JP7199470B2 - Control device for internal combustion engine - Google Patents

Description

The present application relates to a control device for an internal combustion engine.

When the ignition timing is set to achieve optimum combustion efficiency, knocking (hereinafter referred to as knocking) may occur depending on changes in the environment, fuel used, and operating conditions. Since excessive knocking can damage the internal combustion engine, it is necessary to detect the occurrence of knocking using the output signal of a knock sensor and retard the ignition timing so that knocking does not occur.

JP-A-59-39972

By the way, the output signal of the knock sensor detected by the control device fluctuates even if the strength of the knocking vibration is the same due to the individual variation of the knock sensor, the variation of the input circuit of the control device, and the like. Due to this sensor variation, the strength of the output signal of the knock sensor increases or decreases when knock occurs, which causes a problem of erroneous determination of knock occurrence.

Japanese Patent Application Laid-Open No. 2002-200002 describes that if the comparison reference value for determining the occurrence of knock is fixed at a preset constant value, knock detection failures may occur due to individual variations in the output characteristics of the knock sensors or changes over time. ing. In the technique disclosed in Patent Document 1, the output signal of the knock sensor is obtained through a band-pass filter 48 that passes the knocking-specific frequency band (7 to 8 kHz), and the output of the knock sensor after filtering is obtained by a peak hold circuit 50. The peak value of the signal is obtained, and the value obtained by averaging the amplitude of the knock sensor output signal after filtering by the rectifying circuit 51 and the integrating circuit 55 is used as the background signal value immediately before the knock determination period in which the peak hold is performed. The comparison reference value is changed according to the background signal value, and the comparison reference value and the peak value are compared to determine whether or not knock has occurred.

However, in the technique of Patent Document 1, the signal immediately before the knock determination period is set as the background signal value, but the phenomenon of knocking includes various accidental factors, and the timing of knocking varies widely. . Therefore, the background signal value may include a knock component, and the calculated background signal value may become larger than the signal value due to the true background noise component, and the comparison reference value may become larger. . In this case, the occurrence of a knock with a high intensity can be detected, but the occurrence of a knock with a low intensity cannot be detected. Further, when the background noise component increases during the knock determination period in which peak hold is performed, the peak value increases even when knock does not occur, and it may be determined that knock has occurred erroneously.

Therefore, in the technique of Patent Document 1, the components of the same frequency band of the output signal of the knock sensor are used, and the background signal value and the signal value for determination (peak value) are set by dividing the set time band. As a result, the separation accuracy between the knock component and the background noise component is reduced for the knock occurrence phenomenon, which has large variations in the time of occurrence of knock. If the background noise component fluctuates during the period, there is a problem that the accuracy of knock determination decreases.

Therefore, the present application accurately acquires the background noise component and the knock component using the output signal of the knock sensor acquired in the same time period, and accurately detects the occurrence of knock based on the noise component and the knock component. It is an object of the present invention to provide a control device for an internal combustion engine capable of making a determination.

A control device for an internal combustion engine according to the present application includes:
a knock signal calculation unit that calculates the intensity of a plurality of analysis frequency components included in an output signal of a knock sensor provided in the internal combustion engine for each calculation cycle;
Compensation for calculating the strength for correction based on the strength of the component of the analysis frequency for correction set to the analysis frequency other than the analysis frequency for determining the occurrence of knock among the plurality of analysis frequencies for each calculation cycle. a strength calculation unit for
an intensity correction unit that corrects the intensity of the analytic frequency component for determination based on the intensity for correction, and calculates the intensity for determination after correction, for each calculation cycle;
a knock determination unit that determines presence/absence of knock based on the corrected strength for determination calculated in each of the calculation cycles ;
The correction strength calculation unit sets a plurality of correction analysis frequencies including an analysis frequency not adjacent to the determination analysis frequency, and calculates an average value of the strength of the components of the plurality of correction analysis frequencies. , is calculated as the intensity for correction.

According to the control apparatus for an internal combustion engine according to the present application, the intensity of the analytic frequency component for determining whether or not knocking occurs and the intensity of the analytic frequency component for correction, which is different from the analytic frequency for determination, are adjusted for each calculation cycle. The strength for correction is calculated based on the strength of the analysis frequency component for correction, the strength of the analysis frequency component for judgment is corrected based on the strength for correction, and the strength for judgment after correction is calculated. Calculated. Therefore, in response to the occurrence of knock, which has large variations in timing, the knock sensor output signal obtained during the same period of time is used to accurately separate the intensity of the background noise component from the intensity of the knock component. Even if the background noise component fluctuates during the knock occurrence period, the behavior of the noise component can be accurately acquired and reflected in the knock occurrence determination. Therefore, it is possible to improve the accuracy of knock occurrence determination.

1 is a schematic configuration diagram of an internal combustion engine according to Embodiment 1; FIG. 1 is a block diagram of a control device for an internal combustion engine according to Embodiment 1; FIG. 1 is a hardware configuration diagram of a control device for an internal combustion engine according to Embodiment 1; FIG. 4 is a diagram for explaining calculation of intensities of components of a plurality of analysis frequencies according to Embodiment 1; FIG. FIG. 4 is a diagram for explaining gain characteristics of the knock sensor according to Embodiment 1; FIG. 4 is a diagram for explaining gain characteristic data according to the first embodiment; FIG. FIG. 4 is a diagram for explaining strength increase characteristic data according to Embodiment 1; FIG. 4 is a diagram for explaining variation in sensor gain according to Embodiment 1; FIG. FIG. 4 is a diagram for explaining increase and decrease in strength due to variations in sensor gain according to the first embodiment; FIG. 10 is a diagram illustrating components of each analysis frequency after correction with respect to variations in sensor gain according to Embodiment 1; FIG. 7 is a diagram for explaining knock determination based on the corrected strength for determination according to the first embodiment;

1. Embodiment 1
A control device 50 (hereinafter simply referred to as control device 50) for internal combustion engine 1 according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an internal combustion engine 1 according to this embodiment. Although the internal combustion engine 1 according to the present embodiment has a plurality of combustion chambers 25 (eg, three), only one combustion chamber 25 is shown in FIG. 1 for convenience. The internal combustion engine 1 and the control device 50 are mounted on a vehicle, and the internal combustion engine 1 serves as a driving force source for the vehicle (wheels).

1-1. Configuration of Internal Combustion Engine 1 First, the configuration of the internal combustion engine 1 will be described. The internal combustion engine 1 has a combustion chamber 25 in which a mixture of air and fuel is combusted. The internal combustion engine 1 includes an intake passage 23 that supplies air to a combustion chamber 25 and an exhaust passage 17 that discharges exhaust gas burned in the combustion chamber 25 . The internal combustion engine 1 has a throttle valve 6 that opens and closes an intake passage 23 . The throttle valve 6 is an electronically controlled throttle valve driven to open and close by an electric motor controlled by a control device 50 . The throttle valve 6 is provided with a throttle opening sensor 7 that outputs an electric signal corresponding to the opening of the throttle valve 6 .

An air cleaner 24 that cleans the air taken into the intake passage 23 is provided at the most upstream portion of the intake passage 23 . An airflow sensor 3 that outputs an electric signal corresponding to the flow rate of intake air drawn into the intake passage 23 is provided in the intake passage 23 on the upstream side of the throttle valve 6 . A portion of the intake passage 23 on the downstream side of the throttle valve 6 serves as an intake manifold 11 and is connected to a plurality of combustion chambers 25 . A portion on the upstream side of the intake manifold 11 serves as a surge tank that suppresses intake pulsation.

The intake manifold 11 is provided with a manifold pressure sensor 8 that outputs an electrical signal corresponding to manifold pressure, which is the pressure of the gas in the intake manifold 11 . Only one of the airflow sensor 3 and the manifold pressure sensor 8 may be provided. An injector 13 for injecting fuel is provided in a downstream portion of the intake manifold 11 . Note that the injector 13 may be provided so as to inject fuel directly into the combustion chamber 25 .

At the top of the combustion chamber 25, an ignition plug 18 that ignites the mixture of air and fuel, and an ignition coil 16 that supplies ignition energy to the ignition plug 18 are provided. At the top of the combustion chamber 25, an intake valve 14 for adjusting the amount of intake air drawn into the combustion chamber 25 from the intake passage 23 and an exhaust valve 14 for adjusting the amount of exhaust gas discharged from the cylinder to the exhaust passage 17 are provided. A valve 15 is provided. The intake valve 14 is provided with a variable valve timing mechanism 14a that varies the opening/closing timing of the intake valve. The exhaust valve 15 is provided with a variable valve timing mechanism 15a that varies the opening/closing timing of the exhaust valve. The intake and exhaust variable valve timing mechanisms 14a and 15b each have an electric actuator that changes the valve opening/closing timing.

A crankshaft of the internal combustion engine 1 is provided with a signal plate having a plurality of teeth provided at predetermined angular intervals on the outer periphery thereof. The crank angle sensor 9 is fixed to the cylinder block so as to face the teeth of the signal plate of the crankshaft, and outputs a pulse signal synchronized with the passage of the teeth. Although not shown, the camshaft of the internal combustion engine 1 is provided with a signal plate having a plurality of teeth provided at predetermined angular intervals on its outer periphery. The cam angle sensor 10 is fixed facing the tooth of the signal plate of the camshaft and outputs a pulse signal synchronized with the passage of the tooth.

The control device 50 detects the crank angle with reference to the top dead center of each piston 5 based on two types of output signals from the crank angle sensor 9 and the cam angle sensor 10, and determines the stroke of each combustion chamber 25. do.

A knock sensor 12 is fixed to the cylinder block. The knock sensor 12 outputs a signal (vibration waveform signal) corresponding to the vibration of the internal combustion engine 1 . Knock sensor 12 is composed of a piezoelectric element or the like. Knock sensor 12 is of a non-resonant type.

The internal combustion engine 1 is provided with various known mechanisms such as an external EGR mechanism, a variable valve lift mechanism, a variable compression ratio mechanism, a turbocharger mechanism, a swirl control valve mechanism, and a tumble control valve mechanism. may be configured to be Further, the internal combustion engine 1 may not be provided with one or both of the intake and exhaust variable valve timing mechanisms 14a and 15b.

1-2. Configuration of Control Device 50 Next, the control device 50 will be described. The control device 50 is a control device that controls the internal combustion engine 1 . As shown in the block diagram of FIG. 2, the control device 50 includes control units such as a knock signal calculation unit 51, a correction strength calculation unit 52, a strength correction unit 53, a knock determination unit 54, and an ignition control unit 55. there is Each of the control units 51 to 55 and the like of the control device 50 is realized by a processing circuit provided in the control device 50. FIG. Specifically, as shown in FIG. 3, the control device 50 includes an arithmetic processing unit 90 (computer) such as a CPU (Central Processing Unit) as a processing circuit, and a signal line such as a bus to the arithmetic processing unit 90. It includes a connected storage device 91, an input circuit 92 for inputting an external signal to the arithmetic processing unit 90, an output circuit 93 for outputting a signal from the arithmetic processing unit 90 to the outside, and the like.

As the arithmetic processing unit 90, an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, various signal processing circuits, and the like are provided. may Further, as the arithmetic processing unit 90, a plurality of units of the same type or different types may be provided, and each process may be shared and executed.

As the storage device 91, volatile and nonvolatile storage devices such as RAM (Random Access Memory), ROM (Read Only Memory), and EEPROM (Electrically Erasable Programmable ROM) are provided. The input circuit 92 is connected to various sensors and switches, and includes an A/D converter and the like for inputting output signals of these sensors and switches to the arithmetic processing unit 90 . The output circuit 93 is connected to electric loads, and includes a drive circuit and the like for outputting control signals from the arithmetic processing unit 90 to these electric loads.

Each function of the control units 51 to 55 provided in the control device 50 is performed by the arithmetic processing device 90 executing software (program) stored in a storage device 91 such as a ROM and an EEPROM, and the storage device 91, input It is realized by cooperating with other hardware of the controller 50 such as the circuit 92 and the output circuit 93 . The intensity increase characteristic data, gain characteristic data, and setting data such as threshold values used by the control units 51 to 56 are stored in a storage device 91 such as ROM and EEPROM as part of software (program). . Further, the data of each calculated value and each detected value such as the output signal of the knock sensor calculated by each of the control units 51 to 55, the intensity of a plurality of analysis frequency components, the intensity for correction, the intensity for judgment after correction, etc. , RAM or the like.

In this embodiment, the input circuit 92 is connected to the airflow sensor 3, the throttle opening sensor 7, the manifold pressure sensor 8, the crank angle sensor 9, the cam angle sensor 10, the knock sensor 12, the accelerator position sensor 26, and the like. ing. The output circuit 93 is connected to the throttle valve 6 (electric motor), the injector 13, the variable valve timing mechanisms 14a and 15b for the intake and exhaust valves, the ignition coil 16, and the like. Various sensors, switches, actuators, etc. (not shown) are connected to the control device 50 .

The control device 50 detects the amount of intake air based on the output signal of the airflow sensor 3 or the manifold pressure sensor 8, detects the throttle opening based on the output signal of the throttle opening sensor 7, and detects the throttle opening based on the output signal of the accelerator position sensor 26. The accelerator opening is detected based on the output signal. The control device 50 detects the crank angle, the rotation speed, and the opening/closing timing of the intake valve 14 based on the output signals of the crank angle sensor 9 and the cam angle sensor 10 .

As basic control, the control device 50 calculates the fuel injection amount, ignition timing, etc. based on the output signals of various sensors that are input, and drives and controls the injector 13, the ignition coil 16, and the like. Ignition control will be described later. The control device 50 calculates the output torque of the internal combustion engine 1 requested by the driver based on the accelerator opening and the like, and adjusts the throttle valve 6 and the like so that the amount of intake air to achieve the requested output torque. Control. Specifically, the control device 50 calculates a target throttle opening, and drives and controls the electric motor of the throttle valve 6 so that the throttle opening approaches the target throttle opening.

In addition, the control device 50 calculates the target opening/closing timing of the intake valve and the target opening/closing timing of the exhaust valve based on the output signals of the various sensors that have been input, and based on each target opening/closing timing, the intake and exhaust are variable. It drives and controls the valve timing mechanisms 14a and 15a.

1-2-1. Knock signal calculator 51
The knock signal calculator 51 causes the A/D converter of the input circuit 92 to A/D convert the output signal of the knock sensor 12 at sampling intervals during the knock determination period set corresponding to each combustion cycle. An output signal of the knock sensor 12 is acquired. The output signal of the knock sensor 12 acquired at the sampling period is stored in a storage device 91 such as a RAM for a predetermined storage period.

Knock signal calculation unit 51 calculates the intensity of a plurality of analysis frequency components included in the output signal of knock sensor 12 for each calculation cycle.

In the present embodiment, knock signal calculation unit 51 calculates the output signals of a plurality of knock sensors 12 acquired during the immediately preceding processing period for each calculation period in the knock determination period set corresponding to each combustion cycle. are subjected to Fourier transform processing, band-pass filter processing, or the like to calculate the intensity of a plurality of analysis frequency components. The knock determination period of each combustion cycle is set to a period within a predetermined angular range before and after the ignition timing of each cylinder (for example, a period from 10 degrees before top dead center to 60 degrees after top dead center). The processing period is set to, for example, the calculation cycle.

For example, as the Fourier transform process, the knock signal calculation unit 51 performs a discrete Fourier transform (DFT) or a short-time Fourier transform (DFT) on the output signals of the knock sensors 12 acquired during the processing period for each calculation period. STFT) or the like is performed to calculate the spectrum of a plurality of analysis frequencies, and the magnitude of the spectrum of each analysis frequency is calculated as the intensity of the component of each analysis frequency.

For example, as shown in the result of the Fourier transform process in FIG. 4, a plurality of analytic frequencies are set at predetermined frequency intervals in a predetermined frequency interval, and the intensity is calculated for each analytic frequency. . For example, the frequency interval is set to 4 kHz to 22 kHz, the frequency interval is set to 2 kHz, and the multiple analysis frequencies are set to 4, 6, 8, 10, 12, 14, 16, 18, 20, and 22 kHz. set. A frequency band used for knock determination is usually about 5 kHz to 20 kHz, and a plurality of analysis frequencies are set so as to cover this frequency band.

Alternatively, the knock signal calculation unit 51 performs the band-pass filter processing, for each calculation cycle in the knock determination period set corresponding to each combustion cycle, to calculate the values of the plurality of knock sensors 12 acquired during the immediately preceding processing period. An infinite impulse response (IIR) filter, a finite impulse response (FIR) filter, or the like is applied to the output signal to acquire a plurality of analysis frequency components, and the magnitude of each analysis frequency component is You may calculate as the intensity|strength of a component. For each of the plurality of analytic frequencies, band-pass filtering is performed to pass the components of each analytic frequency, and the components of each analytic frequency are extracted. That is, band-pass filtering processes corresponding to the number of analysis frequencies are performed in parallel.

Note that the knock signal calculation unit 51 may calculate the magnitude of the component of only the analytic frequency for determination and the analytic frequency for correction.

<Correction of sensor gain characteristics>
Depending on the knock sensor, as shown in FIG. 5, the gain of each analytic frequency may change, and the gain of the analytic frequency for determination and the gain of the analytic frequency for correction may differ. In this case, the accuracy of correction of the intensity of the analysis frequency component for determination using the correction intensity decreases due to the difference in gain.

In the present embodiment, knock signal calculator 51 is configured to correct the intensity of a plurality of analysis frequency components using gain characteristic data. The gain characteristic data is characteristic data of the gain of the intensity of the component of each analysis frequency calculated by the knock signal calculator 51 with respect to the intensity of the vibration component of each analysis frequency input to the knock sensor. For example, as shown in FIG. 6, the gain characteristic data is map data in which the gain is set for each analysis frequency, and is stored in advance in a storage device such as a ROM. A gain ratio or the like to a reference gain may be set for the gain of the characteristic data.

Knock signal calculation section 51 multiplies the intensity of each analysis frequency component by a correction coefficient (for example, the reciprocal of the gain) corresponding to the reciprocal of the gain of each analysis frequency obtained from the gain characteristic data, and calculates the value as a final value. calculated as the intensity of each analysis frequency component.

In the present embodiment, a knock sensor having a constant gain is used in the frequency band used for knock determination (eg, 5 kHz to 20 kHz), and correction using gain characteristic data may not be performed.

1-2-2. Correction intensity calculator 52
The correction strength calculation unit 52 performs correction based on the strength of the component of the correction analysis frequency set to an analysis frequency other than the analysis frequency for determining the occurrence of knock among the plurality of analysis frequencies for each calculation cycle. Calculate the strength for use.

<Setting analysis frequency for correction>
The correction intensity calculation unit 52 sets the analysis frequency for correction to an analysis frequency other than the analysis frequency for determining the occurrence of knock, at which the intensity increases when a knock occurs. For example, the correction intensity calculator 52 sets the analysis frequency for correction for each knock determination period.

In the present embodiment, the correction intensity calculator 52 sets, as the correction analysis frequency, a specific analysis frequency at which the intensity becomes smaller than the threshold when knock occurs, among the plurality of analysis frequencies. For example, as shown in FIG. 4, when a central product knock sensor is used, one or more analysis frequencies (eight frequencies excluding 12 and 20 kHz in the example of FIG. (4-10, 14-18, 22 kHz) are set as analysis frequencies for correction.

In the example of FIG. 4, the analysis frequency for determination is set to 20 kHz, and the analysis frequency for correction is not set. Analysis frequency for correction is not set. In this way, there is an analytic frequency other than the analytic frequency for judgment, at which the intensity becomes larger than the threshold when knock occurs, and such an analytic frequency can be prevented from being set as the analytic frequency for correction. Not all the analysis frequencies whose intensities are smaller than the threshold may be set as correction analysis frequencies, and some analysis frequencies may be set as correction analysis frequencies.

As shown in FIG. 11, which will be described later, even during the knock determination period in which knocking occurs, the intensity of the analysis frequency component for determination changes at each time point. The analytic frequency for correction is set based on the intensity of each analytic frequency when the intensity of is maximized.

The analysis frequency at which the intensity becomes smaller than the threshold when knock occurs changes depending on the operating state of the internal combustion engine. Therefore, the correction strength calculation unit 52 uses strength increase characteristic data in which information regarding the strength increase of each analysis frequency component at the time of occurrence of knocking is set in advance for each operating point in a specific operating state of the internal combustion engine. , to set the analysis frequency for correction corresponding to the current operating state.

In this embodiment, the rotation speed Ne is used as the specific operating state. Note that, in addition to the rotation speed Ne, another operating state such as the in-cylinder intake air amount may be used as the specific operating state. As shown in FIG. 7, the strength increase characteristic data includes a plurality of analysis frequencies and each The relationship between the intensity of the analysis frequency and the intensity is preset as map data. Then, the correction intensity calculator 52 refers to the intensity increase characteristic data and acquires the intensity of each analysis frequency corresponding to the current operating state (rotational speed Ne). Then, as shown in FIG. 4, the correction intensity calculation unit 52 compares the acquired intensity of each analysis frequency with a threshold value, and selects one or a plurality of analysis frequencies whose intensity is lower than the threshold value for correction analysis. Set as frequency. On the other hand, the analytic frequency for determination is set corresponding to the analytic frequency that maximizes the intensity when knock occurs. Note that the analysis frequency for determination may be set using strength increase characteristic data.

Alternatively, the strength increase characteristic data may be map data in which setting information of one or more analysis frequencies for correction is set in advance for each operating point of a specific operating state (rotational speed Ne in this example). good. Then, the correction strength calculation unit 52 refers to the strength increase characteristic data, acquires one or more setting information of the analysis frequency for correction corresponding to the current operating state (rotational speed Ne), and obtains one or more An analysis frequency for correction may be set.

Further, the correction strength calculation unit 52 may set the analysis frequency for correction to a specific preset analysis frequency without using the strength increase characteristic data.

<Calculation of Correction Intensity>
The correction strength calculator 52 calculates the correction strength based on the strength of the correction analysis frequency component for each calculation cycle. In the present embodiment, the correction strength calculation unit 52 calculates the strength corresponding to the set correction analysis frequency from the strengths of the components of the plurality of analysis frequencies calculated by the knock signal calculation unit 51 for each calculation period. is selected, and the strength for correction is calculated based on the strength of the selected analysis frequency component for correction.

When a plurality of correction analysis frequencies are set, the correction strength calculator 52 calculates the average value of the strengths of the components of the plurality of correction analysis frequencies as the correction strength. When one correction analysis frequency is set, the correction strength calculator 52 calculates the strength of the component of one correction analysis frequency as the correction strength.

1-2-3. Intensity corrector 53
<Intensity Fluctuation Due to Variation in Gain Characteristics>
The knock sensor is managed so that the gain of 5 kHz to 20 kHz, which is often used for knock detection, is almost constant. However, as shown in FIG. 8, due to variations in the sensor or in the input circuit 92 of the control device 50, the sensor gain may increase or decrease at the same rate for all analysis frequencies. be. In FIG. 8, A is the gain characteristic of the middle product, B is the gain characteristic of the upper limit product when there is variation on the increasing side, and C is the gain characteristic of the lower limit product when there is variation on the decreasing side.

As shown in FIG. 9, in proportion to the rate of increase or decrease in the sensor gains of the upper limit product B and the lower limit product C with respect to the middle product A in FIG. increase or decrease at a rate of If the knock determination is performed using the strength of the analysis frequency component for determination that is increased or decreased due to the fluctuation of the sensor gain, an erroneous determination is likely to occur.

<Correction by Correction Intensity>
Therefore, the intensity correction unit 53 corrects the intensity of the analysis frequency component for determination based on the intensity for correction, and calculates the intensity for determination after correction for each calculation cycle.

The influence of fluctuations in the gain characteristics of the sensor appears not only in the intensity of the analytic frequency component for determination but also in the intensity of the analytic frequency component for correction. The intensity of each analysis frequency component includes the intensity of background noise components due to various mechanical vibrations, regardless of whether or not knocking occurs. When knock occurs, the strength of the analysis frequency component used for judgment increases significantly from the strength of the background noise component, but the strength of the analysis frequency component used for correction decreases significantly from the strength of the background noise component. not increase. Therefore, the intensity of the component of the analysis frequency for correction is less affected by the fluctuation of the sensor gain because the increase in intensity due to the occurrence of knocking is reduced. That is, it is possible to reduce the influence of knock generation and detect the influence of sensor gain fluctuation by the intensity of the component of the analysis frequency for correction. According to the above configuration, by correcting the intensity of the analysis frequency component for determination based on the intensity for correction, it is possible to accurately compensate for fluctuations in the intensity of the analysis frequency component for determination due to fluctuations in the sensor gain. can be done.

For example, the intensity correction unit 53 divides the intensity of the analysis frequency component for determination by the intensity for correction to calculate the intensity for determination after correction. According to this configuration, the rate of change in the sensor gain included in the intensity of the analysis frequency component for determination is divided by the rate of change in the sensor gain included in the intensity of the analysis frequency component for correction. The effects of fluctuations can be canceled out.

FIG. 10 shows the intensity of each analysis frequency component after correction, which is obtained by dividing the intensity of each analysis frequency component in FIG. 9 by the correction intensity. In the case of the median product A, the upper limit product B, and the lower limit product C, the influence of fluctuations in gain characteristics is cancelled. FIG. 10 tentatively shows knock determination thresholds. In all of the middle product A, the upper limit product B, and the lower limit product C, the intensity of the analysis frequency component for determination after correction exceeds the knock determination threshold. Accurate determination is possible even if the sensor gain fluctuates.

The analysis frequency for determination may be set to a plurality of analysis frequencies. The intensity correction unit 53 may set the maximum value of the intensity of a plurality of determination analysis frequency components as the intensity of the determination analysis frequency component, and perform correction based on the correction intensity.

1-2-4. Knock determination unit 54
Knock determination unit 54 determines whether or not knock occurs based on the corrected strength for determination calculated in each calculation cycle. In the present embodiment, the knock determination unit 54 determines whether or not knock occurs in each combustion cycle based on a plurality of corrected determination magnitudes calculated in a plurality of calculation cycles of the knock determination period of each combustion cycle. judge.

FIG. 11 shows a time-series graph of a plurality of post-correction determination intensities calculated in a plurality of calculation cycles during the knock determination period of one combustion cycle. The intensity for determination after correction in each computation cycle is calculated based on the intensity of the analysis frequency component for correction calculated in each computation cycle, the intensity for correction, and the intensity of the analysis frequency component for determination. .

For example, knock determination unit 54 determines that knock has occurred when the magnitude for determination after correction for one or more calculation cycles exceeds the knock determination threshold in the knock determination period. If the intensity for determination after correction does not exceed the knock determination threshold value, it is determined that knocking has not occurred. Various known methods can be used for the method of setting the knock determination threshold and the method of determination using the threshold.

1-2-5. Ignition control unit 55
The ignition control unit 55 changes the ignition timing based on the knock determination result, and controls the energization of the ignition coil 16 so that the spark plug 18 starts discharging at the ignition timing (crank angle). The ignition control unit 55 retards the ignition timing of the next combustion cycle when it is determined that knock has occurred, and retards the ignition timing of the next combustion cycle when it is determined that knock has not occurred. ignition timing of is advanced. Various known methods are used for ignition control based on the knock determination result.

Although the present application has described exemplary embodiments, the various features, aspects, and functions described in the embodiments are not limited to application of particular embodiments, alone or Various combinations are applicable to the embodiments. Accordingly, numerous variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, the modification, addition, or omission of at least one component shall be included.

1 Internal Combustion Engine 12 Knock Sensor 16 Ignition Coil 50 Control Device for Internal Combustion Engine 51 Knock Signal Calculation Unit 52 Correction Intensity Calculation Unit 53 Intensity Correction Unit 54 Knock Determination Unit 55 Ignition Control Unit

Claims (7)

a knock signal calculation unit that calculates the intensity of a plurality of analysis frequency components included in an output signal of a knock sensor provided in the internal combustion engine for each calculation cycle;
Compensation for calculating the strength for correction based on the strength of the component of the analysis frequency for correction set to the analysis frequency other than the analysis frequency for determining the occurrence of knock among the plurality of analysis frequencies for each calculation cycle. a strength calculation unit for
an intensity correction unit that corrects the intensity of the analytic frequency component for determination based on the intensity for correction, and calculates the intensity for determination after correction, for each calculation cycle;
a knock determination unit that determines presence/absence of knock based on the corrected strength for determination calculated in each of the calculation cycles ;
The correction strength calculation unit sets a plurality of correction analysis frequencies including an analysis frequency not adjacent to the determination analysis frequency, and calculates an average value of the strength of the components of the plurality of correction analysis frequencies. , a control device for an internal combustion engine that calculates the strength for correction . a knock signal calculation unit that calculates the intensity of a plurality of analysis frequency components included in an output signal of a knock sensor provided in the internal combustion engine for each calculation cycle;
An analysis frequency for correction which is set to an analysis frequency other than the analysis frequency for judging the occurrence of knocking and which is not adjacent to the analysis frequency for judgment among the plurality of analysis frequencies for each calculation period. a correction strength calculation unit that calculates a correction strength based on the strength of the component of
an intensity correction unit that corrects the intensity of the analytic frequency component for determination based on the intensity for correction, and calculates the intensity for determination after correction, for each calculation cycle;
A control device for an internal combustion engine, comprising: a knock determination unit that determines whether or not knock occurs based on the corrected magnitude for determination calculated in each calculation cycle. a knock signal calculation unit that calculates the intensity of a plurality of analysis frequency components included in an output signal of a knock sensor provided in the internal combustion engine for each calculation cycle;
Compensation for calculating the strength for correction based on the strength of the component of the analysis frequency for correction set to the analysis frequency other than the analysis frequency for determining the occurrence of knock among the plurality of analysis frequencies for each calculation cycle. a strength calculation unit for
an intensity correction unit that corrects the intensity of the analytic frequency component for determination based on the intensity for correction, and calculates the intensity for determination after correction, for each calculation cycle;
a knock determination unit that determines presence/absence of knock based on the corrected strength for determination calculated in each of the calculation cycles;
The knock signal calculation section uses the characteristic data of the gain of the intensity of each analysis frequency component calculated by the knock signal calculation section with respect to the intensity of the vibration component of each analysis frequency input to the knock sensor. A control device for an internal combustion engine that corrects the intensity of a plurality of analysis frequency components. 4. The compensating intensity calculator according to any one of claims 1 to 3 , wherein, among the plurality of analytic frequencies, the analytic frequency for compensation is set to a specific analytic frequency at which the intensity becomes smaller than a threshold when a knock occurs. A control device for an internal combustion engine according to claim 1 . 4. The correction intensity calculation unit according to claim 3 , wherein the correction intensity calculation unit sets a plurality of the correction analysis frequencies, and calculates an average value of intensities of components of the plurality of correction analysis frequencies as the correction intensity. A control device for an internal combustion engine. The correction strength calculation unit uses strength increase characteristic data in which information about an increase in strength of each analysis frequency component at the time of occurrence of knock is set in advance for each operating point in a specific operating state of the internal combustion engine, 6. The control device for an internal combustion engine according to claim 1 , wherein the analysis frequency for correction corresponding to the current operating state is set. The knock signal calculation unit calculates the intensity of the components of the plurality of analysis frequencies based on the output signal of the knock sensor for each calculation cycle in the knock determination period set corresponding to each combustion cycle,
The correction strength calculation unit calculates the correction strength based on the strength of the correction analysis frequency component for each calculation cycle,
The intensity correction unit corrects the intensity of the analysis frequency component for determination based on the intensity for correction, and calculates the intensity for determination after correction,
The knock determination unit determines whether or not knock occurs in each of the combustion cycles based on the plurality of corrected determination intensities calculated in the plurality of calculation cycles of the knock determination period of each of the combustion cycles. 7. The control device for an internal combustion engine according to any one of claims 1 to 6 .

Images