JP4379309B2 - Ignition system for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition system for an internal combustion engine using a capacitor discharge type.

  Various capacitor discharge type ignition devices for internal combustion engines have been proposed in the past. For example, there are a configuration as shown in Patent Document 1 and a configuration as shown in FIG. Since the ignition device 20 shown in FIG. 2 (a) has substantially the same configuration as that of Patent Document 1 except that the connection of the grounding portion is slightly different, the background art will be described with reference to FIG. 2 (a).

  In the ignition device 20 shown in FIG. 2A, one end of the exciter coil 21 is grounded via a diode 22, a primary capacitor 24a for the ignition capacitor 23 and the ignition coil 24, and the other end of the exciter coil 21 is connected to the diode 25. Is grounded. The exciter coil 21 induces an AC voltage in synchronism with the rotation of the engine. Based on the positive side rectified by the diodes 22 and 25 among the induced AC voltage, the electric charge is supplied to the ignition capacitor 23. Accumulated (charged). That is, the exciter coil 21 and the diodes 22 and 25 constitute a charging circuit.

  One end of the exciter coil 21 is grounded via a diode 26, and the other end of the exciter coil 21 is grounded via a power supply circuit 27. Of the AC voltage induced by the exciter coil 21, the negative side rectified by the diode 26 is supplied to the power supply circuit 27, and the supplied negative AC voltage is rectified to generate a DC voltage. The power supply circuit 27 applies the generated DC voltage as a power supply voltage for an ignition timing control circuit 29 described later.

  The node between the diode 22 and the ignition capacitor 23 is connected to the anode of a discharge thyristor 28 that constitutes a discharge circuit, and the cathode of the thyristor 28 is grounded. An ignition signal (trigger signal) output from the ignition timing control circuit 29 is input to the gate of the discharge thyristor 28. One end of a pulsar coil 30 whose other end is grounded is connected to the ignition timing control circuit 29, and a pulse timing signal corresponding to a predetermined rotational position of the engine is input from the pulsar coil 30. The ignition timing control circuit 29 operates when one power supply terminal is connected to the power supply circuit 27 and the other power supply terminal is grounded, and the power supply voltage generated by the power supply circuit 27 is applied. To do. The ignition timing control circuit 29 generates an ignition signal (trigger signal) based on the timing signal from the pulsar coil 30, outputs the ignition signal to the gate of the discharge thyristor 28, and causes the thyristor 28 to perform predetermined ignition. Turn on at the timing.

  When the discharge thyristor 28 is turned on, the electric charge accumulated on the anode side of the ignition capacitor 23 flows to the ground side through the thyristor 28 as a discharge current, and from the ground side through the primary coil 24a of the ignition coil 24. Thus, a current flows to the cathode side of the ignition capacitor 23. As a result, a high voltage is induced in the primary coil 24a of the ignition coil 24, a high voltage is generated in the secondary coil 24b of the ignition coil 24, and spark discharge is generated in the spark plug 31 connected to the secondary coil 24b. It has come to occur.

  By the way, the above-mentioned diodes 22, 25, 26, the ignition capacitor 23, the discharge thyristor 28, the power supply circuit 27, the ignition timing control circuit 29, etc. On the other hand, the exciter coil 21, the pulsar coil 30, the ignition coil 24, and the spark plug 31 are provided separately from the ignition unit 35. In the ignition unit 35, the anodes of the diodes 25 and 26 that need to be grounded, the cathode of the discharge thyristor 28, the power supply circuit 27, and the ignition timing control circuit 29 are connected to the same grounding terminal TG provided in the ignition unit 35. The grounding terminal TG is connected to a grounding part near the unit 35 using a grounding wire or the like. On the other hand, outside the ignition unit 35, the other end of the ignition coil 24 that needs to be grounded and the other end of the pulsar coil 30 are respectively connected to a grounding part located in the vicinity of itself.

  In the ignition device 20 having such a configuration, the ignition unit 35 may be poorly grounded due to poor contact with the ground wire, disconnection of the ground wire, forgetting to attach the ground wire, or the like. In this case, as shown by a broken line in FIG. 2B, the exciter coil 21 to the diode 22, the ignition capacitor 23, the primary coil 24a of the ignition coil 24, the pulsar coil 30, the ignition timing control circuit 29, and the diode 25 An abnormal current flows through

  On the other hand, the ignition timing control circuit 29 is configured using elements such as a resistor, a diode, and a transistor. However, since the ignition timing control circuit 29 handles a small output from the pulsar coil 30, these elements are originally matched to the output of the pulsar coil 30. It is possible to configure with an element for low power.

However, if the ignition unit 35 is poorly grounded as described above, an abnormal current sufficiently larger than the output of the pulsar coil 30 flows in the ignition timing control circuit 29. Therefore, the ignition timing control by the abnormal current is performed. In order to prevent damage to the constituent elements of the circuit 29, it was necessary to use a high power element for the element. That is, in this ignition device 20, there is a concern that the element configuration of the ignition timing control circuit 29 is wasted and this affects the cost of the ignition device 20.
JP-A-7-54743

  According to the present invention, an abnormal current generated when an ignition unit becomes poorly grounded while an ignition timing control circuit that generates an ignition signal based on the output of the pulsar coil is configured with a low-power element that matches the output of the pulsar coil. The main object of the present invention is to provide an ignition system for an internal combustion engine that can prevent the control circuit from being damaged by preventing the control circuit from flowing into the control circuit.

  Hereinafter, effective means for solving the above-described problems will be described while showing effects.

  Means 1. An ignition system for an internal combustion engine has an ignition capacitor for accumulating charges for ignition and an exciter coil for inducing an AC voltage in synchronization with the rotation of the engine, and the AC voltage induced by the exciter coil A charge circuit that takes out one polarity from the voltage and accumulates electric charge in the ignition capacitor based on the voltage of the one polarity, and a discharge having a primary coil of the ignition coil that accumulates the electric charge accumulated in the ignition capacitor based on the ignition signal A discharge circuit for generating a spark discharge in a spark plug connected to the secondary coil of the ignition coil by inducing voltage in the primary coil due to the discharge, and a timing signal corresponding to a predetermined rotational position of the engine And an ignition signal is generated based on a timing signal from the pulsar coil, and the ignition signal is output to the discharge circuit. An ignition timing control circuit is provided that. The charging circuit, the discharging circuit, and the ignition timing control circuit that require grounding are connected to the same ground terminal and grounded, and the primary coil of the pulser coil and the ignition coil are grounded separately from the ground terminal. When a ground failure occurs at the ground terminal, the abnormality detection circuit detects an abnormal current flowing through the ignition capacitor caused by the ground failure at the ground terminal. The switching circuit is provided between the ignition capacitor and the primary coil of the ignition coil. When an abnormal current is detected by the abnormality detection circuit, a current discharge path in which the current path of the abnormal current is provided in parallel with the primary coil. Switch to.

  That is, in the ignition system connected as described above, when a ground failure occurs in the ground terminal, an abnormal current caused by the ground contact failure of the ground terminal is detected by the abnormality detection circuit, and the current path of the abnormal current is detected by the switching circuit. It is switched to a current discharge path in parallel with the primary coil. That is, the abnormal current flows again from the charging circuit (exciter coil) to the charging circuit via the ignition capacitor and the switching circuit (current discharge path), and does not pass through the pulsar coil and the ignition timing control circuit. As a result, even if the components (resistors, diodes, transistors, etc.) of the ignition timing control circuit are used for low power in accordance with the output of the pulsar coil, the control circuit (component) can be prevented from being damaged by the abnormal current described above. it can.

  Mean 2. In the means 1, the switching circuit is configured by using a semiconductor switch that is turned on based on detection of an abnormal current and that itself becomes a current discharge path.

  That is, a switching circuit configured using a semiconductor switch can constitute a more reliable ignition system in terms of operating speed, reliability of conduction, and the like than a mechanical switch having contacts.

  Means 3. In the means 1 or 2, the abnormality detection circuit is configured using a resistance voltage dividing circuit, and switches the switching circuit based on a signal from a node divided by the resistance voltage dividing circuit.

  That is, since the abnormality detection circuit is configured using a resistance voltage dividing circuit, the circuit configuration can be simplified.

Means 4 . In any one of the above means 1 to 3, the charging circuit excluding the exciter coil, the discharging circuit, the ignition timing control circuit, the abnormality detection circuit, and the switching circuit are unitized as an ignition unit, and among these circuits, at least the charging circuit and The ignition timing control circuit is connected to the same ground terminal provided in the ignition unit and grounded.

  In other words, the unit is configured as an ignition unit in this way, and the grounding terminal provided in the ignition unit is used for grounding in an integrated manner. A path is formed from the primary coil of the coil via the pulsar coil and the ignition timing control circuit. Therefore, it is significant to provide the above-described abnormality detection circuit and switching circuit in the ignition system unitized in this way.

Means 5 . In any one of the above means 1 to 4 , a power supply that extracts a polarity opposite to the polarity used in the charging circuit from the AC voltage induced in the exciter coil and generates a power supply voltage for the ignition timing control circuit based on the voltage A circuit is provided.

  That is, since the power supply circuit generates the power supply voltage of the ignition timing control circuit from the AC voltage induced in the exciter coil, it is not necessary to separately provide a power supply circuit for generating the power supply voltage of the ignition timing control circuit.

  Hereinafter, an embodiment in which the present invention is embodied in an ignition device for a two-wheeled vehicle engine, which is an internal combustion engine, will be described with reference to the drawings. As shown in FIG. 1 (a), the ignition device 10 of the present embodiment is configured by adding a current path switching circuit 11 to the background art ignition device 20 shown in FIG. 2 (a). ing. Therefore, the following description will focus on the current path switching circuit 11.

As shown in FIG. 1A, the current path switching circuit 11 includes a switching thyristor 12 and voltage dividing resistors 13 and 14 . Incidentally, as a response the means 1-5, switching thyristor 12 corresponds to the switching circuit and the semiconductor switch, the resistor 13 corresponds to resistor divider and abnormality detection circuit.

The anode of the switching thyristor 12 is connected to the negative electrode side of the ignition capacitor 23, and the cathode of the thyristor 12 is connected to the ground terminal TG. The resistors 13 and 14 are connected in series between the anode side of the ignition capacitor 23 (a node between the ignition capacitor 23 and the diode 22) and the ground terminal TG, and the anode side of the ignition capacitor 23 and the ground terminal The potential difference from TG is divided. The gate of the switching thyristor 12 is connected to the node between the resistors 13 and 14. Incidentally, the potential (current value) of the node between the resistors 13 and 14 is a potential (current value) at which the switching thyristor 12 is not turned on during a normal ignition operation, and an abnormal current of an abnormal current occurs when a grounding failure occurs. The resistance values of the resistors 13 and 14 are set so as to rise to the potential (current value) at which the thyristor 12 is turned on by the generation .

  The ignition device 10 provided with such a current path switching circuit 11 operates in the same manner as the ignition device 20 in a normal ignition operation. That is, an alternating voltage is induced in the exciter coil 21 in synchronization with the rotation of the engine, and charges are accumulated in the ignition capacitor 23 based on the positive side of the induced alternating voltage. This charged charge becomes ignition energy.

  When the ignition timing is reached, an ignition signal (trigger signal) is output from the ignition timing control circuit 29 to the gate of the discharge thyristor 28, and the thyristor 28 is turned on based on the ignition signal. Then, the charge accumulated on the anode side of the ignition capacitor 23 flows as a discharge current to the ground side via the discharge thyristor 28, and from the ground side to the cathode of the ignition capacitor 23 via the primary coil 24a. Current flows to the side.

  As a result, a high voltage is induced in the primary coil 24a of the ignition coil 24, a high voltage is generated in the secondary coil 24b of the ignition coil 24, and spark discharge is generated in the spark plug 31 connected to the secondary coil 24b. Arise. The spark discharge generated at the spark plug 31 burns the air-fuel mixture in the cylinder and operates the engine. Such ignition operation is repeated during engine operation.

  In such a normal ignition operation, in the current path switching circuit 11, the potential (current value) of the node between the resistors 13 and 14 changes, but the switching thyristor 12 is turned on by setting each resistance value of the resistors 13 and 14. Therefore, the thyristor 12 is not turned on. That is, the current path switching circuit 11 does not hinder normal ignition operation.

  On the other hand, when the ignition unit 35 becomes poorly grounded due to poor contact with the grounding wire, disconnection of the grounding wire, forgetting to attach the grounding wire or the like, an abnormal current is generated in the ignition device 10, thereby causing the current path switching circuit 11 to The potential (current value) of the node between the resistors 13 and 14 is higher than that during the normal ignition operation. Then, the value of the current flowing from the node between the resistors 13 and 14 to the gate of the switching thyristor 12 eventually exceeds the threshold value, and the thyristor 12 is turned on, as shown by the current path A indicated by the broken line in FIG. The path through which the abnormal current flows is switched. The abnormal current flows from the exciter coil 21 through the diode 22, the ignition capacitor 23, the switching thyristor 12, and the diode 25.

  Therefore, the abnormal current does not flow (is suppressed) to the primary coil 24a, the pulsar coil 30 and the ignition timing control circuit 29 of the ignition coil 24, so that the components of the control circuit 29 (resistance, diode, transistor, etc.) These elements are also prevented from being damaged even when used for low power in accordance with the output of the pulsar coil 30.

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

  In the present embodiment, when a ground failure occurs in the ground terminal TG, an abnormal current generated due to the ground failure of the ground terminal TG is detected by the resistors 13 and 14 of the current path switching circuit 11 (the node between the resistors 13 and 14). As a result, the switching thyristor 12 of the switching circuit 11 is turned on, and the current path of the abnormal current is provided in parallel with the primary coil 24a of the ignition coil 24. The discharge path (path through the thyristor 12 itself) is switched. That is, the abnormal current flows from the exciter coil 21 side through the ignition capacitor 23 and the switching thyristor 12 to the exciter coil 21 side again as shown in the current path A of FIG. No longer goes through 29. As a result, even if the constituent elements (resistors, diodes, transistors, etc.) of the ignition timing control circuit 29 are for low power that matches the output of the pulser coil 30, the control circuit 29 (constituent elements) is prevented from being damaged by the abnormal current described above. can do.

  Further, as described above, the ignition unit 35 is unitized, and the ground terminal TG provided in the ignition unit 35 is used for grounding, so that the ground terminal TG is poorly grounded. A path is formed through which the abnormal current generated passes from the primary coil 24 a of the ignition coil 24 through the pulser coil 30 and the ignition timing control circuit 29. Therefore, it is significant to provide the current path switching circuit 11 in the ignition device 10 that is unitized in this way.

  In the present embodiment, the switching thyristor 12 which is a semiconductor switch is used to switch the current path of the abnormal current. Therefore, the operation speed and the reliability of conduction are more reliable than the mechanical switch having a contact. Thus, the ignition device 10 having high reliability can be configured.

  In the present embodiment, since the detection of abnormal current is configured by the resistance voltage dividing circuit using the resistors 13 and 14, the circuit configuration can be simplified.

  In the present embodiment, since the power supply circuit 27 for generating the power supply voltage of the ignition timing control circuit 29 from the AC voltage induced by the exciter coil 21 is used, the power supply voltage of the ignition timing control circuit 29 is generated. There is no need to provide a separate power circuit.

  In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

  In the above embodiment, the switching thyristor 12 is used as the switching circuit for switching the current path of the abnormal current. However, a semiconductor switch other than the thyristor, for example, a bipolar transistor, an FET, or the like may be used. In addition, it is preferable to use a semiconductor switch as in the present embodiment, but a mechanical switch having a contact may be used.

  In the above embodiment, the abnormal current is detected by the resistance voltage dividing circuit using the resistors 13 and 14, but the abnormal current may be detected by using a circuit other than this. Further, although the resistors 13 and 14 are provided on the anode side of the ignition capacitor 23, they may be provided at other locations.

  You may change suitably the structure of the ignition device 10 in the said embodiment other than the said another example. For example, you may comprise so that the polarity of the capacitor | condenser 23 for ignition may be reverse. The power supply circuit 27 that generates the power supply voltage of the ignition timing control circuit 29 may be omitted. In this case, either the diode 22 or the diode 25 and the diode 26 can be omitted. Moreover, it is good also as multiple, such as the exciter coil 21 and the primary coil 24a (secondary coil 24b) of the ignition coil 24. FIG.

(A) is an electrical block diagram of the ignition device of the internal combustion engine in the present embodiment, (b) is an electrical block diagram for explaining the flow of abnormal current at the time of poor grounding. (A) is an electrical block diagram of the ignition device of the internal combustion engine in the background art, (b) is an electrical block diagram for explaining the flow of abnormal current at the time of poor grounding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 ... Switching thyristor (switching circuit), 13, 14 ... Voltage dividing resistor (abnormality detection circuit and resistance voltage dividing circuit) , 21 ... Exciter coil (charging circuit), 22, 25 ... Diode (charging circuit), 23 ... Ignition Capacitor, 24 ... Ignition coil, 24a ... Primary coil, 24b ... Secondary coil, 28 ... Discharge thyristor (discharge circuit), 29 ... Ignition timing control circuit, 30 ... Pulsar coil, 31 ... Ignition plug, TG ... Ground terminal.

Claims (5)

An ignition capacitor in which charge for ignition is accumulated;
Having an exciter coil that induces an alternating voltage in synchronization with the rotation of the engine, taking out one polarity from the alternating voltage induced by the exciter coil, and charging the ignition capacitor based on the voltage of the one polarity A charging circuit that accumulates
Based on the ignition signal, the electric charge accumulated in the ignition capacitor is discharged through a discharge path having a primary coil of the ignition coil, and is connected to the secondary coil of the ignition coil by voltage induction of the primary coil due to the discharge. A discharge circuit that generates a spark discharge at the spark plug;
A pulsar coil that outputs a timing signal corresponding to a predetermined rotational position of the engine;
An ignition timing control circuit that generates the ignition signal based on a timing signal from the pulsar coil and outputs the ignition signal to the discharge circuit;
The charging circuit, the discharging circuit, and the ignition timing control circuit that need to be grounded are connected to the same ground terminal and grounded, and the primary coil of the pulsar coil and the ignition coil are grounded separately from the ground terminal. An internal combustion engine ignition system,
An abnormality detection circuit for detecting an abnormal current flowing in the ignition capacitor caused by a grounding failure of the ground terminal;
Provided between the ignition capacitor and the primary coil of the ignition coil, and when the abnormal current is detected by the abnormality detection circuit, the current discharge of the abnormal current provided in parallel with the primary coil A switching circuit for switching to the path;
An internal combustion engine ignition system comprising:   2. The ignition system for an internal combustion engine according to claim 1, wherein the switching circuit is configured using a semiconductor switch that is turned on based on detection of the abnormal current and that serves as the current discharge path. 3.   2. The abnormality detection circuit is configured using a resistance voltage dividing circuit, and switches the switching circuit based on a signal from a node divided by the resistance voltage dividing circuit. 3. An ignition system for an internal combustion engine according to 2. The charging circuit excluding the exciter coil, the discharging circuit, the ignition timing control circuit, the abnormality detection circuit, and the switching circuit are unitized as an ignition unit, and at least the charging circuit and the ignition timing control among these circuits. The internal combustion engine ignition system according to any one of claims 1 to 3, wherein the circuit is connected to the same grounding terminal provided in the ignition unit and grounded. A power supply circuit is provided that extracts a polarity opposite to the polarity used in the charging circuit from the AC voltage induced in the exciter coil, and generates a power supply voltage of the ignition timing control circuit based on the voltage. An ignition system for an internal combustion engine according to any one of claims 1 to 4.

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