JPH0385371A - Ignition time controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To constantly obtain optimum ignition timing by providing two storage means, which dispersively memorize in the form of lattice-points the ignition timing corresponding to various engine operating conditions, and calculating the ignition timing through an interpolation method. CONSTITUTION:A first storage means A, which dispersively memorizes in the form of lattice points the prescribed ignition timing corresponding to a first engine operating condition, and a second storage means B, which dispersively memorizes in the form of lattice points the ignition timing, which corresponds to a second engine operating condition and differs from the ignition timing corresponding to the first engine operating condition for the same engine load and engine speed, are provided. According to the engine operating condition, either storage means A or B is selected by means of a selecting means C. Based on the lattice point of the storage means A or B selected, the ignition timing corresponding to the engine operating condition is calculated by a calculating means D, using an interpolation method. In complying with this ignition timing, a spark is generated from a spark plug 5, thereby driving an engine.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an ignition timing control device for an internal combustion engine.

[Conventional technology]

Ignition timing control devices are known that store ignition timing discretely in advance in the form of grid points as a function of engine load and engine speed, and calculate ignition timing by interpolation from these grid points (for example, See Publication No. 62-48944>.

Furthermore, an ignition timing control device is known that increases the fuel injection amount and advances the ignition timing in order to increase the engine output during high-load engine operation. (For example, see Japanese Patent Application Laid-Open No. 60-256536).

On the other hand, currently, an ignition timing map is used that takes into account the effect of increasing the amount of fuel injection in order to calculate the ignition timing. Fig. 6 (A) shows an example of the ignition timing map currently used, and in this ignition timing map, the intake pipe absolute pressure (pH, PI3...>
and engine speed (NBI).

The ignition timing at each grid point is determined as a function of N22...>. The intake pipe absolute pressure and engine speed between each grid point are calculated by interpolation from the ignition timing at each grid point. In addition, Fig. 6 (A) shows a case where the fuel injection amount is increased when the throttle valve opening becomes larger than a predetermined opening, and shows the intake pipe absolute pressure and the engine at this opening. The relationship with the rotational speed is shown by a chain line X. In other words, the region above the chain line The ignition timing is advanced compared to the ignition timing at each grid point in the lower region. This can be understood more clearly by referring to FIG. 6(B). Figure 6 (B)
Absolute intake pipe pressure (PMl, PN
2...> and the ignition timing θ, and the fuel injection amount is increased on the right side of the chain line X. A curve Y shown by a solid line indicates a desirable ignition timing when the fuel injection amount is not increased. Therefore, each grid point is located on the curve Y when the fuel injection amount is not increased. On the other hand, a curve Z indicated by a broken line indicates a desirable ignition timing when the fuel injection amount is increased, and therefore each grid point is located on the curve Z when the fuel injection amount is increased. Therefore, from FIG. 6(B), it can be seen that when considering the same engine load and rotation speed, the ignition timing when the fuel injection amount is increased is advanced compared to the ignition timing when the amount is not increased.

[Problem to be solved by the invention]

However, when the ignition timing is calculated using the ignition timing map shown in FIG. 6, the ignition timing deviates significantly from the desired ignition timing when the engine operating state is near the chain line X. For example, in Fig. 6 (B), if the current intake pipe absolute pressure is Pl, then the ignition timing is calculated by interpolation from the grid point a on the curve Y and the grid point on the curve Z, so it is 0 point. The indicated ignition timing will be reached. However, in this case, since the operating state of the engine is on the left side of the chain line X, the desired ignition timing is at point d on the curve Y. Therefore, the ignition timing C obtained by the interpolation calculation will deviate toward the advance side with respect to the desired ignition timing d.

On the other hand, if the current intake pipe absolute pressure is P2, the ignition timing at this time is also calculated by interpolation from the grid point a on the curve Y and the grid point on the curve Z, so the ignition timing is the ignition timing indicated by the point d. Become. However, in this case, the operating state of the engine is indicated by the dashed line
Therefore, the desirable ignition timing is point e on the curve Z. Therefore, the ignition timing d obtained by the interpolation calculation will be retarded with respect to the desired ignition timing e.

As described above, when the ignition timing map shown in FIG. 6 is used, a problem arises in that the ignition timing near the chain line X deviates to the advanced or retarded side with respect to the desired ignition timing.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, as shown in the constituent countries of the invention in FIG. In the ignition timing control device that interpolates and calculates the ignition timing from these grid points, a first storage means A stores the ignition timing for a predetermined first engine operating state discretely in the form of grid points. and the ignition timing for a predetermined second engine operating state, which is different from the ignition timing for the first engine operating state at the same engine load and rotation speed, is discretely stored in the form of grid points. a second storage means B that has been selected; a selection means C that selects whether to use the first storage means or the second storage means according to the operating state of the engine; The engine is equipped with calculation means for interpolating ignition timing according to the operating state of the engine.

[For production]

When the engine is in the first operating state, the ignition timing is calculated by interpolation from grid points representing the ignition timing desired for that operating state, and when the engine is in the second operating state, the ignition timing is calculated by interpolation from the grid points representing the ignition timing desirable for the operating state. Since the ignition timing is calculated by interpolation from the grid points, the calculated ignition timing is always the desired ignition timing.

〔Example〕

Referring to Figure 2, 1 is the engine body, 2 is the piston, and 3
indicates the cylinder head, 4 indicates the combustion chamber, 5 indicates the spark plug, 6 indicates the intake valve, 7 indicates the intake port, 8 indicates the exhaust valve, and 9 indicates the exhaust port. It is connected to the tank 11.

A fuel injection valve 12 is attached to each branch pipe 10, and fuel is injected from these fuel injection valves 12 into the corresponding intake port 7. The surge tank 11 is connected to an air cleaner (not shown) via an intake duct 13, and a throttle valve 14 is disposed within the intake duct 13. On the other hand, the exhaust port 9 is connected to an exhaust manifold 15, and an oxygen concentration detector 16 is disposed within the exhaust manifold 15. The fuel injection valve 12 and the ignition plug 5 are connected to an electronic control unit 30, and the injection timing from the fuel injection valve 12 and the ignition timing by the ignition plug 5 are controlled based on the output signal of the electronic control unit 30.

The electronic control unit 30 consists of a digital computer with ROMs connected to each other by a bidirectional bus 31.
(read only memory) 32, RAM (random access memory) 33, CPU (microprocessor) 34
, an input port 35 and an output port 36. An absolute pressure sensor 17 that generates an output voltage proportional to the absolute pressure inside the surge tank 11 is attached to the surge tank 11, and the output voltage of the absolute pressure sensor 17 is input to the input port 35 via the AD converter 37. Ru. Oxygen concentration detector 1
6 generates an output voltage of about 0.1 volt when the air-fuel mixture supplied to the engine cylinder is lean, and an output voltage of about 0.9 volt when the air-fuel mixture supplied to the engine cylinder is rich. occurs. The output voltage of the oxygen concentration detector 16 is input to the input port 35 via the AD converter 38. Further, the throttle valve 15 has a throttle valve 15.
A throttle sensor 18 is attached to detect that the opening degree has become larger than a predetermined opening degree, and the output signal of this throttle sensor 18 is input to the input port 35. Further, a water temperature sensor 19 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine body 1, and the output voltage of this water temperature sensor 19 is inputted to the human power port 35 via the AD converter 39. The top dead center detection sensor 20 is 180
The crank angle sensor 21 generates an output pulse for every 30 crank angles, and the top dead center detection sensor 20 and the crank angle sensor 21
The output pulse of is input to the input port 35. In the electronic control unit 30, the current crank angle is calculated from the output pulses of the top dead center detection sensor 20 and the crank angle sensor 21, and the engine rotation speed is calculated from the output pulses of the crank angle sensor 21.

On the other hand, the output port 36 is connected to the spark plug 5 and the fuel injection valve 12 via a corresponding drive circuit 40.41.

FIG. 3(A) shows an ignition timing map similar to FIG. 6(A). Similarly to FIG. 6(A), the chain line X indicates the engine operating state when the throttle valve 14 is at the set opening, and the fuel injection amount is increased in the region above the chain line X. Therefore, the ignition timing at each grid point in the area above the chain line X is advanced compared to the ignition timing at each grid point in the area below the chain line X, considering the same engine load and engine speed. By the way, when the operating state of the engine is near the chain line X, the ignition timing is calculated by interpolation from the grid points in the area above the chain line X and the grid points in the area below the chain line X. In this case, if the operating state of the engine is in the region below the chain line X, the grid points in the region below the chain line X and the grid points on the solid line M are used for interpolation calculation of the ignition timing.

On the other hand, when the operating state of the engine is in an area above the chain line X, grid points in the area above the chain line X and grid points on the dashed line N are used for interpolation calculation of the ignition timing. Therefore, in the embodiment shown in FIG. 3, as shown in FIG. 3(B),
Ignition timing map I with solid line M as the upper limit, and Figure 3 (C
), an ignition timing map (■) whose lower limit is the broken line N in FIG. 3(A) is used. Each grid point of the ignition timing map ■ represents the desired ignition timing when the fuel injection amount is not increased, and each grid point of the ignition timing map ■ represents the desired ignition timing when the fuel injection amount is increased. It represents. When the operating state of the engine is in the region below the chain line X in Figure 3 (A>), the ignition timing is interpolated from the ignition timing map I shown in Figure 3 (B). In this case,
Each grid point of the ignition timing map (■) indicates a desirable ignition timing when the fuel injection amount is not increased, and therefore, the ignition timing calculated by interpolation from the ignition timing map is the desired ignition timing. On the other hand, the operating state of the engine is shown in Figure 3 (A
), the ignition timing is calculated by interpolation from the ignition timing map (2) shown in FIG. 3(C). In this case, each grid point of the ignition timing map (2) indicates a desirable ignition timing when the fuel injection amount is increased, and therefore, the ignition timing calculated by interpolation from the ignition timing map (2) becomes the desired ignition timing. Ignition timing map I and ignition timing map ■ are stored in advance in the ROM 32 and are used selectively depending on the operating state of the engine.

Next, ignition timing control using these ignition timing map I and ignition timing map II will be explained with reference to FIGS. 4 and 5.

FIG. 4 shows a routine for calculating the fuel injection time, and this routine is executed by interruption at every fixed crank angle.

Referring to FIG. 4, first, in step 50, a basic fuel injection time TP is calculated from the intake pipe absolute pressure detected by the absolute pressure sensor 17 and the engine speed. Next, in step 51, it is determined whether the opening degree TA of the throttle valve 14 is larger than a predetermined set opening degree TA0 (dashed line X in FIG. 3) based on the output signal of the throttle sensor 17.TA, When TAo is reached, the process proceeds to step 52, where the power increase coefficient Kl is set to 1.0, and the process proceeds to step 55.In step 55, the fuel injection time TAU is determined based on the following equation.
is calculated.

TAU=TP −FAF −+ ・K2 where F
AF is a feedback correction coefficient for maintaining the air-fuel ratio at the target air-fuel ratio based on the output signal of the oxygen concentration detector 16, and this FAF takes a value near 1.0. On the other hand, K.
2 is a correction coefficient that changes depending on engine cooling water temperature and the like.

In the case of TA, TA, the feedback correction coefficient FAF
The fuel injection time T is set so that the air-fuel ratio becomes the target air-fuel ratio.
Since AU is determined, the air-fuel ratio is maintained at the target air-fuel ratio.

On the other hand, when TA>TAo, the process proceeds to step 53 and the power increase coefficient is set to Ka (>1.0). Next, in step 54, FAF is set to 1.0, and then the process proceeds to step 55. Therefore, at this time, the fuel injection amount is increased and the air-fuel ratio is made smaller than the target air-fuel ratio.

FIG. 5 shows an ignition timing calculation routine, and this routine is executed by interruption at every fixed crank angle.

Referring to FIG. 5, first, in step 60, it is determined whether the opening degree TA of the throttle valve 14 is larger than the set opening degree TAo. When TA, TA, the basic ignition timing θb is calculated by interpolation from the grid points of the ignition timing map I shown in FIG. 3(B). Next, in step 63, a correction value θ, which changes depending on the engine cooling water temperature, etc., is calculated, and the process proceeds to step 64. In step 64, the ignition timing θ is calculated based on the following equation.

θ=θ, 10. On the other hand, when TA>TAo, the process proceeds to step 62, where the basic ignition timing θ is calculated from the lattice points of the ignition timing map ■ shown in FIG. 3(C), and then the process proceeds to step 63. move on.

In this manner, by selectively using the two ignition timing maps I and (2) depending on the operating state of the engine, the ignition timing can be set to a desired ignition timing regardless of whether or not there is an effect of increasing the fuel injection amount.

Although the case where the desired ignition timing changes depending on whether or not there is an effect of increasing the fuel injection amount has been explained so far, the present invention is applied to a case where there are different desired advance angle amounts under the same engine load and rotation speed. be able to.

For example, there is a desirable advance amount for a first engine operating state such as light load operation, and a desirable advance amount exists for another second engine operating state, and the engine load and rotation speed are Considering the same case, it can be applied to cases where these advance angle amounts are different.

As shown in Figure 3, each ignition timing map only requires storing the ignition timing of the grid points necessary when calculating the ignition timing based on each map, and the total engine speed and total intake air Since it is not necessary to store the ignition timing of all grid points relative to the absolute pipe pressure, the amount of data to be stored does not increase significantly.

〔Effect of the invention〕

A desired ignition timing can always be calculated by interpolation from ignition timings stored discretely in the form of grid points.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the invention, Fig. 2 is an overall view of an internal combustion engine, Fig. 3 is a diagram showing an ignition timing map used in an embodiment of the invention, and Fig. 4 is a diagram for calculating fuel injection time. FIG. 5 is a flowchart for calculating the ignition timing, and FIG. 6 is a diagram showing the ignition timing map currently used. 5... Spark plug, 14... Throttle valve. 12...Fuel injection valve,

Claims (1)

[Claims] In an ignition timing control device that stores ignition timing in advance in the form of grid points discretely in accordance with the operating state of the engine, and calculates the ignition timing by interpolation from these grid points, a predetermined first a first storage means that stores ignition timing discretely in the form of grid points for a predetermined second engine operating state; a second storage means that discretely stores ignition timing different from the ignition timing of the first engine operating state in the form of grid points; and the first storage means or the second storage means depending on the engine operating state. An ignition timing control device for an internal combustion engine, comprising a selection means for selecting which one to use, and a calculation means for interpolating and calculating the ignition timing according to the operating state of the engine from the grid points of the selected storage means.