JPS58126464A - Ignition timing control method for multi-cylinder internal-combustion engine - Google Patents

Abstract

PURPOSE:To obtain earlier the optimum ignition timing for each cylinder, in a method for optimum control of ignition timing so that the number of revolutions of the engine becomes maximum, by changing over the change amount of ignition timing from the change amount for all cylinders to that for individual cylinder. CONSTITUTION:In the process from initial setting of three fundamental points L, H and S to R1, R2..., R6, the optimum ignition timing as average of all cylinders is sought by giving a change amount of ignition timing to be applied to all cylindes. Then in the process from initial setting of L'(R6), H', S' to R1', R2'... R5, such an operation is made as due to the modification amount of ignition timing specified for individual cylinder, and the final optimum ignition timing for each cylinder is determined. Thereby the optimum ignition timing for individual cylinder can be sought in earlier stage.

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 a multi-cylinder internal combustion engine.

The ignition timing of an internal combustion engine is generally determined by setting the engine speed and intake pressure (or intake flow rate) to average values that maximize output and minimize fuel consumption. If the engine has multiple cylinders, it is common to use this average common ignition timing for each cylinder. However, the ignition timing that provides the maximum output varies from cylinder to cylinder due to variations during manufacturing, changes over time, etc., and the average ignition timing described above is not necessarily optimal for that cylinder, causing output loss.

In view of the shortcomings of the prior art, the present invention aims to always ensure the maximum output efficiency by giving the optimum ignition timing to each cylinder, and to smoothly converge to the ignition timing that provides the optimum operating state. purpose.

To explain the following using drawings, Figure 1 shows the general relationship between ignition timing and engine speed (torque). . And this optimal ignition timing 0op
Normally, t varies between cylinders. Therefore, for simplicity, if we consider a two-cylinder engine, which is the smallest multi-cylinder engine, each cylinder #1. When the ignition timing of $2 is changed, the engine speed changes as shown by contour lines rI rr2 , r31 . . . as shown by the broken line. Therefore, there is a combination of ignition timings θ1opt and θ20Pt for each cylinder that forms the peak of the engine speed.Conversely, if each cylinder is driven with this combination of optimal ignition timings, the maximum rotational speed ( torque) 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 the principle of this method, in Fig. 2, the ignition timing of the #l cylinder is set to θ1 and the ignition timing of the #2 cylinder is set to 02, and this ignition timing combination (point L) is used for a predetermined period (for example, 20 rotations) to obtain N1 as the engine rotation speed. (Here, 01, θ2
For convenience of explanation later, it should be thought of as a correction amount for the basic advance angle θB determined by the intake air scene (or intake pressure) and the engine rotation speed. In other words, the origin in Fig. 2 is not 0 but θB in terms of ignition timing advance, and 0
The value obtained by adding 1 or θ2 becomes the actual advance angle value. ) Next, the ignition timing at point H is slightly different from the above-mentioned ignition timing (for example, the ignition timing of the #l cylinder is slightly increased by Δθ, while the ignition timing θ2 of the #2 cylinder is left unchanged at 1). A combination of (
θ1 + Δθ, θ2), and the rotational speed at that time is N2
shall be. Furthermore, at another point 8 (for example, the ignition timing of the #2 cylinder is slightly increased by Δθ, while the ignition timing of the #l cylinder is increased by θ1).
Let N3 be the number of rotations obtained by operating with the combination (01, θ2+Δθ). In other words, if the combinations of ignition timings in the case of two cylinders are made into a table, the following Table 1 will be shown.

Table 1 Next, find the average value pf for each cylinder in these three (i.e., the number of cylinders plus 1) initial ignition timing combinations, and calculate the ignition timing combination that minimizes the rotational speed (see Figure 2). In the example, search for L) that gives the rotational speed N□. Then, on a straight line connecting this average value T and the ignition timing combination L at the minimum rotational speed N1, a new point R1 is set on the opposite side of the stone to L (in other words, in the direction in which the rotational speed increases). Then, the combination of ignition timings at this point R1 (θ1+Δθ).

02 + Δθ), operate with this combination, replace the rotation speed N4 at that time with the minimum rotation speed N1, and set N2
, N3, and N4 to find the point S at which the minimum number of revolutions (N3 in the figure) is found, and also find the average value W' of the eight ignition timing combinations, and calculate this average value r' and the minimum revolution number. A new point It2 is set directly on the opposite side of the ignition timing combination S that results in the minimum rotational speed (that is, in the direction in which the rotational speed increases) directly connected to the point S that corresponds to the number of rotations.

If you repeat this, R1 → 几2 → R3 → R4 → R
By successively correcting the combination of ignition timings in the direction of increasing the rotational speed, such as 5→R6→R1→R8, the peak of the rotational speed can be reached.

FIG. 8 shows how to obtain a new ignition timing combination θnew (ie, R) for the basic eight points H, 8, and L. In this case, the average value is expressed as vec)/Ly. In addition, the ignition timing combination that minimizes the rotation speed is 6m in
(In other words, L), if the new point to be replaced with θnflW is θn ew = (j −a (6min −(
j ) -----121α is the constant.

However, since the change in rotation speed associated with a change in the ignition timing of only one cylinder is small, the ignition timing may be corrected in the opposite direction, and if the amount of change in the ignition timing is changed for each cylinder, The operating period until convergence to the optimum ignition timing becomes longer, and as a result, the speed of searching for the optimum ignition timing for each saturated cylinder becomes slower.

Therefore, in the present invention, an operation in which the ignition timing is changed by the amount in the direction of all cylinders (see Table 2) is performed for a predetermined time (from the start of the ignition timing feedback control described above), and then the amount of change is set for each cylinder. By performing operation using combinations of ignition timings, we first search for the average optimum ignition timing for all cylinders, and
A different combination of ignition timings is set for each cylinder at that point, and the optimum ignition timing for each cylinder is finally determined.

As described above, by switching from ignition timing control in which the amount of change in ignition timing is based on all cylinders to ignition timing control for each cylinder, the optimal ignition timing for each cylinder can be searched for more quickly.

Table 2 The above description has been about a two-cylinder engine for convenience of explanation, but even in engines with more cylinders, the ignition timing of each cylinder can be corrected and controlled to maximize the rotational speed using the same principle. I can do it.

Next, an apparatus for implementing the method of the present invention will be described. In Fig. 4, 10 is the main body of the internal combustion engine, in this case #
1. $2. +8. It has 4 cylinders of $4. Intake air is introduced into each cylinder from the intake manifold 12, and
The zero-tuttle valve 14 controls the flow rate of this intake air. An air flow meter 16 is provided upstream of the throttle valve 14 to measure the amount of intake air. Note that instead of measuring the intake air flow rate using the air flow meter 16, the pressure inside the intake pipe may be measured. A rotation sensor 18 generates a signal according to the rotation of the engine.

As a rotation sensor, it measures the crank angle of the engine.
v7. Any known crank angle sensor that generates a signal can be used.

Reference numeral 20 denotes an ignition device, which consists of an igniter, a distributor, and an ibunirasilane coil, and is connected to the ignition plug electrode of each cylinder via a wire 22.

The ignition control circuit 26 forms an activation signal for the ignition device 2o, and has the function of a computer programmed to carry out the method described below. Intake air amount sensor 16 and rotation sensor 18 are connected to control circuit 26 via lines 80 and 32, respectively. The ignition control circuit 26 calculates the ignition timing determined by the combination of the intake air amount and the rotational speed, and sends an ignition timing signal corresponding to the calculation result to the line 34.
Output to the ignition device via.

FIG. 5 shows a block diagram of the ignition control circuit 26, in which the input port 42 is connected to the intake air amount sensor 1.
6 and the rotation speed sensor 18. A/D
Converter 4o converts an analog signal from intake air i sensor 16 (or intake pressure sensor) into a digital signal. Output port 46 serves as a signal gate to igniter 20. The input port 42 and the output port 46 are the components of the computer, such as a CPU 413 and a ROM 50.
, are connected to the RAM 52 via a path 54, and exchange signals in synchronization with a clock signal from a clock generator 58.

The ignition control circuit 26 is programmed to obtain the optimum ignition timing for each cylinder according to the principles of the present invention described above. The average optimum ignition timing for all cylinders is searched for by combining the two ignition timings. That is, in the first calculation step S1, the ignition timing is set as θl and θ, respectively.
Set to 2. By driving in this condition? -4
The engine speed changes as shown, and the ignition pulse appears as shown in the direction.

During the predetermined ignition pulse near the end of this 17th step 8,
The clock pulses are taken in from fo to Of and, and the number thereof is counted, and this is set as the engine rotational speed N1 at the first step 81. In the second step 82, the first cylinder is set to θ1+Δ0, the second cylinder is set to 02+Δ0,
Similarly, the engine is operated a predetermined number of times, and the rotational speed N2 as the number of clock pulses between Cfo and Cf and is measured. Similarly, the rotation speed N3 in the eighth step S3 is measured. Take the average of the rotational speeds measured in this way, and calculate the new ignition timing q1', θ□' on the opposite side of the minimum rotational speed using the calculation described in Fig. 3. Similarly, perform the prescribed ignition operation and set the rotational speed N4. is measured as the number of clock pulses. This will be repeated below.

After a predetermined period of time has elapsed, the optimal ignition timing for each cylinder is searched for in the same way as described above using the ignition timing combinations shown in Table 1.

Now that the lenient aspects of the ignition timing control in the present invention have been explained above, the details will be explained with reference to the flowchart of FIG. 7.

First, when the internal combustion engine starts, the program starts at step (11).
) The knob 100 executes this ignition timing calculation interrupt processing routine. Next, in step 101, the basic ignition timing θB is calculated from the intake air amount (or intake pressure) detected by the intake air amount sensor 16 (or intake pressure sensor) and the rotation speed sensor 18 and the rotation speed.

Specifically, the memory stores basic ignition timing mapping for combinations of intake air amount and rotational speed, and the basic ignition timing is calculated based on the actually measured intake air amount and rotational speed. In step 102, it is determined whether the engine is steady based on the changing state of the rotational speed and intake negative pressure. If the engine is not steady, the process branches to NO and goes to step 108. In 108, the step Karagata is i=0,
The ignition number counter is cleared to Cf-0, the clock pulse counter is cleared to np:Q, and a flag to be described later is cleared to KEY=0. Next, in step 104, the start ignition timing is set to 1, 2, 8, . ...Set (12) for the Mth cylinder. Here, θl, θ2...0M are the correction amounts for the ignition timing, which are stored in accordance with the intake air amount (or intake pressure) and the rotational speed, as explained with reference to Fig. 2. The ignition timing is calculated by adding the basic ignition timing calculated in step 101. ]0
Step 5 returns to the main routine.

If it is determined in step 102 that it is steady, the branch goes to YES and the ignition timing [phase] 1.0□ is set as described above.

The operation is performed using the combination ◎y, and the rotational speed is measured at the first point L in FIG. 2 (that is, the first Nutep 8□ in FIG. 6). First, step.

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 reached M, it is cleared to J=1 in step 108, and if it has not reached M, the process moves to step 109. In step 109, the ignition timing ◎ for each cylinder is based on the addition of the basic advance angle θB and the ignition timing correction amount OJ. Step 11
0 indicates that the ignition number counter Of is incremented by one for each ignition. In step 111, it is determined whether or not the number of ignitions Of is 0fend (see FIG. 6). At first, it naturally branches to NO, and at step 120 it is determined whether the number of ignitions Of is greater than CfO in FIG. 6...). If NO, this indicates that the rotational speed measurement period has not yet entered, and the process returns to the main routine at step 122. At step 120, if it is recognized that the number of ignitions Of has reached the number of ignitions Ofo at which clock pulse measurement should be started, the process branches to YES;
After starting the clock pulse count at step 1, the process returns to the main routine at step 122.

If it is determined in step 111 that the number of ignitions Of has reached 0fend, then in 112 the clock pulse count value np at this time is stored in the memory.

This count value represents the engine rotational speed N1 at step 81 in FIG. Then, at 118, the ignition number counter is set to 0f=0, clock bar! Clear the 7 counter in p=o and clear the 7 step counter ei=j+
The next ignition timing is set by adding 1 to 1, and the operation at point H in FIG. 2 is performed, and the second step 82 in FIG. 6 is entered.

First, in step 114, it is determined whether the number is 16M or not. At this time, since 1=1, the process branches to YES, and in step 115 it is determined whether the flag KEY is O or not. At first, KEY...
Since =0, the amount of correction of the ignition timing of each cylinder is set as follows. In step 117, the process returns to the main μm process. When the interrupt is entered again from step 100, the first
Same as step 106.107°109.110,11
1, 120, 121, 122 (15) The engine rotation speed N2 in this second step S2 is measured as the number of clock pulses, and the result is 112.
is stored in memory in steps.

Thereafter, in step 118, the ignition number counter Cf,
The clock pulse counter np is cleared and the step counter 1 is incremented by one, and the process enters the third inverter. ′
-'1 First, in 114, it is still determined as JES even in the case of two cylinders, and in 115, since KEY=0, it branches to YES, and in 116, the ignition timing correction amount is set. then 1
After returning to the main routine at 17, interrupt this program again at 100, perform the processing from 106 onwards as before,
This eighth step 8. The engine rotational speed N3 is measured in the form of a clock bar/l/7- count value npO, and is stored in the memory in step 112.

(16) Next, in step 114, it is determined whether i≦M. In the case of two cylinders, the process branches to No at this point, and in step 128, a search is made for the step +=min that minimizes the rotation speed in the rotation speed measurement step 1. (If the number of cylinders is greater than this, it branches to step 115 at the trench where the ignition timing is set by adding 1 to the number of cylinders.) Next, in step 124, step i is larger than i M A Determine whether or not. At first, the process naturally branches to NO, and in step 125, the average ignition timing is calculated using the equation α). Since this formula is in vector representation, +8+, +41
, +51 for each cylinder component. Then, at step 126, a new ignition timing One is calculated based on this average ignition timing using the second formula (%). Since this formula is also expressed as a vector, C3
Calculate the new ignition timing for each component of formulas 1, +41, and +51. Next, at 127, this new ignition timing θnew is determined by the combination of ignition timings that constitutes the minimum rotational speed (NI in the case of FIG. 2) (ie, 01 in equation (8)).

02 , ..., 0M). And 128
In step 1, set the ignition timing correction amount for each component to obtain ・01 ・02 r"°゛・OM, and return to the main frequency at step 129.

Thereafter, if it continues to branch to YES at the steady state determination of 102, the number of steps 1 exceeds i M A X f at 124. In that case, it branches to YES for the first time at 124, and for the first time K
Since EY=0, the process branches to 182, sets KEY=l and i=0, and returns to the main routine at 133. (The above process is shown in L and H in Fig. 8, which shows the changes in the ignition timing of each cylinder.

This is an explanation from the initial set of S to B-1, . . . R6). So interrupt this program again at 100,
If it is determined that the temperature is still steady at 1O2, the process proceeds to step 115 through the same process as described above.

At this time, since i=l and KEY=1, the process branches to 118, and the ignition timing correction amount for each cylinder is set to obtain a different ignition timing combination for each cylinder.

(In Table 1, the ignition timing of the #l cylinder is moved by Δq1=Δθ in the second step, and the #2 cylinder remains unchanged, that is, Δ
Although the explanation is given with θ2=0, Δθ2□ does not have to be 0). Then, the ignition timing is set until the branch is NO in step 114. After that, e/new is calculated in exactly the same manner as the calculation described above, and the ignition timing correction amount is set.

This process is shown in Figure 8 as L'(BB), H',
From the beginning of S'! ′,..., this is the explanation up to 9′. Thereafter, the same process is repeated until the peak of the number of rotations is reached.

In the above embodiment, all cylinders are operated with the same ignition timing correction amount for a predetermined period of time from the start of ignition timing feedback control, and thereafter, operation is performed with the ignition timing correction amount determined for each cylinder. , operation with the same amount of ignition timing correction for all cylinders is continued until the optimum ignition timing is obtained, and at that point it is switched to operation with the amount of ignition timing correction determined for each cylinder. It's okay. In other words, in the case of a two-cylinder engine, the engine is operated with the ignition timing combinations shown in Table 2, and the ignition timing combination with the lowest rotation speed is replaced with the new ignition timing combination determined by equation (2). Among the ignition timing combinations of the number of cylinders plus 1, if the rotation speed in the newly replaced ignition timing combination is the smallest, then the cylinders with the ignition timing combinations in Table 1 are The optimum ignition timing for each engine is determined.

As described above, the present invention sets a plurality of combinations of ignition timing for each cylinder, and sets the operating state farthest from the optimal operating state where the rotational speed (l-μ) is the largest among the combinations. This method performs feedback control of the ignition timing in such a way that a combination of ignition timings is determined, and this combination is corrected to a new combination of ignition timings to obtain a combination of ignition timings that provides the optimum operating condition. The amount of correction to the ignition timing combination is set at the start of the ignition timing feedback control and for a predetermined period of time.
9) Since the setting is made for each cylinder after that, it is possible to accelerate the convergence to the optimal ignition timing for each cylinder that provides the optimal operating condition as described above, and to operate the engine efficiently. It has the excellent effect of being able to

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between ignition timing and engine speed, Figure 2 is a diagram showing the search process for the optimal ignition timing in the case of two cylinders, and Figure 3 is a diagram showing the relationship between ignition timing and engine speed. A diagram showing a method of determining a new ignition timing to increase the engine speed from a combination of ignition timings, FIG. 4 is a configuration diagram of an internal combustion engine according to the present invention, and FIG.
The configuration diagram of the ignition control circuit in the figure, FIG. 6 is a timing diagram showing the concept of calculation processing in the present invention, FIG. 7 is a flowchart showing the calculation processing procedure of ignition timing in the present invention, and FIG. FIG. 3 is a diagram showing a process of searching for optimal ignition timing. DESCRIPTION OF SYMBOLS 10... Engine body, 16... Intake air amount sensor, 18... Engine rotation sensor, 20... Ignition device, 26... Ignition control circuit. Representative Patent Attorney Takashi Okabe Diagram 1 Retard angle 0゜, t flag odor history planting period Diagram 2 Diagram 3 ■ @4 Diagram 1 meeting, Xi 1 within

Claims (1)

[Claims] ■Select multiple ignition timing combinations with predetermined values for each cylinder near the target ignition timing, operate for a predetermined period one after another with each selected ignition timing combination, and during each of these operations, the engine By detecting operating state signals such as the rotational speed of the engine and comparing the detection signals for each of the ignition timing combinations, the ignition timing combination that results in the operating state farthest from the optimum operating state is determined. An ignition timing control method that changes a combination of ignition timings to a new combination of ignition timings and corrects the combination of ignition timings in a direction that provides an optimal operating condition, the method comprising: correcting the ignition timings in the combination of ignition timings; The amount is set to the same value for all cylinders or a value set for each cylinder, and for a predetermined period from the start of the ignition timing control.
Ignition timing of a multi-cylinder internal combustion engine, characterized in that an operation is performed using a combination of ignition timings in which the correction amount is the same for all cylinders, and then an operation is performed using a combination of ignition timings in which the correction amount is set for each cylinder. Control method.