JP2011236794A - Ignition control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit multi-discharge only when constantly-favorable ignition discharge can be obtained without causing large cost-up, and to avoid the continuation of the multi-discharge when there is a possibility that in-cylinder pressure may be raised due to an effect that mixed air is ignited and burnt.SOLUTION: An ignition control device calculates a rotational position of an internal combustion engine 1, when the combustion pressure generated upon ignition and burning of mixed air by a spark discharged from an ignition plug 2 at the point of discharge starting timing becomes equal to a discharge allowable maximum pressure value of the ignition plug 2, as a forcible finishing position of multi-discharge control. When an actual rotational position of the internal combustion engine 1 reaches the forcible finishing position of the multi-discharge control, the multi-discharge control at a combustion cycle at which the multi-discharge control is currently performed is forcibly finished.

Description

  The present invention relates to an ignition control device for an internal combustion engine, and more particularly to an ignition control device for an internal combustion engine that performs multiple discharge.

  Multiple discharge means that a high voltage is intermittently generated in the secondary winding of the ignition coil by repeatedly energizing and interrupting the current flowing in the primary winding of the ignition coil, and the mixture in the combustion chamber is ignited. In addition, this is an ignition method in which spark discharge by the spark plug is repeatedly generated in one combustion cycle starting from a set discharge start timing (generally referred to as ignition timing). A technique proposed by Patent Document 2 is known.

  If multiple discharges as described above are performed, it becomes possible to ignite a mixture that is difficult to ignite even if the formation state of the mixture deteriorates and the ignition timing is delayed or the flame goes out. In other words, it is possible to re-ignite a flame that has once disappeared, and there is an advantage that the probability of misfire can be reduced. Therefore, in recent years, ignition control devices for internal combustion engines that employ multiple discharge in preparation for when ignitability deteriorates are becoming widespread.

Japanese Patent Application Laid-Open No. 11-148452 JP 2008-261230 A

  Patent Document 1 discloses a basic control method for multiple discharge in which spark discharge from a spark plug is repeatedly generated during one combustion cycle for the purpose of obtaining the above-described advantages. However, in the multiple discharge disclosed in Patent Document 1, even when the air-fuel mixture is ignited and burned by the spark discharged from the spark plug at the time of the discharge start timing, that is, the spark first emitted. Multiple discharges are continued until a predetermined number of discharges or a predetermined time elapses.

  By the way, when the air-fuel mixture is ignited and combustion starts, the pressure in the cylinder rises as the flame grows. Therefore, the spark plug must discharge sparks in a high-pressure atmosphere due to combustion. The higher the atmospheric pressure at which the spark plug is placed, the higher the dielectric breakdown voltage in the plug gap (the voltage necessary to generate a spark discharge in the plug gap), and the faster the wear and deterioration of the plug electrode. Inevitable. If the plug electrode is further worn or deteriorated, the gap of the plug gap is widened and the dielectric breakdown voltage is expected to be further increased. In the worst case, there is a concern that no spark can be generated.

  In order to prevent such a situation from occurring, it is conceivable that the multiple discharge is interrupted by quickly detecting that combustion has started in the cylinder. Regarding this, for example, as described in Patent Document 2, a method of detecting the ionic current generated when burning and terminating the multiple discharge, or a method of directly detecting the pressure state in the cylinder and performing the multiple discharge. Although the method of ending is mentioned, in any case, it is necessary to add an expensive combustion detection means for detecting the combustion state, and it is not easy to adopt because it causes a significant cost increase.

  Another problem when performing multiple discharge is a decrease in discharge performance due to a decrease in battery voltage when the energization periods of the primary windings overlap between a plurality of cylinders. Usually, a current of several amperes to several tens of amperes is passed through the primary winding of the ignition coil, so that the battery voltage greatly decreases when the primary winding is energized. For this reason, if the energization periods overlap between a plurality of cylinders by performing multiple discharge, it is expected that the battery voltage will be significantly reduced and a desired breaking current cannot be secured. If so, there is a concern that the energy supplied to the ignition coil is reduced, and a good spark discharge cannot be obtained.

  Accordingly, a first object of the present invention is to allow multiple discharges only when a good spark discharge can always be obtained without a significant increase in cost, and the air-fuel mixture ignites and burns in the cylinder. An object of the present invention is to provide an ignition control device for an internal combustion engine that prevents multiple discharges from continuing when there is a possibility that the pressure is rising.

  In addition, the second object is that the energization periods of the primary windings between a plurality of cylinders overlap during execution of multiple discharges, leading to a significant drop in battery voltage, making it impossible to secure a desired cut-off current, and the ignition coil It is an object of the present invention to provide an ignition control device for an internal combustion engine that avoids a decrease in energy supplied to the engine and a failure to obtain a good spark discharge.

  An ignition control device for an internal combustion engine according to the present invention has a primary winding and a secondary winding, and generates a high voltage in the secondary winding when an energization current to the primary winding is interrupted. By controlling the timing of energizing the ignition coil, the ignition plug that generates a spark discharge when a high voltage generated in the secondary winding of the ignition coil is applied, and the combustion of the primary winding of the ignition coil An ignition control device for an internal combustion engine comprising: multiple discharge control means for performing multiple discharge control for repeatedly generating spark discharge from the spark plug starting from a discharge start timing set during a cycle. The maximum allowable discharge pressure value set as the maximum value of the atmospheric pressure of the spark plug for obtaining a spark discharge, and the air-fuel mixture by the spark discharged from the spark plug at the time of the discharge start timing. Based on the two known information of the combustion pressure-rotational position characteristic set as the relationship between the combustion pressure generated when ignition / combustion and the rotational position of the internal combustion engine, the spark plug at the timing of the discharge start timing The rotational position of the internal combustion engine when the combustion pressure generated when the air-fuel mixture is ignited / combusted by the spark discharged from is equal to the discharge allowable maximum pressure value is calculated as the multiple discharge control forced end position, When the actual rotational position of the engine reaches the multiple discharge control forced end position, a multiple discharge forced end means for forcibly terminating the multiple discharge control in the combustion cycle in which the multiple discharge control is currently being executed is provided. .

  According to the ignition control device for an internal combustion engine according to the present invention, when it is predicted that it is difficult to obtain a good spark discharge, the multiple ignition is forcibly terminated and the unnecessary multiple ignition is not continued. Since multiple discharge is continued only when good spark discharge can be obtained, combustion starts in the cylinder, the cylinder pressure increases, and the breakdown voltage may be excessively increased. Multiple discharges can be continued to prevent the plug electrode from being worn out earlier. Then, without adding an expensive combustion detection means for detecting the combustion state, such as an ion current detection sensor or an in-cylinder pressure sensor, the above-described effect can be realized without significant cost increase without changing the existing ignition control device. it can.

1 is an overall configuration diagram illustrating an internal combustion engine ignition control device according to Embodiment 1 of the present invention; 1 is a configuration diagram of an ignition control device for an internal combustion engine according to Embodiment 1 of the present invention. FIG. It is a timing chart for demonstrating the operation | movement in multiple discharge. It is a characteristic view which shows the relationship between the atmospheric pressure in which the ignition plug was placed, and the dielectric breakdown voltage. It is a characteristic view which shows the relationship between the cylinder pressure when an air-fuel mixture burns, and the rotation position of an internal combustion engine. It is a flowchart figure which shows the control action of the ignition control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. FIG. 6 is a timing chart illustrating an operation during multiple discharge over a plurality of continuous cylinders. It is a flowchart figure which shows the control action of the ignition control apparatus of the internal combustion engine which concerns on Embodiment 2 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an ignition control device for an internal combustion engine according to the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and includes various design changes.

Embodiment 1 FIG.
1 is an overall configuration diagram illustrating an ignition control apparatus for an internal combustion engine according to Embodiment 1 of the present invention.
In FIG. 1, a combustion chamber 1b of a cylinder 1a in an internal combustion engine 1 is provided with an intake valve 1c, an exhaust valve 1d, and a piston 1e, and further, an ignition plug 2 and a fuel injection so as to face the combustion chamber 1b. A valve 3 is provided. In the internal combustion engine 1, the intake air amount is adjusted by an electronic control throttle 5 provided in the intake passage 4. The electronic control throttle 5 includes a butterfly valve 5a, a motor 5b for driving the butterfly valve 5a, and a throttle opening degree sensor 5c for detecting the opening degree of the butterfly valve 5a.

  An engine control unit (hereinafter referred to as an ECU) 6 acquires an output signal of an accelerator position sensor 8 that detects the depression position of the accelerator pedal 7, sends a control signal to the motor 5b, and outputs a control signal from the throttle opening sensor 5c. Based on the butterfly valve opening signal, the butterfly valve 5a is controlled to an appropriate opening. The crank angle sensor 9 detects the crank angle of the crankshaft 1f, the cam angle sensor 10 detects the cam angle of the intake-side camshaft 1g, and the water temperature sensor 11 detects the temperature of the cooling water of the internal combustion engine 1. To do.

  The ECU 6 acquires output signals from the accelerator position sensor 8, the crank angle sensor 9, the cam angle sensor 10, the air flow sensor 12, the water temperature sensor 11, and other various sensors (not shown), and the ignition timing, the fuel injection amount, etc. To decide. Then, based on each determined value, the fuel injection valve 3 is driven to inject and supply fuel into the combustion chamber 1b, and the ignition coil 13 connected to the ignition plug 2 is driven to thereby connect the plug of the ignition plug 2. Discharge sparks from the gap.

  The intake air from which dust and dirt have been removed by the air cleaner 14 is flowed by the air flow sensor 12 and then guided to the surge tank 15 through the electronic control throttle 5, and from the surge tank 15 to the intake valve 1c. And is introduced into the combustion chamber 1b. The intake air introduced into the combustion chamber 1b and the fuel injected from the fuel injection valve 3 are mixed to form an air-fuel mixture, and the air-fuel mixture is ignited by the spark discharge of the spark plug 2 and burns.

The combustion pressure of the air-fuel mixture is transmitted to the piston 1e to reciprocate the piston 1e. The reciprocating motion of the piston 1e is transmitted to the crankshaft 1f via the connecting rod 1h, where it is converted into rotational motion and taken out as the output of the internal combustion engine 1. The air-fuel mixture after combustion becomes exhaust gas, is discharged to the exhaust manifold 16 through the exhaust valve 1d, is purified by the catalyst 17, and is discharged to the atmosphere.

FIG. 2 is a configuration diagram of the ignition control device for the internal combustion engine according to the first embodiment. In this figure, only one cylinder is shown.
As shown in FIG. 2, the ignition control apparatus according to the first embodiment includes an ignition plug 2, an ignition coil 13, and an EUC 6. The interior of the ignition coil 13 includes a primary winding 13a, a secondary winding 13b, and a driver circuit 13c. The ignition coil 13 is configured such that the battery voltage V1 connected to the primary winding 13a is boosted by the secondary winding 13b and supplied to the spark plug 2. The driver circuit 13c is connected to the ECU 6, and energization of the primary winding 13a is controlled based on a control signal IB sent from the ECU 6.

  In order to discharge sparks from the plug gap of the spark plug 2 at the discharge start timing, the ECU 6 sets the control signal IB to the H level for a predetermined period immediately before the discharge start timing to turn on the driver circuit 13c. While the driver circuit 13c is on, the battery voltage V1 is applied to the primary winding 13a, and the primary current I1 flows through the primary winding 13a.

  When the rotational position of the internal combustion engine 1 reaches the discharge start timing, the ECU 6 switches the control signal IB from the H level to the L level to turn off the driver circuit 13c. When the driver circuit 13c is switched from on to off, the primary current I1 that has been flowing in the primary winding 13a until then is cut off, and the secondary winding 13b that is electromagnetically coupled to the primary winding 13a is blocked. A high voltage V2 is generated. When this high voltage V2 is applied to the spark plug 2, dielectric breakdown occurs in the plug gap of the spark plug 2, and a spark is discharged to cause the secondary current I2 to flow. When a spark is discharged from the plug gap of the spark plug 2, the air-fuel mixture in the combustion chamber 1b is ignited and starts to burn.

  FIG. 3 is a timing chart illustrating the operation of multiple discharge control. In FIG. 3, the control signal IB described in FIG. 2, battery voltage (power supply voltage applied to the primary winding 13a) V1, current I flowing in the primary winding 13a, and high voltage generated in the secondary winding 13b. The operation when multiple discharge is performed using (voltage applied to the plug gap) V2 and the current I2 flowing through the plug gap when dielectric breakdown occurs in the plug gap will be described. FIG. 3 shows an example in which a total of five discharges of the first spark discharge (main discharge: one time) and multiple discharge (four times) discharged at the timing of the discharge start timing are performed. Yes.

  First, in order to perform the first spark discharge, the ECU 6 sets the control signal IB to the H level at the position ON1 that is a predetermined period K1 before the rotation position IG1 that is the discharge start timing. Accordingly, since the primary current I1 flows out to the primary winding 13a from ON1 to IG1 where IB is at the H level, the battery voltage V1 decreases as the primary current I1 increases.

  When the first discharge position IG1 is changed, the ECU 6 switches the control signal IB from the H level to the L level. When the control signal IB is switched from the H level to the L level, the primary current I1 that has been flowing through the primary winding 13a until then is interrupted, so that a high voltage V2 is generated in the secondary winding 13b. When the high voltage V2 generated in the secondary winding 13b is applied to the plug gap, dielectric breakdown occurs in the plug gap, a spark is discharged, and the secondary current I2 flows and attenuates all at once.

Subsequently, in order to perform multiple discharge (repetition of the second and subsequent spark discharges), the ECU 6 determines a position IG2 after a predetermined period K2 from the first discharge position IG1 as the second discharge timing, and the second time The control signal IB is again set to the H level at the position ON2 before the predetermined period K3 from the discharge position IG2. As a result, the primary current I1 flows out to the primary winding 13a during the period from ON2 to IG2 in which the control signal IB is at the H level.
As the voltage increases, the battery voltage V1 decreases. When the control signal IB is set to the H level, the primary current I1 starts to flow through the primary winding 13a, but when energy remains in the ignition coil 13 when the first discharge is completed. As shown in the primary current I1 at the time of ON2, the primary current I1 does not start from zero.

  When the second discharge position IG2 is changed, the ECU 6 switches the control signal IB from the H level to the L level. When the control signal IB is switched from the H level to the L level, the primary current I1 that has been flowing through the primary winding 13a until then is cut off, so that the second high voltage V2 is generated in the secondary winding 13b. . When the high voltage V2 generated in the secondary winding 13b is applied to the plug gap, dielectric breakdown occurs in the plug gap, and the second spark is discharged.

  Thereafter, the third to fifth discharges are the same as the second discharge operation described above, and the control signal IB is set to the H level from ON3 to IG3, from ON4 to IG4, and from ON5 to IG5. As a result, the third to fifth discharges are performed at each position of IG3, IG4, and IG5.

Next, a dielectric breakdown voltage (also referred to as a required voltage) in the spark plug 2 will be described. Generally, the breakdown voltage of the spark plug 2 is determined by Paschen's law expressed by the equation (1). That is,
V = K × P × d + C (1)
Where V: dielectric breakdown voltage
K: Proportional constant
P: Pressure in the combustion chamber 1b at the time of ignition
d: Plug gap
C: Dielectric breakdown when the plug gap d is wide or the pressure P in the combustion chamber 1b at the time of ignition is high from the constant equation (1) determined by the electrode temperature of the spark plug 2 and the concentration of the air-fuel mixture. It is clear that the voltage V increases.

  As the dielectric breakdown voltage V increases, the electrical shock in the plug gap where sparks are released increases, and wear of the plug gap is accelerated. In addition, since the energy required for causing dielectric breakdown also increases, the secondary current I2 decreases, the discharge duration is shortened, and the ignitability is deteriorated. In the worst case, it is also considered that dielectric breakdown does not occur in the plug gap and sparks cannot be discharged. In view of this, it is desirable not to discharge in a situation where the dielectric breakdown voltage V becomes too high.

  FIG. 4 is a characteristic diagram showing the relationship between the atmospheric pressure P where the spark plug 2 is placed and the dielectric breakdown voltage V. Here, assuming that the maximum dielectric breakdown voltage at which good discharge cannot be realized is Vmax, the discharge allowable maximum pressure value Pmax at that time is determined. If this is replaced with a cylinder, a discharge with a good dielectric breakdown voltage can be realized if the discharge is limited only under the condition that the pressure P in the cylinder generated by combustion is equal to or less than the maximum discharge allowable pressure value Pmax. The limit dielectric breakdown voltage Vmax that does not disappear is not exceeded, and it is possible to discharge only when a good spark discharge can always be obtained. As a result, premature plug gap wear is avoided.

  The limit breakdown voltage Vmax at which good discharge cannot be realized varies depending on the compression ratio, the design specification of the spark plug 2, and the like, so that the spark plug using the target internal combustion engine and the ignition control device in advance is used. A verification test related to wear resistance and pressure resistance is performed, and further determination is made taking into account related specifications and variation widths of specification values, and the result is stored in a storage element in the ECU 6.

  FIG. 5 is a characteristic diagram showing the relationship between the pressure in the cylinder and the rotational position of the internal combustion engine when the air-fuel mixture burns. In FIG. 5, the cylinder pressure when the air-fuel mixture ignites and burns when the first discharge is performed at the discharge start timing IG1, where the rotational position of the internal combustion engine is the horizontal axis and the cylinder pressure is the vertical axis. Behavior A (curve drawn with a solid line) and behavior B of the cylinder pressure when the internal combustion engine is motored (when the air-fuel mixture is not burned) (curve drawn with a one-dot chain line) is doing. In the example of FIG. 5, it is assumed that discharge (a total of five discharges) is performed at each position of IG1, IG2, IG3, IG4, and IG5. Further, the horizontal axis of FIG. 5 shows two compression strokes: a compression stroke in which the piston 1e rises from BDC (Bottom Dead Center) to TDC (Top Dead Center), and an expansion stroke in which the piston 1e descends from TDC to BDC. Shown as the duration of the journey.

  In FIG. 5, when the air-fuel mixture is ignited and combusted when discharged at the first discharge position IG1, the cylinder pressure at the time of IG1 is P1 which is the same as when the motoring operation is performed (curve B). However, at the second discharge position IG2, since combustion has started by the first (first) discharge, P2 is slightly higher than the pressure during the motoring operation, and the subsequent third to fifth discharge positions IG3. In IG4 and IG5, the pressure in the cylinder rises due to combustion, and the in-cylinder pressure rises all at once like P3, P4 and P5, respectively.

  Here, as described with reference to FIG. 4, if the discharge allowable maximum pressure value Pmax is between the pressures P3 and P4, the discharge positions exceeding the discharge allowable maximum pressure value Pmax, that is, IG4 and IG5 It is desirable not to discharge at the location.

  That is, as shown in FIG. 5, when multiple discharge is performed with the discharge start timing IG1 as a starting point, the discharge position IGE corresponding to the pressure value Pmax at which the dielectric breakdown voltage does not exceed Vmax is estimated, and after the IGE position If the discharge is prohibited, it is possible to limit the multiple discharge to be performed only when the dielectric breakdown voltage becomes Vmax or less.

  The pressure value Pmax at which the dielectric breakdown voltage does not exceed Vmax and the discharge position IGE differ depending on the rotational speed of the internal combustion engine, operating load, discharge start timing, environmental conditions when the internal combustion engine is operated, and the like. The relationship between the rotational position of the internal combustion engine and the in-cylinder pressure when discharging at the discharge start timing for each operating state and each environmental condition using the target internal combustion engine and ignition control device is measured in advance. This is stored in the storage element.

Next, the control operation of the ignition control apparatus according to Embodiment 1 will be described with reference to the flowchart of FIG.
In FIG. 6, first, in step S101, the total number of discharges N is set. As an example, N = 5 (when discharging control is performed five times in total) is set.

  Subsequently, in step S102, a target energization off timing Coff for performing the first discharge at the discharge start timing IG1 is determined (IG1 is substituted for Coff), and in step S103, the primary for performing the discharge at the discharge start timing IG1. The target energization on timing Con that is the energization start position of the winding 13a is determined (Con = Coff−K1 is calculated).

  In the next step S104, it is determined whether or not the target energization off timing Coff is a position before the IGE that is the multiple discharge prohibition position. Here, if Coff <IGE (in the case of YES), the process proceeds to step S105 and discharge control described later is executed. On the other hand, when Coff ≧ IGE (in the case of NO), the discharge control is stopped and the process is exited. That is, step S104 functions as multiple discharge forced termination means.

  When the process proceeds from step S104 to step S105, in the next steps S105 to S107, the current rotational position ANG is read and waits until the current rotational position ANG reaches the target energization on timing Con, and ANG = Con. At the time, energization of the primary winding 13a of the ignition coil 13 is started (the control signal IB is switched from L level to H level).

  In the next steps S108 to S110, the current rotational position ANG is read again and waits until the current rotational position ANG reaches the target energization off timing Coff. When ANG = Coff, the primary winding is performed. The energization of the line 13a is terminated (the control signal IB is switched from the H level to the L level).

  As described above, the primary winding 13a is energized from the rotation position ON1 to the discharge start timing IG1, and the first discharge is performed at the time of IG1.

  In the next step S111, the total number of discharges N is decremented (N ← N−1), and the process proceeds to step S112.

  In step S112, it is determined whether the total number of discharges N> 0. Now, since the total number of discharges N> 0, it is determined YES, and the process proceeds from step S112 to step S113.

  Subsequently, in step S113, a target energization off timing Coff for performing the second discharge at the discharge timing IG2 is determined (Coff ← Coff + K2 is calculated), and in step S114, the discharge is performed at the second discharge timing IG2. The target energization on timing Con that is the energization start position of the primary winding 13a is determined (Con = Coff−K3 is calculated), and then the process returns to step S104.

  After returning from step S114 to step S104, it is determined whether the target energization off timing Coff is a position before the IGE which is the multiple discharge prohibition position in step S104 as described above. Since Coff <IGE, the process proceeds from step S104 to step S105. In steps S105 to S110, the same process as described above is performed to execute the second discharge, and then the process from step S111 to step S114 is performed for the third time. The target energization off timing Coff and the target energization on timing Con at the discharge timing are determined, and the process returns to step S104.

  When the same loop process proceeds and the target energization off timing Coff and the target energization on timing Con for the fourth discharge are determined and the process returns from step S114 to step S104, this time the target energization off timing Coff Since the position is IG4, Coff (= IG4) <IGE is not established (NO determination), the process does not proceed to step S105, and the discharge control is stopped and the process is terminated.

  If the fourth discharge position and the fifth (last) discharge position are positions before the multiple discharge prohibition position IGE, the fourth and fifth discharges are also performed, and then the step As a result of the process of S111, N = 0, and a NO determination is made in step S112 to exit the process.

As described above, according to the ignition control device for an internal combustion engine according to the first embodiment, the multiple discharge is continued only when a good spark discharge can always be obtained without increasing the cost compared to the conventional control device. For example, when the discharge start timing is set for each engine operating state in the development stage of the internal combustion engine, the limit dielectric breakdown voltage Vmax at which good discharge cannot be realized is exceeded. Even if such a multiple discharge period is set, the discharge can be performed only when a good spark discharge can always be obtained due to the limitation of the multiple discharge period programmed in the ECU 6. As a result, it is possible to prevent premature wear of the plug electrode due to continuation of unnecessary multiple discharge.

Embodiment 2. FIG.
Next, an internal combustion engine ignition control apparatus according to Embodiment 2 of the present invention will be described. The overall configuration of the internal combustion engine and the ignition control device in the second embodiment are the same as those in FIG. 1 and FIG. In the following description, description will be made with reference to FIGS. 1 and 2 as appropriate.

FIG. 7 is a timing chart describing the operation during multiple discharge over a plurality of continuous cylinders.
The upper part of FIG. 7 shows a time chart of the discharge operation in an arbitrary cylinder when multiple discharge is executed. The lower part of FIG. 7 shows the next cylinder in which multiple discharge is executed next to the arbitrary cylinder. The time chart of the discharge operation in is shown. In the chart drawn with a solid line in FIG. 7, the energization timing for performing the fourth discharge in the arbitrary cylinder (period from ON4 to IG4) is the first half of the energization timing for performing the first discharge in the next cylinder. It is illustrated as a case where it overlaps with (the first half of the period of ON1 ′ to IG1 ′).

  Here, in an arbitrary cylinder, the decrease amount v1 of the battery voltage V1 when the energization is not overlapped in a plurality of cylinders, whereas the decrease amount v2 ( > V1).

  As the amount of decrease in the battery voltage V1 increases, the degree of increase in the primary current I1 flowing through the primary winding 13a of the ignition coil 13 becomes dull, and the peak current at the time when the primary current I1 is cut off is overlapped by multiple cylinders. In contrast to the value i1 when there is no current, when the energization of a plurality of cylinders overlaps, the current increase becomes dull, and this decreases to i2 (<i1). As a result, the peak value c1 of the discharge current I2 and the discharge duration time t1 when the energization is not overlapped in a plurality of cylinders, whereas the peak value c2 of the discharge current I2 is also the discharge duration when the energization is overlapped in a plurality of cylinders. Both t2 decrease.

  Also in the next cylinder, the degree of increase in the primary current I1 is affected by the decrease in the battery voltage V1 in the first half of the energization timing for performing the first discharge (the first half of the period from ON1 ′ to IG1 ′). The value i3 of the primary current I1 at the time IG1 ′ at which the first energization is cut off becomes smaller than the peak value i4 when the energization does not overlap in a plurality of cylinders. As a result, since the energization in the plurality of cylinders overlapped, the peak value c3 of the discharge current I2 and the discharge duration t3 both the peak value c4 of the discharge current I2 and the discharge duration t4 when the energization in the plurality of cylinders did not overlap. Reduced against.

  As described above, when the peak value of the discharge current I2 or the discharge duration time is reduced below a desired value, the ignitability of the air-fuel mixture is deteriorated, or the discharge spark is easily blown off by the flow in the cylinder. However, it is not desirable that the energization periods between a plurality of cylinders overlap.

On the other hand, the chart drawn with a dotted line in FIG. 7 is illustrated as a case where energization after the fourth time in an arbitrary cylinder is prohibited in order to avoid overlap of discharge periods in the arbitrary cylinder and the next cylinder.
By prohibiting energization after the fourth time in the arbitrary cylinder, a total of three discharges are executed in the arbitrary cylinder and the multiple discharge is terminated. As a result, in the next cylinder, an increase in the battery voltage V1 due to the overlapping of energization in a plurality of cylinders is avoided, and the primary current I1 at the time point IG1 ′ when the first energization is cut off is the normal value i4. The peak value c4 of the current I2 and the discharge duration t4 are ensured.

Next, the control operation of the ignition control apparatus according to Embodiment 2 will be described with reference to the flowchart of FIG.
In FIG. 8, first, in step S201, the total number of discharges N is set. As an example, N = 5 (when discharging control is performed five times in total) is set.

  Subsequently, in step S202, a target energization off timing Coff for performing the first discharge at the discharge start timing IG1 is determined (IG1 is substituted for Coff), and in step S303, the primary for performing the discharge at the discharge start timing IG1. The target energization on timing Con that is the energization start position of the winding 13a is determined (Con = Coff−K1 is calculated).

  In the next step S204, it is determined whether or not the target energization off timing Coff in the current cylinder is a position before the energization start position ON1 'for the first discharge in the next cylinder. Here, if Coff <ON1 ′ (in the case of YES), the process proceeds to step S205 and discharge control described later is executed. On the other hand, if Coff ≧ ON1 ′ (NO), the discharge control is stopped and the process is exited. That is, step S204 functions as multiple discharge overlap prohibiting means.

  When the process proceeds from step S204 to step S205, in the next steps S205 to S207, the current rotational position ANG is read and waits until the current rotational position ANG reaches the target energization on timing Con, and ANG = Con. At the time, energization of the primary winding 13a of the ignition coil 13 is started (the control signal IB is switched from L level to H level).

  In the next steps S208 to S210, the current rotational position ANG is read again and waits until the current rotational position ANG reaches the target energization off timing Coff. When ANG = Coff, the ignition coil 13 is reached. The primary winding 13a is turned off (the control signal IB is switched from H level to L level).

  As described above, the primary winding 13a is energized from the rotational position ON1 to the IG1 position, and the first discharge in the current cylinder is executed at the time of IG1.

  In the next step S211, the total number of discharges N is decremented (N ← N−1), and the process proceeds to step S212.

  In step S212, it is determined whether N> 0. Since N> 0 yet, the determination is YES and the process proceeds from step S212 to step S213.

  Subsequently, in step S213, a target energization off timing Coff for performing the second discharge at the discharge timing IG2 is determined (Coff ← Coff + K2 is calculated), and in step S214, the discharge is performed at the second discharge timing IG2. The target energization on timing Con that becomes the energization start position of the primary winding 13a is determined (Con = Coff−K3 is calculated), and then the process returns to step S204.

After returning from step S214 to step S204, as described above, in step S204, whether or not the target energization off timing Coff in the current cylinder is a position before the energization start position ON1 ′ for the first discharge in the next cylinder. But for now,
Since Coff <IG1 ′, the process proceeds from step S204 to step S205. In steps S205 to S210, the same process as described above is performed, and the second discharge in the current cylinder is executed. Subsequently, the process from step S211 to step S214 is performed. The target energization off timing Coff and the target energization on timing Con at the third discharge timing in the current cylinder are determined, and the process returns to step S204.

  Then, when the same loop process proceeds and the target energization off timing Coff and the target energization on timing Con for the fourth discharge in the current cylinder are determined and the process returns from step S214 to step S204, this time the target energization is performed. Since the off timing Coff is no longer in front of the energization start position ON1 ′ for the first discharge in the next cylinder, Coff (= IG4) <ON1 ′ is not established (NO determination), and step S205 is performed. Without proceeding, the discharge control is stopped and the process is exited.

  As described above, according to the ignition control device for an internal combustion engine according to the second embodiment, the energization timing to the primary winding 13a of the ignition coil 13 in the current cylinder in which multiple discharge control is being executed, and the current cylinder When it is predicted that the energization timing to the primary winding 13a of the ignition coil 13 in the next cylinder scheduled to reach the next discharge start timing overlaps, the primary winding of the ignition coil 13 in the next cylinder By providing multiple discharge duplication prohibiting means for forcibly terminating the multiple discharge control in the current cylinder before energization to 13a is started, the energization periods of the primary winding 13a of the ignition coil 13 overlap among a plurality of cylinders. As a result, it is possible to prevent the battery voltage from being lowered and the supply energy from being lowered, so that a desired breaking current cannot be obtained and a good spark discharge cannot be obtained.

  In the above embodiment, the ignition control device for an internal combustion engine provided with multiple discharge forced termination means and multiple discharge overlap prohibiting means has been described. However, both the multiple discharge forced termination means and the multiple discharge overlap prohibiting means are provided. Of course, it may be.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1a Cylinder 1b Combustion chamber 1c Intake valve 1d Exhaust valve 1e Piston 1f Crankshaft 1g Camshaft 1h Connecting rod 2 Spark plug 3 Fuel injection valve 4 Intake passage 5 Electronic control throttle 5a Butterfly valve 5b Motor 5c Throttle opening Sensor 6 Engine control unit (ECU) 7 Accelerator pedal 8 Accelerator position sensor 9 Crank angle sensor 10 Cam angle sensor 11 Water temperature sensor 12 Air flow sensor 13 Ignition coil 13a Primary winding 13b Secondary winding 13c Driver circuit 14 Air cleaner 15 Surge tank 16 Exhaust manifold 17 Catalyst

Claims (3)

An ignition coil having a primary winding and a secondary winding, and generating a high voltage in the secondary winding when an energization current to the primary winding is interrupted;
A spark plug that generates a spark discharge when a high voltage generated in the secondary winding of the ignition coil is applied;
Multiple discharge control is performed to control the timing of energizing the primary winding of the ignition coil, thereby performing multiple discharge control that repeatedly generates spark discharge from the spark plug starting from the discharge start timing set during one combustion cycle. An ignition control device for an internal combustion engine, comprising:
The air-fuel mixture is ignited by the discharge allowable maximum pressure value set as the maximum value of the atmospheric pressure of the spark plug to obtain a good spark discharge in the spark plug and the spark discharged from the spark plug at the time of the discharge start timing. Based on the two known information of the combustion pressure-rotational position characteristic set as a relationship between the combustion pressure generated when combusting and the rotational position of the internal combustion engine,
Multiple discharges of the rotational position of the internal combustion engine when the combustion pressure generated when the air-fuel mixture is ignited and combusted by the spark discharged from the spark plug at the time of the discharge start timing becomes equal to the maximum allowable discharge pressure value When the actual rotational position of the internal combustion engine reaches the multiple discharge control forced end position, the multiple discharge control forcibly ends the multiple discharge control in the combustion cycle in which the multiple discharge control is currently executed. An ignition control device for an internal combustion engine, comprising a forced discharge termination means.   The energization timing to the primary winding of the ignition coil in the current cylinder that is executing the multiple discharge control and the ignition coil primary winding in the next cylinder scheduled to reach the discharge start timing next to the current cylinder When it is expected that the energization timing overlaps, the multiple discharge overlap prohibition for forcibly terminating the multiple discharge control in the current cylinder before the energization to the primary winding of the ignition coil in the next cylinder is started. The ignition control device for an internal combustion engine according to claim 1, further comprising means. An ignition coil having a primary winding and a secondary winding, and generating a high voltage in the secondary winding when an energization current to the primary winding is interrupted;
A spark plug that generates a spark discharge when a high voltage generated in the secondary winding of the ignition coil is applied;
Multiple discharge control is performed to control the timing of energizing the primary winding of the ignition coil, thereby performing multiple discharge control that repeatedly generates spark discharge from the spark plug starting from the discharge start timing set during one combustion cycle. An ignition control device for an internal combustion engine, comprising:
The energization timing to the primary winding of the ignition coil in the current cylinder that is executing the multiple discharge control and the ignition coil primary winding in the next cylinder scheduled to reach the discharge start timing next to the current cylinder When it is expected that the energization timing overlaps, the multiple discharge overlap prohibition for forcibly terminating the multiple discharge control in the current cylinder before the energization to the primary winding of the ignition coil in the next cylinder is started. An ignition control device for an internal combustion engine, characterized by comprising means.

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