Method for operating internal combustion engine, in particular of motor vehicle, and internal combustion engine

Abstract

The invention relates to a method for operating an internal combustion engine (1), in which at least one irregular combustion occurring in at least one combustion chamber (2) of the internal combustion engine (1) is detected by means of at least one sensor (8). According to the detection of the at least one irregular combustion, the ignition time of the at least one combustion chamber (2) is delayed, and the ignition time is changed from a first value to a second value. The second value of the ignition time is maintained within at least 150 working cycles of the internal combustion engine (1), and even if an irregular combustion occurring in the at least one combustion chamber (2) has not been detected before the end of the at least 150 working cycles, the second value of the ignition time is maintained after the end of the at least 150 working cycles. The ignition time is changed from the second value to the first value so as to be earlier.

Description

Technical Field

[0001] The invention relates to a method for operating an internal combustion engine, in particular an internal combustion engine of a motor vehicle, according to the preamble of claim 1. The invention also relates to an internal combustion engine, in particular an internal combustion engine for a motor vehicle. Background Art

[0002] DE 10 2011 012 722 B4 discloses a method for detecting abnormal combustion in a spark-ignition engine equipped with a vibration sensor for detecting engine vibrations or a cylinder pressure sensor for detecting engine cylinder pressure. EP 3 029 301 B1 discloses a method for operating at least one functional unit of a motor vehicle. DE 10 2013 202 654 B4 discloses a method for operating an engine. DE 10 2010 005 646 B4 discloses a method for controlling a powertrain system including an internal combustion engine having a combustion chamber. Furthermore, DE 10 2019 113 359 A1 discloses a method for operating an engine. Furthermore, DE 10 2006 007 876 A1 discloses a knock detection device for an internal combustion engine. Summary of the Invention

[0003] The object of the present invention is to provide a method for operating an internal combustion engine, in particular an internal combustion engine of a motor vehicle, and an internal combustion engine in order to enable particularly advantageous operation of the internal combustion engine.

[0004] This object is achieved according to the invention by a method having the features of claim 1 and an internal combustion engine having the features of claim 4. Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0005] A first aspect of the present invention relates to a method for operating an internal combustion engine, in particular an internal combustion engine of a motor vehicle (also referred to simply as a vehicle). This means, for example, that the motor vehicle comprises the internal combustion engine in its fully manufactured state and can be driven by the internal combustion engine, wherein, for example, in the method, the motor vehicle is driven by the internal combustion engine. In particular, provision is made for the method to operate the internal combustion engine in its fired operation. In the method, at least one irregular combustion (also referred to as abnormal combustion) occurring in at least one combustion chamber is detected by at least one sensor, for example, configured as a knock sensor and also referred to as a knock sensor. During fired operation, a combustion process occurs in the at least one combustion chamber, in particular such that each combustion process (in particular, exactly) occurs within a corresponding working cycle of the internal combustion engine. In each combustion process, a corresponding fuel-air mixture (also referred to simply as a mixture) is combusted, wherein the mixture contains at least air and, for example, liquid or gaseous fuel. In particular, it is provided that within each working cycle of the internal combustion engine, the respective mixture is ignited at the ignition point in time, in particular by an ignition device, for example, configured as a spark plug, assigned to at least one combustion chamber, in particular in such a manner that at the ignition point in time at least one electric spark is generated by the ignition device, by means of which the respective mixture is ignited and subsequently combusted. For example, the at least one combustion chamber is formed partially by a cylinder of the internal combustion engine and partially by a piston accommodated translationally in the cylinder, that is, in particular, directly bounded. For example, the cylinder is formed by the cylinder block of the internal combustion engine (for example, configured as a cylinder crankcase), wherein the piston is translationally movable relative to the cylinder block. Furthermore, the at least one combustion chamber is formed partially by a combustion chamber head, that is, in particular, directly bounded, wherein, for example, the combustion chamber head is formed by a housing element of the internal combustion engine, for example, a cylinder head, which is configured separately from the cylinder block and connected to the cylinder block. Therefore, the internal combustion engine is preferably configured as a reciprocating piston engine or reciprocating piston machine. The combustion process drives an output shaft of the internal combustion engine, for example, a crankshaft, which can provide torque via its output shaft, in particular for driving a motor vehicle. For this purpose, for example, a piston is articulatedly coupled to the output shaft via a connecting rod, wherein the combustion process drives the piston and, in turn, the connecting rod, the output shaft. For example, the internal combustion engine is designed as a four-stroke engine, so that each operating cycle includes exactly two complete rotations of the output shaft, i.e., exactly 720 crankshaft degrees. In principle, it is conceivable that the internal combustion engine is designed as a two-stroke engine, so that each operating cycle includes exactly two complete rotations of the output shaft, i.e., exactly 360 crankshaft degrees. Since the corresponding mixture is ignited at the ignition moment and is thus spark-ignited, the internal combustion engine is designed as a spark-ignition internal combustion engine, such as a gasoline engine.

[0006] In the method, the ignition timing of the at least one combustion chamber is retarded, in particular by an electronic computing device, based on the detection of at least one combustion irregularity, thereby changing it from a first value to a second value. This means that the ignition timing for igniting the corresponding mixture in the at least one combustion chamber is retarded within each working cycle, thereby changing it from the first value to the second value. In particular, the method is performed by the electronic computing device. A sensor provides, for example, a (particularly electrical) signal that is indicative of the at least one combustion irregularity detected by the sensor. The electronic computing device can, for example, receive this signal and, based on this signal and, therefore, based on the at least one combustion irregularity detected, retarded the ignition timing.

[0007] In order to enable particularly advantageous operation of the internal combustion engine (particularly particularly efficient and / or low-wear operation, in particular ignition operation), the present invention provides that the second value of the ignition timing (particularly after the ignition timing has been changed to the second value) remains unchanged for at least 150 working cycles of the internal combustion engine (particularly continuously and therefore uninterruptedly, i.e., without changing the ignition timing), and that it is changed from the second value back to the first value, and thus brought forward again, only after the end of at least 150 working cycles (i.e., only after at least 150 working cycles have elapsed, i.e., have occurred), even if no irregular combustion occurring in the at least one combustion chamber was detected before the end of at least 150 working cycles (i.e., before the end of at least 150 working cycles). This means that the ignition timing is brought back longer, i.e., remains at the second value, compared to conventional solutions, so that irregular combustion in the at least one combustion chamber, or a certain amount of irregular combustion in the combustion chamber, and thus excessive wear of the internal combustion engine can be reliably avoided. Irregular combustion can be detected, for example, as knock (i.e., detonation combustion) and / or so-called superknock and / or pre-ignition. In the case of pre-ignition, the mixture ignites before the actual ignition moment, potentially generating very high pressures and pressure amplitudes in the combustion chamber. In the case of super-deton, the mixture ignites after its own ignition moment, resulting in high pressure amplitudes that can increase wear, even damage the engine, and cause severe shocks. Detonation is understood to be the normal, normal detonation, which can cause melting of combustion chamber surfaces on the piston and valves. Compared to normal detonation, pre-ignition and super-deton are more severe in terms of pressure and maximum pressure amplitudes. Therefore, higher pressures and pressure amplitudes are generated in pre-ignition and super-deton than in normal detonation, leading to severe mechanical shocks and, in some cases, even to the rupture of the internal combustion engine.

[0008] In order to ensure particularly favorable operation of the internal combustion engine, in one embodiment of the present invention, it is provided that the ignition timing is changed from the second value to the first value and then advanced again (in particular by an electronic computing device) if and only if no irregular combustion is detected in the at least one combustion chamber within at least 150 working cycles.

[0009] Finally, to achieve particularly advantageous operation of the internal combustion engine, it has been found to be particularly advantageous if the sensor detects the at least one irregular combustion as a first irregular combustion. For example, the sensor detects at least one second irregular combustion occurring in the combustion chamber. Based on a signal provided by the sensor and characterizing the detected irregular combustion (particularly by an electronic computing device), the first irregular combustion is assigned to a first combustion type, and the at least one second irregular combustion is assigned to a second combustion type different from the first combustion type. In particular, the electronic computing device determines a first number of irregular combustions occurring in the combustion chamber detected by the sensor and assigned to the first combustion type, and in particular, the electronic computing device determines a second number of irregular combustions occurring in the combustion chamber detected by the sensor and assigned to the second combustion type. In particular, the ignition timing of the at least one combustion chamber is retarded, thereby changing from the first value to the second value, only if or only if at least one of the numbers exceeds a predetermined threshold value greater than zero (for example, stored in a memory of the electronic computing device, particularly an electrical or electronic memory). In other words, if irregular combustion occurring in the combustion chamber, detected by the sensor, is assigned to a first combustion type, then, for example, a first integrator representing a first quantity (or the first integrator itself) is incremented, in particular by exactly 1, so that the first integrator is a first counter that counts irregular combustions assigned to the first combustion type. For example, if irregular combustion occurring in the combustion chamber, detected by the sensor, is assigned to a second combustion type, then, for example, a second integrator representing a second quantity (or the second integrator itself) is incremented, in particular by exactly 1, so that the second integrator representing a second quantity (or the second integrator itself) is a second counter that counts irregular combustions assigned to the second combustion type. In other words, when irregular combustion occurring or having occurred in the combustion chamber, detected by the sensor, is assigned to the corresponding combustion type, the corresponding integrator is incremented. For example, if at least one integrator or counter exceeds a threshold value, also referred to as a threshold, the ignition timing is adjusted later, i.e., retarded.

[0010] The ignition point in time is also referred to as the ignition angle, since the ignition point in time coincides within each working cycle with a rotational position of the output shaft in which the output shaft is located at the ignition point in time.

[0011] For example, the internal combustion engine has a plurality of, and therefore at least two, combustion chambers, namely, at least one combustion chamber serving as a first combustion chamber and at least one second combustion chamber, wherein the preceding and following descriptions regarding the at least one combustion chamber (i.e., the first combustion chamber) also apply to the second combustion chamber, and vice versa. Preferably, provision is made for a separate retardation of the ignition timing for each combustion chamber (in particular, for each cylinder), such that, for example, the ignition timing of the at least one combustion chamber (the first combustion chamber) is retarded, while the ignition timing of the second combustion chamber is not retarded. This allows for a response to any irregular combustion that may occur for each combustion chamber (in particular, for each cylinder), thereby ensuring, on the one hand, low-wear operation of the internal combustion engine and, on the other hand, efficient operation.

[0012] The ignition timing is adjusted earlier, i.e., the ignition timing is changed from the second value back to the first value, also known as back-ramp control, and is achieved, for example, by decrementing the corresponding integrator over time. Compared to conventional control in conventional solutions, the method according to the invention maintains the ignition timing later for a significantly longer time, thereby ensuring particularly advantageous operation.

[0013] A second aspect of the present invention relates to an internal combustion engine (also referred to as an internal combustion engine or combustion engine) which is configured to carry out the method according to the first aspect of the present invention. The advantages and advantageous configurations of the first aspect of the present invention should be regarded as advantages and advantageous configurations of the second aspect of the present invention, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Further details of the present invention will be found in the following description of a preferred embodiment with the aid of the accompanying drawings, in which:

[0015] Figure 1 a schematic diagram of an internal combustion engine, particularly an internal combustion engine of a motor vehicle; and

[0016] Figure 2 is a block diagram for illustrating a method for operating an internal combustion engine. DETAILED DESCRIPTION

[0017] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0018] Figure 1 A schematic diagram shows an internal combustion engine 1 (also called engine, internal combustion engine or combustion engine) of a motor vehicle (also called vehicle for short), which can be driven by the internal combustion engine 1 .

[0019] Figure 2A block diagram is shown for illustrating a method for operating an internal combustion engine 1 in a fired mode. In particular, the internal combustion engine drives a motor vehicle during the method. Internal combustion engine 1 is configured as a reciprocating piston engine, thus a reciprocating piston machine, and has at least two combustion chambers 2 and 3, each of which is partially bounded by a corresponding cylinder 4 and 5 of the internal combustion engine. Cylinders 4 and 5 are formed by a cylinder block 6 of internal combustion engine 1 (e.g., a crankcase). Each cylinder 4 and 5 accommodates a corresponding translationally movable piston, which is thus translationally movable relative to cylinder block 6. Combustion chamber 2 is partially bounded by a piston accommodated in cylinder 4, and combustion chamber 3 is partially bounded by a piston accommodated in cylinder 5. Each piston is articulatedly coupled to an output shaft 7 of internal combustion engine 1 via a corresponding connecting rod, wherein output shaft 7 is rotatable relative to cylinder block 6. During ignition operation, a combustion process occurs in each combustion chamber 2, 3, thereby driving the piston and, via the connecting rod, the output shaft 7, which is designed as a crankshaft. Consequently, the output shaft 7 rotates relative to the cylinder block 6. Internal combustion engine 1 can provide torque for driving the motor vehicle via the output shaft 7. Within each working cycle of internal combustion engine 1, a combustion process (particularly, exactly) occurs in each combustion chamber 2, 3. In the respective combustion process that takes place (i.e., occurs) in each combustion chamber 2, 3 within each working cycle, and therefore within each working cycle, the respective fuel-air mixture (also referred to as mixture) is ignited at the ignition point in time and thus combusts, such that within each working cycle, the respective mixture is ignited at the respective ignition point in time within the respective working cycle.

[0020] Reference will be made below to the combustion chamber 2 , so that the aforementioned method will be explained with particular reference to the combustion chamber 2 , wherein the preceding and following explanations regarding the combustion chamber 2 can also be readily transferred to the combustion chamber 3 and vice versa.

[0021] In a first step S1 of the method, at least one Figure 1 Sensor 8, shown schematically in particular, detects at least one irregular combustion event occurring in combustion chamber 2. In a second step S2 of the method, the ignition timing of combustion chamber 2 (i.e., the ignition timing at which the corresponding mixture is ignited and subsequently burns in combustion chamber 2 within each working cycle) is retarded based on the detection of the at least one irregular combustion event (in particular, by electronic computing device 9), thereby changing from a first value to a second value. Within the respective working cycle, the ignition timing corresponds to a rotational position of output shaft 7 that the output shaft is in at the ignition timing within the respective working cycle. Therefore, the ignition timing is also referred to as the ignition angle. For example, electronic computing device 9 (also referred to as a control device or configured as a control device) is a component of internal combustion engine 1.

[0022] In order to achieve particularly advantageous operation of the internal combustion engine 1, the method provides that the second value of the ignition timing remains unchanged for at least 150 working cycles of the internal combustion engine 1, and even if no irregular combustion is detected in the combustion chamber 2 before the end of the at least 150 working cycles, it is not changed from the second value to the first value, and thus brought forward again, until at least 150 working cycles have ended (particularly by the electronic computing device 9). This makes it possible to avoid irregular combustion that places excessive stress on the internal combustion engine 1, or particularly advantageously to keep the number of such irregular combustion that places excessive stress on the internal combustion engine 1 low (particularly over the service life of the internal combustion engine 1), thereby ensuring advantageous low-wear operation of the internal combustion engine 1.

[0023] Reference Signs List

[0024] 1 Internal combustion engine

[0025] 2 combustion chambers

[0026] 3 combustion chambers

[0027] 4 cylinders

[0028] 5 cylinders

[0029] 6-cylinder block

[0030] 7 output shaft

[0031] 8 sensors

[0032] 9 Electronic computing devices

[0033] S1 First step

[0034] S2 second step.

Claims

1. A method for operating an internal combustion engine (1), wherein: - detecting at least one irregular combustion occurring in at least one combustion chamber (2) of the internal combustion engine (1) by means of at least one sensor (8); and - based on the detection of the at least one irregular combustion, retarding the ignition timing of the at least one combustion chamber (2), thereby changing the ignition timing from a first value to a second value; The invention is characterized in that the second value of the ignition timing is maintained within at least 150 working cycles of the internal combustion engine (1), and even if irregular combustion occurring in the at least one combustion chamber (2) is not detected before the end of the at least 150 working cycles, the ignition timing is changed from the second value to the first value, thereby being adjusted earlier, only after the end of the at least 150 working cycles.

2. The method according to claim 1, characterized in that The ignition timing is changed from the second value to the first value if and only if no irregular combustion is detected in the at least one combustion chamber (2) within the at least 150 working cycles.

3. The method according to claim 1 or 2, characterized in that: - detecting the at least one irregular combustion as a first irregular combustion by the sensor (8); - detecting at least one second irregular combustion occurring in the combustion chamber by means of the sensor (8); - assigning the first irregular combustion to a first combustion type and assigning the at least one second irregular combustion to a second combustion type different from the first combustion type based on a signal provided by the sensor (8) and characterizing the detected irregular combustion; - determining a first number of irregular combustions occurring in the combustion chamber (2), detected by the sensor (8) and assigned to the first combustion type; - determining a second number of irregular combustions occurring in the combustion chamber (2), detected by the sensor (8) and assigned to the second combustion type; and - when at least one of the quantities exceeds a predetermined threshold value greater than zero, retarding the ignition timing of the at least one combustion chamber (2), thereby changing the ignition timing from the first value to a second value.

4. An internal combustion engine (1) configured to carry out the method according to any one of the preceding claims.

Images