JPS62247177A - Ignition timing controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the engine faculty in the transient operation region by comparing the delay angle quantity of each cylinder with the min. delay angle quantity set according to the preignition region and controlling the delay angle quantity so as to increase over the min. delay angle quantity. CONSTITUTION:A delay angle control means B for each knocking corresponding cylinder which delay-angle-controls the ignition timing for each cylinder accord ing to the output of a knocking sensor A when knocking is generated is pro vided. Further, a judgement value memory means C which memorizes the judge ment value of the min. delay angle quantity set according to the preignition region according to the engine operation state is provided. Further, it is judged D if the delay angle quantity of each cylinder is larger or not than the judge ment value of the main. delay angle quantity, and if the judgement is 'NO', a delay angle determining value of the min. delay angle quantity, and if the judgement is 'YES', the delay angle quantity determined by the control means B is outputted. Then, the fundamental ignition timing calculated by a fundamen tal ignition timing determining means F is delay angle corrected G according to the operation state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition timing control device for an internal combustion engine that controls ignition timing for each cylinder depending on the knocking state of the internal combustion engine.

[Conventional technology]

Conventionally, this type of device has been considered to detect knocking in each cylinder of an internal combustion engine and control the ignition timing for each cylinder (for example, Japanese Patent Laid-Open No. 57-129260
Publication).

First, with reference to FIGS. 2 and 3, a conventional general all-cylinder timing-responsive ignition timing control (hereinafter referred to as simultaneous KC5) will be explained. The basic ignition timing θ of the simultaneous KC3 is the ignition timing that produces the target knocking sound (the two points u in Fig. 2.3).
The ignition timing that produces the target knocking sound of simultaneous KC3, which is set slightly on the advanced side (dotted chain line in Fig. 2.3) with respect to the L line), is determined by the knocking ignition timing of the cylinder that is most likely to knock.

In the example shown in FIG. 3, the first cylinder is most likely to knock, so the ignition timing is controlled to the target knocking sound.

Next, conventional cylinder-by-cylinder knock-responsive ignition timing control (hereinafter referred to as cylinder-by-cylinder KCS) will be explained. Ignition timing that produces the target knocking sound for each cylinder (KC for each cylinder shown in Figure 3 a)
It is well known that internal combustion engine performance can be improved by controlling the ignition timing to KC5).

Therefore, in order to reliably operate KC3 for each cylinder, it is necessary to set the basic ignition timing θ to the advance side of the knock ignition timing of all cylinders.
.

Since it is necessary to set the basic ignition timing θ of simultaneous KC3, it is necessary to set θ to the advanced side as shown by the solid line in Figure 3.
It is obvious that 8 will be set. That is, in FIG. 4, the basic ignition timing θ is advanced from the dashed line to the solid line.

By the way, there is a correlation between knocking noise and preignition, and it is said that the louder the knocking sound, the easier it is to preignition. However, this is a qualitative story, and quantitatively it changes depending on the operating conditions of the internal combustion engine, etc. An example of this is shown in FIG. This basic ignition timing θ, (
Actual vA) in FIG. 4 is the ignition timing of a knocking sound that is slightly thicker than the target knocking sound. In other words, even though the sound line is an equal knock sound line, the margin of ignition timing with respect to pre-ignition differs depending on the conditions of the internal combustion engine (in this case, the rotation speed).

[Problem that the invention seeks to solve]

This will cause the following problems. Suppose that a certain cylinder is controlled to cause extremely strong knocking and stick to the basic ignition timing θ.

In Fig. 4, this corresponds to the dangerous area. If, for some reason, that cylinder suddenly becomes susceptible to knocking, a very large knock will occur, and it will be in a very dangerous state for pre-ignition. In addition, if we consider the case where the knock sensor or control circuit fails while the control is in a dangerous area, the pre-ignition will still be affected for several ignitions until the failure is detected and the ignition is retarded. You will be exposed to great danger.

Generally, a designer sets the basic ignition timing θ3 with a certain margin for pre-ignition in consideration of the above-mentioned dangerous situation. This is shown in Fig. 5. The basic ignition timing θ error of KC3 for each cylinder is set as shown by the solid line,
Even if the above-mentioned dangerous situation were to occur, a large knock might occur temporarily, but it would never lead to pre-ignition.

The problems of the conventional cylinder-specific KC3 having the basic ignition timing θ1 set for the reasons stated above will be explained below with reference to FIG.

The first thing to note here is the relationship between knocking noise and ignition timing. The equal knock sound line is just the basic ignition timing θ shown by the solid line in FIG. The basic ignition timing θ in Fig. 5 is N
, rpm is on the equal knock sound line, but above N, rpm, the knocking sound is smaller than that.

This will be explained below with this in mind. Now, N, rpm
is operated in steady state. At this time, the first cylinder (#l) that is likely to knock is at point d (retard amount β℃A), and the fourth cylinder (#4) that is less likely to knock is at point a (retard amount α”CA).
), the target knocking sound is controlled. This N, rpm
Considering the case where the rotation rapidly increases from N to RPM, each retard amount α.

Almost immediately after β'CA is updated, the retardation amount is maintained until Nzrpm. Therefore, the 4th cylinder is at point a
When the first cylinder is turned on, the controlled ignition timing moves from point d to point e. Let us now consider the knocking sounds at point e and point e. Even though the retard amounts are the same α0 and β'CA, as described above <N.

Between the knocking sound at the basic ignition timing θ of rpm and the knocking sound at the basic ignition timing θ8 of Nz rpm, Nz rpm is lower, so the knocking sound at point e is also lower than the knocking sound at point a and point d. become something low.

Therefore, after transitioning to a steady state at N2 rpm, in order to control each cylinder to the target knock sound state, the retard amounts α0, β
℃A is gradually decreased to advance the angle to point C and point r. Fourth
Regarding the cylinder, in this case, the ignition timing of the target knock sound is on the advanced side from point C, but it remains at point C due to the margin for pre-ignition.

In other words, during a transient period, the ignition timing is unnecessarily retarded between N, rpm and N2 rpm (an area in which the basic ignition timing θ8 has a margin for pre-ignition), which impairs the performance of the internal combustion engine. This leads to a decrease in

(Note that the maximum retard amount limit value shown by the broken line in FIGS. 2, 4, and 5 is set based on restrictions such as exhaust temperature.) Therefore, the present invention is designed to prevent pre-ignition even during transient times. The purpose of this is to prevent the ignition timing from being unnecessarily retarded in the vicinity of this range, thereby preventing the performance of the internal combustion engine from deteriorating.

[Means for solving problems]

Therefore, the present invention provides an operating state detecting means for detecting the operating state of an internal combustion engine, and a basic method for determining the basic ignition timing without avoiding the pre-ignition region according to the operating state of the internal combustion engine detected by the operating state detecting means. Ignition timing determining means, a knock sensor that detects knocking in the internal combustion engine, and a knock response cylinder-specific knock response cylinder that retards the ignition timing for each cylinder when knocking occurs according to the knocking state detected by the knock sensor. a retard control means; a determination value storage means for storing a determination value of a minimum retard amount set corresponding to a pre-ignition region according to an operating state of the internal combustion engine; and a knock-responsive cylinder-specific retard control means. a retard amount determining means for determining whether the retard amount of each cylinder determined by the above is larger or smaller than the minimum retard amount determination value stored in the determination value storage means; When it is determined that the retard amount for each cylinder determined by the cylinder-specific retard control means is smaller than the minimum retard amount judgment value from the judgment value storage means, the retard amount is set to the minimum retard amount from the judgment value storage means. a retard amount determining means for respectively changing the retard amount determination value and outputting the retard amount determined by the knock-responsive cylinder-specific retard control means when it is determined that the retard amount is large; and the retard amount determining means. ignition timing correction means for retarding the basic ignition timing of the basic ignition timing determining means based on the retardation amount for each cylinder determined by the ignition timing correction means for determining the ignition timing for each cylinder, respectively. It provides:

[Effect]

As a result, the basic ignition timing is determined by the basic ignition timing determining means without avoiding the pre-ignition region.
Further, the retard amount of each cylinder is determined by the knock-responsive cylinder-specific retard control means according to the knocking state of each cylinder. Then, the magnitude of the minimum retardation amount set in the determination storage means and the retardation amount determined by the knock-responsive cylinder-specific retardation control means is retarded in accordance with the pre-ignition region according to the engine operating state. Based on the result, the retard amount determining means determines the retard amount for each cylinder so that it is larger than the minimum retard amount, and the ignition is performed according to the retard amount for each cylinder. The timing correction means retards the basic ignition timing to determine the ignition timing of each cylinder.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

First, the basic technical idea of the present invention will be explained.

In order to achieve the objective, the present invention introduces the concept of minimum retardation amount restriction and sets a prohibited area. The basic ignition timing θ of the cylinder-specific KC3 according to the present invention is the same as θ8 shown in FIG. 4, and θ itself has a dangerous range for pre-ignition. The minimum retard amount limit value shown in FIG. 6 is set to this, and a prohibited area is set to the effective ignition timing.

In other words, the upper limit of the ignition timing that can actually be taken is θ up to N rpm, and the ignition timing with the minimum retard amount limit above N rpm.

Its operation will be explained at N2 rpm. The ignition timing of a certain cylinder is (θ, -θm ”CA, and θ8.〉γ
Suppose that the relationship was Here, θR1 is the retard amount of each cylinder, and γ is the minimum retard amount limit value.

Generally, KO2 is advanced by a certain amount if no knock occurs for a certain period of time or a certain number of ignitions. Here, we assume that δ'
CA. Assuming that there is no knocking at all in this cylinder, θll+ will change over a certain period of time or a certain number of ignition ports.
85=θ1li−δ is calculated, and the actual ignition timing (θ
, -θ■) is also advanced by δ"CA. Therefore, if the calculated θ1. is in the relationship θll!<γ, θ8.=γ is executed. Therefore, the actual ignition timing is The upper limit is (θ■-γ)°C even if there is no knocking.Thus, the first objective of ``never stepping into an area dangerous to pre-ignition'' can be achieved.

Next, unnecessary retardation during transition will be explained.

As described above in FIG. 6, from l'J, rpm to N2r
Consider a case where the rotation speed rapidly increases to pm. N.

At rpm, the first cylinder (#l) is at point d, the fourth cylinder (#4)
is controlled to the target knocking sound at point a.

First, we will observe the behavior of the first cylinder, which tends to knock. When the rotation rapidly increases to N, rpm, the retardation amount β'C
A is almost never updated. However, since θ is on the advance side with respect to Fig. 5, the actual ignition timing (θ8 - θ□)
°CA is on the more advanced angle side, and when compared with the case where the angle is advanced to one point after moving from point d to point e, it can be seen that there is no unnecessary retardation.

In this case, since β>γ, the minimum retard amount limit is not met, and therefore the equal knock line is traced.

Next, let's look at the fourth cylinder, which is difficult to knock. Nz
When the rotation rapidly increases to rpm, the retard amount α''CA hardly has time to be updated.Here, looking at the ignition timing of the 4th cylinder in Fig. 7, the minimum retard amount is reached at ignition points 1 to 3 up to N3 rpm. Since it is outside the limit, the retard amount θe'CA is not checked and (θ8 - θ □)℃A is output as it is. eN3rpm or more is within the minimum retard amount limit value. , a check is executed for the retard amount θ8°C.Here, at the ignition point 4, θ8=α”CA is clearly outside the prohibited area, so (θ8−θ1li)°CA is output as is. At the next ignition point 5, θII! “α℃A is within the prohibited area (θ□〈ρ). Therefore, the advance angle is θ1
After changing to =ρ'CA, (θ, −〇□)°CΔ is output. That is, the ignition point 5 is changed to the ignition point 6, and ignition is executed. The same process is repeated from ignition points 7 to 13, and the ignition is reached at N rpm. That is, the effective ignition timing of the fourth cylinder quickly moves from point a to ignition. Comparison with the conventional method (FIG. 5) in which the angle is advanced to point C after moving to point C, it can be seen that there is no unnecessary retardation.

As explained above, in the cylinder-specific KC3 of the present invention, a minimum retard amount limit is set in a region dangerous to pre-ignition, and the basic ignition timing θ is set on the more advanced side than 01 of the conventional technology in that region. This has the excellent effect of avoiding unnecessary retardation during transition, preventing deterioration of engine performance, and never stepping into a dangerous area for pre-ignition.

In addition, in the above explanation, it is assumed that the minimum retard amount limit is judged to be above N, rpm, but if the minimum retard amount limit below Nsrpm is set to 0℃A, it is determined whether it is in the area or not. It is clear that the means will no longer be necessary.

Next, specific embodiments of the present invention shown in the drawings will be described. FIG. 8 schematically shows the overall configuration of an internal combustion engine according to the present invention, in which 10 is a four-cylinder internal combustion engine cylinder block;
12 is a knock sensor attached to the cylinder block lO. The knock sensor 12 is a well-known device that is composed of, for example, a piezoelectric element or an electromagnetic element, and converts mechanical vibrations into electrical amplitude fluctuations.

In FIG. 8, 14 further indicates a distributor, and this distributor 14 is provided with crank angle sensors 16 and 18. The crank angle sensor 16 is for cylinder discrimination, and if this engine is a 4-stroke, 4-cylinder engine, every time the distributor shaft makes one revolution, that is, every two revolutions of the crankshaft (720'C
A) Generate one pulse for each pulse. The occurrence position is set, for example, to the top dead center of the first cylinder. The crank angle sensor 18 generates 24 pulses for each revolution of the distributor shaft, ie, a pulse for every 30'' of crank angle.

Electric signals from knock sensor 12 and crank angle sensors 16 and 18 are sent to control circuit 20. The control circuit 20 is further fed with a signal representing the intake air flow rate from an air flow sensor 24 provided in the intake passage 22 of the engine. On the other hand, from the control circuit 20, the igniter 2
An ignition signal is output to 6, and the spark current generated by igniter 26 is distributed to spark plugs 28 of each cylinder via distributor 14.

The engine is usually provided with various other sensors that detect operating state parameters, and the control circuit 20 also controls the fuel injection valves 30 and the like, but these are not directly related to the present invention. , all of these will be omitted in the following description.

FIG. 9 is a block diagram showing an example of the configuration of the control circuit 20 shown in FIG. 8. The voltage signal from the air flow sensor 24 is passed through a buffer 30 to an analog multiplexer 32.
The signal is selected according to an instruction from the microcomputer, applied to the A/D converter 34, converted into a binary symbol, and then taken into the microcomputer via the input/output port 36.

Pulses every 720° of crank angle from the crank angle sensor 16 and 30° of crank angle from the crank angle sensor 18
Each pulse is applied to the input/output port 46 via the shaping circuit 40.

The output signal from the knock sensor 12 is sent to the input circuit 52 and A.
It is applied to the input/output port 46 via the /D converter 54. The A/D conversion start of the A/D converter 54 is performed by an A/D conversion start signal applied from the microcomputer via the input/output port 46 and vA56. Also,
When the A/D conversion is complete, A/D converter 54 outputs line 58.
A/D conversion completion notification is sent to the microcomputer via the input/output port 46.

On the other hand, when an ignition signal is output from the microcomputer to the drive circuit 60 via the output boat 59, this is converted into a drive signal to energize the igniter 26, and the ignition signal is activated according to the connection time and duration of the ignition signal. Ignition control is performed.

The microcomputer includes the input/output boats 36 and 46, the output boat 59, and a microprocessor (MPU).
) 62, random access memory (RAM) 64, read-on memory (ROM) 66, clock generation circuit 67
It mainly consists of a bus 68 and the like that connect these, and performs various processes according to a control program stored in the ROM 66.

FIG. 10 is a flowchart showing a knock-responsive ignition timing processing routine that is particularly relevant to the present invention among the above control contents. According to this processing routine, ignition timing control as shown in FIGS. 6 and 7 is realized.

A program for performing such control is stored in the ROM 66, and the processing routine shown in FIG. 10 will be explained in detail below.

In step S, the A/D converter 34, the shaping circuit 4
0, input signals corresponding to various operating conditions of the internal combustion engine are taken into the microcomputer, and depending on these operating conditions, the basic ignition timing characteristic shown by the solid line in Fig. 6 is achieved without avoiding the pre-ignition region. The corresponding basic ignition timing θ is calculated. In the next step S2, the knock sensor 1 is
The output signal from 2 is input to a microcomputer, and knocking is determined according to the knock sensor signal. This determination of knocking is made when the knocking intensity detected by the knock sensor 12 is greater than or equal to a predetermined value, or when the frequency of occurrence of knocking is greater than or equal to a predetermined value.

If it is determined in step S2 that there is knocking, the process moves to step S3 to identify the cylinder in which knocking occurs. Here, the cylinder in which knocking has occurred is determined based on the output signals of both crank angle sensors 16 and 18.

In the next step S4, a retard amount θ1 is calculated and stored for each cylinder according to the knocking intensity.

Further, if it is determined in step S2 that there is no knocking, the process proceeds to step Ss, and when the state of no knocking continues for a predetermined time or a predetermined number of ignitions, the retard amount of each cylinder is subtracted by a predetermined amount δ and is stored.

Then, in the next step S6, the minimum retardation amount limit value and the maximum retardation amount limit value corresponding to the rotational speed of the internal combustion engine are set to R.
Read from OM.

After that, in step S1, it is determined whether the retardation amount of each cylinder is between the minimum retardation amount limit value and the maximum retardation amount limit value, and the retardation amount of each cylinder is determined to be within the minimum retardation amount limit. If it is less than the retardation amount limit value or if it is greater than the maximum retardation amount limit value, proceed to step SL+ and reset the retardation amount θem of each cylinder to the minimum retardation amount limit value or the maximum retardation amount limit value T, respectively. After that, proceed to step S.

Further, if it is determined in step S7 that the retardation amount of the cylinder is between the minimum retardation amount limit value and the maximum retardation amount limit value, the retardation amount of each cylinder determined in steps S4 and Ss is determined. The process proceeds to step S without any change in the angle amount.

In step S, the ignition timing of each cylinder is determined by subtracting the retardation amount θ1 of each cylinder from the basic ignition timing θB.

Note that although the above embodiment also has a maximum retard amount limit value, this maximum retard amount limit value is not necessarily necessary.

Further, the minimum retardation amount limit value can be changed not only depending on the rotation speed of the internal combustion engine but also depending on the magnitude of the load on the internal combustion engine.

〔Effect of the invention〕

As described above, in the present invention, the retard amount of each cylinder is compared with the minimum retard amount set corresponding to the pre-ignition region, and is controlled to be larger than the minimum retard amount. Therefore, the basic ignition timing can be determined without avoiding the pre-ignition region, and even in a transient state, near the pre-ignition region,
This has the excellent effect of preventing the ignition timing from being unnecessarily retarded and improving the performance of the internal combustion engine.

[Brief explanation of drawings]

Figure 1 is a diagram corresponding to the claims of the present invention, Figures 2 to 5
The figures are various characteristic diagrams to explain the operation of the conventional device, Figures 6 and 7 are engine speed vs. ignition timing characteristic diagrams to explain the operation of the device of the present invention, and Figure 8 is the implementation of the device of the present invention. FIG. 9 is a block diagram showing the internal structure of the control circuit shown in FIG. 8; FIG. 10 is a flowchart for explaining the operation of the microcomputer in the circuit shown in FIG. 9. . 12... Knock sensor, 16. 18... Crank angle sensor, 24... Air flow sensor, 26... Igniter, 62... MPU, 66... ROM. Representative Patent Attorney Takashi Okabe 1st drawing>Bun 2nd drawing - Hanawa 3rd engine turning 4th drawing 5th figure 6th figure 7th figure

Claims (1)

[Claims] an operating state detecting means for detecting the operating state of the internal combustion engine; a basic ignition timing determining means for determining the basic ignition timing without avoiding a pre-ignition region according to the operating state of the internal combustion engine detected by the operating state detecting means; a knock sensor that detects knocking in an internal combustion engine; a knock-responsive cylinder-specific retard control means that retards ignition timing for each cylinder when knocking occurs according to a knocking state detected by the knock sensor; and an internal combustion engine. judgment value storage means for storing a judgment value of the minimum retard amount set corresponding to the pre-ignition region according to the operating state of the engine; a retard amount determining means for determining whether the retard amount is larger or smaller than a determination value of the minimum retard amount from the determination value storage means; When it is determined that the retard amount of each cylinder is smaller than the minimum retard amount determination value from the determination value storage means, the retard amount is changed to the minimum retard amount determination value from the determination value storage means. and a retard amount determining means for outputting the retard amount determined by the knock-responsive cylinder-specific retard control means when it is determined that the retard angle is large, and a retard angle for each cylinder determined by the retard amount determining means. 2. An ignition timing control device for an internal combustion engine, comprising: ignition timing correcting means for retarding the basic ignition timing of the basic ignition timing determining means to determine ignition timing for each cylinder.