JPS63314369A - Knocking control device for engine - Google Patents

Abstract

PURPOSE:To improve the reliability of anti-knock performance of an engine irrespective of aged deterioration thereof by changing an output value of a correcting means for correcting a combustion condition control signal in such a manner as to suppress knocking more as the aged deterioration of the engine becomes greater. CONSTITUTION:When knocking of an engine is detected by a knocking detecting means A, a control signal of a combustion condition control means B is corrected by a correcting means C in such a manner as to suppress the knocking. IN such a knocking control device suppressing the knocking upon detection of the knocking, an aged deterioration detecting means D is provided to detect aged deterioration of the engine. An output signal from the aged deterioration detecting means D is input to a knocking suppression degree changing means E so as to increase a knocking suppression degree as the aged deterioration of the engine becomes greater.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an engine knock control device.

(Prior art) In a gasoline engine, a normal flame spreads from the spark plug and burns sequentially to every corner of the combustion chamber, but as this normal flame progresses, the unburned part becomes hot due to adiabatic compression and self-ignites. and may cause knocking. Since this knocking damages the engine and increases heat loss, etc., various knocking control devices have been developed to prevent knocking. Such a knocking control device includes, for example, Japanese Patent Application Laid-Open No. 58-12646.
As shown in Publication No. 7, there are devices that avoid knocking by retarding the ignition timing, and such knocking control devices generally include a knocking detection means that detects knocking and a control that suppresses knocking. The combustion state control means includes a combustion state control means that outputs a signal, and a correction means that corrects a control signal of the combustion state control means so as to suppress knocking when knocking is detected.

As a result, even if knocking occurs, knocking can be suppressed at any time.

(Problem to be Solved by the Invention) However, in a vehicle, as changes over time such as mileage progress, the deterioration of the engine progresses. If the combustion state control means outputs a predetermined control signal depending on the knocking state regardless of the change over time, the predetermined control signal is generally set based on the initial state of the engine. Therefore, an engine that has deteriorated over time is more likely to be damaged by knocking, and its reliability in terms of knock resistance becomes low.

The present invention has been made in view of the above circumstances, and its purpose is to improve the reliability of the engine's knock resistance regardless of changes over time.

(Means and operations for solving the problem) In order to achieve the first objective, the present invention includes a knocking detection means for detecting knocking, as shown in FIG.

Combustion pattern 79 that outputs a control signal to suppress no/king
, an engine knock control device comprising: a control means; and a correction means for correcting a control signal of the combustion state control means so as to suppress knocking when knocking is detected, the engine knocking control device detecting a change over time in the engine. The engine is configured to include: a temporal change detecting means; and a knocking suppression degree changing means for changing the output value of the correcting means in a direction in which the degree of knocking suppression increases as the temporal change of the engine increases.

1- With the configuration described above, as the engine changes over time, the output value of the first correction stage is changed in a direction that increases the degree of knocking suppression. Even if the value is large, linking can be suppressed by an appropriate control signal corresponding to the value.

(Embodiments) Hereinafter, five embodiments of the present invention will be described based on the attached drawings.

In FIG. 2, l is a 4-cycle reciprocating type engine body with a set of nuts, and as is known, this engine body 1 has a combustion chamber 5 defined by a cylinder block 2, a cylinder head 3, and a piston 4. An intake boat 6 and an exhaust boat 7 are opened into the combustion chamber 5. The intake valve 8 or the exhaust valve 9 disposed on the intake/exhaust boat 6.7 is connected to a rocker arm 11 (the rocker arm of the intake valve 8 is The gates are opened and closed at well-known timings via paths (as shown in the figure). A spark plug 12 is arranged in the combustion chamber 5, and an intake pipe 13 is connected to the intake boat 6.
From the 1-stream side to the downstream side, the air cleaner 1
4, an air flow meter 15, a throttle valve 16, and a fuel injection valve 17 are arranged.

Reference numeral 21 in FIG. 2 is a control unit constituted by, for example, a microcomputer, and this control unit / h 2
1, each signal from the sensors 22 to 27 is input manually.

To explain each of these sensors 22 to 27 in turn, the sensor 22 detects the intake negative pressure in the throttle valve 16-door flow, that is, the engine load.
Reference numeral 3 designates a seven-socket sensor that is provided, for example, in the cylinder block 2 and serves as knocking detection means for detecting knocking (combustion state). Further, the sensor 24 is for detecting the engine rotation speed, and the sensor 25 is a mileage detecting sensor serving as a temporal change detecting means for detecting a temporal change in the engine.

On the other hand, the control unit 21 outputs a control signal to the igniter 31. As is well known, this igniter 31 interrupts the primary current of the ignition coil 32 at a timing corresponding to the ignition timing signal from the control unit 21, and the secondary current generated due to the interruption of this secondary current. The high voltage of
is supplied to the spark plug 12 via the spark plug 12 for ignition.

The control unit optimally controls the engine by outputting a predetermined control signal depending on the knocking state and changing the control signal in response to changes in the engine over time. A control example will be described with reference to the flowcharts shown in FIGS. 3 and 4, in which the retard angle (retard amount), the turning determination level, and the ignition timing retard control time are used. In this flowchart, the flag indicates whether or not the ignition timing is within the retard control period. When the flag = 1, it means that the ignition timing is within the retard control period, and the flag = 0. When , it means that the ignition timing is outside the retard control period, that is, the retard control is not being performed. The flag T1 indicates whether or not the elapsed time t from the start of the retard control of the ignition timing is in the range 0≦t≦a. When the flag TI=0, it indicates that the elapsed time t is in the range O≦t≦a. This means that when flag TI=1, elapsed time t is 0.
α taste that ≦t≦a is not satisfied. The flag T2 indicates whether or not the elapsed time t satisfies aCt≦a+b. When the flag T2=0, it means that the elapsed time t satisfies aCt≦a+b. Here, a and b indicate predetermined periods within the ignition timing retard control period as shown in Fig. 5, and flag H indicates whether knocking that should be suppressed is occurring, taking into account the aging of the engine. This indicates whether or not the flag H
When the flag H=1, it means that knocking is occurring, and when the flag H=O, it means that knocking that should be suppressed is not occurring. In addition, S in FIGS. 3 and 4 indicates a step.

First, the engine speed is read in St, the engine load is read in S2, and in S3 the ignition timing Ig is changed to fl based on the basic ignition timing map based on the engine speed in St and the engine load in S2. In S4, it is determined whether the flag 1c=1 or not. If S4 is NO, the ignition timing is not retard controlled, so in S5 the ignition timing Ig in S3 is set to the final ignition timing. Set as Ig. Then, in S6, ignition is performed based on the ignition timing Ig set in S5.

After the ignition is performed in S6, a knock determination routine is performed in S7. In this knock determination routine, as shown in FIG. 4, the actual knock strength is first read into the knock strength D in S8. This actual knock strength is obtained from the knock sensor output level based on the characteristic line f2 in FIG. Next, in step 39, a knock determination knock strength Do is set in consideration of changes over time. This no-2 judgment knock strength Do is determined based on the characteristic line f3 in FIG. This characteristic line f3 decreases as the amount of change over time increases. For this reason,
The knock strength D at 310 becomes more likely to be judged as knocking that should be suppressed as the change over time progresses.
It is determined whether or not is greater than the knock determination knock strength DO, and when S10 is YES, it is assumed that knocking that should be suppressed is occurring, and the flag is set to 1 in Sll.
is set to 0. Then, in S12, the amount of change over time detected by the mileage detection sensor 25 is changed from the characteristic line f in FIG.
The coefficient K is determined based on 4. This characteristic line f4 is tJ
As shown in Figure 48, it is indicated by a straight line that increases as the amount of change over time increases. Next, in step 513, a predetermined value within the retard control period of the ignition timing is determined based on the characteristic lines fs, f6, and fl in FIGS. period a, b
, c are obtained, respectively. The characteristic line f5 is shown as a straight line that decreases as the amount of change over time increases, as shown in FIG. 9, and the characteristic line f6 is shown as a straight line that increases as the amount of change over time increases, as shown in FIG. The characteristic line f7 is shown as a straight line that increases as the amount of change over time increases, as shown in the eleventh factor. And after this S13, S1
We will proceed to step 5.

When the SIO is NO, there is no knocking to be suppressed, and the flag H is reset in S14.
After this, the process advances to S15.

In S15, it is determined whether the flag H=1 or not, and S
When 15 is YES, it is assumed that knocking to be suppressed has occurred, and the process proceeds to S16, where the ignition timing retard code, 11 gRe', is determined as knock strength D and knock judgment based on the characteristic line f8 shown in FIG. 0 obtained from the difference from the knock strength Do. Next, in S17, the ignition timing retard B I g Re of S16 is determined.
IgRe' is corrected by multiplying by the correction coefficient aK of 312, and is set as the final ignition timing retard lIgRe. In this case, as the engine changes over time, the knock judgment knock strength Do becomes smaller and the correction coefficient K becomes larger, so that the final ignition timing retard F
1f4-1gRe increases as the engine ages. Thereafter, in S18, a flag k is set to indicate that the ignition timing is being retarded, and a timer is set in step 519, after which the process proceeds to step 320 in FIG.

In 520, it is determined whether the elapsed time t is longer than the total control time a+b+c in the ignition timing retard control, and when S20 is No, it is determined that the ignition timing retard control has not been completed and the process returns to SL. Ru. When S20 is YES, it means that the ignition timing retard control has ended, and the flag is reset in 521.

If S4 is YES, it means that the ignition timing is within the retard control period, so the process advances to S22, and in S322 it is determined whether the flag TI=1 or the flag is on. S22 is NO
In this case, it is determined that the elapsed time t is within the range of 0≦t≦a within the ignition timing retard control period, and the process proceeds to S23. S
In No. 23, MIg at the time of ignition is T g = I g - (I gRe/a) Xt,
, , is calculated based on the formula (1). this is,
This can be shown by a straight line with a slope within 0≦t≦a in Fig. 5, and the slope of the straight line - (IgRe/a) reduces torque fluctuation and quickly suppresses knocking when retarding the ignition timing. They are being forced to be sold in the market. As the aging of the engine progresses, a decreases and IgRe increases, so as is clear from Equation (1), the slope of this straight line becomes steeper as the aging of the engine progresses. , it is now possible to stop knocking more quickly. After S23, ignition is performed in S24 based on the ignition timing Ig value in S23, and in S25, the elapsed time t plus 1 is set as the elapsed time t. After this, the process will proceed to S20. In this case, since the process does not proceed to the knock determination routine of S7, the ignition timing Ig will be gradually retarded as the elapsed time t progresses, based on the equation (1) of 323 above, within 0≦t≦a. .

If S22 is YES, the elapsed time t is 0≦t≦
It is determined that the flag is other than a, and the process proceeds to S26, where it is determined whether the flag T2=1. When S26 is No, the ignition timing Ig is calculated in S27 based on the formula Ig=xg-igRe'' (2) assuming that the elapsed time t is within a≦t≦a+b. This is a in Figure 5.
Ct≦a+b, that is, it can be shown by the 117 line within period b, and during this period, the ignition timing Ig is equal to the above S3.
ignition timing Ig to final ignition timing retard early Ig Re
is held in a retarded state. In this case, as the aging of the engine progresses, b increases and IgRe increases, so the ignition timing in item 1 will be greatly retarded as the aging of the engine progresses, and the retarded state will be maintained for a long time. It turns out.

This makes it possible to sufficiently deal with the longer time it takes to suppress knocking due to deterioration of the engine over time. After this S27, 52
8, ignition is performed based on the ignition timing Ig value of 527, and in S29, the elapsed time t plus 1 is set as the elapsed time t. And after this, the S
The process then proceeds to the knock determination routine in step 7. For this reason,
If knocking is determined in the knock determination routine of S7, retard control of the ignition timing will be performed again from the beginning.

When S26 is YES, the elapsed time t is a+b<t
≦a+b+c, that is, it is determined that it is within the C period, and at 330, the ignition timing Ig is Ig=Ig-IgRe
+ (IgRe/c), X (t-(a+b) J
, , is calculated based on the formula (3). Is this the 5th v? This can be shown by a straight line within period C during period J, and according to this, the ignition timing Ig is gradually returned to its original value, so that knocking does not occur continuously. In this case, as the aging of the engine progresses, C increases, so the ignition timing is returned more slowly to cope with the deterioration caused by the aging of the engine. After 330, the process proceeds to 528, and in S28, ignition is performed based on equation (3) of S30.

In this way, ignition timing control based on the above flowchart not only determines the ignition timing retard amount according to the knocking state, but also takes into account the deterioration of the engine over time, and adjusts the ignition timing as the engine changes over time. While increasing the retard amount IgRe of the period Ig (S
12, si7, Fig. 8), the knock judgment strength decreases as the engine changes over time, and the ignition timing retard control is performed from when the knock strength D is small (S9.5lO1 (See FIG. 7), even if the engine deteriorates over time, the damage caused by knocking can be reduced, and the reliability of the engine's knock resistance can be improved.

In addition, as the engine changes over time, the a period is shortened to quickly suppress knocking, while as the engine changes over time, the a and c periods are lengthened to prevent knocking from occurring continuously. This also makes it possible to increase the reliability of the deteriorating engine's knock resistance.

Although the embodiments have been described above, the present invention includes the following.

■Retard of ignition timing as knocking suppression amount
Controlling not only the amount of fuel but also the amount of fuel supplied, air-fuel ratio, etc.

■Detecting engine vibration levels that increase over time as changes in the engine over time.

(Effects of the Invention) As described above, the present invention suppresses knocking by appropriate control signals even if the engine deteriorates significantly over time. The reliability of knocking resistance can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the present invention, Fig. 2 is an overall system diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing a control example of the one in Fig. 2, and the 41st threshold is shown in Fig. 3. Fig. 5 is a diagram showing ignition timing control, Fig. 6 is a characteristic diagram of knock intensity/trick sensor output level, and Fig. 7 is a diagram showing the knock judgment knock intensity - change over time. Characteristic diagram. Figure 8 is a characteristic diagram of correction coefficient vs. amount of change over time. Figure 9 is a.
-Characteristic diagram of the amount of change over time, Figure 10 is b-Characteristic diagram of the amount of change over time, Figure 11 is C-
FIG. 12 is a characteristic diagram of the change over time f, and is a characteristic diagram of IgRe'-(knock strength - knock determination knock strength). −
21: Control unit (combustion state control measure, correction means, knocking suppression degree changing means) 23: Knock sensor 25: Mileage detection sensor

Claims (1)

[Claims] (1) A knocking detection means for detecting knocking, a combustion state control means for outputting a control signal for suppressing knocking, and when knocking is detected, correcting the control signal of the combustion state control means so as to suppress knocking. an engine knocking control device comprising: a temporal change detecting means for detecting a temporal change in the engine; and an output value of the correcting means in a direction in which the degree of knock suppression increases as the temporal change in the engine increases. An engine knock control device comprising: a knock suppression degree changing means for changing the degree of knocking;