WO2011138861A1

WO2011138861A1 - Capacitor discharge type internal-combustion engine ignition device

Info

Publication number: WO2011138861A1
Application number: PCT/JP2011/002494
Authority: WO
Inventors: 一智西田; 賢太郎谷口; 旭洋柿島; 正幸杉山; 明下山; 靖一波多野; 啓平松
Original assignee: 本田技研工業株式会社; 国産電機株式会社
Priority date: 2010-05-07
Filing date: 2011-04-28
Publication date: 2011-11-10
Also published as: JP2011236763A

Abstract

In a capacitor discharge type internal-combustion engine, the risks of malfunction and trouble due to a surge intruding via an engine stop switch can be eliminated. A capacitor discharge type internal-combustion engine ignition device comprises: an ignition capacitor provided on the primary side of an ignition coil; a charging circuit for charging the ignition capacitor using the output voltage of an exciter coil; and an ignition switch for discharging the charge stored on the ignition capacitor via the primary coil of the ignition coil. In the capacitor discharge type internal-combustion engine ignition device, an engine stop switch is inserted into the charging circuit, and a constant-voltage circuit that performs an operation for limiting the induced voltage of the exciter coil to a certain value or less is connected to both ends of the exciter coil.

Description

Ignition system for capacitor discharge internal combustion engine

The present invention relates to a capacitor discharge type internal combustion engine ignition device that charges an ignition capacitor with the output of a magnet generator attached to the engine.

For example, as shown in FIG. 9, this type of ignition device is provided in a magnet generator driven by an internal combustion engine, and an exciter coil 1 that induces an AC voltage in synchronization with the rotation of the engine, and a primary An ignition coil 2 having a coil 2a and a secondary coil 2b, an ignition capacitor 3 provided on the primary side of the ignition coil, and a half cycle induced voltage of one polarity of the exciter coil 1 between the diode 4 and the ignition coil 2 A charging circuit for charging the ignition capacitor 3 with the polarity shown in the figure through the primary coil 2a, and the charge stored in the ignition capacitor 3 when turned on when the ignition signal Vi is applied to the primary coil of the ignition coil A thyristor 5 as an ignition switch for discharging through 2a, and an ignition control unit 6 for giving an ignition signal Vi to the thyristor 5 at the ignition timing of the engine are provided.A spark plug 7 attached to the cylinder of the engine is connected to the secondary coil 2b of the ignition coil 2. FIG. 9 shows the configuration of the capacitor discharge ignition device disclosed in Patent Document 1 almost as it is.

In this type of ignition device, in order to operate the ignition control unit 6, a DC power supply unit that supplies a constant DC voltage to the ignition control unit 6 as a power supply voltage is required. This DC power supply unit is constituted by a battery and a power supply circuit that converts the voltage of the battery into a constant DC voltage, or an exciter coil and a constant DC voltage by converting the rectified output of the exciter coil to a constant voltage. And a power supply circuit that outputs a voltage.

In the capacitor discharge type ignition device as shown in FIG. 9, the ignition capacitor 3 is charged with the half-cycle output voltage of one polarity of the exciter coil 1 at a timing before the ignition timing of the engine. At the ignition timing, the thyristor (ignition switch) 5 is turned on to discharge the charge of the ignition capacitor 3 through the primary coil 2a of the ignition coil. When the charge of the ignition capacitor is discharged through the primary coil 2a of the ignition coil, a high voltage is induced in the primary coil 2a, and this voltage is further boosted at the boost ratio between the primary and secondary of the ignition coil. A high voltage for ignition is induced in the secondary coil 2b of the ignition coil. Since the high voltage for ignition is applied to the spark plug 7 attached to the cylinder of the engine, a spark discharge is generated at the spark plug 7 and the engine is ignited.

In order to stop the internal combustion engine ignited by the capacitor discharge ignition device, it is necessary to stop the operation of the ignition device. In the ignition device that operates the ignition control unit by supplying a power supply voltage from a DC power source unit that uses a battery as a power source and operates the ignition control unit, the ignition operation is stopped by opening the key switch. Can do. However, when the DC voltage obtained by making the rectified output of the exciter coil constant without using a battery is used as the power supply voltage of the ignition control unit, a key switch is not provided, so that the ignition operation is stopped. It is necessary to devise something.

There are two known methods for stopping the ignition operation of a batteryless capacitor discharge ignition device. In one method, an engine stop switch that is kept off during engine operation and is turned on when the engine is stopped is used to short out some of the components of the ignition device. To stop the ignition operation. The engine stop switch used in this method is called a short-circuit stop type engine stop switch. In another method, an engine stop switch that is kept on during engine operation and is turned off when the engine is stopped is inserted in a circuit constituting the ignition device, and the engine stop switch is turned off. The ignition operation is stopped by releasing a part of the circuit of the ignition device in the state. The engine stop switch used in this method is called an open stop type engine stop switch.

Normally, an engine stop switch contains switch components such as a fixed contact and a movable contact in an insulating resin case, and is attached to the insulating case in such a way that operation parts such as push buttons and knobs can be operated from the outside. The case is attached to a location where the engine as a drive source is easy to operate. Since the engine stop switch case is exposed to the outside, if the engine stop switch is exposed to the wind while the air is dry or if the operator's clothing rubs the switch case, May be charged and surge voltage or surge current (hereinafter referred to as surge) may enter the ignition device through the contact of the engine stop switch.

When a short-circuit stop type engine stop switch is used, the engine stop switch is kept off during engine operation. There is a possibility that a surge may intrude, and the ignition control unit malfunctions due to this surge, causing the ignition device to operate abnormally, or the potential of the exciter coil 1 may rise to cause dielectric breakdown.

In order to prevent the above problem from occurring, in the capacitor discharge type ignition device disclosed in Patent Document 1, as shown in FIG. 9, the gate of the thyristor 5 constituting the ignition switch is ignited. In addition to the ignition control unit 6 for providing a signal, a circuit for providing a trigger signal from the exciter coil 1 to the gate of the thyristor 5 through the resistor 8 and the diode 9 is provided, and an open stop type engine stop is provided between the anode of the diode 9 and the ground. The switch 10 is connected. In order to prevent a surge from entering when the engine stop switch 10 is in the OFF state, surge absorbing elements 11 are connected to both ends of the engine stop switch 10.

In the ignition device disclosed in Patent Document 1, the engine stop switch 10 is kept on during operation of the engine to prevent a trigger signal from being applied to the thyristor 5 from the exciter coil 1 through the resistor 8 and the diode 9. To do. Thus, only the ignition signal Vi output from the ignition control unit 6 is given to the thyristor 5 so that the engine ignition operation can be performed without any trouble.

When stopping the engine, a trigger signal is given from the exciter coil 1 to the thyristor 5 by turning off the engine stop switch 10. In this state, the exciter coil generates a voltage with a polarity for charging the ignition capacitor 3, and at the same time, the thyristor 5 is turned on to short-circuit the output of the exciter coil. Operation stops. With this configuration, when a surge enters through the contact of the engine stop switch 10 during the operation of the engine, the surge can be released to the ground through the engine stop switch 10 in the on state. Thus, it is possible to prevent a surge from entering the ignition control unit 6 and a surge from entering the exciter coil 1.

However, when the open / stop engine stop switch 10 is connected to the trigger circuit of the thyristor as in the ignition device disclosed in Patent Document 1, the engine stop switch 10 is turned off when the engine stop switch 10 is turned off. A surge may enter the gate circuit of the thyristor 5 and the ignition control unit 6 through the stop switch, and the thyristor 5 and the ignition control unit 6 may be damaged. Therefore, when an open / stop engine stop switch 10 is connected to the trigger circuit of the thyristor 5 as in the ignition device disclosed in Patent Document 1, the thyristor 5 and the ignition control unit 6 are protected from surges. It is necessary to take measures. In the ignition device disclosed in Patent Document 1, surge absorbing elements 11 are connected to both ends of the engine stop switch 10 so that surges entering when the engine stop switch 10 is turned off are absorbed by the surge absorbing element 11. .

Japanese Patent Laying-Open No. 2008-75502 (FIG. 2)

As described above, in the ignition device disclosed in Patent Document 1, when the engine stop switch 10 is turned off, a surge enters the gate of the thyristor 5 and the ignition control unit 6 through the engine stop switch 10. In order to prevent this, it is necessary to connect the surge absorbing element 11 to both ends of the engine stop switch 10. However, when the surge absorbing element 11 is connected to both ends of the engine stop switch 10, the surge absorbing element 11 is damaged and the engine stop switch 10 is short-circuited. Since the current paths are formed in parallel, there arises a problem that the engine stop switch 10 does not function and the engine cannot be stopped.

SUMMARY OF THE INVENTION An object of the present invention is to ensure that a normal ignition operation during operation of an engine is ensured, and to reliably stop the engine when necessary, and to turn off the engine in order to stop the engine. An object of the present invention is to provide an ignition device for a capacitor discharge internal combustion engine in which when a surge intrudes through, the surge is applied to an ignition switch and an ignition control unit to prevent them from being damaged. .

The present invention relates to an exciter coil that induces an alternating voltage in synchronization with the rotation of an internal combustion engine, an ignition coil, an ignition capacitor provided on the primary side of the ignition coil, and induction of a half cycle of one polarity of the exciter coil. Capacitor discharge comprising a charging circuit for charging the ignition capacitor with a voltage, and an ignition switch that is turned on at the ignition timing of the internal combustion engine and discharges the charge accumulated in the ignition capacitor through the primary coil of the ignition coil This is applied to an internal combustion engine ignition device.

In the present invention, the charging current is allowed to flow from the exciter coil to the ignition capacitor when it is inserted in the middle of the charging circuit and is in the on state, and flows from the exciter coil to the ignition capacitor when it is in the off state. An engine stop switch that cuts off the charging current and a constant voltage circuit that performs control to limit the voltage of the one polarity induced in the exciter coil to a control value or less using a preset constant voltage value as a control value are provided. It is done.

With the above configuration, when the engine is operated, the ignition capacitor can be charged by holding the engine stop switch in the ON state, so that the ignition operation can be performed without any trouble. Also, when it is necessary to stop the engine, it is possible to prevent the ignition capacitor from being charged by turning off the engine stop switch, so that the ignition operation is stopped and the engine is immediately stopped. Can do.

As described above, if an engine stop switch is inserted into a circuit that allows the charging current to flow to the ignition capacitor with the output of the exciter coil, a surge will occur through the engine stop switch due to static electricity or the like when the engine stop switch is turned off. Even if it enters, the surge does not enter the control terminal of the ignition switch or the ignition control unit, so it is not necessary to connect a surge absorbing element in parallel to the engine stop switch. Therefore, it is possible to prevent a situation in which the engine stop switch is short-circuited due to breakage of the surge absorbing element and the engine cannot be stopped, and reliability can be improved.

As described above, when the engine stop switch is inserted into the circuit for charging the ignition capacitor with the output of the exciter coil, the engine stop switch is turned off while the charging current is flowing from the exciter coil to the ignition capacitor. Then, a high-polarity voltage that continues to flow the charging current that has flown until then is induced in the exciter coil, and this high voltage is applied to the engine stop switch. If a high voltage is allowed to be applied to the engine stop switch, it is necessary to use an expensive engine stop switch with a high withstand voltage, and the cost is unavoidable. If an arc is generated between the contact points of the engine stop switch due to the high voltage induced in the exciter coil when the engine stop switch is opened, these components are also applied to the charging circuit and ignition switch. May be damaged.

In order to prevent such a problem from occurring, in the present invention, the constant polarity control (voltage used to charge the ignition capacitor) induced in the exciter coil is limited to a certain control value or less. A voltage circuit is provided. By providing such a constant voltage circuit, it is possible to prevent high voltage from being induced in the exciter coil when the engine stop switch is turned off. The element can be prevented from being damaged.

In a preferred embodiment of the invention, one end of the exciter coil is grounded through a current feedback diode with the anode facing ground, and the charging circuit applies the induced voltage of one polarity half cycle of the exciter coil to the other end of the exciter coil. The ignition capacitor is configured to be charged by being applied to the ignition capacitor through a rectifying diode with the anode directed to the side. In this case, the engine stop switch is preferably inserted between the other end of the exciter coil and the anode of the rectifying diode.

In a preferred aspect of the present invention, the constant voltage circuit is connected in parallel to the voltage detection circuit for detecting the voltage at both ends of the exciter coil, and the exciter coil generates an induced voltage of the one polarity. An exciter short-circuit switch that is turned on when a trigger signal is applied while the exciter coil is generating an induced voltage of the one polarity and detected by a voltage detection circuit And an exciter short-circuit switch trigger circuit for providing a trigger signal to the exciter short-circuit switch when the measured voltage reaches the control value.

According to the present invention, the engine stop switch is inserted into a circuit for supplying a charging current to the ignition capacitor with the output of the exciter coil, and the ignition capacitor is charged by charging the ignition capacitor through the engine stop switch that is in an ON state when the engine is operating. When stopping the engine without any trouble, the engine stop switch is turned off to prevent the ignition capacitor from being charged, so that the ignition operation is stopped. It is possible to reliably stop the engine when necessary while guaranteeing a proper ignition operation.

Further, according to the present invention, when an engine stop switch is inserted into a circuit for supplying a charging current to the ignition capacitor with the output of the exciter coil, when the engine stop switch is turned off, the surge current is passed through the engine stop switch due to static electricity or the like. This prevents the surge from entering the control terminal of the ignition switch and the ignition control section even if it enters, thus eliminating the need to connect a surge absorbing element in parallel to the engine stop switch. Can do. Therefore, when a surge enters through the engine stop switch, it can be prevented that the engine stop switch is short-circuited and the engine cannot be stopped.

Further, in the present invention, a constant voltage circuit is provided for performing control to limit the voltage of one polarity induced in the exciter coil to a certain control value or less, and when the engine stop switch is turned off, a high voltage is applied to the exciter coil. When the engine stop switch is turned off, it is possible to prevent an overvoltage from being applied from the exciter coil to the ignition device component, thereby damaging the component. The reliability of the capacitor discharge type internal combustion engine ignition device including the switch can be improved.

1 is a block diagram schematically showing a configuration of an embodiment of an ignition device for a capacitor discharge internal combustion engine according to the present invention. FIG. FIG. 2 is a circuit diagram showing an example of a specific configuration of the capacitor discharge type internal combustion engine ignition device shown in FIG. 1. It is the front view which showed roughly the structure of the magnet generator used by embodiment of FIG.1 and FIG.2. FIG. 4 is a waveform diagram showing a waveform when no AC voltage is obtained from an exciter coil provided in the magnet generator shown in FIG. 3. FIG. 3 is a waveform diagram schematically showing waveforms during operation of an output voltage of a half cycle of one polarity of the exciter coil of the ignition device shown in FIG. 2. FIG. 3 is a waveform diagram schematically showing voltage waveforms at both ends of an ignition capacitor of the ignition device shown in FIG. 2. (A) And (B) is a wave form diagram for demonstrating operation | movement of the waveform shaping circuit of the ignition device shown in FIG. It is the circuit diagram which showed the structure of other embodiment of the ignition device concerning this invention. It is the circuit diagram which showed the structure of the conventional ignition device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a configuration per cylinder of an embodiment of an ignition device according to the present invention. In the figure, 1 is an exciter coil made up of a power generation coil provided in a magnet generator driven by an internal combustion engine, 2 is an ignition coil having a primary coil 2a and a

secondary coil

2b, and 3 is on the primary side of the ignition coil 2. An ignition capacitor is provided. Reference numeral 4 denotes a rectifying diode that supplies a half-cycle voltage of one polarity of the exciter coil 1 to the ignition capacitor 3, and reference numeral 5 denotes an on-state when the ignition signal Vi is applied to turn on the charge of the ignition capacitor 3. A thyristor as an ignition switch for discharging the gas through the primary coil 2a of the ignition coil 2, an ignition control unit 6 for giving an ignition signal Vi to the gate of the thyristor 5 at the ignition timing of the internal combustion engine, and 7 attached to a cylinder of the internal combustion engine (not shown) And a spark plug connected to the secondary coil 2 b of the ignition coil 2.

As shown in FIG. 3, the magnet generator used in the present embodiment is fixed in an iron flywheel 100 formed in a cup shape or a disc shape, and a recess 101 provided on the outer periphery of the flywheel 100. An exciter coil 1 is disposed on an iron core 105 having a magnet rotor 103 having a permanent magnet 102 magnetized in the radial direction of the flywheel and

magnetic pole portions

105a and 105b facing the magnetic poles of the magnet rotor 103 via a gap. And a stator 106 wound around. The magnet rotor 103 is attached to the internal combustion engine by fitting a boss portion 100a provided at the axial center portion of the flywheel 100 to a crankshaft of an internal combustion engine (not shown) and fixing it to the crankshaft. The stator 106 is attached to the internal combustion engine by fixing the iron core 105 to a stator attachment portion provided in an engine case or cover.

In the magnet generator shown in FIG. 3, the magnetic pole on the outer peripheral side of the permanent magnet 102 (N pole in the illustrated example) and the two magnetic poles led out to the regions adjacent to both ends in the circumferential direction of the recess 101 ( A three-pole magnet field is constituted by S poles in the illustrated example. The illustrated exciter coil 1 has a positive half-cycle voltage (hereinafter referred to as positive voltage) V1 and a positive polarity as shown in FIG. 4 while the crankshaft of the internal combustion engine rotates. AC voltage composed of first and second negative half-cycle voltages (hereinafter referred to as first and second negative voltages) V21 and V22, respectively, generated before and after the half-cycle voltage V1. . In the present embodiment, among these voltages, a positive voltage (a voltage of one cycle half cycle) V1 is used for charging the ignition capacitor, and the first and second negative voltages (of the other polarity) are used. Half-cycle voltage) V21 and V22 are used as signal voltages for obtaining engine speed information and crank angle information.

In the ignition device shown in FIG. 1, one end of the primary coil 2a and secondary coil 2b of the ignition coil 2 is grounded, and the non-ground side terminal of the secondary coil 2b is connected to the non-ground side terminal of the spark plug 7. ing. One end of the ignition capacitor 3 is connected to the non-ground side terminal of the primary coil 2 a, and the other end of the capacitor 3 is connected to the cathode of the diode 4. In order to make it possible to use the negative voltages V21 and V22 induced in the exciter coil as signal voltages for obtaining engine rotation information necessary for performing ignition control, the exciter coil 1 is connected between one end and the ground and the exciter coil.

Current feedback diodes

20 and 21 having an anode directed to the ground side are connected between the other end of 1 and the ground, and an engine stop switch 10 is inserted between the other end of the exciter coil 1 and the anode of the rectifying diode 4. Has been.

The engine stop switch 10 is a switch that is kept on when the engine is operated and is turned off when operated by the driver when the engine is stopped. When the engine stop switch 10 is in the ON state, a charging current can flow from the exciter coil 1 to the ignition capacitor 3, so that the ignition capacitor 3 is charged each time the exciter coil 1 generates the positive voltage V1. The ignition operation of the engine is normally performed and the operation of the engine is maintained. On the other hand, when the engine stop switch 10 is turned off, the charging current cannot flow from the exciter coil 1 to the ignition capacitor 3, and the ignition capacitor 3 is not charged. No longer done and the engine is shut down.

In the present invention, the type of switch used as the engine stop switch 10 is not particularly limited. However, in order to prevent the engine stop switch 10 from being held in the off state even after the engine has stopped, it is a momentary type. An engine stop switch, such as a pushbutton switch or rocker switch, that is turned off only while force is applied to the operation unit and returns to the on state when the force applied to the operation unit is removed. It is preferably used as 10.

In this embodiment, a constant voltage circuit 22 is also connected between the other end of the exciter coil 1 and the ground. This constant voltage circuit is a circuit that performs control to limit one polarity voltage (positive voltage) V1 induced in the exciter coil 1 to a control value or less using a preset constant voltage value as a control value.

For example, the constant voltage circuit 22 is connected in parallel to the exciter coil 1 to detect a voltage at both ends of the exciter coil 1, and the exciter coil 1 generates an induced voltage V1 having one polarity. An exciter short-circuit switch that is turned on when a trigger signal is applied in the state and maintains the on state while the exciter coil 1 generates an induced voltage of one polarity, and is detected by a voltage detection circuit. An exciter short-circuit switch trigger circuit that gives a trigger signal to the exciter short-circuit switch when the voltage reaches the control value. When the constant voltage circuit 22 is configured in this way, the half-cycle voltage (positive voltage) V1 of one polarity induced in the exciter coil 1 falls to the zero level when it rises to the control value, and thereafter the polarity of one polarity The waveform which maintains the state of a zero level until the period of a half cycle of this is completed is shown.

In the ignition device shown in FIG. 1, one end of the exciter coil 1 is connected to the input terminal of the waveform shaping circuit 23 and the input terminal of the power supply circuit 24. The waveform shaping circuit 23 is a first signal S21 having a waveform that can be recognized by the microprocessor constituting the ignition control unit 6 with respect to the first and second negative voltages V21 and V22 (see FIG. 4) generated by the exciter coil 1. The second signal S22 is converted into the second signal S22, and the signals S21 and S22 are supplied to the ignition control unit 6.

When the positive voltage V1 generated by the exciter coil 1 is used as the charging voltage for the ignition capacitor and the negative voltages V21 and V22 are used as signal voltages for controlling the ignition timing as in the present embodiment, Positional relationship between the rotor 103 and the stator 105 of the magnet generator so that the exciter coil 1 generates a positive voltage V1 and negative voltages V21 and V22 at a crank angle position suitable for timing control. Is set.

In the present invention, it is arbitrary how to set the crank angle position at which the exciter coil generates the positive voltage V1 and the negative voltages V21, V22. In this embodiment, the piston of the engine is at the top dead center. The first negative polarity voltage V21 is generated at a position sufficiently advanced from the crank angle position (top dead center position) at which the crank angle position is reached, and the crank angle position (generally set near the top dead center position) The positional relationship between the rotor 103 and the stator 105 of the magnet generator is set so that the second negative voltage V22 is generated at a crank angle position suitable as an ignition position at the start of the engine). To do. In the present embodiment, the crank angle position where the negative voltage V21 is generated is used as the reference crank angle position at which the ignition timing measurement is started.

The power supply circuit 24 converts the first and second negative voltages V21 and V22 generated by the exciter coil 1 into a DC voltage Vcc having a certain level, and this DC voltage is a microprocessor constituting the ignition control unit 6. The power supply voltage is supplied as a power supply voltage to the power supply terminals of the waveform shaping circuit 23. For example, the power supply circuit 24 controls the charging of the power supply capacitor so that the power supply capacitor charged by the first and second negative voltages generated by the exciter coil 1 and the voltage Vcc across the power supply capacitor are kept constant. And a circuit. The current that flows from the exciter coil 1 into the power supply circuit 24 and charges the power supply capacitor is fed back to the exciter coil 1 through the diode 21. As the power supply circuit 24, a power supply circuit having a known configuration conventionally used in a batteryless capacitor discharge ignition device can be used.

In this embodiment, the exciter coil 1-engine stop switch 10-diode 4-ignition capacitor 3-ignition coil primary coil 2a-diode 20-exciter coil 1 closed circuit makes one cycle of the exciter coil 1 half cycle. A charging circuit is configured to charge the ignition capacitor 3 to one polarity with the induced voltage. In the present embodiment, a diode 25 in the opposite direction to the thyristor 5 is connected in parallel to the thyristor 5 constituting the ignition switch. This diode 25 is provided in order to extend the duration of the discharge of the ignition capacitor 3 at the time of ignition and to increase the duration of the spark.

The ignition control unit 6 includes, for example, a rotation speed calculation means for calculating the rotation speed of the engine from the generation intervals of the first and second signals S21 and S22 obtained from the waveform shaping circuit, and an ignition timing at the calculated rotation speed. Ignition timing determination means for determining, and ignition timer measurement time calculation means for calculating a time for the ignition timer to measure between the time when the first signal S21 is generated and the ignition timing in order to detect the determined ignition timing And an ignition signal generating means for generating an ignition signal Vi for giving an ignition signal to the thyristor 5 when the measurement of the measurement time calculated by the ignition timer is completed, and at an optimal ignition timing at each rotational speed of the engine. In order to ignite the engine, the timing for giving an ignition signal to the thyristor 5 is controlled. A batteryless capacitor discharge type internal combustion engine ignition device is configured by the above-described units.

In the ignition device shown in FIG. 1, the engine stop switch 10 is held in the on state when the internal combustion engine is operated. In this state, when the exciter coil 1 generates the positive voltage V1, the charging current flows from the exciter coil 1 through the engine stop switch 10, the diode 4, the ignition capacitor 3, the primary coil 2a of the ignition coil, and the diode 20. Flows and the ignition capacitor 3 is charged to the polarity shown in the figure. In the present embodiment, since the constant voltage circuit 22 that limits the positive voltage output from the exciter coil 1 to a predetermined control value or less is provided, the ignition capacitor 3 is charged to a constant voltage value every time. Is done. When the ignition control unit 6 detects an ignition timing of the engine and gives an ignition signal to the thyristor 5, the thyristor 5 is turned on, so that the charge accumulated in the ignition capacitor 3 is transferred between the thyristor 5 and the ignition coil 2. Discharge occurs through the primary coil 2a, and an ignition high voltage is induced in the secondary coil 2b of the ignition coil. Since this high voltage is applied to the spark plug 7, spark discharge occurs in the spark plug 7, and the engine is ignited.

In the capacitor discharge type ignition device, if the charging voltage of the ignition capacitor 3 is insufficient, the ignition high voltage induced in the secondary coil 2b of the ignition coil 2 becomes low, and the desired ignition performance cannot be obtained. Therefore, the control value of the constant voltage circuit 22 is necessary to make the peak value of the high voltage for ignition induced in the secondary coil of the ignition coil 2 equal to or higher than the minimum value necessary for causing spark discharge in the spark plug. It is set to a value that is higher than the lower limit value of the charging voltage value of the ignition capacitor 3 and is equal to or lower than the withstand voltage value of the element to which the positive voltage of the exciter coil 1 is applied. In the embodiment shown in FIG. 1, elements to which the positive polarity voltage of the exciter coil 1 is applied are the engine stop switch 10, the thyristor 5, the

diodes

4, 21, and 25. The control value is usually set to an appropriate value in the range of 200 to 200 tens of volts.

When stopping the engine, the engine stop switch 10 is turned off. When the engine stop switch 10 is turned off, the ignition capacitor 3 is not charged, so the ignition operation is not performed and the engine is immediately stopped.

As described above, in the ignition device of the present embodiment, the ignition capacitor can be charged by holding the engine stop switch 10 in the on state when the engine is operated, so that the ignition operation is performed without any problem. be able to. In addition, since the ignition stop capacitor 10 can be prevented from being charged by turning off the engine stop switch 10, the ignition operation can be stopped and the engine can be stopped.

As described above, when the engine stop switch 10 is inserted into the charging circuit of the ignition capacitor 3, even if a surge current enters through the engine stop switch due to static electricity or the like when the engine stop switch 10 is turned off, the thyristor 5 Therefore, it is not necessary to connect a surge absorbing element in parallel to the engine stop switch 10 because there is no possibility that a surge enters the gate (control terminal of the ignition switch) or the ignition control unit 6. Therefore, when the surge absorbing element is destroyed and short-circuited, it is possible to prevent a situation where the engine stop switch 10 is short-circuited and the engine cannot be stopped, and reliability is improved. Can be improved.

When the engine stop switch 10 is turned off while the charging current is flowing from the exciter coil 1 to the ignition capacitor 3, a high polarity voltage that continues to flow the charging current that has flown until then is generated in the exciter coil 1. However, in this embodiment, the constant voltage circuit 22 functions to limit the positive induced voltage of the exciter coil to a certain value or less. Therefore, the exciter coil is turned off when the engine stop switch 10 is turned off. 1 can prevent an excessive voltage from being induced. Therefore, when the engine stop switch 10 is turned off, an overvoltage is applied from the exciter coil 1 to the components of the charging circuit, the elements such as the thyristor 5, and the like can be prevented from being damaged. Further, according to the present embodiment, it is not necessary to use an expensive element having a high withstand voltage performance as an element to which the induced voltage of the exciter coil is applied, so that the cost of the ignition device can be reduced.

Referring to FIG. 2, an example of a specific configuration of the constant voltage circuit 22 and the waveform shaping circuit 23 of the ignition device shown in FIG. 1 is shown. The constant voltage circuit 22 shown in FIG. 2 includes a voltage dividing circuit composed of a series circuit of resistors R1 and R2 connected between the other end (terminal on the ignition capacitor side) of the exciter coil 1 and the ground, and an exciter. A thyristor Th1 connected between the other end of the coil 1 and the ground with the cathode facing the ground side, a connection point between the resistors R1 and R2 and the gate of the thyristor Th1, and an anode on the gate side of the thyristor Th1. And a Zener diode ZD1 connected in the direction.

In the present embodiment, a voltage detection circuit that detects the voltage across the exciter coil 1 is configured by a voltage dividing circuit composed of a series circuit of resistors R1 and R2, and is parallel to the exciter coil 1 by a thyristor Th1. The exciter coil 1 is turned on when a trigger signal is given in a state where the exciter coil 1 generates an induced voltage of one polarity (positive polarity in the present embodiment), and the exciter coil 1 has one polarity. An exciter short-circuiting switch is configured that maintains an ON state while generating an induced voltage. The Zener diode ZD1 constitutes an exciter short-circuit switch trigger circuit that gives a trigger signal to the exciter short-circuit switch when the voltage detected by the voltage detection circuit reaches the control value.

In the constant voltage circuit 22 of the present embodiment, the positive voltage V1 induced in the exciter coil 1 is determined by the voltage dividing ratio of the voltage dividing circuit (voltage detection circuit) composed of the resistors R1 and R2 and the zener voltage of the zener diode ZD1. When a certain control value Vs determined by the above is exceeded, the Zener diode ZD1 is turned on and a trigger signal is given to the thyristor Th1. As a result, the thyristor Th1 is turned on and the exciter coil 1 is short-circuited for the remaining period of the half cycle in which the positive voltage is generated. Therefore, the positive voltage V1 induced by the exciter coil 1 is limited to a certain control value Vs or less. Is done.

FIG. 5 shows a state in which the positive voltage V1 induced in the exciter coil 1 is limited to the control value Vs or less by the control operation of the constant voltage circuit 22. In the example shown in FIG. 5, when the constant voltage circuit 22 is not provided, the positive voltage V1 induced in the exciter coil 1 is higher than the control value Vs as shown by the broken line in FIG. However, when the constant voltage circuit 22 is provided, it is limited to the control value Vs or less. FIG. 6 shows the voltage Vc across the ignition capacitor 3 charged by the positive voltage V1 of the exciter coil 1. The voltage at both ends of the ignition capacitor 3 rises to the control value Vs as the positive voltage of the exciter coil 1 rises, and then remains equal to the control value Vs until the ignition timing t1. When an ignition signal is given to the thyristor Thi at the ignition timing, the thyristor Thi is turned on to discharge the charge of the ignition capacitor 3 through the primary coil of the ignition coil, so that the voltage Vc across the ignition capacitor 3 is It falls to zero at the ignition timing t1. Although the waveform after the ignition timing of the voltage across the ignition capacitor 3 actually shows a vibration waveform transiently, the detailed illustration thereof is omitted in FIG.

2 includes a diode Da having an anode connected to one end of the exciter coil 1, a parallel circuit of a resistor Ra and a capacitor Ca having one end connected to the cathode of the diode Da, and a resistor. An NPN transistor TRa whose base is connected to the other end of the parallel circuit of Ra and capacitor Ca through a resistor Rb and whose emitter is grounded, and a resistor connected between the collector of the transistor TRa and the output terminal of the power supply circuit 24 The signal voltage obtained between the collector and emitter of the transistor TRa is input to the ignition control unit 6.

In the waveform shaping circuit 23 shown in FIG. 2, the capacitor Ca is charged between the resistor Rb and the base emitter of the transistor TRa by the first and second negative voltages V21 and V22 generated by the exciter coil 1, The electric charge accumulated in the capacitor Ca is discharged through the resistor Ra with a constant time constant. Therefore, at both ends of the capacitor Ca, as indicated by the wavy line in FIG. 7A, a threshold value indicating a waveform that decreases to a predetermined level after rising to a predetermined level every time the negative voltage V21 rises. A voltage Va is obtained. Since the transistor TRa is turned on when the negative voltages V21 and V22 exceed the threshold voltage Va and the base current flows, the transistor TRa has a collector-emitter as shown in FIG. 7B. In addition, a signal voltage indicating a zero level is obtained only during a period in which the negative voltages V21 and V22 exceed the threshold voltage Va. The microprocessor constituting the ignition control unit 6 recognizes the fall of the signal voltage that occurs when the negative voltage V21 exceeds the threshold voltage Va as the first signal S21, and the negative voltage V22 reduces the voltage Va. The falling edge of the signal voltage that occurs when exceeding is recognized as the second signal S22.

In the present embodiment, the first signal S21 is generated at a crank angle position sufficiently advanced with respect to the top dead center position, and the second signal S22 is generated at a crank angle position set near the top dead center position. To do. The ignition control unit 6 calculates the engine rotation speed from the time ta when the first signal S21 is generated to the time tb when the second signal S22 is generated, and the ignition of the engine is calculated with respect to the calculated rotation speed. Calculate the time. The ignition timing control unit 6 also calculates a time to be measured by the ignition timer in order to detect the already calculated ignition timing (ignition timing calculated before one rotation) when the first signal S21 is generated. Then, the calculated time is set in the ignition timer and the measurement is started. When the measurement of the time when the ignition timer is set is completed, an ignition signal is given to the thyristor 5.

In the above embodiment, the negative voltage generated by the exciter coil 1 is used as a signal for obtaining information on the engine speed and crank angle position. However, the engine speed information and crank angle position information are obtained. The present invention can also be applied to a case where a signal generator for generating a signal for the purpose is provided separately.

FIG. 8 shows an embodiment in which a signal generator for generating a signal including engine rotation information is provided in addition to the exciter coil. In the present embodiment, in addition to the magnet generator provided with the exciter coil 1, a signal generator 30 that generates a pulse signal at a preset crank angle position is provided, and the output of the signal generator 30 is the waveform shaping circuit 23. Is provided to the ignition control unit 6. The signal generator 30 generates a first pulse signal at a position sufficiently advanced from the top dead center position of the piston of the engine, and a second pulse signal at a crank angle position set near the top dead center position. Is generated. The waveform shaping circuit 23 converts the first and second pulse signals generated by the signal generator 30 into signals that can be recognized by the microprocessor and supplies them to the ignition control unit 6. Other configurations are the same as those of the embodiment shown in FIG.

In the above embodiment, as shown in FIG. 3, the rotor is provided with an exciter coil in a magnet generator having a three-pole magnet field. However, as shown in FIG. 8, a signal is generated separately from the exciter coil. When the generator 30 is provided, an exciter coil can be provided in a magnet generator including a rotor having a magnet field having an arbitrary number of poles.

In each of the above embodiments, the ignition timing is controlled by the ignition control unit 6 including a microprocessor. However, an ignition signal for determining the ignition timing of the engine is given to the thyristor (ignition switch) 5 without using the microprocessor. Of course, the present invention can also be applied to a configuration.

In each of the above embodiments, the engine stop switch 10 is inserted between the other end of the exciter coil 1 and the anode of the rectifying diode 4. The engine stop switch 10 charges the ignition capacitor with the output of the exciter coil 1. What is necessary is just to insert in the middle of a charging circuit, and the insertion position of the engine stop switch 10 is not limited to said example.

The present invention is widely applied to an ignition device for a capacitor discharge type internal combustion engine having an engine stop switch that is turned off when the engine is stopped and in which a surge may enter through the engine stop switch in the off state. can do.

1 Exciter Coil 2 Ignition Coil 2a Primary Coil 2b Secondary Coil 3 Ignition Capacitor 4 Rectifier Diode 5 Thyristor (Ignition Switch)
6 Ignition control unit 7 Spark plug 10 Engine stop switch 22 Constant voltage circuit 23 Waveform shaping circuit 24 Power supply circuit

Claims

An exciter coil that induces an alternating voltage in synchronization with the rotation of the internal combustion engine, an ignition coil, an ignition capacitor provided on the primary side of the ignition coil, and an induced voltage of a half cycle of one polarity of the exciter coil A charging circuit that charges the ignition capacitor; and an ignition switch that is turned on at the ignition timing of the internal combustion engine and discharges the charge accumulated in the ignition capacitor through a primary coil of the ignition coil. An ignition device for a capacitor discharge internal combustion engine,
Charging current flowing from the exciter coil to the ignition capacitor when inserted in the middle of the charging circuit and allowing the charging current to flow from the exciter coil to the ignition capacitor when turned off. An engine stop switch for preventing the flow of the electric current, and a constant voltage circuit for controlling the voltage of the one polarity induced in the exciter coil to be equal to or less than the control value by using a preset constant voltage value as a control value When,
An ignition device for a capacitor discharge type internal combustion engine comprising:
One end of the exciter coil is grounded through a current feedback diode with the anode directed to the ground side,
The charging circuit applies the induced voltage of the half cycle of the one polarity of the exciter coil to the ignition capacitor through a rectifying diode having an anode directed to the other end of the exciter coil. Configured to charge,
The ignition device for a capacitor discharge internal combustion engine according to claim 1, wherein the engine stop switch is inserted between the other end of the exciter coil and an anode of the rectifying diode.
The constant voltage circuit is connected in parallel to the exciter coil to detect a voltage at both ends of the exciter coil, and the exciter coil generates an induced voltage of the one polarity. An exciter short-circuiting switch that is turned on when a trigger signal is applied and maintains the on state while the exciter coil generates the induced voltage of the one polarity, and is detected by the voltage detection circuit 2. The ignition apparatus for a capacitor discharge internal combustion engine according to claim 1, further comprising an exciter short-circuit switch trigger circuit that provides a trigger signal to the exciter short-circuit switch when a voltage reaches the control value. 3.
The constant voltage circuit is connected in parallel to the exciter coil to detect a voltage at both ends of the exciter coil, and the exciter coil generates an induced voltage of the one polarity. An exciter short-circuiting switch that is turned on when a trigger signal is applied and maintains the on state while the exciter coil generates the induced voltage of the one polarity, and is detected by the voltage detection circuit The ignition apparatus for a capacitor discharge internal combustion engine according to claim 2, further comprising: an exciter short-circuit switch trigger circuit that gives a trigger signal to the exciter short-circuit switch when the voltage reaches the control value.