JP2007009890A - Ignitor provided with ion current detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion current detection device, capable of securing determination time from around 15 degrees of ATDC, and securing the maximum ignition energy over a wide speed range to a system for controlling the ignition timing and the air-fuel ratio by finely collecting ion current variation information from starting to reaching a high speed range. <P>SOLUTION: In the middle of a primary winding provided with a power source on one terminal of an ignition coil, at least one tap terminal is provided, and a switching element is provided on each of the tap terminal of the primary winding and the other terminal. An ignition plug and an ion current detecting device are provided on the secondary winding of the ignition coil, and action of the switching element is switched in accordance with the speed of an internal combustion engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high output energy internal combustion engine ignition device required for a direct fuel injection internal combustion engine and the like effective for exhaust gas countermeasures and fuel efficiency improvement, in particular, means for detecting an ionic current generated in a cylinder according to a combustion state. The present invention relates to an ignition device provided.

  2. Description of the Related Art Conventionally, an internal combustion engine ignition device is required to have a high energy ignition device in order to be compatible with recent high-compression lean combustion for measures against exhaust gas and fuel efficiency. On the other hand, the combustion state detection device for an internal combustion engine detects a continuous misfiring and detects a change in the rotational speed of the internal combustion engine at the time of misfiring with a sensor in order to indicate a warning to the operator of the internal combustion engine. A misfire detection function has been proposed.

  In addition, the combustion state detection device for an internal combustion engine using an ionic current exhibits excellent misfire detection performance even in a multi-cylinder engine in which misfire detection accuracy is reduced by the rotational fluctuation method, and can detect misfire for each cylinder at the same time as the ignition timing and Various proposals have been made in the past for knock control and the like, but since a general high energy ignition device generally has a long discharge duration, the ion detection time is limited, which is incompatible.

  The waveform of the output discharge current of a conventional current interruption type internal combustion engine ignition device is substantially triangular, and the form of the general-purpose ignition coil can be set by the values of the inductance of the secondary wire ring and the leakage capacitance. That is, the maximum value of the discharge current is large when the number of turns of the secondary wire is small, but the discharge duration is shortened, and the opposite discharge current is obtained when the number of turns is large. In a direct-injection internal combustion engine or the like in which strong eddy current combustion is performed, the current in the latter half of the triangular wave hardly contributes to the ignition of fuel due to the increased turbulence.

  In addition, in a conventional current interruption type internal combustion engine ignition device with a combustion state detection device based on ion current, a part of the ignition energy at the beginning of discharge is temporarily accumulated in a capacitor, It is used as a detection power source.

  The voltage of the ion detection power source is generally used in a range of about 70V to 300V, and the higher the voltage, the higher the SN ratio of ion detection and the degree of design freedom. The energy of the ignition device necessary for the discharge is lost.

  In recent exhaust gas countermeasures, a system that finely collects information on changes in ion current from the start of the internal combustion engine to the high engine speed range and controls the ignition timing and air-fuel ratio is desired. It has been confirmed that about 15 degrees after the top dead center is an important time zone for ionic current discrimination in order to detect the combustion deterioration state and knocking by electric current. Then, in order to deal with a direct fuel injection internal combustion engine with lean fuel, etc., a high output energy ignition device is desired as a problem before control by ion current, but a general purpose high output energy ignition device was used. In such a case, there has been a problem that the spark discharge time becomes long and sufficient time required for ion current detection cannot be taken.

  As described above, in the current interruption type ignition device, the discharge current can be set somewhat depending on the number of turns of the secondary coil of the ignition coil, but in all cases, the discharge current is a triangular wave with a relatively large discharge current. In a direct-injection internal combustion engine or the like in which combustion with strong eddy current is performed, the current in the latter half of the triangular wave is greatly disturbed, so that control of discharge current and discharge time is limited.

    In order to solve the above problems, the present invention is configured as follows. In claim 1, at least one tap terminal is provided in the middle of the primary wire ring provided with a power source at one terminal of the ignition coil, and a switching element is provided on each of the tap terminal and the other terminal of the primary wire ring, Ignition equipped with an ion current detecting device, characterized in that the secondary coil wheel of the ignition coil is provided with an ignition plug and an ion current detecting device, and the operation of the switching element is switched according to the rotational speed of the internal combustion engine. By using the device, the degree of freedom in designing the output energy of the ignition coil adapted to the engine speed is greatly improved, and the problem is solved.

  In the ignition device provided with the ion current detection device according to claim 2 of the present invention, when the rotational speed of the internal combustion engine is low, the switching element provided at the other terminal which is the end of the primary wire wheel operates and the rotational speed is high. In some cases, the switching element provided in the tap terminal of the primary wire ring is configured to operate so as to meet the general-purpose ignition coil design specification.

  In the ignition device including the ion current detection device according to claim 3 of the present invention, the discharge duration of the ignition coil is 2.5 ms or more when the internal combustion engine is idling speed, and is 1.0 ms or less when the engine speed is high. Thus, the ion detection time corresponding to each rotation speed of the internal combustion engine is secured, and the ignition energy at the rotation speed is secured to the maximum.

  Similarly, in the ignition device provided with the ion current detection device according to claim 4 of the present invention, the detection start time of the ion current detection circuit is set to about 15 degrees ATDC (after compression top dead center) in at least the internal combustion engine practical rotation region. Thus, the ion detection time corresponding to each rotation speed of the internal combustion engine is ensured to ensure the maximum ignition energy at the rotation speed.

  In the ignition device equipped with the ion current detection device according to claim 3 of the present invention, the control range of the ignition energy and the discharge duration is expanded by making the magnetic circuit of the ignition coil into a closed core magnetic core structure.

  According to the present invention, an ignition device with high output energy is desired in order to cope with a fuel direct injection internal combustion engine with a lean air-fuel mixture, which has been required in recent years for fuel efficiency and exhaust gas countermeasures. By providing a tap terminal in the middle of the primary wire ring of the energy ignition coil and adding a switching element, detailed information on changes in ion current from the start of the internal combustion engine to the high rotation range is collected, and the ignition timing and For the system that controls the air-fuel ratio, while ensuring the discrimination time from about 15 degrees ATDC necessary to detect the combustion deterioration state and knocking due to the ion current, it covers a wide range from low speed to high speed. Thus, it is possible to obtain an ignition device including an ion current detection device that can secure the maximum ignition energy.

  FIG. 1 shows an embodiment of the present invention described in all the claims, and the graph of FIG. 2 is for explaining the operation of the embodiment. The upper part of the graph of FIG. FIG. 5 is a diagram showing the discharge duration on the vertical axis, and the lower part of the graph shows the engine speed on the horizontal axis and the ignition output voltage on the vertical axis. Note that the internal combustion engine is normally used in a multi-cylinder, but for the convenience of explanation, an example with one cylinder is used.

  In FIG. 1, the power source 1 is connected to one terminal 101 of the primary wire ring 100 of the ignition coil 2, the other terminal of the primary wire ring 100 is connected to the first switching element 3, and the primary wire ring. A tap terminal 103 is provided in the middle of winding 100, the second switching element 4 is connected to the tap terminal, and the control terminals of the first and second switching elements are connected to the drive circuit 5. Yes. Further, the high voltage side terminal 201 of the secondary wire ring 200 of the ignition coil 2 is connected to the spark plug 6, and the low voltage side terminal 202 of the secondary wire ring 200 is connected to the constant voltage diode 7 and the capacitor 8 and diode 9. Is connected to the input terminal of the ion current detection device 11 through a series circuit of the register 10 that detects the ion current shunted by the protective diode 12. The protection diode 12 is connected to the input terminal. The drive circuit 5 and the ion current detection device 11 are connected to the internal combustion engine control ECU 13.

  An ON signal is sent to the switching element 3 before the energizing current of the primary coil 100 of the ignition coil 2 becomes about 8 A at the ignition timing from the drive circuit 5 according to the ignition command from the ECU 13 during the idling rotation from the start of the internal combustion engine. When the off signal is transmitted to the switching element 3 at the ignition timing at the same time, the induced energy accumulated in the ignition coil 2 by the current is added to the low voltage side terminal 202 of the secondary wire ring 200 and the high voltage side terminal 201 is transmitted. Discharging while generating a negative voltage of about 40 KV.

  Due to the high voltage, the discharge current that has started to discharge into the spark plug 6 ignites the fuel, and at the same time, charges of a voltage determined by the constant voltage diode 7, for example, 170 V, are accumulated in the capacitor 8. Thereafter, the discharge current at the spark plug 6 is gradually reduced, for example, at a peak current of 100 mA, and while the discharge duration of about 3 ms is completed, the ignition flame nucleus in the cylinder is sufficiently expanded to generate combustion ions. To do. Since the charge voltage of the capacitor 8 is applied to both ends of the electrode of the spark plug 6, an ion current corresponding to the combustion state flows and the ions are taken into the ion detector 11 through the register 10, and then the ECU 13 Information processing.

  The signal sent to the ECU 13 by the ion detector 11 that captures changes in the ionic current, as well as detecting misfire and knock of the internal combustion engine, captures the lean limit of the combustion pressure and air-fuel ratio, and reduces exhaust gas and improves fuel efficiency. It is useful for.

  In order to effectively detect the ion current information, it is necessary to observe the ion current detection start time from about 15 degrees ATDC at least in the practical rotational range of the internal combustion engine. It is required to complete the discharge time at a discharge time having a gradient of 2.5 ms or more at an idle speed of about 800 rpm and at a speed of about 6000 rpm at a high speed of about 6000 rpm.

  When the rotational speed of the internal combustion engine increases, the discharge duration time needs to be shortened. Therefore, in order to reduce the energy accumulated in the primary wire ring 100 of the ignition coil 2, the first switching element 3 is turned off as the rotational speed increases. This can be realized by sequentially reducing the hour current from 8 A to about 5 A, but simultaneously with the reduction of the off-time current, the output voltage induced in the secondary wire ring 200 also decreases. Accordingly, when the rotational speed reaches a value before the limit of the required output voltage of the internal combustion engine is reached, the drive circuit 5 is programmed in advance to stop the operation of the first switching element 3 and simultaneously switch to the operation of the second switching element 4. Has been.

  When the ignition operation is switched to the second switching element 4, the induction energy is reduced to the induction energy determined by the number of turns to the tap terminal 103 of the primary coil 100 of the ignition coil 2 and the energization current, the peak value of the discharge current is low, and the discharge continues. Although the time is shortened, the ignition output voltage is increased in accordance with the turn ratio by increasing the turn ratio with the secondary wire 200.

  The graphs of FIG. 2 show the characteristics of the engine speed, the discharge duration when the switching elements are switched, and the output voltage.

  In the above embodiment, only one tap terminal 103 is provided on the primary wire ring 100. However, by providing a plurality of tap terminals and switching elements, the characteristic curve shown in FIG. Can be made.

  The discharge duration in the above embodiment is about 3 ms, which is much larger than the normal ignition coil discharge duration of about 1.5 ms, but the discharge duration is considered to be a required characteristic of the near future fuel direct injection internal combustion engine. For example, it was confirmed that the ignition coil using a closed magnetic circuit core having a cross-sectional area of about 160? In this case as well, it goes without saying that the use of a bias magnet can reduce the size and weight.

  When each switching element Q1 is turned on, a voltage supplied from the power source 1, for example, 14V, is applied to the primary wire ring 100, and a voltage with the high voltage side of the secondary wire ring 200 as the positive electrode is induced. However, the diode 9 is partially blocked, and the value of the resistor 10 is large, so that a voltage of 1 kV or higher necessary for discharging to the spark plug 6 is not generated across the electrodes of the spark plug 6.

  Although the detection register 10 connected to the ion detector 11 of the above embodiment is connected to the low voltage side of the secondary ring 200, the present invention is effective even if it is configured to be connected to a known high voltage side. is there.

  Further, it goes without saying that a protection element for limiting the back electromotive force of the primary ring 100 can be added to each of the switching elements 3 and 4. The switching element can be selected as appropriate, such as a normal transistor or IGBT.

The figure which shows the Example of invention FIG. 1 is a graph showing operating characteristics of the embodiment of the invention of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply 2 Ignition coil 3, 4 Switching element 5 Drive circuit 6 Spark plug 7 Constant voltage diode 8 Capacitor 9 Diode 10 Resistor 11 Ion current detection device 12 Protection diode 13 ECU
100 Primary wire ring 101 Terminal 103 Tap terminal 200 Secondary wire ring 201 High voltage side terminal 202 Low voltage side terminal

Claims (5)

At least one tap terminal is provided in the middle of the primary wire ring provided with a power source at one terminal of the ignition coil, a switching element is provided on each of the tap terminal and the other terminal of the primary wire ring, and two terminals of the ignition coil are provided. An ignition device comprising an ion current detection device, characterized in that an ignition plug and an ion current detection device are provided on the next wheel, and the operation of the switching element is switched in accordance with the rotational speed of the internal combustion engine. When the rotational speed of the internal combustion engine is low, the switching element provided in the other terminal which is the end of the primary wire ring operates, and when the rotational speed is high, the switching element provided in the tap terminal of the primary wire ring operates. An ignition device comprising the ion current detection device according to claim 1. 3. The ion current according to claim 1, wherein the discharge duration of the ignition coil is 2.5 ms or more when the internal combustion engine is at an idling speed, and is 1.0 ms or less at a high speed. An ignition device including a detection device. The ion current detection device according to any one of claims 1 to 3, wherein the detection start time of the ion current detection circuit is set to about 15 degrees ATDC (after compression top dead center) at least in a practical rotational range of the internal combustion engine. Ignition device. 5. An ignition device comprising the ion current detection device according to claim 1, wherein the magnetic circuit of the ignition coil has an iron core structure with a closed magnetic circuit.

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