JP2015200266A - Ignitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignitor which properly determines the propriety of re-discharge according to a time at which blow-off occurs.SOLUTION: An ignitor blocks a primary current by an ignition switch, and inputs energy at a prescribed energy input period after generating the discharge of an ignition plug by a secondary current. Furthermore, the ignitor comprises a blow-off detection part which detects that the blow-off of discharge has occurred in an energy input period IGW after a start of the discharge by the ignition plug. When a secondary current I2 goes below a blow-off detection current threshold Ibo at a time tbo of a "second region" at which re-discharge after the blow-off cannot be performed, the blow-off detection part determines that the blow-off has occurred, and the ignitor stops an energy input to an ignition coil from an energy input part. By avoiding a waste energy input, waste power consumption and the consumption of an ignition plug electrode can be suppressed.

Description

  The present invention relates to an ignition device that controls the operation of a spark plug.

2. Description of the Related Art Conventionally, an ignition device for an internal combustion engine that generates electric discharge between electrodes of a spark plug and ignites an air-fuel mixture is known. In recent years, a technology for improving combustibility by generating a strong air flow in a combustion chamber in a lean combustion internal combustion engine for improving fuel efficiency has been developed. In such an internal combustion engine, the discharge is extended by the air flow, and the ignitability of the air-fuel mixture is improved. However, if the airflow is strong, the discharge blows out and re-discharge occurs immediately after that. Then, after the re-discharge, the phenomenon that the discharge is blown out again by the air flow is repeated, so that there is a problem that the electrode of the spark plug is consumed.
Therefore, for example, the ignition device disclosed in Patent Document 1 prevents the occurrence of a repeated discharge phenomenon by inhibiting re-discharge after the occurrence of blow-out, and suppresses the consumption of the spark plug electrode.

JP 2013-100811 A

  It is difficult to avoid the occurrence of blow-out in a very strong air current environment. In the prior art of Patent Document 1, since re-discharge is always prohibited regardless of when blow-off occurs, for example, if ignition is not performed before blow-off occurs, there is a risk of misfire as it is.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide an ignition device that appropriately determines whether or not re-discharge is possible depending on the timing when blow-off occurs.

The present invention is an ignition device that controls the operation of an ignition plug that ignites an air-fuel mixture in a combustion chamber of an internal combustion engine, and includes an ignition coil, an ignition switch, energy input means, and blow-off detection means.
The ignition coil is connected to a primary coil through which a primary current supplied from a DC power source flows and an electrode of a spark plug, and the primary current is energized and interrupted, and more specifically, a secondary voltage is generated by the interruption following energization. It has a secondary coil through which the secondary current flows.
The ignition switch is connected to a ground side that is opposite to the DC power source of the primary coil, and switches between energization and interruption of the primary current according to the ignition signal.

The energy input means can input energy in a predetermined energy input period (IGW) after the primary current is interrupted by the ignition switch and the spark plug is discharged by the secondary voltage generated by the interruption. Preferably, the energy input means can input energy in a superimposed manner with the same polarity as the secondary current from the ground side of the primary coil.
The blow-off detection means detects that a “blow-off” of the discharge has occurred after the start of discharge by the spark plug. Here, “detection” is not limited to direct detection but includes indirect estimation based on information related to blow-off.

  The ignition device of the present invention blows off in the “second region” after the passage of the “first region”, which is a time region in which re-discharge is possible after the spark plug blows off from the start of the energy input period. When the occurrence of blow-off is detected by the detection means, the energy input by the energy input means is stopped.

That is, in the present invention, the energy input period is divided into a “first region” from the start to a predetermined switching time and a “second region” from the switching to the end time. In the first region, since a relatively large amount of inductive energy remains in the ignition coil, re-discharge can be performed after the spark plug is blown out. On the other hand, in the second region, most of the inductive energy of the ignition coil is consumed, and even if energy is supplied from the primary coil, the secondary voltage is low, so it is not discharged but cannot be discharged again after being blown out. .
Therefore, when the occurrence of blow-off is detected in the second region, the energy input by the energy input means is stopped to avoid unnecessary energy input, thereby suppressing unnecessary power consumption and consumption of the spark plug electrode. it can.

Preferably, when the occurrence of blow-off is detected in the first region, the energy input by the energy input means is continued.
As a result, during the period in which re-discharge can be performed after blowing off, the energy supply to the air-fuel mixture is continued by positively performing re-discharge. That is, when blow-off occurs in the first region, priority is given to securing ignitability over suppression of spark plug electrode consumption.
In this way, it is possible to appropriately determine whether or not re-discharge can be performed according to the blow-off occurrence timing, and to ensure both ignitability and suppression of spark plug electrode consumption.

Furthermore, the ignition device of the present invention includes secondary current detection means for detecting a secondary current during the energy input period, and the blow-off detection means has an absolute value of the secondary current that is below a predetermined blow-off detection current threshold. It is preferable to determine that blow-off has occurred. When the blowout occurs, the absolute value of the secondary current rapidly decreases. Therefore, by monitoring the absolute value of the secondary current, it is possible to appropriately detect the occurrence of blowout.
Further, by providing the secondary current detecting means, the controllability of the secondary current can be improved by feedback control based on the detected current.

1 is a schematic configuration diagram of an engine system to which an ignition device according to an embodiment of the present invention is applied. The block diagram of the ignition device by one Embodiment of this invention. The time chart explaining the basic operation of the ignition device of FIG. The time chart explaining the operation | movement when blow-off occurs in the 1st field. The time chart explaining the operation | movement when blow-off occurs in the 2nd field. (A) The map which shows the relationship between an engine load and the period of a 1st area | region. (B) A map showing the relationship between the engine speed and the period of the first region.

Hereinafter, an ignition device according to an embodiment of the present invention will be described with reference to the drawings.
(One embodiment)
An ignition device according to an embodiment of the present invention is applied to an engine system mounted on a vehicle or the like. In the following description of the embodiment, the “internal combustion engine” described in the claims is referred to as an “engine”.

[Engine system configuration]
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 a spark ignition engine 13. The engine 13 is a multi-cylinder engine such as, for example, four cylinders, and FIG. 1 shows only a cross section of one cylinder. The configuration described below is similarly provided to other cylinders (not shown).
It is assumed that the engine system 10 of FIG. 1 does not have an EGR (exhaust gas recirculation) system. Alternatively, even when an EGR system is provided, the illustration is omitted because the relevance to the feature of the present embodiment is low. Further, illustration of the catalyst provided in the exhaust passage is also omitted.

  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 intake port of the cylinder head 21 that is the inlet of the combustion chamber 17, and an exhaust valve 23 is provided at the exhaust port of the cylinder head 21 that is the outlet of the combustion chamber 17. 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.

The air-fuel mixture in the combustion chamber 17 is ignited by causing a discharge between the electrodes of the spark plug 7 by the ignition device 30. The ignition device 30 operates the ignition circuit unit 31 based on a command from the electronic control unit 32 to apply a high voltage from the ignition coil 40 to the ignition plug 7, thereby generating a spark discharge in the combustion chamber 17.
The spark plug 7 has a pair of electrodes (see FIG. 2) facing each other with a predetermined gap in the combustion chamber 17 of the engine 13, and a high voltage sufficient to cause dielectric breakdown is applied between the pair of electrodes. When generated, a discharge is generated. 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, and is represented as “ECU” in the drawing.
As indicated by broken line arrows, the electronic control unit 32 receives detection signals from various sensors such as 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 39. . Based on detection signals from these various sensors, the electronic control unit 32 controls the operating state of the engine 13 by driving the throttle valve 14, the injector 16, the ignition circuit unit 31, and the like, as indicated by solid arrows.

[Configuration of ignition device]
Next, the configuration of the ignition device 30 will be described with reference to FIG.
As shown in FIG. 2, the ignition device 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 is grounded via a pair of electrodes of the spark plug 7, and the other end is connected via a rectifier element 43 and a secondary current detection resistor 47. Is grounded.

The current that flows through the primary coil 41 is referred to as a primary current I1, the current that is generated by energization and interruption of the primary current I1, and the current that flows 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, and applies this high voltage to the ignition 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, a secondary current detection resistor 47, and a secondary current detection circuit 48. The ignition circuit unit 31 has a blow-off detection unit 49 that is a characteristic configuration of the present invention.

The ignition switch 45 is composed of, for example, an IGBT (insulated gate bipolar transistor), and has a collector connected to the ground side of the primary coil 41 of the ignition coil 40, an emitter grounded, and a gate connected to the electronic control unit 32. Yes. 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 as “energy input means” includes an energy storage coil 52, a charge switch 53, a charge switch driver circuit 54, and a DCDC converter 51 including a rectifier element 55, a capacitor 56, a discharge switch 57, It has a discharge switch driver circuit 58 and a rectifying element 59, and continuously inputs energy to the ground side of the primary coil 41.

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 configured by, for example, a MOSFET (metal oxide semiconductor field effect transistor), and has a drain connected to the energy storage coil 52, a source grounded, and a gate connected to the driver circuit 54. The driver circuit 54 can drive the charging 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.
The capacitor 56 has one electrode connected to the ground side of the energy storage coil 52 via the rectifying element 55 and the other electrode grounded. Capacitor 56 stores the voltage boosted by DCDC converter 51.

The discharge switch 57 is configured by, for example, a MOSFET, the drain is connected to the capacitor 56, the source is connected to the ground side of the primary coil 41, and the gate is connected to the driver circuit 58. The 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 only the configuration for one cylinder is shown in FIG. 2, in reality, the configuration after the discharge switch 57 is provided in parallel for the number of cylinders, and the current path is provided for each cylinder before the discharge switch 57. The energy stored 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 17. The on-duty ratio of the discharge switch 57 is calculated and commanded to the driver circuit 58 by feedback control to make the secondary current I2 coincide with a target value (hereinafter referred to as “target secondary current I2 ^* ”).

The blow-off detection unit 49 as “blow-off detection means” detects that the blow-off of the discharge has occurred due to the airflow generated in the combustion chamber 17 after the start of the discharge by the spark plug 7. In particular, in the present embodiment, the blow-off detection unit 49 detects the occurrence of blow-out based on the value of the secondary current I2 detected by the secondary current detection circuit 48. The operation when the occurrence of blow-off is detected will be described later.
The above is the configuration of the ignition circuit unit 31.

Next, the electronic control unit 32 generates an ignition signal IGT and an energy input period signal IGW based on the operation information of the engine 13 acquired from various sensors such as the crank position sensor 35, and outputs it to the ignition circuit unit 31.
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 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 during the period when 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, the target secondary current signal IGA for instructing the target secondary current I2 ^* is input to the driver circuit 58.

[Ignition device operation]
Next, the operation of the ignition device 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 the following description, when referring to the magnitude of the negative current, the magnitude is expressed based on the “absolute current value”. That is, in the negative region, the current value increases from 0 [A] and increases as the absolute value increases, and the current increases or increases. As the absolute value approaches 0 [A] and decreases, the current decreases or decreases. That's it. Furthermore, in the comparison between the secondary current I2 and the negative threshold in FIGS. 4 and 5 described later, “the secondary current I2 is below the threshold” means “the absolute value of the secondary current I2 is below the threshold”. Means.

The period from time t3 to t4 during which the energy input period signal IGW is output is referred to as an “energy input period IGW” using the same symbol, and the control target value of the secondary current I2 in the energy input period IGW is expressed as “ Target secondary current I2 ^* ”. The target secondary current I2 ^* is set to a current that can maintain the ignition discharge well.
The secondary current I2 has a wave-like waveform that repeatedly increases and decreases within a control range in which the target secondary current I2 ^* is an intermediate value. In FIG. 3, the intermediate value of the control range is illustrated as the target secondary current I2 ^* , but the maximum value or the minimum value of the control range may be set as the control 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 during the off period after the charging switch 53 is turned on.
In this manner, the ignition coil 40 is charged and energy is accumulated in the capacitor 56 by the output of the DCDC converter 51 during the time t1 to 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, whereby a secondary current (discharge current) flows.
If energy is not input after ignition discharge is generated at time t2, the secondary current I2 approaches 0 [A] as time elapses as shown by a broken line, and the discharge ends when the discharge is attenuated to an extent that the discharge cannot be maintained. To do. Such an ignition system by discharge is called “normal ignition”.

  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. Then, the stored energy of the capacitor 56 is released and is supplied to the ground side of the primary coil 41. As a result, during the ignition discharge, the “primary current I1 resulting from the input energy P” is energized. The input energy P increases as the capacitor voltage Vdc accumulated up to time t2 increases.

At this time, the secondary coil 42 is superposed with the same polarity on the secondary current I2 energized between times t2 and t3 with the same polarity as the primary current I1 caused by the input energy P. The superimposition of the primary current I1 is performed every time the discharge switch 57 is turned on between time t3 and 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. When the secondary current I2 reaches a predetermined value, the discharge switch 57 is turned off and the superimposition of the primary current I1 is stopped. When I2 decreases and reaches a predetermined value, the discharge switch 57 is turned on again. Thereby, 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.

Thus, the control system in which energy is input to the ignition coil 40 from “the ground side of the primary coil 41” after the ignition discharge at time t2 was developed by the present applicant. Hereinafter, when simply referred to as “energy input control” in the present specification, this control method is meant.
On the other hand, as in the known multiple discharge method, a method of supplying energy to the ignition coil 40 from the battery 6 side of the primary coil 41 or the side opposite to the ignition plug 7 of the secondary coil 42 is comprehensively described as “conventional energy input”. It is called “control”. In the energy input control developed by the present applicant, compared to the conventional method, by inputting energy from the low voltage side, it is possible to sustain a ignitable state for a certain period while efficiently inputting the minimum energy. .

  Here, it is assumed that the ignition device 30 of the present embodiment is applied to a lean combustion engine that improves combustibility by generating a strong air flow in the combustion chamber 17. In such an engine, the discharge is extended by the air flow, and the ignitability of the air-fuel mixture is improved. However, if the airflow is strong, there is a risk that the discharge will blow out. In addition, there is a problem that the electrode of the spark plug 7 is consumed if wasteful re-discharge is performed after the discharge is blown out.

  Therefore, in the ignition device 30 of the present embodiment, the blow-off detection unit 49 detects the occurrence of blow-out based on the secondary current I2 detected by the secondary current detection circuit 48. Then, according to the time when blow-off occurs, it is determined whether to continue energy input to generate re-discharge, or to stop energy input and prohibit re-discharge.

Next, the operation when the discharge blows off during the energy input period IGW will be described with reference to FIGS. The symbols used in FIG. 3 are used for the times t2, t3, and t4 on the horizontal axis of the time charts of FIGS. 4 and FIG. 5, the energy input period signal IGW, the secondary current I2, the secondary voltage V2, and the primary current I1 are shown on the vertical axis. A current due to normal ignition is indicated by a broken line with respect to a secondary current I2 (solid line) due to energy input.
4 and 5, the time interval between the time t2 and the time t3 is exaggerated with respect to FIG. 3 in order to represent that the secondary current I2 rises at the timing when the discharge by the secondary voltage V2 is started. It shows.

As shown in FIGS. 4 and 5, the energy input period IGW includes the “first region” from the start time t3 of the input period to the predetermined switching time tx, and from the switching time tx to the end time t4 of the input period. It is divided into two time areas of “second area”.
In the first region, a relatively large amount of the inductive energy of the ignition coil 40 remains, so that re-discharge after the spark plug 7 is blown out is possible. On the other hand, in the second region, most of the inductive energy of the ignition coil 40 is consumed, and even if the energy is supplied, the high voltage is not reached and the re-discharge after blowing off cannot be performed.

  As shown in FIG. 4, when the secondary current I2 falls below the blow-off detection current threshold Ibo at time tbo in the first region, the blow-off detection unit 49 determines that blow-off has occurred, and the discharge switch driver The operation of the circuit 58 is maintained as it is. Therefore, energy input from the energy input unit 50 to the ignition coil 40 is continued. At this time, since a relatively large amount of inductive energy remains in the ignition coil 40, the secondary voltage V2 rises instantaneously and the spark plug 7 is re-discharged. Thus, during a period in which re-discharge can be performed after blowing off, re-discharge is positively performed and energy supply to the air-fuel mixture is continued.

  On the other hand, in FIG. 5, a waveform when blow-out does not occur is indicated by a two-dot chain line, and a waveform when blow-off occurs is indicated by a solid line. When the secondary current I2 falls below the blowout detection current threshold value Ibo at the time tbo in the second region, the blowout detection unit 49 determines that blowout has occurred and stops the operation of the discharge switch driver circuit 58. . Thereby, since the discharge switch 57 stops the on / off operation, the energy input from the energy input unit 50 to the ignition coil 40 is stopped.

In the second region, there is not enough inductive energy to perform re-discharge after blowing off. If energy input is continued even after the blow-off occurs in such a state, useless power that does not lead to ignition is consumed.
Therefore, in the present embodiment, when the occurrence of blow-off is detected, the energy input from the energy input unit 50 is stopped to avoid re-discharge.
The blow-off detection current threshold value Ibo may be a fixed value or may be variable according to the operating state of the engine 13 or the like.

Next, the setting of the period T of the first region, that is, the period T from the start time t3 of the energy input period IGW to the switching time tx will be described with reference to the map of FIG.
The period T of the first region is set shorter as the engine load is higher as shown in FIG. 6A and as the engine speed is higher as shown in FIG. 6B. This is because the higher the engine load or the number of revolutions, the more energy remaining in the ignition coil 40 is required for re-discharge, and the re-dischargeable period after the start of energy input is shortened.
The ignition device 30 calculates an appropriate period T of the first region based on the engine load and rotation speed information acquired by the electronic control unit 32, and changes the blow-off determination switching time tx from the next combustion cycle, for example. You may make it do.

(effect)
(1) The ignition device 30 of the present embodiment includes a blow-off detection unit 49 that detects that a discharge blow-off has occurred after the start of discharge by the spark plug 7, and cannot perform a re-discharge after the blow-off. When the occurrence of blow-off is detected in the second region, the energy input by the energy input unit 50 is stopped. Thus, wasteful power consumption and consumption of the spark plug electrode can be suppressed by avoiding wasteful energy input.

When the occurrence of blow-off is detected in the first region where re-discharge can be performed after blow-off, the energy input by the energy input unit 50 is continued. In a period in which re-discharge can be performed after blowing off, ignitability can be ensured by actively performing re-discharge and continuing to supply energy to the mixture.
In this way, it is possible to appropriately determine whether or not re-discharge can be performed according to the blow-off occurrence timing, and to ensure both ignitability and suppression of spark plug electrode consumption.

(2) The ignition device 30 of the present embodiment includes a secondary current detection circuit 48 that detects the secondary current I2 during the energy input period IGW, and the blow-off detection unit 49 has a predetermined absolute value of the secondary current I2. When it falls below the blow-off detection current threshold Ibo, it is determined that blow-off has occurred. When the blowout occurs, the absolute value of the secondary current I2 rapidly decreases. Therefore, by monitoring the absolute value of the secondary current I2, it is possible to appropriately detect the occurrence of blowout.
In addition, by providing the secondary current detection resistor 47 and the secondary current detection circuit 48, the actual value of the secondary current I2 can be accurately matched with the target secondary current I2 ^* by feedback control based on the detected current. .

(3) The ignition device 30 according to the present embodiment employs a method in which the 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 the energy input control method. 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.

(Other embodiments)
(A) The energy input unit 50 of the above embodiment employs a “method of inputting energy from the ground side of the primary coil” developed by the present applicant. In addition, as the “energy input means” of the present invention, any conventional multiple discharge method or “DCO method” disclosed in Japanese Patent Application Laid-Open No. 2012-167665 can be used as long as it can stop energy input during the energy input period. Or the like.

  Further, as shown in FIG. 3, the energy input control by the ignition device 30 having the configuration shown in FIG. 2 is performed after the charge switch signal SWc is turned on and off during the H level of the ignition signal IGT and the capacitor voltage Vdc is accumulated. The method is not limited to the method in which energy is input to the ground side of the primary coil 41 in the IGW. For example, by alternately turning on / off the charge switch signal SWc and the discharge switch signal SWd during the energy input period IGW, the energy accumulated in the energy accumulation coil 52 when the charge switch signal SWc is on is changed to the primary coil each time. 41 may be put on the ground side. In that case, the capacitor 56 may not be provided.

(A) The blow-off detection unit 49 of the above embodiment determines that blow-off has occurred when the secondary current I2 detected by the secondary current detection circuit 48 falls below the blow-off detection current threshold Ibo. In addition, the “blow-off detector” of the present invention may detect the occurrence of blow-out based on other parameters such as ion current.
When the secondary current I2 is not used for blow-off detection and the secondary current I2 is not feedback controlled (for example, feedforward control), the secondary current detection resistor 47 and the secondary current detection circuit 48 are not provided. Also good.

(C) The blow-off detection unit 49 is not limited to the configuration included in the ignition circuit unit 31 as in the above embodiment, and may be included in the electronic control unit 32. Further, it may be configured by either hardware or software.
(D) The ignition circuit unit 31 may be housed in a housing that houses the electronic control unit 32, or may be housed in a housing that houses the ignition coil 40.
The ignition switch 45 and the energy input unit 50 may be housed in separate housings. For example, the ignition switch 45 may be housed in a housing that houses the ignition coil 40, and the energy input unit 50 may be housed in the housing that houses the electronic control unit 32.

(E) The ignition switch is not limited to the IGBT, and may be composed of other switching elements 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) The direct current power source is not limited to a battery, and may be constituted by, for example, a direct current stabilized power source in which an alternating current power source is stabilized by a switching regulator or the like.

  (G) In the above embodiment, the energy input unit 50 boosts the voltage of the battery 6 by the DCDC converter 51. 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.

(H) The electronic control unit 32 includes a part for controlling the operating state of the entire engine 13, which is relatively unrelated to the characteristics of the above embodiment, in addition to the part for mainly controlling the ignition device 30. These may be configured as a single unit, or may be configured as separate units that communicate with each other via a signal line or the like.
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.

13 ... Internal combustion engine, 17 ... Combustion chamber,
30 ... Ignition device,
40 ... ignition coil,
41 ... primary coil, 42 ... secondary coil,
45 ... Ignition switch,
49 ・ ・ ・ Blow-off detector (blow-off detector),
50 ・ ・ ・ Energy input unit (energy input means),
6 ... Battery (DC power supply),
7: Spark plug.

Claims (4)

An ignition device (30) for controlling the operation of a spark plug (7) for igniting an air-fuel mixture in a combustion chamber (17) of an internal combustion engine (13),
A primary coil (41) through which a primary current supplied from a DC power source (6) flows, and a secondary voltage that is connected to the electrode of the spark plug and generates a secondary voltage due to energization and interruption of the primary current flows. An ignition coil (40) having a secondary coil (42);
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 (50) capable of supplying energy in a predetermined energy input period (IGW) after the primary current is interrupted by the ignition switch and the spark plug is discharged by the secondary voltage generated by the interruption. When,
Blow-off detection means (49) for detecting the occurrence of discharge blow-off after the start of discharge by the spark plug;
With
The occurrence of blow-off is detected by the blow-off detection means in the second region after the first region, which is the time region in which re-discharge is possible after the spark plug blows off from the start of the energy input period. The ignition device is characterized in that the energy input by the energy input means is stopped.   2. The ignition device according to claim 1, wherein in the first region, when the occurrence of blow-off is detected by the blow-off detection unit, the energy input by the energy input unit is continued. A secondary current detecting means (48) for detecting the secondary current during the energy input period;
The blow-off detection means is
3. The ignition device according to claim 1, wherein when the absolute value of the secondary current falls below a predetermined blow-off detection current threshold, it is determined that blow-off has occurred.   The ignition device according to any one of claims 1 to 3, wherein the energy input unit can input energy in a superimposed manner with the same polarity as the secondary current from the ground side of the primary coil. .

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