JP4460135B2 - Ignition system and ignition method for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ignition system and an ignition method for an internal combustion engine used for operation in a lean or stratified intake state.
[0002]
[Prior art]
In recent years, with the in-cylinder injection gasoline engine and the like being put into practical use, in the ignition system of an internal combustion engine, for example, in stratified combustion, the duration of the induced current by the ignition coil during spark discharge is set longer. As a result, reliable ignition is possible, and stratified combustion according to all operating conditions is possible.
[0003]
For this reason, in operating conditions such as stratified combustion and lean conditions, it is necessary to set a longer duration of the induced current by the ignition coil during spark discharge, so it is necessary to store a large amount of discharge energy in the secondary coil of the ignition coil. Is done. Specifically, in order to increase the inductance of the secondary coil, a configuration is adopted in which the number of turns of the coil is increased.
[0004]
Further, for example, a configuration in which the ignition coil itself is made smaller by constructing the ignition device by a capacity discharge method using a capacitor, such as “ignition device for internal combustion engine” disclosed in Japanese Patent Laid-Open No. 3-13430, is also considered. It is done.
[0005]
[Problems to be solved by the invention]
However, if the configuration in which the number of turns of the secondary coil is increased, the size of the ignition coil is increased, so that the volume occupied in the engine room by the ignition coil increases, and other devices and the like accompanying the internal combustion engine are arranged. The problem of making it difficult arises.
[0006]
In addition, in the case where the ignition device is configured by a capacity discharge type using a capacitor, it is necessary to reduce the mutual induction coefficient in order to reduce the size of the ignition coil, and as a result, a semiconductor type DC-DC is provided in front of the booster coil. It is necessary to adopt a configuration in which a converter is provided and the voltage is once increased to a moderate high voltage. Therefore, (1) providing a DC-DC converter, (2) using a thyristor as a switching means for the primary coil, and (3) using two thyristors to perform multiple discharges, respectively. Necessary. That is, there arises a new problem that the number of parts constituting the ignition device is increased.
[0007]
Furthermore, in recent ignition systems for internal combustion engines, there is a tendency for each ignition plug to have an ignition coil having an elongated cylindrical shape that can be accommodated in a plug hole formed in the engine block of the internal combustion engine. For this reason, there is a problem that it is difficult to meet the market needs for a stick type having a small outer diameter as an ignition coil.
[0008]
The present invention has been made in order to solve the above-described problems, and the object of the present invention is to increase the size of the ignition coil without increasing the size of the ignition coil under the operating condition of the internal combustion engine in a lean or stratified intake state. An ignition system and an ignition method for an internal combustion engine capable of improving ignitability.
[0009]
[Means for solving the problems].Action and effect of invention]
  In order to achieve the above object, an ignition system for an internal combustion engine according to claim 1,
  Layered intake stateIn the internal combustion engine ignition system used for operation by
  A spark plug attached to a cylinder of the internal combustion engine;
  An ignition coil for supplying a spark discharge voltage to the spark plug;
  Switching means connected in series to a primary coil of the ignition coil and energizing or interrupting a primary current energized to the primary coil by a control signal;
  Ignition control means for providing the control signal to the switching means;
An internal combustion engine ignition system comprising:
  The ignition control means provides a first control signal to the switching means to generate the spark discharge voltage in the secondary coil of the ignition coil, and after a predetermined time has elapsed, a second control signal is sent to the switching means. The primary current is turned on and off a plurality of times, and the spark discharge voltage is intermittently generated in the secondary coil.,
The switching means is repeatedly energized and interrupted by the second control signal, when the spark plug spark duration is 0.7 mSec. Or more and 1.3 mSec. Or less as measured by the American Automobile Engineering Association standard SAEJ973. The ratio of the energization time to one cycle by energization and shutoff is 30% or more and 70% or less, and the shutoff time is 200 μSec. Or less.Is a technical feature.
[0010]
Further, in the ignition system for an internal combustion engine according to claim 2, in claim 1,
A technical feature is that the number of repetitions of energization and interruption of the primary current by the second control signal is arbitrarily set according to operating conditions of the internal combustion engine.
[0012]
  To achieve the above objective,Claim 3In the internal combustion engine ignition method,
  Layered intake stateIn the ignition method of the internal combustion engine used for operation by
  A second spark required for spark discharge of the spark plug after a predetermined time has elapsed after the first spark discharge voltage required for spark discharge of the spark plug attached to the internal combustion engine is applied from the ignition coil to the spark plug. A discharge voltage is intermittently repeated several times from the ignition coil and applied to the spark plug.When,
  When the second spark discharge voltage is applied to the ignition plug, the energization and the interruption are measured according to American Automobile Engineers Association Standard SAEJ973, and the spark plug has a spark duration of 0.7 mSec. Or more and 1.3 mSec. Or less. Under the conditions, the ratio of the energization time to one cycle by energization and interruption is 30% or more and 70% or less, and the interruption time is 200 μSec. Or less.Is a technical feature.
[0013]
  In the first aspect of the invention, the ignition control means switches the second control signal after a predetermined time has elapsed after giving the first control signal to the switching means to generate the spark discharge voltage in the secondary coil of the ignition coil. The primary coil is repeatedly energized and interrupted a plurality of times by being supplied to the means, and a spark discharge voltage is intermittently generated in the secondary coil. As a result, after the spark plug discharges with the spark discharge voltage according to the first control signal, the spark plug intermittently repeats the spark discharge with the spark discharge voltage according to the second control signal after a predetermined time has elapsed. The spark duration of the plug can be extended.
  Therefore, the spark duration of the spark plug can be set longer even in the operation state in the stratified intake state (stratified combustion state). Therefore, there is an effect that the ignitability can be improved without increasing the size of the ignition coil under the operating condition of the internal combustion engine in the stratified intake state.
In addition, the energization and shut-off of the switching means repeated by the second control signal by the ignition control means is a spark duration of the spark plug of 0.7 mSec. Or more and 1.3 mSec. Or less according to measurement based on the American Automobile Engineering Association standard SAEJ973. Under the power supply conditions, the ratio of the energization time to one cycle by energization and interruption is 30% or more and 70% or less, and the interruption time is 200 μSec. Or less. This avoids an ion shortage state between the spark plug electrodes that may occur when the energization time is less than 30%, and prevents a secondary coil energy shortage state that may occur when the energization time exceeds 70%. Can do. That is, it is possible to prevent a discharge failure that may occur when the energization duty ratio is 30% or more and 70% or less. Preferably, the ratio of the energization time to one cycle by energization and interruption is 40% or more and 60% or less, and the interruption time is 100 μSec. Or less.
Thereby, since such a discharge failure can be prevented more effectively, there is an effect that ignition can be performed more reliably under the same operating condition.
[0014]
  In the invention of claim 2, the number of repetitions of energization and interruption of the primary current by the second control signal of the ignition control means is arbitrarily set according to the operating condition of the internal combustion engine. Thereby, it is possible to set the repetition number of energization and interruption of the primary current suitable for the operating condition of the internal combustion engine.
  Therefore, according to the invention of claim 2, in addition to the effect of the invention of claim 1, there is an effect that an ignitability suitable for the operating condition of the internal combustion engine can be obtained.
[0016]
  According to the invention of claim 3, the same operation and effect as the invention of claim 1 can be obtained.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an ignition system and ignition method for an internal combustion engine according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the internal combustion engine ignition system (hereinafter referred to as “ignition system”) according to the present embodiment mainly includes a spark plug 10, an ignition coil 12, and an engine control unit (hereinafter referred to as “ECU”). 20, a switching element IG, and a battery BATT. In the ignition system, as described below, the first spark discharge voltage and the second spark discharge voltage are applied to the spark plug 10 based on the ignition method of the internal combustion engine of the present invention.
[0018]
The spark plug 10 includes a center electrode 10a and a ground electrode 10b, and is attached to the internal combustion engine such that both electrodes are exposed in the cylinder of the internal combustion engine. Then, a spark discharge voltage supplied from the ignition coil 12 is applied to the center electrode 10a and the ground electrode 10b, whereby a spark discharge is performed between the two electrodes.
As a result, ions are generated between the electrodes due to the combustion after the spark discharge by the spark plug 10 or the like, so that an ion current mediated by the ions can flow between the electrodes after the spark discharge.
[0019]
The ignition coil 12 supplies a spark discharge voltage to the spark plug 10. For example, a primary coil L1 and a secondary coil L2 are wound around a magnetic core, and the turn ratio of both the coils L1 and L2 is a predetermined value. Set to and configured.
The positive terminal of the battery BATT is connected to one end side of the primary coil L1, and the other end side of the primary coil L1 is connected to the negative terminal of the battery BATT via the switching element IG constituting the ignition control means 24. Yes. On the other hand, the center electrode 10a of the spark plug 10 is connected to one end side of the secondary coil L2 of the ignition coil 12, and the ground electrode 10b is connected to the other end side of the secondary coil L2 via ground.
[0020]
The resistor R interposed between the other end of the secondary coil L2 and the ground is a measuring resistor for measuring the discharge current generated by the spark plug 10 and is not an element constituting the ignition system. That is, it is necessary to measure a potential difference generated in proportion to the amount of current as a discharge current at the measurement point α by flowing a discharge current through the resistor R. Thereby, the discharge current waveform as shown in FIGS. 2A and 2B can be captured by an oscilloscope or the like.
[0021]
The switching element IG is connected in series to the primary coil L1 of the ignition coil 12, and the primary current supplied to the primary coil L1 is energized or cut off by the control signals IGS1 and IGS2.
Specifically, the switching element IG is constituted by a transistor, for example, and the collector terminal is connected to the other end of the primary coil L1, and the emitter terminal is connected to the ground. An output terminal of the ECU 20 that outputs a control signal IGS1 and the like is connected to the base terminal of the switching element IG. As a result, when the first control signal IGS1 and the like are output from the ECU 20, the emitter and collector of the switching element IG shift from the disconnected state to the energized state, so that the primary current from the battery BATT can be applied to the primary coil L1. it can.
[0022]
The ECU 20 is an engine control unit including, for example, a main storage device, a microcomputer incorporating each register, an input / output interface, and the like, and controls various electronic controls related to the internal combustion engine. In this ignition system, the ECU 20 controls the energization / cutoff timing of the switching element IG described above, and also has a function of an operation state determination unit that determines the operation state of the internal combustion engine. Each of these processes is executed by a predetermined control program built in the main storage device or the like.
[0023]
The first control signal IGS1 output from the ECU 20 is for applying a spark discharge voltage (first spark discharge voltage) necessary for causing the spark plug 10 to perform the first spark discharge from the ignition coil 12 to the spark plug 10. It is. Specifically, the first control signal IGS1 is applied to the base terminal of the switching element IG for a certain period.
[0024]
By applying the first control signal IGS1, the emitter and collector of the switching element IG are energized during the period, so that the primary coil L1 of the ignition coil 12 is energized with the primary current from the battery BATT, and the primary coil L1 is energized. Is stored. Since the emitter and collector of the switching element IG are cut off by the end of the first control signal IGS1, a negative high voltage lower than the ground potential of the secondary coil L2 due to the energy stored in the primary coil L1, that is, a spark. A discharge voltage is induced, and the induced spark discharge voltage is applied to the spark plug 10. Thereby, when the insulation by the space formed between the center electrode 10a of the spark plug 10 and the ground electrode 10b is broken, a spark discharge is generated between the electrodes. That is, breakdown occurs.
[0025]
The second control signal IGS2 output from the ECU 20 is performed after a predetermined time t0 has elapsed since the end of the first control signal IGS1. For example, the predetermined time t0 is set to 0.3 mSec. Here, the reason for waiting for the elapse of the predetermined time t0 is to keep the spark discharge generated by the first control signal IGS1 as long as possible through the ions generated between the two electrodes.
[0026]
The second control signal IGS2 output from the ECU 20 generates a spark discharge voltage (second spark discharge voltage) necessary for causing the spark plug 10 that has once spark-discharged to cause another spark discharge from the ignition coil 12 to the spark plug 10. To give to. Specifically, the second control signal IGS2 in which the switching element IG repeats energization and interruption a plurality of times is applied for a certain period.
[0027]
Note that the predetermined period t1 for repeating this energization and interruption is set to, for example, 200 μSec. The fixed period during which the second control signal IGS2 is applied is determined by the number of times of energization and interruption (for example, when the predetermined cycle t1 is 200 .mu.Sec. Is repeated 14 times, it is 2.8 mSec.).
[0028]
Application of the second control signal IGS2 causes the emitter and collector of the switching element IG to repeat the energized state and the interrupted state at a predetermined period t1 during the period, so that the primary coil L1 of the ignition coil 12 is connected to the battery BATT. The primary current due to is intermittently energized. That is, energy is repeatedly stored and released in the primary coil L1 of the ignition coil 12 at the predetermined period t1. Therefore, a spark discharge voltage is induced in the secondary coil L2 of the ignition coil 12 corresponding to the predetermined period t1. As a result, a spark discharge voltage (second discharge voltage) lower than the spark discharge voltage (first spark discharge voltage) by the first control signal IGS1 is intermittently repeatedly applied between both electrodes of the spark plug 10. Is done.
[0029]
Ions already generated by the first spark discharge by the first control signal IGS1 already exist between both electrodes of the spark plug 10 when such a second discharge voltage is repeatedly applied. Therefore, even if the second spark discharge voltage by the second control signal IGS2 is lower than the first spark discharge voltage, in the atmosphere where such ions exist, the spark discharge is caused between the two electrodes via the ions. Can be generated. Thereby, the spark plug 10 can intermittently repeat the spark discharge.
[0030]
Next, the experimental results of performing the ignition control of the internal combustion engine by the present ignition system will be described based on FIGS.
Here, FIG. 2 shows the discharge current at the measurement point α shown in FIG. 1, the discharge voltage at the measurement point β, and the pressure in the cylinder to which the spark plug 10 is attached (hereinafter referred to as “in-cylinder pressure”). ) Are respectively measured with an oscilloscope. The horizontal axis is 0.5 mSec./div.
[0031]
As described above, the discharge voltage, discharge current and in-cylinder pressure shown in FIG. 2 (A) are set to 0.3 mSec for a predetermined time t0 waiting from the end of the first control signal IGS1 to the start of the second control signal IGS2. In addition, the repetition cycle of energization and interruption by the second control signal IGS2, that is, the predetermined cycle t1 is set to 200 .mu.Sec., And this repetition is performed 14 times. In the predetermined period t1, the energization time t2 is set to 100 .mu.Sec., And the cutoff time t3 is set to 100 .mu.Sec.
[0032]
As shown in FIG. 2 (A), it can be seen from the discharge voltage waveform and the discharge current waveform that the first spark discharge is first generated by the first control signal IGS1 and the predetermined time t0. Then, after the elapse of the predetermined time t0, the energization and interruption of the predetermined period t1 are performed 14 times by the second control signal IGS2, and the second and subsequent spark discharges are intermittently generated at the same period t1. You can see that
[0033]
As a result, it was confirmed that the overall spark duration t4 was extended to about 3 mSec. FIG. 2 (A) also shows that an inflection point appears in the in-cylinder pressure waveform within such a spark duration t4, so it is also confirmed that ignition occurred in the cylinder.
[0034]
The discharge voltage, discharge current and in-cylinder pressure shown in FIG. 2 (B) are the same as those shown in FIG. 2 (A), but the predetermined cycle t1 by the second control signal IGS2 is set to 100 μSec. The point I went is different. In the predetermined period t1, the energization time t2 is set to 50 .mu.Sec., And the cutoff time t3 is set to 50 .mu.Sec.
[0035]
As shown in FIG. 2 (B), as in FIG. 2 (A), the first spark discharge is first generated by the first control signal IGS1 and the predetermined time t0 from the discharge voltage waveform and the discharge current waveform. Recognize. Then, after the elapse of the predetermined time t0, the energization and interruption of the predetermined period t1 are performed 28 times by the second control signal IGS2, and the second and subsequent spark discharges are intermittently generated at the same period t1. You can see that
[0036]
Since the overall spark duration t4 is also extended to about 3 mSec., Within the range where the predetermined period t1 is set to 100 μSec., The same period t1 is not much different from that set to 200 μSec. Was confirmed. Also from FIG. 2 (B), since an inflection point appears in the in-cylinder pressure waveform within the spark duration t4, it is also confirmed that ignition occurred in the cylinder.
[0037]
FIG. 3A is a first comparative example using a large ignition coil in which the spark duration t5 is extended by increasing the number of coil turns. According to the ignition system using such a large ignition coil, it is possible to extend the spark duration t5 by one spark discharge to about 2.5 mSec. The problem that the volume of the ignition coil itself increases due to the increase in size cannot be solved.
[0038]
FIG. 3B shows a second comparative example in which the ignition coil is reduced in size by reducing the number of coil turns. According to the ignition system using such a miniaturized ignition coil, the spark duration t6 due to one spark discharge remains at about 0.8 mSec. Due to the decrease in inductance of the secondary coil. Therefore, the problem that the spark duration is shortened due to a decrease in stored energy cannot be solved.
[0039]
Comparing the ignition system with the first and second comparative examples, the ignition system can extend the spark duration without increasing the size of the ignition coil 10 from FIG. 3 described above. As a result, it can be clearly seen that the ignitability can be improved.
[0040]
Next, in order to more clearly confirm the improvement in ignitability by the present ignition system, the result of measuring the combustion fluctuation when the A / F in the cylinder is lean is shown in FIG.
As shown in FIG. 4, the fluctuation rate of the mean finger effective pressure (IMEP) with respect to the A / F in the cylinder is expressed by the following (1) to (4) using a 3L, 6 cylinder in-cylinder injection engine. Four types were measured.
[0041]
(1) Among the ignition systems described above, the ignition system corresponds to FIG. 2A (predetermined time t0 is set to 0.3 mSec., And predetermined period t1 is set to 200 μSec.). (Spark duration 0.3 mSec. + S100).
(2) Among the ignition systems described above, those corresponding to FIG. 2B (predetermined time t0 is set to 0.3 mSec. And predetermined period t1 is set to 100 μSec.). In FIG. 4, white square marks (□) (Spark duration 0.3 mSec. + S50).
(3) A large ignition coil according to the first comparative example corresponding to FIG. 3 (A) described above, which is plotted with a black circle (●) in FIG. 4 (spark duration 2.5 mSec.). is there.
(4) A small ignition coil according to the second comparative example corresponding to FIG. 3 (B) described above, which is plotted with a white circle (◯) in FIG. 4 (spark duration 0.8 mSec.). is there.
[0042]
In this measurement, the better the ignitability, the better the conditions from the spark duration, that is, the closer to the characteristic curve obtained by the first comparative example (spark duration 2.5 mSec.) Plotted with ● Indicates that
Therefore, when the spark duration 0.3 mSec. + S100 plotted by ▲ and the spark duration 0.3 mSec. + S50 plotted by □ are examined, the spark duration 0.3 mSec. + S100 and □ plotted by ▲ are plotted. It can be seen from FIG. 4 that both spark duration 0.3 mSec. + S50 have characteristics similar to the characteristic curve of the first comparative example plotted with ● even when the A / F in the cylinder is in a lean state. .
[0043]
On the other hand, according to the second comparative example plotted with ◯, as the A / F approaches the lean state, the characteristic that moves away from the characteristic curve of the first comparative example toward the direction in which the variation rate of IMEP increases. It can be seen from FIG. That is, it is shown that the ignitability deteriorates when the size is reduced by simply reducing the number of turns of the ignition coil. As is apparent from the measurement of the combustion fluctuation, according to the present ignition system, it is possible to obtain the ignition quality equivalent to that of the large coil while reducing the size of the ignition coil 12 itself.
[0044]
Next, in order to confirm the improvement in ignitability by this ignition system also in stratified combustion, the results of measuring the combustion fluctuation in the stratified state are shown in FIGS.
Fig. 5 (A) shows the measurement of the torque value obtained by changing the fuel injection timing (crank angle) and the ignition timing (crank angle). It is shown in
Here, in FIG. 5A, the range where the measurement point A is located is the range where the torque value is the largest, and the magnitude of the torque value decreases in order from this range toward the outside. Therefore, the torque value decreases in the order of measurement point C, measurement point C, and measurement point B next to measurement point A.
[0045]
The measurement point A is a combination of fuel injection timing and ignition timing at which a good combustion state is obtained. The measurement point B is a combination of fuel injection timing and ignition timing at which a good combustion state cannot be obtained even in the ignition system using the large ignition coil according to the first comparative example. Furthermore, the measurement point C is good in the ignition system using the large ignition coil according to the first comparative example, but good in the ignition system using the small ignition coil according to the second comparative example. This is a combination of fuel injection timing and ignition timing at which a proper combustion state cannot be obtained.
[0046]
At each of these measurement points (A to C), the fluctuation rate of the figure finger mean effective pressure (IMEP) with respect to the A / F in the cylinder is expressed by the following (5 ) To (9) are shown in FIG. 5 (B). In the figure, the measurement point A is plotted with a black triangle mark (▲), the measurement point B is plotted with a black square mark (■), and the measurement point C is plotted with a white circle mark (◯).
[0047]
(5) A small ignition coil according to the second comparative example corresponding to FIG. 3 (B) described above is used, and there is a description of “sustained 0.8 mS” in FIG. 5 (B).
(6) A large ignition coil according to the first comparative example corresponding to FIG. 3 (A) described above is used, and there is a description of “sustained 2.5 mS” in FIG. 5 (B).
(7) Among the ignition systems described above, the predetermined time t0 is set to 0.3 mSec., The predetermined period t1 is set to 400 μSec., And there is a description of “sustained 0.3 mSec. + S200” in FIG. is there.
(8) Among the ignition systems described above, the ignition system corresponds to FIG. 2A (predetermined time t0 is set to 0.3 mSec. And predetermined period t1 is set to 200 μSec.). 3 mSec. + S100 ".
(9) Among the ignition systems described above, the ignition system corresponds to FIG. 2B (the predetermined time t0 is set to 0.3 mSec. And the predetermined period t1 is set to 100 μSec.). 3 mSec. + S50 ".
[0048]
In each of the ignition systems according to (7) to (9), the energization / interruption of the predetermined period t1 by the second control signal IGS2 is occupied by the energization time t2 for one period t1 by the energization t2 and the interruption t3. The ratio, that is, the duty ratio of the energization time is set to 50% (see FIG. 5B).
[0049]
In this measurement, the smaller the rate of variation of the mean finger effective pressure (IMEP) at any measurement point, the better the ignitability in the stratified state.
According to the ignition system, both the “continuous 0.3 mSec. + S50” in which the predetermined period t1 is set to 100 μSec. And the “continuous 0.3 mSec. + S100” in which the predetermined period t1 is set to 200 μSec. The variation rate of the figure finger average effective pressure is smaller than that using the large ignition coil according to the first comparative example, and the variation at the measurement point C is small. Therefore, it was confirmed that these were better in ignitability than in the first comparative example in the stratified state.
Although not shown, it has been confirmed that good ignitability cannot be obtained when the predetermined time t0 is set to 0.3 mSec. And the predetermined period t1 is set to 800 μSec.
[0050]
In addition, even when the predetermined period t1 is set to 400 .mu.Sec. By "sustained 0.3 mSec. + S200", the variation of the average effective finger finger at each measurement point (A to C) is almost the same as that according to the first comparative example. The rate is limited. As a result, it was confirmed that even when the energization time t2 and the shutoff time t3 were set to 200 .mu.Sec., The same ignitability as that obtained using the large ignition coil according to the first comparative example was obtained.
[0051]
The measurement result shown in FIG. 6 is based on the second control signal IGS2 under the same conditions as the measurement conditions shown in FIG. 5 except that the predetermined time t0 is set to 0.3 mSec. And the predetermined period t1 is set to 200 .mu.Sec. This is a measurement of the variation rate of the average finger effective pressure (IMEP) when the duty ratio of the energization time is changed to 70%, 50%, and 30%, respectively. Measurement points A to C shown in FIG. 5 (A) correspond to measurement points D to F in FIG. 6 (A), respectively.
[0052]
At each of these measurement points (D to F), the variation rate of the figure finger average effective pressure (IMEP) with respect to the A / F in the cylinder is expressed by the following (10 ) To (14) are shown in FIG. 6 (B). In the figure, the measurement point D is plotted with a black triangle mark (▲), the measurement point E is plotted with a black square mark (■), and the measurement point F is plotted with a white circle mark (◯).
[0053]
(10) A small ignition coil according to the second comparative example corresponding to FIG. 3 (B) described above is used, and there is a description of “sustained 0.8 mS” in FIG. 6 (B).
(11) A large ignition coil according to the first comparative example corresponding to FIG. 3 (A) described above is used, and there is a description of “sustained 2.5 mS” in FIG. 6 (B).
(12) In the ignition system described above, the predetermined time t0 is set to 0.3 mSec., The predetermined period t1 is set to 200 μSec., And the duty ratio of the energizing time is set to 30%. . + S100, Duty 30% ".
(13) In the ignition system described above, the predetermined time t0 is set to 0.3 mSec., The predetermined period t1 is set to 200 μSec., And the duty ratio of the energization time is set to 50%. . + S100, Duty 50% ".
(14) In the ignition system described above, the predetermined time t0 is set to 0.3 mSec., The predetermined period t1 is set to 200 μSec., And the duty ratio of the energization time is set to 70%. . + S100, Duty 70% ".
[0054]
As shown in FIG. 6B, it was confirmed from this measurement result that good ignitability can be obtained when the duty ratio of the energization time is 30% or more and 70% or less. Although not shown, it has also been confirmed that when the duty ratio of the energization time is less than 30%, the fluctuation rate of the figure finger average effective pressure increases. This is presumably because the energization time is too short, so that the energy stored in the ignition coil 12 is insufficient and the ability to generate a spark discharge voltage is reduced. It has also been confirmed that even when the duty ratio of the energization time exceeds 70%, the fluctuation rate of the index finger average effective pressure increases. This is presumably because the ion generated between the electrodes of the spark plug 10 is reduced due to the interruption time being too long, and the atmosphere between the electrodes is difficult to spark discharge.
[0055]
As described above, according to the present ignition system, the ECU 20 gives the first control signal IGS1 to the switching element IG to generate the spark discharge voltage in the secondary coil L2 of the ignition coil 12, and then the elapse of the predetermined time t0. After that, the second control signal IGS2 is given to the switching element IG, and the primary current is repeatedly turned on and off a plurality of times, and a spark discharge voltage is intermittently generated in the secondary coil L2. As a result, after the spark plug 10 has sparked with the spark discharge voltage according to the first control signal IGS1, and after a predetermined time t0 has elapsed, the spark plug 10 will intermittently discharge with sparks due to the spark discharge voltage according to the second control signal IGS2. Since it repeats, the spark duration of the spark plug 10 can be extended. Therefore, the spark duration of the spark plug 10 can be set longer even in an operating state such as stratified combustion or lean conditions. Therefore, there is an effect that the ignitability can be improved without increasing the size of the ignition coil 12 under the operating condition of the internal combustion engine in the lean or stratified intake state.
[0056]
As described above, the ECU 20 has a function of an operating state determining means for determining the operating state of the internal combustion engine. Therefore, depending on the operating condition of the internal combustion engine, the primary current is supplied and cut off by the second control signal IGS2. It is also possible to perform control so as to vary the number of repetitions, i.e., a certain period during which the second control signal IGS2 is applied. As a result, the number of repetitions of energization / cutoff by the second control signal IGS2 can be set to a value suitable for the operating condition of the internal combustion engine. Therefore, there is an effect that the ignitability suitable for the operating condition of the internal combustion engine can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an ignition system according to an embodiment of the present invention.
2 is a time chart showing respective signals and voltage waveforms by the ignition system according to the present embodiment. FIG. 2 (A) is a diagram in which energization / interruption is repeated at a cycle of 100 μSec. After a spark duration of 0.3 mSec. (B) repeats energization / interruption with a period of 50 μSec. After a spark duration of 0.3 mSec.
FIGS. 3A and 3B are time charts showing respective signals and voltage waveforms by an ignition system according to a comparative example. FIG. 3A shows a first comparative example using a large ignition coil, and FIG. It is based on the 2nd comparative example using an ignition coil.
FIG. 4 is a characteristic diagram showing a result of measuring a variation rate of a figure finger average effective pressure (IMEP) with respect to A / F in a cylinder.
FIG. 5 is a characteristic diagram showing combustion fluctuations of an internal combustion engine in a stratified state. FIG. 5 (A) shows a combustion pressure value obtained by changing fuel injection timing and ignition timing, and FIG. ) Is a measurement of the fluctuation rate of the average finger effective pressure (IMEP) at the measurement points A to C shown in FIG.
FIG. 6 is a characteristic diagram showing combustion fluctuations of an internal combustion engine in a stratified state. FIG. 6 (A) shows a combustion pressure value obtained by changing fuel injection timing and ignition timing, and FIG. ) Is a measurement of the fluctuation rate of the average finger effective pressure (IMEP) at the measurement points D to F shown in FIG.
[Explanation of symbols]
10 Spark plug
10a Center electrode
10b Ground electrode
12 Ignition coil
20 ECU (ignition control means)
IG switching element (switching means)
L1 primary coil
L2 secondary coil
IGS1 first control signal (first control signal)
IGS2 second control signal (second control signal)
t0 Predetermined time
t1 predetermined period

Claims (3)

In an internal combustion engine ignition system used for operation in a stratified intake state ,
A spark plug attached to a cylinder of the internal combustion engine;
An ignition coil for supplying a spark discharge voltage to the spark plug;
Switching means connected in series to a primary coil of the ignition coil and energizing or interrupting a primary current energized to the primary coil by a control signal;
Ignition control means for providing the control signal to the switching means;
An internal combustion engine ignition system comprising:
The ignition control means provides a first control signal to the switching means to generate the spark discharge voltage in the secondary coil of the ignition coil, and after a predetermined time has elapsed, a second control signal is sent to the switching means. The primary current is turned on and off a plurality of times and the spark discharge voltage is intermittently generated in the secondary coil ,
The switching means is repeatedly energized and interrupted by the second control signal, when the spark plug spark duration is 0.7 mSec. Or more and 1.3 mSec. Or less as measured by the American Automobile Engineering Association standard SAEJ973. ignition system of energization and interruption by at most 70 percentage bur 30% or more accounts of the energization time for one period, the internal combustion engine shut off time and wherein the 200 .mu.sec. following der Rukoto.   2. The ignition system for an internal combustion engine according to claim 1, wherein the number of repetitions of energization and interruption of the primary current by the second control signal is arbitrarily set according to operating conditions of the internal combustion engine. In an ignition method for an internal combustion engine used for operation in a stratified intake state ,
A second spark required for spark discharge of the spark plug after a predetermined time has elapsed after the first spark discharge voltage required for spark discharge of the spark plug attached to the internal combustion engine is applied from the ignition coil to the spark plug. Applying a discharge voltage to the spark plug repeatedly from the ignition coil a plurality of times intermittently ;
When the second spark discharge voltage is applied to the ignition plug, the energization and the interruption are measured according to American Automobile Engineers Association Standard SAEJ973, and the spark plug has a spark duration of 0.7 mSec. Or more and 1.3 mSec. Or less. An internal combustion engine ignition system characterized in that, under conditions, a ratio of energization time to one cycle by energization and shut-off is 30% to 70% and a shut-off time is 200 μSec. Or less .

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