JP4500205B2 - Knocking control device for internal combustion engine - Google Patents

Description

  The present invention relates to a knocking control device for an internal combustion engine that determines whether knocking has occurred based on a detection signal output from a knock sensor, and performs knocking countermeasure processing such as retarding ignition timing when the occurrence of knocking is determined. .

In Patent Document 1, as a knock detection device that determines the presence or absence of occurrence of knock based on a detection signal of a knock sensor, the knock determination level is determined based on the detection result of the knock sensor when there is no knock, and the mechanical vibration noise component and the electrical noise component. An apparatus is disclosed in which values are removed.
JP 2000-205096 A

  By the way, when a large current flows through an electric load such as a throttle motor that opens and closes the throttle valve, the ground level fluctuates, and the knock sensor output fluctuates due to the ground level fluctuation or the radiation noise emitted from the electric load. Although knocking does not actually occur, there is a possibility that the occurrence of knocking is erroneously determined and the ignition timing is erroneously retarded.

In particular, when a large current is supplied to the throttle motor to open the throttle valve in response to an acceleration request, if the occurrence of knocking is misjudged and the ignition timing is retarded, the acceleration performance deteriorates. To do.
The present invention has been made in view of the above problems, and provides a knock control device for an internal combustion engine capable of avoiding erroneous determination of occurrence of knocking due to a change in electric current of an electric load and erroneously retarding ignition timing. The purpose is to do.

Therefore, according to the first aspect of the present invention, when the current value of the electric load of the internal combustion engine exceeds the threshold value and the detection signal output from the knock sensor is within a predetermined range, the determination of the occurrence of knocking based on the detection signal is made. Or it was set as the structure which prohibits execution of a knocking corresponding | compatible process.

  According to such a configuration, when the current value of the electrical load exceeds the threshold value and the detection signal output from the knock sensor is within a predetermined range, the detection signal of the knock sensor fluctuates with the current change of the electrical load. Therefore, the determination of knocking occurrence based on the detection signal that fluctuates within the predetermined range is prohibited, or the execution of knocking countermeasure processing such as ignition timing retard is prohibited even if knocking occurrence is determined. To do.

Therefore, it is possible to accurately determine the fluctuation of the detection signal of the knock sensor accompanying the change in the electric load current, and appropriately prohibit the determination of the occurrence of knocking or the knocking handling process.
In the invention according to claim 2, when a transient state of the current value in the electric load of the internal combustion engine is detected within a predetermined period and the detection signal output from the knock sensor is within the predetermined range, The configuration is such that the determination of the occurrence of knocking based on the detection signal or the execution of the knocking handling process is prohibited.

  According to such a configuration, when a transient state of the current value of the electric load is detected, there is a possibility that the detection signal of the knock sensor may fluctuate with the transient change of the current in a predetermined period thereafter. When the detection signal fluctuates within a predetermined range, it can be determined that it is caused by a transient change in the current. Therefore, the determination of the occurrence of knocking is prohibited, or even if the occurrence of knocking is determined, Prohibit execution of knocking processing such as retard.

Therefore, it is possible to accurately determine the fluctuation of the detection signal of the knock sensor accompanying the change in the electric load current, and appropriately prohibit the determination of the occurrence of knocking or the knocking handling process.

Embodiments of the present invention will be described below.
FIG. 1 shows a system configuration of an internal combustion engine in the embodiment.
In FIG. 1, air from an air cleaner 2 is sucked into an internal combustion engine 1 for a vehicle through an intake duct 3, a throttle valve 4 and an intake manifold 5.
The intake air amount of the internal combustion engine 1 is controlled by the opening degree of the throttle valve 4, and the throttle valve 4 is opened and closed by a throttle motor 4a.

Further, fuel is injected from an electromagnetic fuel injection valve 6 provided in the intake manifold 5 at a predetermined timing synchronized with engine rotation.
In the combustion chamber of each cylinder, the air-fuel mixture is ignited and burned by spark ignition by the spark plug 7.
The fuel injection amount and fuel injection timing by the fuel injection valve 6, the ignition timing by the spark plug 7, and the opening / closing drive of the throttle valve 4 by the throttle motor 4a are controlled by an electronic control unit 8 built in the microcomputer.

The electronic control unit 8 receives signals from various sensors.
As the various sensors, an air flow meter 9 is provided in the intake duct 3, whereby the intake air flow rate Q of the internal combustion engine 1 is detected.
Further, a crank angle sensor 10 for detecting the rotation angle of the crankshaft is provided, and the rotation speed Ne of the internal combustion engine 1 is calculated in the electronic control unit 8 based on the detection signal of the crank angle sensor 10.

  Further, a throttle sensor 11 is attached to the throttle valve 4 so that the throttle opening TVO is detected, and an accelerator opening sensor 13 for detecting the depression amount of the accelerator pedal is further provided. The throttle motor 4a is feedback-controlled so that the actual opening detected by the throttle sensor 11 coincides with the target opening set based on the detection result.

A knock sensor 12 is attached to the cylinder block of the internal combustion engine 1. The knock sensor 12 is a sensor that detects knocking vibration by a piezoelectric element, and is a type of sensor in which a ground line is connected to the engine body.
However, the knock sensor 12 may be an isolated type whose ground line is connected to the electronic control unit 8.

Here, the electronic control unit 8 determines the presence / absence of knocking based on the detection signal from the knock sensor 12, and when knocking is determined, retards the ignition timing by the spark plug 7 to eliminate knocking. It is like that.
The flowchart of FIG. 2 shows a reference example of the knocking control.
First, in step S11, it is determined whether or not the detection signal of the knock sensor 12 (hereinafter also referred to as a knock detection signal) fluctuates beyond a predetermined range W.

In this reference example, as shown in FIG. 3, when a large current flows through the throttle motor 4a (electric load) to rapidly increase the throttle opening, the battery voltage fluctuates, so that the ground (GND) level of the engine 1 A difference occurs in the ground (GND) level of the electronic control unit 8, the knock detection signal fluctuates regardless of the occurrence of knocking, and radiation noise is mixed into the sensor output line.

If the occurrence of knocking is erroneously determined based on the fluctuation of the knock detection signal due to a large current flowing through the electric load, the ignition timing is retarded even though knocking has not actually occurred. The drivability of the engine 1 is impaired.
Therefore, it is determined that the fluctuation of the knock detection signal within the predetermined range W is not caused by the occurrence of knocking at least, but may be the fluctuation of the knock detection signal due to the fluctuation of the ground level.

On the other hand, when the fluctuation of the knock detection signal exceeding the predetermined range W has occurred, it is determined that there is a possibility that the knocking has actually occurred.
Therefore, if it is determined in step S11 that the knock detection signal varies within the predetermined range W, the occurrence of knocking is not erroneously determined due to the variation in the knock detection signal due to the ground level variation. Thus, the process proceeds to step S12, and the determination of the occurrence of knocking by analysis of the knock detection signal is prohibited.

On the other hand, if it is determined in step S11 that the knock detection signal has fluctuated beyond the predetermined range W, there is a possibility that knocking has actually occurred, so the process proceeds to step S13 to detect knock. The presence or absence of knocking is determined by analyzing the signal.
Specifically, the knock detection signal is subjected to frequency analysis to extract a frequency component peculiar to knock vibration, and the presence or absence of knocking is determined based on the magnitude of the extracted frequency component.

When it is determined in step S13 whether knocking has occurred, in next step S14, it is determined whether knocking has been determined.
When it is determined that knocking has occurred, the routine proceeds to step S15, where the ignition timing (ignition advance value) by the spark plug 7 is corrected by a predetermined angle to eliminate knocking.
On the other hand, if it is determined in step S14 that knocking has not occurred, the process proceeds to step S16, where the ignition timing is advanced by a predetermined angle, and the ignition timing is advanced as much as possible within a range where knocking does not occur. To.

According to the above configuration, when there is a possibility that the knock detection signal is fluctuated due to the fluctuation of the ground level, it is not judged whether knocking has occurred or not, so that the occurrence of knocking is erroneously judged with the fluctuation of the ground level. Can be avoided.
After determining whether or not knocking has occurred based on the knock detection signal, it is determined whether or not the knock detection signal varies within the predetermined range W, and the knock detection signal varies within the predetermined range W. The ignition timing correction (knocking response process) may be prohibited when the engine is on.

The flowchart of FIG. 4 shows a first embodiment of the knocking control according to the present invention .
In the first embodiment shown in the flowchart of FIG. 4, and exceeds the current command value is the threshold value of the throttle motor 4a, and, when the knock detection signal fluctuates within the predetermined range W, the analysis of the knock detection signal It is characterized in that knocking detection by is prohibited.
That is, in step S21, it is determined whether or not the current command value of the throttle motor 4a exceeds a threshold value.

As shown in FIG. 5, the current command value of the throttle motor 4a exceeds the threshold when the throttle valve 4 is requested to open, and a large current flows through the throttle motor 4a, whereby the ground level of the engine 1 fluctuates. .
Therefore, the determination as to whether or not the current command value of the throttle motor 4a exceeds the threshold value determines whether or not the ground level of the engine 1 varies.

If the current command value of the throttle motor 4a does not exceed the threshold value, it is determined that the ground level of the engine 1 does not fluctuate and the knock detection signal indicates the actual knocking vibration, so the process proceeds to step S24. Then, frequency analysis of the knock detection signal is performed.
On the other hand, if the current command value of the throttle motor 4a exceeds the threshold value, it is assumed that the ground level fluctuates, so the process proceeds to step S22.

In step S22, as in step S11, it is determined whether or not the knock detection signal fluctuates beyond a predetermined range W.
When it is determined in step S22 that the knock detection signal varies within the predetermined range W, it is determined that the variation is caused by a ground level variation caused by a large current flowing through the throttle motor 4a. Then, the process proceeds to step S23, and the determination of the occurrence of knocking by analysis of the knock detection signal is prohibited.

Further, when it is determined in step S22 that the knock detection signal has fluctuated beyond the predetermined range W, it is determined that there is a possibility that knocking has actually occurred even if the ground level has fluctuated. Then, the process proceeds to step S24, and the occurrence of knocking is determined by analyzing the knock detection signal.
The analysis result in step S24 is determined in step S25. If knocking is determined to occur, the process proceeds to step S26 to retard the ignition timing. If it is determined that knocking has not occurred, the process proceeds to step S27 and ignition is performed. Correct the timing.

  According to the above-described embodiment, it is determined whether a large current is flowing through the throttle motor 4a that causes a ground level fluctuation, and the knock detection signal is within a predetermined range W while a large current is flowing through the throttle motor 4a. If it fluctuates at, it is determined that the fluctuation is caused by fluctuations in the ground level. Therefore, it is possible to more accurately determine the state in which the knock detection signal fluctuates due to fluctuations in the ground level, and to determine the occurrence of excessive knocking. Can be avoided.

In addition, when a large current flows through the throttle motor 4a, in other words, when the throttle valve 4 is opened, erroneous determination of knocking is avoided, thereby preventing deterioration in acceleration performance. it can.
Incidentally, in the first embodiment, after determining the occurrence of knocking based on the knock detection signal, the exceeding current command value of the throttle motor 4a is a threshold, and change the knocking detection signal is within the predetermined range W It may be determined whether or not ignition timing correction (knocking response processing) is prohibited.

The flowchart of FIG. 6 shows 2nd Embodiment of the knocking control which concerns on this invention .
In the second embodiment shown in the flowchart of FIG. 6, the change amount ΔAPO per unit time of the accelerator opening is within a predetermined time after the predetermined amount or more, and the knock detection signal fluctuates within the predetermined range W. In this case, knocking detection by analyzing the knock detection signal is prohibited.

As shown in FIG. 7, when the accelerator opening changes rapidly, a large current flows through the throttle motor 4a to change the opening of the throttle valve 4 correspondingly, and the ground level of the engine 1 fluctuates. Variation occurs in the knock detection signal.
Therefore, in step S31, after the change amount ΔAPO per unit time of the accelerator opening becomes equal to or larger than a predetermined value, in other words, whether the current value transient state in the electric load is detected and then within the predetermined time t1. Determine whether or not.

If the change amount ΔAPO is within a predetermined time t1 after the change amount ΔAPO becomes equal to or greater than a predetermined value, the condition is such that the knock detection signal may change due to the change in the ground level, and the process proceeds to step S32.
In step S32, as in step S11, it is determined whether or not the knock detection signal fluctuates beyond a predetermined range W.

When it is determined in step S32 that the knock detection signal is fluctuating within the predetermined range W, it is determined that the fluctuation of the knock detection signal at that time is due to the fluctuation of the ground level, and the process proceeds to step S33. Going forward, the determination of the occurrence of knocking by analyzing the knock detection signal is prohibited.
On the other hand, when it is determined in step S32 that the knock detection signal has fluctuated beyond the predetermined range W, it is determined that there is a possibility that knocking has actually occurred even if the ground level has fluctuated. Then, the process proceeds to step S34 to determine whether knocking has occurred by analyzing the knock detection signal.

If it is determined in step S31 that the change ΔAPO is not within the predetermined time t1 after the change amount ΔAPO becomes equal to or greater than a predetermined value, it is determined that there is no fluctuation in the knock detection signal due to the fluctuation in the ground level, and the process proceeds to step S34. The occurrence of knocking is determined by analyzing the knock detection signal.
The analysis result in step S34 is determined in step S35. If knocking is determined to occur, the process proceeds to step S36 to retard the ignition timing. If it is determined that knocking has not occurred, the process proceeds to step S37 and ignition is performed. Correct the timing.

  According to the above embodiment, the condition that a large current flows through the throttle motor 4a that causes the ground level fluctuation is determined from the change amount ΔAPO of the accelerator opening per unit time, and the large current flows through the throttle motor 4a. If the knock detection signal fluctuates within the predetermined range W under the condition of the condition, it is determined that the fluctuation is caused by the fluctuation of the ground level. This makes it possible to accurately determine and avoid prohibiting excessive determination of occurrence of knocking.

In the second embodiment as well, after determining whether or not knocking has occurred based on the knock detection signal, the change ΔAPO is within a predetermined time t1 after the change ΔAPO becomes equal to or greater than a predetermined value, and the knocking detection signal is It may be determined whether or not the fluctuation is within a predetermined range W, and ignition timing correction (knocking response processing) may be prohibited.
In the first and second embodiments , the throttle motor 4a is shown as an example of the electric load that causes a large current to flow and the ground level of the engine 1 varies. However, the electric load is not limited to the throttle motor 4a. Other electric loads such as a variable valve mechanism using a type actuator may be used.

Further, when a current value and / or a transient state of a current value of a plurality of electric loads is detected and a large current that fluctuates the ground level in any of the electric loads is in a state or condition in which knocking occurs, determination of occurrence of knocking is made. Or it can be set as the structure which prohibits execution of the said knocking corresponding | compatible process.
Furthermore, it can be configured that the determination of the occurrence of knocking or the execution of the knocking handling process is prohibited in a state where currents for a plurality of electric loads change simultaneously.

  Further, the predetermined range W is learned based on a knock detection signal in a state or condition in which a large current flows through an electric load, and when the change amount ΔAPO becomes equal to or greater than a predetermined value, the determination of the occurrence of knocking or the processing for knocking is performed. The time t1 during which execution is prohibited can be a period from when the amount of change ΔAPO becomes equal to or greater than a predetermined value until the knock detection signal shows a predetermined attenuation.

Further, in the above-described embodiment, the knocking countermeasure process is the correction of the ignition timing, but the invention is not limited to the correction of the ignition timing.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) In the knocking control device for an internal combustion engine according to claim 1 or 2 ,
A knocking control device for an internal combustion engine, wherein the electric load is a throttle motor that opens and closes a throttle valve.

According to such a configuration, even if the knock sensor output fluctuates due to a fluctuation in the ground level due to a large current flowing through the throttle motor and a fluctuation in the ground level or radiation noise generated from an electric load, the occurrence of knocking is erroneously determined. In addition, it is possible to prevent the knocking handling process from being performed erroneously.
(B) In the knocking control device for an internal combustion engine according to claim 2 ,
The electric load is controlled based on the accelerator opening, and is a throttle motor that drives the throttle valve to open and close, and a state where the amount of change in the accelerator opening is greater than or equal to a predetermined value is detected as a transient state of the current value in the throttle motor An internal combustion engine knocking control device.

According to such a configuration, in order to change the throttle valve opening corresponding to the change in the accelerator opening, in the state where a large current flows through the throttle motor and the ground level fluctuates, the determination of knocking occurrence or knocking based on the knock detection signal is performed. Prohibit execution of corresponding processing.
(C) The knocking control device for an internal combustion engine according to claim 1 or 2 ,
A knocking control device for an internal combustion engine, wherein a ground line of the knock sensor is connected to the internal combustion engine body.

  According to such a configuration, a large current flows through the electric load and the battery voltage fluctuates, resulting in a difference between the engine ground level and the control unit ground level, which causes the detection signal of the knock sensor to fluctuate apparently. However, it is possible to prevent the occurrence of knocking from being erroneously determined, and the knocking handling process from being erroneously performed.

1 is a system diagram of a vehicle internal combustion engine in an embodiment of the present invention. The flowchart which shows the reference example of knocking control. The time chart which shows the control characteristic in the said 1st Embodiment. The flowchart which shows 1st Embodiment of knocking control. The time chart which shows the control characteristic in the said 1st Embodiment. The flowchart which shows 2nd Embodiment of knocking control. The time chart which shows the control characteristic in the said 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 4 ... Throttle valve, 4a ... Throttle motor, 6 ... Fuel injection valve, 7 ... Spark plug, 8 ... Electronic control unit, 9 ... Air flow meter, 10 ... Crank angle sensor, 11 ... Throttle sensor, 12 ... Knock sensor, 13 ... accelerator opening sensor

Claims (2)

In a knock control device for an internal combustion engine that determines whether or not knocking has occurred based on a detection signal output from a knock sensor that detects knocking vibrations of the internal combustion engine, and performs predetermined knocking handling processing when it is determined that knocking has occurred ,
When the current value of the electric load of the internal combustion engine exceeds a threshold and the detection signal output from the knock sensor is within a predetermined range, determination of occurrence of knocking based on the detection signal or execution of the knocking response process A knocking control device for an internal combustion engine characterized by prohibiting the engine. In a knock control device for an internal combustion engine that determines whether or not knocking has occurred based on a detection signal output from a knock sensor that detects knocking vibrations of the internal combustion engine, and performs predetermined knocking handling processing when it is determined that knocking has occurred ,
Knocking based on the detection signal when a transient state of the current value in the electric load of the internal combustion engine is detected within a predetermined period and the detection signal output from the knock sensor is within a predetermined range A knock control apparatus for an internal combustion engine, wherein the determination of occurrence or the execution of the knocking response process is prohibited.

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