JP2015200267A - Internal combustion engine ignition control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine ignition control device capable of reducing a variation in torque in a transition period of switching combustion conditions while reducing the frequency of switching over between a lean combustion condition and a stoichiometric combustion condition.SOLUTION: At time t11, when a wastegate valve opening degree WGd and an air bypass valve opening degree ABd start increasing, an injection quantity of fuel increases so as to keep constant a torque that is to decrease in response to a reduction in a quantity of air and the moving of discharge timing to a retard position. When an air-fuel ratio AFR is changed from an air-fuel ratio AFR1 in a lean combustion condition to 14.5 in a stoichiometric combustion condition in response to the reduction in the quantity of air and the increase in the injection quantity, an extension discharge current Id and extension discharge time ETi of an ignition plug are decreased step by step. By doing so, it is possible to reduce a variation in the torque at a time of switching the lean combustion condition to the stoichiometric combustion condition as compared with a case in which the extension discharge current Id and the extension discharge time ETi are set to zero from the lean combustion condition at a specific air-fuel ratio.

Description

  The present invention relates to an ignition control device for an internal combustion engine that controls the operation of a spark plug.

  Conventionally, the combustion of the air-fuel mixture in the combustion chamber of the internal combustion engine is switched to either lean combustion for combusting the air-fuel mixture thinner than the stoichiometric air-fuel ratio or stoichiometric combustion for combusting the air-fuel mixture with the stoichiometric air-fuel ratio, depending on the vehicle running condition A control device for an internal combustion engine is known. For example, Patent Document 1 discloses a control device for an internal combustion engine that predicts misfire that occurs in a transitional period between lean combustion and stoichiometric combustion, and switches combustion of the air-fuel mixture to stoichiometric combustion based on the prediction. .

Japanese Patent No. 4049669

  However, in the control apparatus for an internal combustion engine described in Patent Document 1, many stoichiometric combustion conditions are applied as a combustion condition for the air-fuel mixture in order to prevent misfire. For this reason, the combustion time under stoichiometric combustion conditions becomes relatively long, and the fuel consumption deteriorates. In addition, when the frequency of switching between the lean combustion condition and the stoichiometric combustion condition increases, there is a switching transition period in which the lean combustion condition is switched to the stoichiometric combustion condition or the stoichiometric combustion condition to the lean combustion condition. It is difficult to burn the air-fuel mixture depending on the combustion conditions matched to the characteristics of the above, and the fluctuation of the output torque may increase.

  The present invention has been made in view of the above-described points, and an object of the present invention is to reduce the fluctuation in torque during a transition transition period of combustion conditions while reducing the frequency of switching between lean combustion conditions and stoichiometric combustion conditions. An ignition control device is provided.

  The present invention is an ignition control device for an internal combustion engine that controls the operation of a spark plug that ignites an air-fuel mixture by electric discharge in a combustion chamber of the internal combustion engine, and includes a discharge control unit and timing detection means. The discharge control unit can change the discharge condition of the spark plug. The timing detection means detects a switching timing that is a timing at which the combustion of the air-fuel mixture in the combustion chamber switches from lean combustion to stoichiometric combustion or from stoichiometric combustion to lean combustion. When the air-fuel mixture in the combustion chamber performs lean combustion, the discharge control unit controls the spark plug so that the discharge time of the spark plug is longer than the discharge time of the spark plug during stoichiometric combustion. In addition, when the timing detection means detects the switching timing, the discharge control unit controls the operation of the spark plug according to a condition different from the discharge condition at the time of lean combustion or the discharge condition at the time of stoichiometric combustion.

  The ignition control device for an internal combustion engine according to the present invention includes a discharge control unit capable of changing a discharge condition of the spark plug. The discharge control unit controls the operation of the ignition plug so that the discharge time of the spark plug becomes longer than the discharge time of the spark plug during stoichiometric combustion when the air-fuel mixture in the combustion chamber performs lean combustion. As a result, it is possible to continuously supply the energy required for ignition to the air-fuel mixture that is difficult to ignite because it is thinner than the stoichiometric air-fuel ratio, and to expand the range of operating states in which the combustion conditions during lean operation can be applied. Therefore, the operation state in which the combustion condition at the time of stoichiometric operation has been applied can be applied as the lean combustion condition, and the switching frequency of the combustion condition can be reduced.

  In the ignition control device for an internal combustion engine of the present invention, when the timing detection means detects the switching timing, the discharge control unit operates the ignition plug depending on conditions different from the discharge conditions at the time of lean combustion or the discharge conditions at the time of stoichiometric combustion. To control. As a result, the air-fuel mixture can be combusted so as to reduce the fluctuation in torque generated during the transitional transition period from the lean combustion condition to the stoichiometric combustion condition or from the stoichiometric combustion condition to the lean combustion condition. Therefore, in the ignition control apparatus for an internal combustion engine according to the present invention, it occurs in the transition period of the combustion condition switching while reducing the frequency of switching between the lean combustion condition and the stoichiometric combustion condition by expanding the range in which the lean combustion condition can be applied. Torque variation can be reduced.

1 is a schematic configuration diagram of an engine system to which an internal combustion engine ignition control device according to a first embodiment of the present invention is applied. 1 is a configuration diagram of an ignition control device for an internal combustion engine according to a first embodiment of the present invention. FIG. It is a time chart of the basic operation | movement of the discharge control part in the ignition control apparatus of the internal combustion engine by 1st Embodiment of this invention. It is a characteristic view which shows the relationship between the rotation speed and torque in a general internal combustion engine ignition control device, and operating conditions. It is a time chart which shows operation | movement of each part when it switches from stoichiometric operation to lean operation in the ignition control apparatus of the internal combustion engine by 1st Embodiment of this invention. It is a time chart which shows operation | movement of each part when it switches from lean operation to stoichiometric operation in the ignition control apparatus of the internal combustion engine by 1st Embodiment of this invention. It is a time chart which shows operation | movement of each part when it switches from stoichiometric operation to lean operation in the ignition control apparatus of the internal combustion engine by 2nd Embodiment of this invention. It is a time chart which shows operation | movement of each part when switching from lean operation to stoichiometric operation in the ignition control apparatus of the internal combustion engine by 2nd Embodiment of this invention. It is a time chart which shows operation | movement of each part when switching from stoichiometric operation to lean operation in the ignition control apparatus of the internal combustion engine by 3rd Embodiment of this invention. It is a time chart which shows operation | movement of each part when it switches from lean operation to stoichiometric operation in the ignition control apparatus of the internal combustion engine by 3rd Embodiment of this invention.

  Hereinafter, an ignition control device for an internal combustion engine according to a plurality of embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
The ignition control device 1 as the point “ignition control device for an internal combustion engine” according to the first embodiment of the present invention is applied to an engine system mounted on a vehicle or the like. The ignition control device 1 includes a discharge control unit 30, a waste gate valve opening sensor 271 and an air bypass valve opening sensor 281. The waste gate valve opening sensor 271 and the air bypass valve opening sensor 281 correspond to “timing detection means” described in the claims.

  First, a schematic configuration of the engine system will be described with reference to FIG. As shown in FIG. 1, the engine system 10 includes an engine 11 as a spark ignition type “internal combustion engine”. The engine 11 is, for example, a 4-cycle multi-cylinder engine, and FIG. 1 shows only a cross section of one cylinder. The configuration described below is similarly provided to other cylinders (not shown).

  The engine 11 burns an air-fuel mixture of air supplied from an intake manifold 14 through an air cleaner 12 and a throttle valve 13 and fuel injected from an injector 15 in a combustion chamber 16. The piston 17 is reciprocated by the explosive force during combustion in the combustion chamber 16. The reciprocating motion of the piston 17 is converted into a rotational motion by the crankshaft 18 and output. The combustion exhaust gas of the air-fuel mixture combusted in the combustion chamber 16 is released into the atmosphere through the exhaust manifold 20 and the like.

  A turbocharger 26 is provided between the intake manifold 14 and the exhaust manifold 20. The turbocharger 26 includes a center housing 261, a shaft 262 inserted through the center housing 261, a turbine 263, a compressor 264, and the like. The turbine 263 is rotatably provided in the exhaust passage 201. On the other hand, the compressor 264 is rotatably provided between the air cleaner 12 and the throttle valve 13 in the intake passage 141. The shaft 262 connects the turbine 263 and the compressor 264. When combustion exhaust gas flows through the exhaust passage 201, the turbine 263 rotates. Thereby, the compressor 264 rotates. When the compressor 264 rotates, the air supplied through the air cleaner 12 is compressed by the compressor 264 and supplied to the engine 11.

  A waist passage 265 is formed at a portion of the exhaust manifold 20 where the turbine 263 is provided so as to bypass the portion where the turbine 263 is provided from the exhaust passage 201. The waste passage 265 is communicated or blocked by the waste gate valve 27. The wastegate valve 27 diverts a part of the exhaust and adjusts the flow rate to the turbine 263.

  A bypass passage 266 is formed in the portion of the intake manifold 14 where the compressor 264 is provided so as to bypass the portion where the compressor 264 is provided from the intake passage 141. The bypass passage 266 is communicated or blocked by the air bypass valve 28. The air bypass valve 28 diverts a part of the intake air and adjusts the flow rate to the compressor 264.

  An intake valve 22 is provided at the intake port of the cylinder head 21 that is the inlet of the combustion chamber 16. An exhaust valve 23 is provided at the exhaust port of the cylinder head 21 that is the outlet of the combustion chamber 16. The intake valve 22 and the exhaust valve 23 are opened and closed by a valve drive mechanism 24. The valve timings of the intake valve 22 and the exhaust valve 23 are adjusted by the variable valve mechanism 25.

  The air-fuel mixture in the combustion chamber 16 is ignited by causing the discharge controller 30 to generate a discharge between the electrodes of the spark plug 7. The discharge control unit 30 operates the ignition circuit unit 31 based on a command from the electronic control unit 32 and applies a high voltage from the ignition coil 40 to the ignition plug 7, thereby generating a spark discharge in the combustion chamber 16.

  The spark plug 7 has a pair of electrodes (see FIG. 2) that face each other with a predetermined gap in the combustion chamber 16. When a high voltage sufficient to cause dielectric breakdown is applied between the pair of electrodes in the gap of the spark plug 7, discharge occurs. In the following description, “high voltage” refers to a voltage that can cause discharge between a pair of electrodes of the spark plug 7.

The electronic control unit 32 is configured by a microcomputer including a CPU, a ROM, a RAM, an input / output port, and the like.
The electronic control unit 32 includes a waste gate valve opening sensor 271, an air bypass valve opening sensor 281, a crank angle sensor 35, a cam position sensor 36, a water temperature sensor 37, a throttle opening sensor 38, and Detection signals from various sensors such as the intake air amount sensor 39 are input. Based on detection signals from these various sensors, the electronic control unit 32 controls the operating state of the engine 11 by driving the throttle valve 13, the injector 15, the ignition circuit unit 31, and the like as indicated by solid arrows. .

Next, the configuration of the discharge control unit 30 will be described with reference to FIG.
As shown in FIG. 2, the discharge control unit 30 includes an ignition coil 40, an ignition circuit unit 31, and an electronic control unit 32.

The ignition coil 40 includes a primary coil 41, a secondary coil 42, and a rectifying element 43, and constitutes a known step-up transformer.
One end of the primary coil 41 is connected to the positive electrode of the battery 6 as a “DC power supply” capable of supplying a constant DC voltage, and the other end is grounded via an ignition switch 45. Hereinafter, the opposite side of the primary coil 41 from the battery 6 is referred to as a “ground side”.
The secondary coil 42 is magnetically coupled to the primary coil 41. One end of the secondary coil 42 is grounded via a pair of electrodes of the spark plug 7, and the other end is grounded via a rectifier element 43 and a secondary current detection resistor 47.

  Here, a current flowing through the primary coil 41 is referred to as a primary current I1, and a current generated by increasing or decreasing the primary current I1 and flowing through the secondary coil 42 is referred to as a secondary current I2. As indicated by the arrows in the figure, the primary current I1 is positive in the direction from the primary coil 41 to the ignition switch 45, and the secondary current I2 is the current in the direction from the secondary coil 42 to the spark plug 7. Positive. The voltage on the spark plug 7 side of the secondary coil 42 is referred to as a secondary voltage V2.

  The rectifying element 43 is composed of a diode and rectifies the secondary current I2.

  The ignition coil 40 generates a high voltage in the secondary coil 42 by a mutual induction action of electromagnetic induction in accordance with a change in the current flowing through the primary coil 41. The ignition coil 40 applies the generated high voltage to the spark plug 7. In the present embodiment, one ignition coil 40 is provided for one ignition plug 7.

  The ignition circuit unit 31 includes an ignition switch (igniter) 45, an energy input unit 50 as “energy input means”, a secondary current detection resistor 47, and a secondary current detection circuit 48.

The ignition switch 45 is composed of, for example, an IGBT (insulated gate bipolar transistor). The collector of the ignition switch 45 is connected to the ground side of the primary coil 41 of the ignition coil 40. The emitter of the ignition switch 45 is grounded. The gate of the ignition switch 45 is connected to the electronic control unit 32. The emitter is connected to the collector via the rectifying element 46.
The ignition switch 45 is turned on / off according to an ignition signal IGT input to the gate. Specifically, the ignition switch 45 is turned on when the ignition signal IGT rises and turned off when the ignition signal IGT falls. Energization and interruption of the primary current I1 in the primary coil 41 are switched by the ignition switch 45 in accordance with the ignition signal IGT.

  The energy input unit 50 includes an energy storage coil 52, a charge switch 53, a charge switch driver circuit 54, and a DCDC converter 51 including a rectifier 55, a capacitor 56, a discharge switch 57, and a discharge switch driver circuit 58. And a rectifying element 59.

The DCDC converter 51 boosts the voltage of the battery 6 and supplies it to the capacitor 56.
The energy storage coil 52 has one end connected to the battery 6 and the other end grounded via a charge switch 53. The charge switch 53 is composed of, for example, a MOSFET (metal oxide semiconductor field effect transistor). The drain of the charge switch 53 is connected to the energy storage coil 52. The source of the charging switch 53 is grounded. The gate of the charging switch 53 is connected to the charging switch driver circuit 54. The charge switch driver circuit 54 can drive the charge switch 53 on and off.
The rectifying element 55 is composed of a diode, and prevents a backflow of current from the capacitor 56 to the energy storage coil 52 and the charge switch 53 side.

When the charging switch 53 is turned on, an induced current flows through the energy storage coil 52 and electric energy is stored. When the charging switch 53 is turned off, the electric energy stored in the energy storage coil 52 is superposed on the DC voltage of the battery 6 and discharged to the capacitor 56 side. By repeating the on / off operation of the charging switch 53, the energy storage coil 52 repeatedly stores and releases energy, and the battery voltage is boosted.
One electrode of the capacitor 56 is connected to the ground side of the energy storage coil 52 via the rectifying element 55. The other electrode of the capacitor 56 is grounded. Capacitor 56 stores the voltage boosted by DCDC converter 51.

The discharge switch 57 is composed of, for example, a MOSFET. The drain of the discharge switch 57 is connected to the capacitor 56. The source of the discharge switch 57 is connected to the ground side of the primary coil 41. The gate of the discharge switch 57 is connected to the driver circuit 58 for discharge switch. The discharge switch driver circuit 58 can drive the discharge switch 57 on and off.
The rectifying element 59 is composed of a diode and prevents a backflow of current from the ignition coil 40 to the capacitor 56.
Although FIG. 2 shows only the configuration for one cylinder, in reality, the configuration after the discharge switch 57 is provided in parallel for the number of cylinders. That is, the current path is branched for each cylinder before the discharge switch 57, and the energy accumulated in the capacitor 56 is distributed to each path.

The secondary current detection circuit 48 detects the secondary current I <b> 2 based on the voltage across the secondary current detection resistor 47 provided in the combustion chamber 16. Thereafter, the feedback control is performed to make the secondary current I2 coincide with a target value (hereinafter referred to as “target secondary current I2 ^* ”), and the on-duty ratio of the discharge switch 57 is calculated. Command.

  The electronic control unit 32 includes a control signal output unit 33 as “energy control means”.

The control signal output unit 33 generates an ignition signal IGT and an energy input period signal IGW based on detection signals output from the waste gate valve opening sensor 271, the air bypass valve opening sensor 281, and the like, and sends them to the ignition circuit unit 31. Output.
The ignition signal IGT is input to the gate of the ignition switch 45 and the charge switch driver circuit 54. The ignition switch 45 is turned on while the ignition signal IGT is input. The charge switch driver circuit 54 repeatedly outputs a charge switch signal SWc for controlling on / off of the charge switch 53 to the gate of the charge switch 53 while the ignition signal IGT is input.

The energy input period signal IGW is input to the discharge switch driver circuit 58. The driver circuit 58 repeatedly outputs a discharge switch signal SWd for controlling on / off of the discharge switch 57 to the gate of the discharge switch 57 while the energy input period signal IGW is input. Further, a target secondary current signal IGA for instructing the target secondary current I2 ^* is input to the discharge switch driver circuit 58.

Next, the operation of the discharge control unit 30 will be described with reference to the time chart of FIG. In the time chart of FIG. 3, the horizontal axis is a common time axis, and the ignition signal IGT, the energy input period signal IGW, the capacitor voltage Vdc, the primary current I1, the secondary current I2, the input energy P, in order from the top on the vertical axis. The time change of the charge switch signal SWc and the discharge switch signal SWd is shown.
Here, “capacitor voltage Vdc” means the voltage stored in the capacitor 56. Further, “input energy P” means energy that is discharged from the capacitor 56 and supplied to the ignition coil 40 from the low-voltage side terminal side of the primary coil 41, and starts supply during one ignition timing (initial discharge) The integrated value from the rising edge of the switch signal SWd is shown.

  In FIG. 3, “primary current I1” and “secondary current I2” have a positive current value in the direction of the arrow shown in FIG. 2 and a negative current value in the direction opposite to the arrow.

In addition, the control target value of the secondary current I2 during the period from the time t3 to the time t4 when the energy input period signal IGW is output is defined as “target secondary current I2 ^* ”. The target secondary current I2 ^* is set to a current that can maintain the ignition discharge well. In the present embodiment, an intermediate value between the wavy maximum value and the minimum value is set as the target value, but the wavy maximum value or the minimum value may be set as the target value.

  When the ignition signal IGT rises to the H (high) level at time t1, the ignition switch 45 is turned on. At this time, since the energy input period signal IGW is at the L (low) level, the discharge switch 57 is off. Thereby, energization of the primary current I1 in the primary coil 41 is started.

Further, while the ignition signal IGT rises to the H level, the rectangular wave pulse-shaped charging switch signal SWc is input to the gate of the charging switch 53. Then, the capacitor voltage Vdc rises stepwise in the off period after the charging switch 53 is turned on.
In this way, the ignition coil 40 is charged and the energy is stored in the capacitor 56 by the output of the DCDC converter 51 between the time t1 and the time t2 when the ignition signal IGT rises to the H level. This energy storage is completed by time t2.
At this time, the capacitor voltage Vdc, that is, the energy storage amount of the capacitor 56 can be controlled by the on-duty ratio and the number of on-off times of the charge switch signal SWc.

Thereafter, when the ignition signal IGT falls to the L level at time t2 and the ignition switch 45 is turned off, the primary current I1 that has been energized to the primary coil 41 until then is suddenly cut off. Then, a high voltage is generated in the secondary coil 42 and a discharge is generated between the electrodes of the spark plug 7. When discharge occurs, a secondary current I2 flows through the secondary coil 42.
When the energy is not input after the ignition discharge is generated at the time t2, the secondary current I2 approaches 0 [A] with the passage of time as shown by the broken line BL1, and when the discharge is attenuated to such an extent that the discharge cannot be maintained, the discharge finish. Such an ignition method by discharge is referred to as “normal discharge”.

  On the other hand, in this embodiment, the energy input period signal IGW is raised to H level at time t3 immediately after time t2, and the discharge switch 57 is turned on while the charge switch 53 is off. When the discharge switch 57 is turned on, the energy stored in the capacitor 56 is released and supplied to the ground side of the primary coil 41. Thereby, the primary current I1 resulting from the input energy P is energized during the ignition discharge.

At this time, the secondary coil 42 is superposed with the same polarity on the secondary current I2 that has been energized between time t2 and time t3 with the same polarity with respect to the energization of the primary current I1 caused by the input energy P. The The superimposition of the primary current I1 is performed every time the discharge switch 57 is turned on from time t3 to time t4.
That is, every time the discharge switch signal SWd is turned on, the primary current I1 is sequentially added by the energy stored in the capacitor 56, and the secondary current I2 is sequentially added correspondingly. Thereby, as shown by the solid line SL1, the secondary current I2 is maintained so as to coincide with the target secondary current I2 ^* .
When the energy input period signal IGW falls to the L level at time t4, the on / off operation of the discharge switch signal SWd stops and both the primary current I1 and the secondary current I2 become zero.

  As described above, after the ignition discharge at time t2, the control method for supplying energy to the ignition coil 40 from the ground side of the primary coil 41 is the battery 6 side of the primary coil 41 or the two as in the known multiple discharge method. Compared to a method in which energy is input to the ignition coil 40 from the side opposite to the ignition plug 7 of the secondary coil 42, the polarity of the secondary current I2 is efficiently input by inputting energy from the low voltage side. Therefore, it is possible to continue the ignition of the air-fuel mixture for a certain period.

  Here, in the time chart of the secondary current I2 in FIG. 3, the time from time t3 to time t4 is defined as the discharge extension time ETi. In addition, the difference between the actual secondary current I2 value shown by the solid line SL1 and the secondary current I2 value in the “normal ignition” shown by the broken line BL1 in the discharge extension time ETi is the discharge extension current Id. And

  The ignition control device 1 according to the first embodiment includes a stoichiometric operation that outputs rotational motion by stoichiometric combustion with an air-fuel ratio of 14.5, and a lean operation that outputs rotational motion by lean combustion with an air-fuel ratio greater than 14.5. There is a feature in the discharge control of the spark plug 7 when the operating state of the engine 11 is switched between. Here, based on FIGS. 4-6, the discharge control of the spark plug 7 at the time of the switching of the driving | running state in the ignition control apparatus 1 is demonstrated.

  FIG. 4 is a characteristic diagram showing the relationship between the rotational speed of the engine 11 and the generated torque. In FIG. 4, the boundary between the region A1 where the lean operation is performed and the region A2 where the stoichiometric operation is performed is indicated by a broken line BL2 in the relationship between the rotational speed of the engine 11 and the generated torque. Further, the rotational speed of the engine 11 and the generated torque upper limit value at each rotational speed of the stoichiometric operation are indicated by a solid line SL2.

  In the engine 11, the air-fuel mixture is burned under the lean combustion condition for executing the lean operation in a region where the rotational speed of the engine 11 is relatively low and the torque is relatively small. Since the air-fuel ratio is relatively large in the lean combustion condition, the ignition control apparatus 1 makes the discharge extension current Id larger than the discharge extension current Id in the stoichiometric combustion condition and the discharge extension time ETi in the discharge extension time in the stoichiometric combustion condition. The discharge of the spark plug 7 is controlled to be longer than ETi to prevent misfire. That is, in FIG. 4, the operating state of the engine 11 is a region A1 where the rotational speed of the engine 11 is relatively low and the torque is relatively small across the broken line BL2, and the rotational speed of the engine 11 is relatively high or the torque is relatively low. When going back and forth between the large region A2 along the broken line BL3, the discharge conditions including the magnitude of the discharge extension current Id of the spark plug 7 and the discharge extension time ETi as parameters change.

  Next, the time change of each parameter of the engine 11 at the time of switching of the operation state will be described based on the time charts shown in FIGS. In the time charts shown in FIGS. 5 and 6, the horizontal axis is the common time axis, and the rotational speed of the engine 11, the torque output by the engine 11, the air-fuel ratio AFR of the engine 11, and the spark plug 7 in order from the top on the vertical axis. Discharge timing, fuel injection amount from the injector 15, amount of air flowing through the intake passage 141, opening WGd of the waste gate valve 27, opening ABd of the air bypass valve 28, opening THd of the throttle valve 13, extended discharge execution A flag, a discharge extension current Id, and a discharge extension time ETi are shown. As for the time on the horizontal axis, the piston 17 makes two reciprocations in the engine 11, that is, the stroke of intake, compression, expansion, and exhaust is taken as one cycle, and that cycle is used as a time scale.

  First, the operation state of the ignition control device 1 when the operation state of the engine 11 is switched from the lean operation to the stoichiometric operation will be described with reference to FIG. In the ignition control apparatus 1 according to the first embodiment, the air-fuel ratio AFR is set to switch from the lean combustion condition to the stoichiometric combustion condition while the engine 11 operates for 10 cycles.

  At time t10, an instruction to change the opening degree WGd of the waste gate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13 in response to a signal output from the accelerator position sensor that the driver steps on is electronic. Input to the control unit 32. At this time, in the discharge control unit 30, the extended discharge execution flag is turned on, and a relatively large current Id1 flows as the discharge extended current Id. The discharge extension time ETi is set to a time Tl that is a discharge extension time under lean combustion conditions. In addition, the discharge extension time ETi in stoichiometric combustion conditions is zero. Further, the current Id1 and the time T1 vary depending on the magnitude of the air-fuel ratio AFR and the combustion conditions of the engine 11.

At time t11, 10 cycles after time t10, the opening WGd of the waste gate valve 27, the opening ABd of the air bypass valve 28, and the opening THd of the throttle valve 13 start to increase. The “10 cycles” is an example of a change delay after the change command in the waste gate valve 27, the air bypass valve 28, and the throttle valve 13 is input, and may not be 10 cycles.
At time t11, when the opening degree WGd of the wastegate valve 27 and the opening degree ABd of the air bypass valve 28 start to increase, the amount of gas flowing through the waist passage 265 and the bypass passage 266 increases, and the air amount from the air amount AM1. It begins to decrease. Accordingly, in order to prevent the occurrence of knocking, the discharge timing starts to shift from the angle DT1 to the retard side. Further, when the discharge timing shifts to the retard side, the torque generated by the engine 11 decreases, so the injection amount is increased from the injection amount IM2 to the injection amount IM1 greater than the injection amount IM2, and the torque is kept constant. Note that the air amount AM1, the angle DT1, and the injection amounts IM1, IM2 vary depending on the magnitude of the air-fuel ratio AFR and the combustion conditions of the engine 11.

The air-fuel ratio AFR that was the value AFR1 at time t11 starts to decrease with the passage of time from the above-described relationship between the air amount and the injection amount.
Here, in the conventional ignition control device, for example, when the air-fuel ratio AFR falls below the value AFR2, the discharge time of the spark plug 7 is set to be extended. Therefore, at the timing when the air-fuel ratio AFR falls below the value AFR2, that is, at time t12 when 14 cycles have elapsed from time t10, the extended discharge execution flag is turned off as indicated by a broken line L11 (white in FIG. 5). (See blank circle C11 and dotted arrow F11). When the extended discharge execution flag is turned off, the discharge extension current Id and the discharge extension time ETi become 0 and the discharge extension time ETi becomes 0 according to the map in the normal stoichiometric operation. Further, from time t11 to time t12, the discharge extension current Id and the discharge extension time ETi are controlled as indicated by broken lines L12 and L13, and are changed according to the map in the normal lean operation. For this reason, during the switching transition period from the time t11 to the time t13 when the operation state of the engine 11 is completely switched from the lean operation to the stoichiometric operation, the generation amount of nitrogen oxide increases or a large torque fluctuation occurs. To do.

Therefore, in the ignition control device 1 according to the first embodiment, the spark plug 7 is operated under a discharge condition different from the map in the normal lean operation or stoichiometric operation while the extended discharge execution flag is turned on even after the time t12. .
Specifically, after the change command is input to the opening degree WGd of the wastegate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13, the time t11 at which actual changes of these opening degrees start. From time to time t13, the extended discharge current Id and the extended discharge time ETi are changed stepwise while the extended discharge execution flag is kept on. More specifically, at time t12, the discharge extension current Id is changed from the current Id1 to a current Id2 that is smaller than the current Id1. Further, the discharge extension time ETi is changed to a time Tt shorter than the time Tl. Thereafter, the discharge extension current Id is changed from the current Id2 to 0 at the time t13 when all the operation states of the engine 11 are switched to the stoichiometric operation. Further, the discharge extension time ETi is changed to zero.

  Next, the operation state of the ignition control device 1 when the operation state of the engine 11 is switched from the stoichiometric operation to the lean operation will be described based on FIG. In the ignition control device 1 according to the first embodiment, the air-fuel ratio AFR is set to switch from the stoichiometric combustion condition to the lean combustion condition while the engine 11 operates for 10 cycles.

  At time t20, an instruction to change the opening degree WGd of the waste gate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13 in response to a signal output from the accelerator position sensor that the driver steps on is electronic. Input to the control unit 32. At this time, in the discharge control unit 30, the extended discharge execution flag is off, and the discharge extended current Id is zero. The discharge extension time ETi is set to 0, which is the discharge extension time under stoichiometric combustion conditions. That is, in the stage before time t20, the time change of the secondary current I2 shows a waveform as indicated by a broken line BL1 in FIG.

  At time t21, which is 10 cycles after time t20, the opening WGd of the waste gate valve 27, the opening ABd of the air bypass valve 28, and the opening THd of the throttle valve 13 start to decrease. At time t21, when the opening degree WGd of the wastegate valve 27 and the opening degree ABd of the air bypass valve 28 start to decrease, the amount of gas flowing through the waist passage 265 and the bypass passage 266 decreases, and the air amount is reduced from the air amount AM2. Start to increase. In accordance with this, the discharge timing starts to shift from the angle DT2 smaller than the angle DT1 to the advance side. When the discharge timing starts to shift to the advance side, the torque generated by the engine 11 increases, so the injection amount is decreased from the injection amount IM1 to the injection amount IM2, and the torque is kept constant.

The air-fuel ratio AFR, which was 14.5 at time t21, starts to increase over time due to the relationship between the air amount and the injection amount.
Here, in the conventional ignition control device that is set so as to cancel the extension of the discharge time of the spark plug 7 when the air-fuel ratio AFR exceeds the value AFR2, the timing at which the air-fuel ratio AFR exceeds the value AFR2, that is, from the time t20. At time t23 when the time for 16 cycles has elapsed, the extended discharge execution flag is turned on as shown by the broken line L21 (see the white circle C21 and the dotted arrow F21 in FIG. 6). When the extended discharge execution flag is turned on, the discharge extension current Id and the discharge extension time ETi are controlled as indicated by the broken lines L22 and L23 according to the map in the normal stoichiometric operation, and the discharge extension current Id becomes a current Id3 smaller than the current Id2. The discharge extension time ETi is changed to a time shorter than the time Tl. For this reason, during the switching transition period from the time t21 to the time t24 when the operation state of the engine 11 is completely switched from the stoichiometric operation to the lean operation, the generation amount of nitrogen oxide increases or a large torque fluctuation occurs. To do.

Therefore, in the ignition control device 1 according to the first embodiment, the extended discharge execution flag is turned on before time t23, and the spark plug 7 is operated under a discharge condition different from the map in the normal lean operation or stoichiometric operation.
Specifically, after the change command is input to the opening degree WGd of the wastegate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13, the time t21 at which actual changes of these opening degrees start. The extended discharge execution flag is turned on, and the discharge extension current Id and the discharge extension time ETi are changed stepwise. More specifically, at time t21, the discharge extension current Id is changed from 0 to the current Id2. Next, at time t22 before time t23, the discharge extension time ETi is set to a time Tt shorter than the time Tl. Next, at time t23, the discharge extension current Id is changed from the current Id2 to the current Id1, and the discharge extension time ETi is changed to the time Tl. As a result, before the time t24 when the operating state of the engine 11 is all switched to the lean operation, the discharge extension current Id becomes the current Id1, and the discharge extension time ETi becomes the time Tl.

  In the ignition control device 1 according to the first embodiment, when the operating state of the engine 11 is a lean operation, the discharge time of the spark plug 7 is extended as compared with the stoichiometric operation, thereby igniting a mixture that is thinner than the stoichiometric air-fuel ratio. Make it easier. Thereby, in the relationship between the rotation speed and the torque of the engine 11 shown in FIG. 4, the lean combustion condition can be applied to the operating state where the stoichiometric combustion condition has been applied so far, and the range in which the lean combustion condition can be applied is expanded. be able to. Therefore, the switching frequency between the lean combustion condition and the stoichiometric combustion condition can be reduced.

  In the ignition control device 1 according to the first embodiment, the switching timing between the lean operation and the stoichiometric operation is detected according to the opening WGd of the waste gate valve 27 and the opening ABd of the air bypass valve 28. When the discharge control unit 30 detects the switching timing, the discharge extension current Id of the spark plug 7 and the spark plug 7 during the switching transition period in which the combustion condition is changed from the lean combustion condition to the stoichiometric combustion condition or from the stoichiometric combustion condition to the lean combustion condition. The discharge extension time ETi is controlled. At this time, the discharge control unit 30 operates the spark plug 7 under a discharge condition different from a condition determined by a map in a normal lean operation or stoichiometric operation in the switching transition period. As a result, the ignition control device 1 according to the first embodiment can reduce the amount of nitrogen oxides generated during the transition transition period of the combustion conditions or reduce the fluctuation in torque.

  Further, the discharge control unit 30 changes the magnitude of the discharge extension current Id and the discharge extension time ETi stepwise as a discharge condition in the transition period of the combustion condition switching. Thereby, the fluctuation | variation of the torque which generate | occur | produces in the switching transition period of combustion conditions can be made still smaller.

In the ignition control device 1 according to the first embodiment, as a method of energy input control, a method is adopted in which input energy boosted by the DCDC converter 51 and stored in the capacitor 56 is input from the ground side of the primary coil 41. As a result, compared to an energy input method such as multiple discharge, it is possible to maintain a ignitable state for a certain period while efficiently supplying the minimum energy by inputting energy from the low voltage side.
Further, during the energy input period IGW, the secondary current I2 is always a negative value, and zero crossing is not performed as in other systems using an alternating current, so that blowout can be prevented.

In addition, the ignition control device 1 according to the first embodiment includes the secondary current detection resistor 47 and the secondary current detection circuit 48, and performs feedback control of the secondary current I2. The actual value can be matched with the target secondary current I2 ^* with high accuracy.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The ignition control device for an internal combustion engine according to the second embodiment differs from the first embodiment in temporal changes in the discharge extension current Id and the discharge extension time ETi in switching between the lean operation condition and the stoichiometric operation condition. Parts substantially the same as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIGS. 7 and 8 show temporal changes of the respective parameters when the operating state of the engine 11 to which the ignition control device for an internal combustion engine according to the second embodiment is applied is switched.

  First, the operating state of the ignition control device according to the second embodiment when the operating state of the engine 11 is switched from the lean operation to the stoichiometric operation will be described with reference to FIG. In the ignition control apparatus according to the second embodiment, the air-fuel ratio AFR is set to switch from the lean combustion condition to the stoichiometric combustion condition while the engine 11 operates for one cycle.

  At time t30, an instruction to change the opening degree WGd of the waste gate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13 in response to a signal output from the accelerator position sensor that the driver steps on is electronic. Input to the control unit 32. At this time, in the discharge control unit 30, the extended discharge execution flag is turned on, and the discharge extended current Id flows, for example, the current Id1. Further, the discharge extension time ETi is set to a time Tl which is the discharge extension time ETi under the lean combustion condition.

At time t31 10 cycles after time t30, the opening WGd of the waste gate valve 27, the opening ABd of the air bypass valve 28, and the opening THd of the throttle valve 13 start to increase.
At time t31, when the opening degree WGd of the waste gate valve 27 and the opening degree ABd of the air bypass valve 28 start to increase, the air amount starts to decrease from the air amount AM1. Since the amount of air is determined by the opening WGd of the wastegate valve 27 and the opening ABd of the air bypass valve 28, which have a relatively small change rate, the change rate is relatively small. On the other hand, since the injection amount is higher in response than the opening degree WGd of the wastegate valve 27 and the opening degree ABd of the air bypass valve 28, the injection amount exceeds the injection amount IM1 from the injection amount IM2 in one cycle time. Can be changed. At this time, the discharge timing further shifts to the retard side from the angle DT2, and the air-fuel ratio AFR changes to 14.5 at time t33, one cycle after time t31.

  In the conventional ignition control device that is set to extend the discharge time of the spark plug 7 when the air-fuel ratio AFR falls below the value AFR2, the timing at which the air-fuel ratio AFR falls below the value AFR2, that is, one cycle from the time t31. At the time t32 when the less time has elapsed, as shown by the broken line L31, the extended discharge execution flag is turned off (see the white circle C31 and the dotted arrow F31 in FIG. 7). When the extended discharge execution flag is turned off, the discharge extension current Id becomes 0 at time t32 as shown by the broken line L32, and the discharge extension time ETi becomes 0 at time t32 as shown by the broken line L33. For this reason, since the discharge extension current Id and the discharge extension time ETi change abruptly, it is particularly large in the switching transition period from the time t31 to the time t34 when the operating state of the engine 11 is completely switched from the lean operation to the stoichiometric operation. Torque fluctuation occurs.

Therefore, in the ignition control device according to the second embodiment, the spark plug 7 is operated under a discharge condition different from that in the normal lean operation or stoichiometric operation while the extended discharge execution flag is turned on even after the time t32.
Specifically, after the change command is input to the opening degree WGd of the wastegate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13, the time t31 at which actual changes of these opening degrees start. From time to time t34, the discharge extension current Id and the discharge extension time ETi are changed stepwise while the extension discharge execution flag is kept on. More specifically, at time t33, one cycle after time t31, discharge extension current Id is changed from current Id1 to current Id2. Further, the discharge extension time ETi is set to a time Tt shorter than the time Tl. Thereafter, the discharge extension current Id is changed from the current Id2 to 0 at time t34 when all the parameters of the engine 11 are switched to the stoichiometric operation conditions. Further, the discharge extension time ETi is changed to zero.

  Next, the operation state of the ignition control device according to the second embodiment when the operation state of the engine 11 is switched from the stoichiometric operation to the lean operation will be described based on FIG. In the ignition control apparatus according to the second embodiment, the air-fuel ratio AFR is set to switch from the stoichiometric combustion condition to the lean combustion condition while the engine 11 operates for one cycle.

  At time t40, an instruction to change the opening degree WGd of the waste gate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13 in response to a signal output from the accelerator position sensor that the driver steps on is electronic. Input to the control unit 32. At this time, in the discharge control unit 30, the extended discharge execution flag is off, and the discharge extended current Id is zero. The discharge extension time ETi is set to 0, which is the discharge extension time ETi under stoichiometric combustion conditions. That is, in the stage before time t40, the time change of the secondary current I2 shows a waveform as indicated by a broken line BL1 in FIG.

  At time t41, 10 cycles after time t40, the opening WGd of the waste gate valve 27, the opening ABd of the air bypass valve 28, and the opening THd of the throttle valve 13 start to decrease. At time t41, when the opening degree WGd of the wastegate valve 27 and the opening degree ABd of the air bypass valve 28 start to decrease, the air amount starts to increase from the air amount AM2. At this time, the engine 11 increases the injection amount from the injection amount IM1 in order to prevent a decrease in torque due to switching from the stoichiometric combustion condition to the lean combustion condition. As a result, the air-fuel ratio AFR remains at 14.5, but the discharge timing is shifted from the angle DT2 to the retard side in order to suppress the increase in torque due to the increase in the injection amount.

  When the opening WGd of the wastegate valve 27 and the opening ABd of the air bypass valve 28 are further reduced, the torque starts to decrease due to the increase in the injection amount and the shift to the retard side of the discharge timing (after time t42 in FIG. 8). ). Therefore, torque variation is reduced by shifting the discharge timing to the advance side while decreasing the injection amount. As a result, the air-fuel ratio AFR, which was 14.5, becomes greater than 20 at time t43.

  Here, in the conventional ignition control device that is set to cancel the extension of the discharge time of the spark plug 7 when the air-fuel ratio AFR exceeds the value AFR2, at the timing when the air-fuel ratio AFR exceeds the value AFR2, that is, at time t43. As shown by the broken line L41, the extended discharge execution flag is turned on (see the white circle C41 and the dotted arrow F41 in FIG. 8). When the extended discharge execution flag is turned on, the discharge extension current Id is changed from 0 to the current Id1 as shown by the broken line L42, and the discharge extension time ETi is changed from 0 to the time T1 as shown by the broken line L43. Is done. Therefore, a particularly large torque fluctuation occurs in the switching transition period from time t41 to time t44 after 10 cycles when the operation state of the engine 11 is completely switched from stoichiometric operation to lean operation.

Therefore, in the ignition control apparatus according to the second embodiment, the extended discharge execution flag is turned on before time t43, and the spark plug 7 is operated under a discharge condition different from the map in the normal lean operation or stoichiometric operation.
Specifically, after a change command is input to the opening degree WGd of the wastegate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13, the time t41 at which actual changes of these opening degrees start. The extended discharge execution flag is turned on, and the discharge extension current Id and the discharge extension time ETi are changed stepwise. More specifically, at time t41, the discharge extension current Id is changed from 0 to the current Id2, and the discharge extension time ETi is changed to a time Tt shorter than the time Tl. Next, at time t43, the discharge extension current Id is changed from the current Id2 to the current Id1, and the discharge extension time ETi is changed to the time Tl. As a result, the discharge extension current Id becomes the current Id1 and the discharge extension time ETi becomes the time Tl before the time t44 at which all the parameters of the engine 11 are switched to the lean operation conditions.

  In the ignition control apparatus according to the second embodiment, when the air-fuel ratio AFR is changed from the value AFR1 to 14.5 during the time of one cycle, the extended discharge execution flag is set even if the air-fuel ratio AFR is lower than the value AFR2. While maintaining the ON state, the discharge extension current Id is maintained at a predetermined magnitude, and the discharge time is extended. When the air-fuel ratio AFR is changed from 14.5 to the value AFR1 during the time of one cycle, the extended discharge execution flag is turned on before the time when the air-fuel ratio AFR exceeds the value AFR2, and the discharge extended current Id To a predetermined size to extend the discharge time. As a result, it is possible to reduce fluctuations in torque generated in the switching transition period in which the combustion condition is changed from the lean combustion condition to the stoichiometric combustion condition, or from the stoichiometric combustion condition to the lean combustion condition. Therefore, 2nd Embodiment has the same effect as 1st Embodiment, and can especially reduce the fluctuation | variation of the torque which may generate | occur | produce in the rapid acceleration request | requirement of a vehicle.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. The ignition control apparatus for an internal combustion engine according to the third embodiment differs from the first embodiment in the temporal change of the discharge extension current Id and the discharge extension time ETi in switching between the lean operation condition and the stoichiometric operation condition. Parts substantially the same as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIGS. 9 and 10 show time charts of respective parameters when the operating state of the engine 11 to which the internal combustion engine ignition control device according to the third embodiment is applied is switched.

  First, the operating state of the ignition control device according to the third embodiment when the operating state of the engine 11 is switched from the lean operation to the stoichiometric operation will be described with reference to FIG. In the ignition control apparatus according to the third embodiment, the air-fuel ratio AFR is set to switch from the lean combustion condition to the stoichiometric combustion condition while the engine 11 operates for five cycles.

  At time t50, an instruction to change the opening degree WGd of the waste gate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13 in response to a signal output by the accelerator position sensor that the driver steps on is electronic. Input to the control unit 32. At this time, in the discharge control unit 30, the extended discharge execution flag is turned on, and the discharge extended current Id flows, for example, the current Id1. Further, the discharge extension time ETi is set to a time Tl which is the discharge extension time ETi under the lean combustion condition.

At time t51, which is 10 cycles after time t50, the opening WGd of the waste gate valve 27, the opening ABd of the air bypass valve 28, and the opening THd of the throttle valve 13 start to increase.
At time t51, when the opening degree WGd of the wastegate valve 27 and the opening degree ABd of the air bypass valve 28 start to increase, the air amount starts to decrease from the air amount AM1. On the other hand, since the injection amount is higher in response than the opening degree WGd of the wastegate valve 27 and the opening degree ABd of the air bypass valve 28, the injection amount is a value exceeding the injection amount IM1 from the injection amount IM2 in the time of five cycles. Can be changed. At this time, the discharge timing shifts further to the retard side than the angle DT2, and the air-fuel ratio AFR changes to 14.5 by time t54 five minutes after time t51.

  In the conventional ignition control device that is set to extend the discharge time of the spark plug 7 when the air-fuel ratio AFR falls below the value AFR2, the timing at which the air-fuel ratio AFR falls below the value AFR2, that is, two cycles from the time t51. At time t52 when the time has elapsed, as shown by a broken line L51, the extended discharge execution flag is turned off (see the white circle C51 and the dotted arrow F51 in FIG. 9). When the extended discharge execution flag is turned off, the discharge extension current Id and the discharge extension time ETi become 0 and the discharge extension time ETi becomes 0 according to the map in the normal stoichiometric operation. Further, from time t51 to time t52, the discharge extension current Id and the discharge extension time ETi are controlled as indicated by broken lines L52 and L53, and are changed according to the map in the normal lean operation. For this reason, in the switching transition period from the time t51 to the time t55 when the operation state of the engine 11 is completely switched from the lean operation to the stoichiometric operation from the time t51, the generation amount of nitrogen oxides increases or a large torque fluctuation occurs. Occur.

Therefore, in the ignition control apparatus according to the third embodiment, the spark plug 7 is operated under a discharge condition different from that in the normal lean operation or stoichiometric operation while the extended discharge execution flag is turned on even after the time t52.
Specifically, the time t51 at which the actual change of the opening starts after the change command is input to the opening WGd of the waste gate valve 27, the opening ABd of the air bypass valve 28, and the opening THd of the throttle valve 13. From time to time t55, the discharge extension current Id and the discharge extension time ETi are changed stepwise while the extension discharge execution flag is on. More specifically, at time t52 after two cycles from time t51, the discharge extension time ETi is set to a time Tt shorter than the time Tl. Further, at time t53, which is three cycles after time t51, the discharge extension current Id is changed from the current Id1 to the current Id2. Thereafter, the discharge extension current Id is changed from the current Id2 to 0 at time t55 when all the parameters of the engine 11 are switched to the stoichiometric operation conditions. Further, the discharge extension time ETi is changed to zero.

  Next, the operation state of the ignition control device according to the third embodiment when the operation state of the engine 11 is switched from the stoichiometric operation to the lean operation will be described based on FIG. In the ignition control apparatus according to the third embodiment, the air-fuel ratio AFR is set to switch from the stoichiometric combustion condition to the lean combustion condition while the engine 11 operates for five cycles.

  At time t60, an instruction to change the opening degree WGd of the waste gate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13 in response to a signal output from the accelerator position sensor that the driver steps on is electronic. Input to the control unit 32. At this time, in the discharge control unit 30, the extended discharge execution flag is turned off, and the discharge extended current Id is 0 [mA]. Further, the discharge extension time ETi is set to 0, which is the discharge extension time ETi in the stoichiometric combustion condition, that is, the time change of the secondary current I2 in the stage before time t20 is as shown by the broken line BL1 in FIG. The waveform is shown.

  At time t61, 10 cycles after time t60, the opening degree WGd of the waste gate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13 start to decrease. At time t61, when the opening degree WGd of the waste gate valve 27 and the opening degree ABd of the air bypass valve 28 start to decrease, the air amount starts to increase from the air amount AM2. At this time, the engine 11 increases the injection amount from the injection amount IM1 in order to prevent a decrease in torque due to switching from the stoichiometric combustion condition to the lean combustion condition. As a result, the air-fuel ratio AFR remains at 14.5, but the discharge timing is shifted further to the retard side than the angle DT2 in order to suppress an increase in torque due to an increase in the injection amount.

When the opening WGd of the wastegate valve 27 and the opening ABd of the air bypass valve 28 are further reduced, the torque starts to decrease due to the increase in the injection amount and the shift to the retard side of the discharge timing (after time t62 in FIG. 10). ). Therefore, torque variation is reduced by shifting the discharge timing to the advance side while decreasing the injection amount. As a result, the air-fuel ratio AFR, which was 14.5, becomes larger than the value AFR2 at time t63.
Here, in the conventional ignition control device that is set to cancel the extension of the discharge time of the spark plug 7 when the air-fuel ratio AFR exceeds the value AFR2, the timing at which the air-fuel ratio AFR exceeds the value AFR2, that is, the time t63. , The extended discharge execution flag is turned on as shown by the broken line L61 (see the white circle C61 and the dotted arrow F61 in FIG. 10). When the extended discharge execution flag is turned on, the discharge extended current Id becomes the current Id1 according to the map in the normal lean operation as indicated by the broken line L62. Further, as shown by a broken line L43, the discharge extension time ETi becomes the time Tl according to the map in the normal lean operation. For this reason, in the switching transition period from the time t61 to the time t64 when the operation state of the engine 11 is completely switched from the lean operation to the stoichiometric operation from the time t61, the generation amount of nitrogen oxide increases or a large torque fluctuation occurs. Occur.

Therefore, in the ignition control device according to the third embodiment, the extended discharge execution flag is turned on before time t63, and the spark plug 7 is operated under a discharge condition different from the map in the normal lean operation or stoichiometric operation.
Specifically, after the change command is input to the opening degree WGd of the wastegate valve 27, the opening degree ABd of the air bypass valve 28, and the opening degree THd of the throttle valve 13, the time t61 at which actual changes of these opening degrees start. The extended discharge execution flag is turned on, and the discharge extension current Id and the discharge extension time ETi are changed stepwise. More specifically, at time t61, the discharge extension current Id is changed from 0 to the current Id2, and the discharge extension time ETi is changed to a time Tt shorter than the time Tl. Next, at time t63, the discharge extension current Id is changed from the current Id2 to the current Id1, and the discharge extension time ETi is changed to the time Tl. As a result, before the time t64 when the operating state of the engine 11 is all switched to the lean operation, the discharge extension current Id becomes the current Id1, and the discharge extension time ETi becomes the time Tl.

  In the ignition control apparatus according to the third embodiment, when the air-fuel ratio AFR is changed from the value AFR1 to 14.5 during the time corresponding to five cycles, the extended discharge execution flag is set even if the air-fuel ratio AFR falls below the value AFR2. While maintaining the ON state, the discharge extension current Id is maintained at a predetermined magnitude, and the discharge time is extended. When the air-fuel ratio AFR is changed from the value AFR1 to 14.5 during the time corresponding to five cycles, the extended discharge execution flag is turned on before the time when the air-fuel ratio AFR exceeds the value AFR2, and the discharge extended current Id To a predetermined size to extend the discharge time. Thereby, 3rd Embodiment can have the same effect as 1st Embodiment.

(Other embodiments)
(A) In the above-described embodiment, the extended discharge current and the discharge extension time are changed in stages in the transition period of the operating conditions. However, the change of these values in the transition period of the operating conditions is changed in stages. It is not limited to changing. Unlike normal lean combustion conditions and stoichiometric combustion conditions, it may be controlled so that the increase in the amount of nitrogen oxides generated and the fluctuation in torque are reduced.

  Moreover, the change of the extended discharge current and discharge extension time shown in the above-mentioned embodiment is an example, and is not limited to this change content.

  (A) In the above-described embodiment, the engine has a turbocharger. However, the engine may not have a turbocharger.

  In the above-described embodiment, the “timing detection means” described in the claims is a wastegate valve opening sensor and an air bypass valve opening sensor. However, the timing detection means is not limited to this. Any means may be used as long as the combustion condition of the air-fuel mixture in the combustion chamber detects a switching timing that is a timing at which the lean combustion condition is switched to the stoichiometric combustion condition or the stoichiometric combustion condition is switched to the lean combustion condition.

  (C) In the above-described embodiment, the control condition in the “method of inputting energy from the ground side of the primary coil” developed by the present applicant is assumed to extend the discharge time in the spark plug according to the discharge timing. In addition, as long as the secondary current or the energy input period can be variably controlled, the conventional multiple discharge method and the energy input control method such as “DCO method” disclosed in Japanese Patent Application Laid-Open No. 2012-167665 can be used. The present invention may be applied to extend the discharge time in the spark plug according to the discharge timing.

  Further, as shown in FIG. 3, the energy input control by the discharge control unit is performed by turning on / off the charge switch signal during the H level of the ignition signal and accumulating the capacitor voltage, and then on the ground side of the primary coil during the energy input period. It is not limited to the method of inputting energy. For example, the charge switch signal and discharge switch signal are alternately turned on and off during the energy input period, so that the energy stored in the energy storage coil when the charge switch signal is on is input to the ground side of the primary coil each time. You may make it do. In that case, the capacitor may not be provided.

  (D) In the above-described embodiment, the secondary current detection resistor and the secondary current detection circuit are provided, and the secondary current is feedback-controlled. However, the method of controlling the secondary current is not limited to this. For example, the secondary current may be feedforward controlled.

  (E) In the above-described embodiment, the ignition switch is not limited to the IGBT, and may be composed of another switching element having a relatively high breakdown voltage. Further, the charge switch and the discharge switch are not limited to MOSFETs, and may be composed of other switching elements.

  (F) In the above-described embodiment, the DC power source is a battery. However, the type of DC power supply is not limited to this. For example, the AC power source may be constituted by a DC stabilized power source stabilized by a switching regulator or the like.

  (G) In the above embodiment, the energy input unit boosts the voltage of the battery by the DCDC converter. However, the type of energy input unit is not limited to this. In addition, when the ignition device is mounted on a hybrid vehicle or an electric vehicle, the output voltage of the main battery may be used as input energy as it is or after being stepped down.

  The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

1 ... Ignition control device (ignition control device for internal combustion engine),
7 ... Spark plug,
11 ・ ・ ・ Internal combustion engine,
16 ... combustion chamber,
271 ... Wastegate valve opening sensor (timing detection means),
281 ... Air bypass valve opening sensor (timing detection means),
30: Discharge control unit.

Claims (5)

An internal combustion engine ignition control device (1) for controlling an operation of a spark plug (7) for igniting an air-fuel mixture by discharge in a combustion chamber (16) of the internal combustion engine (11),
A discharge controller (30) capable of changing a discharge condition of the spark plug;
Timing detection means (271, 281) for detecting a switching timing at which the combustion of the air-fuel mixture in the combustion chamber is switched from lean combustion to stoichiometric combustion, or from stoichiometric combustion to lean combustion;
With
The discharge control unit controls the spark plug so that a discharge time of the spark plug is longer than a discharge time of the spark plug during stoichiometric combustion when the air-fuel mixture in the combustion chamber performs lean combustion,
When the timing detection unit detects the switching timing, the discharge control unit controls the operation of the spark plug according to a discharge condition different from a discharge condition during lean combustion and a discharge condition during stoichiometric combustion. An internal combustion engine ignition control device.   2. The internal combustion engine according to claim 1, wherein when the timing detection unit detects the switching timing, the discharge control unit increases or decreases the magnitude of the discharge current and the discharge time of the spark plug in a stepwise manner. Engine ignition control device. The discharge controller is
A primary coil (41) through which a primary current supplied from a direct current power source (6) flows, and a secondary coil (42) through which a secondary current generated by energization and interruption of the primary current is connected to the electrode of the spark plug. An ignition coil (40) having:
An ignition switch (45) connected to a ground side opposite to the DC power source of the primary coil and switching between energization and interruption of the primary current according to an ignition signal (IGT);
Energy input means for continuously supplying energy enabling discharge to the ignition coil during a predetermined energy input period (IGW) after the discharge of the spark plug is generated by cutting off the primary current by the ignition switch. (50),
Input energy control means (33) that is electrically connected to the discharge condition determination means and controls input energy by the energy input means;
The ignition control device for an internal combustion engine according to claim 1 or 2, characterized by comprising: The energy input means includes
A first control terminal, a first power supply side terminal, and a first ground side terminal connected to the other end of the primary coil, and based on a discharge switch signal (SWd) input to the first control terminal A discharge switch (57) for controlling on / off between the first power supply side terminal and the first ground side terminal;
A charge switch signal (SWc) input to the second control terminal, having a second control terminal, a second power supply side terminal connected to the first power supply side terminal, and a grounded second ground side terminal A charge switch (53) for controlling on / off between the second power supply side terminal and the second ground side terminal based on
An energy storage coil (52) provided to be connected to the non-grounded output terminal and the second power supply side terminal of the DC power supply, and to store energy when the charging switch is turned on;
Have
The input energy control means includes:
When energy is stored in the energy storage coil by turning on the charge switch, the energy storage coil is turned off by turning off the charge switch and turning on the discharge switch during discharge of the spark plug started by turning off the ignition switch. 4. The internal combustion engine ignition control according to claim 3, wherein the discharge switch and the charge switch are controlled to release energy from the first coil and supply a primary current to the primary coil from the other end of the primary coil. apparatus. The discharge controller is
A plurality of ignition coils having a primary coil through which a primary current supplied from a DC power source flows, and a secondary coil connected to an electrode of the ignition plug and through which a secondary current generated by increasing or decreasing the primary current flows;
A plurality of ignition switches connected to a ground side opposite to the direct current power source of the primary coils of each of the plurality of ignition coils and switching between energization and interruption of the primary current according to an ignition signal;
The ignition control device for an internal combustion engine according to claim 1 or 2, characterized by comprising:

Images