JPH0720380Y2 - Ignition device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

[Prior Art] As is well known, in a capacitor discharge type internal combustion engine ignition device, an electric charge of an ignition energy storage capacitor provided on the primary side of an ignition coil and charged by an exciter coil is passed through a discharge control switch. A high voltage for ignition is obtained on the secondary side of the ignition coil by discharging the primary coil of the ignition coil.

As an ignition device of such a system, by switching a boosting semiconductor switch connected in parallel to the exciter coil from a conducting state to a disconnecting state while the exciter coil is generating a positive half-cycle output, There is one in which the ignition energy storage capacitor is charged with a high voltage induced in the exciter coil.

For example, in the invention of JP-A-59-113260, the ignition coil
A transistor that doubles as a discharge control semiconductor switch and a boost semiconductor switch is provided on the next side, and a high voltage is induced in the exciter coil by turning on and off the transistor during the positive half cycle of the output of the exciter coil. Then, the ignition energy storage capacitor is charged by the voltage. Then, during the negative half cycle of the exciter coil, the transistor is turned on to discharge the capacitor to the primary coil of the ignition coil, thereby inducing a high voltage in the secondary coil of the ignition coil and causing a spark in the spark plug. Let

In this type of conventional ignition device, after the transistor is turned on during the positive half cycle of the output of the exciter coil, the transistor is turned off when the voltage across the exciter coil reaches a set level. The capacitor charging voltage was induced at both ends, but with this configuration, the capacitor charging voltage induced in the exciter coil tends to run short when the engine is running at low speed, so sufficient voltage is available at low speed. There is a problem that it is difficult to obtain the ignition performance and the starting rotation speed (the rotation speed at which the ignition operation is started) becomes high.

Therefore, the present applicant first detected the peak of the voltage across the exciter coil and turned off the boosting semiconductor switch connected in parallel to the exciter coil at the detected peak position, whereby the exciter coil We proposed an ignition device that induces a voltage for charging a capacitor.

According to this ignition device, when the short-circuit current flowing through the exciter coil reaches a peak and the voltage across the exciter coil reaches a peak, the energizing current of the exciter coil is cut off to induce a voltage for charging the capacitor. Therefore, the voltage can be made sufficiently high, and the ignition performance at low speed can be improved.

[Problems to be Solved by the Invention] In the previously proposed ignition device, the step-up semiconductor switch having a large current capacity is used because the step-up semiconductor switch is always conducted to the peak position of the voltage across the exciter coil. There was a problem that it was necessary and cost became high. Further, since a large current flows through the boosting semiconductor switch, there is a problem that heat generation increases.

The object of the present invention is to cut off the boosting semiconductor switch at a position where the voltage across the exciter coil reaches a peak from the starting rotation speed to the setting rotation speed, and to cut off the boosting semiconductor switch after the setting rotation speed is exceeded. Finally, the present invention is to provide a capacitor discharge type ignition device for an internal combustion engine in which the ignition energy storage capacitor is charged by the output voltage of the exciter coil without boosting the output voltage of the exciter coil. .

[Means for Solving the Problems] The ignition device of the present invention includes an ignition coil, an exciter coil provided in a magnet generator attached to an internal combustion engine, and an exciter coil provided on a primary side of the ignition coil. An ignition energy storage capacitor charged by an induced voltage, and a discharge control semiconductor switch provided to discharge the electric charge of the ignition energy storage capacitor to the primary coil of the ignition coil when conducting The present invention relates to a capacitor discharge type internal combustion engine ignition device.

In the present invention, a boosting semiconductor switch connected in parallel to an exciter coil, a trigger signal supply circuit for giving a trigger signal to the boosting semiconductor switch by the positive half cycle output of the exciter coil, and a boosting semiconductor switch. The booster semiconductor switch is connected in parallel to the trigger signal input terminals of the switch, and the trigger signal is supplied to the boosting semiconductor switch by providing a conduction signal by the positive half cycle output of the exciter coil to conduct the signal. The trigger signal that bypasses from the bypass switch and the base are connected to one end of the exciter coil through the peak detection capacitor, and the positive half cycle output of the exciter coil supplies the base current through the peak detection capacitor to conduct. Transistor switch and collector-emitter of transistor switch Apply a trigger signal to the trigger signal input terminal of the discharge control semiconductor switch at the position where the phase is behind the peak position of the positive half cycle voltage of the exciter coil and the resistor for adjusting the cutoff position connected in series to the circuit. And a trigger circuit for determining the ignition position to be applied.

The series circuit of the collector-emitter circuit of the transistor switch and the cut-off position adjusting resistor is connected in parallel between the trigger signal input terminals of the trigger signal bypass circuit switching element, and the rotation speed of the internal combustion engine is less than the set value. When the transistor switch is turned on, sometimes the maximum value of the sum of the collector-emitter voltage and the voltage across the cut-off position adjusting resistor is kept below the trigger level of the trigger signal bypass switch. The resistance value of is set.

The discharge control semiconductor switch and the boosting semiconductor switch do not necessarily have to be separately provided, and the discharge control semiconductor switch may also serve as the boosting semiconductor switch.

[Operation] When the engine rotates and the exciter coil generates a positive half-cycle output, the base current is supplied to the transistor switch through the peak detection capacitor, so that the transistor switch becomes conductive. At rotation speeds below the set rotation speed, the voltage across the series circuit of the transistor switch and the cut-off position adjustment resistor is below the trigger level of the trigger signal bypass switch element. The element does not conduct, and a trigger signal is applied to the boosting semiconductor switch. Therefore, the semiconductor switch becomes conductive, and current flows from the exciter coil through the boosting semiconductor switch. When the current flowing through the exciter coil reaches a peak and the voltage across the exciter coil reaches a peak, charging of the peak detection capacitor is terminated and the base current supply to the transistor switch is stopped. From the conductive state to the cutoff state, the conduction signal is given to the switch for the trigger signal side path. As a result, the trigger signal side switch is turned on to prevent the trigger signal from being supplied to the boosting semiconductor switch, so that the semiconductor switch is cut off and the current flowing through the exciter coil is cut off. The interruption of this current induces a high voltage in the exciter coil, which charges the ignition energy storage capacitor.

After the ignition energy storage capacitor is charged, a trigger signal is applied from the ignition position determination trigger circuit to the discharge control semiconductor switch. As a result, the semiconductor switch becomes conductive, and the electric charge of the ignition energy storage capacitor is discharged through the primary coil of the ignition coil. Due to this discharge, a high voltage is generated in the secondary coil of the ignition coil, and the ignition operation is performed.

When the rotation speed of the engine exceeds the set value, the voltage across the series circuit of the transistor switch and the cutoff position adjusting resistor is the trigger signal side path at the position where the phase advances from the position where the voltage across the exciter coil reaches its peak. Because the trigger switch's trigger level is exceeded, the trigger signal bypass switch is turned on and the boost semiconductor switch is turned off at the position where the phase advances from the position where the voltage across the exciter coil reaches its peak. Become. Therefore, as the engine rotation speed increases, the engine in which current flows through the boost semiconductor switch becomes shorter, and eventually the positive half-cycle voltage of the exciter coil rises, and at almost the same time, the trigger signal side switch switches. It becomes conductive and blocks the conduction of the boosting semiconductor switch. In such a state, the output voltage of the exciter coil is not boosted, and the ignition energy storage capacitor is charged by the original output voltage of the exciter coil.

As described above, in the ignition device of the present invention, the boosting semiconductor switch is cut off at the position where the voltage across the exciter coil reaches the peak when the engine speed is below the set value, and the ignition energy is accumulated in the exciter coil. Since the voltage for charging the charging capacitor is induced, the voltage for charging the capacitor induced in the exciter coil at a low speed of the engine can be made sufficiently high to improve the ignition performance at a low speed. Also, when the set speed is exceeded, the cut-off position of the boost semiconductor switch is advanced and finally the ignition energy storage capacitor is charged by the original output of the exciter coil, so the average value of the current flowing through the boost semiconductor switch is increased. Can be made smaller. Therefore, the current capacity required for the semiconductor switch can be reduced as compared with the case where the boosting semiconductor switch is always shut off at the peak position of the voltage across the exciter coil, and an inexpensive semiconductor switch can be used.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention. In FIG. 1, 1 is an ignition coil having a primary coil 1a and a secondary coil 1b, 2 is attached to a cylinder of an engine, and a secondary coil of the ignition coil is provided. It is a connected spark plug. Ignition coil 1
One ends of the secondary coil 1a and the secondary coil 1b are commonly connected.

Reference numeral 3 denotes an ignition energy storage capacitor whose one end is connected to the other end of the primary coil 1a, 4 is a diode whose cathode is connected to one end of the capacitor 3, and 5 is a magnet generator installed in the engine. One end is connected to the anode of the diode 4, and the other end is the primary coil 1a of the ignition coil.
And an exciter coil connected to one end of the secondary coil 1b.

Reference numeral 6 is a thyristor as a discharge control semiconductor switch connected between the other end of the capacitor 3 and one end of the primary coil 1a with the anode facing the capacitor 3 side. The thyristor supplies an ignition position determination trigger signal. A trigger signal VG2 is provided from a circuit (not shown).

Reference numeral 7 denotes a field effect transistor whose drain and source are connected to the anode of the diode 4 and one end of the primary coil 1a, respectively. In this embodiment, this field effect transistor constitutes a boosting semiconductor switch.

The gate of the field effect transistor 7 (trigger signal input terminal) is connected to the cathode of the diode 8, and the resistor 9 is connected between the anode of the diode 8 and one end of the exciter coil 5. Exciter coil 5 →
Trigger signal supply circuit for applying a trigger signal to the field effect transistor (step-up semiconductor switch) by the positive half cycle output of the exciter coil by the circuit of resistor 9 → diode 8 → gate source of field effect transistor 7 → exciter coil 5. Is configured.

Reference numeral 10 is a thyristor connected between the anode of the diode 8 and one end of the primary coil 1a with the annaught facing the diode 8 side. The thyristor 10 constitutes a switch element for a trigger signal bypass, and while the thyristor 10 is conducting, a trigger signal to be supplied to the field effect transistor 7 is bypassed from the transistor 7. ing.

Reference numeral 11 is a diode whose cathode is connected to the gate of the thyristor 10, and 12 is a transistor switch which is an NPN transistor whose emitter is connected to the other end of the exciter coil 5. The collector of the transistor 12 is connected to the anode of the diode 11 through the cutoff position adjusting resistor 13, and the resistor 14 is connected between the anode of the diode 11 and one end of the exciter coil. The base of the transistor 12 is connected to one end of the peak detecting capacitor 15, and the other end of the capacitor 15 is connected to one end of the exciter coil 5 through the resistor 16. A resistor 17 is connected between the base of the transistor 12 and the other end of the exciter coil 5.

Next, the operation of the embodiment of FIG. 1 will be described with reference to the waveform chart of FIG. When the engine rotates, the exciter coil 5 outputs an AC voltage VE as shown in FIG. 2 (A). When the voltage of the positive half cycle of the exciter coil (voltage VE in the arrow direction shown in FIG. 1) rises, the base current is supplied to the transistor 12 through the resistor 16 and the peak detecting capacitor 15. At this time, the output of the exciter coil is also applied to the gate of the thyristor 10 through the anti-14 and the diode 11. But capacitor 15 is the negative half cycle output of the exciter coil (voltage opposite to arrow shown)
Since it is charged with the polarity opposite to that shown in the figure through the resistor 17 at the time, most of the current flows to the capacitor 15 side when the voltage of the positive half cycle of the exciter coil rises and does not flow to the gate side of the thyristor 10. No current flows. Therefore, when the output voltage of the positive half cycle of the exciter coil rises, the transistor 12 becomes thyristor.
Conducting earlier than 10 to prevent conduction of the thyristor 10,
Exciter coil 5 → resistor 9 → diode 8 → between gate and source of field effect transistor 7 → exciter coil 5
The trigger signal VG1 (second
(See Figure B). As a result, the field effect transistor 7 becomes conductive, and a short-circuit current flows from the exciter coil 5 through the field effect transistor 7. When the transistor 12 becomes conductive, a voltage drop occurs between the collector-emitter of the transistor and across the cut-off position adjusting resistor 13, and a voltage VG3, which is the sum of these voltages, is applied between the gate and cathode of the thyristor 10 through the diode 11.
When the engine speed is less than the set value, this voltage VG3
This voltage VG3 does not trigger the thyristor 10 because the maximum value of is not reached to the trigger level of the thyristor 10. When the short-circuit current flowing through the exciter coil 5 reaches a peak and the voltage across the exciter coil reaches a peak, charging of the capacitor 15 ends, so that the base current is no longer supplied to the transistor 12 and the transistor 12 is cut off. . Therefore, a conduction signal is applied to the thyristor 10 from the exciter coil 5 through the resistor 14 and the diode 11, and the thyristor 10 is turned on to bypass the trigger signal supplied to the field effect transistor 7 from the field effect transistor. Therefore, the field effect transistor 7 is turned off, and the exciter coil 5
The current flowing through the field effect transistor 7 is cut off. As a result, a high voltage is induced in the exciter coil 5, and this voltage charges the ignition energy storage capacitor 3 to the polarity shown in the path of the exciter coil 5 → diode 4 → capacitor 3 → primary coil 1a → exciter coil 5. It The voltage of this capacitor 3
It is indicated by a solid line in FIG.

When a negative half-cycle voltage in the direction opposite to the arrow in the figure is induced in the exciter coil 5, the capacitor 15 changes its polarity in the direction opposite to that shown in the figure through the path of capacitor 5 → resistor 16 → exciter coil 5 → resistor 17 → capacitor 15. Be charged. Further, during this time, a trigger signal VG2 (see FIG. 2D) is given to the gate of the thyristor 6 so that the thyristor 6 becomes conductive, and the charge of the capacitor 3 is discharged through the thyristor 6 and the primary coil 1a of the ignition coil. As a result, a high voltage is induced in the secondary coil 1b of the ignition coil, a spark is generated in the ignition plug 2, and the engine is ignited.

As described above, when the rotational speed of the engine is less than the set value, the field effect transistor 7 shuts off at the position where the voltage across the exciter coil reaches its peak, so a sufficiently high voltage is induced in the exciter coil, and the ignition energy accumulation The capacitor 3 is charged to a sufficiently high voltage. Therefore, the ignition performance at low speed of the engine is improved.

When the engine speed reaches the set value, the collector-emitter voltage when the transistor 12 is conducting and the cut-off position adjustment resistor
The peak value of the voltage that is the sum of the voltage across 13 reaches the trigger level of thyristor 10. Therefore, when the rotation speed exceeds the set value, the position where the thyristor 10 is triggered advances ahead of the position where the voltage across the exciter coil reaches its peak, and the position where the field effect transistor 7 cuts off advances. Therefore, the position where the capacitor 3 is charged advances as shown by the broken line in FIG. Finally, almost simultaneously with the output voltage of the positive half cycle of the exciter coil, the thyristor 10 is turned on and the turn-on semiconductor switch is turned off almost at the same time, and the output voltage of the exciter coil is not boosted. In this state, the capacitor 3 is charged by the original output voltage of the exciter coil as shown by the chain line in FIG. 2 (C). Since the output voltage of the exciter coil is sufficiently high when the engine is running at high speed, even if the capacitor 3 is charged by the original output voltage of the exciter coil, the ignition operation will not be hindered.

In the above embodiment, the resistor 17 is connected between the base of the transistor 12 and the other end of the exciter coil 5 in order to charge the peak detecting capacitor 15 to the polarity opposite to that shown in the figure. As described above, the diode 18 whose anode is directed to the exciter coil side is connected between the base of the transistor 12 and the other end of the exciter coil 5, and the capacitor 15
The capacitor 15 may be charged in the reverse direction through the path of the resistor 16, the exciter coil 5, the diode 18, and the capacitor 15.

In the above-described embodiment, the circuit which gives the trigger signal VG2 to the thyristor 6 which constitutes the discharge control switch is configured such that the transistor 12 is activated when the peak detection capacitor 15 is charged.
Any circuit may be used as long as it provides a trigger signal to the semiconductor switch at a position delayed in phase from the position at which the voltage is cut off (the position where the voltage across the exciter coil reaches its peak). For example, the negative half cycle output of the exciter coil 5 may be used to provide a trigger signal for determining the ignition position to the thyristor 6, and the trigger signal may be supplied to the thyristor 6 from a signal source other than the exciter coil. It can also be configured as follows.

In the above-mentioned embodiment, the step-up switch element for interrupting the energizing current of the exciter coil and the discharge switch element for discharging the ignition energy storage capacitor are separately provided, but the discharge control semiconductor switch is It is also possible to double as a boosting semiconductor switch. In this case, for example, in the circuit shown in FIG. 1, the thyristor 6 is removed, the diode 4 is inserted between the drain of the field effect transistor 7 and the resistor 9, and then the gate of the field effect transistor 7 is provided with an ignition position determining trigger signal. Should be provided. In such a configuration, the transistor 7 also serves as a discharge control semiconductor switch for the electric field effect, and the configuration can be simplified.

Although the field effect transistor is used as the boosting semiconductor switch in the above example, other semiconductor switches such as a gate turn-off thyristor and a bipolar type transistor may be used.

Further, in the above example, the thyristor 10 is used as the switch element for the trigger signal side path, but a transistor may be used instead of this thyristor.

[Effects of the Invention] As described above, according to the present invention, the boost semiconductor switch is cut off at the position where the voltage across the exciter coil reaches the peak when the engine speed is below the set value, and the exciter coil is turned on. Since the voltage for charging the ignition energy storage capacitor is induced, there is an advantage that the voltage for charging the capacitor induced in the exciter coil at a low engine speed can be made sufficiently high to improve the ignition performance at a low speed. is there.

When the set speed is exceeded, the cut-off position of the boost semiconductor switch is advanced so that the ignition energy storage capacitor is finally charged by the original output of the exciter coil. It is possible to reduce the current capacity required for the semiconductor switch as compared with the case where the value is reduced and the boosting semiconductor switch is always shut off at the peak position of the voltage across the exciter coil. Can be used.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing voltage waveforms of respective parts of FIG. 1, and FIG. 3 is a circuit diagram showing an essential part of another embodiment of the present invention. Is. 1 ... Ignition coil, 2 ... Ignition plug, 3 ... Ignition energy storage capacitor, 4,8,11,18 ... Diode,
5 ... Exciter coil, 7 ... Field effect transistor (semiconductor switch), 9,13,14,16,20 ...... Resistance, 10 ......
Thyristor (switch element for trigger signal bypass), 12 ...
Transistor, 15 ... Capacitor for peak detection.

Claims (2)

[Scope of utility model registration request] 1. An ignition coil, an exciter coil provided in a magnet generator attached to an internal combustion engine, and an ignition energy storage provided on a primary side of the ignition coil and charged by an induced voltage of the exciter coil. Discharge-type ignition device for an internal combustion engine, comprising: a discharge capacitor; and a discharge control semiconductor switch provided to discharge the charge of the ignition energy storage capacitor to the primary coil of the ignition coil when conducting. A boosting semiconductor switch connected in parallel to the exciter coil, a trigger signal supply circuit for giving a trigger signal to the boosting semiconductor switch with a positive half cycle output of the exciter coil, and the boosting semiconductor The exciter coil is connected in parallel between the trigger signal input terminals of the switch. A trigger signal bypass switch for bypassing the trigger signal supplied to the boosting semiconductor switch when the conduction signal is given by the output of the positive half cycle and is conducted, and the base is for peak detection. A transistor switch connected to one end of the exciter coil through a capacitor, a base current is given through the capacitor for peak detection at the output of the positive half cycle of the exciter coil to conduct, and a collector-emitter circuit of the transistor switch. For providing a trigger signal to the trigger signal input terminal of the discharge control semiconductor switch at a position delayed in phase from the peak position of the positive half cycle voltage of the exciter coil A trigger circuit for determining an ignition position, When the series circuit of the collector-emitter circuit of the switch and the cutoff position adjusting resistor or the trigger signal input terminal of the trigger signal bypass switch element is connected in parallel, and the rotation speed of the internal combustion engine is less than the set value. In addition, the cutoff position adjustment is performed so that the maximum value of the sum of the collector-emitter voltage when the transistor switch is conductive and the voltage across the cutoff position adjustment resistor is suppressed below the trigger level of the trigger signal bypass switch. An ignition device for an internal combustion engine, characterized in that a resistance value of an engine resistance is set. 2. The ignition device for an internal combustion engine according to claim 1, wherein the discharge control semiconductor switch also serves as the boosting semiconductor switch.