JP2000161193A - Engine combustion control device and spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the stability of combustion by causing ignition at an appropriate ignition position along the axial direction of a piston during stratified combustion. SOLUTION: A spark plug having a plurality of ignition parts along the axial direction of a main body is mounted with the axial direction of the main body almost matching the axial direction of a piston. Ignition is caused at the normal ignition part selected according to operating conditions (S5) and an air-fuel ratio at the normal ignition part is detected (S6). When a learning condition is met, the ignition part is changed to a ignition part for leaning, where ignition is caused (S13) and the air-fuel ratio at the ignition part for learning is detected (S14). The air-fuel ratio AF1 detected at the normal ignition part and the air-fuel ratio AF2 detected at the ignition part for learning are compared to each other (S17), and when the air-fuel ratio AF1 at the normal ignition part is leaner than the air-fuel ratio AF2 at the ignition part for learning by a predetermined amount or more, the normal ignition part is corrected to the ignition part for learning (S18).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device and a spark plug for an engine, and more particularly, to a combustion control technology for selecting an optimum ignition portion from a plurality of ignition portions to perform an ignition operation, and The present invention relates to a spark plug suitable for the combustion control.

[0002]

2. Description of the Related Art Conventionally, as a combustion control device for an engine,
As disclosed in JP-A-10-169446,
There has been a configuration in which a plurality of spark plugs are arranged along a fuel spray direction, and ignition is performed by a spark plug selected according to operating conditions.

[0003] Japanese Patent Application Laid-Open No. 6-167240 discloses a combustion control device having a structure in which a gas composition in a cylinder is detected from spark light of an ignition plug and a fuel injection amount or the like is feedback-controlled.

[0004]

In the case where a plurality of spark plugs are arranged along the direction of fuel spray as described above, ignition is performed by a spark plug which is arranged in one side of the combustion chamber. At times, knocking was likely to occur.

[0005] When stratified charge combustion is performed, the air-fuel ratio in the vicinity of the spark plug can be adjusted to some extent by controlling the injection timing. However, in particular, when stratification is attempted by tumble flow, the axial direction of the combustion chamber (piston Since the air-fuel ratio varies in the axial direction (axial direction), arranging the spark plugs in the circumferential direction of the combustion chamber makes it impossible to cause ignition at a locally rich mixture. For this reason, there is a possibility that the combustion stability is impaired, or that the air-fuel ratio in the vicinity of the spark plug is determined to be thinner than the required air-fuel ratio, and the fuel injection amount is increased and the fuel efficiency is deteriorated. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a combustion control device capable of causing ignition at an optimum position in response to air-fuel ratio variations in the axial direction of a piston. Therefore, it is an object of the present invention to improve combustion stability and fuel efficiency.

Another object of the present invention is to provide a spark plug suitable for controlling the optimum ignition position in the piston axial direction.

[0008]

Therefore, in the combustion control apparatus for an engine according to the present invention, a plurality of ignition portions of a spark plug are provided for each cylinder.
The plurality of firing portions are arranged so as to be shifted from each other substantially along the axial direction of the piston, and ignition is performed at a firing portion selected from the plurality of firing portions according to an engine operating condition.

According to such a configuration, a plurality of firing portions are arranged side by side substantially along the axial direction of the piston, and one of the plurality of firing portions is selected in accordance with engine operating conditions.
Cause ignition. That is, the ignition is performed at the proper ignition position in response to the fact that the portion having the highest air-fuel ratio in the axial direction of the piston (appropriate ignition position) changes according to the engine operating conditions (the strength of gas flow). For this purpose, an ignition portion for actually igniting is selected from a plurality of ignition portions provided substantially along the axial direction of the piston.

[0010] The ignition portion is a portion composed of a center electrode, a ground electrode, and a spark gap. In the invention according to claim 2, the ignition plug includes a plurality of firing portions for one main body, and the plurality of firing portions are arranged so as to be shifted from each other substantially along an axial direction of the main body. Each cylinder is provided so that the axial direction of the main body substantially coincides with the axial direction of the piston.

According to such a configuration, one ignition plug is provided with a plurality of firing portions, and the plurality of firing portions are,
Since the spark plugs are arranged substantially along the axial direction of the main body, if the spark plug is attached to the cylinder head so that the axial direction of the main body and the axial direction of the piston substantially coincide with each other, the plurality of ignition portions are aligned in the axial direction of the piston. Are arranged so as to be shifted from each other substantially along.

According to a third aspect of the present invention, there is provided the combustion control apparatus for an engine, wherein a plurality of firing portions are provided for one main body, and the plurality of firing portions are mutually connected substantially along the axial direction of the main body. Each cylinder is provided with a spark plug which is arranged so as to be staggered so as to cause ignition at a firing portion selected from the plurality of firing portions in accordance with an engine operating condition.

According to this configuration, a plurality of ignition portions are provided substantially along the axial direction of the main body of the ignition plug, and one of the ignition portions corresponding to the appropriate ignition position having the highest air-fuel ratio is determined by the engine. The ignition is selected according to the operating conditions.

According to the fourth aspect of the present invention, the air-fuel ratio at the ignition timing at the position of each ignition portion is detected, and the ignition portion for performing ignition is learned and corrected based on the detected air-fuel ratio.

According to this configuration, the local air-fuel ratio at the ignition timing is detected at each position of each ignition portion, and the air-fuel ratio obtained for each ignition portion is compared, so that the optimum position for ignition (local air-fuel ratio is determined). (The darkest position) is learned, and the selected firing part is corrected.

According to the fifth aspect of the present invention, the air-fuel ratio at the ignition timing at the position of the ignition portion where ignition has been performed is detected based on the combustion state, and when a predetermined learning condition is satisfied. Then, by switching to a learning firing portion different from the normal firing portion to cause ignition, the air-fuel ratio at the ignition timing at the position of the learning firing portion is detected, and at the position of the normal firing portion, Then, the air-fuel ratio at the position of the learning ignition section is compared with the air-fuel ratio of the learning section, and the ignition section for performing the ignition is learned and corrected.

According to this configuration, the ignition is actually performed for each ignition portion, and the air-fuel ratio is detected from the combustion state at that time. Therefore, the air-fuel ratio at the ignition timing at the position of each ignition portion is detected. It is necessary to switch the ignition unit to cause ignition. Therefore, when it is determined that the learning condition is satisfied in the state where the ignition is performed in the normal ignition unit, the ignition unit is switched to the ignition unit in which the air-fuel ratio detection is to be performed, which is different from the normal ignition unit. The air-fuel ratio is detected at the position of the ignition portion after the switching, and it is determined whether or not the air-fuel ratio in the learning ignition portion is higher than that of the normal ignition portion, and the appropriate ignition position is determined.

The detection of the air-fuel ratio based on the combustion state includes:
The detection of the air-fuel ratio based on the ion current generated between the gaps and the detection of the air-fuel ratio based on the combustion light are included. In the invention according to claim 6, when the ignition by the normal firing portion is performed a predetermined number of times or more, it is determined that the learning condition is satisfied, and the mode is switched to the firing portion for learning.

According to this configuration, every predetermined cycle,
The process shifts to the detection of the air-fuel ratio in the learning firing section. According to the invention described in claim 7, when the air-fuel ratio at the ignition timing at the position of the normal ignition portion becomes thinner than the reference air-fuel ratio, it is determined that the learning condition is satisfied, and the mode is switched to the ignition portion for learning. And

According to this configuration, when the air-fuel ratio at the ignition timing at the position of the normal ignition portion becomes thinner than the reference air-fuel ratio, the position with the highest air-fuel ratio is shifted in the axial direction of the piston. In order to obtain a new proper ignition position, the ignition switch for learning is switched to perform the detection of the air-fuel ratio.

In the spark plug according to the present invention, a plurality of firing portions are provided for one main body,
The plurality of firing portions are arranged so as to be shifted from each other substantially along the axial direction of the main body.

According to this configuration, since a plurality of ignition portions are provided in the axial direction of the ignition plug main body, when the ignition plug is attached to the cylinder head, it is possible to cope with a variation in the air-fuel ratio along the axial direction of the main body. It is possible to select a firing part.

[0023]

According to the first aspect of the present invention, since ignition can be performed at an appropriate ignition position along the axial direction of the piston, high combustion stability can be ensured and the lean combustion limit can be increased. There is an effect that can be.

According to the second aspect of the invention, there is an effect that the selection of the ignition portion along the axial direction of the piston can be performed by a simple hardware configuration, and high versatility can be realized.

According to the third aspect of the present invention, since ignition can be performed at an appropriate ignition position along the axial direction of the main body of the spark plug, high combustion stability can be ensured and the lean combustion limit is increased. There is an effect that can be.

According to the fourth aspect of the invention, there is an effect that the ignition can always be performed in the most suitable ignition section in response to the fluctuation and variation of the air-fuel ratio characteristics in each ignition section.

According to the fifth aspect of the present invention, while the air-fuel ratio of the ignition timing at the ignition portion is detected based on the combustion state, the ignition portion having a higher air-fuel ratio at the ignition timing is selected, and the ignition is performed. There is an effect that it can be performed.

According to the sixth aspect of the invention, during the normal ignition operation in the ignition section, the optimal ignition section can be learned periodically, and the ignition operation in the inappropriate ignition section becomes longer. There is an effect that it can be reliably prevented from continuing over a period.

According to the seventh aspect of the invention, when the selected firing portion becomes inappropriate, it is possible to surely change the selected firing portion to a more appropriate firing portion. According to the eighth aspect of the invention, there is an effect that an appropriate ignition portion can be selected according to the air-fuel ratio variation along the axial direction of the spark plug main body.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a system configuration of an engine according to the embodiment.

The engine 1 shown in FIG. 1 is provided with a fuel injection device 2 for directly injecting fuel into a cylinder, and a spark plug 3 for igniting and burning a mixture in a combustion chamber for each cylinder. An engine control unit (hereinafter abbreviated as ECU) 4 containing a microcomputer is provided with:
The fuel injection by the fuel injection device 2 and the ignition by the spark plug 3 are controlled based on detection signals from various sensors.

The various sensors include a water temperature sensor 5 for detecting the temperature of the cooling water of the engine 1 and an engine speed (rp).
m), an air flow meter 7 for detecting the amount of intake air of the engine 1, a throttle sensor 9 for detecting the opening of the throttle valve 8, and an air-fuel ratio of the combustion mixture based on the oxygen concentration in the exhaust gas. An air-fuel ratio sensor 10 is provided.

As will be described later, the ignition plug 3 is provided with three ignition portions.
Three ignition coils 11a,
11b and 11c, and each ignition coil 11a, 11c
Three distributors 12a, 12b and 12c are provided for distributing and supplying the high voltage generated at b and 11c to the corresponding ignition portions of each spark plug 3.

Here, the ignition coils 11a, 11b, 11
The energization to the primary side of the ignition coil 11c is controlled by the ECU 4, and by selecting which primary side of the ignition coils 11a, 11b, 11c is energized, the above-described three It is configured so that it is possible to select which of the firing sections is to perform ignition.

As shown in FIGS. 2 and 3, the ignition plug 3 has three ignition portions arranged so as to be shifted from each other substantially along the axial direction of the main body, and the ignition portion A closest to the main body side. , A firing portion C furthest from the main body, and three firing portions A, B, and C, which are located substantially in the middle of the firing portions A and C. The axis of the main body is substantially aligned with the axis of the piston. It is attached to the top of the combustion chamber.

The ignition portion is defined as the center electrodes 31a, 31
b, 31c, ground electrodes 32a, 32b, 32c, spark gap 33
a, 33b, and 33c. Here, according to the flowcharts of FIGS.
Will be described in detail.

In step S1, the operating state of the engine 1 is detected. Specifically, an engine speed Ne, a water temperature Tw, and an intake air amount Qa are detected based on detection signals from various sensors.

In step S2, the fuel injection timing IT, the ignition timing (ignition advance value) ADV, and the ignition position (ignition unit for performing ignition) are determined based on the detected operating state.

As shown in the map of FIG. 7, the ignition position is basically the ignition position furthest from the main body of the ignition plug 3 (closest to the piston) when the engine speed is low and the load is low. The ignition position C) is selected, and the ignition position (the ignition portion A) closest to the main body of the ignition plug 3 (the side farthest from the piston) is selected when the rotation speed is high and the load is high.
In other regions, an intermediate ignition position (ignition portion B) is selected.

When stratified charge combustion is performed with the air-fuel mixture unevenly distributed in the vicinity of the spark plug 3 by the injection in the compression stroke by the fuel injection device 2, a plane a orthogonal to the axis of the piston and passing through each ignition portion. , B, and c (see FIG. 8), for example, if the characteristics shown in FIG. 9 are shown, the appropriate ignition position is the ignition portion B corresponding to the plane b where the air-fuel ratio is the highest. Since the plane (ignition position) where the air-fuel ratio becomes the highest moves due to the difference in the strength of the gas flow depending on the operating conditions, the ignition position where the air-fuel ratio becomes the highest under the operating conditions at that time is experimentally obtained in advance. Then, it is stored in a map as shown in FIG.

However, the proper ignition position for each operating condition does not always coincide with the basic characteristics due to variations in each engine, changes over time, etc., so that the appropriate ignition position is learned and corrected as described later. I have.

In step S3, it is determined whether a learning condition is satisfied. Specifically, it is determined whether the learning condition is satisfied as shown in the flowchart of FIG. That is, in step S301, it is determined whether or not a count value n for counting the number of times of learning of the air-fuel ratio at the basic ignition position is equal to or less than a predetermined value α. After the count value n is increased by one in S302, the normal control in steps S4 to S7 is performed. When the count value n exceeds the predetermined value α, the ignition position learning control in step S11 and thereafter is performed.

Therefore, the ignition position learning is configured to be executed each time the ignition at the basic ignition position is performed a predetermined number of times. It is determined that the learning condition is not satisfied, and step S
In step 4, the fuel injection by the fuel injection device 2 is controlled,
In the next step S5, the determined ignition timing ADV
And ignition control based on the ignition position (ignition unit).

In step S6, the air-fuel ratio AF1 at the ignition timing at the ignition portion (ignition position) where ignition has been performed from the combustion state by the ignition is detected. The detection of the air-fuel ratio based on the combustion state is described in, for example, Japanese Patent Application Laid-Open No. 7-1585.
An air-fuel ratio detection method based on an ion current as disclosed in Japanese Patent Publication No. 00 is used. That is, after applying a high voltage for ignition to the ignition plug 3, a constant voltage is applied, and a current flowing in a closed circuit as ions or the like existing in the flame between the center electrode and the ground electrode becomes a conductive medium. (Ion current) is detected, and the air-fuel ratio is obtained from the correlation between the characteristics of the ion current and the characteristics stored in advance for each air-fuel ratio.

However, the method of detecting the air-fuel ratio is not limited to the method described above.
Or a configuration in which the air-fuel ratio is detected from combustion light (discharge spark light) as disclosed in Japanese Unexamined Patent Publication, or any known method for detecting a local air-fuel ratio in the vicinity of a spark plug may be used. . In addition, the presence or absence of misfire is detected from the in-cylinder pressure, etc.,
The misfire rate may be calculated as a parameter correlated to the air-fuel ratio.

In step S7, the detected air-fuel ratio is averaged. In the above description, the control is shifted to the learning control when the ignition at the normal ignition position is performed a predetermined number of times. However, the air-fuel ratio at the normal ignition position detected at step S6 (or the average at step S7). Value) is smaller than the reference air-fuel ratio, it may be configured to determine whether the learning condition is satisfied. In this case, when the position of the richest air-fuel ratio moves and the air-fuel ratio at the normal ignition position becomes so thin that it is difficult to ensure ignition stability,
It is possible to immediately determine whether or not to switch to another ignition unit.

On the other hand, when it is determined in step S3 that the learning condition is satisfied, the routine proceeds to step S11, where the ignition position for learning is set as shown in the flowchart of FIG.

In the flowchart of FIG. 6, first, in step S1101, it is determined whether or not the normal ignition position PN determined in step S2 is the firing portion C. When the normal ignition position is the ignition portion C, the process proceeds to step S1102, and the ignition portion B is set to the learning ignition position Pn.
Set to.

On the other hand, in step S1101, the normal ignition position P
If it is determined that N is not the firing portion C, the process proceeds to step S1103, and it is determined whether the normal ignition position PN is the firing portion B.

When the normal ignition position PN is the firing portion B, the process proceeds to step S1104, where a learning determination flag FL1 is determined. When the flag FL1 is set to 0, the process proceeds to step S1105, where the learning ignition flag FL1 is set. Position Pn
In the next step S1106, 1 is set to the additional learning flag FL2. The additional learning flag FL2 indicates that the normal ignition position PN is the firing portion B, and that the learning at the firing portion A needs to be performed after the learning at the firing portion C.

In step S1104, the flag FL1 is set to 1
Is set, it is determined that the learning at the firing portion C has been completed, and the firing portion A is set at the learning ignition position Pn in step S1107.

If it is determined in step S1103 that the normal ignition position PN is not the ignition portion B, the routine proceeds to step S1108 because the normal ignition position PN is the ignition portion A, and the ignition is performed at the learning ignition position Pn. Set part B.

That is, when the normal ignition position PN is the ignition portion A or the ignition portion C, the ignition is performed in the ignition portion B, and it is learned from the result whether or not the ignition position should be corrected to the ignition portion B. On the other hand, the normal ignition position PN is
, The ignition is performed in each of the ignition section A and the ignition section C, and it is learned from the result whether or not the ignition position should be corrected to the ignition section A or the ignition section C. I have.

When the learning ignition position Pn is set as described above in step S11, the fuel injection is controlled in step S12. In the next step S13, the ignition is performed at the learning ignition position (ignition portion) Pn. Is performed.

In step S14, similarly to step S6, the air-fuel ratio AF2 at the ignition timing at the ignition position (ignition portion) Pn for learning is detected. In step S15, it is determined whether or not the number m of air-fuel ratio detections at the learning ignition position Pn has exceeded a predetermined value β.

If it is determined in step S15 that the number m of air-fuel ratio detections at the learning ignition position Pn has not exceeded the predetermined value β, the process proceeds to step S29, where the number m is counted up. In step S30, the detection result of the air-fuel ratio AF2 at the learning ignition position Pn is averaged.

When the number m of air-fuel ratio detections at the learning ignition position Pn exceeds the predetermined value β, the process proceeds to step S16, where the average air-fuel ratio AF1 detected at the normal ignition position PN is compared with the learning air-fuel ratio AF1. The average air-fuel ratio AF2 detected at the ignition position Pn is called.

In the next step S17, the average air-fuel ratio A
F1 and AF2 are compared. Specifically, it is determined whether or not the average air-fuel ratio AF1 detected at the normal ignition position PN is larger than a value obtained by adding a predetermined value γ to the average air-fuel ratio AF2 detected at the learning ignition position Pn. . Since the air-fuel ratio is data indicating that the larger the air-fuel ratio is, the smaller the air-fuel ratio is detected at the normal ignition position PN. It is to determine whether or not the thickness is smaller than AF2 and the difference exceeds a predetermined value γ. The predetermined value γ may be set to 0, but a hysteresis of control is provided by adding a predetermined value γ (> 0).

In step S17, the normal ignition position PN
The average air-fuel ratio AF1 detected at the time is determined by the learning ignition position Pn.
When it is determined that the value is larger than the value obtained by adding the predetermined value γ to the average air-fuel ratio AF2 detected in the above, it is determined that the ignition position needs to be corrected, and the process proceeds to step S18.

In step S18, the normal ignition position PN stored on the map shown in FIG.
Rewrite to n. On the other hand, when it is determined that the average air-fuel ratio AF1 detected at the normal ignition position PN is equal to or less than a value obtained by adding a predetermined value γ to the average air-fuel ratio AF2 detected at the learning ignition position Pn, the ignition position is determined. It is determined that there is no need for correction, and the process proceeds to step S24, and the process proceeds to step S25 without rewriting the normal ignition position PN stored on the map shown in FIG.

After rewriting the normal ignition position in step S18, the process proceeds to step S19 where the detected air-fuel ratio AF
1, AF2 is cleared, and in steps S20 to S23, the count value n is reset to 0, the initial value 1 is set to the count value m, and the flags FL1 and FL2 are each set to 0.

On the other hand, when it is determined that it is not necessary to rewrite the normal ignition position, and the process proceeds to step S25, it is determined whether or not 1 is set to the additional learning flag FL2.

When the additional learning flag FL2 is set to 0, there is no need to perform additional learning (when the normal ignition timing is the ignition portion A or C). As in the case where the ignition position is corrected in step S18, the processing in steps S19 to S23 is performed.

When the additional learning flag FL2 is set to 0, it is necessary to perform learning in the firing section A following learning in the firing section C.
Proceed to step S26 and subsequent steps.

In step S26, the count value m is set to the initial value 1
Return to In step S27, 1 is set to the flag FL1. By setting 1 to the flag FL1, the process proceeds from step S1104 to step S1107 in the flowchart of FIG. 6, and the ignition portion A is set at the learning ignition position Pn.

In step S28, 0 is set in the flag FL2.
Is set, and the learning control is terminated when the air-fuel ratio detection in the ignition state in the ignition section A is completed. That is, when the normal ignition position PN is the firing portion B,
First, the ignition is performed in the ignition portion C, and the air-fuel ratio at the ignition timing at the position of the ignition portion C is detected. When the air-fuel ratio in the ignition portion C is higher than the air-fuel ratio in the ignition portion B by a predetermined amount or more, Then, the normal ignition position is rewritten in the ignition section B. When the air-fuel ratio in the ignition section C is not higher than the air-fuel ratio in the ignition section B by a predetermined amount or more, the ignition section A is switched to perform ignition, and the air-fuel ratio at the ignition timing in the ignition section A is changed to the ignition section. When the air-fuel ratio at B is higher than a predetermined value, the normal ignition timing is rewritten to the ignition portion A. Further, when the air-fuel ratios in the ignition portions A and C are not higher than the air-fuel ratio in the ignition portion B by more than a predetermined amount, the learning is terminated with the normal ignition timing as the ignition portion B.

In the above embodiment, the spark plug 3 has the three ignition portions A, B, and C along the body axis direction. However, the number of ignition portions is not limited to three. As shown in FIG. 10 and FIG.
May be arranged so as to be displaced from each other substantially in the axial direction of the main body. Alternatively, as shown in FIGS. 12 and 13, the four firing portions A to D may be displaced from each other substantially in the axial direction of the main body. A configuration in which they are arranged may be used.

In the system shown in FIG. 1, three ignition coils 11a, 11a,
11b, 11c and three distributors 12a, 12b,
14c, as shown in FIG. 14, one ignition coil 11 for generating a high voltage and one distributor 12 for distributing the high voltage generated by the ignition coil 11 to each cylinder. A high voltage which is distributed and supplied to the ignition plug 3 of each cylinder by the distributor 12 is selectively applied to one of the center electrodes 31 of each ignition portion by an ignition position switch 13 provided for each cylinder (each ignition plug). It is good also as composition supplied to.

With this configuration, the number of the ignition coils 11 and the distributors 12 can be reduced, so that space can be saved and the system cost can be reduced.

Further, a configuration may be adopted in which an ignition coil is provided for each firing unit, and power distribution by the distributor 12 is not performed. Further, in the above embodiment, the local air-fuel ratio near the ignition position is detected from the combustion state (ion current or combustion light). However, for example, as disclosed in JP-A-6-288283, the ignition timing The air-fuel ratio at the ignition position at the ignition timing may be detected by irradiating the air-fuel mixture in the vicinity of the ignition position with laser light immediately before the time, and based on the degree of absorption of the laser light by the air-fuel mixture. In this case, it is not necessary to switch the ignition position to detect the air-fuel ratio, and while performing the ignition at the normal ignition position, the air-fuel ratio is detected at all the ignition positions, and the appropriate ignition position with the highest air-fuel ratio is detected. Can be changed.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an engine according to an embodiment.

FIG. 2 is a partially enlarged perspective view showing a configuration of a firing portion of a spark plug in the engine.

FIG. 3 is a top view showing a configuration of a firing portion of the ignition plug.

FIG. 4 is a flowchart showing a state of ignition position control in the embodiment.

FIG. 5 is a flowchart showing details of a learning condition determination in the ignition position control.

FIG. 6 is a flowchart showing how a learning ignition position is set in the ignition position control.

FIG. 7 is a diagram showing an ignition position map in the same ignition position control.

FIG. 8 is a diagram illustrating an air-fuel ratio detection plane according to the embodiment.

FIG. 9 is a diagram showing a characteristic example of an air-fuel ratio on the detection plane according to the first embodiment;

FIG. 10 is a front view showing an example of a spark plug provided with two firing portions.

FIG. 11 is a partially enlarged perspective view showing an example of a spark plug provided with two firing portions.

FIG. 12 is a partially enlarged perspective view showing an example of a spark plug provided with four firing portions.

FIG. 13 is a top view showing an example of a spark plug provided with four firing portions.

FIG. 14 is a system configuration diagram illustrating another example of a high-voltage power distribution system.

[Explanation of symbols]

 Reference Signs List 1 engine 2 fuel injection device 3 spark plug 4 engine control unit (ECU) 5 water temperature sensor 6 crank angle sensor 7 air flow meter 8 throttle valve 9 throttle sensor 10 air-fuel ratio sensor 11 ignition coil 12 distributor 13 ignition position switch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01T 13/22 F02P 5/15 B F-term (Reference) 3G019 AA09 KA03 KA12 KA15 3G022 AA06 BA01 EA01 FA05 GA00 GA02 3G023 AA02 AA18 AB03 AC05 AD03 AD09 AD12 AG01 5G059 AA01 CC03 EE23 KK30

Claims (8)

[Claims] 1. A plurality of ignition portions of a spark plug are provided for each cylinder, and the plurality of ignition portions are arranged so as to be shifted from each other substantially along the axial direction of a piston. A combustion control device for an engine, characterized in that ignition is performed at a firing portion selected according to engine operating conditions. 2. A spark plug comprising: a plurality of firing portions for one main body, wherein the plurality of firing portions are arranged so as to be shifted from each other substantially along an axial direction of the main body; 2. The combustion control device for an engine according to claim 1, wherein each of the cylinders is provided in such a manner that a direction substantially coincides with an axial direction of the piston. 3. Each cylinder is provided with a plurality of firing portions for one main body, and each cylinder is provided with a spark plug in which the plurality of firing portions are arranged so as to be shifted from each other substantially along the axial direction of the main body. An ignition control device for an engine, wherein ignition is performed in an ignition portion selected from the plurality of ignition portions according to an engine operating condition. 4. The method according to claim 1, wherein an air-fuel ratio at an ignition timing at each ignition portion is detected, and the ignition portion for performing ignition is learned and corrected based on the detected air-fuel ratio.
3. The combustion control device for an engine according to any one of 3. 5. An apparatus according to claim 1, wherein an air-fuel ratio at an ignition timing at a position of the ignition portion where ignition is performed is detected based on a combustion state, and when a predetermined learning condition is satisfied, a normal ignition portion is detected. The ignition switch is switched to a learning ignition unit different from the learning unit, the ignition is performed, the air-fuel ratio at the ignition timing at the position of the learning ignition unit is detected, and the air-fuel ratio at the normal ignition unit position and the learning are detected. The combustion control apparatus for an engine according to claim 4, wherein the ignition control unit performs learning correction of the ignition unit for performing ignition by comparing the air-fuel ratio at the position of the ignition unit for use. 6. The combustion of an engine according to claim 5, wherein when the ignition by the normal ignition section is performed a predetermined number of times or more, the learning condition is determined to be satisfied, and the ignition section is switched to the ignition section for learning. Control device. 7. When the air-fuel ratio at the ignition timing at the position of the normal firing portion becomes thinner than a reference air-fuel ratio, it is determined that the learning condition is satisfied, and switching to a learning firing portion is performed. The engine combustion control device according to claim 5, wherein 8. A spark plug for an engine, comprising: a plurality of firing portions for one main body; and wherein the plurality of firing portions are arranged so as to be shifted from each other substantially along the axial direction of the main body.