JPH03286186A - Ignition device for engine - Google Patents

Abstract

PURPOSE:To surely prevent any condition where ignition cannot be carried out immediately after ignition switching by providing a delay means for delaying the ignition switching by means of a switch means if a judgment means determines that ignition cannot be carried out at a required ignition timing after the switching. CONSTITUTION:After reading-in of a engine rotational speed N and a suction air quantity Q, an ignition timing IgC for a center plug 7 and an ignition timing IgS for periphery plugs 8-10 are determined on the basis of a map (which is stored in a ROM of a control unit U) set by using the engine rotational speed and the suction air quantity as parameters. If it is determined that the ignition timing (required ignition timing) IgC or IgS to be ignited this time is positioned on an advance side beyond the present crank angle, ignition cannot be carried out at the timing IgC or IgS any longer. Accordingly, the present ignition timing IgC, IgS are set as the preceding ignition timing, and the ignition is carried out at the preceding ignition timing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ignition device for an engine in which ignition gaps are arranged approximately at the center and around the periphery of a combustion chamber.

(Prior Art) In an Otto-type engine, the ignition gap of the ignition plug is generally located approximately at the center of the cylinder, that is, the combustion chamber, so as to be called a center ignition gap or a center ignition plug.

In response to this, it has been proposed to provide a plurality of ignition gaps (hereinafter referred to as peripheral ignition gaps or peripheral spark plugs) at intervals in the circumferential direction of the cylinder and positioned at the outer peripheral edge of the cylinder. Japanese Patent Publication No. 55-666
(See Japanese Patent Application Laid-Open No. 148021/1983).

By providing such a peripheral ignition gap, HC and NOx in the exhaust gas can be reduced. That is, H
C tends to occur around the combustion chamber, but
Since combustion starts from the periphery, HC is completely burned. In addition, multiple flames are generated when combustion starts from multiple locations around the combustion chamber, but the flame fronts at the tips of these flames collide with each other from an early stage, causing the flame front to grow large in a short period of time. In other words, combustion is slowed down, and NOx is reduced.

(Problems to be Solved by the Invention) In order to perform ideal ignition over a wide operating range of the engine while taking advantage of the advantages of providing the peripheral ignition gap as described above, the center ignition gap and the peripheral ignition gap are It is conceivable to provide both an ignition gap and to switch the ignition gap in which ignition is executed depending on the operating state of the engine.

For example, there are two types of ignition: ignition using only the center ignition gap (hereinafter such an ignition method will be referred to as the center ignition method), ignition using only the peripheral ignition gap (hereinafter referred to as such ignition method and peripheral ignition method), and ignition using only the center ignition gap. It is conceivable that the switching may be performed in three ways: ignition by both the peripheral ignition gap and ignition (hereinafter, such an ignition system will be referred to as the center-ten-periphery ignition system).

When switching the ignition system as described above, each ignition system naturally has different required ignition timing. This means that when switching from one ignition system to another, the required ignition timing after the switch will be more advanced than the current crank angle, and ignition will not be possible with the required ignition timing after the switch. It is conceivable that a situation may occur.

The present invention was made in consideration of the above circumstances, and
To provide an ignition device for a tired engine that can surely prevent a situation where ignition becomes unnecessary immediately after switching when switching ignition execution between a center ignition gap and a peripheral ignition gap.

(Structure of the Invention) In order to achieve the above object, the present invention has the following structure. That is, a central ignition gap disposed approximately in the center of the combustion chamber, a plurality of peripheral ignition gaps disposed around the combustion chamber at intervals in the circumferential direction of the cylinder, and the a switching means for switching execution of ignition between a center ignition gap and a peripheral ignition gap; a determining means for determining whether or not ignition is possible at the required ignition timing after switching by the switching means; When it is determined that ignition is not possible due to the ignition timing,
and a delay means for delaying ignition switching by the switching means.

(Operations and Effects of the Invention) In this way, in the present invention, when it is determined that ignition is not possible at the required ignition timing after switching, the switching is delayed, that is, after waiting until ignition is possible at the above-mentioned required ignition timing, the switching is performed. will be carried out. By performing such a delay,
A situation in which no fuel is combusted immediately after switching the ignition system can be reliably avoided.

(Example) Examples of the present invention will be described below based on the attached drawings.

In FIG. 1, l is a cylinder head, and a combustion chamber 2 formed on the inner wall of the cylinder head is of a vent roof type. As shown in FIG.
B, and two exhaust ports 4A and 4B, a first and a second, are formed.

Then, the first intake port 3A is connected to the first intake valve 5A, the second intake port 3B is connected to the second intake valve 5B, and the first exhaust port 4A is connected to the first exhaust valve 6A, and the second exhaust port 1
-4B is opened and closed at a predetermined timing by the second exhaust valve 6B in synchronization with the rotation of a crankshaft (not shown). Then, fuel is supplied from the fuel injection valve 16 to both intake boats 3A,
It is injected with a predetermined spread toward 3B.

The cylinder head 1 has a total of four spark plugs 7.8.
9.10 are installed, and each spark plug can be installed and removed from above the cylinder head 1. Among the four spark plugs 7 to 10, the plug 7 is the center plug, and its ignition gap 7a is located at the center of the combustion chamber 2. The center plug 7 is slightly inclined with respect to the cylinder axis so as to be inclined toward the exhaust boats 3A and 3B as it goes upward.

The three spark plugs 8 to 10 constitute first to third peripheral spark plugs. That is, the plugs 8 to 10 are arranged at approximately equal intervals in the circumferential direction of the cylinder, and the ignition gaps 88 to 10a are located at the peripheral edge of the cylinder.

The details of the arrangement of the peripheral plugs 8 to 10 (ignition gaps 8a to 10a) are as follows.

First of all, the ignition gap 8a of the first peripheral spark plug 8 is located between the two intake valves 5A and 5B, so that the first peripheral spark plug 8 is located between the partition wall 1a delimiting the two intake boats 3A and 3B. It is arranged so that it penetrates. and,
As the first spark plug 8 moves upward, the exhaust valve 6
It is tilted toward the A and 6B sides.

The ignition gap 9a of the second spark plug 9 corresponds to the first intake valve 5.
A and the first exhaust valve 6A located on the − side in the circumferential direction of the cylinder (clockwise side in FIG. 2) with respect to the first intake valve 5A, the side closer to the first exhaust valve 6A. It is located in The second peripheral plug 9 extends in the axial direction of the cylinder.

The ignition gap 10a of the third peripheral spark plug 1o is
An intake valve 5B, and a second exhaust valve 6 located on the opposite side in the cylinder circumferential direction (counterclockwise side in FIG. 2) with respect to the second intake valve 5B.
B and is disposed on the side closer to the second exhaust valve 6B. The third peripheral plug 1o is inclined toward the intake valves 5A and 5B as it goes upward.

It is preferable that the intervals in the cylinder circumferential direction between the peripheral plugs 8 to 10 are equal to each other, but in the embodiment, each interval is slightly different. More specifically, the circumferential distance between the first and second peripheral plugs 8 and 9 is a, the circumferential distance between the second and third peripheral plugs 9 and 10 is b, and the third and third peripheral plugs are If the distance between peripheral plugs 1 and 8 is C, then a<c<
b. In this way, in portion b, where the distance becomes wider, the spread of the flame surface in the circumferential direction is delayed. Therefore, in the embodiment, the procedure is as follows. First, the second and third peripheral plugs 9,10 (ignition gaps 9a, 10a) are positioned in a recess 15 formed in the cylinder head 1, where the recess 15 and the peripheral plug 9 or 10 are connected to each other. The spacing is wide as indicated by the symbol X in the spacing direction, and narrows as indicated by the symbol Y in the direction opposite to the spacing.

Note that 1)A to 1)D in FIG. 1 are cooling water passages.

The central spark plug 7 and peripheral spark plugs 8 to 10 are as follows:
The operation (ignition) is switched depending on the operating state of the engine, and an example of the range setting for this switching is shown in FIG. In this Figure 4, areas ■ and ■ are peripheral plugs 8.
The peripheral ignition method is where ignition is performed only by the spark plugs 7 to 10, the area (2) is the center ignition method where ignition is performed only by the center plug 7, and the area m is the center ignition method where ignition is performed only by the center plug 7.
The ignition control for each spark plug 7 to 10 is as shown in FIG.
This is performed by a control unit U configured using a microcomputer. This control unit U individually controls the ignition timing and ignition execution of each of the spark plugs 7 to 10. Therefore, for each spark plug 7 to 1o,
An igniter 21, 22, 23 or 24 and an ignition coil 25, 26, 27 or 28 are provided. Then, the control unit U outputs a predetermined ignition timing signal (including a signal not to ignite) to each igniter 21 to 24, and the igniter 21 to 24 outputs an ignition timing signal to indicate whether or not ignition has actually occurred. A confirmation signal is sent back to the control unit U. Further, signals from various sensors or switches (these are collectively shown as a sensor group by reference numeral 30) are input to the control unit U. This sensor group 3
Signals from 0 include engine speed, intake air amount,
Includes crank angle, etc.

The contents of the ignition control by the control unit U include not only the switching of the ignition method and the delay in switching the ignition method, but also the control for when some spark plugs fail (for when there is a failure).
, for dry firing to prevent contamination of plugs that do not normally require ignition, and for temporary ignition method changes immediately after switching the ignition method and during acceleration (center 10-periphery ignition method). . The control contents of this control unit U will be explained below with reference to the flowcharts shown in FIGS. 5A to 5C. In the following explanation, P indicates a step. In addition, in the following explanation, we will first explain the overall overview,
Thereafter, the delay control for switching the ignition method mentioned above will be individually explained.

Kosuke Shino 1 First, when initializing Pl, a count value Nn, which will be described later, is set to a value other than O, and the center F (fail) flag, which indicates whether or not the center plug 7 is unable to ignite, is set to O (of O). when it is set to normal), and peripheral plugs 8 to 1 are set.
A peripheral F (fail) flag indicating whether or not ignition is impossible is set to O (normal when O).

After the engine speed N and intake air amount Q are read in P2, the ignition timing T for the center plug 7 is read in P3.
gC and the ignition timing 1gS for the peripheral plugs 8 to 10 are set based on a map (stored in the ROM of the control unit U) that is set using the engine speed and intake air amount as parameters, respectively. .

After P4, the above I
After gC and IgS undergo correction and change processing, P in Figure 5C
In 46, the IgC5IgS is connected to igniters 21 to 2.
4 and ignition is executed (IgClIgS is O
(This is the ignition non-execution signal in which ignition is not performed).

After P46, it is determined through the processes P47 to P50 whether or not the center spark plug 7 is in a failure state where it is unable to ignite. That is, based on the ignition confirmation signal from the igniter 21 regarding the center spark plug 7, the center F flag is set to 1 in P49 when the center spark plug 7 is in failure, and the center F flag is set to 1 in P49 when the center spark plug 7 is not in failure.
is set to .

Similarly, by the processing of P51 to P54, the peripheral F flags indicating whether or not the peripheral spark plugs 8 to 10 have failed are set or reset. However, in this case, it is determined whether or not each of the peripheral plugs 8 to 10 is malfunctioning.

Finally, at P55, the current ignition timing ('P
The ignition timing (ignited at step 46) is updated as the previous ignition timing, and the process returns to P2.

This corresponds to the processing of ignition off delays P4 to P7. That is, by determining P5 and P6, the ignition timing to be ignited this time (required ignition timing) Ig
If it is determined that C or IgS is on the advanced side of the current crank angle read in P4, it means that ignition is no longer possible at this IgC or IgS timing, and the current ignition timing is changed in P7. IgC1)gS are each set as the previous ignition timing, and ignition is executed at the previous ignition timing in P46.

This corresponds to the process of L Shaka Tenza 1) P8 to P]2. First, I mentioned in P3
gC1) As a map value for gS memory.

When ignition is not performed, O is stored in both IgC and IgS. Therefore, by looking at the combinations of IgC and IgS, whether they are FLo or not (P8, P9), it is possible to determine which ignition method is used.

This determination result is sent to PIO-Pl2 as the setting of the ignition method flag.When the ignition method flag is 1, it is the peripheral ignition method, when it is 2, it is the center ignition method, and when it is 3, it is the center ignition method. It is a method.

Spark Plug Failure ■Failure of Center Spark Plug 7 This is when it is determined in P21 that the center F flag is not 0, and the processing is performed in P22 to P25. At this time, the ignition timings of the peripheral spark plugs 8 to 10 are changed depending on the difference in the current ignition system (the ignition system is confirmed through P22 and P23).

That is, in the case of the central ignition system, the ignition timing IgS of the peripheral spark plugs 8 to 1o is set at the predetermined angle C1 at P25.
The angle is advanced by In addition, when using the center ten-periphery ignition method,
At P24, the ignition timing I of peripheral spark plugs 8 to 10
gS is advanced by C2. Of course, the ignition timing signal IgC for the center spark plug 7 is set to O because ignition is not performed since ignition is impossible.

In addition, when using the current peripheral ignition method, peripheral spark plugs 8 to
10, just ignite at the regular ignition timing,
The process moves to P26 without being corrected.

(2) Failure of peripheral spark plugs 8 to 10 This is when it is determined in P26 that the peripheral F flag is not O, and in this case, the processes of P27 to P30 are performed. That is, when the current peripheral ignition system is used, the ignition timing IgC of the center spark plug is changed to a value advanced by C3 at P2O, and when the center 10 peripheral ignition system is used, the ignition timing of the center spark plug 7 is changed at P29. IgC is changed to a value advanced by 04. Of course, the ignition timing IgS of the malfunctioning peripheral spark plugs 8 to 10 is set to O, which means that ignition is not performed since ignition is impossible.

Note that in the case of the current central ignition system, the central ignition plug 7 can be ignited at the regular ignition timing as it is, so the process moves to P31 without being corrected.

Setting of the count value Nn P31 to P38 are performed to set the count value Nn, but this Nn is performed to see that it is the time immediately after switching the ignition method and that it is the initial stage of acceleration, and later the Ig
It is used for setting the retard amount of C and IgS.

First, in P31, as a preparation for determining whether or not it is time to switch, the value of the current ignition method flag (PLO-P
A difference value Se l ch is calculated by subtracting the value of the previous ignition method flag from the value of the previous ignition method flag (see step 12), and the value of the current ignition method flag is updated as the value of the previous ignition method flag in P32. After this, in P33, the difference value Se
It is determined whether 1ch is O or not. Difference value Se
When lch is O, this means that there is no change in the ignition system, and in this case, the count value Nn is set to O in P34. Further, when it is determined in P33 that the difference value Se 1 ch is not O, it is determined in P35 whether or not Nn is less than or equal to a predetermined upper limit value. This P35
If the determination is YES, Nn is counted up in P36, and then the process moves to P41. Further, when the determination in P35 is NO, it is determined in P37 whether or not it is the initial stage of acceleration. If the determination in P37 is YES, Nn is set to O in P38, and the process returns to P35; if the determination in P37 is No, the process moves to P41.

In this way, the count value Nn is reset to 0 only when it is confirmed that it is not the time to switch the ignition system, or when it is confirmed that it is at the beginning of acceleration.

In the ignition timing correction P41 based on the count value Nn, after the correction values C7 and C8 are set according to the size of the count (fi N n), the correction values c7 and C8 are set according to the current φ fire method. Ignition timing Ig using
C or IgS is corrected (Pd2, Pd2). In other words, in the case of the current center ignition system, the ignition timing IgC of the center spark plug will not be changed as it is in Pd2, but only the ignition timing of the peripheral spark plugs 8 to 1o will be changed by a correction value of 07 minutes from IgS. will be retarded.

When the peripheral ignition system is used, only the ignition timing IgC for the center spark plug 7 is retarded by the correction value C8 at Pd2.

The correction values c7 and C8 in P41 above have two meanings; the first is that spark plugs that do not require ignition due to the current ignition system are ignited at a timing unrelated to combustion. It performs self-purification. The second is that regardless of the ignition system, all spark plugs 7 to 10 are ignited immediately after the ignition system is switched or at the beginning of acceleration, and at that time, the ignition plugs that are originally unnecessary due to the ignition system are set to ignite. This is done to set the ignition timing.

Specifically, when Nn is larger than the upper limit value, it is not immediately after switching the ignition method and is not yet at the beginning of acceleration, and in this case, the correction values C7 and C8 are not used at timings unrelated to combustion. It is set as a sufficient amount of retard to allow the spark plug to be fired (for example, to ignite near bottom dead center) (however, this is different from C7 and C8).
.

Also, when the value of Nn is below the upper limit, all spark plugs 7
The retard amount is set in such a state that ignition is obtained using 10 to 10 ignitions. In this way, by performing ignition using the ignition from all the spark plugs 7 to 10 immediately after switching the ignition method, a situation where ignition becomes impossible immediately after switching is prevented, and a situation where ignition becomes impossible can be prevented. You can check if the spark plug is .

In addition, by igniting all spark plugs 7 to 10 at the beginning of acceleration, it is possible to prevent the spark plugs from getting wet or smoldering due to the increased amount of fuel during acceleration, and to ensure strong ignition and rapid combustion, resulting in good results. Acceleration can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing one embodiment of the present invention. FIG. 2 is a simplified plan view showing the positional relationship between intake/exhaust valves and spark plugs. FIG. 3 is a circuit diagram showing the control system of the spark plug. FIG. 4 is a diagram showing an example of area setting of the ignition method. 5A to 5C are flowcharts showing control examples of the present invention. U: Control unit 2: Combustion chamber 7: Center spark plug 8: First peripheral spark plug 9: Second peripheral spark plug lO: Third peripheral spark plug 7a-10a: Ignition gap 21-24: Igniter 25-28: Ignition Coil Figure 3 Figure 4 Engine B Transfer N Figure 5A

Claims (1)

[Claims] (1) A central ignition gap disposed approximately at the center of the combustion chamber; a plurality of peripheral ignition gaps disposed around the combustion chamber at intervals in the circumferential direction of the cylinder; a switching means for switching execution of ignition between a center ignition gap and a peripheral ignition gap; a determining means for determining whether or not ignition is possible at the required ignition timing after switching by the switching means; When it is determined that ignition is not possible due to the ignition timing,
An ignition device for an engine, comprising: delay means for delaying ignition switching by the switching means.