JP2000073925A - Knock control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a knock control device capable of controlling ignition timing to the optimum value in any environmental condition or operation condition of an internal combustion engine. SOLUTION: By defining a ratio of increase of knock sound strength when ignition timing is gradually advanced from ignition timing when knock starts (a trace knock point) as knock sensitivity, knock sensitivity is changed based on changes in environmental conditions such as temperature, atmospheric pressure and humidity, and engine conditions such as an engine rotation number, cooling water temperature, an air-fuel ratio, therefore knock sensitivity is determined by a knock sensitivity determination means 16 based on a knock level determined by a knocking detection means 13 capable of detecting generation frequency and strength of knocking and a knock level determination means 15, and the determined knock sensitivity is reflected on decision of ignition timing in an ignition timing determination means 18 to change ignition timing delay speed or advance speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knock control device for preventing occurrence of knocking in a spark ignition type internal combustion engine such as a gasoline engine.

[0002]

2. Description of the Related Art In a conventional ignition timing control of a gasoline engine as described in Japanese Patent Application Laid-Open No. Hei 8-1150, the ignition timing is set at a knock start point (trace knock point) in consideration of a balance between knock characteristics and torque characteristics. , Or TK point). This is generally called KCS (Knock Control System) control. Here, conventional general KCS control will be described with reference to FIGS. FIG. 9 shows an outline of the KCS control at a moment, and FIG. 10 shows an outline of the KCS control over a long period of time. In the case of the ignition timing control using the knock sensor, a fixed knock determination period is provided after the ignition timing as shown in FIG.
The knock intensity and frequency are measured from the D-converted value. next,
A knock level is calculated from the knock intensity and the frequency. The magnitude of the knock level is determined by the map value from the intensity and frequency of the knock sound.

In the KCS control, as shown in FIG. 10, the ignition timing is changed according to the calculated knock level. That is, if the knock level is equal to or less than the allowable level, the ignition timing is advanced, and if the knock level exceeds the allowable level, the ignition timing is delayed according to the knock level. In this way, the ignition timing is constantly changed while searching for the trace knock point (TK point) at which knock starts. As a result, the ignition timing is always near the TK point, and a high engine torque can be maintained while the knock level is below the allowable level.

[0004] However, in the conventional KCS control, the advance and retard speeds for shifting the ignition timing to the TK point are set to a constant value, or set to a value corresponding one-to-one to the knock level. Open loop control was performed.

[0005]

Problems of the conventional KCS control will be described with reference to FIGS. If the rate of increase in knock sound intensity when the ignition timing is gradually advanced from the TK point is defined as "knock sensitivity", FIG.
As shown in (d), the knock sensitivity also changes due to changes in environmental conditions such as air temperature, atmospheric pressure, or humidity, and in engine conditions such as engine speed and cooling water temperature. As shown in FIG. 12, even in the same engine, the knock level changes linearly due to a change in the ignition timing, which is one of the engine conditions, but the knock sensitivity, which is the inclination angle, changes according to the environmental conditions as described above. I do.

Accordingly, when the ignition timing is controlled only in response to the knock level under the condition where the knock sensitivity is different as in the conventional KCS control, the change sufficiently responds to changes in environmental conditions and engine conditions. If the ignition timing is excessively advanced and the knock noise becomes larger than the target level, or if the ignition timing is excessively retarded and the knock noise becomes smaller than the target level, the engine torque is also reduced. There was a problem that the size was reduced (see FIG. 13). Further, there is a problem that the control amplitude of the advance / retard of the ignition timing becomes large and drivability deteriorates (see FIG. 14). FIG. 15 shows a three-dimensional display of the combination of FIG. 12, FIG. 13, and FIG.

As described above, in the case of the conventional KCS control in which the ignition timing is controlled only for the knock level, it is difficult to maintain the accuracy of the knock level control when the knock sensitivity changes. The present invention provides a knock control device capable of always controlling the internal combustion engine to an optimum ignition timing under any environmental conditions or operating conditions of the engine with respect to such problems of the related art. It is intended to be.

[0008]

According to the present invention, there is provided a knock control device for an internal combustion engine as described in the claims as means for solving the above-mentioned problems.

The present invention relates to a method for controlling the temperature, pressure,
Alternatively, environmental conditions such as humidity, operating conditions of the engine (engine conditions) such as engine speed, cooling water temperature, air-fuel ratio, etc., or various related factors such as intake pressure, intake temperature, lubricating oil temperature. Focusing on the fact that the knock sensitivity of the engine (slope of the knock level with respect to the ignition timing) changes due to the change in the engine conditions, the ignition timing is advanced by using knocking detection means capable of detecting the frequency and intensity of knocking. A knock level increase ratio with respect to the angular amount is calculated as a knock sensitivity, and the calculated knock sensitivity is reflected in the control of the knock control device to perform the KCS control.

In this case, the control constant changed according to the knock sensitivity can be at least one of the advance speed and the retard speed of the ignition timing. Further, the range of the knock level for determining the magnitude of the knock can be changed based on the calculated knock sensitivity. further,
The knock sensitivity to the operating condition of the internal combustion engine is stored, and the feedforward control is executed based on the stored knock sensitivity, or the knock sensitivity stored for each environmental condition and operating condition of the engine is actually stored. It is also possible to configure so as to correct and update according to the knock sensitivity. In addition, regarding the change in knock sensitivity with respect to changes in environmental conditions and operating conditions, the knock detection means is degraded by comparing the current knock sensitivity with a map value that stores an existing value or a past learned value according to the engine characteristics. It may be configured to make a determination.

As described above, according to the present invention, it is possible to reduce the knock level while suppressing a decrease in torque, regardless of changes in environmental conditions and engine conditions (engine operating conditions). Deterioration of the means can also be detected.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) The structure and operation of a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a gasoline engine 100 to which the control of the first embodiment is executed. 1, the gasoline engine 100 includes a knock sensor 1, a rotation angle sensor 2, an igniter 3, an intake pressure sensor 4, an intake temperature sensor 5, a water temperature sensor 6, an electronic control unit (ECU) 7, and the like. It consists of parts. In the first embodiment, the control constant that changes according to the knock sensitivity is the retard speed,
The control is performed by the ECU 7 so that the retard speed increases as the knock sensitivity increases.

The optimum retardation speed for the knock sensitivity is stored in advance in a memory (not shown) in the ECU 7 as a map value, and the map value is updated with the actually detected knock sensitivity. In the first embodiment, since the advance speed is unchanged, the knock level can be reduced without reducing the advance response. Therefore, the first
The embodiment is suitable for a case where the movement of the TK point is severe, such as in a city where the change in the engine load and the intake air amount is large.

FIG. 2 is a block diagram showing a control operation procedure of the first embodiment. First, from the information of the environmental condition detecting means 11 (intake temperature sensor 5 and water temperature sensor 6) and the engine condition detecting means 12 (rotation angle sensor 2 and intake pressure sensor 4),
A corresponding TK point is obtained from the TK point map 14. Next, the ignition timing determination means 18 (ECU
7) determines the rough ignition timing. The ignition timing switching means 19 (ECU 7 and igniter 3) executes the ignition at this ignition timing by feedforward control.

Immediately after that, within a certain period, knock detection means 13 (knock sensor 1) detects knock vibration and determines knock level determination means 1 based on knock intensity and knock frequency.
5 calculates the current knock level. In this example, the knock level is divided into “large”, “medium”, “small”, and “none”, the trace knock is “small”, and the allowable knock level is “medium”. The ignition timing is sequentially changed by the feedback control through the line 21 according to the current knock level recognized as described above. FIG. 3 shows how the ignition timing is controlled. That is, if the knock level is "none", the ignition timing is advanced by the advance speed 31. In other cases, the ignition timing is retarded by the retard speed 32 according to the height of the knock level.

In the conventional KCS control, the retard speed 32
Was determined on a one-to-one basis according to the knock level,
In the first embodiment of the present invention, the knock level is further reduced by adding a control block that takes knock sensitivity into consideration, such as a portion surrounded by a broken line in FIG. Hereinafter, FIG. 2 will be described in more detail. In the block diagram of FIG. 2, the portions in which the knock sensitivity is taken into account are the knock sensitivity determination means of the block 16 and the knock sensitivity → retarded speed map of the block 17. Since the knock sensitivity is a rate of increase of the knock level with respect to the ignition timing advance, it is calculated by the knock sensitivity determination means 16 using information of the knock level determination means 15 and the engine condition detection means 12. This is entered into the knock sensitivity → delay angle speed map 17, and the delay speed 32 that is roughly adapted to the knock sensitivity is determined through the line 23 by feedforward control.
Further, the retard speed 32 is successively updated by feedback control through the line 22 based on the actually measured knock sensitivity by the knock sensitivity determination means 16.

Knock sensitivity → retarded speed map 1
As shown in FIG. 4, the optimum retardation speed at which the average value of the knock level within a predetermined time is equal to or less than the allowable level is stored in advance in the knock sensitivity, as shown in FIG. , And is updated by the knock sensitivity and the retard speed of the actually measured values that change successively. In the first embodiment, the ignition timing is determined by the above control.

Next, the effect of the KCS control according to the first embodiment will be described with reference to FIGS. FIG. 5 shows a control result of the conventional KCS control when the knock sensitivities are different. Although the amount of advance is the same, the greater the knock sensitivity, the greater the increase in the knock level. Therefore, if the knock sensitivity is high at the peak of the ignition timing shown at 5a in FIG. 5, the knock level may overshoot and greatly exceed the allowable level.

On the other hand, in the first embodiment of the present invention, as shown in the following Table 1, by increasing the retardation speed in accordance with the magnitude of the knock sensitivity, 5 in FIG.
The knock level is reduced by reducing the frequency of reaching the peak as seen in the part a.

[0020]

[Table 1]

FIGS. 6 to 8 show the outline of the control according to the first embodiment.
Shown in In this case, FIG. 8 shows a combination of FIG. 6 showing a change in ignition timing and FIG. 7 showing a change in knock sensitivity. In the first embodiment, in order to maintain the responsiveness to the fluctuation of the TK point, the advance angle is set to a constant value as in the prior art. However, the retarding speed is controlled such that the retarding speed increases as the knock sensitivity increases, as shown in FIG. As a result, once knock is recognized, the ignition timing is controlled to a more retarded side, so that the time until knock occurs again becomes longer. As a result, as shown in FIGS. 6 and 7, the central value of the ignition timing is on the retard side, and the knock level can be suppressed to a small value.

(Second Embodiment) The structure, operation and effects of a second embodiment of the present invention are shown in Table 2 and FIGS.
This will be described with reference to FIG. Also in the second embodiment, the configuration of the gasoline engine 100 to be controlled is shown in FIG. 1 as in the first embodiment. FIG.
Most of the procedure of the control operation shown in FIG. 7 is the same as that of the first embodiment (FIG. 2), but the knocking sensitivity → advance / retard speed map of the block 17a has optimal advance and retard speeds. Is different from the block 17 of the first embodiment.

In the second embodiment, the control constants that change in accordance with the knock sensitivity are both the advance speed and the retard speed. As shown in Table 2, the advance speed and the retard speed are reduced as the knock sensitivity increases. As a result, it is possible to suppress fluctuations in the knock level and the engine torque irrespective of the change in the knock sensitivity.

[0024]

[Table 2]

FIG. 1 shows the effect of the KCS control according to the second embodiment.
7 to 19 are shown. Also in this case, FIG. 19 shows a combination of FIG. 17 showing a change in knock sensitivity and FIG. 18 showing a change in ignition timing. When the knock sensitivity changes as shown in FIG. 17 depending on the environmental condition and the engine condition (engine operating condition), as shown in FIG. 19, the KCS control curve matches at an arbitrary knock sensitivity on the knock level / time plane. In this way, the advance and retard speeds are changed. This is the ignition timing / time plane shown in FIG.
As can be seen from FIG. 2, the knocking sensitivity is increased by appropriately reducing the advance and retard speeds.
Further, in this case, since the center value of the ignition timing does not move to the retard side, the overall torque does not decrease.

However, the operating condition of the engine changes,
If the control of the second embodiment is performed when load fluctuation frequently occurs such that the moving speed at the TK point becomes higher than the control response speed of the ignition timing, the ignition timing remains on the advance side where the knock level is large. This is not preferable because some cases occur. Therefore, when the engine load is monitored by the engine condition detecting means 12 and the engine load changes to an operating state in which the engine load changes frequently, the control of the first embodiment described above or the control of the third embodiment described later is performed. It is desirable to move to.

Third Embodiment The configuration and operation of a third embodiment of the present invention will be described with reference to Table 3 and FIGS. Gasoline engine 10 to be controlled according to the third embodiment
The configuration of 0 is the same as that of the first embodiment shown in FIG. The procedure of the control operation shown in FIG. 20 is almost the same as that of the first embodiment shown in FIG. 2, but the knock sensitivity → knock level correction map of the block 17b shows the optimum knock level correction. The difference from the first and second embodiments is that the values are stored.

In the third embodiment, the control constant that changes according to the knock sensitivity is a knock level that determines the magnitude of the knock sound. The KCS control of the third embodiment is based on the engine 100
It is suitable for a case where the movement of the TK point is severe, such as running in a city where the load of the vehicle and the amount of intake air change drastically.

FIG. 2 shows the effect of the KCS control according to the third embodiment.
This will be described with reference to FIGS. FIG. 2 showing conventional control
In No. 1, the knock level does not change with respect to the intensity and frequency of the knock sound even if the knock sensitivity changes. Therefore, when the ignition timing is advanced, as in the case of the normal knock sensitivity, an excessive advance may occur and the knock noise may increase. That is, at the peak of the ignition timing as indicated by a portion 21a in FIG. 21, the knock sound exceeds the allowable knock sound level and overshoots.

Therefore, in a third embodiment of the present invention,
As shown in Table 3, the range of the knock level is corrected according to the knock sensitivity. The outline of the control is shown in FIGS. FIG. 24 shows a combination of FIG. 22 showing a change in knock sensitivity and FIG. 23 showing a change in ignition timing. When the knock sensitivity increases as shown in FIG. 22 due to environmental conditions and engine conditions, the range of the knock level is reduced. That is, the range of the knock level with respect to the knock sound is reduced in anticipation of the excessive advance at the peak of the ignition timing. Thus, the peak of the ignition timing does not exceed the allowable level (see FIGS. 22 and 24), and the knocking noise can be reduced as a whole.

[0031]

[Table 3]

(Fourth Embodiment) The structure, operation, and effects of a fourth embodiment of the present invention will be described with reference to FIGS. 25 to 31 in addition to FIG. Also in the case of the fourth embodiment, the configuration of the gasoline engine 100 to be controlled is the same as that of the first embodiment shown in FIG. Most of the operation procedure is the same as that of the first embodiment shown in FIG. 2, but in the fourth embodiment, as shown as a block 24 in FIG. Is different from the first embodiment and the like.

In the fourth embodiment, the knock sensitivity map 17c is compared with the actually measured knock sensitivity to detect the deterioration of the knock detection means 13 from the difference between these values. Generally, various sensors are used as knock detection means. In the fourth embodiment, a knock sensor 40 of a resonance type as shown in FIG. 26 is used. When using another type of sensor as knock detection means 13, the deterioration determination means 24 may change the algorithm according to the characteristics of the sensor.

The resonance type knock sensor 40 is provided with a vibrator 41 that resonates in the knocking frequency band of the engine. The vibrator 41 causes the piezoelectric element 42 to vibrate so that a peak signal is generated at the knocking frequency of the engine. Occurs. FIG. 27 shows the characteristics of the vibration frequency and the signal output. Here, as a degradation example of the resonance type knock sensor 40, a case where the resonance frequency deviates from the knocking frequency of the engine due to degradation of the piezoelectric element 42, breakage of the vibrator 41, and the like will be considered.

First, when the piezoelectric element 42 deteriorates and the noise increases as shown in FIG. 28 or the output voltage decreases as shown in FIG. 29, the knock level determining means 15 calculates the knock level to be small. As a result, the knock sensitivity is lower than in the normal state. The deterioration of knock sensor 40 is determined by comparing the actually measured knock sensitivity with the value of knock sensitivity map 17c.

Next, as shown in FIGS. 30 and 31,
When the resonance frequency of knock sensor 40 deviates from the knocking frequency of the engine, knock sensor 40 does not recognize much vibration even if engine 100 is knocked. As a result, the ignition timing is advanced beyond the TK point, so that the vibration due to knocking increases. At this time, the intensity of the frequency component resonating with the knock sensor 40 also increases,
Ultimately, the knock is recognized and the advance of the ignition timing is stopped. However, the TK point and the knock sensitivity recognized by knock sensor 40 are different from the map values of the knock sensitivity. In the fourth embodiment, the difference is compared to determine the deterioration of the knock sensor. Generally speaking, the deterioration of the knock detection means is determined using the knock sensitivity.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view conceptually showing a configuration of a gasoline engine as a control object common to each embodiment.

FIG. 2 is a control block diagram of the first embodiment.

FIG. 3 is a diagram conceptually showing the operation of the KCS control of the first embodiment.

FIG. 4 is a diagram showing a map of an optimum retardation speed with respect to knock sensitivity.

FIG. 5 is a diagram showing a change in knock level with respect to a change in knock sensitivity due to conventional control.

FIG. 6 is a diagram showing a change in ignition timing in the first embodiment.

FIG. 7 is a diagram showing a change in knock sensitivity in the first embodiment.

FIG. 8 is a three-dimensional diagram showing a relationship among parameters in the first embodiment.

FIG. 9 is a conceptual diagram showing an instantaneous operation of KCS control.

FIG. 10 is a conceptual diagram showing the operation of the KCS control as viewed for a longer time than in FIG. 9;

FIGS. 11A to 11D are diagrams illustrating changes in knock sensitivity with respect to changes in various environmental conditions and engine conditions (engine operating conditions).

FIG. 12 is a diagram showing a change in knock sensitivity due to conventional control.

FIG. 13 is a diagram showing a change in knock level due to conventional control.

FIG. 14 is a diagram showing a change in ignition timing by conventional control.

FIG. 15 shows parameters (ignition timing,
FIG. 3 is a three-dimensional diagram showing a relationship between knock level and time).

FIG. 16 is a control block diagram of the second embodiment.

FIG. 17 is a diagram showing a change in knock sensitivity in the second embodiment.

FIG. 18 is a diagram showing a change in ignition timing in the second embodiment.

FIG. 19 is a three-dimensional diagram showing a relationship among parameters in the second embodiment.

FIG. 20 is a control block diagram of a third embodiment.

FIG. 21 is a diagram showing a change in knock level with respect to a change in knock sensitivity due to conventional control.

FIG. 22 is a diagram showing a change in knock sensitivity in the third embodiment.

FIG. 23 is a diagram showing a change in ignition timing in the third embodiment.

FIG. 24 is a three-dimensional diagram showing a relationship between parameters in the third embodiment.

FIG. 25 is a control block diagram of a fourth embodiment.

FIG. 26 is a cross-sectional view showing a configuration of a resonance knock sensor.

FIG. 27 is a diagram illustrating output characteristics of a resonance knock sensor.

FIG. 28 is a diagram showing deterioration of a piezoelectric element.

FIG. 29 is a diagram showing a change in knock sensitivity due to deterioration of a piezoelectric element.

FIG. 30 is a diagram showing a shift of a resonance point due to deterioration of a piezoelectric element.

FIG. 31 is a diagram showing a change in knock sensitivity due to deterioration of a piezoelectric element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 knock sensor 2 rotation angle sensor 3 igniter 4 intake pressure sensor 5 intake temperature sensor 6 cooling water temperature sensor 7 electronic control unit (ECU) 40 resonance type knock sensor 41 oscillator 42 piezoelectric Element 100: gasoline engine

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Osamu Fujishiro 14 Iwatani, Shimowasukamachi, Nishio City, Aichi Prefecture Inside the Japan Auto Parts Research Institute (72) Inventor Tokio Obama 14 Iwatani, Shimotsukamachi, Nishio City, Aichi Prefecture Stock Inside the Japan Auto Parts Research Institute (72) Inventor Seiko Watanabe 14 Iwatani, Shimoba Kakucho, Nishio City, Aichi Prefecture Inside the Japan Auto Parts Research Institute (72) Inventor Takehiko Hirose 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto (72) Inventor Takahiro Nishigaki 1 Toyota Town, Toyota City, Aichi F-term (reference) 3G022 BA01 CA09 DA01 DA02 DA04 EA02 FA03 FA04 FA06 FA07 FA08 FA10 GA00 GA07 GA09 GA11 GA13 3G084 BA17 CA04 DA22 DA27 DA38 EA00 EA08 EA11 EB02 EB08 EB11 EB13 EC02 EC03 EC04 FA00 FA01 FA02 FA11 FA25 FA26

Claims (6)

[Claims] 1. A knocking detection means which is applied to a spark ignition type internal combustion engine and is capable of detecting knocking occurrence frequency and knocking intensity, and knocking based on the detected knocking occurrence frequency and knocking intensity. Knock level determining means for determining the level, knock sensitivity determining means for calculating a rate of increase of the knock level with respect to the advance amount of the ignition timing as knock sensitivity, and by changing a control constant according to the calculated knock sensitivity. A knock control device comprising: ignition timing determining means for determining an ignition timing capable of avoiding knocking; and ignition timing switching means for switching an ignition timing according to a command from the ignition timing determining means. 2. The knock control device according to claim 1, wherein the control constant changed according to the knock sensitivity is at least one of an advance speed and a retard speed of the ignition timing. 3. The knock control device according to claim 1, wherein a range of a knock level for judging a magnitude of knock is changed based on the calculated knock sensitivity. 4. The method according to claim 1, wherein
A knock sensitivity to an environmental condition including at least one of temperature, pressure, and humidity and an operating condition of the internal combustion engine including at least one of intake pressure, intake temperature, oil water temperature, and air-fuel ratio is stored and stored. A knock control device configured to execute feedforward control based on the knock sensitivity that has been performed. 5. The knock sensitivity according to claim 4, wherein the knock sensitivity is stored for each of environmental conditions and operating conditions of the internal combustion engine.
A knock control device characterized in that it is configured to update by correcting with an actual knock sensitivity. 6. A device according to claim 5, further comprising means for comparing the knock sensitivity stored for each environmental condition and operating condition of the internal combustion engine with an actual knock sensitivity to determine deterioration of the knock detection means. A knock control device.