Method for operating an internal combustion engine, in particular of a 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 taking place in at least one combustion chamber (2) of the internal combustion engine (1) is detected by means of at least one sensor (8). Depending on the detection of the at least one irregular combustion, an ignition timing of the at least one combustion chamber (2) is retarded and, as a result, is changed from a first value to a second value. The second value of the ignition timing is maintained for at least 150 working cycles of the internal combustion engine (1) and is only changed from the second value to the first value, and thereby advanced, after the at least 150 working cycles have expired, even if detection of irregular combustions taking place in the at least one combustion chamber (2) ceases before the at least 150 working cycles have expired.

Description

[0001] Method for operating an internal combustion engine, in particular a motor vehicle, and internal combustion engine

[0002] The invention relates to a method for operating an internal combustion engine, in particular a motor vehicle, according to the preamble of patent claim 1. Furthermore, the invention relates to an internal combustion engine, in particular for a motor vehicle.

[0003] DE 102011 012 722 B4 discloses a method for detecting abnormal combustion in a spark-ignition engine equipped with a vibration sensor for detecting engine vibration or a cylinder pressure sensor for detecting cylinder pressure of the engine. EP 3 029 301 B1 discloses a method for operating at least one functional unit of a motor vehicle. DE 102013202 654 B4 discloses a method for operating an engine. DE 102010 005646 B4 discloses a method for controlling a drive train comprising an internal combustion engine with a combustion chamber. Furthermore, DE 10 2019 113 359 A1 discloses a method for operating an engine. Furthermore, a button determination device for an internal combustion engine is known from DE 102006 007 876 A1.

[0004] The object of the present invention is to provide a method for operating an internal combustion engine, in particular a motor vehicle, and an internal combustion engine, so that a particularly advantageous operation of the internal combustion engine can be realized.

[0005] This object is achieved according to the invention by a method having the features of patent claim 1 and by an internal combustion engine having the features of patent claim 4. Advantageous embodiments of the invention are the subject of the dependent claims.

[0006] A first aspect of the invention relates to a method for operating an internal combustion engine, in particular a motor vehicle also simply referred to as a vehicle. This means that, for example, the motor vehicle in its fully manufactured state has the internal combustion engine and can be driven by means of the internal combustion engine, wherein, for example, in the method the motor vehicle is driven by means of the internal combustion engine. In particular, it is provided that in the method the internal combustion engine is operated in its fired mode. In the method, at least one irregular combustion taking place in at least one combustion chamber, which is also referred to as an abnormal combustion, is detected by means of at least one sensor, for example designed as a knock sensor and also referred to as a knock sensor.During fired operation, combustion processes take place in the at least one combustion chamber, in particular in such a way that within a respective working cycle of the internal combustion engine, in particular precisely one of the combustion processes takes place. During the respective combustion process, a respective fuel-air mixture, also simply referred to as a mixture, is burned, wherein the mixture comprises at least air and, for example, liquid or gaseous fuel. In particular, it is provided that within the respective working cycle of the internal combustion engine, the respective mixture is ignited at an ignition time, in particular by means of an ignition device, designed, for example, as a spark plug, assigned to the at least one combustion chamber, in particular in such a way that at least one ignition spark is generated by the ignition device at the ignition time, by means of which ignition spark the respective mixture is ignited and subsequently burned.For example, the at least one combustion chamber is formed partly by a cylinder and partly by a piston of the internal combustion engine that is accommodated in the cylinder so as to be translationally movable, that is to say in particular is directly delimited. For example, the cylinder is formed by a cylinder housing of the internal combustion engine, designed for example as a cylinder crankcase, wherein the piston is translationally movable relative to the cylinder housing. Furthermore, the at least one combustion chamber is formed, for example, partly by a combustion chamber roof, that is to say in particular directly delimited, wherein, for example, the combustion chamber roof is formed by a housing element of the internal combustion engine that is designed separately from the cylinder housing and connected to the cylinder housing, in particular a cylinder head. The internal combustion engine is thus preferably designed as a reciprocating piston engine or as a reciprocating piston machine.The combustion processes can drive an output shaft of the internal combustion engine, designed for example as a crankshaft, which can provide torque via its output shaft, in particular for driving the motor vehicle. For this purpose, for example, the piston is articulated to the output shaft via a connecting rod, with the combustion processes driving the piston and thus the output shaft via the connecting rod. For example, the internal combustion engine is designed as a four-stroke engine, so that the respective working cycle comprises exactly two complete revolutions, i.e. a crank angle of the output shaft of exactly 720 degrees. In principle, it would be conceivable for the internal combustion engine to be designed as a two-stroke engine, so that the respective working cycle then comprises exactly two complete revolutions, i.e. a crank angle of the output shaft of exactly 360 degrees.Since the respective mixture is ignited at the ignition point and thus externally ignited, the internal combustion engine is designed as a spark-ignited internal combustion engine such as a gasoline engine.

[0007] In the method, in particular by means of an electronic computing device, the ignition timing of the at least one combustion chamber is retarded and thereby changed from a first value to a second value depending on the detection of the at least one irregular combustion. This means that the ignition timing at which the respective mixture is ignited within the respective working cycle in the at least one combustion chamber is retarded and thus changed from the first value to the second value. In particular, the method is carried out by means of the electronic computing device. The sensor provides, for example, a signal, in particular an electrical signal, which characterizes the at least one irregular combustion detected by the sensor.The electronic computing device can, for example, receive the signal and thus retard the ignition timing as a function of the signal and thus as a function of the detected at least one irregular combustion.

[0008] In order to be able to realize a particularly advantageous, in particular a particularly efficient and / or low-wear, operation, in particular fired operation, of the internal combustion engine, it is provided according to the invention that the second value of the ignition timing, in particular after the ignition timing has been changed to the second value, is maintained over at least 150 working cycles of the internal combustion engine, in particular continuously and thus without interruption, that is to say without changing the ignition timing, and only after the expiration of the at least 150 working cycles, that is to say only after the at least 150 working cycles have expired, and thus have taken place, is it changed from the second value back to the first value and thereby advanced again, even if already before the expiration of the at least 150 working cycles, that is to say before the end of the at least 150 working cycles, a detection of events taking place in the at least one combustion chamber,irregular combustions are avoided. This means that, compared to conventional solutions, the ignition timing is retarded for a longer period, thus being held at the second value, so that irregular combustions in at least one combustion chamber or a number of irregular combustions in the combustion chamber, and thus excessive wear-prone operation of the internal combustion engine, can be reliably avoided. Irregular combustion is considered to include, for example, knocking, i.e., knocking combustion and / or so-called superknocking and / or pre-ignition. Pre-ignition involves the ignition of the mixture before the actual ignition point,This can result in very high pressure and a very high pressure amplitude in the combustion chamber. In superknock, the mixture ignites after its own ignition point, resulting in a high pressure amplitude. This can be highly wear-promoting or even damaging to the engine and lead to harsh knocks. Knocking is a common, normal knocking sound that can occur when a combustion chamber surface melts, causing damage to the piston and valves. Pre-ignition and superknock are more severe than normal knocking in terms of pressure and maximum pressure amplitudes. Therefore, pre-ignition and superknock result in higher pressures and pressure amplitudes than normal knocking, leading to harsh mechanical impacts and possibly even failures of the internal combustion engine.

[0009] In order to ensure particularly advantageous operation of the internal combustion engine, it is provided in one embodiment of the invention that the ignition timing is changed from the second value to the first value and thus advanced again, in particular by means of the electronic computing device, if and only if irregular combustions taking place in the at least one combustion chamber are not detected within the at least 150 working cycles.

[0010] Finally, it has proven particularly advantageous for achieving particularly advantageous operation of the internal combustion engine if the at least one irregular combustion is detected as the first irregular combustion by means of the sensor. For example, at least one second irregular combustion taking place in the combustion chamber is detected by means of the sensor. Based on the signal provided by the sensor and characterizing the detected irregular combustions, 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 by means of the electronic computing device.In particular, the electronic computing device determines a first number of irregular combustions that have occurred in the combustion chamber and are 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 that have occurred in the combustion chamber and are detected by the sensor and assigned to the second combustion type. The ignition timing of the at least one combustion chamber is retarded, and thereby changed from the first value to the second value, in particular when, and preferably only when, at least one of the numbers exceeds a predetermined threshold value that is greater than zero, for example, stored in an electrical or electronic memory of the electronic computing device.In other words, if an irregular combustion detected by the sensor and taking place in the combustion chamber is assigned to the first type of combustion, a first integrator, which characterizes or is the first number, is incremented, for example, by exactly 1, so that the first integrator is a first counter which counts the irregular combustions assigned to the first type of combustion. If, for example, an irregular combustion detected by the sensor and taking place in the combustion chamber is assigned to the second type of combustion, a second integrator, for example, is incremented, for example, by exactly 1, so that the second integrator, which characterizes the second number or is a second counter which counts the irregular combustions assigned to the second type of combustion.In other words, the respective integrator is incremented when an irregular combustion event detected by the sensor, which is taking place or has taken place in the combustion chamber, is assigned to the respective combustion type. For example, if at least one of the integrators or counters exceeds the threshold value, also simply referred to as the threshold, the ignition timing is retarded, i.e., shifted later.

[0011] The ignition timing is also called the ignition angle, since the ignition timing within the respective working cycle coincides with a rotational position of the output shaft, which is in the rotational position at the ignition timing.

[0012] For example, the internal combustion engine has a plurality of, and thus at least two, combustion chambers, namely the at least one combustion chamber as the first combustion chamber and at least one second combustion chamber, wherein the previous and following statements regarding the at least one combustion chamber, and thus the first combustion chamber, can also be applied to the second combustion chamber and vice versa. In this case, a retardation of the ignition timing is preferably provided for each combustion chamber individually, in particular for each cylinder, so that, for example, the ignition timing of the at least one combustion chamber (first combustion chamber) is retarded, while an adjustment of the ignition timing of the second combustion chamber does not take place. This makes it possible to react to any irregular combustion that may occur on a combustion chamber-by-combustion chamber-by-combustion chamber-by-cylinder basis, so that, on the one hand, low-wear and, on the other hand, efficient operation of the internal combustion engine can be ensured.

[0013] Advancing the ignition timing, i.e., changing the ignition timing from the second value back to the first value, is also referred to as ramping back, which is achieved, for example, by decrementing the ignition timing over time, particularly by the respective integrator. In contrast to conventional control in conventional solutions, the method according to the invention maintains the retarded ignition timing for a significantly longer period, thus ensuring particularly advantageous operation.

[0014] A second aspect of the invention relates to an internal combustion engine, also referred to as an internal combustion engine or combustion engine, which is designed to carry out a method according to the first aspect of the invention. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention, and vice versa.

[0015] Further details of the invention will become apparent from the following description of a preferred embodiment with the accompanying drawings. In the drawings:

[0016] Fig. 1 is a schematic representation of an internal combustion engine, in particular of a motor vehicle; and

[0017] Fig. 2 is a block diagram illustrating a method for

[0018] Operating the internal combustion engine. In the figures, identical or functionally equivalent elements are provided with the same reference numerals.

[0019] Fig. 1 shows a schematic representation of an internal combustion engine 1, also referred to as a motor, internal combustion engine or internal combustion engine, of a motor vehicle, also simply referred to as a vehicle, which can be driven by means of the internal combustion engine 1.

[0020] Fig. 2 shows a block diagram to illustrate a method for operating the internal combustion engine 1, which is operated in a fired mode during the method. In particular, it is provided that the internal combustion engine drives the motor vehicle during the method, i.e. during the method. The internal combustion engine 1 is designed as a reciprocating piston engine, and therefore as a reciprocating piston machine, and has at least two combustion chambers 2 and 3, wherein the respective combustion chamber 2, 3 is partially delimited by a respective cylinder 4, 5 of the internal combustion engine. The cylinders 4 and 5 are formed by a cylinder housing 6 of the internal combustion engine 1, which is designed, for example, as a cylinder crankcase. A respective piston is received in the respective cylinder 4, 5 so as to be translationally movable and is thus translationally movable relative to the cylinder housing 6.The combustion chamber 2 is partially delimited by the piston housed in the cylinder 4, and the combustion chamber 3 is partially delimited by the piston housed in the cylinder 5. Each piston is articulated to an output shaft 7 of the internal combustion engine 1 via a respective connecting rod, the output shaft 7 being rotatable relative to the cylinder housing 6. During fired operation, combustion processes take place in the respective combustion chamber 2, 3, driving the pistons and thus, via the connecting rods, the output shaft 7 designed as a crankshaft. This rotates the output shaft 7 relative to the cylinder housing 6. The internal combustion engine 1 can provide torque for driving the motor vehicle via the output shaft 7. Within each working cycle of the internal combustion engine 1, one of the combustion processes takes place, in particular precisely, in the respective combustion chamber 2, 3.During the respective combustion process occurring within the respective combustion chamber 2, 3, i.e., taking place within the respective working cycle, and thus within the respective working cycle, a respective fuel-air mixture, also referred to as a mixture, is ignited at an ignition point and thereby combusted, so that the respective mixture is ignited within the respective working cycle at the respective ignition point within the respective working cycle. Reference is made below to combustion chamber 2, so that the aforementioned method is explained in particular with reference to combustion chamber 2, wherein the previous and following explanations regarding combustion chamber 2 can readily be applied to combustion chamber 3, and vice versa.

[0021] In a first step S1 of the method, at least one irregular combustion taking place in the combustion chamber 2 is detected by means of at least one sensor 8, shown particularly schematically in Fig. 1. In a second step S2 of the method, depending on the detection of the at least one irregular combustion, in particular by means of an electronic computing device 9, the ignition point of the combustion chamber 2, i.e. the ignition point at which the respective mixture in the combustion chamber 2 is ignited and subsequently burned within the respective working cycle, is retarded and thereby changed from a first value to a second value. Within the respective working cycle, the ignition point coincides with a rotational position of the output shaft 7, which is in the aforementioned rotational position at the ignition point within the respective working cycle. The ignition point is therefore also referred to as the ignition angle.For example, the electronic computing device 9, also referred to as a control unit or designed as a control unit, is a component of the internal combustion engine 1.

[0022] In order to be able to realize a particularly advantageous operation of the internal combustion engine 1, it is provided in the method that the second value of the ignition point is maintained over at least 150 working cycles of the internal combustion engine 1 and is only changed from the second value to the first value and thereby adjusted back to an advanced position after the expiration of the at least 150 working cycles, in particular by means of the electronic computing device 9, even if irregular combustions taking place in the combustion chamber 2 are not detected before the expiration, that is to say before the end of the at least 150 working cycles.As a result, irregular combustions that place excessive strain on the internal combustion engine 1 can be avoided, or the number of such irregular combustions that place excessive strain on the internal combustion engine 1 can be advantageously kept low, particularly over the service life of the internal combustion engine 1, so that advantageous, low-wear operation of the internal combustion engine 1 can be ensured. List of reference symbols.

[0023] internal combustion engine

[0024] combustion chamber

[0025] combustion chamber

[0026] cylinder

[0027] cylinder

[0028] Cylinder housing

[0029] Output shaft

[0030] Sensor electronic computing device first step second step

Claims

Patent claims 1. A method for operating an internal combustion engine (1), in which: - at least one irregular combustion taking place in at least one combustion chamber (2) of the internal combustion engine (1) is detected by means of at least one sensor (8); and - depending on the detection of the at least one irregular combustion, an ignition timing of the at least one combustion chamber (2) is retarded and thereby changed from a first value to a second value; characterized in that the second value of the ignition timing is maintained over at least 150 working cycles of the internal combustion engine (1) and is only changed from the second value to the first value and thereby advanced after the expiration of the at least 150 working cycles, even if irregular combustions taking place in the at least one combustion chamber (2) are not detected before the expiration of the at least 150 working cycles.

2. 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, within the at least 150 working cycles, irregular combustions taking place in the at least one combustion chamber (2) are not detected.

3. Method according to claim 1 or 2, characterized in that: - the at least one irregular combustion is detected as the first irregular combustion by means of the sensor (8); - at least one second irregular combustion taking place in the combustion chamber is detected by means of the sensor (8); - based on a signal provided by the sensor (8) and characterising the detected irregular combustions, the first irregular combustion of a first type of combustion and the at least one second irregular Combustion is assigned to a second combustion type different from the first combustion type; - a first number of irregular combustions detected by the sensor (8) and assigned to the first type of combustion, which have taken place in the combustion chamber (2), is determined; - a second number of irregular combustions detected by the sensor (8) and assigned to the second type of combustion, which have taken place in the combustion chamber (2), is determined; and - the ignition timing of the at least one combustion chamber (2) is retarded and thereby changed from the first value to a second value if at least one of the numbers exceeds a predetermined threshold value which is greater than zero.

4. Internal combustion engine (1) which is designed to carry out a method according to one of the preceding claims.

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