JPH0481574A - Ignition timing controller for spark ignition internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the extent of accelerating performance by comparing each ignition timing found out with a first ignition timing calculating means, compensating the fundamental ignition timing, and a second ignition timing calculating means, finding the ignition timing of minimal spark advance for securing the maximum output, with a combustion chamber wall temperature detecting means. CONSTITUTION:According to the driving of an engine E, fundamental ignition timing of a fundamental ignition angle setting means 30 with a fundamental ignition timing map is added to an ignition timing compensation value operated by an ignition timing compensation value setting means 31 from a combustion chamber temperature with a adding means 34. Then, ignition timing information set by a minimum spark advance value calculating means 35 provided with a minimum spark advance value map securing the maximum output in a driving state is compared with information of the adding means 34 by an ignition timing selecting means 36, thereby selecting ignition timing at the spark delay. At time of acceleration, when temperature in a combustion chamber is low, ignition timing advance is compensated to the spark advance side, and when coming higher, it is compensated to the timing delay side, through which such an optimum ignition timing as producing no knocking should be set at all times. In addition, since desired ignition timing is not set to the more advance side than the minimum timing advance value, the ignition timing at transition can be set to the value that is able to secure the maximum output at an ignition angle where knocking is not produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ignition timing control device for a spark ignition internal combustion engine such as a gasoline engine.

(Prior Art) For example, ignition timing control for a Kanrin engine has conventionally been performed as follows. The basic advance value (ignition timing information) is calculated based on the engine load detected from the intake air amount and throttle valve opening, and the engine speed.
The ignition timing of the engine is controlled by making appropriate corrections to this basic ignition timing information and operating the ignition device (ignition plaque, ignition coil, etc.) based on the obtained ignition timing information.

Is there any appropriate correction to be made to the basic ignition timing information mentioned above, such as correction based on engine cooling water temperature or intake air temperature? Therefore, it is necessary to make some kind of correction to the ignition timing information even when the engine is accelerating.

Here, knocking is a vibration phenomenon in the combustion chamber induced by self-ignition, and such knocking not only generates unpleasant noise but also has the potential to adversely affect the engine.

Conventionally, in order to prevent the occurrence of such knocks, control has been generally carried out to delay the ignition timing, or in this case, the ignition timing is A control method is adopted that delays the knocking to a safe side so that knocking does not occur even under the worst conditions.

(Problem to be Solved by the Invention) By the way, as shown in Fig. 8, the ignition angle at which knock occurs is related to the wall temperature of the combustion chamber wall (cylinder block catalytic surface temperature). When changing from a low load to a high load, the combustion chamber wall temperature is lower than the steady state due to the delay in temperature rise (see Figure 9), so the ignition will be delayed for several tens of cycles when the combustion chamber wall temperature rises to a steady state. No knock occurs even if the angle is advanced relative to the angle.

On the other hand, during the several dozen cycles until the combustion chamber wall temperature reaches a steady state, no knock will occur even if the ignition angle is advanced relative to the ignition angle set at steady state, but the ignition angle will not produce the maximum torque. When considering the minimum lead angle (MBT) that can be achieved, there is a question of whether it is an optimal value. That is, during acceleration, although knocking does not occur even if the ignition angle is advanced as described above, there is no need to advance the ignition angle beyond the ignition angle at which the maximum torque is obtained.

The present invention was made based on such knowledge, and
An ignition timing control device for a spark-ignition internal combustion engine that obtains ignition timing information from the combustion chamber wall temperature to avoid unnecessarily retarding the ignition timing and to obtain maximum engine output during acceleration. The purpose is to provide

(Means for Solving the Problems) In order to achieve the above-mentioned object, the ignition timing control device for a spark-ignition internal combustion engine of the present invention at least adjusts the operating state of the internal combustion engine according to the rotation speed and load of the engine. an ignition timing setting means for setting basic ignition timing in accordance with the operating condition detected by the operating condition detection means; ignition timing actuating means for actuating an ignition device; the ignition timing setting means includes a combustion chamber wall temperature detecting means for detecting a wall temperature of a combustion chamber wall of the internal combustion engine; and the combustion chamber wall temperature detecting means. a first ignition timing calculation means for calculating an ignition timing by correcting the basic ignition timing according to the wall temperature detected by the device; and a minimum advance angle ignition for obtaining maximum output according to the operating condition detected by the operating condition detecting device. The second ignition timing calculation means for calculating the timing compares each ignition timing calculated by the first and second ignition timing calculation means, selects the ignition timing on the delayed side, and uses this as ignition timing information to calculate the ignition timing. and a selection means for outputting an output to the actuation means.

The above-mentioned combustion chamber wall temperature detection means includes a temperature sensor that is attached to the combustion chamber wall and detects the wall temperature of the combustion chamber wall by directly measuring the wall temperature of the combustion chamber wall. Alternatively, the combustion chamber wall temperature estimating means may be configured to detect the wall temperature of the combustion chamber wall by estimating the wall temperature of the combustion chamber wall from a variable indicating the amount of combustion energy. Furthermore, regarding the measured value of the variable indicating the amount of combustion energy, the latest data of the measured value is corrected with the past data of the measured value, and the wall temperature of the wall portion of the combustion chamber wall is determined from the corrected data regarding the amount of combustion energy. The combustion energy index calculation means may be configured to detect the wall temperature of the combustion chamber wall by estimating the combustion energy index.

(Function) The ignition timing control device of the present invention calculates the ignition timing by correcting the basic ignition timing from the wall temperature of the combustion chamber wall using the first ignition timing calculation means, that is, the ignition timing at the maximum advance angle at which knock does not occur. demand. Further, the second ignition timing calculating means determines the ignition timing with the minimum advance angle that provides the maximum output according to the operating state detected by the operating state detecting means. Then, when the ignition timing selection means compares each ignition timing obtained by the first and second ignition timing calculation means and selects the ignition timing on the delayed side, knocking does not occur and maximum output is obtained. The ignition timing will be set.

(Embodiment) Hereinafter, an ignition timing control device for a spark ignition internal combustion engine as an embodiment of the present invention will be explained with reference to the drawings.
FIG. 1 shows an overall configuration diagram showing the control system and general engine system.

The automotive gasoline engine system (spark ignition internal combustion engine system) controlled by this device is the first
As shown in Fig. 1, gasoline engine E (hereinafter simply referred to as engine E) has its combustion chamber 1.
The intake passage 2 and the combustion chamber 1 are communicated with each other by an intake valve 4, and the exhaust passage 3 and the combustion chamber 1 are communicated with each other by an exhaust valve 5. It is now possible to do so.

In addition, an air cleaner 6 is installed in the intake passage 2 in order from the upstream side.
, a throttle valve 7 and an electromagnetic fuel injection valve (injector) 8 are provided in the exhaust passage 3, and a catalytic converter (not shown) for purifying exhaust gas (not shown) is installed in the exhaust passage 3 in order from the upstream side.
A three-way catalyst) and a muffler (silencer) are also provided.

Note that the injectors 8 are provided in the intake manifold portion for the same number of cylinders. Now, the engine E of this embodiment is an inline 4
Assuming that the engine is a cylinder engine, four injectors 8 are provided.

i.e. so-called multi-point fuel injection (MPI)
It can be said that it is the engine of the system.

Further, the throttle valve 7 is connected to the accelerator pedal via a wire cable, so that the opening degree changes depending on the amount of depression of the accelerator pedal.

Further, each cylinder is provided with a spark plug 9 facing toward the combustion chamber 1 thereof, and each spark plug 9 is connected to an ignition coil 10 via a distributor (not shown). When the power transistor 11 with the ignition coil 10 is turned off, a high voltage is generated in the ignition coil 9, causing one of the spark plugs 9 connected to the distributor to spark (ignite). It should be noted that charging of the ignition coil 10 by the battery 12 is started by turning on the power transistor 11 . The spark plug 9, distributor, ignition coil IO, and power transistor 11 constitute an ignition device.

With this configuration, the air taken in through the air cleaner 6 according to the opening degree of the throttle valve 7 is mixed with the fuel from the injector 8 in the intake manifold part to an appropriate air-fuel ratio, and ignited in the combustion chamber 1. By igniting the plug 9 at an appropriate timing, combustion is caused,
After generating engine torque, the air-fuel mixture is discharged as exhaust gas into the exhaust passage 3, where it is purified of three harmful components, Co, HC, and NOx, in the exhaust gas by a catalytic converter, and then muffled by a muffler and released into the atmosphere. It's like being left alone.

Furthermore, in order to control this engine E, various sensors are provided. First, on the intake passage 2 side, an air flow sensor 13 is installed in the air cleaner installation part as a volumetric flow meter that detects the amount of intake air from Karman vortex information. An intake temperature sensor that detects the intake air temperature and an atmospheric pressure sensor that detects the atmospheric pressure are provided, and a potentiometer-type throttle sensor that detects the opening degree of the throttle valve 7 and an idle link state are installed in the throttle valve installation part. An idle switch is provided to detect the

In addition, on the exhaust passage 3 side, the oxygen concentration (02 concentration) in the exhaust gas is displayed at the upstream side of the catalytic converter and close to the combustion chamber 1.
An oxygen concentration sensor (02 sensor) is provided to detect.

Furthermore, the temperature of the wall of the engine combustion chamber 1 (combustion chamber wall temperature)
As shown in FIG. 2, the wall temperature sensor 17 for detecting the Can be installed in a location with little temperature change. Furthermore, although a thermocouple is used as the wall temperature sensor 17, a thermistor or a metal resistor may also be used.

Additionally, in addition to a water temperature sensor 16 that detects the Ennon cooling water temperature, a crank angle sensor 14 that detects a predetermined crank angle position (this crank angle sensor 14 also serves as an engine rotation speed sensor that detects the engine rotation speed N) is provided. (Hereinafter, the crank angle sensor 14 may be referred to as an engine speed sensor if necessary.) and a cylinder discrimination sensor for detecting the top dead center of the first cylinder (reference cylinder) are provided in the distributor. There is.

By the way, detection signals from each of the above-mentioned sensors are input to an electronic control unit (ECU) 15.

In addition, when looking at the hardware configuration of the ECU 15, the CPU, RAM (including backup RAM),
It is equipped with a ROM and an appropriate human output interface circuit, and the signals from each sensor are input to the CPU through the input interface circuit or directly, and the ignition timing control signal or power transistor from the CPU is input through the output interface circuit. 11, and the spark plugs 9 are sequentially sparked from the ignition coil 10 via a distributor.

Note that the CPU outputs an injection fuel control signal to the injector 8 through the output interface circuit, so that fuel is injected from the injector 8 for a time determined by this injection fuel control signal, and the desired air-fuel ratio is achieved. It is controlled so that

Now, focusing on ignition timing control, the ECU 15 is shown using functional blocks for ignition timing control.
The result will be as shown in the figure. That is, this ignition timing control device includes basic ignition angle setting means 30, ignition timing correction amount setting means 31, addition means 34, MBT calculation means 35, ignition timing selection means 36, and ignition signal generation means 37.

Here, the basic ignition angle setting means 30 is configured according to the operating state of the engine E (this operating state is determined from, for example, engine load information from the air flow sensor 13 and engine speed information from the engine speed sensor 14). This is used to set the basic ignition timing e. For example, the volumetric efficiency Ev (-A/N) obtained by dividing the intake air amount A by the engine speed N
) and the engine speed N, the engine has a basic ignition timing map that stores two-dimensional basic ignition timing data (advanced angle data).

The ignition timing correction amount setting means 31 includes a wall temperature calculation means 32, which includes an A/D converter etc. that converts an analog signal from the wall temperature sensor 17 into a digital signal, and a wall temperature calculation means 32, which determines the ignition timing based on the detected combustion chamber wall temperature. The ignition angle correction means 33 serves as an ignition timing correction amount calculation means for determining the correction amount ΔA.

Further, the addition means 34 adds the basic ignition angle θ from the basic ignition angle setting means 30 and the ignition timing correction amount ΔA from the ignition timing correction amount setting means 31.

Therefore, the basic ignition angle setting means 30, the ignition timing correction amount calculation means 33, and the addition means 34 constitute a first ignition timing calculation means for setting the ignition timing corrected based on the combustion chamber wall temperature.

The MBT calculation means 35, which is the second ignition timing calculation means,
The operating state of the engine E, that is, the engine load information E
v (= A / N) and engine speed information N
According to the operating conditions, the minimum advance angle value M B T (Minimum advance
cefor Be5t Torque), and is equipped with an MBT map that stores two-dimensional MBT value data determined from A/N and N.

The ignition timing selection means 36 compares the ignition timing information set by the addition means 34 and the MBT calculation means 35 described above, and selects the ignition timing on the delayed side. The ignition signal generation means 37 generates an ignition signal for operating the power transistor 11 based on the ignition timing selected by the ignition timing selection means 36. transistor 1
This constitutes an ignition device operating means for operating a first-class ignition device.

FIG. 3 is a flowchart showing the procedure for setting the above-mentioned ignition timing, and this ignition timing setting main routine is such that each time a predetermined control signal is generated, the crank angle sensor 14 detects a predetermined crank angle. Executed every time a position is detected.

The electronic control unit h (ECU) 15 first executes a wall temperature correction routine to obtain the ignition timing correction amount ΔA (step MIO). Next, in this routine, the ignition timing correction amount Δ
The method for finding A will be explained.

The ignition timing correction amount ΔA is calculated by determining the relationship between the 1-knock ignition timing and the engine speed N, the intake air amount A/N per engine speed, and the combustion chamber wall temperature relative to the cooling water temperature through experiments. If stored in ROM, ignition timing can be obtained from the combustion chamber wall temperature.

To explain in more detail, different engine speeds N
, at the cooling water temperature, K at WOT (when the throttle is fully open)
If the knock ignition timing K1 can be expressed by a linear equation with respect to the wall temperature θW, the following equation holds true.

A K + =-λ (N) 0w +a (N)
-(1) Here, λ(N) and μ(N) are constants determined by the engine speed and cooling water temperature.

Therefore, the ignition timing correction amount ΔA (' BTDC) from the combustion chamber wall temperature θws at steady WOT at this time is ΔA=λ
(N)(θws−θw) ・(2) Therefore,
Let λ(N) be a map of engine speed N, and W
By having the wall temperature θWS at the time of OT in the ECU 15 as a map of the intake air amount A/N, engine speed N, and cooling water temperature θC, it is possible to calculate from λ(N), A/N, and N in a certain calculation cycle at that point. It is possible to calculate ΔA of .

Note that the actual ignition angle setting allows some leeway.

Furthermore, it is possible to calculate the ignition timing correction amount ΔA in the same manner for a different A/N instead of WOT.

Figure 4 shows the ignition timing correction amount Δ due to the combustion chamber wall temperature mentioned above.
This is a flowchart showing the procedure for determining A, and the procedure for calculating the ignition timing correction amount will be explained with reference to this flowchart.

First, in step S1, the wall temperature θ is detected by the wall temperature sensor 17.
W is directly measured, and in the next step S2, λ(N) is read out from the engine rotation speed N, and in step S3,
The wall temperature θws during steady operation is read from the load A/N, engine speed N, and cooling water temperature θC. And step S4
Then, the ignition timing correction amount ΔA is calculated as λ(
N), θWS, and θW from the above equation (2).

The combustion chamber wall temperature θ may be detected by directly measuring it with the wall temperature sensor 17 as described above, but it may also be detected by estimating it from a variable indicating the amount of combustion energy. In this case, the combustion chamber wall temperature detecting means includes a combustion chamber wall temperature estimating means for estimating the temperature of the wall in the combustion chamber 1 of the engine from variables indicating the amount of combustion energy such as the amount of intake air and the amount of fuel injection. be done.

Next, with reference to FIGS. 5 and 6, the ignition timing correction amount Δ
The procedure for setting A from the method of estimating the combustion chamber wall temperature will be explained.

First, the estimation model and calculation formula for the combustion chamber wall temperature will be explained. As shown in Fig. 5, the model for estimating the combustion chamber wall temperature θ is estimated from the heat Qi, Qo flowing into and out of the combustion chamber wall, the heat capacity C1 of the combustion chamber wall, and the cooling water temperature θC. It can be considered as a non-stationary dimensionless model. Therefore, from this model, the temperature increase rate θW of the combustion chamber wall is jw = (Qi - Qo) /C - (3),
Qo is expressed as Qo=α(θW-θC) (4), where α is the heat transmission coefficient between the combustion chamber wall and the coolant. Therefore, by substituting equation (4) into equation (3), When substituted, θW=-(α (θW-θc)/Cl + (Qi /C)...(5)
becomes. Here, if θ is the temperature difference between the combustion chamber wall and the coolant, and θW=θC+θ (6), then dθc/dt=0, formula (5) becomes tj−(−
αθ/C) + (Qi/C) (7).

By the way, the exothermic energy of the fuel is proportional to the product of the air flow rate, A, /N, taken into the cylinder per engine rotation and the engine rotation speed N, and the heat Qi flowing into the combustion chamber wall is
Assuming that is a part of the exothermic energy and its proportion is constant, Qi is linear with (A/N)XN. Therefore, if we set Qi = Cβ(A/N)N (8) (β is a constant) and rewrite α/C as γ (constant), we get
Equation (7) becomes b--γθ+β(A/N)N (9). This is integrated from time t to t+ΔT, and the subscript (1)
If represents the value at time t, then θ(t+ΔT)
=θ(t) + i−γθ×β(A/N)Nl dt・
...(10) becomes. This is expressed as Euler (Eu) where ΔT is a constant interval.
ier) method, θ(t+ΔT)=θ(1)+[−γθ(t)+β[
A/N(t)] N(t)] ΔT(1-76th) θ
(1) +β tA/N(t)l N(t) 6 or θ(t+ΔT)=(1-76) θ(1) 10β[A/N
(t+ΔT)] N(t+ΔT)ΔT (11) When converted into a calculation formula for each calculation period ΔT, formula (11) becomes the following.

θ, = (l-γΔT) θ, -1+βΔT (A/N+
)N + (12) Here, ΔT is the operation period, and the subscript j is the value at operation j. Since this is a recurrence formula, it can be calculated by an engine control microcomputer, and if γ and β are measured in advance, (6), (1
The combustion chamber wall temperature can be found from equation 2).

Next, a method of calculating the ignition angle correction amount (ignition timing correction amount) ΔA from the combustion chamber wall temperature will be explained.

The corrected advance angle amount ΔA (' BTDC) at steady WOT is:
It is set according to the difference between the combustion chamber wall temperature θws and the wall temperature θW using the above-mentioned equation (2). Also, from equation (6), (12)
The formula is, ΔA−λ (θS −θ) ...(1
3). Here, from the intake air amount A/Ns per engine speed at full-open steady state at this engine speed N, θS at this time can be expressed as θ(t+ΔT)−〇(1) in equation (10). Find, θs-(β/7) (A/NS) N-<14
), so the formula (I3) is ΔA−λ [((β/7) (A/NS ) N
l −θko (15). Therefore, in calculation J, the following equation is obtained.

ΔAj=λ[((β/γ) (A/Ns) Ni
(1G) Therefore, by providing a map of λ, A/N s, and cooling water temperature to the engine control microcomputer, λ, A/N s, N, and ( 12)
ΔA at that point in time can be calculated from θ determined from the formula. Note that the actual ignition angle setting allows some leeway.

Furthermore, if equation (1) holds true not only for WOT but also for different A/'N, ΔAj−λne(1−γΔT) +−θL++(β/γ
)×(A/Nj) Nj l
...(It will be 17.

Next, the ignition timing calculation procedure will be explained using the flowchart shown in FIG.

First, in step Sll, the cooling water temperature θC is set to the set value XDC.
Determine whether it is smaller than. If it is small, no
Taking this route, in step S13, the combustion chamber wall temperature change rate θwj−θwj is determined.

Then, in the next step S15, the combustion chamber wall temperature change rate θw
It is determined whether j-θWj-i is smaller than the set value Xθ. Combustion chamber wall temperature change rate θwj−θWj−+ is set value X
If it is 6 or more, in step S17, FLG is set to 1, and in step 318, λ or λ is determined from the engine rotation speed.
ne is found, and in step S19, the ignition correction amount ΔA is determined. Thereafter, in step S20, the next combustion chamber wall temperature information θ is determined.

Further, in step S15, the combustion chamber wall temperature change rate θWl−θ
If j−+ is smaller than the set value Xθ, that is, when the steady state is reached, the YES route is taken in step S15, FLG is set to 0 in step S22, and the steady state combustion chamber wall temperature is set in step S23. After determining θS, in step S24, the next combustion chamber wall temperature information is set to θS, and in step S25, the ignition correction amount ΔA is set to 0, and the routine ends.

Note that even if the cooling water temperature is low, the step S22 jumps and the steady state control (steps 323 to 525)
Do this.

The method for estimating the combustion chamber wall temperature is as follows:
It can also be determined using a value obtained by subjecting the amount of combustion energy passing through the wall surface to moving average processing or first-order filter processing. In this case, the combustion chamber wall temperature detection means calculates the combustion energy index CI by performing moving average processing or first-order filter processing on variables indicating the amount of combustion energy (for example, intake air amount A and combustion injection amount), and calculates the combustion energy index CI. The combustion energy index calculating means is configured to calculate the combustion chamber wall temperature from the CI.

A method for obtaining a value obtained by subjecting the amount of combustion energy passing through a wall surface to moving average processing or first-order filter processing will be explained. First, when calculating the combustion energy index CI by performing moving average processing, the following equation (17) or (18) is used.

Equation (I7) is an equation when the amount of intake air A is used as a variable indicating the amount of combustion energy, and Equation (18) is an equation when the amount of supplied fuel U is used as a variable indicating the amount of combustion energy.

Here, n is the number of moving average targets (2 to 3), A/N, -.

is the intake air amount per engine rotation speed of the (ik)th cycle, Ni- is the number of engine rotations of the (ik)th cycle, and U, -1 is the amount of fuel supplied to the (ik)th cycle. It is.

In addition, by applying −order filter processing, the combustion energy index CI
When calculating, the following equation (19) or (20) is used.

CI=K(A/N1)Ni+(1-K)(A/N1-
+)N1-, ...(19)CI=Ku+ +(1
-K)u+-1・r2o) Equation (19) is an equation when the amount of intake air A is used as a variable that indicates the amount of combustion energy, and equation (20) is an equation that uses the amount of supplied fuel as a variable that indicates the amount of combustion energy. This is the formula when using U.

Here, K is a filter constant (0<K<1), and A/N is 1
N is the intake air amount per engine rotation speed of the ith cycle, and U is the amount of fuel supplied for the ith cycle.

Therefore, the combustion energy index calculation means corrects the latest data of the measured values obtained from time to time regarding variables indicating the amount of combustion energy (intake air amount A and fuel injection amount U) with past measured data. become.

Next, the relationship between the combustion chamber wall temperature and the amount of combustion energy will be explained. Now, as shown in the above-mentioned Fig. 5, the heat flowing into and out of the combustion chamber wall is Qi and Qo, and the temperature increase rate of the combustion chamber wall (combustion chamber wall temperature) θW and Qo are as described above. It is expressed by equations (3) and (4), and since α in equation (4) can be regarded as a constant and θC as constant, it becomes Q□ccθW (21).

Therefore, similar results can be obtained by using the amount of combustion energy passing through the wall surface instead of the combustion chamber wall temperature. Changes in the combustion chamber wall temperature can be determined using the moving average processing or first-order filter as described above for combustion energy. It can be approximated by the processed version.

Next, a method of calculating the ignition angle correction amount (ignition timing correction amount) ΔA from the combustion chamber wall temperature will be explained.

In other words, the relationship between the knock ignition timing and the combustion energy index CI for all steady-state operating conditions (for example, this relationship is such that the ignition angle is advanced while the combustion energy amount during acceleration is lower than steady state). This relationship is determined through experiments and then set in the engine control microcomputer. Thereby, the ignition timing can be obtained from the combustion energy index CI during a certain operation.

Note that the actual ignition angle setting should be based on the experimentally obtained value with some leeway.

Next, the procedure for calculating the ignition timing correction amount ΔA using the above-described method will be explained using the flowchart shown in FIG.

First, in step 330, variable information (A/N or U) indicating the amount of combustion energy in one cycle is fetched, and in step S31, moving average processing or first-order filter processing is performed on the amount of combustion energy, and the above-mentioned ( 1,7),
The combustion energy index CI is calculated from equation (18) or equations (19) and (20).

Thereafter, in step S32, the ignition correction amount ΔA may be determined based on data measured in advance from the combustion energy index CI determined.

Once the ignition correction amount ΔA is determined as described above, the process returns to step Mll in FIG. Add (step M12). and,
In step M13, the minimum ignition angle MBT that can obtain the maximum output is calculated. This minimum ignition angle MBT is calculated from the above-mentioned MBT map according to the operating state of the engine E at that time (determined by the intake air amount A/N and the engine rotational speed N).

Next, the calculated MBT value is compared with the basic ignition angle θ (-θ+ΔA) corrected by the ignition correction amount ΔA, and the value on the retarded side is selected and set as the target ignition angle (step M1
4). That is, the set target ignition angle is never set to a value on the leading side of the MBT value.

When the ignition angle is determined as described above, based on this information, the ignition signal generation means 37 sends the power transistor 11
An ignition signal is issued to the spark plug 9, and the ignition plaque 9 ignites at a timing corresponding to the ignition signal.

In this way, the combustion chamber wall temperature is directly measured or estimated, and the ignition correction amount ΔA is determined from this wall temperature. ) sets the ignition advance angle to the advance side, and as the combustion chamber wall temperature increases after the middle of acceleration, the ignition advance angle can be corrected to the retard side accordingly. Without further delay, it is possible to always set the optimum ignition angle that does not cause knock, which is determined by the combustion chamber wall temperature.

In addition, since the target ignition angle is never set to a value on the advanced side of the MBT value, the ignition timing during transient periods is set to a value that provides the maximum engine output among the ignition angles that do not cause knocking. This means that the engine output during acceleration can be improved.

Note that during steady state, no correction is made based on the combustion chamber wall temperature.

In addition, when controlling the ignition timing, in addition to correction during acceleration,
Of course, correction may be made depending on the water temperature and intake air temperature.

Furthermore, the ignition timing calculation means is set to the basic ignition timing contact means 3.
0, ignition timing correction amount setting means 31, and adding means 34 for adding the information obtained by these means, a two-dimensional The ignition timing map storing ignition timing data (advance angle data) may be provided for a plurality of combustion chamber wall moisture levels.

Alternatively, the wall temperature sensor 17 may be provided on the piston, and when the piston reaches the bottom dead center, a switch is closed and the wall temperature information detected by the wall temperature sensor 17 can be output.

Furthermore, the present invention is applicable to spark-ignition internal combustion engines that use the Jetro method using an air flow sensor, as well as spark-ignition internal combustion engines that use the D-Jetro method (speed density method) that uses an intake passage pressure sensor. It is applicable. In the case of the D-Jetro system, the operating state of the engine is detected based on intake passage pressure and engine speed.

Further, the present invention can be similarly applied not only to gasoline engines but also to general spark ignition internal combustion engines such as alcohol engines that use alcohol fuel.

(Effects of the Invention) As detailed above, the ignition timing control device for a spark ignition internal combustion engine of the present invention detects the wall temperature of the combustion chamber wall of the internal combustion engine by the combustion chamber wall temperature detection means of the ignition timing setting means. The first ignition timing calculation means calculates the ignition timing by correcting the basic ignition timing from the combustion chamber wall temperature detected by the combustion chamber wall temperature detection means, and the second ignition timing calculation means calculates the ignition timing by correcting the basic ignition timing. The ignition timing selection means determines the ignition timing with the minimum advance angle to obtain the maximum output according to the operating state detected by the state detection means, and the ignition timing selection means
The second ignition timing calculation means compares the calculated ignition timings, selects the ignition timing on the delayed side, and outputs this as ignition timing information to the ignition timing operation means, so especially during acceleration, etc. During the transition period, the engine output and engine efficiency can be improved while preventing the ignition timing from being retarded more than necessary, which has the advantage of improving acceleration performance.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing a control system of an ignition timing control device for a spark-ignition internal combustion engine according to an embodiment of the present invention and a schematic engine system, and FIG. 2 is a partial cross-sectional view showing the mounting position of a wall temperature sensor. , FIG. 3 is a flowchart of the ignition timing setting main routine, and FIG. 4 is a flowchart of the wall temperature correction routine, which shows the procedure for directly measuring the wall temperature of the combustion chamber and calculating the ignition timing correction amount ΔA from the measured wall temperature value. , Fig. 5 is a diagram explaining the combustion chamber wall temperature estimation model, and Fig. 6 is a procedure for estimating the combustion chamber wall temperature by the combustion chamber wall temperature estimation method and calculating the ignition timing correction amount ΔA from this wall temperature estimation value. FIG. 7 is a flowchart of the wall temperature correction routine, which estimates the combustion chamber wall temperature from the combustion energy index value obtained by moving average processing or first-order filter processing of the combustion energy, and corrects the ignition timing from this estimated wall temperature value. A flowchart of the wall temperature correction routine showing the procedure for calculating the amount ΔA. Figure 8 is a diagram showing the knock characteristics with respect to the cylinder block contact surface temperature (combustion chamber wall temperature) when the throttle valve is fully open. Figure 9 is a diagram showing the knock characteristics with respect to the cylinder block contact surface temperature (combustion chamber wall temperature) when the throttle valve is fully open. FIG. 3 is a characteristic diagram illustrating the response state of the combustion chamber wall temperature when the temperature suddenly changes. ■...Combustion chamber, 2...Intake passage, 3...Exhaust passage,
7... Throttle valve, 8... Electromagnetic fuel injection valve (injector), 9... Spark plug, 10... Ignition coil, 13... Air flow sensor, 14... Engine speed sensor ( Crank angle sensor), 15...Electronic control unit) (ECU), 16...Water temperature sensor, 1
7... Wall temperature sensor, 30... Basic ignition angle setting means,
31... Ignition timing correction amount setting means, 32... Wall temperature calculation means, 33... Ignition angle correction means, 34... Addition means, 35... MBT calculation means, 36... Ignition timing Selection means, 37... Ignition signal generation means, E... Engine. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kan Nagato )−

Claims (4)

[Claims] (1) At least an operating state detection means for detecting the operating state of the internal combustion engine according to the rotational speed and load of the engine, and an ignition system that sets the basic ignition timing according to the operating state detected by the operating state detection means. a timing setting means; and an ignition timing operating means for operating an ignition device based on basic ignition timing information set by the ignition timing setting means; Combustion chamber wall temperature detection means for detecting temperature; first ignition timing calculation means for calculating ignition timing by correcting the basic ignition timing according to the wall temperature detected by the combustion chamber wall temperature detection means; and the operating state. The second ignition timing calculation means calculates the minimum advance ignition timing to obtain the maximum output according to the operating state detected by the detection means, and each ignition timing calculated by the first and second ignition timing calculation means is compared. An ignition timing control device for a spark ignition internal combustion engine, comprising a selection means for selecting a delayed ignition timing and outputting the selected ignition timing as ignition timing information to the ignition timing operation means. (2) The combustion chamber wall temperature detection means includes a temperature sensor that is attached to the combustion chamber wall and detects the wall temperature of the combustion chamber wall by directly measuring the wall temperature of the combustion chamber wall. The ignition timing control device for a spark-ignition internal combustion engine according to claim 1, characterized in that: (3) The combustion chamber wall temperature detection means includes combustion chamber wall temperature estimation means for detecting the wall temperature of the combustion chamber wall by estimating the wall temperature of the combustion chamber wall from a variable indicating the amount of combustion energy. The ignition timing control device for a spark ignition internal combustion engine according to claim 1, characterized in that: (4) The combustion chamber wall temperature detection means corrects the latest data of the measured value of the variable indicating the amount of combustion energy with the past data of the measured value, and uses the corrected data regarding the amount of combustion energy. 2. Ignition of a spark ignition internal combustion engine according to claim 1, further comprising combustion energy index calculation means for detecting the wall temperature of the combustion chamber wall by estimating the wall temperature of the combustion chamber wall. Timing control device.