JPH0799135B2 - Ignition timing control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ignition timing control device that enhances drivability while suppressing knocking of an internal combustion engine such as an automobile.

(Prior Art) Generally, in order to efficiently extract the output of an engine, the ignition timing is the ignition timing (MBT: Minimu) at which the maximum torque can be generated.
m spark advance for Best Torque) It is desirable to control to advance. However, it is known that the engine causes knocking when the ignition timing is advanced too much, and the ignition timing of the knocking limit that causes this knocking is behind the MBT depending on the engine state, and if the ignition timing is advanced to the MBT, knocking occurs. There is also an area that generates.

Therefore, as a control device that determines knocking for each cylinder and corrects the retard correction amount to avoid knocking, for example, a control device described in Japanese Patent Publication No. 56-50114 is known.

This device determines the knocking level for each cylinder, controls the ignition timing by calculating the retard correction amount for each cylinder according to the determination result, without reducing fuel consumption and engine output, This is to suppress the occurrence of knocking.

(Problems to be solved by the present invention) However, in such a conventional ignition timing control device, a large knock occurs when the load state of the engine changes suddenly, for example, when the load state shifts from a low load state to a high load state. Despite the fact that it will be easier to perform, since the ignition timing is corrected first in the own cylinder after the knocking is detected in the own cylinder, even if knocking is expected to occur in other cylinders, other It was not possible to immediately perform retard correction on the cylinder. As a result, the speed for retard correction is delayed,
Since the occurrence of knocking cannot be sufficiently suppressed, there is a problem that fuel efficiency and drivability are deteriorated.

(Means for Solving Problems) The present invention has been made to solve such problems, and its basic conceptual diagram is shown in FIG.
That is, according to the present invention, the operating state detecting means a for detecting the operating state of the engine, the knock detecting means b for detecting knocking occurring in the engine, and the first knocking for each cylinder based on the output of the knock detecting means b. Knock level determining means c for determining the level and the second knocking level
And the first for each cylinder determined by the knock level determination means c
A retard correction amount that calculates a new retard correction amount by correcting the retard correction amount that corrects the basic ignition timing to the retard side so as to suppress knocking based on the knocking level, and then calculates the new retard correction amount. When the knock level of a certain cylinder exceeds the second knocking level determined by the knock level determining means c, the retard correction amount is corrected to the retard side and the corrected retard correction amount is advanced. Based on the operating state of the engine, a retardation correction amount changing means e for changing the retardation correction amount of another cylinder on the advance side of the advance limit value as the advance limit value to the advance limit value. The ignition timing is set, and the basic ignition timing is corrected according to the retard correction amount calculated by the retard correction amount calculating means d and the retard correction amount changed by the retard correction amount changing means e, and the ignition signal is output. Ignition timing setting means f for outputting and ignition It is obtained and a ignition means g for igniting air-fuel mixture based on the item.

(Operation) In the present invention, when a large knock that exceeds the second knocking level occurs in a certain cylinder, the retard correction amount of the cylinder (certain cylinder) is corrected to the retard side, and the cylinder (certain cylinder) is retarded. In addition to the effect that knocking is suppressed, the retard correction amount after correction for that cylinder (certain cylinder) is set as the "advance limit value".
As a result, there is a peculiar effect that the retard correction amounts of other cylinders (hereinafter referred to as “specific cylinders”) on the advance side of the advance limit value are corrected to the advance limit value. To be Here, the specific operation will be described in more detail. For example, among the cylinders other than a certain cylinder, the retard correction amount of a cylinder that has already undergone sufficient retard correction is equal to the advance limit value. Although it is almost equal or on the retard side (in other words, it is not on the advance side of the advance limit value), it is predicted that a large knock, which exceeds the second knocking level, will occur in a specific cylinder. Since the retard correction amount of the cylinder is on the advance side of the advance limit value, if the advance retard correction is limited to only the retard correction amount of this specific cylinder, knocking of the specific cylinder will occur. It is possible to prevent the above from occurring in advance, and to prevent the advance retard correction for cylinders other than the specific cylinder (that is, the cylinders for which sufficient retard correction has already been performed).
Therefore, it is possible to avoid overcorrection for a cylinder that has already undergone sufficient retardation correction, and prevent output reduction.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

2 to 12 are views showing an embodiment of the present invention.

First, the configuration will be described. In FIG. 2, reference numeral 1 is an engine, intake air is supplied to each cylinder from an air cleaner (not shown) through an intake pipe 3, and fuel is injected by an injector 5 based on an injection signal. Spark plug 7 for each cylinder
Is mounted, and the ignition plug 7 is supplied with a high-voltage pulse from an igniter 11 via a distributor 9. The spark plug 7, the distributor 9 and the igniter 11 constitute an ignition means 13 for igniting the air-fuel mixture, and the ignition means 13 generates a high voltage pulse based on the ignition signal Sp and discharges it. Then, the air-fuel mixture in the cylinder is ignited and explodes by the discharge of the high-pressure pulse, becomes exhaust gas, and becomes
Exhausted through 15.

The flow rate Qa of the intake air is detected by the air flow sensor 16 and controlled by the throttle valve 17 in the intake pipe 3. The combustion pressure of the engine 1 is detected by a knocking sensor 18 including a pressure element, a magnetostrictive element, etc.
The output S _{1 of} is input to the control circuit (control unit) 19. Control unit 19 is knocking sensor 18
Whether or not knocking has occurred is determined based on the output S ₁ of.

Further, a pair of crank angle sensors 20 and 21 are attached to the distributor 9, one crank angle sensor 20 discriminates each cylinder, and the other crank angle 21 detects the crank angle CA. That is, one crank angle sensor 20 has a value of 1 for each 60 ° rotation of the distributor shaft, that is, for each 120 ° crank angle CA of the crankshaft.
Generates two pulses (hereinafter referred to as REF signal). The rising position of this pulse is, for example, a crank angle CA of 70 ° before the top dead center (TDC) of each cylinder, and this pulse width (crank angle CA from rising to falling) differs for each cylinder. The other crank angle sensor 21 generates 360 pulses each time the distributor shaft makes one rotation, and therefore one rising or falling pulse (hereinafter referred to as POS signal) for each 1 ° crank angle CA.

The air flow sensor 16 and the crank angle sensors 20 and 21 constitute an operating state detecting means 22, and the operating state detecting means 22
A signal from the knocking sensor 18 is input to the control unit 19. The control unit 19 performs ignition timing control (other injection amount control is also available, but omitted here) based on these sensor information.

Next, FIG. 3 is a block diagram showing an example of the configuration of the control unit 19 shown in FIG.

The intake air amount signal from the air flow sensor 16 is buffered.
After being sent to the analog multiplexer 32 via 30 and selected according to the instruction from the micro processing unit (MPU) 62 and converted into a digital signal by the A / D converter 34, via the input / output port 36 Captured in the microcomputer.

The REF signal from the crank angle sensor 20 is input to the interrupt request signal forming circuit 40 and the cylinder discriminating circuit 41 via the buffer 38. Further, the POS signal from the crank angle sensor 21 is input to the signal forming circuit 40 and the engine speed signal forming circuit 44 as an interrupt request via the buffer 42. The cylinder discriminating circuit 41 discriminates the ignition cylinder of this time from the pulse width of the REF signal (crank angle CA from rising to falling), forms a binary code corresponding to it, and sends it to the microcomputer via the input / output port 46. . The interrupt request signal forming circuit 40 forms an interrupt request signal for each predetermined crank angle CA from the REF signal and the POS signal, and inputs these interrupt request signals into the microcomputer via the input / output port 46. The engine speed signal forming circuit 44 is
A binary signal representing the engine speed Ne is formed from the signal cycle. This binary signal is fed into the microcomputer via the input / output port 46.

The output signal S ₁ from the knocking sensor 18 is input to a peak hold circuit 50 via a circuit 48 including a buffer for impedance conversion and a bandpass filter capable of passing a frequency band (7 to 8 kHz) peculiar to knocking. It The peak hold circuit 50 outputs the maximum amplitude of the output signal S ₁ from the knocking sensor 18 when the “1” level signal is applied from the MPU 62 via the line 52 and the input / output port 46 to open the knock gate. Hold the value (peak value a). The output of the peak hold circuit 50 is converted into a binary signal by the A / D converter 54 and sent to the microcomputer via the input / output port 46. However, the A / D converter 54
Start A / D conversion of M through I / O port 46 and line 56.
It is performed by an A / D conversion start signal applied from the PU 62. Further, the A / D converter 54, when the A / D conversion is completed,
A / D conversion completion notification is sent to the microcomputer via the line 58 and the input / output port 46. Therefore, the knocking sensor 18, the buffer filter 48, the peak hold circuit 5
0, the A / D converter 54 as a whole constitutes knock detection means.

On the other hand, when the ignition signal Sp is output from the MPU 62 to the drive circuit 60 via the input / output port 46, the ignition signal Sp is converted into a drive signal, the igniter 11 is energized, and the ignition control according to the ignition signal Sp is performed.

Microcomputer has input / output ports 36 and 46, MP
U62, random access memory (RAM) 64, read only memory (ROM) 66, a clock generation circuit (not shown), a bus 68 connecting these, and the like are mainly included, and various processes are performed according to a control program stored in the ROM 66. To execute. In addition, the engine speed N
The basic ignition timing SA ₀ defined by e and the intake air amount per engine revolution (intake pipe pressure when a pressure sensor that detects the pressure on the downstream side of the throttle valve 17 is used instead of the air flow sensor 16) is stored. Has been done.

Further, the control unit 19 is a microcomputer, buffers 30, 38, 42, a buffer filter 48, a peak hold circuit 50, A / D converters 34, 54, a cylinder discrimination circuit 41,
The interrupt request signal forming circuit 40, the engine speed signal forming circuit 44, the analog multiplexer 32, and the drive circuit 60 are provided, and the knock level determining means, the retard correction amount calculating means, the retard correction amount changing means, and the ignition timing are included. It has a function as a setting means.

Next, the operation will be described.

First, a processing routine according to an embodiment of the present invention will be described. In the following description, in order to avoid complication, the most inconvenient numerical values will be used for explanation, but the present invention is not limited to these numerical values, and the optimum value is selected for each engine. To be done.

From the interrupt request signal forming circuit 40, an interrupt request signal for each predetermined specific crank angle CA, that is, an interrupt (hereinafter referred to as REF interrupt) request signal at the rising edge of the REF signal and A
When a TDC 30 °, 60 ° interrupt (hereinafter referred to as an angle interrupt) request signal is input, the MPU 62 executes the interrupt processing routine shown in FIGS. 4 and 5. The main routine of FIG. 4 is mainly for executing the peak hold of the signal S ₁ output from the knocking sensor 18 and for determining the knocking and controlling the ignition timing SA. The subroutine shown in the figure shows a routine for resetting the count value m of the crank angle counter. When the REF interrupt request signal is input, the routine of FIG. 5 is executed, the count value m is reset in step 70, and the process returns to the main routine. Since the rising edge of the REF signal is output at 70 ° crank angle CA before TDC of each cylinder, the count value m is reset at 70 ° crank angle CA before top dead center of each cylinder.

When the angle interrupt request signal is input, the main routine of FIG. 4 is executed, and in step 72, the engine speed Ne determined by the engine speed signal forming circuit 44 is fetched. Next, at step 80, the count value m of the crank angle counter is incremented by +1.

Here, the relationship between the count value m and the crank angle CA is shown in FIG.

Next, at step 86, it is judged if the count value m is 2, that is, if the piston has reached the TDC of each cylinder. If it is not the TDC of each cylinder, the routine proceeds to step 92. If it is the TDC of each cylinder, the cylinder discrimination result is read from the input / output port 46 at step 87 and the cylinder discrimination result is set as the cylinder number i. Next, in step 88, the peak hold circuit
50 knock gates are opened to start the peak hold, and in step 90, the knock gate is closed and the time t ₁ for ending the peak hold is calculated and set in the compare register A.

At the time t ₁ set in the compare register A, the time coincidence interrupt routine shown in FIG. 6 is executed, and in step 102, the A / D conversion of the peak hold value is started. A / D
When the conversion is completed, an A / D conversion end notification is input from the A / D converter 54, and the A / D conversion end interrupt routine of FIG. 7 is executed by this notification. In this routine, step 10
In step 4, the A / D converted value is stored as a peak value a in a predetermined area of the RAM 64, and in step 106, the knock gate is closed and the process returns. Timings for opening and closing the knock gate in the above routine are shown in FIGS. 9 (B) and 9 (C).

Next, at step 92, it is judged if the count value m is 3, that is, if the piston has reached 30 ° ATDC of each cylinder, and if not 30 ° ATDC, the routine proceeds to step 98. On the other hand, when the angle is 30 ° ATDC, the knocking control process for determining the occurrence of knocking and calculating the corrected retard amount SAri is executed in step 94. This knocking control processing is executed by an interrupt processing routine for each 30 ° ATDC of FIG. 10 described later (see FIG. 9D).

Next, at step 96, the basic ignition timing SAo calculated by the interpolation method from the basic ignition timing map stored in the ROM 66 in the main routine (not shown) and the correction retardation amount SAri assigned to each cylinder for knocking control. ₊₁ (i means the next cylinder with cylinder number i ₊₁ . Therefore, when i ₊₁ = 6, it is regarded as 0) and the execution ignition timing SA (= SA
o-SAri _{+ 1} ) is calculated, the on-time of the igniter is obtained from the execution ignition timing SA and the current time, and is set in the compare register B (see FIG. 9 (E)). In the following step 98, the igniter is turned off depending on whether or not the count value m is 1, that is, when the piston is not 60 ° ATDC of each cylinder, and when it is 60 ° ATDC, the execution ignition timing SA and the current time are used. Calculate the time to be set, set it in the compare register B, and return to the main routine.

When the time set in steps 96 and 100 comes, the time coincidence interrupt processing routine shown in FIG. 8 is executed, and in step 108 it is judged whether or not the igniter-on interrupt set in step 96 is detected. Turns on the igniter in step 110, and turns off the igniter in step 112 when the igniter off interrupt occurs and returns. As a result, ignition is performed at the execution ignition timing SA.

Next, the content of the knocking control process of step 94 of FIG. 4 will be described in detail with reference to the flowchart of the subroutine of FIG.

First, in step 200, the peak value a (currently ignited cylinder) detected this time is compared with a _second target value (second knocking level) SL _2, and if a ≦ SL ₂ , a lower limit value (advancement) is entered in step 201. Angle limit value) SAr _{ADV is set} to 0 and the process proceeds to step 202. Here, as for the second target value SL ₂ , the peak value a exceeding this level does not exist, or the frequency is extremely low (for example,
The value is 0.1% or less) (see FIG. 12 (c)).

Next, in step 202, the peak value a is compared with the first target value (first knocking level) SL _1, and when a> SL ₁ , it is determined that knocking is present, and the routine proceeds to step 203, when a ≦ SL ₁ Determines that there is no knocking and proceeds to step 204. Here, the first target value SL ₁ is a value such that the peak value a exceeding this level has a predetermined frequency, and is set according to the operating condition (for example, engine speed N). Further, the predetermined frequency is a ratio (X / X of the basic advance angle X and the basic delay angle Y).
Y), and an appropriate value is, for example, about 10% (range of 1 to 30%) (see FIG. 12 (c)).

In step 203, the retard correction amount SAri _-1 (i is the cylinder number of the current ignition, i-1 is the cylinder number of the previous ignition) is added to the basic retard amount Y.
(For example, 0.025 °) is added to add a new retard correction amount SAri
_-1 is calculated and the process proceeds to step 205.

_{SAri -1 ← SAri -1 + Y ......} (1) Step 204 basic advance angle amount from the retard correction amount Sari _-1 in (e.g., 0.25 °) to compute the new retard correction amount Sari _-1 by subtracting the Go to step 205.

SAri _-1 ← SAri _-1 -Y (2) Next, in step 205, the newly calculated retard correction amount SAr
If i _-1 is larger than the upper limit SArret (SAr _i-1 > SArre
t), SAr _i-1 is limited to the upper limit value SArret, while the lower limit value SArret
If it is smaller than _ADV (SAr _i-1 <SAr _ADV ), SAr _i-1 is limited to the lower limit value SAr _ADV and the process returns. The upper limit value SArr
Let et be a predetermined value, for example, 15 °. The lower limit value SAr _ADV is shown in FIG. 12 (D), for example.

Next, when a> SL _{2 in} step 200, SL ₂ > SL ₁ , so in this case it is determined that a large knock has occurred in a certain cylinder, and in step 206 the retard correction amount is set. SAr
The basic retard amount Y is added to i _-1 to perform retard correction (SAri _-1
← SAri _-1 + Y (3)).

Then, in step 207, this retard correction amount SAr corrected this time
i _-1 is stored as the lower limit value SAr _{ADV and the} process proceeds to step 208. At step 208, the retard correction amount SArj (j ≠ i−1) of the other advanced cylinder is changed to the lower limit value SAr _ADV and corrected, and the routine proceeds to step 205.

Next, the contents of step 208 in FIG. 10 will be described in detail with reference to the subroutine shown in FIG.

This subroutine is the retard correction amount SA corrected to the retard side this time.
With r _-1 as the lower limit (advance limit) SAr _ADV , the retard correction amount SArj (j ≠ i-1) of other cylinders that are advancing further than this.
Is to correct.

First, in step 300, the cylinder number J is initialized (J =
0) Next, in step 301, it is determined whether or not the cylinder number J is the cylinder (cylinder number i-1) for which the current retard correction amount SAri _-1 has been corrected. When J = i-1, jump to step 304, and when j ≠ i-1, step 302 determines retard correction amount S
Arj is compared with the lower limit value SAr _ADV . When SArj ≧ SAr _ADV , the routine jumps to step 304, and when SArj <SAr _ADV , it is determined that the retard correction amount SArj is on the advance side, and the routine proceeds to step 303. In step 303, the value of the retard correction amount SArj is set to the lower limit value SAr.
Change to _ADV , increment the cylinder number by 1 in step 304, and proceed to step 306. If J <6 in step 306, the process returns to step 301, and the same operation is performed for other cylinders until J = 6, and when J ≧ 6, this routine ends.

By the way, the basic ignition timing SA ₀ is usually set so as to provide the best fuel economy according to the operating conditions of the engine, and when the engine shifts to a high load (see FIG. 11 (A),)
Since knocking easily occurs in the basic ignition timing SA
_It is necessary to increase the retard correction amount SAri for correcting ₀ to the retard side.

In the conventional example, as shown in FIG. 11B, the retard correction amount of the cylinder is corrected to the retard side only when the peak value a becomes larger than the target value SL ₁ .

In this embodiment, when the peak value a exceeds the second target value SL ₂ (see FIG. 11 (C)), the retard correction amount SAri ₋₁ corrected to the retard side of the cylinder is set to the lower limit value ( Advance limit value) SAr _ADV
And the retard correction amount SArj for other cylinders that are advancing from this
Is changed to the lower limit value SAr _ADV (see FIG. 11 (D)).

In this way, the retarding speed can be increased by previously retarding the other cylinders in which knocking is likely to occur. Therefore, the time required to converge the retard correction amount SAri _-1 when retarded due to load change is
It can be greatly shortened as shown in FIG.
As a result, knocking can be effectively suppressed, and fuel economy and drivability can be further improved.

(Effect) As described above, according to the present invention, when the knocking level of a certain cylinder exceeds the second predetermined value, the corrected retard correction amount of that cylinder is set as the lower limit value, and the advance angle is advanced from this. Since the retard correction amounts of the other cylinders that are operating are changed to this lower limit value, the time until the retard correction amounts converge can be shortened. As a result, knocking can be effectively suppressed, and fuel economy and drivability can be further improved.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 12 are diagrams showing an embodiment of the present invention, FIG. 2 is an overall configuration diagram thereof, and FIG. 3 is a block diagram of its control circuit. 4 and 8 are flowcharts showing respective processing routines executed by the control circuit, FIG. 9 is a timing chart showing the operation of the control circuit, and FIG. 10 is the knocking control process of FIG. Fig. 11 is a flow chart showing the execution program.
A concrete flow chart of step 208 in FIG. 10 and FIG. 12 are explanatory views for explaining the operation of the present invention. 1 ... Engine, 13 ... Ignition means, 18, 48, 50, 54 ... Knock detection means, 19 ... Control unit (knock level determination, retard correction amount calculation means, retard correction amount change means, ignition timing Setting means), 22 ... Operating state detection means.

Claims (1)

[Claims] 1. A driving state detecting means for detecting an operating state of an engine, b) a knock detecting means for detecting knocking occurring in the engine, and c) a first for each cylinder based on an output of the knock detecting means. Knock level determining means for determining the first knocking level and the second knocking level; and d) retarding the basic ignition timing so as to suppress knocking based on the first knocking level for each cylinder determined by the knock level determining means. And a retard angle correction amount calculation means for calculating a new retard angle correction amount by correcting the retard angle correction amount to be advanced to the advanced angle side or the retard angle side, and e) the knock level determination means for determining the knock level of a certain cylinder. When the determined second knocking level is exceeded, the retard correction amount is corrected to the retard side, and the corrected retard correction amount is set as the advance limit value to the advance side of the advance limit value. Retard correction amount changing means for changing the retard correction amount of another cylinder to the advance limit value, and f) setting the basic ignition timing based on the operating state of the engine, and retarding the basic ignition timing. Ignition timing setting means that corrects according to the retard correction amount calculated by the correction amount calculation means and the retard correction amount changed by the delay correction amount changing means, and outputs an ignition signal; and g) Mix based on the ignition signal An ignition timing control device comprising: an ignition means for igniting the air.