JPH041341Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

[Prior Art] As an ignition device for an internal combustion engine, an ignition coil and
an exciter coil disposed in a generator driven by an internal combustion engine; an ignition energy storage capacitor provided on the primary side of the ignition coil and charged to one polarity by the output of one half cycle of the exciter coil; A discharge control thyristor is provided to discharge the charge in the ignition energy storage capacitor through the primary coil of the ignition coil when conductive, and a signal coil generates a one-cycle signal at a predetermined rotation angle position of the internal combustion engine. A capacitor discharge type ignition device is used, which includes a discharge control thyristor trigger circuit that receives the output of the internal combustion engine as an input and triggers a discharge control thyristor at the ignition timing of an internal combustion engine.

In this ignition system, an ignition energy storage capacitor is charged by the output of the exciter coil, and a trigger signal is supplied to the discharge control thyristor by the output of the signal coil at the ignition timing of the engine.
Therefore, the discharge control thyristor conducts and transfers the charge of the ignition energy storage capacitor to one of the ignition coils.
Next, discharge to the coil. This causes a large magnetic flux change in the iron core of the ignition coil, and a high voltage for ignition is induced in the secondary coil of the ignition coil. This high voltage is applied through a high voltage cord to a spark plug attached to a cylinder of the engine, so that a spark is generated in the spark plug and the engine is ignited.

[Problems to be solved by the invention] In the conventional capacitor discharge type internal combustion engine ignition system as described above, when the output of the previous half cycle of the signal coil reaches a predetermined trigger level, the discharge control thyristor is activated. Since the trigger signal is supplied to the engine, the ignition timing of the internal combustion engine becomes almost constant, and the ignition timing (top dead center TDC
The characteristics of the angle α (measured toward the advance side) are as shown in the diagram indicated by the symbol a in FIG. With such characteristics, the rotational speed of the engine increases too much in the high-speed range of the engine, causing problems such as engine seizure.

Furthermore, as shown in Japanese Patent Publication No. 59-79072, Japanese Patent Publication No. 57-32224, and Japanese Patent Publication No. 58-49707, when the rotational speed of the engine exceeds a set value to limit the rotational speed of the engine. An ignition device that delays the ignition timing is known. However, in conventional ignition devices of this type, the retard width was limited to less than the width of one half cycle of the AC signal obtained from the signal source, so there was a problem that the retard width could not be widened.

The purpose of this invention is to suppress the increase in engine rotation speed by rapidly retarding the ignition timing by a sufficient retard width when the engine rotation speed exceeds a set value. An object of the present invention is to provide an ignition device for an internal combustion engine.

[Means for Solving the Problems] As shown in FIG. 1 showing an embodiment of the present invention, an ignition coil IG and an exciter coil arranged in a generator driven by an internal combustion engine
Ignition energy storage capacitor C1 charged to one polarity by the output of one half cycle of Le
When electrical conduction occurs, the charge of the ignition energy storage capacitor C1 is transferred to the primary coil W1 of the ignition coil IG.
a discharge control thyristor S1 provided to cause discharge through the internal combustion engine; and a signal coil Ls that generates a one-cycle signal at a predetermined rotation angle position of the internal combustion engine.
In an ignition system for an internal combustion engine, which is equipped with a thyristor trigger circuit T for discharge control that uses the output of the thyristor S1 as an input to trigger a thyristor S1 at the ignition timing of the internal combustion engine, the ignition timing can be rapidly delayed when the engine is running at high speed. It is something.

Therefore, in the present invention, the trigger circuit T includes a first signal supply circuit that supplies an ignition signal to the thyristor S1 with the output of the previous half cycle of the signal coil Ls, an ignition timing control capacitor C2, and a signal coil Ls. an ignition timing control capacitor charging circuit that charges the ignition timing control capacitor C2 to one polarity with the output of the second half cycle; and a thyristor for discharging control when the charging current of the ignition timing control capacitor exceeds a predetermined value. A second signal supply circuit that gives an ignition signal to S1, a discharge circuit that discharges the charge of the ignition timing control capacitor C2 at a fixed time constant, and a discharge circuit that discharges the output of the previous half cycle of the signal coil Ls when conductive. A signal short circuit thyristor S2 provided to short circuit, a signal short circuit thyristor trigger circuit that supplies an ignition signal to the signal short circuit thyristor S2 when the output of the previous half cycle of the signal coil Ls occurs, and an ignition timing When the voltage across the control capacitor C2 is above a certain level, the cut-off state is maintained to allow the supply of the ignition signal to the signal short circuit thyristor S2, and the ignition timing control capacitor C2
The signal shorting thyristor control switch circuit SC is provided with a signal shorting thyristor control switch circuit SC that becomes conductive when the voltage across the signal shorting thyristor S2 is less than a certain level and bypasses the firing signal to the signal shorting thyristor S2 from the signal shorting thyristor S2.

[Operation of the invention] In the above ignition device, the ignition timing control capacitor C2 is charged to one polarity by the output of the subsequent half cycle of the signal coil Ls. Signal coil Ls
When the output voltage in the subsequent half cycle exceeds the peak value, the charge in the capacitor C2 is discharged at a constant time constant through the discharge circuit.

When the engine speed is less than the set value Ns, the voltage across the ignition timing control capacitor becomes less than a certain level before the signal coil Ls generates the output for the next half cycle, and the signal short-circuit thyristor control switch is activated. conducts. Therefore, when the signal coil generates the output of the previous half cycle, no ignition signal is applied to the signal shorting thyristor, and the signal shorting thyristor is maintained in the cut-off state. Therefore, the firing signal is given to the discharge control thyristor without any trouble through the first signal supply circuit, and when the output of the previous half cycle of the signal coil reaches the predetermined trigger level Vgk at the position of angle θ1, the discharge control thyristor An ignition signal is given to the thyristor to perform an ignition operation.

When the engine rotational speed reaches the set value Ns, the voltage across the ignition timing control capacitor is still above a certain level when the output of the previous half cycle of the signal coil Ls is generated, and the signal short-circuit thyristor control is activated. switch remains in the cut-off state.
Therefore, when the signal coil Ls generates the output of the previous half cycle, a firing signal is applied to the signal shorting thyristor S2, and the signal shorting thyristor becomes conductive. Therefore, the output of the signal coil in the previous half cycle is short-circuited by this thyristor S2, and no ignition signal is given to the discharge control thyristor S1 depending on the output of the next half cycle. The signal coil then generates the output for the next half cycle, and the angle θ2
When the charging current of the ignition timing control capacitor exceeds a predetermined value at the position , an ignition signal is supplied from the second signal supply circuit to the discharge control thyristor S1.
Therefore, as indicated by the symbol b in FIG.
In a region where the rotational speed is less than the set rotational speed Ns, ignition is performed at a position at an angle θ1, and in a region where the rotational speed is greater than or equal to the set rotational speed Ns, ignition is performed at a position at an angle θ2 delayed from the angle θ1. In this way, the present invention rapidly retards the ignition timing when the engine speed exceeds the set value, which prevents the engine speed from increasing excessively and prevents engine seizure. be able to.

[Embodiments] Examples of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 shows an embodiment of the present invention, in which IG is an ignition coil having a primary coil W1 and a secondary coil W2, and P is a secondary coil of the ignition coil IG attached to the engine cylinder. This is a spark plug connected to coil W2. One end of the primary coil W1 of the ignition coil IG is grounded, and the other end is connected to one end of the ignition energy storage capacitor C1. The other end of the capacitor C1 is connected to the anode of a discharge control thyristor S1 whose cathode is grounded, and when the thyristor S1 becomes conductive, the charge in the capacitor C1 is transferred to the thyristor S1 and the primary coil W1.
It is designed to discharge electricity through the

Le is an exciter coil arranged in a magnet generator (not shown) driven by the engine. One end of this exciter coil Le is grounded, and the other end is connected to a capacitor C1 via a diode D1 whose anode is directed toward the exciter coil. Connected to the non-ground terminal. A diode D2 is connected in parallel to both ends of the exciter coil Le with the anode facing the ground side. The exciter coil Le outputs an AC voltage Ve that changes as shown in Figure 2A with respect to the engine rotation angle θ, and in one half cycle of this AC voltage, the capacitor C1 is charged to the polarity shown in the figure through the diode D1. .

Ls is a signal coil installed in a signal generator (not shown), and this signal coil generates one cycle of signal voltage at a predetermined rotation angle position as shown in Figure 2B.
Output Vs. Hereinafter, the signal voltage Vs1 of the first half cycle generated by this signal coil will be referred to as the positive direction signal voltage, and the signal voltage of the half cycle generated later.
Vs2 is called a negative direction signal voltage. One end of the signal coil Ls is connected to the cathode of a diode D2 whose anode is grounded, and the other end is connected to the gate of the thyristor S1 via a diode D3 whose anode faces the signal coil. Signal coil Ls
and diodes D2 and D3 constitute a first signal supply circuit that supplies a firing signal to the thyristor S1 using the positive direction signal voltage Vs1.

Also, a resistor R1 is connected between one end of the signal coil Ls and the ground.
is connected, and the cathode of a diode D4 is connected to the other end of the signal coil Ls. Diode D
One end of a resistor R2 is connected to the anode of No. 4, and an ignition timing control capacitor C2 is connected between the other end of the resistor R2 and ground. In this example, the resistance R
1 and R2 and the diode D4 constitute an ignition timing control capacitor charging circuit that charges the ignition timing control capacitor C2 with the negative direction signal voltage Vs2.

The non-grounded terminal of resistor R1 is a Zener diode whose anode is connected to the gate of thyristor S1.
A second signal supply circuit is connected to the cathode of ZD, and the resistor R1 and Zener diode ZD form a second signal supply circuit that provides an ignition signal to the discharge control thyristor when the charging current of the ignition timing control capacitor exceeds a certain value. has been done.

A resistor R3 forming a discharge circuit is connected to both ends of the ignition timing control capacitor C2, so that the charge in the capacitor C2 is discharged at a constant time constant through the resistor R3. In the illustrated example, the resistor R3 is composed of a variable resistor, and by adjusting its resistance value, the discharge time constant of the capacitor C2 can be adjusted as appropriate.

The gate of a field effect transistor Ft whose source is grounded is connected to the non-grounded terminal of the capacitor C2, and the drain of the field effect transistor Ft is connected to the base of a PNP transistor Tr whose collector is grounded.

S2 is a signal shorting thyristor whose cathode is grounded, and the anode of this thyristor is connected to the signal coil.
It is connected to the connection point between Ls and the cathode of the diode D4, so that when the forward signal voltage Vs1 is generated, a forward voltage is applied between the anode and cathode of the thyristor S2. The anode of a diode D5 is connected to the anode of the thyristor S2, and a resistor R4 is connected between the cathode of the diode D5 and the gate of the thyristor S2.
A resistor R5 is connected between the two gate cathodes. A resistor R6 and a capacitor C3 are connected in parallel between the gate and cathode of the thyristor S2.

In this embodiment, when the positive direction signal voltage Vs1 is generated from the signal coil Ls by the diode D5 and the resistors R4 and R5, the signal shorting thyristor S
A signal short-circuiting thyristor trigger circuit is configured to supply an ignition signal to 2. In addition, the field effect transistor Ft and the transistor Tr constitute a signal short circuit thyristor control switch circuit SC.
In this switch circuit SC, when the voltage Vc2 across the ignition timing control capacitor C2 is above a certain level, the transistor Tr maintains the cut-off state and allows the supply of the ignition signal to the signal shorting thyristor S2, thereby starting the ignition timing control capacitor C2. When the voltage Vc2 across the timing control capacitor C2 is less than a certain level, it becomes conductive and the firing signal to the signal shorting thyristor S2 is bypassed from the signal shorting thyristor.

Signal coil Ls, diode D2 to D5,
Thyristor S2 for signal short circuit, capacitor C2, C
3. Resistors R1 to R6, field effect transistors
Ft and the transistor Tr constitute a discharge control thyristor trigger circuit T that receives the output of the signal coil Ls as an input and triggers the discharge control thyristor S1 at the ignition timing of the internal combustion engine.

In the above embodiment, the ignition timing control capacitor C2 is charged to one polarity by the negative signal voltage Vs2 generated by the signal coil Ls, and when the negative signal voltage Vs2 of the signal coil Ls exceeds the peak value, the capacitor C2 is discharged through resistor R3 with a constant time constant. Therefore, the terminal voltage Vc2 of the capacitor C2 changes as shown in FIG. 2C with respect to the engine rotation angle θ. Furthermore, Figure 2C
In the equation, a indicates the voltage Vs2 when the engine rotational speed is less than the set value Ns, and b indicates the voltage Vc2 when the engine rotational speed is equal to or higher than the set value Ns.

When the engine speed is less than the set value Ns, the voltage Vc2 (absolute value) across the ignition timing control capacitor C2 becomes less than a certain level Vf before the positive direction signal voltage Vs1 is generated, so the field effect transistor Ft becomes conductive, and the transistor Tr becomes conductive (switch SC becomes conductive). Therefore, when the signal coil generates the positive direction signal voltage Vs1, no ignition signal is given to the signal shorting thyristor S2, and the signal shorting thyristor S2 is maintained in the cut-off state. Therefore, the thyristor S for discharge control
1 is given an ignition signal through diodes D2 and D3 (first signal supply circuit), and the positive direction signal voltage Vs1 reaches the trigger level Vgk at the position of angle θ1.
When this is reached, an ignition signal is given to the discharge control thyristor S1. As a result, the capacitor C1 is discharged, and an ignition operation is performed.

When the rotational speed of the engine reaches the set value Ns, the voltage Vc2 (absolute value) across the ignition timing control capacitor C2 still remains when the positive direction signal voltage Vs1 is generated.
has reached a certain level Vf or higher, and the signal short circuit thyristor control switch maintains the cutoff state. Therefore, the signal coil Ls has a positive direction signal voltage.
Thyristor S2 for signal short circuit when Vs1 is generated
An ignition signal is applied to the signal short-circuiting thyristor S2, which becomes conductive. Therefore, the positive direction signal voltage Vs1
is short-circuited by the thyristor S2, and the ignition signal is no longer given to the discharge control thyristor by this positive direction signal voltage Vs1. Then the signal coil
Ls generates a negative direction signal voltage Vs2, and when the charging current of the ignition timing control capacitor C2 exceeds a predetermined value at the angle θ2 position and the voltage across the resistor R1 exceeds the Zener voltage Vz of the Zener diode ZD, the discharge occurs. An ignition signal is supplied to the control thyristor S1. As a result, the thyristor S1 becomes conductive, the capacitor C1 is discharged, and an ignition operation is performed.

Therefore, as indicated by the symbol b in Fig. 3, ignition is performed at the angle θ1 in the region below the set rotation speed Ns, and when the set rotation speed Ns is reached, the ignition timing is rapidly retarded. As a result, ignition is performed at an angle θ2 that is delayed from the angle θ1.
By setting the angle from angle θ1 to angle θ2 (retard angle width) to a sufficient size, it is possible to reliably prevent the engine from rotating at a rotation speed higher than the rotation speed, thereby preventing engine seizure. can be prevented. Ignition timing θ1 in the region below the set rotation speed and ignition timing θ when the set rotation speed is reached
2 is determined by the output waveform of the signal coil, the generation interval of positive and negative half-cycle signals, and the trigger levels Vgk and Vz. Therefore, the retard width can be adjusted by adjusting the trigger levels Vgk and Vz and the magnetic pole spacing of the signal generator. can be set appropriately, and the optimum retard width can be obtained according to the characteristics of the engine.

[Effects of the invention] As described above, according to the invention, the ignition timing can be rapidly delayed when the engine rotational speed exceeds the set value, thereby preventing the engine rotational speed from increasing excessively. This has the advantage of preventing engine seizure. Furthermore, according to the present invention, in the region below the set rotation speed, the ignition timing is set at the position where the output of the previous half cycle of the signal coil reaches a predetermined level, and in the region above the set rotation speed, the ignition timing is the position of the output of the signal coil in the next half cycle. Since the ignition timing is set at the point where the output reaches a predetermined level, the retard width can be adjusted over a wide range by adjusting the magnetic pole spacing of the signal generator and adjusting the output phase of the positive and negative half cycles of the signal coil. This has the advantage that the optimum retardation width can be set to limit the rotational speed according to the characteristics of the engine.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram showing signal waveforms of each part in Fig. 1, and Fig. 3 shows the ignition characteristics of the device of the present invention and the ignition characteristics of a conventional ignition device. FIG. IG...Ignition coil, Le...Exciter coil,
Ls...Signal coil, P...Spark plug, C1...
...Ignition energy storage capacitor, C2...Ignition timing control capacitor, D1-D5...Diode, ZD...Zener diode, R1-R6
...Resistance, Ft...Field effect transistor, Tr...
...Transistor, SC...Switch circuit for thyristor control for signal short circuit, T...Thyristor trigger circuit for discharge control.

Claims (1)

[Claim for Utility Model Registration] An ignition coil and an ignition energy storage capacitor that is charged to one polarity by the output of one half cycle of an exciter coil disposed in a generator driven by an internal combustion engine are electrically connected. a discharge control thyristor provided to discharge the charge of the ignition energy storage capacitor through the primary coil of the ignition coil; and a signal coil that generates a one-cycle signal at a predetermined rotation angle position of the internal combustion engine. and a thyristor trigger circuit for discharge control that triggers the thyristor at the ignition timing of the internal combustion engine by inputting the output of the signal coil, wherein the trigger circuit receives the output of the previous half cycle of the signal coil and triggers the thyristor at the ignition timing of the internal combustion engine. a first signal supply circuit that supplies an ignition signal to the thyristor; an ignition timing control capacitor; and ignition timing control that charges the ignition timing control capacitor to one polarity with the output of the subsequent half cycle of the signal coil. a second signal supply circuit that provides an ignition signal to the discharge control thyristor when the charging current of the ignition timing control capacitor exceeds a certain value; a discharge circuit for discharging at a constant time constant; a signal shorting thyristor provided to short-circuit the output of the previous half cycle of the signal coil when conductive; and the output of the previous half cycle of the signal coil. a signal short circuit thyristor trigger circuit that supplies an ignition signal to the signal short circuit thyristor when the signal short circuit occurs; Allowing the supply of an ignition signal to the thyristor, conducts when the voltage across the ignition timing control capacitor is less than a certain level, and bypasses the ignition signal to the signal shorting thyristor from the signal shorting thyristor. An ignition device for an internal combustion engine, comprising a switch circuit for controlling a thyristor for signal shorting.