JP2007303373A - Control device for internal combustion engine - Google Patents

Abstract

To provide a control device for an internal combustion engine capable of preventing erroneous detection when detecting disconnection of an ignition coil and improving the reliability of failure detection.
A control device (20) for an internal combustion engine (1) for detecting disconnection of an ignition coil (9) when monitoring an ion current generated in the internal combustion engine (1) as combustion is caused by ignition of a spark plug (7). When a disconnection is detected and a misfire is detected based on the amount of rotational fluctuation of the crankshaft of the internal combustion engine 1, a lamp for notifying the user of a failure of the ignition coil 9 is turned on.
[Selection] Figure 3

Description

  The present invention relates to a control device for an internal combustion engine that detects a failure of an ignition coil of the internal combustion engine.

  2. Description of the Related Art Conventionally, an internal combustion engine mounted on an automobile or the like is provided with an ion current detection circuit 10 that detects an ion current generated in the internal combustion engine 1 due to combustion by ignition of a spark plug 7, as shown in FIG. There is something. The control device 40 is configured to detect, for example, misfire, knocking, or disconnection of the ignition coil 9 by monitoring the ion current detected by the ion current detection circuit 10.

By the way, in the internal combustion engine 1, when the ignition signal for igniting the spark plug 7 is turned ON, a primary current starts to flow from the power source 8 to the primary coil 9a of the ignition coil 9, and when the ignition signal is turned OFF, A secondary current starts to flow through the secondary coil 9 b, and an ionic current is generated from the internal combustion engine 1 along with combustion by ignition of the spark plug 7. When the ignition signal is turned ON, the secondary current due to electromagnetic induction flows for a short time when the ignition coil 9 is normal, and the ionic current does not flow when the ignition coil 9 is disconnected. The disconnection of the ignition coil 9 is detected by monitoring the ionic current at the time (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-13619 (20th to 24th paragraphs, FIG. 2)

  However, in the conventional control device for an internal combustion engine, when the voltage of the power supply 8 energized to the primary coil 9a changes, the influence may reach the ionic current via the ignition coil 9, so that the ignition coil 9 is disconnected. The problem of false detection remained. For example, in a conventional control device for an internal combustion engine, even when the ignition coil 9 is disconnected, if the voltage value of the power supply 8 fluctuates and rises, an ionic current may flow. Even if the ignition coil is not disconnected, the ionic current may not be detected if the voltage value of the power supply 8 fluctuates and falls, so the ignition coil 9 may be determined to be disconnected. is there.

  The present invention has been made to solve the conventional problems, and provides a control device for an internal combustion engine that can prevent erroneous detection when detecting disconnection of an ignition coil and improve the reliability of failure detection. The purpose is to do.

  The control device for an internal combustion engine of the present invention is a control device for an internal combustion engine that detects disconnection of an ignition coil when monitoring an ionic current generated in the internal combustion engine with combustion by ignition of an ignition plug, the ignition coil When a disconnection is detected, and when a misfire is detected, a failure of the ignition coil is notified.

  With this configuration, in the case of detecting ignition coil disconnection and in the case of misfire detection, the detection of ignition coil disconnection is notified by notifying the user of the ignition coil disconnection. Can be prevented and the reliability of notification of failure detection can be improved.

  Also, the control device for an internal combustion engine of the present invention has a configuration in which the failure notification is withdrawn when the number of times that the disconnection of the ignition coil has not been detected reaches the first predetermined number after the failure notification. is doing.

  With this configuration, after the failure notification, when the number of times that the disconnection of the ignition coil has not been detected reaches the first predetermined number, the failure notification is withdrawn, that is, it is repeatedly determined that the ignition coil is normal. Then, since the failure notification is withdrawn, the reliability indicating the normality of the ignition coil can be increased.

  Further, the control device for an internal combustion engine according to the present invention stores the state of the ignition coil as a failure when the failure notification is performed, and the number of times the disconnection of the ignition coil is not detected after the failure notification. When the second predetermined number is reached, the state of the ignition coil is stored as a non-failure state.

  With this configuration, when the number of times the disconnection of the ignition coil is not detected reaches the second predetermined number, the state of the ignition coil is stored as a non-failure state, that is, the ignition coil is repeatedly normal. Since the state of the ignition coil is not a failure after the determination, the reliability indicating the normality of the ignition coil can be increased.

  In the control device for an internal combustion engine according to the present invention, the second predetermined number is configured to be larger than the first predetermined number.

  With this configuration, when the number of times that the ignition coil disconnection has not been detected after the failure notification reaches the first predetermined number and the failure notification is withdrawn, the second predetermined number is greater than the first predetermined number. Therefore, even if the notification of failure of the ignition coil is withdrawn, the state of the ignition coil may be stored as a failure. Therefore, when the state of the ignition coil is read by the scan tool, it can be known that the ignition coil has been disconnected before, and it can be determined whether the ignition coil needs to be repaired or replaced.

  As described above, the present invention provides a control device for an internal combustion engine that can prevent erroneous detection when detecting disconnection of an ignition coil and improve the reliability of notification of failure detection.

  Hereinafter, an internal combustion engine and a control device thereof according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of an internal combustion engine, an ion current detection device, and a control device according to an embodiment of the present invention. The internal combustion engine 1, the crank angle sensor 6 that detects the rotation of the crankshaft of the internal combustion engine 1, the ion current detection device 10 that detects the ionic current, and the control device 20 such as an ECU (Electronic Control Unit) shown in FIG. It is installed in automobiles.

  The control device 20 is connected to the crank angle sensor 6 and the ionic current detection device 10. One end of the primary coil 9 a of the ignition coil 9 installed in the internal combustion engine 1 is connected to the power source 8. The other end of the primary coil 9a is connected to, for example, a power transistor for ignition control (not shown).

  One end of the secondary coil 9 b of the ignition coil 9 is connected to the spark plug 7, and the other end of the secondary coil 9 b is connected to the ground side via the two Zener diodes 11 and 12 in the ion current detector 10. ing. The ion current detection device 10 includes two Zener diodes 11 and 12, a capacitor 13, resistors 14 and 16, and an amplifier circuit 15.

  The ion current detection device 10 is adapted to detect an ion current generated in the internal combustion engine 1 due to combustion by ignition of a spark plug 7 installed in the internal combustion engine 1. Here, an outline of an operation when the ion current detection device 10 detects an ion current will be described below.

  While the internal combustion engine 1 is in operation, the ignition signal is turned on at an appropriate timing. While the ignition signal is on, the primary current flows from the power source 8 to the primary coil 9a, and then the ignition signal is turned off and the primary signal is turned off. Since the primary current flowing through the coil 9a is interrupted and a high voltage is electromagnetically induced in the secondary coil 9b, a spark discharge is generated between the electrodes of the spark plug 7 by this high voltage. When a spark discharge occurs between the electrodes of the spark plug 7, a current flows through the capacitor 13, and the capacitor 13 is charged to a voltage that matches the Zener voltage of the Zener diode 11.

  When the air-fuel mixture in the combustion chamber of the internal combustion engine is ignited and burned by the spark discharge in the spark plug 7, the air-fuel mixture is ionized and the two electrodes of the spark plug 7 conduct. At this time, since a voltage is applied between both electrodes of the spark plug 7 due to the charging voltage of the capacitor 13, ions generated when the air-fuel mixture burns are converted into an ion current from the capacitor 13 to the secondary of the ignition coil 9. The current flows through the coil 9b, the spark plug 7, and the amplifier circuit 15, is amplified by the amplifier circuit 15, and flows to the control device 20.

  The control device 20 includes various electronic circuits such as a CPU, a memory, an input signal circuit, and an output signal circuit. Further, the control device 20 monitors the ion current detected by the ion current detection circuit 10 to detect, for example, misfire, knocking of the internal combustion engine 1, or disconnection of the ignition coil 9.

  When the disconnection of the ignition coil 9 is detected, for example, the control device 20 turns on a MIL (Malfunction Indicator Lamp) for notifying the user of the failure of the ignition coil 9 and relates to the failure of the ignition coil 9. A predetermined DTC is stored in the memory.

  For example, the control device 20 detects a disconnection of the ignition coil 9 when monitoring a signal due to an ion current (hereinafter referred to as an ion current signal). Here, FIG. 2 shows a time chart showing transition states of the ignition signal and the ion current signal. FIG. 2A shows the transition state of the ignition signal, and FIG. 2B shows the transition state of the ion current signal.

  As shown in FIG. 2 (a), the ignition signal for the ignition coil 9 is turned on at time t1, where the primary current starts to flow through the primary coil 9a of the ignition coil 9 and the ignition timing of the ignition coil 9 is reached. Turns off at t3.

  As shown in FIG. 2B, when the ignition signal is turned on (time t1), a secondary current due to electromagnetic induction flows for a short time (time t1 to time t2). Further, when the ignition signal is turned off (time t3), the secondary current starts to flow through the secondary coil 9b and is ignited by the ignition plug 7, and then generated in the internal combustion engine 1 with combustion by ignition of the ignition plug 7. The ion current signal to be superimposed is superimposed.

  When the primary coil 9a or the secondary coil 9b of the ignition coil 9 is disconnected, the secondary current at the time T1 from the time t1 to the time t2 is not detected or is detected only in a very short time. Therefore, when the detection time T1 during which the secondary current has been detected is less than a predetermined value, the control device 20 detects the disconnection of the ignition coil 9. The predetermined value is, for example, about 50 μsec.

  Further, the control device 20 receives a signal (hereinafter referred to as a crank angle signal) output from the crank angle sensor 6, and based on the received crank angle signal, rotates the crankshaft, that is, the engine speed NE. Misfire is detected by the amount of fluctuation.

  For example, when the difference ΔNE between the crank angular speed in the explosion stroke that is the target of misfire determination and the crank angular speed measured at a predetermined time before a predetermined period exceeds a predetermined misfire threshold, It is determined that a misfire has occurred.

  An example of the operation of the control apparatus for an internal combustion engine according to the embodiment of the present invention configured as described above will be described below with reference to the drawings. FIG. 3 is a flowchart showing an example of the operation of the control device for the internal combustion engine according to the embodiment of the present invention. This flowchart represents a flow of processing that is repeatedly executed at an appropriate timing such as every predetermined time.

  First, in order to detect disconnection of the ignition coil 9, the control device 20 detects the secondary current when monitoring the ion current signal as shown in FIG. 2, and the detection time T1 is less than a predetermined value. It is determined whether or not (S1). When the detection time T1 is less than the predetermined value, the control device 20 assumes that the ignition coil 9 is disconnected, and further determines whether or not the crank angular speed difference ΔNE exceeds a predetermined misfire threshold. (S2).

  When the crank angle speed difference ΔNE exceeds a predetermined misfire threshold, the control device 20 turns on the MIL for notifying the user of the failure of the ignition coil 9 assuming that the ignition coil 9 is disconnected, The ignition coil state is stored as a failure (S3). In the embodiment of the present invention, the control device 20 stores a predetermined DTC related to the failure of the ignition coil 9 in a memory.

  Next, the control device 20 resets a counter, which is the number of times that the ignition coil 9 is detected to be normal, to 0 (S4), and ends the operation assuming that the ignition coil 9 is disconnected.

  On the other hand, if the detection time T1 is not less than the predetermined value in step S1, the control device 20 determines whether or not the ignition coil state is a failure (S5). If the ignition coil state is not a failure, the control device 20 The operation is terminated as if normal.

  If the detection time T1 is not less than the predetermined value in step S1, and if the ignition coil state is faulty in step S5, the control device 20 sets 1 to the counter that is the number of times that the ignition coil 9 has been detected as normal. Increment (S6).

  Next, the control device 20 determines whether or not the incremented counter has reached the predetermined number X2 (S7), and when it reaches the predetermined number X2, deletes the DTC and restores the state of the ignition coil 9 to the original state. The initial state is stored (S8).

  If the counter has not reached the predetermined number X2, the control device 20 determines whether or not the counter has reached the predetermined number X1 (S9). If the counter has reached the predetermined number X1, the controller 20 determines that the ignition coil 9 has failed. The MIL for notifying is turned off (S10). Note that the control device 20 may turn off the MIL only when the MIL is turned on.

  The predetermined number X2 is larger than the predetermined number X1, for example, the predetermined number X2 is about 40 and the predetermined number X1 is about 3. Therefore, even if the MIL is turned off, DTC is stored. It may remain. In this case, it is understood that the disconnection of the ignition coil 9 has been detected when the reading device reads the DTC.

  As described above, the control apparatus for an internal combustion engine according to the embodiment of the present invention detects the disconnection of the ignition coil 9 and detects the misfire based on the crankshaft rotation fluctuation amount. By turning on the MIL for notifying the user of the failure, it is possible to prevent erroneous detection when detecting the disconnection of the ignition coil 9 and to improve the reliability of the notification of failure detection.

  In addition, after turning on the MIL, it is repeatedly determined that the ignition coil is normal, and then the MIL is turned off or the DTC is deleted. Therefore, the reliability indicating the normality of the ignition coil 9 can be increased.

  In the embodiment of the present invention, it has been described that misfire is detected based on the rotational fluctuation amount of the crankshaft of the internal combustion engine. However, the misfire is detected not limited to the rotational fluctuation amount of the crankshaft of the internal combustion engine. Any means may be used as long as it is a means. Further, although the description has been made so that the MIL is turned on or off as a means for igniting the ignition coil failure or withdrawing the notification, the notification is not limited to the lighting or extinguishing of the lamp such as the MIL. Alternatively, any means may be used as long as the notice can be withdrawn.

Configuration diagram of an internal combustion engine, an ion current detection device, and a control device according to an embodiment of the present invention The figure which shows the time chart showing the transition state of the ignition signal and the ion current signal The flowchart which shows an example of operation | movement of the control apparatus of the internal combustion engine which concerns on embodiment of this invention. Configuration diagram of conventional internal combustion engine, ion current detection device, and control device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 6 Crank angle sensor 7 Spark plug 8 Power supply 9 Ignition coil 9a Primary coil 9b Secondary coil 10 Ion current detection device 11, 12 Zener diode 13 Capacitor 14, 16 Resistance 15 Amplifier circuit 20, 40 ECU

Claims (6)

A control device for an internal combustion engine that detects disconnection of an ignition coil when monitoring an ion current generated in the internal combustion engine with combustion by ignition of a spark plug,
A control device for an internal combustion engine, wherein when a disconnection of the ignition coil is detected and a misfire is detected, a failure of the ignition coil is notified. 2. The control of the internal combustion engine according to claim 1, wherein after the notification of the failure, the notification of the failure is withdrawn when the number of times that the disconnection of the ignition coil is not detected reaches a first predetermined number. apparatus. When the notification of the failure is performed, the state of the ignition coil is stored as a failure, and after the notification of the failure, the number of times that the disconnection of the ignition coil is not detected reaches a second predetermined number, The control device for an internal combustion engine according to claim 1 or 2, wherein the state of the ignition coil is stored as a state where there is no failure. The control device for an internal combustion engine according to claim 3, wherein the second predetermined number is larger than the first predetermined number. The control apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the misfire is detected based on a rotational fluctuation amount of a crankshaft of the internal combustion engine. 6. The internal combustion engine according to claim 2, wherein the failure notification is performed by turning on a lamp for notifying a user, and the failure notification is withdrawn by turning off the lamp. Control device.

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