Misfire detection device and misfire detection method for internal combustion engine

Abstract

To provide an internal combustion engine misfire detection device and a misfire detection method capable of detecting all cylinder misfire with improved promptness.SOLUTION: An internal combustion engine misfire detection device 10 which detects misfire of an internal combustion engine having a plurality of cylinders comprises: A pulsation component acquisition section 11 which performs frequency analysis of operation parameter data indicating a temporal change in an operation parameter correlated with an entire operation state of the plurality of cylinders and acquires a pulsation component spectrum which is a frequency spectrum of pulsation of the internal combustion engine; a differential parameter acquisition section 12 which acquires a differential parameter correlated with a degree of a difference in respective operation of the plurality of cylinders; and an all cylinder misfire determination section 41 which determines that the internal combustion engine has all cylinder misfire when the pulsation component spectrum acquired through the pulsation component acquisition section 11 is less than a first threshold and the differential parameter acquired through the differential parameter acquisition section 12 is less than a second threshold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a misfire detection device and a misfire detection method for an internal combustion engine. [Background technology]

[0002] Conventionally, misfire detection devices for detecting misfires in internal combustion engines have been known. For example, the misfire detection device disclosed in Patent Document 1 performs frequency analysis on the angular acceleration of the engine obtained based on the detection results of a crank angle sensor. Furthermore, based on the results of the frequency analysis, the misfire detection device determines individually for each cylinder whether the inter-cylinder component of the angular acceleration (the component corresponding to the period of one combustion cycle of the internal combustion engine divided by the number of cylinders in the internal combustion engine) is smaller than a threshold value. In this way, it is determined whether a misfire has occurred in any one of the multiple cylinders that make up the internal combustion engine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-106417 Summary of the Invention [Problem to be solved by the invention]

[0004] The misfire detection device described above individually determines whether a misfire has occurred in each of the multiple cylinders that make up the internal combustion engine, which can take a long time to detect all-cylinder misfires. As a result, there is a concern that the amount of unburned gas generated when all-cylinder misfires occur may increase. For example, in the case of an internal combustion engine used for power generation, which has a large number of cylinders, there is a concern that the detection of all-cylinder misfires may be delayed, resulting in a large amount of unburned gas being generated.

[0005] An object of the present disclosure is to provide a misfire detection device and a misfire detection method for an internal combustion engine that can detect misfire in all cylinders more quickly. [Means for solving the problem]

[0006] A misfire detection device for an internal combustion engine according to at least one embodiment of the present disclosure includes: A misfire detection device for an internal combustion engine for detecting misfire in an internal combustion engine having a plurality of cylinders, a pulsation component acquisition unit for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a difference parameter acquisition unit for acquiring a difference parameter correlated with a degree of difference between the operations of each of the plurality of cylinders; an all-cylinder misfire determination unit for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired by the pulsating component acquisition unit is below a first threshold value and the difference parameter acquired by the difference parameter acquisition unit is below a second threshold value; Equipped with.

[0007] A misfire detection device for an internal combustion engine according to at least one embodiment of the present disclosure includes: A misfire detection device for an internal combustion engine for detecting misfire in an internal combustion engine having a plurality of cylinders, a pulsation component acquisition unit for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a change rate parameter acquisition unit for acquiring a change rate parameter, which is an absolute value indicating a degree of change in an operating parameter correlated with an overall operating status of the plurality of cylinders; an all-cylinder misfire determination unit for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired by the pulsating component acquisition unit is below a first threshold value and the absolute value of the change rate parameter acquired by the change rate parameter acquisition unit is above a fourth threshold value; Equipped with.

[0008] A method for detecting misfire in an internal combustion engine according to at least one embodiment of the present disclosure includes: A misfire detection method for an internal combustion engine having a plurality of cylinders, comprising: a pulsation component acquisition step for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a difference parameter acquisition step for acquiring a difference parameter correlated with a degree of difference in operation of each of the plurality of cylinders; an all-cylinder misfire determination step for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired in the pulsating component acquisition step is below a first threshold value and the difference parameter acquired in the difference parameter acquisition step is below a second threshold value; Equipped with.

[0009] A method for detecting misfire in an internal combustion engine according to at least one embodiment of the present disclosure includes: A misfire detection method for an internal combustion engine having a plurality of cylinders, comprising: a pulsation component acquisition step for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a change rate parameter acquisition step for acquiring a change rate parameter which is an absolute value indicating a degree of change in an operating parameter correlated with an overall operating status of the plurality of cylinders; an all-cylinder misfire determination step for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired in the pulsating component acquisition step is below a first threshold value and the absolute value of the change rate parameter acquired in the change rate parameter acquisition step is above a fourth threshold value; Equipped with. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a misfire detection device and a misfire detection method for an internal combustion engine that can detect all-cylinder misfires more quickly. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a conceptual diagram illustrating a schematic configuration of a misfire detection system according to an embodiment of the present disclosure. [Figure 2] 1 is a conceptual diagram showing the configuration of a misfire detection device according to a first embodiment of the present disclosure. [Figure 3] 1 is a graph conceptually illustrating operational parameter data according to an embodiment of the present disclosure. [Figure 4] 10 is a graph conceptually illustrating the results of a short-time Fourier transform being applied to motion parameter data according to an embodiment of the present disclosure. [Figure 5] 10 is a matrix illustrating the relationship between a pulsating component spectrum, a difference parameter, all-cylinder misfire, and partial misfire according to an embodiment of the present disclosure. [Figure 6A] 10 is a graph conceptually illustrating the results of applying a short-time Fourier transform to target data according to an embodiment of the present disclosure. [Figure 6B] FIG. 4 is a diagram conceptually illustrating a relationship between sensor values ​​of a plurality of cylinder sensors and a difference parameter according to an embodiment of the present disclosure. [Figure 7] 3 is a flowchart showing a misfire detection method for an internal combustion engine according to a first embodiment of the present disclosure. [Figure 8] FIG. 4 is a conceptual diagram showing the configuration of a misfire detection device according to a second embodiment of the present disclosure. [Figure 9] 10 is a graph illustrating changes over time in an operating parameter and a rate of change parameter according to an embodiment of the present disclosure. [Figure 10] 10 is a matrix illustrating the relationship between a pulsating component spectrum, a rate of change parameter, an all-cylinder misfire, and a partial misfire according to an embodiment of the present disclosure. [Figure 11] 6 is a flowchart showing a misfire detection method for an internal combustion engine according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," or "have" one element are not exclusive expressions that exclude the presence of other elements. Note that the same components will be denoted by the same reference numerals and the description thereof will be omitted.

[0013] <Example of Schematic Configuration of Misfire Detection System 100> 1 is a conceptual diagram showing a schematic configuration of a misfire detection system according to one embodiment of the present disclosure. In some embodiments, the misfire detection system 100 includes an internal combustion engine 1 and a misfire detection device 10 for the internal combustion engine (hereinafter, may be simply referred to as the "misfire detection device 10"). Below, examples of the schematic configurations of the internal combustion engine 1 and the misfire detection device 10 are shown.

[0014] The internal combustion engine 1 of this example is a gas engine for generating electricity, which drives a generator by combusting combustible gas supplied to each cylinder 2. The internal combustion engine 1 has a plurality of cylinders 2. The number of cylinders 2 may be any number, such as four, eight, or sixteen. Each cylinder 2 communicates with an intake pipe 5 via an intake manifold 3 and with an exhaust pipe 6 via an exhaust manifold 4. The internal combustion engine 1 is also provided with a turbocharger 15 having a compressor 7 provided in the intake pipe 5 and a turbine 24 provided in the exhaust pipe 6. The compressor 7 is configured to supply compressed gas to each cylinder 2. The turbine 24 is configured to rotate together with the compressor 7 by exhaust gas discharged from each of the plurality of cylinders 2. In this specification, the term "exhaust gas" is a concept that includes combustion gas and unburned gas.

[0015] Combustible gas flowing through intake pipe 5 is supplied to each cylinder 2 and then ignited by spark plug 17 for combustion. As combustion gas is generated, power is extracted and the crankshaft (not shown) rotates. Exhaust gas discharged from each cylinder 2 flows to turbine 24 via exhaust pipe 6.

[0016] Furthermore, ignition in each cylinder 2 is controlled by the ECU 9. Specifically, ignition by the spark plug 17 is executed when the ECU 9 sends an ignition command signal to the ignition device 8. If ignition is executed normally in each of the plurality of cylinders 2, the crankshaft rotates at a specified rotation speed due to the power extracted in turn from each cylinder 2. Note that although one spark plug 17 is shown in the conceptual diagram of FIG. 1, a plurality of spark plugs 17 may be provided inside each cylinder 2.

[0017] The ECU 9 is configured as a computer and includes a processor, a memory, and an external communication interface. The processor may be a CPU, a GPU, an MPU, a DSP, or a combination thereof. The processor may be implemented as an integrated circuit such as a PLD, an ASIC, an FPGA, or an MCU. The memory is configured to temporarily or non-temporarily store various data and may be implemented, for example, as a RAM, a ROM, a flash memory, or a combination thereof. The processor processes the data according to instructions of a program loaded into the memory, thereby generating various control signals, such as an ignition instruction signal to be sent to the ignition device 8.

[0018] In the illustrated embodiment, the ECU 9 is electrically connected to a crank angle sensor 51, a turbo speed sensor 52, a turbine pressure sensor 53, and multiple exhaust gas temperature sensors 54. However, in the conceptual diagram of FIG. 1 , for ease of understanding, only the crank angle sensor 51 among these sensors is illustrated as being connected to the ECU 9. The crank angle sensor 51 is configured to acquire the rotation angle of the crankshaft of the internal combustion engine 1. Therefore, the ECU 9 can acquire the engine speed of the internal combustion engine 1 based on the detection result of the crank angle sensor 51. The turbo speed sensor 52 is configured to detect the turbo speed, which is the rotation speed of the turbocharger 15. The turbine pressure sensor 53 is configured to detect the inlet exhaust gas pressure of the turbine 24 (i.e., the pressure of the exhaust gas flowing into the turbine 24). The multiple exhaust gas temperature sensors 54 are provided corresponding to each of the multiple cylinders 2. Each exhaust gas temperature sensor 54 is configured to detect the temperature of the exhaust gas discharged from the corresponding cylinder 2.

[0019] In other embodiments, any one of the crank angle sensor 51, the turbo speed sensor 52, the turbine pressure sensor 53, and the exhaust gas temperature sensor 54 may not be provided. For example, the crank angle sensor 51 and the turbo speed sensor 52 may be provided, and none of the other sensors may be provided. Alternatively, the turbo speed sensor 52 and the turbine pressure sensor 53 may be provided, and none of the other sensors may be provided.

[0020] The ECU 9 according to one embodiment of the present disclosure includes a misfire detection device 10. The misfire detection device 10 is configured to detect misfire in the internal combustion engine 1. As a more specific example, the misfire detection device 10 is configured to detect all-cylinder misfire, which is a misfire in all of the multiple cylinders 2, and partial misfire, which is a misfire in only one of the multiple cylinders 2. Note that partial misfire is a concept that includes a misfire that occurs in only one of the multiple cylinders 2 (single-cylinder misfire) and a misfire in only one or more of the cylinders 2. In other embodiments, the misfire detection device 10 does not need to detect partial misfire.

[0021] The above has described the outline of the internal combustion engine 1 and the misfire detection device 10. Below, as examples of several embodiments of the present disclosure, a misfire detection device 10A (10) according to a first embodiment and a misfire detection device 10B (10) according to a second embodiment will be described in detail in this order.

[0022] <Detailed Description of the Misfire Detection Device 10A (10) According to the First Embodiment> 2 is a conceptual diagram showing the configuration of a misfire detection device according to the first embodiment of the present disclosure. The misfire detection device 10A (10) includes a pulsating component acquisition unit 11, a difference parameter acquisition unit 12, and a misfire determination unit 40A (40).

[0023] The pulsating component acquisition unit 11 is configured to perform frequency analysis on operation parameter data 61 (see FIG. 3) indicating changes in operation parameters over time, and acquire a pulsating component spectrum Sp (see FIG. 4), which is a spectrum at the frequency of pulsation of the internal combustion engine 1. The operation parameters are parameters that correlate with the overall operating conditions of the multiple cylinders 2 (specific examples will be described later). Therefore, the operation parameters change depending on the presence or absence of pulsation in the internal combustion engine 1 and the degree of pulsation. The frequency analysis performed on the operation parameter data 61 is, for example, FFT, BPF, or STFT (Short-Term Fourier Transform).

[0024] Examples of the operating parameters include the engine speed, the exhaust gas pressure at the inlet of the turbine 24, or the turbo speed. The pulsating component acquiring unit 11 acquires the operating parameter data 61 by continuously acquiring the detection results of the crank angle sensor 51, the turbo speed sensor 52, or the turbine pressure sensor 53.

[0025] FIG. 3 is a graph conceptually illustrating operational parameter data according to an embodiment of the present disclosure. Operational parameter data 61A (61) represents a case in which multiple cylinders 2 are operating normally without misfire. The operational parameters at this time periodically change. Operational parameter data 61B (61) represents a case in which a partial misfire occurs in the internal combustion engine 1 (FIG. 3 illustrates a case in which one cylinder misfire occurs). In this case, the ideal change in the operational parameters does not occur at the timing (t=ta) when combustion should occur in the misfiring cylinder 2. Operational parameter data 61C (61) represents a case in which all cylinders misfire in the internal combustion engine 1. In this case, the operational parameters hardly change periodically after the timing (t≧ta) when all cylinders misfire. Therefore, when either all cylinders misfire or partial misfire occurs, the pulsating component spectrum Sp described above drops significantly (see FIG. 4).

[0026] 4 is a graph conceptually illustrating the results of applying a short-time Fourier transform to operational parameter data according to one embodiment of the present disclosure. More specifically, FIG. 4 illustrates the results of applying a short-time Fourier transform to operational parameter data 61C when an all-cylinder misfire occurs.

[0027] On the vertical axis of the graph shown in Figure 4, f cyl indicates the frequency of the pulsation of the internal combustion engine 1. cyl It does not matter if the value deviates from the ideal value determined by the formula, and the frequency at which a strong spectrum appears in the frequency analysis can be regarded as the pulsation frequency. This is because the actual measured value may deviate from the ideal value due to some factor at the time of measurement.

[0028] As can be seen from FIG. 4, when all-cylinder misfire occurs at a specified timing (t=ta), the pulsating component spectrum Sp disappears or almost disappears. Although detailed illustration is omitted, when partial misfire occurs, the pulsating component spectrum Sp also drops significantly. Therefore, it is possible to determine whether all-cylinder misfire or partial misfire has occurred in the internal combustion engine 1 based on the pulsating component spectrum Sp. Hereinafter, the threshold that serves as the basis for this determination will be referred to as the first threshold. The first threshold may be determined by experiment, simulation, analysis, or a combination of these (the same applies to the second, third, fourth, and fifth thresholds described below).

[0029] Returning to FIG. 2 , the difference parameter acquisition unit 12 is configured to acquire a difference parameter that correlates with the degree of difference (variation) in the operation of each of the multiple cylinders 2. Specific examples of the difference parameter will be described later. When all-cylinder misfire occurs, none of the multiple cylinders 2 operate normally, so the difference parameter becomes small. As a result, the difference parameter at this time falls below a specified threshold value (hereinafter referred to as the second threshold value). Note that, even when all of the multiple cylinders 2 operate normally, the difference parameter is similarly small and falls below the second threshold value. On the other hand, when a partial misfire occurs, one of the multiple cylinders 2 operates normally, while the remaining cylinders 2 do not operate normally. Therefore, the difference parameter at this time is larger than when all-cylinder misfire occurs and when normal operation without misfire occurs, and is equal to or greater than a specified threshold value (hereinafter referred to as the third threshold value). The third threshold value is equal to or greater than the second threshold value, and an embodiment in which the third threshold value and the second threshold value are the same value is not excluded.

[0030] FIG. 5 is a matrix showing the relationship between the pulsating component spectrum, the difference parameter, all-cylinder misfire, and partial misfire according to an embodiment of the present disclosure. As described above, if the pulsating component spectrum Sp acquired by the pulsating component acquisition unit 11 is equal to or greater than the first threshold, it can be determined that no all-cylinder misfire or partial misfire has occurred. If the difference parameter at this time is less than the second threshold, it can be determined that all of the multiple cylinders 2 are operating normally. On the other hand, if the pulsating component spectrum Sp is less than the first threshold, it can be determined that all-cylinder misfire or partial misfire has occurred. In this case, if the difference parameter acquired by the difference parameter acquisition unit 12 is less than the second threshold, it can be determined that all-cylinder misfire has occurred, and if the difference parameter is equal to or greater than the third threshold, it can be determined that partial misfire has occurred.

[0031] The misfire determination unit 40A (40) shown in Fig. 2 includes an all-cylinder misfire determination unit 41A (41). The all-cylinder misfire determination unit 41A is configured to determine the occurrence of all-cylinder misfire in the internal combustion engine 1 in accordance with the criteria described above with reference to Fig. 5. That is, the all-cylinder misfire determination unit 41 is configured to determine that an all-cylinder misfire has occurred in the internal combustion engine 1 when the spectrum acquired by the pulsating component acquisition unit 11 is below a first threshold value and the difference parameter acquired by the difference parameter acquisition unit 12 is below a second threshold value.

[0032] According to the above configuration, when the pulsating component spectrum Sp falls below the first threshold and the difference parameter falls below the second threshold, the all-cylinder misfire determination unit 41A determines that all-cylinder misfire has occurred. Because it is not necessary to individually determine whether a misfire has occurred in each of the multiple cylinders 2, the misfire detection device 10A can detect the occurrence of an all-cylinder misfire more quickly. For example, when the internal combustion engine 1 is used as a power generation engine with 16 or more cylinders 2, the number of cylinders 2 tends to be greater than when the internal combustion engine 1 is used as a vehicle engine, and a large amount of unburned gas may be generated when an all-cylinder misfire occurs. In this regard, by having the all-cylinder misfire determination unit 41A quickly determine the occurrence of an all-cylinder misfire as in the present disclosure, it becomes possible to take appropriate measures before a large amount of unburned gas is generated.

[0033] In other embodiments, the all-cylinder misfire determination unit 41A may determine that the internal combustion engine 1 is operating normally when the spectrum acquired by the pulsating component acquisition unit 11 is equal to or greater than the first threshold value and the difference parameter acquired by the difference parameter acquisition unit 12 is lower than the second threshold value.

[0034] In the embodiment illustrated in Fig. 2, the misfire determination unit 40A (40) includes a partial misfire determination unit 42A (42). The partial misfire determination unit 42A is configured to determine the occurrence of partial misfire in the internal combustion engine 1 in accordance with the criteria described above with reference to Fig. 5. Specifically, the partial misfire determination unit 42A is configured to determine that partial misfire has occurred in the internal combustion engine 1 when the pulsating component spectrum Sp acquired by the pulsating component acquisition unit 11 is below a first threshold value and the difference parameter acquired by the difference parameter acquisition unit 12 is equal to or greater than a third threshold value.

[0035] According to the above configuration, the misfire detection device 10A is equipped with the partial misfire determination unit 42A and the all-cylinder misfire determination unit 41A, and thus can determine with high accuracy whether a misfire that has occurred in the internal combustion engine 1 is a partial misfire or an all-cylinder misfire.

[0036] <First Example of Details of the Difference Parameter Acquisition Unit 12> 2 and 6A, a first example of details of the difference parameter acquisition unit 12 will be described. Fig. 6A is a graph conceptually showing a result of applying a short-time Fourier transform to target data according to an embodiment of the present disclosure.

[0037] The difference parameter acquisition unit 12 is configured to perform frequency analysis on target data indicating a change over time in a sensor value detected by a single sensor. The single sensor may be, for example, a crank angle sensor 51, a turbo speed sensor 52, or a turbine pressure sensor 53. In this case, the sensor value is the engine speed, the turbo speed, or the exhaust gas pressure at the inlet of the turbine 24. Therefore, the sensor value acquired by the difference parameter acquisition unit 12 may be the same as the operation parameter acquired by the pulsating component acquisition unit 11. These sensor values ​​are correlated with the degree of difference in the operation of each of the multiple cylinders 2. This correlation becomes clearer when the target data indicating a change over time in the sensor value is subjected to frequency analysis. Therefore, the difference parameter acquisition unit 12 is configured to perform frequency analysis on the target data and acquire, as a difference parameter, a cycle component spectrum Sc (see FIG. 6B ), which is a spectrum at a frequency corresponding to one cycle of the internal combustion engine 1. For example, one cycle of an internal combustion engine 1 functioning as a four-stroke engine is completed every time the internal combustion engine 1 rotates twice, and for example, one cycle of an internal combustion engine 1 functioning as a two-stroke engine is completed every time the internal combustion engine 1 rotates once.

[0038] The graph illustrated in FIG. 6A shows the spectrum when all cylinders misfire, similar to FIG. 4. In addition, the vertical axis of the graph in FIG. 6A shows the spectrum when all cylinders misfire. Ne is the frequency corresponding to one cycle of the internal combustion engine 1. Ne is f cyl Similarly, deviations from the ideal values ​​obtained by calculation are permitted. When all-cylinder misfire occurs (t=ta), the sensor values ​​hardly change periodically (not shown), and the cycle component spectrum Sc disappears or almost disappears (below the second threshold). Although detailed illustration is omitted, when partial misfire occurs, the sensor values ​​partially change periodically, and the cycle component spectrum Sc becomes equal to or greater than the third threshold.

[0039] Therefore, in the first example, the all-cylinder misfire determination unit 41A can determine that an all-cylinder misfire has occurred when the pulsating component spectrum Sp is below the first threshold value and the cycle component spectrum Sc is below the second threshold value. Also, the partial misfire determination unit 42A can determine that a partial misfire has occurred when the pulsating component spectrum Sp is below the first threshold value and the cycle component spectrum Sc is equal to or greater than the third threshold value.

[0040] With the above configuration, the all-cylinder misfire determination unit 41A can determine whether an all-cylinder misfire has occurred based on the cycle component spectrum Sc. Furthermore, because the cycle component spectrum Sc as difference data is acquired based on sensor values ​​detected by a single sensor, the cycle component spectrum Sc can be detected with a simpler configuration. Therefore, the configuration for detecting the occurrence of an all-cylinder misfire can be simplified. For the same reason, the configuration for detecting the occurrence of a partial misfire can be simplified.

[0041] In one embodiment of the present disclosure, the above-mentioned sensor values ​​are the same as the operating parameters, and the target data indicating changes in the sensor values ​​over time is the same as the operating parameter data 61 (see FIG. 3). That is, the operating parameter data 61 is frequency-analyzed by both the pulsating component acquisition unit 11 and the difference parameter acquisition unit 12. In this case, the graph shown in FIG. 6A can be superimposed on the graph shown in FIG. 4. According to the above configuration, data based on the sensor values ​​detected by a single sensor is frequency-analyzed, thereby acquiring both the pulsating component spectrum Sp and the cycle component spectrum Sc. This makes it possible to further simplify the configuration for detecting the occurrence of all-cylinder misfire. For the same reason, it is also possible to further simplify the configuration for detecting the occurrence of partial misfire.

[0042] The operating parameter according to one embodiment of the present disclosure is the turbo speed sensor 52 or the turbine pressure sensor 53. That is, the above-mentioned sensor value is the turbine speed or the inlet exhaust gas pressure of the turbine 24. These two sensor values ​​respond quickly to all-cylinder misfires that occur in the internal combustion engine 1. That is, when all-cylinder misfires occur in the internal combustion engine 1, the pulsating component spectrum Sp based on either of these two sensor values ​​responds (decreases) relatively quickly. Therefore, with the above-mentioned configuration, the misfire detection device 10A can detect the occurrence of all-cylinder misfires more quickly. Furthermore, in an embodiment in which the above-mentioned sensor values ​​are the same as the operating parameters, the misfire detection device 10 can also detect partial misfires more quickly.

[0043] <Second Example of Details of the Difference Parameter Acquisition Unit 12> 1, 2, and 6B, a second example of details of the difference parameter acquisition unit 12 will be described. Fig. 6B is a diagram conceptually illustrating the relationship between the detection results of the multiple cylinder sensors 18 and the difference parameters according to an embodiment of the present disclosure.

[0044] In the second example, instead of using a single sensor as in the first example, multiple sensors are used. As a specific example, the difference parameter acquisition unit 12 is configured to analyze sensor values ​​detected by each of the multiple cylinder sensors 18 to acquire a difference parameter. The multiple cylinder sensors 18 are configured to detect the operating state of each of the multiple cylinders 2. In the embodiment illustrated in FIG. 1, the cylinder sensor 18 is an exhaust gas temperature sensor 54, and the sensor value is the temperature of the exhaust gas in the cylinder 2. That is, the difference parameter acquisition unit 12 of this example is configured to analyze the temperature of the exhaust gas detected by each of the multiple exhaust gas temperature sensors 54.

[0045] Therefore, the all-cylinder misfire determination unit 41A can determine that an all-cylinder misfire has occurred when the pulsating component spectrum Sp is below the first threshold value and the difference parameter based on the detection results of each of the multiple cylinder sensors 18 is below the second threshold value. Furthermore, the partial misfire determination unit 42A can determine that a partial misfire has occurred when the pulsating component spectrum Sp is below the first threshold value and the difference parameter is equal to or greater than the third threshold value.

[0046] According to the above configuration, the difference parameter acquired based on the detection results of each of the multiple cylinder sensors 18 is strongly correlated with the degree of difference in operation of each of the multiple cylinders 2. Therefore, the difference parameter changes significantly depending on whether all-cylinder misfire or partial misfire occurs. Therefore, the all-cylinder misfire determination unit 41A can detect all-cylinder misfire in the internal combustion engine 1 with high accuracy. Furthermore, the all-cylinder misfire determination unit 41A determines whether all-cylinder misfire has occurred in the internal combustion engine 1 based on the detection results of the cylinder sensor 18, which is the exhaust gas temperature sensor 54. The detection results of the exhaust gas temperature sensor 54 tend to reflect differences in operation of the multiple cylinders 2. Therefore, the misfire determination unit 40A can accurately detect the occurrence of all-cylinder misfire. Furthermore, it can also accurately determine whether the misfire that has occurred is all-cylinder misfire or partial misfire.

[0047] In other embodiments, the multiple cylinder sensors 18 may be configured to detect the exhaust gas pressure or exhaust gas flow rate of the corresponding cylinders 2. Even in this case, the difference parameter acquired based on the detection results of each of the multiple cylinder sensors 18 is strongly correlated with the degree of difference in operation of each of the multiple cylinders 2, making it possible to accurately detect all-cylinder misfire in the internal combustion engine 1. It is also possible to accurately identify whether the misfire that has occurred is an all-cylinder misfire or a partial misfire.

[0048] The numbers shown on the horizontal axis of the graph in Figure 6B correspond to any of the multiple cylinders 2, and N shown on the graph is the same value as the number of cylinders 2. The vertical axis of the graph in the same figure indicates the sensor value, which is the detection result of the cylinder sensor 18.

[0049] The difference parameter acquisition unit 12 according to an embodiment of the present disclosure calculates an average value A of the sensor values ​​of the plurality of cylinder sensors 18. ave The minimum value of multiple sensor values ​​A min The configuration is such that a value obtained by subtracting the above (a value corresponding to the length L) is acquired as the difference parameter. According to the above configuration, the difference parameter indicating the difference in operation of each of the plurality of cylinders 2 can be easily identified.

[0050] <Misfire detection method according to the first embodiment> 7 is a flowchart showing a misfire detection method for an internal combustion engine according to the first embodiment of the present disclosure. This flowchart is executed, for example, by the misfire detection device 10A (see FIG. 2). When this detection method is started, the internal combustion engine 1 is running. In the following description, steps may be abbreviated as "S."

[0051] First, the pulsating component spectrum Sp is acquired by the pulsating component acquisition unit 11 (S11), and then the difference parameter is acquired by the difference parameter acquisition unit 12 (S13). Furthermore, the all-cylinder misfire determination unit 41A determines whether all-cylinder misfire has occurred (S15). If it is determined that all-cylinder misfire has occurred (S15: YES), the detection method ends. At this time, some kind of notification processing may be performed.

[0052] If it is determined that no full misfire has occurred (S15: NO), the partial misfire determination unit 42A determines whether a partial misfire has occurred (S17). If it is determined that a partial misfire has occurred (S17: YES), the detection method ends. On the other hand, if it is determined that a partial misfire has not occurred (S17: NO), the process returns to step S11. S11 to S17 are repeatedly executed while the internal combustion engine 1 operates normally without misfire. In other embodiments, S17 may not be executed, or S17 may be executed before S15 is executed.

[0053] <Detailed Description of the Misfire Detection Device 10B (10) According to the Second Embodiment> 8 is a conceptual diagram showing the configuration of a misfire detection device according to a second embodiment of the present disclosure. In the following description of the misfire detection device 10B according to the second embodiment, the same components as those of the misfire detection device 10A according to the first embodiment are given the same reference numerals in the drawings, and some or all of their description will be omitted. The misfire detection device 10B (10) of this example is configured to detect all-cylinder misfires and partial misfires, but it is not necessary to detect partial misfires.

[0054] The misfire detection device 10B includes a change rate parameter acquisition unit 13 instead of the above-described difference parameter acquisition unit 12 (see FIG. 2). The change rate parameter acquisition unit 13 is configured to acquire a change rate parameter that indicates the degree of change (rate of change) of an operation parameter. The operation parameter is a parameter that correlates with the overall operating status of the multiple cylinders 2. Examples of the operation parameter include engine speed, turbo speed, or inlet exhaust gas pressure of the turbine 24. The operation parameter may be a parameter different from the operation parameter or may be the same parameter as the operation parameter.

[0055] FIG. 9 is a graph showing changes over time in an operating parameter and a change rate parameter according to an embodiment of the present disclosure. The operating parameter illustrated in FIG. 9 is engine speed. In the graph, all-cylinder misfire occurs at timing t=ta. As can be seen from the graph, when all-cylinder misfire occurs, the operating parameter changes significantly (decreases in the example of FIG. 9), and the change rate parameter also changes significantly (decreases in the example of FIG. 9). Therefore, the absolute value of the change rate parameter increases. Although detailed illustration is omitted, when partial misfire occurs, some cylinders 2 operate normally, so the operating parameter and change rate parameter change slightly, but not as significantly as when all-cylinder misfire occurs. Furthermore, when multiple cylinders 2 operate normally, the change in the change rate parameter is even smaller than when partial misfire occurs. These trends in the change rate parameter when partial misfire occurs and when the internal combustion engine 1 is operating normally are similar when the operating parameter is a parameter other than engine speed.

[0056] Therefore, when the pulsating component spectrum Sp falls below the first threshold and the absolute value of the rate of change parameter exceeds a specified threshold (hereinafter referred to as the fourth threshold), it can be determined that all-cylinder misfire has occurred. Also, when the pulsating component spectrum Sp falls below the first threshold and the absolute value of the rate of change parameter is equal to or less than the fifth threshold, it can be determined that partial misfire has occurred. The fifth threshold is a value equal to or less than the fourth threshold, and embodiments in which the fifth threshold and the fourth threshold are the same value are not excluded. Furthermore, when the pulsating component spectrum Sp is equal to or greater than the first threshold, it can be determined that the internal combustion engine 1 is operating normally if the absolute value of the rate of change parameter is equal to or less than the fifth threshold (or equal to or less than a specified value smaller than the fifth threshold).

[0057] FIG. 10 is a matrix showing the relationship between frequency spectrum, change rate parameter, all-cylinder misfire, and partial misfire according to an embodiment of the present disclosure. As described above with reference to FIG. 5, if the pulsating component spectrum Sp acquired by the pulsating component acquisition unit 11 is equal to or greater than the first threshold, it can be determined that all-cylinder misfire or partial misfire is not occurring. If the absolute value of the change rate parameter at this time is equal to or less than the fifth threshold (or equal to or less than a specified value smaller than the fifth threshold), it can be determined that the internal combustion engine 1 is operating normally. On the other hand, if the pulsating component spectrum Sp is below the first threshold, it can be determined that all-cylinder misfire or partial misfire is occurring. In this case, if the absolute value of the change rate parameter acquired by the change rate parameter acquisition unit 13 is greater than the fourth threshold, it can be determined that all-cylinder misfire is occurring. If the absolute value of the change rate parameter is equal to or less than the fifth threshold, it can be determined that partial misfire is occurring.

[0058] Returning to FIG. 8, the misfire determination unit 40B (40), which is a component of the misfire detection device 10B (10), includes an all-cylinder misfire determination unit 41B (41). The all-cylinder misfire determination unit 41B is configured to determine that an all-cylinder misfire has occurred in the internal combustion engine 1 when the pulsation component spectrum Sp acquired by the pulsation component acquisition unit 11 is below a first threshold and the absolute value of the change rate parameter acquired by the change rate parameter acquisition unit 13 is above a fourth threshold. In an embodiment in which the change rate parameter is a negative value, it may be determined whether the change rate parameter is below a value obtained by multiplying the positive fourth threshold by −1. This determination method also makes it possible to determine whether the absolute value of the change rate parameter is above the fourth threshold.

[0059] According to the above configuration, when the pulsating component spectrum Sp is below the first threshold and the absolute value of the rate-of-change parameter is above the fourth threshold, the all-cylinder misfire determination unit 41B determines that an all-cylinder misfire has occurred. Because it is not necessary to determine whether a misfire has occurred for each of the multiple cylinders 2 individually, the misfire detection device 10B can detect the occurrence of an all-cylinder misfire more quickly.

[0060] In other embodiments, the all-cylinder misfire judgment unit 41B may determine that the internal combustion engine 1 is operating normally when the pulsating component spectrum Sp acquired by the pulsating component acquisition unit 11 is equal to or greater than the first threshold value and the absolute value of the change rate parameter acquired by the change rate parameter acquisition unit 13 is equal to or less than the fifth threshold value (or equal to or less than a specified value smaller than the fifth threshold value).

[0061] In one embodiment, the misfire determination unit 40B (40) includes a partial misfire determination unit 42B (42). The partial misfire determination unit 42B is configured to determine the occurrence of partial misfire in the internal combustion engine 1. That is, the partial misfire determination unit 42B is configured to determine that a partial misfire has occurred in the internal combustion engine 1 when the pulsating component spectrum Sp acquired by the pulsating component acquisition unit 11 is below a first threshold value and the absolute value of the rate of change parameter acquired by the rate of change parameter acquisition unit 13 is equal to or smaller than a fifth threshold value.

[0062] According to the above configuration, the misfire detection device 10B is equipped with the partial misfire determination unit 42B and the all-cylinder misfire determination unit 41B, and thus can determine with high accuracy whether a misfire that has occurred in the internal combustion engine 1 is a partial misfire or an all-cylinder misfire.

[0063] In some embodiments, the operating parameter is the same as the operational parameter. That is, the change rate parameter acquisition unit 13 according to an embodiment of the present disclosure is configured to acquire the operating parameter as the operating parameter. With the above configuration, since the operating parameter and the change rate parameter are the same, the configuration for determining whether all-cylinder misfire has occurred can be simplified. For the same reason, the configuration for detecting whether partial misfire has occurred can be simplified.

[0064] The operating parameter according to one embodiment of the present disclosure is the turbine rotation speed or the inlet exhaust gas pressure of the turbine 24. The turbine rotation speed or the inlet exhaust gas pressure of the turbine 24 responds quickly to an all-cylinder misfire occurring in the internal combustion engine 1. According to the above configuration, the misfire detection device 10B for the internal combustion engine 1 can detect the occurrence of an all-cylinder misfire more quickly. Furthermore, in an embodiment in which the above-described operating parameter is the same as the operating parameter, the misfire detection device 10 can also detect a partial misfire more quickly.

[0065] <Misfire detection method according to the second embodiment> 11 is a flowchart showing a misfire detection method for an internal combustion engine according to a second embodiment of the present disclosure. This flowchart is executed by, for example, the misfire detection device 10B (see FIG. 8). When this detection method is started, the internal combustion engine 1 is running.

[0066] First, the pulsating component spectrum Sp is acquired by the pulsating component acquisition unit 11 (S31), and then the change rate parameter is acquired by the change rate parameter acquisition unit 13 (S33). Furthermore, the all-cylinder misfire determination unit 41B determines whether all-cylinder misfire has occurred (S35). If it is determined that all-cylinder misfire has occurred (S35: YES), the detection method ends. At this time, some kind of notification processing may be performed.

[0067] If it is determined that no full misfire has occurred (S35: NO), the partial misfire determination unit 42B determines whether a partial misfire has occurred (S37). If it is determined that a partial misfire has occurred (S37: YES), the detection method ends. On the other hand, if it is determined that a partial misfire has not occurred (S37: NO), the process returns to step S31. S31 to S37 are repeatedly executed while the internal combustion engine 1 operates normally without misfire.

[0068] <Summary> The contents of the above-described embodiments can be understood, for example, as follows.

[0069] 1) A misfire detection device (10) for an internal combustion engine according to at least one embodiment of the present disclosure includes: A misfire detection device (10) for an internal combustion engine (1) for detecting misfire in an internal combustion engine (1) having a plurality of cylinders (2), comprising: a pulsation component acquisition unit (11) for performing frequency analysis on operation parameter data (61) indicating changes over time in operation parameters correlated with the overall operating conditions of the plurality of cylinders (2) and acquiring a pulsation component spectrum (Sp) which is a spectrum at the frequency of pulsation of the internal combustion engine (1); a difference parameter acquisition unit (12) for acquiring a difference parameter correlated with a degree of difference in operation of each of the plurality of cylinders (2); an all-cylinder misfire determination unit (41) for determining that an all-cylinder misfire has occurred in the internal combustion engine (1) when the pulsating component spectrum (Sp) acquired by the pulsating component acquisition unit (11) is below a first threshold value and the difference parameter acquired by the difference parameter acquisition unit (12) is below a second threshold value; Equipped with.

[0070] When a partial misfire or all-cylinder misfire occurs in the internal combustion engine (1), the periodic changes in the operating parameters before the misfire disappear in part or in whole, and the pulsating component spectrum (Sp) decreases. Furthermore, when a partial misfire occurs in the internal combustion engine (1), the difference in operation among the multiple cylinders (2) becomes large. On the other hand, when all-cylinder misfire occurs in the internal combustion engine (1), the difference in operation among the multiple cylinders (2) becomes small, and the difference parameter at this time is small. According to the configuration of 1), the all-cylinder misfire determination unit (41) determines that all-cylinder misfire has occurred when the pulsating component spectrum falls below the first threshold value and the difference parameter falls below the second threshold value. Because it is not determined individually whether misfire has occurred for each of the multiple cylinders (2), the misfire detection device (10) for an internal combustion engine can detect the occurrence of all-cylinder misfire more quickly.

[0071] 2) In some embodiments, the misfire detection device (10) for an internal combustion engine described in 1) above, The internal combustion engine (1) further includes a partial misfire determination unit (42) for determining that a partial misfire has occurred in the internal combustion engine (1) when the pulsating component spectrum (Sp) acquired by the pulsating component acquisition unit (11) is below the first threshold value and the difference parameter acquired by the difference parameter acquisition unit (12) is equal to or greater than a third threshold value that is equal to or greater than the second threshold value.

[0072] According to the configuration 2), the misfire detection device (10) for an internal combustion engine includes the partial misfire determination unit (42) and the all-cylinder misfire determination unit (41), and thus can determine with high accuracy whether a misfire that has occurred in the internal combustion engine (1) is a partial misfire or an all-cylinder misfire.

[0073] 3) In some embodiments, the misfire detection device (10) for an internal combustion engine according to 1) or 2) above, The difference parameter acquisition unit (12) is configured to perform frequency analysis on target data that is a sensor value detected by a single sensor and indicates a change over time in the sensor value that correlates with the degree of the difference, and to acquire, as the difference parameter, a cycle component spectrum (Sc) that is a spectrum at a frequency corresponding to one cycle of the internal combustion engine (1).

[0074] The cycle component spectrum Sc obtained by frequency analysis of the target data correlates with the degree of difference in operation of the plurality of cylinders 2. In other words, when a partial misfire occurs in the internal combustion engine (1), the cycle component spectrum (Sc) is large, and when an all-cylinder misfire occurs in the internal combustion engine (1), the cycle component spectrum (Sc) is small. According to the configuration of 3) above, the all-cylinder misfire determination unit (41) can determine whether an all-cylinder misfire has occurred based on the cycle component spectrum (Sc). Furthermore, because the difference data is obtained based on the sensor value detected by a single sensor, the cycle component spectrum (Sc) as the difference parameter can be detected with a simpler configuration. Therefore, the configuration for detecting the occurrence of an all-cylinder misfire in the internal combustion engine (1) can be simplified.

[0075] 4) In some embodiments, the misfire detection device (10) for an internal combustion engine described in 3) above, The difference parameter acquisition unit (12) is configured to perform a frequency analysis on the motion parameter data (61) as the target data.

[0076] According to the configuration of 4), the sensor value detected by a single sensor is frequency-analyzed to obtain both the pulsation component spectrum (Sp) and the cycle component spectrum (Sc), thereby simplifying the configuration for detecting the occurrence of all-cylinder misfire.

[0077] 5) In some embodiments, the misfire detection device (10) for an internal combustion engine according to 3) or 4) above, The operating parameter is the rotation speed of a turbine (24) rotated by exhaust gas discharged from each of the plurality of cylinders (2), or the exhaust gas pressure at the inlet of the turbine (24).

[0078] The rotation speed of the turbine (24) and the inlet exhaust gas pressure of the turbine (24) respond quickly to an all-cylinder misfire occurring in the internal combustion engine (1). According to the configuration of 5), the misfire detection device (10) for an internal combustion engine can detect the occurrence of an all-cylinder misfire more quickly.

[0079] 6) In some embodiments, the misfire detection device (10) for an internal combustion engine according to 1) or 2) above, The difference parameter acquisition unit (12) is configured to analyze sensor values ​​detected by each of a plurality of cylinder sensors (18) for detecting the operating state of each of the plurality of cylinders (2), and acquire the difference parameters.

[0080] According to the configuration 6), the difference parameter acquired based on each of the plurality of cylinder sensors 18 is strongly correlated with the degree of difference in operation of each of the plurality of cylinders 2. Therefore, the all-cylinder misfire determination unit 41 can detect all-cylinder misfire in the internal combustion engine 1 with high accuracy.

[0081] 7) In some embodiments, the misfire detection device (10) for an internal combustion engine described in 6) above, The difference parameter acquisition unit (12) is configured to analyze the temperature of the exhaust gas sensed by each of the plurality of cylinder sensors (18).

[0082] According to the above configuration 7), the all-cylinder misfire determining section (41) can determine whether all-cylinder misfire has occurred in the internal combustion engine (1) based on the detection result of the cylinder sensor (18) functioning as an exhaust temperature sensor.

[0083] 8) In some embodiments, the misfire detection device (10) for an internal combustion engine according to 6) or 7) above, The difference parameter acquisition unit (12) is configured to acquire, as the difference parameter, a value obtained by subtracting the minimum value of the plurality of sensor values ​​from the average value of the plurality of sensor values.

[0084] According to the above configuration 8), the difference parameter indicating the difference in operation of each of the plurality of cylinders (2) can be easily identified.

[0085] 9) At least one embodiment of the misfire detection device (10) for an internal combustion engine according to the present disclosure includes: A misfire detection device (10) for an internal combustion engine (1) for detecting misfire in an internal combustion engine (1) having a plurality of cylinders (2), comprising: a pulsation component acquisition unit (11) for performing frequency analysis on operation parameter data (61) indicating changes over time in operation parameters correlated with the overall operating conditions of the plurality of cylinders (2) and acquiring a pulsation component spectrum (Sp) which is a spectrum at the frequency of pulsation of the internal combustion engine (1); a change rate parameter acquisition unit (13) for acquiring a change rate parameter indicating a degree of change in an operating parameter correlated with an overall operating condition of the plurality of cylinders (2); and an all-cylinder misfire determination unit (41) for determining that an all-cylinder misfire has occurred in the internal combustion engine (1) when the pulsating component spectrum (Sp) acquired by the pulsating component acquisition unit (11) is below a first threshold value and the absolute value of the change rate parameter acquired by the change rate parameter acquisition unit (13) is above a fourth threshold value.

[0086] When partial or all-cylinder misfire occurs in the internal combustion engine (1), the periodic changes in the operating parameters before the misfire disappear in part or in whole, and the pulsating component spectrum (Sp) decreases. Furthermore, when partial misfire occurs in the internal combustion engine (1), some of the cylinders 2 operate normally, and the rate-of-change parameter of the operating parameters is small. On the other hand, when all-cylinder misfire occurs in the internal combustion engine (1), none of the cylinders 2 operate normally, and the absolute value of the rate-of-change parameter is large. According to the configuration of 9) above, when the pulsating component spectrum falls below the first threshold and the absolute value of the rate-of-change parameter exceeds the fourth threshold, the all-cylinder misfire determination unit (41) determines that all-cylinder misfire has occurred. Because it is not determined individually whether misfire has occurred for each of the multiple cylinders (2), the misfire detection device (10) for an internal combustion engine can detect the occurrence of all-cylinder misfire more quickly.

[0087] 10) In some embodiments, the misfire detection device (10) for an internal combustion engine described in 9) above, The internal combustion engine (1) further includes a partial misfire determination unit (42) for determining that a partial misfire has occurred in the internal combustion engine (1) when the pulsating component spectrum (Sp) acquired by the pulsating component acquisition unit (11) is below the first threshold value and the absolute value of the change rate parameter acquired by the change rate parameter acquisition unit (13) is equal to or less than a fifth threshold value that is equal to or less than the fourth threshold value.

[0088] According to the configuration of 10), the misfire detection device (10) for an internal combustion engine includes the partial misfire determination unit (42) and the all-cylinder misfire determination unit (41), and thus can determine with high accuracy whether a misfire that has occurred in the internal combustion engine (1) is a partial misfire or an all-cylinder misfire.

[0089] 11) In some embodiments, the misfire detection device (10) for an internal combustion engine according to 9) or 10) above, The change rate parameter acquisition unit (13) is configured to acquire the operation parameter as the operating parameter.

[0090] According to the configuration of 11) above, the operating parameters and the operational parameters are the same, so that the configuration for determining whether all cylinders have misfired can be made simpler.

[0091] 12) In some embodiments, the misfire detection device (10) for an internal combustion engine according to any one of 9) to 11) above, The operating parameter is the rotation speed of a turbine (24) rotated by exhaust gas discharged from each of the plurality of cylinders (2), or the exhaust gas pressure at the inlet of the turbine (24).

[0092] The rotation speed of the turbine (24) and the inlet exhaust gas pressure of the turbine (24) respond quickly to an all-cylinder misfire occurring in the internal combustion engine (1). According to the configuration of 12), the misfire detection device (10) for an internal combustion engine can detect the occurrence of an all-cylinder misfire more quickly.

[0093] 13) A misfire detection method for an internal combustion engine (1) according to at least one embodiment of the present disclosure, A misfire detection method for an internal combustion engine (1) for detecting misfire in an internal combustion engine (1) having a plurality of cylinders (2), comprising: a pulsation component acquisition step (S11) for performing frequency analysis on operation parameter data (61) indicating changes over time in operation parameters correlated with the overall operating conditions of the plurality of cylinders (2) to acquire a pulsation component spectrum (Sp) which is a spectrum at the frequency of pulsation of the internal combustion engine (1); a difference parameter acquisition step (S13) for acquiring a difference parameter correlated with a degree of difference in operation of each of the plurality of cylinders (2); and an all-cylinder misfire determination step (15) for determining that an all-cylinder misfire has occurred in the internal combustion engine (1) when the pulsating component spectrum (Sp) acquired by the pulsating component acquisition step is below a first threshold value and the difference parameter acquired by the difference parameter acquisition step is below a second threshold value.

[0094] According to the configuration of 13) above, for the same reason as in 1), a detection method for an internal combustion engine (1) that can detect the occurrence of an all-cylinder misfire more quickly is realized.

[0095] 14) A misfire detection method for an internal combustion engine (1) according to at least one embodiment of the present disclosure, A misfire detection method for an internal combustion engine (1) for detecting misfire in an internal combustion engine (1) having a plurality of cylinders (2), comprising: a pulsation component acquisition step (S31) for performing frequency analysis on operation parameter data (61) indicating changes over time in operation parameters correlated with the overall operating conditions of the plurality of cylinders (2) to acquire a pulsation component spectrum (Sp) which is a spectrum at the frequency of pulsation of the internal combustion engine (1); a change rate parameter acquisition step (S33) for acquiring a change rate parameter indicating a degree of change in an operating parameter correlated with an overall operating condition of the plurality of cylinders (2); and an all-cylinder misfire determination step (S35) for determining that an all-cylinder misfire has occurred in the internal combustion engine (1) when the pulsating component spectrum (Sp) acquired by the pulsating component acquisition step is below a first threshold value and the absolute value of the change rate parameter acquired by the change rate parameter acquisition step is above a fourth threshold value.

[0096] According to the configuration of 14) above, for the same reason as 9) above, a detection method for an internal combustion engine (1) that can detect the occurrence of all-cylinder misfires earlier is realized. [Explanation of symbols]

[0097] 1: Internal combustion engine 2: Cylinder 10: Misfire detection device 10A: Misfire detection device 10B: Misfire detection device 11: Pulsation component acquisition section 12: Differential parameter acquisition section 13: Change rate parameter acquisition section 18: Cylinder sensor 24: Turbine 40: Misfire determination section 41: All-cylinder misfire determination section 42: Partial misfire determination section 61: Operation parameter data Aave: average value Amin: minimum value Sc: Cycle component spectrum Sp: Pulsation component spectrum

Claims

1. A misfire detection device for an internal combustion engine for detecting misfire in an internal combustion engine having a plurality of cylinders, a pulsation component acquisition unit for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a difference parameter acquisition unit for acquiring a difference parameter correlated with a degree of difference between the operations of each of the plurality of cylinders; an all-cylinder misfire determination unit for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired by the pulsating component acquisition unit is below a first threshold value and the difference parameter acquired by the difference parameter acquisition unit is below a second threshold value; A misfire detection device for an internal combustion engine.

2. a partial misfire determination unit for determining that a partial misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired by the pulsating component acquisition unit is below the first threshold value and the difference parameter acquired by the difference parameter acquisition unit is equal to or greater than a third threshold value that is equal to or greater than the second threshold value, 2. The misfire detection device for an internal combustion engine according to claim 1.

3. the difference parameter acquisition unit is configured to perform frequency analysis on target data that is a sensor value detected by a single sensor and indicates a change over time in the sensor value that correlates with the degree of the difference, and to acquire, as the difference parameter, a cycle component spectrum that is a spectrum at a frequency corresponding to one cycle of the internal combustion engine.

3. The misfire detection device for an internal combustion engine according to claim 1 or 2.

4. the difference parameter acquisition unit is configured to perform frequency analysis on the operation parameter data as the target data; 4. The misfire detection device for an internal combustion engine according to claim 3.

5. the operating parameter is a rotation speed of a turbine rotated by exhaust gas discharged from each of the plurality of cylinders, or an exhaust gas pressure at an inlet of the turbine; 5. The misfire detection device for an internal combustion engine according to claim 3 or 4.

6. the difference parameter acquisition unit is configured to analyze sensor values ​​detected by each of a plurality of cylinder sensors for detecting parameters related to the operating states of each of the plurality of cylinders, and acquire the difference parameters.

3. The misfire detection device for an internal combustion engine according to claim 1 or 2.

7. The sensor value is the temperature of the exhaust gas of the cylinder, the difference parameter acquisition unit is configured to analyze the temperature of the exhaust gas detected by each of the plurality of cylinder sensors; 7. The misfire detection device for an internal combustion engine according to claim 6.

8. the difference parameter acquisition unit is configured to acquire, as the difference parameter, a value obtained by subtracting a minimum value of the plurality of sensor values ​​from an average value of the sensor values ​​for the plurality of cylinders.

8. The misfire detection device for an internal combustion engine according to claim 6 or 7.

9. A misfire detection device for an internal combustion engine for detecting misfire in an internal combustion engine having a plurality of cylinders, a pulsation component acquisition unit for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a change rate parameter acquisition unit for acquiring a change rate parameter indicating a degree of change in an operating parameter correlated with an overall operating status of the plurality of cylinders; an all-cylinder misfire determination unit for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired by the pulsating component acquisition unit is below a first threshold value and the absolute value of the change rate parameter acquired by the change rate parameter acquisition unit is above a fourth threshold value; A misfire detection device for an internal combustion engine.

10. a partial misfire determination unit that determines that a partial misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired by the pulsating component acquisition unit is below the first threshold and the absolute value of the rate of change parameter acquired by the rate of change parameter acquisition unit is equal to or less than a fifth threshold that is equal to or less than the fourth threshold, 10. The misfire detection device for an internal combustion engine according to claim 9.

11. the change rate parameter acquisition unit is configured to acquire the operation parameter as the operating parameter; 11. The misfire detection device for an internal combustion engine according to claim 9 or 10.

12. the operating parameter is a rotation speed of a turbine rotated by exhaust gas discharged from each of the plurality of cylinders, or an exhaust gas pressure at an inlet of the turbine; The misfire detection device for an internal combustion engine according to any one of claims 9 to 11.

13. A misfire detection method for an internal combustion engine having a plurality of cylinders, comprising: a pulsation component acquisition step for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a difference parameter acquisition step for acquiring a difference parameter correlated with a degree of difference in operation of each of the plurality of cylinders; an all-cylinder misfire determination step for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired in the pulsating component acquisition step is below a first threshold value and the difference parameter acquired in the difference parameter acquisition step is below a second threshold value; A misfire detection method for an internal combustion engine comprising:

14. A misfire detection method for an internal combustion engine having a plurality of cylinders, comprising: a pulsation component acquisition step for performing frequency analysis on operational parameter data indicating changes over time in operational parameters correlated with the overall operational status of the plurality of cylinders, and acquiring a pulsation component spectrum, which is a spectrum at the frequency of pulsation of the internal combustion engine; a change rate parameter acquisition step for acquiring a change rate parameter indicating a degree of change in an operating parameter correlated with an overall operating status of the plurality of cylinders; an all-cylinder misfire determination step for determining that an all-cylinder misfire has occurred in the internal combustion engine when the pulsating component spectrum acquired in the pulsating component acquisition step is below a first threshold value and the absolute value of the change rate parameter acquired in the change rate parameter acquisition step is above a fourth threshold value; A misfire detection method for an internal combustion engine comprising:

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