JPS58172465A - Ignition timing control method of multi-cylinder internal-combustion engine - Google Patents

Abstract

PURPOSE:To control an engine to the optimum ignition timing without causing the inflence due to an external factor, by performing prescribed arithmetic operation so as to obtain an engine speed in the increasing direction from combination of plurally set ignition timings and correcting the combination of the ignition timings. CONSTITUTION:In an ignition control circuit 26 controlling the operation of an ignition device 20, firstly the target ignition timing is calculated from outputs of an intake air amount sensor 16 and speed sensor 18. Then combination of ignition timings having a prescribed value for each cylinder in the vicinity of the target ignition timing is plurally selected to perform both operations for a prescribed period with enach of the combination and two times the operations in at least one ignition timing combination of said operations. Then from change of an operational condition at this operation, an operational condition signal in the other combination is corrected. And in accordance with a level of value showing a condition of deviation unevenness of the operational condition signal only by a combination difference between each ignition timing, whether the operational condition is in an optimum state or not is decided to control the ignition timing combination.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for optimally controlling ignition timing for each cylinder in order to improve fuel consumption in an internal combustion engine.

The ignition timing of an internal combustion engine is generally determined by an average value that maximizes output and minimizes fuel consumption based on engine speed and intake pressure (or intake flow rate). If the engine has multiple cylinders, it is common to use this average common ignition timing for each cylinder. However, due to variations during manufacturing, changes over time, etc., the ignition time that gives the maximum output varies from cylinder to cylinder, and the average ignition time 11 described above is not always optimal for that cylinder, but may cause output loss. Become.

In view of the shortcomings of the prior art, the present invention provides the optimum ignition timing for each cylinder to ensure the maximum output efficiency, without being influenced by factors other than ignition timing, such as the actuator operation. The purpose is to achieve a sum that allows stable control to the optimum ignition timing.

If I explain it below using the drawings, the first wi is the general relationship between ignition timing and engine speed (torque)! This indicates the 11th section, and the engine speed is set to the maximum Hm with a constant operation amount.
Let it be H [Tj! It has one ignition gI# period θ・pt.

This optimum ignition timing θopt usually varies between cylinders. Therefore, for simplicity, the minimum number of multi-cylinder engines is the f-cylinder engine. as,
N cusp,. Qi 1161. When changing the ignition timing of Ijl, the number of revolutions per engine is contoured as shown by the dashed line.
'l tr3...). Therefore, the combination θ@opt of the ignition timings of the respective cylinders forms the peak of the engine speed.

There is #1 opt, and conversely speaking, if each cylinder is driven with this combination of optimal ignition timing, the maximum rotation speed can be obtained.

The present invention uses the method described below to search for a combination of ignition timings for each cylinder that provides the maximum engine speed. First, to explain this method, in Figure 2,
Assume that the ignition timing of the 1st cylinder is set to 01Kt, and the ignition timing of the 2nd cylinder of 9th grade is set to Og, and the engine is operated at this combination of ignition timings (point L) to obtain an engine rotation speed of N1. (Here, θ and #1 refer to the intake air amount (for convenience of explanation later).
It can be thought of as a correction amount for the basic advance angle 0B determined by the engine rotation speed (or intake pressure) and the engine rotation speed. That is, the second
In terms of ignition timing advance, the origin in the diagram is not O but θ1
The value obtained by adding Kol or θ8 becomes the actual advance angle value. ) Next, the ignition timing is changed slightly from the above point (for example, the ignition timing of the first cylinder is slightly increased to Δ0, while the ignition timing of the third cylinder is left unchanged at 01). Operate at the timing combination (01+Δ01, #Y) and let the rotational speed at that time be N1. 'IIK another point 8 (
For example, suppose the ignition timing of cylinder No. 2 is slightly increased by Δ#宾, while the ignition timing of cylinder No. 1 is set to 111N11e), and the rotational speed obtained by operating the combination (#s=#m+Δ01) is Ns. Then, the rotation speed obtained by operating again with the first combination of points is set as N1'. In other words, if the combinations of ignition timings in the case of two cylinders are made into a table, there will be one as follows.

The first eight (i.e., the number of cylinders Wcl is added)
When the average value I of each cylinder is found for the initial ignition timing combinations, the combination of ignition timings (in the example of the 21st jlJ, the rotational speed N1 is L) where the rotational speed is minimized due to the influence of only the ignition timing is searched.

In this case, the combination L with the same ignition timing is
1 After operating for a prescribed period, the difference between the two rotational speeds NS+N, / is considered to be due to a cause other than a change in the ignition timing, such as a change in rotational speed due to the actuator operation, etc. It is assumed that the rotational speed changes linearly in proportion to time.

Then, the rotational speed due to accelerator operation, etc. for each ignition timing combination H, 8 is determined by linear interpolation, and the deviation from the measured rotational speed N, , N, is determined. Next, a value (for example, the sum of the absolute values of the deviations, and this value will be described below) indicating the state of dispersion of these deviations is calculated, and when this value is greater than a predetermined value, only the ignition timing can be determined from this deviation. Find the ignition timing combination L that minimizes the rotation speed in shadow 1.

Next, on the straight line connecting this average value τ and the combination L of ignition timing at the minimum rotational speed NIK, a new point R1 is located opposite to L with respect to IK (in other words, in the direction in which the rotational speed increases).
Set. Then, the combination of ignition timing at this point R1 (
a1' - am'), operate with this combination to obtain the rotation speed N4, further operate with the ignition timing combination of point H to obtain the rotation speed N1', and set this rotation speed N4 to the minimum rotation. By replacing the number N1 with the difference between N and IIJ, /, we get point 8. The rotation speed due to actuation operation etc. in R1 is determined by linear interpolation, and from the deviation between this interpolated value and the actual measurement value, Nl p Of the eight rotation speeds of N3 and N4, the minimum rotation speed (in the figure) is determined by the influence of only the ignition timing. Point H where Nm)
seek. Next, find the average value I of the eight ignition timing combinations, and on the straight line connecting this average value 1' and the point H that gives the minimum rotation speed, the opposite side of the ignition timing combination H that gives the minimum rotation speed (i.e. Direction of increasing rotation speed) K New point 8. Set.

If you repeat this, n lx R, -e Rm
-hR,,R,,R・-1t,-,R, By modifying the ignition timing combination one after another in the direction of increasing the rotational speed, you can reach the peak of the rotational speed. .

The above is a case where the sum of the absolute values of the deviations continues to be equal to or greater than the predetermined value in the process of reaching the peak.

Next, when the pattern shown in the table was completed and the sum of the absolute values of the deviations obtained by the same calculation as above became less than the predetermined value at the 9th stage, the Kubakai operated again ((1,).

1g), Nt') (Ce1 +6g) #N1
) and then replace it with 2 in Table C, which is the ignition timing combination when the memorized measured rotational speed is the most temporally past.
The th combination, i.e. gFj! The engine is operated at J [point H at point H), the rotational speed N, / is obtained, and the same calculation as above is repeated. According to this method, by appropriately setting a predetermined value for determining the size of the sum of the absolute values of the deviations, stable ignition can be achieved without correcting the ignition timing in the direction imposed by the optimum ignition timing for each cylinder. Timing control can be achieved.

FIG. 8 shows how to obtain a new ignition timing combination #new (ie, R) for the basic three points H, 8, and L. In this case, the average value is 1 = l soil μ,
:5・・・・・・・・・(1). In addition, the combination of ignition timing that minimizes the rotation speed is 5m1n (i.e. L)
If the new point to be replaced with is #new, θnew ='l -tx (#min -'I)
−−−・−−−+(2) a=constant.

For convenience of explanation, the 2-air IIK engine has been described above, but even if the engine has more cylinders than this, the ignition timing of each cylinder can be corrected and controlled to maximize the rotational speed based on the same principle.

FIG. 4 shows changes in ignition timing combinations and fluctuations in rotational speed for a four-cylinder engine.

In (a), first operate the engine for a predetermined period with each ignition timing combination from ■ to [F] and the same ignition timing combination Φ' as in ■, and calculate the rotational speeds Nl#Nl' of ■ and ■I. Combinations of each ignition timing from the connecting straight lines ■, ■, ■.

Find the distance (difference in rotational speed ΔN), find the sum of the absolute values of the difference in rotational speed ΔN (Σ1ΔN+), and if this is greater than the predetermined value I, select the combination of ignition timings that minimizes the above-mentioned ΔN (in the figure, ΔN, 0) to the new ignition timing combination ■#. Next, in (b), ■, ■, ■, ■I, ■
Operate the engine with each ignition timing combination Z of ρ and the same ignition timing combination ■I as in ■, calculate ΔN1 and ΣlΔNl for each combination in the same way as above, and if Σ1ΔN1 is larger than the predetermined value, do the same as above. In (e), the combination 0 with the smallest ΔN is modified to 0#, and in (e), ■,
Operation is carried out with the same combinations as Φ′, ■“, ■′, ■“, and ■, and ΔN1 for each combination is calculated as above.
and ΣIANI are determined.

Here, when Σ1ΔNl is smaller than the predetermined value, the engine is operated with the ignition timing combination ■' where the memorized measured rotational speed is the most temporally past, without correcting the combination ■' where ΔN is the smallest. Then, the same calculation as described above is repeated. By repeating this operation, the ignition timing combination can be accurately corrected to the optimum ignition timing combination, and stable ignition timing control at the optimum ignition timing can be ensured. In addition, (d) is ΔN
I will show you how to find it by linear interpolation.
......(8) is required.

Next, the apparatus for implementing the method of the present invention will be described. In FIG. , *8. *4 cylinders ◇Intake air is introduced into each cylinder from the intake manifold 12,
The throttle valve 14 controls the flow rate of this intake air. An air meter 16 is provided upstream of the throttle valve 14 to measure the amount of intake air. Furthermore, air two
Instead of measuring the intake air flow rate using the meter 16, the pressure inside the intake pipe may be measured. Reference numeral 18 denotes a rotational speed sensor, which generates a signal according to the engine rotational speed. A well-known crank angle sensor that generates a pulse signal for each crank angle of the engine can be used as the rotational speed sensor.

go is an ignition device, and its constituent elements are an igniter, a guistributor, and an igniter, and ii! ! 2 to the spark plug electrode of each cylinder.

The ignition control circuit 26 forms an activation signal for the ignition device 20, and has the function of a computer programmed to execute the method described below. are ll1180 each
and 82 to the control circuit g6. The control circuit 26 calculates the ignition timing determined by the combination of the intake air amount and the rotation speed, and outputs an ignition timing signal according to the calculation result to the ignition device via the line 84.

mav4 shows a block diagram of the ignition control circuit 26, and the input boat 42 receives signals from the intake air amount sensor 16 and the rotational speed sensor 18. Mu/
The D converter 40 converts an analysis signal from the intake air amount sensor 16 (or intake pressure sensor) into a digital signal. The output boat 46 serves as a signal gate to the ignition device 20.

The input boat 42 and the output boat 46 are the components of a computer, such as a CPU 48 and a ROM 50.

It is connected to the window M52 via a path 54 and exchanges signals in synchronization with a clock signal from a clock generator 58. - The control circuit 26 is programmed to obtain the optimum ignition timing for each cylinder according to the principle of the present invention as described above, and this will generally be explained in the case of the f cylinder with reference to FIG.
In the first calculation step 8, the ignition timing is (a), (b)
), respectively -1=#IK is set. By driving in this condition, the engine speed changes as shown in (c),
An ignition pulse appears as shown in (e). In this first step, a predetermined ignition pulse near the end 9 of 8 is taken in as shown in (2) and the number of the ignition pulses is counted.
This is referred to as the engine rotation speed N1 at the first step SR. II 1st step 8. Then, the first cylinder company O1 + ΔO
The 1st and 2nd cylinders are left as they are, operated for a predetermined number of ignitions, and the rotational speed N as the number of click pulses between Cf. and Cfend is measured. Step 8 for the same cylinder 3. Measure the rotational speed N. Also, in the fourth step S4, the first
Operate with the same ignition timing combination as step
, / is measured. The ignition timing θ1.01, which is the minimum rotation speed, is calculated based on the average of the rotation speeds measured in this way and the distance from the straight line connecting N1 and N, /, and the new ignition timing 01' is placed on the opposite side. +'l' is taken by the calculation shown in FIG. 8, and similarly, a predetermined ignition operation is performed and the rotational speed N4 is calculated as the number of click pulses (fifth step 8). And the sixth
As step (not shown), the operation is performed with the same ignition timing combination as in the second step S, the rotational speed N,' is measured, and step 8. .

Among the combinations of ignition timings a, S, find the combination of ignition timings that minimizes the rotation speed due to only the ignition timing factor,
This combination of opposite side compression new ignition timing is taken and the process is repeated thereafter.

The general outline of the program for executing the ignition timing control in the present invention has been explained above, and the program will be explained in detail with reference to the flowchart shown in FIG.

First, when the internal combustion engine starts, the program starts at step 1.
From 00, the interrupt processing routine for calculating the ignition timing is executed. Next, in step 101, the intake air amount sensor 16
(or intake pressure sensor), the intake air amount (or intake pressure) detected by the rotation speed sensor 18, and the rotation speed to calculate the basic ignition timing θ door. Specifically, the memory has basic ignition timing mapping for the combination of intake air amount and rotational speed, and calculations of the actually measured intake air amount and rotational speed and the actual basic ignition timing are performed. . In step Loll, it is determined whether the engine is steady or not based on the changing state of the rotational speed and intake negative pressure. If the engine is not steady, the NOK branch is taken and the process goes to step 108.

In 10B, the step counter is i=Q, the ignition number counter is 0f==O, and the clock pulse counter is np=Q.
The flags to be described later are cleared to KEY=Q. Next, in step 104, the start ignition timings are set to the 1st, 2nd, and 3rd positions, respectively.
．． ...--Set for the MIBth cylinder. As explained with reference to Fig. 2, KO@*'1m...0M is a correction amount at the time of high point and is stored according to the intake nitrogen amount (or intake pressure) and rotation speed. The ignition timing is calculated by adding the basic ignition timing calculated in step 101 to this.
05 returns to the main routine.

If it is determined in step 102 that it is steady, the process branches to YE8 and the ignition timings ■l and ■2 are set as described above.

. . . The operation is performed using the combination of iris, and the rotational speed is measured at the first point L in FIG. 2 (that is, at the first step 8m if h in FIG. First, in step 106, the value of counter J, which is cleared for each number of cylinders, is incremented by one for each ignition, and in step 107, it is determined whether the value of J has reached the number M of cylinders. If the value of J has not reached MK, J=IK is cleared in step 108, and if it has not reached MK, the process moves to step 109f. In step 109, the ignition timing ■J is determined for each cylinder by adding the basic advance angle OB and the ignition timing correction amount θJ. Step 110 indicates that the ignition number counter Of is incremented by one for each ignition. In step 111, the number of ignitions Cf is as shown in Fig. 7 (E).
It is determined whether or not Cf@nd. Naturally N at first
OK branch, 117, ignition number Cf is C in Figure 7 (e)
It is determined whether or not it is larger than fo. If NO, it means that the rotation speed measurement period has not started, so call 119.
to return to the main μm line. 117, the number of ignitions Of
The number of ignitions CfeK at which to start measuring the
If it is recognized that the number of ignitions Ct has reached Of@wid, it branches to YIC8, starts the callan F of Klefukuba N at 118, and returns to the main routine [119]. At 112, the count value UP of the Norita Fuku pulse at this time is stored in the memory. This count value represents the engine rotational speed N1 at step SR. Then, at 118, the ignition number counter 10 f = 0, and the four-fukupa μ counter *
Clear p=OK, increment the step counter by 1, set the next ignition timing, and operate at point H in Figure 2 until the 'l! In terms of I, the second step 81 is entered.

First, in step 114, it is determined whether the number is 15M or not.

At this time, since i=l, the ignition timing correction amount for each cylinder is set as follows in step 115. (In Figures 2 and 7, in the second step, the ignition timing of the first cylinder is moved by Δθ11"Δ0,
The second cylinder is explained as it is, that is, Δθml"0, but Δθ□1 does not have to be O.) The main routine is returned to in step 116. When the interrupt is entered again from step 100, the first step Same as 106,107,1
This second step 8.09,110°111.117,118,119. The engine rotational speed N, at is measured as the number of clock pulses and the result is stored in the memory in step 112. Thereafter, in step 118, the ignition number counter Cf and the clock pulse counter np are cleared, and the step counter i is incremented by one, and the program enters the third step.

First, in step 114, the determination is still YES in the case of two cylinders, and in step 115, the ignition timing correction amount is set. then 11
After returning to the main routine at step 8, interrupt this program again at step 100, perform the processing from step 106 onwards, and convert the measurement of engine speed N1 at step 8, 8sK, into the form of count value P of clock pass μ. 1111
to store it in memory.

In the next step 114, it is determined whether 1≦older. In case of 2 cylinders, start here, NOK branch, step Ig
At O, it is determined whether or not 7KEY=0. In this case l
Y: o, advance step MIIK, KEY=I
After setting K, in the next step 18ffi, the same correction amount as the first combination of each ignition timing combination whose rotational speed is compared (in this case: , ′:::・, Ichiho +++ , # in step 104) If the engine is a 2-cylinder engine, set the value to 2 and return to the main routine.

Next, when step 120 is reached again, since KEY=1, the NO [branch occurs, and after setting the KEY: OK stage at l21, each ignition timing combination K explained in FIG. 4 is set at step 12g. The rotational speed change ΔN is calculated from equation (3). In step 12B, the sum of absolute values (Σ1ΔN+) of the rotational speed change ΔN is calculated, and in step 124, Σ1ΔN1
is compared with a predetermined value, and if it is larger, the process branches to 125, and the minimum step i=min of the rotational speed change ΔN is determined.

In the next step K126, the average ignition timing 1 is calculated at the (1st) step.
) formula, K. Since this equation is in vector representation, the (
(Conversion), (5), and (6) are calculated for each cylinder component. Then, in step 127, a new ignition timing θnew for increasing the rotational speed is calculated based on this average ignition timing using the second formula (%). Since this equation book vector representation, the (4th
, (5) and (6) Calculate the new ignition timing for each component of equations? Next, in step 128, this new ignition timing θ
The combination θ of ignition timing that constitutes the minimum rotational speed change is new
Shout n (i.e. '1 w#l e in the ((trans)) expression
”...0M).Then, in step 129, set the ignition timing correction amount for each component and 0!

0□, . . . , 0M is obtained, and the process returns to the main routine at step 180.

When the new ignition timing combination is set in this way, the fifth step in FIG. 7 is changed to 10fi, 1 in FIG.
The routines 07, 109, 110, 111, 117, and 118 are executed, and the rotational speed N4 is measured. After that, branching from step 111, 114, 120, 1
After passing through 31 and operating at window 18 with the same correction amount as in the second step, the rotational speed N and I are measured.
Then, as described above, the combination of ignition timings with the minimum rotational speed change ΔN is replaced with a combination in the direction of increasing the rotational speed. After that, the same process is repeated and the peak of the rotation speed is accurate & Cl1
I can be admired. And, at the time of the ultimate race, it was Ste.

Σ1ΔN1 in Pl 2BK becomes smaller by a predetermined value, and the process branches to step 1.91 based on the determination in 1g4.
After setting KEY=1, set the same correction amount as the first combination (meaning that the measured rotational speed is the most temporally past) among the ignition timing combinations compared at 182, and return to the main routine.

If it continues to be determined in step Ig4 that the rotational speed is small, the rotational speed will not be corrected in the wrong direction when it reaches its peak.

In the above-mentioned embodiment, the judgment as to whether or not to calculate the new ignition timing combination was made based on the sum of the absolute values of the corrected rotational speed deviations for each ignition timing combination. A similar effect can be obtained by using a value (as long as it can accurately represent the rotational speed fluctuation due to a change in ignition timing).

Further, the predetermined value K, which determines the magnitude of the value indicating the state of variation in the deviation of the rotational speed, may be changed in accordance with parameters indicating the operating state, such as the engine rotational speed and the intake negative pressure.

As described above, the present invention sets a plurality of ignition timing combinations for each cylinder, performs predetermined calculations to correct the ignition timing combinations so that the engine speed increases from these combinations, This is to obtain the combination of ignition timing for each cylinder that maximizes the engine speed in each operating state,
Il# is operated for two days with at least one ignition timing combination, and the operating status signal tube for each ignition timing combination K is corrected based on the difference in operating status signals such as rotation speed during these two operations. Therefore, it is possible to control the optimum ignition timing without being influenced by external factors such as actuator operation, and the magnitude of the value indicating the dispersion state of the deviation of the operating condition signal due only to the ignition timing change. Since it determines whether the operating condition is optimal or not and controls the combination of ignition timing according to 1. Has excellent effects

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between ignition timing and engine speed. Figure 3 is a contour diagram showing changes in engine speed with respect to ignition timing combinations in the case of Jh two cylinders; 4 (a), (b), (cl is a diagram showing changes in combinations of ignition timing, a1411 (d) is a diagram showing a method of calculating the rotation speed, 5gJ is a diagram showing the configuration of an internal combustion engine according to the present invention , FIG. 6 is a configuration diagram of the control circuit in FIG. 4, FIG. 7 is a timing diagram showing the concept of calculation processing in the present invention, and FIG. 8 is a flowchart showing the ignition timing calculation processing procedure in the present invention. lO-- Engine body, 16... Intake air amount sensor, 18... Engine rotation speed sensor, 20... Ignition device, g6... Control circuit. Attorney Takashi Okabe Figure 1 2nd Figure 7'-ゝ~ #1N#I Advance angle Figure 3 Machikibori 1 Mukuro period Figure 5

Claims (1)

[Claims] (11 Select a plurality of combinations of ignition timings having a predetermined value for each cylinder in the vicinity of the target ignition timing, and perform a predetermined rotation of Jl11m11 one after another with each selected combination of ignition timings. A combination K of at least one ignition timing among the combinations of the plurality of ignition timings is carried out t-g times, and during each of these operations, an operating state signal such as the engine rotation speed is detected, The difference in the operating status signals for the ignition timing combinations of the eight operations performed is determined, and from this difference the operating status signals for other ignition timing combinations are corrected to account for only the differences in each ignition timing combination. Determining the deviation of each of the operating state signal quantities, and comparing the respective operating state signals when the value indicating the dispersion state of the deviation is larger than a predetermined value for determining whether or not the operating state Hc is close to the optimum operating state. The combination of ignition timings that results in an operating state farthest from the optimal operating state determined by An ignition timing control method for a multi-cylinder internal combustion engine, characterized in that one of the plurality of ignition timing combinations is set as the next ignition timing combination without calculating a suitable ignition timing combination. (2) Each of the above-mentioned operations. The ignition timing control method for a multi-cylinder internal combustion engine described in claim I8!, paragraph 1, wherein the value indicating the state of variation in the deviation between states is the sum or average value of the absolute values of the deviations. .