JP6349894B2 - Ignition control device - Google Patents

Description

  The present invention relates to an ignition control device that forms an ignition device that ignites an air-fuel mixture in a combustion chamber of an internal combustion engine and generates a high voltage in a secondary winding by changing a current flowing through a primary winding of an ignition coil.

  The “smoldering” of the spark plug refers to a phenomenon in which carbon generated by incomplete combustion or the like of the internal combustion engine adheres to the insulator surface of the spark plug and the insulation resistance value between the electrodes decreases. When this smoldering progresses, when a high voltage is applied, a leakage current flows between the electrodes of the spark plug, the voltage between the electrodes decreases, spark discharge does not occur, and misfire may occur. On the other hand, Patent Document 1 attempts to suppress the progress of smoldering by performing idle discharge immediately before fuel injection and burning out carbon on the insulator surface.

Japanese Patent No. 3565059

However, even if idling discharge is performed as described in Patent Document 1, the combustion temperature is, for example, a rich combustion operation at a cold start or a lean combustion operation when the exhaust gas recirculation amount is relatively large. There was a problem that the carbon on the insulator surface could not be burned out reliably when the temperature was relatively low. Therefore, the progress of smoldering cannot be sufficiently suppressed, and misfire may occur.
The present invention has been made in view of the above points, and an object of the present invention is to provide an ignition control device that can effectively suppress the progress of smoldering.

  The ignition control device according to the present invention includes an ignition switch and an energy input unit. The ignition switch generates a high voltage in the secondary winding of the ignition coil by starting a discharge by cutting off a current path between the power source and the primary winding of the ignition coil. The energy input unit supplies a discharge sustaining current for the secondary winding.

In particular, the present invention is characterized by further comprising a smolder determining means and an energy control means. The smolder determining means determines whether smoldering has occurred in the spark plug. If the ignition timing interval of the spark plug is defined as an ignition cycle, the energy control means, when it is determined that smoldering has occurred in the spark plug, from the determination until the predetermined number of times the ignition cycle has passed. Command the input of electrical energy.
In the first aspect of the present invention, when it is determined that the smoldering has occurred in the spark plug, the energy control unit causes the electric energy charged in the energy input unit to be input to the ground side of the primary winding, The sustaining current is increased more than before the occurrence of smoldering.
In the second aspect of the present invention, when it is determined that smoldering has occurred in the spark plug, the energy control means increases the maximum value of the discharge sustaining current more than before smoldering occurs.
In the third aspect of the present invention, when it is determined that the smoldering has occurred in the spark plug, the energy control means sets the maximum value of the discharge sustaining current from the maximum value of the secondary current during discharge by the ignition switch. Also make it bigger.

The greater the “electric energy that the energy input unit inputs in one ignition cycle”, the greater the discharge current, so the ability to burn off the carbon on the insulator surface of the spark plug increases. For example, “electric energy input by the energy input unit at one ignition cycle” is used to continue the discharge generated by the spark plug by shutting off the ignition switch at the ignition timing.
Therefore, when the smoldering is judged, the energy input unit inputs electric energy, so that the carbon on the insulator surface can be burned out efficiently in a short time by the increased discharge current even in a situation where the combustion temperature is relatively low. it can. Therefore, according to the present invention, the progress of smoldering can be effectively suppressed.

It is a figure explaining the schematic structure of the engine system provided with the ignition control device by a 1st embodiment of the present invention. It is a figure explaining the structure of the ignition device of FIG. It is a time chart which shows a secondary voltage and a secondary current when a continuous discharge generate | occur | produces by the instruction | command of the energy control part of the electronic control unit of FIG. It is a time chart which shows a secondary current when the smoldering elimination discharge generate | occur | produces by the instruction | command of the energy control part of the electronic control unit of FIG. It is a flowchart explaining the control action of the electronic control unit of FIG.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In the embodiments, substantially the same components are denoted by the same reference numerals and description thereof is omitted.
In the following description, the magnitudes of current and voltage are expressed based on the magnitudes of absolute values. An increase in current and voltage means a case where the absolute value becomes large, and a decrease in current and voltage means a case where the absolute value becomes small. Means.

<First Embodiment>
The ignition control apparatus according to the first embodiment of the present invention is provided in the engine system shown in FIG.
[Engine system configuration]
First, a schematic configuration of the engine system 10 will be described with reference to FIG.
As shown in FIG. 1, the engine system 10 includes an engine 13 that is a spark ignition type internal combustion engine. The engine 13 burns an air-fuel mixture of air supplied from the intake manifold 15 through the throttle valve 14 and fuel injected from the injector 16 in the combustion chamber 17, and reciprocates the piston 18 by the explosive force at the time of combustion. . The reciprocating motion of the piston 18 is converted into a rotational motion by the crankshaft 19 and output. The combustion gas is released into the atmosphere through the exhaust manifold 20 and the like.

  An intake valve 22 is provided at the inlet of the combustion chamber 17, that is, the intake port of the cylinder head 21, and an exhaust valve 23 is provided at the outlet of the combustion chamber 17, that is, the exhaust port of the cylinder head 21. The intake valve 22 and the exhaust valve 23 are opened and closed by a valve drive mechanism 24. The valve timing of the intake valve 22 is adjusted by the variable valve mechanism 25.

  Ignition of the air-fuel mixture in the combustion chamber 17 is performed by the ignition device 30. The ignition device 30 includes an ignition plug 31, an ignition coil 32, an ignition circuit unit 33, and an electronic control unit 34. The ignition circuit unit 33 is operated based on a command from the electronic control unit 34, and the ignition plug 32 is switched from the ignition coil 32. By applying a high voltage to 31, a spark discharge is generated in the combustion chamber 17. The ignition device 30 will be described in detail later.

  The electronic control unit 34 has a microcomputer including a CPU, ROM, RAM, input / output ports, and the like, and includes a crank position sensor 35, a cam position sensor 36, a water temperature sensor 37, a throttle opening sensor 38, and an intake pressure sensor. It is electrically connected to various sensors such as 39. The electronic control unit 34 controls the operation state of the engine 13 by driving the throttle valve 14, the injector 16, the variable valve mechanism 25, the ignition circuit unit 33 and the like by executing program processing based on detection signals of various sensors. To do.

[Configuration of ignition device]
Next, the structure of the ignition device 30 will be described with reference to FIGS.
As shown in FIG. 2, the ignition device 30 includes a spark plug 31, an ignition coil 32, an ignition switch 40, a current detection circuit 41, an energy input unit 42, an electronic control unit 34, and the like. The ignition switch 40, the current detection circuit 41, and the energy input unit 42 are included in the ignition circuit unit 33. The ignition circuit unit 33 and the electronic control unit 34 constitute an ignition control device 5.

  The spark plug 31 has a pair of electrodes facing each other with a predetermined gap in the combustion chamber 17 of the engine 13, and discharges when a high voltage sufficient to cause dielectric breakdown is applied between the pair of electrodes. generate. In the following description, “high voltage” refers to a voltage that can cause discharge between a pair of electrodes of the spark plug 31.

  The ignition coil 32 includes a primary winding 43, a secondary winding 44, and a rectifying element 45, and constitutes a known step-up transformer. The primary winding 43 has one end connected to the DC power supply 46 and the other end grounded via the ignition switch 40. The DC power source 46 is constituted by a battery and can supply a constant DC voltage such as 12V. The secondary winding 44 is magnetically coupled to the primary winding 43, one end is grounded via a pair of electrodes of the spark plug 31, and the other end is grounded via a rectifier element 45 and a current detection resistor 47. Has been. The rectifying element 45 is composed of a diode and rectifies the direction of the current flowing through the secondary winding 44. The ignition coil 32 generates a high voltage in the secondary winding 44 by the mutual induction action of electromagnetic induction in accordance with a change in the current flowing through the primary winding 43, and applies this high voltage to the spark plug 31. In the present embodiment, only one ignition coil 32 is provided corresponding to one spark plug. In the following description, the current flowing through the primary winding 43 is “primary current I1”, and the current flowing through the secondary winding 44 is “secondary current I2”.

  Secondary voltage detection resistors 61 and 62 are connected in parallel with the spark plug 31 on the spark plug 31 side with respect to the secondary winding 44. The secondary voltage detection resistor 61 and the secondary voltage detection resistor 62 are provided in series with each other. The electronic control unit 34 can detect the voltage generated in the secondary winding 44 based on the potential between the secondary voltage detection resistor 61 and the secondary voltage detection resistor 62. Hereinafter, the voltage generated in the secondary winding 44 is referred to as “secondary voltage V2”.

  The ignition switch 40 is composed of an IGBT, a collector is connected to the ground side of the primary winding 43 of the ignition coil 32, an emitter is grounded, and a gate is connected to the electronic control unit 34. The emitter is connected to the collector via a rectifying element 48. The ignition switch 40 opens and closes according to the ignition signal IGT input to the gate. Specifically, the ignition switch 40 is turned on when the ignition signal IGT rises and turned off when the ignition signal IGT falls. The ignition signal IGT is a signal synchronized with the cam position, for example. The current path between the DC power supply 46 and the primary winding 43 is switched between conduction and interruption by the ignition switch 40.

The current detection circuit 41 is connected between the rectifying element 45 and the current detection resistor 47, and can detect the secondary current I2.
The energy input unit 42 includes a choke coil 51, a charge switch 52, a charge switch drive circuit 53, a capacitor 54, a rectifier element 55, a discharge switch 56, a rectifier element 57, and a discharge switch drive circuit 58.

  The choke coil 51 has one end connected to the DC power supply 46 and the other end grounded via the charging switch 52. The charge switch 52 is composed of a MOSFET, the drain is connected to the choke coil 51, the source is grounded, and the gate is connected to the charge switch drive circuit 53. The charge switch drive circuit 53 can drive the charge switch 52 to open and close.

  The capacitor 54 has one electrode connected to the ground side of the choke coil 51 via the rectifying element 55 and the other electrode grounded. The rectifying element 55 is composed of a diode, and prevents a backflow of current from the capacitor 54 to the choke coil 51 and the charging switch 52. The choke coil 51, the charging switch 52, the capacitor 54, and the rectifying element 55 constitute a boosting circuit that boosts and charges the voltage of the DC power supply 46.

  The capacitor 54 has one electrode connected to the ground side of the primary winding 43 via the discharge switch 56 and the rectifying element 57. The discharge switch 56 is composed of a MOSFET, the drain is connected to the capacitor 54, the source is connected to the ground side of the primary winding 43, and the gate is connected to the discharge switch drive circuit 58. The discharge switch drive circuit 58 can open and close the discharge switch 56. The rectifying element 57 is composed of a diode, and prevents a backflow of current from the ignition coil 32 to the capacitor 54.

  Here, there are two ways of changing the current flowing through the primary winding 43 in order to generate a high voltage in the secondary winding 44. First, the energization from the DC power supply 46 to the primary winding 43 is interrupted by the ignition switch 40, so that an electromotive force larger than the voltage of the DC power supply 46 is instantaneously generated by the primary winding due to the self-induction action of electromagnetic induction. 43. Second, by applying electric energy from the energy input unit 42, the voltage Vdc boosted from the DC power supply 46 is applied to the primary winding 43 to the primary winding 43, and the secondary side is caused by the self-induction action of electromagnetic induction. This is a method of generating voltage and current in

  In the present embodiment, the ignition control device 5 generates the discharge only by the first method described above, and generates the discharge by the first method described above, and then generates the discharge during the discharge. Ignition is carried out by properly using the second method in which electric energy is superimposed and the discharge is continued. Hereinafter, the discharge in the former case is referred to as “normal discharge”, and the discharge in the latter case is referred to as “continuous discharge”. In addition, a period in which the discharge is continued by supplying electric energy is described as a continuation period Tc.

  The charge switch drive circuit 53 opens and closes the charge switch 52 according to the charge signal IGC and the ignition signal IGT output from the electronic control unit 34. The charge signal IGC is a signal for instructing ignition by continuous discharge. Specifically, the charge switch drive circuit 53 can detect the capacitor voltage Vdc, which is the voltage of the capacitor 54, and turns on the charge switch 52 when the capacitor voltage Vdc is equal to or lower than a predetermined threshold at the rise of the charge signal IGC. Then, charging of the capacitor 54 is started. Further, the charging switch drive circuit 53 turns on the charging switch 52 and starts charging the capacitor 54 when the charging voltage Idc is equal to or lower than the threshold value during the rising of the charging signal IGC and at the rising time of the ignition signal IGT. When the charging switch 52 is turned on, energy is stored in the choke coil 51, and when the charging switch 52 is turned off, the electric energy released from the choke coil 51 is charged into the capacitor 54. The capacitor voltage Vdc is boosted by repeating the charging switch 52 ON and OFF. Charging of the capacitor 54 is terminated when the capacitor voltage Vdc reaches a predetermined voltage or when the charging signal IGC or the ignition signal IGT falls.

The discharge switch driving circuit 58 opens and closes the discharge switch 56 in accordance with the duration signal IGW and the target secondary current signal IGA output from the electronic control unit 34. The duration signal IGW is a signal that indicates the duration Tc. The target secondary current signal IGA is a signal for instructing a target secondary current I2 ^* that is a target value of the secondary current I2 in the duration Tc. Specifically, the discharge switch drive circuit 58 opens and closes the discharge switch 56 so that the secondary current I2 detected by the current detection circuit 41 matches the target secondary current I2 ^* while the duration signal IGW rises. To drive. When the discharge switch 56 is turned on, the electrical energy charged in the capacitor 54 is input to the ground side of the primary winding 43.

  The electronic control unit 34 includes an injection amount setting unit 71 that sets the fuel injection amount of the injector 16, an ignition switch control unit 72 that controls the ignition switch 40, an energy control unit 73 that controls the energy input unit 42, and a spark plug 31. A smolder determination unit 74 that determines whether smoldering occurs, a lean combustion operation determination unit 75 that determines whether or not the engine 13 is in the lean combustion operation, and the operation of the engine 13 from the lean combustion operation to the stoichiometric operation. An operation switching unit 76 forcibly switching to the combustion operation is provided.

The injection amount setting unit 71 outputs a drive signal IND for operating the drive circuit 59 of the injector 16. The drive signal IND is generated so that the fuel injection amount of the injector 16 matches the target injection amount. The target injection amount is set based on the operating state of the engine 13 determined from the detection signals of various sensors.
The ignition switch control unit 72 outputs an ignition signal IGT for controlling the opening / closing operation of the ignition switch 40. The ignition signal IGT is raised at a predetermined timing, for example, before the ignition timing (ignition timing) determined based on the cam position, starts energizing the ignition coil, is lowered at the ignition timing, cuts off the ignition current, and is ignited. To start.

The energy control unit 73 outputs a charging signal IGC, a target secondary current signal IGA, and a duration signal IGW for controlling driving of the energy input unit 42. The charge signal IGC is activated when a condition for performing ignition by continuous discharge is satisfied based on the operating state of the engine 13. In the present embodiment, the charging signal IGC is raised, for example, when the water temperature of the engine 13 is relatively low, when the output speed of the engine 13 is relatively low, or when the operation of the engine 13 is a lean combustion operation. . The target secondary current signal IGA is generated according to the target secondary current I2 ^* . The duration signal IGW is raised at the start of the duration Tc, and is lowered at the end of the duration Tc. In the present embodiment, the continuation period Tc is started when the secondary current I2 that has started discharging by turning off the ignition switch 40 becomes equal to or less than a predetermined threshold value.

As shown in FIG. 3, the smolder determination unit 74 has a maximum value V2_max of the secondary voltage V2 during the discharge period Tc during the predetermined target secondary current I2 ^* control when the continuous discharge is performed, which is larger than the threshold value V2_th. In this case, it is determined that smoldering has occurred in the spark plug 31. When smoldering occurs, the secondary voltage V2 becomes larger than the threshold value V2_th as indicated by a two-dot chain line, but when smoldering is not a concern, the secondary voltage V2 is set to the threshold value V2_th as indicated by a solid line. Smaller than. The smolder determination unit 74 corresponds to “smolder determination unit” described in the claims.

  Assuming that the ignition timing interval is the ignition cycle, the energy control unit 73, when smoldering is determined, until a predetermined number of executions Nc elapses from the determination, at a predetermined timing after the occurrence of discharge by the ignition switch 40. The smoldering elimination discharge control for causing the energy input unit 42 to input electric energy is performed. In the present embodiment, the number of executions Nc is set to a predetermined number in advance. In the present embodiment, when the smoldering elimination discharge control is performed, the discharge switch 56 is continuously turned on, and all the electric energy charged in the capacitor 54 of the energy input unit 42 is transferred to the primary winding 43 in the shortest time. It is thrown to the ground side. Accordingly, as shown in FIG. 4, the maximum value I2max (1) of the secondary current I2 during discharge by the discharge switch 56 is the maximum value I2max (2) of the secondary current I2 during discharge by the ignition switch 40, Compared with the maximum value I2max (3) of the secondary current I2 at the time of the standard continuous discharge indicated by a two-dot chain line, it is much larger. Due to this large current, carbon on the insulator surface of the spark plug 31 that causes smoldering is burned out efficiently in a short time. Smoldering elimination discharge is one aspect of continuous discharge. The energy control unit 73 corresponds to “energy control means” described in the claims.

The lean combustion operation determination unit 75 determines whether or not the engine 13 is in the lean combustion operation based on the operation state of the engine 13. The lean combustion operation determination unit 75 corresponds to “lean combustion operation determination means” recited in the claims.
When the engine 13 is in a lean combustion operation and the smoldering of the spark plug 31 is not eliminated even if the ignition cycle Nc has elapsed since the smoldering of the spark plug 31 is determined, 13 is switched to stoichiometric combustion operation. The lean combustion operation determination unit 75 corresponds to “lean combustion operation determination means” recited in the claims.

[Control operation of electronic control unit]
Next, the control process of the electronic control unit 34 will be described with reference to the flowchart of FIG. The series of processing shown in FIG. 5 is repeatedly executed from when the ignition switch is turned on until it is turned off.
In step S100, it is determined whether or not a condition for performing ignition by continuous discharge is satisfied. If the determination in step S100 is affirmative (S100: Yes), the process proceeds to step S120. On the other hand, when determination of step S100 is denied (S100: No), a process transfers to step S110.

In step S110, it is determined whether or not the smolder flag indicating that smoldering has occurred in the spark plug 31 is 1. If the determination in step S110 is affirmative (S110: Yes), the process proceeds to step S120. On the other hand, when determination of step S110 is denied (S110: No), a process transfers to step S230.
In step S120, the charge signal IGC is output, and the charge switch drive circuit 53 opens and closes the charge switch 52 to start boosting driving to boost the capacitor voltage Vdc. After step S120, the process proceeds to step S130.

In step S130, it is determined whether or not it is an ignition timing. The timing when the ignition signal IGT falls is the ignition timing. If the determination in step S130 is affirmative (S130: Yes), the process proceeds to step S140. On the other hand, when the determination in step S130 is negative (S130: No), step S130 is repeatedly executed.
In step S140, continuous discharge control for generating continuous discharge is performed. At this time, when the smoldering flag is 1, the duration Tc is set to the shortest time, the discharge switch 56 is continuously turned on, and all electric energy charged in the capacitor 54 of the energy input unit 42 is shortest. Is applied to the ground side of the primary winding 43, and smoldering elimination discharge occurs. After step S140, the process proceeds to step S150.

In step S150, it is determined whether or not the smolder flag is 1. If the determination in step S150 is affirmative (S150: Yes), the process proceeds to step S160. On the other hand, when the determination in step S150 is negative (S150: No), the process proceeds to step S170.
In step S160, a smoldering discharge counter indicating the number of times that smoldering discharge has been performed is incremented by one. After step S160, the process proceeds to step S170.

  In step S170, it is determined whether or not smoldering has occurred in the spark plug 31. In the present embodiment, when continuous discharge is performed in step S140, if the maximum value V2_max of the secondary voltage V2 during the discharge period Tc is smaller than the threshold value V2_th, it is determined that smoldering has occurred in the spark plug 31. . If it is determined as smoldering, the determination in step S170 is positive (S170: Yes), and the process proceeds to step S180. On the other hand, when determination of step S170 is denied (S170: No), a process transfers to step S190.

In step S180, the smoldering flag is set to 1, the continuation period Tc is set to the shortest time, and the discharge switch 56 is continuously turned on. After step S180, the process exits the routine shown in FIG.
In step S190, the smolder flag is reset to 0, and the smolder discharge counter is reset to 0. In addition, the duration Tc is reset to a preset standard value. After step S190, the process exits the routine shown in FIG.

In step S200, it is determined whether the smoldering discharge counter is equal to or greater than a predetermined number. If the determination in step S200 is affirmative (S200: Yes), the process proceeds to step S210. On the other hand, if the determination in step S200 is negative (S200: No), the process exits the routine shown in FIG.
In step S210, based on the operating state of the engine 13, it is determined whether or not the engine 13 is in a lean combustion operation. If the determination in step S210 is affirmative (S210: Yes), the process proceeds to step S220. On the other hand, if the determination in step S210 is negative (S210: No), the process exits the routine shown in FIG.
In step S220, the operation of the engine 13 is switched to the stoichiometric combustion operation. After step S220, the process exits the routine shown in FIG.

In step S230, it is determined whether or not it is an ignition timing. When the determination in step S230 is affirmed (S230: Yes), the process proceeds to step S240. On the other hand, when the determination in step S230 is negative (S230: No), step S230 is repeatedly executed.
In step S240, normal discharge control for generating normal discharge is performed. After step S240, the process exits the routine shown in FIG.

[effect]
As described above, in the first embodiment, the ignition control device 5 includes the ignition switch 40, the energy input unit 42, and the electronic control unit 34.
The energy input unit 42 can input electric energy to the ground side of the primary winding 43, and by adding the electric energy, a secondary current is added to the secondary winding 44 in a superimposed manner to maintain the discharge.
The electronic control unit 34 includes a smolder determination unit 74 and an energy control unit 73. The smolder determination unit 74 determines whether smoldering has occurred in the spark plug 31. When the smoldering of the spark plug 31 is determined, the energy control unit 73 instructs the energy input unit 42 to input electric energy until a predetermined number of executions Nc elapses from the determination.

  The greater the “electric energy input by the energy input unit 42 in one ignition cycle”, the higher the ability to burn off the carbon on the insulator surface of the spark plug 31. Therefore, when the smoldering is determined, the energy input unit 31 inputs electric energy, so that carbon on the insulator surface can be burned out efficiently in a short time even in a situation where the combustion temperature is relatively low. Therefore, according to the first embodiment, the progress of smoldering can be effectively suppressed, and misfire can be suppressed.

In the first embodiment, when the smoldering elimination discharge control is performed, the discharge switch 56 is continuously turned on, and all the electric energy charged in the capacitor 54 of the energy input unit 42 is the primary winding 43 in the shortest time. To the ground side.
Thus, the maximum value I2max (1) of the secondary current I2 at the time of smoldering discharge by the discharge switch 56 is the maximum value I2max (2) of the secondary current I2 at the time of discharge by the ignition switch 40, or at the time of standard continuous discharge. Compared to the maximum value I2max (3) of the secondary current I2 of With this large current, the carbon on the insulator surface of the spark plug 31 can be burned out more efficiently in a shorter time.

In the first embodiment, the electronic control unit 34 includes a lean combustion operation determination unit 75 and an operation switching unit 76.
The lean combustion operation determination unit 75 determines whether or not the engine 13 is in the lean combustion operation based on the operation state of the engine 13.
When the engine 13 is in a lean combustion operation and the smoldering of the spark plug 31 is not eliminated even if the ignition cycle Nc has elapsed since the smoldering of the spark plug 31 is determined, 13 is switched to stoichiometric combustion operation.
With this configuration, the combustion temperature is increased, and the ability to burn off the carbon on the insulator surface of the spark plug 31 can be further enhanced.

<Other embodiments>
In another embodiment of the present invention, the smolder determination is not limited to a method determined based on the secondary voltage during continuous discharge, but may be performed by another known smolder determination method. For example, the smoldering determination may be performed based on the insulation resistance value of the spark plug, may be performed based on the secondary current during normal discharge, or may be performed based on the change in the rise time of the secondary voltage leading to discharge. It may be performed based on the amount of secondary current leakage during application of the secondary voltage before discharging, or may be performed based on ion current generated in the combustion chamber after ignition.

In another embodiment of the present invention, the energy control unit of the electronic control unit does not necessarily have to input all the electric energy charged in the capacitor 54 in the shortest time when performing the smoldering elimination discharge control. For example, electrical energy may be intermittently input. At least, if the electric energy is input from the energy input unit so that the discharge continues longer or longer than the normal discharge sustaining current, the ability to burn off the carbon on the insulator surface of the spark plug can be enhanced.
In another embodiment of the present invention, the number of smoldering elimination discharges may be changed according to the smoldering degree. For example, the smoldering degree can be determined based on the difference between the secondary voltage V2_max and the threshold value V2_th. Specifically, the number of smolder elimination discharges may be increased as the smoldering degree is larger (as the difference between the secondary voltage V2_max and the threshold value V2_th is larger).

In the above-described embodiment, the duration Tc is started when the secondary current I2 increased by turning off the ignition switch 40 becomes equal to or less than a predetermined threshold. On the other hand, in another embodiment of the present invention, the duration period Tc may be started when a predetermined time elapses after the ignition switch is turned off, for example.
In the above-described embodiment, the secondary current I2 is feedback-controlled by opening and closing the discharge switch 56 so that the value detected by the current detection circuit 41 matches the target secondary current I2 ^* . On the other hand, in another embodiment of the present invention, the secondary current I2 is based on an open control in which the discharge switch 56 is driven to open and close by a drive signal set from a map or the like without depending on a feedback value from the current detection circuit. May be controlled.

  In the above-described embodiment, only one ignition coil 32, ignition switch 40, and energy input unit 42 are provided corresponding to one ignition plug 31, and the energy input unit 42 is a discharge generated by turning off the ignition switch 40. Discharging was continued by superimposing electric energy on the ground side of the primary winding 43 inside. On the other hand, in another embodiment of the present invention, two ignition coils and two ignition switches are provided corresponding to one ignition plug, and in the case of maintaining discharge alternately after main discharge, when smolder is detected The discharge sustaining current may be increased by boosting the coil power supply voltage to increase the energy, or by operating with overlapping operation intervals.

In another embodiment of the present invention, the ignition switch is not limited to the IGBT but may be composed of other transistors.
In other embodiments of the present invention, the charge switch may be composed of other transistors such as IGBTs.
In other embodiments of the present invention, the discharge switch may be composed of other transistors such as IGBTs.
In another embodiment of the present invention, the direct current power source is not limited to a battery, for example, a direct current stabilized power source in which an alternating current power source is stabilized by a switching regulator or the like, or a battery voltage boosted by a DC-DC converter or the like. It may be configured.

In the above-described embodiment, the electronic control unit 34 collectively has means for driving the throttle valve 14, the injector 16, the variable valve mechanism 25, the ignition switch 40, and the energy input unit 42. On the other hand, in another embodiment of the present invention, the means for driving the ignition switch and the energy input unit, that is, the ignition switch control unit and the energy control unit are different from the means for driving the throttle valve, the injector, and the variable valve mechanism. The unit may be provided.
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.

5 ... Ignition control device 13 ... Engine (internal combustion engine)
17 ... Combustion chamber 30 ... Ignition device 31 ... Ignition plug 32 ... Ignition coil 40 ... Ignition switch 42 ... Energy input part 43 ... Primary winding 44 ... Secondary Winding 46 ... DC power supply (power supply)
73 ... Energy control unit (energy control means)
74 ... Smoldering determination unit (smoldering determination means)

Claims (6)

An ignition device (30) for igniting the air-fuel mixture in the combustion chamber (17) of the internal combustion engine (13) is configured, and the current flowing through the primary winding (43) of the ignition coil (32) is changed to thereby cause mutual induction. An ignition control device (5) for generating a high voltage in a secondary winding (44) and generating a discharge in a spark plug (31) connected to the secondary winding,
An ignition switch (40) capable of switching between conduction and interruption of a current path between a power source and the primary winding, and generating a high voltage in the secondary winding by starting the discharge by cutting off the current path. When,
An energy input unit (42) for supplying a discharge sustaining current of the secondary winding;
Smolder determining means (74) for determining whether smoldering has occurred in the spark plug;
When it is determined that smoldering has occurred in the spark plug, where the ignition timing interval of the spark plug is an ignition cycle, the energy input is performed until the predetermined number of executions (Nc) of the ignition cycle elapses from the determination. Energy control means (73) for instructing the unit to input electric energy;
Equipped with a,
When it is determined that smoldering has occurred in the spark plug, the energy control means causes the electric energy charged in the energy input unit to be input to the ground side of the primary winding, so that the smoldering occurs before smoldering occurs. An ignition control device characterized by increasing a discharge sustaining current . An ignition device (30) for igniting the air-fuel mixture in the combustion chamber (17) of the internal combustion engine (13) is configured, and the current flowing through the primary winding (43) of the ignition coil (32) is changed to thereby cause mutual induction. An ignition control device (5) for generating a high voltage in a secondary winding (44) and generating a discharge in a spark plug (31) connected to the secondary winding,
An ignition switch (40) capable of switching between conduction and interruption of a current path between a power source and the primary winding, and generating a high voltage in the secondary winding by starting the discharge by cutting off the current path. When,
An energy input unit (42) for supplying a discharge sustaining current of the secondary winding;
Smolder determining means (74) for determining whether smoldering has occurred in the spark plug;
When it is determined that smoldering has occurred in the spark plug, where the ignition timing interval of the spark plug is an ignition cycle, the energy input is performed until the predetermined number of executions (Nc) of the ignition cycle elapses from the determination. Energy control means (73) for instructing the unit to input electric energy;
Equipped with a,
When it is determined that smoldering has occurred in the spark plug, the energy control means makes the maximum value (I2max (1)) of the discharge sustaining current larger than before smoldering. Control device. An ignition device (30) for igniting the air-fuel mixture in the combustion chamber (17) of the internal combustion engine (13) is configured, and the current flowing through the primary winding (43) of the ignition coil (32) is changed to thereby cause mutual induction. An ignition control device (5) for generating a high voltage in a secondary winding (44) and generating a discharge in a spark plug (31) connected to the secondary winding,
An ignition switch (40) capable of switching between conduction and interruption of a current path between a power source and the primary winding, and generating a high voltage in the secondary winding by starting the discharge by cutting off the current path. When,
An energy input unit (42) for supplying a discharge sustaining current of the secondary winding;
Smolder determining means (74) for determining whether smoldering has occurred in the spark plug;
When it is determined that smoldering has occurred in the spark plug, where the ignition timing interval of the spark plug is an ignition cycle, the energy input is performed until the predetermined number of executions (Nc) of the ignition cycle elapses from the determination. Energy control means (73) for instructing the unit to input electric energy;
Equipped with a,
When it is determined that smoldering has occurred in the spark plug, the energy control means sets the maximum value of the discharge sustaining current (I2max (1)) as the maximum value of the secondary current during discharge by the ignition switch. An ignition control device characterized by being larger than (I2max (2)) . The said energy input part (42) can boost and charge the voltage of the said power supply, and can input an electrical energy to the ground side of the said primary winding, The one of Claims 1-3 characterized by the above-mentioned. The ignition control device according to one item . The ignition switch generates a discharge in the spark plug by interrupting the current path in accordance with the ignition timing of the spark plug,
The said energy input part continues discharge by superimposing electric energy on the ground side of the said primary winding during generation | occurrence | production of the discharge by the said ignition switch, The discharge is continued . The ignition control device according to one item . Lean combustion operation determination means for determining whether or not the internal combustion engine is in a lean combustion operation;
When the internal combustion engine is in a lean combustion operation, and the smoldering of the spark plug is not eliminated even after the number of executions of the ignition cycle after it is determined that the smoldering has occurred in the spark plug, Operation switching means for switching the operation of the internal combustion engine to stoichiometric combustion operation;
The ignition control device according to any one of claims 1 to 5 , further comprising:

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