JP3868172B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine control device that controls an operating state of an internal combustion engine based on knock determination.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a control device for an internal combustion engine that performs knock determination on a knock signal extracted from a vibration signal waveform generated in the internal combustion engine and controls knock control factors such as ignition timing and fuel injection amount is known.
[0003]
[Problems to be solved by the invention]
As a knock detection system in the control device for an internal combustion engine, a knock signal is extracted from a vibration signal waveform detected by a knock sensor by a band pass filter, and a peak output value of the knock signal is obtained as an output distribution characteristic of a lognormal distribution. The presence / absence of knock occurrence is determined by comparison with a predetermined knock determination level.
[0004]
By the way, for example, when the ignition timing is further retarded under specific operating conditions such as WOT (Wide Open Throttle: throttle valve fully open / full load), engine speed 2000 [rpm] and no knocking occurrence, A noise signal related to combustion (hereinafter referred to as a “pseudo knock signal”) as shown in FIG. 6B, which is different from the knock signal shown in FIG. . When these knock signals and the pseudo knock signal are compared, the knock signal has a feature that the peak output timing is early and the signal generation time is short, whereas the pseudo knock signal has a substantially constant output value and a long signal generation time. However, the frequencies of the knock signal and the pseudo knock signal are substantially the same.
[0005]
When this pseudo knock occurs, a sound similar to that at the time of knock occurs, so that the driver feels a sense of discomfort similar to that when the knock occurs.
[0006]
Accordingly, the present invention has been made to solve such a problem, and is an internal combustion engine capable of appropriately controlling the operating state of the internal combustion engine while avoiding the generation of a pseudo knock due to a pseudo knock signal that is a noise signal different from the knock signal. It is an issue to provide a control device for a vehicle.
[0007]
[Means for Solving the Problems]
According to the control apparatus for an internal combustion engine of claim 1, when knock is detected by the knock detection means based on the vibration signal waveform generated in the internal combustion engine, the ignition timing is retarded by the knock control means, and when knock is not detected The ignition timing is returned to the advanced angle. When the retard amount during the knock control is larger than a predetermined value, the air-fuel ratio by the air-fuel ratio control means is corrected to the lean side by the correction control means based on the retard amount. Is done. Thereby, generation | occurrence | production of a pseudo knock is prevented beforehand and the driving | running state of an internal combustion engine is controlled appropriately.
[0008]
In the correction control means in the control apparatus for an internal combustion engine according to the second aspect, the correction amount of the air-fuel ratio is set differently for each preset cylinder or each cylinder group. Accordingly, it is possible to cope with the case where the cylinder or the cylinder group in which the pseudo knock is likely to be generated varies depending on various conditions, and the generation of the pseudo knock is appropriately avoided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0013]
FIG. 1 is a block diagram showing the overall configuration of an internal combustion engine control apparatus according to an embodiment of the present invention.
[0014]
In FIG. 1, reference numeral 10 denotes a knock sensor which is attached to a cylinder block (not shown) of the internal combustion engine and detects a vibration signal waveform generated in the internal combustion engine, and 11 is a knock from the vibration signal waveform of the knock sensor 10. A band pass filter (Band Pass Filter: specific frequency band pass filter; hereinafter referred to as “BPF”) having a bandwidth (Q value) of 10 [dB] for extracting the components related to. The knock signal extracted by the BPF 11 is peak-held in accordance with the peak hold signal from the microcomputer 20 in the peak hold circuit 12, and then A / D converted (analog-digital conversion) by the A / D converter 21. The peak output value V is taken into the microcomputer 20.
[0015]
In addition, the microcomputer 20 receives various sensor signals from, for example, a crank angle sensor, an intake air amount sensor, a water temperature sensor, and the like of the internal combustion engine. Based on these captured signals, the microcomputer 20 calculates the ignition timing, fuel injection amount, and the like. Then, the calculation result from the microcomputer 20 is an igniter 30, an injector (fuel injection valve) 40, and a known variable valve timing control mechanism (Variable Valve Timing Control Mechanism; provided on the intake side camshaft (not shown)). (Denoted as “VVT”) and the like.
[0016]
Here, the microcomputer 20 includes a CPU as a central processing unit that executes various known arithmetic processes, a ROM that stores a control program, a RAM that stores various data, a B / U (backup) RAM, an input / output circuit, and the like. Is configured as a logical operation circuit including a bus line or the like for connecting the two.
[0017]
Next, based on the flowchart of FIG. 2 showing the processing procedure of the air-fuel ratio correction coefficient calculation following the end of the knock determination in the microcomputer 20 used in the control apparatus for an internal combustion engine according to an example of the embodiment of the present invention. This will be described with reference to FIGS. Here, FIG. 3 is a characteristic diagram showing the pseudo knock occurrence frequency [%] with respect to the ignition timing variation, and FIG. 4 is a characteristic diagram showing the pseudo knock occurrence frequency [%] with respect to the A / F variation. This air-fuel ratio correction coefficient calculation routine is executed by the microcomputer 20 following the end of the knock determination.
[0018]
In FIG. 2, in step S101, it is determined whether or not it is in a specific operation region within a knock control region that is known in advance through experiments or the like that a pseudo knock is likely to occur. When the determination condition of step S101 is satisfied, that is, when it is in the specific operation region, the process proceeds to step S102, and the retard amount at the ignition timing at this time is read. Next, the process proceeds to step S103, and the retardation amount read in step S102 is set as the KNT value. Next, the process proceeds to step S104, and it is determined whether the KNT value exceeds a predetermined value K1 set in advance. If the determination condition in step S104 is satisfied, that is, if the KNT value exceeds the predetermined value K1 and is on the retard side, the process proceeds to step S105 assuming that a pseudo knock has occurred.
[0019]
That is, as indicated by a thick line in FIG. 3, the frequency of occurrence of pseudo knock, which is noise related to combustion, increases at this time. The characteristic indicated by the thin line in FIG. 3 is the frequency of occurrence of normal knock occurring on the advance side of the ignition timing. In step S105, the air-fuel ratio correction coefficient ΔA / F is set to f (KNT) by a table (not shown), and as shown in FIG. 4, the A / F is unlikely to generate pseudo knock, that is, the frequency of occurrence of pseudo knock. The air-fuel ratio correction coefficient ΔA / F is corrected to the lower lean side, and this routine is finished.
[0020]
On the other hand, when the determination condition of step S101 is not satisfied, that is, when it is not in the specific operation region, or when the determination condition of step S104 is not satisfied, that is, when the KNT value is smaller than the predetermined value K1, occurrence of a pseudo knock is not generated. If it is determined that a normal knock has occurred, the routine proceeds to step S106, and after the air-fuel ratio correction coefficient ΔA / F is set to “0”, this routine is terminated.
[0021]
As described above, the control device for an internal combustion engine of the present embodiment includes a knock sensor 10 that detects knock based on a vibration signal waveform generated in the internal combustion engine (not shown), a BPF (bandpass filter) 11, a peak hold circuit 12, The knock detection means achieved by the microcomputer 20 and the microcomputer 20 that retards the ignition timing when a knock is detected by the knock detection means and advances the ignition timing when the knock is not detected are achieved. When the knock control means, the air / fuel ratio control means achieved by the microcomputer 20 for controlling the A / F (air / fuel ratio) of the internal combustion engine, and the retard amount by the knock control means are larger than a predetermined value, the retard angle A microcomputer 20 that performs correction control so that the A / F by the air-fuel ratio control means is on the lean side based on the amount It is intended to and a correction control means is made.
[0022]
In other words, when the knock is detected based on the vibration signal waveform generated in the internal combustion engine, the ignition timing is retarded, and when the knock is not detected, the ignition timing is returned to the advanced timing. When the angular amount is larger than a predetermined value, the A / F is corrected and controlled to the lean side based on the retardation amount. Thereby, generation | occurrence | production of a pseudo knock is prevented beforehand and the driving | running state of an internal combustion engine can be controlled appropriately.
[0023]
By the way, in the above embodiment, when the ignition timing exceeds the predetermined value K1 set in advance and is retarded, the air-fuel ratio correction coefficient ΔA / F is changed to correct the A / F to the lean side and pseudo knock However, the present invention is not limited to this, and the valve opening timing of the intake VVT 50 is delayed, that is, the occurrence frequency [%] of pseudo knock with respect to intake VVT fluctuations is reduced. As shown in the characteristic diagram of FIG. 5, when the intake VVT 50 is changed to the retard side, the valve overlap amount between an exhaust valve and an intake valve (not shown) is reduced, and the internal EGR amount is reduced to avoid the occurrence of a pseudo knock. You can also.
[0024]
Such a control device for an internal combustion engine includes a knock sensor 10 that detects a knock based on a vibration signal waveform generated in an internal combustion engine (not shown), a BPF (bandpass filter) 11, a peak hold circuit 12, and a microcomputer 20. Knock detection means achieved, and knock control means achieved by the microcomputer 20 that retards the ignition timing when the knock detection means detects a knock, and advances the ignition timing when the knock detection is not detected, When the internal combustion engine's internal EGR amount can be changed by the intake VVT 50, the microcomputer 20, etc., and when the retardation amount by the knocking control device is larger than a predetermined value, the EGR is based on the retardation amount. The control means corrects and controls at least one of the external EGR amount and the internal EGR amount. That is intended to and a correction control means which is achieved by the microcomputer 20, the same effect can be expected as in the above example.
[0025]
Further, by using the exhaust VVT instead of the intake VVT 50, the internal EGR amount may be reduced to avoid the occurrence of a pseudo knock, or a combination thereof may be used. Furthermore, instead of changing the internal EGR amount by the intake VVT 50 or the exhaust VVT, if the system configuration is such that the exhaust gas from the exhaust passage is recirculated to the intake passage side using a known EGR valve, the external EGR amount can be changed. By reducing the external EGR amount, the occurrence of pseudo knock can be avoided.
[0026]
In the above embodiment, when the retard amount by the knock control is larger than the predetermined value, the correction control is performed so that the A / F is on the lean side based on the retard amount. However, the present invention is not limited to this, and the operating condition in which pseudo knock is likely to occur is known in advance as a specific operating condition in the knock control region of the internal combustion engine, for example, near WOT, engine speed 2000 [rpm]. Therefore, if the correction control is performed under such operating conditions, the occurrence of pseudo knock can be prevented in advance.
[0027]
Furthermore, in the above embodiment, the generation of the pseudo knock is avoided based on the calculation result of the knock retardation amount. However, the present invention is not limited to this, and the premium / regular If the fuel property can be determined based on the amount of retarded amount, the air / fuel ratio correction coefficient ΔA / F is changed to correct the A / F to the lean side when determining the regular state of the retarded side operation. Generation | occurrence | production of a pseudo knock can be avoided.
[0028]
Such a control apparatus for an internal combustion engine further includes the fuel property achieved by the microcomputer 20 that determines the premium / regular fuel property based on the amount of retardation by the knock control means in addition to the above-described embodiment. A determination unit is provided, and the correction control unit performs correction control when the fuel property determination unit determines that the fuel property of the reticular is obtained, and the same effect as the above-described embodiment can be expected.
[0029]
Also, when the cylinders or cylinder groups that are likely to generate pseudo knocks due to differences in intake air amount (intake air amount), A / F, heat sink (cooling of each cylinder by cooling water), etc. for each cylinder of the internal combustion engine, The air-fuel ratio correction coefficient ΔA / F in the above embodiment may be implemented by changing the weight for each cylinder or each cylinder group.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a control device for an internal combustion engine according to an example of an embodiment of the present invention.
FIG. 2 is a flowchart showing a processing procedure for calculating an air-fuel ratio correction coefficient following completion of knock determination in a microcomputer used in the control apparatus for an internal combustion engine according to an example of the embodiment of the present invention; .
FIG. 3 is a characteristic diagram showing the frequency of occurrence of pseudo knock with respect to ignition timing fluctuations in the control apparatus for an internal combustion engine according to an example of the embodiment of the present invention.
FIG. 4 is a characteristic diagram showing the frequency of occurrence of pseudo-knock with respect to A / F fluctuations in the control apparatus for an internal combustion engine according to an example of the embodiment of the present invention.
FIG. 5 is a characteristic diagram showing the frequency of occurrence of pseudo-knock with respect to intake VVT fluctuations in the control apparatus for an internal combustion engine according to an example of the embodiment of the present invention.
FIG. 6 is a diagram showing a difference between a knock signal and a pseudo knock signal under a specific operation condition.
[Explanation of symbols]
10 knock sensor 11 BPF (band pass filter)
12 Peak hold circuit 20 Microcomputer

Claims (2)

  Knock detection means for detecting knock based on the vibration signal waveform generated in the internal combustion engine, and knock control for retarding the ignition timing when the knock detection means detects the knock and for returning the ignition timing to advance when no knock is detected And an air / fuel ratio control means for controlling the air / fuel ratio of the internal combustion engine, and when the retardation amount by the knock control means is larger than a predetermined value, the air / fuel ratio by the air / fuel ratio control means is lean based on the retardation amount. A control device for an internal combustion engine comprising correction control means for performing correction control so as to be on the side.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the correction control means sets the correction amount of the air-fuel ratio by changing it for each cylinder or cylinder group set in advance.

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