JP2003269308A - Ignition device of internal-combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition device for an internal-combustion engine as improvement of the conventional publicly known technique including an ion current sensing method and/or a processing circuit in which the ion current sensing wave form is amplified and the obtained signals are turned into rectangular waves and outputted using an integrator circuit, being generally formed with an operational amplifier, wherein, however the offset voltage and/or the bias current of the operational amplifier may cause the hold of the integral output at the time of ignition and the sprung voltage of the integral output at the time of misfire to influence the operational amplifier accuracy to constitute the integrator circuit to result in difficulty in the setting of the circuit. <P>SOLUTION: The integral time constant of the integrator circuit to be formed with the operational amplifier is changed over using an integration period setting signal, and thereby the produced circuit wherein integration is easily performed, and in holding the output and suppressing the sprung voltage are excellent. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine ignition device having an ion current detection function for detecting the combustion state of an internal combustion engine based on the ion current in the combustion chamber.

[0002]

2. Description of the Related Art A method of detecting a combustion state of an internal combustion engine by an ion current is widely known. For example, JP-A-4-
Japanese Patent Publication No. 194367 discloses an example of an ion current detection device. This device charges the capacitor to a constant voltage by the secondary current generated when the primary current of the ignition coil is interrupted, and after spark discharge, it is a closed circuit consisting of this capacitor, the ignition coil secondary winding, the ignition plug and the ion current detection resistor. The current flowing through the circuit can be measured via the ion current detection resistor.

[0003]

In the conventionally widely known technology, a method of detecting an ion current and a circuit for processing have been widely studied. A method is also known in which the ion current detection waveform is amplified by waveform shaping and the signal is output as a rectangular wave using an integrating circuit. It is common to use an operational amplifier as the method of constructing the integrating circuit, but due to the influence of the offset voltage and bias current of the operational amplifier, the integration HIG at the time of ignition is
It is difficult to set the H output and the emergence of the integrated LOW output at the time of misfire.

[0004]

In order to solve the above problems, it is possible to switch the discharge time constant of the integration circuit by using the output of the integration period setting circuit during the integration period and other than the integration period.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the configuration of an embodiment of the present invention. 1 is a battery, 2 is an ignition coil,
The ignition signal output from the ECU causes the igniter 3 to interrupt the current flow in the primary coil 2a of the ignition coil 2 to generate a high voltage in the secondary coil 2b, and the spark plug 4 discharges the high voltage. On the other hand, on the low voltage side of the secondary coil, the ion current detection circuit 6 is composed of a capacitor 6a, a diode 6b, a zener diode 6c and a resistor 6d. The waveform processing circuit 7 processes the ion current waveform detected by the ion current detection circuit into a rectangular wave and outputs it. The present invention is characterized in that an ion current detection circuit 6 and a waveform processing circuit 7 are packaged as one as the ion current processing unit 5 and built in an ignition coil together with the igniter 3 to form an ignition coil ASSY8. The circuit operation of FIG. 1 will be described with reference to FIG.
The igniter 3 is turned on in synchronization with HIGH of the ignition signal from the ECU, and the primary current Ic is supplied to the primary coil 2a of the ignition coil 2. At the start of energization, a positive ON voltage is generated in the A section. When the primary current Ic is cut off, a negative high voltage is generated on the secondary side of the ignition coil, and the spark plug 4 discharges it. At this time, when ignition and combustion occur in the cylinder of the internal combustion engine, the electrodes of the spark plug are ionized. A secondary current flows through the secondary side of the ignition coil due to the discharge of the spark plug, and the capacitor 6a is charged with a voltage clamped by the Zener diode 6c of the ion current detection circuit 6. As described above, when the space between the electrodes of the spark plug is ionized, an ionic current flows through the secondary side of the ignition coil due to the voltage charged in the capacitor 6a. The ionic current is detected as a negative voltage by the resistor 6d. At the time of misfire, the ion current does not flow, so it is not detected. The output of the ion current detection circuit is inverted and shaped by the waveform processing circuit and output as a rectangular wave using the integration circuit. The reason why the integrating circuit is used is to reliably output a signal even with a minute ion waveform. The integrated output is reset for each ignition by the ignition signal so that the combustion state for each ignition can be monitored. Further, since the waveform of the ion current is output by the capacity discharge of ignition before the ion current waveform due to ignition is output, this capacity discharge part is masked, and a more accurate combustion state can be confirmed. Next, the integrating circuit of the present invention will be described with reference to FIGS. 6 and 7. A waveform generated by capacitive discharge and an ion current waveform generated by the flow of ion current are generated at the output of the ion current detector. The ionic current waveform differs in generated voltage and timing depending on the combustion state and operating conditions, and does not occur at misfire.
The output of the ion current detector is input to the signal inversion circuit and amplified and output. An operational amplifier is used as the inverting circuit, for example. The output of the inverting circuit is input to the operational amplifier (comparator) 101, and is compared and output with the reference voltage. At this time, the capacitive discharge section has ON and OFF waveforms corresponding to the vibration frequency during capacitive discharge, and the ion current waveform has a HIGH output during ignition and a LOW output during misfire. SW1 is turned on and off by the output of this comparator 101.
The capacitor 32 is charged when FF is performed and SW1 is turned on, and SW1
Is off, the electric charge charged in the capacitor 32 is discharged through the resistor 31. The discharge waveform and the reference voltage generated by the resistors 33 and 34 are compared by the comparator 102 to determine the mask time. At this time, high-frequency O generated by capacitive discharge
Since the time constant circuit is not completely discharged with the N and OFF waveforms, the discharge voltage of the time constant circuit does not reach the reference voltage during the capacity discharge. As a result, in the circuit of the present invention, a mask is formed for a certain period of time after the capacitive discharge waveform that one wants to mask with certainty, so that a reliable and accurate mask circuit configuration can be achieved.
The output of the comparator 102 is input to the gate of SW2 and operates so that the output of the signal inverting circuit, that is, the ion current output is input to the inverting terminal of the operational amplifier 101 only during the set integration period. The operational amplifier 101 has a capacitor 41 between its output and an inverting terminal, and constitutes an integrating circuit via a resistor between the inverting terminal and GND. An analog SW 42 is arranged in parallel with the capacitor 41, and the analog SW 42 is turned on and off by an ignition signal, and the capacitor 41 is provided for each ignition cycle.
The output of the integrating circuit is reset by discharging the electric charge of. In the present invention, the resistor inserted between the operational amplifier and the GND which constitutes this integrating circuit is divided into two systems, and the comparator 1
Invert the integration period setting signal of 02 output and turn on SW3
By doing so, an integration circuit having a time constant circuit of the resistance value determined by the parallel connection of the resistor 43 and the resistor 44 during the integration period,
During the period other than the integration period, SW3 is turned off to switch to an integration circuit configuration having a time constant circuit including only the resistor 44. At this time, the relationship between the resistors 13 and 44 is the resistance value of the resistor 43 << the resistance 44. In order to raise the integrated output with a small voltage or a short time even at the time of ignition, it is better to have a smaller time constant, but during the period when there is no input for integration (other than the integration period), the integrated output cannot be held if the time constant is small. In addition, at the time of misfire, due to the offset and bias current of the operational amplifier, a source voltage that gradually increases the output of the integrating circuit occurs even though there is no integrating input. To prevent this, it is better to have a large time constant.

FIG. 2 shows a conventional structure. Assuming that the same circuit configuration as that of the present invention is used, conventionally, the ion current detection circuit 6 and the waveform processing circuit 7 are arranged separately from the ignition coil ASSY 11 and the ignition coil in which only the ignition coil 2 and the igniter 3 are integrated. Alternatively, the ignition coil 2, the igniter 3, and the ion current detection circuit 6 are integrated into the ignition coil ASSY 10, and the waveform processing circuit 7 is provided separately. In this case, since a small current flows between the secondary side 2b of the ignition coil 2 to the ion current detection circuit 6 and the ion current detection circuit 6 to the waveform processing circuit, the output is attenuated due to impedance such as wiring wiring, inductance and stray capacitance, and detection is performed. Accuracy deteriorates. By integrating the waveform processing circuit into the ignition coil as in the present invention, the influence of wiring is eliminated, and accurate misfire detection becomes possible. FIG. 4 shows a block diagram of a waveform processing circuit configuration used in the present invention. From the start of the secondary winding of the ignition coil, the ionic current detection section converts the ionic current waveform into a voltage, and the waveform shaping circuit detects the inversion and level to shape the waveform. The output of the waveform shaping circuit integrates the ion current waveform output only at the time of ignition by the integrating circuit. At this time, since all ignition is output due to the capacity discharge waveform at the time of ignition, this capacity discharge portion is masked by the mask circuit. Further, the integrated output is reset every ignition by the ignition signal. FIG. 5 shows a mounting state of the present invention. An ionic current processing unit 5 in which the igniter 3, the ionic current detecting portion, and the waveform processing circuit are integrated is set on the head of the case 21 of the ignition coil, and is integrally sealed with an insulating epoxy resin for the coil winding portion. An ignition signal, a power supply, and GND are input from the outside through the connector terminal 22, and a processing signal is output. Although only one connector terminal 22 is shown because it is a cross-sectional view, each input / output terminal naturally exists. Like the terminal 24, from the ignition coil, there are two connecting from the primary coil to the collector terminal of the igniter 3 and from the secondary coil to the ion current detector in the ion current processing unit. Reference numeral 25 is a center core, 26 is a primary bobbin, 27 is a primary winding, 28 is a secondary bobbin, and 29 is a secondary winding. The high pressure part structure is omitted.

FIG. 8 shows an example of an assembly in which an ion current processing unit and an igniter according to the present invention are built in an ignition coil. An igniter with a heat sink attached is set in the coil case in which the connector terminals are inserted, and the igniter and the ignition signal terminals and GND terminals of the connector terminals are electrically connected by soldering or welding. The collector terminal of the igniter is connected to the end of the primary winding of the ignition coil with a relay terminal, and is connected by soldering or welding in the same manner as the connection terminal. Here, the ignition signal and the GND terminal are terminals shared with the ion current processing unit, and the terminals of the ion current processing unit are also connected by soldering or welding. After connecting the igniter terminals, set the ion current processing unit in the coil case and connect it to each terminal by soldering or welding. Here, the connection of the ignition coil to the winding start of the secondary winding is made by using the relay terminal similarly to the collector terminal of the igniter. Set the igniter and the ion current processing unit in this order in the coil case, connect the terminals by soldering or welding, etc., and fix them in the coil case.
It is integrally fixed by an insulating epoxy resin cast on the ignition coil.

[0008]

According to the present invention, in the misfire detection method using the ion current, the detected information can be output more accurately, the output can be easily processed, and the total cost of the system can be reduced. Become.

[Brief description of drawings]

FIG. 1 is a configuration of an ignition device incorporating an embodiment of the present invention.

FIG. 2 is a configuration example of a conventional ignition device.

FIG. 3 is an operation timing when the present invention is used.

FIG. 4 is a block diagram of a waveform processing circuit according to the present invention.

FIG. 5 is an example of implementation of the invention.

FIG. 6 is a detailed operation timing of the present invention.

FIG. 7 is a specific circuit example of the present invention.

FIG. 8 shows an example of implementation of the present invention.

[Explanation of symbols]

1 ... Battery, 2 ... Ignition coil, 2a ... Primary coil, 2
b ... secondary coil, 3 ... igniter, 4 ... spark plug, 5
... ion current processing unit, 6 ... ion current detection circuit,
6a, 32, 41 ... Capacitor, 6b ... Diode, 6
c ... Zener diode, 6d, 31, 33, 34, 3
5, 36, 43, 44, 45, 47 ... Resistance, 7 ... Waveform processing circuit, 8 ... Ignition coil ASSY, 21 ... Coil case, 22 ... Connector terminal, 23 ... Insulating epoxy resin,
24 ... Connection terminal, 25 ... Center core, 26 ... Primary bobbin, 27 ... Primary winding, 28 ... Secondary bobbin, 29 ... Secondary winding, 42 ... Analog switch, 46 ... Inversion buffer.

Claims (6)

[Claims] 1. A capacitor and a forward diode inserted in series in a secondary current path including a secondary side of an ignition plug and an ignition coil, and the capacitor connected in parallel to the capacitor and charged by the secondary current. Zener diode for limiting the charging voltage of the capacitor to a constant value, and for detecting the ion current generated when ions are generated in the cylinder when the mixture is burned and the charging voltage of the capacitor is applied to the spark plug. , An ion current detection circuit having a current detection resistor connected in parallel to the forward diode and an ion current detected, and when the ion current flows, H
In a misfire detection device including a waveform processing circuit that outputs a rectangular wave of an IGH signal, the waveform processing circuit includes an integration circuit that integrates an ion current output and an integration period setting circuit that integrates the ion current output. A misfire detection device using an ion current, characterized in that the integration time constant of the integration circuit is switched between an integration period and a period other than the integration period according to the output of the circuit. 2. An ion current detection circuit and a waveform processing circuit according to claim 1 are formed in an integrated package, and are provided in an ignition coil together with an ignition device (hereinafter, an igniter) having a switching element for turning on / off the primary current of the ignition coil. A misfire detection device using ion current, which is characterized by being built-in. 3. The ignition coil according to claim 1, wherein four input / output terminals of a power supply terminal, an ignition signal input terminal, a GND terminal and an ion current processing signal output terminal are formed by an integrated connector, and the ion current processing signal is formed. The output of the output terminal is a rectangular wave output. A misfire detection device using ion current. 4. The ion current detection circuit and the waveform processing circuit according to claim 2 are formed in a package integrated with the igniter,
A misfire detection device characterized by being built into an ignition coil. 5. A misfire detection device comprising: detection means for detecting an ion current in a cylinder of an internal combustion engine; and output means for outputting a rectangular wave based on the detected ion current. A misfire detection device comprising: a unit that integrates a current; and a switching unit that switches the integration time constant between a certain period and another period. 6. A misfire detection method for detecting an ionic current in a cylinder of an internal combustion engine, integrating the detected ionic current, and outputting a rectangular wave based on the integrated value. A misfire detection method characterized by switching a constant between a certain period and another period.