JP2014070507A - Ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that, when noises generated from an alternator or the like are superposed on electric power supplied to a primary coil, a power supply voltage having a noise amplitude is induced from the primary coil into a secondary coil to cause the noises to be superposed on an ion current, and when the noises are superposed on the ion current, the noises are erroneously determined as knock in the case of determining the combustion condition of an internal combustion engine from the waveform of the ion current.SOLUTION: Between the low pressure side of the primary coil and a power supply for supplying electric power to the primary coil, a switching element is provided. The switching element is turned on at the same time when an ignition signal is supplied to an ignitor and turned off at the same time when the ignition signal supplied to the ignitor is cut off.

Description

The present invention relates to an ignition device for an internal combustion engine such as an automobile, and more particularly to an ignition device that detects an ionic current generated by combustion of an internal combustion engine.

Conventionally, in an ignition device for an internal combustion engine in which a primary coil and a secondary coil are electromagnetically coupled, an air / fuel mixture supplied into the cylinder of the internal combustion engine is burned by discharge of a spark plug, Some of them have an ion current detection circuit that detects ion current by applying a high voltage to the ignition plug with the ionized molecules in the cylinder, and the combustion state of the internal combustion engine is determined from the detected ion current . As a circuit configuration of such an ignition device, for example, Japanese Patent Application Laid-Open No. 2008-070896 (hereinafter referred to as “Patent Document 1”) is known.

FIG. 6 shows a circuit diagram of the ignition device for an internal combustion engine disclosed in Patent Document 1. 6, in Patent Document 1, an igniter 202 for intermittently connecting a primary current is connected to a primary side of an ignition coil 201 constituted by a step-up transformer, and an ion current detector 204 is connected to a secondary side of the ignition coil 201. Is connected, and a spark plug 203 is connected to the secondary side of the ignition coil 201. The ion current detection unit 204 forms an ion current detection voltage, a zener diode 242 and a capacitor 243, a first diode 244 that supplies a current for charging the ion current detection voltage, and an ion current. It consists of a second diode 245 to be passed, a resistor 246, an amplifier 247 for amplifying the ionic current, and a gain resistor 241 for setting the amplification gain. Further, the output of the ion current detection unit 204 is connected to a comparison unit 205, and the comparison unit 205 includes a combustion determination reference level voltage 251 and a comparator 252. In addition, an ignition coil connected to the engine control unit has been proposed as the output of the comparison unit 205.

JP 2008-070896 A

However, the above-described conventional ignition device for an internal combustion engine has the following problems. That is, in Patent Document 1, the ionic current generated in the cylinder after combustion of the internal combustion engine is detected from the spark plug through the secondary coil, but the noise generated from the alternator or the like is supplied to the primary coil. If it is superimposed on the power supply voltage, a power supply voltage having a noise amplitude in the primary coil is induced in the secondary coil, and noise is superimposed on the ionic current. Specifically, the primary coil and the secondary coil are configured to generate electromagnetic induction, and the power supply voltage is applied to the primary coil regardless of the presence or absence of an ignition signal to the igniter. As a result, when the ionic current passes through the secondary coil, the power supply fluctuation of the primary coil is induced in the secondary coil, and noise is superimposed on the ionic current passing through the secondary coil.

FIG. 5 is a time chart of an ion waveform generated in the cylinder by combustion. In FIG. 5, the X axis represents time, and the Y axis represents the magnitude of the ion waveform. The ion waveform generated in the cylinder is shown by a solid line. As shown by the solid line in FIG. 5, the ion waveform rises to the peak value and then decreases. However, when the alternator is driven, it is shown that the alternator noise is superimposed on the ion waveform. Since the signal and the alternator signal are similar, it is difficult to accurately determine the knock signal and the alternator signal. Thus, when noise is superimposed on the ion current, the noise is erroneously determined to be knock when determining the combustion state of the internal combustion engine from the waveform of the ion current. If it is originally determined that the engine is knocked, the ignition signal to the igniter or the fuel injection signal to the injector is adjusted to suppress the knock generated in the internal combustion engine. When such control is performed, the combustion efficiency and fuel consumption of the internal combustion engine deteriorate.

The present invention has been made in view of the above problems, and prevents noise generated from an alternator or the like from being superimposed on the power supplied to the primary coil to adversely affect the ion current waveform, and the combustion of the internal combustion engine from the ion current waveform. It is an object of the present invention to provide an ignition device for an internal combustion engine that does not erroneously determine that a noise component is knocked when determining the state.

In order to solve the above problems, the present invention is configured as follows. That is, according to the first aspect of the present invention, a coil portion in which a primary coil and a secondary coil are electromagnetically coupled, an igniter that switches ON / OFF of energization to the primary coil, and a high frequency from the secondary coil. In an ignition device for an internal combustion engine, comprising: an ignition plug that discharges a voltage; an ECU that supplies an ignition signal to the igniter; and an ion current detection circuit that detects an ion current; An ignition for an internal combustion engine, wherein a switching element is provided between a power source for supplying power to the secondary coil, and the switching element is turned off at least during a period in which an ion current flows through the secondary coil. A device.

In the above configuration, the switching element may be turned on at the same time as an ignition signal is supplied to the igniter and turned off at the same time as the ignition signal supplied to the igniter is shut off. The switching element may be configured to be turned on and off by a signal from the ECU, and the switching element may be configured from a transistor, a thyristor, or a relay. Further, the ECU may determine the combustion state of the internal combustion engine from the ion current detected by the ion current detection circuit.

As described above, a coil portion in which the primary coil and the secondary coil are electromagnetically coupled, an igniter that switches ON / OFF of energization to the primary coil, an ignition plug that discharges a high voltage from the secondary coil, In an ignition device for an internal combustion engine having an ECU that supplies an ignition signal to an igniter and an ion current detection circuit that detects an ion current generated in an ignition plug, power is supplied to the low voltage side of the primary coil and the primary coil A switching element is provided between the power source and the switching element. The switching element is turned on at the same time as the ignition signal is supplied to the igniter and is turned off at the same time as the ignition signal supplied to the igniter is shut off. Thus, while the ignition signal to the igniter is cut off, the power supply voltage to the primary coil is also cut off, and when the ionic current passes through the secondary coil, the primary coil No power fluctuation occurs and noise can be prevented from being superimposed on the ionic current caused by induction to the secondary coil. When determining the combustion state of the internal combustion engine, the noise component is erroneously determined as knocking. An ignition device for an internal combustion engine that does not occur can be realized.

It is a figure which shows the circuit diagram of the ignition device for internal combustion engines which is an Example of this invention. It is a figure which shows the operation | movement at the time of charge to the primary coil of an ignition device. It is a figure which shows the operation | movement at the time of the discharge from the secondary coil of an ignition device. It is a figure which shows the operation | movement at the time of the ion current detection of an ignition device. It is a time chart of the ion waveform which occurs in a cylinder by combustion of an internal-combustion engine. It is a figure which shows the circuit diagram of the ignition device for internal combustion engines made into patent document 1. FIG.

Hereinafter, an example showing the embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing a circuit diagram of an ignition device for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a diagram showing an operation during charging of a primary coil of the ignition device, and FIG. FIG. 3 is a diagram showing the operation at the time of discharging from the battery, and FIG.

In FIG. 1, an ignition device 100 for an internal combustion engine includes a coil section, an igniter 60, and an ion current detection circuit 90. The fire coil portion is configured by electromagnetically coupling a primary coil 10 wound with a primary winding, a secondary coil 20 wound with a secondary winding, and an iron core 30 made of a silicon steel plate. Yes. The igniter 60 is composed of an IGBT (insulated gate bipolar transistor). Further, the ion current detection circuit 90 includes a Zener diode 92a, two diodes 92b and 92c, a capacitor 94, an operational amplifier 96, and two resistors 98a and 98b.

The high-voltage side of the secondary coil 20 is connected to the center electrode of a spark plug 50 that discharges into the cylinder of the internal combustion engine and detects an ionic current generated between the electrodes due to combustion of the internal combustion engine. The side electrode of the plug 50 is connected to a ground provided on the vehicle body side. Further, the low voltage side of the secondary coil 20 is connected to the ion current detection circuit 90 and is connected to the cathode terminal of the Zener diode 92a.

The anode terminal of the Zener diode 92a is connected to the anode terminal of the diode 92b. Further, the cathode terminal of the diode 92b is connected to the ground.

The capacitor 94 is connected in parallel with the Zener diode 92a. Further, the positive terminal of the capacitor 94 is connected to the cathode terminal of the Zener diode 92b, and the negative terminal is connected to the anode terminal of the Zener diode 92a.

The resistor 98a is connected to the negative terminal of the capacitor 94, and the opposite side of the resistor 98a connected to the capacitor 94 is connected to the inverting input terminal of the operational amplifier 96. Further, the connection portion between the inverting input terminal of the operational amplifier 96 and the resistor 98a is connected to the cathode terminal of the diode 92c, and the anode terminal of the diode 92c is connected to the ground.

The resistor 98b is connected in parallel with the inverting input terminal and the output terminal of the operational amplifier 96. Further, the positive power supply terminal of the operational amplifier 96 is connected to a power supply to receive power, and the non-inverting input terminal and the negative power supply terminal of the operational amplifier 96 are connected to the ground.

The Zener diode 92a is a Zener diode having a breakdown voltage of 270V, and the voltage charged in the capacitor 94 is limited to 270V by the breakdown voltage value of the Zener diode 92a.

Further, a switching element 70 made of a transistor is provided between the primary coil 10 and a power source 40 made of an automobile battery. The positive side of the power source 40 is connected to the collector terminal of the switching element 70, and the emitter terminal of the switching element 70 is connected to the low voltage side of the primary coil 10. Further, the high voltage side of the primary coil is connected to the collector terminal of the igniter 60.

The emitter terminal of the igniter 60 is connected to the ground. Further, the gate terminal of the igniter 60 and the base terminal of the switching element 70 are connected to an engine ECU 80 of the automobile, and the engine ECU 80 supplies an ignition signal to the gate terminal of the igniter 60 and An energization signal is supplied to the base terminal.

Next, the operation at the time of charging the primary coil of the ignition device will be described with reference to FIG.

In FIG. 2, when an ignition signal is input from the engine ECU 80 to the gate terminal of the igniter 60 and an energization signal is input to the base terminal of the switching element 70, the gate emitter of the igniter 60 A gate current flows between them as indicated by a dashed line arrow. Then, the collector-emitter of the igniter 60 and the collector-emitter of the switching element 70 are energized.

As a result, a primary current I ₁ flows through the path of the power source 40 → the switching element 70 → the primary coil 10 → the igniter 60 as indicated by a one-dot chain arrow in FIG. The engine ECU 80 simultaneously turns on / off signals from the engine ECU 80 to the igniter 60 and the switching element 70. When the igniter 60 is on, the switching element 70 is also turned on, and the igniter 60 is turned on. On the other hand, when it is OFF, the switching element 70 is also OFF.

Next, the operation at the time of discharging from the secondary coil of the ignition device will be described with reference to FIG.

In FIG. 3, when the ignition signal from the ECU 80 to the gate terminal of the igniter 60 is cut off and the energization signal to the base terminal of the switching element 70 is cut off, the primary current flowing in the primary coil 10 is blocked. I ₁ generates a back electromotive force in the secondary coil 20 by electromagnetic induction. As a result, as shown in dashed line in FIG. 3 arrow, the spark plug 50 → secondary current I ₂ flows through a path of the secondary coil 20 → the Zener diode 92a → the diode 92b. The capacitor 94 is charged corresponding to the breakdown voltage of the Zener diode 92a.

Next, the operation of the ignition device when detecting the ion current will be described with reference to FIG.

In FIG. 4, when the discharge from the spark plug 50 ends, the voltage across the capacitor 94 charged during the discharge from the secondary coil in FIG. As shown, an ion current I _ion flows through the path of the resistor 98b → the resistor 98a → the capacitor 94 → the secondary coil 20 → the spark plug 50. As a result, a detection signal corresponding to the ion current _Iion is output from the operational amplifier 96. Further, the engine ECU 80 determines the combustion state of the internal combustion engine based on the detection signal output from the operational amplifier 96.

With the above configuration, the switching element 70 is provided between the primary coil 10 and the power source 40. The collector terminal of the switching element 70 is connected to the positive side of the power source 40, and the emitter terminal of the switching element 70 is connected to the low voltage side of the primary coil 10. The base terminal of the switching element 70 is connected to the engine ECU 80 and supplies an energization signal to the switching element 70. Further, ON / OFF of the signal from the engine ECU 80 to the igniter 60 and the switching element 70 is performed at the same time. When the igniter 60 is ON, the switching element 70 is also turned ON, and the igniter 60 On the other hand, when it is OFF, the switching element 70 is also OFF. As a result, while the ignition signal to the igniter 60 is cut off, the power supply voltage to the primary coil 10 is also cut off, and when the ion current I _ion passes through the secondary coil 20, the power supply of the primary coil 10 is cut off. It is possible to prevent noise from being superimposed on the ionic current I _ion caused by the induction to the secondary coil 20 without fluctuation.

Further, since the noise is not superimposed on the ion current _Iion , the engine ECU 80 erroneously determines that the noise is knocked when determining the combustion state of the internal combustion engine based on the detection signal from the ion current _Iion. Therefore, the ignition signal to the igniter 60 or the fuel injection signal to the injector is adjusted and the knock generated in the internal combustion engine is suppressed, and the internal combustion engine is suppressed. It is possible to prevent the combustion efficiency and fuel consumption of the engine from deteriorating.

As a modification of the first embodiment, the ion current detection circuit 90 includes a Zener diode 92a, the two diodes 92b and 92c, the capacitor 94, the operational amplifier 96, and the two resistors 98a and 98b. However, as long as the circuit configuration can detect the ion current I _ion , it may be changed to an arbitrary circuit configuration depending on design circumstances. Further, the switching element 70 is provided between the primary coil 10 and the power source 40. The switching element 70 is a transistor, but if it is an electrical switch, other switching elements such as a thyristor and a relay are used. May be. Further, although the switching element 70 is configured to be supplied with an energization signal from the engine ECU 80, the switch may be configured to be opened and closed by a signal from another CPU.

The switching element 70 may be configured such that the energization signal from the engine ECU 80 is turned off during a period when the ion current I _ion is detected, that is, during a period when the ion current I _ion flows through the secondary coil 20 at least. For example, the supply of energization signals for other periods may be arbitrarily changed according to design circumstances.

10: 1 primary coil
20: Secondary coil
30: Iron core
40: Power supply
50: Spark plug
60: Igniter (IGBT)
70: Switching element (transistor)
80: Engine ECU
90: Ion current detection circuit
92a: Zener diode
92b, 92c: Diode
94: Capacitor
96: Operational amplifier
98a, 98b: Resistance
100: Ignition device

Claims (5)

A coil portion in which the primary coil 10 and the secondary coil 20 are electromagnetically coupled, an igniter 60 for switching ON / OFF of energization to the primary coil 10, and an ignition for discharging a high voltage from the secondary coil 20 In an ignition device 100 for an internal combustion engine comprising a plug 50, an ECU 80 that supplies an ignition signal to the igniter 60, and an ion current detection circuit 90 that detects an ion current,
A switching element 70 is provided between the low voltage side of the primary coil 10 and a power supply 40 that supplies power to the primary coil 10.
The ignition device 100 for an internal combustion engine, wherein the switching element 70 is turned off at least during a period in which an ionic current flows through the secondary coil 20. 2. The switching element 70 is turned on at the same time as an ignition signal is supplied to the igniter 60, and is turned off at the same time as the ignition signal supplied to the igniter 60 is cut off. An ignition device 100 for an internal combustion engine according to claim 1. The ignition device for an internal combustion engine according to claim 1 or 2, wherein the switching element (70) can be switched ON / OFF by a signal from the ECU (80). The ignition device for an internal combustion engine according to any one of claims 1 to 3, wherein the switching element (70) comprises a transistor, a thyristor, or a relay. The ignition device for an internal combustion engine according to any one of claims 1 to 4, wherein the ECU 80 determines the combustion state of the internal combustion engine from the ion current detected by the ion current detection circuit 90.

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