JPH03117684A - Ignition device for engine - Google Patents

Abstract

PURPOSE:To ensure uniformity of propagation of flame by providing a phase set means to set a phase difference between the ignition timings of a plurality of ignition gaps disposed around a cylinder and a phase regulating means to regulate the phase difference. CONSTITUTION:Three ignition plugs 10 - 12 are disposed at intervals of a 120 deg. arc around a cylinder part 2a in a manner to front on a combustion chamber 4. Based on the number of revolutions of an engine and an intake air amount detected by sensors 20 and 21, a controller unit U determines the ignition timing of a first ignition plug 10 from a map. The ignition timings of ignition plugs 11 and 12 are set by regulating a phase difference from the first ignition plug 10 being a reference ignition plug according to an ignition advance amount of the ignition plug 10. This constitution ensures uniformity of propagation of flame regardless of an operation state in relation to a peripheral multiignition engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ignition system for an engine in which a plurality of ignition gaps are provided at intervals around a cylinder.

(Prior art) As one of the means for purifying exhaust gas,
As seen in Japanese Patent No. 077, so-called peripheral multi-point ignition is known in which a plurality of ignition gaps are arranged at intervals around a cylinder. In this peripheral multi-point ignition, it is desirable that the flame formed in each ignition gap propagate uniformly. In other words, ideally there should be no difference in the spread of flame from each ignition gap.

(Problem to be solved by the invention) However, the temperature, concentration, and
The flow state etc. are non-uniform, and as a result, the flame in one ignition gap spreads quickly, and the flame in other ignition gaps spreads slowly, making it difficult to make flame propagation uniform.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ignition system for an engine that ensures uniformity of flame propagation based on the above-mentioned peripheral multi-point ignition.

Means for Solving Problem C) The present invention provides a phase difference in the ignition timing of each ignition gap,
The ignition timing for ignition gaps located in areas where flame propagation is slow is set earlier, and the ignition timing for ignition gaps located at areas where flame propagation is faster is set later. Then, in order to obtain uniform flame propagation over a wide operating range, we learned that the above phase difference should be adjusted in proportion to the ignition advance amount of the ignition gap, which serves as a reference, and we created the following configuration. It's Toshide.

That is, as shown in Fig. 1, when there are a plurality of ignition gaps arranged at intervals around the circumference of the cylinder, and one ignition gap among the plurality of ignition gaps is taken as a reference ignition gap, , between the ignition timing of the reference ignition gap and the ignition timing of other ignition gaps, respectively.
The present invention is configured to include a phase setting means for setting a phase difference, and a phase adjustment means for adjusting the phase difference in proportion to the ignition advance amount of the reference ignition gap.

(Example) Hereinafter, an example of the present invention will be described based on the attached drawings.

In Fig. 2, 1 is the engine body, 2 is the cylinder block, and 3 is the cylinder head.
A piston (not shown) is fitted into the cylinder part 2a formed in the cylinder part 2a, and the space sandwiched between the piston and the cylinder head 2 serves as a combustion chamber 4. Two intake boats provided 5.6 and 2
The two exhaust ports 7.8 are opened and the intake ports 5.8 and 5.8 are opened.
An intake valve (not shown) is provided at 6, and an exhaust port 7
．． 8 is provided with an exhaust valve (not shown). and,
Three spark plugs 10, 11, 12 are arranged around the cylinder part 2a at 120 degree intervals so as to face the combustion chamber 4, and these three spark plugs 10, 11, 12
, the first spark plug lo is provided adjacent to one exhaust port 7, the second spark plug 11 is provided adjacent to the other exhaust port 8, and the third spark plug 12 is provided adjacent to one exhaust port 7. Ignition coils 13 to 15 are attached to each of these spark plugs 10 to 12, respectively, which are arranged between the intake boats 5 and 6, and the ignition of each of the spark plugs IO to 12 is controlled by a control unit U. It is supposed to be done.

That is, the sensor 20 is connected to the control unit U.
．． A signal from 21 is input. The sensor 20 detects the engine speed. The sensor 21 detects the amount of intake air. and control unit U
receives these signals, calculates the ignition timing according to the operating state for each spark plug 10-12, and outputs an ignition signal to the corresponding ignition coil 13-15.

Before specifically explaining ignition timing control, the experimental results that form the basis thereof will be explained.

In FIG. 2, an engine was prepared in which three spark plugs were added in addition to spark plugs 10-12, and these six spark plugs were provided at intervals of 60 degrees.

Now, connect each spark plug to No. 2 as shown in Figure 2.

1, No. 2, -No. 6, the ignition timing of each spark plug No. 1 to No. 6 was investigated to ensure uniform combustion while observing the combustion state of the engine. Then, under various operating conditions, the phase difference between the ignition timing of the No. 1 spark plug (reference spark plug) and the ignition timing of the other spark plugs is determined, and if this phase difference is determined, the No. 1 spark plug (
When we investigated how the ignition angle changes with respect to the ignition advance angle of the standard spark plug, we obtained the results shown in Figure 3. As understood from this Fig. 3, No. 1 spark plug (
It can be seen that there is a proportional relationship between the ignition advance amount of the reference spark plug (reference spark plug) and the above phase difference.

Based on the above knowledge, in this embodiment, as shown in FIG. 4, the ignition timing of the first spark plug 10 is adjusted in step s2 based on the intake air amount and engine rotation speed read in step S1 is obtained from the map, and the next step S3
The ignition timing of the second and third ignition plugs 11 and 12 is calculated, and when the ignition timing of each of these ignition plugs 10 to 12 comes, an ignition signal is output to each of the ignition plugs 10 to 12. . That is, the ignition timing T1 of the first ignition plug 10 is set at an ignition advance angle according to the operating condition from the map, and the ignition timing T2 . spark plug 12
The ignition timing T3 is set by adjusting the phase difference from the first ignition plug 10, which is the reference ignition plug, according to the ignition advance amount of the first ignition plug 10. Of course, the phase difference between the second and third spark plugs 11.12 is determined based on the results of actual combustion in the corresponding engine, and the ignition timing T2. T3 is calculated based on the approximated proportional expression (see step S31 above). That is, in the equation shown in step S3, m, , b, and c are constants, and these values are determined by combustion experiments.

(Effects of the Invention) As is clear from the above description, according to the present invention, uniformity of flame propagation can be ensured regardless of the operating state in an engine with multiple peripheral ignition points. It becomes possible to ensure the reduction of NOx and HC, which is an advantage of the ignition method.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention, Figure 2 is a cross-sectional view of the engine body. FIG. 3 is a diagram showing the experimental results that form the basis of the present invention; FIG. 4 is a flowchart showing an example of control. O 11, 12 13-15 Cylinder block cylinder head combustion chamber Spark plug (standard ignition gap) other spark plugs ignition coil control unit

Claims (1)

[Claims] (1) When a plurality of ignition gaps are arranged at intervals around the circumference of the cylinder, and one ignition gap among the plurality of ignition gaps is set as a reference ignition gap, the ignition timing of the reference ignition gap is determined. and the ignition timing of other ignition gaps, respectively.
An ignition system for an engine, comprising: a phase setting means for setting a phase difference; and a phase adjustment means for adjusting the phase difference in proportion to the ignition advance amount of the reference ignition gap.