JP2010112209A - Discharge abnormality detection device and ignition control system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide discharge abnormality detection device of an internal combustion engine capable of highly accurately detecting the generation of smoking by discharge abnormality such as creeping discharge. <P>SOLUTION: This discharge abnormality detection device is applied to an igniter having an ignition coil composed of a primary coil and a secondary coil, and a spark plug for discharging a secondary current flowing to the secondary coil. Among electric power stored in the primary coil side before discharge, surplus electric power P remaining when finishing the discharge is made to instantly flow to the primary coil as a detecting current I1K when finishing its discharge t3, t13 and t23 (a detection current control means). A determination is made on whether or not the discharge is abnormal discharge of causing smoking based on the magnitude of the detecting current I1K (a discharge abnormality determining means). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a discharge abnormality detection device that detects a discharge abnormality in a spark plug.

  The discharge operation of a conventional general ignition device configured by including an ignition coil composed of a primary coil and a secondary coil and an ignition plug will be described. First, a primary current is supplied to the primary coil, and then the primary current is supplied. By shutting off, a secondary current is generated in the secondary coil, and this secondary current is discharged between the electrodes of the spark plug (spark discharge).

  Here, in normal discharge in the spark plug, discharge is performed from one electrode 12a to the other electrode 12b as indicated by a dashed line SP1 in FIG. On the other hand, when a conductive substance 12x such as carbon generated during combustion adheres to and accumulates on the insulator 12c that holds the electrode 12a, the creeping discharge discharges from one electrode 12a to the other electrode 12b through the conductive substance 12x. (See the wavy line SP10). When such creeping discharge occurs, the amount of heat transferred from the initial flame to the constituent members of the spark plug increases, so that the spread speed of the flame to the surrounding air-fuel mixture becomes slow and the ignition is delayed. Further, since the discharge position is not constant in creeping discharge, there is a concern that variations in ignition timing occur and fluctuations in output torque of the internal combustion engine increase.

In response to these concerns, Patent Document 1 describes a device that detects the occurrence of creeping discharge. In this apparatus, attention is paid to the pulsation in the primary current waveform that appears when the primary coil is energized prior to discharge (see FIG. 2 in Patent Document 1). That is, since the amplitude of this pulsation is small when creeping discharge occurs, it can be determined that creeping discharge has occurred if the integral value obtained by integrating the pulsating waveform is smaller than the determination threshold.
Japanese Patent Publication No. 6-80312

  However, in the above-mentioned conventional device that detects the pulsation appearing in the waveform of the primary current and calculates the magnitude of the pulsation, there is a limit to calculating the magnitude of the pulsation with high accuracy, so that the occurrence of creeping discharge is prevented. It is difficult to detect with sufficient accuracy.

  Even if creeping discharge does not occur, the electrodes 12a and 12b are disposed on the locus of the intake air flow (for example, tumble flow or swirl flow) in the combustion chamber or on the injection locus of the fuel injected in the cylinder. The arc due to normal ignition discharge indicated by reference numeral SP1 in FIG. 3B is affected by the intake air flow and the jet flow (see reference numeral F) and is deformed so as to gradually bend and extend each time ignition is repeated. There are cases (see symbols SP2, SP3, SP4). Even in the case where such arc elongation occurs, there is a concern that variations in the ignition timing are likely to occur and fluctuations in the output torque of the internal combustion engine increase. Therefore, it is desired to detect the occurrence of arc elongation as well as the detection of creeping discharge.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a discharge abnormality detection device and an ignition control system for an internal combustion engine that can detect the occurrence of discharge abnormality such as creeping discharge with high accuracy. There is.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to the first aspect of the invention, of the power stored on the primary coil side prior to the discharge at the spark plug, the surplus power remaining at the end of the discharge is used as a detection current at the end of the discharge to the primary coil. And a detection abnormality control means for determining whether or not the discharge is an abnormal discharge based on a value of the detection current.

  Here, power is stored on the primary coil side by energizing the primary coil prior to discharge, but the remaining power at the end of the discharge at the spark plug (surplus) of the stored power The amount of (electric power) is small when creeping discharge or arc elongation occurs. This is presumably because the amount of discharge at the spark plug increases when creeping discharge or arc elongation occurs.

  The present invention has been made on the basis of this finding, and the above-described surplus power is instantaneously supplied to the primary coil as a detection current at the end of discharge (detection current control means). Then, since the surplus power amount when creeping discharge or arc elongation occurs is small, the value of the detection current should be small. Therefore, in the present invention, since it is determined whether or not the discharge is abnormal based on the value of the detection current (discharge abnormality determination means), a discharge abnormality such as creeping discharge can be detected. In the conventional device described in Patent Document 1, discharge abnormality is detected based on “pulsations appearing in the waveform of the primary current subjected to discharge”, whereas according to the present invention described in claim 1, the discharge end point is detected. Since the discharge abnormality can be detected based on the “current value for instantaneously flowing detection”, the occurrence of the discharge abnormality can be detected with higher accuracy than the conventional device.

  By the way, the “detection current value” used for the determination by the discharge abnormality determination means, strictly speaking, the detection current flows during an instantaneous period (period illustrated by t3 to t4 in FIG. 9). (That is, the integrated value of the detection current) or, as described in claim 2, the detection current at the end of discharge (timing exemplified by reference numerals t3, t13, and t23 in FIG. 5). It may be an absolute value. Specifically, it may be determined that the discharge is abnormal when the integrated value is below a threshold value, and the absolute value of the detection current at the end of the discharge is below the threshold value as described in claim 2. In some cases, it may be determined that the discharge is abnormal. However, according to the second aspect of the invention, which is determined based on the absolute value of the detection current at the end of the discharge, an integration circuit or the like required for determination based on the integral value of the detection current can be eliminated. The occurrence of discharge abnormality can be detected with a simple circuit configuration.

  According to a third aspect of the present invention, the ignition device includes a power supply circuit that stores electric power to be supplied to the primary coil, and supplies the electric power stored in the power supply circuit to the primary coil a plurality of times. Multiple discharges are performed during a single combustion stroke, and the detection current control means uses the surplus power stored in the power circuit as the detection current as the primary coil. It is characterized by flowing instantly.

  Here, in the case of an ignition device in which multiple discharges are not performed and the discharge during the combustion stroke is performed once, the power supply circuit is often not provided. In this case, electric power is stored in the primary coil, and surplus electric power in the primary coil may be instantaneously supplied as a detection current. However, in this case, the difference in the detection current value due to the presence or absence of abnormal discharge is not likely to appear. On the other hand, in the ignition device for multiple discharge according to the third aspect, the surplus power in the power supply circuit is instantaneously supplied as the detection current, so that the difference in the detection current value due to the occurrence of abnormal discharge is significant. Appear in Therefore, the occurrence of discharge abnormality can be detected with high accuracy.

  The invention according to claim 4 is applied to an ignition device comprising: an ignition coil comprising a primary coil and a secondary coil; and an ignition plug for discharging a secondary current flowing through the secondary coil. An electrical storage detection means for detecting electric power stored on the primary coil side, and / or, based on a value detected during the discharge period or at the end of the discharge among the detection values by the electrical storage detection means, the discharge is an abnormal discharge. A discharge abnormality determining means for determining whether or not there is a discharge abnormality.

  Here, power is stored on the primary coil side by energization of the primary coil that is performed prior to the discharge, but the stored power decreases with the discharge at the spark plug. And the speed | rate of the electrical storage reduction becomes quick when creeping discharge and arc elongation arise. This is presumably because the amount of discharge at the spark plug increases when creeping discharge or arc elongation occurs. Therefore, discharge abnormality such as creeping discharge can be detected based on the value detected during the discharge period or at the end of the discharge among the detected value of the electric power stored on the primary coil side.

  In particular, as described in claim 5, if it is determined that the discharge is abnormal when the detected value at the end of the discharge is below a preset threshold value, “pulsations appearing in the waveform of the primary current used for the discharge” The occurrence of discharge abnormality can be detected with higher accuracy than the conventional apparatus that detects discharge abnormality based on "."

  By the way, when the creeping discharge occurs, the conductive substance 12x is burned out by the creeping discharge, and the creeping discharge may not occur in the next discharge. Therefore, in the invention according to claim 6, when it is determined that there is an abnormality by the discharge abnormality determination means, the number of discharges performed during one combustion stroke is increased from the normal number. Thereby, it is possible to increase the possibility that creeping discharge is eliminated by the burning.

  However, in the case of an ignition device that performs multiple discharge, for example, even if a creeping discharge is detected at the first discharge, the conductive material 12x is burned out by the creeping discharge at that time, and a creeping discharge is detected at the second discharge. May not be. Increasing the number of discharges up to such a case is not desirable because unnecessary discharge is performed. Therefore, as described in claim 7, the unnecessary discharge can be avoided by increasing the number of discharges only when it is determined that there is an abnormality with respect to the last discharge among the regular number of discharges.

  The invention according to claim 8 is characterized in that the discharge related to the increase is performed during an exhaust stroke period. According to this, it can be avoided reliably that the discharge increased for the purpose of burning out causes ignition.

  The invention according to claim 9 is an ignition control system comprising the discharge abnormality detecting device and at least one of the ignition coil and the spark plug. According to this ignition control system, the various effects described above can be exhibited in the same manner.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
In the present embodiment, the discharge abnormality detection device according to the present invention is applied to an ignition control system of an on-vehicle multi-cylinder gasoline engine (internal combustion engine). An engine to which the present embodiment is applied is a spray guide type in-cylinder injection engine 10 as illustrated in FIG. In the spray guide method, when fuel is directly injected from the fuel injection valve 11 into the cylinder, the fuel spray is injected during the compression stroke so that the air-fuel ratio is leaner than the stoichiometric air-fuel ratio. This is a method of performing ignition when the portion 11a) passes near the electrodes 12a, 12b (see FIG. 3) of the spark plug 12, and is applied to an internal combustion engine capable of stratified lean combustion. Further, the engine 10 is provided with a supercharger 13 that supercharges intake air using exhaust as a driving force.

  Next, a schematic configuration of an ignition control system for controlling discharge (spark) at the spark plug 12 will be described with reference to FIG.

  In FIG. 2, the ignition coil 14 provided for each cylinder of the engine 10 includes a primary coil 14a and a secondary coil 14b. One end of the primary coil 14a is connected to the high potential (+12 volts) side of the battery 16 via the power supply circuit 15, and the other end thereof is connected to the IGBT 17 as a switch means and a current detection resistor 18 (shunt resistor). Grounded. The output of the current detection resistor 18 is input to the ignition control circuit 19. The gate of the IGBT 17 is connected to the ignition control circuit 19, and the IGBT 17 is controlled to be turned on / off by the ignition control circuit 19. The secondary coil 14 b has one end connected to the spark plug 12 and the other end grounded via the Zener diode 20. The power supply circuit 15 boosts the battery voltage VB, the output voltage of the power supply circuit 15 is Vo, and the currents flowing through the primary coil 14a and the secondary coil 14b are the primary current I1 and the secondary current I2, respectively.

  As is well known, the electronic control unit (hereinafter referred to as ECU 21) is mainly composed of a microcomputer comprising a CPU, a RAM, a ROM, etc., and executes various control programs stored in the ROM to change various operating states of the engine. It is something to control. In the ignition timing control, the ECU 21 acquires operating state information indicating the operating state of the engine such as the engine speed and the accelerator operation amount, and calculates an optimal ignition timing based on the operating state information. Then, an ignition signal IGt (see FIG. 2) is generated according to the ignition timing and output to the ignition control circuit 19. Further, in the present ignition control system, multiple discharge control is performed in which ignition discharge at the spark plug 12 is intermittently generated a plurality of times within one combustion stroke. This avoids a misfire state in which ignition does not occur during the combustion stroke period.

  The ignition control circuit 19 outputs a drive signal IG (see FIGS. 2 and 4) for turning on and off the IGBT 17 based on the ignition signal IGt input from the ECU 21. Specifically, the ignition control circuit 19 outputs a drive signal IG triggered by the input of the ignition signal IGt as a signal for instructing the start of multiple discharges to the ignition control circuit 19. The drive signal IG is a pulse signal that is turned on / off in response to energization of the primary coil 14a and energization of the secondary coil 14b. The IGBT 17 operates so as to switch between energization and interruption of the primary coil 14a in accordance with on / off of the drive signal IG.

  Here, as shown in FIG. 3A, as described above, when the conductive material 12x is deposited on the insulator 12c of the spark plug 12, creeping discharge (see the wavy line SP10) occurs. When such creeping discharge occurs, current leaks from the insulator 12c, so that a sufficient voltage cannot be obtained at the center electrode 12a, which is the original discharge location. As a result, a state in which ignition is not caused by discharge at the center electrode 12a is brought about. Then, when the beat state occurs, there are concerns about problems such as ignition delay, variations in ignition timing, fluctuations in engine output torque, misfire, and the like.

  In response to this concern, in the present embodiment, when the occurrence of a stagnation state due to a discharge abnormality is detected by the discharge abnormality detection device described below, and the occurrence of the swell state is detected, the deposited conductive material 12x is discharged. The self-cleaning function, such as burning out by, prevents the recurrence of the roaring state (details will be described later).

  The discharge abnormality detection device includes an ECU 21 and an ignition control circuit 19, and detects the occurrence of a turning state by controlling to output a drive signal IG as shown in FIGS. 4 (a) and 5 (a). (A), (b), (c), (d), and (e) in FIG. 4 and FIG. 5 are a drive signal IG, a primary current I1, a secondary current I2, a secondary voltage V2, and It is a time chart which shows the change of the electric power (charge amount) stored in the primary coil side.

  In the example of the multiple discharge shown in the figure, the normal number of discharges in one combustion stroke period is set to 3, and the presence or absence of occurrence of sag is determined for each discharge. FIG. 4 shows a case where no sag has occurred in all three discharges, and FIG. 5 shows a case in which sag has occurred during the first discharge. However, in the example of FIG. 5, the conductive material 12x is burned out and self-cleaned at the time of the first discharge, and the second and third discharges are normally discharged without any distortion.

  Next, the operation of the multiple discharge and the control contents for detecting the sag will be described with reference to FIGS. 4 and 5.

  First, reference numeral t1 in the drawing indicates a point in time when the ignition signal IGt output from the ECU 21 is in a multiple discharge start command state (pulse-on state), and the ignition control circuit 19 is t1 when the multiple discharge start is commanded. At the time, the drive signal IG is set to the energization command state (pulse on state). Then, the IGBT 17 is turned on and the primary current I1 flows through the primary coil 14a, and the power supplied from the battery 16 is stored in the power supply circuit 15.

  Thereafter, the drive signal IG is turned off at time t2 when a preset predetermined time T10 has elapsed. Then, the IGBT 17 is turned off and the flow of the primary current I1 is interrupted, thereby generating a secondary current I2 in the secondary coil 14b, and this secondary current I2 is discharged (sparked) between the electrodes 12a and 12b. .

  Thereafter, the drive signal IG is instantaneously turned on at time t3 when a preset predetermined time T20 has elapsed. Then, although the IGBT 17 is turned on instantaneously and the primary current I1 flows, the discharge between the electrodes 12a and 12b ends. That is, the first discharge of the multiple discharge is completed.

  After the first discharge is completed, the drive signal IG is turned on at time t11 when a predetermined time T30 has passed. Thereby, charging on the primary side used for the second discharge, that is, second charging in the power supply circuit 15 is started. Thereafter, similarly to the first discharge operation, the drive signal IG is turned off at the time t12 to start the second discharge, and the drive signal IG is turned on at the time t13 to end the second discharge. To do.

  Thereafter, similarly to the first discharge operation, the drive signal IG is turned on at time t21, and charging on the primary side used for the third (last) discharge is started. Thereafter, at time t22, the drive signal IG is turned off to start the third discharge, and at time t23, the drive signal IG is turned on instantaneously to end the third discharge.

  Next, with respect to changes in the amount of power (charge amount) stored in the power supply circuit 15 during the periods t1 to t2, t11 to t12, and t21 to t22 in which the primary current I1 flows, FIGS. 4E and 5E ).

  The value of the primary current I1 increases and the charge amount of the power supply circuit 15 also increases in proportion to the elapsed time from the start of energization of the primary current I1 (time t1) (see FIG. 4E). Then, the values of the secondary current I2 and the secondary voltage V2 decrease with the passage of time from the discharge start time (time t2). Further, the value of the primary current I1 becomes zero at the start of discharge, and the charge amount of the power supply circuit 15 starts to decrease.

  Then, since the discharge is terminated by instantaneously turning on the drive signal IG, the primary current I1 flows instantaneously at the end of the discharge (time t3). This is because the charge amount remains at the end of discharge. Hereinafter, this remaining amount is referred to as surplus power P.

  As the surplus power P increases, the magnitude of the primary current I1 that instantaneously flows at the end of discharge increases. Here, when the above-described creeping discharge occurs, the rate of decrease in the charge amount increases (see FIG. 5E). That is, the gradient indicated by the symbol Pa increases (strictly speaking, the absolute value of the gradient coefficient increases). As a result, the surplus power P is reduced, and the value of the primary current I1 (hereinafter referred to as “detection current I1K”) that flows instantaneously at the end of discharge is reduced. In short, when the creeping discharge occurs, the detection current I1K becomes small. In this embodiment, paying attention to this point, it is determined that the crease due to creeping discharge occurs when the detection current I1K is lower than the threshold value I1th.

  Incidentally, the dotted lines shown in the discharge periods t2 to t3 in FIGS. 5 (c) and 5 (d) indicate a state where the degree of bending is poor, that is, a case where there is a large amount of electric leakage due to creeping discharge. The increase rate of the secondary current I2 becomes faster. That is, the inclination indicated by the symbol I2a increases (strictly, the inclination coefficient increases). In addition, the amount of drop in the secondary voltage increases. That is, the peak value of the secondary current I2 indicated by the symbol V2peak is lowered. This tendency is the same even in the case of the present embodiment where the degree of fluttering is slight. Compared with normal discharge, the increase rate of the secondary current I2 is faster, and the drop amount of the secondary voltage V2 is larger. (See the solid lines in FIGS. 5C and 5D).

  However, this tendency does not appear noticeably unless the degree of resentment is poor. In addition, since the secondary voltage V2 is extremely higher than the primary voltage and there is a lot of superimposed noise, it is actually very difficult to obtain a waveform as shown in FIGS. is there. Therefore, if it is attempted to detect the occurrence of a turn based on the secondary current I2 and the secondary voltage V2, the detection accuracy cannot be sufficiently ensured.

  Next, a control procedure in which the microcomputer of the ECU 21 detects the turning as described above will be described with reference to the flowcharts of FIGS.

  6 and 7 are flowcharts showing the processing procedure of the turn detection control executed by the microcomputer of the ECU 21.

  The series of processes shown in the figure is started with the start of multiple discharge as a trigger. First, in step S10, the IGBT 17 is turned on to start storage on the primary coil side, that is, storage in the power supply circuit 15. If it is determined in step S11 that the predetermined time T10 (see FIG. 4) has elapsed since the IGBT 17 was turned on, in the subsequent step S12, the IGBT 17 is turned off to start discharging on the secondary coil side. When it is determined in step S13 that a predetermined time T20 (see FIG. 4) has elapsed since the IGBT 17 was turned off, in the subsequent step S14 (detection current control means), the IGBT 17 is turned on instantaneously and on the secondary coil side. End the discharge.

  Here, when turning on instantaneously, the length of the ON time is set to, for example, a calculation cycle of the CPU or a calculation cycle of the processing of FIG. Further, if the on-time is excessively long, the amount of power stored prior to the next discharge is reduced, so it is desirable to set it as short as possible. For example, it is desirable to set the on-time to a time shorter than the discharge time T20.

  Next, in step S15, the value of the detection current I1K is acquired. Specifically, the ignition control circuit 19 detects the IGBT side potential with respect to the shunt resistor 18, and the ECU calculates the value of the detection current I1K based on the detected potential. It should be noted that the potential detection timing in the ignition control circuit 19 is set to the discharge end time t3, t13, t23, and if the detection timing is synchronized with the timing for instantaneously turning on the IGBT 17, a circuit such as a peak hold circuit can be used. The value of the detection current I1K at the discharge end times t3, t13, and t23 can be acquired without necessity.

  Next, when it is determined in step S16 that the predetermined time T30 (see FIG. 4) has elapsed since the IGBT 17 was turned on instantaneously, the number N of discharges performed in step S12 is the normal number of multiple discharges (this example) Then, it is determined whether or not it has reached 3 times. When it is determined that the regular number of discharges has been performed (S17: YES), the series of processes in FIG. 6 is terminated, and when it is determined that the number of discharges N has not reached the regular number (S17: NO), The stored number N of discharges (initial value is 1) is added by one, and the processes after step S10 are repeatedly executed.

  FIG. 7 is a process for determining the presence or absence of a stagnation state due to discharge abnormality based on the value of the detection current I1K acquired in step S15 of FIG. In the process of FIG. 6, the detection current I1K is acquired for each regular number of discharges. However, the turning determination process in FIG. 7 is performed for each acquired detection current I1K.

  In the turning determination process, first, in step S20 (discharge abnormality determination means), it is determined whether or not the acquired value of the detection current I1K is lower than a preset threshold value I1th. In the present embodiment, the detection current I1K has a positive value, but in an ignition circuit configured to have a negative value, it is determined whether or not the absolute value of the detection current I1K is below the threshold value I1th. To do. When a negative determination is made that I1K <I1th is not satisfied (S20: NO), it is determined in the subsequent step S21 that the discharge state is normal and the discharge state is normal (normal determination). On the other hand, when an affirmative determination is made that I1K <I1th (S20: YES), it is determined in subsequent step S22 (discharge abnormality determination means) that the discharge is abnormal and the state of discharge is abnormal (brightness determination). To do.

  If it is determined that the turn is detected, it is determined in subsequent step S23 whether or not the detection current I1K used for the corresponding determination is the detection current I1K acquired for the last discharge, that is, the third discharge. judge. If it is determined that the current I1K for the last discharge is the detection current I1K (S23: YES), multiple discharges are performed by increasing the normal number of times. A one-dot chain line in FIG. 5 shows a mode in the case where such an additional discharge is performed. Reference numeral t32 in the figure indicates a point in time when the additional discharge is started, and reference numeral t31 is performed prior to the additional discharge. A time point at which power storage to the power supply circuit 15 is started is shown.

  This additional discharge is not intended to ignite but is intended to self-clean by burning out the conductive material 12x. Therefore, it is desirable to perform this additional discharge during an exhaust stroke period that does not ignite with the discharge.

  On the other hand, even if the determination is made in step S22, if the determination is not made for the last discharge (S23: NO), the additional discharge in step S24 is not performed, 7 is completed. If it is not the last discharge, even if it is judged to be worn, it may be burned out by the discharge at that time and self-cleaned. Therefore, if it is not determined that the last discharge is over, no additional discharge is required.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) At the discharge end time t3, t13, t23, surplus power P in the power supply circuit 15 is instantaneously supplied to the primary coil 14a as a detection current. Then, since the surplus electric power P when creeping discharge or arc elongation occurs is small, the magnitude (absolute value) of the detection current I1K should be small. Therefore, in this embodiment, when the magnitude of the detection current I1K is less than the threshold value I1th, it is determined that the crease due to creeping discharge has occurred. In the conventional device described in Patent Document 1, the occurrence of swell is detected based on “pulsations appearing in the waveform of the primary current I1 at the beginning of the charging period T10”, whereas according to the present embodiment, the discharge end time t3 is detected. , T13, and t23, the occurrence of the beat can be detected based on “the magnitude of the detection current I1K that flows instantaneously”, so that the occurrence of the beat can be detected with higher accuracy than the conventional device.

  (2) The conventional device described in Patent Document 1 requires an integration circuit for integrating the value of the detection current I1K in order to determine the sag based on the magnitude of the pulsation. On the other hand, in the present embodiment, since the sag is determined based on the magnitude of the detection current I1K that flows instantaneously, the conventionally required integration circuit can be dispensed with, and the sag occurrence can be detected with a simple circuit configuration. .

  (3) Here, in the ignition control system that does not include the power supply circuit 15, when the primary current I1 is supplied prior to the discharge, electric power is stored in the primary coil 14a. In this case, the surplus power in the primary coil 14a may be instantaneously supplied as a detection current. However, in this case, the difference in the magnitude of the detection current due to the presence or absence of distorting is not likely to appear. On the other hand, in the present embodiment including the power supply circuit 15 required for multiple discharges, the surplus power P in the power supply circuit 15 is instantaneously supplied as the detection current I1K. The difference appears prominently. Therefore, it is possible to detect the occurrence of warp with high accuracy.

  (4) When the occurrence of a blow is detected (S20: YES), in addition to the regular number of discharges required for multiple discharges, the discharge for burn-out is performed, so that the possibility of the burn being eliminated by burn-off can be increased. . In addition, since the burnout discharge is performed only when the occurrence of the burn is detected with respect to the last discharge of the regular number of times, it is possible to avoid performing unnecessary discharge. Moreover, since the discharge for burning is performed during the exhaust stroke, it is possible to reliably avoid the occurrence of ignition by the discharge for burning.

  (5) In the spray guide type in-cylinder injection engine 10 illustrated in FIG. 1, the electrodes 12a and 12b are disposed on the fuel injection locus 11a. Then, as described above with reference to FIG. 3B, the arc SP1 due to the normal ignition discharge is easily affected by the jet F and the arc elongation SP2, SP3, SP4 is likely to occur. Further, since the conductive substance 12x such as carbon generated during combustion easily adheres to the spark plug 12, creeping discharge is likely to occur. Therefore, according to the present embodiment in which the discharge abnormality detection device is applied to the in-cylinder injection engine 10 in which arc elongation or creeping discharge is likely to occur in this way, the above-described effect that the occurrence of the sag due to the discharge abnormality can be detected with high accuracy. It is suitably exhibited.

  (6) Furthermore, the discharge abnormality detection device according to the present embodiment is applied to the engine 10 (see FIG. 1) provided with the supercharger 13. In such an engine 10, the arc stretches SP2, SP3, and SP4 are likely to occur due to the influence of the supercharged intake air flow. Therefore, according to the present embodiment applied to the engine 10 in which arc elongation is likely to occur in this way, the above-described effect that it is possible to detect the occurrence of a sag due to a discharge abnormality with high accuracy is suitably exhibited.

(Second Embodiment)
By the way, in the first embodiment, in setting the elapsed time T30 (see FIG. 5) from the discharge end time t3 to the start of energization of the primary current I1 used for the next discharge (power storage start), the power supply from the discharge end time t3 is set. Power storage is started after the charge amount of the circuit 15 decreases to zero. That is, the value of the primary current I1 at the next power storage start time t11 is zero.

  On the other hand, in the present embodiment, as shown in FIG. 8, the value of the primary current I1 at the next power storage start time t11 is larger than zero. In the example of FIG. 8, wrinkles are generated during the first discharge, and no wrinkles are generated during the second discharge. Therefore, the value of the primary current I1 at the second power storage start time t11 is smaller than the value of the primary current I1 at the third power storage start time t21.

  By the way, since it is a matter of how many times the discharge is ignited in the multiple discharge, the shorter the discharge interval, the less the variation in the ignition timing. However, as a contradiction, the shorter the discharge interval, the faster the IGBT 17 is turned on and off, increasing the burden on the circuit. Therefore, when performing multiple discharge by the method of FIG. 5, there is a merit that the burden on the circuit can be reduced compared to the method of FIG. 8, and when performing multiple discharge by the method of FIG. Compared with the method of FIG. 5, there is an advantage that variation in ignition timing can be reduced.

(Third embodiment)
In the first embodiment, the occurrence of sag is detected based on the magnitude (absolute value) of the detection current I1K. On the other hand, in the present embodiment, as shown in FIG. 9, the amount of detection current I1K that flows during the instantaneous period, that is, the integrated value of detection current I1K (the area indicated by the oblique lines in FIG. 9B). Based on this, the occurrence of squealing is detected.

  According to the present embodiment, it is possible to detect the occurrence of warpage with higher accuracy. However, in this embodiment, an integration circuit is required. However, according to the first embodiment, the integration circuit can be made unnecessary, and the occurrence of sag can be detected with a simple circuit configuration.

(Fourth embodiment)
In the first embodiment, as shown in FIG. 1, the application target is the engine 10 in which the electrodes 12a and 12b of the spark plug 12 are arranged on the fuel injection locus 11a. On the other hand, in this embodiment, as shown in FIG. 10, although the electrodes 12a and 12b are at positions deviating from the fuel injection locus 11a, the fuel is injected from the fuel injection valve 11 in a plurality of spray patterns 11b. The electrodes 12a and 12b are disposed between the plurality of spray patterns 11b. In addition, FIG.10 (b) is A arrow directional view of (a).

  Even in an engine having such a configuration, a conductive substance 12x such as carbon generated during combustion easily adheres to the spark plug 12, and therefore creeping discharge is likely to occur. Therefore, according to the present embodiment in which the discharge abnormality detection device similar to that of the first embodiment is applied to the engine in which creeping discharge is likely to occur, various effects described in the first embodiment are suitably exhibited. The

(Fifth embodiment)
In the first embodiment, the occurrence of sag is detected based on the magnitude of the primary current I1 (detection current I1K) that instantaneously flows at the discharge end times t3, t13, and t23, but the discharge end times t3, t13, The occurrence of squealing may be detected based on the surplus power P (see FIG. 5E) of the power supply circuit 15 at t23. Specifically, a circuit (electric storage detection means) for detecting the charge amount of the power supply circuit 15 is provided, the charge amount at the discharge end points t3, t13, and t23 is detected as the surplus power P, and a predetermined timing among the detected values If the value of the surplus power P acquired at the time of the end of discharge (in the present embodiment) is smaller than a preset threshold value, it is determined that there is a twist.

  In addition, instead of detecting the occurrence of the fluctuation based on the surplus power P acquired at a predetermined timing, the rate of decrease in the charge amount of the power supply circuit 15 in the discharge periods t2 to t3, that is, the symbol Pa in FIG. The occurrence of sag may be detected based on the inclination. Specifically, a plurality of values of the surplus power P are sampled during the discharge periods t2 to t3, the slope Pa is calculated based on the sampled values, and the calculated slope Pa (strictly, the absolute value of the slope coefficient) is If it is larger than the preset threshold value, it is determined that the beat has occurred.

  In addition, instead of detecting the occurrence of squealing based on the charge amount gradient Pa and surplus power P, the amount of charge decreased during a period including at least a part of the discharge periods t2 to t3, that is, the integrated value of the charge amount. It is also possible to detect the occurrence of beat based on this.

(Other embodiments)
In the first embodiment, as shown in FIG. 2, a transistor ignition system that supplies electric energy from the power supply circuit 15 to the ignition coil 14 is adopted. However, the capacitor included in the capacitive discharge ignition circuit (CDI circuit) A CDI ignition system for supplying electric energy from the battery may be employed.

  In addition, this invention is not limited to the content of description of each said embodiment, You may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

It is a lineblock diagram showing an outline of an engine to which a discharge abnormality detecting device concerning a 1st embodiment of the present invention is applied. The lineblock diagram showing the outline of the ignition control system concerning a 1st embodiment. (A) is a figure explaining the phenomenon of creeping discharge, (b) is a figure explaining the phenomenon of arc elongation. It is a time chart explaining the method of detecting the occurrence of a wrinkle in the first embodiment, and is a diagram showing an aspect in a case where no wrinkle has occurred. It is a time chart explaining the method of detecting the occurrence of the sag in the first embodiment, and shows a mode when the sag occurs in the first discharge. The flowchart which shows the procedure of the control which detects a twist in 1st Embodiment. The flowchart which shows the procedure of the control which detects a twist in 1st Embodiment. In the second embodiment of the present invention, a time chart for explaining a technique for detecting the occurrence of a sag. In the third embodiment of the present invention, a time chart for explaining a technique for detecting the occurrence of a wrinkle. The block diagram which shows the outline of an engine to which the discharge abnormality detection apparatus concerning 4th Embodiment of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Spark plug, 14 ... Ignition coil, 14a ... Primary coil, 14b ... Secondary coil, 15 ... Power supply circuit, S14 ... Detection current control means, S20, S22 ... Discharge abnormality determination means.

Claims (9)

Applied to an ignition device comprising: an ignition coil comprising a primary coil and a secondary coil; and an ignition plug for discharging a secondary current flowing in the secondary coil;
Detection power control means for instantaneously flowing surplus power remaining at the end of the discharge among the power stored on the primary coil side prior to the discharge to the primary coil as a detection current at the end of the discharge When,
A discharge abnormality determining means for determining whether or not the discharge is an abnormal discharge based on a value of the detection current;
A discharge abnormality detection device for an internal combustion engine, comprising:   2. The internal combustion engine according to claim 1, wherein the discharge abnormality determination unit determines that the discharge is abnormal when an absolute value of the detection current at a discharge end time is below a preset threshold value. Engine discharge abnormality detection device. The ignition device includes a power supply circuit that stores electric power to be supplied to the primary coil, and supplies the electric power stored in the power supply circuit to the primary coil a plurality of times during one combustion stroke of the internal combustion engine. The multiple discharge to perform the discharge a plurality of times is performed,
3. The discharge abnormality detection of the internal combustion engine according to claim 1, wherein the detection current control unit instantaneously flows the surplus power stored in the power circuit as the detection current to the primary coil. apparatus. Applied to an ignition device comprising: an ignition coil comprising a primary coil and a secondary coil; and an ignition plug for discharging a secondary current flowing in the secondary coil;
Storage detection means for detecting power stored on the primary coil prior to the discharge;
Discharge abnormality determining means for determining whether or not the discharge is an abnormal discharge based on a value detected during the discharge period or at the end of discharge among the detection values by the power storage detecting means;
A discharge abnormality detection device for an internal combustion engine, comprising:   The discharge abnormality determination means determines that the discharge is abnormal when the detection value at the end of the discharge is below a preset threshold among the detection values that decrease with discharge. The discharge abnormality detection device for an internal combustion engine according to claim 4.   When it is determined that there is an abnormality by the discharge abnormality determining means, the number of discharges performed during one combustion stroke is increased from the normal number of times when it is determined that there is no abnormality. The discharge abnormality detection device for an internal combustion engine according to any one of claims 1 to 5.   The discharge abnormality detection device for an internal combustion engine according to claim 6, wherein the number of discharges is increased only when it is determined that there is an abnormality with respect to the last discharge among the regular number of discharges.   The discharge abnormality detecting device for an internal combustion engine according to claim 6 or 7, wherein the discharge related to the increase is executed during an exhaust stroke period.   An ignition control system comprising: the discharge abnormality detection device according to any one of claims 1 to 8; and at least one of the ignition coil and the ignition plug.

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