JP2999778B2 - Ignition timing learning control method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing learning control method for performing optimal control while learning an ignition timing in each operation region in a vehicle engine, and more particularly, to learning control and knocking feedback. The present invention relates to an apparatus that uses control in combination.

[Conventional technology]

In the ignition timing learning control, the learning correction amount is updated to the retard side or the advance side in relation to the presence or absence of knocking, and the advance or retard amount of the learning control is determined by the variation of the ignition timing. In order to stabilize combustion by suppressing the octane value of the fuel and stably maintain the actual knocking limit in accordance with the octane value when the octane value changes, the value is relatively small and has little variation. Therefore,
When knocking occurs, the learning correction amount is gradually retarded.

If knocking occurs, knocking is likely to occur continuously due to an increase in engine temperature. In this case, the retard amount is insufficient with only the small learning correction amount described above, and the risk of knocking occurring after the second time increases. In view of this, a knocking feedback correction amount having a value larger than one learning delay amount of the learning correction amount is separately provided, and when knocking occurs, the knocking feedback correction amount is greatly retarded to effectively prevent the second and subsequent knocking occurrences. It is thought that.

Therefore, conventionally, as for the combination of the learning control and the knocking feedback control, there is, for example, Japanese Patent Application Laid-Open No. 61-16272 (hereinafter referred to as "first prior art"). Here, the knocking feedback correction amount is updated and stored in the learning table of the corresponding operating state as a learning correction amount during a steady state,
It is shown that the occurrence of knocking in the next same operation state is prevented.

Japanese Patent Application Laid-Open No. 59-103964 (hereinafter referred to as "second prior art") discloses a basic ignition advance (basic ignition timing) based on an engine operating state based on an engine speed and a load.
θBASE is set, and the basic ignition timing θBASE is corrected by the learning retardation amount θKG and the correction retardation amount (knock feedback correction amount) θK for delay correction when knocking occurs, and the ignition advance angle (final It is disclosed to set an ignition timing) θig.

The learning retard amount θKG is learned according to the value of the correction retard amount (knock feedback correction amount) θK.

More specifically, the learning retard amount θKG is a predetermined crank angle (0.04 ° C.) when the correction retard amount (knock feedback correction amount) θK is smaller than the first predetermined crank angle (2 ° CA).
A) The subtraction learning is performed, and when the corrected retard amount θK is equal to or larger than the second predetermined crank angle (4 CA), the predetermined crank angle addition learning is performed, and the retard correction amount θK is determined by the first and second predetermined crank angles. When a value within a predetermined range is obtained, learning is stopped.

[Problems to be solved by the invention]

However, in the first prior example, since the knocking feedback correction amount is rewritten to the learning correction amount, the advance angle by knocking feedback control,
The variation of the learning value increases with the repetition of the retardation. Here, knocking occurs due to various causes, and knocking does not always occur even in the same operating state as the previous time. If there is no knocking, it is necessary to greatly update the learning value, which leads to deterioration of flammability and output, and the cost for preventing knocking becomes too great.

In the second prior example, the learning retardation amount θKG
Is the correction delay amount (knock feedback correction amount) θ
It is learned according to the value of K, and is not directly learned according to the presence or absence of knocking. Further, since the learning retardation amount θKG is learned according to the value of the correction retardation amount (knock feedback correction amount) θK, the retardation is not always corrected even when knocking occurs.

That is, in the second prior example, the knocking feedback correction amount is rewritten to the learning correction amount in the same manner as in the first preceding example. Therefore, the learning is performed by repeating the advance and the retard by the knocking feedback control. There is an inconvenience that stable learning cannot be performed due to a large value variation.

Further, the learning retard amount θKG in the second prior example is learned according to the value of the correction retard amount (knock feedback correction amount) θK, so that even if knocking occurs, the retardation is corrected. Therefore, even if the basic ignition timing is corrected by the learning retardation amount and the correction retardation amount (knock feedback correction amount) when knocking occurs, the final ignition timing can be greatly retarded at once. In addition, the occurrence of knocking after the second time cannot always be effectively prevented.

Further, since the learning retardation amount θKG is learned in accordance with the value of the correction retardation amount (knock feedback correction amount) θK, the mutual interference between the ignition timing learning control and the knocking feedback control after knocking is eliminated. Occurs, the correction retard amount (knock feedback correction amount) θ
For example, the learning retardation amount θKG is unnecessarily advanced in accordance with the retardation amount due to K, so that the ignition timing is destabilized due to mutual interference, and the inconvenience that the ignition timing controllability deteriorates also arises.

The present invention has been made in view of such a point. An object of the present invention is to use a learning control and a knocking feedback control in combination so that the learning correction amount is always kept small, and the knocking is effectively performed at the second time. An object of the present invention is to provide an ignition timing learning control method capable of preventing the occurrence of subsequent knocking.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, a basic ignition timing set on the basis of an engine operating state is adjusted according to the presence or absence of knocking, and a learning correction amount for learning a retard angle and an advance angle; In the ignition timing learning control method for setting a final ignition timing by correcting with a knocking feedback correction amount that is retarded when it occurs, the learning correction amount is retarded with a first retardation amount when knocking occurs. At the same time, the knocking feedback correction amount is retarded by the second retardation amount, and after knocking is eliminated, the knocking feedback correction amount is gradually corrected to the advance side until the knocking feedback correction amount becomes zero by the advancement amount. Until the knocking feedback correction amount becomes zero, learning of the learning correction amount is prohibited, knocking is eliminated, and the knocking feedback is eliminated. When the back correction amount is zero, the learning of the learning correction amount on the advance side is restarted, and the knocking feedback correction amount and the learning correction amount are added to the basic ignition timing set based on the engine operating state, and finally It is characterized by setting an appropriate ignition timing.

According to a second aspect of the present invention, in the first aspect of the invention, a basic ignition timing and an advance limit given by an advance amount with respect to the basic ignition timing are set based on an engine operating state, and the learning correction is performed. When the addition value of the amount and the knocking feedback correction amount is smaller than the advance angle limit, the final ignition timing is set by adding the knocking feedback correction amount and the learning correction amount to the basic ignition timing, When the addition value is equal to or greater than the advance limit, the final ignition timing is set by adding the advance limit to the basic ignition timing set based on the engine operating state.

According to a third aspect of the present invention, in the first or second aspect, the second retardation amount is set to a retardation amount larger than the first retardation amount.

[Action]

According to the first aspect of the present invention, the basic ignition timing set based on the engine operating state is retarded and advanced according to the presence or absence of knocking, and a learning correction amount, and a retardation correction is performed when knocking occurs. Feedback correction amount is added to set the final ignition timing.
When knocking occurs, the learning correction amount learned according to the presence or absence of knocking is retarded by the first retardation amount, and the knocking feedback correction amount is changed to the second.
The final ignition timing is set by adding the retarded corrected learning correction amount and the knocking feedback correction amount to the basic ignition timing, thereby setting the final ignition timing. Is greatly retarded, and the occurrence of knocking after the second time is effectively prevented.

Then, after the knocking is eliminated, the knocking feedback correction amount is gradually corrected to the advance side until the knocking feedback correction amount becomes zero by the advance amount, and the learning correction is performed until the knocking feedback correction amount becomes zero. When the knocking is eliminated and the knocking feedback correction amount becomes zero, learning of the learning correction amount to the advanced side is restarted, and the basic ignition set based on the engine operating state is prohibited. The final ignition timing is set by adding the knocking feedback correction amount and the learning correction amount to the timing. Therefore, after the knocking is eliminated, the learning control of the ignition timing and the knocking feedback control can be surely separated to keep the variation of the learning correction amount small,
Further, it is possible to prevent mutual interference between the learning control of the ignition timing and the knocking feedback control.

According to the second aspect of the present invention, a basic ignition timing and an advance limit given by an advance amount with respect to the basic ignition timing are set based on an engine operating state. When setting the final ignition timing, if the added value of the learning correction amount and the knocking feedback correction amount is smaller than the advancement limit and cannot take the advancement limit, the knocking feedback correction is performed on the basic ignition timing. The final ignition timing is set by adding the amount and the learning correction amount. On the other hand, when the added value is in the range where the advance limit is equal to or greater than the advance limit, the final ignition timing is set by adding the advance limit to the basic ignition timing set based on the engine operating state.

In this case, according to the third aspect of the invention, the second retardation amount is set to a retardation amount larger than the first retardation amount.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 2, an outline of an engine to which the present invention is applied will be described. Reference numeral 1 denotes an engine main body. An intake valve 4 is provided in an intake port 3 communicating with the combustion chamber 2, an exhaust valve 6 is provided in an exhaust port 5, and a spark plug 7 is attached to the combustion chamber 2. Air cleaner 8 as intake system
Is a throttle body having an intake pipe 9 and a throttle valve 10.
11, the intake port 3 communicates with the intake port 3 via the intake manifold 12, and the exhaust port 5 communicates with the exhaust pipe 13 as an exhaust system. Idle control valve 14 bypassing throttle valve 10
Is provided, and an injector 16 is attached to the inlet of the suction port 3 in a multipoint manner.

The control system includes a crank angle sensor 20 and a pressure sensor 21 downstream of the throttle valve 10. These sensor signals are input to the control unit 30 and the engine speed Ne is determined by the crank angle.
The suction pipe pressure Pm is detected by the pressure downstream of the throttle valve 10, and the basic fuel injection amount Tp is determined by the engine speed Ne and the suction pipe pressure Pm. Also, the water temperature of the water temperature sensor 22 is
Tw, intake air temperature Ta of the intake air temperature sensor 23, even if the signal such as the O ₂ sensor 24 is input to the control unit 30, in addition to various corrections to the basic fuel injection amount Tp is calculated fuel injection amount Ti by these signals, the fuel A fuel injection signal having a pulse width corresponding to the injection amount Ti is output to the injector 16, and fuel is injected according to each operation state. The opening of the throttle valve 10 is detected by a throttle opening sensor 25. If the throttle opening (or idle switch) is determined to be idling, the opening of the idle control valve 14 is adjusted, and the engine speed Ne is adjusted.
Is feedback-controlled to a predetermined idle speed. Further, as the ignition system, the above-described engine speed Ne, suction pipe negative pressure P
The basic ignition timing, advance angle limit, and the like are obtained from m, and the retard or advance angle is corrected based on the presence or absence of knock detection by the knock sensor 26 attached to the engine body 1, and the optimum ignition timing IGT is learned and determined. Then, an ignition signal corresponding to the optimum ignition timing IGT is output to the ignition plug 7 via the igniter 27, the ignition coil 28, and the distributor 29, so that ignition and combustion are performed at a predetermined crank angle before the piston top dead center. .

FIG. 1 illustrates the ignition timing learning control system of the above-described ignition system.

First, the ignition timing setting control system will be described. The signals of the crank angle sensor 20, the pressure sensor 21, the water temperature sensor 22, and the knock sensor 26 are output from the engine speed calculating means 31, the suction pipe pressure calculating means 32, the water temperature of the control unit 30. Input to the detection means 33 and the knocking determination means 34, the engine speed Ne, the suction pipe pressure Pm, the water temperature Tw, and the presence or absence of knocking are obtained. The engine speed Ne and the suction pipe pressure Pm are input to the basic ignition timing detection means 35 and the advance limit search means 36, and the basic ignition timing IGB and the advance limit MBT (advance angle with respect to the basic ignition timing IGB) according to each operation state are provided. Is searched using the basic ignition timing map and the advance limit map.

These two maps are set on the basis of, for example, the characteristics shown in FIG. 4, and the advance limit MBT is determined by the engine speed N
It decreases as e increases. The basic ignition timing IGB corresponding to the knocking limit of regular gasoline is set to the advanced side as the engine speed Ne increases, and the knocking limit becomes parallel to the advanced side as the octane number increases. The advance limit MBT and the basic ignition timing IGB are
It has similar characteristics with respect to the engine load such as the suction pipe pressure Pm.
The advanced angle limit MBT and the basic ignition timing IGB corresponding to each operation state are searched by map using the above parameters.

The advance angle limit MBT and a learning correction amount IGL (set by an advance amount with respect to the basic ignition timing IGB) to be described later are input to the area discriminating means 37, and both are compared as shown in FIG. Area Da where the limit MBT can be obtained (MBT ≦ IGL), Lead angle limit MBT
The region Db (MBT> IGL) in which the difference cannot be obtained is determined, and the result of this determination is input to the ignition timing calculating means 38. Ignition timing calculation means 38
The advance limit MBT, the basic ignition timing IGB, the learning correction amount IGL, and the knocking feedback correction amount AK to be described later are input to the CPU. The ignition timing IGT is calculated and determined as follows.

IGT = IGB + IGL + AK Here, in the area where the advance limit MBT of MBT ≦ IGL can be obtained,
It is possible to set the optimal ignition timing by using the value of the advance limit MBT as it is, and therefore, in the region of MBT ≦ IGL,
The ignition timing IGT is calculated by substituting the MBT for the IGL.

The calculated value of the ignition timing IGT and the crank angle signal of the crank angle sensor 20 are input to the igniter driving means 39, and the ignition signal is output at a crank angle corresponding to the ignition timing IGT.

Next, the ignition timing learning value update control system will be described. The learning condition determination means 40 receives the engine speed Ne, the suction pipe pressure Pm, the water temperature Tw, and the area determination result of the area determination means 37. Here, the current operation state is an operation state (excluding the low load side and the high rotation side) where knocking detection can be performed with high accuracy after warming up by the engine speed Ne, the suction pipe pressure Pm, and the water temperature Tw, MBT> IGL advance limit MBT
It is determined that the learning condition is satisfied in the case of the area Db where the difference cannot be obtained, and this determination result is input to the learning value updating means 41.

The learning value updating means 41 receives a signal indicating the operating state of the engine speed Ne and the suction pipe pressure Pm and the presence / absence of knocking of the knocking determination means 34. Execute selectively. First, when the engine is started, overall learning is performed, the overall learning value AT is read from the overall learning value storage means 42, the learning value AT is updated according to the presence or absence of knocking, and the learning value AT is approximated to a knocking limit corresponding to the octane number of the fuel. Let it. That is, if there is no knocking, the overall learning value AT is updated to the advanced side at a constant rate every fixed time, and if knocking occurs, the overall learning value AT is updated to the retarding side at a constant rate every knocking occurrence. Update to And the number of knocks in this case,
The advance amount of the overall learning value AT is detected by the knocking frequency detection means 43 and the advance angle detection means 44, and the knocking frequency reaches the set value α, or the overall learning value AT reaches the predetermined maximum advance angle AM. In this case, it is determined that the knocking limit has been approximated, the overall learning value AT at this time is stored, and the overall learning ends.

In addition, in contrast to the above-described overall learning, a partial learning value storage unit 45 having a fine address for each operation state as a partial learning is provided.
The learning value updating means 41 reads the partial learning value AP from the partial learning value storage means 45 after the completion of the above-described overall learning. In the same manner as described above, the partial learning value AP for each operating state is also updated in accordance with the presence or absence of knocking. Set to. The overall learning value AT and the partial learning value AP are input to the learning correction amount calculating means 46 to calculate the learning correction amount IGL by IGL = AT + AP, and the learning correction amount IGL corresponds to the ignition timing already described. It is used for a setting control system.

Further, regarding the knocking feedback control system, there is provided a knocking feedback correction amount setting means 47 to which a signal indicating the presence or absence of knocking of the knocking determination means 34 is inputted, and the knocking feedback correction amount AK (AK ≦ 0) is set only when knocking occurs. It is input to the calculating means 38. In this case, in order to reliably prevent the second and subsequent times when knocking occurs, a second retardation amount γF for retarding the knocking feedback correction amount AK when knocking occurs.
Is, with respect to the first retardation amount γ adopted in the learning control,
γ _F >> γ is set. Further, after the retarded each time to continue a certain time knocking without, and outputs a small amount of advance a _F of advance amount a substantially same learning control ends when it becomes AK = 0. Further, the signal from the knocking feedback correction amount setting means 47 is input to the advance angle prohibiting means 48, and AK = 0.
As long as it does not escape from the danger of knocking, it is determined that advance is prohibited, and this advance inhibition signal is input to the learning value updating means 41 to hold the learning correction amount IGL in the knocking retarded state. ing.

Next, the operation of the ignition timing learning control system having such a configuration will be described.
This will be described with reference to the flowcharts of FIGS.

First, steps S100 to S100 in the routine of FIG.
In step S103, the engine speed Ne, the suction pipe pressure Pm, and the coolant temperature Tw are read, and the presence or absence of knocking is determined. In steps S104 and S105, the advance angle limit map and the basic ignition are determined based on the engine speed Ne and the suction pipe pressure Pm. Timing limit MBT from time map,
The basic ignition timing IGB is searched. In steps S106 to S108, the learning execution condition is checked, and the knocking detection signal is excluded from the high rotation speed side where there is much disturbance, the low load side where the sensor output is small, and the cold state, and the learning condition is satisfied in other operating states. Then, the learning value update routine of step S109 is executed.

That is, when the engine is started or the like, the overall learning is first selected in step S200 of the routine in FIG. 3B, and the address of the overall learning value AT is stored in the index register X in step S201. In step S203, the presence or absence of knocking is determined. If knocking is present, step S204
To retard the overall learning value AT by a certain amount by the first retardation amount γ,
In steps S205, the timers 1 and 2 are cleared, and in step S206, the counter is incremented to count the number of knockings. If there is no knocking, the advance limit MBT is compared with the learning correction amount IGL (= AT + AP) in step S207, and the MBT
If the vehicle enters the region of ≤IGL, the learning value will not be updated because the output torque will exceed the advancing limit MBT and conversely, the output torque will decrease even if the advancing angle is further advanced. Then, in step S208, the timer 1 for measuring the time without knocking is checked, and if no knocking continues for a fixed time t ₁ (for example, 1 second), the knocking feedback correction amount AK is checked in step S217, and if AK = 0, In step S209, the overall learning value AT is updated to the advance side by a fixed amount a, and in step S210, the timer 1
Is cleared.

In step S211 and thereafter, the end condition of the overall learning is checked, and in step S212, the magnitude of the overall learning value AT for the predetermined maximum advance amount AM is determined.
In step S213, the timer 2 is cleared. In step S214, the number of knocks is checked. If the number of knocks is equal to or more than the set value α (for example, 5 times), it is determined that the overall learning value AT has converged to the knocking limit, and the overall learning is terminated. In step S215, the end flag is set. Also, the advance angle advances without knocking and AT
When ≧ AM is reached, the process proceeds from step S212 to S216, and after the accumulated time t ₂ (for example, 3 seconds) of the timer 2 has elapsed, the overall learning is similarly terminated.

When the overall learning value AT is learned and determined in this way, the process proceeds from step S200 to S202, where the partial learning value of the current driving state is
The address where the AP is stored is stored in the index register X
, And the partial learning is performed in the same manner after step S203. That is, when there is knocking, the partial learning value AP is updated to the retard side, and when there is no knocking, the partial learning value AP is updated to the advance side under the condition of MBT> IGL. The AP learning update is always performed during operation as long as the learning condition is satisfied. This gives the overall learning value
The learning correction amount IGL obtained by adding the AT and the partial learning value AP becomes a value very close to the actual knocking limit in each operating state.

On the other hand, after setting the knocking feedback correction amount AK in step S113, the value obtained by adding the knocking feedback correction amount AK to the learning correction amount IGL obtained by adding the overall learning value AT and the partial learning value AP to the advance limit is set in step S110. Compare with MBT. If MBT ≦ IGL + AK, the ignition timing IGT is calculated from the advance limit MBT and the basic ignition timing IGB in step S111. Therefore, as shown by the thick solid line in FIG.
The ignition timing IGT is determined by the T characteristic. If MBT> IGL, then in step S112, IGT = IGB + IGL + AK. Here, if AK = 0, the ignition timing IGT is calculated from the learning correction amount IGL and the basic ignition timing IGB. Therefore, the ignition timing IGT becomes parallel to the basic ignition timing IGB as shown by the thick solid line in FIG. , A value close to the actual knocking limit IGT 'of a certain octane number.

Then, when we describe knocking occurs, the knocking feedback correction amount AK proceeds from step S300 to S304 of the routine of FIG. 3 (c) is updated to increase the retard side by the second delay amount gamma _F, step S305 Clears the timer 3. At this time, the learning correction amount IGL is also updated to the retard side by the first retardation amount γ in step S204 of the routine of FIG. 3B of the learning control, and therefore, the step of the routine of FIG. In S113, the ignition timing IGT is largely retarded by both of these retardation amounts γ _F and γ. On the other hand, when this knocking occurs, the steps of the routine shown in FIG.
Since it is determined that AK ≠ 0 in S217, even if knocking is avoided, the process proceeds from step S217 to S211 until the knocking feedback correction amount AK becomes zero, and the advance of the learning correction amount IGL is set to the time T in FIG. Prohibited after _O.

And after knocking avoidance proceeds from step S300 S301, a predetermined time t ₃ (e.g. 1 second) timer 3 in the case of no continuously knocking, advance the knock feedback correction amount AK is advancing amount alpha _F at step S302 The timer 3 is cleared in step S303. For this reason, the ignition timing IGT is separated from the learning control and updated to the advance side only by the advance amount α _{F of the} knocking feedback,
Mutual interference with the learning control is prevented, and variations in the learning correction amount IGL are also prevented.

Thus after knocking avoidance, as time T ₁ of the Figure 5
When AK returns to 0, the knocking feedback correction ends, and the process proceeds from step S217 to step S209 in the routine of FIG. 3B, where the learning correction amount IGL is updated to the advanced side.
Incidentally, when the knocking continues as in the fifth diagram of time T _2, T ₃ occurs, it is updated larger retarded by the retard amount gamma _F at step S304 again advancing middle time T _3, knocking In the direction in which is unlikely to occur.

The embodiment of the present invention has been described above, but the present invention is not limited to this.

〔The invention's effect〕

As described above, according to the first aspect of the present invention,
At the basic ignition timing set based on the engine operating state,
A final ignition timing is set by adding a learning correction amount for retarding and advancing according to the presence or absence of knocking, and a knocking feedback correction amount for retarding the angle when knocking occurs. When knocking occurs, the learning correction amount learned according to the presence or absence of knocking is retarded by the first retardation amount, and the knocking feedback correction amount is retarded by the second retardation amount.
The final ignition timing is set by adding the learning correction amount and the knocking feedback correction amount that have been retarded to the basic ignition timing, so that the final ignition timing is greatly retarded and the second and subsequent times are set. Knocking can be effectively prevented. In addition, it is possible to carry the retardation correction amount for retarding the basic ignition timing when knocking occurs in a distributed manner between the learning correction amount and the knocking feedback correction amount. By reducing the amount of retard correction of the correction amount, the fluctuation of the learning correction amount can be suppressed, and stable learning can be performed.

Then, after the knocking is eliminated, the knocking feedback correction amount is gradually corrected to the advance side until the knocking feedback correction amount becomes zero by the advance amount, and the learning correction is performed until the knocking feedback correction amount becomes zero. When the knocking is eliminated and the knocking feedback correction amount becomes zero, learning of the learning correction amount to the advanced side is restarted, and the basic ignition set based on the engine operating state is prohibited. Since the final ignition timing is set by adding the knocking feedback correction amount and the learning correction amount to the timing, after the knocking is eliminated, the ignition timing learning control and the knocking feedback control are reliably separated, and the learning is performed. Variations in the correction amount can be kept small, and mutual interference between ignition timing learning control and knocking feedback control is prevented. Rukoto can. As a result, after knocking has been eliminated, the ignition control is performed in accordance with the ignition timing learning control and the knocking feedback correction. Timing instability can be eliminated, and ignition timing controllability can be greatly improved.

Further, as described above, it is possible to suppress the variation of the learning correction amount by reducing the delay correction amount of the learning correction amount when knocking occurs, and to perform the learning correction amount by the knocking feedback correction amount after knocking is eliminated. In addition, since the erroneous learning is prevented and the variation of the learning correction amount is suppressed, the ignition timing can be quickly converged to the optimum ignition timing by the learning correction amount after the completion of the knocking feedback correction by the knocking feedback correction amount. Thus, it is possible to improve the engine output performance and drivability, and to improve the exhaust emission.

According to the second aspect of the invention, the basic ignition timing and the advance limit given by the advance amount with respect to the basic ignition timing are set based on the engine operating state. When setting the final ignition timing, if the addition value of the learning correction amount and the knocking feedback correction amount is smaller than the advancement limit and does not show the advancement limit, the knocking feedback correction is performed on the basic ignition timing. The final ignition timing is set by adding the amount and the learning correction amount, while
When the added value is in an area where an advance limit equal to or more than the advance limit can be obtained, the final ignition timing is set by adding the advance angle limit to the basic ignition timing set based on the engine operating state. In addition to the effects of the invention described in the item 1, in addition to the knocking limit corresponding to the octane number of the fuel used, the final ignition timing can be obtained, and the engine output performance can be maximized.

At this time, according to the third aspect of the invention, the second retardation amount is set to a retardation amount larger than the first retardation amount, so that the invention of the first or second aspect is provided. In addition to the above-mentioned effect, when the knocking occurs, the correction of the learning correction amount to the retard side is minimized, and the delay correction amount by the knocking feedback correction amount is increased to effectively avoid the second and subsequent knocking can do. Further, since the correction of the learning correction amount to the retard side when knocking occurs is suppressed, it is possible to stably perform the learning with the subsequent learning correction amount, and it is possible to improve the ignition timing learning accuracy. Having.

[Brief description of the drawings]

Drawings show an embodiment of the present invention, FIG. 1 is a functional block diagram showing a functional configuration relating to ignition timing control of a control unit, FIG. 2 is a schematic configuration diagram of a vehicle engine to which the present invention is applied, FIG. 3 is a flowchart showing an ignition timing control procedure, FIG. 4 is an explanatory diagram showing a relationship between the basic ignition timing and the advance limit, and a setting state of the ignition timing, and FIG. 5 is a learning correction with and without knocking. 6 is a time chart showing a relationship between setting amounts and knocking feedback correction amounts. DESCRIPTION OF SYMBOLS 1 ... Engine body, 7 ... Spark plug, 30 ... Control unit, 35 ... Basic ignition timing search means, 36 ... Advance limit search means, 37 ... Region determination means, 38 ... Ignition timing calculation means , 40 ... learning condition determination means, 41 ... learning value updating means,
46: learning correction amount calculation means 47: knocking feedback correction amount setting means 48: advance angle prohibition means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02P 5/152 F02P 5/15

Claims (3)

(57) [Claims] 1. A learning correction amount in which a basic ignition timing set based on an engine operation state is retarded and advanced in accordance with the presence or absence of knocking, and a knocking feedback correction amount in which retardation is corrected when knocking occurs. In the ignition timing learning control method of setting the final ignition timing by correcting the above, when knocking occurs, the learning correction amount is retarded by a first retardation amount, and the knocking feedback correction amount is changed by a second retardation amount. After the knocking is eliminated, the knocking feedback correction amount is gradually corrected to the advance side until the knocking feedback correction amount becomes zero by the advancement amount, and the knocking feedback correction amount is reduced to zero. Until the knocking is eliminated and the knocking feedback correction amount is zero, the learning of the learning correction amount is prohibited. The learning on the advance side of the correction amount is restarted, and the final ignition timing is set by adding the knocking feedback correction amount and the learning correction amount to the basic ignition timing set based on the engine operating state. Ignition timing learning control method. 2. A basic ignition timing and an advance limit given by an advance amount with respect to the basic ignition timing are set based on an engine operating state, and an added value of the learning correction amount and the knocking feedback correction amount is set. Is smaller than the advance angle limit, a final ignition timing is set by adding the knocking feedback correction amount and the learning correction amount to the basic ignition timing,
On the other hand, when the added value is equal to or more than the advance angle limit, the final ignition timing is set by adding the advance angle limit to the basic ignition timing set based on the engine operating state. Ignition timing learning control method. 3. The ignition timing learning control method according to claim 1, wherein the second retardation amount is set to a retardation amount larger than the first retardation amount.