal if a presence of an anomaly of the cylinder pressure is determined. The triggering of an output signal allows a quick response to the anomaly, so on a malfunction of the cylinder, for example by a manufacturer and / or user of the internal combustion engine. As a result, a consequential damage to the cylinder can be avoided.

In an embodiment of the internal combustion engine according to the invention, the analysis unit indicates on which cylinder from the number of cylinders the presence of an anomaly of the cylinder pressure was determined. As a result, it is clear even in the presence of the output signal, which cylinder must be repaired in the context of maintenance, and how many cylinders a fault, ie an anomaly, is present. For example, the output signal may indicate whether an A-side cylinder or a B-side cylinder is affected. For example, the output signal may further indicate which cylinder of the A side or the B side is affected, such as by displaying the information B6 for an abnormality on the sixth cylinder of the B side of the engine. Preferably, the output signal further indicates a motor identification number allowing the output signal to be assigned to the output-triggering motor. As a result, for example, a manufacturer of the internal combustion engine can immediately assess the anomaly that has been detected for an engine, in nature and extent given the intended use for the specific engine, in particular assess whether a user should be informed about the malfunction of the internal combustion engine.

In a particularly preferred development, the output signal also indicates an anomaly cause in addition to the presence of the anomaly, in particular whether there is a defect of a valve or of a piston ring. The internal combustion engine from this development particularly advantageously enables a detailed determination of which component of a cylinder needs to be repaired and / or replaced as part of a maintenance. As a result, maintenance of the internal combustion engine can be made particularly effective. In a preferred refinement of the internal combustion engine, the monitoring device furthermore has a control unit which is designed to trigger a measurement of the cylinder pressure by the respective cylinder pressure sensor and / or a determination of the presence of an anomaly by the analysis unit at regular time intervals. In the context of this development, the monitoring effort can be reduced by the user and / or manufacturer of the internal combustion engine particularly advantageous. In particular, the monitoring can be automated in such a way that no manual triggering of an activation of the monitoring device is necessary. The regular time intervals are typically a predetermined time interval, such as every 10 seconds, every 5 minutes, every hour, every 2 hours. The monitoring of the cylinder pressure of each individual cylinder of the internal combustion engine can be done for each working cycle. Furthermore, the regular time intervals can be formed by an engine-related event, such as a start of an operation of the internal combustion engine according to the invention or a termination of an operation of an internal combustion engine according to the invention.

In a further development, the internal combustion engine further comprises a warning device with a transmitting unit, wherein the warning device is connected to the analysis unit and is designed to generate an output signal in the presence of an anomaly of the cylinder pressure and output via the transmitting unit, in particular to an external monitoring device Manufacturer and / or a user of the internal combustion engine. Preferably, the monitoring of the internal combustion engine by the monitoring device by means of the external monitoring device is a service of the manufacturer, which may optionally inform the user of the internal combustion engine, if there is a significant malfunction of the cylinder of the internal combustion engine. The output signal may in particular be an optical or acoustic output signal.

In a further development of the method according to the invention for monitoring an operation of an internal combustion engine, the method further comprises calculating a current cylinder pressure curve with current cylinder pressure curve coefficients from discrete values of the determined time characteristic of the cylinder pressure data of the cylinder, wherein the determination of whether there is an anomaly of the cylinder pressure, based on the current cylinder pressure curve.

In a preferred embodiment of the method according to the invention, the method further comprises the additional step of triggering an output signal, if a presence of an anomaly of the cylinder pressure is determined.

In a further development of the method according to the invention, determining whether an anomaly of the cylinder pressure is present is based on predetermined desired pressure data as an adequate reference, in particular on a predetermined desired pressure curve.

Embodiments of the invention will now be described below with reference to the drawing. This is not necessarily to scale the embodiments, but the drawing, where appropriate for explanation, executed in a schematized and / or slightly distorted form. With regard to additions to the teachings directly recognizable from the drawing reference is made to the relevant prior art. It should be noted that various modifications and changes may be made in the form and detail of an embodiment without departing from the general idea of the invention. The disclosed in the description, in the drawing and in the claims features of the invention may be essential both individually and in any combination for the development of the invention. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiments shown and described below Embodiment or limited to an object that would be limited compared to the claimed in the claims subject. For the given design ranges, values within the stated limits should also be disclosed as limit values and be arbitrarily usable and claimable. For simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar function.

Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiments and from the drawing.

In detail, the drawing shows in:

FIG. 1 is an illustration of an embodiment of the invention

 Internal combustion engine, wherein a monitoring device of

Internal combustion engine, an analysis unit and for each cylinder of the engine one

Cylinder pressure sensor comprises;

FIG. 2a is a first diagram with three cylinder pressure curves and four through the

 Cylinder pressure curves presented symptoms;

FIG. 2b shows a second diagram with three cylinder pressure curves and two through the

 Cylinder pressure curves presented symptoms;

FIG. 2c a third diagram with two cylinder pressure curves and two through the

 Cylinder pressure curves presented symptoms;

FIG. 3 is a flow chart of an embodiment of a device according to the invention

 Process.

FIG. 1 shows an illustration of an exemplary embodiment of the internal combustion engine 100 according to the invention, in which a monitoring device 120 of the internal combustion engine 100 has an analysis unit 140 and, for each cylinder 115 of the engine 110, a cylinder pressure sensor 130.

The monitoring device 120 has, according to the number of cylinders 115, a number of cylinder pressure sensors 130, wherein each cylinder of the number of cylinders 115 is associated with a respective cylinder pressure sensor 130. For clarity, however, only a single cylinder pressure sensor 130 is shown. The assigned one Cylinder pressure sensor 130 is disposed on the respective cylinder 115 of the engine 100 and configured to measure a cylinder pressure of the respective cylinder 115, to determine cylinder pressure data corresponding to the cylinder pressure, and to output a respective cylinder pressure signal 135 indicating the cylinder pressure data.

The analysis unit 140 of the monitoring device 120 is designed to receive the respective cylinder pressure signal 135, in particular to receive the cylinder pressure signal 135 assigned to a respective cylinder 115. In an embodiment not shown, the internal combustion engine has more than one analysis unit, for example a first analysis unit for an A side of the engine and a second analysis unit for a B side of the engine.

Furthermore, the analysis unit 140 is designed to determine from the chronological progression of the cylinder pressure data of the respective cylinder for each individual cylinder whether there is an anomaly of the cylinder pressure. In particular, the analysis unit 140 is designed to determine individually for each cylinder whether there is an anomaly of the cylinder pressure during a compression phase of the respective cylinder during operation of the engine. This determination is carried out for each of the output from the individual cylinder pressure sensors 130 Zy cylinder pressure signals 135. Here, the individual cylinder pressure signals 135 can be evaluated successively or in parallel. The anomaly can be determined here as a symptom occurring in the course of time of the cylinder pressure data. The analysis unit of the illustrated exemplary embodiment is designed to determine a measured dependence between cylinder pressure and crank angle of the respective cylinder from the chronological course of the cylinder pressure data and to examine individual features of this measured dependency as a symptom. In the context of such an examination, the symptom is related to an adequate reference of the cylinder pressure data, in particular compared. If there is a significant proportionate size of the symptom compared to the adequate reference, so a difference between the symptom and the adequate reference is found, which is not probable during a faultless operation of the engine, is based on the presence of anomalies, in particular extent and nature of the Anomaly, closed. Examples of various symptoms and adequate references suggesting the presence of an abnormality are shown in FIGS. 2a, 2b and 2c presented. In the illustrated embodiment, the monitoring device 120 further includes a memory unit 150 connected to the analysis unit 140 and configured to store predetermined desired pressure data indicative of a desired pressure waveform of the engine 110.

The analysis unit 140 is configured to access the predetermined target pressure data and to use the predetermined target pressure data for comparison with the measured cylinder pressure data. In examining some symptoms, the analysis unit 140 uses the predetermined target pressure data as an adequate reference for the comparison of the symptom and, in that context, for a determination of the significant proportionate size of the symptom.

In the illustrated embodiment, the analysis unit 140 is additionally designed to calculate from discrete values of the determined time profile of the cylinder pressure data of the cylinder 115, a current cylinder pressure curve with current cylinder pressure curve coefficients and based on the current cylinder pressure curve to determine whether an anomaly of the cylinder pressure is present.

In the illustrated embodiment, the predetermined target pressure data stored on the storage unit is data supplied to the storage unit 150 prior to operation of the internal combustion engine 100. In one embodiment, not shown, the analysis unit 140 is further configured to determine from predetermined cylinder pressure data during an error-free operation of the engine 110, a target pressure curve of the engine 110 and output to the memory unit 150. Finally, the internal combustion engine 100 has a warning device 160 with a transmitting unit 170. The warning device is connected to the analysis unit 140 and designed to generate an output signal 145 in the event of an anomaly of the cylinder pressure and to output it via the transmission unit 170. In particular, in the illustrated embodiment, the output signal 145 is output to an external monitor 180 of a manufacturer of the internal combustion engine 100. In the illustrated embodiment, the output signal 145 indicates on which cylinder 115 from the number of cylinders of the internal combustion engine 100, the presence of an anomaly of the cylinder pressure has been determined. Furthermore, by the output signal 145, a motor identification number indicating an assignment of the output signal 145 to a motor triggering the output signal 145 is displayed 110 allows. Further, the output signal 145 indicates whether there is a defect of a valve or a piston ring of the corresponding cylinder 115, if such a determination has been made by the analyzing unit 140 in view of the symptom indicating the anomaly.

The output signal 145 triggers an entry within a database 185 of the external monitor 180, which informs the manufacturer of the engine 100 that there is an anomaly of the cylinder pressure. The manufacturer can then inform the user of the internal combustion engine and perform a maintenance of the internal combustion engine 100. In one embodiment, not shown, the monitoring device is further configured to output the output signal to the user of the internal combustion engine. As a result, the user can adjust operation of the internal combustion engine particularly quickly in order to avoid further damage to the internal combustion engine. Furthermore, the internal combustion engine 100 has a control unit 190, which is designed to trigger a measurement of the cylinder pressure by the respective cylinder pressure sensor 130 at regular time intervals, in particular to trigger for each cylinder pressure sensor 130. As a result, an expense of monitoring the internal combustion engine 100 for the user can be reduced to a particular extent. In particular, a manual triggering of an activation of the monitoring device 120 can be completely dispensed with.

FIG. 2a shows a first diagram 200 with three cylinder pressure curves K1, K2 and K3 and five symptoms represented by the cylinder pressure curves. On the x-axis 210 of the first diagram 200, the crank angle KW of -360 ° to 360 ° is shown, where 0 ° represents the top dead center of the internal combustion engine, at which the cylinder pressure curves were measured. Above the y-axis 220 of the first diagram 200, a measured cylinder pressure in bar is shown. For a faultless engine with a functioning valve and 0.3 mm valve clearance at the intake valve, the curve K1 was measured, which shows a maximum maximum cylinder pressure pl max at 0 ° crank angle KWl max. The curve K2 was measured for a cylinder having an intake valve set to be 1 mm open when closed, showing a reduced maximum cylinder pressure p2_max at about 25 ° Crank angle KW2_max before the dead center of the internal combustion engine is located. Finally, the cylinder pressure curve K3 for a cylinder having an intake valve set to open 2 mm in the closed state was measured, showing a further reduced maximum cylinder pressure p3_max, which at about 35 ° crank angle KW3_max before the dead center of Internal combustion engine is located, and thus further shifted from K1 than the crank angle of the maximum cylinder pressure of the curve K2.

The maximum cylinder pressure plmax, p2_max, p3_max of the cylinder examined by a cylinder pressure sensor is a symptom by which the presence of an anomaly, that is to say a malfunction of the engine, can be inferred. Thus, a decreasing maximum cylinder pressure p2_max, p3_max according to the curves K2 and K3 shows a significantly proportionate magnitude of the maximum cylinder pressure compared to a maximum cylinder pressure with a faultless cylinder, as shown in Kl. The analysis unit is hereby adapted, due to the large difference between the maximum cylinder pressure reached in curve K1 and the maximum cylinder reached in the curves K2 and K3, to the presence of an anomaly, in particular to the presence of a malfunction of Close and display the intake valve of the cylinder.

Further, shifting the crank angle KWl_max, KW2_max, KW3_max at which the maximum cylinder pressure is reached, in view of the curves K1, K2, and K3, indicates that there is a malfunction of the intake valve. The crank angle, which is reached at maximum cylinder pressure, in this sense is a symptom that must be compared with an adequate reference for the crank angle at maximum cylinder pressure to determine the presence of an anomaly, so a malfunction of the engine.

In addition or as an alternative to an examination of the maximum cylinder pressure, the respectively indicated mean pressure of the curves K1, K2 and K3 indicates that a malfunction of a valve exists because the indicated mean pressure of the curves K2 and K3 is significantly below an indicated mean pressure of a faultless cylinder according to curve K1 lies.

The curve Kl shows a time characteristic of typical cylinder pressure data in the context of a fault-free operation of an internal combustion engine. Therefore, the curve Kl can be used as a setpoint pressure curve of the engine or engines with comparable operating parameters, to the presence of a marked deviation from the curve Kl Anomaly to be able to close. Whether there is a significant deviation or difference to the cylinder pressure data of the curve K1 is examined, in particular in the crank angle range of an increased compression, ie an increased cylinder pressure. Thus, the shape of the cylinder pressure curve obtained by the measured cylinder pressure data may be a symptom which is compared with a desired pressure curve of Kl as an adequate reference. Such a comparison can be made for example by determining the area between the two curves.

Furthermore, characteristic high frequency cylinder pressure oscillations at a crank angle that is known to close the exhaust valve at this crank angle may indicate a functioning exhaust valve. Thus, Kl, K2 and K3 show in a in FIG. 2a, a significant reduction in the measured cylinder pressure by more than 0.2 bar at the predetermined crank angle KW AV of -350 ° crank angle before the top dead center of the internal combustion engine, which can be concluded that a functional exhaust valve.

FIG. 2b shows a second diagram 250 with the three cylinder pressure curves K1, K2 and K3 and two symptoms represented by the cylinder pressure curves.

The second graph 250 with the x-axis 210 and the y-axis 220 again showed the same curves K1, K2 and K3, the x-axis 210 of the second graph 250 indicating the crank angle between -200 ° crank angle and 200 ° crank angle.

FIG. 2b makes it clear that another symptom represents a degree of symmetry of incoming and outgoing flanks around the top dead center of the internal combustion engine. While the curve K1 is almost perfectly symmetrical about the top dead center of the engine (represented by an axis of symmetry 260), the curves K2 and K3 show a high degree of asymmetry with respect to potential symmetry axes 262, 264 shown to be indicative of a malfunction of a valve of the cylinder leaves. While some asymmetry is always encountered in structural inaccuracies, in a malfunction of the monitored cylinder, the symmetry is lost to a significantly disproportionate extent compared to a structural asymmetry as an adequate reference.

Furthermore, characteristic high-frequency cylinder pressure oscillations at a crank angle KW EV, of which it is known that the intake valve at this crank angle indicates a functioning inlet valve. An illustrated diagram section 270 of the second diagram 250 shows that only the curve K1, which is known to close the intake valve at -184 ° crank angle before the top dead center of the internal combustion engine, a significant jump-off of the cylinder pressure by more than 0.5 bar at this crank angle KW EV shows. On the other hand, the curves K2 and K3 show no such lowering, so that it is possible to decide on a faulty closing of the inlet valves of the cylinders measured according to the curves K2 and K3.

From the shape of the curves that result when the intake and / or exhaust valves of the cylinders of the engine close, additionally or alternatively, an existing valve clearance of the corresponding valves can be concluded. Thus, the curve Kl shows a valve clearance of 0.3 mm. If a valve clearance of 0 mm is present or close to 0 mm, the valve would on the other hand open earlier and close later, which could be seen from the curve by a later drop in the cylinder pressure. Thus, a position of the characteristic pattern for the closing of the intake valve and / or the exhaust valve forms a further symptom, by which an anomaly, namely an optionally excessive valve clearance, can be concluded.

FIG. 2c shows a third plot 280 with the x-axis 210 and the y-axis 220, with the two cylinder pressure curves K2 and K3 and two symptoms represented by the cylinder pressure curves.

The third graph 280 showed the curves K2 and K3 already known from the first and second graphs. As a further symptom of a malfunctioning intake valve, the curves K2 and K3 show a sudden increase in a curvature, which manifests itself in a respective bend 284, 288 of the measured cylinder pressure curve. The curve K2 shows this kink 284 at about 10 ° crank angle after top dead center. The curve K3 shows this kink 288 at about -15 ° crank angle before top dead center but on an outgoing edge of the corresponding cylinder pressure curve.

Such a kink 284, 288 and / or a displacement of the kink 284, 288 over time to lower crank angles, is a symptom by which the presence of an abnormality, namely a faulty cylinder valve, can be concluded. Additionally or alternatively, an abnormality of the cylinder pressure may also be determined based on a minimum cylinder pressure p2_min, p3_min being decreased after reaching a top dead center of the internal combustion engine compared to a minimum cylinder pressure forming the adequate reference before top dead center of the internal combustion engine. The curve K2 shows a significant reduction of the minimum cylinder pressure p2_min compared to a minimum cylinder pressure before the top dead center of the internal combustion engine. K3 also reveals such a reduced minimum cylinder pressure p3_min.

Preferably, the analysis unit of an internal combustion engine according to the invention is designed to evaluate various symptoms of a current cylinder pressure curve resulting from the time profile of the cylinder pressure data by comparison with an adequate reference. Various signs of anomaly, namely multiple symptoms that are significantly larger in size compared to an adequate reference, make this anomaly particularly reliable.

FIG. 3 shows a flow chart of an embodiment of a method 300 according to the invention.

The method 300 according to the invention for monitoring an operation of an internal combustion engine having a number of cylinders has the following four method steps 310, 320, 330, 340. A first method step 310 comprises measuring a respective cylinder pressure for all cylinders of the internal combustion engine.

In a next method step 320, corresponding cylinder pressure data are determined and a cylinder pressure signal indicating the cylinder pressure data is output.

A subsequent method step 330 includes receiving the respective cylinder pressure signal and determining whether there is an anomaly of the cylinder pressure on the basis of a chronological progression of the cylinder pressure data, wherein the anomaly can be determined as occurring in the course of time of the cylinder pressure data A symptom wherein the symptom is compared with an adequate reference of the cylinder pressure data, and wherein a significant proportionate size of the symptom is inferred as compared to the adequate reference to the presence of the anomaly, in particular the extent and nature of the anomaly.

In a further method step 340, the determined anomaly is assigned to a cylinder of the engine.

The method according to the invention preferably carries out the method steps 310, 320 and 330 repeatedly at regular time intervals, at least until an anomaly is determined or the operation of the internal combustion engine is stopped.

In the context of the last method step 340, the presence of the anomaly together with the associated cylinder of the engine is also preferably displayed. This indication typically results in the triggering of an output signal informing a manufacturer and / or user of the engine that preventive maintenance is recommended, particularly for replacement or maintenance of engine valves or piston rings.

LIST OF REFERENCE NUMBERS:

100 internal combustion engine

 110 engine

115 cylinders

 120 monitoring device

 130 cylinder pressure sensor

 135 cylinder pressure signal

 140 analysis unit

145 output signal

 150 storage unit

 160 warning device

 170 transmission unit

 180 external monitor

185 database

 190 control unit

 200 first diagram

 210 x axis

 220 y-axis

230 Diagram section of the first diagram

 250 second diagram

 260 symmetry axis

 262, 264 potential axis of symmetry

 270 Diagram section of the second diagram

280 third diagram

 284, 288 kink

 300 procedures

 310, 320, 330 steps of the procedure

340 pl max maximum cylinder pressure of the curve Kl

p2_max maximum cylinder pressure of curve K2

p3_max maximum cylinder pressure of curve K3

p2_min minimum cylinder pressure after top dead center of curve K2 p3_min minimum cylinder pressure after top dead center of curve K3

K1, K2, K3 Cylinder pressure curve

 KWl max crank angle at maximum cylinder pressure of the curve Kl

KW2_max Crank angle at maximum cylinder pressure of curve K2

KW3_max Crank angle at maximum cylinder pressure of curve K3

KW AV predetermined crank angle for closing the exhaust valve

KW EV predetermined crank angle for closing the intake valve

Claims

An internal combustion engine (100) comprising a motor (110) having a number of cylinders (115) and a monitor (120) for monitoring an operation of Internal combustion engine (100), characterized in that - For each cylinder (115) of the number of cylinders, a respective Zy cylinder pressure sensor (130) of the monitoring device (120) on the respective cylinder (115) of the internal combustion engine (100) is arranged and adapted to a cylinder pressure of the respective cylinder (115 ) to determine cylinder pressure data corresponding to the cylinder pressure and to output a respective cylinder pressure signal (135) indicating the cylinder pressure data; - An analysis unit (140) of the monitoring device (120) is adapted to receive the respective cylinder pressure signal (135) and from a time course of the Cylinder pressure data of the respective cylinder (115) cylinder-individually for each cylinder to determine whether an anomaly of the cylinder pressure is present, in particular whether an anomaly of the Cylinder pressure during a compression phase of the respective cylinder (115) in the operation of Motors (110) is present, wherein  the anomaly can be determined as a symptom occurring in the course of time of the cylinder pressure data,  the symptom is compared with an adequate reference of the cylinder pressure data, and from a significant proportionate size of the symptom compared to the adequate one Reference is made to the presence of the anomaly, in particular extent and nature of the anomaly, and wherein  the analysis unit (140) is further configured to associate the anomaly with the respective cylinder (115) of the engine (110). 2. Internal combustion engine (100) according to claim 1, characterized in that the analysis unit (140) is further formed of discrete values of the determined temporal History of the cylinder pressure data of the cylinder (115) to calculate an actual cylinder pressure curve (Kl, K2, K3) with current cylinder pressure curve coefficients and based on the Current cylinder pressure curve (Kl, K2, K3) to determine whether an anomaly of the cylinder pressure is present. 3. Internal combustion engine (100) according to claim 1 or 2, characterized in that - The monitoring device (120) further comprises a memory unit (150) which is connected to the analysis unit (140) and which is adapted to store predetermined target pressure data, which characterize a desired pressure curve of the motor (110) - The analysis unit (140) is further adapted to access the predetermined target pressure data and to use the predetermined desired pressure data as an adequate reference for the comparison of the symptom. 4. The internal combustion engine according to claim 1, wherein the analysis unit is configured to determine whether there is an abnormality of the cylinder pressure based on detecting a reduction in a symptomatic maximum cylinder pressure of the cylinder compared to a cylinder the adequate reference forming earlier measurement of cylinder pressure. 5. The internal combustion engine according to claim 1, wherein the analysis unit is configured to determine whether there is an abnormality of the cylinder pressure based on detecting a shift of a symptomatic time position of a maximum cylinder pressure relative to a cylinder the adequate reference forming top dead center of the internal combustion engine towards a negative crank angle of the internal combustion engine. 6. The internal combustion engine according to claim 1, wherein the analysis unit is configured to determine whether there is an abnormality of the cylinder pressure, based on a detection of a reduction of a symptomatic indicated mean pressure of the cylinder compared to a cylinder the adequate reference forming earlier measurement of the indicated mean pressure. An internal combustion engine (100) according to any one of the preceding claims, characterized in that the analysis unit (140) is adapted to determine if there is an abnormality of the cylinder pressure based on detecting a reduction in a symptomatic minimum cylinder pressure after reaching a top dead center of the Internal combustion engine compared to a forming the adequate reference minimum cylinder pressure before top dead center of the internal combustion engine. An internal combustion engine (100) according to any one of the preceding claims, characterized in that the analysis unit (140) is adapted to determine if there is an abnormality of the cylinder pressure based on detecting a large increase in a symptomatic curvature of an outgoing flank the time course of the cylinder pressure data resulting cylinder pressure curve after a top dead center of the internal combustion engine. 9. Internal combustion engine (100) according to one of the preceding claims, characterized in that the analysis unit (140) is adapted to determine from a reduction of a symptomatic degree of symmetry of a resulting from the time course of the cylinder pressure data cylinder pressure curve with respect to a top dead center of the internal combustion engine whether there is an abnormality of the cylinder pressure. 10. internal combustion engine (100) according to one of the preceding claims, characterized in that the analysis unit (140) is further formed, based on the cylinder pressure data and a predetermined displacement of the cylinder of the internal combustion engine for at least two different crank angle of the internal combustion engine, a symptomatic current polytropic -Exponent of the cylinder of the internal combustion engine to determine and thereby determine whether an anomaly of the cylinder pressure is present. 11. The internal combustion engine according to claim 1, wherein the analysis unit is configured to determine whether there is an abnormality of the cylinder pressure based on an analysis of a symptomatic pressure history pattern formed by the timing of the cylinder pressure data at the time closing an intake and / or exhaust valve. 12. internal combustion engine (100) according to one of the preceding claims, characterized in that the analysis unit (140) is adapted to additionally present in the presence of an anomaly analysis of a formed by the time course of the cylinder pressure data symptomatic pressure history pattern at the time of closing an intake and or discharge valve of the cylinder and based on the anomaly to assign an anomaly cause, in particular to distinguish whether a defect of a valve or a piston ring is present. 13. Internal combustion engine (100) according to one of the preceding claims, characterized in that the analysis unit (140) is adapted to trigger an output signal (145) if a presence of an anomaly of the cylinder pressure is determined. 14. Internal combustion engine (100) according to claim 13, characterized in that the output signal (145) indicates on which cylinder of the number of cylinders the presence of an anomaly of the cylinder pressure has been determined. 15. Internal combustion engine (100) according to claim 13 or 14, characterized in that the output signal (145) in addition to the presence of the anomaly also indicates an anomaly cause, in particular indicate whether a defect of a valve or a piston ring is present. 16. Internal combustion engine (100) according to one of the preceding claims, characterized in that the monitoring device (120) further comprises a control unit (190) which is designed to measure the cylinder pressure by the respective cylinder pressure sensor (130) and / or determining the Presence of an anomaly by the analysis unit at regular intervals. 17. Internal combustion engine (100) according to one of the preceding claims, characterized in that the internal combustion engine further comprises a warning device (160) with a transmitting unit (170), wherein the warning device (160) is connected to the analysis unit (140) and is designed in the presence of an anomaly of the cylinder pressure to generate an output signal (145) and output via the transmitting unit, in particular to output to an external monitoring device of a manufacturer and / or a user of the internal combustion engine. 18. A method (300) for monitoring an operation of an internal combustion engine with a number of cylinders, in particular an internal combustion engine according to one of claims 1 to 17, comprising the steps: - Measuring a respective cylinder pressure for all cylinders of the internal combustion engine; Determining respective cylinder pressure data and outputting a cylinder pressure signal indicative of the cylinder pressure data; - Receiving the respective cylinder pressure signal and cylinder-individual determination of whether an anomaly of the cylinder pressure is present, based on a time course of the cylinder pressure data, wherein  the anomaly can be determined as a symptom occurring in the course of time of the cylinder pressure data,  the symptom is compared with an adequate reference of the cylinder pressure data, and is concluded from a significant proportionate size of the symptom compared to the adequate reference to the presence of the anomaly, in particular the extent and nature of the anomaly, and assigning the determined anomaly to a cylinder of the anomaly engine. 19. The method of claim 18, wherein the method further comprises calculating a current cylinder pressure curve with current cylinder pressure curve coefficients from discrete values of the determined time history of the cylinder pressure data of the cylinder, and determining if there is an abnormality of the cylinder pressure based on the current cylinder pressure curve. 20. The method according to claim 18 or 19, characterized in that the method further comprises triggering an output signal (145), if a presence of anomaly of the cylinder pressure is determined. 21. The method according to any one of claims 18 to 20, characterized in that the determination of whether an anomaly of the cylinder pressure is based on predetermined desired pressure data as an adequate reference based, in particular on a predetermined target pressure curve. 22. Software comprising program means having a module adapted to control a method for monitoring an operation of an internal combustion engine according to one of claims 18 to 21.