JPH02223678A - Ignition timing control device for spark ignition type internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an optimum ignition timing even when any fuel is used by a method wherein ignition timing information available when multicomponent fuel or monofuel set by a first or a second ignition timing setting means is used is selected to feed it to an ignition device. CONSTITUTION:An octane number estimating means 22 of an ECU 15 has an estimating means 22A to estimate a gasifying and suction amount from an injection fuel amount by a measuring means 20 and the gasifying characteristics and the octane number of each component of fuel by a setting means 21, and an equivalent octane number is determined by a calculating means 22B. Based on the equivalent octane number, an ignition timing calculating means 23 of a first ignition timing setting means 100 selects corresponding ignition timing maps 231 - 23n, and determines an ignition timing responding to the load and the number of revolutions of an engine by sensors 13 and 14. A second ignition timing setting means 101 outputs ignition timing information during the use of monofuel, and according to a fuel composition detected by a detecting means 42, a selecting means 43 outputs corresponding ignition timing information through a switch means 44 to a power transistor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a spark-ignition internal combustion engine (hereinafter referred to as a The present invention relates to an ignition timing control device for an "internal combustion engine" (sometimes referred to simply as an "engine").

[Prior Art] Conventionally, for example, ignition timing control of a gasoline engine has been performed as follows. Namely.

The operating state of the engine is detected from a flow rate sensor that detects the intake air amount of the engine (a pressure sensor that detects the intake passage pressure may be used instead of this flow rate sensor) and an engine rotation speed sensor that detects the engine rotation speed. , based on the detection results from these sensors, the volumetric efficiency Ev (A
/N) Alternatively, basic ignition timing information is obtained from a two-dimensional map with advance angle values (ignition timing information) determined by intake passage pressure and engine speed N, and appropriate correction is made to this basic ignition timing information. The ignition timing of the engine is controlled by operating an ignition device (spark plug, ignition coil, etc.) based on the ignition timing information obtained in this way.

[Problems to be Solved by the Invention] Appropriate corrections made to the above-mentioned basic ignition timing information include corrections based on the engine cooling water temperature and corrections based on the intake air temperature. Since knocking occurs, it is necessary to make some kind of correction to the ignition timing information even when the engine is accelerating.

Incidentally, one of the causes of knock occurring during engine acceleration is that the vaporization characteristics of each fuel component are not uniform.

That is, gasoline is a multicomponent fuel, usually consisting of multiple components with different octane numbers, and the vaporization characteristics of these components are usually different. Furthermore, in a fuel-injected gasoline engine, not all of the injected fuel enters the combustion chamber at the same time; a portion of the fuel adheres to the intake passage, vaporizes at each intake valve, and is inhaled into the combustion chamber. In this case, since the vaporization characteristics of each fuel component are not uniform, the octane number during combustion in the combustion chamber does not always match that of the original fuel. When a large amount is injected, the octane number decreases, making knocking more likely.

Therefore, conventionally, control has been generally performed to delay the ignition timing by one ignition timing in order to prevent such knock from occurring, but in this case, it is impossible to detect the decrease in octane number during combustion that leads to the occurrence of knock. Therefore, a control method is used to delay the ignition timing to a safe side that prevents knocking even under the worst conditions.

On the other hand, engines that use a single fuel such as alcohol fuel have also been proposed, but in such engines, the octane number during combustion in the combustion chamber matches that of the original fuel, so when accelerating In such a transitional period,
Although the octane number does not decrease, if the ignition timing is controlled to be delayed to the same extent as in the case of a gasoline engine, the ignition timing will be delayed more than necessary. Performance will deteriorate.

The present invention was devised under these circumstances, and is designed to provide spark ignition internal combustion engines that can use both multi-component fuel and single fuel in all operating ranges, including transitional periods such as during acceleration. An object of the present invention is to provide an ignition timing control device for a spark-ignition internal combustion engine that can set appropriate ignition timing information when using any fuel.

[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 according to the present invention as set forth in claim 1 uses both a multi-component fuel and a single fuel. In a spark-ignition internal combustion engine that can be used, a first ignition timing setting means sets ignition timing information when using the multi-component fuel, and a second ignition timing setting means sets ignition timing information when using the single fuel. ignition timing setting means, and selection means capable of selecting ignition timing information from the first ignition timing setting means and ignition timing information from the second ignition timing setting means and supplying the selected ignition timing information to the ignition device. It is characterized by the fact that

Further, in the ignition timing control device for a spark ignition internal combustion engine of the present invention according to claim 2, the first ignition timing setting means includes supplied fuel amount measuring means for measuring the amount of fuel supplied to the internal combustion engine. , octane number estimating means for estimating the octane number of the fuel in the combustion chamber based on the amount of supplied fuel obtained by the supplied fuel amount measuring means and information on vaporization characteristics and octane number preset for each component of the fuel; and ignition timing calculation means for calculating the ignition timing based on the octane number estimated by the octane number estimation means.

[Function] In the ignition timing control device for a spark-ignition internal combustion engine of the present invention as set forth in claim 1 above, when using multi-component fuel,
Ignition timing information from the first ignition timing setting means is output to the ignition device, and when using a single fuel, ignition timing information from the second ignition timing setting means is output to the ignition device.

In the ignition timing control device for a spark ignition internal combustion engine according to the present invention, the ignition timing from the first ignition timing setting means is determined as follows. That is, first, with octane estimation means.

Based on the amount of supplied fuel obtained by the supplied fuel amount measuring means and information regarding the vaporization characteristics and octane number preset for each component of the fuel.

The octane number of the fuel in the combustion chamber is estimated, and then the ignition timing calculation means calculates the ignition timing based on the octane number estimated by the octane number estimation means.

[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.
Figure 2 is an overall configuration diagram showing the control system and engine schematic system, Figure 2 is a diagram explaining the combustion octane number estimation model, and Figure 3 is a flowchart for determining the ignition timing.

Now, the in-vehicle engine system (spark ignition internal combustion engine system) controlled by this device is as shown in Fig. 1. The engine E can use either alcohol fuel (alcohol blend fuel) as one fuel, and furthermore, this engine E has an intake passage 2 and an exhaust passage 3 that communicate with the combustion chamber 1. Communication between the passage 2 and the combustion chamber 1 is controlled by an intake valve 4, and communication between the exhaust passage 3 and the combustion chamber 1 is controlled by an exhaust valve 5.

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 wandering gas is installed in the exhaust passage 3 in order from the upstream side.
A three-way catalyst) and a muffler (silencer) are 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.

That is, it can be said to be a so-called multi-point fuel injection (MPI) type engine.

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.

Furthermore, each cylinder is provided with an ignition plug 9 facing the combustion chamber 1 thereof, and each spark plug 9 is connected to an ignition coil 1o via a distributor (not shown). By turning off the power transistor 11 with the ignition coil 10, a high voltage is generated in the ignition coil 9, causing one of the spark plugs 9 connected to the distributor to spark (ignite). By turning on the power transistor 11, the ignition coil 10 starts being charged by the battery. And these spark plugs9. Distributor, ignition coil 10. The power transistor 11 constitutes 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 so as to have an appropriate air-fuel ratio, and the spark plug is mixed in the combustion chamber 1. By igniting 9 at the appropriate timing, it is combusted,
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 No, in the exhaust gas by a catalytic converter, and then muffled by a muffler and released into the atmosphere. It is designed to be emitted to the side.

Furthermore, in order to control this engine E, various sensors are provided. First, on the intake passage 2 side, an air flow sensor (engine load sensor) 13° serving as a volume flow meter that detects the amount of intake air from Karman vortex information, an intake air temperature sensor that detects the intake air temperature, and An atmospheric pressure sensor for detecting atmospheric pressure is provided, and a potentiometer-type throttle sensor for detecting the opening degree of the throttle valve 7 and an idle switch for detecting the idling state are provided in the throttle valve arrangement part.

In addition, on the exhaust passage 3 side, in a part close to the combustion chamber 1 on the upstream side of the catalytic converter, the oxygen concentration (0, concentration) in the exhaust gas is
An oxygen concentration sensor (0□ sensor) is provided to detect.

Furthermore, in addition to a water temperature sensor that detects the engine cooling water temperature, a crank angle sensor 14 that detects the crank angle (this crank angle sensor 14 is connected to the engine rotation speed N) is provided.
Since the crank angle sensor 14 also serves as an engine rotation speed sensor that detects the engine rotation speed sensor, the crank angle sensor 14 may be referred to as the engine rotation speed sensor hereinafter as needed) and the top dead center of the first cylinder (reference cylinder). A TDC sensor is provided at each distributor.

Further, a fuel composition detection means 42 for detecting the composition (type) of fuel supplied to the engine E is provided in the fuel supply passage leading to the fuel tank 46 or inside the fuel tank 46; is an optical sensor that uses a known alcohol blend ratio sensor (this sensor is an optical sensor that utilizes the fact that the critical angle at the part of the transparent body that comes into contact with the mixed fuel changes depending on the alcohol blend ratio). be done.

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 configuration from a bird-aware perspective, the ECU 15 has a CPU, RAM (including backup RAM)
, ROM, and appropriate input/output interface circuits. Signals from each sensor are input to the CPU through the input interface circuit or directly, and ignition timing control signals from the CPU are input to the power transistor 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, we are focusing on ignition timing control and ECU15.

The functional blocks for such ignition timing control are shown in FIG. 1. That is, this ignition timing control device includes first ignition timing setting means 100. Second ignition timing setting means 1o12 selection means 43. It has a changeover switch means 44.

Here, the first ignition timing setting means 100 is for setting ignition timing information when using multi-component fuel (Kalin fuel), and for this purpose, the first ignition timing setting means 100 is for setting the ignition timing information when using multi-component fuel (Kalin fuel). Vaporization characteristics/octane number setting means 21, octane number estimation means 2
22 ignition timing calculation means 232 ignition signal generation means 24.

First, the supplied fuel amount measuring means 20 measures the amount of fuel supplied to the engine intake passage 2.
It measures the amount of fuel supplied through the injector 8. For example, the amount of fuel is measured based on the time width of the fuel injection pulse supplied to the injector 8 or the amount of intake air obtained by the air flow sensor 13. .

The vaporization characteristic/octane number setting means 21 is for presetting the component ratio, vaporization characteristic, and octane number for each component of the fuel. The measurement may be performed automatically when or while the device is inserted.

The octane number estimating means 22 calculates the amount of fuel inside the combustion chamber 1 based on the supplied fuel amount obtained by the supplied fuel amount measuring means 20, the component ratio set in advance for each fuel component, the vaporization characteristics, and the octane number. The octane number estimating means 22 estimates the octane number (isometric octane number) of the fuel at A vaporization/inhalation estimating means 22A that estimates the amount of vaporization and inhalation for each component from information about vaporization characteristics and octane number, and an equivalent device that calculates an equivalent octane number from the amount of vaporization and inhalation estimated by this vaporization/inhalation estimation means 22A. octane number calculation means 22B.

The ignition timing calculating means 23 calculates the ignition timing based on the equivalent octane number estimated by the octane number estimating means 22, and furthermore, this ignition timing calculating means 23 calculates the ignition timing based on the operating state of the engine E (this operating state is determined by the engine load sensor). Stores two-dimensional ignition timing data (advance angle data) in which the ignition angle (ignition timing) is determined according to the engine load information from the air flow sensor 13 and the engine rotation speed information from the engine rotation speed sensor 14). Ignition timing map 23
It has a plurality (n) of isometric octane deviations from -1 to 23-n. In the example shown in FIG. 1, map 23-1 is for the minimum equivalent octane rating, and map 23-n
is for the maximum equivalent octane number. In addition,
Maps with numbers between 23-1 and 23-n are for equivalent octane numbers intermediate between the minimum equivalent octane number and the maximum equivalent octane number, and the lower the suffix number, the lower the equivalent octane number. be.

Further, the ignition signal generation means 24 includes the ignition timing calculation means 23
The ignition signal for operating the power transistor 11 is output based on the ignition timing information calculated from the ignition timing information.

The second ignition timing setting means 101 is for setting ignition timing information when using a single fuel (alcohol fuel), and for this purpose, the first ignition timing calculation means 40. It has an ignition signal generating means 41.

The ignition timing calculation means 40 calculates the operating state of the engine E (this operating state is based on the engine load sensor (air flow sensor) 1
, 3 and engine speed sensor 1
It has an ignition timing map that stores two-dimensional ignition timing data (advanced angle data) in which the ignition angle (ignition timing) is determined according to the engine speed information from 4).

Further, the ignition signal generation means 41 includes an ignition timing calculation means 40.
The ignition signal for operating the power transistor 11 is output based on the ignition timing information calculated from the ignition timing information.

The selection means 43 selects either the ignition timing information from the first ignition timing setting means 100 or the ignition timing information from the second ignition timing setting means 101 based on the signal from the fuel composition detection means 42. It gives a signal of
The changeover switch means 44 receives the selection signal from the selection means 43 and selects the ignition timing information from the first ignition timing setting means 100 when multi-component fuel is detected, and single fuel is selected. At this time, the ignition timing information from the second ignition timing setting means 101 can be selected and any of the ignition timing information can be supplied to the power transistor 11.

Next, the first. A method for estimating the equivalent octane number using the ignition timing setting means 100 will be explained.

First, before considering multicomponent fuels, consider single composition fuels. In this case, as shown in Figure 2, 1
If the injection amount at a time is ul, it is considered that a proportion b of the fuel is directly inhaled, and the rest adheres to the intake passage 2, and it is considered that only a of the adhering fuel x1 is inhaled through vaporization.

Then, the following equation holds true for the intake amount yi into the combustion chamber 1 and the increase in the amount of adhesion to the inner wall surface of the intake passage (x to t-xt).

yi= a X1+ b u t...(1) xbl-x
i= (1-b) ul-a xll (2) Further organizing: cr= (1-a) xi-t+ (1-b) ui-u
” (3).

Next, we extend the above theory to fuels with multiple compositions.

The adhesion amount vector for each component is 11. The inhalation amount vector for each component is yl, and the vaporization coefficient matrix for each component is AA (this AA is the diagonal component atztaztt.
・+ann is sequential vaporization coefficient aj, *a*p...t aQ
, and the other parts are O matrices), and
The weight ratio of each component x the direct inhalation rate is taken as a vector, and b is
The weight ratio matrix for each component is expressed as W (this W is the diagonal components wt, w, . . . wnn are sequentially weight ratio coefficients w, .
w, . . eWn, and the other parts are O matrices).

For multicomponent fuels, x1= (I −AA)xl−1+ (e−b)tWu
t-t"(4)Vi=AAxl+TojWul...(5
) holds true.

Here, e is a unit vector and ■ is a unit matrix.

Next, estimation of equivalent octane number will be explained.

First, let 1 be a vector in which αj is the octane number of each component. For some types of fuel, the equivalent octane number can be determined by the sum of (weight ratio x octane number), so
Approximately, the following formula can be used.

ON1=gtyt/ety, too (6) where, Os
i is the equivalent octane number at time i, and t is the transpose of the vector.

In this way, equivalent octane numbers for fuels of multiple compositions can be determined.

Note that if the error in equation (6) is large, use a data table in which the octane numbers for each weight ratio are determined in advance. in this case.

0Ni=f(@+y) (7).

Next, the procedure for calculating the ignition timing performed by the first ignition timing setting means 100 will be explained using the flowchart shown in FIG.

First, in step a1, the vaporization characteristics of each component of the fuel,
The octane number is read, the amount of injected fuel is measured in step a2, and the vaporization/intake model as described above is calculated based on this information in step a3, thereby obtaining the adhesion amount vector x1 for each component. Inhalation amount y1 for each component
seek.

Next, in step a4, the equivalent octane number is calculated, and in step a5, the engine speed and load parameters are taken in. In step a6, the ignition angle is calculated as the equivalent octane number and the engine speed.

Determined by engine load.

When one ignition angle is determined as described above (this ignition angle is calculated for each ignition timing), one ignition signal generation means 24 outputs an ignition signal based on this information.

With the above configuration, the type of fuel is determined by the fuel composition detection means 42.
At this time, when multi-component fuel is detected, the selection means 43 is switched, thereby outputting the ignition timing information from the first ignition timing setting means 100 to the power transistor 11, while When one fuel is detected, the selection means 43 is switched, thereby outputting the ignition timing information from the second ignition timing setting means 101 to the power transistor 11.

At this time, first, in the first ignition timing setting means 100,
The octane number estimating means 22 determines the octane number of the fuel in the combustion chamber 1 based on the amount of supplied fuel obtained by the supplied fuel amount measuring means 20 and information on the vaporization characteristics and octane number preset for each component of the fuel. is estimated, and then the ignition timing calculation means 23 calculates one ignition timing based on the octane number estimated by the octane number estimation means 22.

In this way, appropriate ignition timing information can be set when using any fuel, but when determining the ignition timing with the first ignition timing setting means 100, a required mathematical model is used to set the ignition timing information in the combustion chamber. Since it is possible to estimate the equivalent octane number during combustion in real time and obtain ignition timing information based on this equivalent octane number, it is possible to improve output and fuel efficiency without unnecessarily delaying the ignition angle. Optimal ignition timing control can be achieved. In particular, even if the octane number decreases during acceleration, ignition timing information is retrieved from the appropriate map 23-i (i = 1 to n), and thereby the optimal ignition angle that does not cause knocking is always set. Therefore, knocking during acceleration can be reliably prevented while preventing rapid acceleration as much as possible.

This makes it possible to increase engine output, improve engine efficiency, and significantly improve acceleration performance.

Furthermore, when obtaining the ignition timing information with the second ignition timing setting means 101, the ignition timing is set more than necessary because the ignition timing is not controlled by a decrease in the octane number during a transient period as in the first ignition timing setting means 100. This helps improve engine output and fuel efficiency without slowing down the process. Furthermore, since ignition timing information can be easily obtained from the map, control is also simple.

Note that a display means 45 for displaying the detection results of the fuel composition detection means 42 may be provided, for example, in the vehicle interior, and in this case,
Instead of using the automatic switch switching method as described above, a method may be adopted in which, for example, the passenger looks at the display contents on the display means 45 and manually switches the changeover switch means 44.

In this case, if the 9th passenger still does not switch the changeover switch means 44 even though the changeover display is displayed, the first passenger is alerted, and if the changeover still does not occur, the changeover switch means 44 is automatically switched. .

Note that the ignition timing calculation means 23 of the first ignition timing setting means 100 is provided with an ignition timing map for the nominal octane number, and if the estimated octane number does not deviate much from the nominal octane number, the ignition timing map for the nominal octane number is calculated. It is also possible to use the ignition timing map and perform one ignition timing correction only when the estimated octane number deviates significantly from the nominal octane number.

Further, even if a multicomponent fuel is used, if the composition ratio of the -component among the fuels is extremely large, control may be performed to treat the fuel as a single component. In this case, an ignition timing map for the single component considered is separately prepared in the ignition timing calculation means 40.

Furthermore, the ignition timing calculation means 23 of the first ignition timing setting means 100 is constituted by a basic ignition timing setting means, an ignition timing correction amount setting means, and an addition means for adding the information obtained by these means, The basic ignition timing obtained according to the engine operating state may be corrected by the ignition timing correction amount obtained according to the isometric octane number and used as the ignition timing information.

Furthermore, when controlling the ignition timing, corrections may be added in accordance with the water temperature and the intake air temperature.

Furthermore, the present invention is applicable to spark-ignition internal combustion engines that use the Jetro system using an air flow sensor, as well as spark-ignition internal combustion engines that use the D-Jetro system (speed density system) that uses an intake passage pressure sensor. It is possible.

[Effects of the Invention] As detailed above, according to the ignition timing control device for a spark-ignited internal combustion engine of the present invention as set forth in claim 1, the spark ignition timing control device for a spark-ignition internal combustion engine according to the present invention can use both a multi-component fuel and a single fuel. In an ignition type internal combustion engine, a first ignition timing setting means for setting ignition timing information when using a multi-component fuel, and a second ignition timing setting means for setting ignition timing information when using a single fuel. With a simple configuration, a selection means is provided for selecting the ignition timing information from the first ignition timing setting means and the ignition timing information from the second ignition timing setting means and supplying the selected ignition timing information to the ignition device. The advantage is that appropriate ignition timing information can be set in all operating ranges, including transitional periods such as during acceleration, and when using any fuel.

Further, according to the ignition timing control device for a spark-ignition internal combustion engine of the present invention according to claim 2, the octane number during combustion in the combustion chamber is estimated in real time using a required mathematical model,
Since ignition timing information when using multi-component fuel can be obtained based on this estimated octane number, it is possible to achieve optimal ignition timing control for improving output and fuel efficiency without unnecessarily delaying the ignition angle. In particular, even if a drop in octane occurs during acceleration, appropriate ignition timing information is retrieved, and this allows the optimum ignition angle to be set without knocking at all times, so that rapid acceleration is not hindered as much as possible. This has the advantage that knocking during acceleration can be reliably prevented, and as a result, engine output can be increased, engine efficiency can be increased, and acceleration performance can be significantly improved.

[Brief explanation of the drawing]

1 to 3 show an ignition timing control device for a spark ignition internal combustion engine as an embodiment of the present invention. FIG. 1 is an overall configuration diagram showing the control system and a schematic engine system. A diagram explaining the combustion octane number estimation model,
FIG. 3 is a flowchart for determining the ignition timing. 1-combustion chamber, 2-intake passage, 3-exhaust passage, 4-intake valve, 5-exhaust valve, 6-air cleaner, 7-throttle valve,
8 - Solenoid valve (injector), 9 - Spark plug constituting the ignition device, 10 - Ignition coil, 11 - Power transistor, 13 - Air flow sensor (volume flow meter) as an engine load sensor, 14 - Crank angle sensor (engine 15-ECU, 20-supply fuel amount measuring means, 21-vaporization characteristic/octane number setting means. 22 - octane number estimation means, 22A - vaporization/intake estimation means, 22B - isometric octane number calculation means, 23 - ignition timing calculation means, 23-1.23-n - ignition timing map,
24-Ignition signal generating means (igniter operating means), 40-
Ignition timing calculation means, 41-Ignition signal generation means (ignition device operation means), 42-Fuel composition detection means, 43-Selection means, 44-Switch means, 45-Display means, 46-Fuel tank, 100-First Ignition timing setting means, 101-second
Ignition timing setting means for E-engine.

Claims (2)

[Claims] (1) In a spark-ignition internal combustion engine that can use either a multi-component fuel or a single fuel, a first ignition timing setting means for setting ignition timing information when using the multi-component fuel; a second ignition timing setting means for setting ignition timing information when one fuel is used, the ignition timing information from the first ignition timing setting means and the ignition timing from the second ignition timing setting means; An ignition timing control device for a spark-ignition internal combustion engine, characterized in that it is provided with selection means that can select information and supply it to an ignition device. (2) The first ignition timing setting means includes a supplied fuel amount measuring means for measuring the amount of fuel supplied to the internal combustion engine, the supplied fuel amount obtained by the supplied fuel amount measuring means, and the components of the fuel. an octane number estimating means for estimating the octane number of the fuel in the combustion chamber based on information regarding the vaporization characteristics and octane number preset for each case; and an ignition timing for determining the ignition timing based on the octane number estimated by the octane number estimating means. 2. The ignition timing control device for a spark ignition internal combustion engine according to claim 1, further comprising a calculation means.