JP3613000B2 - In-cylinder internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct injection internal combustion engine provided with a spark plug having a pair of side poles (ie, two poles).
[0002]
[Prior art]
In recent years, a spark ignition type cylinder injection internal combustion engine that directly injects fuel into a combustion chamber has been developed. In this cylinder injection type internal combustion engine, laminar combustion using fuel injection mainly in a compression stroke is performed. It is possible to operate with an extremely lean air-fuel ratio.
[0003]
[Problems to be solved by the invention]
By the way, in a spark ignition type internal combustion engine, an ignition plug (hereinafter referred to as an ignition plug) is required, and a unipolar type as shown in FIG. 4 is usually used.
In the case of a spark ignition type cylinder injection internal combustion engine, a unipolar spark plug is usually used. In this case, the center pole of the spark plug 31A is changed as shown in FIG. In the case of an in-cylinder injection type internal combustion engine, the ignition condition range of the engine is such that the plug contamination such as carbon adhesion can be avoided (see FIG. 5). ) Ignition timing control must be performed.
[0004]
In other words, if plug contamination does not occur, stable combustion can be achieved in a wide region (region where the air-fuel ratio A / F and EGR rate can be increased) as indicated by the broken line A1 in FIG. 5, but plug contamination occurs. Since the stable combustion region is narrowed as shown by the broken line A2, unless the fouling status of the plug is known, the operation must be performed within the region surrounded by the broken line A2 in order to ensure stable combustion.
[0005]
Therefore, the operation in a region where the air-fuel ratio A / F or the EGR rate is large is restricted, and the super-lean operation in which the air-fuel ratio is largely adjusted to the lean side or sufficient EGR introduction can be performed during this lean operation. Therefore, a sufficient fuel efficiency improvement effect cannot be obtained.
On the other hand, as shown in FIG. 6, the spark plug has a bipolar plug (here, a pair of side poles 36 and 37 sandwiching the center axis 35 of the insulator 34 (axis center line of the center pole 32)). A two-pole semi-creeping plug) has also been developed, and in the case of such a two-pole type spark plug 31B, since it has a stable ignition characteristic, as shown by a solid line B in FIG. The ignition condition range of the engine is wider than that in the case of the spark plug 31A (see the region surrounded by the broken line A2), the ignition timing control range can be expanded, and a further improvement in fuel efficiency can be expected. .
[0006]
The reason why a stable ignition characteristic can be obtained by this bipolar spark plug 31B is that the plug contamination (that is, carbon adhesion to the pole portion) is eliminated by the self-cleaning action. This self-cleaning action is because, due to the positional relationship between the side poles 36 and 37 and the center pole 32, a spark generated between the side poles 36 and 37 and the center pole 32 is generated around the center pole 32 where carbon easily adheres. The carbon around the center pole 32 is burned by this spark and prevents the adhesion around the center pole 32 from being prevented or eliminated.
[0007]
However, in order to obtain this self-cleaning action, it is necessary to increase the ignition energy by the spark plug to some extent.
However, when the ignition energy by the spark plug is increased, as shown in FIG. 7, in the surface of the insulator 34 around the center pole 32, the spark 39 between the side poles 36 and 37 and the center pole 32 is generated. The problem is that, due to the spark 38 being cut by the spark ignition energy, the insulator 38 is damaged or even cracked, and the spark does not fly sufficiently, reducing the durability of the spark plug. There is.
[0008]
As a technique for controlling ignition energy, there is one disclosed in Japanese Utility Model Laid-Open No. 61-12760. However, this technique increases the battery voltage as the engine speed increases, and the required ignition energy is also increased. Since it increases, this is a technique for increasing the ignition energy in accordance with the integrated value of the rotational speed of the engine, and cannot solve the above-mentioned problems.
[0009]
The present invention was devised in view of the above-mentioned problems, and using a bipolar spark plug that can prevent the plug from being soiled by a self-cleaning action, while being able to widen the ignition condition range of the engine, It is an object of the present invention to provide a direct injection internal combustion engine capable of reducing a decrease in durability of a spark plug that is likely to occur as a side effect of a self-cleaning action.
[0010]
[Means for Solving the Problems]
For this reason,BookIn the cylinder injection type internal combustion engine of the invention, the fuel injection valve directly injects fuel into the combustion chamber and ignites the fuel injected by the spark plug facing the combustion chamber. At this time, since the spark plug has a pair of side electrodes provided with the central axis of the insulator interposed therebetween, the ignition plug has stable ignition characteristics, the possible ignition timing range is expanded, and appropriate ignition timing control is performed. Will be able to.
[0011]
Further, in the case of an ignition plug having such a pair of side electrodes, if the ignition energy of the ignition plug is increased, a self-purifying action is obtained, but damage to the insulator is caused.
In contrast, in the direct injection internal combustion engine according to the first aspect of the present invention, the ignition energy control means is configured so that the air-fuel ratio of the engine is in the operating range where the air-fuel ratio of the engine is close to the stoichiometric air-fuel ratio or richer than the stoichiometric air-fuel ratio. Since the ignition energy of the spark plug is reduced while ensuring the ignitability that is more reliable than the operating range in which the fuel ratio is leaner than the stoichiometric air-fuel ratio, damage to the insulator and the like can be avoided while obtaining a self-purifying action.
Moreover, in the ignition energy control means, the control for reducing the ignition energy of the spark plug is not always performed in the specific operation region, but is partially performed in the specific operation region. Can be avoided.
TheAnd claims2In the in-cylinder injection internal combustion engine of the present invention described above, the ignition energy control means is configured so that the air-fuel ratio is the stoichiometric air-fuel ratio for a certain period of time in an operating region where the air-fuel ratio of the engine is close to the stoichiometric air-fuel ratio or richer than the stoichiometric air-fuel ratio. Further, since the ignition energy of the spark plug is made smaller than the leaner operating region, damage to the insulator and the like can be avoided while obtaining a self-cleaning action.
The ignition energy control means includes:In the above specific operation areaIt's a certain timeRisingEven after reducing the ignition energy of the spark plugContinue the above specific operation areaFor example, it is preferable to increase the ignition energy of the spark plug for the next fixed time.3].
The spark plug is preferably configured so that a spark passes through the insulator surface around the center pole.4].
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show a direct injection internal combustion engine as an embodiment of the present invention.
A spark ignition type cylinder injection internal combustion engine (hereinafter also referred to as a cylinder injection engine or simply an engine) according to this embodiment is configured as shown in FIG. 1 for each cylinder 1A of the engine body.
[0013]
That is, an intake port 2A communicating with the intake passage 2 and an exhaust port 3A communicating with an exhaust passage (not shown) are connected to the combustion chamber 1C formed above the piston 1B of each cylinder 1A. The exhaust port 3A is provided with an intake valve 2B and an exhaust valve 3B that open and close between the combustion chamber 1C.
In particular, the intake port 2 is directed vertically downward along the axial center line (not shown) of the cylinder 1A, and the intake air flowing into the combustion chamber 1C from the intake port 2 is formed on the upper surface of the piston 1B. Guided by the curved portion 1D, a tumble flow F can be formed.
[0014]
A fuel injection valve (injector) 4 is disposed at the upper portion of the cylinder 1A, and a spark plug (ignition plug) 5 is disposed at the center upper portion of the cylinder 1A so as to face the combustion chamber 1C. A fuel-air mixture is created by injecting fuel from an injector 4 into an intake tumble flow F formed in 1C, and combustion is performed by igniting this fuel-air mixture with a spark plug 5.
[0015]
In particular, the spark plug 5 has a stable ignition characteristic, and the self-cleaning action causes less plug contamination (for example, carbon adhesion to the pole portion). It is used. That is, as shown in FIG. 6, the spark plug 5 is a bipolar plug having a pair of side electrodes 36 and 37 (in this case, sandwiching the center axis 35 of the insulator 34 (axis center line of the center pole 32)). Bipolar semi creepage plug).
[0016]
In addition, an intake pipe 2C, a surge tank 7, and an intake manifold 2D are connected to the intake passage 2 in this order from the upstream side, and a throttle valve 6 that controls the intake amount is provided upstream of the surge tank 7. Further, an exhaust gas recirculation passage (EGR passage) 8A and an exhaust gas recirculation amount control valve (EGR valve) for opening and closing the EGR passage 8A are provided between the exhaust port 3A and the intake pipe 2C immediately above the surge tank 7 in the intake passage 2. An exhaust gas recirculation device (EGR) 8 comprising 8B is interposed.
[0017]
Various sensors (operating state detecting means) 10 and an electronic control unit (ECU) 20 are provided to control the injector 4, the spark plug 5, the throttle valve 6, and the EGR valve 8B.
In this engine, since the fuel is directly injected from the injector 4 into the cylinder (inside the combustion chamber 1C), the fuel can be injected at any timing regardless of whether the intake valve 2B is opened or closed. For this reason, this engine has a late lean mode in which fuel is injected during the compression stroke and stratified combustion is performed during the compression stroke. In this late lean mode, the tumble is performed at a stage very close to the ignition timing as in the latter half of the compression stroke. Fuel injection is performed toward the flow F, and fuel is collected in the vicinity of the spark plug, and the air-fuel ratio is partially rich to make the whole lean significantly, while ensuring ignitability and combustion stability. Efficient saving operation can be performed.
[0018]
As a mode in which fuel is injected mainly during the intake stroke and premixed combustion is performed, there are a first lean mode, a stoichiometric feedback mode, and an open loop mode.
Of these, in the first lean mode, fuel injection is performed before the second lean mode, and fuel is premixed to ensure ignitability and combustion stability while making the air-fuel ratio leaner than the stoichiometric air-fuel ratio as a whole. However, it is possible to perform some saving operation while obtaining a certain output.
[0019]
In the stoichiometric feedback mode, the O / F ratio is maintained so that the stoichiometric condition is maintained.₂  By performing feedback control based on the output of the sensor, a sufficient engine output can be efficiently obtained while exhibiting an exhaust gas purification action by a three-way catalyst or the like (not shown).
In the open loop mode, combustion is performed by open loop control of the air-fuel ratio to stoichiometric or rich so that a sufficient output can be obtained at the time of acceleration or starting.
[0020]
In this engine, one mode is selected from these various operation modes, and fuel injection control (that is, injection control of the injector 4), ignition control (that is, drive control of the spark plug 5), intake air in each mode. An amount control (that is, control of the throttle valve 6) and an exhaust gas recirculation amount control (that is, control of the EGR valve 8B) are performed.
[0021]
Each of these controls is performed through the ECU 20 based on the driving state detected (or calculated) by the driving state detection means 10. For this reason, as shown in FIG. 1, the ECU 20 includes a mode selection means 21 for selecting an operation mode, a fuel injection control means 22 for controlling the drive of the injector 4, and an ignition control means for controlling the drive of the spark plug 5. 23, an intake control means 24 for controlling the throttle valve 6, and an exhaust gas recirculation control means 25 for controlling the EGR valve 8B.
[0022]
The operating state detection means 10 includes an engine speed sensor 11, a throttle opening sensor 12, an accelerator position sensor (APS) 13, an air flow sensor 14, and an O (not shown).₂Sensors etc. are included. Further, a battery voltage sensor 15 for detecting a voltage of a battery (not shown) as a driving power source for the spark plug 5 and the like is provided.
[0023]
The ECU 20 then obtains effective pressure calculating means (Pe calculation) for calculating the average effective pressure Pe from each information of the engine speed Ne detected by the engine speed sensor 11 and the accelerator opening degree θ detected by the accelerator position sensor 13. Means) 27 is provided, and the average effective pressure (engine load state) Pe calculated by the effective pressure calculating means 27 is used for engine control including fuel injection control as the engine operating state together with the engine speed Ne. It is supposed to be.
[0024]
The mode selection means 21 selects a mode with characteristics as shown in the map of FIG. 2, for example, based on the operating state of the engine, that is, the engine load state Pe and the engine speed Ne. In other words, the late lean mode is selected in the low load / low speed region, and the lean mode, stoichiometric feedback mode, and open loop mode are selected in this order as the load or the rotational speed increases. ing. In FIG. 2, the boundary between the late lean mode and the previous lean mode, and the boundary between the stoichiometric feedback mode and the open loop mode are shown with a one-dot chain line, and the boundary between the lean lean mode and the stoichiometric feedback mode is a solid line. Respectively.
[0025]
In the fuel injection control means 22, the fuel injection amount (fuel injection period) and the fuel injection timing according to the engine operating state such as the engine load state Pe and the engine speed Ne based on the selected operation mode, specifically, An injection end time and an injection start time are set, and the drive of the injector 4 is controlled based on these settings. As for the fuel injection amount, the fuel injection amount is set from the target air-fuel ratio A / F set by the air-fuel ratio setting means 26 and the intake air flow rate detected by the air flow sensor 14. The air-fuel ratio setting means 26 sets the target air-fuel ratio A / F according to the engine operating state such as the engine load state Pe and the engine speed Ne based on the selected operation mode.
[0026]
The ignition control means 23 sets the fuel ignition timing according to the engine operating state such as the engine load state Pe and the engine speed Ne based on the selected operation mode, and drives the spark plug 5 based on this setting. Along with fuel ignition timing control means 23A for controlling, ignition energy control means 23B for controlling the ignition energy of the spark plug 5 is provided. This engine is characterized by this ignition energy control means 23B. Here, controlling the ignition energy means, for example, changing the power supply energizing time to the primary coil in a general ignition system electric circuit (not shown) through the ECU 20.
[0027]
The ignition energy control means 23B reduces the ignition energy of the spark plug 5 in the specific operation region of the engine based on the selected operation mode, and increases the ignition energy of the spark plug 5 in the other operation regions. This specific operation region is an operation region in which the air-fuel ratio of the engine is close to the stoichiometric air-fuel ratio or richer than the stoichiometric air-fuel ratio. As shown by hatching in FIG. 2, the stoichiometric feedback mode and the open loop mode are It corresponds to this.
[0028]
That is, in the ignition energy control means 23B, in the stoichiometric feedback mode or the open loop mode, the ignition energy of the ignition plug 5 is reduced, that is, the energization time of the ignition plug 5 is shortened. Further, in the operation modes other than the stoichiometric feedback mode and the open loop mode, that is, the lean mode (late lean mode or lean lean mode), the ignition energy of the spark plug 5 is increased, that is, the energization time to the primary coil is lengthened. To do.
[0029]
It should be noted that the ignition energy of the spark plug 5 changes not only according to the energization time to the primary coil in the electric circuit of the ignition system (not shown) but also according to the battery voltage (not shown). That is, even if the energization times are equal, the ignition energy decreases if the battery voltage is low. Therefore, it is necessary to lengthen the energization time as the battery voltage is lower. For this reason, in the ignition energy control means 23B, for example, a basic energization time is set using a map in which the energization time is associated with the ignition energy, and the basic energization time corresponds to the battery voltage value detected by the battery voltage sensor 15. The final energization time is set after correction.
[0030]
Such ignition energy control is intended to achieve both the self-cleaning action and durability of the spark plug 5 using such a bipolar spark plug 31B while ensuring a good operating state of the engine. is there.
That is, when the bipolar spark plug 31B is used as the spark plug 5, since the spark passes near the insulator 34 surface around the center pole 32, the periphery of the center pole 32 (the periphery of the center pole 32 itself and the periphery of the center pole 32). It is possible to prevent the carbon from adhering to the surface of the insulator 34) or to remove the adhering carbon, and to expect a self-cleaning action to prevent the plug from being soiled.
[0031]
In order to obtain this self-cleaning action, it is necessary to increase the ignition energy by the spark plug to some extent, but when the ignition energy by the spark plug is increased, the surface of the insulator 34 is scraped by the spark ignition energy to form a groove 38 ( This causes damage or cracking of the insulator 34 and the like, and reduces the durability of the spark plug.
Therefore, by reducing the ignition energy of the spark plug 5 in the specific operation region of the engine and increasing the ignition energy of the spark plug 5 in the other operation regions, both the self-cleaning action and the durability of the spark plug 5 will be achieved. It is what.
[0032]
In selecting the specific operation region in this case, reducing the ignition energy should not adversely affect the combustion. In the lean mode (late lean mode or early lean mode), it is difficult to ensure combustion stability unless reliable ignition is performed. Therefore, during operation in the lean mode (during lean operation), the ignition energy of the spark plug 5 is increased, That is, it is necessary to lengthen the energization time to the primary coil, and here, the ignition energy during lean operation is substantially maximized. On the other hand, in the operation region where the air-fuel ratio is close to the stoichiometric air-fuel ratio or richer than the stoichiometric air-fuel ratio, that is, in the stoichiometric feedback mode and the open loop mode, ignition can be reliably performed even if the ignition energy is reduced. In the operating region, the ignition energy of the spark plug 5 is reduced, that is, the energization time is shortened.
[0033]
In the ignition control means 23, the ignition timing set by the fuel ignition timing control means 23A is used as the start timing of the spark plug 5, and energization is performed for the energization time set by the ignition energy control means 23B from this start timing. Stop energization.
The intake control means 24 sets the intake air amount according to the engine operating state such as the engine load state Pe and the engine speed Ne based on the selected operation mode, and controls the throttle valve 6 based on this setting. .
[0034]
The exhaust gas recirculation control means 25 sets the exhaust gas recirculation amount (recirculation rate) according to the engine operating state such as the engine load state Pe and the engine speed Ne based on the selected operation mode, and the EGR based on this setting. The valve 8B is controlled. Here, EGR is introduced only when the engine is in the late lean mode and stoichiometric feedback mode, but EGR is not introduced in the lean mode or the open loop mode. This is because the effects of NOx reduction and fuel efficiency improvement are very small for the worsening of combustion when EGR is introduced in the first lean mode. Further, in the open loop mode, priority is given to securing the engine output above all. In addition, in the stoichiometric feedback mode, EGR is introduced mainly for the purpose of improving fuel efficiency. However, if EGR is introduced in a large amount, the combustion deteriorates. It is set less than the mode.
[0035]
Since the direct injection internal combustion engine as one embodiment of the present invention is configured as described above, the control of the ignition energy control means 23B of the ignition control means 23 will be mainly described as shown in the flowchart of FIG. To work.
That is, first, in the ECU 20, the operating state detected by the operating state detecting unit 10 based on the engine speed Ne, the throttle opening θth, the accelerator position APS, the intake air flow, and the like, and the average effective pressure calculated by the effective pressure calculating unit 27. (Engine load state) Pe is read (step S10), and based on this operation state (particularly, the engine speed Ne and the engine load state Pe), the operation mode selection means 21 performs the late lean mode, the early lean mode, and stoichiometric feedback. The operation mode is selected from the mode and open loop mode.
[0036]
Next, the value of the battery voltage detected by the battery voltage sensor 15 is read (step S20).
Then, the ignition energy control means 23B of the ignition control means 23 determines whether or not the selected operation mode is the lean mode (late lean mode or early lean mode) (step S30). Is set to a large value (a value stored in advance) (step S40), and if it is not the lean mode, that is, the stoichiometric feedback mode or the open loop mode, the ignition energy is set to a small value (a value stored in advance). Is set (step S50).
[0037]
And the energization time to a primary coil is set based on the battery voltage value read by step S20, and the ignition energy set by step S40 or step S50. For example, the basic energization time is set using a map in which the energization time to the primary coil is associated with the ignition energy, and the basic energization time is corrected according to the battery voltage value detected by the battery voltage sensor 15 to obtain the final value. Set a normal energization time.
[0038]
With such ignition energy control, the spark plug 5 using the bipolar spark plug 31B can secure both a self-cleaning action and durability while ensuring a good operating state of the engine. Is there an advantage?
That is, if the ignition energy by the spark plug is increased to some extent using the bipolar spark plug 31B as the spark plug 5, the spark of a certain amount of energy passes through the vicinity of the insulator 34 surface around the center pole 32, so the center pole 32 itself The carbon is prevented from adhering to the surface of the insulator 34 around the periphery of the central pole 32 and the adhering carbon is removed.
[0039]
By such a self-cleaning action, the plug 5 is prevented from being damaged, and the deterioration of the plug performance due to the contamination is prevented.
As a result, as shown by a solid line B in FIG. 5, compared to the case of the unipolar spark plug 31A in which plug contamination occurs (in the region surrounded by the broken line A2), the air-fuel ratio A / F and EGR rate are wider. Can be stably combusted in an area where the air / fuel ratio can be increased), the super lean operation can be performed with the air-fuel ratio adjusted to the lean side, and sufficient EGR can be introduced during the lean operation, resulting in a sufficient fuel efficiency improvement effect. Be able to get.
[0040]
On the other hand, when the ignition energy by the spark plug is increased in order to obtain the self-cleaning action of the bipolar spark plug 31B, the insulator 34 surface is scraped by the spark ignition energy to form a groove 38 (see FIG. 7). However, in this in-cylinder injection type internal combustion engine, the ignition energy of the spark plug 5 is reduced in a specific operating region of the engine. It is possible to prevent a decrease in durability while ensuring a self-cleaning action.
[0041]
In this case, the specific operation region in which the ignition energy is reduced is the stoichiometric feedback mode or the open loop mode in which reducing the ignition energy does not adversely affect the ignition and combustion. In other words, it is possible to achieve both the self-cleaning action of the spark plug 5 and ensuring the durability.
[0042]
In the present embodiment, the ignition energy is selected from two values of large and small, but the ignition energy may be set in a plurality of stages from finer to smaller. For example, the ignition energy is set to E1 to E3 (E1 <E2 <E3) and is set to E3 in the late lean mode, E2 in the lean mode, and E1 in the stoichiometric feedback mode or the open loop mode. Various configurations are conceivable.
[0043]
Further, the ignition energy may be set according to the engine operating state (for example, the engine speed Ne or the engine load state Pe) regardless of the operation mode. However, also in this case, it is preferable that the ignition energy is relatively increased in the lean mode region, and the region in which the ignition energy is decreased is performed mainly in the stoichiometric feedback mode or the open loop mode with good ignition and combustion stability.
[0044]
Further, the control for reducing the ignition energy in the specific operation region (such as the stoichiometric feedback mode or the open loop mode) having good ignition and combustion stability is not always performed in the specific operation region, but is performed in the specific operation region. It is also possible to perform this partially. For example, if the ignition energy is decreased for a certain time T1 in the specific operation region, the ignition energy may be increased for the next certain time T2.
[0045]
【The invention's effect】
As described above in detail, according to the in-cylinder injection internal combustion engine of the first aspect of the present invention, the spark plug has a pair of side electrodes provided with the central axis of the insulator interposed therebetween. The possible ignition timing range is expanded so that appropriate ignition timing control can be performed, and the ignition energy control means is an operation region in which the air-fuel ratio of the engine is near the stoichiometric air-fuel ratio or richer than the stoichiometric air-fuel ratio. Then, since the ignition energy of the spark plug is made smaller than the operating region where the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, it is possible to avoid damage to the insulator due to excessive ignition energy while obtaining a self-cleaning action. it can. Therefore, the durability of the spark plug can be ensured while improving the performance of the engine such as improving the fuel consumption by appropriate ignition timing control.
Moreover, in the ignition energy control means, the control for reducing the ignition energy of the spark plug is not always performed in the specific operation region, but is partially performed in the specific operation region. Can be avoided.
Claim2According to the described cylinder injection type internal combustion engine of the present inventionIn the ignition energy control means, the control for reducing the ignition energy of the spark plug is performed for a predetermined time in the specific operation region.Therefore, damage to the insulator and the like can be avoided while obtaining a self-cleaning action, and the durability of the spark plug can be ensured while improving the performance of the engine, such as improving fuel efficiency, by appropriate ignition timing control.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a direct injection internal combustion engine as an embodiment of the present invention.
FIG. 2 is a diagram for explaining ignition energy control of a direct injection internal combustion engine as one embodiment of the present invention.
FIG. 3 is a flowchart for explaining ignition energy control of a direct injection internal combustion engine according to an embodiment of the present invention.
FIG. 4 is a side view showing a general unipolar spark plug.
FIG. 5 shows an ignition condition range of a conventional in-cylinder injection internal combustion engine using a general unipolar ignition plug, and a bipolar ignition plug considered in the process of devising the present invention. It is a figure which shows the ignition condition range of a cylinder injection type internal combustion engine.
FIG. 6 is a side view showing a general bipolar type spark plug.
7 is a front view of a spark plug showing a problem in the case of using a bipolar spark plug (a cross-sectional view taken along line AA in FIG. 6).
[Explanation of symbols]
1C Combustion chamber
4 Fuel injection valve
5 Spark plug (ignition plug)
20 ECU
23 Ignition control means
23A Ignition energy control means
34 Reiko
36, 37 Side pole

Claims (4)

A fuel injection valve that injects fuel directly into the combustion chamber;
An ignition plug having a pair of side electrodes provided so as to face the combustion chamber and sandwiching the central axis of the insulator;
Ignition energy control for reducing the ignition energy of the spark plug in a specific operating region where the air-fuel ratio of the engine is close to or richer than the stoichiometric air-fuel ratio than in an operating region where the air-fuel ratio is leaner than the stoichiometric air-fuel ratio With means ,
In the above-mentioned ignition energy control means, the control for reducing the ignition energy of the spark plug is not always performed in the specific operation region, but is partially performed in the specific operation region. . The in- cylinder injection internal combustion engine according to claim 1, wherein the ignition energy control means performs control for reducing the ignition energy of the spark plug for a predetermined time in the specific operation region . The ignition energy control means, if even continue further the specific operating region after reducing the ignition energy of the s predetermined time only the upper Symbol spark plug in the specific operating region, the next predetermined time ignition energy of the ignition plug 3. The direct injection internal combustion engine according to claim 2, wherein The in-cylinder injection internal combustion engine according to any one of claims 1 to 3 , wherein the spark plug is configured such that a spark passes through a surface of an insulator around a central pole.

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