JPS631760A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve combustion efficiency, by a method wherein the ignition timing of a given cylinder, where knocking is apt to occur and that of other cylinder are set by their respective different methods, and an ignition timing can be corrected so as to match the knocking occurring tendency of a cylinder. CONSTITUTION:A fundamental ignition timing memory means A is provided for storing a fundamental ignition timing at each of small regions, into which an engine running region is fractionated, in relation to a given cylinder where knocking is apt to occur. A deviation memory means B is provided for storing a deviation between a fundamental ignition timing, determined at each region formed such that small regions are divided into plural regions in one lot, and average ignition timing, being obtained by averaging fundamental ignition timings in plural small regions in a given cylinder contained in the same region. In an ignition timing set means C, an ignition timing is set, based on a fundamental ignition timing by the memory means A, in relation to a given cylinder, and an ignition timing is set, based on a value, to which a fundamental ignition timing and a deviation are added, in relation to other cylinder.

Description

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

<Prior art> In electronically controlled ignition systems for internal combustion engines, the engine operating range is generally subdivided based on engine speed, load (fuel injection amount), etc., and the basic ignition timing is set according to the operating state. is stored in the memory (ROM) of a microcomputer, and the ignition timing is controlled based on the basic ignition timing retrieved from the memory according to the engine operating conditions (see Japanese Patent Application Laid-Open No. 184967/1984).

<Problems to be Solved by the Invention> By the way, in such a conventional ignition system, although there is variation in the tendency for knocking to occur from cylinder to cylinder even if the -a function is the same, the basic ignition timing is different from cylinder to cylinder. Since this is not set, the ignition timing of each cylinder will be uniformly controlled.

In order to prevent knocking, especially in models that use a simple control method that does not use a knocking sensor, the basic ignition timing is set to a considerably retarded side to match the cylinder where knocking is most likely to occur, resulting in non-knocking. In cylinders that are difficult to control, the combustion efficiency is forcibly retarded even though there is still some margin, making it impossible to increase combustion efficiency and resulting in a reduction in output.

Although it is possible to control the ignition timing to the very edge of the knocking generation limit using a non-king sensor, it is difficult to say that all cylinders have reached near the non-king generation dust range, so the engine as a whole does not necessarily have to maximize its output. It wasn't something that could be improved upon.

In order to solve the above problem, it may be possible to set the basic ignition timing independently for each cylinder, but in this case, the memory data of the basic ignition timing would be required to be stored twice as many times as the number of cylinders, which would increase significantly. It is impractical because it requires a memory with a large capacity, resulting in a significant increase in cost.

The present invention has been made by focusing on these conventional problems, and provides an ignition timing control for an internal combustion engine that enables excellent ignition timing control to be performed independently for each cylinder by simply increasing the number of stored data. The purpose is to provide a timing control device.

Means for Solving Problems> For this reason, the present invention, as shown in FIG. A basic ignition timing storage means stores the basic ignition timing determined accordingly, and for each cylinder other than the predetermined cylinder, the operating state of each cylinder is stored in each region divided into a plurality of small regions. deviation storage means storing a deviation between the basic ignition timing obtained according to the above and the average ignition timing obtained by averaging the basic ignition timing of a plurality of small regions in the predetermined cylinder included in the same region; , for the predetermined cylinder, the ignition timing is set based on the basic ignition timing retrieved from the small area corresponding to the engine operating condition of the basic ignition timing storage means, and for each other cylinder, the ignition timing is set. The ignition timing is set based on the sum of the basic ignition timing retrieved from a small area corresponding to the engine operating condition of the basic ignition timing and the deviation retrieved from the area corresponding to the engine operating condition of the deviation storage means. The configuration includes ignition timing setting means.

<Operation> For a predetermined cylinder where knocking is likely to occur, a good ignition timing that prevents knocking is set based on the basic ignition timing retrieved from the basic ignition timing storage means for each small region.

For each other cylinder, the value is the sum of the basic ignition timing retrieved from the basic ignition timing storage means for each small region and the deviation of the corresponding region retrieved from the deviation storage means in the same way as for the predetermined cylinder. Ignition timing is set based on. Therefore, the ignition timing can be set for each small region as in the case of a predetermined cylinder, and by adding the deviation, the ignition timing can be corrected in accordance with the knocking tendency of the cylinder, and the combustion efficiency can be increased as much as possible.

Furthermore, the number of deviation data stored can be made sufficiently smaller than the number of basic ignition timing data, so there is no need to use an expensive memory with a large storage capacity.

(Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing one embodiment, an internal combustion engine 1 is provided with a rotation speed sensor 2 that detects an engine rotation speed N, and an air flow meter 4 that detects an intake air flow fiQ and an electromagnetic type A fuel injection valve 5 is provided. The engine rotation speed N signal from the rotation speed sensor 2 and the intake air flow 1iQ signal from the air flow meter 4 are input to a control unit 6 containing a microcomputer. The control unit 6 calculates the fuel injection amount Tp based on the engine speed N, the intake air flow rate Q, etc., and calculates the fuel injection amount '
An injection signal corresponding to rp is output to the fuel injection valve 5 to perform fuel injection, and the engine speed N and fuel injection f
The ignition timing for each cylinder is calculated based on f1Tp (load), etc. as will be described in detail later, and an ignition signal is output to the ignition plug 7 provided in the cylinder corresponding to the ignition timing to cause ignition. It has become.

Here, the memory of the microcomputer built in the control unit 6 stores information about the engine as shown in FIG. Basic ignition timing PffiJ determined experimentally according to the operating state of the relevant cylinder for each of a total of 255 sub-regions obtained by subdividing the operating region into lattices of 16 each for engine speed N and fuel injection ITp.
is what I remember.

Similarly, the memory also contains a fourth cylinder for each cylinder (second, third, and fourth cylinders) other than the predetermined cylinder (first cylinder).
As shown in the figure, a plurality of small regions in which the basic ignition timing Pij data is stored are grouped together and divided into three grids each for engine speed N and fuel injection amount Tp, resulting in a total of nine regions. For each cylinder, the ignition timing is determined experimentally according to the operating condition of each cylinder, and the average is determined by averaging the basic ignition timing of a plurality of small regions of the predetermined cylinders included in the same region. The deviation (advanced angle value) ΔPin from the ignition timing is stored.

That is, the memory constitutes basic ignition timing storage means and deviation storage means.

Then, the CPU of the microcomputer sets the ignition timing for the first cylinder based on the basic ignition timing retrieved from a small area corresponding to the engine operating conditions, and sets the ignition timing for the other second to fourth cylinders. Then, the ignition timing is calculated based on the sum of the basic ignition timing retrieved in the same manner as for the first cylinder and the deviation retrieved from the corresponding area of the deviation storage means.

That is, the CPU constitutes ignition timing setting means.

The ignition timing control routine by the control unit 6 will be explained with reference to the flowchart shown in FIG.

In step 1 (denoted as Sl in the figure; the same applies hereinafter), the basic ignition timing of the corresponding small region is searched from the basic ignition timing map stored in the memory, based on the engine speed N and the fuel injection ff1Tp.

Next, in steps 2 to 4, it is determined whether the cylinder to be ignited next time is the second cylinder, the third cylinder, or the fourth cylinder, and if the determination is NO in any case, it is the first cylinder, so step 5, the basic ignition timing stored in step 1 is temporarily stored in the register of the microcomputer as it is.

If it is determined in step 2 that it is the second cylinder, step 6
Based on the engine speed N and the fuel injection ITp,
The deviation in the corresponding area is searched from the deviation map for the second cylinder stored in the memory.

Next, in step 7, after adding the basic ignition timing of the first cylinder found in step 1 and the deviation found in step 6, the process proceeds to step 5 and stores this value in a register.

Similarly, if it is determined in step 3 that it is the third cylinder,
In step 8, the deviation is searched from the map for the 3rd cylinder, and after addition in step 9, the process proceeds to step 5. When the 4th cylinder is determined in step 4, the deviation is searched from the map for the 4th cylinder in step 10. After addition in step 11, the process proceeds to step 5.

In this way, the ignition timing signal stored in the register is output at a predetermined crank angle position, counted by a counter, and when the ignition timing is reached, an ignition signal is output to the ignition plug of the corresponding cylinder to start ignition. It will be done.

With such control, it goes without saying that good ignition timing control can be performed for the first cylinder, which has a high tendency to cause knocking, by using the basic ignition timing set for the first cylinder as is. Even in the second to fourth cylinders, by adding the deviation to the basic injection timing searched for each of the small regions, the ignition timing can be corrected according to the operating condition of each cylinder, suppressing the occurrence of knocking. At the same time, combustion efficiency can be increased as much as possible, and engine output can thereby be improved.

Furthermore, although it is ideal to set the basic ignition timing for each small area in each cylinder, the difference between the deviation for a group of multiple small areas and the deviation for the small area is small, and the basic ignition timing is for the small area. Since it uses , it is possible to set a sufficiently good ignition timing. By storing the deviation in each region where the deviation is relatively large, the increase in the number of stored data can be significantly reduced compared to the case where the basic ignition timing is set in each small region for each cylinder.

Therefore, the conventional memory is often sufficient, but if it cannot be done in time, simply reduce the number of grid axes that divide the small area where the basic ignition timing is stored by one (14 x 14). , Even if this is done, the accuracy is hardly affected.

Incidentally, in the case of this embodiment, the number of stored data of only basic ignition timing is 15 x 15 = 225 in the conventional case, whereas 3 x 3
Whereas it only requires an increase of about 10% for X3 = 27 pieces,
If you want to set the basic ignition timing for each cylinder, use 225x 3.
It is necessary to increase the number of data by =675.

Note that the non-king sensor may be used to perform feedpack correction control on the ignition timing set for each cylinder as described above, which is possible because the ignition timing can be controlled to the very edge of the knob king limit for each cylinder. output can be improved.

<Effects of the Invention> As explained above, according to the present invention, ignition timing control corresponding to the tendency of knocking in each cylinder can be performed by simply increasing the number of stored data, and the engine output can be improved. .

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration 1 function of the present invention, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a basic ignition timing map used in the above embodiment, and Fig. 4 is a Similarly, FIG. 5 is a flow chart showing the ignition timing control routine. 1... Internal combustion engine 2... Rotation speed sensor 6...
・Control unit 7... Spark plug patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 3 Figure 4

Claims (1)

[Claims] a basic ignition timing storage means that stores basic ignition timing determined according to the operating state of the cylinder for each subregion obtained by subdividing the engine operating region for a predetermined cylinder that is likely to cause knocking; For each cylinder, the basic ignition timing determined according to the operating state of each cylinder is determined for each area in which a plurality of the above-mentioned small areas are grouped together, and the basic ignition timing for each of the predetermined cylinders included in the same area. a deviation storage means for storing a deviation from an average ignition timing obtained by averaging basic ignition timings in a small area of the area; The ignition timing is set based on the basic ignition timing retrieved from the small region, and for each other cylinder, the basic ignition timing is set based on the basic ignition timing retrieved from the small region corresponding to the engine operating condition of the basic ignition timing, and the An ignition timing control device for an internal combustion engine, comprising ignition timing setting means for setting the ignition timing based on a value obtained by adding the deviation searched from the area corresponding to the engine operating condition of the deviation storage means. .