JP2007092692A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase an EGR rate in an area where combustion stability is deteriorated during introduction of EGR gas. <P>SOLUTION: In an internal combustion engine provided with a spark plug 12, 13 at least on a roughly center of a combustion chamber and a circumference wall side of the combustion chamber each per one combustion chamber and with exhaust gas recirculating devices 21 to 24 recirculating exhaust gas discharged from the combustion chamber to an intake air passage 14, a phase different ignition demand judgment means 32 judging whether phase difference of ignition timing of each spark plug 12, 13 is demanded or not according to a combustion condition, a phase difference establishing means 33 establishing phase difference according to the combustion condition if phase difference is demanded, and an ignition execution means 34 igniting the spark plug 13 in the circumference wall side of the combustion chamber with delay in relation to the spark plug 12 on roughly center of the combustion chamber by phase difference established by the phase difference establishing means 33 are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine that includes a plurality of spark plugs in one combustion chamber, and further includes an exhaust gas recirculation device that circulates exhaust gas discharged from the combustion chamber to an intake passage.

  Conventionally, a multipoint ignition type internal combustion engine in which a plurality of ignition plugs are provided in one combustion chamber is known. This multi-point ignition type internal combustion engine generates a plurality of flame nuclei by igniting at a plurality of locations, and burns each flame quickly and uniformly in a form close to complete combustion. For example, as this type of multipoint ignition type internal combustion engine, those disclosed in Patent Documents 1 to 5 below are known.

  First, in the internal combustion engine described in Patent Document 1, one ignition plug is provided at approximately the center and the peripheral wall side of the combustion chamber, and the concentration of the air-fuel mixture is thicker at the central portion of the combustion chamber and at the peripheral wall portion of the combustion chamber. In the case of a thin film, a technique is disclosed in which ignition is performed with a spark plug in the center portion and then ignition is performed with a spark plug in the peripheral wall portion.

  Further, in the internal combustion engine described in Patent Document 2, spark plugs are provided one by one as opposed to the peripheral wall side of the combustion chamber with the central portion as the center, and rotation falls (combustion engine lengthening) occurs. A technique is disclosed in which each spark plug is simultaneously ignited when there is not, and a phase difference is provided to the ignition timing of each spark plug when a rotation drop occurs.

  Furthermore, in the internal combustion engine described in Patent Document 3, two spark plugs are provided at the same position as in Patent Document 2, and a remarkable effect is obtained when a phase difference is added to the ignition timing of each spark plug. A technique is disclosed in which ignition is performed with a phase difference in a certain region (a predetermined operation region determined based on the engine speed and load), while each spark plug is simultaneously ignited in other regions.

  Furthermore, in the internal combustion engine described in Patent Document 4, two spark plugs are provided at the same position as in Patent Document 1, and after ignition with the center spark plug in an extremely low load operation state, the peripheral wall The technique of igniting with the spark plug of a part is disclosed.

  Patent Document 5 discloses a technique in which ignition is performed a plurality of times during one combustion stroke with a single spark plug.

JP 2003-254216 A JP 2000-230470 A JP 2001-289143 A JP-A-4-287871 JP 2001-159367 A

  However, the above-described internal combustion engine of the multipoint ignition system has the effects of higher output, lower fuel consumption, and reduced HC concentration, but has the negative effect of increasing the amount of NOx generated. That is, this multipoint ignition type internal combustion engine can obtain the above-mentioned effect by shortening the combustion period and performing rapid combustion. On the other hand, since a plurality of flame nuclei spread rapidly in the combustion chamber. As a result, the initial combustion becomes steeper than in the case of the central one-point ignition, and the in-cylinder pressure and the in-cylinder temperature (heat generation amount) increase rapidly, and the NOx generation amount increases.

  Here, an exhaust gas recirculation device (so-called EGR device) is known as a technique for solving such a problem. This exhaust gas recirculation device circulates the exhaust gas discharged from the combustion chamber to the intake passage and burns it again in the combustion chamber. When the exhaust gas is introduced into the combustion chamber, the combustion temperature decreases. NOx generation amount is reduced. Moreover, since the pump loss is reduced by introducing the exhaust gas into the combustion chamber, the fuel consumption rate is reduced and the fuel consumption is improved. Hereinafter, the exhaust gas thus recirculated is referred to as “EGR gas”.

  On the other hand, an increase in the amount of EGR gas introduced (in other words, when the EGR rate increases) increases combustion fluctuations due to a decrease in combustion temperature and combustion speed, which makes combustion unstable and decreases the fuel consumption rate. To do. This is particularly noticeable when a large amount of EGR gas is introduced into the combustion chamber when the throttle is fully open (WOT).

  Therefore, the present invention provides an internal combustion engine that improves the disadvantages of the conventional example and can increase the EGR rate in a region such as WOT where the combustion state deteriorates with the introduction of EGR gas. For that purpose.

  In order to achieve the above object, according to the first aspect of the present invention, in one combustion chamber, at least one ignition plug is provided at approximately the center of the combustion chamber and the peripheral wall side of the combustion chamber, and the combustion chamber is further provided. In an internal combustion engine equipped with an exhaust gas recirculation device that circulates exhaust gas exhausted from the exhaust passage to the intake passage, whether or not a phase difference ignition is necessary is determined according to the combustion state whether or not to add a phase difference to the ignition timing of each spark plug When it is necessary to add a phase difference to the determination means, the phase difference setting means for setting the phase difference according to the combustion state, and the ignition plug on the peripheral wall side of the combustion chamber with respect to the ignition plug at the substantially center of the combustion chamber Ignition executing means for igniting with a delay by the phase difference set by the phase difference setting means.

  According to the internal combustion engine of the first aspect, the ignition timing phase difference can be changed between the respective spark plugs according to the combustion state, so that a good combustion state can always be maintained.

  For example, the phase difference ignition necessity determining means may be any one of the EGR valve opening, the throttle opening, the engine load factor, or the EGR rate of the exhaust gas recirculation device and the engine speed as in the second aspect of the invention. Based on the above, it is possible to distinguish between a combustion state region where simultaneous ignition is performed and a combustion state region where phase difference ignition is performed. The EGR rate used in such a case is configured to be obtained from the engine speed, the EGR valve opening, and the engine load factor as in the third aspect of the invention.

  Here, it is preferable that the phase difference setting means is configured to set the phase difference as the combustion state deteriorates, as in the fourth aspect of the invention. As a result, a good combustion state is always effectively maintained. For example, the phase difference setting means is configured to set the phase difference according to any one of the engine speed, the EGR gas temperature, the EGR rate, or the torque fluctuation amount, as in the fifth aspect of the invention. ing.

  According to the internal combustion engine of the present invention, when the engine is in an engine operating state in which the combustion state can be deteriorated, ignition is performed with a phase difference between the respective spark plugs, so that a good combustion state can always be maintained. For this reason, in this internal combustion engine, the limit point of the EGR rate can be extended, and the amount of EGR gas introduced can be increased. As a result, it is possible to further improve the fuel consumption accompanying the decrease in the fuel consumption rate and further reduce the amount of nitrogen oxide (NOx) generated.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

  A first embodiment of an internal combustion engine according to the present invention will be described with reference to FIGS.

  First, the configuration of the internal combustion engine of the first embodiment will be described with reference to FIG. Although an in-line four-cylinder internal combustion engine is shown here, the present invention is not necessarily applied only to such an internal combustion engine.

  Reference numeral 10 in FIG. 1 indicates the internal combustion engine of the first embodiment. In the internal combustion engine 10, two first and second spark plugs 12 and 13 are provided in each cylinder 11. In the first embodiment, the first spark plug 12 is disposed substantially at the center of the combustion chamber, and the second spark plug 13 is disposed on the peripheral wall surface side of the combustion chamber. These first and second spark plugs 12 and 13 ignite in the combustion chambers of the respective cylinders 11, respectively, and air from the intake passage 14 formed in the combustion chambers and fuel injected from the fuel injection device 15. The air-fuel mixture consisting of Then, the in-cylinder gas after combustion in each cylinder 11 is discharged to the exhaust passage 16.

  Further, in the internal combustion engine 10, an air cleaner 17 for removing foreign matters such as dust in the air introduced from the outside, an air flow meter 18 for detecting the amount of intake air from the outside, and an amount of intake air into the combustion chamber are adjusted. A throttle valve 19 is provided on the intake passage 14.

The detection signal of the air flow meter 18 is transmitted to an electronic control unit (ECU) 30 shown in FIG. 1, and the electronic control unit 30 calculates the amount of intake air from the outside. On the other hand, the throttle valve 19 is provided with a throttle valve opening sensor 20, and the electronic control unit 30 that receives the detection signal of the throttle valve opening sensor 20 opens the opening angle of the throttle valve 19 (hereinafter referred to as “throttle”). Called “opening”.) Find θ _TH .

Here, the throttle valve 19 of the first embodiment may be mechanically connected to an accelerator pedal (not shown) via a cable or the like, and is driven and controlled by the electronic control unit 30. Alternatively, a throttle opening degree θ _TH may be adjusted via a throttle valve actuator (not shown) (so-called electronically controlled throttle). In the case of the latter electronically controlled throttle, since the electronic control unit 30 grasps the throttle opening θ _TH by the control command of the throttle opening θ _TH to the throttle valve actuator, the throttle valve opening sensor This may be used instead of the 20 detection signals.

  The electronic control unit 30 includes a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) that stores a predetermined control program and the like, and a RAM (Random Access Memory) that temporarily stores the calculation results of the CPU. , And a backup RAM for storing information prepared in advance.

Further, the internal combustion engine 10 is provided with an exhaust gas recirculation device (so-called EGR device) that recirculates the exhaust gas discharged to the exhaust passage 16 to the intake passage 14 and burns it again in the combustion chamber. The exhaust gas recirculation device includes an EGR passage 21 that allows the exhaust passage 16 and the intake passage 14 to communicate with each other, an EGR valve 22 that allows the exhaust passage 16 and the intake passage 14 to communicate with each other, and an opening / closing drive of the EGR valve 22. And an EGR valve actuator 23 for detecting the valve opening angle (hereinafter referred to as “EGR valve opening”) θ _EGR of the EGR valve 22.

A detection signal of the EGR valve opening sensor 24 is transmitted to the electronic control device 30, and the electronic control device 30 grasps the EGR valve opening θ _EGR . Here, the EGR valve actuator 23 is driven and controlled by a control command for the EGR valve opening θ _EGR by the electronic control unit 30. For this reason, the electronic control unit 30 may grasp the EGR valve opening degree θ _EGR from the control command instead of the detection signal of the EGR valve opening degree sensor 24 described above.

  The internal combustion engine 10 is also provided with various sensors such as a crank angle sensor 26 that detects the rotational speed of the crankshaft 25. The electronic control device 30 uses detection signals of the various sensors. Understands the operating state of the internal combustion engine (hereinafter referred to as “engine operating state”).

For example, the electronic control unit 30 grasps the engine speed Ne from the crank angle sensor 26, and, as described above, from the throttle valve opening sensor 20 and the EGR valve opening sensor 24, the throttle opening θ _TH. And EGR valve opening degree θ _EGR is grasped.

Further, the electronic control unit 30 calculates and grasps the engine load factor KL as the engine operating state. For example, the engine load factor KL can be calculated by referring to a predetermined map based on the throttle opening θ _TH and the engine speed Ne.

Meanwhile, the first and second spark plugs 12 and 13 of each cylinder 11 described above have the engine operating state (throttle opening θ _TH , EGR valve opening θ _EGR , engine speed Ne, The electronic control unit 30 grasps the combustion state based on the engine load factor KL, the fuel injection amount, etc., and executes ignition based on the control command from the electronic control unit 30 at the ignition timing corresponding to the combustion state.

  Therefore, the electronic control device 30 of the first embodiment first includes a simultaneous ignition timing setting means 31 for setting the simultaneous ignition timing of the first and second spark plugs 12 and 13 in each cylinder 11 according to the combustion state. Provide. The simultaneous ignition timing setting means 31 is configured based on, for example, the same idea as the simultaneous ignition timing setting method in the technical field.

Here, when the EGR rate is high, as shown in FIG. 2, it is better to ignite with a phase difference between the ignition timings than to ignite the first and second ignition plugs 12 and 13 of the same cylinder 11 simultaneously. Even if the EGR rate is the same, it is possible to stabilize the combustion and lower the fuel consumption rate. On the other hand, by adding a phase difference to the ignition timings of the first and second spark plugs 12 and 13, the EGR rate limit point can be extended to the same combustion stability limit as in the case of simultaneous ignition. The consumption rate can be reduced. The EGR rate is defined by the engine speed Ne, the EGR valve opening degree θ _EGR and the engine load factor KL. For example, the engine speed Ne, the EGR valve opening degree θ _EGR and the engine load factor KL are parameters. As shown, an EGR rate map (not shown) capable of obtaining the EGR rate is prepared.

  For this reason, the electronic control unit 30 according to the first embodiment has a phase difference ignition necessity for determining whether or not to make a phase difference between the ignition timings of the first spark plug 12 and the second spark plug 13 in the same cylinder 11. A rejection determination means 32 is provided. This phase difference ignition necessity determination means 32 determines that the region where the deterioration of the combustion state becomes remarkable with the introduction of EGR gas is the phase difference ignition execution region, and determines the other region as the simultaneous ignition execution region. Constitute.

For example, whether it is the phase difference ignition execution region or the simultaneous ignition execution region can be determined by the EGR valve opening degree θ _EGR and the engine speed Ne, which are parameters that define the EGR rate. For this reason, in the first embodiment, it can be determined in FIG. 3 whether the phase difference ignition execution region or the simultaneous ignition execution region can be determined according to the EGR valve opening degree θ _EGR and the engine speed Ne. A phase difference ignition necessity determination map is prepared in advance in a ROM or the like of the electronic control unit 30, and based on the phase difference ignition necessity determination map, the phase difference ignition necessity determination means 32 determines which execution region it is in. Let This phase difference ignition necessity determination map is created, for example, by examining the EGR valve opening degree θ _EGR and the combustion state (for example, the combustion stability limit) for each engine speed Ne in advance through experiments and simulations.

Here, when the EGR valve opening degree θ _EGR is constant, the amount of exhaust gas increases as the engine speed Ne increases, and the differential pressure between the exhaust passage 16 and the intake passage 14 increases. As the engine speed Ne increases, the EGR rate increases, the amount of EGR gas introduced increases, and the combustion state deteriorates. On the other hand, if the engine speed Ne is low, the amount of exhaust gas is small, and the differential pressure between the exhaust passage 16 and the intake passage 14 is also small. For this reason, at the time of low rotation, even if the EGR valve opening degree θ _EGR is large, the EGR rate is low and the amount of introduced EGR gas is small, so the combustion state becomes better than that at the time of high rotation. That is, in the case of the same EGR valve opening degree θ _EGR , the combustion state becomes worse as the engine speed Ne becomes higher. Therefore, in the phase difference ignition necessity determination map, as shown in FIG. 3, the phase difference ignition execution region is expanded as the engine speed Ne increases.

  When the phase difference ignition necessity determination unit 32 makes the determination in this way and determines that the phase difference ignition execution region, it is determined to what extent between the first spark plug 12 and the second spark plug 13 next. It is necessary to decide whether to provide the ignition timing phase difference. For this reason, the electronic control unit 30 of the first embodiment is provided with a phase difference setting means 33 for setting the phase difference of the ignition timing. This phase difference setting means 33 is configured to set a larger phase difference as the combustion state deteriorates.

Here, as described above, when the EGR valve opening degree θ _EGR is constant, the EGR rate increases as the engine speed Ne increases, and the combustion state deteriorates. Therefore, in the first embodiment, the phase difference setting map shown in FIG. 4 in which the phase difference increases as the engine speed Ne increases increases in advance in the ROM of the electronic control unit 30 for each EGR valve opening θ _EGR. Prepared and causes the phase difference setting means 33 to set the phase difference based on the phase difference setting map. This phase difference setting map is obtained by, for example, investigating the combustion state (for example, the combustion stability limit) for each engine speed Ne in advance by experiments and simulations with a constant EGR valve opening θ _EGR and opening the EGR valve based on the result. Created every degree θ _EGR .

The phase difference setting means 33 of the first embodiment calls a phase difference setting map corresponding to the detected EGR valve opening degree θ _EGR from the ROM or the like, and a phase difference corresponding to the detected engine speed Ne is set to the phase difference setting map. Read from. The ignition timing of the second spark plug 13 on the peripheral wall side of the combustion chamber is set so as to be delayed by a phase difference from the above-described simultaneous ignition timing.

  Further, the electronic control unit 30 of the first embodiment is provided with an ignition execution means 34 that executes ignition on the first and second spark plugs 12 and 13. The ignition execution means 34 is configured to ignite the first and second spark plugs 12 and 13 at the simultaneous ignition timing in the case of the simultaneous ignition execution region. On the other hand, in the case of the phase difference ignition execution region, the first spark plug 12 disposed in the approximate center of the combustion chamber is ignited at the above-mentioned simultaneous ignition timing, and the second spark plug 13 disposed on the peripheral wall side of the combustion chamber. Is ignited late by the above phase difference.

  Next, the ignition control operation of the internal combustion engine 10 of the first embodiment described above will be described based on the flowchart of FIG.

First, the electronic control unit 30 according to the first embodiment grasps engine operating state information (step ST1). For example, here, the throttle opening θ _TH , the EGR valve opening θ _EGR, and the engine speed Ne are ascertained from the detection signals of the throttle valve opening sensor 20, the EGR valve opening sensor 24, and the crank angle sensor 26. . Here, the engine load factor KL is also calculated based on the throttle opening θ _TH and the engine speed Ne.

  The electronic control unit 30 grasps the combustion state based on the engine operation state information, and the simultaneous ignition timing setting means 31 causes the simultaneous ignition timings of the first and second spark plugs 12 and 13 corresponding to the combustion state. Is set (step ST2).

Then, the phase difference ignition necessity determination means 32 of the electronic control unit 30 compares the EGR valve opening θ _EGR and the engine speed Ne obtained in step ST1 with the phase difference ignition necessity determination map shown in FIG. In addition, it is determined whether it is the phase difference ignition execution region or the simultaneous ignition execution region (step ST3).

  Here, when the phase difference ignition execution region is determined, the phase difference setting means 33 of the electronic control unit 30 determines the level of the ignition timing between the first spark plug 12 and the second spark plug 13. A phase difference is set (step ST4). Here, the phase difference corresponding to the engine speed Ne obtained in step ST1 is read from the phase difference setting map shown in FIG. At this time, since the combustion state is worse as the engine speed Ne is higher, a large phase difference is set.

  Thereafter, the electronic control unit 30 causes the ignition execution means 34 to ignite the first ignition plug 12 disposed substantially at the center of the combustion chamber at the simultaneous ignition timing set in step ST2 above the peripheral wall side of the combustion chamber. The arranged second spark plug 13 is ignited after the simultaneous ignition timing by the phase difference set in step ST4 (step ST5).

  On the other hand, when it is determined in step ST3 that the simultaneous ignition execution region has been made, the ignition execution means 34 of the electronic control unit 30 sets the first and second spark plugs 12 and 13 in step ST2. Simultaneous ignition is performed at the same ignition timing (step ST6).

  As described above, according to the internal combustion engine 10 of the first embodiment, the first spark plug 12 and the second spark plug 13 are always ignited with a phase difference when the engine is in an engine operating state in which the combustion state can be deteriorated. A good combustion state can be maintained. Therefore, in the internal combustion engine 10 of the first embodiment, as shown in FIG. 2, the limit point of the EGR rate can be extended and the amount of EGR gas introduced can be increased, so that the fuel consumption rate is reduced and the fuel consumption is reduced. Can be further improved. In addition, the amount of nitrogen oxide (NOx) generated can be further reduced as the amount of EGR gas introduced increases. In particular, in the internal combustion engine 10 of the first embodiment, since a large amount of EGR gas can be introduced even during WOT by such phase difference ignition, it is possible to improve fuel consumption and reduce NOx in various operating conditions. It becomes possible.

  Next, a second embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. The internal combustion engine 10 of the second embodiment is configured in the same manner as the above-described first embodiment shown in FIG. 1 except for the following points.

The phase difference ignition necessity determination unit 32 according to the first embodiment determines whether the phase difference ignition execution area or the simultaneous ignition execution area by using the above-described phase difference ignition necessity determination map shown in FIG. Yes. In the phase difference ignition necessity determination map used in the first embodiment, the EGR valve opening degree θ _EGR that defines the EGR rate and the engine speed Ne are determined for the phase difference ignition execution region or the simultaneous ignition execution region. It is determined according to the above.

However, as to whether it is the phase difference ignition execution region or the simultaneous ignition execution region, it is possible to use the throttle opening θ _TH instead of the EGR valve opening θ _EGR of the first embodiment. It can also be defined by the degree θ _TH and the engine speed Ne. That is, when the throttle opening degree θ _TH is constant, the amount of exhaust gas increases as the engine speed Ne increases, and the differential pressure between the exhaust passage 16 and the intake passage 14 increases, so that the engine speed As the number Ne increases, the EGR rate increases, the amount of EGR gas introduced increases, and the combustion state deteriorates. On the other hand, if the engine speed Ne is low, the amount of exhaust gas is small, and the differential pressure between the exhaust passage 16 and the intake passage 14 is also small. For this reason, at the time of low rotation, even if the throttle opening degree θ _TH is large, the EGR rate is low and the amount of EGR gas introduced is small, so the combustion state is better than at high rotation. That is, in the case of the same throttle opening degree θ _TH , the combustion state becomes worse as the engine speed Ne becomes higher.

Accordingly, in the second embodiment, whether the phase difference ignition execution region or the simultaneous ignition execution region can be determined according to the correspondence between the throttle opening θ _TH and the engine speed Ne. Is prepared in advance in a ROM or the like of the electronic control unit 30. This phase difference ignition necessity determination map of the second embodiment is obtained by, for example, investigating beforehand the combustion stability (for example, the combustion stability limit) for each throttle opening θ _TH and engine speed Ne by experiments and simulations. Based on the increase in the engine speed Ne, the phase difference ignition execution region is created to expand.

The phase difference ignition necessity determination means 32 of the second embodiment refers to the phase difference ignition necessity determination map shown in FIG. 6, and the region corresponding to the detected throttle opening θ _TH and the engine speed Ne is the phase difference. It is determined whether it is an ignition execution region or a simultaneous ignition execution region.

  Note that the simultaneous ignition timing setting means 31, the phase difference setting means 33, and the ignition execution means 34 provided in the electronic control unit 30 of the second embodiment operate in the same manner as in the first embodiment, and thus description thereof is omitted here. .

  As described above, also in the second embodiment, as in the first embodiment described above, the first spark plug 12 and the second spark plug 13 are provided with a phase difference in the engine operating state in which the combustion state can be deteriorated. Since ignition is performed, a good combustion state can always be maintained, and further, the limit point of the EGR rate can be extended. Therefore, even in the internal combustion engine 10 of the second embodiment, the amount of EGR gas introduced can be increased, so that further improvement in fuel consumption and further reduction in NOx can be achieved due to a decrease in fuel consumption rate. . In particular, since a large amount of EGR gas can be introduced even at the time of WOT, it is possible to improve fuel consumption and reduce NOx in various operating conditions.

  Next, a third embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. The internal combustion engine 10 of the third embodiment is configured in the same manner as the above-described first embodiment shown in FIG. 1 except for the following points.

  In this third embodiment, as in the second embodiment described above, the phase difference ignition necessity determination map is changed with respect to the first embodiment.

  Specifically, in the third embodiment, whether it is the phase difference ignition execution region or the simultaneous ignition execution region is defined by the engine load factor KL and the engine speed Ne, which are other parameters that define the EGR rate. To do. For this reason, the phase difference ignition necessity determination map of the third embodiment is, as shown in FIG. 7, whether the phase difference ignition execution region is in accordance with the correspondence relationship between the engine load factor KL and the engine speed Ne. It is configured so that it can be determined whether it is an execution area. This phase difference ignition necessity determination map, for example, is obtained by examining the combustion state (for example, the combustion stability limit) for each engine load factor KL and engine speed Ne in advance through experiments and simulations, and is created based on the results to create an electronic control unit. It is stored in 30 ROMs.

  Here, when the engine load factor KL is constant, the amount of exhaust gas increases as the engine rotational speed Ne increases, and the differential pressure between the exhaust passage 16 and the intake passage 14 increases, so that the engine speed As the number Ne increases, the EGR rate increases, the amount of EGR gas introduced increases, and the combustion state deteriorates. On the other hand, if the engine speed Ne is low, the amount of exhaust gas is small, and the differential pressure between the exhaust passage 16 and the intake passage 14 is also small. For this reason, at the time of low rotation, even if the engine load factor KL is high, the EGR rate is low and the amount of EGR gas introduced is small, so the combustion state becomes better than at high rotation. That is, in the case of the same engine load factor KL, the combustion state becomes worse as the engine speed Ne becomes higher. Accordingly, in the phase difference ignition necessity determination map of the third embodiment, as shown in FIG. 7, the phase difference ignition execution region is expanded as the engine speed Ne increases.

  The phase difference ignition necessity determination means 32 of the third embodiment refers to the phase difference ignition necessity determination map shown in FIG. 7, and the region corresponding to the calculated engine load factor KL and the engine speed Ne is the phase difference ignition. It is determined whether it is an execution region or a simultaneous ignition execution region.

  Note that the simultaneous ignition timing setting means 31, the phase difference setting means 33, and the ignition execution means 34 provided in the electronic control unit 30 of the third embodiment operate in the same manner as in the first embodiment, and thus description thereof is omitted here. .

  As described above, in the third embodiment as well, in the same way as in the first embodiment described above, the first spark plug 12 and the second spark plug 13 are provided with a phase difference when the engine operating state is likely to deteriorate the combustion state. Since ignition is performed, a good combustion state can always be maintained, and further, the limit point of the EGR rate can be extended. Therefore, even in the internal combustion engine 10 of the third embodiment, the amount of EGR gas introduced can be increased, so that further improvement in fuel consumption and further reduction in NOx can be achieved due to a decrease in fuel consumption rate. . In particular, since a large amount of EGR gas can be introduced even at the time of WOT, it is possible to improve fuel consumption and reduce NOx in various operating conditions.

  Next, a fourth embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. The internal combustion engine 10 of the fourth embodiment is configured in the same manner as the first embodiment shown in FIG. 1 except for the following points.

  In this fourth embodiment, as in the second and third embodiments described above, the phase difference ignition necessity determination map is changed with respect to the first embodiment.

  Specifically, in the fourth embodiment, whether the phase difference ignition execution region or the simultaneous ignition execution region is defined by the EGR rate and the engine speed Ne. For this reason, the phase difference ignition necessity determination map of the fourth embodiment is, as shown in FIG. 8, a phase difference ignition execution region or a simultaneous ignition execution region depending on the correspondence between the EGR rate and the engine speed Ne. It is configured so that it can be determined. This phase difference ignition necessity determination map, for example, is obtained by examining the EGR rate and the combustion stability for each engine speed Ne (for example, the combustion stability limit) in advance through experiments and simulations, and is created based on the results, and the electronic control unit 30. Stored in a ROM or the like.

  Here, when the EGR rate is constant, the amount of exhaust gas increases due to the increase in the engine speed Ne, and the differential pressure between the exhaust passage 16 and the intake passage 14 increases, so the engine speed Ne. As the value rises, the EGR rate increases, the amount of EGR gas introduced increases, and the combustion state deteriorates. On the other hand, if the engine speed Ne is low, the amount of exhaust gas is small, and the differential pressure between the exhaust passage 16 and the intake passage 14 is also small. For this reason, at the time of low rotation, since the introduction amount of EGR gas is small even if the EGR rate is high, the combustion state becomes better than that at the time of high rotation. That is, in the case of the same EGR rate, the combustion state gets worse as the engine speed Ne becomes higher. Therefore, in the phase difference ignition necessity determination map of the fourth embodiment, as shown in FIG. 8, the phase difference ignition execution region is expanded as the engine speed Ne increases.

The phase difference ignition necessity determination means 32 of the fourth embodiment refers to the phase difference ignition necessity determination map shown in FIG. 8 and uses the engine speed Ne, the EGR valve opening θ _EGR and the engine load factor KL. It is determined whether the region corresponding to the EGR rate obtained from the EGR rate map and the engine speed Ne is the phase difference ignition execution region or the simultaneous ignition execution region.

  The simultaneous ignition timing setting unit 31, the phase difference setting unit 33, and the ignition execution unit 34 provided in the electronic control unit 30 of the fourth embodiment operate in the same manner as in the first embodiment, and thus description thereof is omitted here. .

  As described above, in the fourth embodiment as well, in the same way as in the first embodiment described above, the first spark plug 12 and the second spark plug 13 are provided with a phase difference when the engine operating state is likely to deteriorate the combustion state. Since ignition is performed, a good combustion state can always be maintained, and further, the limit point of the EGR rate can be extended. Therefore, even in the internal combustion engine 10 of the fourth embodiment, the amount of EGR gas introduced can be increased, so that further improvement in fuel consumption and further reduction in NOx can be achieved due to a decrease in fuel consumption rate. . In particular, since a large amount of EGR gas can be introduced even at the time of WOT, it is possible to improve fuel consumption and reduce NOx in various operating conditions.

  Next, a fifth embodiment of the internal combustion engine according to the present invention will be described with reference to FIGS. The internal combustion engine 10 of the fifth embodiment is configured in the same manner as the first embodiment shown in FIG. 1 except for the following points.

The phase difference setting means 33 of the first to fourth embodiments uses the phase difference setting map shown in FIG. 4 described above to determine the ignition timing between the first spark plug 12 and the second spark plug 13 when the phase difference ignition is executed. The phase difference is set. The phase difference setting map used in each of the first to fourth embodiments is prepared for each EGR valve opening θ _EGR, and is a phase difference that stabilizes combustion according to the engine speed Ne (in the above example, the combustion stability limit and Phase difference).

  However, it is known that the combustion state generally worsens as the EGR gas temperature rises, and the phase difference can be defined by the EGR gas temperature. Therefore, in the fifth embodiment, in each of the first to fourth embodiments described above, the phase difference shown in FIG. 9 increases as the EGR gas temperature increases (that is, as the combustion state deteriorates). A setting map is prepared in advance in the ROM of the electronic control unit 30. For example, this phase difference setting map is created based on the result of examining the combustion state (for example, the combustion stability limit) for each EGR gas temperature in advance through experiments and simulations.

  Further, the internal combustion engine 10 of the fifth embodiment is provided with a temperature sensor 27 shown in FIG. 1 for detecting the EGR gas temperature. This temperature sensor 27 may be dedicated to the EGR gas provided in the EGR passage 21, or the detection value of the exhaust temperature sensor provided in the exhaust passage 16 may be substituted. In the fifth embodiment, the latter temperature sensor 27 is illustrated.

  The phase difference setting means 33 of the fifth embodiment reads the phase difference corresponding to the detected EGR gas temperature from the phase difference setting map, and sets the ignition timing of the second spark plug 13 on the peripheral wall side of the combustion chamber as the first spark plug. 12 is set with a phase difference delayed from the ignition timing of 12.

  The simultaneous ignition timing setting means 31, the phase difference ignition necessity determination means 32, and the ignition execution means 34 provided in the electronic control unit 30 of the fifth embodiment operate in the same manner as in the first to fourth embodiments. Description of is omitted.

  As described above, also in the fifth embodiment, similarly to the first embodiment described above, the first spark plug 12 and the second spark plug 13 are provided with a phase difference when the engine operating state in which the combustion state can be deteriorated. Since ignition is performed, a good combustion state can always be maintained, and further, the limit point of the EGR rate can be extended. Therefore, even in the internal combustion engine 10 of the fifth embodiment, it is possible to increase the amount of EGR gas introduced, so that further improvement in fuel consumption and further reduction in NOx can be achieved due to a decrease in fuel consumption rate. . In particular, since a large amount of EGR gas can be introduced even at the time of WOT, it is possible to improve fuel consumption and reduce NOx in various operating conditions.

  Next, a sixth embodiment of the internal combustion engine according to the present invention will be described with reference to FIG. The internal combustion engine 10 of the sixth embodiment is configured in the same manner as the above-described first embodiment shown in FIG. 1 except for the following points.

  In this sixth embodiment, the phase difference setting map is changed with respect to the first to fourth embodiments, similarly to the fifth embodiment described above.

  Specifically, in the sixth embodiment, the combustion state deteriorates as the EGR rate increases, so the phase difference is defined by the EGR rate. For this reason, in the sixth embodiment, in each of the first to fourth embodiments described above, the phase difference setting shown in FIG. 10 increases the phase difference as the EGR rate increases (that is, as the combustion state deteriorates). A map is prepared in advance in a ROM or the like of the electronic control unit 30. For example, this phase difference setting map is created based on the result of examining the combustion state (for example, the combustion stability limit) for each EGR rate in advance through experiments and simulations.

The phase difference setting means 33 of the sixth embodiment obtains an EGR rate from the EGR rate map using the engine speed Ne, the EGR valve opening θ _EGR and the engine load factor KL, and shows the phase difference corresponding to the EGR rate. 10 is read from the phase difference setting map shown in FIG. 10, and the ignition timing of the second spark plug 13 on the peripheral wall side of the combustion chamber is set to be delayed from the ignition timing of the first spark plug 12 by a phase difference.

  The simultaneous ignition timing setting means 31, the phase difference ignition necessity determination means 32 and the ignition execution means 34 provided in the electronic control unit 30 of the sixth embodiment operate in the same manner as in the first to fourth embodiments. Description of is omitted.

  As described above, also in the sixth embodiment, similarly to the first embodiment described above, the first spark plug 12 and the second spark plug 13 are provided with a phase difference when the engine operating state is likely to deteriorate the combustion state. Since ignition is performed, a good combustion state can always be maintained, and further, the limit point of the EGR rate can be extended. Therefore, even in the internal combustion engine 10 of the sixth embodiment, it is possible to increase the amount of EGR gas introduced, so that further improvement in fuel consumption and further reduction in NOx can be achieved due to a decrease in fuel consumption rate. . In particular, since a large amount of EGR gas can be introduced even at the time of WOT, it is possible to improve fuel consumption and reduce NOx in various operating conditions.

  Next, a seventh embodiment of the internal combustion engine according to the present invention will be described with reference to FIGS.

  The seventh embodiment exemplifies a hybrid vehicle that uses both a prime mover and an electric motor as power sources, specifically, a series / parallel hybrid hybrid vehicle. As the prime mover of the seventh embodiment, as shown in FIG. 11, an internal combustion engine 10 configured in the same manner as each of the first to fourth embodiments described above except for the following points is used.

  First, the configuration of this hybrid vehicle will be briefly described. The hybrid vehicle includes a power split mechanism 51 that splits engine power output from the internal combustion engine 10, a generator 52 that is driven by the engine power of the internal combustion engine 10 that is split by the power split mechanism 51, and the generator An electric motor 53 driven by electric power of 52 and / or electric power of the battery 61 is provided.

  Here, the power split mechanism 51 includes, for example, a planetary carrier whose rotating shaft is connected to the crankshaft 25 of the internal combustion engine 10, a pinion gear supported by the planetary carrier, and a rotating shaft connected to the generator 52. The planetary gear mechanism includes a sun gear and a ring gear whose rotating shaft is coupled to the electric motor 53, and a drive shaft (not shown) is coupled to the ring gear via a power transmission mechanism such as a transmission 71. For this reason, the engine power of the internal combustion engine 10 is transmitted to the sun gear and the ring gear via the pinion gear and can be used as the driving force of the generator 52, while the drive shaft can be directly driven via the power transmission mechanism. .

  The hybrid vehicle is also provided with a control means for controlling various operations. In the seventh embodiment, as the control means, an electronic control device (hereinafter referred to as “main ECU”) 81 for controlling the operation of the entire hybrid vehicle and the above-described embodiments for controlling the operation of the internal combustion engine 10. An electronic control device (hereinafter referred to as “engine ECU”) 30 similar to 1 to 4 and an electronic control device (hereinafter referred to as “electric motor ECU”) 82 for controlling the operation of the electric motor 53 are provided. The main ECU 81 obtains a required driving force value (hereinafter referred to as “driving force required value”) for the driving shaft in accordance with the driving state based on detection signals from various sensors, map data in the backup RAM, and the like. The main ECU 81 sets the power and distribution of the internal combustion engine 10 and the electric motor 53 that can generate a driving force corresponding to the required driving force value on the driving shaft, and sends the setting conditions to the engine ECU 30 and the electric motor ECU 82. .

  By the way, in the internal combustion engine 10, torque fluctuation occurs when combustion becomes unstable. Since this torque fluctuation increases as the combustion stability deteriorates (that is, as the combustion state deteriorates), if the amount of torque fluctuation is known, the ignition between the first spark plug 12 and the second spark plug 13 will occur. The phase difference of the time can be defined. On the other hand, the torque fluctuation of the internal combustion engine 10 is transmitted to the electric motor 53 via the crankshaft 25 and the power split mechanism 51 and detected by the electric motor ECU 82 in this type of hybrid vehicle. Therefore, the phase difference can be set by using the torque fluctuation information of the internal combustion engine 10 detected by the electric motor ECU 82.

  Therefore, in the seventh embodiment, the electric motor ECU 82 is configured to transmit the information of the torque fluctuation amount to the main ECU 81 when the torque fluctuation of the internal combustion engine 10 is detected, and the received torque fluctuation is received for the main ECU 81. The information of the quantity is configured to be transmitted to the engine ECU 30.

  Further, a phase difference setting map shown in FIG. 12 showing the correspondence between the torque fluctuation amount of the internal combustion engine 10 and the phase difference is prepared in advance in the ROM or the like of the engine ECU 30. This phase difference setting map, for example, examines the combustion stability (for example, the combustion stability limit) for each torque fluctuation amount in advance by experiments and simulations, and based on the results, the torque fluctuation amount increases (that is, the combustion state). It is created so that the phase difference increases).

  The phase difference setting means 33 of the seventh embodiment reads the phase difference corresponding to the torque fluctuation amount information received from the electric motor ECU 82 from the main ECU 81 from the phase difference setting map shown in FIG. The ignition timing of the second ignition plug 13 is set with a phase difference delayed from the ignition timing of the first ignition plug 12. Here, the information of the torque fluctuation amount is grasped in, for example, step ST1 in FIG.

  The simultaneous ignition timing setting means 31, the phase difference ignition necessity determination means 32, and the ignition execution means 34 provided in the electronic control unit 30 of the seventh embodiment operate in the same manner as in the first to fourth embodiments. Description of is omitted.

  As described above, also in the seventh embodiment, similarly to the first embodiment described above, the first spark plug 12 and the second spark plug 13 are provided with a phase difference when the engine operating state in which the combustion state can be deteriorated. Since ignition is performed, a good combustion state can always be maintained, and further, the limit point of the EGR rate can be extended. Therefore, even in the internal combustion engine 10 of the seventh embodiment, the amount of EGR gas introduced can be increased, so that further improvement in fuel consumption and further reduction in NOx can be achieved due to a decrease in fuel consumption rate. . In particular, since a large amount of EGR gas can be introduced even at the time of WOT, it is possible to improve fuel consumption and reduce NOx in various operating conditions.

  In the first to seventh embodiments described above, the internal combustion engine in which two spark plugs (first and second spark plugs 12 and 13) are provided in one combustion chamber is illustrated. The ignition control in -7 may be applied to an internal combustion engine provided with more spark plugs. In such a case, as in the first to seventh embodiments, the ignition timing of the spark plug group on the peripheral wall side is delayed by the phase difference with respect to the spark plug group on the central side separately from the central side and the peripheral wall side of the combustion chamber. May be ignited, and an optimum phase difference may be appropriately provided between the respective spark plugs.

  In each of the first to seventh embodiments described above, the second spark plug 13 disposed on the peripheral wall side of the combustion chamber is based on the ignition timing of the first spark plug 12 disposed substantially in the center of the combustion chamber. Although the ignition timing is delayed by the phase difference, conversely, the ignition timing of the first spark plug 12 may be advanced based on the ignition timing of the second spark plug 13.

  As described above, the internal combustion engine according to the present invention is useful for the ignition control technique that can suppress the deterioration of the combustion state accompanying the introduction of EGR gas and increase the amount of EGR gas introduced.

It is a figure which shows the structure of Examples 1-6 of the internal combustion engine which concerns on this invention. It is a figure which shows the fuel consumption rate with respect to EGR rate at the time of simultaneous ignition, and the time of phase difference ignition, and combustion stability. It is a figure shown about the phase difference ignition necessity determination map of Example 1. FIG. It is a figure shown about the phase difference setting map of Example 1. FIG. 3 is a flowchart illustrating an ignition control operation of the internal combustion engine according to the present invention. It is a figure shown about the phase difference ignition necessity determination map of Example 2. FIG. It is a figure shown about the phase difference ignition necessity determination map of Example 3. FIG. It is a figure shown about the phase difference ignition necessity determination map of Example 4. FIG. It is a figure shown about the phase difference setting map of Example 5. FIG. It is a figure shown about the phase difference setting map of Example 6. FIG. It is a figure which shows the structure of Example 7 of the internal combustion engine which concerns on this invention. It is a figure shown about the phase difference setting map of Example 7. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 1st spark plug 13 2nd spark plug 14 Intake passage 16 Exhaust passage 19 Throttle valve 20 Throttle valve opening sensor 21 EGR passage 22 EGR valve 23 EGR valve actuator 24 EGR valve opening sensor 25 Crankshaft 26 Crank angle Sensor 27 Temperature sensor 30 Electronic control unit (ECU, engine ECU)
31 Simultaneous ignition timing setting means 32 Phase difference ignition necessity determination means 33 Phase difference setting means 34 Ignition execution means 51 Power split mechanism 53 Electric motor 81 Main ECU
82 Electric motor ECU
KL Engine load factor Ne Engine speed θ _EGR EGR valve opening θ _TH throttle opening

Claims (5)

Each combustion chamber includes at least one ignition plug at approximately the center and the peripheral wall side of the combustion chamber, and further includes an exhaust gas recirculation device that circulates exhaust gas discharged from the combustion chamber to the intake passage. In internal combustion engines,
Phase difference ignition necessity determination means for determining whether or not to add a phase difference to the ignition timing of each of the spark plugs according to the combustion state;
When it is necessary to add a phase difference, a phase difference setting means for setting the phase difference according to the combustion state;
Ignition execution means for igniting the ignition plug on the peripheral wall side of the combustion chamber with a phase difference set by the phase difference setting means delayed with respect to the ignition plug at the substantially center of the combustion chamber;
An internal combustion engine comprising:   The phase difference ignition necessity determining means is a combustion that performs simultaneous ignition based on any one of the EGR valve opening, throttle opening, engine load factor or EGR rate of the exhaust gas recirculation device and the engine speed. 2. The internal combustion engine according to claim 1, wherein the internal combustion engine is configured to discriminate between a state region and a combustion state region in which phase difference ignition is performed.   The internal combustion engine according to claim 2, wherein the EGR rate is obtained from an engine speed, an EGR valve opening degree, and an engine load factor.   4. The internal combustion engine according to claim 1, wherein the phase difference setting unit is configured to set the phase difference larger as the combustion state deteriorates.   The phase difference setting means is configured to set the phase difference according to any one of an engine speed, an EGR gas temperature, an EGR rate, or a torque fluctuation amount. , 3 or 4 Internal combustion engine.

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