JP4835589B2 - Ignition control system for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition control system for a spark ignition type internal combustion engine.

Conventionally, when a torque-down condition for reducing the torque of the internal combustion engine is established, a technique has been proposed in which the throttle valve opening is decreased and the ignition timing is advanced by MBT (Minimum spark advance for Best Torque) (for example, , See Patent Document 1).
JP-A-5-302535 JP 2007-40259 A Japanese Patent No. 2825164 JP 61-34358 A

  However, if the ignition timing is always advanced from the MBT when the torque-down condition is satisfied, there is a problem that the energy that is not useful for the generated torque of the internal combustion engine, the exhaust temperature, etc. increases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an energy control system for an internal combustion engine that reduces torque by adjusting the ignition timing of a spark ignition internal combustion engine. An object of the present invention is to provide a technique capable of approximating the generated torque of an internal combustion engine to a target value while achieving as much usefulness as possible.

  In order to solve the above-described problems, the present invention provides an ignition control system for an internal combustion engine that controls ignition timing so that a physical quantity correlated with a generated torque of a spark ignition internal combustion engine matches a target value. When a torque down request is made to decrease to a value, the ignition timing is retarded from the MBT as much as possible to ensure the combustion stability of the internal combustion engine, and the torque is reduced while ensuring the combustion stability of the internal combustion engine. Only when the engine could not be reduced, the ignition timing was advanced from the MBT to reduce the torque.

  When the ignition timing is retarded from MBT, the torque generated by the internal combustion engine tends to decrease as the ignition timing retard amount increases. However, if the ignition timing is significantly retarded after the compression top dead center (TDC), there is a risk of causing misfire due to a decrease in combustion stability and an excessive increase in exhaust temperature. Therefore, a retard guard is set in the ignition timing control logic.

  Therefore, when a significant torque reduction request is generated (when the difference between the actual generated torque and the target value is large), the generated torque of the internal combustion engine may not be reduced to the target value.

  On the other hand, when the ignition timing is advanced from the MBT, a part of the energy generated by the combustion of the air-fuel mixture acts to reverse the internal combustion engine. For this reason, it is possible to significantly reduce the torque with a relatively small advance amount. In addition, when the ignition timing is advanced before MBT, ignition is performed while the in-cylinder pressure is rising, so that incomplete combustion is less likely to occur than when the ignition timing is retarded after MBT. In addition, there is an advantage that it is difficult to increase the exhaust temperature.

However, the energy that acts to reverse the internal combustion engine does not contribute to the torque generated by the internal combustion engine or the exhaust gas temperature, which causes a decrease in the operating efficiency of the internal combustion engine and an unnecessary increase in fuel consumption.

Therefore, the present invention provides an ignition control system for an internal combustion engine that controls an ignition timing so that a physical quantity correlated with a generated torque of a spark ignition internal combustion engine matches a target value.
First acquisition means for acquiring a first ignition timing that is an ignition timing capable of achieving the target value in a range retarded from MBT;
Second acquisition means for acquiring a second ignition timing that is an ignition timing capable of achieving the target value in a range on the advance side from MBT;
When the first ignition timing is earlier than or equivalent to a predetermined retard guard, the first ignition timing is set as a target ignition timing, and the first ignition timing is later than the retard guard. A control means for setting the second ignition timing as a target ignition timing,
I was prepared to.

  According to this invention, only when the first ignition timing is later than the retard guard, the second ignition timing is set to the target ignition timing. As a result, it is possible to bring the generated torque of the internal combustion engine closer to the target value while making the energy as useful as possible.

  By the way, even if the first ignition timing satisfies the condition as the target ignition timing (same timing as the retard guard or the timing earlier than the retard guard), the combustion stability may deteriorate depending on the use environment of the internal combustion engine. The amount of fluctuation in torque and engine speed may be excessive.

  In contrast, the ignition control system for an internal combustion engine according to the present invention sets the target ignition timing to the first ignition timing when the variation amount of the physical quantity exceeds the allowable amount when the first ignition timing is set to the target ignition timing. It may be changed from the second ignition timing to the second ignition timing.

  According to such an ignition control system for an internal combustion engine, it is possible to more reliably suppress a decrease in combustion stability while keeping the generated torque of the internal combustion engine equal.

  On the other hand, even when the second ignition timing is set to the target ignition timing, there is a possibility that combustion stability may be reduced or misfire may occur due to the influence of the use environment of the internal combustion engine. Therefore, in the ignition control system for an internal combustion engine of the present invention, if misfire is detected when the second ignition timing is set to the target ignition timing, the target ignition timing is changed from the second ignition timing to the third ignition timing after MBT. You may make it change to.

  When the target ignition timing is set in this way, since the continuous occurrence of misfire is suppressed, it is possible to prevent the internal combustion engine from stalling.

  The third ignition timing may be determined so that the internal combustion engine generates torque as close as possible to the torque that can be generated by the internal combustion engine when the second ignition timing is set to the target ignition timing. An example of the third ignition timing that satisfies such conditions is an ignition timing at the same time as the retard guard. If the third ignition timing is set at the same time as the retard guard, the combustion stability can be improved without excessively increasing the torque generated by the internal combustion engine.

  The case where the present invention is effectively utilized includes (1) when the engine speed exceeds the target engine speed in the ignition timing feedback control for converging the engine speed to the target engine speed, or (2 The case where it is necessary to reduce the torque transmitted to the drive wheels in the attitude stability control of the vehicle on which the internal combustion engine is mounted can be exemplified.

In the case of (1) described above, if the retard amount of the ignition timing is limited by the retard guard, the torque generated by the internal combustion engine does not decrease to the target value, so that the engine speed can be decreased to the target engine speed. It may not be possible. Also in the case of (2) described above, if the retard amount of the ignition timing is limited by the retard guard, there is a possibility that the torque transmitted to the drive wheels cannot be reduced to a desired torque.

  When the present invention is applied to these cases, the generated torque of the internal combustion engine is set to the target value by advancing the ignition timing before MBT even in a situation where the retard amount of the ignition timing is limited by the retard guard. Can be reduced to Furthermore, since the ignition timing is advanced before MBT only when the ignition timing that can achieve the target value is later than the retard guard, it is possible to minimize unnecessary consumption of combustion energy. is there.

  In the present invention, examples of the physical quantity correlated with the torque generated by the internal combustion engine include the rotational angular acceleration of the crankshaft, the in-cylinder pressure of the cylinder in the expansion stroke, or the engine speed.

  According to the present invention, in an ignition control system for an internal combustion engine that reduces torque by adjusting the ignition timing of a spark ignition internal combustion engine, the generated torque of the internal combustion engine is set to a target value while making the energy as useful as possible. It is possible to approximate.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

<Example 1>
First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of an ignition control system for an internal combustion engine according to the present invention.

  An internal combustion engine 1 shown in FIG. 1 is a 4-stroke cycle spark ignition internal combustion engine (gasoline engine) having a plurality of cylinders 2.

  Each cylinder 2 of the internal combustion engine 1 is connected to the intake passage 30 via the intake port 3 and is connected to the exhaust passage 40 via the exhaust port 4.

  The intake port 3 is provided with a fuel injection valve 5 that injects fuel into the cylinder 2. The intake passage 30 is provided with a throttle valve 6 that controls the amount of air flowing through the intake passage 30.

  An intake pressure sensor 7 that measures the pressure (intake pressure) in the intake passage 30 is provided in the intake passage 30 downstream of the throttle valve 6. An air flow meter 8 that measures the amount of air flowing through the intake passage 30 is provided in the intake passage 30 upstream of the throttle valve 6.

  An exhaust purification device 9 is disposed in the exhaust passage 40. The exhaust purification device 9 includes a three-way catalyst, an NOx storage reduction catalyst, and the like, and purifies exhaust when it is in a predetermined activation temperature range.

  An air-fuel ratio sensor 41 that outputs a signal correlated with the air-fuel ratio of the exhaust gas flowing in the exhaust passage 40 is disposed in the exhaust passage 40 downstream of the exhaust purification device 9.

Further, the internal combustion engine 1 is provided with an intake valve 10 that opens and closes an open end of the intake port 3 facing the cylinder 2 and an exhaust valve 11 that opens and closes an open end of the exhaust port 4 facing the cylinder 2. The intake valve 10 and the exhaust valve 11 are driven to open and close by an intake camshaft 12 and an exhaust camshaft 13, respectively.

  A spark plug 14 for igniting the air-fuel mixture in the cylinder 2 is disposed at the upper part of the cylinder 2. A piston 15 is slidably inserted into the cylinder 2. The piston 15 is connected to the crankshaft 17 via the connecting rod 16.

  A crank position sensor 18 that detects the rotation angle of the crankshaft 17 is disposed in the internal combustion engine 1 in the vicinity of the crankshaft 17. Further, a water temperature sensor 19 that measures the temperature of the cooling water circulating through the internal combustion engine 1 is attached to the internal combustion engine 1.

  The internal combustion engine 1 configured as described above is provided with an ECU 20. The ECU 20 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like. The ECU 20 is electrically connected to various sensors such as the intake pressure sensor 7, the air flow meter 8, the crank position sensor 18, the water temperature sensor 19, and the air / fuel ratio sensor 41 described above, and inputs measurement values of the various sensors.

  The ECU 20 electrically controls the fuel injection valve 5, the throttle valve 6, and the spark plug 14 based on the measurement values of the various sensors described above.

  For example, the ECU 20 controls the operation timing (ignition timing) of the spark plug 14 so that the physical quantity correlated with the generated torque of the internal combustion engine 1 matches the target value. When such control is necessary, it is possible to execute the ignition timing feedback control for converging the engine speed to the target engine speed, or the attitude stability control of the vehicle equipped with the internal combustion engine 1. It can be illustrated. Hereinafter, an ignition timing control method will be described by taking ignition timing feedback control as an example.

  The ignition timing feedback control is executed for the purpose of preventing the engine speed from being increased when the internal combustion engine 1 is started, for example. FIG. 2 is a diagram showing measurement results of the engine speed and the exhaust air / fuel ratio when the internal combustion engine 1 is started.

  In FIG. 2, when cranking of the internal combustion engine 1 is started (a starter motor (not shown) is started), the engine speed Ne rotates at a predetermined cranking speed Necrk (for example, 200 rpm).

  When the air-fuel mixture burns (initial explosion) in a cylinder 2 in which the internal combustion engine 1 is located, the engine speed Ne starts to increase from the cranking speed (t1 in FIG. 2). Thereafter, when the air-fuel mixture burns (complete explosion) in all the cylinders 2 of the internal combustion engine 1, the engine speed Ne exceeds the target engine speed Netrg (t2 in FIG. 2).

  If the engine speed Ne blows up exceeding the target engine speed Netrg, vibration and noise may increase. The increase in vibration and noise tends to become more prominent as the engine speed Ne increases (the difference between the engine speed Ne and the target engine speed Netrg).

  On the other hand, the air-fuel ratio of the exhaust begins to decrease with a slight delay with respect to the timing t1 when the first explosion occurred. This delay is because it takes time (transport delay) until the gas (exhaust gas) discharged from the cylinder 2 reaches the air-fuel ratio sensor 41.

When the internal combustion engine 1 is completely exploded, the target air-fuel ratio A / Ftrg is reached with a transport delay due to the same reason as described above. When the engine speed Ne exceeds the target engine speed Netrg, it has adhered to the inner wall surface of the intake port 3 or the inner wall surface of the cylinder 2 due to an increase in the flow rate of intake air or a decrease in pressure downstream of the throttle valve 6. Unburned fuel is detached from the inner wall surface. The unburned fuel separated from the inner wall surface or the like is easily discharged to the exhaust port 4 without being used for combustion in the cylinder 2. For this reason, the exhaust air-fuel ratio decreases to an air-fuel ratio that is lower than the target air-fuel ratio A / Ftrg. The amount of decrease at that time tends to increase as the amount of engine speed Ne increases. When the internal combustion engine 1 is cold-started or the like, there is a high possibility that the temperature of the exhaust emission control device 9 has not reached the activation temperature range, so the unburned fuel described above is discharged into the atmosphere without being purified. It is also a concern.

  Therefore, when the engine speed Ne rises, vibration and noise increase, and unburned fuel discharged from the internal combustion engine 1 to the atmosphere may increase.

  On the other hand, when the ignition timing feedback control is executed when the internal combustion engine 1 is started, the difference dn (= Ne−Netrg) between the actual engine speed Ne and the target engine speed Netrg, or the integrated value of the difference dn. The ignition timing is corrected based on the above.

  By the way, according to conventional ignition timing feedback control, when the engine speed Ne becomes higher than the target engine speed Netrg, the ignition timing is retarded from the MBT in order to reduce the generated torque of the internal combustion engine 1. become.

  However, if the ignition timing is significantly retarded from the MBT, the ignition timing becomes later than the compression top dead center (TDC), so that ignition failure and incomplete combustion are likely to occur. In order to prevent such a problem, a retard angle guard is set in the ignition timing feedback control logic.

  Therefore, when the difference between the engine speed Ne and the target engine speed Netrg is large (in other words, when the generated torque of the internal combustion engine 1 needs to be greatly reduced), the retard amount of the ignition timing is retarded. Limited by.

  If the retard amount of the ignition timing is limited by the retard guard, the generated torque of the internal combustion engine 1 may not be reduced to the target value. In such a case, the increase in engine speed Ne cannot be suppressed, so that an increase in vibration, an increase in noise, an increase in the discharge amount of unburned fuel, etc. cannot be sufficiently suppressed.

  On the other hand, a method of reducing the generated torque of the internal combustion engine 1 by advancing the ignition timing before MBT is conceivable. When the ignition timing is advanced before MBT, a part of the energy generated by the combustion of the air-fuel mixture acts to reverse the crankshaft 17. For this reason, it is possible to significantly reduce the torque with a relatively small advance amount. Further, when the ignition timing is advanced before MBT, ignition is performed while the in-cylinder pressure is rising. Therefore, compared with the case where the ignition timing is retarded after MBT, poor ignition or incomplete combustion is performed. There is also an advantage that it becomes difficult to occur.

  However, the energy that acts to reverse the crankshaft 17 does not contribute to the torque generated or the exhaust temperature of the internal combustion engine 1, thereby leading to a decrease in operating efficiency of the internal combustion engine 1 and an unnecessary increase in fuel consumption. .

  Therefore, in the ignition timing feedback control in this embodiment, the ECU 20 retards the ignition timing from the MBT when the ignition timing that can achieve the target value in the range on the retard side from the MBT is the timing before the retard guard. To reduce the torque, and to advance the ignition timing from the MBT only when the ignition timing at which the target value can be achieved in the retard side range from the MBT is later than the retard guard. I made it.

Hereinafter, the control procedure of the ignition timing in the present embodiment will be described with reference to FIG. FIG.
It is a flowchart which shows the process routine which ECU20 performs when a torque down request | requirement generate | occur | produces. This processing routine is an interrupt processing routine that is executed with the occurrence of a torque reduction request in the middle of execution of the ignition timing feedback control as a trigger.

  In the processing routine of FIG. 3, the ECU 20 first determines whether or not a torque down request has occurred in S101. If a negative determination is made in S101, the ECU 20 ends the execution of this routine. On the other hand, if an affirmative determination is made in S101, the ECU 20 proceeds to S102.

  In S102, the ECU 20 acquires the ignition timing SA1 calculated from the difference dn between the engine speed Ne and the target engine speed Netrg, the integrated value of the difference dn, and the like in the main routine of ignition timing feedback control.

  The ignition timing SA1 acquired by the ECU 20 in S102 is a calculated value before the comparison with the retard guard ksa, and corresponds to the first ignition timing according to the present invention. Hereinafter, the ignition timing SA1 acquired in S102 will be referred to as a first ignition timing SA1.

  In S103, the ECU 20 determines whether or not the first ignition timing SA1 acquired in S102 is a timing before the retard guard ksa.

  If an affirmative determination is made in S103, the ECU 20 proceeds to S104. In S104, the ECU 20 sets the first ignition timing SA1 acquired in S102 as the target ignition timing SAtrg.

  In this case, the ECU 20 operates the spark plug 14 in accordance with the target ignition timing SAtrg set in S104. That is, the spark plug 14 operates at a timing later than MBT. As a result, it is possible to reduce the generated torque of the internal combustion engine 1 to the target value Tetrg while making the energy useful for raising the exhaust gas temperature and raising the temperature of the exhaust gas purification device 9.

  On the other hand, if a negative determination is made in S103, the ECU 20 proceeds to S105. In S105, the ECU 20 calculates a torque Tetrg that can be generated by the internal combustion engine 1 when the spark plug 14 is operated in accordance with the first ignition timing SA1 acquired in S102.

  At that time, the ECU 20 may use a map as shown in FIG. The map in FIG. 4 is a map showing the correlation between the ignition timing and the torque. The correlation between the ignition timing and the torque may be experimentally obtained in advance.

  The torque Tetrg obtained in S105 corresponds to the target value according to the present invention. Hereinafter, the torque Tetrg obtained in S105 is referred to as a target value Tetrg.

  In S106, the ECU 20 calculates an ignition timing SA2 that can achieve the target value Tetrg obtained in S105 in the advance side of the MBT. At that time, the ECU 20 can use the map of FIG. 4 described above. The ignition timing SA2 thus obtained corresponds to the second ignition timing according to the present invention. Hereinafter, the ignition timing SA2 obtained in S106 is referred to as a second ignition timing SA2.

  In S107, the ECU 20 sets the second ignition timing SA2 obtained in S106 as the target ignition timing SAtrg.

  In this case, the ECU 20 operates the spark plug 14 in accordance with the target ignition timing SAtrg set in S107. That is, the spark plug 14 operates at a timing earlier than MBT. As a result, it is possible to reduce the generated torque of the internal combustion engine 1 to the target value Tetrg even in a situation where the first ignition timing SA1 that can achieve the target value Tetrg is limited by the retard guard ksa.

  Thus, when ECU20 performs the processing routine of FIG. 3, the 1st acquisition means, 2nd acquisition means, and control means concerning this invention are implement | achieved.

  Therefore, when it is necessary to reduce the generated torque of the internal combustion engine 1 to the target value Tetrg, the target ignition timing is retarded from the MBT as long as the ignition timing that can achieve the target value Tetrg is the timing before the retard guard. Therefore, the energy generated by the combustion of the air-fuel mixture can be used as much as possible.

  When the ignition timing at which the target value can be achieved is later than the retard guard, the target ignition timing is advanced from the MBT to reduce the torque, so that the generated torque of the internal combustion engine 1 is made as much as possible. The target value Tetrg can be approximated. As a result, an increase in vibration, an increase in noise, and an increase in the amount of unburned fuel due to the increase in the engine speed Ne are reduced as much as possible.

<Example 2>
Next, a second embodiment of the present invention will be described with reference to FIG. Here, a configuration different from that of the first embodiment will be described, and description of the same configuration will be omitted.

  In the first embodiment described above, an example in which the target ignition timing SAtrg is advanced from the MBT only when the first ignition timing SA1 is later than the retard guard ksa has been described, but in the present embodiment, the first ignition timing is set. An example will be described in which the target ignition timing SAtrg is advanced from the MBT when SA1 becomes slower than the retard guard ksa and when the fluctuation amount of the engine speed Ne exceeds the allowable value.

  Even if the first ignition timing SA1 is set to the target ignition timing SAtrg on the condition that the first ignition timing SA1 is the timing before the retard guard ksa, misfire may occur depending on the use environment of the internal combustion engine 1. It can happen. For example, when the internal combustion engine 1 is used at an extremely low temperature, the in-cylinder pressure is unlikely to increase. Therefore, if the ignition timing SA is retarded from the compression top dead center, misfire is likely to occur. If the target ignition timing SAtrg continues to be retarded from the MBT after the misfire has occurred, the internal combustion engine 1 may stall.

  Therefore, in this embodiment, the ECU 20 detects the fluctuation amount of the engine speed Ne when the first ignition timing SA1 is set to the target ignition timing SAtrg, and the detected fluctuation amount exceeds the allowable value. The target ignition timing SAtrg is switched from the first ignition timing SA1 to the second ignition timing SA2. When the target ignition timing SAtrg is thus determined, it is possible to suppress the occurrence of misfire and the stall of the internal combustion engine 1.

  Hereinafter, the control procedure of the ignition timing in the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a processing routine executed by the ECU 20 when a torque down request is generated. In FIG. 5, the same steps as those in the processing routine of the first embodiment described above (see FIG. 3) are denoted by the same reference numerals.

In the processing routine of FIG. 5, the ECU 20 proceeds to S201 after executing S104. In S201, the ECU 20 calculates a fluctuation amount ΔNe of the engine speed Ne based on the output signal of the crank position sensor 18.

  In S202, the ECU 20 determines whether or not the fluctuation amount ΔNe of the engine speed Ne calculated in S201 is less than an allowable value ΔNeall. For example, the allowable value ΔNearl is a value set to be smaller than the fluctuation amount of the engine speed Ne when a misfire occurs.

  If an affirmative determination is made in S202 (ΔNe <ΔNeall), the ECU 20 ends the execution of this routine. On the other hand, if a negative determination is made in S202 (ΔNe ≧ ΔNeall), the ECU 20 executes the processing of S105 to S107, thereby changing the target ignition timing SAtrg from the first ignition timing SA1 to the second ignition timing SA2. change. In this case, torque reduction of the internal combustion engine 1 can be achieved while suppressing misfires and stalls.

  Therefore, according to the ignition control system for the internal combustion engine of the present embodiment, the target ignition timing SAtrg is advanced from the MBT only when it is difficult to ensure the combustion stability of the internal combustion engine 1. As a result, energy can be used as long as the combustion stability of the internal combustion engine 1 can be ensured.

<Example 3>
Next, a third embodiment of the present invention will be described with reference to FIG. Here, a configuration different from the second embodiment described above will be described, and the description of the same configuration will be omitted.

  In the second embodiment described above, if the fluctuation amount ΔNe of the engine speed Ne exceeds the allowable value ΔNearl when the first ignition timing SA1 is set to the target ignition timing SAtrg, the target ignition timing SAtrg is set to the first ignition timing. Although the example of changing from SA1 to the second ignition timing SA2 has been described, in this embodiment, when the second ignition timing SA2 is set to the target ignition timing SAtrg, the fluctuation amount ΔNe of the engine speed Ne becomes the allowable value ΔNeall. Exceeding this will describe an example in which the target ignition timing SAtrg is changed from the second ignition timing SA2 to an ignition timing after MBT.

  FIG. 6 is a flowchart showing a processing routine executed by the ECU 20 when a torque down request is generated. In FIG. 6, the same steps as those in the processing routine of the second embodiment described above (see FIG. 5) are denoted by the same reference numerals.

  In the processing routine of FIG. 6, the ECU 20 proceeds to S301 after executing S107. In S301, the ECU 20 performs misfire determination processing when the spark plug 14 is operated according to the target ignition timing SAtrg (= SA2) set in S107. As the execution method of the misfire determination process, various conventionally known methods can be employed. For example, the ECU 20 can detect the occurrence of misfire based on changes in the angular acceleration of the crankshaft 17 and the in-cylinder pressure after the ignition plug 14 is actuated. The detection unit according to the present invention is realized by the ECU 20 executing the process of S301.

  In S302, the ECU 20 determines whether or not a misfire has been detected in S301. If a negative determination is made in S302, the ECU 20 ends the execution of this routine. On the other hand, if a positive determination is made in S302, the ECU 20 proceeds to S303.

  In S303, the ECU 20 changes the target ignition timing SAtrg to an ignition timing later than MBT. At this time, in order to make the generated torque of the internal combustion engine 1 as close as possible to the target value Tetrg, it is desirable to set the target ignition timing SAtrg to a timing equivalent to the retard guard ksa.

  Note that if an affirmative determination is made in S302, the ECU 20 immediately tries at least one reignition without executing the process in S303, and proceeds to S303 if misfire is detected even after the reignition is performed. Good. Re-ignition may be attempted in a cycle in which a misfire is detected, or may be attempted in the next cycle or later.

  As described above, when the logic for changing the target ignition timing SAtrg triggered by the occurrence of misfire when the second ignition timing SA2 is set to the target ignition timing SAtrg is incorporated in the processing routine, combustion stability The target ignition timing SAtrg can be advanced as much as possible. That is, the probability that the generated torque of the internal combustion engine 1 can be made equal to the target value Tetrg is increased.

  This embodiment and the second embodiment described above can be executed in combination. In that case, it is possible to reduce the torque of the internal combustion engine 1 while more reliably suppressing misfires and stalls.

It is a figure which shows schematic structure of the ignition control system of an internal combustion engine. It is a figure which shows the measurement result of the engine speed at the time of start-up of an internal combustion engine, and an exhaust air fuel ratio. It is a flowchart which shows the processing routine in a 1st Example. It is a figure which shows the correlation of the torque of an internal combustion engine, and ignition timing. It is a flowchart which shows the processing routine in a 2nd Example. It is a flowchart which shows the processing routine in a 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Intake port 4 ... Exhaust port 5 ... Fuel injection valve 6 ... Throttle valve 7.・ ・ ・ ・ Intake pressure sensor 8 ・ Air flow meter 9 ・ Exhaust gas purification device 10 ・ ・ ・ ・ Intake valve 11 ・ ・ ・ ・ Exhaust valve 12 ・ ・ ・ ・ Intake side camshaft 13 ・ ・・ ・ Exhaust camshaft 14 ・ ・ ・ ・ Spark plug 15 ・ ・ ・ ・ Piston 16 ・ ・ ・ ・ Connecting rod 17 ・ ・ ・ ・ Crankshaft 18 ・ ・ ・ ・ Crank position sensor 19 ・ ・ ・ ・ Water temperature sensor 20 ・... ECU
30 ... Air intake passage 40 ... Air exhaust passage 41 ... Air-fuel ratio sensor

Claims (5)

In an ignition control system for an internal combustion engine that controls ignition timing so that a physical quantity correlated with a generated torque of a spark ignition internal combustion engine matches a target value,
First acquisition means for acquiring a first ignition timing that is an ignition timing capable of achieving the target value in a range retarded from MBT;
Second acquisition means for acquiring a second ignition timing that is an ignition timing capable of achieving the target value in a range on the advance side from MBT;
When the first ignition timing is earlier than or equivalent to a predetermined retard guard, the first ignition timing is set as a target ignition timing, and the first ignition timing is later than the retard guard. A control means for setting the second ignition timing as a target ignition timing,
An ignition control system for an internal combustion engine, comprising:   2. The control means according to claim 1, wherein the control means changes the target ignition timing from the first ignition timing to the second ignition timing when the fluctuation amount of the physical quantity exceeds an allowable amount when the first ignition timing is set to the target ignition timing. An ignition control system for an internal combustion engine, wherein the ignition timing is changed to an ignition timing. In Claim 1 or 2, further comprising a detecting means for detecting misfire in the internal combustion engine,
If the detection means detects misfire when the second ignition timing is set to the target ignition timing, the control means changes the target ignition timing from the second ignition timing to a third ignition timing after MBT. An ignition control system for an internal combustion engine.   4. The internal combustion engine ignition control system according to claim 3, wherein the third ignition timing is an ignition timing simultaneously with the retard guard. 5. The ignition control system for an internal combustion engine according to claim 1, wherein the physical quantity is an engine speed of the internal combustion engine.

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