JP2007107487A - Ignition control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition control device for an internal combustion engine capable of controlling an ignition timing so that required voltage for each spark plug is not too high when there are the plurality of spark plugs in one cylinder. <P>SOLUTION: The ignition control device is provided for the internal combustion engine having the plurality of spark plugs in one cylinder. It sets a phase difference between ignition timings for the plurality of spark plugs to be reduced at predetermined rates 201, 202, as the load of the internal combustion engine is higher when low to medium, and to be a value greater than a virtual value based on assumption that it is reduced at the same rate as the predetermined rate, as the load of the internal combustion engine is higher when high (51, 52, 53). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition control device for an internal combustion engine.

  An engine ignition device disclosed in Japanese Patent Laid-Open No. 3-117684 (Patent Document 1) includes a plurality of ignition gaps arranged at intervals around the circumference of a cylinder, and one of the plurality of ignition gaps. Phase setting means for setting a phase difference between the ignition timing of the reference ignition gap and the ignition timing of the other ignition gap, respectively, and the reference ignition gap Phase adjusting means for adjusting the phase difference in proportion to the ignition advance amount.

Japanese Patent Laid-Open No. 3-117684

  When there are a plurality of spark plugs in one cylinder, the temperature and A / F in the vicinity of the spark plugs may be different for each spark plug, so the required voltage when discharging in the spark plugs may be different. In order to effectively suppress the breakage of the spark plugs, it is necessary to control the ignition timing so that the required voltage of each spark plug does not become excessive.

  An object of the present invention is to provide an ignition control device for an internal combustion engine capable of controlling the ignition timing so that the required voltage of each spark plug does not become excessive when there are a plurality of spark plugs in one cylinder. It is.

  An ignition control apparatus for an internal combustion engine according to the present invention is an ignition control apparatus for an internal combustion engine having a plurality of spark plugs in one cylinder, and when the load of the internal combustion engine is low to medium, the load increases. It is assumed that the phase difference between the ignition timings of the plurality of spark plugs decreases at a predetermined rate, and decreases at the same rate as the predetermined rate as the load increases when the load of the internal combustion engine is high. It is characterized in that the phase difference is set to a value larger than the virtual value at the time.

  The ignition control device for an internal combustion engine according to the present invention is characterized in that when the load of the internal combustion engine is high, the phase difference is set so as to increase as the load increases.

  In the ignition control device for an internal combustion engine according to the present invention, when the load of the internal combustion engine is high, the phase difference is set to be substantially constant even when the load becomes high.

  In the ignition control device for an internal combustion engine according to the present invention, when the load of the internal combustion engine is high, the phase difference is set to decrease at a rate smaller than the predetermined rate as the load increases. It is characterized by that.

  In the ignition control apparatus for an internal combustion engine according to the present invention, when the load of the internal combustion engine is high, the phase difference is set to about 3 degrees or more even if the load becomes high.

  In the ignition control device for an internal combustion engine according to the present invention, when the load of the internal combustion engine is high, the phase difference is set to about 10 degrees or less even when the load increases.

  In the ignition control device for an internal combustion engine according to the present invention, when the load of the internal combustion engine is high, the phase difference is set to about 5 degrees or less even when the load increases.

  In the ignition control device for an internal combustion engine according to the present invention, when a load of the internal combustion engine is high, a required voltage of a spark plug that is positioned relatively laterally among the plurality of spark plugs is greater than or equal to a predetermined value that is set in advance. The phase difference is set so as not to occur.

  An ignition control device for an internal combustion engine according to the present invention is an ignition control device for an internal combustion engine having a plurality of spark plugs in one cylinder, wherein the plurality of spark plugs are controlled based on the stratification degree of the air-fuel mixture in the cylinder. It is characterized in that a phase difference of ignition timing is set.

  The ignition control device for an internal combustion engine according to the present invention is characterized in that the phase difference is set to be large when the stratification degree of the air-fuel mixture is high.

  In the ignition control device for an internal combustion engine according to the present invention, the internal combustion engine injects fuel into the intake pipe of the internal combustion engine with respect to the one cylinder, and directly injects fuel into the cylinder. The phase difference is set to be large when the ratio of injection by the second fuel injection valve is high.

  In the ignition control device for an internal combustion engine according to the present invention, the internal combustion engine injects fuel into the intake pipe of the internal combustion engine with respect to the one cylinder, and directly injects fuel into the cylinder. The phase difference is set to be large when the ratio of injection by the second fuel injection valve in the compression stroke is high.

  In the ignition control device for an internal combustion engine according to the present invention, the internal combustion engine injects fuel into the intake pipe of the internal combustion engine with respect to the one cylinder, and directly injects fuel into the cylinder. Only one of the second fuel injection valves is provided, and the air-fuel mixture is based on the fuel injection timing of either the first fuel injection valve or the second fuel injection valve provided in the internal combustion engine. When the degree of stratification is high, the phase difference is set to be large.

  According to the present invention, when there are a plurality of spark plugs in one cylinder, it is possible to control the ignition timing so that the required voltage of each spark plug does not become excessive.

  Hereinafter, an embodiment of an ignition control device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
A first embodiment of an ignition control device for an internal combustion engine will be described with reference to FIGS.

The present embodiment is an ignition control device for an internal combustion engine having a plurality of spark plugs in one cylinder,
When the load of the internal combustion engine is low to medium, the phase difference between the ignition timings of the plurality of spark plugs decreases at a predetermined rate as the load increases, and when the load of the internal combustion engine is high, The phase difference is set to a value larger than a hypothetical value when it is assumed that the load decreases with the same ratio as the predetermined ratio as the load increases.

That is, this embodiment is an internal combustion engine having a plurality of spark plugs in one cylinder, and sets different ignition timings for each of the plurality of spark plugs provided in one cylinder, and the load on the internal combustion engine increases. In the ignition control device for an internal combustion engine that tends to reduce the phase difference of the ignition timing, any of the following (1) to (3).
(1) When the load is high, the phase difference is increased as the load increases.
(2) When the load is high, the phase difference remains substantially constant and does not change even if the load increases.
(3) The ratio of reducing the phase difference at high load is made smaller than the ratio of reducing the phase difference as the load increases from low load to medium load.

  First, the concept for setting the ignition timing of a plurality of spark plugs provided in one cylinder will be described with reference to FIGS.

  As shown in FIG. 1A, in the internal combustion engine of the present embodiment, a plurality of spark plugs 21 and 22 are provided in one cylinder (combustion chamber) 11. A spark plug 21 is provided in the center of the cylinder 11, and a spark plug 22 is provided on the side of the cylinder 11. The internal combustion engine of the present embodiment is not limited to the configuration of FIG. 1-1, and may have the configurations of FIGS. 1-2 to 1-4.

  That is, the side spark plug 22 may be disposed between the intake valve 12 and the exhaust valve 13 as shown in FIG. 1-1, or between the two intake valves 12 as shown in FIG. But you can. Moreover, as shown in FIGS. 1-3 and FIGS. 1-4, the two side spark plugs 22 may be provided in one cylinder 11. As shown in FIG. When two side spark plugs 22 are provided in one cylinder 11, the operation and control method of the two side spark plugs 22 is basically one side ignition in one cylinder 11. This is the same as when the stopper 22 is provided.

  FIG. 2 is a diagram showing the relationship between the ignition timing (ignition timing phase difference) and the load when there are a plurality of spark plugs in one cylinder. As shown in the figure, the ignition timing 32 of the side ignition plug 22 is advanced compared to the ignition timing 31 of the central ignition plug 21. As described above, one of the purposes for setting the phase difference in the ignition timings of the plurality of spark plugs 21 and 22 provided in one cylinder is to end the combustion due to the difference in the installation positions of the spark plugs 21 and 22 in the cylinder 11. Is to correct the difference in the flame propagation distance necessary for the combustion and the difference in the combustion speed due to the difference in temperature and in-cylinder flow.

  The side ignition plug 22 has a larger flame propagation distance than the center ignition plug 21, and the temperature near the side ignition plug 22 is higher than the vicinity of the center ignition plug 21. Low. For these reasons, a difference in flame propagation distance and a difference in combustion speed occur between the center spark plug 21 and the side spark plug 22. In order to correct these differences, a phase difference is set between the ignition timing 31 of the central ignition plug 21 and the ignition timing 32 of the lateral ignition plug 22, so that the central ignition plug 21 and the lateral ignition plug 22 are set. The contribution of combustion is made substantially the same, thereby stabilizing combustion, improving efficiency, and reducing harmful components.

  In addition, when the load is low, the flame propagation speed is relatively slow because the temperature in the cylinder is lower than when the load is high. For this reason, when the combustion is to be terminated within a certain optimum crank angle, it is necessary to advance the ignition timing when the load is low compared to when the load is high. Therefore, as shown in FIG. 2, the ignition timings 31 and 32 of the central ignition plug 21 and the side ignition plug 22 are advanced when the load is low compared to when the load is high.

  Furthermore, since the combustion speed is relatively high at high loads, even if the phase difference between the ignition timing 31 of the central ignition plug 21 and the ignition timing 32 of the side ignition plug 22 is smaller than that at low load, The contribution of combustion of the center spark plug 21 and the side spark plug 22 is substantially the same. Therefore, the phase difference between the ignition timing 31 of the central ignition plug 21 and the ignition timing 32 of the side ignition plug 22 is set to be smaller at high loads than at low loads.

  As described above, the phase difference amount between the ignition timing 31 of the central ignition plug 21 and the ignition timing 32 of the side ignition plug 22 is proportional to the ignition timing advance amount (inversely proportional to the combustion speed based on the crank angle). Is set.

  Next, setting of the ignition timings 31a and 32a of the central ignition plug 21 and the side ignition plug 22 according to the present embodiment will be described with reference to FIG.

  In the present embodiment, further, from the above-mentioned purpose (correction of flame propagation distance difference or combustion speed difference correction), that is, from the problem of the required voltage (voltage resistance) of the plurality of spark plugs 21, 22, ignition is performed. A phase difference is set for the ignition timing of the plugs 21 and 22. When the air density in the cylinder (in-cylinder pressure) becomes high, it becomes difficult for sparks to fly from the spark plug, so that the required voltage when starting to discharge in the spark plug increases. The in-cylinder pressure increases when the ignition timing is retarded or during a high load. Further, when the air-fuel mixture A / F is lean, the required voltage of the spark plug increases. When the required voltage exceeds the limit, a failure occurs in the spark plug, so that it is required to suppress the required voltage so as not to exceed the limit value.

  Here, as a result of experiments by the present inventors, when the required voltage of the spark plug 21 at the center of the cylinder 11 and the required voltage of the spark plug 22 at the side are compared, the required voltage of the spark plug 22 at the side is higher. The experimental result that was high was obtained. The reason is that the temperature at the side is lower than that at the center of the cylinder 11 and that the A / F of the side air-fuel mixture is leaner than that at the center of the cylinder 11. The required voltage of the side ignition plug 22 is considered to be higher than that of the central ignition plug 21.

  Therefore, in this embodiment, as shown in FIG. 3, in order to lower the required voltage of the side spark plug 22, ignition should be performed in a state where the air density in the cylinder is relatively low (piston position is low). The ignition timing 32a of the side ignition plug 22 is advanced. On the other hand, since the required voltage of the central ignition plug 21 is not as severe as that of the side ignition plug 22, it is ignited after ignition of the side ignition plug 22 (a phase difference is set in the ignition timing). In the present embodiment, instead of aiming to make the contribution of combustion in the center spark plug 21 and the side spark plug 22 the same, as a result, the contribution of the side spark plug 22 is relative. Therefore, the problem of the required voltage of the side spark plug 22 will be solved. Thereby, damage to the side spark plug 22 is effectively suppressed.

  As described above, it is necessary to advance the ignition timing 32a so that the required voltage of the side spark plug 22 does not increase. Here, since the required voltage of the spark plug becomes more severe as the air density in the cylinder becomes higher, the required voltage of the side spark plug 22 increases correspondingly, especially when the load is high, and there is a problem with voltage resistance. More likely to occur. In addition, when the load is high, the mixture formation may become uneven due to an increase in the absolute amount of injected fuel and an increase in pressure. In this case, the required voltage of the spark plug 22 that becomes the lean portion increases. There is a case. For these reasons, in particular, when the load is higher than the load indicated by the symbol P1 in FIG. 3, for example, the advance of the ignition timing 32a is prevented so that the required voltage of the side spark plug 22 does not become higher than a predetermined value. Set the angular amount. When the air-fuel mixture formation becomes non-uniform at high load, the required voltage of the central spark plug 21 that is a rich portion decreases. Therefore, when the load is higher than the load indicated by the symbol P1 in FIG. It becomes possible to relatively retard 31a.

  In the example of FIG. 3, when the load is high, the phase difference between the ignition timing 31 a and the ignition timing 32 a is increased as the load increases. However, the present embodiment is not limited to this tendency. In other words, in the present embodiment, at the high load, at the center of the spark plug as the load increases at least from the low load to the medium load, the required voltage of the side spark plug 22 does not exceed a predetermined value. Compared to the ratio of reducing the phase difference between the ignition timing 31a of 21 and the ignition timing 32a of the side spark plug 22, the ratio of reducing the phase difference as the load increases at a high load is reduced. From this, regarding the setting of the phase difference between the ignition timing 32a of the side ignition plug 22 and the ignition timing 31a of the central ignition plug 21 at the time of high load, any one of the above aspects (1) to (3) To do.

  Next, the embodiment will be described in more detail with reference to FIGS.

  FIG. 4 shows an example of the relationship between the absolute value of the ignition timing and the load when there is only one spark plug at the center of the cylinder. As described above with reference to FIG. 2, the combustion in the cylinder is completed at a certain optimum crank angle because the temperature in the cylinder is lower and the flame propagation speed is relatively slower at low load than at high load. In order to achieve this, it is necessary to advance the ignition timing when the load is low compared to when the load is high. Therefore, as shown in FIG. 4, the ignition timing 101 of the spark plug is advanced when the load is low compared to when the load is high. In the example of FIG. 4, the ignition timing 101 is about 36 deg when the load (surge tank pressure) is about 20 kPa, and about 3 deg when the load is 200 kPa.

  FIG. 5 shows the relationship between the ignition timing phase difference and the load when there are two spark plugs in one cylinder. Normally, when there are two spark plugs, the combustion speed increases when there are only two spark plugs, so the absolute value of the ignition timing is a relatively small value. In general, when there are two spark plugs in one cylinder, the phase difference between the two ignition timings is a value of about 1/3 to 1/10 of the advance side ignition timing absolute value as shown in FIG. It becomes.

  In the 1/3 line (reference numeral 201) where the phase difference is maximum, when the load is about 20 kPa, the phase difference is about 12 deg, and the ignition timing of the side spark plug, which is the absolute value of the advance side ignition timing, is Since it is about 36 deg (FIG. 4), the ignition timing of the center spark plug is about 24 deg. On the other hand, in the 1/10 line (reference numeral 202) where the phase difference is minimum, when the load is about 20 kPa, the phase difference is about 4 deg, and the ignition timing of the side spark plug is about 36 deg (FIG. 4). Therefore, the ignition timing of the center spark plug is about 32 deg. As described above with reference to FIG. 2, also in FIG. 5, the phase difference between the ignition timings of the two spark plugs becomes smaller as the load becomes higher.

  As a result of experiments conducted by the present inventors under a certain condition, the side ignition plug has a higher required voltage of about 1 to 2 kV on the high load side where the required voltage becomes the strictest than the central ignition plug. was gotten. For example, if the required voltage value is lowered by about 1 to 2 kV only by adjusting the ignition timing, it is necessary to advance the angle by 5 to 10 degrees. However, if the ignition timing of the side spark plug is relatively advanced and the ignition timing of the central spark plug is relatively retarded to widen the phase difference to 10 degrees, the reaction (as a whole, the combustion will be slowed down). There is a possibility that the combustion stability deteriorates due to the above, the exhaust temperature rises, etc.). Therefore, there is a possibility that the phase difference up to 10 deg may not be actually set. In this sense, the phase difference is preferably 5 deg at the maximum. However, since the above-mentioned contradiction is only a problem caused by conforming specifications, it is possible to set the phase difference up to 10 degrees depending on the conditions of the internal combustion engine.

  FIG. 6 is a graph showing the results of experiments by the present inventors. FIG. 6 shows a case where the required voltage of the side spark plug is about 2 kV higher than the required voltage of the center spark plug on the high load side where the required voltage is the strictest. In FIG. 6, the meanings of the 1/3 line 201 and the 1/10 line 202 are as described with reference to FIG.

  In FIG. 6, reference numeral 111 indicates a limit line when a spark plug having a low withstand voltage is used, and reference numeral 112 indicates a limit line when a spark plug having a high withstand voltage is used. In this experiment, the withstand voltage of the spark plug having a low withstand voltage is about 20 kV, and the withstand voltage of the spark plug having a high withstand voltage is about 32 kV. When a spark plug having a high withstand voltage is used, the required voltage of the side spark plug does not become a problem even if the phase difference is small at the time of high load.

  As a result of the experiment of FIG. 6, the smallest phase difference amount is the intersection of the 1/10 line 202 and the limit line 112 when a spark plug having a high withstand voltage is used, which is about 3 degrees. In the second pattern 52 in the relationship between the load and the phase difference, which will be described later, the phase difference remains 3 deg and does not change even when the load becomes high at high loads.

  On the other hand, the most necessary phase difference amount is the rightmost point (10 deg) on the limit line 112 when a spark plug having a high withstand voltage is used. The numerical value of 10 deg on the right end on the limit line 112 when using a spark plug having a high withstand voltage shown in FIG. 6 is necessary when the required voltage value is lowered by about 2 kV just by adjusting the ignition timing. Technically similar to the advance amount of 10 deg.

  In the graph of FIG. 6, the limit line 112 when the spark plug having a high withstand voltage is used can be replaced with the limit line when the required voltage required by the engine is low, and the spark plug having a low withstand voltage is used. In this case, the limit line 111 can be replaced with a limit line when the required voltage required by the engine is high. Here, the case where the required voltage required by the engine is low is a case where the compression ratio of the engine is low or the A / F is rich, and the case where the required voltage required by the engine is high is that the engine is compressed. This is the case when the ratio is high or the A / F is lean.

  From the above, in the present embodiment, the phase difference of the ignition timing is set to 3 deg or more on the high load side (refer to the shaded area C in FIG. 6). Further, the upper limit value of the phase difference of the ignition timing is set to 10 deg (refer to the shaded area C in FIG. 6). That is, in this embodiment, it was found that the ignition timing phase difference should be set within the shaded area c in FIG.

  Here, the upper limit value of the phase difference of the ignition timing is preferably 5 deg. As described above, if the phase difference of the ignition timing is further increased, combustion stability is deteriorated due to slow combustion as a whole, exhaust temperature is increased, and the like.

  Further, the phase difference of the ignition timing is generally set to become smaller at a predetermined proportional ratio (a value between the 1/3 line 201 to the 1/10 line 202) as the load becomes higher (from the low load to the middle). When the load is high, the advance amount of the side ignition timing is set relatively large so that the required voltage of the side spark plug does not become higher than a predetermined value. The phase difference is set to be larger than the proportional ratio so far (see FIGS. 6 and 3).

  That is, as the load increases from the low load to the medium load side, for example, when the phase difference decreases due to the inclination of the 1/3 line 201, a value larger than 1/3 on the high load side ( For example, the phase difference changes with an inclination of 1/2). That is, on the high load side, the phase difference is set to a value larger than the virtual value when it is assumed that the phase difference has decreased along the 1/3 line 201. Similarly, as the load increases from the low load side to the medium load side, for example, when the phase difference decreases with the inclination of the 1/10 line 202, the high load side is larger than 1/10. The phase difference changes with the slope of the value (for example, 1/5). That is, on the high load side, the phase difference is set to a value larger than the virtual value when it is assumed that the phase difference has decreased along the 1/10 line 202.

  As shown in FIG. 6, the following three patterns can be considered as the relationship between the ignition timing phase difference and the load. Hereinafter, a case where the limit line 112 in the case where a spark plug having a high withstand voltage is used will be described as an example.

  First, as indicated by reference numeral 51, in the first pattern, the phase difference decreases as the load increases until it reaches the limit line 112 when a spark plug having a high withstand voltage is used. After hitting the pattern, the phase difference increases as the load increases. Note that the pattern indicated by reference numeral 51 is set to rise to the right along the limit line 112 after hitting the limit line 112.

  Next, in the second pattern, as indicated by reference numeral 52, the phase difference decreases as the load increases. After hitting the limit line 112, the phase difference does not change even when the load increases. It is a pattern. Finally, as indicated by reference numeral 53, in the third pattern, the phase difference decreases with a predetermined inclination as the load increases. After hitting the limit line 112, the third pattern is larger than the predetermined inclination until then. Is a pattern in which the phase difference decreases with a small inclination.

  The above (1) relating to the setting of the phase difference between the ignition timing 32a of the side ignition plug 22 at the time of high load and the ignition timing 31a of the central ignition plug 21 is the first pattern (the load at the time of high load). The phase difference is increased as the value increases. Similarly, the above (2) corresponds to the second pattern (when the load is high, the phase difference remains substantially constant even when the load increases). Similarly, the above (3) reduces the ratio of reducing the phase difference at high load as compared to the third pattern (the ratio of reducing the phase difference as the load increases from low load to medium load). ).

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG.
In the present embodiment, the description of the parts common to the first embodiment is omitted, and only the characteristic parts of the second embodiment will be described.

  In this embodiment, two cylinders, a fuel injection valve (port injection valve) for injecting fuel into the intake pipe and a fuel injection valve (direct injection injection valve) for direct injection into the cylinder, are provided for one cylinder. It can be applied to internal combustion engines.

  In the present embodiment, in the case of performing double injection by intake process injection + compression process injection or double injection by port injection + direct injection compression process injection in a direct injection engine, the ratio of direct injection compression process injection is increased. As a result, the ratio of the stratified mixture increases, and the A / F near the center spark plug 21 becomes richer, while the A / F near the side spark plug 22 becomes leaner. As a result, the difference in required voltage between the central spark plug 21 and the side spark plug 22 is further increased, and the required voltage of the side spark plug 22 becomes more severe.

  Therefore, as the stratification degree of the air-fuel mixture increases, the phase difference between the ignition timings of the central ignition plug 21 and the side ignition plug 22 is increased in order to advance the ignition timing of the side ignition plug 22 more greatly. Enlarge. That is, as shown in FIG. 7, when the ratio of the direct injection compression process injection is increased and the stratification degree of the air-fuel mixture is positively increased (shaded), the central spark plug 21 is accordingly increased. And the phase difference amount 61 of the ignition timing of the side spark plug 22 is increased. As a result, the ignition timing of the side ignition plug 22 is further advanced, and the side ignition plug 22 is ignited in a state where the air density in the cylinder is low, thereby reducing the required voltage of the side ignition plug 22. It becomes possible. Therefore, it is possible to solve the problem of withstand voltage of the side spark plug 22.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG.
In the present embodiment, the description of the parts common to the above embodiment is omitted, and only the characteristic part of the third embodiment will be described.

  The present embodiment is applicable to an internal combustion engine in which only a port injection valve is provided for one cylinder, or an internal combustion engine in which only a direct injection valve is provided.

  In this embodiment, the phase difference between the ignition timings of the central ignition plug 21 and the side ignition plug 22 is changed according to the injection timing. When the injection timing of the port injection valve is intake-synchronized (injection when the intake valve is open), the mixture is highly stratified and is asynchronous (injection when the intake valve is closed) The stratification degree of the air-fuel mixture is low. Further, in the direct injection engine, when the injection timing of the intake stroke injection is on the piston top dead center side, the stratification degree of the air-fuel mixture is higher than that on the bottom dead center side. Further, in the direct injection engine, when the injection timing of the compression process injection is on the top dead center side, the stratification degree of the air-fuel mixture is lower than that on the bottom dead center side.

  When the degree of stratification of the air-fuel mixture increases, the A / F near the center spark plug 21 becomes richer, while the A / F near the side spark plug 22 becomes leaner. As a result, the difference in required voltage between the central spark plug 21 and the side spark plug 22 is further increased, and the required voltage of the side spark plug 22 becomes more severe. Therefore, as the stratification degree of the air-fuel mixture increases, the phase difference between the ignition timings of the central ignition plug 21 and the side ignition plug 22 is increased in order to advance the ignition timing of the side ignition plug 22 more greatly. Enlarge.

  In the present embodiment, as described above, the stratification degree of the air-fuel mixture changes according to the injection timing. Therefore, when the injection timing is changed to a higher stratification degree, that is, the injection timing of the port injection valve is asynchronous with intake air. Is changed from the side to the intake synchronous side, or the injection timing of the intake stroke injection is changed from the bottom dead center side to the top dead center side in the direct injection engine, or the compression stroke injection is injected in the direct injection engine When the timing is changed from the top dead center side to the bottom dead center side, the phase difference amount 62 between the ignition timings of the central ignition plug 21 and the side ignition plug 22 is increased accordingly.

  As a result, the ignition timing of the side ignition plug 22 is further advanced, and the side ignition plug 22 is ignited in a state where the air density in the cylinder is low, thereby reducing the required voltage of the side ignition plug 22. It becomes possible. Therefore, it is possible to solve the problem of withstand voltage of the side spark plug 22.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG.
In the present embodiment, description of parts common to the above embodiment will be omitted, and only characteristic parts of the fourth embodiment will be described.

  The present embodiment is applicable to an internal combustion engine in which two ports, a port injection valve and a direct injection valve, are provided for one cylinder.

  In the case of in-cylinder injection from the direct injection valve, the degree of stratification of the air-fuel mixture is high regardless of the injection timing, compared to the case of injection from the port injection valve. That is, not only when the compression process injection is performed from the direct injection valve, but also when the intake process injection is performed, especially when the injection is performed on the bottom dead center side, the stratification degree of the air-fuel mixture is high. .

  When the degree of stratification of the air-fuel mixture increases, the A / F near the center spark plug 21 becomes richer, while the A / F near the side spark plug 22 becomes leaner. As a result, the difference in required voltage between the central spark plug 21 and the side spark plug 22 is further increased, and the required voltage of the side spark plug 22 becomes more severe. Therefore, as the stratification degree of the air-fuel mixture increases, the phase difference between the ignition timings of the central ignition plug 21 and the side ignition plug 22 is increased in order to advance the ignition timing of the side ignition plug 22 more greatly. Enlarge.

  In the present embodiment, as described above, when the injection ratio from the direct injection valve increases, the stratification degree of the air-fuel mixture increases, and accordingly, the center ignition plug 21 and the side ignition plug 22 The ignition timing phase difference amount 63 is increased. As a result, the ignition timing of the side ignition plug 22 is further advanced, and the side ignition plug 22 is ignited in a state where the air density in the cylinder is low, thereby reducing the required voltage of the side ignition plug 22. It becomes possible. Therefore, it is possible to solve the problem of withstand voltage of the side spark plug 22.

  As described above, in the second to fourth embodiments, as shown in FIG. 10, the center spark plug 21 and the side spark plugs 22 are finally arranged according to the stratification degree of the air-fuel mixture as shown in FIG. This is common in that the problem of the voltage resistance of the side spark plug 22 is solved by changing the phase difference amount of the ignition timing. Here, when determining the stratification degree of the air-fuel mixture, it may be determined based on contents other than those described in the second to fourth embodiments.

(Fifth embodiment)
Next, with reference to FIG. 11, the setting of the ignition timing of the center spark plug 21 and the side spark plug 22 of the present embodiment will be described. Note that in the fifth embodiment, description of parts common to the above embodiment will be omitted.

  When there are a plurality of spark plugs in one cylinder, it is desired from the viewpoint of stabilization of combustion, efficiency improvement, and the like that the contribution of combustion by each spark plug is substantially the same. Therefore, it is hoped that the phase difference between the ignition timings of the plurality of spark plugs of the cylinders is set to a more optimal value by taking into consideration factors other than the ignition advance amount disclosed in Patent Document 1 above. It is rare.

  An object of the present embodiment is to provide an ignition control device for an internal combustion engine that can set a phase difference between ignition timings of a plurality of spark plugs to a more optimal value when there are a plurality of spark plugs in one cylinder. That is.

  As described above with reference to FIG. 2, the phase difference amount between the ignition timing 31 of the central spark plug 21 and the ignition timing 32 of the side ignition timing 22 is set in proportion to the ignition timing advance amount.

  In the present embodiment, the phase difference 31 between the ignition timings of the central ignition plug 21 and the side ignition plug 22 is further reduced in accordance with factors (EGR amount, engine cooling water temperature, engine load, etc.) that reduce the combustion speed. Set. The greater the EGR amount entering the cylinder 11, the slower the combustion speed, and the smaller the EGR amount, the faster the combustion speed. Further, the lower the engine water temperature, the slower the combustion speed, and the higher the engine water temperature, the faster the combustion speed. Also, the lower the engine load, the slower the combustion speed, and the higher the engine load, the faster the combustion speed.

  For this reason, in this embodiment, the greater the factors that slow the combustion speed, such as the EGR amount, the engine coolant temperature, and the engine load, the greater the phase difference 31 between the ignition timings of the central ignition plug 21 and the side ignition plug 22. On the contrary, the phase difference 31 is reduced as the factor that slows down the combustion speed is set to a larger value. Thus, the difference in combustion speed between the combustion by the center spark plug 21 and the combustion by the side spark plug 22 is corrected, and the contribution of combustion between the center spark plug 21 and the side spark plug 22 is substantially increased. Can be the same.

In addition, the following [1] to [3] can be cited as factors that change the combustion rate (variable controllable ones). In the present embodiment, similarly to the above, the phase difference 31 between the ignition timings of the central ignition plug 21 and the side ignition plug 22 is set according to the following factors that slow the combustion rate.
[1] Chemical reactivity, AF ... Injection quantity / Quality of air-fuel mixture ... Homogeneity (injection timing, fuel pressure)
・ EGR amount: Internal EGR, external EGR (back pressure, valve timing overlap amount)
・ Ignition properties: Ignition energy
[2] In-cylinder flow velocity / intake turbulence: tumble flow, swirl flow (intake control valve)
・ Intake turbulence: Disturbance caused by fuel spray (fuel pressure and injection timing of direct injection injector)
・ Intake turbulence ... Intake flow behavior (valve timing, lift, etc.)
[3] Temperature-related air / air mixture: Intake air temperature / air mixture: EGR gas volume (back pressure, valve timing)
・ Air-fuel mixture: Actual compression ratio (valve timing)
・ Wall temperature: Water temperature, oil temperature, presence of oil jet

  Further, for example, depending on the type of the internal combustion engine, among a plurality of cylinders, it can be divided into a cylinder into which a relatively large EGR amount enters and a cylinder into which a relatively small amount enters. In this case, the cylinder having a relatively large EGR amount and a slow combustion rate has a phase difference 31 between the ignition timings of the central ignition plug 21 and the side ignition plug 22 as compared with a cylinder having a relatively small EGR amount and a high combustion speed. Set to a large value. In FIG. 11, reference numeral 31 a indicates the phase difference between the ignition timings of the plurality of spark plugs 21, 31 in the cylinder having the fastest combustion speed among the plurality of cylinders of the internal combustion engine, and reference numeral 31 b indicates the plurality of internal combustion engine pluralities. The phase difference of the ignition timings of the plurality of spark plugs 21 and 31 in the cylinder having the slowest combustion speed among the cylinders is shown.

(Sixth embodiment)
Next, a sixth embodiment will be described with reference to FIGS. Note that in the sixth embodiment, a description of portions common to the above embodiment will be omitted.

  The purpose of this embodiment is to set the phase difference between the ignition timings of the plurality of spark plugs to a more optimal value when there are a plurality of spark plugs in one cylinder, as in the fifth embodiment. An ignition control device for an internal combustion engine is provided.

  In the plurality of spark plugs 21, 22 in the cylinder 11, an ignition timing correction amount is set for each of the plurality of spark plugs 21, 22. That is, each of the central spark plug 21 and the side spark plug 22 has a separate ignition map. FIG. 12 shows the relationship between the factor that affects the combustion speed and the correction amount 41 of the ignition timing of the central ignition plug 21 and the correction amount 42 of the ignition timing of the side ignition plug 22. Since the central spark plug 21 and the side spark plug 22 have different sensitivities (influences) with respect to factors that affect the combustion speed, the central spark plug 21 and the side spark plugs 22 according to the degree of influence. The ignition timing correction amount is determined.

  Here, the factors that affect the combustion rate include a factor that lowers the combustion rate and a factor that increases the combustion rate. Examples of factors that lower the combustion rate are as described in the fifth embodiment, and examples of factors that increase the combustion rate include air temperature (intake air temperature). The higher the intake air temperature, the higher the combustion speed, and the lower the intake air temperature, the slower the combustion speed.

  In the example shown in FIG. 12, the correction amount 41 of the ignition timing of the central spark plug 21 is shown as a larger value than the correction amount 42 of the ignition timing of the side spark plug 22. On the contrary, depending on what factors affect the combustion speed, the correction amount of the ignition timing of the central spark plug 21 is smaller than the correction amount of the ignition timing of the side spark plug 22. There is also.

  Depending on factors that affect the combustion speed, the necessity for correcting the ignition timing may differ for each spark plug 21, 22. For example, as the factor that slows down the combustion rate increases, both of the spark plugs 21 and 22 are common in that it is necessary to increase the correction amount of the ignition timing. There may be a difference in the degree of necessity of increasing the amount (how much the correction amount should be increased). Therefore, as shown in FIG. 12, the correction amount of the ignition timing is individually set for each spark plug 21, 22.

  As described above, depending on factors that affect the combustion speed, there may be a difference in the degree of necessity of the ignition timing correction amount for each of the spark plugs 21, 22. A map shown in FIG. 12 is prepared in order to set the correction amount of the ignition timing for each of the spark plugs 21 and 22 in consideration of the degree of influence. Instead of the map of FIG. 12, the map of FIG. 13 in which the phase difference amount of the ignition timing of other spark plugs with respect to the ignition timing of the reference spark plug can be used. That is, FIG. 13 shows the relationship between the factor that affects the combustion speed and the phase difference amount 43 of the ignition timing of the reference spark plug 21 and the other spark plugs 22 among the plurality of spark plugs 21 and 22.

  FIG. 14 shows an example in which the ignition timing correction amount is set for each of the plurality of spark plugs in the plurality of spark plugs in the cylinder in accordance with the degree of influence on the factor that slows the combustion speed.

  Of the plurality of spark plugs, the ignition timing correction amount (advance amount) 44 of the ignition plug on the slow combustion speed side is set to be larger than the ignition timing correction amount 45 of the ignition plug on the fast combustion speed side. The slope of each of the ignition timing correction amount 44 of the ignition plug on the slow combustion speed side and the ignition timing correction amount 45 of the ignition plug on the high combustion speed side indicates the sensitivity (degree of influence) to the factor that slows the combustion speed. Each is set accordingly. Thereby, the contribution to the combustion of each of the plurality of spark plugs is made substantially the same.

  For example, in general, among the plurality of spark plugs, spark plugs disposed in the vicinity of the bore have a relatively slow combustion rate. Similarly, among the plurality of spark plugs, the combustion speed of the spark plug on the side where the in-cylinder flow rate is small or the spark plug on the side where EGR is excessive is relatively slow. Therefore, as shown in FIG. 14, the correction amount of the ignition timing of the ignition plug on the slow combustion speed side is made larger than the correction amount of the ignition timing of the ignition plug on the high combustion speed side.

  Depending on the position of the spark plug with respect to the bore, the spark plug may be disposed at a position where the combustion speed must be slow. For example, in the case of two spark plugs arranged at positions other than the center, a difference in in-cylinder flow speed, a difference in EGR amount, and a temperature difference may occur even when the spark plugs are arranged at left and right symmetrical positions. . In this case, the correction amount of the ignition timing of the ignition plug on the slow combustion speed side is set large.

  In addition, said each embodiment can be combined suitably.

1 is a schematic configuration diagram showing a cylinder and a spark plug of an internal combustion engine to which a first embodiment of an ignition control device for an internal combustion engine of the present invention is applied. It is a schematic block diagram which shows the cylinder and spark plug of another internal combustion engine to which 1st Embodiment of the ignition control apparatus of the internal combustion engine of this invention is applied. It is a schematic block diagram which shows the cylinder and ignition plug of another internal combustion engine to which 1st Embodiment of the ignition control apparatus of the internal combustion engine of this invention is applied. It is a schematic block diagram which shows the cylinder and ignition plug of another internal combustion engine to which 1st Embodiment of the ignition control apparatus of the internal combustion engine of this invention is applied. It is a figure for demonstrating the relationship between the load and ignition timing of 1st Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is another figure for demonstrating the relationship between the load and ignition timing of 1st Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is another figure for demonstrating the relationship between the load and ignition timing of the ignition control apparatus of the conventional general internal combustion engine. It is a figure for demonstrating the relationship between the load and phase difference ignition timing of 1st Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is another figure for demonstrating the relationship between the load and phase difference ignition timing of 1st Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the relationship between the compression stroke injection ratio and phase difference ignition timing of 2nd Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the relationship between the injection timing and phase difference ignition timing of 3rd Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the relationship between the injection ratio of direct injection and phase difference ignition timing of 4th Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the relationship between the stratification degree of an air-fuel | gaseous mixture and phase difference ignition timing of the ignition control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the relationship between the factor which makes the combustion speed slow, and phase difference ignition timing of 5th Embodiment of the ignition control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the relationship between the factor which affects the combustion rate of 6th Embodiment of the ignition control apparatus of the internal combustion engine of this invention, and ignition timing. It is another figure for demonstrating the relationship between the factor which influences the combustion speed of 6th Embodiment of the ignition control apparatus of the internal combustion engine of this invention, and phase difference ignition timing. It is a figure for demonstrating the relationship between the factor which makes the combustion speed slow, and the ignition timing of 6th Embodiment of the ignition control apparatus of the internal combustion engine of this invention.

Explanation of symbols

11 cylinders (combustion chamber)
21 ignition plug 31 lateral ignition plug 31 ignition timing 31a ignition timing 32 ignition timing 32b ignition timing 41 ignition timing correction amount 42 ignition timing correction amount 43 phase difference amount 44 ignition timing correction amount 45 ignition timing correction amount 51 1st Pattern 52 Second pattern 53 Third pattern 61 Phase difference amount 62 Phase difference amount 63 Phase difference amount 64 Phase difference amount 111 Limit line when using a spark plug having a low withstand voltage 112 Using a spark plug having a high withstand voltage Limit line 201 1/3 line 202 1/10 line

Claims (13)

An ignition control device for an internal combustion engine having a plurality of spark plugs in one cylinder,
When the load of the internal combustion engine is low to medium, the phase difference between the ignition timings of the plurality of spark plugs decreases at a predetermined rate as the load increases, and when the load of the internal combustion engine is high, The ignition control device for an internal combustion engine, characterized in that the phase difference is set to a value larger than a hypothetical value when it is assumed that the load decreases with the same rate as the predetermined rate as the load increases. The ignition control device for an internal combustion engine according to claim 1,
An internal combustion engine ignition control device, wherein the phase difference is set to increase as the load increases when the load of the internal combustion engine is high. The ignition control device for an internal combustion engine according to claim 1,
An ignition control device for an internal combustion engine, wherein the phase difference is set to be substantially constant even when the load of the internal combustion engine is high even when the load is high. The ignition control device for an internal combustion engine according to claim 1,
The internal combustion engine ignition control device, wherein the phase difference is set to decrease at a rate smaller than the predetermined rate as the load increases when the load of the internal combustion engine is high. . The ignition control device for an internal combustion engine according to any one of claims 1 to 4,
The ignition control device for an internal combustion engine, wherein when the load of the internal combustion engine is high, the phase difference is set to about 3 degrees or more even when the load becomes high. The ignition control device for an internal combustion engine according to any one of claims 1 to 5,
The ignition control device for an internal combustion engine, wherein the phase difference is set to about 10 degrees or less even when the load of the internal combustion engine is high. The ignition control device for an internal combustion engine according to any one of claims 1 to 5,
The ignition control device for an internal combustion engine, wherein when the load of the internal combustion engine is high, the phase difference is set to about 5 degrees or less even if the load becomes high. The ignition control device for an internal combustion engine according to any one of claims 1 to 7,
When the load of the internal combustion engine is high, the phase difference is set so that a required voltage of a spark plug that is located relatively laterally among the plurality of spark plugs does not exceed a preset predetermined value. An ignition control device for an internal combustion engine. An ignition control device for an internal combustion engine having a plurality of spark plugs in one cylinder,
An ignition control device for an internal combustion engine, wherein a phase difference between ignition timings of the plurality of spark plugs is set based on a degree of stratification of the air-fuel mixture in the cylinder. In the internal combustion engine ignition control device according to claim 9,
The ignition control device for an internal combustion engine, wherein the phase difference is set to be large when the stratification degree of the air-fuel mixture is high. The ignition control device for an internal combustion engine according to claim 9 or 10,
The internal combustion engine includes a first fuel injection valve that injects fuel into the intake pipe of the internal combustion engine for the one cylinder, and a second fuel injection valve that directly injects fuel into the cylinder.
The ignition control device for an internal combustion engine, wherein the phase difference is set to be large when a ratio of injection by the second fuel injection valve is high. The ignition control device for an internal combustion engine according to claim 9 or 10,
The internal combustion engine includes a first fuel injection valve that injects fuel into the intake pipe of the internal combustion engine for the one cylinder, and a second fuel injection valve that directly injects fuel into the cylinder.
An ignition control device for an internal combustion engine, wherein the phase difference is set to be large when a ratio of injection by the second fuel injection valve in a compression stroke is high. The ignition control device for an internal combustion engine according to claim 9 or 10,
The internal combustion engine has only one of a first fuel injection valve that injects fuel into the intake pipe of the internal combustion engine and a second fuel injection valve that directly injects fuel into the cylinder. When the stratification degree of the air-fuel mixture is high based on the fuel injection timing of one of the first fuel injection valve and the second fuel injection valve provided in the internal combustion engine, the phase difference is An ignition control device for an internal combustion engine, wherein the ignition control device is set to be large.

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