JPH06323230A - Ignition timing controller for multipoint ignition engine - Google Patents

Abstract

PURPOSE:To reduce the burden on a control system for determining ignition timing by starting calculation for determining the ignition timing only for a specific control unit of a plurality of control units and, then by calculating the ignition timing for other control units. CONSTITUTION:When the starting time for calculating ignition timing based on a reference crank angle signal is reached, the engine speed and a load detected by sensors S1, S2 are referred to a preliminarily stored map to read a reference ignition timing, and a final reference ignition timing IG1 for a peripheral ignition gap 11 is corrected according to correction signals such as the water temperature, and is thus determined by a control unit U1. The reference ignition timing IG1 after the correction is output to control units U2, U3, and the ignition timing is calculated by referring to the ignition timing IG1 and the engine speed and the load from the sensors S1, S2, to a specific expression. The expression is set as a primary function, and the burden on a memory means is limited to as little as possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control device for a multipoint ignition engine.

[0002]

2. Description of the Related Art Among engines, particularly for automobiles, as shown in Japanese Unexamined Patent Publication No. 3-117684,
It has been proposed to provide a plurality of ignition gaps for one cylinder so that the ignition timings of the plurality of ignition gaps differ depending on the operating state of the engine.

[0003]

As described above, when a plurality of ignition timings are set for one cylinder, a heavy load is imposed on the control system, particularly the CPU. That is, generally, the ignition timing is determined by interrupt processing when the trigger signal such as the reference crank angle signal is received, but the ignition signal is interrupted by receiving the trigger signal for each ignition timing. However, the number of interrupts increases and the system maintenance time becomes long, and the effective time for control becomes insufficient. Especially, at the time of high rotation where the number of calculations per unit time increases, such a problem is remarkable. become.

When the ignition timing is determined, the ignition timing is calculated independently for each of the plurality of ignition timings. Therefore, the data (map value) for determining the ignition timing is stored. The amount will be extremely large. In the above publication, the reference ignition timing is determined for one specific ignition gap, and the ignition timing phase difference corresponding to the operating state of the engine is stored for the ignition timings of the other ignition gaps. It has been proposed to correct the stored phase difference according to the advance amount of the time. However, even in this case, although the load on the control system is lightened compared to determining a plurality of ignition timings completely independently, a considerable storage capacity is required for storing the phase difference, and The calculation for compensating for the phase difference becomes a considerable burden.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ignition timing control device for a multipoint ignition engine which can reduce the load on the control system for determining a plurality of ignition timings.

[0006]

In order to achieve the above object, the present invention has the following as a first structure thereof. That is, in an engine in which a plurality of ignition gaps are provided in one cylinder and different ignition timings are set for the plurality of ignition gaps according to the operating state of the engine, for a specific ignition gap among the plurality of ignition gaps, First ignition timing determining means for determining a reference ignition timing, ignition timings of ignition gaps other than the specific ignition gap among the plurality of ignition gaps, the reference ignition timing, the engine speed and the engine load. And a second ignition timing determining means which is calculated from a predetermined calculation formula.

Preferred embodiments of the present invention based on the above configuration are as set forth in claims 2 to 7.

In order to achieve the above object, the present invention has the following second construction. That is, in an engine in which a plurality of ignition gaps are provided in one cylinder and different ignition timings are set for the plurality of ignition gaps according to the operating state of the engine, the ignition gaps are set to be different from each other. A plurality of control units that independently determine the ignition timings of the corresponding ignition gaps are provided, and a trigger that starts the calculation for determining the ignition timings of only one specific control unit of the plurality of control units. The control unit other than the specific control unit is set to receive the signal, and subsequently calculates the ignition timing of the ignition gap corresponding to the other control unit after the calculation by the specific control unit is started. It is configured as follows.

[0009]

According to the present invention, the second ignition timing determining means determines the ignition timing only based on a predetermined calculation formula. In addition to reducing the negative, the amount of memory is reduced compared to the case where data for determining a plurality of ignition timings are individually stored, and the load on the control system is greatly reduced as a whole. be able to.

By adopting the structure as described in claim 2, it becomes preferable in order to reduce the load on the control system by using the predetermined calculation formula as the simplest calculation formula of linear function.

The structure as described in claim 3 is preferable for appropriately setting the ignition timing of the always operating ignition gap involved in the constant ignition.

With the structure as described in claim 4, in the combustion chamber structure having the central ignition gap and the peripheral ignition gap, the same effect as that obtained in claim 3 can be obtained.

With the structure as described in claim 5, in a combustion chamber structure in which a plurality of ignition gaps are arranged in series in the combustion chamber diameter direction, the same effect as that obtained in claim 3 is obtained. be able to. In this case, with the structure as described in claim 6, the effect of claim 5 can be obtained in a recent engine for automobiles having a pentor-fu type combustion chamber shape.

With the structure as described in claim 7, since the trigger signal for starting the calculation of the ignition timing needs to be used only once for the calculation of the plurality of ignition timings, a plurality of trigger signals can be used. The load on the control system will be reduced compared to the case of reuse.

With the configuration as described in claim 8, when the plurality of ignition timings are independently determined by the plurality of control units, the number of times the trigger signal is used for starting the calculation of the ignition timing is determined. It is possible to reduce the load on the control system. In this case, by adopting the configuration as described in claim 9, the load on other control units can be significantly reduced.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 designates a pentorf-type combustion chamber, one inclined surface of which is a reference numeral 1A, the other inclined surface is a reference numeral 1B, and a ridge line where both inclined surfaces 1A and 1B intersect is a reference character α. Indicated by. In the combustion chamber 1, two intake ports 2 and 3 are opened on the inclined surface 1A, and two exhaust ports 4 and 5 are opened on the other inclined surface 1B. The intake ports 2 and 3 are separated from each other along the ridge line α, and similarly, the exhaust ports 4 and 5 are separated from each other along the ridge line α. A control valve valve 6 that is closed in a predetermined operating region of the engine is provided in one of the intake ports 3.

The combustion chamber 1 is provided with a total of four ignition gaps (ignition plugs) 11-14. The ignition gaps 11 to 13 serve as peripheral ignition gaps arranged at the peripheral edge of the combustion chamber 1, and are arranged at intervals of approximately 120 degrees in the circumferential direction of the combustion chamber. Of the three peripheral ignition gaps 11 to 13, the ignition gap 11 is arranged between the two intake ports 2 and 3. The peripheral ignition gap 12 is disposed between the intake port 2 and the exhaust port 4 at a position close to the exhaust port 4.
The peripheral ignition gap 13 is formed by the intake port 3 and the exhaust port 5
, And is located at a position close to the exhaust port 5. Further, the ignition gap 14 serves as a central ignition gap, and is arranged substantially at the center of the combustion chamber 1.

Of the four ignition gaps, the central ignition gap 14 is a resting ignition gap that is stopped in a predetermined operating region of the engine, and the remaining three peripheral ignition gaps are executed in all operating regions of the engine. The ignition gap is always on. In FIG. 2, the operating region of the engine is divided into three regions X1 to X3 with the engine speed and the engine load as parameters. That is, the region X1 is the idle region, the region X2 is the low rotation and low load region excluding the idle region, and the region X3 is the high rotation or high load region. Center ignition gap 1
4 is paused only in the area X2 and the other areas X1 and X3
Is activated with. That is, the regions X1 and X3 are set to the four-point ignition state in which all the ignition gaps 11 to 14 are operated, and the region X2 is set to the three-point ignition state in which only the peripheral ignition gaps 11 to 13 are operated.

The control valve 6 is closed in the regions X1 and X2 and opened in the region X3. When the control valve 6 is closed, the intake air is supplied only from one intake port 2, and at this time, a swirl of the intake air clockwise in FIG. 1 is generated in the combustion chamber 1.

When only the peripheral ignition gaps 11-13 are activated, the flame produced in each ignition gap 11-13 is
First, an annular flame is formed so as to match in the circumferential direction of the combustion chamber, and then the annular flame is directed to the center of the combustion chamber. This suppresses the rapid increase in flame area,
The combustion mode ideally becomes as shown by the solid line in FIG. Incidentally, the conventional combustion mode when ignition is executed only in the central ignition gap 14 is as shown by the broken line in FIG. In other words, by executing the ignition only by the peripheral ignition gaps 11 to 13, the heat generation amount (heat generation amount per unit time-the same below) is made as uniform as possible over the entire combustion period without reducing the combustion period, and NOx is reduced. On the other hand, due to the formation of the annular flame in the circumferential portion of the combustion chamber at the initial stage of combustion, HC easily generated in the peripheral portion of the combustion chamber is reduced.

The ignition timings of the peripheral ignition gaps 11 to 13 are set to be different from each other in order to effectively form the annular flame at the initial stage of combustion. That is,
Considering the swirl generation direction, the uneven distribution of fuel, and the flame propagation speed such as the temperature distribution of the combustion chamber wall surface, the ignition gaps are set as the ignition gaps 13, 12, 11 in order from the earliest to the latest. . Further, in the four-point ignition state in which all the ignition gaps 11 to 14 are operated, the ignition timing of the central ignition gap 14 is set as the same timing as the peripheral ignition gap 13 in the embodiment.

FIG. 4 shows a control system for determining the ignition timing. The control unit U1 is for determining the ignition timing of the peripheral ignition gap 11. Control unit U2
Is for determining the ignition timing of the peripheral ignition gap 12. The control unit U3 has a peripheral ignition gap 1
3 for determining the ignition timing of the center ignition gap 14 and the center ignition gap 14. The ignition timing determined by each of the control units U1 to U3 is output to an igniter (not shown), and ignition is executed at the determined ignition timing. When there are a plurality of cylinders, ignition is performed in the corresponding ignition gap in each cylinder from the igniter through the distributor.

The control unit U1 serves as a specific control unit for determining the reference ignition timing, and a reference crank angle signal serving as a trigger signal for starting the ignition timing calculation is input and the engine from the sensor S1 is also inputted. Number of revolutions,
An engine load signal (intake air amount in the embodiment) from the sensor S2 and a correction signal such as a water temperature for ignition timing correction are input.

The control unit U1 is provided with a map (storage means) which stores a reference ignition timing signal set by using the engine speed and the engine load as parameters, and the ignition timing of the ignition timing is determined based on the reference crank angle signal. When the calculation start timing comes, the reference ignition timing is read by comparing the engine speed detected by the sensors S1 and S2 and the engine load with the stored map. Then, the reference ignition timing read according to the correction signal such as the water temperature is corrected, and the corrected ignition timing is set as the final reference ignition timing IG1 for the peripheral ignition gap 11. In this way, the control unit U1 determines the ignition timing in the same manner as the conventional engine in which one ignition gap is provided for one cylinder.

The control unit U1 outputs the corrected reference ignition timing IG1 to the control units U2 and U3 and receives the reference ignition timing signal.
Starts the calculation of the ignition timing of the ignition gap 12 or 13 (14). The calculation of the ignition timing by the control units U2 and U3 is performed by using the reference ignition timing IG1 and the sensor S
2, the engine speed and the engine load from S2 are collated with a predetermined calculation formula.

The calculation formula of the ignition timing IG2 by the control unit U2 is set as the following formula (1), and the control unit U2
The calculation formula of the ignition timing IG3 by 3 is set as the following formula (2). In the following formula, C1 to C4 are constants, N
e is the engine speed and Ce is the engine load. IG2 = IG1 + C1 (Ne) + C2 (Ce) ... (1) IG3 = IG1 + C3 (Ne) + C4 (Ce) ... (2)

As described above, in the embodiment, both equations (1) and (2) are set as linear functions so that the arithmetic means and the storage means for storing the equations are not overloaded. However, the setting of the equation can be variously adopted, such as setting as a quadratic function.

The processes performed by the control units U1 to U3 are
It can also be performed by one CPU, and a control example in that case is shown in the flowchart of FIG. The processing of FIG. 5 is started at the time when the ignition timing calculation start timing is received in response to the reference crank angle signal (since the CPU for engine control generally also serves to set the air-fuel ratio, etc., The process of FIG. 5 is an interrupt process when the reference crank angle signal is received).

First, at P1, after the data of the sensors S1, S2, etc. are input, at P2, the reference ignition timing IG1 is determined by the same method as described for the control unit U1. Next, at P3, the ignition timing IG2 is determined based on the equation (1), and at P4, the ignition timing IG3 (= IG
4) is decided.

The determination of the ignition timing is ended by the processing up to P4, but in FIG. 5, for ease of understanding and the like, the selection of the ignition gap corresponding to the region shown in FIG. 2 is shown. is there. That is, all the ignition gaps 11 at P5
It is judged whether or not there is a four-point ignition state in which the ignition of 14 to 14 should be executed. When the determination in P5 is YES, in P6, ignition is performed by all the ignition gaps 11-14. If NO in P5, in P7, ignition is performed by the three ignition gaps of the peripheral ignition gaps 11 to 13.

FIG. 6 shows another embodiment of the present invention. The same components as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, a total of three ignition gaps 21 to 23 are arranged along the ridge line α, that is, at intervals in the diameter direction of the combustion chamber. Of these, the ignition gap 21 is disposed substantially at the center of the combustion chamber 1, and the ignition gaps 22 and 23 are disposed at or near the peripheral edge of the combustion chamber.

In region X2 of FIG. 2, all ignition gaps 21 to 2 are activated, and in regions X1 and X3 only the central ignition gap 21 is activated. The area X1
The operation mode of the control valve 6 in X3 is the same as that of the above-mentioned embodiment.

When all the ignition gaps 21 to 23 are operated, the flames generated in the ignition gaps 21 to 23 at the beginning of combustion are elongated and elongated over the entire length of the combustion chamber in the diameter direction (ridge line α direction). A columnar flame is formed, and then the flame spreads in the horizontal direction in FIG. This allows
The combustion mode is in the state shown by the solid line in FIG. 3, almost the same as in the case of the above embodiment.

In order to effectively generate the columnar flame at the initial stage of the combustion chamber, the swirl and the like are taken into consideration, and after the central ignition gap 21 is first ignited, the ignition gaps 22 and 23 at both ends are the same after a slight delay. Ignition is performed at the timing (the flame spread from the central ignition gap 21 is caused by the ignition gaps 22 and 23 at both ends).
Slower than the flame spread from. Thus, in the case of FIG. 6, the ignition timing is set as two different timings for the ignition gap 21 and for the ignition gaps 22 and 23. In this embodiment as well, different ignition timings may be determined in the same manner as in the above-described embodiment, and in this case, the ignition timing of the central ignition gap 21 that is constantly operated is set to the reference ignition timing IG1.

In FIG. 6, the control valve 6 is eliminated, and the region X2 in which all three ignition gaps 21 to 23 are operated.
At this time, intake air tumbles that are substantially parallel to each other may be formed in the combustion chamber 1. In this case, due to the tumble flow, the flame spread from the ignition gaps 22 and 23 at both ends is slow and the flame spread from the central ignition gap 21 is accelerated, so that the ignition timing of the ignition gaps 22 and 23 at both ends is The ignition timing is set to be earlier than the ignition timing of the ignition gap 21.

Although the embodiment has been described above, the present invention is not limited to this, and includes the following cases, for example. (1) The ignition timing of the center ignition gap 14 may be set to the same timing as the ignition timing of the peripheral ignition gap 13 or 12, or may be set as the ignition timing specific to the center ignition gap 14. (2) Not only when the ignition timing is made different to obtain the combustion mode as shown by the solid line in FIG. 3, but also when the ignition timings of a plurality of ignition gaps are made different, such as those in which the central ignition gap does not exist. It is also applicable to known appropriate ones. (3) When the ignition gap is paused, the ignition may be executed at a timing that is not involved in the ignition (so-called blank firing) to prevent the pause ignition gap from being contaminated. Of course,
The present invention may be one in which all ignition gaps are activated at all times without having the ignition gaps paused.

[Brief description of drawings]

FIG. 1 is a simplified plan view of a combustion chamber portion showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of division of engine operating regions when a part of cylinders of a plurality of ignition gaps is deactivated.

FIG. 3 is a diagram showing a combustion mode obtained in an example in comparison with a conventional combustion mode.

FIG. 4 is a control system diagram for determining ignition timing.

FIG. 5 is a flowchart showing an example of control for determining ignition timing.

FIG. 6 shows another embodiment of the present invention, and is a view corresponding to FIG. 1.

[Explanation of symbols]

 1: Combustion chambers 11-13: Ignition gap (peripheral) 14: Ignition gap (center) 21: Ignition gap (center) 22, 23: Ignition gap (both ends) U1: Control unit (specific) U2: Control unit U3: Control Unit IG1: Reference ignition timing α: Ridge line

Claims (9)

[Claims] 1. An engine in which a plurality of ignition gaps are provided in one cylinder, and different ignition timings are set for the plurality of ignition gaps according to the operating state of the engine. First ignition timing determining means for determining a reference ignition timing for the ignition gap; ignition timings for ignition gaps other than the specific ignition gap among the plurality of ignition gaps, the reference ignition timing, the engine speed, and the engine. An ignition timing control device for a multipoint ignition engine, comprising: a second ignition timing determining means for calculating a load by collating with a predetermined calculation formula. 2. The method according to claim 1, wherein the predetermined calculation formula is set as a linear function. 3. The ignition gap according to claim 1, wherein a part of the plurality of ignition gaps is
A quiescent ignition gap that is deactivated in accordance with the operating state of the engine, and the specific ignition gap is an ignition gap other than the quiescent ignition gap. 4. The combustion engine according to claim 3, wherein the plurality of ignition gaps are provided at a peripheral portion of the combustion chamber and are provided at predetermined intervals in a circumferential direction of the combustion chamber, and a plurality of peripheral ignition gaps. A central ignition gap arranged substantially at the center of the chamber, and the rest ignition gap is the central ignition gap. 5. The ignition gap according to claim 3, wherein the plurality of ignition gaps are at least three and are arranged in series in a diametrical direction of the combustion chamber, and the rest ignition gaps are arranged in series. Ignition gaps located at both ends. 6. The structure according to claim 5, wherein the shape of the combustion chamber is a pentorf type, and the plurality of ignition gaps are located on the ridgeline of the pentorf type combustion chamber. 7. The first ignition timing determination means according to claim 1, wherein the first ignition timing determination means is set to start calculation of the reference ignition timing when a predetermined trigger signal is received, and the second ignition timing determination means The setting is made so that the calculation of the ignition timing is subsequently started after the reference ignition timing is determined by the first ignition timing determination means. 8. An engine in which a plurality of ignition gaps are provided in one cylinder, and different ignition timings are set for the plurality of ignition gaps according to the operating state of the engine, and the ignition gaps have different ignition timings. Is provided with a plurality of control units that determine the ignition timings of the corresponding ignition gaps independently of each other, and only one specific control unit of the plurality of control units performs an operation for determining the ignition timing. A control signal other than the specific control unit is set so that a trigger signal to be started is input, and the ignition timing of the ignition gap corresponding to the other control unit after the start of calculation by the specific control unit. An ignition timing control device for a multipoint ignition engine, wherein the ignition timing control device is set to calculate 9. The ignition timing determination by the other control unit according to claim 8, wherein the reference ignition timing calculated by the specific control unit, the engine load, and the engine speed are collated with a predetermined calculation formula. Is set to calculate.