JPH0830461B2 - Ignition timing control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control device that enhances drivability while suppressing strong knocking that may interfere with the operation of an internal combustion engine such as an automobile.

(Prior Art) Generally, in order to efficiently extract the output of the engine, the ignition timing (MBT: Mini
It is desirable to control so as to advance to mum spark adyance for Best Torque). When advanced to MBT, maximum torque can be obtained while accompanied by light knocking called trace knock. However, it is known that if the engine advances the ignition timing too much, it causes strong knocking (hereinafter simply referred to as knocking) to the extent that it interferes with the operation of the internal combustion engine. Some of them are on the lag side of the MBT, and there is a region where knocking occurs when the ignition timing is advanced to the MBT.

Therefore, when there is no knocking of the engine, that is, when there is no strong knocking that interferes with the operation of the internal combustion engine, a control that controls the ignition timing by changing the amount of advancement and the amount of retarding when knocking is detected. As a device, for example, one described in Japanese Patent Publication No. 60-24310 is known.

This is to retard the ignition timing when the knocking is detected, and to advance the ignition timing when the knocking is not detected. It is set to a value that is larger than the amount to be caused. As a result, once knocking is detected, the occurrence of knocking is surely prevented in the next combustion.

(Problems to be solved by the present invention) However, in such a conventional ignition timing control device, the retard correction amount is set to a value larger than the advance correction amount, and the amount is a constant value. Therefore, there is a large difference in the correction delay amount at which the knocking is at an allowable level depending on the operating conditions (for example, when the load changes from the high load range to the low load range, or vice versa), and the correction delay amount becomes large When the operating condition changes to a small value, or when the octane number increases negatively, the difference between the retard correction amount and the required advance value is large, and it takes time to reach the required advance value. There was a problem that fuel efficiency and drivability deteriorate.

(Means for Solving Problems) The present invention has been made to solve such problems, and includes an operating state detecting means a for detecting an operating state of an engine and a knocking occurring in the engine. Knocking signal detecting means b for detecting a signal, and knocking state judging means c for judging a knocking state when the strength of the knocking signal exceeds a predetermined value, and a knocking state judging means c for judging a non-knock state including a trace knock when the strength of the knocking signal does not exceed a predetermined value. When the knocking state determination means c determines the knocking state, a retard correction amount for correcting the ignition timing to the retard side is generated, while when the non-knock state is determined, the knock signal in the non-knock state is generated. Correction amount generating means d for generating an advance correction amount that increases as the strength of the engine decreases, and the basic ignition timing is set based on the operating state of the engine. At the same time, an ignition timing setting means e for correcting the basic ignition timing based on the output of the correction amount generating means d, and an ignition means f for igniting the air-fuel mixture according to the output of the ignition timing setting means e are provided. It is a feature.

(Operation) In the present invention having such a configuration, the smaller the knocking signal in the non-knock state including the trace knock, the faster the advance speed of the ignition timing can be made. Therefore, the time required to reach the required advance value can be shortened. can do. As a result, fuel efficiency and drivability can be improved.

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

2 to 11 are views showing an embodiment of the present invention.

First, the configuration will be described. In FIG. 2, reference numeral 1 is an engine, and intake air is supplied from an air cleaner (not shown) to an intake pipe 3
Is supplied to each cylinder through the fuel, and the fuel is injected by the injector 5 based on the injection signal. A spark plug 7 is attached to each cylinder, and a high-voltage pulse from an igniter 11 is supplied to the spark plug 7 via a distributor 9. The spark plug 7, the distributor 9 and the igniter 11 constitute an ignition means 13 for igniting an air-fuel mixture, and the ignition means 13 generates a high voltage pulse based on the ignition signal Sp to discharge it. Then, the air-fuel mixture in the cylinder is ignited and exploded by the discharge of the high-pressure pulse, becomes exhaust gas, and is exhausted through the exhaust pipe 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. A knocking signal corresponding to the combustion pressure of the engine 1 is detected by a knocking sensor 18 composed of a pressure element, a magnetostrictive element, etc., and an output S ₁ of the knocking sensor 18 is input to a control circuit (control unit) 19. The control unit 19 determines whether knocking occurs based on the output S ₁ of the knocking sensor 18.

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, which is an operating state detecting means.
The signals from the knocking sensor 22 and the knocking sensor 18 are 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 sent to the analog multiplexer 32 via the buffer 30,
It is selected according to an instruction from the micro processing unit (MPU) 62, converted into a digital signal by the A / D converter 34, and then taken into the microcomputer through the input / output port 36.

The REF signal from the crank angle sensor 20 is transmitted via the buffer 38 to the interrupt request signal forming circuit 40 and the cylinder discriminating circuit 41.
Is input to In addition, the POS signal from the crank angle sensor 21 sends an interrupt request to the signal forming circuit 40 via the buffer 42.
And the engine speed signal forming circuit 44. 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 58 constitutes the knock detecting means as a whole.

On the other hand, drive circuit 60 from MPU 62 via I / O port 46
When the ignition signal Sp is output to, 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.

The microcomputer has input / output ports 36 and 46,
The MPU 62, a random access memory (RAM) 64, a read only memory (ROM) 66, a clock generation circuit (not shown), a bus 68 connecting these, and the like are mainly configured, 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 SAo defined by e and the intake air amount per engine revolution (intake pipe pressure when a pressure sensor for detecting the pressure on the downstream side of the throttle valve 17 is used instead of the air flow sensor 16) is stored. ing.

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 included, and have a function as a knock state determining means, a correction amount generating means, and an ignition timing setting means.

 Next, the operation will be described.

First, a processing routine according to an embodiment of the present invention will be described. It should be noted that in the following description, in order to avoid complication, description will be made using the most inconvenient numerical values, but the present invention is not limited to these numerical values, and the optimum value for each engine type Is selected.

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 when the REF signal rises and an ATDC 30 °, 60 ° interrupt (hereinafter, angle interrupt Say)
When the 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, A / D conversion of the peak hold value is started. A /
When the D 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
At 104, the A / D conversion value is stored as a peak value a in a predetermined area of the RAM 64, and at step 106, the knock gate is closed and the process returns. The timing for opening and closing the knock gate in the above routine is No. 9
Shown in Figures (B) and (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 map of the basic ignition timing 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
Is the cylinder number; i _{+ 1} means the next cylinder. Therefore, i ₊₁ =
When it reaches 6, it is regarded as 0) and the execution ignition timing SA
(= SAo-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.

Eighth when the time set in steps 96 and 100 is reached
The time coincidence interrupt processing routine shown in the figure is executed, and in step 108 it is judged whether or not it is the igniter on interrupt set in step 96.If the igniter is on interrupt, the igniter is turned on in step 110 and the igniter off If it is an interrupt, the igniter is turned off in step 112 and the process 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 knocking strength is determined. This knocking strength determination is performed by using a knocking determination parameter a indicating the knocking strength and a predetermined value set in advance.
K ₁ , K ₂ , and K ₃ (K ₁ <K ₂ <K ₂ ) are compared, and the comparison is performed according to the size of both. Knocking determination parameter a is a> K ₃
If so, go to step 202.

Here, the frequency distribution of the knocking determination parameter a is shown in FIG. 11 for each knocking level ◯, ◇, Δ. In FIG. 11, when a> K ₃ , the knock level may be three knock levels ○, ◇, △, but the frequency of the levels ○, ◇ (knocking frequency) is low and the knock level is △. It is judged as a level. That is, it is determined that the frequency of a> K ₃ , that is, the frequency of strong knocking that hinders the operation of the engine 1 is a predetermined value or more (for example, 10% or more). And
In step 202, the correction retardation amount SAri ₋₁ is added to the correction retardation amount SAri to calculate the correction retardation amount SAri ₋₁ . In this way, it is possible to prevent the occurrence of strong knocking that retards the execution ignition timing SA and hinders the operation of the engine 1.

Next, when the knocking determination parameter a is K ₂ <a ≦ K ₃ , the process proceeds to step 204. When K ₂ <a ≤ K ₃ , as shown in Fig. 11, the knocking level is three levels ○,
◇, △ may occur, and the frequency is such that a> K ₃ , that is, the frequency of strong knocking that hinders the operation of the engine 1 is low (for example, 1 to 10%). It is determined that And step 204
In newly calculates a correction retard amount Sari _-1 from the correction retard amount Sari _-1 by subtracting a small amount of advance X. As a result, the execution ignition timing SA is gradually advanced slightly, and ignition timing control is performed so as to generate a trace knock, that is, control at the knocking limit is performed. Therefore, the torque of the engine can be sufficiently drawn. The value of the minute advance angle amount X is set to, for example, 1/10 of the minute retard angle amount Y.

Next, when the knocking determination parameter a is K ₁ <a ≦ K ₂ , the routine proceeds to step 206, where the frequency at which a ≦ K ₃ is satisfied is determined at step 206. <When the a ≦ K _2, as shown in FIG. 11, the level of △ is Okoriezu, knocking level is determined to be near or level ○ and ◇, a> K ₁ K ₃
Is determined, that is, the possibility of occurrence of strong knocking that hinders the operation of the engine 1 is small (for example, 0.1 to 1%). In this case, the process proceeds to step 206, and in this step 206, the corrected retard amount SAri _-1
The small amount of advance angle X ₁ is subtracted from this to newly calculate the corrected amount of retard angle SAri ₋₁ . Then, the advance angle is advanced with a value (X ₁ > X) larger than the minute advance angle amount X in step 204. That is, the advance speed is increased to shorten the time required to reach the required advance value. In this way, fuel efficiency and drivability can be improved.

Next, when the knocking determination parameter a is a <K ₁ , the process proceeds to step 208. As shown in FIG. 11, a <K ₁
In this case, the ◇ and Δ levels cannot occur, and in this case, the knocking level is determined to be the O level, and there is no possibility that knocking will occur. That is, a non-knock state in which the frequency of a> K ₃ is less than or equal to a certain value (for example, 0.1% or less) is determined, and in this case, the execution ignition timing SA may be significantly advanced. In step 208, the corrected retard amount SAr
The minute advance amount X ₂ is subtracted from i ₋₁ , but the advance amount is advanced with a value (X ₂ > Y) larger than the minute retard amount Y in step 202. In this way, it is possible to further increase the advance angle speed and further shorten the time required to reach the required advance angle value. As a result, fuel efficiency and drivability can be further improved.

In this embodiment, when the corrected retard amount SAri _-1 becomes negative, SAri _-1 is reset to 0.

When the subroutine described above is executed, the process returns to the main routine.

(Effect) As described above, according to the present invention, it is possible to accelerate the speed for slightly advancing according to the strength of knocking, so that it is possible to shorten the time until the required advance value is reached. As a result, fuel efficiency and drivability can be improved.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 11 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 flowchart showing an execution program, and FIG. 11 is a diagram showing a frequency distribution of knocking determination parameters. 1 ... Engine, 13 ... Ignition means, 18, 48, 50, 54 ... Knock detection means, 19 ... Control unit (knock state determination means, correction amount generation means, ignition timing setting means), 22 ... Operation State detection means.

Claims (1)

[Claims] 1. A driving state detecting means for detecting an operating state of the engine; b) knocking signal detecting means for detecting a knocking signal generated in the engine; and c) the intensity of the knocking signal exceeds a predetermined value. When the knocking state is determined, and when the knocking state is not exceeded, when the knocking state is determined by the knocking state determination means, the ignition timing is retarded. Correction amount generation means for generating a retardation correction amount for correcting the knock angle signal, and, when a non-knock state is determined, a correction amount generation means for generating an advance correction amount that increases as the strength of the knocking signal in the non-knock state decreases. ) Ignition that sets a basic ignition timing based on the operating state of the engine and corrects the basic ignition timing based on the output of the correction amount generating means. An ignition timing control device comprising: timing setting means; and f) ignition means for igniting an air-fuel mixture according to the output of the ignition timing setting means.