JP6881131B2 - Internal combustion engine misfire judgment device - Google Patents

Description

The present invention relates to an internal combustion engine misfire determination device that determines misfires that occur in each cylinder of an internal combustion engine.

Patent Document 1 discloses a device for determining misfire using the engine speed excluding the resonance component based on the twist of the damper interposed between the internal combustion engine and the transmission.

However, in the misfire determination device for an internal combustion engine described in Patent Document 1, since the resonance component is calculated using the rotation speed of the member located on the downstream side of the damper, the peripheral members and disturbances thereof are affected. It is easily affected and the accuracy of misfire judgment may vary.

Japanese Unexamined Patent Publication No. 2009-144561

Therefore, an object of the present invention is to provide an internal combustion engine misfire determination device capable of performing highly accurate misfire determination by realizing a misfire determination process that is not affected by resonance.

One aspect of the invention of the misfire determination device for an internal combustion engine that solves the above problems is to reduce misfire in the combustion chamber of an internal combustion engine in which an input shaft having a resonance frequency of a transmission is connected to a crankshaft to change the rotation of the crankshaft. It is a misfire judgment device that judges based on
The process of acquiring the rotation information Ne of the crank shaft and the rotation information Nt of the input shaft, and calculating the rotation change amount ΔNe of the crank shaft and passing it through a digital filter to remove the primary frequency component to achieve the secondary or higher order. The process of acquiring the rotation fluctuation of the crank shaft including the frequency component and the amplitude of the first-order frequency component that is not affected by the resonance frequency separated and extracted by passing the rotation change amount ΔNe of the crank shaft through a digital filter are second-order or higher. The process of calculating and specifying from the amplitude of the frequency component of the above, and the rotation information Ne of the crank shaft and the rotation information Nt of the input shaft are processed by the physical model of the control function to remove the resonance frequency component, and then passed through a digital filter. By doing so, the process of specifying the phase of the primary frequency component and the primary frequency component that does not include the resonance frequency component are shaped from the amplitude and phase of the primary frequency component specified by the process to form the primary frequency of the crank shaft. The process of restoring the components and the primary frequency component shaped by the process are combined with the second and higher frequency components acquired by the process to acquire the rotational characteristics of the crankshaft that are not affected by the resonance frequency. Equipped with an estimation unit that performs processing and
As a physical model of the control function, a function process using the following equation that expresses the combustion torque Te of the internal combustion engine having the same behavior as the rotational change amount ΔNe of the crankshaft by the moment of inertia Ie of the internal combustion engine and the angular velocity ω. Extracts the primary frequency component of the crankshaft by
Te = Ie · dω
The frequency component of the rotational operation of the crankshaft according to the pattern of misfire generated in the combustion chamber of the internal combustion engine is acquired to determine the misfire of the internal combustion engine.

As described above, according to one aspect of the present invention, the secondary frequency component and the tertiary frequency component that are not affected by resonance are extracted from the rotational fluctuation of the crankshaft of the internal combustion engine, the primary frequency component is estimated, and the misfire is determined. Therefore, it is possible to accurately determine the misfire of the internal combustion engine without being affected by the resonance frequency component included in the rotational fluctuation.

Therefore, it is possible to provide a misfire determination device for an internal combustion engine capable of performing misfire determination processing without being affected by resonance and capable of highly accurate misfire determination.

FIG. 1 is a diagram showing an example of a vehicle equipped with an internal combustion engine misfire determination device according to an embodiment of the present invention, and is a conceptual diagram showing a configuration of a main part thereof. FIG. 2 is a diagram showing the frequency components included in the rotational fluctuation of the crank shaft, (a) is an amplitude waveform diagram of the frequency components excluding the influence of the resonance of the damper, and (b) is the influence of the resonance of the damper. It is an amplitude waveform diagram of the frequency component including. FIG. 3 is a block diagram illustrating a process of acquiring the rotational characteristics of the crankshaft, which is not affected by the resonance of the damper. FIG. 4 is a processing flow diagram illustrating each process performed in the acquisition process shown in FIG. FIG. 5 is a block diagram illustrating an individual function for executing each process performed in the acquisition process shown in FIG. FIG. 6 is a control function block diagram illustrating data processing in the model calculation of FIGS. 3 to 5. FIG. 7 is a graph for explaining the appearance pattern of the amplitude intensity of the frequency component at the time of misfire, where (a) is a single misfire pattern, (b) is a double misfire pattern, (c) is an inter-missing fire pattern, and (d). ) Indicates an oncoming misfire pattern. FIG. 8 is a flowchart illustrating a process of setting an amplitude correction coefficient according to the misfire pattern shown in FIG. 7. 9A and 9B are diagrams for explaining another mode of the amplitude correction coefficient setting process according to the misfire pattern shown in FIG. 7, where FIG. 9A is a map used at the time of facing misfire, and FIG. 9B is used at the time of two consecutive misfires. It is a map to do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 8 are views showing an example of a vehicle equipped with a misfire determination device for an internal combustion engine according to an embodiment of the present invention.

In FIG. 1, in the vehicle 100, an internal combustion engine type engine 101 and a transmission 111 are connected by a damper 121 having a lockup function. The vehicle 100 travels by rotating drive wheels (not shown) by transmitting the rotational power output from the engine 101 to the transmission 111 via the damper 121 to shift gears. The vehicle 100 is efficiently and comfortably driven by executing a control program stored in the memory 11 by the ECU (Electronic Control Unit) 10 to collectively control the entire engine 101, transmission 111, damper 121, and the like. It is supposed to be done.

The internal combustion engine type engine 101 repeats four cycles of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke in a combustion chamber 103 formed in a cylinder 102, and injects fuel and intake air in the combustion chamber 103. By burning and exploding the air-fuel mixture, the piston 104 in the cylinder 102 is moved up and down to rotate the crankshaft 105, thereby outputting power (torque). With this structure, the rotational power of the engine 101 is output while slightly fluctuating because the vertical movement of the piston 104 for each cylinder 102 is switched to rotation by the crankshaft 105. Therefore, if a misfire occurs in the combustion in the combustion chamber 103 for some reason, the rotational power is lost and the rotational fluctuation becomes large.

The damper 121 inputs a plurality of arcuate springs 122 arranged in series around the axis between the crankshaft 105, which is the output shaft of the engine 101, and the input shaft 115 of the transmission 111, respectively. By connecting the member 121i and the output side member 121io so as to be sandwiched between them, the rotational power of the engine 101 is transmitted to the transmission 111 via the spring 122. With this structure, the fluctuation generated in the rotational power of the engine 101 is transmitted and output to the transmission 111 while being absorbed by the elastic force of the spring 122 of the damper 121. Therefore, when the transmitted rotational power fluctuates greatly, the spring 122 also expands and contracts greatly and vibrates. The damper 121 is provided with a lockup mechanism 125 that directly fastens the input side member 121i and the output side member 121o, and a spring 122 is provided between the crankshaft 105 of the engine 101 and the input shaft 115 of the transmission 111. It has a structure that connects non-rotatably without intervening elastic force.

Since the damper 121 is composed of a spring 122 that expands and contracts and vibrates, it has a unique resonance vibration frequency according to the structure. Therefore, the damper 121 may resonate and vibrate due to a large fluctuation in the transmitted rotational power due to a misfire occurring in any of the combustion chambers 103 of the engine 101 for some reason.

From this, the ECU 10 acquires the input / output rotation characteristics of the damper 121 from the detection information by connecting the output rotation sensor 21 and the input rotation sensor 22 so as to be able to receive the detection information. The output rotation sensor 21 detects the rotation speed of the crankshaft 105 of the engine 101 located on the upstream side of the damper 121. The input rotation sensor 22 detects the rotation speed of the input shaft 115 of the transmission 111 located on the downstream side of the damper 121. The output rotation sensor 21 and the input rotation sensor 22 detect the rotation positions of the outer peripheral surfaces of the large-diameter disk members 21p and 22p that rotate integrally with the crankshaft 105 and the input shaft 115, respectively. It is assembled so that the rotation speed can be detected with high accuracy.

Then, in parallel with executing the control program in the memory 11 to execute the control process for efficiently and constantly driving the engine 101 and the transmission 111, the ECU 10 is generated in the combustion chamber 103 of each cylinder 102 of the engine 101. A processing procedure for determining a misfire to be performed based on the detection information of the output rotation sensor 21 and the input rotation sensor 22 is executed. The ECU 10 is adapted to suppress deterioration of the drive quality of the engine 101 by performing an adjustment process for recovering the combustion control in the combustion chamber 103 identified as the occurrence of the misfire.

By the way, the crankshaft 105 of the engine 101 rotates with rotational characteristics including waveforms of high-order frequency components of primary, secondary, and higher order, and the output rotational sensor 21 detects the rotational characteristics. There is. The crankshaft 105 has a primary frequency component in a phase corresponding to four cycles of each cylinder 102, for example, as shown in FIG. 2A, due to the vertical movement of the piston 104 for each cylinder 102 of the engine 101. It is rotating with rotational characteristics including the amplitude intensity of the secondary frequency component and the tertiary frequency component.

At this time, if a misfire occurs in any of the combustion chambers 103 of each cylinder 102 of the engine 101, the rotation of the crankshaft 105 is a rotation characteristic in which the rotational power (load) is removed in the rotation phase of the corresponding portion of the cylinder 102. It becomes. The ECU 10 performs an adjustment process of identifying and recovering the rotation phase of the corresponding cylinder 102 in which a misfire has occurred in the combustion chamber 103 based on the detection information of the output rotation sensor 21 that detects the rotation of the crankshaft 105, thereby performing the adjustment process of the engine 101. Suppress the deterioration of drive quality.

Further, when the spring 122 of the damper 121 has a resonance vibration that expands and contracts at a specific resonance frequency, the crank shaft 105 has, for example, a secondary frequency component or a tertiary frequency component, as shown in FIG. 2 (b). Although it does not affect the amplitude intensity, it rotates with the rotational characteristics that fluctuate as the amplitude intensity of the primary frequency component is increased. From this, it is possible to specify the rotation phase of the crankshaft 105 corresponding to the cylinder 102 of the combustion chamber 103 in which misfire occurs, based on the detection information of the output rotation sensor 21 received by the ECU 10 at the timing of resonance vibration of the damper 121. It is difficult, and it is not possible to properly execute the recovery adjustment process that suppresses the deterioration of the drive quality of the engine 101.

Therefore, the ECU 10 of the present embodiment estimates the primary frequency component in the rotation fluctuation of the crankshaft 105 of the engine 101 based on the secondary frequency component and the tertiary frequency component extracted from the detection information of the output rotation sensor 21. Therefore, the rotational characteristics of the crankshaft 105, which is not affected by the resonance vibration (resonance frequency), are acquired, and the cylinder 102 of the combustion chamber 103 in which the misfire occurs is specified so that the misfire determination is performed. That, ECU 10 constitute the misfire identification device comprising estimation tough. Here, the rotational characteristics of the crank shaft 105 are represented by the amplitude an for each frequency component. For example, the amplitude a1 of the primary frequency component, the amplitude a2 of the secondary frequency component, and the amplitude a3 of the tertiary frequency component are used. It can be used as a function F (a1, a2, a3) for misfire determination processing and the like.

As shown in FIG. 3, the ECU 10 uses the rotational characteristics of the crankshaft 105, which is not affected by the resonance frequency of the damper 121, as information capable of determining misfire that occurs in the engine 101 by executing various processes Pc1 to Pc7. get. In the acquisition process Pc1, the rotation information Ne of the crankshaft 105 of the engine 101 is acquired from the detection information of the output rotation sensor 21. In the acquisition process Pc2, the rotation information Nt of the input shaft 115 of the transmission 111 is acquired from the detection information of the input rotation sensor 22. In the filter (extraction) process Pc3, a second-order or higher frequency component that is not affected by the resonance frequency is extracted from the rotation information Ne of the crankshaft 105 acquired in the acquisition process Pc1. In the amplitude estimation process Pc4, the second-order frequency component and the third-order frequency component that are not affected by the resonance frequency are acquired (extracted) from the rotation information Ne of the crankshaft 105 acquired in the acquisition process Pc1 and the amplitude of the first-order frequency component is obtained. presume. In the model calculation process Pc5, the primary frequency component excluding the influence of the resonance frequency from the rotation information Ne of the crankshaft 105 acquired in the acquisition process Pc1 and the rotation information Nt of the input shaft 115 of the transmission 111 acquired in the acquisition process Pc2. Get the phase of. In the restoration process Pc6, the primary frequency component that does not include the resonance frequency component is shaped (restored) from the amplitude and phase of the primary frequency component acquired by the amplitude estimation process Pc4 and the model calculation process Pc5. In the synthesis process Pc7, the secondary and higher frequency components extracted by the extraction process Pc3 and the primary frequency component acquired by the restoration process Pc6 are combined, and the crankshaft 105 is not affected by the resonance frequency of the damper 121. Output the rotation characteristics.

Specifically, as shown in FIG. 4, the ECU 10 has a rotation information (detection information of the output rotation sensor 21) Ne of the crankshaft 105 of the engine 101 and a rotation information (input rotation sensor) of the input shaft 115 of the transmission 111. 22 detection information) Resonance of the damper 121 by performing the first processing procedure Pr1, the second processing procedure Pr2, and the third processing procedure Pr3 in parallel using Nt to extract and synthesize the signal waveform. Acquires the rotational characteristics of the crankshaft 105 that does not contain a frequency component. As a result, the ECU 10 can reliably determine the misfire in the combustion chamber 103 while specifying the cylinder 102 of the engine 101 by using the rotational characteristics of the crankshaft 105.

In the first processing procedure Pr1 executed by the ECU 10, the rotation change amount ΔNe per unit time is calculated from the rotation information Ne of the crankshaft 105 of the engine 101 detected by the output rotation sensor 21, and the rotation change amount ΔNe is passed through the digital filter DF1. , Acquires the rotational fluctuation of the crankshaft 105 including the secondary and higher frequency components excluding the primary frequency component together with the noise.

Further, in the second processing procedure Pr2 executed by the ECU 10, the calculated amplitude change amount ΔNe of the crankshaft 105 is passed through the digital filter DF2 to specify the amplitude of the primary frequency component while removing noise.

On the other hand, in the third processing procedure Pr3 executed by the ECU 10, the rotation information Ne of the crankshaft 105 of the engine 101 detected by the output rotation sensor 21 and the rotation of the input shaft 115 of the transmission 111 detected by the input rotation sensor 22. By using the information Nt as it is and processing it in a control function, a so-called physical model Pm, which will be described later, the resonance frequency component included in the rotation information Ne of the crankshaft 105 is removed, and the noise is passed by passing through the digital filter DF3. The phase of the primary frequency component is specified while removing the above. Here, since the physical model Pm performs a process of removing the resonance frequency component included in the rotation information Ne of the crankshaft 105, the misfire determination of the engine 101 is determined as the rotation variation of the crankshaft 105 which is not affected by the resonance vibration only by this process. It is also possible to do. However, due to the problem of the detection characteristic (accuracy) of the output rotation sensor 21, in the present embodiment, the processing result by the physical model Pm is passed through the digital filter DF3 to extract the phase of the primary frequency component and use it.

After that, the ECU 10 applies the amplitude of the primary frequency component specified in the second processing procedure Pr2 to the phase of the primary frequency component specified in the third processing procedure Pr3 to perform waveform shaping (synthesis) processing Fm. By restoring the primary frequency component that does not contain the resonance frequency component in the rotation fluctuation of the crank shaft 105, and further performing the synthetic processing Cp on the secondary or higher frequency component extracted in the first processing procedure Pr1, the crank shaft 105 Estimate and obtain the rotational fluctuation that is not affected by the resonance of.

Specifically, as shown in FIG. 5, when the processing procedure shown in FIG. 4 is applied to the arithmetic processing shown in FIG. 3, the ECU 10 shifts the speed from the output rotation sensor 21 and the input rotation sensor 22 to the rotation information Ne of the crankshaft 105. While acquiring the rotation information Nt of the input shaft 115 of the machine 111 in parallel, the rotation change amount ΔNe per unit time is calculated and acquired from the rotation information Ne of the crankshaft 105 (acquisition processes Pc1 and Pc2).

After this, the ECU 10 passes the rotational change amount ΔNe of the crankshaft 105 through the digital filter DF1 to acquire the rotational fluctuation of the crankshaft 105 including the secondary and higher frequency components excluding the primary frequency component together with noise ( Extraction process Pc3, first process procedure Pr1).

On the other hand, the ECU 10 passes the rotational change amount ΔNe of the crankshaft 105 through the digital filter DF2 to specify the amplitude of the included primary frequency component while removing noise (estimation process Pc4). At this time, in the digital filter DF2, the primary frequency component is separated and extracted based on the rotational change amount ΔNe of the crank shaft 105, the secondary frequency component is separated and extracted, and the tertiary frequency component is separated and extracted. The amplitude of the frequency component is calculated and estimated from the amplitudes of the secondary frequency component and the tertiary frequency component (estimation processing Pc4, second processing procedure Pr2).

Further, the ECU 10 processes the rotation information Ne of the crankshaft 105 and the rotation information Nt of the input shaft 115 of the transmission 111 by a control function, a so-called physical model Pm, which will be described later, to remove the resonance frequency component, and then performs a digital filter. Through DF3, the phase of the included primary frequency component is specified while removing noise (model calculation process Pc5, third processing procedure Pr3).

After that, the ECU 10 shapes the waveform with the specified amplitude and phase to restore the primary frequency component in the rotational fluctuation of the crank shaft 105 that does not include the resonance frequency (restoration process Pc6, synthesis process Fm), and further. By synthesizing with the second or higher frequency components extracted from the rotation fluctuation of the crank shaft 105 (synthesis processing Pc7, Cp), the rotation fluctuation of the theoretical waveform of the crank shaft 105 not including the influence of the resonance frequency of the damper 121 is estimated. To get.

The ECU 10 functioning as the physical model Pm executes a function process for extracting the primary frequency component to be processed by the digital filter DF3 by estimating the torque generated by the combustion in the engine 101. At this time, the combustion torque Te can be expressed by the following equation, and since the combustion torque Te and the rotational change amount ΔNe of the crankshaft 105 have substantially the same behavior, the crank is made by utilizing the moment of inertia Ie of the engine 101. The primary frequency component of the rotational change amount ΔNe of the shaft 105 can be extracted.
Te = Ie · dω Ie: Moment of inertia of engine ω: Angular velocity

In this physical model, as shown in FIG. 6, first, the angular velocity ωe is derived from the rotation information Ne of the crankshaft 105 of the engine 101, and the angular velocity ωimp is derived from the rotation information Nt of the input shaft 115 of the transmission 111. By synthesizing (“+” and “−”), the vibration angular velocity ωdmp due to the input / output difference of the damper 121 is acquired and the reciprocal (1 / s) is taken to calculate the twist angle θdmp of the damper 121. The torsion angle θdmp of the damper 121 is calculated by transforming the above equation (1) into a functional expression that divides the constant Kdmp of the damper 121 by the moment of inertia Ie of the engine 101, and then takes the reciprocal (1 / s). Acquires the angular velocity ωe_dmp due to the influence of the damper 121. By synthesizing (“−” and “+”) the angular velocity ωe_dmp of the influence of the damper 121 and the angular velocity ωe of the crankshaft 105 including the resonance frequency component of the damper 121, the angular velocity of the crankshaft 105 excluding the resonance frequency component is removed. ωe_Te can be obtained.

By the way, the engine 101 may cause a misfire in each of the combustion chambers 103 for each cylinder 102, and as shown in FIG. 7, the frequency characteristic included in the rotation fluctuation of the crankshaft 105 according to the pattern of the misfire occurrence. Makes a difference. For example, as shown in FIG. 7A, in the case of so-called single-cylinder misfire in which misfire occurs continuously in any one of the cylinders 102, the primary frequency component and the secondary frequency component, It becomes the rotation information Ne in which all the amplitude intensities of the third frequency components exist. As shown in FIG. 7B, in the case of a so-called double misfire in which two consecutive cylinders of the cylinders 102 are misfired, the amplitude intensity of the primary frequency component is larger than that of the secondary frequency component. The rotation information Ne does not include the amplitude intensity of the tertiary frequency component (for example, about twice). As shown in FIG. 7 (c), in the case of a so-called inter-cylinder misfire in which misfire occurs every other cylinder of the cylinder 102, the primary frequency component, 2 The rotation information Ne is such that the amplitude intensities of any of the next frequency component and the third frequency component are present. As shown in FIG. 7D, in the case of a so-called facing misfire in which a misfire occurs in the cylinders at the opposite layout positions of the cylinders 102, only the amplitude intensity of the secondary frequency component is used to obtain the primary frequency component. And the rotation information Ne that does not include the third frequency component. Here, FIG. 7 shows an misfire pattern in the case of 6 cylinders or 8 cylinders as an example.

Therefore, when the ECU 10 (digital filter DF2) executes the estimation process Pc4 (second processing procedure Pr2) for calculating the amplitude intensity of the primary frequency component described above, the secondary frequency component in the rotational characteristics of the crankshaft 105 And by using the amplitude of the third-order frequency component, the misfire pattern that has occurred is discriminated, the correction coefficient is determined, and the amplitude of the first-order frequency component is calculated and estimated.

Specifically, the ECU 10 determines whether it is an opposed misfire pattern, a double continuous misfire pattern, or other rotational characteristics according to the processing procedure shown in the flowchart of FIG. 8, determines the correction coefficient, and determines the correction coefficient. The amplitude of each frequency component in the rotation characteristic F (a1, a2 , a3) of the above is acquired.

First, as shown in the flowchart of FIG. 8, the ECU 10 calculates the discrimination ratio popp from the following opposed misfire discriminant using the amplitude of each frequency component of the acquired rotation change amount ΔNe of the crankshaft 105 (step S11). ), It is confirmed whether or not the ratio popp is less than a predetermined discriminant threshold value (step S12).
popp = [max (amplitude of primary or tertiary frequency component)] / amplitude of secondary frequency component max (x1, x2, x3, ...): Select the maximum value in parentheses Discrimination threshold: amplitude A value that definitely exceeds the ratio popp in the case of frequency components with no intensity

In this step S12, as shown in FIG. 7D, in the case of the opposite misfire pattern, neither the amplitude of the primary frequency component nor the amplitude of the tertiary frequency component is recognized, and a value of about the background is acquired. Therefore, it is confirmed that the discrimination ratio popp is about a minute error value and is less than the discrimination threshold.

Therefore, in step S12, the ECU 10 confirms that the oncoming misfire occurs in the engine 101 and the discrimination ratio popp is less than the discrimination threshold value, and sets the amplitude correction coefficient kopp = "0" in the memory 11 (step S13). ).

Further, in step S12, the ECU 10 confirms that no oncoming misfire has occurred in the engine 101 and the discrimination ratio popp is equal to or higher than the discrimination threshold value, and sets the amplitude correction coefficient kopp = "1" in the memory 11 (step). S14).

Next, the ECU 10 calculates the discrimination ratio pdbl from the following two-cylinder continuous misfire discriminant using the amplitude of each frequency component of the acquired rotation change amount ΔNe of the crankshaft 105 (step S15), and the ratio pdbl is predetermined. It is confirmed whether or not it is less than the discriminant threshold value of (step S16).
pdbl = Amplitude of 3rd frequency component / Amplitude of 2nd frequency component

In this step S16, as shown in FIG. 7B, in the case of the double misfire pattern, the amplitude of the tertiary frequency component is not recognized and a value of about the background is acquired, and the ratio pdbl for discrimination is obtained. Is about a minute error value, and it is confirmed that is less than the discrimination threshold.

Therefore, in step S16, the ECU 10 confirms that the discriminant ratio pdbl is less than the discriminant threshold due to the occurrence of two consecutive misfires in the engine 101, and sets the amplitude correction coefficient kdbl = "KDBL-H", for example, "2". It is set in the memory 11 (step S17). Since the amplitude of the primary frequency component in this double misfire pattern is about twice the amplitude intensity of the secondary frequency component, 2 is used when calculating (estimating) the amplitude a1 of the primary frequency component described later. The correction coefficient is used to double the amplitude of the next frequency component.

Further, in step S16, the ECU 10 which confirmed that the engine 101 did not cause two consecutive misfires and the discrimination ratio pdbl was equal to or higher than the discrimination threshold value had an amplitude correction coefficient kdbl = "KDBL-L", for example, "1". Is set in the memory 11 (step S18).

By the processing of steps S11 to S18, the amplitude correction coefficient kopp = "0" is set in the memory 11 when the oncoming misfire of FIG. 7 (d) occurs in the engine 101, and the engine 101 is set in FIG. 7. When the double misfire of (b) has occurred, the amplitude correction coefficient kdbl = "2" is set, and the single misfire of FIG. 7 (a) and the deletion fire of FIG. 7 (c) occur in the engine 101. Alternatively, if the misfire itself has not occurred, the amplitude correction coefficient kopp = "1" and the amplitude correction coefficient kdbl = "1" are set.

After that, the ECU 10 calculates and estimates the amplitude a1 of the primary frequency component from the amplitude estimation formula of the following equation using the amplitude correction coefficient kopp and the amplitude correction coefficient kdbl in the memory 11 and the acquired amplitude of the secondary frequency component. (Step S19).
Amplitude of primary frequency component a1 = Amplitude of secondary frequency component × kopp × kdbl

As a result, the ECU 10 can acquire the rotational characteristics F (a1, a2, a3) of the crankshaft 105 that is not affected by the resonance frequency of the damper 121, and can reliably execute the misfire determination process in the engine 101. Can be done.

Here, in steps S11 to S18, "0" or "1" is selected and set as the amplitude correction coefficient kopp, and "KDBL-H: 2" or "KDBL-L: 1" is selected and set as the amplitude correction coefficient kdbl. This case will be described as an example, but the present invention is not limited to this, and may be appropriately set according to the vehicle type of the vehicle 100 having different mounted devices such as the engine 101 and the damper 121. For example, a map for determining the amplitude correction coefficients kopp and kdbk according to the values of the discrimination ratio popp and pdbl calculated in steps S11 and S15 is stored and prepared in the memory 11, and the calculated discrimination ratio popp and pdbl are set. The corresponding amplitude correction coefficients kopp and kdbl may be determined and set in the memory 11.

Specifically, as a map for facing misfire stored in the memory 11, for example, as shown in FIG. 9A, a low threshold value of the discrimination ratio popp in which the amplitude correction coefficient kopp = "0" is set. The high threshold value of the discrimination ratio popp with "EOPP-THL" and the amplitude correction coefficient kopp = "1" is set to "EOPP-THH", and the discrimination ratio popp is set to the low threshold value "EOPP-THL". In the case of the high threshold value “EOPP-THH”, for example, an intermediate value between “0” and “1” may be set in the memory 11 as an amplitude correction coefficient kopp.

Further, as a map for double misfire stored in the memory 11, for example, as shown in FIG. 9B, the lower side of the discrimination ratio pdbl in which the amplitude correction coefficient kdbl = "EDBL-THL: 2" is set. The high threshold value of the discrimination ratio pdbl with the threshold value set to "EDBL-THL" and the amplitude correction coefficient kdbl = "EDBL-THH: 1" is set to "EDBL-THH", and the discrimination ratio pdbl is the low side threshold value. In the case of between "EDBL-THL" and the high threshold value "EDBL-THH", for example, the intermediate value between "KDBK-H: 2" and "KDBK-L: 1" is set as the amplitude correction coefficient kdbl and stored in the memory. It may be set within 11.

As a result, the ECU 10 optimizes the amplitude correction coefficient according to, for example, the equipment mounted on each vehicle type of the vehicle 100, and the rotational characteristics F (a1, a2, a3) of the crankshaft 105, which is not affected by the resonance frequency of the damper 121. ) Can be acquired with higher accuracy, and the misfire determination process in the engine 101 can be executed with higher reliability.

As described above, in the ECU 10 of the present embodiment, the primary frequency component of the crank shaft 105 of the engine 101 is estimated and acquired from the secondary frequency component and the tertiary frequency component that are not affected by the resonance frequency of the damper 121. Therefore, even if the engine 101 has a power transmission path for transmitting the rotational power of the engine 101 to the transmission 111 with the damper 121 interposed therebetween, the misfire determination of the engine 101 is highly reliable and high without being affected by the resonance of the damper 121. It can be executed with precision.

Although embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

10 ...... ECU (estimated tough, misfire determination device)
11 …… Memory 21 …… Output rotation sensor 22 …… Input rotation sensor 100 …… Vehicle 101 …… Engine (internal combustion engine)
102 ... Cylinder 103 ... Combustion chamber 104 ... Piston 105 ... Crankshaft 111 ... Transmission 115 ... Input shaft 121 ... Damper 122 ... Spring

Claims (1)

A misfire determination device that determines misfire in the combustion chamber of an internal combustion engine in which an input shaft having a resonance frequency of a transmission is connected to a crankshaft based on the rotational fluctuation of the crankshaft.
The process of acquiring the rotation information Ne of the crank shaft and the rotation information Nt of the input shaft, and calculating the rotation change amount ΔNe of the crank shaft and passing it through a digital filter to remove the primary frequency component to achieve the secondary or higher order. The process of acquiring the rotation fluctuation of the crank shaft including the frequency component and the amplitude of the first-order frequency component that is not affected by the resonance frequency separated and extracted by passing the rotation change amount ΔNe of the crank shaft through a digital filter are second-order or higher. The process of calculating and specifying from the amplitude of the frequency component of the above, and the rotation information Ne of the crank shaft and the rotation information Nt of the input shaft are processed by the physical model of the control function to remove the resonance frequency component, and then passed through a digital filter. By doing so, the process of specifying the phase of the primary frequency component and the primary frequency component that does not include the resonance frequency component are shaped from the amplitude and phase of the primary frequency component specified by the process to form the primary frequency of the crank shaft. The process of restoring the components and the primary frequency component shaped by the process are combined with the second and higher frequency components acquired by the process to acquire the rotational characteristics of the crankshaft that are not affected by the resonance frequency. Equipped with an estimation unit that performs processing and
As a physical model of the control function, a function process using the following equation that expresses the combustion torque Te of the internal combustion engine having the same behavior as the rotational change amount ΔNe of the crankshaft by the moment of inertia Ie of the internal combustion engine and the angular velocity ω. Extracts the primary frequency component of the crankshaft by
Te = Ie · dω
An internal combustion engine misfire determination device that acquires the frequency component of the rotational operation of the crankshaft according to the pattern of misfire that occurs in the combustion chamber of the internal combustion engine and determines the misfire of the internal combustion engine.

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